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Biomedical subjects

S K Manchanda

Publications and source records attributed to S K Manchanda.

At least 37 records · Page 2Linked to original sources
PubMed1988

Midbrain cholinergic mechanisms regulating cardiovascular responses during hypothalamic defence reaction.

1. Hind limb blood flow and arterial blood pressure were recorded during aggressive behaviour induced on electrical stimulation of the anterior hypothalamic area and the central gray, in anaesthetised cats. 2. Bilateral microinfusions of atropine sulphate (20 ug/ul) were made in the midbrain central gray, and the effect on the behavioural and cardiovascular components recorded. 3. Atropine sulphate was found to decrease the hind limb vascular conductance obtained on stimulation of the hypothalamic and the midbrain defence areas. 4. It was found that the recovery of the behavioural components of aggression required at least 1-5 days as compared to the cardiovascular components which reappeared after 3 weeks of atropine sulphate microinfusions. 5. These results suggest that although the cholinergic muscarinic mechanisms play an important role in eliciting both the behavioural and the cardiovascular responses from the same site, yet the two mechanisms may operate differently.

Aggression↗
PubMed1988

Midbrain cholinergic mechanisms in elicitation of hypothalamic aggressive responses in cats.

1. Electrodes were implanted stereotaxically in the central gray, and the anterolateral regions of the hypothalamus, in chronically prepared cats. 2. The affective attack behaviour elicited on electrical stimulation of the hypothalamic and the midbrain regions was recorded in the caged animals. 3. Bilateral microinfusions of atropine sulphate were given in the central gray and the effect on the midbrain and the hypothalamic responses studied. 4. Cholinergic blockade by atropine sulphate raised the threshold of many of the components of attack behaviour obtained on stimulation of the central gray, and from the anterior hypothalamic regions. 5. Muscarinic receptors may be playing an important role in the central gray regions for the modulation of the aggressive responses from the hypothalamus.

Aggression↗
PubMed1988

The attitudes of medical students to the objective structured practical examination.

The objective structured practical examination (OSPE) together with the classical practical examination (CPE) form the basis for evaluation of laboratory teaching at the All India Institute of Medical Sciences, New Delhi. Students' attitudes to OSPE and CPE were assessed by preparing a questionnaire containing 32 item statements on Likert's 5-point scale (LS) and 11 bipolar adjectives on Osgood's 7-point Semantic Differential Scale (OSDS). The questionnaire was administered to 50 medical undergraduates before their final examination. Forty-two (84%) students responded to the questionnaire. The LS showed high internal consistency and validity. Attitude scoring on LS and OSDS revealed a high degree of correlation. The majority of students showed a positive attitude to OSPE, and high-rank students had a greater intensity of positive attitude. OSPE was rated as a reliable, effective, useful, interesting and challenging examination, although considered taxing, mentally and physically. The students preferred a combination of OSPE and CPE as in the present system to a complete change-over to the OSPE. The item analysis of the questionnaire is discussed.

Attitude of Health Personnel↗
PubMed1987

Effect of hCG on protein synthesis and progesterone production in the bovine luteal cells.

The study was carried out to investigate whether the luteal steroidogenesis in response to tropic stimulus is mediated through de novo synthesis of protein(s). Luteal cell suspension was prepared by collagenase-DNAse treatment of the bovine corpora lutea, weighing 4-6 g. Cells equivalent to 250 micrograms of protein were incubated in a total volume of 550 microliter of medium 199 with or without various test substances. Production of progesterone by the luteal cells was stimulated by hCG in a dose dependent manner. Incorporation of 3H-leucine into the cellular proteins was concomitantly enhanced. Emetine, cycloheximide and puromycin inhibited both basal and hCG stimulated protein synthesis as well as progesterone production in the cells. Thus, luteal steroidogenesis induced by hCG seems to be dependent upon de novo synthesis of a protein(s).

