Biomedical subjects

A Kumar

Publications and source records attributed to A Kumar.

At least 1,783 records · Page 99Linked to original sources

PubMed1987

Design and synthesis of phosphonate inhibitors of glutamine synthetase.

Inhibitors 1-4 have been shown previously to undergo enzymatic phosphorylation by glutamine synthetase (GS). Phosphonates 6-9 were designed as chemically stable analogues of these phosphorylated inhibitors, incorporating either a tetrahedral sulfur group (6-8) (-S-, -SO-, -SO2-) or phosphinate (9) adjacent to methylphosphonic acid. Phosphonates 6-8 resemble the transiently stable phosphorylated methionine sulfone (2), whereas 9 resembles phosphorylated 2-amino-4-phosphonobutyric acid (4). When tested as inhibitors of glutamine synthetase from bacteria, mammals, and plants, analogue 9 proved to be the most potent, with a Ki value of 7.5 X 10(-5) M vs. the Escherichia coli enzyme. Analysis of the inhibition data for 6-9 suggests that a replacement of the oxygen bridging the tetrahedral sulfur (6-8) or phosphinate (9) and the terminal phosphate with a hydrophobic methylene drastically reduces the enzyme's affinity for inhibitors. Enhanced affinity of GS for phosphonate 9 may result from interaction of the negative charge on the phosphinate with Mn2+ at the active site.

Glutamate-Ammonia Ligase↗

PubMed1987

Synthesis and biological activity of isodithiobiurets, dithiobiurets, and dithiazoles.

A series of isodithiobiurets, dithiobiurets, and dithiazoles was synthesized and tested for biological activity. Generally, the compounds potentiated the hypnosis induced by pentobarbitone (50 mg/kg ip) in albino mice and exhibited antifungal and insecticidal activity against Fusarium oxysporum and Periplanata americana, respectively. Some compounds showed anticonvulsant and analgesic activity in albino rats.

Analgesics↗

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↗

PubMed1987

Evaluation of preinduction scoring systems.

Two hundred patients requiring induction of labour were assigned a preinduction score according to Dhall's criteria and Bishop's criteria. A score of 9 or more (Dhall) and 6 or more (Bishop) had favourable outcomes with successful induction in more than 90% of patients and an induction delivery interval (IDI) of less than 12 hours. In multiparas a Dhall score of more than 7 had a sensitivity and specificity of 88.6% and 90.0% respectively in predicting induction outcome compared to Bishop score sensitivity of 86.3% and low specificity of 47.4%. Correlation of the score with IDI as a dependent variable also showed that the Dhall score had a better predictive value than the Bishop score.

Cesarean Section↗

PubMed1987

Optimum dosage of ispaghula husk in patients with irritable bowel syndrome: correlation of symptom relief with whole gut transit time and stool weight.

To determine the optimum dose of ispaghula husk in patients with irritable bowel syndrome (IBS) and to assess the correlation, if any between the relief in patients' symptoms and the whole gut transit time, and the increase in stool weight, a two part study was carried out. In part 1, 14 male patients were given ispaghula husk in increasing doses of 10 g, 20 g, and 30 g a day for a duration of 17 days each (14 days of study period + three days of stool collection). Ten patients completed the trial. The symptom score improved significantly with all the three doses of ispaghula. Both 20 g and 30 g doses of ispaghula were superior to the 10 g dose but there was no significant difference between the 20 g and 30 g doses. There was a significant (p less than 0.001) increase in the daily stool weight with 10 g dose of fibre with further significant increases with the 20 g and 30 g doses. A positive correlation was seen between the improvement in the symptom score and the increase in stool weight with the 10 g dose of ispaghula but not with the 20 g and 30 g doses. Whole gut transit time remained fairly constant throughout the study period and there was no relationship with either the dose of ispaghula, the alteration in stool weight, or the improvement in the patients symptoms. Ten patients completed part 2 of the study in which ispaghula husk was given in the same dose (10 g, 20 g, and 30 g) but in a random order and with a "washout" period of one week between individual doses. Again all the three doses of ispaghula produced a significant improvement in the symptoms; 20 g and 30 g doses were equally effective and both were significantly superior to the 10 g dose. Assessed individually, all the three symptoms improved significantly; improvement in constipation and pain abdomen was more pronounced than diarrhoea. It is concluded that the optimum dose of ispaghula husk in irritable bowel syndrome is 20 g per day. There is some correlation between the increase in stool weight and the improvement in symptom score but the whole gut transit time remains unchanged despite alterations in stool weight and patients' symptoms.

Adult↗

PubMed1987

Inhibitory effect of Azone (1-dodecylazacycloheptan-2-one) on herpes simplex viruses. In vivo and in vitro studies.

Enhanced activity of antiviral agents, when mixed with a penetration enhancer like Azone (1-dodecylazacycloheptan-2-one) in topical preparations, is well-recognized. These studies were undertaken to investigate whether Azone, per se, has any activity against herpes simplex (HSV) type 1 and type 2 viruses. When HSV-1 and HSV-2 were mixed with 5, 10 and 20% Azone, there was a 1-4.5 log10 decrease in virus titers. The efficacy of 5 and 10% Azone applied topically was evaluated during the treatment of HSV-1 cutaneous infections in guinea pigs. HSV-1 infection was produced by intradermally inoculating guinea pigs with 10(7.7) HSV-1/ml. The mean number of lesions per site was reduced by more than 50% in Azone-treated sites as compared to no treatment (control) sites (p less than 0.01). Similarly, the surface area of each lesion in the Azone-treated sites was only 40% of that seen in control sites (p less than 0.001). More than 80% of the lesions on Azone-treated sites healed by day 4 as compared to only 3% on control sites (p less than 0.001). These data indicate that Azone, a lipophilic chemical, may have antiviral properties when used topically.

Animals↗

PubMed1987

Molecular cloning of human angiotensinogen cDNA and evidence for the presence of its mRNA in rat heart.

Human angiotensinogen cDNA clone was isolated from a liver cDNA library using a 32-nucleotide-long, synthetic oligonucleotide. The cDNA insert was 1,030 bp long and coded for the secretory and biologically active angiotensin II regions of the angiotensinogen molecule. The RNA from rat liver, brain, and heart was analyzed by the Northern hybridization procedure using nick translated angiotensinogen cDNA as a probe. In addition to liver, the angiotensinogen mRNA is present in the brain and the heart. The angiotensinogen mRNA in the heart is at least fourfold to fivefold more abundant as compared with the liver. We also provide evidence that angiotensinogen mRNA is present in the rat atria and right ventricle but not detectable in the left ventricle. The size of the angiotensinogen mRNA is the same from all three of the tissues, as judged by their electrophoretic mobilities.

Angiotensinogen↗

PubMed1987