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Biomedical subjects

A Kar

Publications and source records attributed to A Kar.

At least 55 records · Page 3Linked to original sources
PubMed1996

Free radical mediated membrane perturbation and inhibition of type-I iodothyronine 5'-monodeiodinase activity by lead and cadmium in rat liver homogenate.

The possible involvement of lipid peroxidation (LPO) in the lead (Pb) and cadmium (Cd) induced thyroid dysfunction with special reference to type-I iodothyronine 5'-monodeiodinase (5'-D) activity was studied in rat liver homogenate. Peroxidative reactions involving membrane components were found to be markedly stimulated by chronic administration of Pb and Cd in rats. Metal induced inhibition in 5'-D activity was also observed. Since LPO is primarily an outcome of free radical generation, we suggest metal induced free radical mediated inhibition of 5'-D activity in rat liver homogenate. In addition, serum triiodothyronine (T3) and thyroxine (T4) concentrations were also decreased by metals.

Animals↗
PubMed1995

Loss of membrane integrity and inhibition of type-I iodothyronine 5'-monodeiodinase activity by fenvalerate in female mouse.

The possible involvement of lipid peroxidation (LPO) in the fenvalerate-induced thyroid dysfunction with special reference to type I 5'-monodeiodinase (5'-D) activity has been worked out. Fenvalerate (40, 80 and 120 mg/kg body weight) enhanced LPO in biomembranes of liver and kidney leading to a decrease in membrane integrity. 5'-D activity and serum concentration of triiodothyronine (T3) were reduced by the highest dose. Serum thyroxine (T4) concentration was decreased in all the three fenvalerate-treated groups, indicating the sensitivity of thyroid gland to this pesticide. A marginal increase in T4 concentration in highest dose-treated group compared to that of the lower one supports the view that the monodeiodination of the phenolic ring of T4 is inhibited by fenvalerate. We suggest the possible inactivation of 5'-D by the generated free radicals in pesticide-treated animals.

Animals↗
PubMed1993

Induction and characterization of premature chromosome condensation in Drosophila synkaryons and implications to dosage compensation.

Premature chromosome condensation (PCC) was induced in Drosophila melanogaster cell hybrids, with Drosophila mitotic cells and interphase cells at different phases (G1,G1-S,S,S-G2 of the cell cycle, and from male and female, using standard cell fusion technique with polyethylene glycol (PEG). A combination of Feulgen and autoradiography was used to enhance the resolution of the PCC plates. It was possible to identify the characteristics of PCC's at G1, S and G2, and the transitory intermediate phases, which are comparable with respect to the characteristics of PCC's previously described for other species. Using the combined Feulgen-autoradiography technique it was possible to critically resolve the different phases including the transitory intermediate phases in greater detail. Analysis and comparison of results obtained from M (female) x S (female/male) and M (female) x G2 (female/male) hybrids have revealed that the X chromosome from the male could be identified as a distinct acrocentric entity which showed clear allocyclic, heteropycnotic characteristics. The results thus lead us to suggest that the X chromosome in such synkaryons is indeed early replicating as is the X chromosome of male larval salivary gland of Drosophila. The X chromosome morphology is also distinctly at an advanced stage of the cell cycle. On the basis of these findings it is concluded that X chromosome is hyperactive in the normally dividing diploid cells.

Animals↗
PubMed1990

Evidence for the role of thyroxine as a hormone in the physiology of a lizard.

In vivo effects of thyroxine (T4) and triiodothyronine (T3) were studied in male lizards. T4 or T3 (0.5 to 2 nmol) was administered per day over 10 days to surgically thyroidectomized male lizards (35 +/- 2.0 g) and the responses were measured in terms of scale shedding, whole body oxygen consumption (OC), and testicular weight. T3 was more effective in stimulating OC as compared to T4. T4 accelerated scale shedding to a greater extent as compared to T3. T4 was more effective than T3 in restoring the decline in the gonadal weight of thyroidectomized animals. Effect of inhibition of peripheral conversion of T4----T3 by iopanoic acid (IOP) was studied on the above response parameters. IOP at both dose levels inhibited extrathyroidal conversion of T4----T3. The T4-stimulated increase in OC of IOP-treated animals was suppressed, clearly indicating that the T4 effect could be attributed to its conversion to T3. But in these same animals, IOP failed to inhibit T4-stimulated scale shedding and gonadal weight. As the proportion of T4 converted to T3 decreased as a result of IOP treatment, the effectiveness of T4 increased in terms of scale shedding and restoration of gonadal weight. From these studies it appears that all effects of T4 in lizards need not necessarily be mediated via conversion to T3.

