Role of the dorsolateral pontine nucleus in short-term adaptation of the horizontal vestibuloocular reflex

The dorsolateral pontine nucleus (DLPN) is a major component of the cortico-ponto-cerebellar pathway that carries signals essential for smooth pursuit. This pathway also carries visual signals that could play a role in visually guided motor learning in the vestibular ocular reflex (VOR). However, there have been no previous studies that tested this possibility directly. The aim of this study was to determine the potential role of the DLPN in short-term VOR gain adaptation produced by viewing a scene through lenses placed in front of both eyes. In control experiments, adaptation of VOR gain was achieved by sinusoidal rotation (0.2 Hz, 30 degrees /s) for 2 h while the monkey viewed a stationary visual surround through either magnifying (x2) or minifying (x0.5) lenses. This led to increases (23-32%) or decreases (22-48%) of VOR gain as measured in complete darkness (VORd). We used injections of muscimol, a potent GABA(A) agonist (0.5 microl; 2%), to reversibly inactivate the DLPN, unilaterally, in three monkeys. After DLPN inactivation, initial acceleration of ipsilateral smooth-pursuit was reduced by 35-68%, and steady-state gain was reduced by 32-61%. Despite these significant deficits (P < 0.01) in ipsilesional smooth pursuit, the VOR during lens viewing was similar to that measured in preinjection control experiments. Similarly, after 2 h of adaptation, VORd gain was not significantly different (P > 0.61) from control adaptation values for either ipsi- or contralesional directions of head rotation. This was the case even though a stable ipsilesional smooth pursuit deficit persisted throughout the full adaptation period. Our results suggest that visual error signals for short-term adaptation of the VOR are derived from sources other than the DLPN perhaps including other basilar pontine nuclei and the accessory optic system.     

Metastatic Differentiated Thyroid Carcinoma: ClinicopathologicalProfile and Outcome in an Iodine Deficient Area

Reports on metastatic differentiated carcinoma in endemic goiter regions are scarce. The aim of this study was to look into the clinicopathological profile and outcome of patients with metastatic differentiated thyroid carcinoma (DTC) of endemic origin. This was a retrospective study of 28 cases of metastatic DTC out of a total of 140 DTC patients managed between 1990 and June 1999. Demographic data, clinicopathological profile, operative and radioiodine ablation therapy details, and follow-up findings were noted. The overall incidence of distant metastases in our series was 20%. Mean age was 48.5 +/- 12.8 years (32.1%patients were < 45 years). Most metastases were detected synchronously (85.7%) and were multiple, with the skeletal system being the commonly affected site. Out of 22 cases having skeletal metastases, 6 patients were young (< 45 years). Though most patients with skeletal metastases had follicular carcinoma (FTC), 4 cases had papillary thyroid cancer (PTC). Near total or total thyroidectomy was done in 26 cases. Sixteen patients required regional lymph node dissection. Resection of metastases was performed in 9 cases.Histopathological diagnosis was PTC, FTC, and poorly differentiated carcinoma in 32.1%, 50.0%, and 17.9% of cases, respectively. Most patients had good symptomatic palliation following administration of I131 therapy. In 17.9% of cases there were locoregional recurrences. There was an overall 28.6% mortality. Two patients expired in the perioperative period. Six others died in follow-up (all within 3-9 months). In contrast to iodine sufficient regions, the incidence of metastases was high; the majority of cases had synchronous, symptomatic skeletal metastases. Skeletal metastases were not infrequent even in cases of PTC and in young patients. One-third of the cases were young. Though survival was poor despite aggressive management, significant symptomatic palliation could be achieved in most cases.     

Combining off pump coronary artery bypass with mitral valve replacement

Background Conventional approach to combined coronary artery bypass grafting (CABG) and mitral valve replacement (MVR) is associated with longer cardiopulmonary bypass (CPB) and aortic cross clamp (ACC) time leading to high operative risk. Methods We conducted a retrospective review of nine consecutive patients undergoing coronary artery bypass grafting/mitral valve replacement combining the off pump technique with cardioplegic arrest. Elective intra aortic balloon pump (IABP) support was instituted in all cases. CABG was first done in all cases without cardiopulmonary bypass support. Mitral valve replacement was then done using conventional cardiopulmonary bypass and cardioplegic arrest using the superior septal approach. Results Nine consecutive patients underwent coronary artery bypass grafting with mitral valve replacement including three patients with acute myocardial infarction. Preoperative echocardiogram revealed a mean ejection fraction (EF) of 38.4 ± 6.0%. Intra aortic balloon pump was inserted in all patients preoperatively. The average number of grafts were 3.0 ± 0.7. Eight patients received bioprosthetic valve while one patient received mechanical prosthesis. The average length of stay in intensive care unit was 3.3 ± 0.5 days. There was no mortality. One patient had superficial wound infection. Conclusion The data suggest that the combined technique (off pump coronary artery bypass grafting and conventional mitral valve replacement) is a safe method to perform coronary artery bypass grafting/mitral valve replacement with minimal morbidity and mortality.     

