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  • Public defence: 2024-10-17 09:00 Belladonna, Hus 511, LinköpingOrder onlineBuy this publication >>
    Ledin, Håkan
    Linköping University, Department of Biomedical and Clinical Sciences, Division of Surgery, Orthopedics and Oncology. Linköping University, Faculty of Medicine and Health Sciences.
    Fixation of total knee replacement: Effects of bone specific drugs and tourniquet use2024Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    Knee and hip replacements are among the most common surgical procedures in today's healthcare. Joint replacement is effective for treating pain and disability from osteoarthritis. Although most patients are satisfied with their operation, two percent are reoperated within two years. A common cause for reoperation is aseptic loosening. Almost three thousand reoperations of hip and knee prostheses are performed annually in Sweden. The most common reason for a reoperation is aseptic loosening. Such interventions are technically difficult, associated with poor patient satisfaction, greater risks of complications, and involving larger costs for society. 

    The primary mechanism of aseptic loosening is debated, but it has been convincingly shown that a well-fixed implant in the first two years after the operation is important for the long-term survival of the prosthesis. Even well-integrated prostheses can loosen over time if the fixation is impaired. 

    The use of a tourniquet, to obtain a bloodless field in knee replacement surgery is very common but can have serious side effects. The bloodless field during the operation theoretically creates a blood-free bone bed for cementation, which might lead to better fixation because the bone cement can penetrate into the trabecular bone structure. In this thesis, we show that surgery performed with tourniquet did not improve fixation but may cause more postoperative pain and decreased range of motion (Study I). 

    We also explored using bone specific drugs to improve fixation: parathyroid hormone (Study II) stimulates bone-forming cells (osteoblasts), and denosumab (Study III) inhibits bone-resorbing cells (osteoclasts). We found that patients who received parathyroid hormone after total knee replacement did not experience improved fixation, whereas those treated with denosumab showed enhanced fixation. Similar to denosumab, bisphosphonates—widely used in the treatment of osteoporosis—also inhibit osteoclast function. 

    Study IV is a protocol publication of an ongoing, double-blinded, randomised controlled clinical trial involving 1000 patients. We are investigating whether a single intravenous dose of bisphosphonate given immediately after surgery improves prosthesis fixation and patient satisfaction after primary total hip and knee joint replacement. 

    List of papers
    1. Tourniquet use in total knee replacement does not improve fixation, but appears to reduce final range of motion A randomized RSA study involving 50 patients
    Open this publication in new window or tab >>Tourniquet use in total knee replacement does not improve fixation, but appears to reduce final range of motion A randomized RSA study involving 50 patients
    2012 (English)In: Acta Orthopaedica, ISSN 1745-3674, E-ISSN 1745-3682, Vol. 83, no 5, p. 499-503Article in journal (Refereed) Published
    Abstract [en]

    Background and purpose Although a tourniquet may reduce bleeding during total knee replacement (TKA), and thereby possibly improve fixation, it might also cause complications. Migration as measured by radiostereometric analysis (RSA) can predict future loosening. We investigated whether the use of a tourniquet influences prosthesis fixation measured with RSA. This has not been investigated previously to our knowledge. less thanbrgreater than less thanbrgreater thanMethods 50 patients with osteoarthritis of the knee were randomized to cemented TKA with or without tourniquet. RSA was performed postoperatively and at 6 months, 1 year, and 2 years. Pain during hospital stay was registered with a visual analog scale (VAS) and morphine consumption was measured. Overt bleeding and blood transfusions were registered, and total bleeding was estimated by the hemoglobin dilution method. Range of motion was measured up to 2 years. less thanbrgreater than less thanbrgreater thanResults RSA maximal total point motion (MTPM) differed by 0.01 mm (95% CI-0.13 to 0.15). Patients in the tourniquet group had less overt bleeding (317 mL vs. 615 mL), but the total bleeding estimated by hemoglobin dilution at day 4 was only slightly less (1,184 mL vs. 1,236 mL) with a mean difference of -54 mL (95% CI-256 to 152). Pain VAS measurements were lower in the non-tourniquet group (p = 0.01). There was no significant difference in morphine consumption. Range of motion was 11 more in the non-tourniquet group (p = 0.001 at 2 years). less thanbrgreater than less thanbrgreater thanInterpretation Tourniquet use did not improve fixation but it may cause more postoperative pain and less range of motion.

    Place, publisher, year, edition, pages
    Informa Healthcare, 2012
    National Category
    Medical and Health Sciences
    Identifiers
    urn:nbn:se:liu:diva-85605 (URN)10.3109/17453674.2012.727078 (DOI)000310015700011 ()
    Note

    Funding Agencies|Swedish Research Council|VR - 2009-6725|

    Available from: 2012-11-26 Created: 2012-11-26 Last updated: 2024-09-16
    2. No effect of teriparatide on migration in total knee replacement A randomized controlled trial involving 50 patients
    Open this publication in new window or tab >>No effect of teriparatide on migration in total knee replacement A randomized controlled trial involving 50 patients
    2017 (English)In: Acta Orthopaedica, ISSN 1745-3674, E-ISSN 1745-3682, Vol. 88, no 3, p. 259-262Article in journal (Refereed) Published
    Abstract [en]

    Background and purpose - Aseptic loosening is a main cause of late revision in total knee replacement (TKR). Teriparatide, a recombinant parathyroid hormone (PTH), stimulates osteoblasts and has been suggested to improve cancellous bone healing in humans. This might also be relevant for prosthesis fixation. We used radiostereometric analysis (RSA) to investigate whether teriparatide influences prosthesis fixation. Early migration as measured by RSA can predict future loosening. Patients and methods - In a randomized controlled trial with blind evaluation, 50 patients with osteoarthritis of the knee were allocated to a teriparatide treatment group (Forsteo, 20 mu g daily for 2 months postoperatively) or to an untreated control group. RSA was performed postoperatively and at 6 months, 12 months, and 24 months. The primary effect variable was maximal total point motion (MTPM) from 12 to 24 months. Results - Median maximal total point motion from 12 to 24 months was similar in the 2 groups (teriparatide: 0.14 mm, 10% and 90% percentiles: 0.08 and 0.24; control: 0.13 mm, 10% and 90% percentiles: 0.09 and 0.21). [Authors: this is perhaps better than using "10th" and "90th", which looks ugly in print. /language editor] The 95% confidence interval for the difference between group means was -0.03 to 0.04 mm, indicating that no difference occurred. Interpretation - We found no effect of teriparatide on migration in total knee replacement. Other trials using the same dosing have suggested a positive effect of teriparatide on human cancellous fracture healing. Thus, the lack of effect on migration may have been due to something other than the dose. In a similar study in this issue of Acta Orthopaedica, we found that migration could be reduced with denosumab (Ledin etal. 2017). The difference in response between the anabolic substance teriparatide and the antiresorptive denosumab suggests that resorption has a more important role during the postoperative course than any deficit in bone formation.

    Place, publisher, year, edition, pages
    TAYLOR & FRANCIS LTD, 2017
    National Category
    Orthopaedics
    Identifiers
    urn:nbn:se:liu:diva-137867 (URN)10.1080/17453674.2017.1300745 (DOI)000400742500004 ()28287044 (PubMedID)
    Note

    Funding Agencies|Swedish Research Council [VR 02031-47-5]; Medical Research Council of Southeast Sweden [FORSS-37511]; Linkoping University

    Available from: 2017-06-07 Created: 2017-06-07 Last updated: 2024-09-16
    3. Denosumab reduces early migration in total knee replacement A randomized controlled trial involving 50 patients
    Open this publication in new window or tab >>Denosumab reduces early migration in total knee replacement A randomized controlled trial involving 50 patients
    2017 (English)In: Acta Orthopaedica, ISSN 1745-3674, E-ISSN 1745-3682, Vol. 88, no 3, p. 255-258Article in journal (Refereed) Published
    Abstract [en]

    Background and purpose - Aseptic loosening is a main cause of late revision in total knee replacement (TKR). Migration of implants as measured by radiostereometric analysis (RSA) can predict future loosening. This migration is associated with bone resorption. Denosumab is a human monoclonal antibody that binds to receptors on osteoclast precursors and osteoclasts. This prevents osteoclast formation, resulting in less bone resorption in cortical and trabecular bone. We investigated whether denosumab can reduce migration of TKR, as measured with RSA. Patients and methods - In this 2-center, randomized, double-blind placebo-controlled trial, 50 patients with osteoarthritis of the knee were treated with an injection of either denosumab (60 mg) or placebo 1 day after knee replacement surgery and again after 6 months. RSA was performed postoperatively and after 6, 12, and 24 months. The primary effect variable was RSA maximal total point motion (MTPM) after 12 months. We also measured other RSA variables and the knee osteoarthritis outcome score (KOOS). Results - The primary effect variable, MTPM after 12 months, showed that migration in the denosumab group was statistically significantly less than in the controls. Denosumab MTPM 12 months was reduced by one-third (denosumab: median 0.24 mm, 10% and 90% percentiles: 0.15 and 0.41; placebo: median 0.36 mm, 10% and 90% percentiles: 0.20 and 0.62). The secondary MTPM variables (6 and 24 months) also showed a statistically significant reduction in migration. There was no significant difference in MTPM for the period 12-24 months. KOOS sub-variables were similiar between denosumab and placebo after 12 and 24 months. Interpretation - Denosumab reduces early migration in total knee replacement, as in previous trials using bisphosphonates. As migration is related to the risk of late loosening, denosumab may be beneficial for long-term results.

    Place, publisher, year, edition, pages
    TAYLOR & FRANCIS LTD, 2017
    National Category
    Orthopaedics
    Identifiers
    urn:nbn:se:liu:diva-137866 (URN)10.1080/17453674.2017.1300746 (DOI)000400742500003 ()28287004 (PubMedID)
    Note

    Funding Agencies|Eli Lilly Corp; Amgen

    Available from: 2017-06-07 Created: 2017-06-07 Last updated: 2024-09-16
    4. Single postoperative infusion of zoledronic acid to improve patient-reported outcome after hip or knee replacement: study protocol for a randomised, controlled, double-blinded clinical trial
    Open this publication in new window or tab >>Single postoperative infusion of zoledronic acid to improve patient-reported outcome after hip or knee replacement: study protocol for a randomised, controlled, double-blinded clinical trial
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    2020 (English)In: BMJ Open, E-ISSN 2044-6055, Vol. 10, no 9, article id e040985Article in journal (Refereed) Published
    Abstract [en]

    Introduction In Sweden, roughly 3000 patients are reoperated each year due to pain and loss of function related to a loosened hip or knee prosthesis. These reoperations are strenuous for the patient, technically demanding and costly for the healthcare system. Any such reoperation that can be prevented would be of great benefit. Bisphosphonates are drugs that inhibit osteoclast function. Several clinical trials suggest that bisphosphonates lead to improved implant fixation and one small study even indicates better functional outcome. Furthermore, in epidemiological studies, bisphosphonates have been shown to decrease the rate of revision for aseptic loosening by half. Thus, there are several indirect indications that bisphosphonates could improve patient-reported outcome, but no firm evidence. Methods and analysis This is a pragmatic randomised, placebo-controlled, double-blinded, academic clinical trial of a single postoperative dose of zoledronic acid, in patients younger than 80 years undergoing primary total hip or knee replacement for osteoarthritis. Participants will be recruited from two orthopaedic departments. All surgeries will be performed, and study drugs given at Motala Hospital, Sweden. The primary endpoint is to investigate between-group differences in the Hip dysfunction and Osteoarthritis Outcome Score and the Knee injury and Osteoarthritis Outcome Score at 3-year follow-up. Secondary outcomes will be investigated at 1 year, 3 years and 6 years, and stratified for hip and knee implants. These secondary endpoints are supportive, exploratory or explanatory. A total of 1000 patients will be included in the study. Ethics and dissemination The study has been approved by the Regional Ethical Review Board in Linkoping (DNR 2015/286-31). The study will be reported in accordance with the Consolidated Standards of Reporting Trials statement for pharmacological trials. The results will be submitted for publication in peer-reviewed academic journals and disseminated to patient organisations and the media.

    Place, publisher, year, edition, pages
    BMJ PUBLISHING GROUP, 2020
    Keywords
    adult orthopaedics; hip; knee
    National Category
    Orthopaedics
    Identifiers
    urn:nbn:se:liu:diva-170948 (URN)10.1136/bmjopen-2020-040985 (DOI)000578438500005 ()32998932 (PubMedID)
    Note

    Funding Agencies|Swedish Research CouncilSwedish Research Council [2014-07284]; ALF-grants from Region Ostergotland, Sweden

    Available from: 2020-11-01 Created: 2020-11-01 Last updated: 2024-09-16
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  • Public defence: 2024-10-18 13:00 Key 1, Key huset, Linköping
    Lien, Jakob
    Linköping University, Department of Culture and Society, Division of Language, Culture and Interaction. Linköping University, Faculty of Arts and Sciences.
    Maskintankar: Sammankopplingar av människan och det digitala i svensk litteratur 1965–19802024Doctoral thesis, monograph (Other academic)
    Abstract [en]

    Machine Thoughts explores how Swedish literature approached, explored, experimented with, and portrayed the post-war digital transformation. The period from 1965 to 1980 was characterized by accelerating technological development. The digital transitioned from being a matter for a few technically experts to increasingly permeating the entire society. In parallel with the introduction of digital media, and strongly influenced by each other, cybernetics and its elusive concept of information were introduced, further contributed to transforming the understanding of ourselves by challenging traditional notions of the body, identity, and subjectivity. Through analyses of science fiction and experimental prose, as well as more traditional novels and visually and linguistically exploratory poetry, the dissertation demonstrate how literature both shaped and was shaped by these circumstances. Through aesthetically explorative and playful forms, but also through more realistic expressions, literature posed questions about humans and machines, language and code, and the natural and the artificial. The study shows that there was a technically and aesthetically conscious way of relating to questions about the digital among institutions and authors long before more contemporary notions of digital literature, written for and read on screens, had been established. From media-ecological and media-archaeological perspectives, the dissertation sketches a history that points towards and puts our contemporary situation in perspective, showing how ideas related to the digital have been present for a long time and continue to inform and influence today’s literary and cultural discourses.

    In the first chapter of the dissertation, questions of language, code, and the changing conditions of communication are addressed by discussing how early experiments with algorithmic poetry reshaped and expanded the forms of literary writing. The second chapter examines the relationship between, and potential dissolution of, human subjects and technical objects, and between the natural and the artificial, considering the parallel emergence of cybernetics with digital technology. The third chapter investigates the hardware and infrastructure of the digital with a focus on the (changing) material conditions that underpinned the media development during the period 1965–1980. In a concluding chapter, the analytical points of the dissertation are summarized by turning to some contemporary literary and artistic examples that, in various ways, thematize or utilize AI in their works.

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  • Public defence: 2024-10-24 09:15 A2, A-building, LinköpingOrder onlineBuy this publication >>
    Linder, Clara
    Linköping University, Department of Physics, Chemistry and Biology, Nanostructured Materials. Linköping University, Faculty of Science & Engineering.
    Tailoring multicomponent thin films for combined corrosion resistance and oxygen electrocatalysis2024Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    Catalytic water recombination and electrolysis play an important role in the transition towards green, renewable, fossil-free energy production. The processes are kinetically limited by the oxygen reactions, i.e. Oxygen Reduction Reaction (ORR) and Oxygen Evolution Reaction (OER), thus these reactions have higher demand for electrocatalysts than the hydrogen reactions. There is a particular focus on finding abundant and cheap alternatives to noble metal oxygen reaction catalysts used today. Alternatives such as Co, Ni, Fe and Mn oxides, are promising candidates and in some cases found to be bifunctional oxygen catalysts, i.e. that they are active towards both reactions. In this thesis, these catalytically active elements have been alloyed together in multicomponent, high entropy thin films deposited by magnetron sputtering. 

    Anodization profiles have been designed to activate the thin films by tuning the surface oxidation states. This considerably enhanced the catalytic activity towards both ORR and OER. For pure Co films, the electrochemical modification resulted in the formation of Co3O4 platelets with the two Co cations as active sites. In the CoCrFeNi films, an enrichment of the surface in Co and Ni cations was observed after anodization. In addition, the presence of Fe and its synergy with the active sites was identified as key to the catalytic activity.   

