Search PubMed⌕ Search

Biomedical subjects

A Pandey

Publications and source records attributed to A Pandey.

At least 73 records · Page 4Linked to original sources
PubMed1999

Screening of sputum: an experience in a tertiary care hospital.

In order to reduce the work load on the clinical laboratory, it has been recommended that sputum samples, before accepting for culture, should be looked for the presence of polymorphs and squamous epithelial cells. (An appropriate sample should have more than 25 polymorphs per low power field and less than 10 epithelial cells per low power field; others are labelled as inappropriate). We examined this criteria for it's suitability on 1043 samples received at the clinical bacteriology laboratory at the All India Institute of Medical Sciences (AIIMS) for a period of one year (September, 1996 to August, 1997). Four hundred samples were found appropriate while 643 were inappropriate as per recommended criteria. Amongst the 400 appropriate samples, 215 were culture positive and 185 grew normal flora. However, we found that out of 643 inappropriate samples, 195 were culture positive (p < 0.01, statistically significant). The data was further divided into hospitalized and OPD cases. The distribution of culture positive cases in the appropriate samples was again found to be highly significant. It is apparent from our results that an attempt to process an inappropriate sample does not provide useful information.

Bacteriological Techniques↗
PubMed1998

Candida rugosa lipases: molecular biology and versatility in biotechnology.

This review describes how the versatile Candida rugosa lipases (CRL) have extended the frontiers of biotechnology. As evidenced by the current literature, CRL claims more applications than any other biocatalyst. This review comprises a detailed discussion on the molecular biology of CRL, its versatile catalytic reactions, broad specificities and diverse immobilization strategies. It also discusses its role in the food and flavour industry, the production of ice cream and single cell protein, biocatalytic resolution of life-saving pharmaceuticals, carbohydrate esters and amino acid derivatives unobtainable by conventional chemical synthesis, potent biocide making, biosensor modulations, eco-friendly approach and bioremediation, biosurfactants in detergent making, and recently, cosmetics and perfumery.

Biotechnology↗
PubMed1998

Src-like adaptor protein (Slap) is a negative regulator of mitogenesis.

The Src-like adaptor protein (Slap) is a recently identified adaptor protein containing Src homology 3 (SH3) and SH2 domains. Slap is found in a wide range of cell types and was shown to interact with the Eck receptor tyrosine kinase in a yeast two-hybrid interaction screen [1]. Here, we found that Slap is expressed in NIH3T3 cells and could associate with the activated platelet-derived growth factor (PDGF) receptor. Using mutated versions of the PDGF receptor and phosphopeptide competition experiments, we determined that Slap has the highest affinity for the Src-binding site of the PDGF receptor. Our inability to produce cell lines that stably expressed Slap suggested that Slap inhibited cell growth. We further investigated this issue by transiently expressing Slap by microinjection. Overexpression of Slap by this method inhibited DNA synthesis induced by PDGF and serum, whereas overexpression of the adaptor proteins Grb2 and Shc did not. Finally, microinjection of a Slap antibody into NIH3T3 cells that had been stimulated with suboptimal doses of growth factors potentiated the effects of the growth factors. These data suggest that, unlike other adaptor proteins, Slap is a negative regulator of signalling initiated by growth factors.

3T3 Cells↗
PubMed1998

In vitro activities of ampicillin-sulbactam and amoxicillin-clavulanic acid against Acinetobacter baumannii.

In vitro susceptibility patterns of newer beta-lactamase-inhibiting antibiotics ampicillin-sulbactam (A/S) and amoxicillin-clavulanic acid (A/C) for 100 consecutive isolates of Acinetobacter baumannii obtained from various clinical samples were studied. The A/C MIC for 86% of the strains was more than 16/8 microgram/ml, whereas there was an A/S MIC of more than 16/8 microgram/ml for only 38% of the strains. This showed that A/S has significantly superior in vitro activity compared to A/C against A. baumannii, although, theoretically, both should have similar activities. The therapeutic superiority of A/S over A/C needs to be studied, or else the breakpoints for these agents in in vitro tests need to be redefined.

Acinetobacter↗
PubMed1998

1,2,4-Benzotriazine 1,4-dioxides. An important class of hypoxic cytotoxins with antitumor activity.

Tirapazamine (1,2,4-benzotriazin-3-amine 1,4-dioxide, SR 4233, WIN 59075) is the lead compound representing this class of anticancer drugs. It is also the first compound to be introduced in the clinic as a pure bioreductive cytotoxic agent. Tirapazamine represents a completely novel approach to the treatment of solid tumors and has generated considerable interest, with research being carried out on all aspects of the its anticancer activity. Phase III trials of tirapazamine in combination with cisplatin (cDDP) have recently been concluded, and phase II trials of triapazamine in combination with irradiation are presently being performed. We developed a drug discovery program into this class of compounds designed to produce derivatives with improved in vivo activity against solid tumors. Based on the hypothesis that these compounds require bioreductive activation for antitumor activity, the research was primarily directed at producing analogues with greater electron affinity and improved aqueous solubility. The in vitro and in vivo data for a variety of structural analogues clearly show that 1,2,4-benzotriazine 1,4-dioxides have considerable potential as anticancer agents. When their activity is compared directly with the activity observed for triapazamine, the most promising series of analogues appears to be the 3-alkyl-substituted derivatives, especially the 3-ethyl- and 3-(2'-methoxyethyl)-derivatives, SR 4895 and SR 4941 respectively.

