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Biomedical subjects

R I Ellin

Publications and source records attributed to R I Ellin.

At least 19 recordsLinked to original sources
PubMed1989

Carbamoylated enzyme reversal as a means of predicting pyridostigmine protection against soman.

The inhibition of human and mammalian red blood cell (RBC) cholinesterase (AChE) in whole blood in the presence of added pyridostigmine has been examined. After the addition of pyridostigmine to animal and human blood, red cells were separated from plasma at varying intervals and their enzyme activity measured. An apparent rate constant (ke) was derived for the reaction sequence in which carbamate is released from AChE inhibited by pyridostigmine. The constant is a complex of the rates of decarbamoylation and reinhibition of AChE in the blood sample. Rate constants were also determined for the spontaneous reactivation (ks) of carbamoylated AChE in the species studied. Values of Ks were greater than Ke in corresponding species but varied little between species. Pretreatment of animals with pyridostigmine is known to be an effective therapy against organophosphorus compounds, including soman. The ranking of ke values in mammalian blood was the same as that for the protection against soman in animals: monkey greater than guinea-pig greater than rabbit greater than rat (ke = 0.15, 0.07, 0.05, 0.02 h-1, respectively). Since ke for human blood (0.20 h-1) was greater than that of monkey, pyridostigmine pretreatment would be expected to be an effective prophylaxis for soman in humans.

Acetylcholinesterase↗
PubMed1985

Leaching of zinc compound from rubber stoppers into the contents of automatic atropine injectors.

This report describes how a material within the cartridge of an automatic injector contaminated its contents. On prolonged storage, a formulation that contained atropine produced lethality in mice. The toxic material originated from zinc compounds that were present in the rubber stopper and plunger of the container and that subsequently leached into the formulation. The contents of cartridges that contained greater than or equal to 0.75 mg/mL of solubilized zinc were lethal to at least 20% of the mice tested; those that contained 0.42 mg/mL showed no lethality. The problem resulted from the physicochemical properties of the rubber, not the concentration of zinc used in the vulcanization process.

Animals↗
PubMed1982

Method for isolation and determination of pyridostigmine and metabolites in urine and blood.

A procedure is presented for the unique isolation and determination by liquid chromatography of pyridostigmine and its metabolites in urine and blood. Isolation is accomplished by an extension of paired-ion theory using a reversed-phase chromatographic column. The assay of pyridostigmine is linear in concentrations from 40 to 5000 ng/ml. Separation and quantitation of pyridostigmine and metabolites in urine and blood are rapid. An analysis can be performed in 15 min. The method has been applied to the determination of urinary excretion and plasma levels of pyridostigmine administered intramuscularly in rats and to the isolation of acetylcholine, neostigmine, and edrophonium from aqueous solutions.

Animals↗
PubMed1982

Kinetics and stability of a multicomponent organophosphate antidote formulation in glass and plastic.

An aqueous solution of trimedoxime bromide, atropine, and benactyzine hydrochloride was formulated to have maximum stability as an antidote in organophosphorus poisoning. The stability of the mixture in glass and plastic cartridges was determined. Glass cartridges were more desirable than plastic; there was less vapor loss, color formation, and anomalous reaction. Trimedoxime was stable, losing 1.4% of its potency after 1 year at 25 degrees and atropine was more stable than trimedoxime. Considerable degradation of benactyzine occurred; 20% of its potency was lost after 1 year at 25 degrees. Equations for predicting the shelf life of each ingredient at selected temperatures are presented.

Antidotes↗
PubMed1982

Stability of concentrated aqueous solutions of pralidoxime chloride.

Concentrated aqueous solutions of pralidoxime chloride degrade more rapidly than dilute solutions. The rate and degree of degradation is dependent on the initial and final pH as well as the container in which the solution is stored. The effects of glass, metal, plastic, and rubber stoppers on the stability of concentrated and dilute solutions are discussed. The stability and shelf lives of 50% aqueous concentrates at different temperatures were determined.

Drug Packaging↗
PubMed1981

The stability of sarin and soman in dilute aqueous solutions and the catalytic effect of acetate ion.

The hydrolysis of aqueous solutions of organophosphonate compounds such as sarin and soman is a critical factor in biochemical and therapeutic studies. The ability to dilute and transport these compounds with assurance of their purity is imperative to the integrity of such studies. An enzymic method has been used to measure low levels of organophosphonates. Maximum stability data were determined in aqueous and isotonic saline solutions. Acetate ion was found to significantly accelerate hydrolysis.1

Acetates↗
PubMed1977

Quantitative assay of physostigmine in human whole blood.

A quantitative assay for measuring physostigmine in human whole blood is described. Blood samples are maintained at 37 degrees, and cholinesterase activity is measured periodically. The time required for enzyme reactivation is related to physostigmine concentration. The precision of the method is within +/- 4% over a physostigmine concentration range of 0.5-5.0 x 10(-7) M.

Cholinesterase Inhibitors↗
PubMed1975

Delta-pH method for measuring blood cholinesterase. A study on the effect of temperature.

Efforts to evaluate precision of the Michel delta pH method for blood cholinesterase, performed in a beaker immersed in a 25 C water bath, resulted in unexpected variability in results of daily and day-to-day replicate analyses. Most disturbing was the considerable variation between each four-hour period of an eight-hour day (AM and PM measurements). Precision of quadruplicate sets, expressed as coefficient of variation, ranged from plus or minus 0.5% to 8.5%. By rigidly controlling temperature with a water-jacketed reaction vessel the variation was reduced to plus or minus 1.7%. A study of effect of temperature on the method showed that a one-degree change in temperature resulted in a 5.5% change in plasma activity and a 3.0% change in red blood cell (RBC) activity. A graphing of the influence of temperature on reaction rate produced a linear relationship. Identical thermodynamic data were obtained with plasma and RBC samples that were inhibited 50% with an irreversible anticholinesterase agent.

Cholinesterases↗