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An emerging area of research extends work on couple functioning and physical health to gut health, a critical marker of general health and known to diminish with age. As a foray into this area, we conducted a pilot study to (1) determine the feasibility of remote data collection, including a fecal sample, from older adult couples, (2) examine within-couple concordance in gut microbiota composition, and (3) examine associations between relationship functioning and gut microbiota composition. Couples (N = 30) were recruited from the community. The participants' demographic characteristics were as follows: M (SD) age = 66.6 (4.8), 53% female, 92% White, and 2% Hispanic. Two of the couples were same-sex. All 60 participants completed self-report measures and supplied a fecal sample for microbiome analysis. Microbial DNA was extracted from the samples, and the 16S rRNA gene V4 region was amplified and sequenced. The results indicated that individuals shared more similar gut microbial composition with their partners than with others in the sample, p < 0.0001. In addition, individuals with better relationship quality (greater relationship satisfaction and intimacy and less avoidant communication) had greater microbial diversity, p < 0.05, a sign of healthier gut microbiota. Further research with a larger and more diverse sample is warranted to elucidate mechanisms.

While the history of nutrition support dates to the ancient world, modern home parenteral and enteral nutrition (HPEN) has been available since the 1960s. Home enteral nutrition is primarily for patients in whom there is a reduction in oral intake below the amount needed to maintain nutrition or hydration (i.e., oral failure), whereas home parenteral nutrition is used for patients when oral-enteral nutrition is temporarily or permanently impossible or absorption insufficient to maintain nutrition or hydration (i.e., intestinal failure). The development of home delivery of these therapies has revolutionized the field of clinical nutrition. The use of HPEN appears to be increasing on a global scale, and because of this, it is important for healthcare providers to understand all that HPEN entails to provide safe, efficacious, and cost-effective support to the HPEN patient. In this article, we provide a comprehensive review of the indications, patient requirements, monitoring, complications, and overall process of managing these therapies at home. Whereas some of the information in this article may be applicable to the pediatric patient, the focus is on the adult population.

Background: The large intestine provides a compensatory role in energy recovery when surgical interventions such as extensive small intestinal resections or bypass operations lower the efficiency of nutrient absorption in the upper gastrointestinal (GI) tract. While microorganisms in the colon are known to play vital roles in recovering energy, their contributions remain to be qualified and quantified in the small intestine resection., Objective: We develop a mathematical model that links nutrient absorption in the upper and lower GI tract in two steps., Methods: First, we describe the effects of small intestine resection on the ileocecal output (ICO), which enters the colon and provides food for microbes. Second, we describe energy recovered by the colon's microorganisms via short-chain fatty acid (SCFA) production. We obtain model parameters by performing a least-squares regression analysis on clinical data for subjects with normal physiology and those who had undergone small intestine resection., Results: For subjects with their intestines intact, our model provided a metabolizable energy value that aligns well with the traditional Atwater coefficients. With removal of the small intestine, physiological absorption became less efficient, and the metabolizable energy decreased. In parallel, the inefficiencies in physiological absorption by the small intestine are partly compensated by production of short-chain fatty acids (SCFA) from proteins and carbohydrates by microorganisms in the colon. The colon recovered more than half of the gross energy intake when the entire small intestine was removed. Meanwhile, the quality of energy absorbed changed, because microbe-derived SCFAs, not the original components of food, become the dominant form of absorbed energy., Conclusion: The mathematical model developed here provides an important framework for describing the effect of clinical interventions on the colon's microorganisms., Competing Interests: The authors have declared that no competing interests exist.

