Orocecal transit delay in obese patients

A guide to developing population files for physiologically-based pharmacokinetic modeling in the Simcyp Simulator

The Simcyp Simulator is a software platform widely used in the pharmaceutical industry to conduct stochastic physiologically-based pharmacokinetic (PBPK) modeling. This approach has the advantage of combining routinely generated in vitro data on drugs and drug products with knowledge of biology and physiology parameters to predict a priori potential pharmacokinetic changes in absorption, distribution, metabolism, and excretion for populations of interest. Combining such information with pharmacodynamic knowledge of drugs enables planning for potential dosage adjustment when clinical studies are feasible. Although the conduct of dedicated clinical studies in some patient groups (e.g., with hepatic or renal diseases) is part of the regulatory path for drug development, clinical studies for all permutations of covariates potentially affecting pharmacokinetics are impossible to perform. The role of PBPK in filling the latter gap is becoming more appreciated. This tutorial describes the different input parameters required for the creation of a virtual population giving robust predictions of likely changes in pharmacokinetics. It also highlights the considerations needed to qualify the models for such contexts of use. Two case studies showing the step-by-step development and application of population files for obese or morbidly obese patients and individuals with Crohn's disease are provided as the backbone of our tutorial to give some hands-on and real-world examples.

The Influence of Obesity on Small Bowel Capsule Endoscopy

Objective

Intestinal motility may be different in obese and nonobese patients, but this has not been determined. Here, we sought to evaluate the effect of obesity on small bowel capsule endoscopy (SBCE). Patients and Methods. We retrospectively analyzed the cases of the 340 patients who underwent SBCE for small intestinal disease (excluding cases of unobservable total small bowel, small bowel stenosis, and bowel resection) at our hospital during the period January 2014 to December 2020 to extract patient background factors and the bowel transit times of SBCE according to the presence/absence of obesity (defined as a body mass index (BMI) ≥ 25 kg/m²).

Results

The obese group was 54 patients (nonobese, n = 286). The small bowel transit time (SBTT) was significantly shorter in the obese patients compared to the nonobese patients (p = 0.0026), and when we divided the patients by their short/long SBTTs using 216.5 min as the cutoff, we observed significant between-group differences in the patients' age (≥60 years) and in the patients' hospitalization status at the time of the SBCE examination. A multivariate analysis revealed that hospitalized status at the examination is a factor contributing significantly to a long SBTT (OR 0.25, 95% CI: 0.15–0.42, p < 0.0001). An analysis using the outpatient/inpatient conditions showed that obesity was an independent factor in the inpatient status at the SBCE examination with a significant short SBTT (OR 2.91, 95% CI: 1.06–7.97, p = 0.0380). Constipation at the examination was also a factor contributing to a long SBTT (OR 0.26, 95% CI: 0.07–0.99, p = 0.0493).

Conclusion

The SBTT of the SBCE was significantly shorter in the obese patients. This tendency was especially evident in the hospitalized state.

Pathophysiological Commonality Between Irritable Bowel Syndrome and Metabolic Syndrome: Role of Corticotropin-releasing Factor-Toll-like Receptor 4-Proinflammatory Cytokine Signaling

Irritable bowel syndrome (IBS) displays chronic abdominal pain with altered defecation. Most of the patients develop visceral hypersensitivity possibly resulting from impaired gut barrier and altered gut microbiota. We previously demonstrated that colonic hyperpermeability with visceral hypersensitivity in animal IBS models, which is mediated via corticotropin-releasing factor (CRF)-Toll-like receptor 4 (TLR4)-proinflammatory cytokine signaling. CRF impairs gut barrier via TLR4. Leaky gut induces bacterial translocation resulting in dysbiosis, and increases lipopolysaccharide (LPS). Activation of TLR4 by LPS increases the production of proinflammatory cytokines, which activate visceral sensory neurons to induce visceral hypersensitivity. LPS also activates CRF receptors to further increase gut permeability. Metabolic syndrome (MS) is a cluster of cardiovascular risk factors, including insulin resistance, obesity, dyslipidemia, and hypertension, and recently several researchers suggest the possibility that impaired gut barrier and dysbiosis with low-grade systemic inflammation are involved in MS. Moreover, TLR4-proinflammatory cytokine contributes to the development of insulin resistance and obesity. Thus, the existence of pathophysiological commonality between IBS and MS is expected. This review discusses the potential mechanisms of IBS and MS with reference to gut barrier and microbiota, and explores the possibility of existence of pathophysiological link between these diseases with a focus on CRF, TLR4, and proinflammatory cytokine signaling. We also review epidemiological data supporting this possibility, and discuss the potential of therapeutic application of the drugs used for MS to IBS treatment. This notion may pave the way for exploring novel therapeutic approaches for these disorders.

European guideline on indications, performance, and clinical impact of hydrogen and methane breath tests in adult and pediatric patients: European Association for Gastroenterology, Endoscopy and Nutrition, European Society of Neurogastroenterology and Motility, and European Society for Paediatric Gastroenterology Hepatology and Nutrition consensus

INTRODUCTION

Measurement of breath hydrogen (H2 ) and methane (CH4 ) excretion after ingestion of test-carbohydrates is used for different diagnostic purposes. There is a lack of standardization among centers performing these tests and this, together with recent technical developments and evidence from clinical studies, highlight the need for a European guideline.