Animals↗
PubMed1984

The formalin test: a tonic pain model in the primate.

The formalin test has been used in monkeys for assessing pain. After formalin injection in the palmar surface of the hand just proximal to the base of the fingers, the monkey's responses are rated for 1 h according to objective behavioral criteria. The present 'tonic' pain model has a fair degree of objectivity, validity, reproducibility and quantifiability. The analgesic effects of morphine and pethidine have been evaluated.

Animals↗
PubMed1984

Carbohydrate metabolism in 'delayed implanting' mouse blastocysts undergoing activation in utero and in vitro.

Delayed blastocysts were activated by injecting oestradiol-17 beta to delayed implanting mice or by exposure to culture medium lacking serum. Four enzymes of carbohydrate metabolism (phosphofructokinase, pyruvate kinase, lactate dehydrogenase, malate dehydrogenase) were studied at different time periods and specific time-dependent changes were found during activation. A characteristic feature was a marked decline by 6 h in the activities of phosphofructokinase and pyruvate kinase. Blastocyst activation in vitro and in utero showed similar trends in metabolic patterns during the 24-h period studied.

Animals↗
PubMed1984

Role of embryonic oestrogen in rabbit blastocyst development and metabolism.

Rabbit morulae were grown for 24 h in Ham's F12 medium supplemented with BSA. CI-628 citrate (1.5 micrograms/ml), a specific oestrogen antagonist, significantly inhibited the transformation of morulae to blastocysts. This inhibition was reversed with oestradiol-17 beta (1 micrograms/ml) but not oestradiol-17 alpha (1 micrograms/ml) added to the culture medium. The specific activities of phosphofructokinase, lactic dehydrogenase, malate dehydrogenase and alkaline phosphatase in blastocysts grown in vitro for 24 h in medium TC 199 + BSA showed significant elevation with blastocyst growth and expansion, while that of acid phosphatase revealed no change, and leucine aminopeptidase activity declined significantly. These changes were markedly inhibited by CI-628 citrate (2 micrograms/ml) and were reversed by oestradiol-17 beta (0.4 micrograms/ml) but not by oestradiol-17 alpha (0.4 micrograms/ml). Our findings suggest a role of oestrogen present in the rabbit morula and blastocyst in the triggering of embryonic differentiation and metabolic functions.

Alkaline Phosphatase↗
PubMed1983

Effect of an estrogen antagonist on development of blastocysts and implantation in the hamster.

CI 628 citrate, an estrogen antagonist, was given as a single intraluminal injection (5 micrograms) on day 3 to ovariectomized, progesterone-treated hamsters. This significantly reduced embryo cleavage rate, transformation of morula into blastocyst, and completely inhibited implantation. The effects of the drug could be reversed by estradiol-17B (1 microgram) but not estradiol-17 alpha (1 microgram) injected intraluminally with CI 628 citrate. Our finding suggests a role of estrogen present in hamster preimplantation embryo in the triggering of embryonic differentiation and implantation of the blastocyst.

Animals↗
PubMed1983

Steroid hormones and embryo development in ovariectomized hamsters.

Preimplantation embryo development was arrested at the premorula stage in hamsters ovariectomized on Day 1 of pregnancy. This effect was reversed when 500 micrograms progesterone were administered daily. Oestradiol-17 beta given alone had no significant effect on the cleavage rate or blastocyst formation, but a synergistic response was evident when a suboptimal (30 micrograms) dose of progesterone was given with 50 ng oestradiol-17 beta. Cholesterol and hydrocortisol had no effect on embryo development.

Animals↗
PubMed1983

Histochemical study of beta-glucuronidase in the rat uterus during implantation and pseudopregnancy.

