ACTN3 R577X genotype and performance of elite middle-long distance swimmers in China.

The ACTN3 gene is one of the genes that have a potential influence on physical performance. Studies have shown that the 577R genotype of ACTN3 is more prevalent in sprint athletes, while the 577X genotype is more prevalent in endurance athletes. In swimming, both power and endurance related phenotypes are equally needed for swimmers to excel at the elite level. Therefore, the ACTN3 R577X polymorphism may become a genetic marker for swimmers. The study aimed to examine the association of the ACTN3 R577X genotype with the performance of elite middle-long distance (MLD) swimmers. The distributions of the ACTN3 R577X (rs1815739) genotype and allele were examined in a general population (206) and a group of elite MLD swimmers (160) in China by using PCR-RFLP and TOF. Compared with the general population, the elite MLD swimmers, especially the females, had a higher frequency of the RR genotype. The swimmers had a higher frequency of the R allele than the general population. However, the difference was not statistically significant. After being stratified by performance, the difference of the R allele frequency between the international master athletes and the general population was statistically significant. The elite MLD swimmers had a higher frequency of the RR genotype than the RX+XX genotype compared with the general population. The ACTN3 R577X polymorphism was associated with the performance of elite MLD swimmers in China. The SNP R577X could be used as a biomarker for selecting elite MLD swimmers in China.

Radical tessellation of the packing of spheres with a log-normal size distribution.

The packing of particles with a log-normal size distribution is studied by means of the discrete element method. The packing structures are analyzed in terms of the topological properties such as the number of faces per radical polyhedron and the number of edges per face, and the metric properties such as the perimeter and area per face and the perimeter, area, and volume per radical polyhedron, obtained from the radical tessellation. The effect of the geometric standard deviation in the log-normal distribution on these properties is quantified. It is shown that when the size distribution gets wider, the packing becomes denser; thus the radical tessellation of a particle has decreased topological and metric properties. The quantitative relationships obtained should be useful in the modeling and analysis of structural properties such as effective thermal conductivity and permeability.

Association of androgen receptor CAG repeat polymorphism with VO2max response to hypoxic training in North China Han men.

The purposes of this study were to investigate the distribution characteristics of CAG repeat polymorphism in exon 1 of androgen receptor gene and the association of CAG polymorphism with VO2max response to hypoxic training in North China Han men. Sixty-five healthy young men completed a 30-day HiHiLo training (living high, exercise high and training low) in a simulated normobaric hypoxic environment. All subjects slept in 14.3-14.8% O2 concentration, and participated in hypoxic training three times a week in 15.4% O2 concentration. VO2max (peak oxygen consumption) and body weight were measured before and after hypoxic training. A total of 15 repeat alleles were observed by CAG genotype analyze, in which (CAG)22 was most common. When using 21 and 22 alleles, respectively, as cut-off points, we found that the baseline body weight of two shorter genotype groups was significantly lower than that of longer ones, and that the ΔVO2max and ΔrVO2max (Δrelative value of VO2max) of two shorter genotype groups were significantly higher than those of longer ones after hypoxic training. These findings indicated that AR CAG repeat polymorphism was associated with the exercise performance after simulated normobaric hypoxic HiHiLo training in North China Han men, and that the shorter genotypes had a better individual response to hypoxic training.

Greater improvement in summer than with light treatment in winter in patients with seasonal affective disorder.

OBJECTIVE: The authors sought to compare the degree of mood improvement after light treatment with mood improvement in the subsequent summer in patients with seasonal affective disorder. METHOD: By using the Seasonal Affective Disorder Version of the Hamilton Depression Rating Scale, the authors rated 15 patients with seasonal affective disorder on three occasions: during winter when the patients were depressed, during winter following 2 weeks of light therapy, and during the following summer. They compared the three conditions by using Friedman's analysis of variance and the Wilcoxon signed ranks test. RESULTS: The patients' scores on the depression scale were significantly higher after 2 weeks of light therapy in winter than during the following summer. CONCLUSIONS: Light treatment for 2 weeks in winter is only partially effective when compared to summer. Further studies will be necessary to assess if summer's light or other factors are the main contributors to this difference.