liu.seSearch for publications in DiVA
Change search
Refine search result
1234567 1 - 50 of 2875
CiteExportLink to result list
Permanent link
Cite
Citation style
  • apa
  • harvard1
  • ieee
  • modern-language-association-8th-edition
  • vancouver
  • Other style
More styles
Language
  • de-DE
  • en-GB
  • en-US
  • fi-FI
  • nn-NO
  • nn-NB
  • sv-SE
  • Other locale
More languages
Output format
  • html
  • text
  • asciidoc
  • rtf
Rows per page
  • 5
  • 10
  • 20
  • 50
  • 100
  • 250
Sort
  • Standard (Relevance)
  • Author A-Ö
  • Author Ö-A
  • Title A-Ö
  • Title Ö-A
  • Publication type A-Ö
  • Publication type Ö-A
  • Oldest first
  • Newest first
Select all
  • 1.
    Zaigham, Mehreen
    et al.
    Department of Obstetrics and Gynecology Skåne University Hospital, Institution of Clinical Sciences, Lund University, Malmö, Sweden.
    Lundberg, Fredrik
    Department of Neonatology, Skåne University Hospital, Institution of Clinical Sciences, Lund University, Malmö, Sweden.
    Hayes, Ronald
    Banyan Biomarkers Inc., Alachua, FL, USA.
    Undén, Johan
    Department of Intensive Care and Perioperative Medicine, Skåne University Hospital, Institution of Clinical Sciences, Lund University, Malmö, Sweden.
    Olofsson, Per
    Department of Obstetrics and Gynecology Skåne University Hospital, Institution of Clinical Sciences, Lund University, Malmö, Sweden.
    Umbilical cord blood concentrations of ubiquitin carboxy-terminal hydrolase L1 (UCH-L1) and glial fibrillary acidic protein (GFAP) in neonates developing hypoxic-ischemic encephalopathy.2015In: The Journal of Maternal-Fetal & Neonatal Medicine, ISSN 1476-7058, E-ISSN 1476-4954, Vol. 29, no 11, 1822-1828 p.Article in journal (Refereed)
    Abstract [en]

    OBJECTIVE: To compare ubiquitin carboxy-terminal hydrolase L1 (UCH-L1) and glial fibrillary acidic protein (GFAP) concentrations in umbilical cord blood of neonates who develop Sarnat stage II-III hypoxic-ischemic encephalopathy (HIE) to healthy controls, and to relate the concentrations to the severity of neurology and long-time outcomes.

    MATERIAL AND METHODS: Cord sera of 15 neonates with HIE II-III and 31 matched controls were analyzed for UCH-L1 and GFAP. Comparisons were performed for cord artery pH, amplitude-integrated electroencephalography (aEEG), stage of HIE, and death or sequelae up to an age of 6 years. Parametric and non-parametric statistics were used with a two-sided p < 0.05 considered significant.

    RESULTS: Among controls no associations between biomarker concentrations and gestational age, birthweight, length of storage of cord sera and degree of hemolysis were found. No significant differences in biomarker concentrations were found between HIE neonates and controls, and no differences were found with regard to HIE stage, cord acidemia, severity of aEEG changes, or persistent sequelae or death.

    CONCLUSIONS: No differences in cord blood UCH-L1 and GFAP concentrations were found between HIE neonates and controls, and no associations were found between the biomarker concentrations and the severity of disease, or whether the condition developed into a permanent or fatal injury.

  • 2.
    Rashid, Asim
    et al.
    Department of Mechanical Engineering, Jönköping University, Jönköping, Sweden.
    Kallin, Sara
    Department of Mechanical Engineering, Jönköping University, Jönköping, Sweden.
    Salomonsson, Kent
    Department of Mechanical Engineering, Jönköping University, Jönköping, Sweden.
    Hansbo, Peter
    Department of Mechanical Engineering, Jönköping University, Jönköping, Sweden.
    Simulation of internal mechanical conditions in the lower limb donned in a transtibial prosthetic socketManuscript (preprint) (Other academic)
    Abstract [en]

    This paper investigates the internal mechanical conditions in a transtibial cross-section while in contact with a prosthetic socket. The nite element model considers the nonlinear behaviors of individual soft tissues instead of lumping them together. The contact problem is solved between socket and limb while taking the friction into consideration to determine the contact forces and resultant internal stress-strain in the limb. Simulation results are presented for three dierent socket designs; total contact, total surface-bearing and hydrostatic sockets. Inuence of higher blood pressure on internal mechanical conditions is also explored.

  • 3.
    Didanovic Nilsson, Lotta
    Linköping University, Department of Culture and Communication.
    Är blod tjockare än vatten?: En kvalitativ studie om familjen och den biologiska betydelsen.2015Independent thesis Advanced level (degree of Master (One Year)), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

     

     

    Titel: Is blood thicker than water? A qualitative study of the family and the biological significance.

    Author: Lotta Didanovic Nilsson

     

    The purpose of this study has been to investigate whether, and if so, why it is so important for individuals to get to know their biological parents. The point of departure has been people who have grown up with one of their biological parents and met the other biological parent only as an adult. I have chosen to look at what happens in this meeting and how the people involved reacted and were affected by this. What controls and shapes the individual/group, such as the media, family-policy, social structures and what is considered proper procedure in a certain context and at different levels will also be discussed. The study is qualitative with semi-structured interviews with six informants, myself included. Therefore, this thesis will be an auto-ethnography as my own history and my experience is lifted and analysed together with my informants’. The results show a multi-faceted picture where the conclusion I draw is that the biological plays an important role for the parent- and child-relationship but perhaps for other reasons than we have previously thought. It further requires a social context on a day to day-basis for this relationship to become something significant and deep.

  • 4.
    Gustavsson, Frida
    Linköping University, Department of Physics, Chemistry and Biology, Biology. Linköping University, Faculty of Science & Engineering.
    Validation study: HemoCue Hb 201 + as a tool in comparative physiological field studies on avian blood2015Independent thesis Basic level (degree of Bachelor), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

    Haemoglobin concentration is becoming a widely popular parameter to use to assess physiological condition within a broad range of species. Assessments of large populations would preferable be done in field to receive quick results and avoid confounding factors associated with transport of blood. A validation study is here performed to see how well the point-of-care device HemoCue Hb 201 + can assess haemoglobin concentration on avian blood. Nucleated erythrocytes have previously been pointed out as something that makes it problematic to apply HemoCue Hb 201 +, designed for human blood, on avian blood. Here it is shown that HemoCue Hb 201 + accurately can estimate haemoglobin concentration for chicken-, tinamou-, and ostrich blood. However, manipulation of ostrich cells, to yield a larger mean corspuscular volume, results in HemoCue Hb 201 + overestimating haemoglobin concentration. A large mean corpuscular volume could therefore be something that impair accuracy in values retrieved with HemoCue Hb 201 +. This study shows that HemoCue Hb 201 + seems possible to apply on avian blood to some extent, but highlights the importance of validation studies when applying this device on new species. 

  • 5.
    Magnusson, Karolina
    Linköping University, Department of Biomedical Engineering. Linköping University, Faculty of Science & Engineering.
    Mechanical heart rate detection using cardiogenic impedance - a morphology approach2015Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    The objective of this thesis is to examine the possibility to determine the mechanical heart rate using intracardiac impedance in the time domain. Deducing the mechanical heartrate from the impedance could help improve the performance of implanted devices that today depend on the measurement of the heart’s electrical activity. Cardiogenic – also known as intracardiac – impedance is based on the difference in conductivity between heart muscle tissue and blood, making the impedance vary as the heart is filled and emptied. The data used in this thesis was acquired from three previous studies performed by St Jude Medical, two clinical and one preclinical. Two impedance measurement configurations were chosen from these studies, one bipolar and one quadropolar. To deduce the heart rate from the intracardiac impedance six algorithms were evaluated. Three using continuous peak detection and three evaluating small frames of the impedance signal.The peak detection algorithms were peak detection on the impedance signal itself, on its derivative  and on its integral. The three others were an Auto Correlation Function (ACF), an Average Magnutide Difference Function (AMDF) and an Average Wave Comparison Function (AWCF). In order to assess the heart rates deduced from the intracardiac impedance by the algorithms, these rates were compared to both the IEGM or the ECG (depending on which study was at hand) and the blood pressure.

    Several issues affected the performance of the algorithms. Impedance morphology can vary between patients. Some display so called “double peaks”, making it hard to decide whether a patient has for example a pulse of 80 bpm or of 160 bpm. The impedance morphology was also affected by amplitude modulation with the respiration frequency which in some patients cause difficulties to analyze the impedance signal. The results show that the two impedance measurement configurations perform equally well and that the ACF method was the overall best performing algorithm. They also show that individual patient impedance morphology has a large influence on the results and for future studies it should therefore be interesting to calibrate the algorithms for each patient, as this should improve performance.

  • 6.
    Persson, Louise
    Linköping University, Department of Physics, Chemistry and Biology, Biology. Linköping University, Faculty of Science & Engineering.
    Behavioural responses of mice to the odour of cat blood and horse blood2015Independent thesis Basic level (degree of Bachelor), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

    A variety of prey species are able to detect predators by odours emanating from their urine, feces, fur and anal glands. However, it is unknown whether the odour of a predator’s blood also contains information signalling “predator” to a prey. The aim of the present study was therefore to assess if blood odour from a cat elicits avoidance or anxiety responses in CD-1 mice (Mus musculus). A two-compartment test arena was used to assess place preference, motor activity and fecal excretions when the mice were simultaneously presented with cat blood and a blank control. Additionally, the mice were tested with horse blood and N-pentyl acetate, a fruity odour. The mice did not show avoidance of any of the three odours. Nevertheless, the mice were significantly less active when exposed to cat blood in comparison to horse blood, but did not increase defecation when exposed to cat blood. This suggests that the information mice get by the odour of cat blood did not contain the signal “predator”.

  • 7.
    Elwin, Elin
    Linköping University, Department of Culture and Communication. Linköping University, Faculty of Arts and Sciences.
    Att lita på andras blodgåva: Åsikter om att homosexuella män i praktiken nekas donera blod2015Independent thesis Basic level (degree of Bachelor), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

    This Bachelor Thesis investigates the perceptions nurses and homosexual men, respectively, have concerning the rules for blood donation, focusing on the fact that homosexual men in practice aren't able to donate blood. The study was conducted using qualitative interviews.

    The results emphasise that my informants classify blood and people differently, where both foreign and Swedish blood are rated on potential risk of infection. Nurses and homosexual men also handle the various rules differently, the nurses placing greater focus on protecting receivers of blood. At the same time nurses, like the homosexual men, find the rules discriminatory and based on the prejudice that homosexual men have a riskier lifestyle than others relating to infection. In reality, there can be no certainty in knowing if someone is honest when answering the health declaration which is meant to help the blood bank weed out unsuitable donors.