    Another critical aspect was the film structure. Here the substrate bias was varied which affected the ion bombardment during the deposition. This changed the typical columnar structure of the films towards denser and more faceted films with larger grains. Both the columnar and denser structure were found catalytically active, in particular towards OER. The denser films had better long-term stability towards OER compared to the columnar films.   To understand in depth the catalytic mechanism for the CoCrFeNi and MnCrFeNi films, the ORR pathway was also investigated. It was first observed that replacing Co with Mn reduced the overpotentials for both ORR and OER. The as-deposited films follow a (2+1) electrons pathway whereas the anodized films shifted towards either 4 or 2 electrons pathway. This was also correlated to the active sites and film structure. 

    Furthermore, the films synthesized in this thesis have also a high corrosion resistance in alkaline and neutral chloride containing environments. The films presented a passive behavior due to the formation of a protective oxide layer. Once again, film composition and film structure, in particular grain size affected the corrosion performance. The presence of defects due to lattice distortion of CoCrFeNi significantly improved the corrosion resistance in NaCl. The smaller grain size of the films led to a higher corrosion resistance in KOH. Additions of Mo to CoCrFeNi significantly improve the corrosion resistance in acidic environments at elevated temperature. This was attributed to the suppression of secondary phases and presence of Mo in the passive films.  

    In summary, this thesis focuses on tuning thin film composition, structure, and post-deposition oxidation to improve both the catalytic activity towards oxygen reactions and the corrosion resistance in environments relevant for cata-lytic water recombination and electrolysis. The focus on abundant and cheap elements for material synthesis aims to contribute to the development of non-noble metal oxygen electrocatalysts for potential use in future green energy technologies.   

    List of papers
    1. Cobalt thin films as water-recombination electrocatalysts
    Open this publication in new window or tab >>Cobalt thin films as water-recombination electrocatalysts
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    2020 (English)In: Surface & Coatings Technology, ISSN 0257-8972, E-ISSN 1879-3347, Vol. 404, article id 126643Article in journal (Refereed) Published
    Abstract [en]

    Catalysts and electmcatalysts are crucial for energy production and storage. To develop cost-efficient systems taking advantage of functionalized surfaces, the catalysts can be synthesized as nanomaterials or thin films. In this work, cobalt thin films were deposited on low-alloyed steel using magnetron sputtering. The films are uniform with a smooth surface and a thickness of similar to 400 nm. The films were electrochemically oxidized via anodization to a mix of cobalt oxides, one of them being Co3O4, at room temperature in an alkaline solution. The electrocatalytic performances of the anodized films were evaluated in 1 M KOH electrolyte saturated with oxygen. Cathodic currents in -0.5 mA/cm(2) range, corresponding to oxygen reduction reaction (ORR) activity, were measured with cyclic voltammetry. The catalytic activity of the films was evaluated as a function of time. The anodized Co coating exhibited three times higher activity than the steel substrate. The kinetics for the ORR were evaluated through Tafel plots and a slope of 226 mV/decade was found. Post-ORR characterization of the films revealed hexagonal plate-like oxide particles on the surface. After 50 cyclic voltammograms, the film was further oxidized, indicating that the ORR activity also affects the overall surface state of the film. This study demonstrates that thin films, after electrochemical modification, can be electrocatalysts for the oxygen reduction reaction and potentially used for applications in energy production and storage.

    Place, publisher, year, edition, pages
    ELSEVIER SCIENCE SA, 2020
    Keywords
    Cobalt thin film; Anodization; Cobalt oxide; Electrocatalyst; Oxygen reduction reaction; Water recombination
    National Category
    Inorganic Chemistry
    Identifiers
    urn:nbn:se:liu:diva-172974 (URN)10.1016/j.surfcoat.2020.126643 (DOI)000597889400065 ()
    Note

    Funding Agencies|competence center FunMat-II - Swedish Agency for Innovation Systems (VINNOVA)Vinnova [2016-05156]; VINNOVAVinnova [2018-04291]; Swedish Government Strategic Research Area in Materials Science on Functional Materials at Linkoping University (Faculty Grant SFO-Mat-LiU) [2009 00971]

    Available from: 2021-01-26 Created: 2021-01-26 Last updated: 2024-10-01
    2. Corrosion Resistance and Catalytic Activity toward the Oxygen Reduction Reaction of CoCrFexNi (0 < x < 0.7) Thin Films
    Open this publication in new window or tab >>Corrosion Resistance and Catalytic Activity toward the Oxygen Reduction Reaction of CoCrFexNi (0 < x < 0.7) Thin Films
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    2022 (English)In: ACS Applied Energy Materials, E-ISSN 2574-0962, Vol. 5, no 9, p. 10838-10848Article in journal (Refereed) Published
    Abstract [en]

    Corrosion resistance and catalytic activity toward the oxygen reduction reaction (ORR) in an alkaline environment are two key properties for water recombination applications. In this work, CoCrFexNi (0 &lt;= x &lt;= 0.7) thin films were deposited by magnetron sputtering on polished steel substrates. The native passive layer was 2-4 nm thick and coherent to the columnar grains determined by transmission electron microscopy. The effect of Fe on the corrosion properties in 0.1 M NaCl and 1 M KOH and the catalytic activity of the films toward ORR were investigated. Electrochemical impedance spectroscopy and potentiodynamic polarization measurements indicate that CoCrFe0.7Ni and CoCrFe0.3Ni have the highest corrosion resistance of the studied films in NaCl and KOH, respectively. The high corrosion resistance of the CoCrFe0.7Ni film in NaCl was attributed to the smaller overall grain size, which leads to a more homogeneous film with a stronger passive layer. For CoCrFe0.3Ni in KOH, it was attributed to a lower Fe dissolution into the electrolyte and the build-up of a thick and protective hydroxide layer. Scanning Kelvin probe force microscopy showed no potential differences globally in any of the films, but locally, a potential gradient between the top of the columns and grain boundaries was observed. Corrosion of the films was likely initiated at the top of the columns where the potential was lowest. It was concluded that Fe is essential for the electrochemical activation of the surfaces and the catalytic activity toward ORR in an alkaline medium. The highest catalytic activity was recorded for high Fe-content films (x &gt;= 0.5) and was attributed to the formation of platelet-like oxide particles on the film surface upon anodization. The study showed that the combination of corrosion resistance and catalytic activity toward ORR is possible for CoCrFexNi, making this material system a suitable candidate for water recombination in an alkaline environment.

    Place, publisher, year, edition, pages
    American Chemical Society (ACS), 2022
    Keywords
    magnetron sputtering; multicomponent thin film; corrosion; ORR; water recombination; electrocatalysis
    National Category
    Other Chemistry Topics
    Identifiers
    urn:nbn:se:liu:diva-188445 (URN)10.1021/acsaem.2c01499 (DOI)000848746100001 ()
    Note

    Funding Agencies|Swedish Agency for Innovation Systems (VINNOVA) [2016-05156, 2019-04881]; Swedish Government Strategic Research Area in Materials Science on Functional Materials at the Linkoping University [2009 00971]; Swedish Research Council [2021-03826]

    Available from: 2022-09-14 Created: 2022-09-14 Last updated: 2024-10-01Bibliographically approved
    3. Effect of Mo content on the corrosion resistance of (CoCrFeNi)1−xMox thin films in sulfuric acid
    Open this publication in new window or tab >>Effect of Mo content on the corrosion resistance of (CoCrFeNi)1−xMox thin films in sulfuric acid
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    2024 (English)In: Thin Solid Films, ISSN 0040-6090, E-ISSN 1879-2731, Vol. 790, article id 140220Article in journal (Refereed) Published
    Abstract [en]

    (CoCrFeNi)1−xMox thin films with various Mo content (0–10 at.%) were grown by magnetron sputtering on a stainless steel substrate. The films with 0–2 at.% presented two crystal structures: one FCC phase and one sigma phase, while films with higher Mo content only had the FCC structure. All films have a (111) texture and follow the topography of the substrate. The corrosion resistance of the films was evaluated in 0.05 M H2SO4 at room temperature and at 80 °C. It was observed that the corrosion current densities considerably decreased for Mo > 2 at%, and that the current densities were higher at the elevated temperature. Scanning Kelvin Probe Force Microscopy showed a large potential difference between the main FCC phase and sigma phase for the Mo0–2 films. This would suggest that preferential dissolution of the FCC phase occurs over the sigma and reduces the corrosion resistance. Such preferential dissolution does not occur for the higher Mo content films with only the FCC phase. The high corrosion resistance was also attributed to the inhibition of Fe and Cr dissolution by Mo and the stabilisation of the Cr enriched oxide by incorporating Mo oxides into the passive film, identified by X-ray photoelectron spectroscopy. The low corrosion current densities (below 1 µA/cm2) make these thin films possible candidates for protective coatings of bipolar plates in PEM fuel cells.

    Place, publisher, year, edition, pages
    Elsevier B.V., 2024
    Keywords
    Corrosion, Fuel cells; High entropy alloy; Magnetron sputtering; Multicomponent thin film
    National Category
    Other Materials Engineering
    Identifiers
    urn:nbn:se:liu:diva-201590 (URN)10.1016/j.tsf.2024.140220 (DOI)2-s2.0-85182731274 (Scopus ID)
    Note

    Funding Agencies|LiTH; Swedish Agency for Innovation Systems; VINNOVA, (2016–05156, 2019–04881); Linköpings Universitet, LiU, (2009 00971)

    Available from: 2024-03-13 Created: 2024-03-13 Last updated: 2024-10-01
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  • Public defence: 2024-10-25 09:00 Ada Lovelace, B-building, LinköpingOrder onlineBuy this publication >>
    Olmin, Amanda
    Linköping University, Department of Computer and Information Science, The Division of Statistics and Machine Learning. Linköping University, Faculty of Arts and Sciences.
    Perspectives on Predictive and Annotation Uncertainty in Probabilistic Machine Learning2024Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    Machine learning models are, just as us humans, exposed to the uncertainty of the world. Following the complexity of real-world events, these models are often employed for prediction tasks where there is no single, ground-truth answer, meaning that it may be impossible to determine the precise outcome of the predicted event beforehand. This aleatoric uncertainty is potentially, but not necessarily, a result of the event in question being part of a larger system, where some information remains undisclosed. 

    Moreover, machine learning models are data-driven and typically learn everything they know from data, called training data. The quality of the training data is vital in deter-mining the extent of a machine learning model’s knowledge and, consequently, how well the model performs on a given task. For instance, when training data is limited, this can result in uncertainty originating from a lack knowledge, often referred to as epistemic uncertainty. Furthermore, collected through observation, or measurements, of real-world events, the training data naturally incorporates the uncertainty inherent to these events. Some-times, additional uncertainty is integrated through the processes used to acquire the data, following, for instance, measurement error or human error. One such type of uncertainty is in this thesis termed annotation uncertainty, and relates to the collection of annotations for training models through supervised learning. 

    The focus of this thesis lies on probabilistic predictive machine learning models, as an approach to representing different sources of so-called predictive uncertainty, including aleatoric, epistemic and annotation uncertainty. Special attention is given to annotation uncertainty, beginning with an exploration of possible negative effects of this type of uncertainty on the performance of probabilistic predictive models. We analyse how annotation uncertainty, or noise, affects the properties of asymptotic risk minimisers when training models with two different classes of loss functions: strictly proper and a group of previously proposed robust loss functions. The analysis emphasises the importance of considering a model’s ability to accurately estimate predictive uncertainty, also referred to as the model’s reliability, when developing training algorithms robust to annotation noise. 

    However, under the umbrella of weak supervision, we also provide two examples of when annotation uncertainty can be allowed, to instead benefit model performance. In the first example, we use ensemble models to generate annotations for the training data, with the aim to teach individual probabilistic models to estimate both aleatoric and epistemic uncertainty in their predictions. Having this ability is beneficial in many applications, one of them being active learning, and, notably, the active learning algorithm constituting the second example. This specific active learning algorithm acquires data samples based on high epistemic uncertainty, believed to represent samples for which there is much gain to be made in terms of model performance. The contribution does not lie in the particular approach to acquiring data samples, but instead in introducing the possibility to make a trade-off between annotation costs and quality of annotations, as part of the active learning algorithm. Such a trade-off has the potential to lead to an improved model performance under a fixed annotation budget.

    The thesis also explores topics beyond annotation uncertainty. First, in the context of learning probabilistic machine learning models, we focus on unnormalised probabilistic models, with energy-based models among them. We establish a link between two groups of important methods used for estimating unnormalised models, namely noise-contrastive estimation and approximate maximum likelihood methods. This link provides an improved under-standing of noise-contrastive estimation and serves to create a more coherent framework for the estimation of unnormalised models. Second, for deeper insights into the generalisation behaviour of machine learning models trained using gradient-based learning, we study the epoch-wise double descent phenomenon in two-layer linear neural networks. With this, we identify additional factors contributing to epoch-wise double descent that has not been observed for the simpler linear regression model, which is commonly central to theoretical studies. Although not specific to probabilistic models, these insights could potentially be extended to such models in the future and used to further explore the interplay between annotation uncertainty and model performance.

    List of papers
    1. A General Framework for Ensemble Distribution Distillation
    Open this publication in new window or tab >>A General Framework for Ensemble Distribution Distillation
    2020 (English)In: 2020 IEEE 30th International Workshop on Machine Learning for Signal Processing (MLSP), IEEE, 2020, p. 1-6Conference paper, Published paper (Refereed)
    Abstract [en]

    Ensembles of neural networks have shown to give better predictive performance and more reliable uncertainty estimates than individual networks. Additionally, ensembles allow the uncertainty to be decomposed into aleatoric (data) and epistemic (model) components, giving a more complete picture of the predictive uncertainty. Ensemble distillation is the process of compressing an ensemble into a single model, often resulting in a leaner model that still outperforms the individual ensemble members. Unfortunately, standard distillation erases the natural uncertainty decomposition of the ensemble. We present a general framework for distilling both regression and classification ensembles in a way that preserves the decomposition. We demonstrate the desired behaviour of our framework and show that its predictive performance is on par with standard distillation.

    Place, publisher, year, edition, pages
    IEEE, 2020
    Series
    IEEE International Workshop on Machine Learning for Signal Processing, ISSN 2161-0363
    Keywords
    Uncertainty, Predictive models, Data models, Computational modeling, Training, Toy manufacturing industry, Neural networks, Ensemble, distillation
    National Category
    Probability Theory and Statistics
    Identifiers
    urn:nbn:se:liu:diva-175056 (URN)10.1109/MLSP49062.2020.9231703 (DOI)000630907800032 ()9781728166629 (ISBN)
    Conference
    30th IEEE International Workshop on Machine Learning for Signal Processing (MLSP), Aalto Univ, ELECTR NETWORK, sep 21-24, 2020
    Funder
    Wallenberg AI, Autonomous Systems and Software Program (WASP)
    Note

    Funding: Wallenberg Al, Autonomous Systems and Software Program (WASP) - Knut and Alice Wallenberg Foundation

    Available from: 2021-04-16 Created: 2021-04-16 Last updated: 2024-09-19Bibliographically approved
    2. Robustness and Reliability When Training With Noisy Labels
    Open this publication in new window or tab >>Robustness and Reliability When Training With Noisy Labels
    2022 (English)In: Proceedings of the 25th International Conference on Artificial Intelligence and Statistics (AISTATS) 2022, JMLR , 2022, Vol. 151, p. 922-942Conference paper, Published paper (Refereed)
    Abstract [en]

    Labelling of data for supervised learning canbe costly and time-consuming and the riskof incorporating label noise in large data setsis imminent. When training a flexible discriminative model using a strictly proper loss,such noise will inevitably shift the solution towards the conditional distribution over noisylabels. Nevertheless, while deep neural networks have proven capable of fitting randomlabels, regularisation and the use of robustloss functions empirically mitigate the effectsof label noise. However, such observationsconcern robustness in accuracy, which is insufficient if reliable uncertainty quantificationis critical. We demonstrate this by analysingthe properties of the conditional distributionover noisy labels for an input-dependent noisemodel. In addition, we evaluate the set ofrobust loss functions characterised by noiseinsensitive, asymptotic risk minimisers. Wefind that strictly proper and robust loss functions both offer asymptotic robustness in accuracy, but neither guarantee that the finalmodel is calibrated. Moreover, even with robust loss functions, overfitting is an issue inpractice. With these results, we aim to explain observed robustness of common training practices, such as early stopping, to labelnoise. In addition, we aim to encourage thedevelopment of new noise-robust algorithmsthat not only preserve accuracy but that alsoensure reliability. 