Although the etiology of obesity is not well-understood, genetic, environmental, and microbiome elements are recognized as contributors to this rising pandemic. It is well documented that Roux-en-Y gastric bypass (RYGB) surgery drastically alters the fecal microbiome, but data are sparse on temporal and spatial microbiome and metabolome changes, especially in human populations. We characterized the structure and function (through metabolites) of the microbial communities in the gut lumen and structure of microbial communities on mucosal surfaces in nine morbidly obese individuals before, 6 months, and 12 months after RYGB surgery. Moreover, using a comprehensive multi-omic approach, we compared this longitudinal cohort to a previously studied cross-sectional cohort (n = 24). In addition to the expected weight reduction and improvement in obesity-related comorbidities after RYGB surgery, we observed that the impact of surgery was much greater on fecal communities in comparison to mucosal ones. The changes in the fecal microbiome were linked to increased concentrations of branched-chain fatty acids and an overall decrease in secondary bile acid concentrations. The microbiome and metabolome data sets for this longitudinal cohort strengthen our understanding of the persistent impact of RYGB on the gut microbiome and its metabolism. Our findings highlight the importance of changes in mucosal and fecal microbiomes after RYGB surgery. The spatial modifications in the microbiome after RYGB surgery corresponded to persistent changes in fecal fermentation and bile acid metabolism, both of which are associated with improved metabolic outcomes.

Short bowel syndrome (SBS) is a malabsorptive disorder associated with significant morbidity and mortality, reduced quality of life, and high health care costs. Managing the patient with SBS requires an understanding of gastrointestinal anatomy and physiology; a dedicated multidisciplinary team; and the coordination of dietary, fluid, pharmacologic, and comorbid disease management. This article provides an overview of the current state of management of SBS, including a practical approach to optimizing the care and quality of life of the adult patient with SBS., Competing Interests: The authors have no relevant conflicts of interest to disclose.

Roux-en-Y gastric bypass (RYGB) and laparoscopic adjustable gastric banding (LAGB) are anatomically different bariatric operations. RYGB achieves greater weight loss compared with LAGB. Changes in the gut microbiome have been documented after RYGB, but not LAGB, and the microbial contribution to sustainable surgical weight loss warrants further evaluation. We hypothesized that RYGB imposes greater changes on the microbiota and its metabolism than LAGB, and that the altered microbiota may contribute to greater weight loss. Using multi-omic approaches, we analyzed fecal microbial community structure and metabolites of pre-bariatric surgery morbidly obese (PreB-Ob), normal weight (NW), post-RYGB, and post-LAGB participants. RYGB microbiomes were significantly different from those from NW, LAGB and PreB-Ob. Microbiome differences between RYGB and PreB-Ob populations were mirrored in their metabolomes. Diversity was higher in RYGB compared with LAGB, possibly because of an increase in the abundance of facultative anaerobic, bile-tolerant and acid-sensible microorganisms in the former. Possibly because of lower gastric acid exposure, phylotypes from the oral cavity, such as Escherichia, Veillonella and Streptococcus, were in greater abundance in the RYGB group, and their abundances positively correlated with percent excess weight loss. Many of these post-RYGB microorganisms are capable of amino-acid fermentation. Amino-acid and carbohydrate fermentation products-isovalerate, isobutyrate, butyrate and propionate-were prevalent in RYGB participants, but not in LAGB participants. RYGB resulted in greater alteration of the gut microbiome and metabolome than LAGB, and RYGB group exhibited unique microbiome composed of many amino-acid fermenters, compared with nonsurgical controls.

Background & Aims: Systemic scleroderma (SSc) is associated with esophageal aperistalsis and hypotensive esophagogastric junction pressure, although there could be a gradation in esophageal motor dysfunction. We characterized esophageal motor function by high-resolution esophageal manometry (HRM) and assessed associations between SSc severity, health-related quality of life (HRQOL), and HRM findings in patients., Methods: We performed a prospective study of 200 patients with SSc and 102 patients without SSc (controls) who underwent HRM at Mayo Clinic Arizona from May 2006 through January 2015. We used data on integrated relaxation pressure, distal contractile integral, and distal latency to classify esophageal motility disorders according to the Chicago Classification v 3.0. A subset of subjects (n = 122) completed SSc-specific gastrointestinal symptom and HRQOL questionnaires. HRM findings, symptoms, and HRQOL data were compared among diffuse SSc, limited SSc, and control subjects. Categorical variables were compared by using the χ 2 or Fisher exact test; continuous variables were compared by using Mann-Whitney or Kruskal-Wallis test. Multivariable logistic regression was used to assess the association between severity of esophageal dysmotility and baseline clinical factors., Results: Among patients with SSc, 83 had diffuse SSc (42%), and 117 had limited SSc (58%). Absent contractility was more frequent in patients with SSc than in controls (56% vs 13%; P < .001). HRM findings varied among the patients; absent contractility (56%) was the most frequent diagnosis, followed by normal motility (26%) and ineffective esophageal motility (10%). Classic scleroderma esophagus (esophagogastric junction pressure with absent contractility) was only observed in 33% of patients (34% with diffuse SSc vs 32% limited SSc) (P = .880). Severe esophageal dysmotility was associated with disease duration, interstitial lung disease, and higher gastrointestinal symptom scores (P < .001). HRQOL was decreased in patients with SSc and severe esophageal dysmotility., Conclusions: Although severe dysmotility is more common in patients with SSc than in controls, we observed the so-called scleroderma esophagus in only one-third of patients with SSc. Esophageal motor function appears to be heterogeneous in SSc. Esophageal dysmotility reduces HRQOL in patients with SSc., (Copyright © 2017 AGA Institute. Published by Elsevier Inc. All rights reserved.)

