Modification of the level of acetylcholinesterase activity by two oximes in certain brain regions and peripheral tissues of paraoxon treated rats

The diacetylmonoxime assay of urea, its application to the assay of diacetylmonoxime and a comparison with other methods for the analysis of diacetylmonoxime

The experiments reported herein were designed to identify the best assay of diacetylmonoxime (DAM) in biological fluids, with particular emphasis on detection limits. Initially, four variations of the assay of urea with excess DAM were compared. The best method, published in 1977, was one that includes thiosemicarbazide, 4-aminoantipyrine and ceric ammonium sulphate in the acid reagent; it is fast, gives a reasonably stable chromophore and displays good linearity. However, the reaction was two or more times less sensitive when applied to the assay of DAM, with urea in excess, by interchanging the amounts of urea and DAM. Further, the calibration graphs did not pass through the origin, and one of the methods gave a mixture of two chromophores. None approached the sensitivity of a DAM-urea reaction specifically designed to assay biacetyl (formed from DAM by acid hydrolysis) and published in 1968. This method, using antipyrine and arsenicosulphuric acid, is also fast, with good linearity and a stable chromophore, but is sensitive to interference by plasma and urine. An alternative photometric assay that does not involve urea was equally sensitive. It had the advantage of less interference by plasma and urine but was more time-consuming. Both of these photometric methods had a limit of detection of ca. 0.2 microgram DAM, similar to that of a high-performance liquid chromatography (HPLC) assay. Sample clean-up is necessary before application of the HPLC assay.

The therapeutic effects of 2,3-butanedione monoxime and atropine in severe dichlorvos intoxication in buffalo calves

2,3-Butanedione monoxime and atropine alone or in combination were evaluated for their ability to alleviate the toxicity and to reverse the biochemical changes induced by dichlorvos in the blood of buffalo calves. Treatment with 2,3-butanedione monoxime plus atropine 30 min after oral administration of dichlorvos (160 mg/kg) eliminated the apparent toxic signs within 10-15 min, completely prevented lethality, and reversed the dichlorvos-induced alterations in the concentrations of serum carboxylesterase, total plasma proteins, blood glucose and plasma cholinesterase within 2, 4, 12 and 168 h, respectively. Treatment with either 2,3-butanedione monoxime or atropine alone was less effective but the former was the more potent of the two in counteracting the biochemical effects of dichlorvos. These antidotal studies suggest that 2,3-butanedione monoxime in conjunction with atropine would provide effective therapy against severe dichlorvos intoxication in buffalo.

Effects of cholinesterase reactivators and atropine on fenitrothion-induced hypothermia in Bubalus bubalis

Oral administration of fenitrothion (435 mg/kg) produced a pronounced fall in rectal temperature and erythrocyte AChE activity in buffalo calves. Treatment with DAM alone or in conjunction with atropine at the time of severe toxicity (within 1 h) significantly (P less than 0.01) reversed fenitrothion-induced hypothermia and AChE inhibition. The temperature decrease and AChE inhibition were not significantly (P greater than 0.05) altered by either 2-PAM or atropine. It is concluded that DAM may be more effective than either 2-PAM or atropine in reversing hypothermic effect of OP insecticides.