    Place, publisher, year, edition, pages
    JMLR, 2022
    Series
    The proceedings of Machine Learning research, ISSN 2640-3498
    National Category
    Computer and Information Sciences
    Identifiers
    urn:nbn:se:liu:diva-185232 (URN)000828072700039 ()
    Conference
    International Conference on Artificial Intelligence and Statistics, ELECTR NETWORK, mar 28-30, 2022
    Note

    Funding: Swedish Research Council via the project Handling Uncertainty in Machine Learning Systems [2020-04122]; Swedish Foundation for Strategic Research via the project Probabilistic Modeling and Inference for Machine Learning [ICA16-0015]; Wallenberg AI, Autonomous Systems and Software Program (WASP) - Knut and Alice Wallenberg Foundation; ELLIIT

    Available from: 2022-05-22 Created: 2022-05-22 Last updated: 2024-09-19
    3. Active Learning with Weak Supervision for Gaussian Processes
    Open this publication in new window or tab >>Active Learning with Weak Supervision for Gaussian Processes
    2023 (English)In: Neural Information Processing 29th International Conference, ICONIP 2022, Virtual Event, November 22–26, 2022, Proceedings, Part V / [ed] M. Tanveer et al., Singapore: Springer Nature, 2023, p. 195-204Conference paper, Published paper (Refereed)
    Abstract [en]

    Annotating data for supervised learning can be costly. When the annotation budget is limited, active learning can be used to select and annotate those observations that are likely to give the most gain in model performance. We propose an active learning algorithm that, in addition to selecting which observation to annotate, selects the precision of the annotation that is acquired. Assuming that annotations with low precision are cheaper to obtain, this allows the model to explore a larger part of the input space, with the same annotation budget. We build our acquisition function on the previously proposed BALD objective for Gaussian Processes, and empirically demonstrate the gains of being able to adjust the annotation precision in the active learning loop.

    Place, publisher, year, edition, pages
    Singapore: Springer Nature, 2023
    Series
    Communications in Computer and Information Science, ISSN 1865-0929, E-ISSN 1865-0937 ; 1792
    Keywords
    Machine learning, Active learning, Weak supervision
    National Category
    Computer Sciences
    Identifiers
    urn:nbn:se:liu:diva-195039 (URN)10.1007/978-981-99-1642-9_17 (DOI)978-981-99-1641-2 (ISBN)978-981-99-1642-9 (ISBN)
    Conference
    29th International Conference on Neural Information Processing, ICONIP 2022, Virtual Event, November 22–26, 2022
    Available from: 2023-06-14 Created: 2023-06-14 Last updated: 2024-09-19
    4. On the connection between Noise-Contrastive Estimation and Contrastive Divergence
    Open this publication in new window or tab >>On the connection between Noise-Contrastive Estimation and Contrastive Divergence
    2024 (English)Conference paper, Published paper (Refereed)
    Abstract [en]

    Noise-contrastive estimation (NCE) is a popular method for estimating unnormalised probabilistic models, such as energy-based models, which are effective for modelling complex data distributions. Unlike classical maximum likelihood (ML) estimation that relies on importance sampling (resulting in ML-IS) or MCMC (resulting in contrastive divergence, CD), NCE uses a proxy criterion to avoid the need for evaluating an often intractable normalisation constant. Despite apparent conceptual differences, we show that two NCE criteria, ranking NCE (RNCE) and conditional NCE (CNCE), can be viewed as ML estimation methods. Specifically, RNCE is equivalent to ML estimation combined with conditional importance sampling, and both RNCE and CNCE are special cases of CD. These findings bridge the gap between the two method classes and allow us to apply techniques from the ML-IS and CD literature to NCE, offering several advantageous extensions.

    Series
    Proceedings of Machine Learning Research, ISSN 2640-3498
    Keywords
    Unnormalised models, noise-contrastive estimation, contrastive divergence
    National Category
    Computer and Information Sciences
    Identifiers
    urn:nbn:se:liu:diva-204020 (URN)
    Conference
    International Conference on Artificial Intelligence and Statistics, 2-4 May 2024, Palau de Congressos, Valencia, Spain
    Funder
    Wallenberg AI, Autonomous Systems and Software Program (WASP)
    Note

    This article has a CC BY-licence.

    Available from: 2024-05-31 Created: 2024-05-31 Last updated: 2024-09-19Bibliographically approved
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  • Public defence: 2024-10-25 10:00 K1, Kåkenhus, NorrköpingOrder onlineBuy this publication >>
    Savvakis, Marios
    Linköping University, Department of Science and Technology, Laboratory of Organic Electronics. Linköping University, Faculty of Science & Engineering.
    Visible Light Activated Polymerization of Conjugated Molecules: Mechanism and Applications2024Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    Bioelectronics, a field that bridges biology and electronics, has a rich history dating back to the 18th century. The inception of bioelectronics is generally attributed to Luigi Galvani, who in the late 1700s discovered that frog legs twitch as if alive when struck by electrical current. Consequently, this was the idea leading to what is known as animal electricity, which is considered the precursor to modern bioelectronics. Furthermore, in the mid-1800s, the electrical phenomena of exposed cerebral hemispheres in rabbits and monkeys were discovered by Richard Caton leading to the advancement in the 20th century bringing us closer to what we refer as bioelectronics nowadays, with the development of medical devices to aid with cardiological or hearing disorders such as the pacemaker and cochlear implants. What is more, a big milestone in the field of bioelectronics was the invention of the transistor in the middle of the 20th century opening countless new possibilities for biocompatible devices and electronic miniaturization. Nowadays bioelectronics have been evolving into a broad and diverse field with applications ranging from medical imaging to even genetic modification. The focus is on areas like bioelectronic medicine, neural interfaces and biosensors as well as the development and testing of new biocompatible materials. The field is growing every day driven by advancements in both organic electronics and biology. As our understanding is expanding more about the properties of biological cells and tissues, the potential ideas and applications will also continue to grow.   

    Currently, the state of the art is Neuralink with the aim of creating a brain-computer interface that could potentially restore autonomy to those with medical needs that could not be met with the current advancements in technology. A device containing a chip and several electrode arrays of more than 1,000 super thin, flexible conductors that a surgical robot carefully implants into the cerebral cortex was utilized. Implantable devices designed to make controlling a computer or mobile device at will come closer to reality, with the biggest success being that these devices were successfully implanted in a human for the first time ever.   

    Organic electronics is a field with focus on the synthesis, characterization, design, and application of polymers that exhibit desirable electronic properties such as high conductivity and processability. Organic electronic materials are constructed from organic polymers unlike their inorganic semiconductor counter parts. Benefits of organic electronics include their (potential) lower cost compared to traditional inorganic electronics as well as increased material flexibility. What is more, organic electronics are a better fit for the growing field of green environmentally friendly chemistry. However, the implementation of organic electronic materials can be challenging, especially considering their inferior thermal stability and diverse fabrication issues. Organic electrochemical transistors (OECTs) are transistor devices where the channel betwixt the source and drain is comprised by an organic semiconductor. The electrical current produced is governed by the interchange of ions between the device channel and the electrolyte solution (usually phosphate buffered saline for our experiments). The operation of OECTs is governed by potential changes between the organic semiconductor channel and the gate electrode (usually AgCl or Pt) leading to modulation of the charge density and thus conductivity. For this reason, OECTs are great for applications like bioelectronics and biosensors due to the excellent modulation properties they exhibit  

    This thesis focuses on the development of a new wave of conducting polymers by selective visible-light-activated polymerization of advanced processable functional materials for possible applications in neural interfaces, biosensors, photocatalysis, conductive inks, and energy storage. Chemical and morphological effects of micro-structured processable materials are of utmost importance. Bioelectronic technologies were developed to enable new discoveries like soft electrodes that can be grown inside living tissue utilizing processes taking place inside the brain. Several new strategies were developed for the polymerization of these materials that were also electrically characterized afterwards. These strategies include the photoinduced polymerization of EEE-COONa (EDOT-EDOT-EDOT moieties with a carboxylic acid side chain) as well as EEE-S (EDOT-EDOT-EDOT moieties with a sulfonate side chain). What is more, these materials can be successfully processed and utilized in applications like photopatterning, where photolithography masks are used as the desired patterning shape with high fidelity structures as a result with micrometer resolution. Photopatterning can also be implemented in vivo with the use of photocatalytic dyes like SiR-COOH which extends the polymerization capabilities to longer wavelengths (650 nm) on zebrafish brains and tails, essentially creating conductive tattoos on living organisms.   

    One other important part of this thesis is the mechanistic studies of the photoinduced polymerization, to gain further insight on how this new technology can be refined and implemented in new applications. Our findings suggest that oxygen plays an integral role in the polymerization reaction since hydrogen peroxide production has been observed after the illumination of the monomer/polymer solutions. Furthermore, a study on the stability of enzymatically crafted OECTs containing materials such as ETE-COONa (EDOT-Thiophene-EDOT moieties with a carboxylic acid side group), ETE-S (EDOT-Thiophene-EDOT moieties with a sulfonate side group), and EEE-COONa was conducted to improve adhesion and long-term usage. Sulfo-NHS click chemistry was implemented to improve the adhesion to modified epoxy group silane (GOPS) to create a stronger covalent bond between the organic molecules and the surface of the interface. 

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  • Public defence: 2024-10-25 10:15 ACAS, A-building, LinköpingOrder onlineBuy this publication >>
    Romanov, Pavel
    Linköping University, Department of Management and Engineering, Engineering Materials. Linköping University, Faculty of Science & Engineering.
    Cooling of Steel Components with Impinging Jet Quenching Technique: The Effect of Continuous and Differential Cooling on Material Properties and Microstructure2024Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    Heat-treatment plays a crucial role in manufacturing and production of steel components since its aim is to provide necessary material properties to fulfil the in-service requirements and comply with the safety measures. Cooling of steel components is a necessary step in heat-treatment and associated with different microstructure manipulations that control the mechanical and other properties, depending on the steel type in question. Common issues of this process, for example in large-scale production of thick bars or in small scale-production of automobile or agricultural steel components, include insufficient cooling rate that leads to poor properties, undesirable residual stresses that may lead to cracks and premature failure, as well as insufficient spatial and temporal control over the quenched sample in case when gradients of mechanical properties are required.  

    To avoid the mentioned issues and improve the control during cooling process, a newly developed test rig for Impinging Jet Quenching Technique (IJQT) is used in this thesis to investigate the spatial and temporal behavior of various steel types during different cooling routes. The study is focused on two main cases: continuous cooling of solid cylindrical bars and differential cooling of thick plates. The continuous cooling of bars involves water quench-hardening of low-alloyed carbon steel and different cooling routes of super duplex stainless-steel. The differential cooling of plates involves cooling of different types of carbon steels with various hardenability levels using water and compressed air. The work includes an accurate temperature recording from cooling experiments and metallurgical characterizations for validation of cooling simulation models.  

    The results from continuous cooling case showed that martensite hardening of carbon steel bars with water jets can be controlled using IJQT and correlate well with the simulation model which is validated by hardness measurements, microstructure observations and residual stress analysis. Cooling of the duplex stainless-steel bars and their metallurgical characterizations as well as impact toughness results show the technique’s high flexibility and control over temperature evolutions during both water and compressed air cooling. The study of continuous cooling using IJQT in this thesis clearly demonstrates its high potential to be used for other sizes and geometries.  

    The results from differential cooling case show that IJQT is flexible enough to provide a wide range of simultaneous cooling rates along the steel plates of different carbon content using both water jets and air jets resulting in various microstructure and hardness gradients. For 0.38-mass% C steel the gradient includes fully martensitic condition with high hardness level transitioning to a slightly softer bainitic region. For the 0.27-mass% C steel the gradient includes almost fully hardened state smoothly transitioning to a soft pearlitic region covering a wide range of hardness levels within a component. The results from physical experiments on differential quenching facilitated further modelling approach for exploring carbon steels in terms of their applicability for microstructure- and hardness gradient formation using different cooling strategies.  

    The research in this thesis provides a deeper understanding of how microstructures and properties of steel components can be manipulated using IJQT to achieve specific requirements depending on the steel type in question. In long term, it is believed that the approach used in this thesis will contribute to the development and establishment of an advanced digital tool for optimal selection of alloys and corresponding cooling strategies thus reducing the experimental time and unnecessary emissions. 

    List of papers
    1. Quenching of Carbon Steel Plates with Water Impinging Jets: Differential Properties and Fractography
    Open this publication in new window or tab >>Quenching of Carbon Steel Plates with Water Impinging Jets: Differential Properties and Fractography
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    2023 (English)In: Procedia Structural Integrity, ISSN 2452-3216, Vol. 43, p. 154-159Article in journal (Refereed) Published
    Abstract [en]

    The demand for steel components with tailored properties is constantly growing. To obtain a specific variation of microstructures and mechanical properties along the component it must undergo a controllable cooling. One way to control the cooling rates along the component is by using different simultaneous water jet impingements on a hot austenitized surface. This can be done by a newly developed test rig for water Impinging Jet Quenching Technique (IJQT). This work discusses the effect of IJQT on mechanical properties and fracture behavior of 15 mm steel plates containing 0.27 and 0.38 mass-% carbon. The samples were cooled in a specifically designed setup of the technique to obtain simultaneous water and air cooling resulting in diverse microstructures. The mechanical property gradients of both steels were analyzed through hardness measurements and tensile tests. The fracture surfaces and the near fracture regions were observed using scanning electron microscope and light optical microscope respectively. The results from tensile tests showed that the larger part of the sample with higher carbon content was fully hardened, however smoothly transitioning to a more ductile region. The sample with lower carbon content combined various degrees of hardening and transitioned from higher to lower ultimate tensile strength values. Fracture behavior of higher carbon steel was predominantly brittle transitioning to a ductile, while the lower carbon steel had a small region showing brittle fracture transitioning to a larger region of predominant ductile fracture behavior.

    Place, publisher, year, edition, pages
    Elsevier, 2023
    Keywords
    Martensite, Brittle fracture, Ductile fracture, Impinging Jet Quenching, Boron steel
    National Category
    Metallurgy and Metallic Materials
    Identifiers
    urn:nbn:se:liu:diva-191833 (URN)10.1016/j.prostr.2022.12.251 (DOI)001198152000026 ()
    Conference
    10th International Conference on Materials Structure and Micromechanics of Fracture (MSMF), Brno, CZECH REPUBLIC, sep 12-14, 2022
    Note

    Funding Agencies|Sweden's Innovation Agency Vinnova [2017-02281]; Swedish Agency for Economic and Regional Growth [20201438]

    Available from: 2023-02-20 Created: 2023-02-20 Last updated: 2024-09-24
    2. Differential Microstructure and Properties of Boron Steel Plates Obtained by Water Impinging Jet Quenching Technique
    Open this publication in new window or tab >>Differential Microstructure and Properties of Boron Steel Plates Obtained by Water Impinging Jet Quenching Technique
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    2024 (English)In: Steel Research International, ISSN 1611-3683, E-ISSN 1869-344X, Vol. 95, no 1, article id 2300406Article in journal (Refereed) Published
    Abstract [en]

    Soil-working tools in agriculture are made of boron-containing steels with high wear resistance and hardenability. Nevertheless, these tools are subject to high impacts, abrasive wear, and fatigue and are therefore prone to failure. To combine varying levels of properties within one component in as-quenched condition can be beneficial for such products. To obtain this property variation, a component must undergo a complex and controllable cooling. Therefore, the aim of this work is to obtain a microstructure gradient along two 15 mm-thick steel plates in a newly developed test rig by water jet impingement technique to confirm its controllability and flexibility. Furthermore, a quenching simulation model is created for hardness prediction using phase transformation data from a machine learning tool. Microstructure variation is observed using light optical microscopy and the electron backscatter diffraction technique. Mechanical properties are studied through tensile tests and hardness measurements and are also compared with simulation results. The 0.27 mass% C steel sample is obtained in almost fully martensitic state transitioning to a softer ferritic/bainitic condition, while the 0.38 mass% C steel sample results predominantly into a fully hardened martensitic state and slightly shows ferritic and bainitic features along the sample. The quenching simulation model shows promising hardness prediction for both steels. A newly developed impinging jet quenching technique is used for differential quenching of 15 mm-thick boron steel sheets with the aim of obtaining microstructure and property gradients along their lengths. As a result, combinations of differential hardness profiles along with varying hardening degrees are produced and metallurgically characterized through microstructure observations and mechanical tests.