Animals↗
PubMed1998

Modification of arginine residues at the substrate binding site of yeast glutathione reductase.

Yeast glutathione reductase (GR) was inactivated by phenylglyoxal (PG), which specifically modifies arginine residues of the enzyme. Inactivation followed psuedo-first order rate kinetics. There was no reversible complex formation prior to inactivation. Analysis of the kinetic data showed the order of reaction to be unity with respect to the modifier. Inactivation of GR was completely prevented by the presence of oxidised glutathione (GSSG), whereas NADP gave only partial protection. Stoichiometric studies showed that around four arginine residues per subunit were modified by PG in the absence of GSSG, whereas only one was modified in its presence. From these observations, it is concluded that essential arginine residues are present at the substrate binding site.

Arginine↗
PubMed1997

Perineal canal.

Perineal canal (PC) is a rare anomaly constituting 4% of all anorectal malformations. Sixty patients (56 females and 4 males) with PC managed over the past 27 years are reported. The ages ranged from 2 days to 13 years. The chief symptom was passage of fecal matter through both the anus and the fistula. One girl had undergone previous, unsuccessful surgery. All our patients were treated by anterior sagittal anorectoplasty (ASARP), which allowed anatomic exposure and accurate repair of the anomaly. In 49 patients without any perineal inflammation primary ASARP was undertaken. Surgery was delayed in 11 patients with perineal excoriations and/or active inflammation. One patient died post-operatively due to unrelated causes and 1 developed a recurrence. Anal dilation was required in 7 cases. Fifty patients were seen at first follow-up 12 weeks after surgery. All were continent and had normal defecation without the use of laxatives. Thirty-four could be followed up to the age of 3 years; they were continent with normal bowel habits. There was no shift in the position of the anus and no instance of rectal dilation. Individualization of the management and operation by the anterior sagittal approach thus offers good results in this uncommon anorectal anomaly.

Adolescent↗
PubMed1997

Examination of soils from residential garbage in Betul, India, for fungi by the keratin baiting technique.

A report on an examination of soils from residential garbage of Betul, India, for fungi by the keratin (materials) baiting technique is presented. A total of 69 fungi representing 39 species among 17 genera were isolated. In all the soil samples, only two genera, namely Aspergillus (190.9%), followed by Fusarium (118.18%), were most frequently isolated. Maximum colonisation of fungi was found on hair, followed by horn, feathers and nails. For the first time, the genus Fusoma is reported here as a keratinophilic fungus. The keratin baiting technique was found very effective in detecting a broad spectrum of fungi in biological wastes and compost.

Aspergillus↗
PubMed1997

Bacillus species: the dominant bacteria of the rhizosphere of established tea bushes.

A number of species belonging to the genus Bacillus were found to be well adapted to the rhizoplane and rhizosphere of established tea bushes. Amongst the species, Bacillus subtilis and B. mycoides appeared to be closely associated with tea roots. The two species comprised a major part of the bacterial population, even during unfavourable periods. In extreme winter months the population of B. subtilis and B. mycoides were recorded upto 3.9 X 10(6) and 10(7) cells/g rhizosphere soil, respectively. The soil temperature during this period was in the range of 0 to 5 degrees C. Under laboratory conditions pure cultures of these Bacillus species did not grow upto 14 degrees C. While the pH of tea rhizosphere soil samples ranged from 4.3 to 6.3, these two species were able to grow at 28 degrees C in a much wider range of pH (4 to 12.0-12.5) under laboratory conditions. Survival of these bacterial species under adverse environmental conditions was probably due to their spore forming property. Various species of Bacillus behaved antagonistically amongst themselves, indicating perhaps to their bacteriocinogenic property. The observations also indicate that the tea bushes tend to make the soil acidic.

Bacillus↗
PubMed1997

Modification of an essential amino group of glutathione reductase from yeast by pyridoxal 5'-phosphate.

Yeast glutathione reductase is inactivated by pyridoxal 5'-phosphate (PLP). The reactivation of the enzyme by dilution as well as a characteristic absorption peak at 325 nm exhibited by NaBH4-reduced-PLP modified enzyme show that the inactivation is due to the specific modification of the epsilon-amino group of lysine residue. The maximum of 70% inactivation was observed at 7mM PLP and the equilibrium was reached within 3 min. Kinetic and equilibrium analysis of inactivation data derived at different PLP concentrations showed that a noncovalent intermediate is formed prior to inactivation. From the studies on the effect of pH on the inactivation rate, the pKa of epsilon-amino group of the reactive lysine residue was calculated to be 7.3. Among various protecting agents tried, only NADP was found to be effective. The apparent stoichiometry of the reaction was one to one as the incorporation of 0.65 mole PLP/mole of enzyme led to 70% inactivation at saturating PLP concentration.

