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Biomedical subjects

J L Way

Publications and source records attributed to J L Way.

62 records · Page 4Linked to original sources
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In vitro studies on sterically stabilized liposomes (SL) as enzyme carriers in organophosphorus (OP) antagonism.

This study describes a new approach for organophosphorous (OP) antidotal treatment by encapsulating an OP hydrolyzing enzyme, OPA anhydrolase (OPAA), within sterically stabilized liposomes. The recombinant OPAA enzyme was derived from Alteromonas strain JD6. It has broad substrate specificity to a wide range of OP compounds: DFP and the nerve agents, soman and sarin. Liposomes encapsulating OPAA (SL)* were made by mechanical dispersion method. Hydrolysis of DFP by (SL)* was measured by following an increase of fluoride ion concentration using a fluoride ion selective electrode. OPAA entrapped in the carrier liposomes rapidly hydrolyze DFP, with the rate of DFP hydrolysis directly proportional to the amount of (SL)* added to the solution. Liposomal carriers containing no enzyme did not hydrolyze DFP. The reaction was linear and the rate of hydrolysis was first order in the substrate. This enzyme carrier system serves as a biodegradable protective environment for the recombinant OP-metabolizing enzyme, OPAA, resulting in prolongation of enzymatic concentration in the body. These studies suggest that the protection of OP intoxication can be strikingly enhanced by adding OPAA encapsulated within (SL)* to pralidoxime and atropine.

Animals↗
PubMedDate not supplied

Fluorometric determination of cyanide in biological fluids and pyridoxal.

Investigations of the physiological disposition of cyanide during thiosulfate therapy has necessitated the development of a convenient and sensitive method for cyanide analysis. A fluorometric method involving the catalytic conversion of pyridoxal to 4-pyridoxylactone was adapted for use with biological fluids by employing microdiffusion analysis. The presence of the cyanide antagonist, sodium thiosulfate, interferes with the formation of the fluorophore. In order to circumvent this interference, the pH of the diffusion media was altered to selectively diffuse cyanide. After testing various acidifying agents, an acetate buffer (pH = 5.2) was determined to be satisfactory. The fluorometric method was then correlated with the classical colorimetric procedure by an in vivo study. Blood from mice treated with sodium nitrite and sodium thiosulfate, prior to receiving potassium cyanide, was analyzed by both procedures and no significant difference was demonstrated between the results of the two methods of analysis.

Animals↗
PubMedDate not supplied

Metabolic disposition of the alkylphosphate antagonist, 1,1'-trimethylenebis(4-aldoximinopyridinium) ion (TMB-4), in the rat. III. Trimethylene-1-(4-aldoximinopyridinium)-1'-(4-carboxamidopyridinium) ion.

1,1'-Trimethylene [1,1'-14C]bis(4-aldoximinopyridinium) ion (TMB-4) was synthesized and its metabolic disposition was investigated in vivo. Rats were administered multiple doses of TMB-4 (25 mg/kg) by the intraperitoneal route and urine was collected over a 48-hr period. Approximately 98% of the administered radioactive dose could be accounted for in the urine during that time. A urinary metabolite, trimethylene-1-(4-aldoximinopyridinium)-1'-(4-carboxamidopyridinium) ion (TACARB), was isolated by ethanol extraction, charcoal adsorption chromatography, and ion-exchange chromatography. The metabolite was then characterized by comparing its spectral, chromatographic, and electrophoretic properties with those of authentic TACARB ion. Possible reaction mechanisms involved in the biochemical pathways for the formation of this metabolite from TMB-4 are discussed.

Animals↗
PubMedDate not supplied

Cyanide antagonism.

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Animals↗
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Bond strength of light-cured glass ionomers to carious primary dentin.

The pre-cooperative or handicapped child with decay presents a special challenge to the practitioner and may require sedation or general anesthesia. Treatment with an interim restoration may delay treatment until the child is more mature and can accept dental treatment and is a more conservative approach than sedation, extractions or general anesthesia. Glass ionomer materials have been utilized for this application, but little is known about their retention to carious dentin. The purpose of this study was to determine whether the presence of artificial dentin decay will affect the shear bond strength of two light-cured glass ionomer materials. VariGlass and Vitrebond glass ionomer materials were attached to carious and non-carious primary dentin surfaces and bond strengths determined. There were no significant differences in shear bond strengths between the decayed and non-decayed surfaces [p < or = .001]. VariGlass had higher shear bond strengths than Vitrebond only after a pre-treatment with the PAA containing liquid. Pre-treatment with the liquid provided with each light-cured glass ionomer was beneficial in all instances except for Vitrebond on non-decayed surfaces.

Acid Etching, Dental↗