    Place, publisher, year, edition, pages
    WILEY-V C H VERLAG GMBH, 2024
    Keywords
    boron steel; critical cooling rate; differential quenching; hardenability; martensite
    National Category
    Metallurgy and Metallic Materials
    Identifiers
    urn:nbn:se:liu:diva-198813 (URN)10.1002/srin.202300406 (DOI)001082647000001 ()
    Note

    Funding Agencies|The present study was financed by Swedenapos;s Innovation Agency Vinnova (grant no. 2017-02281) and by the Swedish Agency for Economic and Regional Growth (grant no. 20201438). [2017-02281]; Swedenapos;s Innovation Agency Vinnova [20201438]; Swedish Agency for Economic and Regional Growth

    Available from: 2023-10-30 Created: 2023-10-30 Last updated: 2024-09-24
    3. Hardening of Cylindrical Bars with Water Impinging Jet Quenching Technique
    Open this publication in new window or tab >>Hardening of Cylindrical Bars with Water Impinging Jet Quenching Technique
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    2024 (English)In: Steel Research International, ISSN 1611-3683, E-ISSN 1869-344XArticle in journal (Refereed) Epub ahead of print
    Abstract [en]

    Hardening of carbon steel products by austenitization and immersion in a quenching medium is a widely used heat treatment to obtain a hard and strong martensitic structure. To avoid the undesired consequences, such as residual stresses or insufficient hardening depth, the cooling rates must be accurately measured and controlled. This can be achieved using the impinging water jet quenching technique. The aim of this work is to perform hardening of four low-alloyed 70 mm cylindrical carbon steel bars, using impinging water jet quenching technique with different jet flow rates, and to analyze its effect on thermal evolution and residual stresses. The temperature evolution during quenching experiments is recorded and used as input to a comprehensive quenching model to predict phase transformations, final hardness, and residual stresses of cylindrical bars. All four quenching experiments result in a fully hardened martensitic state. Furthermore, a decrease in jets' flow rate, within a certain interval, results in different thermal histories and in lower compressive residual stresses on the surface. The results from quenching simulations show promising hardness, microstructure, and residual stress predictions that are validated by hardness measurements, optical microscopy, and residual stress analysis using X-Ray diffraction method. Four 70 mm cylindrical steel bars are martensite hardened with different water jet flow rates using impinging jet quenching technique. A finite element method (FEM) quenching model is created to simulate phase transformations and predict the resulting microstructure, hardness, and residual stresses. The model is metallurgically validated through hardness measurements, microstructure observations, and residual stress measurements using X-ray diffraction technique.image (c) 2024 WILEY-VCH GmbH

    Place, publisher, year, edition, pages
    WILEY-V C H VERLAG GMBH, 2024
    Keywords
    hardening; impinging jet quenching; machine learning; martensite; residual stresses
    National Category
    Metallurgy and Metallic Materials
    Identifiers
    urn:nbn:se:liu:diva-202288 (URN)10.1002/srin.202300884 (DOI)001180262600001 ()
    Note

    Funding Agencies|The Knowledge Foundation [20190066]; Knowledge Foundation

    Available from: 2024-04-09 Created: 2024-04-09 Last updated: 2024-09-24
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  • Public defence: 2024-10-25 13:00 Hasselquistsalen, building 511, LinköpingOrder onlineBuy this publication >>
    Svensson, Katarina
    Linköping University, Department of Biomedical and Clinical Sciences, Division of Children's and Women's Health. Linköping University, Faculty of Medicine and Health Sciences. Region Östergötland, Center of Paediatrics and Gynaecology and Obstetrics, H.K.H. Kronprinsessan Victorias barn- och ungdomssjukhus.
    Pediatric ischemic stroke and Cerebral Palsy: Early Identification and Intervention2024Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    Pediatric ischemic stroke can affect children of all ages often leading to motor impairment. Early identification of children at risk of permanent motor impairments such as cerebral palsy (CP) or hemiparesis is crucial to enable timely interventions optimizing their functional outcomes. One method for early assessment in infants is Prechtl’s qualitative assessment of General movements (GMA), along with an early motor intervention applied before 12 months of age: Baby-mCIMT.  The aim of the thesis was to identify adverse motor outcomes after pediatric ischemic stroke, assess potential risk factors and explore the feasibility of early identification and intervention in infants at high risk of CP using remote eHealth approaches.  

    Study I is an epidemiological study using a national register-based cohort of individuals with pediatric ischemic stroke and matched controls, investigating the risk and contributing factors for adverse motor outcomes. The study found that in children affected by ischemic stroke, 32% were diagnosed with adverse motor outcomes, with a higher risk in childhood stroke compared to perinatal stroke. No other significant risk factors such as gestational age, sex or parental age were identified.  

    Study II evaluates remote GMA in a neonatal risk group, focusing on inter-rater reliability and smartphone app usability, as part of the methodological approach in an ongoing nationwide study. Caregivers filmed their infants’ spontaneous movements with a smartphone app. The films were analyzed by certified assessors blinded to the infants’ medical history. Inter-rater reliability was moderate between assessors but substantial when the assessors’ final group consensus was compared to a GMA expert’s assessment. The app was rated highly for usability according to film quality and parental satisfaction.  

    Study III examines early intervention in infants at risk of unilateral CP using the Baby-mCIMT program comparing two groups with different parental coaching approaches: remote and in-person. The outcome was evaluated based on the infants’ development of hand function, assessed before and after the intervention. The result showed that the infants’ hand function developed equally, regardless of the coaching approach used.  

    Study IV describes parental experiences of implementing training according to the Baby-mCIMT program with remote coaching. The findings highlighted that the remote approach offered parents as primary trainers opportunities for learning and empowerment. The responsive professional guidance and a strong therapist-parent relationship were found to be important for implementing the intervention.  

    This thesis highlights the substantial risk of motor impairment following pediatric ischemic stroke, emphasizing the need of targeted actions, regardless of the child’s age at the time of the ischemic stroke. Parents can effectively engage in remote assessment and early intervention with professional support, even at a geographical distance.   

    List of papers
    1. Adverse motor outcome after paediatric ischaemic stroke: A nationwide cohort study
    Open this publication in new window or tab >>Adverse motor outcome after paediatric ischaemic stroke: A nationwide cohort study
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    2022 (English)In: Paediatric and Perinatal Epidemiology, ISSN 0269-5022, E-ISSN 1365-3016, Vol. 36, no 3, p. 412-421Article in journal (Refereed) Published
    Abstract [en]

    Background Various frequencies of adverse motor outcomes (cerebral palsy and hemiplegia) after paediatric ischaemic stroke have been reported. Few reports on the risks of adverse motor outcomes in nationwide cohorts and contributing risk factors are available. Objectives To assess risk of adverse motor outcome and potential risk factors thereof after paediatric ischaemic stroke in a nationwide cohort. Methods This nationwide matched cohort study identified 877 children &lt;18 years of age diagnosed with ischaemic stroke through the Swedish national health registers from 1997 to 2016. These children, exposed to ischaemic stroke, alive 1 week after stroke, were matched for age, sex and county of residence with 10 unexposed children. Using Cox regression, we estimated the risk of adverse motor outcomes in children with stroke compared to that in unexposed children. Logistic regression was applied to compare the characteristics of children with and without adverse motor outcomes after stroke. Results Out of the 877 children with ischaemic stroke, 280 (31.9%) suffered adverse motor outcomes compared with 21 (0.2%) of the 8770 unexposed: adjusted hazard ratio (aHR) 167.78 (95% confidence interval (CI) 107.58, 261.66). There were no differences between risk estimates of adverse motor outcome according to age at stroke: perinatal stroke (aHR 124.11, 95% CI 30.45, 505.84) and childhood stroke (aHR 182.37, 95% CI 113.65, 292.64). An association between adverse motor outcome and childhood stroke aOR 1.56 (95% CI 1.05, 2.31) was found when analysing only children with ischaemic stroke. No associations were found between adverse motor outcome and sex, gestational age or parental age at birth. Conclusions The risk of adverse motor outcome is substantial after paediatric ischaemic stroke, especially childhood stroke, confirming results of previous smaller studies. This study found no associations between sex, gestational age or parental age and adverse motor outcome after paediatric ischaemic stroke.

    Place, publisher, year, edition, pages
    Wiley, 2022
    Keywords
    adverse motor outcome; cerebral palsy; children; cohort studies; hemiplegia; ischaemic stroke
    National Category
    Occupational Health and Environmental Health
    Identifiers
    urn:nbn:se:liu:diva-183415 (URN)10.1111/ppe.12869 (DOI)000755930800001 ()35172018 (PubMedID)
    Note

    Funding Agencies|Knut and Alice Wallenberg FoundationKnut & Alice Wallenberg Foundation; Region Ostergotland Research Council; Jerring foundation; Petrus and Augusta Hedlunds foundation; Sachs children and youth hospital; Linnea and Josef Carlsson foundation

    Available from: 2022-03-10 Created: 2022-03-10 Last updated: 2024-10-09Bibliographically approved
    2. Usability and inter-rater reliability of the NeuroMotion app: A tool in General Movements Assessments
    Open this publication in new window or tab >>Usability and inter-rater reliability of the NeuroMotion app: A tool in General Movements Assessments
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    2021 (English)In: European journal of paediatric neurology, ISSN 1090-3798, E-ISSN 1532-2130, Vol. 33, p. 29-35Article in journal (Refereed) Published
    Abstract [en]

    Background: Early intervention after perinatal brain insults requires early detection of infants with cerebral palsy (CP). General Movements Assessments (GMA) in the fidgety movement period has a high predictive value for CP. Aim: To investigate the NeuroMotionTM apps usability regarding film quality and user experience and to assess the inter-rater reliability of GMA in a neonatal risk group. Methods: GMA, inter-rater reliability and film quality was assessed in a cohort consisting of 37 infants enrolled in a multicentre study of GMA as part of the Swedish neonatal follow-up program for high-risk infants. Some of these infants were filmed twice. For evaluation of user experience 95 parents of 52 infants were addressed with a web-based questionnaire. A GMA expert assessed film quality and performed GMA and three on-site assessors, individually performed GMA. Inter-rater reliability was computed using Krippendorffs alpha (k-alpha). Results: In all, 45 films showed good or excellent quality. The response rate of the questionnaire survey was 40% and revealed predominantly positive perceptions of the NeuroMotionTM app. GMA in 36 infants resulted in substantial agreement (k-alpha = 0.72, 95%CI = 0.3-1.0) between the three on-site assessors consensus and the GMA expert. Inter-rater reliability for GMA between the on-site assessors was moderate (k-alpha = 0.48, 0.18-0.74). Conclusion: The NeuroMotionTM app produces good technical quality films and the app user experience was overall positive. High agreement was observed between the on-site assessors and the GMA expert. The study design is feasible for more extensive GMA studies in cohorts of infants at risk of CP. (c) 2021 The Authors. Published by Elsevier Ltd on behalf of European Paediatric Neurology Society. This is an open access article under the CC BY license (http://creativecommons.org/licenses/by/4.0/).

    Place, publisher, year, edition, pages
    Elsevier Science Ltd, 2021
    Keywords
    Cerebral palsy; General movement assessment; Infant; Inter-rater reliability; Smartphone application
    National Category
    Pediatrics
    Identifiers
    urn:nbn:se:liu:diva-180535 (URN)10.1016/j.ejpn.2021.05.006 (DOI)000704291700008 ()34052727 (PubMedID)
    Note

    Funding Agencies|Knut and Alice Wallenberg Foundation for research on stroke; Region Ostergotland Research Council; Medical Reaserch Council of Southeast Sweden [FORSS-859871]

    Available from: 2021-10-26 Created: 2021-10-26 Last updated: 2024-10-09
    3. Outcomes of a Parent-Delivered Baby-mCIMT Model for Infants at High Risk of Unilateral Cerebral Palsy Using Remote Coaching in Telerehabilitation
    Open this publication in new window or tab >>Outcomes of a Parent-Delivered Baby-mCIMT Model for Infants at High Risk of Unilateral Cerebral Palsy Using Remote Coaching in Telerehabilitation
    2024 (English)In: Children, E-ISSN 2227-9067, Vol. 11, no 1, article id 101Article in journal (Refereed) Published
    Abstract [en]

    There is growing evidence of the positive effects of constraint-induced movement therapy (CIMT) for infants at high risk of unilateral cerebral palsy (UCP) when provided by parents with in-person coaching/supervision from occupational therapists during home visits. The aim of this study is to investigate whether Baby-mCIMT (modifiedCIMT) can be as effective if parents are coached/supervised remotely. In this case-control study, we recruited 20 infants and re-used 18 controls, 4-8-month-old infants in both groups at high risk of UCP. The same protocol regarding inclusion criteria, data collection, and training volume was used in both groups. The training was conducted for two 6-week periods, separated by a 6-week break, consisting of daily 30 min sessions conducted by parents, supported by therapist coaching once a week. The primary outcome was measured using the Hand Assessment for Infants (HAI). There was no difference in the change of HAI units (p = 0.803) or that of the affected-hand raw score (p = 0.942) between the two groups. The remote coaching method was well received by parents. In conclusion, this demonstrates that remote coaching/supervision is as effective as the in-person approach, requiring less time and effort for both families and healthcare providers.

    Place, publisher, year, edition, pages
    MDPI, 2024
    Keywords
    infant; unilateral CP; constraint-induced movement therapy; early intervention; telerehabilitation; internet-based training; hand function; hand assessment for infants
    National Category
    Pediatrics
    Identifiers
    urn:nbn:se:liu:diva-201012 (URN)10.3390/children11010101 (DOI)001149309700001 ()38255414 (PubMedID)
    Note

    Funding Agencies|Swedish Research Council [05474]; Stiftelsen Frimurare Barnhuset in Stockholm; Knut and Alice Wallenberg Foundation; Region Stockholm [2019-1138]; Queen Silvia's jubilee fund, Joanna Cocozza Foundation

    Available from: 2024-02-22 Created: 2024-02-22 Last updated: 2024-10-09
    4. Parents in the Driver's Seat-Experiences of Parent-Delivered Baby-mCIMT Coached Remotely
    Open this publication in new window or tab >>Parents in the Driver's Seat-Experiences of Parent-Delivered Baby-mCIMT Coached Remotely
    2024 (English)In: Journal of Clinical Medicine, E-ISSN 2077-0383, Vol. 13, no 16, article id 4864Article in journal (Refereed) Published
    Abstract [en]

    Background/Objectives: Recent guidelines on early intervention in children at high risk of cerebral palsy (CP) recommend parental involvement and family-centered home-based interventions with parents as primary trainers. Therapist coaching by home visitation is resource demanding, and telerehabilitation is a viable option for remote intervention and coaching. This study aims to describe parents' experiences of engaging in Baby-mCIMT coached remotely. Their infants are at high risk of unilateral cerebral palsy and the parents have been the primary trainers in regard to home-based intervention, optimizing the use of the affected hand. Methods: A qualitative approach involving semi-structured interviews with eight parents was employed. Data were analyzed using qualitative content analysis. Results: The overarching theme "Parents in the driver's seat-learning through remote coaching to create conditions to enhance the child's motor skills" describes parents' experiences as primary training providers. The following three underlying categories with subcategories were identified: (1) Baby-mCIMT coached remotely in an everyday context-practical and technical prerequisites; (2) the child's response and the therapists' coaching supports active parental learning; (3) capability and sense of control-strengthening and demanding aspects. Conclusions: Our findings revealed that Baby-mCIMT coached remotely empowered the parents as primary trainers, which provided them with opportunities for understanding and learning about their child and their development. The findings underscore the importance of responsive professional guidance and a strong therapist-parent relationship to succeed with the Baby-mCIMT program coached remotely and to manage the digital coaching format.

