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Biomedical subjects

R Prasad

Publications and source records attributed to R Prasad.

At least 217 records · Page 12Linked to original sources
PubMed1991

Vanadate-resistant mutants of Candida albicans show alterations in phosphate uptake.

Phosphate uptake studies in different strains of the dimorphic pathogenic yeast Candida albicans were undertaken to show that this yeast actively transported phosphate with an apparent Km in the range of 90-170 microM. The uptake was pH dependent and derepressible under phosphate starvation. Vanadate-resistant (van) mutants of C. albicans showed a 20-70% reduction in the rate of phosphate uptake in high phosphate medium and was associated with an increased Km and reduced Vmax. The magnitude of derepression under phosphate starvation was different between van mutants. These results demonstrate that van mutants may have developed resistance by modifying the rate of entry of vanadate.

Biological Transport↗
PubMed1991

Nucleotide sequence analysis of purH and purD genes from Salmonella typhimurium.

The purH and purD genes coding for the 5'-phosphoribosyl 5-amino-imidazole-4-carboxamide (AICAR) transformylase and 5'-phosphoribosyl-glycinamide (GAR) synthetase, respectively, were identified on a 4.8 kb Eco RI fragment of chromosomal DNA from Salmonella typhimurium. Nucleotide sequence analysis of the cloned fragment revealed the presence of two large open reading frames (O.R.F.), which were separated by 11 base pairs (bp). Substantial DNA and amino acid sequence homology was noted between the purH and purD genes of S. typhimurium and Escherichia coli. Expression of the Salmonella purD gene in a T7 polymerase/promoter system revealed the presence of a 49 kDa protein band by SDS-PAGE and subsequent autoradiography. The purH gene of Salmonella was not expressed since the 5' end of this gene was not cloned.

Acyltransferases↗
PubMed1991

Enterotoxin-associated DNA sequence homology between Salmonella species and Escherichia coli.

Multiple HindIII-restriction fragments of Salmonella typhimurium and Salmonella typhi chromosomal DNA exhibited homology with the heat-labile enterotoxin (LT1) gene of Escherichia coli as determined by Southern blot analysis. A 9.4 kb HindIII restriction fragment identified in S. typhimurium and S. typhi chromosomal DNA reacted with both eltA and eltB gene probes. However, the homology of the 9.4 kb DNA fragment from these Salmonella species was greater with eltB than eltA. In addition, a synthetic oligonucleotide probe, made to a portion of the putative GM1-ganglioside binding region of cholera toxin (CT) and LT1, hybridized with the 9.4 kb DNA fragment of S. typhimurium but not with the 9.4 kb fragment found in S. typhi isolates. The hybridization of multiple restriction fragments of Salmonella DNA with eltA and eltB gene sequences further suggests duplication of the stx operon on the chromosome of these bacteria.

Amino Acid Sequence↗
PubMed1991

Education, fertility and contraception among Hindus and Roman Catholics in Goa.

Differences in age at marriage, fertility and contraceptive use are related to religious background, individual educational level and community level education. In general, the effects of community education are weak compared to individual level of education, but differences exist between Hindus and Roman Catholics.

Adult↗
PubMed1991

Transesophageal echocardiographic evaluation for mural thrombus following radiofrequency catheter ablation of accessory pathways.

BACKGROUND: Catheter ablation of accessory pathways (APs) provides a definitive therapy for patients with Wolff-Parkinson-White Syndrome. The reported incidence of thrombus formation on ablation-induced injuries with direct current shock varies from 0%-20% in animal studies. The purpose of this study was to determine the prevalence of mural thrombus following catheter ablation with radiofrequency current of accessory pathways in humans. METHODS AND RESULTS: Radiofrequency current (30-35 watts) was applied through a catheter electrode placed against the mitral or tricuspid annulus guided by catheter recordings of AP potentials. Transthoracic (TTE) and transesophageal echocardiography (TEE) were performed in 95 of 111 patients, at 18 +/- 6 hours following catheter ablation. After ablation, no thrombus was identified at or near the ablation site in any patient. Two out of 95 patients had a mural thrombus at a remote site that was detected by TEE but not by TTE. No new wall motion abnormality was detected in any patient. No significant regurgitant valvular lesion was found in any patient. CONCLUSION: Intracardiac thrombus was not identified at the site of catheter ablation, possibly owing to the small lesions produced by radiofrequency energy and high blood flow normally present in those areas. However, patients may be at small risk for mural thrombus at a remote site from prolonged placement of catheters.

