The impact of calcium, magnesium, zinc, and copper in blood and seminal plasma on semen parameters in men.

To investigate the impact of calcium, magnesium, zinc, and copper in blood and seminal plasma on semen parameters, 107 fertile and 103 subfertile males provided a standardized blood and semen specimen. Total calcium and magnesium concentrations were determined with colorimetric end point assay procedures. Zinc and copper were determined by flame atomic absorption spectrophotometer (AAS). Semen analysis was performed according to World Health Organization guidelines (1992). The concentrations of calcium, magnesium, zinc, and copper in blood and seminal plasma were not different between the subfertile and fertile group. Weak correlations were demonstrated between blood plasma zinc concentrations and sperm count (rs = 0.18), sperm motility (rs = 0.15), and abnormal sperm morphology (rs = 0.13). Zinc and magnesium concentrations in seminal plasma correlated weakly with sperm count (rs = 0.17 and rs = 0.16, respectively), and copper concentrations in blood plasma with motility (rs = 0.25). Strong correlations were found between calcium, magnesium, and zinc in seminal plasma. Although calcium, magnesium, zinc, and copper play an essential role in spermatogenesis and fertility, the determination of these elements in blood and seminal plasma does not discriminate on the basis of fertility in this group of men.

Stereospecific in vitro embryotoxicity of l-homocysteine in pre- and post-implantation rodent embryos.

Recently a derangement of homocysteine metabolism has been suggested as a possible risk factor for neural tube defects and recurrent spontaneous abortion. To investigate a possible role of homocysteine in the aetiology of neural tube defects we tested the in vitro embryotoxicity of l-homocysteine by culturing day 10 post coitum post-implantation rat embryos in whole embryo culture (WEC) for 24 hr and day 2 post coitum pre-implantation mouse embryos for 48 hr. With an area under curve (AUC) of 6.3 mm/hr, l-homocysteine significantly reduced the percentage of mouse embryos that developed into blastocysts. In rat WEC, an AUC for l-homocysteine of 3.6 mm/hr reduced the mitotic index of the neural epithelium of the rhombencephalon and the cell density of the mesenchyme adjacent to it, while at an AUC of 7.2 mm/hr l-homocysteine reduced the total morphological score and the number of malformations was increased. Malformations most often seen were transparent rhombencephalon, no or delayed formation of forelimb buds, dysmorphogenesis of the somites, and blister formation dorso-laterally of the place of forelimb bud formation. The embryotoxicity of l-homocysteine was stereospecific since d-homocysteine caused no embryotoxic effects. Also the oxidation product l-homocystine (AUC, 72 mm/hr) and the metabolite l-methionine (AUC, 144 mm/hr) were not embryotoxic. Both stereoisomers of homocysteinethiolactone were embryotoxic at an AUC of 72 mm/hr. The results are discussed in relation to the metabolism of homocysteine and methionine and their possible role in the neurulation process.

Sex difference in Aroclor 1254 induction of rat hepatocytes: Consequences for in vitro embryotoxicity and mutagenicity of cyclophosphamide.

The sequential culture of rat hepatocytes and post-implantation rat embryos has been proposed as a model for the in vitro testing of pro-teratogens. Comparing this model with a model in which embryos and hepatocytes are cultured simultaneously a striking difference in sensitivity was noted. To address the question of whether this difference could be explained by different sex and/or Aroclor 1254 pretreatment of the rats providing the hepatocytes, an experiment was designed with four groups: male Aroclor 1254 pretreated (M(1)), male untreated, pregnant female Aroclor 1254 pretreated (F(1)) and pregnant female untreated rats. Hepatocytes were incubated in the presence of cyclophosphamide (CP) and rat embryos were cultured in the media derived from the hepatocyte culture (i.e. the sequential culture model). Additionally, the CP concentrations of the media were analysed and subsequently the media were tested in a bacterial mutagenicity test (Salmonella typhimurium TA1535). With a CP concentration of 300 mum, M(1) produced maximum embryotoxicity and mutagenicity after 4 hr of hepatocytes incubation. All other groups showed no or only a slight increase in embryotoxicity and mutagenicity for all hepatocyte incubations. M(1) was also quickest to eliminate CP from the medium. These results indicate that despite a strong increase in total cytochrome P-450 in both sexes as a result of Aroclor 1254 pretreatment, and in the absence of a significant difference in total cytochrome P-450 between M(1) and F(1), Aroclor 1254 pretreatment has a much more pronounced effect in male rats than in pregnant female rats with regard to the production of embryotoxic and mutagenic metabolites of CP.