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Biomedical subjects

N K Misra

Publications and source records attributed to N K Misra.

28 records · Page 2Linked to original sources
PubMed1973

Neurones in the somatosensory cortex of the rat responding to scrotal skin temperature changes.

1. In rats the scrotal temperature was raised or lowered with a water-perfused thermode while micro-electrode recordings were made of unit activity in the somatosensory (SI) cortex. The electrodes were inserted in the area where the largest evoked potentials had been found from electrical stimulation of the scrotum.2. Changes in firing rate of cortical neurones were found only in the scrotal temperature range of 32-41 degrees C. Within this range 40% of all the cells tested were excited or suppressed by skin warming. At temperatures above or below this range, activity was not affected. Most of the cells responded just to temperature and only 14% were also excited by touch.3. Raising temperature in the range 33-41 degrees C caused 83% of the thermally responding cells to decrease their firing rate and 17% to increase their rate. Individual neurones showed a sudden and maintained change in their activity for scrotal temperature increases of only 2, 1 or even 0.5 degrees C. Mean firing rates changed several-fold with these temperature increases and further warming did not change the rate. These step-like changes in firing rate were found at different points over the whole skin temperature range of 33-41 degrees C but most were between 35 and 39 degrees C.4. For a given neurone the step-like change in activity occurred once its critical temperature was reached, irrespective of whether this was achieved by a step increase of skin temperature over 1-2 sec, or by a slow ramp increase lasting several minutes.5. The results are very similar to those found in the thalamus (preceding paper), but the proportions of cortical cells which were excited or suppressed on skin warming were the reverse of the proportions seen in the thalamus.

Animals↗
PubMedDate not supplied

Adrenocortical reserve and morphology in tuberculosis.

Ninety seven patients (63 males, mean age 31.8 years, SD 2.3) with various forms of tuberculosis were studied. All of them were HIV negative. Thirty normal control subjects (16 males, mean age 36.4 years, SD 1.8) were also studied. Fifty-eight of the 97 patients (59.8%) were malnourished (BMI < 18 kg/m2). The mean basal serum cortisol was lower in the TB group (n = 91) (351 nmol/1; SD 150) as compared to the normal control group (n = 8) (402 nmol/1; SD 93) but this difference did not attain statistical significance. Following administration of synthetic ACTH (cosyntropin), the 30 and 60 minutes mean serum cortisol values in the TB group were significantly lower as compared to the normal control group (p < 0.05). Forty five of the 91 patients (49.5%) who underwent the ACTH stimulation test had compromised adrenal reserve. Fourteen of the 86 patients (16.3%) in whom adrenal morphology was studied revealed adrenal gland enlargement on abdominal CT scan. ACTH stimulation was done in 12 of these 14 patients and eight of them had compromised adrenal reserve. Repeat ACTH stimulation done six months to one year after treatment in 13 patients revealed significantly increased 30 minutes (p < 0.05) and 60 minutes (p < 0.05) serum cortisol values. While nine of these 13 patients were negative responders before treatment, only three of them had evidence of compromised adrenal reserve after one year of antituberculosis treatment, (p < 0.05). Serum cortisol values in patients with drug-sensitive and drug-resistant tuberculosis did not differ significantly. Patients with drug-resistant tuberculosis had a higher prevalence of adrenal gland enlargement (7 of the 30) as compared to those with drug-sensitive tuberculosis (7 of the 56) (p = NS). Subclinical adrenal insufficiency is prevalent in a significant number of patients with both drug-sensitive and drug-resistant tuberculosis, and in some of these it is associated with adrenal gland enlargement. The compromised adrenal reserve and enlargement seem to reverse with therapy.

Adrenal Cortex Hormones↗
PubMedDate not supplied

Cold abscess due to malignant pleural mesothelioma.

A middle aged male presented to us with a cold abscess on the left side of chest which later proved to be a malignant pleural mesothelioma. The clinical, radiological and histopathological findings have been discussed.

Biopsy↗
PubMedDate not supplied

Transsynaptic neuronal degeneration of optic nerves associated with bilateral occipital lesions.

A case is reported of a 9-year old male who presented with abnormal behaviour and progressive diminution of vision. Pupils were middilated in both eyes but the pupillary reflexes were preserved. Fundus examination revealed a bilateral optic atrophy and radiological investigations showed a bilateral occipital calcification. We hereby document a case of retrograde transsynaptic neuronal degeneration of the visual system secondary to bilateral occipital lesions. Transsynapptic neuronal degeneration of optic nerves consequent to occipital lobe lesions is a rare phenomenon. Experimentally occipital lobe ablation in non-human primates has been shown to result in optic atrophy. Herein, we document a case of retrograde transsynaptic neuronal degeneration of the visual system secondary to bilateral occipital lesions.

Brain Diseases↗
PubMedDate not supplied

Albendazole in neurocysticercosis.

BACKGROUND: In India, parenchymatous cysticercus cysts are more common than the meningeal racemose variety which are seen frequently in Latin America. Reports from Mexico suggest that albendazole is effective in the treatment of neurocysticercosis. We, therefore, studied whether this drug changed the natural course of neurocysticercosis in India. METHODS: In a randomized, double-blind, placebo controlled study, we allocated 29 consecutive patients (22 men and 7 women) with multiple cystic lesions on computed tomography (CT) of the head suggestive of cysticercosis to 7 days treatment with albendazole (15 mg/kg/day) or placebo. CT scans were repeated at the end of treatment and 1 and 3 months later to assess the number of cysts and extent of oedema. RESULTS: Sixteen patients received albendazole and 13 placebo. No change was seen at the end of one week. At 3 months, 14 patients in the albendazole group and 10 in the placebo group showed more than 25% reduction in the number of lesions. The difference between the two groups was not significant. CONCLUSION: Albendazole given in a dose of 15 mg/kg/day for 1 week does not change the natural course of neurocysticercosis.

Adolescent↗
PubMedDate not supplied

Distribution of vascular lesions in ischaemic stroke: a magnetic resonance angiographic study.

BACKGROUND: Carotid endarterectomy is now an accepted modality for reducing the threat of recurrence of ischaemic strokes in patients with severe carotid artery stenosis. However, the incidence of carotid artery stenosis, and hence the applicability of carotid endarterectomy in the Indian population is not known. We conducted a prospective study to detect and quantify extracranial and intracranial arterial lesions using magnetic resonance angiography in consecutive patients with ischaemic strokes. METHODS: All patients with recent onset of ischaemic stroke (< 4 months) had a magnetic resonance angiography done to evaluate the neck vessels as well as the circle of Willis and its branches. The degree of stenosis of the internal carotid or common carotid artery was measured according to the criteria described by the North American Symptomatic Carotid Endarterectomy Trial (NASCET) collaborators. The site and extent of the extracranial and intracranial arterial lesions were correlated with the clinical features and the pattern of infarcts on magnetic resonance imaging or computerized tomographic scan of the brain. RESULTS: The magnetic resonance angiography was abnormal in 56 out of 100 patients included in the study. Severe stenosis (> 70%) of the extracranial carotid arteries was seen in 26 patients. Lesions suitable for carotid endarterectomy were present in only 11 patients (42.3% of those with severe stenosis). CONCLUSION: Our results are in contrast to those reported from western countries where the likelihood of a surgically correctable lesion being present is 60%-70%. We found operable lesions in only 11%. Intracranial atherosclerotic disease causing strokes is probably more common in India. Therefore, although carotid endarterectomy is the only accepted surgical procedure for secondary prophylaxis of stroke, there is a need to find an alternative surgical intervention for the predominantly intracranial pathology found in the Indian population.

Adolescent↗