Obesity increases the risk of small intestinal bacterial overgrowth (SIBO).

BACKGROUND: Small intestinal bacterial overgrowth (SIBO) has been associated with anatomical and motility-related abnormalities. Specifically, obesity has been postulated to alter small bowel motility, leading to SIBO. AIMS: (i) Assess the prevalence of SIBO in obesity; (ii) determine the relationship of obesity and SIBO, using small bowel transit time (SBTT) and pH; (iii) profile the gut microbiome in obese and non-obese patients with SIBO. METHODS: Thirty consecutive participants referred for SIBO underwent lactulose breath tests (LBTs) and wireless motility capsule (WMC) studies. Composition of the intestinal microbiome was assessed by analyzing samples from three different gastrointestinal sites via 16S rRNA gene-sequencing. KEY RESULTS: SIBO was more frequent among obese patients vs non-obese patients (88.9% vs 42.9%, P < .05). Obesity did not correlate with small bowel transit time (SBTT), gastric pH, and small bowel pH. In patients with normal SBTT, obesity was associated with an 11-fold increase (P = .05) in the risk of SIBO. Whereas in those with prolonged SBTT, there was no correlation between obesity and SIBO. Obese vs non-obese patients exhibited significant differences in microbiome diversity in rectal samples. Obesity was associated with increased odds of developing SIBO (P = .04) in multivariate regression analyses. CONCLUSIONS AND INFERENCES: While obesity was significantly associated with SIBO, our findings suggest that alterations in gut pH, SBTT, and decline in species richness do not account for the obesity-SIBO relationship.

Nicotinic receptor subtypes mediating relaxation of the normal human clasp and sling fibers of the upper gastric sphincter.

BACKGROUND: Proper function of the gastro-esophageal high pressure zone is essential for the integrity of the antireflux barrier. Mechanisms include tonic contractions and the decreased tone during transient lower esophageal sphincter relaxations. METHODS: We characterized the pharmacology of nicotinic receptors mediating relaxations of the human upper gastric sphincter (clasp and sling fibers) using currently available subtype selective nicotinic antagonists in tissue from organ transplant donors. Donors with either a history of gastro-esophageal reflux disease or histologic evidence of Barrett's esophagus were excluded. Clasp and sling muscle fiber strips were used for one of three paradigms. For paradigm 1, each strip was exposed to carbachol, washed, exposed to nicotinic antagonists then re-exposed to carbachol. In paradigm 2, strips were exposed to a near maximally effective bethanechol concentration then nicotine was added. Strips then were washed, exposed to nicotinic antagonists then re-exposed to bethanechol followed by nicotine. In paradigm 3, strips were exposed to bethanechol then choline or cytisine. KEY RESULTS: 100 µM methyllycaconitine has no inhibitory effects on relaxations, eliminating homomeric α7 subtypes. Subtypes composed of α4ß2 subunits are also eliminated because choline acts as an agonist and dihydro-beta-erythroidine is ineffective. CONCLUSIONS & INFERENCES: Because mecamylamine blocks the relaxations and both choline and cytisine act as agonists in both clasp and sling fibers, the nicotinic receptor subtypes responsible for these relaxations could be composed of α3ß4ß2, α2ß4, or α4ß4 subunits.

Enhanced nicotinic receptor mediated relaxations in gastroesophageal muscle fibers from Barrett's esophagus patients.

BACKGROUND: Increased nicotinic receptor mediated relaxation in the gastroesophageal antireflux barrier may be involved in the pathophysiology of reflux. This study is designed to determine whether the defects we previously identified in gastroesophageal reflux disease patients in- vivo are due to abnormalities of the gastric sling, gastric clasp, or lower esophageal circular (LEC) muscle fibers. METHODS: Muscle strips from whole stomachs and esophagi were obtained from 16 normal donors and 15 donors with histologically proven Barrett's esophagus. Contractile and relaxant responses of gastric sling, gastric clasp, or LEC fibers were determined to increasing concentrations of carbachol and to nicotine after inducing maximal contraction to bethanechol. Muscarinic receptor density was measured using subtype selective immunoprecipitation. KEY RESULTS: Barrett's esophagus gastric sling and LEC fibers have decreased carbachol-induced contractions. Barrett's esophagus sling fibers have decreased M2 -muscarinic receptors and LEC fibers have decreased M3 receptors. Relaxations of all three fiber types are greater in Barrett's esophagus specimens to both high carbachol concentrations and to nicotine following bethanechol precontraction. The maximal response to bethanechol is greater in Barrett esophagus sling and LEC fibers. CONCLUSIONS & INFERENCES: The increased contractile response to bethanechol in Barrett's specimens indicates that the defect is likely not due to the smooth muscle itself. The enhanced nicotinic receptor mediated response may be involved in greater relaxation of the muscles within the high-pressure zone of the gastroesophageal junction during transient lower esophageal sphincter relaxations and during deglutitive inhibition and may be involved in the pathophysiology of gastroesophageal reflux disease.

