Determination of methomyl in human blood by LC/MS / 中国法医学杂志

Objective To develop a sensitive and simple LC/MS method for determination of methomyl in blood samples.Methods Methomyl was extracted from blood by liquid-liquid extraction with ethyl acetate, and then analyzed on a Zorbax SB-C18 (2.1mm×50mm, 5μm) column. The mobile phase consisted of acetonitrile-0.1% formic acid with gradient elution, at a lfow rate of 0.5 mL/min, at 40℃. LC-MS was performed in ESI source with MRM mode for quantiifcation.ResultsThe linear range of the concentration were 0.05~2.0μg/mL for methomyl (r>0.995). The relative recoveries of methomyl were in the range of 90%~108%. The RSDs of intra-days and inter-day were both less than 15%.Conclusion The method is a simple, quick, sensitive and could be used for determination of methomyl in blood samples.

A Case of Methomyl-induced Acute Allergic Tubulointerstitial Nephritis

Drug-induced interstitial nephritis is one of the causes of acute kidney injury. Although methomyl is widely used as an insecticide in many countries, methomyl-induced interstitial nephritis has not been reported thus far in the general population. We report a case of a 39-year-old male patient with acute allergic tubulointerstitial nephritis due to methomyl intoxication. He took methomyl 250 mL to commit suicide. He was treated with hemodialysis, but his renal function continued to deteriorate. Kidney biopsy demonstrated mononuclear cell and some eosinophils infiltration into the renal interstitium with tubular invasion. Immediate steroid pulse therapy, appropriate education, and conservative management resulted in gradual restoration of his renal function. This case suggests that methomyl may be a causative allergen inducing acute interstitial nephritis in some patients.

Protective Effect and its Mechanism of Hemoperfusion on Methomyl Poisoning Rabbit Myocardium / 中国药师

Objective:To observe the effect and its mechanism of hemoperfusion on injured myocardium under acute toxication of methomyl in rabbits. Methods:Twenty-four rabbits were randomly divided into three groups:control group ( N group) , acute metho-myl intoxication group ( P group) , hemoperfusion group ( HP group) . P group and HP group was treated by methomyl intoxication, and with 2-hour sham-hemoperfusion and hempoperfusion respectively. Then the pathological changes of myocardium were observed under optical microscope. The activity of SOD and content of MDA in myocardium were measured by colorimetry. The experimental data were analyzed by SPSS 16. 0 package. Results:There were congestion, edema and other pathological changes in group P, while no obvious changes in N group and HP group. The activity of SOD decreased while MDA content increased in P group versus N and HP group ( P< 0. 05). Conclusion:Hemoperfusion can alleviate the myocardial injury induced by methomyl poisoning through the mechanism of the resistance to oxidative damage.

An Outbreak of Food Borne Illness Due to Methomyl Pesticide Intoxication in Korea

On February 21, 2013, 6 elderly people collapsed abruptly after eating bean sprout bibimbab (boiled rice mixed with bean sprouts and seasoned with soybean sauce) at a countryside restaurant in the Chungbuk Province, Korea. Minutes after eating the meal, all of the patients lapsed into a state of stupor. Respiratory arrest developed in 2 patients; and one of two patients died of cardiac arrest. The autopsy identified methomyl and methanol in the deceased patient's gastric contents and in the remaining soybeanbean sauce seasoning. Five of the 6 patients ingested one spoonful of the soybeanbean sauce seasoning and survived, while one patient who died of cardiac arrest, ingested approximately two spoons. Symptoms of toxicity presented quickly in the subjects and progressed rapidly, including chest tightness, an unusual sensation in the pit of the stomach, dizziness, ataxia, and finally, collapse. Three patients who drank ethanol with the meal experienced only mild toxic symptoms. Our analysis of the clinical observations in these cases suggests that ingestion of methomyl pesticide and the additive toxicity of methanol may have been responsible for the intoxication.

Effect of methomyl formulation, a carbamate pesticide on ovarian follicular development and fertility in albino mice.