    Place, publisher, year, edition, pages
    MDPI, 2024
    Keywords
    early intervention; remote Baby-mCIMT; telerehabilitation; unilateral cerebral palsy; home-training; parent experience
    National Category
    Pediatrics
    Identifiers
    urn:nbn:se:liu:diva-208008 (URN)10.3390/jcm13164864 (DOI)001305659700001 ()39201006 (PubMedID)
    Note

    Funding Agencies|Linnea and Josef Carlsson Foundation; Stiftelsen for Barnmedicinsk forskning, Linkoping, Queen Silvia's Jubilee Fund; Joanna Cocozza Foundation; Region Stockholm, clinical postdoctoral [2019-1138]

    Available from: 2024-10-04 Created: 2024-10-04 Last updated: 2024-10-09
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  • Public defence: 2024-10-31 09:00 Berzeliussalen, LinköpingOrder onlineBuy this publication >>
    Saleh, Muna
    Linköping University, Department of Biomedical and Clinical Sciences, Division of Inflammation and Infection. Linköping University, Faculty of Medicine and Health Sciences. Region Östergötland, Medicine Center, Department of Rheumatology.
    Adverse pregnancy outcomes in systemic lupus erythematosus: Special emphasis on biomarker reference intervals2024Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    Abstract: Systemic lupus erythematosus (SLE) is a chronic autoimmune disease of unknown etiology, characterized by a wide range of manifestations that can vary from mild to severe or even life-threatening multiple organ system involvement. SLE predominantly affects women and has a peak incidence during women’s reproductive age. Given the complexity of SLE, managing pregnancy in these women is particularly challenging, as the disease itself can impact pregnancy outcomes, and conversely, pregnancy can exacerbate SLE symptoms. This thesis aims to explore pregnancy complications among women with SLE and to assess the feasibility of utilizing specific biomarkers for evaluating the risk of adverse outcomes in SLE pregnancies, as well as their potential to predict these outcomes. Paper I: A descriptive study on adverse pregnancy outcomes (APOs) in a Swedish population was conducted, involving 28 women diagnosed with SLE and 59 pregnancies monitored from 2002 to 2018 at Skåne University Hospital. The study aimed to determine the prevalence of each APO and to assess demographic, clinical, and laboratory risk factors. Most pregnancies experienced at least one APO, although only a small number were categorized as severe. It was shown that a history of lupus nephritis was the clinical feature most strongly associated with APOs. Moreover, the co-occurrence of SLE and antiphospholipid syndrome was linked to an increased risk of miscarriage, and the presence of one or more antiphospholipid antibodies was correlated with APOs overall. In papers II and III, the aim was to investigate, in 100 healthy women with 100 normal pregnancies selected from the pregnancy register and biobank at Linköping University (GRABB), if pregnancy influences the normal reference values of biomarkers such as complement proteins and pentraxins, to establish a reference interval that is more appropriate for the pregnancy period. Paper II: This study investigated the complement system, which is a vital component of the humoral innate immune system that exhibits increased activity during pregnancy. This function is necessary for maintaining the host's defense and ensuring fetal survival. However, excessive or unbalanced activation of the complement system in the placenta has been linked to various APOs. The study found that maternal plasma C1q and the C3d/C3 ratio had their highest mean values during the first trimester, while C3, C4, and C3d levels increased until delivery. However, the reference limits for complement analyses used for the general population were generally suitable for most of the samples in the study. This suggests that while there were some deviations from the norm in complement levels in certain pregnant women, the standard reference values still adequately captured the overall trends in complement activity during pregnancy in this population. Paper III: This study investigated the same population as in paper II and focused on two types of pentraxins: the liver-produced short pentraxin C-reactive protein (CRP), which is commonly used in clinical practice, and the leukocyte-produced long pentraxin 3 (PTX3), which is structurally and functionally related to CRP. Both pentraxins were previously described as biomarkers related to various APOs. The study found that both CRP and PTX3 levels were significantly elevated in the third trimester compared to the other trimesters. This suggests that during pregnancy, particularly in the later stages, reference values for these biomarkers may need to be adjusted to account for these physiological changes, highlighting the importance of considering pregnancy-specific reference values for these markers. Paper IV: Plasma levels of CRP, PTX3, C3, and C4 were assessed during 123 pregnancies in 102 patients with SLE and 170 pregnancies in women from the general population concerning the risk of APOs. All the patients and controls were recruited from three Swedish cohorts: the Lund cohort, referenced in Paper I; the GRABB cohort, which is mentioned in Papers II and III; and the SLE-Placenta cohort (SLE-PLAC) which is a multicenter Swedish cohort. Only PTX3 showed higher levels in the first and third trimesters of SLE pregnancies with APOs. Even after including control pregnancies with APOs, PTX3 levels remained significantly higher in complicated pregnancies, suggesting that PTX3 could serve as a potential biomarker for identifying at-risk complicated pregnancies.

    Conclusion: The incidence of APOs in pregnancies affected by SLE is significantly higher than in the general population, highlighting the urgent need for risk stratification and increased attention to specific clinical and serological risk factors in these cases. It is essential to note that reference intervals for some biomarkers may require adjustment during the pregnancy period to ensure accurate interpretation. While our findings need to be confirmed, the pentraxins especially PTX3 could be used for the risk stratification of pregnant women with SLE. 

    List of papers
    1. Adverse Pregnancy Outcomes after Multi-Professional Follow-Up of Women with Systemic Lupus Erythematosus: An Observational Study from a Single Centre in Sweden
    Open this publication in new window or tab >>Adverse Pregnancy Outcomes after Multi-Professional Follow-Up of Women with Systemic Lupus Erythematosus: An Observational Study from a Single Centre in Sweden
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    2020 (English)In: Journal of Clinical Medicine, E-ISSN 2077-0383, Vol. 9, no 8, article id 2598Article in journal (Refereed) Published
    Abstract [en]

    While the management of pregnant patients with systemic lupus erythematosus (SLE) has improved over the last decades, the risk of maternal, foetal, and neonatal complications is still substantial. We evaluated the occurrence of adverse pregnancy outcomes (APO) occurring in 2002-2018 among patients with SLE from the catchment area of the Department of Rheumatology in Lund, Sweden. Longitudinal clinical and laboratory data were collected and analysed. Results were stratified according to the sequence of conception. We investigated a total of 59 pregnancies in 28 patients. Prior lupus nephritis was the clinical feature that, in a multivariable regression analysis, displayed the strongest association with APO overall (OR 6.0,p= 0.02). SLE combined with antiphospholipid syndrome (APS) was associated with the risk of miscarriage (OR 3.3,p= 0.04). The positivity of multiple antiphospholipid antibodies (aPL) was associated with APO overall (OR 3.3,p= 0.05). IgG anti-cardiolipin during pregnancy resulted in a higher risk of preterm delivery (OR 6.8,p= 0.03). Hypocomplementaemia was associated with several APO, but only in the first pregnancies. We conclude that, despite the close follow-up provided, a majority of pregnancies resulted in &gt;= 1 APO, but a few of them were severe. Our study confirms the importance of previous lupus nephritis as a main risk factor for APO in patients with SLE.

    Place, publisher, year, edition, pages
    MDPI, 2020
    Keywords
    SLE; pregnancy; conception; adverse pregnancy outcomes; maternal and foetal complications; Lupus nephritis; antiphospholipid syndrome; risk factors
    National Category
    Rheumatology and Autoimmunity
    Identifiers
    urn:nbn:se:liu:diva-170013 (URN)10.3390/jcm9082598 (DOI)000564848300001 ()32796552 (PubMedID)
    Note

    Funding Agencies|Swedish Rheumatism Association; Region Ostergotland (ALF grants); King Gustaf Vs 80-year Anniversary Foundation; King Gustaf V and Queen Victorias Freemasons Foundation; Swedish Research CouncilSwedish Research Council; Alfred Osterlunds Foundation; Anna-Greta Crafoord Foundation; Greta and Johan Kocks Foundation; Skane University Hospital; Medical Faculty of Lund University

    Available from: 2020-09-26 Created: 2020-09-26 Last updated: 2024-10-09
    2. Variation of Complement Protein Levels in Maternal Plasma and Umbilical Cord Blood during Normal Pregnancy: An Observational Study
    Open this publication in new window or tab >>Variation of Complement Protein Levels in Maternal Plasma and Umbilical Cord Blood during Normal Pregnancy: An Observational Study
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    2022 (English)In: Journal of Clinical Medicine, E-ISSN 2077-0383, Vol. 11, no 13, article id 3611Article in journal (Refereed) Published
    Abstract [en]

    The complement system constitutes a crucial part of the innate immunity, mediating opsonization, lysis, inflammation, and elimination of potential pathogens. In general, there is an increased activity of the complement system during pregnancy, which is essential for maintaining the hosts defense and fetal survival. Unbalanced or excessive activation of the complement system in the placenta is associated with pregnancy complications, such as miscarriage, preeclampsia, and premature birth. Nonetheless, the actual clinical value of monitoring the activation of the complement system during pregnancy remains to be investigated. Unfortunately, normal reference values specifically for pregnant women are missing, and for umbilical cord blood (UCB), data on complement protein levels are scarce. Herein, complement protein analyses (C1q, C3, C4, C3d levels, and C3d/C3 ratio) were performed in plasma samples from 100 healthy, non-medicated and non-smoking pregnant women, collected during different trimesters and at the time of delivery. In addition, UCB was collected at all deliveries. Maternal plasma C1q and C3d/C3 ratio showed the highest mean values during the first trimester, whereas C3, C4, and C3d had rising values until delivery. We observed low levels of C1q and C4 as well as increased C3d and C3d/C3 ratio, particularly during the first trimester, as a sign of complement activation in some women. However, the reference limits of complement analyses applied for the general population appeared appropriate for the majority of the samples. As expected, the mean complement concentrations in UCB were much lower than in maternal plasma, due to the immature complement system in neonates.

    Place, publisher, year, edition, pages
    MDPI, 2022
    Keywords
    pregnancy; complement system; umbilical cord blood
    National Category
    Obstetrics, Gynecology and Reproductive Medicine
    Identifiers
    urn:nbn:se:liu:diva-187481 (URN)10.3390/jcm11133611 (DOI)000825612500001 ()35806894 (PubMedID)
    Note

    Funding Agencies|Region Ostergotland (ALF Grants) [RO-932055]; Swedish Rheumatism Association [R-939149]; Ulla and Roland Gustafsson Foundation; King Gustaf Vs 80-year Anniversary foundation [FAI-2020-0663]; King Gustaf V and Queen Victorias Freemasons foundation

    Available from: 2022-08-24 Created: 2022-08-24 Last updated: 2024-10-09
    3. Plasma C-Reactive Protein and Pentraxin-3 Reference Intervals During Normal Pregnancy
    Open this publication in new window or tab >>Plasma C-Reactive Protein and Pentraxin-3 Reference Intervals During Normal Pregnancy
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    2021 (English)In: Frontiers in Immunology, E-ISSN 1664-3224, Vol. 12, article id 722118Article in journal (Refereed) Published
    Abstract [en]

    Although several biomarkers are available to monitor the acute phase response, the short pentraxin C-reactive protein (CRP) is dominating in clinical practice. The long pentraxin 3 (PTX3) is structurally and functionally related to CRP, but not liver-derived. In addition, increased levels of PTX3 have been linked to preeclampsia. Reference intervals are usually based on healthy blood donors. Several physiological and immunological alterations occur during normal pregnancy with subsequent potential effects on blood analytes. Hence, this study aims to determine pregnancy-specific reference intervals for CRP and PTX3. Longitudinal clinical data and blood plasma samples from the 1(st), 2(nd) and 3(rd) trimester of 100 healthy, non-medicating, females aged 18-40 at the time-point of conception were available to us. High-sensitivity CRP measurements were performed by turbidimetry and enzyme-linked immunosorbent assay (ELISA) was used to quantify PTX3. CRP and PTX3 levels followed each other during the first two trimesters and both increased during the third trimester. CRP showed a median of 4.12 mg/L in the third trimester, and were significantly higher compared to the first (median 2.39 mg/L, p &lt; 0.0001) and the second (median 2.44 mg/L, p=0.0006) trimesters. In the third trimester PTX3 levels reached a median of 7.70 mu g/L, and were significantly higher compared to the first (median 3.33 mu g/L, p &lt; 0.0001) and the second (median 3.70 mu g/L, p &lt; 0.0001) trimesters. Plasma albumin was inversely correlated with CRP (rho=-0.27, p &lt; 0.0001), but not with PTX3. In conclusion, it is important to consider pregnancy-specific reference values as elevations of CRP and PTX3 during the later phase may occur in absence of infection.

    Place, publisher, year, edition, pages
    Frontiers Media SA, 2021
    Keywords
    C-reactive protein; pentraxin-3; pregnancy; reference interval (RI); biomarkers; acute phase protein; inflammation
    National Category
    Immunology in the medical area
    Identifiers
    urn:nbn:se:liu:diva-179179 (URN)10.3389/fimmu.2021.722118 (DOI)000692811700001 ()34408755 (PubMedID)
    Note

    Funding Agencies|Region Ostergotland (ALF Grants); Gustafsson Foundation; King Gustaf Vs 80-year Anniversary Foundation; King Gustaf V, Queen Victorias Freemasons Foundation; Swedish Rheumatism Association; Royal Swedish Academy of Sciences

    Available from: 2021-09-15 Created: 2021-09-15 Last updated: 2024-10-09
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  • Public defence: 2024-11-01 09:00 Belladonna Hall, building 511/ 10th floor, LinköpingOrder onlineBuy this publication >>
    Beka, Ervin
    Linköping University, Department of Biomedical and Clinical Sciences, Division of Surgery, Orthopedics and Oncology. Linköping University, Faculty of Medicine and Health Sciences. Region Östergötland, Center for Surgery, Orthopaedics and Cancer Treatment, Department of Surgery in Linköping.
    Various aspects of hemithyroidectomy: Towards individualized treatment2024Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    There are mainly two indications in patients with enlarged thyroid for which a hemithyroidectomy is recommended: (1) surgery as a therapeutic procedure to improve compression symptoms and (2) surgery as a diagnostic procedure to confirm or rule out thyroid malignancy. This thesis evaluates which patients benefit more from hemithyroidectomy and examines the patients' perspectives, which can provide knowledge that can be implemented in meetings with patients.  

    Paper I was a preclinical study of fine-needle aspiration cytology (FNAC) from the thyroid gland. The study evaluated if the addition of a molecular BRAF-V600E mutation analysis could detect more papillary thyroid cancers in the palpation-guided FNAC group. The results showed that adding BRAF-V600E mutation analysis might significantly increase the proportion of papillary thyroid cancers diagnosed preoperatively in the palpation-guided FNAC group.  

    Paper II was a retrospective cohort study from a well-established Scandinavian quality register (SQRTPA). Retrospective data for two different hemithyroidectomy indications were collected, to exclude malignancy or as a therapeutic procedure. The study showed that the excised thyroid weight was an independent risk factor for bleeding, and permanent recurrent laryngeal nerve paresis was less common in the excluding malignancy group.  

    Paper III was a prospective cohort study of patients with compressive symptoms who underwent hemithyroidectomy due to an enlarged thyroid. Seventy-two patients filled in four different questionnaires before and after hemithyroidectomy and objective measurements of the enlarged thyroid were registered before the operation. Most of the patients benefited from hemithyroidectomy, however, many patients had voice impairments 6 weeks after the operation. No correlation was found between the symptom changes and the preoperative measurements of the thyroid lobe.

    Paper IV was a qualitative interview study on 16 patients with compression symptoms from an enlarged thyroid who underwent a hemithyroidectomy. The data were analysed using conventional content analysis. The analysis revealed two main categories. Patients experienced postoperative symptoms that affected their daily life and postoperative symptoms that made the patients develop coping strategies. A subcategory showed that the patients had concerns about the future.  

    This thesis reinforces that a successful choice of hemithyroidectomy begins with a well-informed patient and professional counselling based on the patient's condition and preferences. A holistic perspective of the patients is central for individualized treatment. 