On Day 5 of pregnancy and pseudopregnancy, beta-glucuronidase activity in pseudopregnant uteri and in the inter-implantation zones from pregnant animals was found mainly in stromal and glandular epithelial cells. The luminal epithelium also showed an intense enzyme-positive reaction, particularly in the apical regions of these cells. Blastocyst attachment was associated with marked depletion of beta-glucuronidase activity from epithelial cells lying adjacent to the blastocyst, suggesting a possible involvement of this lysosomal enzyme in the blastocyst-endometrium attachment reaction.

Animals↗
PubMed1982

In vitro inhibiton of trophoblast maturation and expansion of early rat blastocysts by an oestrogen antagonist.

Rat blastocyst development and expansion were studied in an in vitro culture system. Early blastocysts collected from rats on the morning of day 5 were shown to develop normally and underwent expansion when placed in bovine serum albumin supplemented culture medium for 12 h at 37 degrees C. Nafoxidine, an oestrogen antagonist, prevented embryo expansion when added to the culture medium, and it was found that if oestradiol-17 beta was added to this medium this inhibitory effect was removed and the embryos again expanded. Ethanol, used as a solvent for steroids, and cholesterol were added to the medium containing nafoxidine but the blastocysts remained unexpanded after 12 h in culture. These results suggest a need for oestrogen action during blastocyst expansion in vitro. Cultured rat blastocysts were subjected to histochemical study for acid phosphatase (ACPase) and leucylnaphthylamidase (LNAse). In unexpanded blastocysts ACPase was found to be low while LNAse activity was higher when compared with enzyme distribution patterns in expanded blastocysts.

Acid Phosphatase↗
PubMed1982

A study of carbohydrate metabolism in 'delayed' and 'activated' mouse blastocyst and uterus.

Several regulatory enzymes of carbohydrate metabolism were studied in blastocysts and uteri of mice in which implantation had been delayed and of oestrogen-activated mice, and compared with those of normal mice just before implantation on day 4 of pregnancy. A significant increase in the activities of phosphofructokinase and pyruvate kinase was observed but the level of lactate dehydrogenase declined in delayed blastocysts. Carbohydrate metabolism in the uterus remained essentially unchanged during the delay period. A study of uterine mitotic patterns showed a steady increase in stromal mitosis after administration of oestradiol to animals in which implantation had been delayed.

Animals↗
PubMed1981

Rat embryo development in vitro.

We report the first successful culture of 8-cell/morula stage rat embryos in a fully synthetic medium supplemented with 3% crystalline bovine serum albumin. Eighty-four per cent of morulae developed to blastocysts, showing that this is a highly efficient culture medium for in vitro studies on rat pre-implantation embryos. Blastocyst formation was severely inhibited by antioestrogen (nafoxidine 3 microgram/ml) but no further reversal was obtained by giving oestrogen to culture medium containing this antagonist.

Animals↗
PubMed1981

Effect of an anti-oestrogen on implantation of mouse blastocysts.

Mouse blastocysts collected on Day 4 were cultured for 4 h in Whitten's medium containing 5 micrograms CI-628 citrate, a specific oestrogen antagonist, and transferred to the uteri of pseudopregnant hosts. There was a significant reduction in the number of implantations observed on Day 11 when compared with those from blastocysts which were similarly transferred after culture in medium alone or in medium containing 1 microgram oestradiol-17 beta and 5 micrograms CI-628 citrate. We suggest that this is further evidence for the involvement of embryonic oestrogen in implantation.

Animals↗
PubMed1981

Effect of an oestrogen antagonist on implantation and uterine leucylnaphthylamidase activity in the ovariectomized hamster.

CI-628 citrate, an oestrogen antagonist, instilled into the uterine lumen of ovariectomized, progesterone-treated hamsters on Day 3 of pregnancy completely prevented implantations. Normal implantations occurred in the contralateral uterine horn which was pierced by a needle and in horns into which saline was instilled. There was less activity of lysosomal leucylnaphthylamidase in implantation sites than in inter-implantation sites and in the tissues of the CI-628 citrate-treated horns.

Animals↗