METHODS

This consensus-based clinical practice guideline defines the clinical indications, performance, and interpretation of H2 -CH4 -breath tests in adult and pediatric patients. A balance between scientific evidence and clinical experience was achieved by a Delphi consensus that involved 44 experts from 18 European countries. Eighty eight statements and recommendations were drafted based on a review of the literature. Consensus (≥80% agreement) was reached for 82. Quality of evidence was evaluated using validated criteria.

RESULTS

The guideline incorporates new insights into the role of symptom assessment to diagnose carbohydrate (e.g., lactose) intolerances and recommends that breath tests for carbohydrate malabsorption require additional validated concurrent symptom evaluation to establish carbohydrate intolerance. Regarding the use of breath tests for the evaluation of oro-cecal transit time and suspected small bowel bacterial overgrowth, this guideline highlights confounding factors associated with the interpretation of H2 -CH4 -breath tests in these indications and recommends approaches to mitigate these issues.

CONCLUSION

This clinical practice guideline should facilitate pan-European harmonization of diagnostic approaches to symptoms and disorders, which are very common in specialist and primary care gastroenterology practice, both in adult and pediatric patients. In addition, it identifies areas of future research needs to clarify diagnostic and therapeutic approaches.

Effect of obesity on gastrointestinal transit, pressure and pH using a wireless motility capsule

BACKGROUND

Despite the increasing prevalence and medical burden of obesity, the understanding of gastrointestinal physiology in obesity is scarce, which hampers drug development.

AIM

To investigate the effect of obesity and food intake on gastrointestinal transit, pressure and pH.

MATERIAL AND METHODS

An exploratory cross-sectional study using a wireless motility capsule (SmartPill©) was performed in 11 participants with obesity and 11 age- and gender-matched participants with normal weight (group) in fasted and fed state (visit). During the first visit, the capsule was ingested after an overnight fast. During a second visit, the capsule was ingested after a nutritional drink to simulate fed state. Linear mixed models were constructed to compare segmental gastrointestinal transit, pressure and pH between groups (obesity or control) and within every group (fasted or fed).

RESULTS

Food intake slowed gastric emptying in both groups (both P < 0.0001), though food-induced gastric contractility was higher in participants with obesity compared to controls (P = 0.02). In the small intestine, a higher contractility (P = 0.001), shorter transit (P = 0.04) and lower median pH (P = 0.002) was observed in participants with obesity compared to controls. No differences were observed for colonic measurements.

CONCLUSION

Obesity has a profound impact on gastrointestinal physiology, which should be taken into account for drug development.

Irritable bowel syndrome: a new therapeutic target when treating obesity?

There is accumulating evidence showing that obesity is due not merely to increased food intake, but could have a more complex pathophysiology possibly originating from the gut. Due to its microbiological, hormonal, and nutritional aspects, the gut could represent a starting point for the treatment of weight excess. Obesity is associated with a change of microbiota composition that not only could increase the calorie extraction from food but also could create a functional derangement resulting in irritable bowel syndrome (IBS). Several mechanisms have been postulated to explain this association, such as specific foods that are poorly absorbed, i.e., carbohydrates and lipids, as well as conditions of psychological stress which could stimulate colonic hypersensitivity giving rise to IBS symptoms. Another factor involved in this link could be the subclinical inflammation typical of obesity, characterized by the release of inflammatory mediators that can irritate intestinal nerve endings. The change of levels of some anorexigenic hormones, as well as the alterations of the gut microbiota with the reduction of the bacteroides/Firmicutes ratio, could also contribute to the pathogenesis of IBS related to obesity. Thus, the aim of this manuscript is to review the current evidence on the association between obesity and IBS while providing physiopathological hypotheses that may explain this link. Further, we will report the effect of weight loss on IBS symptoms, highlighting the importance of an accurate assessment of gut function in obese patients.

Lactulose Breath Testing Can Be a Positive Predictor Before Weight Gain in Participants with Obesity Submitted to Roux-en-Y Gastric Bypass

BACKGROUND

Small intestinal bacterial overgrowth (SIBO) is defined as the colonization of fermentative bacteria in the duodenum and jejunum. The alteration of digestive anatomy promoted by bariatric surgery may be a pre-disposing factor for SIBO. In this context, the prevalence of SIBO in participants undergoing bariatric surgery using Roux-en-Y gastric bypass (BGYR) was evaluated.

METHODS

Participants, both sexes, older than 18 years, were those who (a) had bariatric surgery by the BGYR technique at least 1 year before the data collection and (b) did not use antibiotics recently. The SIBO diagnosis was established through the hydrogen breath test (H₂BT), with intake of lactulose and serial collection of breath samples over 2 h. A test with ≥ 12-point elevation over the basal sample at 60 min after substrate intake was deemed positive.

