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- Stjernman, Henrik
(författare)
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Crohn’s Disease in Sickness and in Health : Studies of Health Assessment Strategies and Impact on Health-Related Quality of Life
- 2011
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Background and aims. Crohn’s disease (CD) is a chronic inflammatory bowel disease (IBD) with potentially deleterious effects on well-being and daily-life functioning. A complete picture of health status in CD therefore comprises both disease activity (DA) and health-related quality of life (HRQL). Several measures of DA and HRQL in CD have been developed. Some have gained prominence as standard endpoints in clinical trials, but none has been validated in Swedish CD patients and their use in clinical practice has been limited. A conceptual health status model of five dimensions (Biological variables, Symptoms, Function, Worries, and Well-being) has been proposed for IBD health assessment, enabling the construction of the Short Health Scale (SHS), a four-item questionnaire intended to facilitate assessment and interpretation of HRQL in IBD.The aims of this thesis were: (1) to evaluate the Swedish versions of the Inflammatory Bowel Disease Questionnaire (IBDQ) and the Rating Form of IBD Patient Concerns (RFIPC); (2) to evaluate the Short Health Scale; (3) to study the relationship between DA and HRQL variables by identifying determinants of DA outcome and by validating the SHS health status model; (4) to describe the spectrum of disease-related worries and repercussions on general HRQL in a context of social variables, sickness, and disability.Methods. The thesis is based on clinical variables and HRQL data measured in a population-based cohort of 505 CD patients, consecutively included in conjunction with their regular outpatient visits at three hospitals (Jönköping, Örebro, Linköping). The HRQL questionnaires were evaluated regarding construct validity, reliability, and responsiveness. Multivariate analyses were used to investigate the relationship between Crohn’s Disease Activity Index (CDAI) and physician-assessed DA. The SHS health status model was validated with structural equation modelling (SEM). Disease-related worries and concerns, general HRQL, social variables, sickness, and work disability were compared with data from background population or patients with ulcerative colitis (UC).Results. The IBDQ had good validity, reliability, and responsiveness, but the original dimensional structure was not supported. The RFIPC was valid, and reliable, but less sensitive to change in disease activity. The SHS had the highest completion rate and proved adequate psychometric properties. The CDAI correlated weakly with the physician’s appraisal of disease activity, being more influenced by subjective health perception than objective disease activity. SEM showed that the SHS model had a good fit to measured data, explaining >98% of the covariance of the variables. Worries and general HRQL impairment were greater in CD than in UC, especially for women. Disease complications and impaired life achievements elicited most worries. CD patients had lower educational level. Female patients were more often living single. The rates of long-term sickness and disability were doubled compared with background population, with worse outcome for women.Conclusions. The IBDQ, the RFIPC, and the SHS all demonstrated adequate psychometric properties. The SHS was easier to administer and provided a more comprehensive picture of subjective health status. The weak correlation between CDAI and physician-assessed DA was explained by a strong influence of subjective variables on CDAI, stressing the importance of assessing DA and HRQL separately. The SHS health status model was further supported by SEM. CD has tangible effects on subjective health perception, worries and work capacity, especially for women.