    The issue of blood donation by homosexual men can be approached from different angles and is therefore a complex topic without an easy solution, especially since current testing cannot detect the HIV virus immediately after transmission. In contrast, my informants emphasise that everyone should be judged on individual behaviour instead of collectively; for example, homosexual men in monogamous relationships should also be able to donate blood.

  • 8.
    Athanasiou, Vasileios
    Linköping University, Department of Medical and Health Sciences, Division of Radiological Sciences. Linköping University, Faculty of Health Sciences.
    Estimation and modelling of fMRI BOLD response2014Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    One of the current topics of research in neuroimaging techniques is related to explaining and modelling the Blood Oxygen Level Dependent (BOLD) responses. BOLD responses are estimated by processing functional Magnetic Resonance Imaging (fMRI) data. BOLD responses are caused by hemodynamic responses to neural activity which alter the levels of blood oxygenation at local brain regions. The main aims of the current thesis were to i) develop and examine methods regarding BOLD response estimation from the visual cortex and the frontal cortex of human brain and to ii) develop a model in order to explain the physiological mechanisms which cause the estimated BOLD responses.

    In order to satisfy the main aims, fMRI data were provided by the Center of Medical Imaging and Visualization (CMIV). The provided fMRI data consist of fMRI brain measurements of twelve healthy human subjects who were subjected to visual stimulation. By processing the fMRI data, Regions Of Interest (ROIs) were extracted at the anatomical sites of the visual cortex and the frontal cortex. Afterwards, the fMRI data were manipulated in order to extract BOLD responses from the visual cortex and the frontal cortex. Various methods were developed and compared in terms of which technique provided well representative BOLD responses.       

    Subsequently, a model was developed by using software Wolfram Mathematica 9 in order to explain the physiological mechanisms of the estimated BOLD responses at the visual and the frontal cortex. The model aimed to solve for oxygen concentration in blood plasma as blood flows from the arterial part to the venous part of the blood circulation system through a capillary. Oxygen outward diffusion through the capillary wall and oxygen concentration at the extravascular environment were modelled as well. Blood plasma oxygen concentration was turned into hemoglobin oxygen saturation (Sa ) through hemoglobin oxygen dissociation curve and Henry’s law for gases. As a result, the Sa  was estimated through modelling for oxygen concentration in blood plasma. Finally, the developed model ended to a system with input the fractional change of Cerebral Blood Flow (CBF) velocity and Cerebral Metabolic Rate of Oxygen (CMR ) and as output a proportional signal to the BOLD response. By simulating for different scenarios of fractional changes of CBF velocity and CMR  and by comparing the resulted BOLD responses to the estimated ones, it was attempted to explain for the physiological mechanisms which caused the BOLD responses at the anatomical sites of the visual and frontal cortex.

  • 9.
    Nyberg White, Maria
    Linköping University, Department of Medical and Health Sciences, Division of Nursing Science. Linköping University, Faculty of Health Sciences.
    Preventing maternal mortality: - Nurses’ and midwives’ experiences from Tanzanian maternal health care services.2013Independent thesis Basic level (degree of Bachelor), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    Background: Half a million women died during pregnancy or childbirth in 2005. Bleeding, infections, high blood pressure, obstructed labor, unsafe abortions, malaria and HIV/Aids were the main causes. Tanzania is a highly affected country with 460 maternal deaths per 100 000 live births. Nurses and midwives play an important role in preventing maternal mortality.

    Purpose: The aim of this study was to explore and analyze nurses’ and midwives’ experiences of maternal mortality prevention on the Tanzanian island of Unguja.

    Method: Interviews with nine nurses and midwifes from four different hospitals and health care facilities were conducted with the assistance of an interpreter. A structural analysis designed by Ricoeur was undertaken.

    Results: The findings suggest that family planning, a more accessible health care, referral of severe cases, medical interventions, health education, community resource persons and involving fathers in maternal health care are preventive strategies that can reduce maternal mortality.

    Conclusion: To further improve the quality of maternal mortality prevention further knowledge aboutindividual differences in learning from health education is needed.  Involvement of all fathers in maternal health care should also be considered. Training of unskilled personnel is believed to improve early identification of life-threatening complications and thereby reduce maternal mortality.

  • 10.
    Prabahar, Jasila
    Linköping University, Department of Biomedical Engineering. Linköping University, The Institute of Technology.
    Localization of Stroke Using Microwave Technology and Inner product Subspace Classifier2014Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    Stroke or “brain attack” occurs when a blood clot carried by the blood vessels from other part of the body blocks the cerebral artery in the brain or when a blood vessel breaks and interrupts the blood flow to parts of the brain. Depending on which part of the brain is being damaged functional abilities controlled by that region of the brain is lost. By interpreting the patient’s symptoms it is possible to make a coarse estimate of the location of the stroke, e.g. if it is on the left or right hemisphere of the brain. The aim of this study was to evaluate if microwave technology can be used to estimate the location of haemorrhagic stroke.

    In the first part of the thesis, CT images of the patients for whom the microwave measurement are taken is analysed and are used as a reference to know the location of bleeding in the brain. The X, Y and Z coordinates are calculated from the target slice (where the bleeding is more prominent). Based on the bleeding coordinated the datasets are divided into classes. Under supervised learning method the ISC algorithm is trained to classify stroke in the left and right hemispheres; stroke in the anterior and posterior part of the brain and the stroke in the inferior and superior region of the brain. The second part of the thesis is to analyse the classification result in order to identify the patients that were being misclassified.

    The classification results to classify the location of bleeding were promising with a high sensitivity and specificity that are indicated by the area under the ROC curve (AUC). AUC of 0.86 was obtained for bleedings in the left and right brain and an AUC of 0.94 was obtained for bleeding in the inferior and superior brain. The main constraint was the small size of the dataset and few availability of dataset with bleeding in the front brain that leads to imbalance between classes. After analysis it was found that bleedings that were close to the skull and few small bleedings that are deep inside the brain are being misclassified. Many factors can be responsible for misclassification like the antenna position, head size, amount of hair etc.

    The overall results indicate that SDD using ISC algorithm has high potential to distinguish bleedings in different locations. It is expected that the results will be more stable with increased patient dataset for training.

  • 11.
    Skarphagen, Richard
    et al.
    Linköping University, Department of Electrical Engineering. Linköping University, The Institute of Technology.
    Suu, Albin
    Linköping University, Department of Electrical Engineering. Linköping University, The Institute of Technology.
    Utveckling av prototyp för utläsning av sensorvärden från enkortsdator via NFC2014Independent thesis Basic level (degree of Bachelor), 10,5 credits / 16 HE creditsStudent thesis
    Abstract [en]

    The use of phone to check if you are sick or not has just begun, one example of this is that Apple recently released its new ios that contains the app “Health” where you can check how many steps you have taken on a day, check your pulse rate or how many calories you have burnt during the day.

    We simply want to check our health at home with ease so we don’t have to go to the hospital, this requires that our product has to be small and cellpowered and of course cheap.

    This report describes our examwork where we investigate if we can build a blood flow measurement/measuring prototype, it has to be cheap, cellpowered, small and it must have theability to send its information via the protocol NFC.

    We were given a Raspberry Pi, this to keep the price down, and for the NFCsending issue wehad to use Androidphones/tablets with NFC on them. To reach the goal we had to program the Raspberry Pi in C to take care of the information, and make an app for Android in Java that reads the information wirelessly and can show the information on display.

    Late in the project we noticed that our ADC couldn’t handle the probe, wich made us unable to realise the blood flow probe measurements. Therefore our finished product is not the complete product we were hiping for.

    We had to change the probe to a IRdistance sensor, wich we chose because then we would still be able to show that we can send information from a sensor via ADC to Raspberry Pi and then to the phone/tablet.

    Our finished product became a small, cheap and cellpowered distance measurer. This showed us that we have the knowledge to make a small, cheap and cellpowered hospital gear.

    In the future there are big possibilites with what you can do with this  technique for example, check for disease, blood flow, lung capacity just by reading via moving your phone over for example a watch.

  • 12.
    Ottosson, Marie-Louise
    Linköping University, Faculty of Health Sciences.
    Visualisering av basalcellscancer med Tissue Viability Imaging - ett icke-invasivt diagnostiskt alternativ2014Independent thesis Basic level (degree of Bachelor), 180 HE creditsStudent thesis
    Abstract [en]

    Basal cell carcinoma (BCC) is the most common non-melanoma skin cancer. It can be divided in different subtypes. The most common type is superficial and is most frequently occurring on the trunk and on the face. In severe cases it can be difficult to differentiate basal cell carcinoma from other skin tumors, therefore a skin biopsy is conclusive diagnostic method. In terms of treatment, curettage is a common non-surgical treatment of basal cell carcinoma. However, being superficial, curettage increases the risk of recurrence. Between 30-40 % of most recurrences occur within five years.

    Tissue Viability Imaging or TiVi is a diagnostic method used by the Department of Dermatology at the University Hospital in Linköping. The technology allows the investigator to see through the top layer of the skin (epidermis) and map the skin skin blood circulation in the dermal area.

    The aim of this study was to investigate whether histological features of present basal cell carcinoma, inflammation, stroma and microvessels, correlates with the presence of the tumour visualized by Tissue Viability Imaging technique.

    The hypothesis is, that by visualizing BCC recurrence at the first visit at the clinic by using TiVi technique, we can diagnose BCC and treat patients in one step, thus reducing the amount of discomfort for the patient and also reduce the cost of care.

    In this pilot-study, patient material involving two basal cell carcinomas from one patient were used. The results show that microscopic examination of the tumor and blood vessels correlate with visualizing basal cell carcinoma with TiVi, although furthermore studies of existing basal cell carcinoma and several tumours are required to ensure correlation before TiVi can be used to replace skin biopsy.

  • 13.
    Björn, Niklas
    Linköping University, Department of Medical and Health Sciences. Linköping University, Faculty of Health Sciences.
    Database processing for identification of concomitant drug frequencies in a forensic material positive for antidepressant drugs2014Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    This article presents a study conducted on data containing drug concentrations. The data was obtained from femoral venous blood samples collected at medico legal autopsies in Sweden. Cases positive for antidepressant drugs were scrutinized and divided in to two groups for 15 antidepressant drugs: B‑cases, where the cause of death was intoxication with more than one drug detected in the blood sample. C‑cases, where the cause of death was NOT intoxication and at least one drug (the antidepressant) was detected in the blood sample. This data was then processed to find frequencies of concomitant drugs taken together with the antidepressant drugs. Frequencies of the most common concomitant drugs were then compared between B-cases and C-cases for each antidepressant drug. This revealed that the drugs dextropropoxyphene, ethanol, codeine, flunitrazepam, paracetamol, propiomazine and alimemazine were signifcantly more common as concomitant drugs in B-cases (intoxications) than in C‑cases (non‑intoxications). With regards to unknown interactions the most interesting combinations were: Propiomazine with mirtazapine, venlafaxine, citalopram or fluoxetine; Paracetamol with paroxetine; Flunitrazepam with mirtazapine, venlafaxine or citalopram; Codeine with mirtazapine or sertraline. These combinations should be further investigated.

