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Biomedical subjects

S Majumdar

Publications and source records attributed to S Majumdar.

At least 343 records · Page 19Linked to original sources
PubMed1985

Effect of a steroidal oral contraceptive on intestinal absorptive functions in proteins deficient rat.

The effects of steroidal oral contraceptive norethynodrel plus ethinylestradiol-3-methyl ether (SOC) at a daily dose of 5 mg: 0.06 mg per kg body weight for 28 days on intestinal absorptive functions have been investigated in protein-deficient female albino rats. The administration of this contraceptive caused significant increase in glucose and amino acids uptake but had no effect on calcium and zinc uptake in pair-fed as well as in protein-deficient rat. Further studies carried out on glucose transport system showed that the transport of sodium-dependent glucose was significantly enhanced while that of sodium-independent glucose remained unaltered in drug-treated animals. Kinetic studies of glucose transport in the presence of sodium ions revealed that SOC treatment affected the rate of uptake of glucose by elevating Vmax, but the apparent Kt value remained the same in treated and untreated animals.

Amino Acids↗
PubMed1985

Effects of 17 beta-estradiol and progesterone on intestinal digestive and absorptive functions in ovariectomized rats.

The effects of low and high doses of 17 beta-estradiol and progesterone for 2 weeks on intestinal digestive and absorptive functions have been investigated in ovariectomized rats. The uptake of glucose was significantly enhanced following ovariectomy and administration of hormones restored the level of glucose uptake to that observed in sham-operated animals. Neither, the uptake of L-leucine nor calcium was affected after ovariectomy and treatment with the hormones. The activity of alkaline phosphatase (AP) of ileum was significantly elevated with the low and high doses of 17 beta-estradiol but in jejunum only at high doses. Progesterone alone did not alter AP activity but the combination of this hormone and 17 beta-estradiol significantly enhanced the jejunal and ileal AP activities. It seems that activity of AP is mainly under the control of 17 beta-estradiol. The activity of ileal disaccharidases and leucine aminopeptidase were enhanced at high doses of 17 beta-estradiol alone or in combination with progesterone whereas in the jejunum only AP activity was increased significantly. The present study indicates that 17 beta-estradiol plays an important role in regulating the activities of intestinal digestive enzymes and it is the ileal enzymes which are more prone to its action.

Alkaline Phosphatase↗
PubMed1985

UV-repair and mutagenesis in Azotobacter vinelandii. II. Repair and mutagenesis.

More numbers of mutants were isolated when UV-irradiated cells of Azotobacter vinelandii OP were treated with caffeine for a limited period of time after UV-irradiation. This is encouraging, considering the difficulty in isolating Azotobacter mutants. Post-irradiation treatment with acriflavine, however, yielded comparatively lesser number of mutants.

Acriflavine↗
PubMed1984

Alterations and reversibility of digestive and absorptive functions of rat intestine following medroxyprogesterone acetate administration.

The long term (90 days) effects of medroxyprogesterone acetate (MPA) administration on the digestive and absorptive functions of the small gut have been investigated in female albino rats. The uptake of glucose and amino acids was found to be significantly increased while Ca++ uptake decreased following MPA treatment (35 mg/kg body weight). The observed increase in glucose uptake might be due to carrier mediated transport in enterocytes and not to a change in cell number. The Michaelis constant for glucose uptake was not altered by MPA. Activities of brush border membrane disaccharidases, leucine aminopeptidase and basolateral membrane enzyme Na+, K+-ATPase were significantly increased in response to MPA treatment. It was observed that these biochemical alterations caused by MPA in intestinal digestive and absorptive functions were reversible by 5 weeks after termination of the drug treatment. The action of the drug appears to closely resemble that of known effects of glucocorticoids on intestinal mucosa.

Animals↗
PubMed1984

Effect of medroxyprogesterone acetate on the intestinal absorptive functions in protein-deficient rat.