Background: Obesity is associated with increased oesophageal acid exposure time (AET) in patients with gastro-oesophageal reflux (GER), and may decrease the effects of proton pump inhibitors (PPIs)., Aim: To evaluate the effects of increased body mass on the ability of PPI therapy to decrease AET in patients with reflux symptoms., Methods: Acid exposure time profiles collected from adult patients using wireless pH-metry while on or off PPI therapy was retrospectively reviewed. Patients were separated into five body mass index (BMI) categories as defined by the World Health Organization. A multivariable logistic regression evaluated the association between abnormal AET and BMI groups while controlling for age, gender and pH capsule placement methods., Results: The study group comprised 968 patients with 336 (34.7%) studied on a PPI and 632 (65.3%) studied off PPI therapy. AET (total greater than 5.3%) was found more frequently in the overweight (67%) and obese classes (74-80%) compared to those who were normal weight (40%) while off acid-suppressing medications (P < 0.001). No significant differences were found between these groups when studied on acid-suppressing medications, and the proportion of patients with abnormal AET across BMI classes was similar regardless of taking a PPI either once or twice daily., Conclusions: This is the largest study to report on the relationship between BMI and oesophageal acid exposure time in patients with GER on and off PPI therapy. We conclude that obesity is related to increased acid exposure time, but with no significant difference in acid exposure time among different weight-based groups when taking a once or twice-daily PPI., (© 2015 John Wiley & Sons Ltd.)

Background & Aims: Antidepressants are frequently prescribed to treat functional dyspepsia (FD), a common disorder characterized by upper abdominal symptoms, including discomfort or postprandial fullness. However, there is little evidence of the efficacy of these drugs in patients with FD. We performed a randomized, double-blind, placebo-controlled trial to evaluate the effects of antidepressant therapy on symptoms, gastric emptying (GE), and meal-induced satiety in patients with FD., Methods: We performed a study at 8 North American sites of patients who met the Rome II criteria for FD and did not have depression or use antidepressants. Patients (n = 292; 44 ± 15 years old, 75% were female, 70% with dysmotility-like FD, and 30% with ulcer-like FD) were randomly assigned to groups given placebo, 50 mg amitriptyline, or 10 mg escitalopram for 10 weeks. The primary end point was adequate relief of FD symptoms for ≥5 weeks of the last 10 weeks (of 12). Secondary end points included GE time, maximum tolerated volume in Nutrient Drink Test, and FD-related quality of life., Results: An adequate relief response was reported by 39 subjects given placebo (40%), 51 given amitriptyline (53%), and 37 given escitalopram (38%) (P = .05, after treatment, adjusted for baseline balancing factors including all subjects). Subjects with ulcer-like FD given amitriptyline were >3-fold more likely to report adequate relief than those given placebo (odds ratio = 3.1; 95% confidence interval: 1.1-9.0). Neither amitriptyline nor escitalopram appeared to affect GE or meal-induced satiety after the 10-week period in any group. Subjects with delayed GE were less likely to report adequate relief than subjects with normal GE (odds ratio = 0.4; 95% confidence interval: 0.2-0.8). Both antidepressants improved overall quality of life., Conclusions: Amitriptyline, but not escitalopram, appears to benefit some patients with FD, particularly those with ulcer-like (painful) FD. Patients with delayed GE do not respond to these drugs. ClinicalTrials.gov ID: NCT00248651., (Copyright © 2015 AGA Institute. Published by Elsevier Inc. All rights reserved.)