  • 14.
    Home, P.D.
    et al.
    Newcastle Diabetes Centre, Newcastle University, Newcastle upon Tyne, United Kingdom.
    Pocock, S.J.
    Medical Statistics Unit, London School of Hygiene and Tropical Medicine, London, United Kingdom.
    Beck-Nielsen, H.
    Department of Endocrinology and Metabolism, Odense, Denmark.
    Curtis, P.S.
    GlaxoSmithKline Research and Development, Greenford, United Kingdom.
    Gomis, R.
    Hospital Clinic, University of Barcelona, Barcelona, Spain.
    Hanefeld, M.
    Zentrum für Klinische Studien Forschungsbereich Endokrinologie und Stoffwechsel, Dresden, Germany.
    Jones, N.P.
    GlaxoSmithKline Research and Development, Harlow, United Kingdom.
    Komajda, M.
    Université Pierre et Marie Curie Paris 6, Hôpital Pitié-Salpêtrière, Département de Cardiologie, Paris, France.
    McMurray, J.J.
    British Heart Foundation Cardiovascular Research Centre, University of Glasgow, Glasgow, United Kingdom.
    Rosiglitazone evaluated for cardiovascular outcomes in oral agent combination therapy for type 2 diabetes (RECORD): a multicentre, randomised, open-label trial2009In: The Lancet, ISSN 0140-6736, E-ISSN 1474-547X, Vol. 373, no 9681, 2125-2135 p.Article in journal (Refereed)
    Abstract [en]

    Background: Rosiglitazone is an insulin sensitiser used in combination with metformin, a sulfonylurea, or both, for lowering blood glucose in people with type 2 diabetes. We assessed cardiovascular outcomes after addition of rosiglitazone to either metformin or sulfonylurea compared with the combination of the two over 5-7 years of follow-up. We also assessed comparative safety. Methods: In a multicentre, open-label trial, 4447 patients with type 2 diabetes on metformin or sulfonylurea monotherapy with mean haemoglobin A 1c (HbA 1c) of 7·9% were randomly assigned to addition of rosiglitazone (n=2220) or to a combination of metformin and sulfonylurea (active control group, n=2227). The primary endpoint was cardiovascular hospitalisation or cardiovascular death, with a hazard ratio (HR) non-inferiority margin of 1·20. Analysis was by intention to treat. This study is registered with ClinicalTrials.gov, number NCT00379769. Findings: 321 people in the rosiglitazone group and 323 in the active control group experienced the primary outcome during a mean 5·5-year follow-up, meeting the criterion of non-inferiority (HR 0·99, 95% CI 0·85-1·16). HR was 0·84 (0·59-1·18) for cardiovascular death, 1·14 (0·80-1·63) for myocardial infarction, and 0·72 (0·49-1·06) for stroke. Heart failure causing admission to hospital or death occurred in 61 people in the rosiglitazone group and 29 in the active control group (HR 2·10, 1·35-3·27, risk difference per 1000 person-years 2·6, 1·1-4·1). Upper and distal lower limb fracture rates were increased mainly in women randomly assigned to rosiglitazone. Mean HbA 1c was lower in the rosiglitazone group than in the control group at 5 years. Interpretation: Addition of rosiglitazone to glucose-lowering therapy in people with type 2 diabetes is confirmed to increase the risk of heart failure and of some fractures, mainly in women. Although the data are inconclusive about any possible effect on myocardial infarction, rosiglitazone does not increase the risk of overall cardiovascular morbidity or mortality compared with standard glucose-lowering drugs. Funding: GlaxoSmithKline plc, UK. © 2009 Elsevier Ltd. All rights reserved.

  • 15.
    Rehman, Atif ur
    et al.
    Biosciences, School of Life and Medical Sciences, University of Hertfordshire, College, United Kingdom.
    Dugic, Elma
    Linköping University, Department of Medical and Health Sciences. Linköping University, Faculty of Health Sciences.
    Benham, Chris
    Biosciences, School of Life and Medical Sciences, University of Hertfordshire, College, United Kingdom.
    Lione, Lisa
    Biosciences, School of Life and Medical Sciences, University of Hertfordshire, College, United Kingdom.
    Mackenzie, Louise S
    Biosciences, School of Life and Medical Sciences, University of Hertfordshire, College, United Kingdom.
    Selective inhibition of NADPH oxidase reverses the over contraction of diabetic rat aorta2014In: Redox Biology, ISSN 2213-2317, Vol. 2, no 1, 61-64 p.Article in journal (Refereed)
    Abstract [en]

    Abnormal vascular responsiveness in diabetes has been attributed to a number of changes in contractile pathways, affected in part by the overproduction of reactive oxygen species (ROS). It has been reported that NADPH oxidase (NOX) is increased in diabetic (streptozotocin treated; STZ) rat arteries; however the pharmacological agents used to inhibit NOX activity are known to be unsuitable for in vitro studies and have a high level of non-selectivity. Here we have used the highly selective NOX inhibitor VAS2870 in diabetic rat aorta and compared its effects with apocynin, SOD, and allopurinol on phenylephrine and U46619 induced contraction. Male Wistar rats were injected intraperitoneally with 65mg/kg STZ and development of diabetes was confirmed by testing blood glucose levels. Rats were killed by CO2 asphyxiation, and the thoracic aorta removed and mounted in an organ bath under a tension of 1g. Diabetic rat aortas exhibit a greatly increased response to phenylephrine, which was reduced to a level consistent with control rat aorta by 10-5M VAS2870 and 150U/ml SOD. Incubation with VAS2870 led to an increase in normal rat aorta contraction, but led to a significant reduction in phenylephrine and U46619 induced tone in diabetic rat aorta, which indicates that ROS in diabetic rats directly contributes to these contractile responses. Apocynin and allopurinol had no effect on contraction in diabetic or normal rat aorta. This data is the first to show that selective inhibition of NOX reduces diabetic arterial contraction in direct comparison with inhibition of other known contributors of ROS.

  • 16.
    Karlsson, Lise-Lott
    Linköping University, Department of Culture and Communication, Centre for Applied Ethics. Linköping University, Faculty of Arts and Sciences.
    Prenatal Testing and Reproductive Freedom: A Mother´s Right to Choose2014Independent thesis Advanced level (degree of Master (One Year)), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

    The aim of this thesis is to analyse and examine the debate on prenatal testing in Western countries, with a special focus on my own country, Sweden. In the near future it might be possible for a pregnant woman to profile the DNA of her foetus with a simple blood test early in pregnancy. This method of prenatal testing – Non Invasive Prenatal Diagnosis (NIPD) – could potentially detect the genetic causes of almost every disease. I will argue that prenatal testing should be offered by society to all pregnant women, not only to those at highest risk of giving birth to children with severe conditions. I will do that from a perspective of reproductive freedom. Furthermore, I will argue that offering prenatal testing for some conditions (such as Downs’s syndrome) and not for others, is conflicting with the autonomous choice of the pregnant woman.

  • 17.
    Håkman, Jonna
    Linköping University, Department of Clinical and Experimental Medicine. Linköping University, Faculty of Health Sciences.
    Vitamin C as a modifier of mammalian epigenetics: implications for adaptive immunity2013Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    Ascorbic acid (AA), in popular speech vitamin C, is a commonly known nutrient. It is involved in several biological processes and deficiency can lead to scurvy. Recent publications have shown the impact of AA on epigenetic regulation in mice. Addition of AA, via enzymatic activity, enhances the generation of 5-hydroxymethylcytosine (5hmC), which is an intermediate in active demethylation of DNA.

    The role of AA on epigenetic changes in humans has to our knowledge never been studied. In this study, naïve CD4+ T cells from blood donors were used as a model system to investigate AAs possible role in methylation changes in the immune system. By using dot-blot assay, hydroxymethylated DNA immunoprecipitation (hmeDIP) and qPCR, changes in methylation executed by AA could be detected.

    A confirmation of AAs impact on epigenetic changes in mice was observed. AA enhanced the levels of 5hmC compared to untreated cells. The Jurkat cell line, a human T lymphocyte cell line, showed an opposite result. Treatment with AA decreased the levels of 5hmC compared to untreated cells. When comparing this result with the results obtained in human naïve T cells, the same observation was made. The difference between mouse and human in the ability of producing and metabolize AA could be a reason for this opposite result.

    Since AA had the ability to modify epigenetic changes in primary human CD4+ T cells, the results suggest that AA may have a function in the human immune system.

  • 18.
    Hedblom, Anders
    Linköping University, Department of Science and Technology, Media and Information Technology. Linköping University, The Institute of Technology.
    Blood vessel segmentation for neck and head computed tomography angiography2013Independent thesis Advanced level (professional degree), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    This thesis presents tests and discussions evaluating different methods for doing automatic or semi automatic blood vessel segmentation on single CT data volumes of the head and neck. The two approaches being closest to accomplish this are a bone subtracting registration process, and a more advanced region growing combined with morphology.

  • 19.
    Stoltz, Jonathan
    Linköping University, Department of Computer and Information Science. Linköping University, Faculty of Arts and Sciences.
    Naturljud inomhus - En pilotstudie i tre fall2013Independent thesis Advanced level (degree of Master (One Year)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    It's an everyday experience shared by many that nature can be of help in relieving pain, reducing stress, support mental recovery etc. In the last three decades or so this experience has also found support in a large number of scientific investigations. Among other things the experience of nature has been shown to reduce stress and pain in patients and to boost concentration and reduce impulsive behavior in children. Most of this research however has mainly been concerned with the visual modality. In this thesis the aim has been to focus on the auditory modality in this context by trying to reveal some effects on people from the exposure of nature sounds played indoors in three different environments: a grammar school class room, a kindergarten play room and a post-surgery wake up room at an intensive care unit. The results from the class room revealed a great difference among the children in how they perceived the sounds and how the sounds affected their self-reported ability to concentrate. The sounds of nature seemed to have no great impact on the kindergarten children; however the impact that was found was slightly positive. No impact on the investigated parameters of blood pressure, heart rate and respiration rate was found in the subjects at the intensive care unit; though the number of subjects was very small and they were all under heavy influence of anesthesia and analgesic drugs during the sound exposure. Also, the sound environment in the wake up room was very hard to control and was sometimes noisy.

  • 20.
    Sievert, Andreas
    Linköping University, Department of Science and Technology. Linköping University, The Institute of Technology.
    Tools and Algorithms for Classification in Volume Rendering of Dual Energy Data Sets2008Independent thesis Advanced level (degree of Master (One Year)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    In the last few years, technology within the medical imaging sector has made many advances, which in turn has opened many new possibilities. One such recent advance is the development of imaging with data from dual energy computed tomography, CT, scanners. However, with new possibilities come new challenges.