    List of papers
    1. Increased diagnostic sensitivity of palpation-guided thyroid nodule fine-needle aspiration cytology by BRAF V600E-mutation analysis
    Open this publication in new window or tab >>Increased diagnostic sensitivity of palpation-guided thyroid nodule fine-needle aspiration cytology by BRAF V600E-mutation analysis
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    2021 (English)In: The journal of pathology. Clinical research, ISSN 2056-4538, Vol. 7, no 6, p. 556-564Article in journal (Refereed) Published
    Abstract [en]

    Papillary thyroid carcinoma (PTC) is the most common type of thyroid cancer and its incidence is increasing. Preoperative diagnosis is warranted in order to avoid two-stage procedures that are associated with additional costs and higher radioactive iodine remnant uptake. In the setting of thyroid cancer, somatic BRAF V600E-mutations are highly specific for PTC and can be analyzed in aspirates from fine-needle aspiration cytology (FNAC). The gold standard to perform FNAC is ultrasound guidance. Here, we analyze whether adding BRAF V600E-mutation analysis could be of value in palpation-guided FNACs. A total of 430 consecutive patients were included. Ultrasound-guided FNACs were performed in 251 patients and 179 patients underwent palpation-guided FNACs. BRAF V600E-mutation analysis was performed using two methods, an allele-specific polymerase chain reaction (PCR) analyzed by capillary gel electrophoresis (PCR/Qiaxcel), and a droplet digital PCR (ddPCR) assay. A total of 80 patients underwent surgery, and histology revealed 25 patients to have PTC. Of the 25 PTCs, 23 (92%) showed a BRAF V600E-mutation. Both mutation analysis methods (PCR/Qiaxcel and ddPCR) produced concordant results. In the ultrasound-guided group, the preoperative diagnostic sensitivity of FNAC using the Bethesda classification alone was very high and additional BRAF V600E-mutation analysis added little to the preoperative diagnostic sensitivity. By contrast, in the palpation-guided group, by adding BRAF V600E-mutation analysis, eight instead of four patients were diagnosed of having PTC. This increase in the diagnostic sensitivity was statistically significant (p &lt; 0.05). The costs per sample were as low as 62 USD (PCR/Qiaxcel and ddPCR) and 35 USD (PCR/Qiaxcel only). Ultrasound-guided FNAC should be aimed for when dealing with thyroid nodules. However, if palpation-guided FNAC cannot be avoided or may be required due to resource utilization, adding BRAF V600E-mutation analysis using the methods described in this study might significantly increase the proportion of preoperatively diagnosed PTCs. The additional costs can be considered very reasonable.

    Place, publisher, year, edition, pages
    Wiley-Blackwell, 2021
    Keywords
    papillary thyroid carcinoma; BRAF; mutation analysis; ultrasound-guided; palpation-guided; fine-needle aspiration cytology; FNAC
    National Category
    Surgery
    Identifiers
    urn:nbn:se:liu:diva-180109 (URN)10.1002/cjp2.231 (DOI)000665025100001 ()34156770 (PubMedID)
    Note

    Funding Agencies|Medical Research Council of Southeast SwedenUK Research & Innovation (UKRI)Medical Research Council UK (MRC) [FORSS-648671, FORSS-861891]

    Available from: 2021-10-08 Created: 2021-10-08 Last updated: 2024-10-01
    2. Hemithyroidectomy, does the indication influence the outcome?
    Open this publication in new window or tab >>Hemithyroidectomy, does the indication influence the outcome?
    2024 (English)In: Langenbeck's archives of surgery (Print), ISSN 1435-2443, E-ISSN 1435-2451, Vol. 409, no 1, article id 1Article in journal (Refereed) Published
    Abstract [en]

    PurposeHemithyroidectomies are mainly performed for two indications, either therapeutically to relieve compression symptoms or diagnostically for suspicious nodule(s). In case of the latter, one could consider the approach to be rather extensive since the majority of patients have no symptoms and will have benign disease. The aim of this study is to investigate the complication rates of diagnostic hemithyroidectomy and to compare it with the complication rates of compressive symptoms hemithyroidectomy.MethodsData from patients who had undergone hemithyroidectomy either for compression symptoms or for excluding malignancy were extracted from a well-established Scandinavian quality register (SQRTPA). The following complications were analyzed: bleedings, wound infections, and paresis of the recurrent laryngeal nerve (RLN). Risk factors for these complications were examined by univariable and multivariable logistic regression.ResultsA total of 9677 patients were included, 3871 (40%) underwent surgery to exclude malignancy and 5806 (60%) due to compression symptoms. In the multivariable analysis, the totally excised thyroid weight was an independent risk factor for bleeding. Permanent (6-12 months after the operation) RLN paresis were less common in the excluding malignancy group (p = 0.03).ConclusionA range of factors interfere and contribute to bleeding, wound infections, and RLN paresis after hemithyroidectomy. In this observational study based on a Scandinavian quality register, the indication "excluding malignancy" for hemithyroidectomy is associated with less permanent RLN paresis than the indication "compression symptoms." Thus, patients undergoing diagnostic hemithyroidectomy can be reassured that this procedure is a safe surgical procedure and does not entail an unjustified risk.

    Place, publisher, year, edition, pages
    SPRINGER, 2024
    Keywords
    Thyroid gland; Hemithyroidectomy; Register study; Complications
    National Category
    Surgery
    Identifiers
    urn:nbn:se:liu:diva-199674 (URN)10.1007/s00423-023-03168-w (DOI)001115580200001 ()38062331 (PubMedID)
    Available from: 2023-12-18 Created: 2023-12-18 Last updated: 2024-10-01
    3. Patient Experiences of Symptoms and Coping Strategies in the Early Postoperative Phase Following Hemithyroidectomy: A Qualitative Interview Study
    Open this publication in new window or tab >>Patient Experiences of Symptoms and Coping Strategies in the Early Postoperative Phase Following Hemithyroidectomy: A Qualitative Interview Study
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    2024 (English)In: JOURNAL OF PATIENT EXPERIENCE, ISSN 2374-3743, Vol. 11, article id 23743735241273580Article in journal (Refereed) Published
    Abstract [en]

    The aim was to explore patients' early experiences of symptoms after hemithyroidectomy and how these symptoms influenced their daily lives. An inductive explorative qualitative research design was performed. Sixteen patients from two hospitals were interviewed between two-three weeks after the surgery. All the patients experienced compression symptoms before the surgery. The study was analyzed with conventional manifest content analysis. The inductive analysis yielded two main categories and one subcategory. The two main categories were: Early postoperative symptoms that caused disadvantage in daily life and Early postoperative symptoms and coping strategies. The subcategory was: Early postoperative experiences of concerns about the future. Key points: 1. Patients experienced early postoperative symptoms that affected their lives in multiple levels, making them develop coping strategies and awaking concerns about remaining symptoms in the future. 2. The effect of hemithyroidectomy influenced patients' daily life in the early postoperative phase considerably. 3. The study shows that tailored preoperative patient information is important. The findings may guide professionals to tailored preoperative information to optimize the care for this patient group.

    Place, publisher, year, edition, pages
    SAGE PUBLICATIONS INC, 2024
    Keywords
    thyroid surgery; postoperative symptoms; hemithyroidectomy; qualitative interviews; content analysis
    National Category
    Nursing
    Identifiers
    urn:nbn:se:liu:diva-207248 (URN)10.1177/23743735241273580 (DOI)001290375700001 ()39139704 (PubMedID)
    Available from: 2024-09-05 Created: 2024-09-05 Last updated: 2024-10-01
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  • Public defence: 2024-11-01 13:00 Key 1, Key-house, LinköpingOrder onlineBuy this publication >>
    Asp, Lene
    Linköping University, Department of Culture and Society, Division of Language, Culture and Interaction. Linköping University, Faculty of Arts and Sciences.
    Voices and Places: Reading Colonial Landscapes as Vibrant Archives2024Doctoral thesis, monograph (Other academic)
    Abstract [en]

    This dissertation challenges the conventional narrative of Danish colonial history by critiquing the predominant reliance on textual records and archives as primary carriers of historical knowledge. Through case studies focused on landscape and landscaping practices, it offers an alternative approach to understanding the past by actively engaging with material heritage in what is conceptualized as a vibrant archive. Utilizing interdisciplinary and practice-led methodologies, from cultural and memory studies to ecocriticism, the research examines and engages with colonial history through case studies in dialog with contemporary interlocutors. Emphasizing the dynamic nature of landscapes as vibrant archives-in-the-making, building on Jane Bennett’s concept of vibrant matter, the dissertation underscores their capacity to both shape and be shaped by diverse actors and forces. This perspective prioritizes ethical considerations in preserving and interpreting cultural heritage, aiming to foster inclusivity and resilience in shaping future landscapes. As landscapes embody multiple pasts that transcend national borders, they reveal a global network of interconnected material heritage. However, prevailing historical understandings often prioritize certain discursive national formations, limiting a comprehensive grasp of global connectivity. By exploring contemporary investments in constructing new relational pasts, the dissertation seeks to broaden the analytical scope and challenge such dominant narratives. Through an exploration of colonial trauma and the enduring impacts of historical violence, the research delves into the entangled relationships between past, present, and future. Additionally, the dissertation investigates the role of sound recordings in creating immersive narratives and enhancing the communication of findings, offering insights into preservation efforts, cultural revitalization projects, and community-led initiatives in a contemporary context. Throughout the research, there is a consistent advocacy for a more just and inclusive approach to caring for the colonial archive within the context of colonial exploitation and ecological crisis. This emphasis on interconnectedness across social, environmental, and cultural dynamics highlights the urgent need to reckon with colonial legacies to promote social and environmental justice.

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  • Public defence: 2024-11-07 13:00 K3, NorrköpingOrder onlineBuy this publication >>
    Blomqvist, Andreas
    Linköping University, Department of Health, Medicine and Caring Sciences, Division of Nursing Sciences and Reproductive Health. Linköping University, Faculty of Medicine and Health Sciences.
    Supporting physical activity in people with heart failure: Novel Tools for Intervention and Assessment2024Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    Background

    Heart failure is a common disease affecting well over 20 million people worldwide. In addition to pharmacological therapy, self-care is efficacious in improving prognosis and generating symptom relief in this population and one important part of self-care behaviour is physical activity. Physical inactivity and sedentary behaviour negatively affect prognosis for the heart failure population but achieving sustained behaviour change relating to physical activity is challenging. There is research published on how to positively influence behaviours relating to physical activity and one means by which this can be achieved is using mobile health applications. One such mobile health tool, which is designed to enhance self-care behaviour is called Optilogg and it constitutes an appropriate platform on which to develop a novel tool to address sedentary behaviour and physical inactivity.

    Aim

    The aim of this thesis was to develop and evaluate tools for assessing and supporting physical activity in patients with heart failure.

    Methods

    This thesis describes the development and testing of two tools, through four scientific studies, employing both quantitative and qualitative methods of data collection and analyses. Study I (n = 106) was a cross-sectional study to test a single item self-report screening tool for identifying physically inactive people with heart failure. Study II (n = 10) describes the mixed-method evaluation of the intervention tool called the Activity Coach, along with the development process. Studies III and IV served to evaluate the Activity Coach in terms of study design, potential outcomes and user experiences. Study III (n = 20) was a pilot randomized controlled clinical trial and Study IV (n = 10) a qualitative study using thematic analysis.

    Results

    The screening tool studied (Study I) had a high specificity (92%), but low sensitivity (30%) in correctly identifying physically inactive people and correlated significantly (ρ = 0.24, p = 0.016) with an objective measure of physical activity. The whole development process of the Activity Coach took 76 months, with the process of defining and implementing it taking 21 months. Key development elements included co-design, defining factor-action pairs, intervention theory, and mixed-method evaluations. The mixed-methods analyses (Study II) showed an acceptable system adherence of 61% and that it could increase motivation to be physically active, but that user selection likely matters, and too physically active people should not be targeted. The pilot randomized controlled clinical trial (Study III) showed that recruiting people for this type of study, while also screening for physical inactivity was challenging with a recruitment rate of 22%. There were significant effects on subjective goal-attainment and health-related quality of life, and a trend towards reduced sedentary behaviour. Following improvements made prior to Study III, the system adherence increased to 69%. The qualitative analysis (Study IV) showed that the Activity Coach was user-friendly, increased motivation to be physically active and that users experienced positive effects on physical health and emotional well-being.

    Conclusions

    A single-item self-report screening tool may be used to identify those in extra need of intervention. A pilot trial showed challenges in recruiting participants. It also showed high system adherence and potential benefits in subjective goal-attainment and health-related quality of life. Qualitative analyses of user experience highlighted perceptions of user-friendliness and a sense of enhanced well-being. Further validation and updates are recommended before a full efficacy trial is undertaken.

    List of papers
    1. Utility of single-item questions to assess physical inactivity in patients with chronic heart failure
    Open this publication in new window or tab >>Utility of single-item questions to assess physical inactivity in patients with chronic heart failure
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    2020 (English)In: ESC Heart Failure, E-ISSN 2055-5822, Vol. 7, no 4, p. 1467-1476Article in journal (Refereed) Published
    Abstract [en]

    Aim The purpose of this study was to explore the utility of two single-item self-report (SR) questions to assess physical inactivity in patients with heart failure (HF). Methods and results This is a cross-sectional study using data from 106 patients with HF equipped with accelerometers for 1 week each. Two SR items relating to physical activity were also collected. Correlations between accelerometer activity counts and the SR items were analysed. Patients were classified as physically active or inactive on the basis of accelerometer counts, and the SR items were used to try to predict that classification. Finally, patients were classified as having high self-reported physical activity or low self-reported physical activity, on the basis of the SR items, and the resulting groups were analysed for differences in actual physical activity. There were significant but weak correlations between the SR items and accelerometer counts: rho = 0.24, P = 0.016 for SR1 and rho = 0.21, P = 0.033 for SR2. Using SR items to predict whether a patient was physically active or inactive produced an area under the curve of 0.62 for SR1, with a specificity of 92% and a sensitivity of 30%. When dividing patients into groups on the basis of SR1, there was a significant difference of 1583 steps per day, or 49% more steps in the high self-reported physical activity group (P &lt; 0.001). Conclusions There might be utility in the single SR question for high-specificity screening of large populations to identify physically inactive patients in order to assign therapeutic interventions efficiently where resources are limited.

    Place, publisher, year, edition, pages
    WILEY PERIODICALS, INC, 2020
    Keywords
    Physical inactivity; Heart failure; Accelerometer; Self-report
    National Category
    Physiotherapy
    Identifiers
    urn:nbn:se:liu:diva-166195 (URN)10.1002/ehf2.12709 (DOI)000530372400001 ()32372549 (PubMedID)
    Note

    Funding Agencies|Swedish National Science Council [K2013-69X-22302-01-3, 2016-01390]; Swedish National Science Council/Swedish research council for health, working life and welfare, VR-FORTE [2014-4100]; Swedish Heart and Lung AssociationSwedish Heart-Lung Foundation [E085/12]; Swedish Heart and Lung FoundationSwedish Heart-Lung Foundation [20130340, 20160439]; Vardal Foundation [2014-0018]; Medical Research Council of Southeast Sweden [FORSS 474681]

    Available from: 2020-06-09 Created: 2020-06-09 Last updated: 2024-10-04
    2. Usability and feasibility analysis of an mHealth-tool for supporting physical activity in people with heart failure
    Open this publication in new window or tab >>Usability and feasibility analysis of an mHealth-tool for supporting physical activity in people with heart failure
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    2024 (English)In: BMC Medical Informatics and Decision Making, E-ISSN 1472-6947, Vol. 24, no 1, article id 44Article in journal (Refereed) Published
    Abstract [en]

    BackgroundPhysical inactivity and a sedentary lifestyle are common among people with heart failure (HF), which may lead to worse prognosis. On an already existing mHealth platform, we developed a novel tool called the Activity coach, aimed at increasing physical activity. The aim of this study was to evaluate the usability of the Activity coach and assess feasibility of outcome measures for a future efficacy trial.MethodsA mixed-methods design was used to collect data. People with a HF diagnosis were recruited to use the Activity coach for four weeks. The Activity coach educates the user about physical activity, provides means of registering daily physical activity and helps the user to set goals for the next week. The usability was assessed by analysing system user logs for adherence, reported technical issues and by interviews about user experiences. Outcome measures assessed for feasibility were objective physical activity as measured by an accelerometer, and subjective goal attainment. Progression criteria for the usability assessment and for the proposed outcomes, were described prospectively.ResultsTen people with HF were recruited, aged 56 to 78 with median age 72. Data from nine of the ten study participants were included in the analyses. Usability: The Activity coach was used 61% of the time and during the first week two study participants called to seek technical support. The Activity coach was found to be intuitive and easy to use by all study participants. An increased motivation to be more physically active was reported by six of the nine study participants. However, in spite of feeling motivated, four reported that their habits or behaviours had not been affected by the Activity coach. Feasibility: Data was successfully stored in the deployed hardware as intended and the accelerometers were used enough, for the data to be analysable. One finding was that the subjective outcome goal attainment, was challenging to collect. A proposed mitigator for this is to use pre-defined goals in future studies, as opposed to having the study participants be completely free to formulate the goals themselves.ConclusionsIt was confirmed that the Activity coach was easy to use. Furthermore, it might stimulate increased physical activity in a population of people with HF, who are physically inactive. The outcomes investigated seem feasible to include in a future efficacy trial.Trial registrationClinicalTrials.gov identifier: NCT05235763. Date of first registration: 11/02/2022.

