We hypothesized that 12 weeks of downhill skiing mitigates the functional deficits of knee extensor muscles in elderly subjects due to the specific recruitment of fast motor units during forceful turns on the slope. Downhill skiing led to a 1.4-fold increase in the mean cross-sectional area of slow (P=0.04)- and fast (P=0.08)-type muscle fibers. Fold changes in the expression of the structural component of focal adhesions, gamma-vinculin, were correlated with alterations in concentric force (r=0.64). Hypertrophy of fast fibers was more pronounced in women than in men (1.7 vs 1.1). Gender-specific structural-functional adjustments of knee extensor muscles and attached patellar tendon were reflected by altered expression of pro- vs de-adhesive proteins and a number of correlations. The de-adhesive protein tenascin-C was selectively increased in women compared with men (1.7 vs 1.1) while the content of the adhesive collagen XII was specifically reduced in women. The pro-adhesive focal adhesion kinase showed a specific increase in men compared with women (1.9 vs 1.1). Our findings indicate that quantitatively matched adaptations in slow and fast motor units of extensor muscle underlie the preventive effect of skiing against sarcopenia and support that hypertrophy and reinforcement of fiber adhesion operate in the improvement of muscle strength.

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Apheresis systems for the production of single-donor platelets may be divided into 3 categories: those which collect high-yield products with low leukocyte contamination, those with high yields but higher WBC residuals, and those giving lower yields with high leukocyte contamination. Systems in the first category have clear advantages. Of the 2 methods for producing platelet concentrates (PC) from whole blood – the platelet-rich-plasma (PRP) and the buffy-coat (BC) methods – platelets produced by the BC method are better in terms of yield, WBC residuals, and in vitro function assays. In studies comparing the in vitro function of apheresis platelets and BC platelets, the apheresis platelets show better results in some assays, however, the differences are small. In a recent study carried out in Bristol, UK, corrected count increments (CCIs) for apheresis platelets were significantly higher than those for PRP platelets and not significantly higher than those for BC platelets. Use of apheresis platelets reduces the number of donors to which a recipient is exposed. A further reduction can be achieved if a larger dose of platelets is used per transfusion. A multicenter study carried out in France confirmed earlier findings that the platelet survival time in thrombocytopenic patients is improved if sufficient platelets are given to bring the post-transfusion platelet count above levels achieved with standard-dose transfusions.

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