Organophosphate compound

Agarwal SB A clinical, biochemical, neurobehavioral, and sociopsychological study of 190 patients admitted to hospital as a result of acute organophosphorus poisoning, in Neurobehavioral Methods and Effects in Occupational and Environmental Health. Edited by Araki S. San Diego, CA, Academic Press, 1994, pp 787- 

Aldous JC, Ellam GA, Murray V, et al An outbreak of illness among schoolchildren in London toxic poisoning not mass hysteria. J Epidemiol Community Health 48 41-45, 1994 

Ames RG, Steenland K, Jenkins B, et al Chronic neurologic sequelae to cholinesterase inhibition among agricultural pesticide applicators. Arch Environ Health 50 440-444, 1995 

Allam M, Osmaan AL, et al Neurobehavioral changes among workers in some chemical industries in Egypt. Environ Res 63 295-300,1993 Azaroff LS, Neas LM Acute health effects associated with nonoccupational pesticide exposure in rural El Salvador. Environ Res 80 158-164,1999 Barr AM Further experience in the treatment of severe organic phosphate poisoning. Med J Aust 1 490-492,1966 

Bazylewicz-Walczak B, Majczakowa W, Szymczak M Behavioral effects of occupational exposure to organophosphorous pesticides in female greenhouse planting workers. Neurotoxicology 20 819-826,1999 Beilin JS, Chow I Biochemical effects of chronic low-level exposure to pesticides. Research Communications in Chemical Pathology and Pharmacology 9 325-337, 1974 

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Phospholipid Biosynthesis Inhibitors. The organophosphate compounds ediphenphos [17109-49-8] (83) and iprobenphos [26087-47-8]... 

There is a second type of cholinesterase called butyrylcholinesterase, pseudocholinesterase, or cholinesterase. This enzyme is present in some nonneural cells in the central and peripheral nervous systems as well as in plasma and serum, the liver, and other organs. Its physiologic function is not known, but is hypothesized to be the hydrolysis of esters ingested from plants (Lefkowitz et al. 1996). Plasma cholinesterases are also inhibited by organophosphate compounds through irreversible binding this binding can act as a detoxification mechanism as it affords some protection to acetylcholinesterase in the nervous system (Parkinson 1996 Taylor 1996). 

Zhao IS, Wang B, Dai ZX, Wang XD, Kong LR, Wang LS. 3D-quantitative structure-activity relationship stndy of organophosphate compounds. Chinese Sci Bull 2004 49 240-5. 

Previously, we have shown that functional secretion of OPH molecules into the periplasmic space induced about 2.8-fold higher specific whole cell OPH activity [10]. From the detail reaction kinetic studies in this work, we showed that this periplasmic space-secretion strategy provided much improved bioconversion capability and efficiency ( 1.8-fold) for Paraoxon as a model organophosphate compound. From these results, we confirmed that Tat-driven periplasmic secretion of OPH can be successfully employed to develop a whole cell biocatalysis system with notable enhanced bioconversion efficiency and capability for environmental toxic organophosphates. 

Diisopropyl methylphosphonate is an organophosphate compound that was first produced in the United States as a by-product of the manufacture of the nerve gas isopropyl methylphosphonofluoridate (GB, or Sarin) (ATSDR 1996 EPA 1989 Robson 1977, 1981). It is not a nerve gas and is not a metabolite or degradation product (Roberts et al. 1995). Diisopropyl methylphosphonate constitutes approximately 2-3% of the crude GB product, but it is neither a metabolite nor a degradation product of GB (EPA 1989 Rosenblatt et al. 1975b). Diisopropyl methylphosphonate is not normally produced except for its use in research. One method of producing diisopropyl methylphosphonate is to combine triisopropyl phosphite and methyl iodide. The mixture is then boiled, refluxed, and distilled, yielding diisopropyl methylphosphonate and isopropyl iodide (Ford-Moore and Perry 1951). Diisopropyl methylphosphonate may also be prepared from sodium isopropyl methylphosphonate by a reaction at 270° C, but a portion of the resulting diisopropyl methylphosphonate is converted to trimethylphosphine oxide at this temperature (EPA 1989). 

Six different individual data matrices were obtained for GW (gwi, gw2,..., gw6) but, in this case, rows (samples) were not common for all data matrices. A new GW data matrix was obtained after individual matrix concatenation containing 92 samples in total (see Fig. 7). In this case, the number of samples for the different sampling campaigns was not coincident (10, 16, 17, 15, 17, and 17 locations were sampled, from first to sixth campaigns respectively). Seven variables (all of them detected in SW as well) were measured in every GW sample an organophosphate compound (tributylphosphate), triazines (atrazine, desethylatrazine, simazine, and terbuthylazine), and APs (octylphenol and nonylphenol). 

Finally, three additional individual data matrices were obtained for soil (so1 so2, and so3), in this case with the same number of samples (rows) for each of them. A new soil data matrix (SO) was obtained after individual matrix concatenation containing 36 samples in total (12 samples analyzed in 3 sampling campaigns) (see Fig. 7). Fifteen variables (all of them detected in SE as well) were measured in every sample PAHs (acenaphtylene, phenanthrene, anthracene, fluoranthene, pyrene, benzo(a)anthracene, chrysene, benzo(b)fluoranthene, benzo(a)pyrene, indeno (l,2,3-cd)pyrene, dibenzo(a,h)anthracene, and benzo(g,h,i)perylene), an organophosphate compound (tributylphosphate), and an OC (4,4 -DDE). 

