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Biomedical subjects

S C Sharma

Publications and source records attributed to S C Sharma.

At least 325 records · Page 18Linked to original sources
PubMed1977

Visual function in goldfish with unilateral and bilateral tectal ablation.

Following complete bilateral tectal ablation, the ability to detect light recovers in about three weeks. The non-tectal retinal connections which may mediate detection are about one log unit less sensitive than the retinotectal connections. At moderate illumination levels, tectumless fish do not react visually to objects. Tectumless fish integrate luminous flux over a very wide area (at least 25 degrees diameter) while the critical diameter for the normal in this experiment is smaller. Subcortical structures may mediate the interocular transfer of a brightness discrimination. The ipsilateral retinotectal projection following unilateral tectal removal is functional, with normal sensitivity to detection of light.

Animals↗
PubMed1977

Retinotectal projection of the adult winter flounder (Pseudopleuronectes americanus).

The winter flounder shifts the orinetation of its body 90 degrees at metamorphosis so that its left side is functionally ventral and its right side functionally dorsal. Concomitantly the left eye migrates onto the right side. The net result of these complex metamorphic changes is that the dorsoventral axes of the visual fields are perpendicular to the body rather than parallel as in most other teleosts. The developing flatfish may provide a resource for studying the formation of neural connections, for the change in orientation may necessitate some shift in connections in visuomotor pathways. As a baseline for developmental studies, we have established the retinotectal projection in adult winter flounder by means of anatomical tracing techniques (autoradiography and degeneration staining) and electrophysiological mapping techniques. The histological pattern of retinal afferents to the tectum is similar to that of other teleosts; afferents are confined to the superficial white and gray zone, with a few fibers coursing in the deep white zone. Electrophysiological mapping shows that the visuotectal projection is complete over the entire extent of the tectum, symmetrical for right and left fields and patterned normally.

Animals↗
PubMed1977

The effect of orciprenaline sulphate on the in vitro production of postaglandins E and F by the guinea pig uterus.

The effect of orciprenaline sulphate on the in vitro production of PGs E and F by guinea pig uterine tissue homogenates has been investigated. Estmations of PGs were carried out using sensitive radioimmunoassay techniques. The results indicated that orciprenaline can effectively reduce the in vitro yield of PGs E and F from guinea pig uterine tissue. This could in turn be due to an inhibitory effect of orciprenalline on PG formation or due to stimulation of PG breadkdown by the drug. The implications of these results in relation to premature labour are discussed.

Animals↗
PubMed1977

Cord blood porphyrins. A quantitative assay in newborn infants.

A quantitative assay of free erythrocyte porphyrins was done in umbilical cord blood of 30 newborn babies by a spectrophotometric method. The mean value of free erythrocyte protoporphyrin in umbilical cord blood was found to be 74.58 microng/100 ml packed erythrocytes and that of free erythrocyte coproporphyrin to be 0.77 microng/100 ml packed erythrocytes with a standard deviation of +/-29.99 and +/-1.48 respectively. Relationship between free erythrocyte protoporphyrin and free erythrocyte comproporphyrin and their correlations with birth weight and sex of the newborn baby were found to be statistically significant.

Birth Weight↗
PubMed1977

Changes in transthoracic electrical impedance at high altitude.

Mean transthoracic electrical impedance (impedance) which is inversely related to intrathoracic extravascular fluid volume was measured in 121 normal healthy volunteers at sea-level and at 3658 metres altitude. Fifty (group A) reached the high altitude location after an hour's journey in a pressurised aircraft. Twenty-five (group D) underwent slow road ascent including acclimatisation en route. Thirty permanent residents (group B) and 16 temporary residents at high altitude (group C) were also studied. Serial studies in the 30 subjects of group A who developed symptoms of high altidue sickness showed a significant decrease of impedance up to the fourth day of exposure to high altitude which later returned to normal. The 4 volunteers who developed severe symptoms showed the largest drop in impedance. A case of acute pulmonary oedema developing at 4300 metres showed an impedance value of 24-1 ohms on admission. After effective treatment the impedance increased by 11-9 to 36-0 ohms. Twenty asymptomatic subjects of group A and 25 of group D showed a small average increase in impedance values at high altitude. These obstructions suggest that measurement of transthoracic electrical impedance may be a valuable means of detecting incipient high altitude pulmonary oedema.

Acclimatization↗
PubMed1977

Catecholamines and free fatty acids in myocardial infarction and angina.

Total urinary catecholamines and plasma free fatty acids (FFA) were estimated serially in 50 patients with myocardial infarction (A) and in 27 cases of angina (B). A group of 24 normal healthy subjects (C) were also studied as controls. Catecholamines were significantly high (p is less than 0.001) in group A in the first 48 hours after infarction as compared to group C. Group B did not show significant variation from the normals (C). FFA also tended to increase only in group A in the first 48 hours. Both the parameters had returned to normal by 72 hours. The significance of the findings is discussed.

Acute Disease↗
PubMed1977

Platelet adhesiveness in young patients with ischaemic stroke.

A significant increase in platelet adhesiveness was observed in 13 patients who developed ischaemic stroke at high altitude and in 43 patients who developed stroke at low altitude when compared with a similar group of normal healthy volunteers. Eighty-eight percent of the patients were below the age of 40 years. The role of platelet adhesiveness in the pathogenesis of cerebral schaemia in young patients is discussed.

Adolescent↗
PubMed1977

Effect of high-altitude exposure for 10 days on stroke volume and cardiac output.

Resting stroke volume and cardiac output of 50 normal healthy sea-level residents (group A) were estimated by the noninvasive technique of electrical impedance plethysmography. They were then airlifted to an altitude of 3,658 m and serial estimations carried out at 0-4 h and 5-8 h and on the 2nd, 3rd, 4th, 5th, and 10th days. The subjects were brought back to sea level and studied for up to 5 days. Thirty permanent residents of high altitude (group B) and sixteen lowlanders temporarily resident at high altitude (group C) were also subjected to similar studies. It was found that resting stroke volume and cardiac output of group A started falling immediately on arrival at high altitude, reached the minimum on the 3rd day and tended to improved on the 4th and 5th day, but showed a secondary fall on the 10th day. The reduction in stroke volume in this group was not fully compensated by tachycardia. On return to sea level the cardiac output normalized immediately, the stroke volume on the 2nd day. At sea level goup A had values similar to group B and at high altitude to group C.

Adult↗
PubMed1977

Urinary catecholamine excretion on induction to high altitude (3,658 m) by air and road.

In a preliminary pilot study we had reported a significant difference in urinary catecholamine excretion between symptomatic and asymptomatic individuals inducted to high altitude by air. The present study covers slower induction by road; 25 lowlanders ascended from 1,800 to 3,658 m in 50 h and 33 similar subjects covered the journey in 6 h. They were studied according to the protocal used in the initial study. None of the 58 subjects inducted by road developed symptoms of high-altitude illness. Their urinary catecholamine excretion remained normal during the 10 days' stay at high altitude. These findings lend support to our earlier contention that there might be a relationship between increased sympathoadrenal activity and high-altitude illnesses.

Adult↗