Effect of Medroxyprogesterone acetate (MPA) at a dose level of 35mg/Kg body weight per week for four weeks on the intestinal uptake of nutrients viz glucose, amino acids, (alanine and leucine), calcium and zinc has been investigated in protein-deficient female rats. The administration of MPA was found to enhance significantly the uptake of glucose and amino acids in both the pair-fed and the protein-deficient rats. In contrast, calcium uptake was depressed as a result of treatment with the drug as well as protein-deficiency. The uptake of zinc was not affected on drug administration. This steroidal contraceptive caused elevation in sodium-dependent glucose uptake, while the sodium-independent uptake remained unaltered. The kinetic parameters of glucose and leucine uptake indicate that MPA might be inducing the transport carrier protein of these nutrients as elevation in Vmax of these nutrients transport system was observed following its administration.

Amino Acids↗
PubMed1983

Degenerative and regenerative changes in central projections of glossopharyngeal and vagal sensory neurons after peripheral axotomy in cats: a structural basis for central reorganization of arterial chemoreflex pathways.

Hypoxic hyperventilation in cats is a reflex normally initiated by afferent impulses originating in the carotid body and conducted to the brain stem by the carotid sinus nerves. The reflex response is abolished acutely after section of carotid sinus nerves and excision of the carotid bodies; but, chronically, there is a chemoreflex restoration which is mediated by the aortic body via the aortic depressor nerves. The restoration is associated temporally with changes in efficacy of ventilatory reflexes elicited by electrically stimulating carotid sinus and aortic depressor nerves, and these changes are postulated to reflect a central reorganization of the reflex pathways. In the present study, histological and ultrastructural techniques were used to investigate the neuroanatomical basis of the reorganization. The brain stem of the cat was examined using the Fink-Heimer silver stain to determine if degenerating axons were present following section of the carotid sinus nerve peripheral to its sensory ganglion. Degeneration was found 4-15 days postoperatively and the distribution of the axons corresponded with that reported for central projections of carotid sinus nerves labeled by transganglionic transport of horseradish peroxidase. The fine structure of nerve terminals in nucleus tractus solitarius was then examined with electron microscopy after cutting the vagus and glossopharyngeal nerves unilaterally peripheral to the sensory ganglia. Structural changes consistent with nerve terminal degeneration were observed 4-91 days postoperatively, and presumptive axonal sprouts were seen at 56-91 days.(ABSTRACT TRUNCATED AT 250 WORDS)

Afferent Pathways↗
PubMed1983

Effect of medroxyprogesterone acetate on the digestive and absorptive functions of rat intestine.

The effects of medroxyprogesterone acetate (MPA) on the digestive and absorptive functions of the small intestinal epithelium have been investigated in female albino rats. The transport of sodium-dependent glucose was significantly enhanced while sodium-independent transport remained unaltered in drug-treated animals. The uptake of amino-acids was also considerably increased, while Ca++ uptake decreased significantly on administration of the drug at a dose of 35 mg/kg body weight once a week for 1 month. Kinetic studies of glucose transport in the presence of sodium ions revealed that MPA treatment affected the rate of uptake of glucose by elevating Vmax, but the Km value remained the same in treated and untreated animals. The administration of the drug also led to significant augmentation in the activities of the brush border enzymes, disaccharidases, and to an insignificant decrease in alkaline phosphatase. The activities of leucine aminopeptidase did not show any change. The enhancement in sucrase activity might be due to induction of the enzyme because only Vmax was elevated in treated animals. As concerns cellular enzymes, lactate dehydrogenase activity was significantly depressed. This study suggests that MPA also exerts glucocorticoid-like effects on the intestinal tissue.

Amino Acids↗
PubMed1982

Alterations in the activities of intestinal enzymes in vitamin-C-deficient guinea pigs.

The effect of vitamin C deficiency on various enzymes of the intestinal epithelium has been studied in guinea pigs. Brush border sucrase and alkaline phosphatase activities were considerably enhanced (p less than 0.001), but leucine aminopeptidase levels were reduced in scorbutic animals compared to the control group. There was essentially no change in the activity of maltase under these conditions. Kinetic studies with sucrase and alkaline phosphatase in control and scorbutic animals revealed that augmentation of the enzyme activities in scurvy is due to enhanced enzyme contents. Lactate dehydrogenase, succinate dehydrogenase, glucose-6-phosphatase and Mg+2 ATPase also exhibited reduced activities in the intestine of vitamin-C-deficient animals. Observed alterations in the activities of intestinal enzymes in scurvy were restored to control levels upon feeding of vitamin C to scorbutic guinea pigs.

Alkaline Phosphatase↗