liu.seSearch for publications in DiVA
Change search
Refine search result
3456789 251 - 300 of 511
CiteExportLink to result list
Permanent link
Cite
Citation style
  • apa
  • ieee
  • modern-language-association-8th-edition
  • vancouver
  • oxford
  • 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
  • Issued (Oldest first)
  • Issued (Newest first)
  • Created (Oldest first)
  • Created (Newest first)
  • Last updated (Oldest first)
  • Last updated (Newest first)
  • Disputation date (earliest first)
  • Disputation date (latest first)
  • Standard (Relevance)
  • Author A-Ö
  • Author Ö-A
  • Title A-Ö
  • Title Ö-A
  • Publication type A-Ö
  • Publication type Ö-A
  • Issued (Oldest first)
  • Issued (Newest first)
  • Created (Oldest first)
  • Created (Newest first)
  • Last updated (Oldest first)
  • Last updated (Newest first)
  • Disputation date (earliest first)
  • Disputation date (latest first)
Select
The maximal number of hits you can export is 250. When you want to export more records please use the Create feeds function.
  • 251.
    Lindblom, Emely
    et al.
    Stockholm University.
    Dasu, Alexandru
    Linköping University, Department of Medical and Health Sciences, Division of Radiological Sciences. Linköping University, Faculty of Medicine and Health Sciences. Östergötlands Läns Landsting, Center for Surgery, Orthopaedics and Cancer Treatment, Department of Radiation Physics.
    Toma-Dasu, Iuliana
    Stockholm University and Karolinska Institutet.
    Optimal fractionation in radiotherapy for non-small cell lung cancer - a modelling approach2015In: Acta Oncologica, ISSN 0284-186X, E-ISSN 1651-226X, Vol. 54, no 9, p. 1592-1598Article in journal (Refereed)
    Abstract [en]

    Background. Conventionally fractionated radiotherapy (CFRT) has proven ineffective in treating non-small cell lung cancer while more promising results have been obtained with stereotactic body radiotherapy (SBRT). Hypoxic tumours, however, might present a challenge to extremely hypofractionated schedules due to the decreased possibility for inter-fraction fast reoxygenation. A potentially successful compromise might be found in schedules employing several fractions of varying fractional doses. In this modelling study, a wide range of fractionation schedules from single-fraction treatments to heterogeneous, multifraction schedules taking into account repair, repopulation, reoxygenation and radiosensitivity of the tumour cells, has been explored with respect to the probability of controlling lung tumours.

    Material and methods. The response to radiation of tumours with heterogeneous spatial and temporal oxygenation was simulated including the effects of accelerated repopulation and intra-fraction repair. Various treatments with respect to time, dose and fractionation were considered and the outcome was estimated as Poisson-based tumour control probability for local control.

    Results. For well oxygenated tumours, heterogeneous fractionation could increase local control while hypoxic tumours are not efficiently targeted by such treatments despite reoxygenation. For hypofractionated treatments employing large doses per fraction, a synergistic effect was observed between intra-fraction repair and inter-fraction fast reoxygenation of the hypoxic cells as demonstrated by a reduction in D50 from 53.3 Gy for 2 fractions to 52.7 Gy for 5 fractions.

    Conclusions. For well oxygenated tumours, heterogeneous fractionation schedules could increase local control rates substantially compared to CFRT. For hypoxic tumours, SBRT-like hypofractionated schedules might be optimal despite the increased risk of intra-fraction repair due to a synergistic effect with inter-fraction reoxygenation.

  • 252.
    Lindblom, Emely
    et al.
    Stockholm University, Sweden.
    Dasu, Alexandru
    Linköping University, Department of Medical and Health Sciences, Division of Radiological Sciences. Linköping University, Faculty of Medicine and Health Sciences. The Skandion Clinic, Uppsala, Sweden.
    Uhrdin, Johan
    RaySearch Laboratories AB.
    Even, Aniek J. G.
    Maastricht University Medical Center, Maastricht, The Netherlands.
    van Elmpt, Wouter
    Maastricht University Medical Center, Maastricht, The Netherlands.
    Lambin, Philippe
    Maastricht University Medical Center, Maastricht, The Netherlands.
    Wersäll, Peter
    Karolinska University Hospital, Stockholm, Sweden.
    Toma-Dasu, Iuliana
    Stockholm University and Karolinska Institutet, Sweden.
    Defining the hypoxic target volume based on positron emission tomography for image guided radiotherapy - the influence of the choice of the reference region and conversion function2017In: Acta Oncologica, ISSN 0284-186X, E-ISSN 1651-226X, Vol. 56, no 6, p. 819-825Article in journal (Refereed)
    Abstract [en]

    Background: Hypoxia imaged by positron emission tomography (PET) is a potential target for optimization in radiotherapy. However, the implementation of this approach with respect to the conversion of intensities in the images into oxygenation and radiosensitivity maps is not straightforward. This study investigated the feasibility of applying two conversion approaches previously derived for 18F-labeled fluoromisonidazole (18F-FMISO)-PET images for the hypoxia tracer 18F-flortanidazole (18F-HX4).

    Material and methods: Ten non-small-cell lung cancer patients imaged with 18F-HX4 before the start of radiotherapy were considered in this study. PET image uptake was normalized to a well-oxygenated reference region and subsequently linear and non-linear conversions were used to determine tissue oxygenations maps. These were subsequently used to delineate hypoxic volumes based partial oxygen pressure (pO2) thresholds. The results were compared to hypoxic volumes segmented using a tissue-to-background ratio of 1.4 for 18F-HX4 uptake.

    Results: While the linear conversion function was not found to result in realistic oxygenation maps, the non-linear function resulted in reasonably sized sub-volumes in good agreement with uptake-based segmented volumes for a limited range of pO2 thresholds. However, the pO2 values corresponding to this range were significantly higher than what is normally considered as hypoxia. The similarity in size, shape, and relative location between uptake-based sub-volumes and volumes based on the conversion to pO2 suggests that the relationship between uptake and pO2 is similar for 18F-FMISO and 18F-HX4, but that the model parameters need to be adjusted for the latter.

    Conclusions: A non-linear conversion function between uptake and oxygen partial pressure for 18F-FMISO-PET could be applied to 18F-HX4 images to delineate hypoxic sub-volumes of similar size, shape, and relative location as based directly on the uptake. In order to apply the model for e.g., dose-painting, new parameters need to be derived for the accurate calculation of dose-modifying factors for this tracer.

  • 253.
    Lindblom, Emely
    et al.
    Department of Physics, Stockholm University, Stockholm, Sweden.
    Toma-Dasu, Iuliana
    Department of Physics, Stockholm University, Stockholm, Sweden / Department of Oncology and Pathology, Karolinska Institutet, Solna, Sweden.
    Dasu, Alexandru
    Linköping University, Department of Medical and Health Sciences, Division of Radiological Sciences. Linköping University, Faculty of Medicine and Health Sciences. The Skandion Clinic, Uppsala, Sweden.
    Accounting for Two Forms of Hypoxia for Predicting Tumour Control Probability in Radiotherapy: An In Silico Study2018In: Oxygen Transport to Tissue XL / [ed] Oliver Thews, Joseph C. LaManna and David K. Harrison, Cham: Springer, 2018, Vol. 1072, p. 183-187Chapter in book (Refereed)
    Abstract [en]

    The progress in functional imaging and dose delivery has opened the possibility of targeting tumour hypoxia with radiotherapy. Advanced approaches apply quantitative information on tumour oxygenation retrieved from imaging in dose prescription. These do not, however, take into account the potential difference in radiosensitivity of chronically and acutely hypoxic cells. It was the aim of this study to evaluate the implications of assuming the same or different sensitivities for the hypoxic cells. An in silico 3D-model of a hypoxic tumour with heterogeneous oxygenation was used to model the probabilities of tumour control with different radiotherapy regimens. The results show that by taking into account the potential lower radioresistance of chronically hypoxic cells deprived of oxygen and nutrients, the total dose required to achieve a certain level of control is substantially reduced for a given fractionation scheme in comparison to the case when chronically and acutely hypoxic cells are assumed to have similar features. The results also suggest that the presence of chronic hypoxia could explain the success of radiotherapy for some hypoxic tumours. Given the implications for clinical dose escalation trials, further exploration of the influence of the different forms of hypoxia on treatment outcome is therefore warranted.

  • 254.
    Lindborg, Lennart
    et al.
    Karolinska Institute, Sweden.
    Hultqvist, Martha
    RaySearch Labs, Sweden.
    Carlsson Tedgren, Åsa
    Linköping University, Department of Medical and Health Sciences, Division of Radiological Sciences. Linköping University, Faculty of Medicine and Health Sciences. Region Östergötland, Center for Surgery, Orthopaedics and Cancer Treatment, Department of Radiation Physics. Swedish Radiat Safety Author, Sweden.
    Nikjoo, Hooshang
    Karolinska Institute, Sweden.
    Nanodosimetry and RBE values in radiotherapy2015In: Radiation Protection Dosimetry, ISSN 0144-8420, E-ISSN 1742-3406, Vol. 166, no 1-4, p. 339-342Article in journal (Refereed)
    Abstract [en]

    In a recent paper, the authors reported that the dose mean lineal energy, (y) over bar (D) in a volume of about 10-15 nm is approximately proportional to the alpha-parameter in the linear-quadratic relation used in fractionated radiotherapy in both low- and high-LET beams. This was concluded after analyses of reported radiation weighting factors, W-isoE (clinical RBE values), and (y) over bar (D) values in a large range of volumes. Usually, microdosimetry measurements in the nanometer range are difficult; therefore, model calculations become necessary. In this paper, the authors discuss the calculation method. A combination of condensed history Monte Carlo and track structure techniques for calculation of mean lineal energy values turned out to be quite useful. Briefly, the method consists in weighting the relative dose fractions of the primary and secondary charged particles with their respective energy-dependent dose mean lineal energies. The latter were obtained using a large database of Monte Carlo track structure calculations.

