Gender differences in irritable bowel syndrome

Value of different diagnostic criteria for the irritable bowel syndrome among men and women

INTRODUCTION

Whether the diagnostic value of various criteria used to diagnose irritable bowel syndrome (IBS) differ by sex is controversial.

AIM

To evaluate the sex-specific value of varying IBS criteria and sex-specific symptoms in patients with IBS and organic disease.

METHODS

Outpatients of a gastroenterology practice (64% female) completed a validated questionnaire and received a complete diagnostic work-up as required. Questionnaire data were collected prospectively and audited retrospectively.

RESULTS

Overall 233 (male 21%) had a final diagnosis of IBS; 305 (male 47%) received a diagnosis of organic disease. Constipation and bloating were more frequent in females independent whether they had IBS or organic disease. The sensitivity of the diagnostic criteria in male patients was between 82% and 88%, when Manning (3 or more), Rome I or Rome II criteria were applied, whereas the specificity was 65% to 71%. In females, sensitivity was 62% to 64% and specificity was between 66% and 70%. Although all the diagnostic IBS criteria had higher positive predictive values in females versus males, the negative predictive values were lower in females.

CONCLUSIONS

Current criteria for IBS differ modestly between sexes, probably reflecting variable prevalence of the disease rather than a sex-specific presentation of IBS.

Daily stress and gastrointestinal symptoms in women with irritable bowel syndrome

BACKGROUND

Stress has been implicated as contributing to the initiation and exacerbation of bowel and discomfort symptoms in patients with irritable bowel syndrome (IBS).

OBJECTIVE

To examine the relationships of daily self-reported stress to gastrointestinal (GI) and psychological distress symptoms both across women and within woman in a comparison group of women without IBS and among subgroups of women with IBS.

METHODS

Women with IBS (n = 181; age = 18-49 years) who were divided into subgroups based on bowel pattern (constipation, n = 52; diarrhea, n = 67; alternating, n = 62) were compared to a group of women without IBS (n = 48). Self-report stress measures; abdominal (abdominal pain, bloating, and intestinal gas), bowel pattern (constipation, diarrhea), and intestinal gas; and psychological (anxiety and depression) distress symptoms were obtained daily over 1 month. Across-women and within-woman analyses were used.

RESULTS

There were significant across-women correlations among mean daily stress, psychological distress, and GI symptoms in the total IBS group and the IBS bowel pattern subgroups. The across-women relationships between daily stress and GI symptoms were diminished when anxiety and depression were controlled in the analyses. Within-woman analyses showed little evidence of relationship between day-to-day variations in stress and day-to-day variations in GI symptoms; however, stress was strongly related to anxiety and depression.

DISCUSSION

Gastrointestinal symptom distress is associated with self-reported stress in women with IBS. Psychological distress moderates the effects of stress on GI symptoms. The IBS treatment protocols that incorporate strategies that decrease stress and psychological distress are likely to reduce GI symptoms.

Estrogen modulation of ovariectomy-induced hyperalgesia in adult mice

Some chronic pain conditions are more prevalent in women. However, the evidence from both human and animal studies as to whether estrogen is pro- or anti-nociceptive is inconsistent. We have used a model of functional abdominal pain in mice to examine the role of estrogen in the modulation of a hyperalgesic state induced by ovariectomy. C57/BL6 female mice were either ovariectomized (OVX), received the same surgery without removing the ovaries or were tested without any surgical procedure. Mechanical hyperalgesia was assessed by von Frey filaments and thermal pain was measured using a hot-plate at 50 degrees C. OVX mice, but not sham-operated, developed mechanical hyperalgesia localized to the abdominal region, the hindlimbs and the proximal tail, 4-5 weeks after OVX as well as a reduction in response latency to the hot plate. OVX animals were implanted with 17beta-estradiol pellets or with similar pellets with no hormone five weeks after OVX, when the hyperalgesic state was fully developed, and the estrogen reversed both mechanical and thermal hyperalgesia. Vaginal smears were taken to record the phase of the cycle at the time of the test from all animals and no significant differences were detected in mechanical hyperalgesia or in thermal pain threshold between normal animals in different phases of their estrous cycle. These results show that OVX induces a hyperalgesic state of slow onset and long duration that can be reversed by estrogen. We have also observed no estrous cycle modulation of pain sensitivity in normal animals.

Irritable bowel syndrome is more common in women regardless of the menstrual phase: a Rome II-based survey

Functional gastrointestinal disorders are more common in women in relation to the fluctuations of female sex hormones. We tried to know the gender-related differences in the prevalence of irritable bowel syndrome and gastrointestinal symptoms according to the menstrual phase. A total of 253 women before menopause and 252 men below age 50 were examined by a gastroenterologist after completing the questionnaire. Blood tests, endoscopic procedures, and imaging studies were done, if needed. Women were subclassified into three groups according to their menstruation period; menstrual phase, proliferative phase, and secretory phase. Finally, 179 men and 193 women were analyzed. Irritable bowel syndrome was more frequently noticed in women than in men (p=0.01). The diarrhea-dominant type was more common in men, while constipation-dominant or alternating types were more common in women (p<0.001). Of 193 women, there was no significant difference in their gastrointestinal symptoms according to their menstrual phase. Regardless of the menstrual phase, gastrointestinal symptoms are more frequent in women. Physicians should consider different symptomatic manifestations between men and women should be considered when evaluating functional gastrointestinal disorders.

Experimental gastritis in mice enhances anxiety in a gender-related manner

There is a gender-related comorbidity of pain-related and inflammatory bowel diseases with psychiatric diseases. Since the impact of experimental gastrointestinal inflammation on the emotional-affective behavior is little known, we examined whether experimental gastritis modifies anxiety, stress coping and circulating corticosterone in male and female Him:OF1 mice. Gastritis was induced by adding iodoacetamide (0.1%) to the drinking water for at least 7 days. Inflammation was assessed by gastric histology and myeloperoxidase activity, circulating corticosterone determined by enzyme immunoassay, anxiety-related behavior evaluated with the elevated plus maze and stress-induced hyperthermia tests, and depression-like behavior estimated with the tail suspension test. Iodoacetamide-induced gastritis was associated with gastric mucosal surface damage and an increase in gastric myeloperoxidase activity, this increase being significantly larger in female mice than in male mice. The rectal temperature of male mice treated with iodoacetamide was enhanced, whereas that of female mice was diminished. The circulating levels of corticosterone were reduced by 65% in female mice treated with iodoacetamide but did not significantly change in male mice. On the behavioral level, iodoacetamide treatment caused a decrease in nocturnal home-cage activity, drinking and feeding. While depression-related behavior remained unaltered following induction of gastritis, behavioral indices of anxiety were significantly enhanced in female but not male mice. There was no correlation between the estrous cycle and anxiety as well as circulating corticosterone. Radiotracer experiments revealed that iodoacetamide did not readily enter the brain, the blood-brain ratio being 20:1. Collectively, these data show that iodoacetamide treatment causes gastritis in a gender-related manner, its severity being significantly greater in female than in male mice. The induction of gastritis in female mice is associated with a reduction of circulating corticosterone and an enforcement of behavioral indices of anxiety. Gastric inflammation thus has a distinct gender-dependent influence on emotional-affective behavior and its neuroendocrine control.

Irritable bowel syndrome: current approach to symptoms, evaluation, and treatment

There are frequent advances in knowledge about the clinical presentation, pathophysiology, and treatment of irritable bowel syndrome. It is important for clinicians to be aware of available therapies and the supporting evidence for those therapies to increase patient satisfaction. This is best achieved with a collaborative and long-term clinician-patient relationship and mutual commitment to modify therapy and try new modalities until the greatest relief of symptoms and improvement in health-related quality of life is achieved. This article reviews symptoms, comorbidities, gender differences, and measure of severity in irritable bowel syndrome and current and evidence-based approaches to evaluation and treatment, and the new symptom-based Rome III diagnostic criteria are reviewed and explained.

