Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: EC:3.1.1.8 (cholinesterase)
 12,691 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

In order to assess pollutant transfer in Camargue ponds from bordering agrosystems, a biomonitoring assay was conducted in irrigation and drainage channels of rice fields in the Rhone Delta (France). A filter-feeding bivalve, the Asian clam, Corbicula fluminea, was used as bioindicator and caged in upstream and downstream channels of an area of conventional rice fields. After 6 weeks incubation, many lipophilic biocides were identified in Corbicula tissues, including pesticides used in rice plantations (pretilachlor, oxadiazon), pesticides presumed in use in the Rhone basin [diuron and its metabolite 3,4 dichloroaniline (3,4-DCA)] and organochlorine pesticides (OCPs) banned for several decades. In addition, PCBs were highly bioaccumulated in Corbicula. Downstream bivalves had significantly lower concentrations of OCPs, PCB and 3,4-DCA. However, the exposure biomarkers (glutathione S-transferase, catalase and propionylcholinesterase) were not correlated with the decreased concentrations. The results of this experiment raise several questions concerning the potential role of immersed plants in a retention process.
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PMID:Rice fields regulate organochlorine pesticides and PCBs in lagoons of the Nature Reserve of Camargue. 1915 94

Mechanistic studies with simple mixtures have provided insights into the nature of interactions among chemicals that lead to non-additive effects and have elucidated the exposure conditions under which interactions are likely to occur. This paper discusses studies on four mixtures: (1) 1,1-dichloroethylene and trichloroethylene, (2) carbon tetrachloride and Kepone, (3) hexane and methyl-n-butylketone, and (4) coplanar and non-coplanar polychlorinated biphenyls. These mechanistic studies show that interactions should be described at the level of target tissue dose and are best categorized as either pharmacokinetic (PK) or pharmacodynamic (PD) interactions. In PK interactions the presence of a second chemical alters the kinetics such that a unit of administered dose no longer produces a unit of dose at the target tissue. In PD interactions, the presence of other compounds alters the PDs such that a unit tissue dose no longer produces a unit of response. Physiologically based pharmacokinetic (PBPK) models for mixtures have become important tools for predicting conditions under which interactions are likely to alter the assumption of additivity and have permitted calculation of interaction thresholds with more confidence. New cumulative risk assessment approaches have provided opportunities to classify compounds on the basis of similar chemistry-based modes of action (cholinesterase inhibitors) or similar physiological modes of action (diverse chemicals that alter a common biological outcome, such as defeminization of the developing nervous system). The latter examples present challenges for expanding our risk assessment paradigm to focus on the biology of responses more than on the kinetics of the xenobiotics. Some of the future advances in mixture research will depend on progress in systems biology, a discipline that integrates information across multiple level of biological organization producing PD models of normal function and assessing conditions under which exposures to chemicals lead to the perturbations sufficiently great to produce toxicity and disease. We describe briefly the elements of a systems biology approach for assessing the interactions between various PCB congeners.
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PMID:Mechanistic approaches for mixture risk assessments-present capabilities with simple mixtures and future directions. 2178 89