Characterization of the distal esophagus high-pressure zone with manometry, ultrasound and micro-computed tomography.

BACKGROUND: We sought to determine how the individual components of the distal esophagus and proximal stomach form the gastroesophageal junction high-pressure zone (GEJHPZ) antireflux barrier. METHODS: An endoscopic ultrasound/manometry catheter was pulled through the proximal stomach and distal esophagus in 20 normal subjects. The axial length and width of individual structures on endoscopic ultrasound were measured. The anatomic orientation of gastroesophageal junction (GEJ) components was examined in two organ donor specimens using micro-computed tomography (micro-CT). KEY RESULTS: The three distinct structures identified within the GEJHPZ, from distal to proximal, were as follows: the gastric clasp and sling muscle fiber complex, crural diaphragm, and lower esophageal circular smooth muscle fibers (LEC). The LEC was statistically significantly thicker than adjacent esophageal muscles. These structures were associated with three pressure peaks. The pressure peak produced by the clasp/sling fiber complex often overlapped with the pressure peak from the crural diaphragm. The most proximal peak, associated with the LEC, was significantly greater and bimodal in nine of 20 subjects. This bimodal LEC pressure peak correlated with two areas of thickened muscle observed with ultrasound. Micro-CT of GEJ from organ donors confirmed the two areas of thickened muscle. CONCLUSIONS & INFERENCES: Three distinct anatomic structures, the clasp and sling muscle fibers, crural diaphragm, and LEC combine to form the antireflux barrier of the proximal stomach and distal esophagus. The clasp and sling muscle fibers combine with the crural diaphragm to form a distal pressure profile. The more proximal LEC has a bimodal pressure profile in some patients.

Survey and management of anaesthesia related complications in PACU.

It is the first prospective study about anaesthesia related postoperative complications conducted in Hamad General Hospital. Total 1128 adult patients admitted to the Post Anaesthesia Care Unit (PACU) during a period of three months were surveyed for anaesthesia related complications. Documented complications were found in 48 patients i.e. 4.25% of patients' population. The types of complications were related to the respiratory system, cardiovascular system, nausea/vomiting and body temperature in this descending order. Most of the complications happened to healthy ASA I and II patients. Factors that play major role in determining the immediate postoperative complications were the ASA status, the level of anaesthesia seniority attending the patient, the urgency and the nature of procedure. We tried to find other factors that may influence complications in addition, discussed below.

A missing sphincteric component of the gastro-oesophageal junction in patients with GORD.

It was recently shown that the tonic pressure contribution to the high-pressure zone of the oesophago-gastric segment (OGS) contains the contributions from three distinct components, two of which are smooth muscle intrinsic sphincter components, a proximal and a distal component [J Physiol 2007; 580.3: 961]. The aim of this study was to compare the pressure contributions from the three sphincteric components in normal subjects with those in gastro-oesophageal reflux disease (GORD) patients. A simultaneous endoluminal ultrasound and manometry catheter was pulled through the OGS in 15 healthy volunteers and seven patients with symptomatic GORD, before and after administration of atropine. Pre-atropine (complete muscle tone), postatropine (non-muscarinic muscle tone plus residual muscarinic tone) and subtracted (pure muscarinic muscle tone) pressure contributions to the sphincter were averaged after referencing spatially to the right crural diaphragm and the pull-through start position. In the normal group, the atropine-resistant and atropine-attenuated pressures identified the crural and two smooth muscle sphincteric components respectively. The subtraction pressure curve contained proximal and distal peaks. The proximal component moved with the crural sling between full inspiration and full expiration and the distal component coincided with the gastric sling-clasp fibre muscle complex. The subtraction curve in the GORD patients contained only a single pressure peak that moved with the crural sphincter, while the distal pressure peak of the intrinsic muscle component, which was previously recognized in the normal subjects, was absent. We hypothesize that the distal muscarinic smooth muscle pressure component (gastric sling/clasp muscle fibre component) is defective in GORD patients.