RESULTS

A total of 18 participants (14 females (77.8%)) were enrolled with a mean age of 50.5 years (range, 23 to 79 years). The interval between surgery and data collection ranged from 5 to 20 years (mean, 11.2 years). The mean preoperative body mass index (BMI) was 44.6 kg/m² (range, 36.7-56.2 kg/m²). The H₂RT with lactulose was positive for SIBO in seven (six female) participants. The participants with negative test measured trough H₂BT with lactulose had a lower mean BMI of 28.69 kg/m², in comparison with the positive group, which presented a mean BMI of 33.04 kg/m² (p value = 0.041).

CONCLUSION

Our data point to a high prevalence of SIBO (38.8%) in patients undergoing BGYR with a value in accordance with the literature. Moreover, the differences in BMI between negative and positive groups by H₂BT with lactulose evidenced a weight gain relapse in participants with SIBO.

Characteristics of Intestinal Myoelectrical and Motor Activities in Diet-Induced Obese Rats: Obesity and Motility

BACKGROUND

Gastrointestinal motility has been reported to be altered in obesity. However, it is unknown whether intestinal myoelectrical activity (IMA) is also changed in obesity.

AIMS

The aim of this study was to characterize intestinal myoelectrical and motility activities in the fasting state, during feeding, and postprandial state after various test meals in diet-induced obese (DIO) rats in comparison with regular rats.

METHODS

IMA was recorded in the fasting, feeding, and postprandial states in DIO and regular rats. Regular laboratory chow, high-fat solid food, and high-fat liquid food were used to test IMA responses to different meals.

RESULTS

(1) The intestinal slow waves in the DIO rats were not different from those in normal rats in the fasting or postprandial state. Neither intestinal transit nor the number of intestinal contractions per minute was altered in DIO rats although gastric emptying was accelerated. (2) Both DIO rats and normal rats showed altered IMA during the first minute of feeding (cephalic stimulation). (3) The intestinal slow waves in both DIO rats and regular rats were impaired slightly but significantly after intake of a high-fat meal.

CONCLUSIONS

Our study demonstrates that intestinal myoelectrical activity is not altered in DIO rats and its postprandial responses to various meals are not altered either. High-fat meals induce intestinal dysrhythmia but do not have a chronic impact on intestinal slow waves in DIO rats.

Gastrointestinal Transit Time, Glucose Homeostasis and Metabolic Health: Modulation by Dietary Fibers

Gastrointestinal transit time may be an important determinant of glucose homeostasis and metabolic health through effects on nutrient absorption and microbial composition, among other mechanisms. Modulation of gastrointestinal transit may be one of the mechanisms underlying the beneficial health effects of dietary fibers. These effects include improved glucose homeostasis and a reduced risk of developing metabolic diseases such as obesity and type 2 diabetes mellitus. In this review, we first discuss the regulation of gastric emptying rate, small intestinal transit and colonic transit as well as their relation to glucose homeostasis and metabolic health. Subsequently, we briefly address the reported health effects of different dietary fibers and discuss to what extent the fiber-induced health benefits may be mediated through modulation of gastrointestinal transit.

Relationship of body weight with gastrointestinal motor and sensory function: studies in anorexia nervosa and obesity

Background

Whether gastrointestinal motor and sensory function is primary cause or secondary effect of abnormal body weight is uncertain. Moreover, studies relating continuous postprandial sensations of satiation to measurable pathology are scarce. This work assessed postprandial gastrointestinal function and concurrent sensations of satiation across a wide range of body weight and after weight change.

Methods

Patients with anorexia nervosa (AN) and obesity (OB) were investigated in reference to normal weight controls (HC). AN were additionally investigated longitudinally. Gastric emptying, antral contractions and oro-cecal transit after ingestion of a solid meal were investigated by MRI and ¹³C-lactose-ureide breath test. The dependency of self-reported sensations of satiation on the varying degree of stomach filling during gastric emptying was compared between groups.

Results

24 AN (BMI 14.4 (11.9–16.0) kg/m²), 16 OB (34.9 (29.6–41.5) kg/m²) and 20 HC (21.9 (18.9–24.9) kg/m²) were studied. Gastric half-emptying time (t₅₀) was slower in AN than HC (p = 0.016) and OB (p = 0.007), and a negative association between t₅₀ and BMI was observed between BMI 12 and 25 kg/m² (p = 0.007). Antral contractions and oro-cecal transit were not different. For any given gastric content volume, self-reported postprandial fullness was greater in AN than in HC or OB (p < 0.001). After weight rehabilitation, t₅₀ in AN tended to become shorter (p = 0.09) and postprandial fullness was less marked (p < 0.01).

Conclusions

A relationship between body weight and gastric emptying as well as self-reported feelings of satiation is present. AN have slower gastric emptying and heightened visceral perception compared to HC and OB. Longitudinal follow-up after weight rehabilitation in AN suggests these abnormalities are not a primary feature, but secondary to other factors that determine abnormal body weight.

Trial registration

Registered July 20, 2009 at ClinicalTrials.gov (NCT00946816).

Electronic supplementary material

The online version of this article (doi:10.1186/s12876-016-0560-y) contains supplementary material, which is available to authorized users.

