***TASK*** the task is to summarize an input biomedical literature in six sentences 
    ***INPUT*** the input is a biomedical literature 
    ***OUTPUT*** the output is the summary of an input biomedical literature in six sentences 
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    ***EXAMPLES*** 
    Input: OBJECTIVES The aim of the study was to assess prevalence , incidence , recovery , and risk factors of irritable bowel syndrome according to different definitions in a large r and om population . DESIGN A 5 year follow-up study of a sex- and age-stratified r and om sample of 4581 Danes interviewed about abdominal symptoms . SETTING The Glostrup Population s Studies Unit at Glostrup County Hospital . MAIN OUTCOME MEASURES Prevalence , incidence , recovery , and the association of risk factors to irritable bowel syndrome ( IBS ) . The percentage of subjects common to the population s selected by the various definitions of IBS . RESULTS According to various definitions , the prevalence of IBS varied from 5 to 65 % and the incidence varied from 1 to 36 % . At the 5 year follow-up only 5 % of subjects with IBS were completely free of all symptoms . Psychological vulnerability and the experience of having problems were strongly associated with prevalence and incidence of IBS , whereas lifestyle factors only showed a very weak or no relationship to IBS . Population s defined as suffering from IBS according to the various definitions had less than 50 % of the subjects in common . CONCLUSIONS Irritable bowel syndrome is frequent but fluctuating in the general population . Psychological factors seem to be of greater aetiological importance to IBS than lifestyle factors . However , a generally accepted and precise definition is essential to make future studies comparable and to allow general conclusions to be drawn . Furthermore , it still needs to be verified whether the syndrome is a disease entity or just an acceptable , common life-condition Alosetron is a 5‐hydroxytryptamine‐3 receptor antagonist reducing symptoms in female patients with diarrhoea‐predominant irritable bowel syndrome , and is known to increase the colonic transit time Functional gastrointestinal disorders , including the irritable bowel syndrome , account for up to 40 % of referrals to gastroenterologists , but accurate data on the natural history of these disorders in the general population are lacking . Using a reliable and valid question naire , the authors estimated the onset and disappearance of symptoms consistent with functional gastrointestinal disorders . An age- and sex-stratified r and om sample of 1,021 eligible residents of Olmsted County , Minnesota , aged 30 - 64 years were initially mailed the question naire ; 82 % responded ( n = 835 ) . In a remailing to responders 12 - 20 months later , 83 % responded again ( n = 690 ) . The age- and sex-adjusted prevalence rates per 100 for irritable bowel syndrome , chronic constipation , chronic diarrhea , and frequent dyspepsia were 18.1 ( 95 % confidence interval ( CI ) 15.1 - 21.1 ) , 14.7 ( 95 % CI 11.9 - 17.4 ) , 7.3 ( 95 % CI 5.3 - 9.3 ) , and 14.1 ( 95 % CI 11.5 - 16.8 ) , respectively , on the second mailing . Symptoms were not significantly associated with nonresponse to the second mailing ; moreover , the estimated prevalence rates were not significantly different from the first mailing . Among the 582 subjects free of the irritable bowel syndrome on the first survey , 9 % developed symptoms during 795 person-years of follow-up , while 38 % of the 108 who initially had the irritable bowel syndrome did not meet the criteria after 146 person-years of follow-up . Similar onset and disappearance rates were observed for the other main symptom categories . While functional gastrointestinal symptoms are common in middle-aged persons and overall prevalence appears relatively stable over 12 - 20 months , substantial turnover is implied by the observed onset and disappearance rates ; several potential sources of bias do not seem to account for this variation Background Flatulence is a common symptom in patients with irritable bowel syndrome ( IBS ) . This may be due to production of hydrogen by intestinal flora . With the presence of methanogenic flora , 4 mol of hydrogen ( H2 ) are used with 1 mol of carbon dioxide ( CO2 ) to produce 1 mol of methane ( CH4 ) , a process greatly reducing