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R W Stephany

Publications and source records attributed to R W Stephany.

At least 37 records · Page 2Linked to original sources
PubMed1988

Assay for trenbolone and its metabolite 17 alpha-trenbolone in bovine urine based on immunoaffinity chromatographic clean-up and off-line high-performance liquid chromatography-thin-layer chromatography.

An high-performance liquid chromatography (HPLC)-thin-layer chromatography (TLC) method was developed to detect the illegal use of the xenobiotic growth promotor Trenbolone acetate (TBA). Very effective clean-up of bovine urine was achieved by immunoaffinity chromatography (IAC). The active form of TBA, the steroid 17 beta-Trenbolone (17 beta-TB), as well as its major metabolite 17 alpha-Trenbolone (17 alpha-TB), were assayed simultaneously with HPLC and on-line UV detection. The fraction containing 17 alpha-TB and 17 beta-TB (TB-fraction) was collected, and for confirmation 17 beta- and 17 alpha-TB were subsequently separated and identified by TLC. The limit of detection by on-line HPLC-UV (350 nm) was 1-2 micrograms TB/l. Off-line TLC detection was even more sensitive, 0.5 microgram 17 beta- or 17 alpha-TB/1. The assay was validated by investigating urine samples from veal calves implanted with TBA. The presence of 17 beta- and 17 alpha-TB was clearly demonstrated. A survey of the illegal use of TBA in cattle was performed by applying the assay to urine obtained at slaughter. No residues of TBA or its metabolites were found in any of the 144 random samples from the Dutch public health surveillance programme.

Animals↗
PubMed1986

Quantitative determination of diethylstilboestrol in bovine urine with isotope dilution mass spectrometry.

A method has been described for the quantification of diethylstilboestrol (DES) in bovine urine. The determining step is based on isotope dilution mass spectrometry (IDMS). The chemical work-up consisted of enzymatic deconjugation, Sep-Pak clean-up and high-performance liquid chromatography (HPLC). The labelled compound synthesized for IDMS is hexadeutero DES (DES-2H6). The labelled compound is not only used to quantify DES, but also to check the recovery of the chemical work-up procedure, in order to avoid false negative results. At the 1-5 micrograms l-1 level of urinary DES, the average recovery of 2 micrograms l-1 DES-2H6 is 70 +/- 20% (s.d.).

Animals↗
PubMed1986

A chemiluminescent immunoassay for zeranol and its metabolites.

A sensitive immunoassay is presented for the detection of the xenobiotic oestrogenic growth promotor zeranol (Ralgro) and the mycotoxin zearalanone. The detection is based on chemiluminescence using a zeranol-isoluminol conjugate. A lowest detectable amount of 2-5 pg zeranol per tube was achieved. The bovine zeranol metabolites zearalanone and taleranol can also be determined, and this has been shown in a metabolic pilot study of zeranol in veal calves. This study indicates that taleranol is a major metabolite in male veal calves, in contrast to zearalanone which is known to be the major metabolite in adult cattle.

Animals↗
PubMed1985

[A quarter of a century of studies of the abuse of hormonal anabolics in slaughtering animals: no DES-illusion!].

Over twenty-five years of analytical chemical and analytical biological forensic examination for residues of anabolic agents are reviewed. Up to 1981, this review is not only representative of the research done at the National Institute of Public Health but also of any research in this field in The Netherlands. A more detailed background is presented of the situation and the model of investigation adopted in the analytical-chemical testing of bovine urine for diethylstilbestrol (DES) following legal verdicts in 1981. At the time, examination in accordance with the Meat Regulations as well as a particular method of analysis were condemned. A retrospective study showed the rejected radioimmunochemical method (RIA) to be reliable as regards false-positive results at a level of 2 micrograms or more of DES per litre of urine (2 parts per billion or 2 ppb) rather than the level of 1 ppb adopted in 1981. Extensive and large-scale screening for DES from 1984 up to the present day resulted in the almost complete disappearance of the illegal use of this anabolic compounds in the Netherlands. However, investigations of sites of injection detected in slaughtered cattle during the period from 1983 to 1984, showed that other anabolics were still being used illegally. These studies particularly revealed residues of combined anabolic compounds ('cocktails'). The most common active anabolic ingredients observed were the xenobiotic steroids nortestosterone (nandrolone) and medroxyprogesterone and the exogenous natural steroids oestradiol and testosterone.

Anabolic Agents↗
PubMed1985

[Anabolic steroid residues in administration sites in slaughtering cattle. October 1983 - January 1985].

Samples from 573 sites of injection or implantation in carcasses of slaughtered cattle and veal calves in the Netherlands were studied by high performance liquid chromatography associated with on-line detection of the total UV spectrum (diode array detector). Anabolic substances were identified in 462 (100%) out of 573 samples. Nortestosterone was most frequently detected (84%) during the period from October 1983 to January 1985. Other xenobiotic steroids observed were medroxyprogesterone (14%), methyltestosterone (2%) and trenbolone (2%). The 'natural' steroids testosterone, oestradiol and progesterone were found in 29%, 66% and 3% of the samples respectively. The stilbene derivatives diethylstilboestrol (DES), dienestrol and hexoestrol were found in 2%, 3% and 0% of the samples. After re-introduction of DES control in the urine of cattle early in 1984, DES residues were no longer detected in the samples from sites of administration. Zeranol was not observed at all. If applicable, all anabolic agents were found to be present in a variety of esterified dosage forms.

