Effects of a single bout of resistance exercise on calcium and bone metabolism in untrained young males.

Although resistance exercise training appears to increase bone mineral density in the long term, a single bout of resistance exercise could paradoxically induce bone homeostasis disturbance, secondary to metabolic acidosis. To examine this, we obtained fasting blood and 24-hour urine samples from untrained male subjects for 5 subsequent days (control day, exercise day, and three post-exercise days), and investigated the effects of a single bout of resistance exercise on urinary calcium excretion and bone metabolism as indicated by sensitive biomarkers of bone formation and resorption. After an intense bout of resistance exercise, blood and urine became more acidic and renal net acid excretion significantly increased by 44% on the exercise day. Urinary calcium excretion significantly increased by 48% on the exercise day. Plasma procollagen type-I C-terminal concentration significantly decreased by 12% on the next day of the exercise and serum bone-specific alkaline phosphatase activity also significantly decreased by 13% and 9% on days 2 and 3, respectively, after the exercise. There was no significant change in serum osteocalcin concentration. Serum tartrate-resistant acid phosphatase activity significantly decreased by 15% on the day after the exercise and urinary deoxypyridinoline excretion decreased by 22% and 27% on days 1 and 3, respectively, after the exercise. These results suggest that the early response of bone to a bout of resistance exercise in untrained individuals was transient decreases in bone formation and resorption, whereas urinary calcium excretion increased.

Cometabolism of DDT analogs by a Pseudomonas sp.

A Pseudomonas sp. capable of growth on several nonchlorinated and mono-p-chloro-substituted analogs of DDT as a sole carbon source degraded bis(p-chlorophenyl)methane and 1,1-bis(p-chlorophenyl)ethane only in the presence of diphenylethane. The products p-chlorophenylacetic acid and 2-(p-chlorophenyl)-propionic acid were not further metabolized by the bacterium. Other chlorinated analogs of DDT were found to be recalcitrant to cometabolic degradation with diphenylethane.

Metabolism of DDT analogues by a Pseudomonas sp.

A Pseudomonas sp. rapidly metabolized several nonchlorinated analogues of DDT, with the exception of 2,2-diphenylethanol, as the sole carbon source. Several of the mono-p-chloro-substituted diphenyl analogues were also metabolized as the sole carbon source by the bacterium. The resulting chlorinated aromatic acid metabolites were not further metabolized. The isolate was unable to metabolize p,p'-dichlorodiphenyl analogues as the sole carbon source.

Degradation of lindane by Escherichia coli.

Lindane was degraded by Escherichia coli isolated from rat feces. About 10% of the added lindane was metabolized by the bacterium in Trypticase soy broth containing the pesticide. A single metabolite, 2,3,4,5,6-pentachloro-1-cyclohexene, was detected and identified by gas chromatography and mass spectrometry.