Carbamate Poisoning Research Articles

Red cell and plasma cholinesterase activities in microsamples of human and animal blood determined simultaneously by a modified acetylthiocholine/DTNB procedure

A modification of the acetylthiocholine/DTNB method has been developed for the simultaneous determination of red cell and plasma cholinesterases in samples of only 0.01–0.03 ml of whole human and animal blood, using a relatively short incubation period of 10 min and an incubation temperature of 30°C. In contrast to many other micromethods, these test conditions allow activity determinations of cholinesterases inhibited by insecticidal carbamates in vivo, because decarbamylation of the enzymes after dilution is comparatively low after 10 min at 30°C. Human blood cholinesterases are assayed with propionylthiocholine, whereas for blood samples of various laboratory animals acetylthiocholine was found to be the better substrate. The experimental procedure of this micromethod is based on two cholinesterase measurements, of which the first determines total activity in whole blood, and the second, plasma cholinesterase activity alone. Erythrocyte cholinesterase activity is determined by subtraction. Normal activity values of the enzymes in red cells, plasma, and brain are given for a variety of species, and a few in vivo inhibition data after organophosphate and carbamate poisoning are also presented.

Pralidoxime chloride with atropine in dimpylate poisoning.

To the Editor:— Pralidoxime (Protopam) chloride is a cholinesterase reactivator that has been recommended in the treatment of organic phosphate intoxications. Pralidoxime (2 PAM), however, is contraindicated in carbamate poisoning. It appears to be most effective when used in conjunction with atropine therapy. Dimpylate (Diazinon [Britain]) is an organic phosphate insecticide of intermediate toxicity. Effective against a variety of household pests, it is the most widely used pesticide for roach control. Like other organic phosphate insecticides, it is a cholinesterase inhibitor. A number of published reports state that pralidoxime should not be used in dimpylate poisoning: Although oximes are effective antagonists to many of the cholinesterase inhibitors, there are some such compounds with effects that are either not antagonized by oximes or are made worse by their administration. In this latter group, the effects of Sevin or Diazinon are likely to be enhanced rather than antagonized. 1 In March 1967,

In vivo effects of carbamate insecticides on mammalian esterase enzymes

The in vivo antiesterase activity of three carbamate insecticides was examined by an abbreviated manometric assay. A comparison of this method with a potentiometric esterase assay indicated the feasibility of the abbreviated manometric assay for routine determination of reversible esterase inhibitors. The intensity of the cholinergic effects produced after carbamate intoxication correlated with the degree of cholinesterase inhibition. Inhibition and recovery of liver aliphatic esterase activity did not correlate with signs of poisoning. A comparison was made of the response of rat and mouse liver esterases to in vivo carbamate poisoning.