Background: The role of the gut microbiome in arresting pathogen colonization and growth is important for protection against Clostridium difficile infection (CDI). Observational studies associate proton pump inhibitor (PPI) use and CDI incidence. We hypothesized that PPI use affected the distal gut microbiome over time, an effect that would be best explored by time-longitudinal study of healthy subjects on PPI in comparison to treatment-naïve CDI subjects. This study enrolled nine healthy human subjects and five subjects with treatment-naïve CDI. After random assignment to a low (20 mg/day) or high (2× 20 mg/day) dose group, fecal samples were collected from the nine healthy subjects before, during, and after 28 days of PPI use. This was done in conjunction with pre-treatment fecal collection from CDI subjects. High-throughput sequencing (16S rRNA) was performed on time-longitudinal samples to assess changes to the healthy gut microbiome associated with prolonged PPI usage. The healthy samples were then compared to the CDI subjects to explore changes over time to the gut microbiome associated with PPI use and potentially related to CDI., Results: We report that PPI usage at low and high dosages, administered for 28 days, resulted in decreases to observed operational taxonomic unit (OTU) counts after both 1 week and 1 month. This decrease resulted in observed OTU levels that were similar to those found in treatment-naïve CDI patients, which was partly reversible after a 1 month recovery period. We did not detect a dose-dependent difference in OTU levels nor did we detect significant changes in taxa previously reported to be affected by PPI treatment., Conclusion: While our observation of diminishing observed OTU counts during PPI therapy is a preliminary finding in a small cohort, our hypothesis that PPIs disrupt the healthy human gut microbiome is supported in this group. We conclude that decreases in observed species counts were reversible after cessation of PPI usage within 1 month. This finding may be a potential explanation for the association between prolonged PPI usage and CDI incidence.

Objective: To report the initial experience of treating recurrent Clostridium difficile infection (CDI) with fecal microbiota transplant (FMT) at Mayo Clinic in Arizona., Patients and Methods: The study retrospectively reviewed FMTs performed at Mayo Clinic in Arizona between January 1, 2011, and January 31, 2013. All the recipients had multiple recurrent CDIs unresponsive to traditional antibiotic drug therapy. A standardized protocol was developed to identify patients, screen donors, perform FMT, and determine outcomes via telephone surveys., Results: Thirty-one patients (mean ± SD age, 61.26±19.34 years) underwent FMT. Median time from index infection to FMT was 340 days. Ninety-seven percent (29 of 30) of patients reported substantial improvement or resolution of diarrhea (median time to improvement, 3 days), 74% (17 of 23) reported improvement or resolution of abdominal pain (median time to improvement, 3 days), and 55% (16 of 29) had improvement or resolution of fatigue (median time to improvement, 6 days). Three patients underwent repeated FMT owing to persistent symptoms; 2 reported improvement in diarrhea with the second therapy. No serious adverse events directly related to FMT were reported., Conclusion: A standardized regimen of FMT for recurrent CDI is safe, is highly effective, and can be provided using a relatively simple protocol., (Copyright © 2013 Mayo Foundation for Medical Education and Research. Published by Elsevier Inc. All rights reserved.)