    Place, publisher, year, edition, pages
    BMC, 2024
    Keywords
    mHealth; Heart failure; Physical activity; Disease management; Development; Co-design
    National Category
    Other Health Sciences
    Identifiers
    urn:nbn:se:liu:diva-201174 (URN)10.1186/s12911-024-02452-z (DOI)001160563500001 ()38347499 (PubMedID)
    Note

    Funding Agencies|Linkping University

    Available from: 2024-02-26 Created: 2024-02-26 Last updated: 2024-10-04
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  • Public defence: 2024-11-08 13:00 Belladonna, Building 511, LinköpingOrder onlineBuy this publication >>
    Frampton, Damon
    Linköping University, Department of Biomedical and Clinical Sciences, The Division of Cell and Neurobiology. Linköping University, Faculty of Medicine and Health Sciences.
    Endogenous and Exogenous Molecules Modulating Voltage-Gated Potassium Channels2024Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    The superfamily of voltage-gated potassium (KV) channels is crucial for the normal function of several tissues and represents an attractive pharmacological target for treating disorders such as epilepsy and cardiac arrhythmias. However, any drug designed to target a KV channel must be capable of discriminating between different members within the superfamily, lest they plague the user with deleterious side effects. Such rational design requires structural and functional insight into how the selectivity of a molecule can be tailored to suit the intended target.  

    This thesis combines the use of electrophysiological and computational techniques to investigate the molecular basis for how the function of hKV7 and hERG channels can be modulated by different lipophilic compounds with known or suspected effects on ion channels. These include polyunsaturated fatty acids (PUFAs), cannabidiol (CBD), and synthetic cannabinoid receptor agonists (SCRAs).   

    Using the two-electrode voltage clamp technique on Xenopus oocytes, we find that both PUFAs and CBD modulate the function of hKV7 channels in subtype-specific manners. PUFAs facilitated the activation of hKV7 channels, except for hKV7.4 channels which were instead inhibited. Molecular dynamics simulations revealed that structural differences in the voltage-sensing domain of hKV7.4 conferred a unique, inhibitory PUFA interaction site absent in the other hKV7 subtypes. Once this site was neutralised by mutagenesis, PUFAs facilitated hKV7.4 activation. In the case of CBD, we observed three different responses: inhibition of channels with hKV7.1 subunits, potentiated voltage-sensitivity of channels with hKV7.2 or hKV7.3 subunits and enhanced maximum conductance of channels with hKV7.4 or hKV7.5 subunits. However, these responses were evoked from the same interaction site in the pore domain, indicating a more complex subtype-specific mechanism of action. Finally, using an automated patch-clamp system we screened 36 different SCRAs on the cardiac channels responsible for repolarisation: hERG and hKV7.1/KCNE1. We find 28 of the SCRAs to be inhibitors of hERG and 22 to be inhibitors of hKV7.1/KCNE1. Molecular dynamics simulations suggest the increased susceptibility of hERG to SCRA-mediated inhibition may be due to a unique central cavity site that is absent from the pore domain of hKV7.1/KCNE1.   

    In conclusion, structurally diverse lipophilic molecules of endogenous and exogenous origins can interact with KV channels and influence their function by enhancing or interfering with functional domains. In some instances, structural differences in the channel protein can explain the discrepancies in pharmacology. These findings have implications for both pharmacology (informing rational drug design) and toxicology (identifying targets through which adverse effects may occur).   

    List of papers
    1. Subtype-specific responses of hKv7.4 and hKv7.5 channels to polyunsaturated fatty acids reveal an unconventional modulatory site and mechanism
    Open this publication in new window or tab >>Subtype-specific responses of hKv7.4 and hKv7.5 channels to polyunsaturated fatty acids reveal an unconventional modulatory site and mechanism
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    2022 (English)In: eLIFE, E-ISSN 2050-084X, Vol. 11, article id e77672Article in journal (Refereed) Published
    Abstract [en]

    The K(V)7.4 and K(V)7.5 subtypes of voltage -gated potassium channels play a role in important physiological processes such as sound amplification in the cochlea and adjusting vascular smooth muscle tone. Therefore, the mechanisms that regulate K(V)7.4 and K(V)7.5 channel function are of interest. Here, we study the effect of polyunsaturated fatty acids (PUFAs) on human K(V)7.4 and KV7.5 channels expressed in Xenopus oocytes. We report that PUFAs facilitate activation of hK(V)7.5 by shifting the V50 of the conductance versus voltage (G(V)) curve toward more negative voltages. This response depends on the head group charge, as an uncharged PUFA analogue has no effect and a positively charged PUFA analogue induces positive V-50 shifts. In contrast, PUFAs inhibit activation of hK(V)7.4 by shifting V-50 toward more positive voltages. No effect on V-50 of hK(V)7.4 is observed by an uncharged or a positively charged PUFA analogue. Thus, the hK(V)7.5 channels response to PUFAs is analogous to the one previously observed in hK(V)7.1-7.3 channels, whereas the hK(V)7.4 channel response is opposite, revealing subtype-specific responses to PUFAs. We identify a unique inner PUFA interaction site in the voltage-sensing domain of hKV7.4 underlying the PUFA response, revealing an unconventional mechanism of modulation of hK(V)7.4 by PUFAs.

    Place, publisher, year, edition, pages
    eLife Sciences Publications Ltd, 2022
    Keywords
    docosahexaenoic acid; electrophysiology; KCNQ; lipid; molecular dynamics simulations; omega 3; Xenopus
    National Category
    Biophysics
    Identifiers
    urn:nbn:se:liu:diva-185818 (URN)10.7554/eLife.77672 (DOI)000806620500001 ()35642964 (PubMedID)
    Note

    Funding Agencies|Swedish Research Council [2017-02040, 2018-04905, 2021-01885]; Swedish Society for Medical Research

    Available from: 2022-06-14 Created: 2022-06-14 Last updated: 2024-10-02
    2. Subtype-specific modulation of human K(V)7 channels by the anticonvulsant cannabidiol through a lipid-exposed pore-domain site
    Open this publication in new window or tab >>Subtype-specific modulation of human K(V)7 channels by the anticonvulsant cannabidiol through a lipid-exposed pore-domain site
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    2023 (English)In: British Journal of Pharmacology, ISSN 0007-1188, E-ISSN 1476-5381, Vol. 180, no 23, p. 2956-2972Article in journal (Refereed) Published
    Abstract [en]

    Background and PurposeCannabidiol (CBD) is used clinically as an anticonvulsant. Its precise mechanism of action has remained unclear. CBD was recently demonstrated to enhance the activity of the neuronal K(V)7.2/7.3 channel, which may be one important contributor to CBD anticonvulsant effect. Curiously, CBD inhibits the closely related cardiac K(V)7.1/KCNE1 channel. Whether and how CBD affects other K(V)7 subtypes remains uninvestigated and the CBD interaction sites mediating these diverse effects remain unknown. Experimental ApproachHere, we used electrophysiology, molecular dynamics simulations, molecular docking and site-directed mutagenesis to address these questions. Key ResultsWe found that CBD modulates the activity of all human K(V)7 subtypes and that the effects are subtype dependent. CBD enhanced the activity of K(V)7.2-7.5 subtypes, seen as a V-50 shift towards more negative voltages or increased maximum conductance. In contrast, CBD inhibited the K(V)7.1 and K(V)7.1/KCNE1 channels, seen as a V-50 shift towards more positive voltages and reduced conductance. In K(V)7.2 and K(V)7.4, we propose a CBD interaction site at the subunit interface in the pore domain that overlaps with the interaction site of other compounds, notably the anticonvulsant retigabine. However, CBD relies on other residues for its effects than the conserved tryptophan that is critical for retigabine effects. We propose a similar, though not identical CBD site in K(V)7.1, with a non-conserved phenylalanine being important. Conclusions and ImplicationsWe identify novel targets of CBD, contributing to a better understanding of CBD clinical effects and provide mechanistic insights into how CBD modulates different K(V)7 subtypes.

    Place, publisher, year, edition, pages
    WILEY, 2023
    Keywords
    electrophysiology; KCNQ; molecular dynamics; phytocannabinoid
    National Category
    Pharmaceutical Sciences
    Identifiers
    urn:nbn:se:liu:diva-196630 (URN)10.1111/bph.16183 (DOI)001036807200001 ()37377025 (PubMedID)
    Note

    Funding Agencies|Goeran Gustafsson Foundation; European Research Council (ERC) [850622]; Swedish Research Council [VR2018-04905, VR2021-01885]; Science for Life Laboratory; Marie-Sklodowska Curie Fellowship Lipopeutics [898762]

    Available from: 2023-08-16 Created: 2023-08-16 Last updated: 2024-10-02
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  • Public defence: 2024-11-15 13:00 Belladonna, building 511, LinköpingOrder onlineBuy this publication >>
    Johansson, Lovisa
    Linköping University, Department of Biomedical and Clinical Sciences, The Division of Cell and Neurobiology. Linköping University, Faculty of Medicine and Health Sciences.
    The Impact of Endosomes, Autophagy and Extracellular Vesicles on Alzheimer’s Disease2024Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    Alzheimer’s disease (AD) is the leading cause of dementia, and clinical symptoms develop due to neuronal death. This neurodegeneration is believed to be primarily initiated by the abnormal accumulation of Amyloid β (Aβ) peptide and tau protein aggregates. Among these, Aβ accumulation is considered the primary driver of AD and forms the main focus of this thesis. Different alloforms of Aβ (e.g. Aβ1-40 and Aβ1-42) are produced by differential cleavage of the Amyloid precursor protein (APP). The lifecycles of APP and Aβ depend on their localization to different cellular compartments such as endosomes, but they can also be trafficked out of the cells in exosomes, a type of extracellular vesicle (EV). It is hypothesized that halting the spread and accumulation of Aβ via EVs could slow neurodegeneration and disease progression. However, the mechanisms underlying Aβ packaging into these vesicles and how other AD-related cellular dysfunctions influence EV propagation, remain largely unclear. Understanding these mechanisms could be crucial for identifying new treatment targets. This thesis aims to elucidate some of these gaps.   

    Differences in Aβ fibril conformations have been hypothesized to result in diverse clinical phenotypes of AD. Therefore, Paper I examined how different ratios of Aβ1-40 to Aβ1-42 affect fibril conformation. Given that there is no standard timeframe for fibril formation, we further investigated the effect of maturation time. Using electron microscopy, different dyes, and antibodies, we found that both Aβ1-40:42 ratio and maturation significantly influenced fibril conformation. Fibrils with higher Aβ1-42 ratio showed increased cellular association, although this did not substantially impact cytotoxicity and autophagy.

    Mutations or dysfunctions related to endosomal trafficking (e.g. dysfunction of the retromer subunit Vps35), can cause Aβ accumulation but the impact on exosome biogenesis and EV release is lacking. Therefore, Paper II investigated the effect of Vps35 knockout (KO) on exosome biogenesis and EV cargo during Aβ challenge. We found that lack of Vps35 resulted in lower EV abundance, caused by a decrease in exosome biogenesis-related proteins, leading to increased Aβ cargo. Aβ challenge also led to increased EV release and affected EV cargo, revealing new mechanisms by which Vps35 dysfunction contributes to Aβ accumulation.  

    Aβ is hypothesized to be released in exosomes via a neutral sphingomyelinase 2 (nSMase2)-dependent pathway. However, knowledge regarding how Aβ is packaged is still lacking. Therefore, Paper III aimed to confirm the nSmase2-dependency and to investigate whether the Aβ-interacting cellular prion protein (PrPC) could influence Aβ packaging into exosomes. Our findings confirmed that Aβ release occurs via an nSMase2-dependent pathway, independent of PrPC. Surprisingly, lack of PrPC caused cellular Aβ accumulation, changes to exosome biogenesis-related proteins, and an increase in EV production.   

    Autophagy is heavily involved in both the accumulation and degradation of Aβ and has been connected to EV abundance. Therefore, Paper IV examined the role of autophagy in Aβ accumulation and EV dynamics. Using a cross between an Atg7 conditional KO mouse and a knock in APP mouse (with Swedish and Iberian mutation, APPNL-F) we could demonstrate that plaques and intracellular Aβ was decreased while EV abundance was increased upon autophagy deficiency. However, the Aβ content of EVs was not altered. With additional mutations (Arctic mutation, APPNL-G-F), leading to excessive Aβ production in autophagy deficient mice, similar decreases in Aβ plaque were seen but intracellular Aβ remained unchanged. This resulted in different cell death mechanisms, gamma oscillations, and behavioral outcomes between the autophagy deficient APPNL-F and APPNL-G-F mice.   In conclusion, this thesis expands our understanding of the impact of amyloid conformation, endosomal trafficking dysfunction, autophagy dysfunction, exosome biogenesis and EVs dynamics in the progression of AD. 