    One challenge, that is discussed in this thesis, is rendering of images created from two volumes in an efficient way with respect to the classification of the data. Focus lies on investigating how dual energy data sets can be classified in order to fully use the potential of having volumes from two different energy levels. A critical asset in this investigation is the ability to utilize a transfer function description that extends into two dimensions. One such transfer function description is presented in detail.

    With this two-dimensional description comes the need for a new way to interact with the transfer function. How the interaction between a user and the transfer function description is implemented for Siemens Corporate Research in Princeton, NJ will also be discussed in this thesis as well as the classification results of rendering dual energy data. These results show that it is possible to classify blood vessels correctly when rendering dual energy computed tomography angiography, CTA, data.

  • 21.
    Sehr, Viktor
    Linköping University, Department of Science and Technology. Linköping University, The Institute of Technology.
    Automation of methods for extracting a vascular system from CT-data for use in medical simulation applications2008Independent thesis Advanced level (degree of Master (One Year)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    In this thesis an application for extraction and verification of anatomical data for use in Men- tice Procedicus VIST has been implemented. The data sources are three dimensional data sets received from scans of human bodies using Computer Tomography- (CT) 1 and Magnetic Resonance (MRI) 2 scanners. Mentice Proceducis VIST is a medical simulator with the aim of providing surgeons an environment for practicing endovascular surgery. In order to create a sim- ulator case from a patient case, Mentice relies on manual modeling of the anatomical structures using 3D scans of the patient as key. This thesis utilizes algorithms for extraction of center lines and parsing them to a hierarchical structure of curves with radiuses, representing the vascular system where the hierarchy represents the blood flow direction. In addition to automated meth- ods, this application also features a user interface for visualization of the vascular system as well as editing capabilities for adjusting the vascular system.

  • 22.
    Dadi, Kamalaker Reddy
    Linköping University, Department of Biomedical Engineering. Linköping University, Center for Medical Image Science and Visualization, CMIV. Linköping University, The Institute of Technology.
    Circadian Rhythms in the Brain - A first step2013Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    Circadian Rhythms (CR) are driven by a biological clock called as suprachiasmaticnucleus (SCN), located in a brain region called the hypothalamus. These rhythms are very much necessary in maintaining the sleep and wake cycle at appropriate times in a day. As a starting step towards non-invasive investigation of CR, aim is to study changes in the physiological processes of two Regions of Interest (ROI), the hypothalamus and the visual cortex. This was studied using a functional Magnetic Resonance Imaging (fMRI) technique to investigate for any changes or differences in the Blood Oxygen Level Dependent (BOLD)signals extracted from the ROI during a visual stimulation. We acquired and processed fMRI data to extract BOLD signals from ROI and the extracted signals are again further used to study the correlation with the experimental ON-OFF design paradigm.

    The extracted BOLD signals varied a lot between the two specified brain regions within the same subject and between three types of fMRI data. These variations were found in terms of number of activated voxels and also Signal to Noise ratio(SNR) level present in the signals. The number of activated voxels and SNR werehigh in visual cortex whereas low number of activated voxels and low SNR were found in hypothalamus. The correlation between BOLD responses from primaryvisual cortex were shown as positive with the experimental stimulation whereas BOLD responses extracted from hypothalamus have shown a negative correlation in time with the experimental stimulation.

    As a start up of the project, these BOLD responses can provide references for a future use in research studies, especially to further study about change in phase of the BOLD signal extracted exactly from the SCN. These phase responses can then be used to study physiological processing in subjects affected by sleep disorders.

  • 23.
    Kus, Emre
    Linköping University, Department of Biomedical Engineering. Linköping University, Center for Medical Image Science and Visualization, CMIV. Linköping University, The Institute of Technology.
    Estimation and visualization of relative pressure fields in the human heart from time resolved MRI flow data2013Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    Heart diseases are the leading cause of death in developed countries, hence, understanding of the hemodynamics of the heart is critically important to enable methods for cardiovascular diagnosis. Assessment of intracardiac blood pressure is highly interesting as blood flow is driven by the pressure differences.

    Phase-contrast magnetic resonance imaging (PC-MRI) is a tool for measuring blood flow and has a wide range of cardiovascular applications. Based on previous studies, an approach to estimate the relative pressure fields in the human heart from three-dimensional time-resolved PC-MRI velocity data was implemented and evaluated. The relative pressure fields were obtained by solving the pressure Poisson equation, using a multi-grid approach. The method was evaluated on a numerical phantom and on PC-MRI data from one healthy subject and one patient with dilated cardiomyopathy. The pressure field was visualized in combination with blood flow data and morphological images.

    Results indicate that the used approach works well for cardiac relative pressure estimation and are in agreement with findings from previous research. The complete spatial and temporal coverage of relative pressure enables a higher understanding of physiology and pathophysiology of the human heart and is expected to give new insights for clinical investigations.

  • 24.
    Karlsson, Cecilia
    Linköping University, Department of Physics, Chemistry and Biology. Linköping University, The Institute of Technology.
    Studies of unspecific interaction between the Aβ antibody 6E10 and blood coagulation protein factor X2012Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    Alzheimer’s disease is neurodegenerative with amyloid plaque and neurofibrillary tangles as pathological hallmarks. The most abundant component in the amyloid plaque is the amyloid-β (Aβ) peptide, with presence of both isoform Aβ40 and Aβ42. In immunological methods studying the Aβ peptide a specific monoclonal antibody, 6E10, is routinly being used. In this master thesis work unspecific binding of 6E10 antibody to the blood coagulating protein factor X has been investigated. Factor X is a protein in the blood coagulation cascade where it forms protein complex that activates thrombin. Non-hemostatic functions with connections to nerves and Aβ peptide are also known. Studies with Western blot show clear binding of 6E10 to denatured factor X. Interaction studies with ELISA gives uncertain results, where binding is found but no clear binding curve is obtained. Studies with native factor X in real time measurements with SPR gave no binding at all. These results suggest binding to denatured factor X. Immunohistochemistry studies of colocalisation of factor X and Aβ peptide gave clear evidence that factor X and Aβ are found near each other in mouse brain tissue. Factor X is located outside the blood vessels and Aβ is located at the inside. 

  • 25.
    Nylander, Sven
    et al.
    Cell Biology and Biochemistry, Precrinicar R and D, AstraZeneca R and D Mölndal, Mölndal, Sweden.
    Mattson, Christer
    Cell Biology and Biochemistry, Precrinicar R and D, AstraZeneca R and D Mölndal, Mölndal, Sweden.
    Thrombin-induced platelet activation and its inhibition by anticoagulants with different modes of action2003In: Blood Coagulation and Fibrinolysis, ISSN 0957-5235, E-ISSN 1473-5733, Vol. 14, no 2, 159-167 p.Article in journal (Refereed)
    Abstract [en]

    Thrombin-induced platelet activation involves cleavage of protease-activated receptors (PARs) 1 and 4, and interaction, via glycoprotein (Gp)Ibα, with the platelet GpIb/IX/V complex. This study investigated inhibition of platelet activation by thrombin inhibitors with different modes of action: two reversible direct thrombin inhibitors, melagatran and inogatran; hirudin, a tightly binding direct thrombin inhibitor; and two indirect thrombin inhibitors, heparin and dalteparin. Up-regulation of P-selectin (CD62P) and PAR-1 cleavage was measured in human whole blood, by flow cytometry. The thrombin concentration that induced 50% of maximum (EC50) PAR-1 cleavage was 0.028 nmol/l, while that of platelet activation (CD62P) was over two-fold higher (0.64 nmol/l). The EC50 of a PAR-1-independent component, defined as a further activating effect of thrombin on top of the maximum PAR-1-activating peptide (AP) effect, was 3.2 nmol/l. All anticoagulants were concentration-dependent inhibitors of thrombin-induced platelet activation and PAR-1 cleavage, but none inhibited PAR-1-AP or PAR-4-AP induced activation. Melagatran and inogatran were more potent inhibitors of CD62P up-regulation than of PAR-1 cleavage; conversely, hirudin, heparin and dalteparin were more potent inhibitors of PAR-1 cleavage.Thus, reversible direct thrombin inhibitors, such as melagatran, are potent inhibitors of thrombin-induced platelet activation, acting mainly by inhibition of a PAR-1-independent component.

  • 26.
    Gasparini, Isabella
    Linköping University, Department of Physics, Chemistry and Biology, Biology. Linköping University, The Institute of Technology.
    Cardiorespiratory responses upon increased metabolism in the Ornate Tinamou, Nothoprocta ornata2012Independent thesis Advanced level (degree of Master (Two Years)), 40 credits / 60 HE creditsStudent thesis
    Abstract [en]

    The Bolivian Ornate Tinamou, Nothoprocta ornata, lives higher than 3300 m above sea level and must constantly deal with a restricted availability of atmospheric oxygen, i.e., chronic hypoxia. Interestingly enough, the Ornate Tinamou has a small heart to body ratio, which implies a reduced ability in transporting oxygenated blood to the tissues. In order to increase knowledge about the cardiorespiratory response of the Ornate Tinamou, heart rate (HR) and ventilation frequency (VR) were monitored during resting at 25 °C. The values were compared with those obtained in conditions known to elevate metabolism, i.e., lowered temperature and graded exercise. This was later compared with domestic chickens, Gallus gallus. Results showed a significant increase in HR at 4 °C, 305 ±42 bpm in the Ornate Tinamou when compared with HR at 25°C, 241± 48 bpm (330 ±42bpm and 239 ±32bpm in chicken). A significant increase in VR was only observed in chicken. As expected, with a progressive increase in running speed, a significant increase in HR in both species was observed. At 1,5 km h-1, HR in the Ornate Tinamou was 327 ±5,6 bpm and 342 ±8,5 in chicken. At 3,0 km h -1 HR was 383 ±15 bpm and 404 ±7,9, respectively. However, HR was not significantly higher in the Ornate Tinamou than in chicken, indicating that there must be other physiological adaptations involved in the sufficient oxygen delivery to tissues, e.g. a high blood oxygen affinity or a preference for anaerobic metabolism due to living in a chronic hypoxic environment.

  • 27.
    Christoffersson, Jonas
    Linköping University, Department of Clinical and Experimental Medicine. Linköping University, Faculty of Health Sciences.
    Distribution of Sca-1+ cardiac progenitor cells in the healthy and the post-MI heart2012Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    The myocardial infarction (MI) is one of the leading causes of death in the world today. Accumulated atherosclerotic plaque occluding cardiac blood vessels results in a lack of oxygen supply to parts of the heart, and consequentially the death cardiomyocytes. The damaged area is replaced by scar tissue because of the heart’s insufficient regenerative capability, and the contraction property of the post-MI heart is therefore compromised. The recent findings of an endogenous cardiac progenitor cell (CPC) population gives hope for the establishment of new methods for medical treatments of the post-MI heart. Compared to other stem/progenitor cell sources, the CPCs are committed to a cardiac fate which places them in the forefront of interesting cell sources for regenerative treatments. In this thesis, the distribution of stem cell antigen 1 (Sca-1) positive CPCs in the healthy mouse myocardium, as well as the healthy and post-MI rat left ventricle was determined and compared to the total amount of nuclei. An immunohistochemistry protocol for the detection of Sca-1+ cells was established, and the number of Sca-1+ cells and the total number of nuclei in the different mouse and rat tissue samples were counted using laser scanning cytometry (LSC). The results could conclude a significantly higher distribution of Sca-1+ cells in the mouse atrium compared to the mouse ventricle, and a significantly higher distribution of Sca-1+ cells in the 8 days post-MI rat left ventricle compared to the healthy rat left ventricle. Furthermore, a heterogeneous distribution within the 8 days post-MI rat left ventricle was observed.

