Biomedical subjects

J M den Hartog

Publications and source records attributed to J M den Hartog.

14 recordsLinked to original sources

PubMed1991

[The withdrawing government, a new possibility for the meat inspection].

The Meat Inspection Act has been in existence more than seventy years. Meat inspection based on this act did not change very much over a considerable period. The parties involved, government, industry and science, are all of the opinion that a thorough revision of the aims of the meat inspection is required. Certain aspects, which did not receive much attention in the past: consumers' expectations, the effectiveness of governmental meat inspection in the future in relation to the position of the industry, are reviewed. The Integrated Surveillance System of the Animal and Meat Production Chain can only be partially effective. When the interest of consumers in the product is increased, it will be possible to translate their desires into specifications of the final product. A system of inspection which at least fulfills the safety requirements of the government, can be worked out by the participants without direct responsibility of the government. The direct task of the government will be concentrated on assessing the effectiveness of the system by the safety criteria.

Animals↗

PubMed1991

Control system for detection of the illegal use of naturally occurring steroids in calves.

Within the scope of the National Plan for Hormone Control in The Netherlands, a study was performed to develop a system for control of the illegal use of three naturally occurring hormones [oestradiol-17 beta (E2-17 beta), testosterone (T), progesterone (P)] for fattening purposes in animal production. Using a specific high-performance liquid chromatographic-radioimmunoassay method, reference values were established for concentrations of E2-17 beta, T and P and some of their metabolites in blood plasma and urine from untreated male and female veal calves. E2-17 beta levels of both male and female calves were less than 0.01 microgram/l in blood plasma and less than 0.2 microgram/l in urine. For male veal calves levels of T and epitestosterone (epiT) in blood plasma and urine varied widely. The P levels were less than 0.1-0.3 micrograms/l in blood plasma and less than 0.6-10 micrograms/l in urine from both male and female calves. To investigate the effect of anabolic treatment on the hormone levels in plasma and excreta, male veal calves were injected, subcutaneously into the dewlap, with a solution containing 20 mg of E2-17 beta benzoate and 200 mg of T propionate in 5 ml of arachis oil. Only the levels of E2-17 beta and E2-17 alpha in blood plasma and excreta were elevated until about one week after injection, compared with the untreated control calves and the reference values. T and epiT levels were similar in plasma and excreta from both untreated and treated animals.

Animals↗

PubMed1991

[Problems in the demonstration of Toxoplasma gondii in muscle tissue of sheep].

It is a known fact that sheep usually show a high level of infection with the parasite Toxoplasma gondii. Samples of five grams of muscular tissue taken from the diaphragms of forty sheep were digested with trypsin. The digested material was microscopically examined for bradyzoites of Toxoplasma using the Giemsa-staining method and a Toxoplasma-specific immunofluorescence test. In spite of the fact that antibodies were detected with the ELISA in sixty-five percent of the sheep, Toxoplasma could not be identified in any of the samples of muscular tissue.

Animals↗

PubMed1990

Histological changes in the genital tract of female veal calves implanted with naturally occurring anabolic steroids.

The influence of implants composed of estradiol and testosterone on the genital tract of female veal calves was studied. Striking results were the metaplastic and hyperplastic lesions seen in Bartholin's glands (an estrogenic effect) and a preputial-like separation of the clitoral epithelium (an androgenic effect). Other changes were less pronounced or resembled those found in estrous animals. Similar though less distinct histological changes were observed in the genital tract of animals from a farm with a history of illegal administration of anabolic steroids suggesting illegal treatment. From these findings it is concluded that histological screening of Bartholin's glands for estrogenic influences and of the clitoris for androgenic activity can be useful in tracing illegal anabolic treatment of female veal calves with combination preparations.

Animals↗

PubMed1989

[Histologic hormone studies, a practical evaluation].

Based on histological studies of the prostate or Bartholin's gland, chemical analysis of the urine, injection site or implant was conducted in 114 veal calves suspected of receiving hormonal treatment. In 65% of the samples the results of chemical analysis confirmed the histological findings.

Anabolic Agents↗

PubMed1989

Influence of androgens on the genital tract of cyclic heifers.