The complex role of estrogens in inflammation

There is still an unresolved paradox with respect to the immunomodulating role of estrogens. On one side, we recognize inhibition of bone resorption and suppression of inflammation in several animal models of chronic inflammatory diseases. On the other hand, we realize the immunosupportive role of estrogens in trauma/sepsis and the proinflammatory effects in some chronic autoimmune diseases in humans. This review examines possible causes for this paradox. This review delineates how the effects of estrogens are dependent on criteria such as: 1) the immune stimulus (foreign antigens or autoantigens) and subsequent antigen-specific immune responses (e.g., T cell inhibited by estrogens vs. activation of B cell); 2) the cell types involved during different phases of the disease; 3) the target organ with its specific microenvironment; 4) timing of 17beta-estradiol administration in relation to the disease course (and the reproductive status of a woman); 5) the concentration of estrogens; 6) the variability in expression of estrogen receptor alpha and beta depending on the microenvironment and the cell type; and 7) intracellular metabolism of estrogens leading to important biologically active metabolites with quite different anti- and proinflammatory function. Also mentioned are systemic supersystems such as the hypothalamic-pituitary-adrenal axis, the sensory nervous system, and the sympathetic nervous system and how they are influenced by estrogens. This review reinforces the concept that estrogens have antiinflammatory but also proinflammatory roles depending on above-mentioned criteria. It also explains that a uniform concept as to the action of estrogens cannot be found for all inflammatory diseases due to the enormous variable responses of immune and repair systems.

Sex-dependent differences in the activity and modulation of N-methyl-d-aspartic acid receptors in rat dorsal root ganglia neurons

Women have greater temporal summation of experimental pain stimuli and also have a higher propensity for developing chronic visceral pain conditions. Sex hormone-mediated regulation of N-methyl-d-aspartic acid receptors (NMDARs) in nociceptive pathways is a plausible mechanism that may underlie these phenomena. The aim of this study was to compare the effect of 17-beta-estradiol (E2) in modulation of NMDAR activity in adult male and female rat dorsal root ganglia (DRG) neurons. DRG neurons were collected from adult male or female rats and grown in short-term culture in steroid-free media. NMDAR currents were recorded on small to medium size neurons by whole cell patch clamp using rapid perfusion with saturating concentrations of N-methyl-d-aspartic acid and glycine in the absence of extracellular Mg(2+). We found that the average density of NMDAR currents was 2.8-fold larger in DRG neurons from female rats compared with male rats (P<0.0001). Addition of 100 nM E2 increased NMDAR currents 55+/-15% in female neurons, but only 19+/-7% in male neurons. Potentiation was maximal after 20-40 min and dose dependent with an apparent 50% excitatory concentration of 17-23 nM. This effect was mimicked by E2 conjugated to BSA and attenuated by pretreatment with the protein tyrosine kinase inhibitor lavendustin A (1 microM) or the estrogen receptor (ER) antagonist, ICI 182,780 (1 microM), strongly suggesting activation of a cell surface ER acting through a non-genomic mechanism involving protein tyrosine kinases to increase NMDAR currents. These results identify sex-based differences in both the basal expression and the regulation of the NMDARs in DRG neurons.

Somatic focus/awareness: Relationship to negative affect and pain in chronic pain patients

Somatic focus refers to the tendency to notice and report physical symptoms, and has been investigated in relation to chronically painful conditions. This study investigated the relationship between somatic focus, as measured by the Pennebaker Inventory of Limbic Languidness (PILL), negative affect and pain. A secondary purpose of the present study was to examine sex differences in these relationships. Participants included 280 chronic pain patients (69.6% females, 88.9% Caucasian), who completed a battery of self-report measures on somatic focus, pain, negative affect, coping, and dysfunction. Results for the overall sample revealed that the PILL shares considerable variance with measures of negative affect, particularly with the physiological components of anxiety and depression. When the results were analyzed separately for male and female patients, it was found that several components of negative affect and cognitive factors play a stronger role in predicting somatic focus among men compared to women. Additional analyses then examined whether somatic focus was predictive of male and female patients' pain reports. Results indicated that somatic focus explained a small, but unique amount of variance in female patients' pain reports, which differed from the relationship observed among male patients.

Healthcare policy implications of heterogeneity of treatment effects

Heterogeneity of treatment effects (HTE) is a phenomenon wherein the same treatment produces different responses in different patients. Following scientific presentations at a conference on HTE in drug therapy, a roundtable panel discussed the policymaking implications of this phenomenon in the current healthcare environment. The presentation of evidence on HTE served as a backdrop for this more pragmatic, solutions-based discussion of how HTE should be addressed in light of the trend in healthcare toward use of evidence-based medicine along with professional society clinical practice guidelines for specific disease states. Overall, the panel concluded that a specific agent should be used when the clinician is equipped with sound data. However, in the absence of such data, care has to be individualized, using the clinician's best judgment regarding available treatment options. The sharing of data across all levels of the healthcare infrastructure is crucial for policymakers seeking to ensure quality care while considering the phenomenon of HTE and, at the same time, keeping cost-effectiveness a major concern.

Temporomandibular disorders: associated features

Temporomandibular disorder (TMD) encompasses a number of clinical problems involving the masticatory muscles or the temporomandibular joints. These disorders are a major cause of nondental pain in the orofacial region, and are considered to be a subclassification of musculoskeletal disorders. Orofacial pain and TMD can be associated with pathologic conditions or disorders related to somatic and neurologic structures. When patients present to the dental office with a chief complaint of pain or headaches, it is vital for the practitioner to understand the cause of the complaint and to perform a thorough examination that will lead to the correct diagnosis and appropriate treatment. A complete understanding of the associated medical conditions with symptomology common to TMD and orofacial pain is necessary for a proper diagnosis.

Female bowel function: the real story

PURPOSE

There has been minimal research done on normal female bowel habits. Because we do not know what is normal, this affects counseling of patients and research. The aim of this study was to conduct a survey of females with no bowel pathology to obtain a baseline of normal bowel function and examine any normal changes that occur during a woman's lifetime.

METHODS

Females accompanying patients to our hospital and clinic were invited to fill out an IRB-approved questionnaire after excluding those with current bowel pathology, depression, a stoma, or were wheelchair bound.

RESULTS

Four hundred twenty-five of 528 questionnaires of females who reported they had normal bowel habits were evaluated. The age range was from 18 to 80 years and comparison was according to age, race, and parity. Fifty-one percent had one bowel movement daily while 30 percent reported fewer. Overall, 15 percent reported constipation, which was higher in African-American females (26 percent) vs. Caucasian females (14 percent), P = 0.08. The average time for a bowel movement was 5-6 minutes, which was longer in African-American females (7.7 min) vs. Caucasian (5.0 min), P = 0.002. Younger females had changes in their bowel pattern reported as soft stool usually associated with their menstrual cycle; this was seen mostly in single females. Menopause did not affect bowels. Thirty-six percent of parous females reported occasional stool incontinence. Flatal incontinence was seen occasionally in over 50 percent of females, more frequently in those over 35 years old. Seventy-four percent of parous females reported incontinence to gas. One-third of females read on the toilet, with a majority doing so to relax or to be distracted and with African-American females reading more (54 percent) vs. Caucasian (32 percent), P = 0.004. Interestingly, Caucasian females read to conserve time (26 percent) vs. African-Americans (4 percent), P = 0.02. Fiber as a supplement was taken by only 8 percent. Foods affected bowel function in all age groups, while travel and exercise did not. Stress affected a change in 35 percent in the 18 to 50-year group.