Background: Functional dyspepsia (FD), a common functional gastrointestinal disorder, is defined by the Rome III criteria as symptoms of epigastric pain or discomfort (prevalence in FD of 89-90%), postprandial fullness (75-88%), and early satiety (50-82%) within the last 3 months with symptom onset at least 6 months earlier. Patients cannot have any evidence of structural disease to explain symptoms and predominant symptoms of gastroesophageal reflux are exclusionary. Symptoms of FD are non-specific and the pathophysiology is diverse, which explains in part why a universally effective treatment for FD remains elusive., Aim: To present current management options for the treatment of FD (therapeutic gain/response rate noted when available)., Results: The utility of Helicobacter pylori eradication for the treatment of FD is modest (6-14% therapeutic gain), while the therapeutic efficacy of proton pump inhibitors (PPI) (7-10% therapeutic gain), histamine-type-2-receptor antagonists (8-35% therapeutic gain), prokinetic agents (18-45%), tricyclic antidepressants (TCA) (response rates of 64-70%), serotonin reuptake inhibitors (no better than placebo) is limited and hampered by inadequate data. This review discusses dietary interventions and analyses studies involving complementary and alternative medications, and psychological therapies., Conclusions: A reasonable treatment approach based on current evidence is to initiate therapy with a daily PPI in H. pylori-negative FD patients. If symptoms persist, a therapeutic trial with a tricyclic antidepressant may be initiated. If symptoms continue, the clinician can possibly initiate therapy with an anti-nociceptive agent, a prokinetic agent, or some form of complementary and alternative medications, although evidence from prospective studies to support this approach is limited., (© 2012 Blackwell Publishing Ltd.)

The past decade has seen an enormous increase in the number of bariatric, or weight loss, operations performed. This trend is likely to continue, mirroring the epidemic of obesity around the world and its rising prevalence among children. Bariatric surgery is considered by many to be the most effective treatment for obesity in terms of maintenance of long-term weight loss and improvement in obesity-related comorbid conditions. Although overly simplified, the primary mechanisms of the surgical interventions currently utilized to treat obesity are the creation of a restrictive or malabsorptive bowel anatomy. Operations based on these mechanisms include the laparoscopic adjustable gastric band and laparoscopic vertical sleeve gastrectomy (considered primarily restrictive operations), the laparoscopic biliopancreatic diversion with or without a duodenal switch (primarily malabsorptive operation), and the laparoscopic Roux-en-Y gastric bypass (considered a combination restrictive and selective malabsorptive procedure). Each operation has pros and cons. Important considerations, for the patient and surgeon alike, in the decision to proceed with bariatric surgery include the technical aspects of the operation, postoperative complications including long-term nutritional problems, magnitude of initial and sustained weight loss desired, and correction of obesity-related comorbidities. Herein, the pros and cons of the contemporary laparoscopic bariatric operations are reviewed and ongoing controversies relating to bariatric surgery are discussed: appropriate patient selection, appropriate operation selection for an individual patient, surgeon selection, and how to measure success after surgery.

Background & Aims: Cholecystokinin-cholescintigraphy (CCK-CS) provides a physiologic, noninvasive, and quantitative method for assessing gallbladder contraction and calculation of a gallbladder ejection fraction (GBEF). At present, it is used most commonly to identify patients with suspected functional gallbladder disorder. However, the methodology of CCK infusion and normal values differ markedly among imaging centers., Methods: This document represents the consensus opinion of an interdisciplinary panel that gathered to assess the current optimal method for performing CCK-CS in adults, potential uses and limitations of CCK-CS, and questions that require further investigation., Results: The panel recommended the use of a single, standardized, recently described CCK-CS protocol that involves infusion of 0.02 μg/kg of sincalide over 60 minutes with a normal gallbladder ejection fraction defined as ≥38%. The panel emphasized the need for a large, multicenter, prospective clinical trial to establish the utility of CCK-CS in the diagnosis of functional gallbladder disease. Although not without controversy regarding its clinical utility, the primary indication for CCK-CS at present is the well-selected patient with suspected functional gallbladder disorder., Conclusions: Agreement was reached that the adoption of this standardized protocol is critical to improve how CCK-CS is used to direct patient care and will represent an improvement over the diverse methods currently in use by eliminating the current lack of uniformity and adding both reliability and credibility to the results., (Copyright © 2011 AGA Institute. Published by Elsevier Inc. All rights reserved.)

Background & Aims: Negative affectivity and social isolation (Type D personality) are personality traits associated with poor health-related quality of life (HRQoL). We hypothesized these traits would be associated with impaired HRQoL and increased gastrointestinal symptom severity in functional gastrointestinal disorders., Methods: Data were collected from patients undergoing breath testing. Patients completed the Type D Scale-14, Gastrointestinal Symptoms Severity Index and Short-Form Health Survey 12., Results: Of 230 patients evaluated, 37% met criteria for Type D personality. Type D was associated with a decreased Mental Component score on the Short-Form Health Survey 12 (mean difference = -8.29; 95% confidence interval, 5.2-11.4; P < .001). On the Gastrointestinal Symptoms Severity Index, severity of symptoms was significantly higher in Type D patients compared with non Type D patients (P < .001)., Conclusions: Type D personality was associated with decreased perceived HRQoL and reporting of more severe gastrointestinal symptoms. Type D personality construct may be an important consideration when assessing HRQoL outcomes. Consideration of personality traits could improve risk stratification in research and clinical practice in this patient group., (Copyright 2010 AGA Institute. Published by Elsevier Inc. All rights reserved.)

