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Biomedical subjects

S Mantha

Publications and source records attributed to S Mantha.

9 recordsLinked to original sources
PubMed1992

Radioimmunoassay for ceronapril, a new angiotensin-converting enzyme inhibitor, and its application to a pharmacokinetic study in healthy male volunteers.

Ceronapril is a member of a new chemical class of angiotensin-converting enzyme inhibitors being developed by The Bristol-Myers Squibb Pharmaceutical Research Institute. A radioimmunoassay (RIA) has been developed for the measurement of ceronapril in biological fluids. The RIA has a range of 0 to 500 ng/ml and has the sensitivity to detect 1.0 ng/ml of ceronapril. Satisfactory zero binding and sensitivity were obtained after a 2-h incubation at room temperature or overnight at 4 degrees C. Separation of the antibody-bound and free radiolabel was achieved by employing polyethylene glycol-goat anti-rabbit gamma-globulin separant. A quantitative recovery of the exogenous analyte was obtained at all concentrations of ceronapril tested. Intraassay coefficients of variance (CV's) were 3.9% and 4.6% for the low and medium controls, respectively. A highly significant statistical correlation between RIA and [14C]TLRC was observed for both plasma and urine samples. Clinical samples from the ascending dosage studies have been analyzed by the ceronapril RIA. The maximum concentration and the area under the plasma concentration-time curve did not increase in a dose-proportional manner for doses above 100 mg.

Adult↗
PubMed1992

A radioimmunoassay for the new antiviral agent 1-beta-D-arabinofuranosyl-E-5-(2-bromovinyl)uracil.

A specific and sensitive radioimmunoassay (RIA) for the measurement of 1-beta-D-arabinofuranosyl-E-5-(2-bromovinyl)uracil (BV-araU) in biological fluids has been developed. The assay has a range of 2.5-1,000 ng/ml and 10-1,000 ng/ml for serum and urine, respectively, and has the sensitivity to detect 2.5 and 25 ng/ml of BV-araU in serum and urine, respectively. A satisfactory zero binding and sensitivity were obtained after an overnight incubation at 4 degrees C. Separation of the antibody-bound and free ligand was achieved by employing polyethylene glycol-goat anti-rabbit gamma globulin separant. A quantitative recovery of the exogenous analyte was obtained at all concentrations of BV-araU tested. The assay is specific for the parent drug and is not affected by the presence of its metabolite, BV-U (bromovinyl uracil) or serum components (nucleotides, nucleosides, or sugars). Intraassay coefficients of variation were 3.1-4.4% and 2.5-4.2% for serum and urine controls, respectively. Interassay variability was < 8.6% for all serum and urine controls. Linear regression analysis showed that the correlation between RIA and high-pressure liquid chromatography was excellent (r = 0.997). The ascending dosage studies have been analyzed by the BV-araU RIA, and results indicate that the values of area under the serum concentration-time curve increased proportionally with the administered dose of BV-araU up to 80 mg. Cumulative urinary excretion data showed that approximately 50% of unchanged BV-araU was excreted in the urine within 24 h.

Antiviral Agents↗
PubMed1991

Reaction of gadolinium chelates with endogenously available ions.

The extent of reaction of 153Gd-radiolabeled Gd(L) chelates with 25 mM CO23- (25 mF), PO34-, Zn2+ and Cu2+ at pH 7 was determined for L = EDTA, DTPA, DOTA, HP-DO3A, and DO3A. Gd(EDTA)- and Gd(DTPA)2- reacted (greater than 20% in 10 min) with Cu2+ and Zn2+ in the presence of PO34-. These double replacement reactions yielded precipitated GdPO4 and chelated Cu(L). Gd(HP-DO3A), Gd(DO3A) and Gd(DOTA)- were inert to reaction with all four ions at room temperature (less than or equal to 1% reaction detected). The thermodynamic binding constants of the ligands for Gd3+ and Cu2+ were found to be equal (10(20) M-1) for DO3A, while DOTA and HP-DO3A favored Gd3+ over Cu2+ by greater than or equal to 10(2) M-1. The low order of reactivity of Gd(DOTA)- and Gd(HP-DO3A) was anticipated by the binding constants, but the lack of reactivity of Gd(DO3A) is attributed to kinetic inertia. This latter property, desirable in MRI contrast agents, is promoted by the conformational stability of the tetraazacyclododecane macrocycle, which forms the backbone of the ligand. It is concluded that this class of chelates is exceptionally inert in solutions of endogenously available ions, and that thermodynamics alone is an insufficient predictor of the reactivity of the highly inert Gd complexes based on the tetraazamacrocycle.

Contrast Media↗
PubMed1991

Visual evoked potentials and visual acuity after transurethral resection of the prostate.

Changes in visual evoked potentials, visual acuity, blood ammonia levels and serum electrolytes (Na+ and K+) after transurethral resection of the prostate using glycine as an irrigating fluid performed under subarachnoid block were studied in 12 patients, in the pre-operative and immediate postoperative periods. Visual evoked potentials (p100 latency), recorded by shift of a checkerboard pattern, increased significantly from a pre-operative value of mean (SEM) 101.18 (1.63) msec in the right eye, and 102.5 (1.47) msec in the left eye to 108.91 (1.8) msec (p less than 0.01) and 108.08 (2.53) msec (p less than 0.01) respectively in the postoperative phase. There were no changes in visual acuity as assessed by a Snellen's chart, blood ammonia levels and serum electrolyte concentrations. The amount of glycine used intra-operatively for irrigation ranged from 3 to 31 litres.

Aged↗