CONCLUSION

There is a vast diversity in what is considered normal female bowel habits. One daily bowel movement is not the norm. Normal older females and those who have had children report more flatal incontinence. One-third experience some element of fecal incontinence. Foods most commonly caused a change in bowel pattern, followed by menstruation, stress, and childbirth. A vast majority do not take fiber as a supplement.

Intramucosal ganglion cells in normal adult colorectal mucosa

Intramucosal ganglion cells are incompletely understood. Reviewed were 100 normal specimens from colorectal biopsies of nonconstipated adults to firmly establish the existence of intramucosal ganglion cells in normal adult colorectal mucosa, determine whether intramucosal giant ganglia exist, and compare the prevalence of colorectal intramucosal ganglion cells between men and women. Fifty specimens from each gender were examined. Twenty specimens contained intramucosal ganglion cells, including 15 from women (75%) and only 5 from men (25%). Intramucosal ganglion cells occurred singly or in clusters. One woman had large disciform and globular clusters with 7 ganglion cells, resembling giant ganglia. Awareness of ganglion cells and large ganglia in normal mucosa is necessary to avoid potential confusion with ectopic ganglion cells and submucosal giant ganglia seen in adult intestinal neuronal dysplasia. Intramucosal ganglion cells in normal colorectal mucosa are particularly common in women. This disparity might contribute to colorectal neurophysiologic differences between genders.

Lipid-induced colonic hypersensitivity in the irritable bowel syndrome: the role of bowel habit, sex, and psychologic factors

BACKGROUND & AIMS

Duodenal lipid infusion increases colonic hypersensitivity in irritable bowel syndrome (IBS). Whether this is affected by bowel habit, psychologic factors, or sex is unknown.

METHODS

We included 61 patients with IBS (50 women, 11 men), 25 with diarrhea-predominant IBS, 17 with constipation-predominant IBS, 19 with alternating-type IBS, and 20 healthy controls (15 women, 5 men). A colonic distension trial was performed with a barostat before and after a 1-hour duodenal lipid infusion (3 kcal/min). Colonic thresholds, colonic tone, and the viscerosomatic referral pattern were assessed and compared between groups. Patients also completed the Hospital Anxiety and Depression scale.

RESULTS

The reduction in colonic pressure thresholds after vs before duodenal lipids was greater in patients than in controls for discomfort (P = .006) and pain (P < .0001). An increased viscerosomatic referral area for pain and discomfort during colonic distensions after vs before duodenal lipids was observed in patients but not in controls. The response was similar in IBS subgroups based on the predominant bowel habit, in patients with vs without anxiety and/or depression, and in women and men with IBS. The colonic tone response during lipid infusion was similar in IBS patients and controls, and in the different IBS subgroups.

CONCLUSIONS

IBS patients show increased colonic sensitivity and altered viscerosomatic referral pattern after duodenal lipids. This response is largely unaffected by the predominant bowel habit, psychologic factors, or sex, but seems to be related to IBS per se.

Protease-activated receptors: potential therapeutic targets in irritable bowel syndrome?

Protease-activated receptors (PARs) are a family of four G-protein-coupled receptors (PAR-1 to PAR-4) activated by the proteolytic cleavage of their N-terminal extracellular domain. This activation first involves the recognition of the extracellular domain by proteases, such as thrombin, but also trypsin or tryptase which are particularly abundant in the gastrointestinal tract, both under physiological circumstances and in several digestive diseases. Activation of PARs, particularly of PAR-1 and -2, modulates intestinal functions, such as gastrointestinal motility, visceral nociception, mucosal inflammatory response, and epithelial functions (intestinal secretion and permeability). As these physiological properties have been shown to be altered in various extents and combinations in different clinical presentations of irritable bowel syndrome, PARs appear as putative targets for future therapeutic intervention in these patients.

Colorectal distension-induced pseudoaffective changes as indices of nociception in the anesthetized female rat: morphine and strain effects on visceral sensitivity

INTRODUCTION

Colorectal distension of a sufficient intensity evokes several characteristic postural, visceromotor and cardiovascular reflexes in conscious rats that have been extensively utilized for testing putative visceral analgesics. The neural circuitry for these reflexes is encompassed within the spinobulbar region and continues to be robust even after decerebration. Yet, these are not consistently replicated in anesthetized animals, presumably due to medullary depression. In the following studies, we tested the hypothesis that a carefully chosen anesthetic regimen can replicate the pattern of pseudoaffective responses seen in awake animals.

METHODS

Female rats were anesthetized with methohexital sodium and equipped with arterial and venous catheters, a colorectal balloon and abdominal wire electrodes. Subsequent anesthesia was maintained with urethane.

RESULTS

Colorectal distension produced clear changes in visceromotor and cardiovascular indices that not only mimicked responses to distension seen in conscious rats, but also importantly, showed a comparable stimulus sensitivity and stability. Morphine (ED(50), 0.17 mg/kg, iv) was highly efficacious in attenuating response in a dose-dependent and naloxone-selective manner. Using this model, we compared three commonly used rat strains (Wistar, Wistar-Kyoto and Sprague-Dawley) for distension-mediated responses. Whereas Wistar-Kyoto rats were significantly hyper-responsive to distension, the sensory threshold for distension was nearly identical across strains. Thus, we report an anesthetized female rat model that replicates characteristic responses associated with visceral pain in conscious rats and its modulation by known factors like analgesia and strain.

DISCUSSION

These findings provide a simple insensate model for testing novel visceral analgesics while eliminating postoperative recovery and motion-related artifact typically associated with colorectal distension studies in conscious rats. Thus, a viable and humane alternative to visceral nociception studies in conscious animals is offered.

Contribution of gender to pathophysiology and clinical presentation of IBS: should management be different in women?

The irritable bowel syndrome (IBS) is found more commonly in women than men. It is more prevalent in patients with chronic fatigue syndrome, fibromyalgia, and chronic pelvic pain, all syndromes characterized by pain and found predominantly in women. This article reviews evidence for a role of biological sex factors and gender on the pathways mediating visceral pain. The effect of gonadal hormones on gastrointestinal motility and the sensory afferent pathway and central processing of visceral stimuli and the contribution of gender role to the clinical presentation are discussed. Although differences in responses to treatment modalities between genders exist, the approach to IBS patients in both genders is quite similar. Nevertheless, a special attention to gender role and stress-related factors should be addressed. New developments in research, outlined in the paper, might bring more gender-specific treatments in the future.

A deficiency of gastric interstitial cells of Cajal accompanied by decreased expression of neuronal nitric oxide synthase and substance P in patients with type 2 diabetes mellitus

BACKGROUND

Gastrointestinal motility is impaired in patients with diabetes mellitus (DM). Interstitial cells of Cajal (ICC) in the gastrointestinal tract play a central role in gastrointestinal motility. The present study examined whether ICC density, or expression of neuronal nitric oxide synthase (nNOS)- and substance P (SP)-containing nerves in the gastric antrum, were altered in patients with type 2 DM.

METHODS

Paraffin-embedded gastric specimens from 51 controls and 36 male DM patients with gastric cancer were used for immunohistochemistry. Serial sections were stained with Kit and mast cell tryptase-specific antibodies. Fresh-frozen gastric specimens from patients with gastric cancer were used for immunofluorescence. The specimens were stained with antibodies to Kit, nNOS, and SP, and levels of expression of these three markers were compared between controls and DM patients.

