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Biomedical subjects

A Goswami

Publications and source records attributed to A Goswami.

At least 55 records · Page 3Linked to original sources
PubMed1992

Reconstitution of a purified and partially active low Km iodothyronine 5'-deiodinase with phospholipids.

We previously reported the detergent-extraction and purification to homogeneity from rat liver microsomes of an iodothyronine 5'-deiodinase which differed from the type I enzyme in its molecular size as well as its Km, thiol responsiveness, and its expected sensitivity to the antithyroid drug, propylthiouracil. The specific activity enhancement (22-fold) of the delipidated enzyme was, however, relatively modest. We report here that the purified enzyme can be activated a further 25-fold by reconstitution in microsomal phospholipids and, to a lesser extent, in soybean phospholipids. The data suggest that a native lipid environment is necessary for proper conformation of the enzyme for optimal activity.

Animals↗
PubMed1991

Heart rate & blood lactate response in field hockey players.

The heart rate and blood lactate were studied in field hockey players (25 juniors and 29 seniors) as well as the blood lactate response in training to assess the anaerobic demand of the game and the adaptability of the players to anaerobic metabolism, respectively. The mean VO2 max of the junior and senior players were 3.32 l/min (54.4 ml/kg/min) and 3.28 l/min (53.8 ml/kg/min), respectively. Blood lactate levels after warm up, training and the game were 2.1, 7.4 and 4.2 mM/l, respectively for the juniors and 2.6, 7.7 and 5.6 mM/l, for the seniors. The aerobic capacity (VO2 max) of the juniors did not differ from their senior counterparts, indicating a similar adaptability to aerobic metabolism. However, the Indian players revealed a lower VO2 max than their International counterparts. Similar lactate levels in juniors and seniors after training indicated a similar adaptability to the anaerobic metabolism also. The higher blood lactate level in seniors after the game reflected that they played with greater intensity than the juniors, due to more experience, better motivation and skill.

Adolescent↗
PubMed1991

Percutaneous retrogasserian radiofrequency thermal rhizotomy for trigeminal neuralgia.

Forty patients suffering from intractable unilateral trigeminal neuralgia involving more than one division of the trigeminal nerve were treated by percutaneous radiofrequency thermocoagulation of the trigeminal sensory root. The aim of the operation was to relieve the pain without producing dense sensory deficit in the face. This goal was achieved by making selective lesions in the sensory root with gradually increasing temperature 60 degrees C to 90 degrees C. Three to four consecutive lesions each for 60 seconds have been found to produce excellent pain relief in 77.7% with good and fair results in the rest. The recurrence rate has been found to be 15% during 2 years of follow-up. Considerable dysaesthesia was observed in 5% of cases. Corneal anaesthesia was found in 5% cases while one patient developed neuroparalytic keratitis. Transient trigeminal motor weakness was observed in 10% of patients.

Aged↗
PubMed1990

Purification and partial characterization of iodothyronine 5'-deiodinase from rat liver microsomes.

We have isolated and purified iodothyronine 5'-deiodinase from rat liver microsomes to homogeneity as judged by PAGE and analytical HPLC. The enzyme progressively lost activity after solubilization, and specific activity enhancement was a modest 22-fold, but the final preparation still had substantial activity and was used for molecular characterization. The enzyme had an Mr of 56,000 with a single band in SDS-PAGE, suggesting absence of subunit structure. The high Km, and the GSH-responsive low Km, activities were co-purified, but the low Km enzyme lost GSH-responsiveness upon pretreatment with dithiothreitol (DTT) and urea. The enzyme was strongly inhibited by the iron chelator, alpha,alpha'-dipyridyl and showed a broad absorbance band at 410 nm. Spectral analysis with diethylpyrocarbonate (DEPC) revealed 5 histidine residues/mol enzyme, while enzyme activity was inhibited by DEPC in a pseudo-first order process with modification of 1 histidine residue/mol.

Animals↗
PubMed1990

Regulation of iodothyronine 5'-deiodinases: effects of thiol blockers and altered substrate levels in vivo and in vitro.