  • 255.
    Lindström, Jan
    et al.
    Karolinska Univ. Hospital, Sweden.
    Hulthén, Markus
    Karolinska Univ. Hospital, Sweden.
    Alm Carlsson, Gudrun
    Linköping University, Department of Medical and Health Sciences, Division of Radiological Sciences. Linköping University, Faculty of Health Sciences. Linköping University, Center for Medical Image Science and Visualization (CMIV). Östergötlands Läns Landsting, Center for Surgery, Orthopaedics and Cancer Treatment, Department of Radiation Physics.
    Sandborg, Michael
    Linköping University, Department of Medical and Health Sciences, Division of Radiological Sciences. Linköping University, Faculty of Health Sciences. Linköping University, Center for Medical Image Science and Visualization (CMIV). Östergötlands Läns Landsting, Center for Surgery, Orthopaedics and Cancer Treatment, Department of Radiation Physics.
    Optimizing two radioluminescence based quality assurance devices for diagnostic radiology utilizing a simple model2014In: Medical Imaging 2014: Physics of Medical Imaging / [ed] Bruce R. Whiting; Christoph Hoeschen, SPIE - International Society for Optical Engineering, 2014, Vol. 9033, p. 90333R-1-90333R-15Conference paper (Refereed)
    Abstract [en]

    The extrinsic (absolute) efficiency of a phosphor is expressed as the ratio of light energy emitted per unit area at the phosphor surface to incident x-ray energy fluence. A model described in earlier work has shown that by knowing the intrinsic efficiency, the particle size, the thickness and the light extinction factor ξ, it is possible to deduce the extrinsic efficiency for an extended range of particle sizes and layer thicknesses for a given design. The model has been tested on Gd 2O2S:Tb and ZnS:Cu fluorescent layers utilized in two quality assurance devices, respectively, aimed for the assessment of light field and radiation field congruence in diagnostic radiology. The first unit is an established device based on both fluorescence and phosphorescence containing an x-ray sensitive phosphor (ZnS:Cu) screen comprising a long afterglow. Uncertainty in field edge position is estimated to 0.8 mm (k=2). The second unit is under development and based on a linear CCD sensor which is sensitized to x-rays by applying a Gd 2O2S:Tb scintillator. The field profiles and the corresponding edge location are then obtained and compared. Uncertainty in field edge location is estimated to

    0.1 mm (k=2). The properties of the radioluminescent layers are essential for the functionality of the devices and have been optimized utilizing the previously developed and verified model. A theoretical description of the maximization of phosphorescence is also briefly discussed as well as an interesting finding encountered during the development processes: focal spot wandering. The oversimplistic physical assumptions made in the radioluminescence model have not been found to lead the optimizing process astray. The obtained functionality is believed to be adequate within their respective limitations for both devices.

  • 256.
    Linge, Jennifer
    et al.
    AMRA Med AB, Linkoping, Sweden.
    Borga, Magnus
    Linköping University, Department of Biomedical Engineering, Division of Biomedical Engineering. Linköping University, Faculty of Science & Engineering. Linköping University, Center for Medical Image Science and Visualization (CMIV). AMRA Med AB, Linkoping, Sweden.
    West, Janne
    Linköping University, Department of Medical and Health Sciences, Division of Radiological Sciences. Linköping University, Center for Medical Image Science and Visualization (CMIV). Linköping University, Faculty of Medicine and Health Sciences.
    Tuthill, Theresa
    Pfizer Inc, MA USA.
    Miller, Melissa R.
    Pfizer Inc, MA USA.
    Dumitriu, Alexandra
    Pfizer Inc, MA USA.
    Thomas, E. Louise
    Univ Westminster, England.
    Romu, Thobias
    Linköping University, Department of Biomedical Engineering. Linköping University, Faculty of Science & Engineering. Linköping University, Center for Medical Image Science and Visualization (CMIV). AMRA Med AB, Linkoping, Sweden.
    Tunon, Patrik
    AMRA Med AB, Linkoping, Sweden.
    Bell, Jimmy D.
    Univ Westminster, England.
    Dahlqvist Leinhard, Olof
    Linköping University, Department of Medical and Health Sciences, Division of Radiological Sciences. Linköping University, Faculty of Medicine and Health Sciences. Region Östergötland, Center for Surgery, Orthopaedics and Cancer Treatment, Department of Radiation Physics. Linköping University, Center for Medical Image Science and Visualization (CMIV). AMRA Med AB, Linkoping, Sweden.
    Body Composition Profiling in the UK Biobank Imaging Study2018In: Obesity, ISSN 1930-7381, E-ISSN 1930-739X, Vol. 26, no 11, p. 1785-1795Article in journal (Refereed)
    Abstract [en]

    ObjectiveMethodsThis study aimed to investigate the value of imaging-based multivariable body composition profiling by describing its association with coronary heart disease (CHD), type 2 diabetes (T2D), and metabolic health on individual and population levels. The first 6,021 participants scanned by UK Biobank were included. Body composition profiles (BCPs) were calculated, including abdominal subcutaneous adipose tissue, visceral adipose tissue (VAT), thigh muscle volume, liver fat, and muscle fat infiltration (MFI), determined using magnetic resonance imaging. Associations between BCP and metabolic status were investigated using matching procedures and multivariable statistical modeling. ResultsConclusionsMatched control analysis showed that higher VAT and MFI were associated with CHD and T2D (Pamp;lt;0.001). Higher liver fat was associated with T2D (Pamp;lt;0.001) and lower liver fat with CHD (Pamp;lt;0.05), matching on VAT. Multivariable modeling showed that lower VAT and MFI were associated with metabolic health (Pamp;lt;0.001), and liver fat was nonsignificant. Associations remained significant adjusting for sex, age, BMI, alcohol, smoking, and physical activity. Body composition profiling enabled an intuitive visualization of body composition and showed the complexity of associations between fat distribution and metabolic status, stressing the importance of a multivariable approach. Different diseases were linked to different BCPs, which could not be described by a single fat compartment alone.

    Download full text (pdf)
    fulltext
  • 257.
    Linge, Jennifer
    et al.
    Advanced MR Analytics AB, Linköping, Sweden.
    West, Janne
    Linköping University, Center for Medical Image Science and Visualization (CMIV). Linköping University, Department of Medical and Health Sciences, Division of Radiological Sciences. Linköping University, Faculty of Medicine and Health Sciences.
    Romu, Thobias
    Linköping University, Department of Biomedical Engineering, Medical Informatics. Linköping University, Center for Medical Image Science and Visualization (CMIV). Linköping University, Faculty of Science & Engineering.
    Borga, Magnus
    Linköping University, Center for Medical Image Science and Visualization (CMIV). Linköping University, Department of Biomedical Engineering, Medical Informatics. Linköping University, Faculty of Science & Engineering.
    Bell, Jimmy
    Westminster University, London, UK.
    Dahlqvist Leinhard, Olof
    Linköping University, Center for Medical Image Science and Visualization (CMIV). Linköping University, Department of Medical and Health Sciences, Division of Radiological Sciences. Linköping University, Faculty of Medicine and Health Sciences. Region Östergötland, Center for Surgery, Orthopaedics and Cancer Treatment, Department of Radiation Physics.
    The Body Composition Profile – Enhancing the Understanding of Obesity using UK Biobank Imaging Data2017Conference paper (Refereed)
  • 258.
    Linge, Jennifer
    et al.
    AMRA Medical AB, Linköping, Sweden.
    Whitcher, Brandon
    AMRA Medical AB, Linköping, Sweden.
    Borga, Magnus
    Linköping University, Center for Medical Image Science and Visualization (CMIV). Linköping University, Department of Biomedical Engineering, Division of Biomedical Engineering. Linköping University, Faculty of Science & Engineering. AMRA Medical AB, Linköping, Sweden.
    Dahlqvist Leinhard, Olof
    Linköping University, Department of Medical and Health Sciences, Division of Radiological Sciences. Linköping University, Faculty of Medicine and Health Sciences. Linköping University, Center for Medical Image Science and Visualization (CMIV). Region Östergötland, Center for Diagnostics, Medical radiation physics. AMRA Medical AB, Linköping, Sweden.
    Sub-phenotyping Metabolic Disorders Using Body Composition: An Individualized, Nonparametric Approach Utilizing Large Data Sets2019In: Obesity, ISSN 1930-7381, E-ISSN 1930-739X, Vol. 27, no 7, p. 1190-1199Article in journal (Refereed)
    Abstract [en]

    Objective: This study performed individual-centric, data-driven calculations of propensity for coronary heart disease (CHD) and type 2 diabetes (T2D), utilizing magnetic resonance imaging-acquired body composition measurements, for sub-phenotyping of obesity and nonalcoholic fatty liver disease (NAFLD).Methods: A total of 10,019 participants from the UK Biobank imaging substudy were included and analyzed for visceral and abdominal subcutaneous adipose tissue, muscle fat infiltration, and liver fat. An adaption of the k-nearest neighbors algorithm was applied to the imaging variable space to calculate individualized CHD and T2D propensity and explore metabolic sub-phenotyping within obesity and NAFLD.

    Results: The ranges of CHD and T2D propensity for the whole cohort were 1.3% to 58.0% and 0.6% to 42.0%, respectively. The diagnostic performance, area under the receiver operating characteristic curve (95% CI), using disease propensities for CHD and T2D detection was 0.75 (0.73-0.77) and 0.79 (0.77-0.81). Exploring individualized disease propensity, CHD phenotypes, T2D phenotypes, comorbid phenotypes, and metabolically healthy phenotypes were found within obesity and NAFLD.

    Conclusions: The adaptive k-nearest neighbors algorithm allowed an individual-centric assessment of each individual’s metabolic phenotype moving beyond discrete categorizations of body composition. Within obesity and NAFLD, this may help in identifying which comorbidities a patient may develop and conse- quently enable optimization of treatment.

