Combinatorial encoding of odors in the mosquito antennal lobe.

Among the cues that a mosquito uses to find a host for blood-feeding, the smell of the host plays an important role. Previous studies have shown that host odors contain hundreds of chemical odorants, which are detected by different receptors on the peripheral sensory organs of mosquitoes. But how individual odorants are encoded by downstream neurons in the mosquito brain is not known. We developed an in vivo preparation for patch-clamp electrophysiology to record from projection neurons and local neurons in the antennal lobe of Aedes aegypti. Combining intracellular recordings with dye-fills, morphological reconstructions, and immunohistochemistry, we identify different sub-classes of antennal lobe neurons and their putative interactions. Our recordings show that an odorant can activate multiple neurons innervating different glomeruli, and that the stimulus identity and its behavioral preference are represented in the population activity of the projection neurons. Our results provide a detailed description of the second-order olfactory neurons in the central nervous system of mosquitoes and lay a foundation for understanding the neural basis of their olfactory behaviors.

Replacement of a Björk-Shiley tilting disc mitral valve prosthesis 33 years after initial replacement.

Björk-Shiley tilting disc prosthesis was the first tilting disc prosthesis to be used worldwide on a large-scale basis. Herein, we report a case of a 67-year-old male presenting with severe prosthetic valvular dysfunction. He had undergone mitral valve replacement with Björk-Shiley valve at some other center in 1987. The surgical challenge was to replace that with an adequately sized prosthesis. To achieve that, we removed all the previously preserved posterior cusp and then reconstructed the sub-valvular apparatus. The patient had a smooth post-operative recovery. This case report highlights the longest reported survival of a Björk-Shiley mitral valve and specific challenges faced during such redo cases.

Aortic valve replacement with biological substitutes in children.

BACKGROUND: this study was performed to assess the results of aortic valve replacement in children with biological substitutes including homografts, pulmonary autografts (Ross procedure), and aortic valve reconstruction with autologous pericardium (Duran technique). METHODS: between March 1992 and July 2009, 73 children with aortic valve disease (mean age, 11.8 ±2.7 years) underwent aortic valve replacement with biological substitutes including homografts, pulmonary autografts, and aortic valve reconstruction with autologous pericardium. Associated procedures were mitral valve repair in 32 and subaortic membrane resection in 3. RESULTS: early mortality was 1.4% (1 patient). Median follow-up was 94 months. Sixty (83.3%) survivors had insignificant aortic regurgitation. Reoperation was required in 7 (9.6%) patients: for autograft dysfunction alone in 2, autograft failure and failed mitral valve repair in 2, autograft dysfunction with severe pulmonary homograft regurgitation in 1, severe homograft aortic valve regurgitation in 1, and right ventricular outflow tract obstruction in 1. There were 4 (5.4%) late deaths. Actuarial reoperation-free, event-free, and aortic valve dysfunction-free survival were 92.5% ±4%, 93.4% ±3.3 %, 94% ±2.9%, 86.2% ±4.3%, respectively, at 94 months. CONCLUSIONS: aortic valve replacement with biological substitutes is associated with acceptable hemodynamics and midterm results.

Open vertical vein in non-obstructed supracardiac TAPVC: merits and fate.

Data of 18 patients who underwent surgical repair of non-obstructed supracardiac total anomalous pulmonary venous connection between January 2007 and March 2011 were reviewed. The vertical vein was left patent in all patients as an elective surgical strategy. There was no operative mortality in patients with or without preoperative pulmonary infection, but there were significant differences in postoperative airway pressures, ventilation time, intensive care unit and hospital stay between the 2 groups. None of the patients demonstrated any flow in the vertical vein over a 30-day follow-up period. One patient had a mild anastomotic stricture and pulmonary venous hypoplasia. Operative repair of supracardiac total anomalous pulmonary venous connection can be carried out successfully without ligation of the vertical vein, and this strategy possibly reduces early postoperative morbidity and mortality, with no adverse effects detected in the short to midterm follow-up.

Unidirectional valved patch closure of ventricular septal defects with severe pulmonary arterial hypertension.

Delayed presentation of ventricular septal defect (VSD) is common in developing countries. Such patients often have severe pulmonary arterial hypertension (PAH), which increases post-operative morbidity and mortality. To address these problems, we used our technique of unidirectional valved patch (UVP) for closure of VSD. Between January 2006 and December 2010, 17 patients (age 2-23 years, median 9 years) with a large VSD and severe PAH underwent VSD closure with UVP. Pre-operative mean indexed pulmonary vascular resistance (PVRI) was 10.9 ± 2.2 Wood units and mean pre-operative systemic saturation was 93.4 ± 2.6%. Shunt was bidirectional in 15 patients and predominantly right to left in two. After VSD closure, intra-operative transoesophageal echocardiography revealed a right to left shunt across the patch in three patients 2, 7 and 9 years of age who had pre-operative PVRI of 9.5, 9.8 and 11.1 Wood units, respectively. There were no in-hospital deaths and all patients had uneventful recovery. Mean follow-up was 30 ± 14.7 months and all patients are well without cyanosis. Echocardiography showed no shunt across the patch and all have systemic saturation >95%. We conclude that UVP is a promising technique in patients with large VSD and severe PAH.

Peritonitis: 10 years' experience in a single surgical unit.

BACKGROUND: Peritonitis secondary to gut perforation is still one of the commonest surgical emergencies in India and is associated with high morbidity and mortality. The present study examines the aetiology and outcome of peritonitis cases operated on in our surgical unit, and compares our findings with those of previous studies performed between 1981 and 1991. METHOD: A retrospective study of 260 peritonitis patients operated on in a single surgical unit from 1995 to 2006 was done and data involving clinical presentation, operative findings and post-operative course were studied and analysed. RESULTS: Causes of peritonitis were small bowel perforation (96 ileal, 17 jejunal), peptic perforation (45 duodenal, 16 gastric), appendicular perforation (36), primary peritonitis (8), and others (42). The incidence of major complications was 25% (burst-11%, leak-5%, intraabdominal abscess-5%, multi-organ failure-6.5%). The overall mortality was 10%. High mortality was observed in jejunal, gall bladder and liver abscess perforation cases (> 20%). Histopathological evaluation (143 specimens) revealed tuberculosis in 42 (mostly small bowel), malignancy in 8, and inflammation in the rest. Comparisons with a similar study carried out in the same unit and published in 1995 revealed similar demographic features and mortality, but a change in the most common cause (peptic ulcer perforation to small bowel perforation), and an increased performance of enterostomy compared with primary repair in small bowel perforation and a decrease in the leak rate (13% to 4%). CONCLUSION: Small bowel perforation is the commonest form of perforation and the mortality rate associated with peritonitis remains unchanged.