the volume of gas in the colon . However , the prevalence of methanogenic flora has not yet been reported in healthy and IBS patients from North India . Therefore , this study was planned . Methods This study was conducted prospect ively and included 345 patients with irritable bowel syndrome ( fulfilling Rome II criteria ) and 254 age- and gender-matched apparently healthy controls . Each subject underwent a hydrogen breath test using 10 g lactulose after an overnight fast . An SC Microlyser from Quintron , USA , was used to measure methane and hydrogen at baseline and at every 30 min for 4 h. Subjects with fasting methane concentration < 10 p.p.m . were labeled as low methane producers ( LMPs ) and > 10 p.p.m . as predominant methane producers ( PMPs ) . Results The IBS and control groups included 66.78 % and 67.53 % men , respectively . Mean age in the two groups was 48.52 ± 30.54 years ( range 15–68 years ) and 45.67 ± 30.54 years ( range 15–78 years ) , respectively . Prevalence of predominant methanogenic flora in IBS and control groups was 14.5 % ( 50/345 ) and 34.6 % ( 88/254 ) , respectively ( P < 0.001 ) . Fifty-two out of 254 ( 20.6 % ) were PMPs and 36 out of 254 ( 14.0 % ) were LMPs in controls . In contrast to this , IBS patients had 17 out of 354 ( 4.9 % ) that were PMPs and 33 out of 345 ( 9.6 % ) that were LMPs . Conclusion Methanogenic flora was significantly lower in IBS patients from North India than in apparently healthy subjects . This may be one of the causes of flatulence in IBS patients & NA ; Visceral pain processing is abnormal in a majority of irritable bowel syndrome ( IBS ) patients . Aberrant endogenous nociceptive modulation and anticipation are possible underlying mechanisms investigated in the current study . Twelve IBS patients and 12 matched healthy controls underwent brain fMRI scanning during the following r and omised stimuli : sham and painful rectal distensions by barostat without and with simultaneous activation of endogenous descending nociceptive inhibition using ice water immersion of the foot for heterotopic stimulation . Heterotopic stimulation  decreased rectal pain scores from 3.7 ± 0.2 to 3.1 ± 0.3 ( mean ± SE , scale 0–5 ) in controls ( p < 0.01 ) , but not significantly in IBS . Controls differed from IBS patients in showing significantly greater activation bilaterally in the anterior insula , SII and putamen during rectal stimulation alone compared to rectal plus heterotopic stimulation . Greater activation during rectal plus heterotopic versus rectal stimulation was seen bilaterally in SI and the right superior temporal gyrus in controls and in the right inferior lobule and bilaterally in the superior temporal gyrus in IBS . Rectal pain scores were similarly low during sham stimulation in both groups , but brain activation patterns differed . In conclusion , IBS patients  showed dysfunctional endogenous inhibition of pain and concomitant aberrant activation of brain areas involved in pain processing and integration . Anticipation of rectal pain was associated with different brain activation patterns in IBS involving multiple interoceptive , homeostatic , associative and emotional areas , even though pain scores were similar during sham distension . The aberrant activation of endogenous pain inhibition appears to involve circuitry relating to anticipation as well as pain processing itself OBJECTIVE : Little is known about the natural history of functional GI symptoms , including what factors influence GI symptom patterns and health care seeking for them over the long term . We aim ed to determine whether psychological factors play a role in the development and long-term course of these symptoms . METHODS : A r and om sample of community subjects ( n = 361 ) who reported having unexplained abdominal pain for ≥1 month in a previous population survey were included in the study . Controls ( n = 120 ) were defined as not having abdominal pain for ≥1 month from this initial survey . Subjects were prospect ively followed up via a question naire every 4 months over a 12-month period . The question naire asked about the  presence of GI symptoms over the past week and psychological distress  over the past 3 wk ( psychological caseness being defined as a score of ≥2 of 12 on the General Health Question naire ) . The number of visits made to a physician or medical specialist over the past 4 months was evaluated . RESULTS : GI symptoms were common among community controls and subjects with abdominal pain .  