Role of the cell recognition molecule, cognin, in GABAergic differentiation in chick retina

Previous work showed that GABAergic differentiation in developing chick retina depends on insulin and cell interactions. Here, we investigated whether it depended on cell signaling mediated by retina cognin, a 50 kDa cell recognition molecule. Cognin mediates cell adhesion in vitro and occurs on retinal neurons that become both GABAergic and cholinergic. We investigated two markers of GABAergic differentiation: glutamate decarboxylase (GAD) activity and high-affinity GABA uptake. Both increase during differentiation of retinal neurons in culture and can be easily measured. We blocked cognin-mediated cell signaling with cognin antibody and found a reduction of the developmental increase in GAD activity in cultures of retinal neurons from 7 and 11 day chick embryos. There was no reduction of high-affinity GABA uptake. This suggested that cognin-mediated signaling was necessary for the normal developmental increase in GAD but not for high-affinity GABA uptake. These results contrasted with our previous observations on cholinergic differentiation in cultured retinal neurons. We found that cognin antibody blocked the normal developmental increase in choline acetyltransferase (ChAT) only if the cells were exposed before embryonic day 7. Thus, while both GAD and ChAT activity appear to be controlled by cell signaling involving cognin, the periods of developmental sensitivity for the two differentiation markers are different. Antibodies to other adhesion molecules, Ng-CAM, and N-cadherin, did not similarly affect GAD activity. Antibodies to laminin at a 10-fold higher concentration inhibited GAD activity only in early embryonic retina. Tests for protein synthesis and “housekeeping” enzyme activity demonstrated that the cognin antibody effect was selective for neuronal differentiation pathways. Thus, GABAergic differentiation in developing retina is sensitive to cell signaling mediated in part by cognin.     

Experience with the International League Against Epilepsy Classifications of Epileptic Seizures (1981) and Epilepsies and Epileptic Syndrome (1989) in Epileptic Children in a Developing Country

Four hundred eighty-three epileptic children attending the Pediatric Epilepsy Clinic at Bai Jerbai Wadia Hospital for Children, Bombay, India were classified according to the International League Against Epilepsy (ILAE) classification of epileptic seizures (1981) and epilepsies and epileptic syndromes (1989). The predominant seizures were partial (53.6), generalized (40.3%), and unclassifiable (6%). In epilepsies and epileptic syndromes, 55.3% were partial, 27% were generalized, 13.5% were undetermined, and 4.1% were special syndromes. Although our results were similar in many respects to those of other reported series, some differences were observed in the incidence of partial and generalized seizures, and partial and generalized epileptic syndromes and their subgroups, such as idiopathic, symptomatic, and cryptogenic partial syndromes, idiopathic generalized syndromes, and symptomatic specific syndromes. These differences are probably due to different age limits, methods of case ascertainment and inclusion criteria, different genetic and environmental factors, variable interpretation of clinical and EEG features, and lack of facilities for investigation in developing countries. Despite various limitations, we were able to classify most cases; the ILAE classification can be used in developing countries so that comparison can be made with other studies.     

Giant right atrial diverticulum: an unusual cause of Wolff-Parkinson-White syndrome

A case of a giant right atrial diverticulum associated with neonatal supraventricular tachycardia is reported. The electrocardiogram in sinus rhythm showed pre-excitation that may have been caused by the right atrial diverticulum adhering to the right ventricle.     

The problem of neck relapse in early stage supraglottic larynx cancer

We reviewed the records of 104 patients with Stage T1NO or Stage T2NO epidermoid carcinoma of the supraglottic larynx treated between 1965 and 1979. In 79 patients, surgery was the only type of initial treatment. These 79 patients are the subjects of this report. Forty-eight (61%) of these patients were treated by total laryngectomy, whereas 31 (39%) had a partial laryngectomy. An elective unilateral radical neck dissection was performed on 31 patients considered at high risk, but metastatic disease was found in the dissected side of the neck histologically in only 32% (ten of 31) of these patients. The minimum follow-up period was 5 years and the maximum was 20 years. Twenty-nine percent of the patients (23 of 79) experienced a neck relapse. The neck relapse rate was the same whether the patients did or did not have an elective radical neck dissection. Among the patients who experienced a neck relapse, 65% (15 of 32) have died of the cancer. Among those who did not experience a neck relapse, none (zero of 56) have died of the cancer (P less than 0.01). These results indicate that in surgically treated patients with early stage supraglottic larynx cancer, neck relapse was the major cause of failure associated with death from cancer. Strategies for decreasing the relapse rate are discussed.     

Selective Use of Older Adults in Right Lobe Living Donor Liver Transplantation

Many centers are reluctant to use older donors (>44 years) for adult right-lobe living donor liver transplantation (RLDLT) due to concerns about possible increased morbidity in donors and poorer outcomes in recipients. Since 2000, 130 adult RLDLTs have been performed at our institution. Recipients were divided into those who received a right lobe graft from a donor ≤age 44 (n = 89, 68%; median age 30) and those who received a liver graft from a donor age >44 (n = 41, 32%; mean age 52). The two donor and recipient populations had similar demographic and operative profiles. With a median follow-up of 29 months, the severity and number of complications in older donors were similar to those in younger donors. No living donor died. Older donor allografts had initial allograft dysfunction compared to younger donors. Complication rates were similar among recipients in both groups but there was a higher bile duct stricture rate with older donor grafts (27% vs. 12%; p = 0.04). One-year recipient graft survival was 86% for older donors and 85% for younger donors (p = 0.95). Early experience with the use of selected older adults (>44 years) for RLDLT is encouraging, but may be associated with a higher rate of biliary complications in the recipient.     

Endoscopic pituitary surgery - a. beginner’s guide

Endonasal endoscopic surgery is now the preferred technique to tackle pituitary tumours. Our paper describes the stepwise endoscopic approach for surgeons embarking on pituitary surgery. It also highlights the common pitfalls encountered during surgery and the ways to avoid them. One must proceed in a gradual step- wise manner starting from simple exposure of the sphenoid sinus to complete endoscopic tumour removal so us to gain the neurosurgeon’s confidence as well as develop our own skills, confidence and ability to tackle complications. We use the endonasal paraseptal trans- sphenoidal approach. Surgery begins with gentle packing between the middle turbinate and septum to expose the anterior sphenoid wall and expose the sphenoid astium. The ostitum is then widened inferiorly and onto the opposite side to expose both sphenoid sinuses. The inter- sphenoid sinus and necessary mucosa is removed to expose the sella. We then use a bone flap technique or punches to open the sella. After incising the dura, tumour is removed with a suction curette. An endoscope holder facilitates the operation. The bone flap is replaced at the end of surgery to reconstruct the sella. This is especially important if a CSF leak is present. Nasal packing is usually not required.