Sex-related differences in small intestinal transit and serotonin dynamics in high-fat-diet-induced obesity in mice

Obesity alters gastrointestinal (GI) motility and 5-HT signalling. Altered 5-HT signalling disrupts control of GI motility. Levels of extracellular 5-HT depend on enterochromaffin (EC) cell release and serotonin transporter (SERT) uptake. We assessed GI transit and 5-HT signalling in the jejunum of normal and obese mice. Male and female mice were fed a control diet (CD; 10% of kilocalories as fat) or a high-fat diet (HFD; 60% of kilocalories as fat). Gastrointestinal transit was increased in male HFD-fed and female CD-fed compared with male CD-fed mice. The 5-HT3 receptor blocker, alosetron, increased gastric emptying in male CD-fed mice, but decreased transit in female CD-fed mice. The 5-HT-induced jejunal longitudinal muscle contractions in vitro were similar in all mice. In contrast to male CD-fed mice, 5-HT uptake (measured using continuous amperometry in vitro) in male HFD-fed mice was fluoxetine insensitive, yet sensitive to cocaine and the dopamine transporter (DAT) blocker GBR 12909. Immunoreactivity for DAT was present in the mucosa, and protein levels were greater in male HFD-fed compared with CD-fed mice. Extracellular 5-HT and mucosal 5-hydroxyindolacetic acid (5-HT metabolite) were similar in male HFD-fed compared with CD-fed mice. 5-Hydroxytryptamine uptake was fluoxetine sensitive in all females. Greater SERT protein, decreased extracellular 5-HT and greater mucosal 5-hydroxyindolacetic acid were observed in female HFD-fed compared with CD-fed mice. Mucosal 5-HT and EC cell numbers were similar in CD-fed and HFD-fed mice of both sexes; female 5-HT and EC cell numbers were increased compared with males. The HFD did not alter plasma sex hormone levels in any mice. Overall, obesity alters GI transit and 5-HT signalling in a sex-dependent manner.

Disturbed intestinal nitrogen homeostasis in a mouse model of high-fat diet-induced obesity and glucose intolerance

The oligopeptide transporter peptide cotransporter-1 Slc15a1 (PEPT1) plays a major role in the regulation of nitrogen supply, since it is responsible for 70% of the dietary nitrogen absorption. Previous studies demonstrated that PEPT1 expression and function in jejunum are reduced in diabetes and obesity, suggesting a nitrogen malabsorption from the diet. Surprisingly, we reported here a decrease in gut nitrogen excretion in high-fat diet (HFD)-fed mice and further investigated the mechanisms that could explain this apparent contradiction. Upon HFD, mice exhibited an increased concentration of free amino acids (AAs) in the portal vein (60%) along with a selective increase in the expression of two AA transporters (Slc6a20a, Slc36a1), pointing to a specific and adaptive absorption of some AAs. A delayed transit time (+40%) and an increased intestinal permeability (+80%) also contribute to the increase in nitrogen absorption. Besides, HFD mice exhibited a 2.2-fold decrease in fecal DNA resulting from a reduction in nitrogen catabolism from cell desquamation and/or in the intestinal microbiota. Indeed, major quantitative (2.5-fold reduction) and qualitative alterations of intestinal microbiota were observed in feces of HFD mice. Collectively, our results strongly suggest that both increased AA transporters, intestinal permeability and transit time, and changes in gut microbiota are involved in the increased circulating AA levels. Modifications in nitrogen homeostasis provide a new insight in HFD-induced obesity and glucose intolerance; however, whether these modifications are beneficial or detrimental for the HFD-associated metabolic complications remains an open issue.

Delayed small intestinal transit in patients with long-standing type 1 diabetes mellitus: investigation of the relationships with clinical features, gastric emptying, psychological distress, and nutritional parameters

BACKGROUND

Studies on small intestinal transit in type 1 diabetes mellitus have reported contradictory results. This study assessed the orocecal transit time (OCTT) in a group of patients with type 1 diabetes mellitus and its relationships with gastrointestinal symptoms, glycemic control, chronic complications of diabetes, anthropometric indices, gastric emptying, small intestinal bacterial overgrowth (SIBO), and psychological distress.

SUBJECTS AND METHODS

Twenty-eight patients with long-standing (>10 years) type 1 diabetes mellitus (22 women, six men; mean age, 39 ± 9 years) participated in the study. The lactulose hydrogen breath test was used to determine OCTT and the occurrence of SIBO. The presence of anxiety and depression was assessed by the Hospital Anxiety and Depression scale. Gastric emptying was measured by scintigraphy. Anthropometric indices included body mass index, percentage body fat, midarm circumference, and arm muscle area.

RESULTS

There was a statistically significant increase in OCTT values in diabetes patients (79 ± 41 min) in comparison with controls (54 ± 17 min) (P=0.01). Individual analysis showed that OCTT was above the upper limit (mean+2 SD) in 30.8% of patients. All anthropometric parameters were significantly decreased (P<0.05) in patients with prolonged OCTT in comparison with those with normal OCTT. In contrast, there was no statistically significant association between prolonged OCTT and gastrointestinal symptoms, peripheral neuropathy, diabetic retinopathy, glycated hemoglobin, delayed gastric emptying, SIBO, anxiety, or depression.