Adult↗
PubMed1991

Isolation, purification and kinetic characterization of plasma membrane H(+)-ATPase of Candida albicans.

The plasma membrane ATPase of Candida albicans was solubilized by Tween 40 and purified to homogeneity on glycerol step gradient. The purified protein appeared as a single band of 100 +/- 4 KDa, represented greater than 98% of the total pure protein on densitometer scan. The purified PM-ATPase which was very specific to MgATP, had Km of about 0.77 mM and a sharp pH optimum at 6.6. Orthovanadate was able to inhibit the enzyme in a non-competitive manner, however, at higher concentrations the nature of inhibition changed to uncompetitive type. Based on molecular size, immuno cross-reactivity and sensitivity to different inhibitors, PM-ATPase of C. albicans appears to be similar to other ion pumps.

Adenosine Triphosphate↗
PubMed1991

General practitioner referrals to specialists.

A survey of referrals by general practitioners to medical specialists was carried out to determine current referral patterns, and to compare them with two earlier Australian studies. The mean referral rate was 6 per cent of all consultations, with the four most frequent specialty groups referred to being proceduralists. A comparison with two previous Australian surveys reveals minimal change in general practitioner referral patterns in 18 years. The need to study the appropriateness of general practitioner referrals further is stressed.

Australia↗
PubMed1990

An evaluation of the biological response to Fraxiparine, (a low molecular weight heparin) in the healthy individual.

The tolerance of a low molecular weight heparin (Fraxiparine, Choay, Paris, France) in normal individuals was determined using a two part investigation. Study 1 consisted of administering escalating doses of Fraxiparine in a single blinded, placebo controlled, rising dose tolerance evaluation. The daily doses tested were 3750 U AXA IC, 7500 U AXa IC, 11250 U AXa IC, 15000 U AXa IC, and 22500 U AXa IC Fraxiparine subcutaneously for 5 consecutive days. In study 2, we compared the tolerance of unfractionated heparin (UH) administered as 5000 IU every 8 hours, to that of 7500 U AXa IC/day or 15000 U AXa IC/day of Fraxiparine administered once daily. Our results indicated very good tolerance to this low molecular weight heparin (LMWH) at doses up to and including 22500 U AXa IC/day. We observed significantly elevated increases in transaminases following LMWH administration. In our second study we observed that the increase in serum transaminases seen after 15000 U AXa IC/day Fraxiparine was without significant difference from that observed following UH (5000 IU every 8 hours). AXa examination revealed an accumulation of AXa effect after 5 days of administration at doses greater than 15000 U AXa IC, and there was good correlation between AXa and APTT at Fraxiparine doses greater than 15000 U AXa IC/day. No thrombocytopenia was associated with Fraxiparine. We conclude that Fraxiparine is relatively well tolerated and shows accumulation after daily dosing with greater than 15000 U AXa IC.

Adult↗
PubMed1990

Biological and immunological characterization of a cloned cholera toxin-like enterotoxin from Salmonella typhimurium.

