Serum mammals

FIGU RE 2.10 Plasma A-esterase activities of birds and mammals. Activities were originally measured as nanomoles product per milliliter of serum per minute, but they have been converted to relative activities (male rat = 1) and plotted on a log scale. Each point represents a mean value for a single species. Substrates , paraoxon , pirimiphos-methyl oxon. Vertical hues indicate limits of detection, and all points plotted to the left of them are for species in which no activity was detected. (Activities in the male rat were 61 4 and 2020 130 for paraoxon and pirimiphos-methyl oxon, respectively.) (From Walker 1994a in Hodgson and Levi 1994.)... 

Serum Albumin is the most abundant plasma protein in humans (and other mammals) with a concentration of about 600 p,M in healthy humans. Around 80-90% of the extracellular gold in the circulation is bound to albumin and about... 

Uric acid A by-product of purine metabolism in mammals, including humans. A high serum uric acid concentration is a major risk factor for gout. 

In mammals, phenobarbital and phenytoin increase serum ceruloplasmin concentrations (Aaseth and Norseth 1986). Chronic copper poisoning in sheep is exacerbated when diets contain heliotrope plants (Heliotropium sp., Echium spp., Senecio sp.). Aggravated effects of the heliotrope plants include reduced survival and a twofold to threefold increase in liver and kidney copper concentrations when compared to control animals fed copper without heliotropes (Howell et al. 1991). Rats given acutely toxic doses of 2,3,7,8-tetrachlorodibenzo-para-dioxin had elevated concentrations of copper in liver and kidney because of impaired biliary excretion of copper (Elsenhans et al. 1991). Morphine increases copper concentrations in the central nervous system of rats, and dithiocarbam-ates inhibit biliary excretion (Aaseth and Norseth 1986). In human patients, urinary excretion of copper is increased after treatment with D-penicillamine, calcium disodium EDTA, or calcium trisodium diethylenetriamine penta acetic acid (Flora 1991). 

Nickel retention in the body of mammals is low. The half-time residence of soluble forms of nickel is several days, with little evidence for tissue accumulation except in the lung (USEPA 1980, 1986). Radionickel-63 (63Ni) injected into rats and rabbits cleared rapidly most (75%) of the injected dose was excreted within 24 to 72 h (USEPA 1980). Nickel clears at different rates from various tissues. In mammals, clearance was fastest from serum, followed by kidney, muscle, stomach, and uterus relatively slow clearance was evident in skin, brain, and especially lung (Kasprzak 1987). The half-time persistence in human lung for insoluble forms of nickel is 330 days (Sevin 1980). 

Chlordane is readily absorbed by warm-blooded animals through skin, diet, and inhalation. It is quickly distributed in the body and tends to concentrate in liver and fat (WHO 1984). Up to 75% of a single oral dose of chlordane administered to rats and mice was absorbed in the gut, and up to 76% of an aerosol dose was absorbed in the respiratory tract (Nomeir and Hajjar 1987). Rabbits absorbed 33% in the gut following oral administration (USEPA 1988). Chlordane residues in mammals were usually not measurable 4 to 8 weeks after cessation of exposure (Ingle 1965). Chlordane persistence in human serum and whole body was estimated at 88 days and 21 days, respectively this compares to a Tb 1/2 of about 23 days in rats fed chlordane for 56 days (USEPA 1980). 

In chemical-specific parameters used for PBPK modeling, the metabolic rate constant is crucial to the accuracy of modeling results in many cases. For some pyrethroids, hydrolysis in intestine and serum has a significant role in the metabolism of the compound in mammals besides oxidation and ester cleavage in liver, which is the most important organ for detoxification of many chemicals. 

The Serum Proteins of the Fetus and Young of Some Mammals R. A. Kekwick... 

The fatty acids could be carried by proteins by a process similar to the way in which serum albumin binds fatty acid in the bloodstream of mammals. Other types of lipid might be formed into complexes analogous to low-density lipoproteins of the type found in animal tissues, where the lipid core of the lipoprotein is surrounded by a hydrophilic cortex made up of protein, phospholipid, and cholesterol (87). This allows the lipid to be moved in an aqueous environment. The protein of the lipoprotein shell could also act as possible ligands for particular receptors at the membrane of the cell at which the export occurs. The lipoproteins, if they are present, would probably be formed within the endomembrane lumen and would receive the proteins at the endoplasmic reticulum. 

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