    Download full text (pdf)
    fulltext
  • 259.
    Linge, Jennifer
    et al.
    Advanced MR Analytics AB, Linköping, Sweden.
    Whithcher, Brandon
    Advanced MR Analytics AB, Linköping, Sweden.
    Dimitriu, Alexandra
    Pfizer inc. Cambridge, MA, USA.
    Borga, Magnus
    Linköping University, Department of Biomedical Engineering, Medical Informatics. Linköping University, Faculty of Science & Engineering. Linköping University, Center for Medical Image Science and Visualization (CMIV).
    Dahlqvist Leinhard, Olof
    Linköping University, Department of Medical and Health Sciences, Division of Radiological Sciences. Linköping University, Faculty of Medicine and Health Sciences. Linköping University, Center for Medical Image Science and Visualization (CMIV). Region Östergötland, Center for Surgery, Orthopaedics and Cancer Treatment, Department of Radiation Physics.
    Associating Body Composition Profiling to Propensity for Diabetes2017Conference paper (Refereed)
  • 260.
    Ljung, Patric
    et al.
    Linköping University, Department of Science and Technology, Media and Information Technology. Linköping University, Faculty of Science & Engineering.
    Winskog, Calle
    Persson, Anders
    Linköping University, Department of Medical and Health Sciences, Division of Radiological Sciences. Linköping University, Faculty of Medicine and Health Sciences. Linköping University, Center for Medical Image Science and Visualization (CMIV). Östergötlands Läns Landsting, Center for Diagnostics, Department of Radiology in Linköping.
    Lundström, Claes
    Linköping University, Department of Science and Technology, Media and Information Technology. Linköping University, Faculty of Science & Engineering. Linköping University, Center for Medical Image Science and Visualization (CMIV).
    Ynnerman, Anders
    Linköping University, Department of Science and Technology, Media and Information Technology. Linköping University, Faculty of Science & Engineering. Linköping University, Center for Medical Image Science and Visualization (CMIV).
    Full Body Virtual Autopsies using a State-of-the-art Volume Rendering Pipeline2006In: IEEE Transactions on Visualization and Computer Graphics, ISSN 1077-2626, Vol. 12, no 5, p. 869-876Article in journal (Refereed)
    Abstract [en]

    This paper presents a procedure for virtual autopsies based on interactive 3D visualizations of large scale, high resolution data from CT-scans of human cadavers. The procedure is described using examples from forensic medicine and the added value and future potential of virtual autopsies is shown from a medical and forensic perspective. Based on the technical demands of the procedure state-of-the-art volume rendering techniques are applied and refined to enable real-time, full body virtual autopsies involving gigabyte sized data on standard GPUs. The techniques applied include transfer function based data reduction using levelof- detail selection and multi-resolution rendering techniques. The paper also describes a data management component for large, out-of-core data sets and an extension to the GPU-based raycaster for efficient dual TF rendering. Detailed benchmarks of the pipeline are presented using data sets from forensic cases.

  • 261.
    Lowén, Mats B. O.
    et al.
    Linköping University, Department of Clinical and Experimental Medicine, Division of Neuro and Inflammation Science. Linköping University, Faculty of Medicine and Health Sciences.
    Mayer, E.
    Oppenheimer Center for Neurobiology of Stress, Division of Digestive Diseases, Department of Medicine, David Geffen School of Medicine at UCLA, Los Angeles, CA, USA.
    Tillisch, K.
    Oppenheimer Center for Neurobiology of Stress, Division of Digestive Diseases, Department of Medicine, David Geffen School of Medicine at UCLA, Los Angeles, CA, USA.
    Labus, J.
    Oppenheimer Center for Neurobiology of Stress, Division of Digestive Diseases, Department of Medicine, David Geffen School of Medicine at UCLA, Los Angeles, CA, USA.
    Naliboff, B.
    Oppenheimer Center for Neurobiology of Stress, Division of Digestive Diseases, Department of Medicine, David Geffen School of Medicine at UCLA, Los Angeles, CA, USA.
    Lundberg, Peter
    Linköping University, Center for Medical Image Science and Visualization (CMIV). Linköping University, Department of Medical and Health Sciences, Division of Radiological Sciences. Linköping University, Faculty of Medicine and Health Sciences. Region Östergötland, Center for Surgery, Orthopaedics and Cancer Treatment, Department of Radiation Physics.
    Thorell, Lars-Håkan
    Emotra AB, Gothenburg, Sweden.
    Ström, Magnus
    Linköping University, Department of Clinical and Experimental Medicine, Division of Neuro and Inflammation Science. Linköping University, Faculty of Medicine and Health Sciences. Region Östergötland, Heart and Medicine Center, Department of Gastroentorology.
    Engström, Maria
    Linköping University, Center for Medical Image Science and Visualization (CMIV). Linköping University, Department of Medical and Health Sciences, Division of Radiological Sciences. Linköping University, Faculty of Medicine and Health Sciences.
    Walter, Susanna
    Linköping University, Department of Clinical and Experimental Medicine, Division of Neuro and Inflammation Science. Linköping University, Faculty of Medicine and Health Sciences. Region Östergötland, Heart and Medicine Center, Department of Gastroentorology.
    Deficient habituation to repeated rectal distensions in irritable bowel syndrome patients with visceral hypersensitivity2015In: Neurogastroenterology and Motility, ISSN 1350-1925, E-ISSN 1365-2982, Vol. 27, no 5, p. 646-655Article in journal (Refereed)
    Abstract [en]

    Background Irritable bowel syndrome (IBS) patients show evidence of altered central processing of visceral signals. One of the proposed alterations in sensory processing is an altered engagement of endogenous pain modulation mechanisms. The aim was to test the hypothesis that IBS patients with (IBS-S) and without visceral hypersensitivity (IBS-N) differ in their ability to engage endogenous pain modulation mechanism during habituation to repeated visceral stimuli.

    Methods Brain blood oxygen level dependent (BOLD) response was measured during repeated rectal distension and its anticipation in 33 IBS patients with and without visceral hypersensitivity and 18 healthy controls (HCs). BOLD response to early and late phase of the distension series was compared within and between groups.

    Key Results While BOLD response was similar during the early phase of the experiment, IBS-S showed greater BOLD response than IBS-N and HCs during the late phase of the distension series. IBS-S showed increasing BOLD response both to the anticipation and delivery of low intensity rectal distensions in brain regions including insula, anterior and mid cingulate cortex. IBS-N showed decreasing BOLD response to repeated rectal distensions in brain regions including insula, prefrontal cortex and amygdala.

    Conclusions & Inferences These findings are consistent with compromised ability of IBS-S to respond to repeated delivery of rectal stimuli, both in terms of sensitization of sensory pathways and habituation of emotional arousal. The fact that both IBS subgroups met Rome criteria, and did not differ in terms of reported symptom severity demonstrates that similar symptom patterns can result from different underlying neurobiological mechanisms.

  • 262.
    Lowén, Mats
    et al.
    Linköping University, Department of Clinical and Experimental Medicine. Linköping University, Faculty of Health Sciences. Linköping University, Center for Medical Image Science and Visualization (CMIV). Östergötlands Läns Landsting, Local Health Care Services in Central Östergötland, Department of Geriatric Medicine in Linköping.
    Mayer, E A.
    University of Calif Los Angeles, CA USA .
    Sjoberg, M
    Karolinska Institute, Sweden .
    Tillisch, K
    University of Calif Los Angeles, CA USA .
    Naliboff, B
    University of Calif Los Angeles, CA USA .
    Labus, J
    University of Calif Los Angeles, CA USA .
    Lundberg, Peter
    Linköping University, Center for Medical Image Science and Visualization (CMIV). Linköping University, Department of Medical and Health Sciences, Division of Radiological Sciences. Linköping University, Faculty of Health Sciences. Östergötlands Läns Landsting, Center for Surgery, Orthopaedics and Cancer Treatment, Department of Radiation Physics. Östergötlands Läns Landsting, Center for Diagnostics, Department of Radiology in Linköping.
    Ström, Magnus
    Linköping University, Department of Clinical and Experimental Medicine, Gastroenterology and Hepatology. Linköping University, Faculty of Health Sciences. Östergötlands Läns Landsting, Heart and Medicine Center, Department of Gastroentorology.
    Engström, Maria
    Linköping University, Department of Medical and Health Sciences, Radiology. Linköping University, Faculty of Health Sciences.
    Walter, Susanna
    Linköping University, Department of Clinical and Experimental Medicine, Gastroenterology and Hepatology. Linköping University, Faculty of Health Sciences. Östergötlands Läns Landsting, Heart and Medicine Center, Department of Gastroentorology.
    Effect of hypnotherapy and educational intervention on brain response to visceral stimulus in the irritable bowel syndrome2013In: Alimentary Pharmacology and Therapeutics, ISSN 0269-2813, E-ISSN 1365-2036, Vol. 37, no 12, p. 1184-1197Article in journal (Refereed)
    Abstract [en]

    Background Gut-directed hypnotherapy can reduce IBS symptoms, but the mechanisms underlying this therapeutic effect remain unknown. Aim To determine the effect of hypnotherapy and educational intervention on brain responses to cued rectal distensions in IBS patients. Methods Forty-four women with moderate-to-severe IBS and 20 healthy controls (HCs) were included. Blood oxygen level dependent (BOLD) signals were measured by functional Magnetic Resonance Imaging (fMRI) during expectation and delivery of high- (45mmHg) and low-intensity (15mmHg) rectal distensions. Twenty-five patients were assigned to hypnotherapy (HYP) and 16 to educational intervention (EDU). Thirty-one patients completed treatments and posttreatment fMRI. Results Similar symptom reduction was achieved in both groups. Clinically successful treatment (all responders) was associated with significant BOLD attenuation during high-intensity distension in the dorsal and ventral anterior insula (cluster size 142, P=0.006, and cluster size 101, P=0.005 respectively). Moreover HYP responders demonstrated a prepost treatment BOLD attenuation in posterior insula (cluster sizes 59, P=0.05) while EDU responders had a BOLD attenuation in prefrontal cortex (cluster size 60, P=0.05). Prepost differences for expectation conditions were almost exclusively seen in the HYP group. Following treatment, the brain response to distension was similar to that observed in HCs, suggesting that the treatment had a normalising effect on the central processing abnormality of visceral signals in IBS. Conclusions The abnormal processing and enhanced perception of visceral stimuli in IBS can be normalised by psychological interventions. Symptom improvement in the treatment groups may be mediated by different brain mechanisms. Clinical trial number: NCT01815164.