RESULTS

ICC density in the inner circular muscle layer, but not in the myenteric plexus, was lower in patients with severe DM than in controls in paraffin-embedded specimens. In addition, decreased expression of nNOS and SP accompanied by reduced ICC density was observed in frozen specimens from patients with DM.

CONCLUSIONS

These results suggest that lower gastric ICC, nNOS, and SP densities in patients with DM may be associated with the pathogenesis of diabetic gastroparesis.

Investigation of serotonin type 4 receptor expression in human and non-human primate gastrointestinal samples

BACKGROUND

The serotonin type 4 (5-HT4) receptor has been associated with functions of the gastrointestinal tract such as modulation of the peristaltic reflex, smooth muscle tone, intestinal secretion and visceral sensitivity. The activation of peripheral 5-HT4 receptors with agonists such as tegaserod has been shown to accelerate gastric emptying and improve symptoms of constipation in animals and humans. However, detailed data on the expression profile and on the localization of this receptor subtype are lacking so far.

OBJECTIVE

To study the pattern and expression levels of 5-HT4 receptor messenger RNA expression in the gut.

METHOD

Normal tissue samples were collected from the whole gastrointestinal tract of patients undergoing abdominal surgery and, in addition, of monkeys. We performed a comprehensive analysis of 5-HT4 receptor expression by quantitative reverse transcription-polymerase chain reaction, using human and non-human primate tissues from the oesophagus to the rectum. In addition, the brain and heart of non-human primates were analysed.

RESULTS

Significantly higher levels of 5-HT4 receptor mRNA were measured in the human stomach, duodenum, jejunum, ileum and caecum and also in the corresponding non-human primate gut segments, ranging from 2- to 12-fold compared with the liver. No differences were found between females and males of both human and non-human primates.

CONCLUSIONS

These results show 5-HT4 receptor mRNA expression throughout the gastrointestinal tract in humans and primates, and also support the preclinical and clinical findings of 5-HT4 receptors ligands exhibiting multiple effects throughout the gastrointestinal tract.

Irritable bowel syndrome and chronic constipation: emerging drugs, devices, and surgical treatments

Irritable bowel syndrome (IBS) and chronic constipation (CC) are two of the most common functional disorders of the gut. CC and IBS are estimated to affect up to 20% and 27% of the North American population respectively. Although not life-threatening, CC and IBS can profoundly and negatively affect quality of life and are associated with a significant economic burden related to direct and indirect annual health-care costs. Possible etiologies for IBS and CC include alterations in visceral sensation and gastrointestinal motility. IBS may be caused by disturbances in brain-gut interactions affecting gastrointestinal motility and visceral sensitivity. Research efforts in CC have begun to identify abnormalities in myenteric neurons, alterations in neurotransmitters and their receptors, and incoordination of the muscles of the pelvic floor or anorectum. Both disorders may be influenced by genetic predisposition, environmental factors, and stress. In this article, the safety and efficacy of traditional and emerging therapies for CC and IBS are examined. In addition, their pathophysiology and symptoms are briefly reviewed.

Significance of Rome II-defined functional constipation in Taiwan and comparison with constipation-predominant irritable bowel syndrome

BACKGROUND

The epidemiology and impact of functional constipation on Asians remain unclear.

AIM

To determine the prevalence of functional constipation, its social/medical impact, and its distinction from constipation-predominant irritable bowel syndrome (C-IBS) in Taiwan.

METHODS

A Rome II questionnaire was administered to an apparently healthy adult Chinese population (n = 2865).

RESULTS

The prevalence of functional constipation was 8.5% and it was 2.7% for C-IBS. The functional constipation subjects were predominantly female and had excessive gastrointestinal-related doctor visits, absenteeism and sleep disturbance compared with controls (P < 0.01). Among functional constipation subjects, approximately 40% were 'consulters' with excessive doctor consultations, absenteeism and sleep disturbance. Female gender, the presence of sleep difficulty and higher constipation symptom scores were predictive of their consultation behaviour (P < 0.05). No differences existed in demographic variables, doctor consultations and absenteeism between 172 functional constipation and 54 C-IBS subjects. However, the C-IBS subjects experienced more severe constipation symptoms and sleep disturbance than functional constipation subjects.

CONCLUSIONS

Functional constipation in Taiwan is comparable with that in other countries. The clinical presentation of constipation-predominant irritable bowel syndrome differ somewhat from that of functional constipation.

Androgens regulate the sexually dimorphic production of co-contained galanin and cholecystokinin in lumbar laminae VII and X neurons

A population of rat lumbar laminae VII and X putative spinothalamic (STT) neurons that co-contain cholecystokinin-8 (CCK) and galanin (GAL) are sexually dimorphic. Males have a significantly greater number of these neurons, as well as having greater optical densities for both neuropeptides than females. Optical densities for GAL and CCK immunoreactivities in these lumbar neurons in rats that have the testicular feminization mutation (Tfm) are not significantly different from females; however, the number of these lumbar neurons in Tfm rats is significantly smaller than in females. These data suggest that androgens, as well as functional androgen receptors (that Tfm rats lack), are necessary for the establishment of these sexual dimorphisms. Functionally, these CCK- and GAL-containing neurons in the deep lumbar laminae may contribute to the establishment of known sex differences in the affective component of somatic and visceral nociception, as well as the sexually dimorphic nature of some pelvic diseases, e.g., irritable bowel syndrome or cystitis.

Sex differences in irritable bowel syndrome in Japanese university students

BACKGROUND

Epidemiological studies of irritable bowel syndrome (IBS) among young adults are few, especially in Asian countries. Our aim was to examine the prevalence of IBS, whether there was a sex difference, and whether allergic diseases were important risk factors for IBS in young adults.

METHODS

Newly enrolled university students completed health survey questionnaires regarding general health. Those with gastrointestinal symptoms completed the Gastrointestinal Symptom Rating Scale (GSRS) and an additional questionnaire covering the presence of allergic manifestations. IBS was diagnosed based on the Rome II criteria.

RESULTS

IBS was diagnosed in 268 of 2495 students [10.7%; constipation-predominant type (IBS-C), 128; diarrhea-predominant type (IBS-D), 117; unclassified, 23]. IBS-C was associated with female sex (odds ratio, 6.4; 95% confidence interval, 4.1-9.7; P < 0.001), whereas there was no sex difference in IBS-D. The proportions of subjects with food sensitivity were significantly different among the three groups (4.0%, subjects without IBS; 8.6%, IBS-C group; and 15.4%, IBS-D group) (P < 0.001). The median GSRS scores for pain (1.67 vs 1, P = 0.001), indigestion (1.75 vs 1.5, P < 0.001), and constipation (2.0 vs 1.33, P < 0.001) were higher, and the median diarrhea score was lower (1.33 vs 1.67) (P < 0.001), in women than in men. The median score for diarrhea (2.33 vs 1.67, P = 0.001) was significantly higher in subjects with food sensitivity than in those without.

CONCLUSIONS

There was a strong relationship between IBS-C and female sex, and food sensitivity seemed to be an exacerbating factor for IBS-D.

Multimodal pain stimulation of the gastrointestinal tract

Understanding and characterization of pain and other sensory symptoms are among the most important issues in the diagnosis and assessment of patient with gastrointestinal disorders. Methods to evoke and assess experimental pain have recently developed into a new area with the possibility for multimodal stimulation (e.g., electrical, mechanical, thermal and chemical stimulation) of different nerves and pain pathways in the human gut. Such methods mimic to a high degree the pain experienced in the clinic. Multimodal pain methods have increased our basic understanding of different peripheral receptors in the gut in health and disease. Together with advanced muscle analysis, the methods have increased our understanding of receptors sensitive to mechanical, chemical and temperature stimuli in diseases, such as systemic sclerosis and diabetes. The methods can also be used to unravel central pain mechanisms, such as those involved in allodynia, hyperalgesia and referred pain. Abnormalities in central pain mechanisms are often seen in patients with chronic gut pain and hence methods relying on multimodal pain stimulation may help to understand the symptoms in these patients. Sex differences have been observed in several diseases of the gut, and differences in central pain processing between males and females have been hypothesized using multimodal pain stimulations. Finally, multimodal methods have recently been used to gain more insight into the effect of drugs against pain in the GI tract. Hence, the multimodal methods undoubtedly represents a major step forward in the future characterization and treatment of patients with various diseases of the gut.

