[Practice relevant rapid tests for milk progesterone in cattle compared with a laboratory-connected routine method]. / Vergleich praxisrelevanter Milchprogesteron-Schnelltests mit einer laborgebundenen Routinemethode beim Rind.

Four commercially available semiquantitative milk progesterone tests (Ovucheck-Praxistest: Cambridge Veterinary Science/Smith Kline), Progestassay-Milchprogesteron (Pitman-Moore/Janssen), Reprostrip-Progesteron-Schnelltest (Noctech/Albrecht), Enzygnost-Milchprogesteron (IQ, 'Bio' UK/Hoechst Veterinär) were examined for their accuracy by using them for the determination of progesterone levels of 64 milk samples, i.e. 1556 single assays. Several test series were performed, using codified samples and changing sequences. Three or four test persons respectively, performed the tests independently and classified the samples semiquantitatively. These test results were then compared to the results acquired by measuring the progesterone levels of the same samples by means of an approved quantitative, labor-bound progesterone test (Hormonost: Biolab). These control tests were performed at a specialized routine labor, by different personnel and at a different location. Lastly, in 48 out of the 64 sampled animals the reproductive status could be evaluated clinically and was taken into account as well. Samples yielding high progesterone levels, i.e. greater than or equal to 9 ng/ml were classified correctly in 84.4 to 96.5% of the cases, whereas samples with low levels (less than or equal to 2.5 ng/ml) were classified correctly in 68.8 to 90.0% of the cases only. Samples ranging between this spectrum (greater than 2.5 less than 9 ng/ml) were classified correctly only in 42.1 to 52.6% of the cases. However, this range appears to be of the most interest for the veterinary practitioner since cows in proestrus or early interestrus tend to have mild progesterone levels within these values. On the other hand, clinical findings are often insufficient for a proper diagnosis just in these animals.(ABSTRACT TRUNCATED AT 250 WORDS)

Steroid determination in milk by enzyme immunoassay (EIA).

A simple and sensitive enzyme immunoassay for progesterone using a homologous system was developed covering the range of 30-3000 fmol/test tube (9.4-944 pg) and applied to extracts from milk fat and bovine serum. By changing the incubation procedure the sensitivity of the assay was increased to measure milk from cows directly without extraction. The influence of milk fat is tolerable and does not falsify physiological results concerning corpus luteum activity or inactivity. The EIA can also be used to follow the change of progesterone under physiological, pathological and therapeutic conditions in samples of human blood and saliva after extraction and in serum directly.

Enzyme-immunoassay for determination of progesterone in milk from cows.

An enzyme-immunoassay using horseradish peroxidase as label is described. The assay has a sensitivity of 0.1-20 pmol, i.e. 0.03-0.63 ng and intra- and inter-assay coefficients of variation of less than 10% when used for the determination of progesterone in samples of milk from cows. Comparison with a radio-immunoassay based on tritiated tracer showed excellent correlation (r = 0.98) for milk samples from cows during the oestrous cycle and early pregnancy.

[Enzyme immunoassay (EIA) for the estrogenic stilbene derivative diethylstilbestrol (DES) (author's transl)]. / Enzym-Immuntest (EIA) für das synthetische Ostrogen Diäthylstilböstrol (DES).

An enzyme immunoassay (EIA) for diethylstilbestrol (DES) is described, which is based on the competitive reaction between DES and peroxidase-labelled DES for an antibody, which has been bond to an insoluble support. The preparation of the enzyme-labelled DES necessitates the use of highly purified 4-O-(carboxypropyl)-diethylstilbestrol (CP-DES) to obtain a highly immunoreactive conjugate. CP-DES was synthesized from DES and ethyl-4-bromobutylate and was purified by a novel isolation procedure involving a simple solvent partition followed by hydrolysis of the ester. It was characterized by it's chemical and biological properties. The assay covers the range from 0.2 to 20 pmol/test (approximately equal to 0.05-5 ng/test). It has sufficient sensitivity and specificity compared with radio immuno assay to make it a potential method for controlling the misuse of this estrogenic substance in animal production.

[Mechanism for the condensation reaction of fatty-acid biosynthesis (author's transl)]. / Zum Mechanismus der Kondensationsreaktion der Fettsäurebiosynthese

The spontaneous hydrogen-deuterium exchange of the methylene group of malonyl-thioesters was investigated by nuclear-magnetic-resonance (NMR) spectroscopy using the model compound S-malonyl-N-acetylcysteamine. The half life of the methylene proteins is 12 to 16 min in 0.1 M K-phosphate buffer at pH 6.5 to 7.0 at 25 degrees C, the conditions of maximal activity of fatty acid synthetase from yeast. Proton catalysis was used for the quick preparation of deuterium- and tritium-labeled malonylthioesters. Compared with malonyl-CoA, dideutero-malonyl-CoA had no primary isotope effect on the reaction velocity of the yeast enzyme catalysed fatty acid synthesis, in which the rate limiting step is the condensation reaction. Although deuterium oxide had a solvent isotope effect, there was no difference in reaction velocities between malonyl CoA and dideuteromalonyl CoA in deuterium oxide. The condensation reaction was investiaged separately from the overall fatty acid synthesis using beta-ketoacyl-acyl-carrier-protein (ACP) synthetase (condensing enzyme) of Escherichia coli. The condensation reaction with deuteromalonyl-ACP had no kinetic isotope effect, in agreement with the observations on the overall reaction. However, in this case no solvent isotope effect was observed with 2H2O. When the condensation reaction was carried out in the presence of tritiated water, there was no incorporation of label into the reaction product acetoacetyl-thioester, excluding proton exchange with the solvent. The results exclude a mechanism for the condensation reaction involving a malonyl carbanion and its acylation as intermediates in the sense of an organic-chemical malonic ester synthesis, and they indicate that the condensation reaction follows a concerted mechanism: The formation of the new carbon-carbon bond is coupled with the cleavage of the carboxyl bond of the malonyl group.