Similar onset and disappearance rates were observed for the majority of GI symptom categories , accounting for the stability of the prevalence rates over a 1-yr period . Changes in a state measure of psychological distress were not significantly associated with changes in GI symptom status between the 4- and 8-month ( r= 0.14 , p= 0.08 ) and 8- and 12-month ( r= 0.02 , p= 0.77 ) follow-ups . Baseline psychological distress , however , was an independent predictor of having persistent GI symptoms , including abdominal pain , bloating , and constipation , and frequently seeking health care for GI symptoms over 1 yr . CONCLUSIONS : Psychological distress levels do not seem to be important in explaining GI symptom change over a 1-yr period . Psychological distress , however , is linked to having persistent GI symptoms and frequently seeking health care for them over time . Clinicians should consider psychological factors in the treatment of this subset of irritable bowel syndrome patients BACKGROUND : While symptom question naires provide a snapshot of bowel habits , they may not reflect day-to-day variations or the relationship between bowel symptoms and stool form . AIM : To assess bowel habits by daily diaries in women with and without functional bowel disorders . METHOD : From a community-based survey among Olmsted County , MN , women , 278 r and omly selected subjects were interviewed by a gastroenterologist , who completed a bowel symptom question naire . Subjects also maintained bowel diaries for 2 wk . RESULTS : Among 278 subjects , question naires revealed diarrhea ( 26 % ) , constipation ( 21 % ) , or neither ( 53 % ) . Asymptomatic subjects reported bowel symptoms ( e.g. , urgency ) infrequently ( i.e. , < 25 % of the time ) and generally for hard or loose stools . Urgency for soft , formed stools ( i.e. , Bristol form = 4 ) was more prevalent in subjects with diarrhea ( 31 % ) and constipation ( 27 % ) than in normals ( 16 % ) . Stool form , straining to begin ( odds ratio [ OR ] 4.1 , 95 % confidence interval [ CI ] 1.7–10.2 ) and end ( OR 4.7 , 95 % CI 1.6–15.2 ) defecation increased the odds for constipation . Straining to end defecation ( OR 3.7 , 95 % CI 1.2–12.0 ) , increased stool frequency ( OR 1.9 , 95 % CI 1.02–3.7 ) , incomplete evacuation ( OR 2.2 , 95 % CI 1.04–4.6 ) , and rectal urgency ( OR 3.1 , 95 % CI 1.4–6.6 ) increased the odds for diarrhea . In contrast , variations in stool frequency and form were not useful for discriminating between health and disease . CONCLUSIONS : Bowel symptoms occur in association with , but are only partly explained by , stool form disturbances . These observations support a role for other pathophysiological mechanisms in functional bowel disorders Objectives The role of melatonin in regulating gut motility in human subjects is not clear . The aim of this study was to investigate the effects of exogenous melatonin on colonic transit time ( CTT ) in healthy subjects and in patients with irritable bowel syndrome ( IBS ) . Methods Colonic transit time was measured in 17 healthy controls using the radio-opaque , blue dye , and Bristol stool form score method before and after 30 days of melatonin treatment 3 mg daily . A double blind cross-over study aim ed at measuring CTT was also performed in 17 matched IBS patients using the blue dye and Bristol stool form score methods . The patients were r and omized and received either melatonin 3 mg or placebo daily for 8 weeks , followed by a 4-week washout , and then placebo or melatonin in the reverse order for a second 8-week period . Results The melatonin treatment of the control subjects caused an increase in CTT ( mean ± SD ) from 27.4 ± 10.5 to 37.4 ± 23.8 h ( P = 0.04 ) . Compared with the CTT of the controls ( 25.2 ± 7.7 ) , that of the constipation-predominant IBS patients appeared prolonged—65.2 ± 33.3 h ( P < 0.01 ) . The CTT did not change significantly in IBS patients  after melatonin treatment . Conclusion Melatonin may be a promising c and i date for the future research of agents that can modulate bowel motility Modern methods of diagnosing diarrhe 
    Output:
    
The definitions of healthy controls in studies of functional bowel diseases such as IBS are inconsistent .