Calpeptin provides functional neuroprotection to rat retinal ganglion cells following Ca2+ influx

Apoptosis of retinal ganglion cells (RGCs) impairs vision in glaucoma patients. RGCs are also degenerated in multiple sclerosis (MS), resulting in loss of visual perception in MS patients. We examined the involvement of calpain and caspase cascades in apoptosis of the rat retinal ganglion cell line RGC-5 following 24 h of exposure to 250 nM ionomycin (IMN) or 300 units/ml interferon-gamma (IFN-gamma) and then evaluated functional neuroprotection with 2 microM calpeptin (CP, a calpain-specific inhibitor). Morphological and biochemical features of apoptosis were detected in RGC-5 cells following exposure to IMN or IFN-gamma. Fura-2 assay determined significant increases in intracellular free [Ca2+] following exposure to IMN or IFN-gamma. Pretreatment with CP for 1 h prevented Ca2+ influx, proteolytic activities, and apoptosis in RGC-5 cells. Western blot analyses showed an increase in activities of calpain and caspase-12, upregulation of Bax:Bcl-2 ratio, release of cytochrome c from mitochondria, and increase in caspase-9 and caspase-3 activities during apoptosis. Increased caspase-3 activity was also confirmed by a colorimetric assay. Activation of caspase-8 and cleavage of Bid to tBid in RGC-5 cells following exposure to IFN-gamma indicated co-operation between extrinsic and intrinsic pathways of apoptosis. Patch-clamp recordings showed that pretreatment with CP attenuated apoptosis and maintained normal whole-cell membrane potential, indicating functional neuroprotection. Taken together, our results demonstrated that Ca2+ overload could be responsible for activation of calpain and caspase cascades leading to apoptotic death of RGC-5 cells and CP provided functional neuroprotection.     

A rare case of segmental small bowel pneumatosis intestinalis: A case report

Introduction

Pneumatosis intestinalis is a rare condition affecting 0.03% of the population. It has a myriad of aetiological causes and hence presentation can vary immensely. The management of symptomatic pneumatosis intestinalis in an acute and outpatient setting remains a challenge to both physicians and surgeons.

Case presentation

We present a case of a 79 year old who presented in a gastroenterology outpatients department with a history suggestive of intermittent small bowel obstruction associated with abdominal pain aggravated by eating and posture. He was found to have signs suggestive of Marfan''s syndrome. Computed tomography demonstrated extensive pneumatosis intestinalis of the small bowel. Due to deterioration in symptoms, an exploratory laparotomy was performed demonstrating segmental small bowel pneumatosis intestinalis secondary to a hypermobile mesentery.

Conclusion

This case highlights the importance of both surgical and gastroenterology expertise in successfully managing symptomatic pneumatosis intestinalis.     

Excimer laser revascularisation: current indications, applications and techniques

. The ultraviolet pulsed excimer laser (308 nm wavelength) is currently the only laser approved by the FDA for percutaneous intervention in patients with ischemic coronary artery disease. The clinical presentation of the treated patients varies from stable and unstable angina to acute myocardial infarction. Potential advantages of excimer laser revascularisation in acute coronary syndromes and in ischaemic obstructive peripheral vascular disease include concomitant plaque debulking and thrombus removal; absence of systemic lytic state; shortened thrombus clearing time and facilitation of adjunct balloon angioplasty and stenting. Improved understanding of laser–tissue interactions and positive clinical outcomes through the use of safe lasing techniques have led to expansion of indications/applications for laser angioplasty. These include stent restenosis, complex lesions and thrombotic stenoses, bifurcation lesions, balloon failure, total occlusions, focal saphenous vein graft lesions and peripheral arterial obstructions. The excimer laser can be effectively utilised in patients with depressed left ventricular ejection fraction and does not require implantation of a temporary pacemaker as no-reflow phenomenon and severe arrhythmias are rarely encountered. Careful case selection, proper utilisation of equipment and incorporation of efficient lasing techniques play a crucial role in effective and safe cardiovascular laser applications.     