Cyclic heifers were implanted with the synthetic androgen trenbolone acetate (TBA = 17 beta-hydroxy-19-norandrosta-4, 9, 11-trien-3-on-17 beta-acetate, C2OH2403) (for formulas see Fig. 1). The influence of this androgen on the macroscopic and microscopic morphology of the genital tract was studied. The most striking result was the induction of polycystic ovaries. The clitoris was markedly enlarged and the cervix showed an increased amount of mucus. Microscopically, extensive folding of the cervical epithelium, consisting of tall swollen columnar cells with basal nuclei was seen. The vagina showed an increase of PAS-positive granules in the superficial layer of the epithelium, while there was no increase in the height of the epithelium. These effects are due to androgenic influence on the female genital tract and are in no case specific to one particular product. They could be of help in the detection of the illegal use of agents with androgenic activity.

Androgens↗

PubMed1988

[The New Dutch Kidney Test. I. Description of the method].

The New Netherlands Kidney test is designed for the detection of antibacterial residues in slaughtered animals. It is a single-plate system in which the culture medium used is composed of Standard II nutrient agar, supplemented with 1 per cent of NaCl, 1 per cent of dextrose, 0.2 per cent of KH2PO4 and 0.28 per cent of Na2HPO4.12H2O. After autoclaving, this medium is cooled to 55 degrees C, which is followed by the addition of trimethoprim (0.12 microgram/ml of agar) and spores of Bacillus subtilis BGA (10(4) ml of agar). The pH should be adjusted to 7.00 +/- 0.05, the prepared medium then being poured out into plates specially designed for this purpose, in such a manner that the thickness of the layer of agar is 2.2 mm throughout. The following method is used in examining slaughtered animals for the presence of residues showing antibacterial activity. Four paper discs are placed in the renal pelvis for a minimum period of thirty minutes; two discs impregnated with fluid from the renal pelvis are frozen at -20 degrees C for possible re-inspection and the other two are laid diagonally on a test plate. 25 microliter of a trimethoprim solution (containing 2 micrograms of TMP per ml of a 10 per cent NaCl solution) are dropped on each of the two last-named discs. The test plates are incubated at 37 degrees C for a period ranging from thirteen to eighteen hours.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗

PubMed1988

[The New Dutch Kidney Test. II. Sensitivity of the test system].

When the in vitro sensitivity of the New Netherlands Kidney Test (NNKT) is compared with that of the test plates of the current Netherlands Kidney Test (NKT) and the EEC four-plate system (ECT), this shows that it occupies a middle position with regard to aminoglycosides, macrolides and tetracyclines. The test plate of the NNKT is more sensitive to sulphonamides. Experimental qualitative and quantitative studies in slaughtered pigs showed that the New Netherlands Kidney Test was equally sensitive or more so in detecting residues of sulphonamides, chloramphenicol, tetracyclines, aminoglycosides and penicillin derivatives than the ECT system for meat. In addition to the simplicity of the current Netherlands Kidney Test, the New Netherlands Kidney Test also shows the broad-spectrum sensitivity of the ECT system. When tolerance standard of nitrofurans or chloramphenicol respectively is 1 or 10 ppb, the New Netherlands Kidney Test will fail.

Animals↗

PubMed1988

[The New Dutch Kidney Test. III. Practical evaluation].

The New Netherlands Kidney Test (NNKT) is a method used to detect residues of antibacterial agents in slaughtered animals. This test will shortly be substituted for the current Netherlands Kidney Test (NKT). The new method was tested for its suitability in meat inspection in the field by four district laboratories, comparative studies with the current Netherlands Kidney test being done at the same time. These investigations showed that, when the new test (NNKT) was used, 5.3 per cent of the category of diseased animals and, using the current Netherlands Kidney Test, 2.2 per cent of these animals were positive. When control discs were used, it was shown that reproducibility of the new test (NNKT) within and between the participating laboratories was satisfactory. A method was developed to obtain similar results on re-examination with the NNKT as those obtained in the first inspection. By freezing the duplicate discs at the time of performance of the test and using these discs for re-inspection, reproducible results were obtained with the NNKT. The substance inhibiting the growth of bacteria was identified in a number of specimens diagnosed as positive when the NNKT was used. False-positive results were not recorded in the NNKT.

Animals↗

PubMed1988

[The predictive value of urinalysis in the New Dutch Kidney Test].

