Disease relevance of MONITOR

• The selective toxicity of acephate is considered to be due to facile conversion to methamidophos in insects but not mammals [1].
• Food poisoning due to methamidophos-contaminated vegetables [2].
• Methamidophos (O,S-dimethyl phosphorothioamidate) causes polyneuropathy in man and hens [3].
• Study subjects were stratified into three groups: 1) never poisoned; 2) poisoned with organophosphates other than methamidophos, agents which have not been reported to cause peripheral neuropathy; and 3) poisoned with methamidophos, a peripheral neurotoxin [4].
• Thresholds of the big toes of men with severe intentional poisonings due to neuropathic OPs (metamidophos and chlorpyrifos) increased between the first and second examinations [5].

Psychiatry related information on MONITOR

• Children's PTSD reactions one year after a sniper attack at their school [6].
• Acute stress disorder, alcohol use, and perception of safety among hospital staff after the sniper attacks [7].
• The sniper and the public's mental health [8].

High impact information on MONITOR

• Inhibition of acetylcholinesterase with methamidophos also enhanced transmission, demonstrating a similar effect of endogenous acetylcholine. nAChR activation also enhanced transmission by dorsal root entry zone stimulation, suggesting that alpha7 nAChRs on the central terminals of DRG afferents mediate this effect [9].
• Here we describe experiments which allowed to resolve some of the less well understood reaction pathways of phosphylation and "aging" of acetylcholinesterase (AChE) involving phosphoroamidates (P-N agents) such as tabun or the widely used pesticide methamidophos [10].
• Reactions of the N- and O-methyl derivatives of MeO(MeS)P(O)NHOH and (MeO)2P(O)NHOH are consistent with proposed mechanisms A and B. N-Hydroxymethamidophos is less potent than methamidophos as an AChE inhibitor and toxicant possibly associated with its rapid hydrolysis [11].
• We show in the present investigation that a carboxyamidase activates acephate in mice and in turn undergoes inhibition by the hydrolysis product, i.e., methamidophos; thus, the bioactivation is started but immediately turned off [1].
• The bone marrow transplantation survivors demonstrated more denial and avoidance and fewer arousal symptoms than has been noted in children traumatized by a violent life threat, such as a sniper attack [12].

Chemical compound and disease context of MONITOR

• Single and binary-combined toxicity of methamidophos, acetochlor and copper acting on earthworms Esisenia foelide [13].
• The Fort Bragg Sniper Attack and Mental Health Response [14].

Biological context of MONITOR

• For methamidophos, we show that phosphylation of AChE involves elimination of the thiomethyl moiety and that the spontaneous reactivation of the resulting organophosphate adduct generates the phosphorus free AChE active site Ser-peptide [10].
• The rate of phosphorylation of insect and rat AChE was similar in the presence of methamidophos [15].
• The inhibition potency [as measured by Ki and the concentration required to cause 50% inhibition in AChE or ChE activity (IC50 values)] of methamidophos, but not of acephate, increased by lengthening the enzyme-inhibitor incubation time [16].
• An extensive QSAR study may help in determining the mode of action of Met in vivo and in vitro and provide a rational for its high insecticidal toxicity [17].
• The calculated, acute oral LD50 of acephate and methamidophos to dark-eyed juncos (Junco hyemalis) was 106 mg/kg and 8 mg/kg, respectively [18].

Anatomical context of MONITOR

• Methamidophos transiently inhibits neuronal nicotinic receptors of rat substantia nigra dopaminergic neurons via open channel block [19].
• Preimplantation embryos that were conceived 6 weeks after paternal methamidophos exposure (5 mg kg(-1) body wt) exhibited a significant increase in cleavage arrest [20].
• In this study, the mouse was used to evaluate paternal germline exposure to the organophosphate methamidophos for its potential to produce adverse effects on spermatozoa and in the offspring [20].
• Males were euthanized 4 weeks after an acute intraperitoneal injection of methamidophos (0.5, 3.75, 5.0, and 7.5 mg kg(-1) body wt) and the number of spermatids per gram testes and sperm morphology were analyzed [20].
• Inhibition of human erythrocyte and plasma cholinesterases by methamidophos [21].

Associations of MONITOR with other chemical compounds

• Aldicarb-induced ChE inhibition was readily reversible in all age groups, whereas with methamidophos, enzyme activity recovered more rapidly in the young [22].
• The neuropathy-target-esterase (NTE) inhibition data were either obtained from the literature for a number of OP compounds or were determined experimentally for methamidophos, acephate, coumaphos and EPN [23].
• RESULTS: Metamidophos- and isofenphos-treated animals showed the highest percentage of necrotic muscle fibers: 1.66 +/- 1.112 and 1.34 +/- 0.320, respectively [24].
• DESIGN: Adult male Wistar rats were given oral organophosphate compounds dissolved in glycerol formal: dichlorvos, isofenphos, metamidophos, and diazinon [24].
• Whereas benzyl-P2A is somewhat less active than P2S for reactivation of ACHE inhibited by methamidophos, it is superior to P2S for reactivation of ACHE inhibited by crufomate and also superior to P2S and to the bispyridinium oximes for AChE inhibited by tabun [25].

Gene context of MONITOR

• In addition, the CFU (colony-forming unit) numbers of methamidophos metabolized bacteria in CS2 and CS3 also increased significantly by 86.1% and 188.9% compared with that of CS1 [26].
• In vitro and in vivo assessment of the effect of impurities and chirality on methamidophos-induced neuropathy target esterase aging [27].
• Moreover, the levels of NTE inhibited by methamidophos which can be promoted to neuropathy are lower than those required for classic protective chemicals and higher than those of classic neuropathic OPs [28].
• Genetically modified acetylcholinesterase (AChE) from Drosophila melanogaster (dm) and from commercial sources, Electric eel (ee), Bovine erythrocites (be) and Human erythrocites (he), were investigated as biological receptors for the detection of methamidophos pesticide based on inhibition studies [29].
• Most engineered variant of AChE from dm showed enhanced sensitivity toward methamidophos pesticide [29].

Analytical, diagnostic and therapeutic context of MONITOR

• The diminution of metamidophos residue levels with time in vegetables an greenhouse air was investigated after treatment of tomatoes and green beans [30].
• Levels of metamidophos in air and vegetables after greenhouse applications by gas chromatography [30].
• In conclusion, administration of low doses of methamidophos to female and male Wistar rats for 16 weeks during early adulthood did not impair spatial working and reference memory in the Morris water escape task 33 and 55 weeks after cessation of treatment [31].
• Adding a fourth sensor (neuronal microelectrode array) to the test battery allowed detection of two additional chemicals (aldicarb and methamidophos), but the neuronal microelectrode array was overly sensitive to paraquat [32].
• Comparative investigation between acetylcholinesterase obtained from commercial sources and genetically modified Drosophila melanogaster: application in amperometric biosensors for methamidophos pesticide detection [29].

References