    List of papers
    1. Amyloid beta 1-40 and 1-42 fibril ratios and maturation level cause conformational differences with minimal impact on autophagy and cytotoxicity
    Open this publication in new window or tab >>Amyloid beta 1-40 and 1-42 fibril ratios and maturation level cause conformational differences with minimal impact on autophagy and cytotoxicity
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    2024 (English)In: Journal of Neurochemistry, ISSN 0022-3042, E-ISSN 1471-4159Article in journal (Refereed) Epub ahead of print
    Abstract [en]

    The amyloid beta (A beta) peptide has a central role in Alzheimer's disease (AD) pathology. The peptide length can vary between 37 and 49 amino acids, with A beta 1-42 being considered the most disease-related length. However, A beta 1-40 is also found in A beta plaques and has shown to form intertwined fibrils with A beta 1-42. The peptides have previously also shown to form different fibril conformations, proposed to be related to disease phenotype. To conduct more representative in vitro experiments, it is vital to uncover the impact of different fibril conformations on neurons. Hence, we fibrillized different A beta 1-40:42 ratios in concentrations of 100:0, 90:10, 75:25, 50:50, 25:75, 10:90 and 0:100 for either 24 h (early fibrils) or 7 days (aged fibrils). These were then characterized based on fibril width, LCO-staining and antibody-staining. We further challenged differentiated neuronal-like SH-SY5Y human cells with the different fibrils and measured A beta content, cytotoxicity and autophagy function at three different time-points: 3, 24, and 72 h. Our results revealed that both A beta 1-40:42 ratio and fibril maturation affect conformation of fibrils. We further show the impact of these conformation changes on the affinity to commonly used A beta antibodies, primarily affecting A beta 1-40 rich aggregates. In addition, we demonstrate uptake of the aggregates by neuronally differentiated human cells, where aggregates with higher A beta 1-42 ratios generally caused higher cellular levels of A beta. These differences in A beta abundance did not cause changes in cytotoxicity nor in autophagy activation. Our results show the importance to consider conformational differences of A beta fibrils, as this can have fundamental impact on A beta antibody detection. Overall, these insights underline the need for further exploration of the impact of conformationally different fibrils and the need to reliably produce disease relevant A beta aggregates.image

    Place, publisher, year, edition, pages
    WILEY, 2024
    Keywords
    Alzheimer's disease; amyloid beta; conformation; fibril maturation; LCO
    National Category
    Cell and Molecular Biology
    Identifiers
    urn:nbn:se:liu:diva-207183 (URN)10.1111/jnc.16201 (DOI)001289211800001 ()39133499 (PubMedID)
    Note

    Funding Agencies|Hans- Gabriel och Alice Trolle- Wachtmeisters stiftelse for medicinsk forskning; Gustav V and Drottning Viktorias Foundation; Kurt and Helena Walldens research foundation; Demensfonden; Vetenskapsradet [2019-01016, 2023- 03931]; Swedish Brain foundation [ALZ2019-0004, ALZ2022-0004, FO2020-0207]; Swedish Alzheimer foundation; Region Ostergotland; Linkopings Universitet; Swedish Research Council [2023-03931, 2019-01016] Funding Source: Swedish Research Council; Formas [2019-01016] Funding Source: Formas

    Available from: 2024-09-04 Created: 2024-09-04 Last updated: 2024-10-09
    2. Lack of cellular prion protein causes Amyloid ß accumulation, increased extracellular vesicle abundance, and changes to exosome biogenesis proteins
    Open this publication in new window or tab >>Lack of cellular prion protein causes Amyloid ß accumulation, increased extracellular vesicle abundance, and changes to exosome biogenesis proteins
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    2024 (English)In: Molecular and Cellular Biochemistry, ISSN 0300-8177, E-ISSN 1573-4919Article in journal (Refereed) Epub ahead of print
    Abstract [en]

    Alzheimer's disease (AD) progression is closely linked to the propagation of pathological Amyloid beta (A beta), a process increasingly understood to involve extracellular vesicles (EVs), namely exosomes. The specifics of A beta packaging into exosomes remain elusive, although evidence suggests an ESCRT (Endosomal Sorting Complex Required for Transport)-independent origin to be responsible in spreading of AD pathogenesis. Intriguingly, PrPC, known to influence exosome abundance and bind oligomeric A beta (oA beta), can be released in exosomes via both ESCRT-dependent and ESCRT-independent pathways, raising questions about its role in oA beta trafficking. Thus, we quantified A beta levels within EVs, cell medium, and intracellularly, alongside exosome biogenesis-related proteins, following deletion or overexpression of PrPC. The same parameters were also evaluated in the presence of specific exosome inhibitors, namely Manumycin A and GW4869. Our results revealed that deletion of PrPC increases intracellular A beta accumulation and amplifies EV abundance, alongside significant changes in cellular levels of exosome biogenesis-related proteins Vps25, Chmp2a, and Rab31. In contrast, cellular expression of PrPC did not alter exosomal A beta levels. This highlights PrPC's influence on exosome biogenesis, albeit not in direct A beta packaging. Additionally, our data confirm the ESCRT-independent exosome release of A beta and we show a direct reduction in Chmp2a levels upon oA beta challenge. Furthermore, inhibition of opposite exosome biogenesis pathway resulted in opposite cellular PrPC levels. In conclusion, our findings highlight the intricate relationship between PrPC, exosome biogenesis, and A beta release. Specifically, they underscore PrPC's critical role in modulating exosome-associated proteins, EV abundance, and cellular A beta levels, thereby reinforcing its involvement in AD pathogenesis.Graphical abstractThere are two main exosome biogenesis pathways: ESCRT dependent and ESCRT independent. In this study, we explored the effect of the cellular prion protein (PrPC) on the release of Amyloid beta via exosomes. Our findings demonstrate that Amyloid beta mainly is released via an ESCRT-independent pathway, independent of PrPC. However, lack of PrPC resulted in upregulation of the ESCRT-dependent proteins Tsg101 and VPS25, a decrease in Chmp2a, and an overall increase in extracellular vesicles. Lack of PrPC also caused an accumulation of cellular, but not exosomal, Amyloid beta.

    Place, publisher, year, edition, pages
    SPRINGER, 2024
    Keywords
    Alzheimer's disease; Amyloid beta; Extracellular vesicles; Exosome; Prion; ESCRT
    National Category
    Medical Biotechnology (with a focus on Cell Biology (including Stem Cell Biology), Molecular Biology, Microbiology, Biochemistry or Biopharmacy)
    Identifiers
    urn:nbn:se:liu:diva-206394 (URN)10.1007/s11010-024-05059-0 (DOI)001263433000001 ()38970706 (PubMedID)
    Note

    Funding Agencies|Linkoping University; Swedish Research Council ("Vetenskapsradet") [2019-01016]; Swedish Alzheimer foundation ("Alzheimerfonden"); Swedish Brain Foundation ("Hjarnfonden"); Hans-Gabriel and Alice Trolle-Wachtmeister Foundation for Medical Research; Swedish Dementia Foundation ("Demensfonden"); Kurt and Helena Walldens research foundation; Linkoping University; Region Ostergotland; Lions research foundation; Eva Olsson's foundation; Health foundation; Canadian Institutes of Health Research (CIHR) Project Grant; University of Calgary Eyes High Postdoctoral Recruitment Scholarships; CIHR; Banting fellowship through CIHR; Alberta Innovates Postdoctoral Scholarship

    Available from: 2024-08-16 Created: 2024-08-16 Last updated: 2024-10-09
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  • Public defence: 2024-11-21 13:15 Key 1, Key-building, LinköpingOrder onlineBuy this publication >>
    Johansson, Robert
    Linköping University, Department of Computer and Information Science, Human-Centered Systems. Linköping University, Faculty of Arts and Sciences.
    Empirical Studies in Machine Psychology2024Doctoral thesis, monograph (Other academic)
    Abstract [en]

    This thesis presents Machine Psychology as an interdisciplinary paradigm that integrates learning psychology principles with an adaptive computer system for the development of Artificial General Intelligence (AGI). By synthesizing behavioral psychology with a formal intelligence model, the Non-Axiomatic Reasoning System (NARS), this work explores the potential of operant conditioning paradigms to advance AGI research. 

    The thesis begins by introducing the conceptual foundations of Machine Psychology, detailing its alignment with the theoretical constructs of learning psychology and the formalism of NARS. It then progresses through a series of empirical studies designed to systematically investigate the emergence of increasingly complex cognitive behaviors as NARS interacts with its environment. 

    Initially, operant conditioning is established as a foundational principle for developing adaptive behavior with NARS. Subsequent chapters explore increasingly sophisticated cognitive capabilities, all studied with NARS using experimental paradigms from operant learning psychology: Generalized identity matching, Functional equivalence, and Arbitrarily Applicable Relational Responding. 

    Throughout this research, Machine Psychology is demonstrated to be a promising framework for guiding AGI research, allowing both the manipulation of environmental contingencies and the system’s intrinsic logical processes. The thesis contributes to AGI research by showing how using operant psychological paradigms with NARS can enable cognitive abilities similar to human cognition. These findings set the stage for AGI systems that learn and adapt more like humans, potentially advancing the creation of more general and flexible AI.  

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  • Public defence: 2024-11-22 13:00 Fornborgen, NorrköpingOrder onlineBuy this publication >>
    Spetz, Kristina
    Linköping University, Department of Biomedical and Clinical Sciences, Division of Surgery, Orthopedics and Oncology. Linköping University, Faculty of Medicine and Health Sciences. Region Östergötland, Center for Diagnostics, Department of Clinical Pharmacology.
    Vitamins and Minerals after Bariatric Surgery: Adherence and Deficiencies2024Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    Obesity is a complex, chronic disease that increases the risk of other serious medical conditions. Bariatric surgery provides long-term weight loss and remission of obesity-related comorbidities. Currently, about 1% of the Swedish population have undergone bariatric surgery. A side effect of the bariatric operations is an increased risk of micronutrient deficiencies, which can lead to nutritional complications, including anemia. Therefore, a lifelong vitamin and mineral supplementation is recommended.

    This thesis aims to assess real-world use of vitamin and mineral supplements after bariatric surgery with a particular focus on adherence and patterns of biochemical deficiencies.

    Study I is a cohort study assessing adherence to vitamin and mineral supplements and development of biochemical deficiencies two years after bariatric surgery.

    Study II validates the psychometric properties of the patient questionnaire 5-item Medication Adherence Report Scale (MARS-5) in measuring adherence to vitamin and mineral supplementation after bariatric surgery.

    Study III is a randomized controlled trial evaluating the effect of the PromMera smartphone application, designed to improve adherence to vitamin and mineral supplements after bariatric surgery.

    Study IV is a cross-sectional registry study assessing prevalence of anemia up to 10 years after bariatric surgery and factors associated with anemia following bariatric surgery in a Swedish national cohort.

    In this thesis it is concluded that: 1) Poor adherence to vitamin and mineral supplementation after bariatric surgery is a concern, and about 10% of patients discontinue supplementation within two years after surgery. 2) The patient questionnaire MARS-5 may be a useful tool in identifying patients with poor adherence to vitamin and mineral supplementation. 3) The PromMera smartphone application, designed to support adherence to vitamin and mineral supplementation after bariatric surgery, demonstrated no long-term benefits for adherence. 4) Five years after bariatric surgery, nearly one in five individuals in the Swedish cohort who have undergone bariatric surgery have anemia. Undergoing gastric bypass surgery (as compared to sleeve gastrectomy), female sex, large weight loss and young age at surgery is associated with an increased risk of anemia.

    List of papers
    1. Adherence to vitamin and mineral supplementation after bariatric surgery – A two-year cohort study
    Open this publication in new window or tab >>Adherence to vitamin and mineral supplementation after bariatric surgery – A two-year cohort study
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    2022 (English)In: Obesity Research and Clinical Practice, ISSN 1871-403X, E-ISSN 1878-0318, Vol. 16, no 5, p. 407-412Article in journal (Refereed) Published
    Abstract [en]

    Background: Lifelong vitamin and mineral supplementation is recommended after bariatric surgery to prevent nutritional deficiencies, but it is not clear to which extent patients adhere to the recommended medication. The aim of this study was to assess adherence to supplementation. Additionally, we assessed predictors of low adherence and biochemical deficiencies.Methods: 263 adults were followed two years post bariatric surgery (89.4 % Roux-en-Y gastric bypass, 10.6 % sleeve gastrectomy) regarding adherence to calcium-vitamin D, vitamin B12 and iron. Pharmacy refill data was used to objectively capture adherence-rate. Predictors of low adherence were assessed via questionnaires and medical records. Blood sampling was performed preoperatively, and 1-and 2-years post-surgery.Results: About 60 % of the study participants had high adherence-rate (>= 80 %) two years post-surgery, but a significant proportion had discontinued the intended lifelong supplementation: 15 % for calcium-vitamin D and 12 % for B12. Biochemical deficiencies were uncommon two years after surgery, both in adherent and non -persistent subjects, except for a 10 % prevalence of anemia. Younger age, experience of side effects, mental health problems and no regular use of medication before surgery, were factors associated with low adherence.Conclusion: Substantial variation existed in adherence to supplementation regimens after bariatric surgery during the first two years after bariatric surgery, but biochemical deficiencies were rare. The results indicate need for tailored follow-up and strategies to support long-term persistence.

    Place, publisher, year, edition, pages
    Elsevier, 2022
    Keywords
    Bariatric surgery, Gastric Bypass, Sleeve gastrectomy, Vitamin and mineral. supplementation, Adherence, Compliance, Biochemical deficiencies, Micronutrient, deficiencies
    National Category
    Basic Medicine
    Identifiers
    urn:nbn:se:liu:diva-188720 (URN)10.1016/j.orcp.2022.09.001 (DOI)000892630600008 ()36151032 (PubMedID)
    Available from: 2022-09-22 Created: 2022-09-22 Last updated: 2024-10-10
    2. Using the 5-Item Medication Adherence Report Scale (MARS-5) to Screen for Non-adherence to Vitamin and Mineral Supplementation After Bariatric Surgery
    Open this publication in new window or tab >>Using the 5-Item Medication Adherence Report Scale (MARS-5) to Screen for Non-adherence to Vitamin and Mineral Supplementation After Bariatric Surgery
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    2024 (English)In: Obesity Surgery, ISSN 0960-8923, E-ISSN 1708-0428Article in journal (Refereed) Epub ahead of print
    Abstract [en]

    IntroductionPoor adherence to recommended vitamin and mineral supplementation after bariatric surgery is common and challenging for healthcare professionals to identify. There are several questionnaires for self-reporting of adherence to chronic medication, but none has so far been evaluated for assessment of adherence to vitamin and mineral supplementation after bariatric surgery. The aim of this study was to assess the accuracy of the 5-item Medication Adherence Report Scale (MARS-5) in measuring adherence to vitamin and mineral supplementation post bariatric surgery (gastric bypass or sleeve gastrectomy).MethodThe psychometric properties of MARS-5 for vitamin and mineral supplementation were validated in two cohorts: one at 1 year post bariatric surgery (n = 120) and the other at 2 years post-surgery (n = 211). MARS-5 was compared to pharmacy refill data for vitamin B12 and combined calcium/vitamin D as reference.ResultsCorrelation analyses demonstrated that the MARS-5 had acceptable validity compared to objectively measured adherence rates from pharmacy refill data (calculated as continuous, multiple-interval measures of medication availability/gaps-coefficient ranged from 0.49 to 0.54). Internal reliability (Cronbach's alpha) was high: 0.81 and 0.95, respectively. There was a clear ceiling effect where one out of three had a maximum score on MARS-5.ConclusionMARS-5 demonstrated acceptable psychometric properties for assessment of adherence to vitamin and mineral supplementation post bariatric surgery.

    Place, publisher, year, edition, pages
    SPRINGER, 2024
    Keywords
    Adherence; Compliance; Gastric bypass; Sleeve gastrectomy; Bariatric surgery; Vitamin; Mineral; Deficiencies; Obesity
    National Category
    Surgery
    Identifiers
    urn:nbn:se:liu:diva-200510 (URN)10.1007/s11695-023-07027-x (DOI)001136126300002 ()38177555 (PubMedID)
    Note

    Funding Agencies|Linkping University

    Available from: 2024-01-30 Created: 2024-01-30 Last updated: 2024-10-10
    3. A smartphone application to improve adherence to vitamin and mineral supplementation after bariatric surgery
    Open this publication in new window or tab >>A smartphone application to improve adherence to vitamin and mineral supplementation after bariatric surgery
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    2022 (English)In: Obesity, ISSN 1930-7381, E-ISSN 1930-739X, Vol. 30, no 10, p. 1973-1982Article in journal (Refereed) Published
    Abstract [en]

    Objective This trial evaluated a smartphone applications effectiveness in improving adherence to vitamin and mineral supplementation postoperatively. Methods This study was a randomized controlled trial comprising 140 patients undergoing bariatric surgery (gastric bypass or sleeve gastrectomy). Participants were randomized 1:1 to the 12-week intervention, using the smartphone application PromMera, or to standard care. The primary end point was adherence to vitamin and mineral supplementation. Results Initiation rate and overall adherence to supplementation were high in both groups. Change in objectively measured adherence rate from before the intervention to 1 year post surgery, measured with pharmacy refill data, did not differ between groups for vitamin B-12 (-9.6% [SD = 27%] vs. -9.3% [SD = 30%]; p = 0.48) or calcium/vitamin D (-12.3% [SD = 29%] vs. -11.5% [SD = 32%]; p = 0.44). A modest effect on the secondary end point (subjectively measured adherence, using the Medication Adherence Report Scale-5) was seen immediately after the intervention (intervention group 0.00 [SD = 1.3] vs. control group -1.2 [SD = 3.5]; p = 0.021), but this effect did not persist 1 year post surgery. No differences were detected in the prevalence of biochemical deficiencies. Conclusions The use of the smartphone application PromMera did not obtain a lasting improvement in adherence to vitamin and mineral supplementation 1 year post bariatric surgery.

    Place, publisher, year, edition, pages
    Wiley, 2022
    National Category
    Pediatrics
    Identifiers
    urn:nbn:se:liu:diva-188410 (URN)10.1002/oby.23536 (DOI)000848438400001 ()36050801 (PubMedID)
    Note

    Funding Agencies|County Council of Ostergotland; Karolinska Institutet; Region Stockholm

    Available from: 2022-09-12 Created: 2022-09-12 Last updated: 2024-10-10
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