Electron diffraction studies of light-induced conformational changes in the Leu-93 → Ala bacteriorhodopsin mutant

We previously have presented evidence for prominent structural changes in helices F and G of bacteriorhodopsin during the photocycle. These changes were determined by carrying out electron diffraction analysis of illuminated two-dimensional crystals of wild-type bacteriorhodopsin or the Asp-96 → Gly mutant that were trapped at a stage in the photocycle after light-driven proton release, but preceding proton uptake from the aqueous medium. Here, we report structural analysis of the long-lived O intermediate observed in the photocycle of the Leu-93 → Ala mutant, which accumulates after the release and uptake of protons, but before the reisomerization of retinal to its initial all-trans state. Projection Fourier difference maps show that upon illumination of the Leu-93 → Ala mutant, significant structural changes occur in the vicinity of helices C, B, and G, and to a lesser extent near helix F. Our results suggest that (i) all four helices that line the proton channel (B, C, F, and G) participate in structural changes during the late stages of the photocycle, and (ii) completion of the photocycle involves significant conformational changes in addition to those that are associated with steps in proton transport.     

Catheter ablation guided by termination of postinfarction ventricular tachycardia by pacing with nonglobal capture.

OBJECTIVES: We prospectively investigated the prevalence and value of this criterion for identifying a target site for ablation in patients with postinfarction ventricular tachycardia (VT). BACKGROUND: Termination of postinfarction VT by pacing with nonglobal capture identifies a critical component of the reentrant circuit. METHODS: In a consecutive series of 34 patients with prior infarction (age 67 +/- 10 years, ejection fraction 0.26 +/- 0.1) referred for radiofrequency catheter ablation, mapping was performed in the left ventricle. At sites with abnormal electrograms, pacing was performed during VT. If VT terminated with nonglobal capture during the pacing train, radiofrequency energy was delivered. RESULTS: Sixty-two VTs (cycle length 450 +/- 84 ms) were mapped and targeted for radiofrequency ablation. Concealed entrainment was present at 101 endocardial sites. Among the 101 sites, VT terminated by pacing with nonglobal capture at 5 sites (5%). At 10 additional sites in 10 patients, VT terminated by pacing with nonglobal capture, and concealed entrainment could not be documented at these sites because of reproducible termination of the VT. An application of radiofrequency energy resulted in VT termination at all 15 sites where nonglobal capture was documented and the targeted VTs were no longer inducible after ablation. CONCLUSIONS: Termination of VT by pacing with nonglobal capture can be demonstrated in approximately one third of patients with postinfarction VT and is a specific criterion for identifying a critical component of the reentrant circuit, whether or not concealed entrainment can be documented at that site.     

Gossypiboma Presenting as Coloduodenal Fistula – Report of a Rare Case With Review of Literature

The term gossypiboma is used to describe a mass of cotton matrix left behind in a body cavity intraoperatively. The most common site reported is the abdominal cavity. It can present with abscess, intestinal obstruction, malabsorption, gastrointestinal hemorrhage, and fistulas. A 37-year-old woman presented with pain in the right hypochondrium for 2 months following open cholecystectomy. As she did not improve with proton pump inhibitors, an esophagogastroduodenoscopy (EGD) was done, which showed a possible gauze piece stained with bile in the first part of the duodenum. Contrast-enhanced computed tomography (CECT) of the abdomen revealed an abnormal fistulous communication of the first part of duodenum with proximal transverse colon, with a hypodense, mottled lesion within the lumen of the proximal transverse colon plugging the fistula, suggestive of a gossypiboma. Excision of the coloduodenal fistula, primary duodenal repair, and feeding jejunostomy was done. The patient recovered well and is now tolerating normal diet. Coloduodenal fistula is usually caused by Crohn''s disease, malignancy, right-sided diverticulitis, and gall stone disease. Isolated coloduodenal fistula due to gossypiboma has not been reported in the literature so far to the best of our knowledge. We report this case of coloduodenal fistula secondary to gossypiboma for its rarity and diagnostic challenge.Key words: Surgical sponges, Intestinal fistula, Multidetector computed tomographyThe first report of a coloduodenal fistula was by Haldane in 1862, and it was malignant from the hepatic flexure.¹ Coloduodenal fistula is caused by Crohn''s disease, malignancy, right-sided diverticulitis, and gall stone disease, but isolated coloduodenal fistula due to gossypiboma has not been reported in the literature to the best of our knowledge. Gossypiboma is known to present as intra-abdominal abscess, intestinal obstruction, and fistulization, but coloduodenal fistula has not been reported as a mode of presentation. We report this case of coloduodenal fistula secondary to gossypiboma for its rarity and diagnostic challenge.     

Prevalence and correlates of alcohol use disorders in the Singapore Mental Health Survey

Aims To establish the prevalence, correlates, comorbidity and treatment gap of alcohol use disorders in the Singapore resident population. Design The Singapore Mental Health Study is a cross‐sectional epidemiological survey. Setting A nationally representative survey of the resident (citizens and permanent residents) population in Singapore. Participants A total of 6616 Singaporean adults aged 18 years and older. Measurements The diagnoses were established using the World Mental Health Composite International Diagnostic Interview (WMH‐CIDI) diagnostic modules for life‐time and 12‐month prevalence of selected mental illnesses including alcohol use disorders. Findings The life‐time prevalence of alcohol abuse and alcohol dependence was 3.1% and 0.5%, while the 12‐month prevalence of alcohol abuse and alcohol dependence was 0.5% and 0.3%, respectively. The life‐time and 12‐month prevalence of alcohol use disorders was 3.6% and 0.8%, respectively. Those with alcohol use disorder had significantly higher odds of having major depressive disorder [odds ratio (OR) 3.1] and nicotine dependence (OR 4.5). Compared to the rest of the population, those with an alcohol use disorder had significantly higher odds of having gastric ulcers (OR 3.0), respiratory conditions (OR 2.1) and chronic pain (OR 2.1). Only one in five of those with alcohol use disorder had ever sought treatment. Conclusions The prevalence of alcohol use disorders is relatively low in the Singapore adult population. Comorbidity with mental and physical disorders is significant, emphasizing the need to screen people with alcohol use disorders for these comorbidities.