A urine test is described, by which a reliable indication of the time of slaughter is obtained in normal as well as in diseased animals, in which the New Netherlands Kidney Test (NNKT) will be negative. The test plate and testing procedure of the NNKT are used in this urine test.

Animals↗

PubMed1987

[Waiting periods in the New Netherlands Kidney Test].

The New Netherlands Kidney Test used in monitoring slaughtered animals for antimicrobial residues will be legalised in the near future. With regard to this new test, minimum pre-slaughter withdrawal periods required to obtain negative results of the test are roughly indicated. The problem of establishing reliable withdrawal periods is briefly discussed.

Animals↗

PubMed1987

Quantitative aspects of two methods to dissolve collagen-free muscle proteins from acetone dry powders of Guelders ring sausage.

The purpose of this study was to find experimental conditions for the complete solubility of collagen-free muscle proteins (CFMP) using acetone powder of Guelders ring sausage. Preliminary experiments were carried out to choose the best procedure for preparing the acetone dry powder. Two different methods of acetone extraction of minced sausage were compared. The acetone dry mass (ADM) method using continuous extraction in a Soxhlet [2] apparatus gave better results than the acetone powder (ACP) method, which used a blender [1]. The ADM method was used for further investigations. ADM was extracted with two types of sodium dodecyl sulphate (SDS), containing solvents A and B. Solvent A contains a Tris-boric acid buffer (pH 8.2) with 1.5% (m/v) SDS and 0.05% (m/v) dithioerythreitol [3]. Solvent B is a borate-chloric acid buffer (pH 9.0) with 2.0% (m/v) SDS and 1.0% (m/v) mercapto-ethanol [2]. Both solvents showed a linear relationship between the quantities of CFMP in ADM and the dissolved CFMP. The linear relationships were found between quantities of 10.0 and 30.0 mg (solution A) and of 5.0 and 30.0 mg ADM (solution B) per ml solvent. The solubility of CFMP was better in solvent B than in solution A. Completely dissolved CFMP from ADM was only obtained in the case of 5.0 mg ADM in 1.0 ml solution B. These conditions will be used in liquid chromatography experiments, the results of which will be reported later.

Acetone↗

PubMed1985

Actin, a possible quantitative indicator for the quality of meat products. II. Separation and determination of actin from a Guelders ring sausage.

Quality regulations of the Guelders ring sausage are applied in the Netherlands. One of the quality parameters is the content of CFMP (collagen-free muscle protein) in the product. The purpose of this research is to substitute the usual indirect method by a direct analytical method for CFMP. The proposed direct method is composed of separation and determination of actin. Actin was well separated from the sausage product by SDS-gel-filtration chromatography, which was checked by SDS-polyacrylamide-gel electrophoresis. Actin was determined by its 3-methylhistidine content, but this result was smaller than expected. It was caused by the presence of salt during the 3-methylhistidine analysis. Finally, a method for the determination of actin by 3-methylhistidine was developed for the direct procedure. The relations of 3 MH (3-methylhistidine) with respective CFMP and MP (muscle protein) are formulated. Both formulae give a reasonably good estimation of 3 MH, CFMP or MP, one of these parameters of the Guelders ring sausage being known.

Actins↗

PubMed1980

[Actin, target protein for estimation of the muscle meat content of meat products? (author's transl)].

Until recently, the muscle meat protein content of comminuted and heated meat products could be estimated by subtracting the connective tissue content from the total protein content. Both contents can be fairly well determined. Today, however, the potential use of non-meat proteins makes it very difficult to estimate the muscle protein content of the meat product. This is one of the reasons for which extensive studies were done to develop a direct method for determination of the muscle meat content. An accurate parameter for this muscle meat is not available. In the present investigations, the proteins of meat of various animals (cow, pig, chicken and horse) were studied by SDS polyacrylamide gel electrophoresis. The thermo stability (heating for 30 minutes at temperatures ranging from 50 degrees C- 120 degrees C) of the meat proteins was also studied. The pherograms of the SDS-extracts of these kinds of meats appeared to be very similar. The various myofibrillar proteins were plainly perceptible in every case. Particularly actin was found to be resistant to a heating procedure for 30 minutes at 90 degrees C (and even higher). As regards the analytical problems relating to the estimation of the muscle meat content, actin would appear to offer good perspectives.

Actins↗