Biomedical subjects
Publications and source records attributed to S K Gupta.
The absorption kinetics of cyclosporine were studied in eight healthy volunteers following oral and intravenous administration. Bioavailability of cyclosporine was observed to be 20.8 +/- 5.5 per cent. Absorption of cyclosporine was found to be better described by first order processes rather than by a zero order process as previously reported.
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Explore the source record for details and available documents.
Explore the source record for details and available documents.
Explore the source record for details and available documents.
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This study was carried out to explore the effect of piperine-containing food in altering the pharmacokinetics of phenytoin, an anti-epileptic drug with a narrow therapeutic index. A preliminary pharmacokinetic study was carried out in mice by administering phenytoin (10 mg) orally, with or without piperine (0.6 mg). Subsequently, oral pharmacokinetics of phenytoin was carried out in six healthy volunteers in a crossover design. Phenytoin tablet (300 mg) was given 30 minutes after ingestion of a soup (melahu rasam) with or without black pepper. A further study of intavenous pharmacokinetics of phenytoin (1 mg) in rats with or without oral pretreatment with piperine (10 mg) was also conducted. The phenytoin concentration in the serum was analyzed by HPLC. The study showed a significant increase in the kinetic estimates of Ka, AUC(0-10) and AUC(0-infinity) in the piperine-fed mice. Similarly, in human volunteers piperine increased Ka, AUC(0-48), AUC(0-infinity), and delayed elimination of phenytoin. Intravenous phenytoin in the oral piperine-treated rat group showed a significant alteration in the elimination phase indicating its metabolic blockade. The significance of this finding in epileptic patients maintained on phenytoin therapy requires further investigation. This study may also have implications in the case of other drugs having a low therapeutic index.
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Ultrastructural studies were conducted to assess the effect of lead (Pb 5 mg/kg IP for 16 days as lead acetate) on rat spermiogenesis. Results showed swelling of nuclei and acrosomes in round spermatids. In Sertoli cells, nuclei appeared fragmentated, whereas the cytoplasm exhibited a vacuolated appearance and a few structures delimitated by a double membrane that contain parallelly arranged microtubules and cross-striated fine fibrils. Sertoli cell tight junctions remained intact. There was no significant change in epididymal sperm motility and counts, although testicular and blood lead levels were found to be elevated after lead exposure. These results suggest that spermatid and Sertoli cell damage may lead to disruption of spermiogenesis in lead-intoxicated rats.
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We have evaluated the results of endoscopic fine needle aspiration cytology in 50 consecutive cases of suspected malignancy of the esophagus and stomach and compared them with those of forceps biopsy and brush cytology. The diagnostic yield with forceps biopsy, fine needle aspiration, and brush cytology in 46 cases of carcinoma was 88.8%, 89.1%, and 80.4%, respectively. A combination of forceps biopsy and brush cytology gave an accuracy of 93.5% while the addition of fine needle aspiration increased the yield to 100%. This was due to a very high positive yield of fine needle aspiration in infiltrative tumors.
A solid-phase sandwich enzyme immunoassay for human chorionic gonadotropin (hCG) employing monoclonal antibodies directed against beta- and alpha-subunits is described. Polystyrene beads used as solid support were coated with monoclonal anti-beta-hCG antibody. Monoclonal anti-alpha-hCG antibody was labelled with the enzyme, horseradish peroxidase. The assay could be performed by a "one-step" or "two-step" procedure. The sensitivity of the two-step procedure was 7.8 ng hCG/ml with a linear range up to 500 ng hCG/ml. The one-step procedure had a measurement range between 15.6 and 125 ng hCG/ml. Within the limits of measuring ranges, the two procedures had similar accuracy, the correlation coefficient being 0.987. Twenty-one urine samples from pregnant women were analysed by the two-step procedure and also by radioimmunoassay. The results were comparable, with r = 0.956.
Given that there was documented evidence of an association between diarrhea and high nitrate ingestion, the authors examined drinking water nitrate concentration and its possible correlation(s) with methemoglobin levels, cytochrome b5 reductase activity, and recurrent diarrhea. In addition, the authors studied histopathological changes in the intestines of rabbits in an animal model. Five village areas were studied, and nitrate concentrations (expressed in mg of nitrate per liter of water) of 26, 45, 95, 220, and 459 existed in the respective villages. The study included 88 randomly selected children who were 8 yr of age or younger; they represented 10% of the total population of each of the areas. Detailed histories of recurrent diarrhea were noted, and medical examinations were conducted. Cytochrome b5 reductase activity and methemoglobin levels were estimated biochemically. Collected data were analyzed statistically with Microsoft Excel software. In addition, the authors exposed rabbits to various levels of nitrate, and histopathological changes of the stomach and intestine (small and large) were evaluated. There was a strong relationship between nitrate concentration and recurrent diarrhea; 80% of the recurrent diarrhea cases were explained by nitrate concentration alone. In the rabbit intestines, lymphocytic infiltration and hyperplasia characterized the submucosa as nitrate concentrations increased.