  • 28.
    Shamsudin, Nebil
    Linköping University, Department of Biomedical Engineering, Biomedical Instrumentation. Linköping University, The Institute of Technology.
    A Device for Measurement of Capillary Refilling Time2012Independent thesis Advanced level (degree of Master (Two Years)), 80 credits / 120 HE creditsStudent thesis
    Abstract [en]

    The main objective of this project is to design, construct and validate a portable prototype of a device that is capable of performing a test to accurately measure Capillary Refilling Time (CRT), and to analyze the results with defined parameters; force, area, pressure (compression) and time. This prototype is dedicated to study and evaluate CRT readouts for different pressure values, collected from healthy subjects.The presented prototype of this study is capable of producing skin compressing and to measure the refilling time of capillaries following this compression. This prototype introduces accuracy, mechanical reproducibility and controlling options for the applied pressure and compression time. The presented prototype is non-invasive, portable and it can be used to conduct more CRT tests and other capillary refilling studies.CRT measurement is done by calculating time interval starting from the first point when the applied pressure is released; ending with the recording point at the time when the concentration of red blood cells has reached the level of its pre-occlusion values.Based on the calculated CRT values and the number of iterations of the test in CRT tables, one can observe that given the same applied pressure value, CRT values do not significantly vary when the test is repetitively conducted on the same subject and on the same site.

  • 29.
    Budde, Kiran Kumar
    Linköping University, Department of Electrical Engineering, Computer Vision.
    A Matlab Toolbox for fMRI Data Analysis: Detection, Estimation and Brain Connectivity2012Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    Functional Magnetic Resonance Imaging (fMRI) is one of the best techniques for neuroimaging and has revolutionized the way to understand the brain functions. It measures the changes in the blood oxygen level-dependent (BOLD) signal which is related to the neuronal activity. Complexity of the data, presence of different types of noises and the massive amount of data makes the fMRI data analysis a challenging one. It demands efficient signal processing and statistical analysis methods.  The inference of the analysis is used by the physicians, neurologists and researchers for better understanding of the brain functions.

         The purpose of this study is to design a toolbox for fMRI data analysis. It includes methods to detect the brain activity maps, estimation of the hemodynamic response (HDR) and the connectivity of the brain structures. This toolbox provides methods for detection of activated brain regions measured with Bayesian estimator. Results are compared with the conventional methods such as t-test, ordinary least squares (OLS) and weighted least squares (WLS). Brain activation and HDR are estimated with linear adaptive model and nonlinear method based on radial basis function (RBF) neural network. Nonlinear autoregressive with exogenous inputs (NARX) neural network is developed to model the dynamics of the fMRI data.  This toolbox also provides methods to brain connectivity such as functional connectivity and effective connectivity.  These methods are examined on simulated and real fMRI datasets.

  • 30.
    Ekbäck, Gustav
    et al.
    Department of Anesthesiology and Intensive Care and Regional Blood Center, Örebro Medical Center Hospital, Örebro, Sweden.
    Schött, U.
    Department of Anesthesiology and Intensive Care and Regional Blood Center, Örebro Medical Center Hospital, Örebro, Sweden.
    Axelsson, K.
    Department of Anesthesiology and Intensive Care and Regional Blood Center, Örebro Medical Center Hospital, Örebro, Sweden.
    Carlberg, M.
    Department of Anesthesiology and Intensive Care and Regional Blood Center, Örebro Medical Center Hospital, Örebro, Sweden.
    Perioperative autotransfusion and functional coagulation analysis in total hip replacement1995In: Acta Anaesthesiologica Scandinavica, ISSN 0001-5172, E-ISSN 1399-6576, Vol. 39, no 3, 390-395 p.Article in journal (Refereed)
    Abstract [en]

    Functional coagulation analyses like Sonoclot and thromboelastography have not been evaluated during perioperative autotransfusion. We have prospectively studied three different transfusion regimes in 45 patients undergoing total hip arthroplasty. Blood losses were replaced either with heterologous erythrocyte concentrate (group I), intra- and postoperative autotransfusion of blood salvaged with cellsaver technique (group II) or predonated autologous erythrocyte concentrates together with salvaged blood (group III). Routine and functional coagulation analyses with a Sonoclot were performed preoperatively, 6 hours postoperatively (6 h), day 1–5 and 10. An early postoperative hypo- and late postoperadve hypercoagulative phase could be detected with Sonoclot signs of platelet function and fibrin deposition in all groups. Sonoclot coagulation analyses better correlated to both blood loss and dextran dosage than APTT and platelet count in the routine coagulation analyses. Functional coagulation analysis has a potential use in individualizing plasmasubstitution and thromboprophylaxis regimes during autotransfusion in THR.

  • 31.
    Ekbäck, Gustav
    et al.
    Department of Anesthesiology and Intensive Care, Örebro Medical Center Hospital, Örebro, Sweden and Department of Statistics, University of Örebro, Örebro, Sweden.
    Carlsson, Olle
    Department of Anesthesiology and Intensive Care, Örebro Medical Center Hospital, Örebro, Sweden and Department of Statistics, University of Örebro, Örebro, Sweden.
    Schött, Ulf
    Department of Anesthesiology and Intensive Care, Örebro Medical Center Hospital, Örebro, Sweden and Department of Statistics, University of Örebro, Örebro, Sweden.
    Sonoclot coagulation analysis: A study of test variability1999In: Journal of Cardiothoracic and Vascular Anesthesia, ISSN 1053-0770, E-ISSN 1532-8422, Vol. 13, no 4, 393-397 p.Article in journal (Refereed)
    Abstract [en]

    Objective: To test the reproducibility of Sonoclot coagulation analysis (SCA; Sienco Inc, Morrison, CO). The authors wished to determine if the mix/release of the preloaded celite activator in standard Sono-cuvettes could be responsible for the high variation coefficients for SCA parameters with citrated whole blood and if citrated whole blood is optimal for SCA.

    Design: A prospective trial.

    Setting: A large academic teaching medical center.

    Participants: Eight healthy volunteers.

    Interventions: Repeated blood sampling was performed through indwelling radial artery catheters. Seven different Sonoclot analyzers were used to test seven different types of analysis procedures in the volunteers, involving activators of different types and amounts and in different forms, and the use of citrated or native whole blood.

    Measurments and Main Results: Two-way and one-way ANOVA, variance, variance analysis, and Tukey's test were used to evaluate differences in SCA methods and volunteer influence. A high variance, with SDs up to 200% of the median values of the SCA parameters with recalcified citrated blood and the standard Sono-cuvette, was confirmed. SCA with native blood and/or the use of other types of preloaded activators, ie, kaolin, significantly (p < 0.05) reduced this variance. Repeated SCAs further reduced the variance to 10% to 35% of the variance for a single analysis (standard cuvette and native blood).

    Conclusion: Improvement of the activator in the Sonocuvette, use of native whole blood, and repeated Sonoclot analyses reduced the previously reported high variability of this instrument.

  • 32.
    Ekbäck, Gustav
    et al.
    Departments of Anesthesiology and Intensive Care Örebro Medical Center Hospital.
    Axelsson, Kjell
    Department of Anesthesiology and Intensive Care Örebro Medical Center Hospital.
    Ryttberg, Lars
    Department of Orthopedic Surgery, Örebro Medical Center Hospital.
    Edlund, Bror
    Department of Clinical Chemistry, Örebro Medical Center Hospital.
    Kjellberg, Jill
    Department of Anesthesiology and Intensive Care Örebro Medical Center Hospital.
    Weckström, Johan
    Department of Orthopedic Surgery, Örebro Medical Center Hospital.
    Carlsson, Olle
    Department of Statistics, University of Örebro, Örebro, Sweden .
    Schött, Ulf
    Department of Anesthesiology and Intensive Care Örebro Medical Center Hospital.
    Tranexamic Acid Reduces Blood Loss in Total Hip Replacement Surgery2000In: Anesthesia and Analgesia, ISSN 0003-2999, E-ISSN 1526-7598, Vol. 91, no 5, 1124-1130 p.Article in journal (Refereed)
    Abstract [en]

    Intraoperatively administered, tranexamic acid (TA) does not reduce bleeding in total hip replacement (THR). Therefore, its prophylactic use was attempted in the present study because this has been shown to be more effective in cardiac surgery. We investigated 40 patients undergoing THR in a prospective, randomized, double-blinded study. Twenty patients received TA given in two bolus doses of 10 mg/kg each, the first just before surgical incision and the second 3 h later. In addition, a continuous infusion of TA, 1.0 mg · kg−1 · h−1 for 10 h, was given after the first bolus dose. The remaining 20 patients formed a control group. Both groups used preoperative autologous blood donation and intraoperative autotransfusion. Intraoperative bleeding was significantly less (P = 0.001) in the TA group compared with the control group (630 ± 220 mL vs 850 ± 260 mL). Postoperative drainage bleeding was correspondingly less (P = 0.001) (520 ± 280 vs 920 ± 410 mL). Up to 10 h postoperatively, plasma D-dimer concentration was halved in the TA group compared with the control group. One patient in each group had an ultrasound-verified late deep vein thrombosis. In conclusion, we found TA, administrated before surgical incision, to be efficient in reducing bleeding during THR.

  • 33.
    Ekbäck, Gustav
    et al.
    Department of Anesthesiology and Intensive Care, Örebro Medical Center Hospital, Örebro, Sweden.
    Edlund, Bror
    Department of Clinical Chemistry, Örebro Medical Center Hospital, Örebro, Sweden.
    Smolowicz, Adam
    Department of Transfusion Medicine, Örebro Medical Center Hospital, Örebro, Sweden.
    Axelsson, Kjell
    Department of Anesthesiology and Intensive Care, Örebro Medical Center Hospital, Örebro, Sweden.
    Kjellberg, Jill
    Department of Anesthesiology and Intensive Care, Örebro Medical Center Hospital, Örebro, Sweden.
    Carlsson, Olle
    Department of Statistics, University of Örebro, Sweden.
    Schött, Ulf
    Department of Anesthesiology, Halmstad County Hospital, Halmstad, Sweden.
    The Effects of Platelet Rish Plasmapheresis in Total Hip Replacement Surgery on Platelet Activation Studied by Flow CytometryManuscript (preprint) (Other academic)
    Abstract [en]

    Background: Autologous platelet rich plasma (PRP) harvest with autotransfusion devices has been used for ten years in cardiac surgery and recently in orthopedics. Its influence on the outcome of surgery is still controversial, in part because of methodological difficulties in studying platelet function during surgery.