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| 2. |
- Lowén, Mats, 1977-
(författare)
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Irritable Bowel Syndrome : Studies of central pathophysiological mechanisms and effects of treatment
- 2015
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Background and aimsIrritable bowel syndrome (IBS) is a common gastrointestinal disorder characterized by abdominal pain and altered bowel habits. The societal costs of the disorder are significant, as are its negative effects on quality of life. Medical treatment options are limited, but psychological treatments such as hypnotherapy have proven to be effective. Important pathophysiological mechanisms include disturbances in brain processing of visceral sensation and expectation of visceral sensation. Increased sensation of stimuli (hypersensitivity) is present in a subset of IBS patients to distensions in the lower part of the gastrointestinal tract, indicating a probable important pathophysiological mechanism in IBS. The overall aim of the thesis was to further study the central pathophysiological mechanisms involved in IBS. Specifically, we aimed to identify differences in brain response to standardized repeated rectal distensions and expectation of these stimuli between IBS patients (with or without perceptual rectal hypersensitivity), and healthy controls. Furthermore, we aimed to investigate IBS patients´ brain responses to standardized rectal distensions and expectation of these stimuli after either a successful course hypnotherapy or educational intervention.MethodsFunctional magnetic resonance imaging (fMRI) data were acquired and analyzed from 15 IBS patients with visceral hypersensitivity, and 18 IBS patients with normal visceral sensitivity (papers I and II). In paper III, fMRI data were analyzed from IBS patients who reported significant symptom reduction after either a course of hypnotherapy, or an educational intervention. FMRI data from IBS patients and healthy controls were also compared.ResultsThe findings reported in papers I and II suggest, that the differences in brain response between IBS patients with and without rectal hypersensitivity, can be explained by changes in brain response during the course of the experiment. Even though the brain responses were similar between groups during the early phase of the experiment, they became substantially different during the late phase. The IBS patients with rectal hypersensitivity demonstrated increased brain response in several brain regions and networks involved in visceral sensation and processing. In contrast, IBS patients with normal rectal sensitivity exhibited reduced brain response during the late phase of the experiment. As reported in paper III, similar symptom reduction was achieved for both treatments. The symptomatic improvement was associated with a reduction of response in the anterior insula, indicating an attenuated awareness of the stimuli. The hypnotherapy group had a reduction of response in the posterior insula, indicating less input to the brain, possibly due to changed activity in endogenous pain modulatory systems. In patients who reported significant symptom reduction following treatment, the brain response to rectal distension got more similar to that observed in healthy controls.ConclusionsThe results from papers I and II indicate that a subpopulation of IBS patients lacks the ability to habituate to repeated rectal distensions and expectation of these stimuli. Results from paper III indicate that the abnormal processing of visceral stimuli in IBS can be altered, and that the treatments probably had a normalizing effect on the central processing abnormality of visceral signals in IBS.
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| 3. |
- Münch, Andreas
(författare)
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Collagenous colitis : The influence of inflammation and bile acids on intestinal barrier function
- 2010
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Background and aims: Collagenous colitis (CC) is a diarrheal disorder with an incidence rate of 5-6/100000 inhabitants, affecting mainly middle-aged women. The diagnosis is made by histology of the colonic mucosa. Classical findings are a thickened subepithelial collagenous layer and chronic inflammation in the lamina propria. In inflammatory bowel disease (IBD) the mucosal barrier function is important in pathogenesis. The main purpose of the thesis was therefore to describe the barrier function in CC. The cause of CC is uncertain but the condition seems to be associated with bile acid malabsorption. Increased faecal bile acids are known to induce diarrhea. In functional studies the influence of bile acids on mucosal permeability in biopsies of healthy human individuals and in patients with CC was investigated.Methods and patients: In the first paper a single patient with intractable CC was examined before surgery, with loop-ileostomy and after bowel reconstruction. For the other studies a total of 25 patients with CC were included (20 women, 5 men, mean age 66 years). There were three groups (14 patients in clinical remission without medical treatment, 11 with active disease, and 8 of these again after 6 weeks of budesonide treatment); 17 individuals with normal histology served as controls. Endoscopic biopsies from the sigmoid colon were mounted in modified Ussing chambers and assessed for short-circuit current (Isc), transepithelial resistance (TER), and transmucosal passage of chemically killed E. coli K12 after addition of chenodeoxycholic acid (CDCA) and deoxycholic acid (DCA). The biopsies were further investigated with confocal microscopy to assess bacterial transepithelial passage.Results: Para- and transcellular permeability was increased in active CC, but normalized with histological improvement due to faecal stream diversion. After bowel reconstruction, permeability to CrEDTA and HRP increased again.In CC, bacterial uptake in colonic biopsies was significantly higher in all groups than in controls. Despite significant alleviation of symptoms, budesonide did not normalize the increased bacterial passage. Histology was unchanged after 6 weeks of budesonide treatment. DCA augmented mucosal permeability to CrEDTA in a dose-dependent manner and even such a low dose as 100 μmol/l DCA increased bacterial uptake significantly. The combination of bile acids and E.coli K12 had additive effects on TER.100 μmol/l CDCA and DCA increased bacterial uptake in biopsies of CC patients in remission 4-fold, but had no additive effect on biopsies from patients with active disease. Furthermore, patients in clinical remission on budesonide treatment showed no bile acidinduced effects on E.coli K12 passage.Conclusion: Collagenous colitis presents with increased para/transcellular permeability and bacterial uptake, irrespective of disease activity or budesonide treatment, signifying an underlying mucosal barrier defect. Faecal stream diversion can normalize the barrier dysfunction, but budesonide does not, despite its beneficial clinical effects which alleviate diarrhea or bowel symptoms. Bile acids in physiological concentrations have the potential to augment bacterial uptake, especially in mucosa from CC patients in remission. Budesonide treatment appears to counteract the bile acid induced mucosal impairment. These detrimental effects of bile acids on mucosal barrier function might facilitate initiation and perpetuation of mucosal inflammation in CC.