Crystallography, X-Ray↗
PubMed1996

Direct association between the Ret receptor tyrosine kinase and the Src homology 2-containing adapter protein Grb7.

Adapter proteins containing Src homology 2 (SH2) domains link transmembrane receptor protein-tyrosine kinases to downstream signal transducing molecules. A family of SH2 containing adapter proteins including Grb7 and Grb10 has been recently identified. We had previously shown that Grb10 associates with Ret via its SH2 domain in an activation-dependent manner (Pandey, A., Duan, H., Di Fiore, P.P., and Dixit, V.M. (1995) J. Biol, Chem. 270, 21461-21463). We now demonstrate that the related adapter molecule Grb7 also associates with Ret in vitro and in vivo, and that the binding of the SH2 domain of Grb7 to Ret is direct. This binding is dependent upon Ret autophosphorylation since Grb7 is incapable of binding a kinase-defective mutant of Ret. Thus two members of the Grb family, Grb7 and Grb10, likely relay signals emanating from Ret to other, as yet, unidentified targets within the cell.

Cell Line↗
PubMed1996

Oncogenic RET receptors display different autophosphorylation sites and substrate binding specificities.

The c-ret proto-oncogene encodes a receptor tyrosine kinase which plays an important role in neural crest as well as kidney development. Genetic studies have demonstrated that germ line mutations in the ret oncogene are the direct cause of multiple endocrine neoplasia (MEN) 2A and 2B, familial medullary thyroid carcinoma (FMTC), and Hirschsprung's disease. However, despite the large body of genetic and biological evidence suggesting the importance of RET in development and neoplastic processes, the signal transduction mechanisms of RET remain unknown. To begin to understand the molecular mechanisms of the disease states caused by mutations in RET, the patterns of autophosphorylation of the wild-type RET and the MEN mutants were studied using site-directed mutagenesis and phosphopeptide mapping. Among the 6 autophosphorylation sites found in the wild-type RET receptor, the MEN2B mutant lacked phosphorylation at Tyr-1096, leading to decreased Grb2 binding, while simultaneously creating a new phosphorylation site. These changes in autophosphorylation suggest that the MEN2B mutation may result in the more aggressive MEN2B phenotype by altering the receptor's signaling capabilities.

Amino Acid Sequence↗
PubMed1996

Identification of cysteine and lysine residues present at the active site of beef liver glutamate dehydrogenase by o-phthalaldehyde.

Beef liver glutamate dehydrogenase (GDH) is inactivated by the bifunctional reagent, o-phthalaldehyde. The initial rate of inactivation follows pseudo first-order kinetics. The reaction of the enzyme with o-phthalaldehyde results in isoindole derivative formation which is characterized by typical fluorescence emission and excitation maximum at 410 nm and 337 nm, respectively. The inactivation of GDH by o-phthalaldehyde is partially prevented by alpha-ketoglutaric acid, whereas NADH does not provide any protection. This clearly indicates that cysteine and lysine residues are located near the alpha-ketoglutaric acid binding center. The dissociation constant of 2.2 mM was obtained for enzyme-alpha-ketoglutaric acid complex. Stoichiometry of o-phthalaldehyde binding with glutamate dehydrogenase showed that the formation of approximately one isoindole derivative per subunit of glutamate dehydrogenase is accompanied by complete loss of activity.

4-Chloromercuribenzenesulfonate↗
PubMed1996

Growth and cyclosporin A production by an indigenously isolated strain of Tolypocladium inflatum.

A fungal culture isolated from a local soil sample which showed antifungal activity and produced cyclosporin A, was identified as Tolypocladium inflatum. The culture grew best in a medium containing 1% maltose (pH 5-6) when inoculated with a one-day-old inoculum at 2% (V/V) concentration. Under batch fermentation conditions, growth and cyclosporin A production were better in complex media (24.6 g biomass and 205 mg cyclosporin A per liter) in comparison with synthetic media (6.84 g biomass and 35 mg cyclosporin A per liter). While addition of peptone increased culture growth (high biomass yield), supplementation with casein acid hydrolyzate favored cyclosporin A production.

Culture Media↗
PubMed1996

Congenital short colon.

Congenital short colon (CSC) is a condition in which the colon is replaced, wholly or partially, by a dilated pouch together with anorectal malformation and a colourinary fistula. Most of the reported series have been from northern India where this malformation is frequent. This paper details the management of 108 patients with CSC over a period of 23 years. The patients were classified into two types: (1) Partial short colon, where a segment of normal colon is present between the ileum and the sac. These patients could be treated by excision of the pouch and pull-through of the segment of normal colon during either single- or two-stage surgery. (2) Complete short colon, where the ileum opened directly into the sac, and formation of a tube from this sac (coloplasty) was required in one or more stages to provide a length of normally functioning colon. Review of the results showed staged management to be superior. The follow-up has ranged between 3 and 7 years, with satisfactory long-term results in both groups of patients. We have evolved a protocol for the management of CSC that has improved the prognosis and quality of life of these patients.

Abnormalities, Multiple↗