CONCLUSIONS

Small bowel transit may be delayed in about one-third of patients with long-standing type 1 diabetes mellitus. This abnormality seems to have a negative effect on nutritional status in these patients.

Recovery of upper gastrointestinal bowel movement after rectosigmoid cancer surgery: a pilot transit analysis

Postoperative gastrointestinal bowel transit right after colorectal resection has not yet been clarified. Thirty patients with rectosigmoid cancer were treated in this pilot study. The nasogastric tube was removed on the first postoperative day. One Sitzmarks capsule was given to each patient on the second postoperative day. Abdominal X-rays were taken at 3, 6, 8, 24, 48, and 72 hours after capsule intake. Distribution of the remaining Sitzmarks capsules were counted on X-ray films to clarify postoperative gastrointestinal movement after bowel resection. All Sitzmarks capsules were observed in the stomach at 3 and 6 hours after capsule intake. At 8 hours (second postoperative day), the Sitzmarks capsules were distributed from the stomach to the small intestine. Sitzmarks capsules were distributed in the right side colon at 24 hours (third postoperative day) after intake. Although the main distribution was still in the right side colon, several patients had evacuations accompanied by the disappearance of the Sitzmarks capsules. In 50% of the patients, it took approximately 72 hours (fifth postoperative day) for the first defecation after intake of the capsules. However, the Sitzmarks capsules remained mainly in the right side colon. Eight hours after intake, the majority of the Sitzmarks capsules shifted to the small intestine. Therefore, medication or feeding should be safely possible starting on the second postoperative day. There was no particular impact of bowel resection on upper gastrointestinal transit in patients with rectosigmoid cancer.

Slower gastric emptying in high-fat diet induced obese rats is associated with attenuated plasma ghrelin and elevated plasma leptin and cholecystokinin concentrations

Gastrointestinal (GI) motility and gut hormones have been considered to be involved in the development and maintenance of obesity. Our aim was to assess the relationships between gastric emptying (GE), GI transit and gut hormones and leptin concentrations in diet-induced obese rat model. Male 6-week-old Sprague-Dawley rats were fed with a high-fat (HF) diet for 8weeks to generate diet-induced obesity (DIO) and diet resistant (DR) rats. GE, GI transit and plasma ghrelin, cholecystokinin (CCK), PYY and leptin concentrations were determined in DIO, DR and control (CON) rats. The DIO rats had slower GE, higher plasma leptin and CCK concentrations, and lower plasma ghrelin concentration compared with CON and DR rats. GE was correlated with plasma ghrelin (r=0.402, P=0.028), CCK (r=-0.518, P=0.003) and leptin concentration (r=-0.514, P=0.004). The slower GE, which can be considered as an adaptive response aimed at HF diet induced obesity, may be mediated by changes of plasma ghrelin, CCK and leptin concentrations.

Small intestinal bacterial overgrowth in nonalcoholic steatohepatitis: association with toll-like receptor 4 expression and plasma levels of interleukin 8

BACKGROUND

Experimental and clinical studies suggest an association between small intestinal bacterial overgrowth (SIBO) and nonalcoholic steatohepatitis (NASH). Liver injury and fibrosis could be related to exposure to bacterial products of intestinal origin and, most notably, endotoxin, including lipopolysaccharide (LPS).

AIM

To compare the prevalence of SIBO and its relationships to LPS receptor levels and systemic cytokines in NASH patients and healthy control subjects.

METHODS

Eighteen NASH patients (eight males) and 16 age-matched and gender-matched healthy volunteers were studied. SIBO was assessed by the lactulose breath hydrogen test (LHBT), plasma lipopolysaccharide binding protein (LBP) levels by ELISA, and expression (as a percentage) of TLR-2 and 4 on CD14-positive cells by flow cytometry. Pro-inflammatory cytokines (IL-1β, IL-6, IL-8, and TNF-α) were measured in plasma.

RESULTS

SIBO was more common in NASH patients than control subjects (77.78% vs. 31.25%; P < 0.0001). LBP levels and TLR-2 expression were similar in both groups, TLR-4/MD-2 expression on CD14 positive cells was higher among NASH patients: expression, mean ± SEM, NASH vs. control: 20.95 ± 2.91% vs. 12.73 ± 2.29%, P < 0.05. Among the examined cytokines, only IL-8 levels were significantly higher in patients than control (P = 0.04) and correlated positively with TLR-4 expression (r = 0.5123, P = 0.036).

CONCLUSION

NASH patients have a higher prevalence of small intestinal bacterial overgrowth which is associated with enhanced expression of TLR-4 and release of IL-8. SIBO may have an important role in NASH through interactions with TLR-4 and induction of the pro-inflammatory cytokine, IL-8.

Small intestinal clustered contractions and bacterial overgrowth: a frequent finding in obese patients

BACKGROUND

Small intestinal bacterial overgrowth (SIBO) has been observed in several disorders of the gastrointestinal tract. Studies have shown abnormalities of motor function in obese patients, and there is indirect evidence suggesting that SIBO is present in them.

