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Biomedical subjects

J M Oosthuizen

Publications and source records attributed to J M Oosthuizen.

At least 19 recordsLinked to original sources
PubMed1999

The effect of p-nonylphenol on the fertility potential of male rats after gestational, lactational and direct exposure.

There is growing concern that abnormalities in male reproductive health are becoming more frequent. The most fundamental change has been the striking decline in sperm counts and semen quality. The effect of maternal exposure of rats to the oestrogenic environmental substance p-nonylphenol (p-NP) was determined in this study. Exposure to p-NP for the experimental period impaired general growth. The lower testicular mass indicated a direct toxic effect on the testis in animals exposed to p-NP during foetal life, the postnatal period and after weaning until termination at 10 weeks of age. The epididymal mass was also negatively affected by p-NP; this was supported by the decrease in the epididymal ratio. The total cauda epididymal sperm count was significantly lower in the 250 mg kg-1 p-NP dosage group compared to the control and 100 mg kg-1 p-NP groups. The overall lower sperm count with increased p-NP concentrations corresponded with the decreased testicular and epididymal masses. This emphasized the toxicity of p-NP on both testis and epididymis. Seminiferous tubule diameter, lumen diameter and seminiferous epithelium thickness were smaller in the exposed groups, even at the low dose level. These histological measurements further supported the finding of a low testicular mass. In spite of the measurements being smaller, p-NP had no effect on the stages of spermatogenesis except for one animal with disrupted spermatogenesis in some tubules, while others were normal.

Animals↗
PubMed1996

The influence of carbon particles on the concentration of acid phosphatase and lysozyme enzymes within alveolar macrophages during the killing and degradation of Mycobacterium bovis.

SETTING: Diagnostic bronchoscopy performed on untreated African patients with tuberculosis revealed alveolar macrophages filled with carbon particles. It was postulated that this was the result of excessive inhalation of smoke from domestic fires and the consequent phagocytosis by alveolar macrophages. OBJECTIVE: To determine whether carbon particles influence acid phosphatase and lysozyme enzyme concentrations during the killing and degradation of Mycobacterium bovis by alveolar macrophages. DESIGN: Alveolar macrophages were recovered by bronchoalveolar lavage from adult rabbits and cultured. Experimental cultures were exposed to M. bovis and carbon particles, and controls only to M. bovis. Cultures were grown for 42 h for killing and degradation of organisms. Cells were microscopically enumerated for carbon particle content and enzyme stain intensity. The level of significance was determined by means of a statistical test for sample proportions and by using Student's t-test. RESULTS: The majority of alveolar macrophages in the experiments contained large amounts of carbon particles. The average percentage of alveolar macrophages that stained positive for acid phosphatase and lysozyme enzymes is significantly lower in the experiments than in the controls (P < 0.01 and P < 0.001 respectively). CONCLUSION: It is concluded that large amounts of carbon particles significantly decrease these enzyme concentrations intracellularly.

Acid Phosphatase↗
PubMed1996

Influence of carbon particles on superoxide and hydrogen peroxide radical release during the killing of Mycobacterium bovis by alveolar macrophages.

SETTING: Diagnostic bronchoscopy performed on untreated African patients with tuberculosis revealed alveolar macrophages filled with carbon particles. It was postulated that this was the result of excessive inhalation of smoke from domestic fires and the consequent phagocytosis by alveolar macrophages. OBJECTIVE: To determine whether carbon particles influence the release of superoxide and hydrogen peroxide radicals by the alveolar macrophage during killing of Mycobacterium bovis. DESIGN: Alveolar macrophages were recovered by bronchoalveolar lavage from adult rabbits and cultured. Experimental macrophages were exposed to M. bovis and carbon particles, controls only to M. bovis. Superoxide release was measured by the superoxide dependent cytochrome C reduction method and hydrogen peroxide release by luminol dependent chemiluminescence. Significance of differences was calculated by Student's t-test for unpaired data. RESULTS: For superoxide and hydrogen peroxide release, results show a significant difference between the experiments and the controls. Hydrogen peroxide radicals are, however, released at a low constant average median value in the controls. CONCLUSION: Hydrogen peroxide is not greatly involved in the killing of M. bovis by alveolar macrophages since low concentrations are released in the controls. Ingestion of large amounts of carbon particles decreases the release of superoxide and hydrogen peroxide radicals.

Animals↗
PubMed1984

Effect of physical exercise on plasma melatonin levels in normal volunteers.

Plasma melatonin, cortisol and prolactin levels were determined in clinically normal adult Black male volunteers before, immediately after, and 1 hour after a period of controlled physical exercise. In all subjects the levels of these three hormones showed highly significant increases immediately after exercise and returned to pre-exercise levels 1 hour after physical exertion. In subjects who exercised in a room with reduced environmental lighting (54 lux), the plasma melatonin level immediately after exercise was significantly higher than in the group who exercised in a room with a lighting level of 320 lux. Reduction of environmental lighting had no effect on the plasma cortisol and prolactin values immediately after exercise. Significant positive relationships between post-exercise melatonin levels and body mass, age and pulse rate were noted in all volunteers. Since plasma melatonin reached a plateau level after 30 minutes, it is suggested that controlled exercise (step-climbing), which induces an energy output of 185 W/m2 body surface, conducted in a room with reduced environmental lighting for a period of 30 minutes, may form the basis for a pineal function test.

Adolescent↗
PubMedDate not supplied

Melatonin levels are decreased in rheumatoid arthritis.

The hormone, melatonin, is a product of the pineal gland. This methoxy-indole, also known as N-acetyl-5-methoxy-tryptamine, is structurally related to indomethacin, a derivative of methylated indole. The fact that indomethacin has been used successfully in patients suffering from certain chronic inflammatory conditions (such as rheumatoid- and osteoarthritis) gives rise to the question as to whether melatonin also possesses anti-inflammatory virtues. This hypothesis has been tested by determining melatonin concentration levels by means of a radioimmunoassay in patients with rheumatoid arthritis. The daytime melatonin levels of untreated patients were significantly lower (mean concentration = 5.76 pg/ml) than the normal value (mean concentration = 15-33 pg/ml). The second part of this study showed that the administration of indomethacin (100 mg/day) to normal healthy subjects led to a 14.7 pg/ml decrease in plasma melatonin levels. This may indicate that melatonin and indomethacin act synergistically.

Aged↗
PubMedDate not supplied

Testicular compression during exercise: serum testosterone levels.

Serum testosterone levels are increased in athletes after short-term exercise. To investigate whether mechanical compression could contribute to this increase, we subjected 14 male volunteers to mechanical testicular compression via a pneumatic cuff. The serum testosterone levels were sampled at time intervals before, during and after compression. There was a rise in mean serum testosterone levels of 16.7-18.2%, with a maximal increase at 1.5 min after compression was released. Mechanical compression alone did not explain the rise in serum testosterone, although it may have a contributory role.

Exercise↗
PubMedDate not supplied

Differential sperm motility scoring and sperm ATP concentrations.

Sperm motility is one of the most important parameters in semen analysis. In this study the motility scoring method of Hellinga was used. Adenosine triphosphate (ATP) is the main energy source used by the sperm flagellum to initiate and propagate forward motility. This study was conducted to evaluate the interrelationships between sperm ATP and differential motility. The differential motility method supplemented the conventional by which the quantitative and qualitative motility were estimated. There was a good correlation between the differential motility scoring method and sperm [ATP], although the latter did not necessarily improve the diagnostic capacity.

Adenosine Triphosphate↗