Acetylcholine produces stimulus-specific receptive field alterations in cat auditory cortex

Frequency receptive fields (RFs) were determined before and after pairing iontophorectic administration of acetylcholine (ACh) with a repeated single-frequency stimulus in the auditory cortex of barbiturate-anesthesized cats. In 58% of the cells, the paired ACh + tone treatment produced subsequent alterations of frequency RFs. In half of these cases, the RF modifications were highly specific to the frequency that had been paired with ACh. Atropine antagoized the frequency-effects of ACh, suggesting that they were mediated via muscarinic cholinergic receptors.     

Synaptic potentials and effects of amino acid antagonists in the auditory cortex

Neurons of in vitro guinea pig and rat auditory cortex receive a complex synaptic pattern of afferent information. As many as four synaptic responses to a single-stimulus pulse to the gray or white matter can occur; an early-EPSP followed, sequentially, by an early-IPSP, late-EPSP, and late-IPSP. Paired pulse stimulation and pharmacological studies show that the early-IPSP can modify information transmission that occurs by way of the early-EPSP. Each of these four synaptic responses differed in estimated reversal potential, and each was differentially sensitive to antagonism by pharmacological agents. DNQX (6,7-dinitroquinoxaline-2,3-dione), a quisqualate/kainate receptor antagonist, blocked the early-EPSP, and the late-EPSP was blocked by the NMDA receptor antagonist APV (D-2-amino-5-phosphonovalerate). The early-IPSP was blocked by the GABA-a receptor antagonist bicuculline, and the late-IPSP by the GABA-b receptor antagonists 2-OH saclofen or phaclofen. Presentation of stimulus trains, even at relatively low intensities, could produce a long-lasting APV-sensitive membrane depolarization. Also discussed is the possible role of these synaptic potentials in auditory cortical function and plasticity.     

Chronic subdural haematoma associated with nontraumatic CSF rhinorrhea: a management challenge.

We report an unusual case of chronic subdural haematoma (CSH) associated with cerebrospinal fluid (CSF) rhinorrhoea emphasizing the importance of managing both conditions simultaneously. A 59- year-old man presented with watery discharge from the right nostril, of 2 months duration. MRI of the brain showed a CSH in the left fronto-parietal region with significant mass effect. There was an arachnoidocoele with a defect in the planum sphenoidale. He first underwent a burr hole evacuation of the CSH following which the CSF rhinorrhea did not subside, even with bed rest. Transnasal endoscopic closure of the CSF dural fistula was done. On the first post-operative day, he was disoriented and a CT scan showed a recollection of the subdural haematoma that required repeat evacuation. The patient was asymptomatic at discharge. To our knowledge this is the first reported case of CSF rhinorrhoea associated with CSH. Simultaneous closure of the CSF dural fistula at the time of evacuation of a coexisting CSH would be the optimal management.     

A successful model of small bowel autotransplantation in the dog

Experimental small bowel transplantation has continued to be a complex procedure with high mortality. We investigated the technical aspects of small bowel transplantation in an effort to define a procedure that would result in an improved survival rate. Three methods of graft harvesting were examined in a model of canine small bowel autotransplantation. Harvesting the graft by first flushing with room-temperature lactated Ringer's followed by iced lactated Ringer's resulted in the best preservation and subsequently the best survival rate (71%). Flushing with iced lactated Ringer's alone resulted in survival rates of 22 and 50% in two additional groups. We also investigated two methods of graft reanastomosis. Although either venous drainage regimen appears to be suitable, graft venous reanastomosis to the host portal vein resulted in a slightly higher postoperative weight than reanastomosis to the host inferior vena cava. A model of small bowel transplantation with a high long-term survival rate has been developed. This model can now be applied to studies of the various physiological aspects of small bowel transplantation.     

Impact of nutritional status on peritonitis in CAPD patients.

OBJECTIVE: To determine the impact of nutritional status on peritonitis in patients on continuous ambulatory peritoneal dialysis (CAPD) in a developing country. METHODS: 56 patients with end-stage renal disease on CAPD were randomly selected for this study. These patients were assessed for nutritional status and peritonitis episodes. Nutritional parameters were assessed by anthropometry, diet, body mass index (BMI), Nutritional Risk Index (NRI), serum albumin level, and Subjective Global Assessment (SGA). Based on SGA, patients were categorized into either group 1 (malnutrition, n = 31) or group 2 (normal nutritional status, n = 25). Peritonitis was considered the primary outcome and was compared between the two groups. RESULTS: Demographic profiles, Kt/V, creatinine clearance, and mean follow-up of the two groups were similar. Number of peritonitis episodes was significantly higher in patients with malnutrition (25/31) compared to patients with normal nutritional status (4/25) (p = 0.001). Mean peritonitis rate per patient per year was also significantly higher in patients with malnutrition (0.99 +/- 1.07) compared to patients with normal nutritional status (0.18 +/- 0.42) (p = 0.007). On univariate analysis, malnutrition based on SGA (p = 0.009), NRI (p = 0.02), serum albumin level (p = 0.005), and calorie intake (p = 0.006) was a significant predictor of peritonitis. On multivariate Cox regression analysis, only SGA (p = 0.001, odds ratio 0.08, 95% confidence interval 0.02-0.36) was found to be a significant predictor of peritonitis. On general linear model, the observed power of prediction of peritonitis was 0.96 based on SGA. On Kaplan-Meier survival analysis, peritonitis-free survival in patients with normal nutrition (42 months) was significantly higher compared to patients with malnutrition (21 months) based on SGA (log rank p = 0.003). CONCLUSION: We conclude that peritonitis rate is high in patients with malnutrition and that malnutrition indices, especially SGA, can predict the peritonitis rate in CAPD patients.     

Transurethral resection of the prostate with local anesthesia in 100 patients

We performed transurethral resections of the prostate in 100 patients under local anesthesia supplemented when appropriate by intravenous medication. In the first part of the study (40 patients) local anesthesia was infiltrated into the prostate transurethrally only, while in the second part (60 patients) infiltration was performed transurethrally and perineally. Prostate sizes ranged from 5 to 50 gm., and pain control was excellent in the majority of the patients, especially when perineal infiltration was added to the procedure. Of the patients 98 per cent said they would do it again, no patient required conversion to general anesthesia and there were no significant complications relating to the anesthesia. Local anesthesia with intravenous supplementation can be performed successfully in the majority of the patients with small to moderately sized prostate glands.