    Methods: Twenty patients undergoing primary total hip replacement (THR) were studied. Ten patients underwent an immediately preoperative platelet apheresis forming concentrated platelet rich plasma (c-PRP). Ten patients not undergoing apheresis were allocated to a control group. Platelet activation was evaluated as the population expressing P-Selektin on the surface of platelets in the c-PRP and in blood samples collected pre-, per- and postoperatively. The method used was flow cytometry.

    Results and Conclusions: There is a minor population of activated platelets circulating in the patient's blood with a highly significant difference between patients (p=0.005) with a range of 1-23 % in peroperative activation. PRP harvest did not significantly alter platelet activity. The platelet apheresis procedure did not inhibit platelet function in the c-PRP as judged by a high proportion of platelets that could be activated in ADP stimulation experiments (mean value±SD 86%±7.5%).

    The total number of platelets that could be activated in the c-PRP estimated as % ADP activated platelets x % sampled platelets in the c-PRP (total platelet yield), was non significantly correlated (r=-0.59, p<0.l) with postoperative bleeding, indicating a possible hemostatic effect of these platelets.

  • 34.
    Ekbäck, Gustav
    et al.
    Department of Anesthesiology and Intensive Care, Örebro Medical Center Hospital, Örebro, Sweden.
    Ryttberg, Lars
    Department of Orthopedic Surgery, Örebro Medical Center Hospital, Örebro, Sweden.
    Axelsson, Kjell
    Department of Anesthesiology and Intensive Care, Örebro Medical Center Hospital, Örebro, Sweden.
    Christianssen, Frank
    Department of Diagnostic Radiology, Örebro Medical Center Hospital, Örebro, Sweden.
    Kjellberg, Jill
    Department of Anesthesiology and Intensive Care, Örebro Medical Center Hospital, Örebro, Sweden.
    Carlsson, Peder
    Department of Anesthesiology and Intensive Care, Örebro Medical Center Hospital, Örebro, Sweden.
    Carlsson, Olle
    Department of Statistics, University of Örebro, Sweden.
    Schött, Ulf
    Department of Anesthesiology and Intensive Care, Örebro Medical Center Hospital, Örebro, Sweden.
    Preoperative platelet-rich plasmapheresis and hemodilution with an autotransfusion device in total hip replacement surgery2000In: Journal of clinical apheresis, ISSN 0733-2459, E-ISSN 1098-1101, Vol. 15, no 4, 256-261 p.Article in journal (Refereed)
    Abstract [en]

    The effectiveness of both preoperative autologous donation (PAD) and intraoperative autotransfusion (IAT) with an autotransfusion device has recently been questioned. Preoperative apheresis, with separation of concentrated platelet rich-plasma (c-PRP) and erythrocyte concentrate (ERC), represents an aggressive use of the autotransfusion device. Can such a procedure replace PAD in total hip replacement surgery (THR)? Eighty patients undergoing THR were investigated in a prospective and randomized study. Forty patients underwent PAD, and 2 units of ERC + plasma were retrieved within 4 weeks preoperatively. Another 40 patients underwent an immediately preoperative apheresis with a concomitant hemodilution with 4% albumin, retrieving c-PRP (30% of the platelet pool) and 2 units of ERC. Both groups used IAT up to 2 hours postoperatively, with 3% dextran-60 as a plasma substitute according to our standard of care. There were no differences in blood loss, B-hemoglobin or allogeneic transfusions between the groups: 85% of the patients did not receive allogeneic blood. Both apheresis and reinfusion of c-PRP had minor impact on the coagulation parameters. Platelet count increased slightly but significantly (P < 0.05) from 154 to 179 × 109/L after the c-PRP at wound closure. Preoperative apheresis with an autotransfusion device, separating platelet-rich plasma and erythrocyte concentrate, is a useful alternative for patients who are unable to utilize the PAD technique for either religious or practical reasons.

  • 35.
    Vanichbuncha, Tita
    Linköping University, Department of Computer and Information Science, Statistics. Linköping University, The Institute of Technology.
    Risk Factors and Predictive Modeling for Aortic Aneurysm2012Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    In 1963 – 1965, a large-scale health screening survey was undertaken in Sweden and this data set was linked to data from the national cause of death register. The data set involved more than 60,000 participants whose age at death less than 80 years. During the follow-up period until 2007, a total of 437 (338 males and 99 females) participants died from aortic aneurysm. The survival analysis, continuation ratio model, and logistic regression were applied in order to identify significant risk factors. The Cox regression after stratification for AGE revealed that SEX, Blood Diastolic Pressure (BDP), and Beta-lipoprotein (BLP) were the most significant risk factors, followed by Cholesterol (KOL), Sialic Acid (SIA), height, Glutamic Oxalactic Transaminase, Urinary glucose (URIN_SOC), and Blood Systolic Pressure (BSP). Moreover, SEX and BDP were found as risk factors in almost every age group. Furthermore, BDP was strongly significant in both male and female subgroup.

     

    The data set was divided into two sets: 70 percent for the training set and 30 percent for the test set in order to find the best technique for predicting aortic aneurysm. Five techniques were implemented: the Cox regression, the continuation ratio model, the logistic regression, the back-propagated artificial neural network, and the decision tree. The performance of each technique was evaluated by using area under the receiver operating characteristic curve. In our study, the continuation ratio and the logistic regression outperformed among the other techniques.

  • 36.
    Kottravel, Sathish
    Linköping University, Department of Science and Technology, Media and Information Technology. Linköping University, The Institute of Technology.
    GPU accelerated Nonlinear Soft Tissue Deformation2012Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    There are two types of structures in human body, solid organs and hollow membrane like organs. Brain, liver and other soft tissues such as tendons, muscles, cartilage etc., are examples of solid organs. Colon and blood vessels are examples of hollow organs. They greatly differ in structure and mechanical behavior. Deformation of these types of structures is an important phenomena during the process of medical simulation.

    The primary focus of this project is on deformation of soft tissues. These kind of soft tissues usually undergo large deformation. Deformation of an organ can be considered as mechanical response of that organ during medical simulation. This can be modeled using continuum mechanics and FEM. The primary goal of any system, irrespective of methods and models chosen, it must provide real-time response to obtain sufficient realism and accurate information. One such example is medical training system using haptic feedback. In the past two decades many models were developed and very few considered the non-linear nature in material and geometry of the solid organs. TLED is one among them. A finite element formulation proposed by Miller in 2007, known as total Lagrangian explicit dynamics (TLED) algorithm, will be discussed with respect to implementation point of view and deploying GPU acceleration (because of its parallel nature to some extent) for both pre-processing and actual computation.

  • 37.
    Baeza Ortega, José Antonio
    Linköping University, Center for Medical Image Science and Visualization, CMIV. Linköping University, Department of Biomedical Engineering. Linköping University, The Institute of Technology.
    Combined Visualization of Intracardiac Blood Flow and Wall Motion Assessed by MRI2011Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    MRI is a well known and widely spread technique to characterize cardiac pathologies due to its high spatial resolution, its accessibility and its adjustable contrast among soft tissues.

    In attempt to close the gap between blood flow, myocardial movement and the cardiac fucntion, researching in the MRI field addresses the quantification of some of the most relevant blood and myocardial parameters.

    During this proyect a new tool that allows reading, postprocessing, quantifying and visualizing 2D motion sense MR data has been developed. In order to analyze intracardiac blood flow and wall motion, the new tool quantifies velocity, turbulent kinetic energy, pressure and strain.

    In the results section the final tool is presented, describing the visualization modes, which represent the quantified parameters both individually and combined; and detailing auxiliary tool features as masking, thresholding, zooming, and cursors.

    Finally, thecnical aspects as the convenience of two dimensional examinations to create compact tools, and the challenges of masking as part of the relative pressure calculation, among others, are discussed; ending up with the proposal of some future developments.

  • 38.
    Wondim, Yonas kassaw
    Linköping University, Department of Biomedical Engineering, Biomedical Instrumentation. Linköping University, The Institute of Technology.
    Hyperspectral Image Analysis Algorithm for Characterizing Human Tissue2011Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    AbstractIn the field of Biomedical Optics measurement of tissue optical properties, like absorption, scattering, and reduced scattering coefficient, has gained importance for therapeutic and diagnostic applications. Accuracy in determining the optical properties is of vital importance to quantitatively determine chromophores in tissue.There are different techniques used to quantify tissue chromophores. Reflectance spectroscopy is one of the most common methods to rapidly and accurately characterize the blood amount and oxygen saturation in the microcirculation. With a hyper spectral imaging (HSI) device it is possible to capture images with spectral information that depends both on tissue absorption and scattering. To analyze this data software that accounts for both absorption and scattering event needs to be developed.In this thesis work an HSI algorithm, capable of assessing tissue oxygenation while accounting for both tissue absorption and scattering, is developed. The complete imaging system comprises: a light source, a liquid crystal tunable filter (LCTF), a camera lens, a CCD camera, control units and power supply for light source and filter, and a computer.This work also presents a Graphic processing Unit (GPU) implementation of the developed HSI algorithm, which is found computationally demanding. It is found that the GPU implementation outperforms the Matlab “lsqnonneg” function by the order of 5-7X.At the end, the HSI system and the developed algorithm is evaluated in two experiments. In the first experiment the concentration of chromophores is assessed while occluding the finger tip. In the second experiment the skin is provoked by UV light while checking for Erythema development by analyzing the oxyhemoglobin image at different point of time. In this experiment the melanin concentration change is also checked at different point of time from exposure.It is found that the result matches the theory in the time dependent change of oxyhemoglobin and deoxyhemoglobin. However, the result of melanin does not correspond to the theoretically expected result.