Women's Mental Health Research: The Emergence of a Biomedical Field

This review surveys the field of women's mental health, with particular emphasis on its evolution into a distinct area of biomedical research. The field employs a biomedical disease model but it also emphasizes social and cultural influences on health outcomes. In recent years, its scope has expanded beyond studies of disorders occurring in women at times of reproductive transitions and it now encompasses a broader study of sex and gender differences. Historical and conceptual influences on the field are discussed. The review also surveys gender differences in the prevalence and clinical manifestations of mental disorders. Epidemiological findings have provided a rich resource for theory development, but without research tools to test theories adequately, findings of gender differences have begged the question of their biological, social, and cultural origins. Clinical depression is used to exemplify the usefulness of a sex/gender perspective in understanding mental illness; and major theories proposed to account for gender differences are critically evaluated. The National Institutes of Health (NIH) is the primary federal funding source for biomedical women's mental health research. The review surveys areas of emphasis in women's mental health research at the NIH as well as some collaborative activities that represent efforts to translate research findings into the public health and services arenas. As new analytic methods become available, it is anticipated that a more fundamental understanding of the biological and behavioral mechanisms underlying sex and gender differences in mental illness will emerge. Nonetheless, it is also likely that integration of findings predicated on different conceptual models of the nature and causes of mental illness will remain a challenge. These issues are discussed with reference to their impact on the field of women's mental health research.

Effect of sex on perception of rectosigmoid stimuli in irritable bowel syndrome

In irritable bowel syndrome (IBS) patients, the relationship between sex and sensitivity to visceral stimuli is incompletely understood. Our aim was to evaluate the effect of sex on perceptual responses to visceral stimulation in IBS. Fifty-eight IBS patients (mean age 42+/-1 yr; 34 men, 24 women) and 26 healthy controls (mean age 38+/-3 yr; 9 men, 17 women) underwent barostat-assisted distensions of the rectum and sigmoid colon. Rectal discomfort thresholds were measured using a randomized, phasic distension paradigm before and after repeated noxious sigmoid stimulation (SIG, 60-mmHg pulses). Sex had a significant effect on rectal discomfort thresholds. Women with IBS were the most sensitive (lower thresholds [27+/-2.7 mmHg] and higher ratings), with significantly lower rectal discomfort thresholds compared with men with IBS (38+/-2.3 mmHg) and healthy women who were the least sensitive (41.9+/-3.2 mmHg; both P<0.01). There were no significant differences in rectal discomfort thresholds between healthy men (34+/-4.3 mmHg) and men with IBS. Across both IBS and control groups, women demonstrated a significant lowering of discomfort thresholds after noxious sigmoid stimulation (P<0.01), while men did not. Sex significantly influences perceptual sensitivity to rectosigmoid distension. Women show greater perceptual responses to this paradigm.

Sexually dimorphic responses of the brain norepinephrine system to stress and corticotropin-releasing factor

Stress-related psychiatric disorders are more prevalent in females than males, and this has been attributed to differences in stress sensitivity. As activation of the locus coeruleus (LC)-norepinephrine (NE) system is an important component of the stress response, this study compared LC responses to stress in female and male rats under different hormonal conditions in the halothane-anesthetized state. The mean basal LC discharge rate was similar between groups. However, the magnitude of LC activation elicited by hypotensive stress was substantially greater in females, regardless of hormonal status. The difference in stress sensitivity could be attributed to the differential postsynaptic sensitivity of LC neurons to corticotropin-releasing factor (CRF), which mediates LC activation by hypotension. CRF was 10-30 times more potent in activating LC neurons in female vs male rats. Interestingly, previous exposure to swim stress differentially regulated LC responses to CRF by sensitizing LC neurons of male, but not female, rats to CRF. The net effect of this was to abolish sex differences in LC sensitivity. Finally, CRF receptor (CRF-R) protein levels in the LC were greater in ovarectomized female vs male rats. This is the first study to demonstrate sex differences in the stress responsiveness of the brain noradrenergic system. Substantial sex differences were apparent in postsynaptic sensitivity to CRF and stress-induced regulation of postsynaptic sensitivity to CRF. These sex differences in the CRF regulation of the LC-NE system translate to a differential response to stress and may play a role in the increased vulnerability of females to stress-related psychiatric disorders.

Role of partially hydrolyzed guar gum in the treatment of irritable bowel syndrome

Irritable bowel syndrome (IBS) is the world's most common gastrointestinal functional disorder and is associated with several social and economic costs. Health-related quality of life is often impaired in patients with IBS. The pathophysiologic mechanisms underlying IBS remain poorly defined. The therapeutic approach to patients with IBS is based on symptoms, and fibers may play an important role in treatment. Among the various types of fiber, water-soluble, non-gelling fibers seem to be a promising option for treatment of IBS. Partially hydrolyzed guar gum (PHGG) is a water-soluble, non-gelling fiber that has provided therapeutic benefits. In clinical trials, PHGG decreased symptoms in constipation-predominant and diarrhea-predominant forms of IBS and decreased abdominal pain. Further, an improvement in quality of life was observed in patients with IBS during and after treatment with PHGG. Moreover, PHGG seems to have prebiotic properties because it increases the colonic contents of short-chain fatty acids, Lactobacilli, and Bifidobacteria.

Gender-related differences in visceral perception in health and irritable bowel syndrome

BACKGROUND

Irritable bowel syndrome (IBS) is more common in female subjects, and IBS patients generally exhibit reduced pain thresholds to rectal distension. The aim of the present paper was to determine gender-related differences in rectal perception in both healthy controls and IBS patients.

METHODS

Fifty-nine IBS patients (age 20-65 years; mean, 39.2 years; 31 women, 28 men) with symptoms that fulfilled Rome-II criteria and 21 healthy controls (age 25-58 years; mean, 37.8 years; 11 women, 10 men) were recruited. Participants completed a questionnaire regarding bowel symptoms and psychological distress, and maximal tolerable pressures were evaluated via barostat tests.

RESULTS

Although healthy women appear to have lower perception thresholds than men, significant gender differences in pain sensitivity were not detected (P > 0.05). In addition, female patients with IBS also exhibited no enhanced colorectal perception, as compared with male IBS patients (P > 0.05).

CONCLUSIONS

No gender differences in visceral perception were determined to exist between the healthy controls and the IBS patients. Therefore, the increased prevalence of IBS in women may be related to another set of pathophysiological factors, and not to gender-related differences in visceroperception.

New directions in brain imaging research in functional gastrointestinal disorders

Functional brain imaging has greatly enhanced the ability to investigate brain-gut interactions and to assess the central nervous system role on visceral pain perception. The results of studies using brain imaging in irritable bowel syndrome (IBS) have demonstrated differences in brain activation between patients with IBS and healthy controls. In addition, the more recent studies are starting to shed light on pathophysiological mechanisms that underlie the generation of functional gastrointestinal (GI) symptoms as well as the response to treatment. These studies highlight the potential of functional brain imaging to become an important and exciting investigative tool in research of functional GI disorders. However, the multifactorial, multideterminant nature of these disorders, the current limitations in the understanding of the pathophysiology of the disorders, and the heterogeneous patient population make brain imaging research in this field difficult and require caution in the interpretation of the data. The continued development of brain imaging techniques provides not only exciting opportunities but also significant challenges to the field. This article focuses on brain imaging research in functional GI disorders. It describes some of the recent developments in the use of brain imaging in research of the brain-gut axis and provides an overview of the current data.

