Antidotal action of atropine sulfate against insecticide benfuracarb poisoning in rats.

The antidotal action of atropine sulfate and 2-pyridine aldoxime methiodide (2-PAM) against poisoning attributable to the new procarbamate insecticide benfuracarb [(ethyl N-[2,3-dihydro-2,2-dimethylbenzofuran-7-yloxycarbonyl (methyl) aminothio]-N-isopropyl-beta-alaninate] was compared utilizing rats as our experimental model. Both the intraperitoneal and oral administrations of these antidotes were examined after five, ten, fifteen and thirty minutes exposure periods, following treatment with benfuracarb at dose levels approximating LD50 and LD100. The results obtained demonstrate that both the intraperitoneal and oral administrations of atropine sulfate blocked or significantly reduced the toxic effects of benfuracarb and protected the animals from death. The intraperitoneal administration route appears to be more effective than was the oral route. In addition, the administration of atropine sulfate after the shorter period (up to 15 minutes), following exposure to benfuracarb, improved antidotal action, particularly with the LD100 dose of benfuracarb. It is suggested that atropine sulfate antagonizes benfuracarb poisoning by blocking acetylcholine (ACh) receptors, as many other carbamate insecticides, since benfuracarb was an in vivo cholinesterase (ChE) inhibitor and the toxic effect of benfuracarb was reduced by atropine sulfate. 2-PAM, however, did not significantly block or reduce the toxic effects of benfuracarb.

[Research related to pressures under dentures. The effect of differences in impression pressure with special reference to unilateral mandibular free-end edentulousness].

The purpose of this paper is to investigate the difference of impression pressure under denture bases made by the pressure impression-taking method, which considers the resiliency of ligaments under abutment teeth and mucosa under dentures, and under those made by the non-pressure impression-taking method, and then analyzed its influence on the distribution of pressure curve produced by bite force with the case of unilateral mandibular free-end edentulousness. The findings were as follows: 1. As for the pressures under the dentures, dentures made by the pressure impression-taking method in all cases showed an apparent increase at the mesial part, while at the distal part, a decrease was detected in three out of five patients. 2. The pressure curve caused by bite force tended to rise sharply immediately before the application of maximum bite force. 3. Ratio of pressures resulting from the increased bite force tended to increase with dentures using the non-pressure impression-taking method, while dentures using the pressure impression-taking method showed a clear tendency to equalize toward 0.5, regardless of the values of the bite force.

Toxicological properties of phosphorothioate and related esters present as impurities in technical organophosphorus insecticides.

O,O,S-Trimethyl phosphorothioate, an impurity in several technical organophosphorus insecticides, when administered orally to rats at single doses as low as 15 mg/kg caused delayed mortality, with death occurring 4-22 d after treatment. Delayed toxic signs were also observed in mice, but mice were generally less sensitive than rats. O,O,S-triethyl phosphorothioate and O,S,S-trimethyl phosphorodithioate induced the same signs of intoxication at slightly higher doses. Rats treated with O,O,S-trimethyl phosphorothioate refused food and water within 24 h after treatment and did not eat or drink until the time of death. Neither injection of nutrient solution nor atropine served to reduce or block intoxication. However, the isomeric O,O,O-trimethyl phosphorothioate was a potent antagonist of the toxicity of O,O,S-trimethyl phosphorothioate. As little as 1% of the O,O,O-trimethyl isomer protected rats from the intoxicating effects of the O,O,S-trimethyl isomer at doses as high as 200 mg/kg. Rat serum carboxylesterase and cholinesterase were inhibited for prolonged periods after a single oral dose of O,O,S-trimethyl phosphorothioate, but the duration of inhibition was significantly less when the toxicant contained 1% O,O,O-trimethyl isomer.

Nature of N-S bond cleavage of 2,3-dihydro-2,2-dimethyl-7-benzofuranyl (di-n-butylaminosulfenyl) (methyl)carbamate.

The cleavage of the N-S bond in 2,3-dihydro-2,2-dimethyl-7-benzofuranyl (di-n-butylaminosulfenyl) (methyl)carbamate was examined in different buffer solutions (hydrolysis), in buffer solution containing sulfhydryl reagents (thiolysis) and on thin-layer chromatographic plates. In buffer solution and on thin-layer plates, N-S bond cleavage readily occurred to give carbofuran as a major product, with minor amounts of bis-carbofuran-N,N'-disulfide and -trisulfide. The hydrolysis reaction in buffer proceeded with first-order kinetics. Significant amounts of an unknown polar compound were obtained in buffer solution and on thin-layer plates. In the presence of excess cysteine and glutathione at pH 7.0, thiolytic N-S bond cleavage occurred with first-order kinetics to give carbofuran as the sole identifiable product. At pH 5.0, three minor products were obtained along with carbofuran.

Enhancement of cell separation by colchicine in cell suspension cultures of soybean.

When cell suspension of soybean was cultured in the presence of colchicine (1.0x10(-4) to 1.0x10(-3) M), the degree of cell separation was greatly increased. This promotion of cell separation was accompanied with swelling of cells and modification of cell form. The treated suspension consisted predominantly of single cells and a few small aggregates, and could be repeatedly subcultured in the presence of 1.0x10(-4) M colchicine, but could not at 1.0x10(-3) M.