Administration of 5 mg methomyl (40%) kg-1 b.wt. mouse-1 (equal to 50% of LD50 dose), every day for 90 days to adult female mice resulted in a significant decrease in body weight, relative weight of the ovary, uterus and fallopian tube; mean number of small, preantral, antral and pre-ovulatory follicles and fertility compared to controls. On the other hand, total duration of the estrous cycle was significantly increased compared to controls. One month after the cessation of the treatment (a commercial methomyl preparation-lannate) the effect on estrous cycle and organ weight was not restored. Treatment of 2.5 mg or 1 mg lannate kg-1 b. wt., although did not alter duration of the estrous cycle; relative weight of the ovary, uterus, and fallopian tube and fertility, caused a significant decrease in mean number of small follicles compared to controls. All the groups of mice treated with lannate showed loss in body weight (15.15% in 1 mg, 6.61% in 2 mg and 12.16% in 5 mg treated groups) whereas controls showed a gain in body weight (20.02%) during the period of experimentation. The results indicate that 5 mg lannate kg-1 b. wt. causes loss of follicles and infertility, whereas lower dosages (2.5 and 1 mg) reduce the number of small follicles which might shorten reproductive life span of mice.

Degradation of methomyl by the novel bacterial strain Stenotrophomonas maltophilia M1 / Degradación del metomil por la nueva cepa bacteriana Stenotrophomonas maltophilia M1

The use of microorganisms in the degradation and detoxification of many toxic xenobiotics, especially pesticides, is an efficient tool for the decontamination of polluted sites in the environment. A novel bacterial strain (M1) was isolated from several water samples contaminated with methomyl which is capable of degrading methomyl pesticide (1000 ppm) in the presence of 0.05 percent glucose. These water samples were collected from different irrigation sites in Egypt where methomyl is heavily applied. The partial sequence of 16SrRNA gene of the isolate showed the highest similarity to Stenotrophomonas maltophilia. Restriction fragment patterns of isolated plasmid DNA showed that this strain harbours two different plasmids PMa (8Kb) and PMb (5Kb). PMb succeeded to be transferred to Escherichia coli DH5á strain. This transformed strain (M2) acquired the ability to grow in the presence of methomyl (1000 ppm) and 0.05 percent glucose. So it was deduced that the gene responsible for the degradation process was encoded by this plasmid. The ability of the two strains M1 and M2 to degrade methomyl was detected by using solid phased extraction coupled to capillary liquid chromatography-electrospray ionization-mass spectrometry (SPE-LC-ESI-MS).

Determination of methomyl in rat plasma by SPE-HPLC / 中国法医学杂志

Objective To establish a method of solid phase extraction-reversed-phase high performance liquid chromatography(SPE-HPLC)for determination of methomyl in plasma of rat.Methods The sample pretreatment method,the test conditions,the linear range,the sensitivity,the specificity,the precision, the accuracy,the stability and the recoveries for plasma were investigated by using rat plasma spiked with standard methomyl and intemal standard substance.Results The linear range was 0.1～20μg/mL ( r= 0.9993,P<0.001).The limit of detection was 0.03μg/mL(S/N ≥3).The intra and inter-day precision of assay for methomyl was less than 8.33%and 11.11%in plasma respectively.The intra and inter-day accuracy of assay for methomyl was between 90%and 120%in plasma respectively.The recoveries for methomyl were more than 88%±4.4%in plasma.Conclusion The HPLC method for quantitative and qualitative analysis of methomyl is simple,rapid and accurate,which is suitable for the identification of methomyl in the cases.

Analysis of methomyl and its metabolite in rat plasma by HPLC-MS / 医学研究生学报

Objective: No complete study has been reported on methomyl and its metabolite in rat plasma at home and abroad.This study aimed to detect methomyl and its metabolite in rat plasma by high performance liquid chromatography-mass spectrometry(HPLC-MS).Methods: Ten Wistar rats received intragastric administration of methomyl 50mg/kg,and then executed and kept at room temperature for 72 hours.After that,methomyl and its metabolite in the heart-blood of the rats were determined by solid phase extraction(SPE) and HPLC-MS.Results: Compared with the blank controls,methomyl and its metabolite were detected in the plasma of the experimental rats,and so were protonate ions and multistage fragment ions.Conclusion: The methomyl metabolite in the rat plasma was S-methyl-N-hydroxythioacetamidate.