  • 263.
    Lund, Eva
    et al.
    Linköping University, Department of Medical and Health Sciences, Division of Radiological Sciences. Linköping University, Faculty of Health Sciences.
    Adolfsson, Emelie
    Linköping University, Department of Medical and Health Sciences, Division of Radiological Sciences. Linköping University, Faculty of Health Sciences.
    Kolbun, Natallia
    Linköping University, Department of Medical and Health Sciences, Division of Radiological Sciences. Linköping University, Faculty of Health Sciences.
    Gustafsson, Håkan
    Linköping University, Center for Medical Image Science and Visualization (CMIV). Linköping University, Department of Medical and Health Sciences, Division of Radiological Sciences. Linköping University, Faculty of Health Sciences.
    EPR imaging of dose distributions aiming at applications in radiation therapy2014In: Radiation Protection Dosimetry, ISSN 0144-8420, E-ISSN 1742-3406, Vol. 159, no 1-4, p. 130-136Article in journal (Refereed)
    Abstract [en]

    A one-dimensional electron paramagnetic resonance (EPR) imaging method for visualisation of dose distributions in photon fields has been developed. Pressed pellets of potassium dithionate were homogeneously irradiated in a Co-60 radiation field to 600 Gy. The EPR analysis was performed with an X-Band (9.6 GHz) Bruker E540 EPR and EPR imaging spectrometer equipped with an E540 GC2X two-axis X-band gradient coil set with gradients along the y axis (along the sample tube) and z axis (along B-0) and an ER 4108TMHS resonator. Image reconstruction, including deconvolution, baseline corrections and corrections for the resonator sensitivity, was performed using an in-house-developed Matlab code for the purpose to have a transparent and complete algorithm for image reconstruction. With this method, it is possible to visualise a dose distribution with an accuracy of similar to 5 % within +/- 5 mm from the centre of the resonator.

    Download full text (pdf)
    EPR imaging of dose distributions aiming at applications in radiation therapy
  • 264.
    Lundberg, Peter
    Linköping University, Department of Medical and Health Sciences, Division of Radiological Sciences. Linköping University, Faculty of Health Sciences. Linköping University, Center for Medical Image Science and Visualization (CMIV). Region Östergötland, Center for Surgery, Orthopaedics and Cancer Treatment, Department of Radiation Physics.
    Educational NMR software1997In: Journal of Chemical Education, ISSN 0021-9584, E-ISSN 1938-1328, Vol. 74, no 12, p. 1489-1491Article in journal (Refereed)
    Abstract [en]

    A description of a compilation of computer programs (EduNMRSoft) suitable for teaching NMR at an introductory to advanced level is presented. Each program is categorised and described by function, hardware requirements, availability, author, and references in the list. The compilation is available in electronic form at http://www.chem.umu.se/divisions/fk/EduNMRSoft.html.

  • 265.
    Lundberg, Peter
    et al.
    Linköping University, Department of Medical and Health Sciences, Division of Radiological Sciences. Linköping University, Faculty of Health Sciences. Linköping University, Center for Medical Image Science and Visualization (CMIV). Region Östergötland, Center for Surgery, Orthopaedics and Cancer Treatment, Department of Radiation Physics. Department of Biochemistry, University of Sydney, Sydney, New South Wales. 2006, Australia.
    Berners-Price, Susan J.
    Division of Science and Technology, Griffith University, Nathan, Queensland, 4111, Australia.
    Roy, Sushmita
    Department of Biochemistry, University of Sydney, Sydney, New South Wales. 2006, Australia.
    Kuchel, Philip W.
    Department of Biochemistry, University of Sydney, Sydney, New South Wales. 2006, Australia.
    NMR studies of erythrocytes immobilized in agarose and alginate gels1992In: Magnetic Resonance in Medicine, ISSN 0740-3194, E-ISSN 1522-2594, Magn Reson Med, Vol. 25, no 2, p. 273-288Article in journal (Refereed)
    Abstract [en]

    31P and 13C NMR were used to study the energy metabolism in perfused, human erythrocytes. The erythrocytes were immobilized in agarose threads, Ca- or Ba-alginate beads, and Ba-alginate-coated agarose threads. Erythrocytes were easily washed out from the agarose threads, but not from alginate-containing gels. Various small molecules, such as hypophosphite, dimethyl methylphosphonate, and methylphosphonate, were taken up from the perfusion medium in a normal manner. In addition, the 2,3-bisphosphoglycerate (2,3-DPG) chemical shifts were sensitive to the oxygen partial pressure suggesting that O2 molecules were diffusing through the gel and modifying the binding of 2,3-DPG to hemoglobin. A combination of inosine and pyruvate stimulated the synthesis of 2,3-DPG, but only if inorganic phosphate was present in the perfusion medium. Inosine only resulted in a dramatic rise in the intracellular sugarphosphate concentrations. Furthermore, [2-13C]glucose was converted to [2-13C]lactate by immobilized cells at a rate which was comparable to that in a control suspension. In summary, immobilization in Ba-alginate-coated agarose threads was an efficient way of trapping human erythrocytes for whole cell NMR investigations.

  • 266.
    Lundberg, Peter
    et al.
    Linköping University, Department of Medical and Health Sciences, Division of Radiological Sciences. Linköping University, Faculty of Health Sciences. Linköping University, Center for Medical Image Science and Visualization (CMIV). Östergötlands Läns Landsting, Center for Surgery, Orthopaedics and Cancer Treatment, Department of Radiation Physics.
    Chapman, BE
    Kuchel, PW
    Diffusion of metabolities in gels used for cell immobilization1992Conference paper (Other academic)
  • 267.
    Lundberg, Peter
    et al.
    Linköping University, Department of Medical and Health Sciences, Division of Radiological Sciences. Linköping University, Faculty of Health Sciences. Linköping University, Center for Medical Image Science and Visualization (CMIV). Östergötlands Läns Landsting, Center for Surgery, Orthopaedics and Cancer Treatment, Department of Radiation Physics.
    Drakenberg, T
    Vogel, HJ
    Wahlgren, M
    Rudérus, H
    Multinuclear NMR of food1985Conference paper (Other academic)
  • 268.
    Lundberg, Peter
    et al.
    Linköping University, Department of Medical and Health Sciences, Division of Radiological Sciences. Linköping University, Faculty of Health Sciences. Linköping University, Center for Medical Image Science and Visualization (CMIV). Region Östergötland, Center for Surgery, Orthopaedics and Cancer Treatment, Department of Radiation Physics. Department of Biochemistry, University of Sydney, Australia.
    Dudman, Nicholas P.
    Department of Cardiovascular Medicine, Prince Henry Hospital, University of New South Wales, Australia.
    Kuchel, Philip W.
    Department of Biochemistry, University of Sydney, Australia.
    Wilcken, David E. L.
    Present address: Department of Physical Chemistry, University of Umeå, Umeå, Sweden.
    1H NMR determination of urinary betaine in patients with premature vascular disease and mild homocysteinemia1995In: Clinical Chemistry, ISSN 0009-9147, E-ISSN 1530-8561, Vol. 41, no 2, p. 275-283Article in journal (Refereed)
    Abstract [en]

    Urinary N,N,N-trimethylglycine (betaine) and N,N-dimethylglycine (DMG) have been identified and quantified for clinical purposes by proton nuclear magnetic resonance (1H NMR) measurement in previous studies. We have assessed these procedures by using both one-dimensional (1-D) and 2-D NMR spectroscopy, together with pH titration of urinary extracts to help assign 1H NMR spectral peaks. The betaine calibration curve linearity was excellent (r = 0.997, P = 0.0001) over the concentration range 0.2-1.2 mmol/L, and CVs for replicate betaine analyses ranged from 7% (n = 10) at the lowest concentration to 1% (n = 9) at the highest. The detection limit for betaine was < 15 mumol/L. Urinary DMG concentrations were substantially lower than those of betaine. Urinary betaine and DMG concentrations measured by 1H NMR spectroscopy from 13 patients with premature vascular disease and 17 normal controls provided clinically pertinent data. We conclude that 1H NMR provides unique advantages as a research tool for determination of urinary betaine and DMG concentrations.

  • 269.
    Lundberg, Peter
    et al.
    Linköping University, Department of Medical and Health Sciences, Division of Radiological Sciences. Linköping University, Center for Medical Image Science and Visualization (CMIV). Region Östergötland, Center for Surgery, Orthopaedics and Cancer Treatment, Department of Radiation Physics. Linköping University, Faculty of Medicine and Health Sciences.
    Engström, Maria
    Linköping University, Department of Medical and Health Sciences, Division of Radiological Sciences. Linköping University, Center for Medical Image Science and Visualization (CMIV). Linköping University, Faculty of Medicine and Health Sciences.
    van Ettinger-Veenstra, Helene
    Linköping University, Center for Medical Image Science and Visualization (CMIV). Linköping University, Department of Medical and Health Sciences, Division of Radiological Sciences. Linköping University, Faculty of Medicine and Health Sciences.
    Gerdle, Björn
    Linköping University, Department of Medical and Health Sciences, Division of Community Medicine. Linköping University, Faculty of Medicine and Health Sciences. Region Östergötland, Anaesthetics, Operations and Specialty Surgery Center, Pain and Rehabilitation Center.
    Pain disrupts thalamic and nucleus accumbens functional connectivity in chronic widespread pain2016Conference paper (Refereed)
  • 270.
    Lundberg, Peter
    et al.
    Linköping University, Department of Medical and Health Sciences, Division of Radiological Sciences. Linköping University, Center for Medical Image Science and Visualization (CMIV). Linköping University, Faculty of Medicine and Health Sciences. Region Östergötland, Center for Diagnostics, Department of Radiology in Linköping. Region Östergötland, Center for Surgery, Orthopaedics and Cancer Treatment, Department of Radiation Physics.
    Forsgren, Mikael
    Linköping University, Department of Medical and Health Sciences, Division of Radiological Sciences. Linköping University, Faculty of Medicine and Health Sciences. Linköping University, Center for Medical Image Science and Visualization (CMIV). Region Östergötland, Center for Surgery, Orthopaedics and Cancer Treatment, Department of Radiation Physics.
    Nasr, Patrik
    Linköping University, Department of Medical and Health Sciences. Linköping University, Faculty of Medicine and Health Sciences. Region Östergötland, Heart and Medicine Center, Department of Gastroentorology.
    Ignatova, Simone
    Linköping University, Department of Clinical and Experimental Medicine, Division of Cell Biology. Linköping University, Faculty of Medicine and Health Sciences.
    Leinhard Dahlqvist, Olof
    Linköping University, Department of Medical and Health Sciences, Division of Radiological Sciences. Linköping University, Center for Medical Image Science and Visualization (CMIV). Linköping University, Faculty of Medicine and Health Sciences. Region Östergötland, Center for Surgery, Orthopaedics and Cancer Treatment, Department of Radiation Physics.
    Dahlström, Nils
    Linköping University, Department of Medical and Health Sciences, Division of Radiological Sciences. Linköping University, Center for Medical Image Science and Visualization (CMIV). Linköping University, Faculty of Medicine and Health Sciences. Region Östergötland, Center for Diagnostics, Department of Radiology in Linköping.
    Ekstedt, Mattias
    Linköping University, Department of Medical and Health Sciences, Division of Cardiovascular Medicine. Linköping University, Faculty of Medicine and Health Sciences. Region Östergötland, Heart and Medicine Center, Department of Gastroentorology.
    Kechagias, Stergios
    Linköping University, Department of Medical and Health Sciences, Division of Cardiovascular Medicine. Linköping University, Faculty of Medicine and Health Sciences. Region Östergötland, Heart and Medicine Center, Department of Gastroentorology.
    Kvantifiering av leversteatos: diagnostisk utvärdering av protonmagnetresonansspektroskopi jämfört med histologiska metoder2016Conference paper (Refereed)
    Abstract [sv]

    Bakgrund

    Leversteatos är den vanligaste manifestationen av leversjukdom i västvärlden. Leverbiopsi med semikvantitativ histologisk gradering är referensmetod vid gradering av leversteatos. Med protonmagnetsresonansspektroskopi (1H-MRS), en metod som föreslagits ersätta leverbiopsi för värdering av steatos, kan leverns innehåll av triglycerider mätas icke-invasivt. Triglyceridinnehåll >5,00 % används ofta som ett diagnostiskt kriterium för leversteatos vid undersökning med 1H-MRS. Syftet med studien var att jämföra 1H-MRS med semikvantitativ histologisk steatosgradering och kvantitativ histologisk steatosmätning.