A chromosomal DNA fragment, encoding an enterotoxin gene of Salmonella typhimurium Q1, was cloned into bacteriophage EMBL3 and plasmid vector pBR322. The recombinant clones lambda B8 and pC1 were identified using a synthetic oligonucleotide probe made to the B subunit region of the cholera toxin gene (ctx). Cell lysates of Escherichia coli VCS257 [lambda B8] induced fluid secretion in rabbit intestinal loops, while lysates of E. coli DH5 alpha [pC1] failed to elicit an enterotoxic response in this model. Both lysates and partially purified preparations elongated Chinese hamster ovary (CHO) cells, elevated cellular cAMP and PGE2, and bound to ganglioside GM1. The biological activity associated with the cloned enterotoxin was neutralized by monospecific antiserum to cholera toxin (CT). Immunoblots of pC1 and lambda B8 lysates probed with anti-CT, exhibited a 30 kDa protein similar to that of pJM17, which carried the ctx gene. Under non-dissociating conditions, anti-CT immunoblots of the same lysates revealed two proteins, one corresponding in size to the holotoxin and the other to CT-A. When analysed by DNA-directed protein synthesis in vitro, both pC1 and lambda B8 DNA expressed two unique proteins (30 and 11 kDa) similar to that of pJM17.

Animals↗
PubMed1990

The importance of dose-intensity in neoadjuvant chemotherapy of osteosarcoma: a retrospective analysis of high-dose methotrexate, cisplatinum and adriamycin used preoperatively.

The relationship between dose-intensity and outcome was retrospectively analyzed in 125 patients with osteosarcoma of the extremities treated at our institution with neoadjuvant chemotherapy between 1986 and 1988. Before surgery, chemotherapy was performed with high-dose methotrexate (HDMTX) i.v. followed by cisplatinum (CDP) i.a. and adriamycin (ADM) i.v. Postoperative chemotherapy was tailored according to the necrosis induced by preoperative treatment. Patients who were "good responders" had 31-weeks of chemotherapy with the same drugs utilized preoperatively, while "poor responder" patients received a longer treatment (40 weeks) in which ifosfamide and etoposide (VP-16) were added to HDMTX, CDP and ADM. At a median follow-up of 2 years (1-3 years) 100 patients (80%) remained continuously disease-free and 25 patients relapsed: 24 with lung metastases and 1 with local recurrence. According to the real dose-intensity received, calculated as a percentage of the dose intensity projected by the protocol, the continuously disease-free survival was 87% in the 82 patients who received 80% or more of the scheduled dose-intensity and only 65% for the 43 patients who received less than 80% of the projected dose-intensity. This difference is highly significant (P less than 0.01). These results suggest that in neoadjuvant chemotherapy of osteosarcoma the real dose-intensity delivered is a determinant of treatment outcome and therefore every effort should be made to avoid reductions of doses and delays of cycles of chemotherapy in these patients.

Adolescent↗
PubMed1990

Defective plasma membrane H(+)-ATPase or orthovanadate resistant mutants from Candida albicans, a pathogenic yeast.

Orthovanadate-resistant mutants of diploid yeast Candida albicans were isolated by using two step mutational process. Such mutants had altered plasma membrane H(+)-ATPase activity. Based on the levels of PM-ATPase activity, these mutants could be grouped into two categories; one group included those mutants which did not exhibit reduction in PM-ATPase activity while the other displayed a reduction of upto 40% in enzyme activity. These mutants exhibited a number of distinct phenotypic characteristics and altered abilities with regard to phenotypic divergence. Results demonstrate the importance of PM-ATPase in overall physiology of this pathogenic yeast.

Animals↗
PubMed1989

Direct scavenging of free radicals by captopril, an angiotensin converting enzyme inhibitor.

Captopril, an angiotensin converting enzyme (ACE) inhibitor, was hypothesized to be a potential scavenger of free radicals because of the presence of a thiol group. The scavenging action of captopril was examined against superoxide anion (O2-), hydroxyl radical (OH.), hypohalite radical (HOCL) either generated biochemically, or derived from activated polymorphonuclear leukocytes (PMN). Our results indicate that captopril is an extremely potent free radical scavenger, scavenging power being as effective as superoxide dismutase (SOD) against O2-, or dimethylthiourea against OH., but better than allopurinol against OCL. plus HOCL. Free radical scavenging action of captopril against PMN-derived free radical is equivalent to the combined effects of SOD, catalase and allopurinol.

Allopurinol↗