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S S Hwang

Publications and source records attributed to S S Hwang.

45 records · Page 3Linked to original sources
PubMed1985

General method for evaluating the fraction of the irreversible organ clearance due to conversion of drug to a primary metabolite.

An expression for the fractional metabolic clearance of a drug across an organ has been developed. The expression is a function of areas under the temporal profiles of the drug and metabolite concentrations in the sampling compartment. Formation of the metabolite of interest is permitted throughout the linear systems analyzed. The expression is shown to be applicable to any linear system provided there is only a single direct feed from the organ of interest (compartment where formation of the particular metabolite is being investigated) to the drug-sampling compartment.

Biotransformation↗
PubMed1985

Bioanalysis and disposition of alpha-fluoromethylhistidine, a new histidine decarboxylase inhibitor.

A sensitive, selective, and rapid high-performance liquid chromatographic procedure was developed for the determination of alpha-fluoromethylhistidine (alpha-FMH) in human biological samples. The plasma assay required isolation of the drug using a weak cation-exchange resin prior to HPLC analysis with UV detection. The urine assay employed postcolumn derivatization with o-phthalaldehyde (without a thiol) and fluorescence detection. The extent of metabolism of alpha-FMH in humans was studied in four healthy volunteers using tritium-labeled material. No significant differences in the plasma and urine concentrations of radioactivity and unchanged drug were detected. In addition, the radiochromatograms of selected urine samples revealed a single peak with a retention time corresponding to the unchanged drug. The evidence presented suggests negligible biotransformation of alpha-FMH in humans.

Biotransformation↗
PubMed1984

An assessment of the accuracy of a regional economic-demographic projection model.

A large number of regional economic-demographic projection models have been developed but their accuracy has seldom been evaluated. This article examines the accuracy of one such model in projecting total populations for 1980, using 1970 base data, for 106 counties and 553 places in two states. Comparisons of the model's projections to 1980 Census counts reveal mean percentage absolute differences of 10 percent for counties and 14 percent for places. In addition, the model's accuracy was comparable to that for alternative projection systems. When projections for places of less than 1,000 are excluded, differences are substantially reduced. Economic-demographic models appear to be quite useful and deserve further attention.

Demography↗
PubMed1977

Vaginal drug absorption in rhesus monkeys I: development of methodology.

Earlier reports from these laboratories described a procedure for determining vaginal drug absorption in the rabbit based upon a perfusion system, and data on the vaginal absorption of the straight-chain aliphatic alcohols and carboxylic acids were given. These studies have been extended to the rhesus monkey. Rib-cage-type cells were designed for intravaginal insertion through the vulval orifice and to fit the specific dimensions of the monkey vagina. The general design of the cell was similar to that used in the rabbit vaginal absorption studies. The persusion system was checked by using 3H-polyethylene glycol 4000, and no significant leaks from the cell were found. The absorption of the alcohols followed first-order kinetics. The computed apparent permeability coefficients for the alcohols were of comparable magnitude to those previously reported for the rabbit vaginal membrane.

Absorption↗
PubMedDate not supplied

Metanephric adenoma of the kidney: case report.

Metanephric adenoma is an extremely rare, epithelial, renal tumor with characteristic histology. This tumor is invariably benign. We report a case of metanephric adenoma diagnosed by ultrasound-guided needle biopsy.

Adenoma↗
PubMedDate not supplied

N-butyl-2-cyanoacrylate pulmonary embolism after endoscopic injection sclerotherapy for gastric variceal bleeding.

PURPOSE: The purpose of this work was to describe the radiologic and clinical manifestations of n-butyl-2-cyanoacrylate pulmonary embolism (PE) after endoscopic injection sclerotherapy (EIS) for gastric variceal bleeding. METHOD: From 1992 to 1999, the medical records of 140 patients who had undergone EIS using n-butyl-2-cyanoacrylate were reviewed for identification of respiratory symptoms and amount of injection, and their pre- and postprocedure chest radiographs were reviewed to identify PE. In patients with PE, pre- and postprocedure chest radiographs (6/6), chest CT scans (3/6), lung perfusion scans (3/6), and follow-up chest radiographs (6/6) were analyzed retrospectively. RESULTS: Radiographically evident PE was observed in 6 (4.3%) of 140 patients. In comparison with patients without emboli, these patients received a higher mean volume of injection (4.2 vs. 1.8 ml) (p = 0.0011). Four of the six patients with pulmonary emboli had respiratory symptoms. Chest radiographs and CT scans showed unusual tubular or nodular, radiopaque pulmonary emboli along the pulmonary vessels. Multiple peripheral, wedge-shaped, subsegmental perfusion defects were seen on perfusion lung scans. In five of six patients, the radiographic abnormalities showed complete or partial resolution. There were no fatalities directly associated with PE. CONCLUSION: Radiographically evident PEs are uncommonly observed following EIS and appear to be more common in patients receiving a higher volume of liquid acrylate. Affected patients were either mildly symptomatic or asymptomatic, and there were no direct fatalities of this complication.

Adolescent↗
PubMedDate not supplied

Kinetics of the tissue distributions of sulindac and metabolites. Relevance to sites and rates of bioactivation.

Sulindac (sulfoxide) is a prodrug in reversible metabolic equilibrium with its pharmacologically active metabolite, the corresponding sulfide. Following simultaneous parenteral injection of sulfoxide-14C and sulfide-3H at equivalent dosage, all labeled species in the plasma of rats and guinea pigs and in representative tissues were determined at various times. Rate constants for sulfoxide in equilibrium or formed from sulfide, calculated from the rates of interchange of the two labels in plasma, are still higher than those approximated from earlier, single-label studies, and indicate turnovers of total body pools every 45 and 8.5 min in rat and guinea pig, respectively. From the time-course of tissue/plasma ratios of endogenous labeled species, it can be concluded that kidney and liver are major sites of bioactivation of the prodrug, with significant sulfoxide leads to sulfide activity present in all tissues examined. At steady state, tissue concentrations of each redox form are determined by the ratio of the metabolic rate constants for the two opposing biotransformations and by unique tissue/plasma distributive constants for each redox form, resulting in all tissues, except lung, and at all times examined, in a sulfide/sulfoxide ratio greater than one.

Animals↗