    Metod

    Patienter remitterade för utredning av förhöjda leverenzymer in-kluderades i studien. Samtliga patienter genomgick klinisk undersökning, laboratorieprovtagning samt 1H-MRS direkt följd av leverbiopsi. För konventionell histologisk semikvantitativ gradering av steatos användes kriterierna utarbetade av Brunt och medarbetare. Kvantitativ mätning av fett i biopsierna utfördes genom att med hjälp av stereologisk punkträkning (SPC) mäta andelen av ytan som innehöll fettvakuoler.

    Resultat

    I studien inkluderades 94 patienter, varav 37 hade icke-alkoholor-sakad fettleversjukdom (NAFLD), 49 hade andra leversjukdomar och 8 hade normal leverbiopsi. En stark korrelation noterades mel-lan 1H-MRS och SPC (r=0,92, p<0,0001; к=0.82). Korrelationen mellan 1H-MRS och Brunts kriterier (к=0.26) samt mellan SPC och Brunts kriterier (к=0.38) var betydligt sämre. När patologens gradering (Brunts kriterier) användes som referensmetod för diag-nos av leversteatos så hade alla patienter med triglyceridinnehåll >5,00 % mätt med 1H-MRS steatos (specificitet 100 %). Emellertid hade 22 av 69 patienter med triglyceridinnehåll ≤5,00 % också le-versteatos enligt Brunts kriterier (sensitivitet 53 %). Motsvarande siffror när man använde gränsvärdet 3,02 % var sensitivitet 79 % och specificitet 100 %. Vid ytterligare reduktion av gränsvärdet för triglyceridinnehåll till 2,00 % ökade sensitiviteten till 87 % med upprätthållande av hög specificitet (94 %).

    Slutsats

    1H-MRS och SPC uppvisade en mycket hög korrelation vid kvantifiering av leversteatos. SPC borde därför föredras framför Brunts kriterier när noggrann histologisk kvantifiering av leversteatos är önskvärd. Många patienter kan ha histologisk leversteatos trots triglyceridinnehåll ≤5,00 % mätt med 1H-MRS. Gränsvärdet för diagnostisering av leversteatos med 1H-MRS bör därför reduceras.

  • 271.
    Lundberg, Peter
    et al.
    Linköping University, Department of Medical and Health Sciences, Division of Radiological Sciences. Linköping University, Faculty of Health Sciences. Linköping University, Center for Medical Image Science and Visualization (CMIV). Östergötlands Läns Landsting, Center for Surgery, Orthopaedics and Cancer Treatment, Department of Radiation Physics.
    Friman, Ola
    Linköping University, Department of Biomedical Engineering, Medical Informatics. Linköping University, The Institute of Technology.
    Carlsson, J
    Borga, M
    Söderfeldt, B
    Knutsson, H
    Detection of neural activity in functional MRI using canonical correlation analysis.2001Conference paper (Other academic)
    Abstract [en]

    A novel method for detecting neural activity in functional magnetic resonance imaging (fMRI) data is introduced. It is based on canonical correlation analysis (CCA), which is a multivariate extension of the univariate correlation analysis widely used in fMRI. To detect homogeneous regions of activity, the method combines a subspace modeling of the hemodynamic response and the use of spatial relationships. The spatial correlation that undoubtedly exists in fMR images is completely ignored when univariate methods such as as t-tests, F-tests, and ordinary correlation analysis are used. Such methods are for this reason very sensitive to noise, leading to difficulties in detecting activation and significant contributions of false activations. In addition, the proposed CCA method also makes it possible to detect activated brain regions based not only on thresholding a correlation coefficient, but also on physiological parameters such as temporal shape and delay of the hemodynamic response. Excellent performance on real fMRI data is demonstrated. Magn Reson Med 45:323-330, 2001

  • 272.
    Lundberg, Peter
    et al.
    Linköping University, Department of Medical and Health Sciences, Division of Radiological Sciences. Linköping University, Faculty of Health Sciences. Linköping University, Center for Medical Image Science and Visualization (CMIV). Region Östergötland, Center for Surgery, Orthopaedics and Cancer Treatment, Department of Radiation Physics. Department of Biological Sciences, University of Calgary, Calgary, Alberta, Canada.
    Harmsen, Eef
    Department of Biological Sciences, University of Calgary, Calgary, Alberta, Canada.
    Ho, Clinton
    Department of Biological Sciences, University of Calgary, Calgary, Alberta, Canada.
    Vogel, Hans J.
    Department of Biological Sciences, University of Calgary, Calgary, Alberta, Canada.
    Nuclear magnetic resonance studies of cellular metabolism1990In: Analytical Biochemistry, ISSN 0003-2697, E-ISSN 1096-0309, Vol. 191, no 2, p. 193-222Article in journal (Refereed)
    Abstract [en]

    Nuclear magnetic resonance (NMR) spectroscopy was described in 1946 (1,2), initially as a method that had appeal only for nuclear physicists who used it to accurately determine nuclear magnetic moments. Thissituation changed rapidly, however, when it was demonstrated that the NMR frequency for the same nucleus in different chemical compounds was different (3). For example, two separate signals are observed in a 14N NMR spectrum of a solution of NH,NO,, representing the NH: and NO; ions, respectively (4). Since individual atoms within one molecule also give rise to resolved signals (5) it became clear that the NMR technique held great analytical potential, in particular since the spectra can be recorded in such a way that the area under a signal is directly proportional to its concentration. Such phenomena and various theoretical aspects of NMR are currently quite well understood (6,7). Because of these features NMR has become the foremost spectroscopic method for the analysis of all sorts of chemical compounds.

  • 273.
    Lundberg, Peter
    et al.
    Linköping University, Department of Medical and Health Sciences, Division of Radiological Sciences. Linköping University, Center for Medical Image Science and Visualization (CMIV). Region Östergötland, Center for Surgery, Orthopaedics and Cancer Treatment, Department of Radiation Physics. Linköping University, Faculty of Medicine and Health Sciences.
    Icenhour, Adriane
    Bednarska, O.
    Tapper, Sofie
    Linköping University, Department of Medical and Health Sciences, Division of Radiological Sciences. Linköping University, Faculty of Medicine and Health Sciences.
    Witt, ST
    Elsenbruch, S
    Walter, Susanna
    Linköping University, Department of Clinical and Experimental Medicine, Division of Neuro and Inflammation Science. Linköping University, Center for Medical Image Science and Visualization (CMIV). Linköping University, Faculty of Medicine and Health Sciences. Region Östergötland, Heart and Medicine Center, Department of Gastroentorology.
    Increased inhibitory neurotransmission within anterior cingulate cortex is related to comorbid anxiety in irritable bowel syndrome.2016Conference paper (Other academic)
  • 274.
    Lundberg, Peter
    et al.
    Linköping University, Department of Medical and Health Sciences, Division of Radiological Sciences. Linköping University, Center for Medical Image Science and Visualization (CMIV). Linköping University, Faculty of Medicine and Health Sciences. Region Östergötland, Center for Surgery, Orthopaedics and Cancer Treatment, Department of Radiation Physics.
    Karlsson, Markus
    Linköping University, Department of Medical and Health Sciences, Division of Radiological Sciences. Linköping University, Center for Medical Image Science and Visualization (CMIV). Linköping University, Faculty of Medicine and Health Sciences.
    Forsgren, Mikael
    Linköping University, Department of Medical and Health Sciences, Division of Radiological Sciences. Linköping University, Faculty of Medicine and Health Sciences. Linköping University, Center for Medical Image Science and Visualization (CMIV). Region Östergötland, Center for Surgery, Orthopaedics and Cancer Treatment, Department of Radiation Physics.
    Dahlström, Nils
    Linköping University, Department of Medical and Health Sciences, Division of Radiological Sciences. Linköping University, Center for Medical Image Science and Visualization (CMIV). Linköping University, Faculty of Medicine and Health Sciences. Region Östergötland, Center for Diagnostics, Department of Radiology in Linköping.
    Leinhard Dahlqvist, Olof
    Linköping University, Department of Medical and Health Sciences, Division of Radiological Sciences. Linköping University, Center for Medical Image Science and Visualization (CMIV). Linköping University, Faculty of Medicine and Health Sciences. Region Östergötland, Center for Surgery, Orthopaedics and Cancer Treatment, Department of Radiation Physics.
    Norén, Bengt
    Linköping University, Department of Medical and Health Sciences, Division of Radiological Sciences. Linköping University, Faculty of Medicine and Health Sciences. Region Östergötland, Center for Diagnostics, Department of Radiology in Linköping.
    Cedersund, Gunnar
    Linköping University, Department of Biomedical Engineering. Linköping University, Faculty of Science & Engineering.
    Ekstedt, Mattias
    Linköping University, Department of Medical and Health Sciences, Division of Cardiovascular Medicine. Linköping University, Faculty of Medicine and Health Sciences. Region Östergötland, Heart and Medicine Center, Department of Gastroentorology.
    Kechagias, Stergios
    Linköping University, Department of Medical and Health Sciences, Division of Cardiovascular Medicine. Linköping University, Faculty of Medicine and Health Sciences. Region Östergötland, Heart and Medicine Center, Department of Gastroentorology.
    Mechanistic modeling of qDCE-MRI data reveals increased bile excretion of Gd-EOB-DTPA in diffuse liver disease patients with severe fibrosis2016Conference paper (Refereed)
    Abstract [en]

    Introduction

    Over the past decades, several different non-invasive methods for staging hepatic fibrosis have been proposed. One such method is dynamic contrast enhanced MRI (DCE-MRI) using the contrast agent (CA) Gd-EOB-DTPA. Gd-EOB-DTPA is liver specific, which means that it is taken up specifically by the hepatocytes via the OATP3B1/B3 transporters and excreted into the bile via the MRP2 transporter. Several studies have shown that DCE-MRI and Gd-EOBDTPA can separate patients with advanced (F3-F4) from mild (F0-F2) hepatic fibrosis by measuring the signal intensity, where patients with advanced fibrosis have a lower signal intensity than the mild fibrosis cases.1 However, none of the studies up to date have been able to differentiate if the reduced signal intensity in the liver is because of an decreased uptake of CA or an increased excretion. Analyzing the DCE-MRI data with mechanistic mathematical modelling has the possibility of investigating such a differentiation.

