SummarySilicone rubber poppets, apparently without exception, will absorb lipid from the blood stream. I n most cases, absorption is quite low and confined to simple lipids like cholesterol and cholesterol esters. A small percentage, however, absorb an unknown material in quantities sufficient to render them variant. This material appears to be an oxidation product of polyunsaturated fatty acids formed after their absorption into the poppet by the action of molecular oxygen. I n vitro experiments supporting the in vivo findings are described.
Sulfamethazine prolonged release bolus was orally administered to calves in a single therapeutic dose of 225 mg per lb of body weight. Sulfamethazine residues in edible tissues were measured. The average biological half-life of the drug in various tissues fell within a narrow range of 0.87 to 1.05 days. Tissue residues in muscle, fat, liver, and kidney fell to control levels by 16 days. Data are presented which validate the method used in the range of 100-10000 ppb. Tissue residue levels are not adversely affected if the tissues are frozen for up to 40 days prior to analysis.
The fatty acid composition of the seed fat of Taraktogenos kurzii has been investigated by carrying out the preliminary resolution of the mixed fatty acids into 13 fractions by low-temperature crystallisation followed by urea adduction and by subsequent identification of the component acids of each fraction by paper chromatography. The presence and the quantity of linoleic acid has been established by ultra-violet spectrophotometry. The composition of the mixed fatty acids as established in the present work consists of chaulmoogric 21.0% ; hydnocarpic 19.6% ; palmitic 5.8% ; myristic 5'9% ; gorlic 26.6% ; oleic I 1.3% and linoleic 4.4%. A gel-like substance of unestablished composition amounting to 5.4%. probably a mixture of partially polymerised/oxidised unsaturated acid was also obtained. The results agree with those of earlier workers for the percentages of chaulmoogric, gorlic, oleic and palmitic acids concerned, but not of hydnocarpic acid. The presence of linoleic and myristic acids in this seed fat has been established for the first time.
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