To study the physiological regulation of the iodothyronine 5'-deiodinases (I-5'D), we have examined the effects of some thiol blockers and of thyroid status on I-5'D activities both in vitro and in vivo. At low (less than 5 mM) concentrations of dithiothreitol, propylthiouracil (PTU) inhibited I-5'D in the brain, pituitary, and brown adipose tissue (BAT) of hypothyroid rats (which contain predominantly the type II activity); the patterns of inhibition in these tissues were essentially similar, with a Ki of about 174 microM at 250 microM dithiothreitol. Hydroxyethyldisulfide was a strong inhibitor of the type II enzyme, with relatively little effect on the renal enzyme at both high concentrations (micromolar) of T4, i.e. predominantly type I activity, and low concentrations (nanomolar) to T4, i.e. both type I and low Km activity. Preincubation of cerebral microsomes with PTU, followed by removal of excess PTU, resulted in 70% inhibition of I-5'D activity in cerebral microsomes at 5 mM dithiothreitol; the corresponding inhibitions of the renal enzyme at high and low substrate concentrations were 66% and 48%, respectively. Specific binding of PTU to renal and cerebral microsomes was diminished by hydroxyethyldisulfide, but not by T4, suggesting that PTU binding was not dependent on substrate interaction. Administration of PTU in vivo (1 mg/100 g BW, ip; 1 h before killing) resulted in approximately 80% inhibition of I-5'D activity in renal microsomes at high T4, and 50-70% inhibition in pituitary, BAT, and renal microsomes at low T4, but no inhibition was observed in brain microsomes. HPLC analyses revealed a PTU content of 35-65 nmol/g wet wt in the pituitary, BAT, liver, and kidney, but no PTU was detected in the brain, suggesting that PTU may be excluded by the blood-brain barrier. Maintaining hypothyroid rats on 1 microgram T4/100 g BW.day for 5 days enhanced renal type I and low Km I-5'D with restoration of serum T3 to normal levels, although the type II I-5'Ds from all sources were severely depressed. A supraphysiological dose of T4 depressed all three I-5'Ds. The data indicate that the I-5'Ds are regulated in a qualitatively similar fashion.

Adipose Tissue, Brown↗
PubMed1990

Effect of educational intervention on defaecation habits in an Indian urban slum.

The defaecation habits of 172 adults before and after a cholera epidemic in New Delhi in 1988 were investigated. Intensive educational activities were undertaken during the epidemic. A community latrine facility was constructed in this area in February 1988. A greater proportion of females than males were found to be exclusively using the latrines at both rounds of the investigation. A statistically significant relationship with age was observed (P less than 0.001), while literacy was not found to exert a statistically significant effect. Difference in usage habits were more marked in the second round of the investigation. Cost and distance were the main reasons cited for non-utilization of latrines. 91.4% of respondents stated that they had faced some problem in using latrines. Most children were found to be defaecating in the open around the dwelling units at both rounds of the investigation.

Adult↗
PubMed1989

In vitro metabolic transformations of vinblastine: oxidations catalyzed by peroxidase.

Vinblastine is converted to a single major metabolite during in vitro enzymatic oxidations catalyzed by horseradish peroxidase in the presence of hydrogen peroxide. Preparative-scale enzyme incubation permitted the isolation of sufficient amount of the transformation product for complete structural identification and biological evaluation. The metabolite was identified as catharinine (also known as vinamidine) by 1H and 13C NMR and by mass spectrometry. Incubations conducted in H2(18)O-enriched water gave catharinine in which a single atom of 18O was incorporated into the metabolite structure. The labeling experiment provided evidence for an unusual ring-fission pathway by which peroxidase transforms vinblastine to catharinine. Catharinine is 77 times less active than vinblastine when tested in vitro against the human T-cell leukemic cell line (CRFF-CEM).

Animals↗
PubMed1989

Reactive thiols in type II iodothyronine 5'-deiodinases: inactivation by iodoacetate.

Although all iodothyronine 5'-deiodinases require thiol cofactors for activity, the type II variant has been suspected to contain no reactive thiol groups because of its resistance to inactivation by iodoacetate (IAC). We report here that, under suitable stoichiometric conditions for the alkylation reaction, the type II enzyme is substantially inactivated by IAC. The reaction follows pseudo-first-order kinetics with an inactivation rate constant of 0.08 min-1. Moreover, the enzyme is inhibited by hydroxyethyl disulfide and propylthiouracil. These reagents, but not thyroxine, also protect the enzyme from inactivation by IAC, The data suggest that IAC interacts with an essential thiol group in the active center domain.

Animals↗
PubMed1988

Ergonomics in sickle operation.

Sickle operation in harvesting has been analysed with reference to design features of nine different types of sickles, and field and laboratory based investigations on biomechanical stresses and physiological valuation on six farmers. It has been indicated that the blade geometry contributes significantly to human performance and there is ample scope for further design optimisation. The suggested modifications are: (i) sickle weight - 200 g; (ii) total length of sickle - 33 cm; (iii) handle length - 11 cm; (iv) handle diameter - 3 c cm; (v) radius of blade curvature - 15 cm; (vi) blade concavity - 5 cm; (vii) serrated sickle: tooth pitch - 0.20 cm and tooth angle - 60 degrees; (viii) ratio of the length of cutting surface to chord length - 1.20.

Journal Article↗