Functional gastrointestinal disorders and mast cells: implications for therapy

The pathophysiology of functional gastrointestinal disorders is poorly understood. Accepted common mechanisms include psychosocial factors, abnormal gastrointestinal motility and disturbed visceral sensory perception, but the underlying causes remain unclear. Mast cells (MCs) are immunocytes widely distributed throughout the gastrointestinal tract. Several stimuli (e.g. allergens, neuropeptides and stress) lead to MC activation with consequent mediator release (e.g. histamine, tryptase and prostanoids). The MC mediators interact with nerves supplying the gut leading to altered gut physiology and increased sensory perception. The intestinal mucosa of irritable bowel syndrome patients contains on average an increased number of MCs. These cells release an increased amount of mediators in close vicinity to mucosal innervation. The MC activation and their close proximity to nerve fibres is correlated with the severity of perceived abdominal painful sensations. These data provide a strong basis for considering MCs as important participants in visceral hypersensitivity and pain perception in irritable bowel syndrome. Inhibition of MC function may ameliorate irritable bowel symptoms. Novel drugs with an increased potential in the control of MC function (e.g., anti-IgE antibodies, the intracellular protein tyrosine kinase inhibitor Syk) and mediator release (e.g., second generation antihistamines, proteinase-activated receptor antagonists) may be useful pharmacological tools for these common disorders.

The role of gender and biological sex in irritable bowel syndrome

Irritable bowel syndrome (IBS), which is characterized by abdominal pain or discomfort that is associated with altered bowel function (diarrhea, constipation, or alteration between the two), is one of several gastrointestinal motility disorders. IBS affects up to one in five North Americans, mostly women. The reason(s) this disorder is reported more often by women than men, and the role of gender and biological sex in the prevalence, pathophysiology, symptom presentation, impact on quality of life, diagnosis, and response to treatment, are poorly understood. The purpose of this article is to review the evidence surrounding the roles of gender and biological sex in IBS.

Cow milk is not responsible for most gastrointestinal immune-like syndromes--evidence from a population-based study

BACKGROUND

Gastrointestinal hypersensitivity to cow milk (CM) may be more common among school-aged children and young adults than previously thought.

OBJECTIVE

The objective was to study various gastrointestinal complaints and the immunologic mechanisms associated with food-related, especially CM-related, gastrointestinal disorders in young adults.

DESIGN

Of 827 subjects aged 16-21 y who completed a questionnaire on food-related gastrointestinal symptoms, 49 symptomatic subjects agreed to a clinical examination, including an interview, blood tests, a lactose-maldigestion test, a blinded CM challenge and, in severely symptomatic subjects (n = 12), an endoscopic examination. Twenty-nine subjects served as controls.

RESULTS

Approximately 10% of the subjects reported having major gastrointestinal symptoms, mainly food-related (n = 70 of 86), during the preceding year. Specific organic disease was found in 2 symptomatic subjects: 1 case of celiac disease and 1 of colitis. The result of the lactose-maldigestion test was positive in 16 of the remaining 47 symptomatic subjects, but only 4 carried the C/C(-13910) genotype for adult-type hypolactasia. The symptomatic subjects had restricted their consumption of certain foods, particularly CM. However, in a blinded challenge, CM-induced symptoms were rare. The symptomatic subjects had higher plasma soluble intercellular adhesion molecule 1 (P = 0.007) and lower granzyme A (P = 0.001) concentrations than did the control subjects. Duodenal biopsy samples tended to have higher intraepithelial CD3(+) cell counts (P = 0.065) and a higher expression of transforming growth factor beta (P = 0.073) and interleukin 12p35 messenger RNA (P = 0.075) than did the control subjects.

CONCLUSIONS

In an unselected cohort of young adults, 8% reported food-related gastrointestinal symptoms. The finding of immunologic activity implied the existence of a food-related gastrointestinal syndrome but not one induced by CM.

Estrogen receptor-alpha mediates estradiol attenuation of ATP-induced Ca2+ signaling in mouse dorsal root ganglion neurons

A mechanism underlying gender-related differences in pain perception may be estrogen modulation of nociceptive signaling in the peripheral nervous system. In rat, dorsal root ganglion (DRG) neurons express estrogen receptors (ERs) and estrogen rapidly attenuates ATP-induced Ca2+ signaling. To determine which estrogen receptor mediates rapid actions of estrogen, we showed ERalpha and ERbeta expression in DRG neurons from wild-type (WT) female mice by RT-PCR. To study whether ERalpha or ERbeta mediates this response, we compared estradiol action mediating Ca2+ signaling in DRG neurons from WT, ERalpha knockout (ERalphaKO), and ERbetaKO mice in vitro. ATP, an algesic agent, induced [Ca2+]i transients in 48% of small DRG neurons from WT mice. 17beta-Estradiol (E2) inhibited ATP-induced intracellular Ca2+ concentration ([Ca2+]i) with an IC50 of 27 nM. The effect of E2 was rapid (5-min exposure) and stereo specific; 17alpha-estradiol had no effect. E2 action was blocked by the ER antagonist ICI 182,780 (1 microM) in WT mouse. Estradiol coupled to bovine serum albumin (E-6-BSA), which does not penetrate the plasma membrane, had the same effect as E2 did, suggesting that a membrane-associated ER mediated the response. In DRG neurons from ERbetaKO mice, E2 attenuated the ATP-induced [Ca2+]i flux as it did in WT mice, but in DRG neurons from ERalphaKO mice, E2 failed to inhibit the ATP-induced [Ca2+]i increase. These results show that mouse DRG neurons express ERs and the rapid attenuation of ATP-induced [Ca2+]i signaling is mediated by membrane-associated ERalpha.

Performance, tolerability, and symptoms related to prolonged pH monitoring using the Bravo system in Mexico

BACKGROUND

The traditional system for esophageal 24-h pH monitoring requires transnasal introduction of the catheter with pH sensors; this technique produces discomfort, inconvenience, and interference with daily activity. Recently, a catheter-free pH monitoring system (Bravo) has been proposed as an alternative and promising method for 24-h pH.

AIM

To evaluate performance, tolerability, and symptoms related to this new technology in our population.

METHODS

Consecutive patients with gastroesophageal reflux disease (GERD) with indication for 24-h pH were included. pH Bravo capsule was placed 6 cm above the squamocolumnar junction using endoscopic measurement. Symptoms associated were evaluated daily in a personal diary until 7 days after the capsule attachment. Severity of symptoms was assessed by a 5-point Likert scale. Capsule detachment was assessed by chest X-ray.

RESULTS

Eighty-four patients were included. Forty-nine were female (mean age 44 +/- 12 yr). Indications for pH monitoring were: nonresponse to proton pump inhibitor therapy in 38 (45%), preoperative evaluation for anti-reflux surgery in 36 (43%), previous failed transnasal 24-h pH monitoring in 6 (7%), and extra-esophageal manifestations of GERD in 4 (5%). The capsule was successfully attached in 95% of patients. At day 7, capsule detachment occurred spontaneously in all cases. Symptoms related to capsule attachment were: chest pain in 26 (33%), foreign body sensation in 11 (14%), nausea in 5 (6%), and 9 (11%) patients had more than one symptom. Severities of those symptoms were mild, and no patient required removal of the capsule. Women and younger patients had more symptoms related to the procedure (p < 0.05).

