Principles lec 7 2013

Incorporation shape of toxicant is similar enough to

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Unformatted text preview: 3. Incorporation shape of toxicant is similar enough to normal compound that its suppose to interact with a c hemical may act as a substitute for an endogenous compound / substrate and can be incorporated into the target e.g. - Fluoride (teeth/bone) - Selenium (cysteine residues impacts S-S bonds) Key component of proper protein folding - Pb2+ (bone) Result: Disrupts normal structure, physical characteristics (strength) or chemical characteristics (bonding interactions) Chemical / Target Interactions 10 4. Peroxidation: Free radicals can abstract electrons from target, rendering the target unstable. Or CYP-P450 the ability of a toxicant to produce reactive toxicant species i.e. lipid peroxidation - unsaturated fatty acids contain (many) double bonds INCREASE OXIDATIVE STRESS!! Consequences of chemical-target interactions 11 1. Destroy Target Irreversible - Lipid peroxidation of cell membranes E.g. paraquat (lungs) - Covalent binding of enzyme E.g. aflatoxin (liver) cell death or organ failure whatever affect we’ve created destroys the target Effect: loss of target function Consequences of chemical-target interactions 12 2. Alter Target Function Reversible - especially receptor interactions altered level of activity decrease or increase in activity - Decrease activity e.g. CN- inhibits e.t.c. function - Increase activity e.g. phytoestrogens stimulate estrogenic receptors - Loss of control e.g. cell regulatory protein expression altered in cancer decreases energy function in cells cells can recover from this just as damaging as decrease in activity more specifically in respect to cancer Toxicosis … the cellular response 13 1. Cellular degeneration: caused by an alteration in cells, which leads to abnormal function Sub-lethal injury such that removal of the stimulus results in recovery. (subclinical) Changes in the cell operations, ATP synthesis, Ca2+ regulation, protein synthesis, membrane fluid leak, cellular swelling or shrinkage function Results in Cell Swelling, lower energy output, loss of function (lower metabolism, No absorption in GI etc.) 2....
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This document was uploaded on 04/07/2014.

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