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| 4. |
- Bednarska, Olga, 1973-
(författare)
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Peripheral and Central Mechanisms in Irritable Bowel Syndrome : in search of links
- 2019
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Irritable bowel syndrome (IBS) is a chronic visceral pain disorder with female predominance, characterized by recurrent abdominal pain and disturbed bowel habits in the absence of an identifiable organic cause. This prevalent and debilitating disease, which accounts for a substantial economic and individual burden, lacks exact diagnostic tools and effective treatment, since its pathophysiology remains uncertain. The bidirectional and multilayered brain-gut axis is a well-established disease model, however, the interactions between central and peripheral mechanisms along the brain-gut axis remain incompletely understood. One of the welldescribed triggering factors, yet accounting for only a fraction of IBS prevalence, is bacterial gastroenteritis that affects mucosal barrier function. Altered gut microbiota composition as well as disturbed intestinal mucosal barrier function and its neuroimmune regulation have been reported in IBS, however, the impact of live bacteria, neither commensal nor pathogenic, on intestinal barrier has not been studied yet. Furthermore, abnormal central processing of visceral sensations and psychological factors such as maladaptive coping have previously been suggested as centrally-mediated pathophysiological mechanisms of importance in IBS. Brain imaging studies have demonstrated an imbalance in descending pain modulatory networks and alterations in brain regions associated with interoceptive awareness and pain processing and modulation, particularly in anterior insula (aINS), although biochemical changes putatively underlying these central alterations remain poorly understood. Most importantly, however, possible associations between these documented changes on central and peripheral levels, which may as complex interactions contribute to disease onset and chronification of symptoms, are widely unknown.This thesis aimed to investigate the peripheral and central mechanisms in women with IBS compared to female healthy controls (HC) and to explore possible mutual associations between these mechanisms.In Paper I, we studied paracellular permeability and passage of live bacteria, both commensal and pathogenic through colonic biopsies mounted in Ussing chambers. We explored the regulation of the mucosal barrier function by mast cells and the neuropeptide vasoactive intestinal polypeptide (VIP) as well as a correlation between mucosal permeability and gastrointestinal and psychological symptoms. We observed increased paracellular permeability and the passage of commensal and pathogenic live bacteria in patients with IBS compared with HC, which was diminished by blocking the VIP receptors as well as after stabilizing mast cells in both groups. Moreover, higher paracellular permeability was associated with less somatic and psychological symptoms in patients.In Paper II, we aimed to determine the association between colonic mucosa paracellular permeability and structural and resting state functional brain connectivity. We demonstrated different patterns of associations between mucosa permeability and functional and structural brain connectivity in IBS patients compared to HC. Specifically, lower paracellular permeability in IBS, similar to the levels detected in HC, was associated with more severe IBS symptoms and increased functional and structural connectivity between intrinsic brain resting state network and descending pain modulation brain regions. Our findings further suggested that this association between mucosa permeability and functional brain connectivity was mainly mediated by coping strategies.In Paper III, we investigated putative alterations in excitatory and inhibitory neurotransmission of aINS, as the brain’s key node of the salience network crucially involved in cognitive control, in IBS patients relative to HC and addressed possible connections with both symptoms and psychological factors. We found decreased concentrations of the excitatory neurotransmitter Glx in bilateral aINS in IBS patients compared to HC, while inhibitory neurotransmitter GABA+ levels were comparable. Further, we demonstrated hemisphere-specific associations between abdominal pain, coping and aINS excitatory neurotransmitter concentration.In conclusion, this thesis broadens the knowledge on peripheral and central mechanisms in IBS and presents novel findings that bring together the ends of brain-gut axis. Our results depict association between mucosal permeability, IBS symptoms and functional and structural connectivity engaging brain regions involved in emotion and pain modulation as well as underlying neurotransmitter alterations.
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