    Subjects and methods

    88 patients with diffuse liver disease were examined using DCE-MRI (1.5 T Philips Achieva, two-point Dixon, TR=6.5 ms, TE=2.3/4.6 ms, FA=13) after a bolus injection of Gd-EOB-DTPA, followed by a liver biopsy. Regions of interest were placed within the liver, spleen and veins and a whole-body mechanistic pharmacokinetic model2 was fitted to the data. The fitted parameters in the model correspond to the rate of CA transport between different compartments, e.g. hepatocytes, blood plasma, and bile (Fig. 1).

    Results

    As can be seen in Fig. 2, the parameter corresponding to the transport of CA from the blood plasma to the hepatocytes, kph, is lower for patients with advanced fibrosis (p=0.01). Fig. 3 shows that the parameter corresponding to the CA excretion into the bile, khb, is higher for patients with advanced fibrosis (p<0.01).

    Discussion/Conclusion

    This work shows that the decreased signal intensity in DCE-MRI images in patients with advanced fibrosis depends on both a decreased uptake of CA in the hepatocytes and an increased excretion into the bile. Similar results have also been observed in a rat study3. In that study, rats with induced cirrhosis had a higher MRP2-activity than the healthy control rats.

    References

    1Norén et al: Eur. Radiol, 23(1), 174-181, 2013.

    2Forsgren et al: PloS One, 9(4): e95700, 2014.

    3Tsuda & Matsui: Radiol, 256(3): 767-773, 2010.

  • 275.
    Lundberg, Peter
    et al.
    Linköping University, Department of Medical and Health Sciences, Division of Radiological Sciences. Linköping University, Faculty of Health Sciences. Linköping University, Center for Medical Image Science and Visualization (CMIV). Region Östergötland, Center for Surgery, Orthopaedics and Cancer Treatment, Department of Radiation Physics. Department of Physical Chemistry, University of Umeå, Umeå, Sweden / Department of Biochemistry, University of Sydney, Australia .
    Kuchel, Philip W.
    Department of Physical Chemistry, University of Umeå, Umeå, Sweden / Department of Biochemistry, University of Sydney, Australia.
    Diffusion of solutes in agarose and alginate gels: 1H and 23Na PFGSE and 23Na TQF NMR studies1997In: Magnetic Resonance in Medicine, ISSN 0740-3194, E-ISSN 1522-2594, Vol. 37, no 1, p. 44-52Article in journal (Refereed)
    Abstract [en]

    Cells immobilized in gels experience potential metabolic restrictions in the form of reduced diffusion rates of metabolites and ions and their possible selective adsorption on the gel matrix. Diffusion and relaxation characteristics of common solutes in agarose and barium alginate gels were investigated at 37 degrees C by using 1H PFGSE and 23Na TQF NMR spectroscopy. Glucose, glycine, alanine, lactate, sodium ions, and HDO were studied. There were no selective interactions between any of the metabolites and the gel materials but the diffusion coefficients were uniformly reduced. The effects of metabolite diffusion and utilization, in gel beads and threads containing cells, were simulated by using a reaction diffusion model incorporating the measured diffusion coefficients. Metabolism is expected to be very significantly limited by diffusion of solutes to and from the cells that are centrally located within gel threads or spheres of radius approximately 2.0 mm, which is a commonly used size.

  • 276.
    Lundberg, Peter
    et al.
    Linköping University, Department of Medical and Health Sciences, Division of Radiological Sciences. Linköping University, Faculty of Health Sciences. Linköping University, Center for Medical Image Science and Visualization (CMIV). Östergötlands Läns Landsting, Center for Surgery, Orthopaedics and Cancer Treatment, Department of Radiation Physics.
    Kuchel, PW
    Determination of betaine in urine by 1H NMR1992Conference paper (Other academic)
  • 277.
    Lundberg, Peter
    et al.
    Linköping University, Department of Medical and Health Sciences, Division of Radiological Sciences. Linköping University, Faculty of Health Sciences. Linköping University, Center for Medical Image Science and Visualization (CMIV). Östergötlands Läns Landsting, Center for Surgery, Orthopaedics and Cancer Treatment, Department of Radiation Physics. Department of Physical Chemistry, University of Lund, Chemical Center, Lund, Sweden .
    Linsefors, L.
    Pure and Applied Biochemistry, University of Lund, Chemical Center, Lund, Sweden.
    Vogel, H. J.
    Department of Physical Chemistry, University of Lund, Chemical Center, Lund, Sweden.
    Brodelius, P.
    Institute of Biotechnology, Swiss Federal Institute of Technology, Hönggerberg, Zürich, Switzerland .
    Permeabilization of plant cells: 31P NMR studies on the permeability of the tonoplast1986In: Plant Cell Reports, ISSN 0721-7714, E-ISSN 1432-203X, Vol. 5, no 1, p. 13-16Article in journal (Refereed)
    Abstract [en]

    A suspension culture of Catharanthus roseus has been used to study the permeability of cell membranes after treatment with various concentrations of a permeabilizing agent (DMSO). The uptake and release (after permeabilization) of inorganic phosphate (Pi) by cells have been investigated by 32P radiotracer and non-invasive phosphorus-31 NMR experiments. These studies have demonstrated that measurements of the Pi-efflux from plant cells provide a reliable measure of the permeability of the tonoplast.

  • 278.
    Lundberg, Peter
    et al.
    Linköping University, Department of Medical and Health Sciences, Division of Radiological Sciences. Linköping University, Faculty of Health Sciences. Linköping University, Center for Medical Image Science and Visualization (CMIV). Östergötlands Läns Landsting, Center for Surgery, Orthopaedics and Cancer Treatment, Department of Radiation Physics.
    Lundquist, P-O
    Huss-Danell, K
    NMR methods for studying metabolities in an N-fixing root nodule symbiosis1995Conference paper (Other academic)
  • 279.
    Lundberg, Peter
    et al.
    Linköping University, Department of Medical and Health Sciences, Division of Radiological Sciences. Linköping University, Faculty of Health Sciences. Linköping University, Center for Medical Image Science and Visualization (CMIV). Östergötlands Läns Landsting, Center for Surgery, Orthopaedics and Cancer Treatment, Department of Radiation Physics.
    Roy, S
    Kuchel, PW
    Immobilization and in vivo NMR studies of the intracellular metabolism in erythrocytes and T-lymphocytes1992Conference paper (Other academic)
  • 280.
    Lundberg, Peter
    et al.
    Linköping University, Department of Medical and Health Sciences, Division of Radiological Sciences. Linköping University, Faculty of Health Sciences. Linköping University, Center for Medical Image Science and Visualization (CMIV). Östergötlands Läns Landsting, Center for Surgery, Orthopaedics and Cancer Treatment, Department of Radiation Physics. Umeå University, Umeå, Sweden.
    Roy, S
    Kuchel, PW
    In situ NMR studies of perfused erythrocytes and thymocytes1995Conference paper (Other academic)
  • 281.
    Lundberg, Peter
    et al.
    Linköping University, Department of Medical and Health Sciences, Division of Radiological Sciences. Linköping University, Faculty of Health Sciences. Linköping University, Center for Medical Image Science and Visualization (CMIV). Region Östergötland, Center for Surgery, Orthopaedics and Cancer Treatment, Department of Radiation Physics. Department of Biochemistry, University of Sydney, Australia..
    Roy, Sushmita
    Department of Biochemistry, University of Sydney, Australia..
    Kuchel, Philip W.
    Department of Biochemistry, University of Sydney, Australia..
    Fructose 3-phosphate and 5-phosphoribosyl-1-pyrophosphate formation in perfused human erythrocytes: 31P NMR studies1994In: Magnetic Resonance in Medicine, ISSN 0740-3194, E-ISSN 1522-2594, Vol. 31, no 2, p. 110-121Article in journal (Refereed)
    Abstract [en]

    31P NMR was used to study the formation of fructose 3-phos-phate (F3P) and 5-phosphoribosyl-1-pyrophosphate (PRPP) in perfused human erythrocytes, in the presence of 10 different combinations and concentrations of glucose, inosine, pyru-vate, fructose, and inorganic phosphate (Pi). (1) The cells were immobilized in alginate-coated agarose threads and perfused with a medium containing fructose, and the level of F3P increased continuously over more than 10 h. The net rate of F3P formation was independent of the concentration of 2,3-bis-phosphoglycerate (2,3-DPG) present in the cells. (2) PRPP was formed in high concentrations, relative to normal, in immobilized cells when they were perfused with a medium containing Pi at a low pH (6.6). (3) The 2,3-DPG level decreased simultaneously when the sample was perfused with a medium containing fructose, but without inosine or pyruvate. The measured intracellular pH and free Mg2+ concentration were constant in these experiments. (4) The experiments confirmed the presence of fructose-3-phosphokinase (E.C. 2.7.1.-) and ribose-phosphate pyrophosphokinase (E.C. 2.7.6.1) activity in the human erythrocytes and that the biosynthetic pathways are active in immobilized cells at 37°C. (5) The rates of accumulation of 2,3-DPG and phosphomonoesters (PME) appeared to be strongly correlated.

