Effect of nitration on protein tyrosine phosphatase and protein phosphatase activity in neuronal cell membranes of newborn piglets

Protein tyrosine phosphatase predominantly determines the status of protein tyrosine kinase-dependent phosphorylation of specific proteins and controls the survival and death of neurons. Previous studies have shown that protein tyrosine phosphatase activity is decreased during hypoxia in cortical membranes of the newborn piglet. We have also shown that nitric oxide (NO) free radicals are generated during hypoxia, and may result in modification of protein tyrosine phosphatase via peroxynitrite-mediated modification. The present study tests the hypothesis that the hypoxia-induced decrease in protein tyrosine phosphatase activity is NO-mediated. To test this hypothesis, in vitro experiments were conducted by measuring protein tyrosine phosphatase activity in the presence of an NO donor, sodium nitroprusside (SNP), or peroxynitrite. Since 3-nitrotyrosine is produced as a consequence of peroxynitrite reactions, we have also examined the effect of 3-nitrotyrosine on protein phophatase activity. Cerebral cortical P(2) membranes were prepared from seven normoxic newborn piglets and each sample was divided into three aliquots: a control group, a SNP group (exposed to 200 microM SNP), and a peroxynitrite group (exposed to 100 microM peroxynitrite). Protein tyrosine phosphatase activity was determined spectrophotometrically in the presence or absence of 2 microM bpV(phen), a highly selective inhibitor of protein tyrosine phosphatase. The protein tyrosine phosphatase activity was 198+/-25 nmol/mg protein/h in the normoxic group, 177+/-30 nmol/mg protein/h in the SNP group (p=NS versus normoxic) and 77+/-20 nmol/mg protein/h in the peroxynitrite group (p<0.001 versus normoxic). The results show that peroxynitrite but not SNP exposure results in decreased protein tyrosine phosphatase activity in vitro. Furthermore 3-nitrotyrosine (100 microm), a product of peroxynitrite, decreased the enzyme activity from 926+/-102 to 200+/-77 (p<0.001). We conclude that protein tyrosine phosphatase regulation is mediated by peroxynitrite. We propose that hypoxia-induced NO production leading to peroxynitrite formation is a potential mechanism of protein tyrosine phosphatase inactivation in vivo. The NO-induced decrease in protein tyrosine phosphatase and protein phosphatase activity, leading to Bcl-2 protein phosphorylation and loss of its antiapoptotic activity may be a NO-mediated mechanism of programmed cell death in the hypoxic brain.     

Comparison of Vitek Yeast Biochemical Card with conventional methods for speciation of Candida

The ability of the Vitek Yeast Biochemical Card to identify yeast isolates was compared with conventional methods. Of the fifty yeast isolates tested same species identification was obtained in thirty-four isolates. The Vitek yeast biochemical card identified 13 isolates which could not be identified by the conventional tests. Though the Vitek Yeast biochemical card gave a good rapid identification the high cost of each test severely limits its routine use in most of the laboratories.     

Immobilisation stress induced analgesia in diabetic rats

Stress is known to produce analgesia. The pain threshold is altered in diabetes. We studied the effect of 1 hr of immobilisation stress on pain threshold in male Wistar rats. The same effect was tested in streptozotocin induced diabetic rats. The pain threshold of tail flick, vocalisation and vocalisation after discharge increased in the control group after the stress procedure. Significant analgesia was also obtained in diabetic rats, for flick and after discharge pain threshold. However the vocalisation threshold was not altered, probably due to the antagonistic action of glucose on opiate receptor at the level of brain stem.     

Neuro-otological profile of Episodic Vertigo

Episodic Vertigo Comprises a large group of patients seen in any neurootology unit. A total of 118 subjects were reviewed who attended the neurootology unit. Vertigo of shorter duration was noted in 78 and of longer duration in 40 cases. 51 cases showed bilateral neurosensory deafness, 15 cases had bilateral and another one case had unilateral conductive loss. Spinovestibular tests were abnormal in all cases of vertigo of short duration but only 29 cases showed abnormal reflex in patients with a long duration of illness. Thermal vestibulometry revealed hyporeflexia in 33 cases, directional preponderance in 30 cases and 4 cases showed hyperreflexia 28 cases had peripheral lesions while 81 cases had central lesions. The acute cases showed significant improvement on follow up except cases with abnormality in thermal vestibulometry . The cases with positional nystagmus showed improvement with head and body balance exercises expect in those who received treatment with vestibulosedative and vestibular suppersive drugs. Hearing loss remained the same except in patients with middle ear disorders.     

Persistent congenital milia with naevus spilus

We are reporting a case of solitary persistent left-sided endoareolar congenital milia in association with no serious malformation or abnormality of any structure except the presence of naevus spilus, on the back of the ipsilateral forearm.     

Nutritional status of pavement dweller children of Calcutta City

Pavement dwelling is likely to aggravate malnutrition among its residents due to extreme poverty, lack of dwelling and access to food and their exposure to polluted environment. Paucity of information about nutritional status of street children compared to that among urban slum dwellers, squatters or rural/tribal population is quite evident. The present study revealed the magnitude of Protein Energy Malnutrition (PEM) and few associated factors among a sample of 435 underfives belonging to pavement dweller families and selected randomly from clusters of such families, from each of the five geographical sectors of Calcutta city. Overall prevalence of PEM was found almost similar (about 70%) to that among other 'urban poor' children viz. slum dwellers etc., but about 16% of them were found severely undernourished (Grade III & V of IAP classification of PEM). About 35% and 70% of street dweller children had wasting and stunting respectively. Severe PEM (Grade III & IV) was more prevalent among 12-23 months old, girl child, those belonged to illiterate parents and housewife mothers rather than wage earners. It also did increase with increase of birth rate of decrease of birth interval.     

Population dynamics of Anopheles culicifacies and malaria in the tribal area of central India.

A longitudinal study (1993-94) on malaria was conducted in Dungaria, a typical forest fringe tribal village in Mandla district of central India (Madhya Pradesh). Our initial objective was to obtain in-depth baseline data on malaria transmission in the tribal village to elucidate the factors responsible for persistent malaria in the area and thereby to help in formulating an improved malaria control program. Anopheles culicifacies Giles was the predominant vector of malaria, although Anopheles fluviatilis James were recorded in small numbers. The transmission season was from May to November. Analysis of the malaria cases revealed hyperendemic malaria, with Plasmodium falciparum the predominant species. The prevalence of Plasmodium vivax was mainly in the summer and that of P. falciparum in autumn. The study suggested that a number of factors were responsible for the continuation of malaria transmission in the village.     

Diagnostic significance of vestibular tests in posterior fossa tumefaction

Abnormal vestibular responses are observed more frequently in cerebellar and Brain stem lesions than in cerebello-pontine angle tumours. The direction of spontaneous, positional, positioning nystagmus or caloric induced directional preponderance are not quite reliable in topographical localisation of these lesions. Hyperreflexia and dysarhythmia of thermally induced nystagmus are reasonably reliable evidences of affections of cerebellum or its connections. The deficiency of the fast phase of nystagmus indicates a bulbopontine lesion.