Seasonal changes in performance and free testosterone: cortisol ratio of elite female rowers

The aim of this study was to investigate the seasonal behaviour of the plasma free testosterone: cortisol ratio (FTCR) and to relate hormonal changes to daily training volume and performance parameters on a rowing ergometer in elite female rowers. During 9 months of training preceding the 1988 Olympic Games the resting values of the FTCR in six elite female rowers were regularly (ten times) studied. Daily training volume was analysed in terms of rowed distance (l _rowad) and time (t). In addition, two performance parameters, the power at 4.0 mmol·l^–1 lactate concentration in the blood and the maximal power, were determined by a test on a rowing ergometer. The results indicated that the mean FTCR test value did not differ significantly from the level of the initial test or from the mean value of the directly preceding test. A significant negative correlation (r=–0.98, P<0.01) between FTCR and l _rowed was found in a period i.e. at a training camp, when there was a sudden increase in training volume. When FTCR was related to t a significant positive correlation (r=0.88, P<0.05) was found only for the period at the training camp. Our data further suggested that the FTCR alone was not an adequate indicator for the anabolic/catabolic balance in elite female rowers. This finding was contrary to previous findings in elite male rowers. However, in training practice the FTCR seems useful as an indicator of the hormonal training status of elite female rowers when complemented with data about total and free testosterone, performance parameters and knowledge concerning cyclic variations of the FTCR.Both departments co-operate in the working group Janus Jongbloed Research Centre, Utrecht, The Netherlands     

Über hybridogene Pseudoparthenogenesis

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Iron supply and hydrogenase activity in green algae

Summary An addition of EDTA to the culture medium considerably increases H₂ metabolism of green algae. However, even under these conditions, several hours of anaerobic incubation (adaptation) are necessary for the optimum of hydrogenase activity to be reached. In addition, the stability of H₂ metabolism during longer periods of anaerobiosis is much better.     

Effects of retinoic acid metabolites on proliferation and differentiation of the clonal rhabdomyosarcoma cell line BA-HAN-1C

Summary— The clonal rat rhabdomyosarcoma cell line BA-HAN-IC is composed of proliferating mononuclear cells, some of which spontaneously fuse to terminally differentiated myotube-like giant cells. This cell line has been shown to be susceptible to differentiation induction with all-trans retinoic acid (RA). Since it is still unknown whether exclusively all-trans RA itself or also its metabolites can act as inductive compounds in our cell line, we exposed BA-HAN-1C cells to the metabolites 4-hydroxy RA, 4-oxo RA and 5,6epoxy RA. Exposure to these RA metabolites resulted in a significant inhibition of proliferation (P < 0.001) and induction of cellular differentiation, as evidenced by a significant increase in the number of myotube-like giant cells (P < 0.05) and a significant increase in creatine kinase activity (P < 0.05). However, differences in the inductive potency of these RA metabolites became apparent. Furthermore, RA metabolites exhibited a significantly weaker (P < 0.05) inductive activity when compared to all-trans RA. Summarizing our results we could demonstrate that the endogenous metabolites 4-hydroxy RA, 4-oxo RA and 5,6-epoxy RA are not merely deactivated cellular excretion products of all-trans RA, but potent inducers of differentiation and inhibitors of proliferation, possibly contributing to the complex physiological actions of retinoic acid.     

Beeinflussung der leitfähigkeit abgetöteter gewebe durch Behandlung mit einem Narkotikum

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