The effect of exercise on the production and clearance of testosterone in well trained young men

Tritium-labelled testosterone was infused into four well-trained subjects at rest and during one hour of exercise at about 60% of their maximum aerobic power. This exercise regime led to a mean increase of 27% (range 10-51%) in plasma testosterone concentration. At the same time there were significant decreases in the estimated hepatic plasma flow (EHPF) (45%; range 28-67%), metabolic clearance rate of testosterone (MCRT) (29%; range 18-37%) and plasma volume (8.2%; range 3-10%). The production rate of testosterone decreased by 10% (range 9-22%) but this was not statistically significant. The ratio MCRT:EHPF increased in 3 out of 4 subjects in response to exercise but there was considerable inter-subject variation both at rest and during exercise. These findings suggest that the exercise-induced elevation of testosterone level is due solely to the reduction in the rate at which testosterone is cleared from the plasma. The principal cause of the reduction in MCRT is probably the reduction in EHPF but the variation in the ratio MCRT:EHPF suggests that changes in the extrahepatic clearance of testosterone may also be involved.     

Genbank accession #: 133708

Plant Molecular Biology -     

The effect of high altitude on saliva aldosterone and glucocorticoid concentrations

Saliva was collected from six healthy young men at hourly intervals at sea level and after 1-2, 8-9 and 15-16 days at 4450 m on Mount Kenya for measurement of aldosterone (SA) and glucocorticoid (SGC, cortisol + cortisone) concentrations. Blood samples were collected simultaneously with some of the saliva samples and analysis of these showed that plasma and saliva concentrations of aldosterone and glucocorticoids were highly correlated (r = 0.91 and 0.75 respectively; p less than 0.01 for both hormones). Mean SA for the group was reduced to approximately 50% of the sea-level value (p less than 0.05) by the time the first saliva samples were collected at altitude, and remained at this depressed level throughout the 2-week period on Mount Kenya, although there was considerable inter-subject variation. SGC concentration also tended to be lower on Mount Kenya than at sea level. Though SA was lower throughout the day at altitude compared to sea level, the principal difference in the temporal pattern of SA was the reduction or complete absence of the marked rise in SA that normally occurs in the first few hours after rising. SA and SGC responses to exercise, which consisted of stepping on and off and 0.4-m high stool 60 times/min for 25 min, were assessed at sea level and after various periods at 4450 m.(ABSTRACT TRUNCATED AT 250 WORDS)     

Properties of Extracellular Enzymes from Aphanomyces astaci and Their Relevance in the Penetration Process of Crayfish Cuticle

In culture filtrates from the crayfish plague parasite, Aphanomyces astaci, protease and a low level of hyaluronidase activity were found. The hyaluronidase activity was highest at pH 6.5 or above and at about 23°C. The protease activity had a broad pH-optimum, between pH 7 and at least pH 10, and was partially denatured at 30°C. However, when incubated for 30 min with the substrate, casein, the activity increased logarithmically up to about 35–40°C and had an apparent optimum at 45–50°C. The proteases from the parasitic as well as from two less proteolytic, saprophytic Aphanomyces species were predominantly constitutive and were excreted mainly by the older mycelia. Proteases from the parasite and a saprophyte did not reach full activity until 10–30 min after substrate addition. No lipase activity was found in the case of the mycelium of the parasitic species. However, esterase was apparently present inside germinating zoospores. The native enzymes of A. astaci could degrade freeze-dried soft cuticle from crayfish. The relevance of the different enzymes of A. astaci for the penetration process within the cuticle of crayfish is discussed.     

Long-term predictable nipple projection following reconstruction.

The creation of the nipple-areola complex is often the final step in the surgical treatment of breast cancer patients, and it consequently has important symbolic and aesthetic implications. Patient expectations and the need for symmetry make nipple projection a crucial aesthetic determinant of nipple reconstruction. We hypothesize that long-term nipple projection and shape can be achieved in a predictable fashion using the modified star dermal fat flap technique. Prospectively, 93 nipples were reconstructed by a single surgeon using a modified star dermal fat flap technique in 44 implant and 49 TRAM flap breast reconstructions. Flap dimensions (base diameter and flap length) were designed according to patient desire or to the base diameter and projection of the opposite breast nipple. A standardized, 3-month postoperative care regimen was observed in all patients. Nipple projection was assessed by the same observer at each follow-up examination. The average length of follow-up was 730 days (745 for TRAM reconstructions and 713 for implants). Consistently, an average of 41 percent of the intraoperative projection remained intact in both groups at final evaluation (SD 12 percent). The total flap length was strongly predictive of intraoperative and long-term projection (r = 0.64 and 0.86, p < 0.0001). Flap lengths ranged from 5.5 to 9.0 cm, and in a linear correlation, resulted in intraoperative projection of 1.0 to 2.1 cm, respectively, and long-term projection of 0.4 to 0.83 cm, respectively. Based on the linear relationship, every 1-cm increase in flap length could be expected to result in a 0.16-cm increase in projection. When controlled for flap length and intraoperative projection, there was no difference between TRAM and implant nipple reconstruction in predicting postoperative nipple projection. Intraoperative planning and execution are critical to achieve predictable nipple shape, size, and projection. The dimensions of the star dermal fat flap can be strategically modified to allow the surgeon predictable projection with a consistent 41-percent preservation of intraoperative nipple projection in both TRAM and implant patients at 2 years.