AIMS

To study small intestinal motility and the prevalence of SIBO in obese patients and to determine whether there was any relationship between both parameters.

METHODS

Thirty-nine patients scheduled for bariatric surgery were subjected to hydrogen breath test with lactulose and to a stationary small intestinal motility study with perfused catheters.

RESULTS

SIBO was observed in 41% of obese patients and was not related to body mass index. Small intestinal manometry showed a marked increase of clustered contractions in obese patients with SIBO compared to obese subjects without SIBO, whereas all the other parameters of fasting cyclic activity were not different.

CONCLUSIONS

SIBO was a frequent finding in obese patients and was associated with an increased pattern of clustered contractions, which was not observed in absence of SIBO.

The role of the gut microbiota in nonalcoholic fatty liver disease

Important metabolic functions have been identified for the gut microbiota in health and disease. Several lines of evidence suggest a role for the gut microbiota in both the etiology of nonalcoholic fatty liver disease (NAFLD) and progression to its more advanced state, nonalcoholic steatohepatitis (NASH). Both NAFLD and NASH are strongly linked to obesity, type 2 diabetes mellitus and the metabolic syndrome and, accordingly, have become common worldwide problems. Small intestinal bacterial overgrowth of Gram-negative organisms could promote insulin resistance, increase endogenous ethanol production and induce choline deficiency, all factors implicated in NAFLD. Among the potential mediators of this association, lipopolysaccharide (a component of Gram-negative bacterial cell walls) exerts relevant metabolic and proinflammatory effects. Although the best evidence to support a role for the gut microbiota in NAFLD and NASH comes largely from animal models, data from studies in humans (albeit at times contradictory) is accumulating and could lead to new therapeutic avenues for these highly prevalent conditions.

Conference on "Multidisciplinary approaches to nutritional problems". Postgraduate Symposium. The role of fat in gastric emptying and satiety: acute and chronic effects

Dietary fat is an important factor in the aetiology of obesity and the metabolic syndrome. It has been widely debated whether gastric emptying (GE) is altered in obesity. GE times have been reported as both longer and shorter in obese individuals compared with matched lean individuals. However, the general consensus is that GE is accelerated and satiety is lower in obesity. Research has implicated a high-fat (HF) diet in these findings. A single HF meal has a longer GE time than a low-fat meal and can even delay GE of the subsequent meal. However, an HF diet has shown different effects. Feeding a HF diet adapts gastrointestinal function to reduce GE times in comparison with a low-fat diet. Increased GE may lead to decreased satiety and faster onset of subsequent eating episodes. Further results have suggested that consuming an HF diet for 14 d increases the GE rate of HF food but not low-fat food. Consuming HF diets for 2 weeks has also been shown to increase food intake. Decreased satiation following an HF diet may cause increased food intake and a positive energy balance, potentially resulting in a gradual increase in adiposity. Recent results have suggested that gastrointestinal transit is accelerated following only 3 d on a HF diet. The variable GE times reported in obesity may be associated with interactions between the HF diet and obesity and not simply the obese state.

Influences of fat restriction and lipase inhibition on gastric emptying in obesity

OBJECTIVE

Accelerated gastric emptying of solids may play a role in the pathogenesis of obesity. Orlistat, a potent lipase inhibitor, induces fat malabsorption and body weight loss but might accelerate gastric emptying as a result of suppressed CCK release. The aim was to investigate the role of fat restriction and lipase inhibition in CCK release and gastric emptying.

SUBJECTS

A total of 28 patients (three male (M)/25 female (F); mean (s.d.) BMI 37.4(3.9) kg/m2) entering a randomized, double-blind, placebo-controlled study.

MEASUREMENTS

CCK release and gastric emptying by scintigraphy at the start (T0), after 1 month of an energy- and fat-restricted diet and placebo (T1), and after 1 month (T2) and 1 year (T3) of randomization to placebo or 120 mg orlistat three times a day.

RESULTS

One month of dieting and a weight loss of 2.3 kg (2.1% of initial weight) did not affect gastric emptying of liquids and solids. Basal and meal-stimulated CCK levels remained unaltered. Placebo-treated subjects who continued the diet for 1 month demonstrated a borderline significant suppressed CCK secretion and a weight loss of 1.2 kg (1.0%) without an effect on gastric emptying. After 1 year, the CCK secretion recovered to or beyond values at the start. A significantly slower emptying of solids (17.6 (T3) versus 25.9 (T1)%/h) and a weight loss of 10.4 kg (9.9%) was observed. Subjects on 120 mg orlistat lost 2.5 kg (2.5%) after 1 month, and 9.8 kg (9.9%) after 1 year. Basal and postprandial CCK release decreased significantly after the first month of orlistat treatment but normalized after 1 year. Diet and lipase inhibition did not have any influence on gastric emptying.

CONCLUSION

Energy and fat restriction of 1 month did not alter gastric emptying in the whole group. Continuation of the diet for 1 year resulted in a delayed gastric emptying of solids. Lipase inhibition did not result in a sustained depressed CCK release and the anticipated acceleration of gastric emptying did not occur.