Background & Aims: Colonic transit time (CTT) traditionally is assessed with radiopaque markers (ROMs), which requires radiation and is hindered by lack of standardization and compliance. We assessed regional and CTT with the SmartPill (SmartPill Corporation, Buffalo, NY), a new wireless pH and pressure recording capsule, in constipated and healthy subjects and compared this with ROM., Methods: Seventy-eight constipated (Rome II) and 87 healthy subjects ingested a 260-kcal meal, a ROM capsule, and the SmartPill. Subjects wore a data receiver and kept daily stool diaries for 5 days. SmartPill recordings assessed CTT, whole-gut transit time (WGTT), small-bowel transit time, and gastric emptying time. Abdominal radiographs on days 2 and 5 assessed ROM transit. Sensitivity/specificity and receiver operating characteristics (ROCs) of each technique and utility were compared., Results: Gastric emptying time, CTT, and WGTT were slower (P < .01) in constipated subjects than controls. CTT was slower in women than men (P = .02). Day 2 and day 5 ROM transits were slower (P < .001) in constipated subjects. Correlation of the SmartPill CTT with ROMs expelled on day 2/day 5 was r = 0.74/r = 0.69 in constipation, and r = 0.70/r = 0.40 in controls, respectively. The diagnostic accuracy of the SmartPill CTT to predict constipation from ROC was 0.73, with a specificity of 0.95. These were comparable with those of day 5 ROM (ROC, 0.71; specificity, 0.95)., Conclusions: The SmartPill is a novel ambulatory technique of assessing regional (gastric, small bowel, colonic) and WGTT without radiation. It reveals hitherto unrecognized gender differences and upper-gut dysfunction in constipation. It correlates well with ROM and offers a standardized method of discriminating normal from slow colonic transit.

Background: Safe and effective colonoscopy is aided by the use of endoscopic techniques and maneuvers (ETM) during the examination including patient repositioning, stiffening of the endoscope and abdominal pressure., Aim: To better understand the use and value of ETM during colonoscopy by using a device that allows real-time imaging of the colonoscope insertion shaft., Methods: The use of ETM during colonoscopy and their success was recorded. Experienced colonoscopists and endoscopy assistants used a commercially available electromagnetic (EM) transmitter and a special adult variable stiffness instrument with 12 embedded sensors to examine 46 patients. In 5 of these a special EM probe passed through the instrument channel of a standard pediatric variable stiffness colonoscope was used instead of the EM colonoscope., Results: Thirty-nine men and 7 women with a mean age of 64 years (range 33-90) were studied. The cecum was intubated in 93.5% (43/46). The mean time to reach the cecum was 10.6 minutes (range 3-25). ETM were used a total of 174 times in 41 of the patients to assist with cecal intubation. When ETM were required to reach the cecum, and the cecum was intubated, an average of 3.82 ETM/patient was used. While ETM were used most often when the tip of the colonoscope was in the left side of the colon (rectum 5.0%, sigmoid colon 20.7%, descending colon 5.0%, and splenic flexure 11.6%), when the instrument was in the transverse colon (14.8%), hepatic flexure (20.7%) and ascending colon (19.8%) the use of ETM was also required. When the colonoscope tip was in the transverse colon, hepatic flexure and ascending colon, ETM success rates were less (61.1%, 52.0%, and 41.7% respectively) compared to the left colon success rates (rectum 83.3%, sigmoid colon 84.0%, descending colon 100%, and splenic flexure 85.7%)., Conclusion: The EM colonoscope allows imaging of the insertion shaft without fluoroscopy and is a useful device for evaluating the efficacy of ETM. ETM are important tools of the colonoscopist and are used most often in the left colon where they are most effective.