Anabolic Agents↗
PubMed1985

Effective control for diethylstilbestrol in cattle in the Netherlands.

In the period from August 1981 to April 1983, 10243 random samples of urine from slaughtered cattle were inspected for the presence of the stilbene derivatives diethylstilbestrol (DES), dienestrol (DE), and hexestrol (HEX). Fast screening of all samples was performed by radioimmunoassay (RIA) with prior clean-up column chromatography. In this screening, 216 samples were indicated for confirmatory analyses by combined high performance liquid chromatography-gas chromatography-mass spectrometry (HPLC-GCMS) on account of an immunochemical response equivalent to 1 microgram/1 DES or more. The presence of DES was confirmed in 184 samples, DE in 5 samples and HEX in 14 samples. In the remaining 13 samples no stilbene derivative could be confirmed. From the results in 1984, after the introduction of the Meat Inspection Act, it is concluded that the use of stilbene derivatives in cattle in the Netherlands has dropped almost to zero. Of 4558 samples investigated, only 6 (0.13%) were indicated as 'stilbene' positive. The presence of DES was confirmed in 2 samples and DE in 4 samples.

Animals↗
PubMed1985

A specific radioimmunoassay for the detection of 19-nortestosterone in urine.

The antisera used were raised in rabbits against a 19-nortestosterone-7 alpha-carboxyethylthioether conjugate of bovine serum albumin. Tritium-labeled nortestosterone was used as tracer. Cross reactivities with metabolites of nandrolone, other anabolics and endogenous steroids were very low. To achieve additional specificity a clean up and separation procedure was developed, using isocratic high performance liquid chromatography. So far no qualitative discrepancies have been observed between the assay described here and confirmative determinations by combined high performance liquid chromatography-gas chromatography-mass spectrometry.

Animals↗
PubMed1984

[Diethylstilbestrol in urine of slaughtered cattle].

The results of an investigation during 1981-1984 for the presence of diethylstilbestrol (DES) in 12576 samples of bovine urine in the Netherlands are presented. The screening was performed by radioimmunochemical detection after chromatographic purification on celite. Subsequent final confirmation was performed by combined high pressure liquid chromatography-gas chromatography mass spectrometry. On the average in 1.7% of the 12576 samples the presence of stilbenes , primarily DES, was proven. Probably due to the reintroduction of the meat inspection act regarding the control for DES, a substantial decrease to 0.2% (4 samples) was observed in the first three months of 1984. In these 4 samples out of 2333 samples the presence of dienestrol (DE) was confirmed. No DES or hexestrol (HEX) could be detected.

Animals↗
PubMed1984

Identification of several stilbene derivatives in bovine urine by means of high performance liquid chromatographic fractionation and immunochemical detection.

Radioimmunochemical detection (RIA) following fractionation of urine extracts via high performance liquid chromatography (HPLC) turned out to be a very specific method for the identification of stilbene derivatives in bovine urine. Combination of the high resolution of the HPLC with a specific RIA is a suitable method to discriminate between the presence of different stilbene derivatives like diethylstilboestrol (DES), dienoestrol (DE) and hexoestrol (HEX) or other unknown compounds interfering in the celite-RIA used in the screening. Using this screening method 8200 samples of bovine urine were investigated on the presence of stilbene derivatives of which 133 were classified as 'positive'. In 106 'positive' urines the presence of DES was shown and in 19 'positive' urines the presence of DE or HEX, using the method described in this report whereas in 8 'positive' urines an unknown immunochemical active compound was detected. During 1.5 year of comparative investigation no qualitative discrepancies occurred between the results of the HPLC-immunogram procedure and the final confirmation by high resolution gas chromatography-mass spectometry (GCMS).

Animals↗
PubMed1984

Monitoring and identification of residues of anabolic preparations in slaughtered cattle by HPLC with diode array detection.

The new combination of isocratic high performance liquid chromatography (HPLC) with on line UV spectrum detection via a diode array configuration has been applied to the detection and identification of anabolics present in application sites of cattle. Combination of the characteristic retention time in the HPLC chromatogram and a comparison of the full spectrum between 190-400 nm of the anabolic components with that of a standard resulted in a very reliable identification. By means of this method 117 samples of application sites were investigated for the presence of anabolic residues. Of the xenobiotic anabolics , 19-nortestosterone (NT) was found most frequently (in 96 cases), whereas diethylstilbestrol (DES) was found in only 11 cases. In all samples the identification of NT and DES was confirmed by high resolution gas chromatography-mass spectrometry (GCMS).

Anabolic Agents↗
PubMed1983

II.6.e Silages.

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Animal Feed↗