Increased orocecal transit time in patients with nonalcoholic fatty liver disease

Intestinal bacterial overgrowth (IBO) has been suggested to play a pathogenic role in patients with nonalcoholic fatty liver disease (NAFLD). Delayed intestinal transit may contribute to IBO development. Ten nondiabetic patients with NAFLD and abnormal liver enzymes were recruited. Ten healthy individuals, matched by sex, age, and body mass index, were used as controls. Orocecal transit time (OCTT) was measured by the lactulose breath test. Anti-endotoxin core antibodies (EndoCAb) were determined. The effect of oral norfloxacin (400 mg BID during 2 weeks) on liver enzymes, lactulose breath test, and EndoCAb was also studied. NAFLD patients had higher basal breathed H2 and prolonged OCTT compared to controls (127 +/- 61 vs. 57 +/- 23 min, respectively; P = 0.0037). EndoCAb titers were similar in NAFLD patients and controls. Norfloxacin administration had no effect on ALT levels, lactulose breath test, or EndoCAb titers in patients with NAFLD. The present data show evidence of deranged intestinal motility in nondiabetic patients with NAFLD and support the hypothesis that NAFLD could be linked to endotoxin-induced liver damage of intestinal origin.

Alterations of gastrointestinal motility in obesity

All nutrients are absorbed in the gastrointestinal (GI) system, and GI motility plays a very critical role in the consumption of foods, digestion, and absorption of nutrients. Various segments of the GI tract (esophagus, stomach, and intestines) coordinate in a complex yet precise way to control the process of food consumption, digestion, and absorption of nutrients. GI motility not only regulates the rates at which nutrients are processed and absorbed in the gut but also participates in the control of appetite and satiety. Altered GI motility has been associated with various disease conditions (gastroparesis, etc.) and has been frequently observed in obese patients. The significance of these GI motility alterations in obesity is not fully understood, but they have been considered as potential contributing factors in the development and maintenance of obesity and changed eating behavior. Therapies aimed at regulating GI motility are being actively explored and applied clinically for the management of obese patients. To better understand the pathophysiology of obesity, we systematically reviewed GI motility changes observed in obese conditions. The relationship and pathological significance of these findings, as well as the potential therapies by modification of GI motility, are also discussed.

Effects of gender and menstrual cycle on colonic transit time in healthy subjects

BACKGROUND

Measuring colonic transit time (CTT) by the radio-opaque marker method is simple, widely available and important for the diagnosis of slow transit constipation. Moreover, the effects of gender and menstrual cycle on CTT remain controversial. Thus, in this study, we examined the effects of gender and menstrual cycle on CTT in healthy subjects.

METHODS

We measured CTT in 42 healthy subjects (21M, 21F) by using a radio-opaque marker, Kolomark. Two simple abdominal radiographs were taken on the 4th and 7th days. Average daily intake of dietary fiber and menstrual history were surveyed.

RESULTS

The mean CTT of the 42 healthy subjects was 26.5 +/- 19.4 hours. The mean CTT was not significantly different between the male and female subjects (22.3 +/- 16.1 h vs. 30.1 +/- 21.4 h, p > 0.05). However, the mean CTT of 11 female subjects in the luteal phase was significantly longer than that of 10 female subjects in the follicular phase (40.9 +/- 19.0 h vs. 20.6 +/- 19.2 h, p < 0.05). Serum progesterone level, age, BMI, and the average daily intake of dietary fiber did not correlate with CTT.

CONCLUSION

The effects of the menstrual cycle should be considered in interpreting CTT in young women.

Effect of lactulose on carbohydrate metabolism and diabetes mellitus

BACKGROUND

Unabsorbable disaccharides, by reducing transit time and possibly glucose absorption, are expected to affect carbohydrate metabolism.

AIM

To test the effects of a preparation containing fibre and lactulose in the form of biscuits on glucose and insulin levels in obesity.

METHODS

In 10 obese patients glucose and insulin were measured in the fasting state and in response to a meal during two consecutive days on a strictly controlled diet; on one day a total of 11 biscuits (10 g dietary fibre, 2 g raw fibre +8.2 g lactulose) were randomly substituted for an equicaloric part of a diet.

RESULTS

Glucose and insulin in response to breakfast and to lunch were blunted by dietary fibre and lactulose, without any trend towards post-meal hypoglycaemia. Average day-time glucose decreased by 0.53 +/- SD 0.28 mmol/L, and insulin by 74.6 +/- 45.2 pmol/L. Plasma amino acids were higher during supplementation, ruling out malabsorption as a cause of glucose flattening.

CONCLUSION

Because of the rationale of the preparation, good compliance of patients, and significant results in short-term experiments, the association of fibre and lactulose deserves more careful evaluation in long-term clinical studies.

Variability of gastrointestinal transit in healthy women and men

BACKGROUND AND AIMS

Measurements of gastrointestinal transit are made in clinical and research gastroenterology, yet their intrinsic variability is not well characterised. In particular, an influence of hormones on transit has been proposed as the basis for gastrointestinal symptoms that vary with the menstrual cycle. Our aims were to quantify individual differences in transit during the menstrual cycle in healthy women and to compare these with the intrinsic variability in healthy men.