  • 282.
    Lundberg, Peter
    et al.
    Linköping University, Department of Medical and Health Sciences, Division of Radiological Sciences. Linköping University, Faculty of Health Sciences. Linköping University, Center for Medical Image Science and Visualization (CMIV). Östergötlands Läns Landsting, Center for Surgery, Orthopaedics and Cancer Treatment, Department of Radiation Physics.
    Stephenson, J
    Thorpe, TA
    Vogel, HJ
    Nitrogen NMR studies (15N and 14N) of Picea glauca (white spruce).1988Conference paper (Other academic)
  • 283.
    Lundberg, Peter
    et al.
    Linköping University, Department of Medical and Health Sciences, Division of Radiological Sciences. Linköping University, Center for Medical Image Science and Visualization (CMIV). Region Östergötland, Center for Surgery, Orthopaedics and Cancer Treatment, Department of Radiation Physics. Linköping University, Faculty of Medicine and Health Sciences.
    Tisell, Anders
    Linköping University, Department of Medical and Health Sciences, Division of Radiological Sciences. Linköping University, Center for Medical Image Science and Visualization (CMIV). Region Östergötland, Center for Surgery, Orthopaedics and Cancer Treatment, Department of Radiation Physics. Linköping University, Faculty of Medicine and Health Sciences.
    Quantification of metabolite relaxation rates using STEAM2016Conference paper (Refereed)
  • 284.
    Lundberg, Peter
    et al.
    Linköping University, Department of Medical and Health Sciences, Division of Radiological Sciences. Linköping University, Center for Medical Image Science and Visualization (CMIV). Region Östergötland, Center for Surgery, Orthopaedics and Cancer Treatment, Department of Radiation Physics. Linköping University, Faculty of Medicine and Health Sciences.
    Tisell, Anders
    Linköping University, Department of Medical and Health Sciences, Division of Radiological Sciences. Linköping University, Center for Medical Image Science and Visualization (CMIV). Linköping University, Faculty of Medicine and Health Sciences. Region Östergötland, Center for Surgery, Orthopaedics and Cancer Treatment, Department of Radiation Physics.
    Subject movements in MRS: Evaluating the reliability in GABA concentrations determined at 3 T.2016Conference paper (Refereed)
  • 285.
    Lundberg, Peter
    et al.
    Linköping University, Department of Medical and Health Sciences, Division of Radiological Sciences. Linköping University, Center for Medical Image Science and Visualization (CMIV). Region Östergötland, Center for Surgery, Orthopaedics and Cancer Treatment, Department of Radiation Physics. Linköping University, Faculty of Medicine and Health Sciences.
    Tisell, Anders
    Linköping University, Department of Medical and Health Sciences, Division of Radiological Sciences. Linköping University, Center for Medical Image Science and Visualization (CMIV). Region Östergötland, Center for Surgery, Orthopaedics and Cancer Treatment, Department of Radiation Physics. Linköping University, Faculty of Medicine and Health Sciences.
    Cedersund, Gunnar
    Linköping University, Department of Biomedical Engineering. Linköping University, Faculty of Science & Engineering.
    Shimekaw, Sara
    Robust Quantification of Myelin Water Volume and Water Exchange2016Conference paper (Refereed)
  • 286.
    Lundberg, Peter
    et al.
    Linköping University, Department of Medical and Health Sciences, Division of Radiological Sciences. Linköping University, Center for Medical Image Science and Visualization (CMIV). Region Östergötland, Center for Surgery, Orthopaedics and Cancer Treatment, Department of Radiation Physics. Linköping University, Faculty of Medicine and Health Sciences.
    Tisell, Anders
    Linköping University, Department of Medical and Health Sciences, Division of Radiological Sciences. Linköping University, Center for Medical Image Science and Visualization (CMIV). Region Östergötland, Center for Surgery, Orthopaedics and Cancer Treatment, Department of Radiation Physics. Linköping University, Faculty of Medicine and Health Sciences.
    Tapper, Sofie
    Linköping University, Department of Medical and Health Sciences, Division of Radiological Sciences. Linköping University, Faculty of Medicine and Health Sciences.
    Absolute Quantification of Metabolite Concentrations and Relaxation Rates.2016Conference paper (Refereed)
  • 287.
    Lundberg, Peter
    et al.
    Linköping University, Department of Medical and Health Sciences, Division of Radiological Sciences. Linköping University, Faculty of Health Sciences. Linköping University, Center for Medical Image Science and Visualization (CMIV). Östergötlands Läns Landsting, Center for Surgery, Orthopaedics and Cancer Treatment, Department of Radiation Physics. Division of Biochemistry, University of Calgary, Calgary, Canada.
    Vogel, H. J.
    Division of Biochemistry, University of Calgary, Calgary, Canada.
    NMR as a Noninvasive Tool in Meat Research1987In: Annals of the New York Academy of Sciences, ISSN 0077-8923, E-ISSN 1749-6632, Vol. 508, p. 516-522Article in journal (Refereed)
    Abstract [en]

    NMR has been used for some time for in vivo measurements of biological tissues and has established itself as a valuable and complementary method to be used in parallel with traditional extraction methods. To date most attention has been paid to problems such as central biochemical pathways, energy metabolism in simple organisms and organs, and of course to problems encountered in medicine. There has been relative little interest in applying NMR to problems in food technology, even if these questions can have a tremendous impact on everyday life. Following a suggestion by Gadian,' we show here that multinuclear metabolic NMR is a useful method for studying post-mortem events in carcasses of slaughtered animals.

    The treatment and storage of carcasses during the first hours after slaughter is of extreme importance for the final quality and tenderness of the meat. Mistreatment can cause large economical losses and waste of valuable food. For example, in order to reduce the risk of bacterial infections one would like to cool down a carcass as soon as possible. Nevertheless, if a muscle is cooled down below 15OC before the postmortem metabolism is completed it may shorten dramatically thus decreasing the tenderness of the meat.' Therefore it is important to measure the rates of postmortem metabolism and to study the efficiency of methods that are aimed at speeding up this process.

  • 288.
    Lundberg, Peter
    et al.
    Linköping University, Department of Medical and Health Sciences, Division of Radiological Sciences. Linköping University, Faculty of Health Sciences. Linköping University, Center for Medical Image Science and Visualization (CMIV). Östergötlands Läns Landsting, Center for Surgery, Orthopaedics and Cancer Treatment, Department of Radiation Physics. Division of Biochemistry, Department of Chemistry, University of Calgary, Calgary, Alberta, Canada.
    Vogel, Hans J.
    Division of Biochemistry, Department of Chemistry, University of Calgary, Calgary, Alberta, Canada.
    Carbon-13 and proton NMR studies of post-mortem metabolism in bovine muscles1986In: Meat Science, ISSN 0309-1740, E-ISSN 1873-4138, Vol. 18, no 2, p. 133-160Article in journal (Refereed)
    Abstract [en]

    Proton and carbon-13 NMR was used to investigate post-mortem metabolism in bovine muscles at 26°C during the first 10h after slaughter. WALTZ-16 decoupling was used to eliminate the proton couplings in the (13)C spectra and the 'jump and return' pulse sequence was used to suppress the water resonance in the (1)H-NMR experiments. With carbon-13 NMR the glycogen breakdown and the lactate development could be followed. This was compared with the lactate, creatine and phosphocreatine development as measured by proton NMR. The intracellular pH was estimated from the chemical shift of the abundant dipeptide, carnosine, as measured in the (1)H- and (13)C-NMR spectra. These were compared with similar measurements obtained earlier using phosphorus-31 NMR. The three independently determined pH profiles were in excellent agreement with one another, as well as with results obtained with the standard iodoacetate extraction method. In the course of these studies we observed that the post-mortem metabolism in cow and heifer was slow and that it took four more hours to complete compared to bull or young bull. After 10 h the pH was 5·9 in bull and 6·1 in cow. Phosphocreatine had completely disappeared after 3·5 h in bull samples while the lactate continued to increase even after 10h. The curves obtained by carbon-13 and proton NMR for the increase in lactate during the first 10 h post mortem were very similar. Moreover, plots for the increase in the lactate level versus the intracellular pH decrease showed a linear relationship, indicating that anaerobic glycolytic activity is the main determining cause for the intracellular pH decrease. Various other parameters, such as the ratio of unsatirated to saturated fatty acid side chains and the presence of amino acids and taurine, could be measured from the in vivo carbon-13 NMR spectra. However, no gross changes occured in any of these parameters during the first 10 h post mortem.

  • 289.
    Lundberg, Peter
    et al.
    Linköping University, Department of Medical and Health Sciences, Division of Radiological Sciences. Linköping University, Faculty of Health Sciences. Linköping University, Center for Medical Image Science and Visualization (CMIV). Region Östergötland, Center for Surgery, Orthopaedics and Cancer Treatment, Department of Radiation Physics. Department of Physical Chemistry 2, University of Lund, 221 000 Lund, Sweden.
    Vogel, Hans J.
    Department of Physical Chemistry 2, University of Lund, 221 000 Lund, Sweden.
    Post-mortem metabolism in fresh porcine, ovine and frozen bovine muscle1987In: Meat Science, ISSN 0309-1740, E-ISSN 1873-4138, Vol. 19, no 1, p. 1-14Article in journal (Refereed)
    Abstract [en]

    Post-mortem metabolism was followed by phosphorus-31-NMR in muscle samples obtained from freshly slaughtered pigs and lambs. Resonances for creatine phosphate (CP), ATP, inorganic phosphate (Pi) and sugar phosphates (SP) could be discerned and the intracellular pH could be determined from the spectra. The rates of post-mortem metabolism varied in the following fashion: porcine muscle > ovine muscle > bovine muscle. However, the course of post-mortem metabolism was, in all cases, the same. CP disappeared first and then ATP. Simultaneously, Pi increased, while SP remained relatively constant. The intracellular pH decreased to pH 5·5 in all tissues.

    In a separate set of experiments the post-mortem metabolism during thawing was studied in bovine muscles that had been frozen immediately after slaughter. Again, the same course of post-mortem metabolism was observed, but the thaw shortening was accompanied by an extremely rapid post-mortem metabolism, which was more than ten times as fast as that measured for fresh bovine muscles. The intracellular pH decreased from 7·2 to 5·5 in 45 min. This rapid metabolism started only after the sample ha reached 0°C. Resonances for metabolites were broadened in frozen muscles due to the limited motions that are allowed within the ice lattice.

