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Biomedical subjects

R Nagarajan

Publications and source records attributed to R Nagarajan.

At least 55 records · Page 3Linked to original sources
PubMed1993

Effect of cilazapril on exercise tolerance in congestive heart failure.

Cilazapril (C), an angiotensin-converting enzyme inhibitor with effective antihypertensive efficacy, was examined for its ability to alter exercise tolerance testing (ETT) and respiratory oxygen uptake in 33 patients with congestive heart failure (CHF). C was administered in capsules daily to patients with New York Heart Association Class II or Class III CHF for 12 weeks, in parallel double-blind treatment groups of 0 mg (n = 8), 0.5 mg (n = 8), 1.0 mg (n = 9), and 2.5 mg (n = 8). The blood pressure (BP) was reduced by 2.5 mg C: systolic BP (SBP) from 126 to 114 mm Hg; diastolic BP from 76 to 69 mm Hg. The maximum heart rate (MHR) during ETT was increased by 2.5 mg C from 137 to 143 bpm, as was the double product (MHR x maximum SBP x 0.01) from 237 to 251. There was an insignificant change in duration of exercise (548-610 s), anaerobic threshold (AT), and maximum oxygen uptake (14.1-15.7 ml/kg/min). The results suggest a positive effect of 2.5 mg C on energy utilization in CHF patients.

Aged↗
PubMed1993

Post-penetrating keratoplasty glaucoma.

To study the risk factors in the development of glaucoma following penetrating keratoplasty, we retrospectively analysed 190 eyes of 185 consecutive patients who had undergone surgery during 1990. The donor button was larger by 0.2 mm and 0.5 mm in phakia and aphakia/pseudophakia patients, respectively. Over a mean follow-up period of 14.5 months, 52 of the 190 eyes (27.4%) either developed glaucoma de novo or had worsening of preexisting glaucoma. Of these 52 eyes, 38 were managed medically and 14 required surgery. From our study, aphakia (37%), pseudophakia (24%), preexisting glaucoma (81.8%), and regrafting (43.18%) were found to be the significant risk factors in the development of glaucoma following penetrating keratoplasty.

Aphakia, Postcataract↗
PubMed1990

A mathematical model for Rn sampling by activated C adsorption.

This paper describes a diffusion/adsorption model that has been developed for the transport of Rn in an activated carbon porous bed. It is useful in studying the carbon canister Rn sampling technique used for monitoring Rn levels in air. The model calculates the amount of Rn adsorbed by the canister for various situations. The predictions of the response of the canister to both constant, as well as a periodic varying concentration of Rn in the surroundings, compares very well with experimental data. Based on this model, it is possible to simulate on a computer the response of the canister for an arbitrarily varying surrounding Rn level. Such computer simulations are effective tools in the design of a more accurate carbon canister monitor.

Adsorption↗
PubMed1990

Actions of the opioid antagonist, nalmefene, and congeners on reperfusion cardiac arrhythmias and regional left coronary blood flow.

Opioid antagonists have been shown to prevent the occurrence of lethal arrhythmias following coronary reperfusion. In this study, we have examined the effect of a new, long-lasting, potent opioid antagonist, nalmefene, and congeners in the prevention of reperfusion arrhythmias in dogs. Nalmefene given at a dose of 1 mg/kg i.v. reduced the incidence of reperfusion arrhythmias significantly when compared to the saline control. Neither N-methyl nalmefene, a quaternary analog that does not cross the blood brain barrier, nor (+) nalmefene, an isomer with no anti-opioid actions, provided any protection against reperfusion arrhythmias. Regional myocardial blood flow profiles, during and after coronary occlusion, were not different between the nalmefene- and saline-treated groups. We conclude that nalmefene prevents the occurrence of reperfusion-induced arrhythmias by blocking opioid receptors in the brain.

Animals↗
PubMed1989

Activity of glycopeptides against vancomycin-resistant gram-positive bacteria.

Gram-positive bacteria resistant to vancomycin are rare; but they include members of the genera Leuconostoc, Lactobacillus, and Pediococcus, as well as recently emerging vancomycin-resistant strains of Enterococcus faecium and Enterococcus faecalis. Vancomycin, teicoplanin, and several vancomycin derivatives were tested for their activities against vancomycin-resistant gram-positive bacteria. Vancomycin-resistant E. faecium and E. faecalis were generally cross-resistant to other glycopeptides, but some N-substituted vancomycin derivatives were active against the resistant strains, with MICs of 2 to 32 micrograms/ml. These vancomycin derivatives also had significant levels of activity against intrinsically vancomycin-resistant organisms such as Leuconostoc sp. While vancomycin resistance in E. faecium and E. faecalis was inducible, resistance in members of the genera Leuconostoc, Lactobacillus, and Pediococcus appeared to be expressed constitutively. Antibody to a vancomycin-induced membrane protein found in membranes of resistant enterococci did not detect a cross-reacting protein in other vancomycin-resistant species.

Drug Resistance, Microbial↗
PubMed1989

Synthesis and antibacterial evaluation of N-alkyl vancomycins.

Over eighty N-alkyl vancomycins were synthesized by reductive alkylation of vancomycin with the appropriate aldehydes. The N-alkyl vancomycins exhibit greater antibacterial activity than the corresponding N-acyl vancomycins and the parent antibiotic. Some of these semisynthetic vancomycins are five times more active than vancomycin. The N-alkyl vancomycins also show longer elimination half-lives in rats than vancomycin.

Animals↗
PubMed1988

Synthesis and antibacterial activity of N-acyl vancomycins.

Several glycopeptides containing N-acyl groups have been isolated recently. We undertook the synthesis of N-acyl vancomycins, using the active ester method. The in vitro and in vivo antibacterial activity were evaluated, and structure-activity relationship of this series of semisynthetic vancomycins is discussed.

Animals↗