  • 39.
    Sookthai, Disorn
    Linköping University, Department of Computer and Information Science, Statistics. Linköping University, The Institute of Technology.
    Risk and Predictive Factors for Liver Cancer: Analysis of Data from a Cohort Study2011Independent thesis Advanced level (degree of Master (Two Years)), 30 credits / 45 HE creditsStudent thesis
    Abstract [en]

    The association between the risk of liver cancer and blood chemistry was investigated in a cohort study with 95,150 men and women from two counties in Sweden. In 1963-65, blood tests and physical measurements were undertaken. All individuals were then followed up until 2007, and a total of 312 were diagnosed with liver cancer. Using survival analysis and logistic regression, significant risk factors were identified. Stepwise Cox proportional hazards regression applied to a main effect model revealed that Glutamic Pyruvate Transaminase (GPT) and Thymol Turbidity (TYM) were the most significant risk factors (p<0.0001), followed by Protein-Bound Hexoses (HEX)  (p=0.002), sex (p=0.02), and Serum Iron (p= 0.03). Increasing the level of GPT expressed in U/L from normal (<21) to slightly elevated (21, 31) or substantially elevated (>31) raised the hazard of experiencing liver cancer by a factor of 1.45 and 4.09, respectively. In addition, GPT was found to be the most significant risk factor in almost all age groups among both men and women. However, there was no evidence that elevated GPT levels within the normal range (<21), influenced the risk of liver cancer. Additional subgroup analyses revealed that TYM was highly significant within the group with normal GPT, and a high level of HEX (≥134 mg/dl) increased the hazard 1.55 times in comparison with the lowest HEX group (<115 mg/dl). BMI was significant only in the male subgroup  (p<0.01) and, in the obesity group, the hazard of experiencing liver cancer was 1.99 times higher than in the normal BMI group. A significant three-way interaction between GPT, BMI and gender was present (p=0.05) with a robust significant two-way interaction between GPT and BMI (p<0.01) in the male subgroup.

  • 40.
    Forsgren, Mikael Fredrik
    Linköping University, Department of Medical and Health Sciences, Radiation Physics. Linköping University, Faculty of Health Sciences.
    Human Whole Body Pharmacokinetic Minimal Model for the Liver Specific Contrast Agent Gd-EOB-DTPA2011Independent thesis Advanced level (degree of Master (One Year)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    Magnetic resonance imaging (MRI) of the liver is an important non-invasive tool for diagnosing liver disease. A key application is dynamic contrast enhanced magnetic resonance imaging (DCE-MRI). With the use of the hepatocyte specific contrast agent (CA) Gd-EOB-DTPA it is now possible to evaluate the liver function. Beyond traditional qualitative evaluation of the DCE-MRI images, parametric quantitative techniques are on the rise which yields more objective evaluations. Systems biology is a gradually expanding field using mathematical modeling to gain deeper mechanistic understanding in complex biological systems. The aim of this thesis to combine these two fields in order to derive a physiologically accurate minimal whole body model that can be used to quantitatively evaluate liver function using clinical DCE-MRI examinations. 

    The work is based on two previously published sources of data using Gd-EOB-DTPA in healthy humans; i) a region of interest analysis of the liver using DCE-MRI ii) a pre-clinical evaluation of the contrast agent using blood sampling.  The modeling framework consists of a system of ordinary differential equations for the contrast agent dynamics and non-linear models for conversion of contrast agent concentrations to relaxivity values in the DCE-MRI image volumes.

    Using a χ2-test I have shown that the model, with high probability, can fit the experimental data for doses up to twenty times the clinically used one, using the same parameters for all doses. The results also show that some of the parameters governing the hepatocyte flux of CA can be numerically identifiable. Future applications with the model might be as a basis for regional liver function assessment. This can lead to disease diagnosis and progression evaluation for physicians as well as support for surgeons planning liver resection.

  • 41.
    Samuelsson, Johanna
    Linköping University, Department of Medical and Health Sciences.
    Visualization of Regional Liver Function with Hepatobiliary Contrast Agent Gd-EOB-DTPA2011Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    Liver biopsy is a very common, but invasive procedure for diagnosing liver disease. However, such a biopsy may result in severe complications and in some cases even death. Therefore, it would be highly desirable to develop a non-invasive method which would provide the same amount of information on staging of the disease and also the location of pathologies. This thesis describes the implementation of such a non-invasive method for visualizing and quantifying liver function by the combination of MRI (Magnetic Resonance Imaging), image reconstruction, and image analysis, and pharmacokinetic modeling. The first attempt involved automatic segmentation, functional clustering (k-means) and classification (kNN) of in-data (liver, spleen and blood vessel segments) in the pharmacokinetic model. However, after implementing and analyzing this method some important issues were identified and the image segmentation method was therefore revised. The segmentation method that was subsequently developed involved a semi-automatic procedure, based on a modified image forest transform (IFT). The data were then simulated and optimized using a pharmacokinetic model describing the pharmacokinetics of the liver specific contrast agent Gd-EOB-DTPA in the human body. The output from the modeling procedure was then further analyzed, using a least-squares method, in order to assess liver function by estimating the fractions of hepatocytes, extracellular extravascular space (EES) and blood plasma in each voxel of the image. The result were in fair agreement with literature values, although further analyses and developments will be required in order to validate and also to confirm the accuracy of the method.

  • 42.
    Ahlman, Gustav
    Linköping University, Department of Electrical Engineering, Computer Vision.
    Improved Temporal Resolution Using Parallel Imaging in Radial-Cartesian 3D functional MRI2011Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    MRI (Magnetic Resonance Imaging) is a medical imaging method that uses magnetic fields in order to retrieve images of the human body. This thesis revolves around a novel acquisition method of 3D fMRI (functional Magnetic Resonance Imaging) called PRESTO-CAN that uses a radial pattern in order to sample the (kx,kz)-plane of k-space (the frequency domain), and a Cartesian sample pattern in the ky-direction. The radial sample pattern allows for a denser sampling of the central parts of k-space, which contain the most basic frequency information about the structure of the recorded object. This allows for higher temporal resolution to be achieved compared with other sampling methods since a fewer amount of total samples are needed in order to retrieve enough information about how the object has changed over time. Since fMRI is mainly used for monitoring blood flow in the brain, increased temporal resolution means that we can be able to track fast changes in brain activity more efficiently.The temporal resolution can be further improved by reducing the time needed for scanning, which in turn can be achieved by applying parallel imaging. One such parallel imaging method is SENSE (SENSitivity Encoding). The scan time is reduced by decreasing the sampling density, which causes aliasing in the recorded images. The aliasing is removed by the SENSE method by utilizing the extra information provided by the fact that multiple receiver coils with differing sensitivities are used during the acquisition. By measuring the sensitivities of the respective receiver coils and solving an equation system with the aliased images, it is possible to calculate how they would have looked like without aliasing.In this master thesis, SENSE has been successfully implemented in PRESTO-CAN. By using normalized convolution in order to refine the sensitivity maps of the receiver coils, images with satisfying quality was able to be reconstructed when reducing the k-space sample rate by a factor of 2, and images of relatively good quality also when the sample rate was reduced by a factor of 4. In this way, this thesis has been able to contribute to the improvement of the temporal resolution of the PRESTO-CAN method.

  • 43.
    Sowdamini, Nakka Sravya
    Linköping University, Department of Physics, Chemistry and Biology, Molecular genetics .
    Detection of Bacterial Flora in Biological Secretions  Using Antibodies Developed In Vitro and Immobilized in a  Surface Plasmon Resonance System2011Independent thesis Advanced level (degree of Master (Two Years)), 60 credits / 90 HE creditsStudent thesis
    Abstract [en]

    Identification of pathogens living in biofilms of chronic infections has been difficult with PCR, serological, biochemical and culture techniques. The study aims at the detection of bacterial pathogens in biofilms of biological secretions using SPR analysis Biacore. The antibodies were developed by isolating mononuclear lymphocytes from the blood of the patients who sustained systemic infection. The isolated lymphocytes had antibody secreting B cells (plasma cells) which were identified using flow cytometry analysis. The antibodies produced (n=4) were used to immobilize CM5 chip of Biacore to detect the bacteria in ulcer secretions with wound secretions of healthy volunteers as controls. The results from Surface Plasmon Resonance (SPR) analysis and culture technique were compared and statistically there was no significant difference obtained. The results from present study suggest that SPR analysis could be used as an alternative system for detection of bacteria in poly-microbial samples and detect the organisms that might not be discovered by culture or PCR method.

  • 44.
    Frånlund, Ebba
    Linköping University, Department of Physics, Chemistry and Biology.
    Exon sequencing of the gene encoding UCMA/GRP in healthy and clinical subjects2011Independent thesis Advanced level (degree of Master (One Year)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    Mineralization of soft tissues can cause significantly increased morbidity and mortality. The mechanism for this process is still unknown; however, patients with chronic kidney disease (CKD) are at high risk of developing vascular calcifications. Coronary artery calcification occurs faster in CKD patients undergoing dialysis in comparison with the general population. The pathological process of vascular calcification is the leading cause of death in patients with CKD.

     

    Upper zone of growth plate and cartilage matrix associated protein (UCMA) is a novel vitamin-K dependent (VKD) protein expressed in bone and the vascular system. The UCMA protein contains 15 γ-carboxyglutamic acid (Gla) residues in its 138 residue sequence which is the highest ratio between the number of Gla-residues and the size of the mature protein found in any protein so far. These Gla-residues form a domain that gives unique calcium binding properties for UCMA with high affinity for calcium phosphate crystals (i.e., hydroxyapatite). Even though the function of UCMA remains to be elucidated, it has been speculated that UCMA inhibits calcification of soft tissues and could therefore have a protective function against vascular calcification. Any mutations in the gene coding for UCMA might lead to a diminished function or defective protein.

     

    The aim of this study was to determine whether the gene encoding UCMA in patients with the most progressed stage of CKD (stage 5 CKD) contained any mutations. This was accomplished by performing a full re-sequencing of all five exons with dideoxy sequencing in 16 patients with stage 5 CKD on heamodialysis. If any mutations were discovered, pyrosequencing would be performed on 98 healthy control individuals. This would help to determine if the mutation was exclusive for the patients or existed in the general population as well.

     

    Genomic DNA was extracted from whole blood originating from 16 patients with CKD on haemodialysis. Each of UCMAs five exons were amplified with PCR and the results were visualized using gel electrophoresis. Each exon was re-sequenced and pyrosequencing was performed on 98 healthy control samples. The acquired results were compared with the sequence of the UCMA gene identified at NCBI-GenBank (NCBI, build 37.2, NM_145314.1, Gene ID: 221044) and the Ensemble genome browser (ENSG00000165623). In addition, the frequencies of each SNP were calculated and compared with a study at the Ensemble database originating from the 1000 genomes project (1000GENOMES:low_coverage: CEU).

     

    Because the population of our study group was too small to yield appropriate power for statistical calculations, no definite conclusions could be drawn from the acquired results. Nevertheless, this is the first patient group with CKD ever studied and should thus be regarded as a pilot study due to the limited size. However, no indication was found that UCMA had major defects in the investigated patients. Instead, a heterozygous transversion mutation was found in SNP rs4750328, indicating that the site of this SNP is subject to other modifications. Furthermore, a novel SNP was discovered which has not been described in other populations to our knowledge. The novel SNP is non-synonymous (i.e., causes an amino acid exchange) and located at the carboxyl-terminal of the protein. A serine is incorporated instead of threonine giving a 138Thr>Ser change since the last ACC codon in exon 5 (adjacent to the stop codon) is altered to an AGC codon. The UCMA 138Thr>Ser polymorphism was submitted to the dbSNP database and has been assigned the accession number ss283927876, which will be publicly available upon the release of the next dbSNP Build, B134. In order to determine the physiological significance of the discovered SNP, functional studies are required on both the wild-type and mutated UCMA variants.