CONCLUSIONS

Esophageal pH monitoring with Bravo capsule is a safe, reliable, and tolerable method in patients with GERD.

Sex, gender, and irritable bowel syndrome: making the connections

BACKGROUND

Irritable bowel syndrome (IBS) is a widespread chronic health condition experienced more often by women than by men. The extent to which women outnumber men varies, however, with a narrower sex ratio found in population surveys and the widest in gastroenterology clinics. This suggests that explanations of women's excess risk of this condition likely involve both sex, or biological, differences between men and women as well as gender, or social, differences.

OBJECTIVE

This article reviews research on sex and gender factors in IBS and, in particular, the ways in which these factors affect the risk of IBS, either independently or in synergy.

METHODS

A multidisciplinary literature review of English-language IBS research published between 1966 and 2002 was conducted using a number of electronic databases (ASSIA, MEDLINE, PsycLIT, and SSCI/Web of Knowledge), augmented by manual search of issues not yet entered onto the databases. The key terms sex, gender, women, men, and irritable bowel disease were used to identify articles with potential relevance; titles and abstracts were reviewed and downloaded to a bibliographic referencing system. This approach yielded approximately 450 articles of interest in the subject area.

RESULTS

The literature review highlighted a range of sex- and gender-linked factors in IBS, including hormonal factors, genetic differences, psychosocial factors related to stress, mental well-being, gender roles, and the experience of sexual abuse. In addition, the literature suggests that gender-related factors overlap each other in explanations of IBS among women, and the interactions between these factors and sex-linked biology are not yet fully understood.

CONCLUSION

A complex model is needed-reflecting sex- and gender-linked factors and their interactions-to fully understand how these factors affect variations in risk and outcome between men and women with IBS.

Recognizing and managing patients with irritable bowel syndrome

PURPOSE

To address the diagnosis and clinical management of irritable bowel syndrome (IBS) and provide a discussion of the available serotonergic agents.

DATA SOURCES

Recent studies examining the pathophysiology of IBS.

CONCLUSIONS

Diagnostic testing may be required in the subset of patients with IBS who present with alarm symptoms, or "red flags," suggestive of underlying organic disease. An important role has been suggested for the neurotransmitter serotonin in both gut motility and visceral pain sensitivity.

IMPLICATIONS FOR PRACTICE

A diagnosis of IBS is largely based on symptoms; therefore, effective clinician-patient communication and careful attention to details of patient presentation, history, and physical examination are essential.

Gender difference on the symptoms, health-seeking behaviour, social impact and sleep quality in irritable bowel syndrome: a Rome II-based survey in an apparent healthy adult Chinese population in Taiwan

BACKGROUND

Little is known about the gender effect on irritable bowel syndrome in Asia.

AIM

To assess the gender difference in Chinese subjects with irritable bowel syndrome meeting Rome II criteria.

METHODS

Irritable bowel syndrome was identified from an apparently healthy adult population receiving a routine health maintenance program (n = 2018).

RESULTS

Female gender is not a factor associated with irritable bowel syndrome or irritable bowel syndrome-related health care-seeking behaviour. Female irritable bowel syndrome subjects, irrespective of consulting behaviour for irritable bowel syndrome, are likely to have < 3 bowel movements/week, hard/lumpy stools and abdominal fullness/bloating (P < 0.05). Female irritable bowel syndrome subjects are prone to be absent from school/work with more days of absenteeism, irrespective of consultation status (P < 0.05). Only female irritable bowel syndrome consulters have more absenteeism for their irritable bowel syndrome-related symptoms, reporting more sleep disturbances than their male counterparts (P < 0.001).

CONCLUSIONS

In an apparent healthy adult population in Taiwan, gender difference is present in Rome II defined Chinese subjects with irritable bowel syndrome as regards bowel symptoms, social impact and sleep quality. Female predominance was not found in irritable bowel syndrome subjects and irritable bowel syndrome-related health care-seeking behaviour in the current population. Both irritable bowel syndrome non-consulters and consulters have similar gender difference profiles in presenting symptoms, suggesting that bowel symptoms per se may not be the only factor leading to health care-seeking behaviour. The gender differences in sleep problems were observed solely in irritable bowel syndrome consulter.

Testing the sequential model of pain processing in irritable bowel syndrome: a structural equation modeling analysis

Pain, the cardinal feature of irritable bowel syndrome (IBS), is a multidimensional phenomenon with sensory and affective dimensions. Price's pain processing model was used to delineate four a priori sequentially related stages (pain sensation intensity, immediate pain unpleasantness, long-term suffering, and pain-related behavior). Although prior research with both healthy individuals and somatic pain patients supports the model in general, its applicability to IBS is unclear. Our goal was to extend the scope of the sequential model and test its fundamental tenets using structural equation modeling (SEM) with data obtained from 168 Rome II diagnosed IBS patients (19% male, 81% female). A secondary goal was to assess the relationship between a set of contextual factors associated with IBS (age, gender, trait anxiety) and the four pain stages. Results were consistent with a successive order of pain processing such that the pain sensation directly impacts pain unpleasantness, which, in turn, leads to suffering and illness behaviors. However, contrary to a model with strictly successive stages, pain sensation had independent effects on illness behaviors over and above pain affect. The effect of anxiety on illness behavior was mediated by suffering, while psychopathology directly influenced pain sensation and pain unpleasantness but not later stages. Age was related to pain sensation and illness behaviors but not pain affect. Gender tended to be more strongly associated with more distal pain stages (e.g., pain affect) vis-a-vis its effects on pain sensation. These data are generally supportive of a four-stage pain processing model.

Definition and classification of irritable bowel syndrome: current consensus and controversies

The symptom-based taxonomy of IBS and other functional bowel disorders is based on defined individual symptoms and the co-occurrence of certain symptoms in individuals. Wording of survey questions to accurately reflect the symptoms can be difficult in English, but accomplishing it for non-English-speakers, especially residents of non-Western societies, is an even greater challenge that needs more attention. The potential for misdiagnosis and inappropriate management, including unnecessary surgery, under-scores the need for wider knowledge of typical IBS symptoms by physicians and the collaboration of primary and specialist physicians in patient care. Even though the evolving symptom classification is as evidence-based as its designers can make it, some arbitrariness is inevitable. Population prevalence rates vary widely, depending on diagnostic criteria and other factors, and further work is needed to determine which individuals detected in surveys consider themselves distressed enough to want medical care and why the remaining people do not feel this need. Clearly, more primary care patients should be studied. Physicians should assess clinical trials critically regarding patient recruitment methods and patient features that could influence whether the results are applicable to their patients. The instability of bowel habit subtypes suggests that relatively few patients should expect relief by taking the same motility-active drug regularly for a long time. Long-term, natural history studies of symptoms and health care use are needed. Discoveries of subtle morphologic pathology and disordered physiology are elucidating IBS pathophysiology further, which some experts believe will lead to a more objective, laboratory-based (organic) diagnosis and more effective therapy. The benefit patients will obtain from supplementing a traditional symptom-based, biopsychosocial approach with such findings remains to be determined. The symptom criteria have had important roles in epidemiological studies and characterizing subjects for clinical trials. Many practitioners, however,do not know the typical symptoms or use the criteria, and investigating how physicians diagnose IBS has received scanty attention. It is unknown how many physicians diagnose IBS by exclusion only after extensively testing patients with typical symptoms and no alarm features, but determining this could have important economic and safety implications. There has been little careful validation of the symptom criteria, especially with primary care patients, and no particular criteria are clearly superior for clinical practice,although the Manning and Rome I criteria have been most evaluated and are less restrictive than the Rome II criteria.

