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R W Stephany

Publications and source records attributed to R W Stephany.

49 records · Page 3Linked to original sources
PubMed1982

Weight increase of the thyroid gland as a tentative screening parameter to detect the illegal use of thyreostatic compounds in slaughter cattle.

A total of 45 normal or enlarged thyroid glands of adult slaughter cattle were weighed and analyzed by thin-layer chromatography for the presence of residues of the following thyreostatic compounds: thiouracil, methylthiouracil, propylthiouracil, phenylthiouracil, and methimazole. In 21 glands, mostly from imported animals, residues of methylthiouracil or methimazole were detected. These thyroids ranged in weight from 68-245 g (mean value 118 g). Glands in which no residues were found, varied in weight between 20 and 124 g (mean value 42 g). Taking an upper limit of 60 g as normal, 4 out of 22 were false-positive' with respect to the 5 thyreostatic compounds screened for, while no false-negative cases were scored. On the basis of these results the weight increase of the thyroid gland is proposed as a simple indirect parameter in the screening for the illegal use of thyreostatic compounds in slaughter cattle.

Animals↗
PubMed1981

[Toxicological aspects of the use of hormones as anabolic agents (author's transl)].

The use of anabolic agents may give rise to residues in foods of animal origin and thus to potential effects on public health. Therefore, the physiology, metabolism and toxicity of the three endogenous hormones. 17 beta-oestradiol, progesterone and testosterone are discussed. In addition, the effects of the use of three exogenous hormones, diethylstilboestrol (DES), trenbolone and zeranol are evaluated. As can be expected all six compounds have effects on the endocrine system and reproduction. Endogenous hormones and DES are teratogenic at high-dose levels. With the exception of DES, there is no evidence of a mutagenic action. 17 beta-Oestradiol and testosterone were shown to induce tumours at high-dose levels in experimental animals; probably however, a threshold can be established. The residues in edible tissue resulting from the use of endogenous hormones are much smaller than are the natural levels in cow's milk and butter. In view of the carcinogenicity of DES in man, its use should be strongly discouraged. A definite statement on the acceptability of the use of trenbolone and zeranol cannot be made.

Anabolic Agents↗
PubMed1981

The determination of propiopromazine in animal tissue.

A thin-layer chromatographic method for the determination of the veterinary tranquillizer propiopromazine (Combelen) in slaughter pigs is described. Propiopromazine residue depletion from the kidney occurs with different rates in sows and in castrated boars. In the liver residues increase over at least 24 h after intramuscular administration, in accordance with the distribution pattern of phenothiazine tranquilizers.

Animals↗
PubMed1980

Daily dietary intakes of nitrate, nitrite and volative N-nitrosamines in the Netherlands using the duplicate portion sampling technique.

In total, 201 duplicates of all foods and drinks sampled by adult volunteers during a 24-hour sampling period have been analyzed for nitrate, nitrite and volatile N-nitrosamines. For nitrate the mean daily intake was equivalent to 179 mg of potassium nitrate per 24 h, for nitrite this intake was equivalent to 4.2 mg of sodium nitrite per 24 h. The best estimate for the total daily fraction of salivary nitrite originating from dietary nitrate has been calculated as 6.3 mol%/24 h. For N-nitrosodimethylamine the mean daily intake was 0.38 microgram/24 h. The most important source of this nitrosamine contributing to the daily dietary intake was shown to be beer, which contributes 71% of the intake of an average consumer. Finally, attention has been drawn to the identification of N-nitroso-5-methyl-1,1-oxazolidine as an environmental nitrosamine present as an impurity in cutting fluids.

Beer↗
PubMed1978

The intake of nitrate, nitrite and volatile N-nitrosamines and the occurrence of volatile N-nitrosamines in human urine and veal calves.

A hundred samples of total diets, 19 samples of cheese (mainly Dutch), a total of 30 samples of muscle, fat liver, kidney, blood and fried meat from experimental veal calves (fed daily with 0.6 or 300 mg of potassium nitrate per kg b.w.) and 14 samples of urine of patients medicated with massive amounts of ammonium nitrate (up to an equivalent of 180 mg potassium nitrate per kg b.w.) have been analysed with GC-TEA for their content of the following N-nitrosamines: NDMA, NDEA, NDPA, NDBA, NPIP, NPYR and NMOR. NDMA was frequently found, but always in the sub micrograms per kg range, except for two diets (1.2 and 1.7 microgram/kg). Other N-nitrosamines were sporadically found in the same concentration range, except for one diet (NPYR, 1.9 microgram/kg). No correlation was found between NDMA content and the composition of diets or the nitrate load of patients or veal calves. Mean daily intake of NDMA, potassium nitrate and sodium nitrite from total diets was calculated to be 0.5 microgram, 215 mg and 7.7 mg respectively. N-nitrosamine recoveries from the various samples were determined mostly at the 1 microgram/kg level. Contents of potassium nitrate and sodium nitrite are reported for 124 samples of various vegetables, 94 samples of canned baby food and 48 samples of human saliva, collected at various times after the intake of meals. Some kinds of vegetables showed high to very high nitrate contents, for example, purslane, red beets, spinach and lettuce. Only traces of nitrite were found in the vegetables. Salivary nitrite content was shown to be highly dependent on the dietary intake of nitrate and increased up to 60 times its initial value after the consumption of vegetable-rich meals.

Adult↗
PubMed1976

Methods for controlling the application of anabolics in farm animals.

In the use of anabolic agents, the most pronounced effect on growth is caused by estrogens. For this reason primarily attention will be given to the methods of detection of estrogen administration to fattening animals. The detection methods can mainly be divided in histological, biological, chemical, and immunological determinations and these will be briefly discussed in the light of the present situation in many countries, where the use of anabolic agents is prohibited. From the point of view of control, this prohibition is much easier to handle than a situation in which the application of some specified products is permitted. The possibilities and limitations of control, when certain anabolic agents are permitted for use, will be discussed and evaluated. The conclusion is drawn that in this latter case a sufficient control is very difficult if at all possible considering the methods of control available at the time.

Anabolic Agents↗
PubMedDate not supplied

A chemiluminescent immunoassay for 17 alpha-methyltestosterone.

An immunoassay for the xenobiotic anabolic compound methyltestosterone (MT) is presented. The detection is based on chemiluminescence of a MT-isoluminol conjugate. Applications are presented for detection of methyltestosterone and cross-reacting compounds in bovine urine and tissues of application sites isolated from slaughtered cattle, illegally treated with hormonal anabolics.

Animals↗
PubMedDate not supplied

A highly specific detection method for diethylstilbestrol in bovine urine by radioimmunoassay following high performance liquid chromatography.

A specific radioimmunoassay (RIA) for diethylstilbestrol (DES) is presented following purification of sample extracts by isocratic reversed phase high performance liquid chromatography. Applications are given of a forensic investigation for the control of DES in bovine urine. Specificity of HPLC-RIA is compared with that of RIA's with other (chromatographic) purification procedures and with gas chromatography-mass spectrometry. Implications of the use of these techniques in practice and the use of various DES-antisera are discussed.

Animals↗