  • 45.
    Wallstedt, Maria
    Linköping University, Department of Physics, Chemistry and Biology, Applied Physics .
    Evaluation of blood interactions with a drug loaded protein matrix2011Independent thesis Advanced level (degree of Master (One Year)), 30 credits / 45 HE creditsStudent thesis
    Abstract [en]

    Many things might happen in the body when a titanium implant is inserted into bone. Examples are activation of the immune system and imbalance between bone formation and bone resorption, which might lead to damaged bone around the implant and at worse, loosening of the implant.

    Bisphosphonates, BP’s, is a class of drugs that is able to decrease the osteoclast (bone resorption cell) activity and thereby strengthen the bone. FibMat2.0 is a fibrinogen matrix and consists of a thin protein layer which can be applied on an implant and act as a local drug delivery system.

    The work in this thesis was divided into two parts where aim of the first part was to study FibMat2.0 with integrated BP’s, and their effect in the presence of blood. The aim for the second part was to determine whether it was possible to incorporate antithrombotic drugs into the fibrinogen matrix. No detection method for the amount of drugs incorporated into the fibrinogen matrix was used but the fact that the drugs gave effect was verifying that it is possible to integrate other drugs than BP’s into FibMat2.0. Methods that have been used in the experiments in presence of blood are imaging of coagulation, fluorescence microscopy and cone-and-plate.

    For the first part, the results showed that surfaces incubated with fibrinogen and fibrinogen with integrated BP’s act alike in regard to coagulation and platelet adhesion. Compared to titanium, which is known to be a biocompatible material, the surfaces with fibrinogen and fibrinogen with BP’s behave similar in regard to platelet adhesion. When it comes to coagulation, the surfaces coated with fibrinogen with or without an addition of BP’s have shown a longer coagulation time compared to the clean titanium surface.

    For the second part, some conclusions have been drawn according to the results. Heparin and hirudin have shown anticoagulant effects when integrated in the matrix. The platelet inhibitor cangrelor seemed to have better effect when added in blood and incubated compared to incubation with the platelet inhibitor on the surface before incubation in blood. Finally, when combining heparin and cangrelor, very clear differences in regard to formation of fibrin network could be seen. It seems promising to be able to load different kind of drugs in FibMat2.0.

  • 46.
    Bergman, Nina
    Linköping University, Department of Physics, Chemistry and Biology.
    Sample preparation of 8-hydroxy-2’-deoxyguanosine with solid phase extraction methodology based on molecular imprinting polymers and conventional silica based phases2011Independent thesis Basic level (degree of Bachelor), 10,5 credits / 16 HE creditsStudent thesis
    Abstract [en]

    The aim of this study was to develop methods for sample preparation for 8-OHdG in blood plasma samples with different solid phase extraction techniques using HPLC with an elec- trochemical detector. The solid phase extraction cartridges used were Chromabond® C18, Oasis® MAX, and three types of SupelMIPTM cartridges for chloramphenicol, riboflavin, and nitroimidazoles. The SupelMIPTM cartridges are based on molecularly imprinted polymers- technique. The separation of 8-OHdG in samples extracted from blood plasma was carried out with a Thermo Quest Hypersil Division ODS column (250 mm × 4 mm, 3μm I.D.) and methanol:buffer (10:90, v/v) as mobile phase. Recovery and selectivity was studied for the different solid phase extraction methods. The highest recovery was obtained using the Chromabond C18 cartridge with a recovery of 92%, and CV coefficient 9.5% (n = 4). 8-OHdG could not be extracted on MIP-cartridges for chloramphenicol or riboflavin, but was retained on MIP columns for nitroimidazoles, and the highest recovery was 49%.

  • 47.
    Sammartano, Chiara
    Linköping University, Department of Management and Engineering, Applied Thermodynamics and Fluid Mechanics.
    Simulation of radio-frequency ablation of liver tumors: Development of a power regulation model and comparison with microwave ablation2011Independent thesis Advanced level (degree of Master (One Year)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    Local therapy with radiofrequency ablation (RFA) is an important method for treating liver tumors mostly in early stage, which has been increasingly used in recent years.

    RFA utilizes an RF current that is applied to the target tissue through an electrode connected with a power generator and percutaneously inserted into the tumor; the electrode power causes the tissue temperature rise required for destroying cancer cells.

    If RF thermal ablation entails numerous advantages - such as high repeatability of treatments, suitability for patients who can‟t undergo surgery, quick procedure and fast recovery -, there are still some inconveniences and difficulties coupled with this technique. One of these problems is the so called heat sink effects, resulting from the presence of large blood vessels close to the electrode tip.

    First, an overview is given of RFA physical background and heat transfer models followed by the improvement of a model of RF ablation in the liver. Second, special attention has been given to the mesh settings so that the simulation model could benefit from an appropriate mesh in terms of resolution and accuracy of the results obtained and in terms of reduced computational time. Then, a large part of the work has been dedicated to the development of a power regulation (PR) aiming at an optimization of the thermal treatment although the presence of large blood vessels in the ablation area and at an abatement of the number of residual tumors. Finally, a comparison work has been conducted between two different ablation modalities (RF versus MW) showing similarities and differences until the conclusion that currently the RFA treatment is the most suitable treatment for tumors in early stage, small and localized.

  • 48.
    Wickström, Anette
    Linköping University, Department of Culture and Communication. Linköping University, Faculty of Arts and Sciences.
    Virginity Testing as a Local Public Health Initiative2009Conference paper (Refereed)
    Abstract [en]

    This paper focuses on virginity testing in Nkolokotho in northeastern rural KwaZulu Natal. I argue that testing is a strategy that involves the deployment of collective pressure and symbolic means both to increase the indivual's and the community's responsibility for sexual relations, and to strengthen girls' and women's positions at a time of chronic HIV/AIDS. In the absence of effective measures against AIDS, inhabitants try to find alternative ways to protect young people. An older tradition that emphasizies the status of virgin girls and the significance of the collective is used in a strategy that incorporates HIV blood tests. I show how virginity testing is a 'preventive ritual' more than a 'diagnostic measure', while emphasizing how both South African and Western projects aimed at improving the situation are grounded in perspectives that sometimes collide with how local people conceive of both relationships and sexuality.

  • 49. Wong, Liza S M
    et al.
    Huzen, Jardi
    van der Harst, Pim
    de Boer, Rudolf A
    Codd, Veryan
    Westenbrink, B Daan
    Benus, Germaine F J D
    Voors, Adriaan A
    van Gilst, Wiek H
    Samani, Nilesh J
    Jaarsma, Tiny
    van Veldhuisen, Dirk J
    Anaemia is associated with shorter leucocyte telomere length in patients with chronic heart failure.2010In: European Journal of Heart Failure, ISSN 1388-9842, E-ISSN 1879-0844, Vol. 12, no 4, 348-53 p.Article in journal (Refereed)
    Abstract [en]

    AIMS: Anaemia is highly prevalent and associated with poor prognosis in patients with chronic heart failure (CHF). Reduced erythroid proliferation capacity of haematopoietic progenitor cells is associated with reduced telomere length, a marker of cellular ageing. We hypothesize that short telomere length contributes to the susceptibility to develop anaemia in patients with CHF. METHODS AND RESULTS: We studied 875 CHF patients, of whom 254 (29%) fulfilled the WHO criteria of anaemia. Telomere length in DNA from peripheral leucocytes was measured with real-time quantitative polymerase chain reaction. Age, gender, and baseline differences adjusted telomere length was correlated with haemoglobin levels (partial r = 0.130; P = 0.011). One standard deviation shorter telomere length was associated with an increased risk of having anaemia [odds ratio (OR), 1.31; 95% confidence interval (CI), 1.12-1.53; P = 0.001]. This observation was not affected by adjustment for potential confounders (OR, 1.38; 95% CI, 1.05-1.81; P = 0.021 after adjustment for age, gender, erythropoietin levels, renal function, left ventricular ejection fraction, age of CHF onset, blood pressure, history of stroke, diabetes, and B-type natriuretic peptide levels). CONCLUSION: Shorter telomere length increases the odds of having anaemia in CHF patients. This finding supports the hypothesis that cellular ageing in CHF contributes to the susceptibility to develop anaemia.

  • 50. Vermeulen, Robert P
    et al.
    Hoekstra, Miriam
    Nijsten, Maarten Wn
    van der Horst, Iwan C
    van Pelt, L Joost
    Jessurun, Gillian A
    Jaarsma, Tiny
    Zijlstra, Felix
    van den Heuvel, Ad F
    Clinical correlates of arterial lactate levels in patients with ST-segment elevation myocardial infarction at admission: a descriptive study2010In: Critical Care, ISSN 1364-8535, E-ISSN 1466-609X, Vol. 14, no 5, R164- p.Article in journal (Refereed)
    Abstract [en]

    ABSTRACT : INTRODUCTION : Blood lactate measurements can be used as an indicator of hemodynamic impairment and relate to mortality in various forms of shock. Little is known at the moment concerning the clinical correlates of systemic lactate in patients with ST-segment elevation myocardial infarction (STEMI). METHODS : To assess the relation of systemic arterial lactate levels in STEMI patients with clinical correlates at presentation in the catheterization laboratory, we measured arterial lactate levels with a rapid point-of-care technique, immediately following femoral sheath insertion. The study population (n= 1,176) was divided into tertiles with lactate levels ≤1.1 (n = 410), 1.2 to 1.7 (n = 398) and ≥1.8 mmol/l (n = 368). We compared both baseline characteristics and outcome measures of the three lactate groups. RESULTS : Factors independently associated with higher lactate levels were hypotension, heart rate, thrombolysis in myocardial infarction (TIMI) flow 0 to 1, diabetes and non-smoking. Mortality at 30 days in the three groups was 2.0%, 1.5% and 6.5%. The latter group also showed lower blush grades and greater enzymatic infarct sizes. An intra aortic balloon pump (IABP) was used more frequently in patients with higher lactate levels (4.2%, 7.6% and 14.7%). CONCLUSIONS : In STEMI patients, impaired hemodynamics, worse TIMI flow and non-smoking were related to increased arterial lactate levels. Higher lactate levels were independently related with 30-day mortality and an overall worse response to percutaneous coronary intervention (PCI). In particular, acute mortality was related to admission lactates ≥1.8 mmol/L. Point-of-care measurement of arterial lactate at admission in patients with STEMI has the potential to improve acute risk stratification.

1234567 1 - 50 of 2875
CiteExportLink to result list
Permanent link
Cite
Citation style
  • apa
  • harvard1
  • ieee
  • modern-language-association-8th-edition
  • vancouver
  • Other style
More styles
Language
  • de-DE
  • en-GB
  • en-US
  • fi-FI
  • nn-NO
  • nn-NB
  • sv-SE
  • Other locale
More languages
Output format
  • html
  • text
  • asciidoc
  • rtf