The use of organochlorine insecticides for public health programs is indisputably necessary in developing countries. Thus, there is a need to evaluate human response to these chemicals under local field conditions. The effects of a short-term, 16-wk exposure to hexachlorocyclohexane has been evaluated and compared in malaria spraymen with and without any previous occupational exposure to this insecticide by measuring the pre- and post-exposure serum hexachlorocyclohexane concentration. A significant increase in original serum hexachlorocyclohexane concentration. A significant increase in original serum hexachlorocyclohexane concentration was observed in subjects on their first occupational exposure (5X), compared to those with previous exposure (3X). All workers reached approximately the same serum levels within 16 wk, regardless of their history of previous exposure.
Topical drug delivery is preferred in the eye to avoid under or over medication and undesired side effects of systemic administration. In order to maintain adequate drug levels in ocular tissues, frequent drug installation is necessary in vision threatening conditions like glaucoma, corneal ulcers due to microbial infections, etc. Only a part of the installed drug reaches the aqueous humor and the rest of it is drained by the nasolacrimal duct. Positively charged liposomes have been found to enhance the penetration of drugs into the cornea. The present study was conducted to visualize the interaction of liposomes with the cornea. Briefly, positively charged liposomes entrapped with Carboxyfluorescein (CF), Propidium iodide (PI), Horseradish peroxidase (HRP), Biotin, Hydroxy benzimide (Hoechst No: 33258), and Ethoxy benzimide (Hoechst No: 33342) were prepared by sonication. Their size and shape were analysed by laser dynamic light spectra and electron microscopy, respectively. The liposome encapsulated and free materials in buffer were instilled, in a volume of 20 microliters, into eyes of anesthetized albino rats. After 30 min and 1 h, the eyes were enucleated and quickly processed for cryosections of 3-5 microns thickness. The interaction of liposome entrapped propidium iodide and HRP was visualized on the outer epithelium of the cornea after specific processing.
Phorate (Thimet), an aliphatic derivative of phosphorus is a highly toxic insecticide. In order to implement the safety measures, the clinical manifestations and cholinesterase (ChE) activity were evaluated before and after 2 weeks of exposure to this insecticide in 40 male formulators. The 2 week's exposure reveal signs and symptoms of toxicity in 60% of the formulators. Gastrointestinal symptoms and lowering of heart rate (bradycardia) were more prominent as compared to the neurological symptoms. A significant depression in plasma ChE activity was observed at the end of 1st week (55%) and 2nd week (71%) as compared to the respective pre-exposure values. A recovery up to 79% of the pre-exposure activity of this enzyme was noticed 10 days after cessation of the above exposure.
The zona pellucida (ZP) surrounding a mammalian oocyte mediates the initial recognition and binding of spermatozoon to oocyte in a relatively species-specific manner and plays an important role in the subsequent activation events during the fertilization process. The ZP comprises three biochemically and immunologically distinct glycoproteins termed ZP1, ZP2 and ZP3. The critical role of ZP glycoproteins in reproduction together with their tissue-specific nature have led to their being considered as potential candidate antigens for immunocontraception. Immunization of females with ZP glycoproteins leads to a block of fertility in several animal models. However, it is invariably associated with either a transient or an irreversible alteration in the cyclicity, hormonal profile and follicular development in the ovary. To overcome these problems, attempts are being made to delineate relevant 'B' cell epitopes on ZP proteins so as to design immunocontraceptive vaccines based on synthetic peptides devoid of oophoritogenic 'T' cell epitopes. Monoclonal antibodies capable of inhibiting the gamete interaction are being employed to delineate such regions. Additionally, DNA-recombinant technology has made it feasible to obtain, in reasonably large quantities, the ZP glycoproteins from human and non-human primates. Availability of sequence information of these zona proteins and the availability of recombinant antigens (devoid of other ovarian-associated proteins) will further help in understanding more precisely their functions during fertilization and make it feasible to undertake immunization studies to determine their prospects as immunogens for fertility regulation.