METHODS

On two occasions, whole gut transit was assessed scintigraphically and colonic transit quantified by radio-opaque markers. Thirty two healthy volunteers (12 women, 20 men) were studied, women during the follicular and luteal phases, men twice within a similar four week period. Diets and exercise were standardised prior to and during both studies.

RESULTS

Colonic transit was significantly faster in men, and postlag gastric emptying was also more rapid; other indices of regional transit were not different between the sexes. Total colonic transit time was equally well reflected by the scintigraphic and radio-opaque marker methods. Important intraindividual differences were noted in both sexes. The variances in our samples predicted an 80% chance of detecting (with 95% confidence) a mean effect of menstrual hormones on transit that was in the same range as the intrinsic variation in men.

CONCLUSIONS

Colonic transit was faster in men than in women. Although group means in the two studies were almost identical, single assessments of transit in subjects sometimes exhibited considerable variability, implying broad biological variations. Given this intrinsic variability, the influence of menstrual hormones on gastrointestinal transit must be small and of doubtful clinical significance.

Gastrointestinal motility in obesity

Gastrointestinal motility is closely linked to the rate at which nutrients become systemically available. Regulation of gastric emptying represents the most important brake against delivery of nutrients to the intestine in excess of digestive and absorptive capacity. In man, gastric emptying is slowed in proportion to the energy density of the meal, which will level out the rate of energy delivery to the duodenum. Studies suggest a more rapid gastric emptying in obesity, although the opposite has been reported in some experimental settings. Moreover, gastric volume is larger in obese individuals and appropriate satiety signals are not triggered in response to gastric distension. Postprandial intestinal transit time in obesity is similar to that in normal-weight subjects, however, despite this fact, intestinal absorption of nutrients is more efficient in obesity. Several regulatory mechanisms for gastrointestinal motility, such as the autonomous and enteric nervous systems and gastrointestinal regulatory peptides, are also of importance for feeding behaviour and metabolism. Dysfunction of the autonomous nervous system has been observed, the sensitivity to cholecystokinin is decreased in obesity, and plasma concentrations of somatostatin and neurotensin are lower than in normal-weight subjects. These changes in regulatory mechanisms favour rapid gastrointestinal transit of ingested nutrients and promote rapid intestinal absorption in obesity and decreased satiety in response to ingested food. It is presently not known whether the observed changes in gastrointestinal motility in obesity represent a primary feature linked to the pathogenesis of such disease.

Effect of cafeteria diet on alpha-MG intestinal absorption in rats

The effect of a cafeteria diet (a hypercaloric diet) on the accumulative ability of the mediated and non-mediated small intestine transport of alpha-methyl-D-glucoside (alpha-MG) in developing female Wistar rats was studied using everted intestinal slices. Cafeteria diet increased intestinal active transport and decreased intestinal passive diffusion of alpha-MG in 30-day-old rats. No differences in alpha-MG intestinal absorption were found in cafeteria vs control rats after the development of obesity in cafeteria diet fed rats. A link between gastrointestinal functions and the development of obesity induced by cafeteria diet is suggested.

Gastrointestinal disturbances with obesity

Steatosis and steatohepatitis are associated with obesity. Despite florid histological changes, patients with non-alcoholic steatohepatitis generally remain asymptomatic, and it usually runs a relatively benign course. An elevated insulin level may be important in the pathogenesis. There is a marked regression of fatty changes after weight reduction. In obese subjects the risk of developing gallstones is increased due to an increased saturation of gallbladder bile with cholesterol and possible gallbladder stasis. During weight reduction with very low calorie diets the incidence in gallstones increases probably because of an increased saturation of bile during the loss of weight. Ursodeoxycholic acid appears to be a promising prophylactic agent. Chenodeoxycholic acid is not useful for these subjects. There is controversy over whether obesity contributes to gastroesophageal reflux and gastric emptying disturbances. There are changes in gastrointestinal peptide plasma levels in obesity but it is not clear if this contributes to its development. The risk for high-risk colorectal adenomas and carcinomas is reported to be increased in obese males. Vertical banded gastroplasty and gastric bypass procedures are nowadays the surgical options for the treatment of obesity. Nutritional deficiencies, particularly of vitamin B12, folate and iron are common after gastric bypass and must be sought and treated. Dumping is another potential complication of this operation. If stenosis and gastric outlet obstruction develop endoscopic dilatation is a good therapeutic option.

Effect of cafeteria diet on the gastrointestinal transit and emptying in the rat

1. When gastrointestinal transit and emptying of intraluminal contents were studied using a radioactive tracer marker [( 14C]PEG-4000), the fastest gastric transit and the slowest overall transit time were observed in female Wistar rats (1-3 months old) after they were fed a cafeteria diet (a hypercaloric diet). 2. The small intestine length of cafeteria fed rats was higher than lean rats, whereas the stomach and large bowel length showed no difference between cafeteria and lean rats. 3. A state of mild obesity was obtained after rats were fed a cafeteria diet. This obesity was demonstrated by the highest body weight and the highest gain of white adipose tissue in rats fed a cafeteria diet.