  • 290.
    Lundberg, Peter
    et al.
    Linköping University, Department of Medical and Health Sciences, Division of Radiological Sciences. Linköping University, Faculty of Health Sciences. Linköping University, Center for Medical Image Science and Visualization (CMIV). Region Östergötland, Center for Surgery, Orthopaedics and Cancer Treatment, Department of Radiation Physics. Department of Biological Sciences, University of Calgary, Calgary, Alberta, Canada.
    Vogel, Hans J.
    Department of Biological Sciences, University of Calgary, Calgary, Alberta, Canada.
    Brodelius, Peter E.
    Department of Plant Biochemistry, Lund University, Lund, Sweden.
    A phosphorus-31 nuclear magnetic resonance study of elicitor-mediated metabolic changes in Catharanthus roseus suspension cultures1997In: In vitro cellular & developmental biology. Plant, ISSN 1054-5476, E-ISSN 1475-2689, Vol. 33, no 4, p. 301-305Article in journal (Refereed)
    Abstract [en]

    The induction of metabolic changes in suspension cultured cells of Catharanthus roseus upon elicitation has been investigated. Addition of a yeast glucan preparation to the growth medium resulted in induction of phenylalanine ammonia lyase. Phosphate uptake and metabolism of elicited cells was followed by 31P nuclear magnetic resonance. The uptake rate of Pi from the medium by oxygenated cells of C. roseus was reduced immediately after elicitation. Despite this reduced Pi uptake elicited cells had significantly increased amounts of ATP (twofold increase within 6 h). Cytoplasmic levels of Pi, phosphomonoesters, and Uridine Diphasphate glucose (UDP-Glc) were unaffected by eliciation. Furthermore, the cytoplasmic and vacuolar pH remained constant after addition of elicitor.

  • 291.
    Lundberg, Peter
    et al.
    Linköping University, Department of Medical and Health Sciences, Division of Radiological Sciences. Linköping University, Faculty of Health Sciences. Linköping University, Center for Medical Image Science and Visualization (CMIV). Region Östergötland, Center for Surgery, Orthopaedics and Cancer Treatment, Department of Radiation Physics. Department of Biological Sciences, University of Calgary, Calgary Canada.
    Vogel, Hans J.
    Department of Biological Sciences, University of Calgary, Calgary Canada.
    Drakenberg, Torbjörn
    Department of Physical Chemistry 2, University of Lund, Lund Sweden.
    Forsén, Sture
    Department of Physical Chemistry 2, University of Lund, Lund Sweden.
    Amiconi, Gino
    CNR Center of Molecular Biology and Department of Biochemical Sciences, Rome Italy.
    Forlani, Luciano
    Department of Experimental Medicine, University ‘La Sapienza’, Rome Italy.
    Chiancone, Emilia
    CNR Center of Molecular Biology and Department of Biochemical Sciences, Rome Italy.
    A35Cl--NMR study of the singular anion-binding properties of dromedary hemoglobin1989In: Biochimica et Biophysica Acta, ISSN 0006-3002, E-ISSN 1878-2434, Vol. 999, no 1, p. 12-8Article in journal (Refereed)
    Abstract [en]

    35Cl(-)-NMR measurements of chloride binding to carbonmonoxy- and deoxy-dromedary hemoglobin reveal the existence of two classes of chloride-binding sites, one of high and the other of low affinity. Although this situation resembles that described for human hemoglobin, it was found that the number of binding sites as well as the association equilibrium constant for chloride binding are significantly higher in the dromedary protein. This difference may be due to the greater number of basic residues exposed to solvent and to the higher flexibility of dromedary hemoglobin. The two oxygen-linked polyanion-binding sites characteristic of this hemoglobin show competition for some of the high-affinity chloride-binding sites in keeping with their location in the cleft enclosed by the beta chains and between the alpha chains termini. It is suggested that the observed anion-binding properties of dromedary hemoglobin may contribute to the control of the physiological osmotic shock after rehydration.

  • 292.
    Lundberg, Peter
    et al.
    Linköping University, Department of Medical and Health Sciences, Division of Radiological Sciences. Linköping University, Faculty of Health Sciences. Linköping University, Center for Medical Image Science and Visualization (CMIV). Östergötlands Läns Landsting, Center for Surgery, Orthopaedics and Cancer Treatment, Department of Radiation Physics.
    Vogel, HJ
    Multinuclear NMR studies of cultured plant cells1987Conference paper (Other academic)
  • 293.
    Lundberg, Peter
    et al.
    Linköping University, Department of Medical and Health Sciences, Division of Radiological Sciences. Linköping University, Faculty of Health Sciences. Linköping University, Center for Medical Image Science and Visualization (CMIV). Östergötlands Läns Landsting, Center for Surgery, Orthopaedics and Cancer Treatment, Department of Radiation Physics.
    Vogel, HJ
    Multinuclear NMR studies of plants1987Conference paper (Other academic)
  • 294.
    Lundberg, Peter
    et al.
    Linköping University, Department of Medical and Health Sciences, Division of Radiological Sciences. Linköping University, Faculty of Health Sciences. Linköping University, Center for Medical Image Science and Visualization (CMIV). Östergötlands Läns Landsting, Center for Surgery, Orthopaedics and Cancer Treatment, Department of Radiation Physics.
    Vogel, HJ
    Multinuclear studies of various muscles1986Conference paper (Other academic)
  • 295.
    Lundberg, Peter
    et al.
    Linköping University, Department of Medical and Health Sciences, Division of Radiological Sciences. Linköping University, Faculty of Health Sciences. Linköping University, Center for Medical Image Science and Visualization (CMIV). Östergötlands Läns Landsting, Center for Surgery, Orthopaedics and Cancer Treatment, Department of Radiation Physics.
    Vogel, HJ
    NMR studies of monovalent ions in cultured plant cells1990Conference paper (Other academic)
  • 296.
    Lundberg, Peter
    et al.
    Linköping University, Department of Medical and Health Sciences, Division of Radiological Sciences. Linköping University, Faculty of Health Sciences. Linköping University, Center for Medical Image Science and Visualization (CMIV). Östergötlands Läns Landsting, Center for Surgery, Orthopaedics and Cancer Treatment, Department of Radiation Physics.
    Vogel, HJ
    NMR studies of monovalent ions in cultured plant cells1990Conference paper (Refereed)
  • 297.
    Lundberg, Peter
    et al.
    Linköping University, Department of Medical and Health Sciences, Division of Radiological Sciences. Linköping University, Faculty of Health Sciences. Linköping University, Center for Medical Image Science and Visualization (CMIV). Östergötlands Läns Landsting, Center for Surgery, Orthopaedics and Cancer Treatment, Department of Radiation Physics.
    Vogel, HJ
    Fabiansson, S
    Rudérus, H
    Tornberg, E
    Noninvasive 31P NMR studies of metabolities in meat1984Conference paper (Other academic)
  • 298.
    Lundberg, Peter
    et al.
    Linköping University, Department of Medical and Health Sciences, Division of Radiological Sciences. Linköping University, Faculty of Health Sciences. Linköping University, Center for Medical Image Science and Visualization (CMIV). Östergötlands Läns Landsting, Center for Surgery, Orthopaedics and Cancer Treatment, Department of Radiation Physics.
    Vogel, HJ
    Hellstrand, P
    NMR studies of energy metabolism in rabbit smooth muscle1986Conference paper (Other academic)
  • 299.
    Lundberg, Peter
    et al.
    Linköping University, Department of Medical and Health Sciences, Division of Radiological Sciences. Linköping University, Faculty of Health Sciences. Linköping University, Center for Medical Image Science and Visualization (CMIV). Östergötlands Läns Landsting, Center for Surgery, Orthopaedics and Cancer Treatment, Department of Radiation Physics.
    Vogel, HJ
    Larsson, G
    Tornberg, E
    Rudérus, H
    Multinuclear NMR studies of meat1985Conference paper (Other academic)
  • 300.
    Lundberg, Peter
    et al.
    Linköping University, Department of Medical and Health Sciences, Division of Radiological Sciences. Linköping University, Faculty of Health Sciences. Linköping University, Center for Medical Image Science and Visualization (CMIV). Region Östergötland, Center for Surgery, Orthopaedics and Cancer Treatment, Department of Radiation Physics.
    Weich, Rainer. G.
    Jensen, Paul.
    Vogel, Hans J.
    Phosphorus-31 and Nitrogen- 14 NMR Studies of the Uptake of Phosphorus and Nitrogen Compounds in the Marine Macroalgae Ulva lactuca1989In: Plant Physiology, ISSN 0032-0889, E-ISSN 1532-2548, Vol. 89, no 4, p. 1380-1387Article in journal (Refereed)
    Abstract [en]

    Cytoplasmic phosphomonoesters and inorganic phosphate, as well as vacuolar inorganic phosphate and polyphosphates, gave rise to the major peaks in (31)P nuclear magnetic resonance (NMR) spectra of the marine macroalgae Enteromorpha sp., Ceramium sp., and Ulva lactuca which were collected from the sea. In contrast, NMR-visible polyphosphates were lacking in Pylaiella sp. and intracellular vacuolar phosphate seemed to act as the main phosphorus store in this organism. In laboratory experiments, polyphosphates decreased in growing U. lactuca which was cultivated in continuous light under phosphate-deficient conditions. In contrast, the same organism cultivated in seawater with added phosphate and ammonium, accumulated phosphate mainly in the form of polyphosphates. When nitrate was provided as the only nitrogen source, accumulation of polyphosphates in the algae decreased with increasing external nitrate concentration. From the chemical shift of the cytoplasmic Pi peak, the cytoplasmic pH of superfused preparations of Ulva was estimated at 7.2. The vacuolar pH, determined from the chemical shifts of the vacuolar Pi and the terminal polyphosphate peaks, was between 5.5 and 6.0. The intracellular nitrate and ammonium levels in U. lactuca were determined by (14)N NMR. Both nitrogen sources were taken up and stored intracellularly; however, the uptake of ammonium was much faster than that of nitrate.

3456789 251 - 300 of 511
CiteExportLink to result list
Permanent link
Cite
Citation style
  • apa
  • ieee
  • modern-language-association-8th-edition
  • vancouver
  • oxford
  • 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