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Biomedical subjects

A W Neff

Publications and source records attributed to A W Neff.

42 records · Page 3Linked to original sources
PubMed1978

Microbiological method for assaying lincomycin in animal feed: collaborative study.

A microbiological assay for determining lincomycin in swine feed, supplement, and a vitamin-mineral premix was studied collaboratively in 16 laboratories. The design of the study involved a complete feed, feed supplement, and a vitamin-mineral premix covering a range of fortification from 20 to 80 g/ton and 80 to 2600 g/ton. Two methods of sample preparation were used depending on the concentration of lincomycin in the sample. Statistical evaluation of the results from the 2 methods indicated that 10 and 11 collaborators, respectively, had mean recoveries which were not significantly different from one another. Ten laboratories obtained a mean recovery of 112.2% (range 102.3--123.5%) for the lower level, and 11 laboratories obtained a mean recovery of 104.4% (range 100.0--107.7%) for the higher level. The method has been adopted as official first action.

Animal Feed↗
PubMed1977

Experiences in dealing with drug-related bound residues.

Although more than 90% of the radioactivity was excreted in the urine and feces within 10 days of oral treatment of sheep with a single dose of p [14C]toluoyl chloride phenylhydrazone (TCPH), persistent blood residues (5-6 ppm) were observed for at least 21 days. The 14C residues were largely localized in erythrocytes and covalently bound to both heme and globin. Only the phenyl group of the phenylhydrazine part of TCPH was present as 14C bound residues. An analytical procedure to measure the level of phenyl groups incorporated in heme, based on their oxidation to benzoic acid, was developed to monitor residues in treated animals. Relay metabolism in rats was studied by feeding sheep blood containing 14C residues form [14C]TCPH treatment. No retention of 14C residues in rat tissues was observed, which contrasted with the TCPH metabolism. A 90-day relay toxicity study in rats, which were fed dried blood from treated sheep containing up to 2,000 times the potential exposure to residues in the human diet, indicated no observable toxic responses. It is concluded that these data support a tolerance of 6 ppm TCPH equivalents in blood.

Animals↗
PubMed1976

Screening and confirmatory methods for determining lincomycin residues in animal tissues.

Methods for screening and for confirming residues of lincomycin in animal tissues, both sensitive to 0.1 ppm, are described. In the screening technique, residues are extracted, cleaned up by solvent partition, and detected by microbiological plate assay. In the confirmatory technique, residues are cleaned up on an unfunctionalized macroreticular-type resin column, concentrated, chromatographed on thin layer plates, and detected by bioautography. This system was effective in identifying lincomycin in the presence of 20 other antibiotics and chemicals used in the animal health industry.

Animals↗