Risk factors for hip fracture in Asian men and women: the Asian osteoporosis study.

The objectives of the Asian Osteoporosis Study (AOS) were to determine risk factors for hip fracture in men and women in four Asian countries, that is, Singapore, Malaysia, Thailand, and the Philippines. A total of 451 men and 725 women (aged 50 years and over) with hip fractures were compared with an equal number of community controls. A standardized questionnaire was administered by interview. The following relative risks (RRs) were found in women and men by multiple logistic regression: dietary calcium intake < 498 mg/day, 2.0 for women (95% CI, 1.5-2.8) and 1.5 for men (95% CI, 1.0-2.2); no load bearing activity in the immediate past, 2.0 for women (95% CI, 1.4-2.7) and 3.4 for men (95% CI, 2.3-5.1); no vigorous sport activities in young adulthood, 7.2 for women (95% CI, 4.0-13.0) and 2.4 for men (95% CI, 1.6-3.6); cigarette smoking, 1.5 for men (95% CI, 1.0-2.1); alcohol consumption 7 days a week, 2.9 for women (95% CI, 1.0-8.6) and 1.9 for men (95% CI, 1.1-3.2); fell twice or more in the last 12 months, 3.0 for women (95% CI, 1.8-4.8) and 3.4 for men (95% CI, 1.8-6.6); a history of fractures after 50 years of age, 1.8 for women (95% CI, 1.1-2.9) and 3.0 for men (95% CI, 1.6-5.6); a history of stroke, 3.8 for women (95% CI, 2.0-7.1) and 3.6 for men (95% CI, 1.8-7.1); use of sedatives, 2.5 for women (95% CI, 1.0-6.3) and 3.0 for men (95% CI, 1.0-9.7); and use of thyroid drugs, 7.1 for women (95% CI, 2.0-25.9) and 11.8 for men (95% CI, 1.3-106.0). Women who were 1.56 m or taller had an RR of 2.0 (95% CI, 1.3-3.0) for hip fracture and men who were 1.69 m or taller had an RR of 1.9 (95% CI, 1.2-3.1) for hip fracture. Based on these findings, primary preventive programs for hip fracture could be planned in Asia.     

The surgical management of aortic root vessel anomalies presenting in adults

Anomalies of the aortic root vessels may present in adults and are common incidental findings during standard vascular imaging. Knowledge of their presentation and management is important for surgeons dealing with vascular pathology within these anomalous vessels. A comprehensive literature search was conducted and a review of the current opinion performed on the embryology, clinical features, and surgical treatment of aortic root vessel anomalies, with particular emphasis on their management in adults. A classification system for aortic arch anomalies based on arch configuration is presented: (1) double aortic arch, (2) right aortic arch, (3) left aortic arch with abnormal branching, and (4) interrupted aortic arch. Anomalies of the aortic root vessels may be classified based on their presence or absence, their anomalous size or course, or their atypical origin, bifurcation, or subsequent branching pattern. A symptomatic aberrant right subclavian artery may be encountered by vascular surgeons, and a right supraclavicular approach would appear the most appropriate method of repair. Knowledge of aortic arch and root vessel anomalies is important for any clinician dealing with cardiothoracic, head and neck, or intracranial pathology. Vascular surgeons may encounter these anomalies during routine practice and may need to deal with their clinical sequelae.     

Role of preoperative carbohydrate loading: a systematic review

INTRODUCTION

Surgical stress in the presence of fasting worsens the catabolic state, causes insulin resistance and may delay recovery. Carbohydrate rich drinks given preoperatively may ameliorate these deleterious effects. A systematic review was undertaken to analyse the effect of preoperative carbohydrate loading on insulin resistance, gastric emptying, gastric acidity, patient wellbeing, immunity and nutrition following surgery.

METHODS

All studies identified through PubMed until September 2011 were included. References were cross-checked to ensure capture of cited pertinent articles.

RESULTS

Overall, 17 randomised controlled trials with a total of 1,445 patients who met the inclusion criteria were identified. Preoperative carbohydrate drinks significantly improved insulin resistance and indices of patient comfort following surgery, especially hunger, thirst, malaise, anxiety and nausea. No definite conclusions could be made regarding preservation of muscle mass. Following ingestion of carbohydrate drinks, no adverse events such as apparent or proven aspiration during or after surgery were reported.

CONCLUSIONS

Administration of oral carbohydrate drinks before surgery is probably safe and may have a positive influence on a wide range of perioperative markers of clinical outcome. Further studies are required to determine its cost effectiveness.