Animals↗
PubMed1987

PULMONOLOGIST: a computer-based diagnosis system for pulmonary diseases.

PULMONOLOGIST is a prototype expert system designed as a decision-making aid for physicians in providing accurate diagnosis and treatment of lung diseases. Disease information in the system has been encoded in the form of rules and schemata. The system has been developed using the expert system building tool ART (Automated Reasoning Tool) from Inference Corporation. This paper gives a brief introduction to the expert system concept, and includes a detailed description of the diagnosis system. This system will be tested against clinical data in future studies.

Diagnosis, Computer-Assisted↗
PubMed1985

Circulating thyroid hormone concentrations in relation to seasonal events in the male Indian garden lizard, Calotes versicolor.

Circulating thyroxine (T4) and triiodothyronine (T3) were estimated by RIA in plasma samples of Calotes versicolor collected over a period of 28 months. Monthly observations on seasonal events, viz., molting, whole body O2 consumption, abdominal fat deposition, and testes weight were also made. Plasma T4 ranged from 0.16 to 4.63 ng/ml and T3 from 0 to 1.76 ng/ml during the course of the year. Peaks of T4 and T3 could be related with prehibernating (October/November) and posthibernating (March/April) periods, when scale shedding and O2 consumption were also enhanced. Maximum abdominal fat deposition was found in prehibernatory months (October/November). Thyroid hormone levels declined sharply with entry into hibernation. Abdominal fat deposits gradually decreased, being almost depleted by the end of hibernation. The gradual increase in thyroid hormone concentration in the later half of hibernation may be associated with increased lipolysis and preparation of the oncoming reproductive period. Although T4 and T3 profiles were apparently parallel, discrepancies were observed. Posthibernatory peak of T4 was maintained much longer than that of T3 which declined earlier. Also the rise in the prehibernatory T3 concentration was delayed as compared to that in T4.

Adipose Tissue↗
PubMed1984

Ureteroarterial and ureterosigmoid fistula associated with polyethylene indwelling ureteral stents.

Iliac artery-ureteral fistulas are uncommon, with less than 15 cases described in the literature. Ureterocolic fistulas have been described even less frequently. We report the first case of synchronous right ilioureteral and left ureterosigmoid fistulas associated with indwelling ureteral stents. The patient presented with massive sentinel gross hematuria, urosepsis and chronic anemia.

Aged↗
PubMed1983

Cinchophen analogues as potential CNS agents.

Several amides of cinchophen were prepared and evaluated as CNS agents. Compounds III, VII, XII, XIII, and XIV exhibited analgesic activity while I, III, and XIV acted as CNS depressants.

Analgesics↗
PubMed1983

Synthesis and CNS-depressant profile of 3,4,5-trimethoxybenzoyl analogues.

A series of 3,4,5-trimethoxybenzoyl analogues with varying electronic and stereochemical characteristics has has been synthesized. Many of these compounds (4, 5, 9, 12, 15) showed appreciable potentiation of pentobarbitone-induced hyposis. Several analogues (1, 5, 6, 11, 12, 15) exhibited marked reduction of Spontaneous motor activity (SMA).

Analgesics↗
PubMed1981

Spectrophotometric determination of dimenhydrinate with Reinecke salt.

A convenient spectrophotometric method was developed for the determination of dimenhydrinate in bulk drug and dosage forms and in 1:1 combinations with aspirin, acetaminophen, meprobamate, phenylephrine, and tolbutamide. The method consisted of reacting dimenhydrinate with reinecke salt in an acidic medium at 27 +/- 2 degrees. The purple precipitate was filtered and dissolved in acetone, and the maximum color absorption attained in 15 min was measured at 540 nm. Evidence is provided to establish the optimal experimental parameters. The stoichiometric balance of the precipitate was determined. Reasonably ideal adherence of the color absorption pattern to the Beer-Lambert law permitted microdetermination of dimenhydrinate in pure form, commercial formulations, laboratory-made combinations, and recovery experiments with good accuracy and repeatability. No interference was observed with any of the drugs or tablet adjuvants.

Dimenhydrinate↗
PubMed1980

Synthesis and antimicrobial activity of some anthranilic acid derivatives.

The synthesis of eight derivatives of anthranilic acid is described. Investigation of their antimicrobial activity showed that four of the compounds, viz; anthranilohydrazide, 3,4-dihydro-4-oxo-1,2,3-benzotriazine, triazine-beta-naphthol adduct and N-phenyl anthranilic acid showed significant antibacterial activity. None of the compounds showed any noticeable antifungal effect.

Anti-Bacterial Agents↗