Irritable bowel syndrome: a syndrome in evolution

As a group, functional gastrointestinal disorders are the most common gastrointestinal disorder seen by both generalists and specialists. These disorders can be frustrating to both patients and physicians as they are usually chronic in nature and difficult to treat. These disorders are associated with frequent healthcare visits, the scheduling of multiple, expensive diagnostic tests, and the use of both over-the-counter and prescription medications. All of these factors lead to a significant economic burden to society. In addition, functional gastrointestinal disorders are associated with a reduction in quality of life for the patient. Irritable bowel syndrome (IBS) is the most common of the functional gastrointestinal disorders. This syndrome has been the focus of a large number of research studies over the past two decades. These studies have resulted in a number of significant changes in our definition of IBS. In addition, these research studies have produced considerable changes in our understanding of the etiology and pathogenesis of IBS. In this section, we will review some of the evolutionary changes that have occurred in IBS. We will discuss how the definition of IBS has changed, consider our evolving strategies to evaluate and diagnose IBS, and finally, provide a brief overview of treatment options for this common disorder.

The effects of the 5-HT3 antagonist, alosetron, on brain serotonin synthesis in patients with irritable bowel syndrome

Serotonin (5-HT) plays an important role in the pathophysiology of irritable bowel syndrome (IBS). Using alpha-[(11)C]methyl-L-tryptophan-positron emission tomography (PET), it was demonstrated that brain 5-HT synthesis is increased in patients with IBS, in a gender-specific manner. The aims of the study were to evaluate the effects of alosetron on brain 5-HT synthesis in patients with IBS. Six male and five female non-constipation-predominant IBS patients were enrolled. The subjects received alosetron or a placebo for 14 days, separated by a 2-week washout period. On day 14, rectal distensions commenced just prior to the PET scan (which was performed for 80 min), and continued for 20-min periods. The functional images were analysed with SPM99. Alosetron vs placebo treatments, in a randomized, double-blinded, crossover manner, were studied. 5-HT synthesis was greater in several regions in the males than in the females during the alosetron treatment, whereas there was no region in which the females had greater synthesis. There were significant gender-treatment interactions of synthesis in the cingulate gyrus, caudate nucleus, globus pallidus, and cerebellum. The gender differences in the effect of alosetron on brain 5-HT synthesis may be related to the gender differences in the efficacy of alosetron.

Systematic review: the influence of geography and ethnicity in irritable bowel syndrome

BACKGROUND

Irritable bowel syndrome has been said to be less common in developing countries compared with western populations. In some case series of irritable bowel syndrome from the Indian subcontinent and Africa, the female predominance typical of western patients did not occur.

AIM AND METHODS

A systematic review was performed on Medline, of community prevalence studies of irritable bowel syndrome, chronic constipation and chronic diarrhoea using standardized criteria, with special reference to the effect of geography and ethnicity, and the gender distribution in different countries.

RESULTS

There is a wide variation, depending in part on the criteria used and differences in diagnostic practices and health care utilization. No convincing evidence emerged of a difference between east and west. Most series, eastern or western showed a female predominance or no gender difference. Several US studies in communities and specific populations suggest that stool frequency is lower, and the prevalence of constipation higher, among Afro-Caribbean Americans compared with white individuals.

CONCLUSIONS

Community studies in multi-racial populations are a useful way of assessing possible ethnic differences in the frequency of irritable bowel syndrome, chronic constipation and diarrhoea, and would additionally present opportunities to relate any ethnic differences to dietary and other environmental factors.

Bowel habits in hemorrhoid patients and normal subjects

OBJECTIVES

Bleeding, pain, soiling, and prolapse are the classic symptoms in hemorrhoid disease, but the patients sometimes report a variety of other symptoms. Little is known about functional bowel symptoms in patients with hemorrhoids and few studies have previously addressed this subject. The aim of this study was to compare patients with hemorrhoids with a control population regarding functional bowel symptoms and anorectal complaints.

METHODS

One hundred consecutive patients who participated in a randomized study on hemorrhoidectomy completed a validated questionnaire on bowel and anorectal functional symptoms. Two hundred age- and gender-matched population based control subjects, and 100 gender-matched consecutive patients undergoing an orthopedic procedure served as two control groups, and completed the same questionnaire.

RESULTS

Bowel frequency was the same in all three groups, but only 37% of the patients described their bowel movements as normal, compared to 55 and 67% of the controls (p < 0.001). Up to 37% of the patients reported bloating, compared to 18 and 26% in the control groups. Abdominal pain associated with bowel evacuation was experienced by 34% of the patients but in 3 and 5% of the controls (p < 0.001). Excessive straining, feeling of incomplete evacuation, and repeated toilet visits were significantly more usual in the patients. Reduced feeling of well being and disturbed social life caused by bowel symptoms was often reported by patients but rarely in the control groups.

CONCLUSIONS

Beside hemorrhoidal symptoms, many patients with Grade 3-4 hemorrhoids have concomitant functional bowel symptoms, possibly associated with the irritable bowel syndrome. This knowledge might be important while selecting therapy for patients with hemorrhoids.

A dose-ranging, phase II study of the efficacy and safety of alosetron in men with diarrhea-predominant IBS

BACKGROUND

A randomized, double blind, placebo-controlled dose-ranging study was conducted to assess the efficacy of alosetron in men with diarrhea-predominant irritable bowel syndrome (IBS).

METHODS

Six hundred and sixty-two men were randomized to treatment with alosetron 0.5, 1.0, 2.0, 4.0 mg, or placebo twice daily for 12 wk, followed by a 4-wk posttreatment period. Adequate relief of IBS pain and discomfort during week 5-12 of the treatment phase was the primary endpoint; secondary endpoints included bowel urgency, stool frequency, and consistency, incomplete evacuation, bloating, and abdominal pain or discomfort.

RESULTS

Subjects ranked urgency and abdominal pain as their most bothersome IBS symptoms. The average rate of adequate relief during week 5-12 was significantly higher in the alosetron 1.0 mg twice-daily group compared to placebo (53%vs 40%, p= 0.04), and all doses of alosetron significantly reduced stool consistency scores (p < 0.001) indicating firmer stools. No significant effects of alosetron were seen with regard to urgency, number of bowel movements, bloating, and incomplete evacuation. Constipation was the most common adverse event and occurred in a dose-related manner among subjects receiving alosetron, 9% (0.5 mg twice daily), 15% (1.0 mg twice daily), 11% (2.0 mg twice daily), and 21% (4.0 mg twice daily). No serious adverse events of constipation were reported. One subject in the 0.5 mg twice-daily group had an episode of rectal bleeding suggestive of a possible diagnosis of ischemic colitis.

CONCLUSIONS

Alosetron 1 mg twice daily provided adequate relief of IBS pain and discomfort, and improved stool consistency in men with diarrhea-predominant IBS.

Sex-based differences in gastrointestinal pain

Recent interest has focused on sex-related differences in irritable bowel syndrome (IBS) physiology and treatment responsiveness to novel pharmacologic therapies. Similar to a variety of other chronic pain conditions and certain affective disorders, IBS is more prevalent amongst women, both in population-based studies as well as in clinic-based surveys. Non-painful gastrointestinal symptoms, constipation and somatic discomfort are more commonly reported by female IBS patients. While perceptual differences to rectosigmoid stimulation are only observed following repeated noxious stimulation of the gut, sex-related differences in certain sympathetic nervous system (SNS) responses to rectosigmoid stimulation are consistently seen. Consistent with experimental findings in animals, current evidence is consistent with a pathophysiological model which emphasizes sex-related differences in autonomic and antinociceptive responses to certain visceral stimuli.