Recent evidence suggests that the microbial community in the human intestine may play an important role in the pathogenesis of obesity. We examined 184,094 sequences of microbial 16S rRNA genes from PCR amplicons by using the 454 pyrosequencing technology to compare the microbial community structures of 9 individuals, 3 in each of the categories of normal weight, morbidly obese, and post-gastric-bypass surgery. Phylogenetic analysis demonstrated that although the Bacteria in the human intestinal community were highly diverse, they fell mainly into 6 bacterial divisions that had distinct differences in the 3 study groups. Specifically, Firmicutes were dominant in normal-weight and obese individuals but significantly decreased in post-gastric-bypass individuals, who had a proportional increase of Gammaproteobacteria. Numbers of the H(2)-producing Prevotellaceae were highly enriched in the obese individuals. Unlike the highly diverse Bacteria, the Archaea comprised mainly members of the order Methanobacteriales, which are H(2)-oxidizing methanogens. Using real-time PCR, we detected significantly higher numbers of H(2)-utilizing methanogenic Archaea in obese individuals than in normal-weight or post-gastric-bypass individuals. The coexistence of H(2)-producing bacteria with relatively high numbers of H(2)-utilizing methanogenic Archaea in the gastrointestinal tract of obese individuals leads to the hypothesis that interspecies H(2) transfer between bacterial and archaeal species is an important mechanism for increasing energy uptake by the human large intestine in obese persons. The large bacterial population shift seen in the post-gastric-bypass individuals may reflect the double impact of the gut alteration caused by the surgical procedure and the consequent changes in food ingestion and digestion.

Obesity results from alterations in the body's regulation of energy intake, expenditure, and storage. Recent evidence, primarily from investigations in animal models, suggests that the gut microbiota affects nutrient acquisition and energy regulation. Its composition has also been shown to differ in lean vs obese animals and humans. In this article, we review the published evidence supporting the potential role of the gut microbiota in the development of obesity and explore the role that modifying the gut microbiota may play in its future treatment. Evidence suggests that the metabolic activities of the gut microbiota facilitate the extraction of calories from ingested dietary substances and help to store these calories in host adipose tissue for later use. Furthermore, the gut bacterial flora of obese mice and humans include fewer Bacteroidetes and correspondingly more Firmicutes than that of their lean counterparts, suggesting that differences in caloric extraction of ingested food substances may be due to the composition of the gut microbiota. Bacterial lipopolysaccharide derived from the intestinal microbiota may act as a triggering factor linking inflammation to high-fat diet-induced metabolic syndrome. Interactions among microorganisms in the gut appear to have an important role in host energy homeostasis, with hydrogen-oxidizing methanogens enhancing the metabolism of fermentative bacteria. Existing evidence warrants further investigation of the microbial ecology of the human gut and points to modification of the gut microbiota as one means to treat people who are over-weight or obese.

Small intestinal bacterial overgrowth (SIBO) occurs commonly in short-bowel syndrome (SBS) and, in some instances, may result in significant problems. SIBO is characterized by a variety of signs and symptoms resulting from nutrient malabsorption caused by an increased number and/or type of bacteria in the small intestine. The anatomic and physiologic changes that occur in SBS together with medications commonly used in these patients facilitate the development of SIBO. Because many aspects related to SIBO in the SBS population remain poorly understood, it was our aim to review the current understanding of the gut flora and issues related to SIBO occurring in SBS.

Recent experimental evidence suggests that polyethylene glycol (PEG) is a highly effective chemopreventive agent against colon cancer; however, the mechanism(s) remain largely unexplored. To further elucidate this issue, we evaluated the effect of PEG on two human colon cancer cell lines. PEG treatment resulted in a dose- and time-dependent reduction in cell number without alteration in markers of cell proliferation. However, there was a dramatic and specific, concentration-dependent induction of apoptosis, with 50 mM PEG rendering approximately half the cells apoptotic. This corresponded with a 17-fold induction in the expression of the pro-apoptotic protein, prostate apoptosis response-4. Our data suggest that induction of apoptosis may be responsible, at least in part, for the ability of PEG to prevent experimental colon cancer.