Supercritical extractions such as that illustrated in Procedure 12.3 have been used to extract phenols, organochlorine, organophosphate compounds, and amines from soil [9,10,12],... 

Garcia M, Rodriguez I, Cela R (2007) Optimisation of a matrix solid-phase dispersion method for the determination of organophosphate compounds in dust samples. Anal Chim Acta 590 17-25... 

It accounts for the greater span between symptom-producing and lethal doses than most organophosphate compounds. 

Crop protection chemicals are an important group of contaminants that exhibit biologically mediated transformation in aerobic or anaerobic subsurface environments. We consider two well-known contaminants the insecticide parathion, which is an organophosphate compound, and the herbicide atrazine, from the triazine group. 

Poisoning by pesticides that contain organophosphate compounds produces a variety of symptoms, including nausea, blurred vision, fatigue, muscle weakness and, potentially, death caused by paralysis of respiratory muscles. 

The organophosphate compounds also react at the es-teratic site of AChE (Fig. 12.4). In general, however, they are much less selective than are the carbamates, inhibiting many enzymes that contain a serine molecule at an active center. The organophosphate compounds have this general structure ... 

Metrifonate (9.121), an organophosphate compound, is a low-cost antihelminthic used to treat Schistosoma hematobium infections. The drug appears to alter cholinesterase activity in the nematode, temporarily paralysing the adult worm and causing the worm to die. Because of its activity against the cholinesterase enzyme, this drug has also been evaluated as a treatment for Alzheimer s disease. 

Metrifonate, an organophosphate compound, is rapidly absorbed after oral administration. After the standard oral dose, peak blood levels are reached in 1-2 hours the half-life is about 1.5 hours. Clearance appears to be through nonenzymatic transformation to dichlorvos, its active metabolite. Metrifonate and dichlorvos are well distributed to the tissues and are completely eliminated in 24-48 hours. 

Functional interactions are those in which both of the two chemicals affect a bodily system perhaps by different mechanisms, and either increase or decrease the combined effect. For example, both atropine and pralidoxime decrease the toxic effects of organophosphate compounds by different means, a combination of the two antidotes leads to a large increase in effectiveness synergism). 

Chronic exposure to certain organophosphate compounds, including some organophosphate cholinesterase inhibitors, causes neuropathy associated with demyelination of axons. 

Metrifonate, an organophosphate compound, is rapidly absorbed after oral administration. 

Acetylcholine is a neurotransmitter, a key substance involved with transmission of nerve impulses in the brain, skeletal muscles, and other areas where nerve impulses occur. An essential step in the proper function of any nerve impulse is its cessation (see Figure 6.9), which requires hydrolysis of acetylcholine as shown by Reaction 6.10.1. Some xenobiotics, such as organophosphate compounds (see Chapter 18) and carbamates (see Chapter 15) inhibit acetylcholinesterase, with the result that acetylcholine accumulates and nerves are overstimulated. Adverse effects may occur in the central nervous system, in the autonomic nervous system, and at neuromuscular junctions. Convulsions, paralysis, and finally death may result. 

What is done to organophosphate compounds containing the P=0 group to increase their insect mammal toxicity ratios and decrease their tendency to undergo nonenzymatic hydrolysis ... 

Tetraethylpyrophosphate (TEPP) was the first organophosphate compound to be used as an insecticide. This compound was developed in Germany during World War II and was substituted for nicotine as an insecticide. It is a white to amber hygroscopic liquid (bp, 155°C) that readily hydrolyzes in contact with water. Because of its tendency to hydrolyze and its extremely high toxicity to mammals, TEPP was used for only a very short time as an insecticide, although it is a very effective one. It was typically applied as an insecticidal dust formulation containing 1% TEPP. 

An example of irreversible binding is that of paraoxon, which can be viewed as an organophosphate compound containing a phosphorylating group (P) and a leaving group (L), as shown below ... 

This review is mainly devoted to summarize the results of the theoretical studies of organophosphates interacting with catalytic surfaces (transition metal and metal oxide). Therefore, we need to mention that to the best of our knowledge, there were published only a few theoretical works addressing this problem. Some theoretical studies of the interactions of organophosphate compounds with clay minerals and magnesium oxide were also published. 

A number of synthetic organophosphate compounds have the capacity to bind covalently to acetylcholinesterase. The result is a long lasting increase in acetylcholine at all sites where it is released. Many of these drugs are extremely toxic and were developed by the military as nerve agents. Related compounds such as parathion are employed as insecticides. 

The inhibition by other organophosphate compounds of the carboxylesterase which hydrolyzes malathion is a further example of xenobiotic interaction resulting from irreversible inhibition because, in this case, the enzyme is phosphorylated by the inhibitor. A second type of inhibition involving organophosphorus insecticides involves those containing the P=S moiety. During CYP activation to the esterase-inhibiting oxon, reactive sulfur is released that inhibits CYP isoforms by an irreversible interaction with the heme iron. As a result, these chemicals are inhibitors of the metabolism of other xenobiotics, such as carbaryl and fipronil, and are potent inhibitors of the metabolism of steroid hormones such as testosterone and estradiol. 

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