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Between-sex Differences (between-sex + difference)
Selected AbstractsLow Skeletal Muscle Mass Is Associated With Poor Structural Parameters of Bone and Impaired Balance in Elderly Men,The MINOS Study,JOURNAL OF BONE AND MINERAL RESEARCH, Issue 5 2005Pawel Szulc MD Abstract In 796 men, 50-85 years of age, decreased relative skeletal muscle mass index was associated with narrower bones, thinner cortices, and a consequent decreased bending strength (lower section modulus), as well as with impaired balance and an increased risk of falls. Introduction: In men, appendicular skeletal muscle mass (ASM) is correlated positively with BMC and areal BMD (aBMD). In elderly men, low muscle mass and strength (sarcopenia) is associated with difficulties in daily living activities. The aim of this study was to evaluate if ASM is correlated with bone size, mechanical properties of bones, balance, and risk of falls in elderly men. Materials and Methods: This study used 796 men, 50-85 years of age, belonging to the MINOS cohort. Lifestyle factors were evaluated by standardized questionnaires. Estimates of mechanical bone properties were derived from aBMD measured by DXA. ASM was estimated by DXA. The relative skeletal muscle mass index (RASM) was calculated as ASM/(body height)2.3. Results: After adjustment for age, body size, tobacco smoking, professional physical activity, and 17,-estradiol concentration, RASM was correlated positively with BMC, aBMD, external diameter, and cortical thickness (r = 0.17-0.34, p < 0.0001) but not with volumetric BMD. Consequently, RASM was correlated with section modulus (r = 0.29-0.39, p < 0.0001). Men in the lowest quartile of RASM had section modulus of femoral neck and distal radius lower by 12-18% in comparison with men in the highest quartile of RASM. In contrast, bone width was not correlated with fat mass, reflecting the load of body weight (except for L3), which suggests that the muscular strain may exert a direct stimulatory effect on periosteal apposition. After adjustment for confounding variables, a decrease in RASM was associated with increased risk of falls and of inability to accomplish clinical tests of muscle strength, static balance, and dynamic balance (odds ratio per 1 SD decrease in RASM, 1.31-2.23; p < 0.05-0.001). Conclusions: In elderly men, decreased RASM is associated with narrower bones and thinner cortices, which results in a lower bending strength. Low RASM is associated with impaired balance and with an increased risk of falls in elderly men. It remains to be studied whether low RASM is associated with decreased periosteal apposition and with increased fracture risk in elderly men, and whether the difference in skeletal muscle mass between men and women contributes to the between-sex difference in fracture incidence. [source] The effects of age and sex on chondroitin sulfates in normal synovial fluidARTHRITIS & RHEUMATISM, Issue 8 2002Yoshihito Nakayama Objective To examine how age and sex influence chondroitin sulfates (CS) in normal synovial fluid, we measured the concentrations of chondroitin 6-sulfate (C6S), chondroitin 4-sulfate (C4S), and hyaluronic acid (HA) in healthy subjects of different ages. Methods Synovial fluid samples were obtained from 82 healthy volunteers, ages 20,79 years. Results The concentrations of CS and HA and the C6S:C4S ratio varied with age. Their values were highest between 20 and 30 years of age, and thereafter they showed a tendency to decrease. Statistically, the C6S concentration and the C6S:C4S ratio at ages 60,70 years were significantly lower than those at 20,30 years of age. There was also a clear between-sex difference, in which the CS concentrations and the C6S:C4S ratio in women were significantly lower than those in men (P = 0.0003 for C6S, P = 0.02 for C4S, P = 0.002 for C6S:C4S ratio). In sharp contrast, little between-sex difference was found in the HA concentration. In multiple regression analysis, age correlated strongly with the C6S concentration and the C6S:C4S ratio (r = ,0.521 and r = ,0.617, respectively), weakly with the C4S concentration (r = ,0.202), and moderately with the HA concentration (r = ,0.483). Sex showed a weak correlation with the concentrations of C6S and C4S and the C6S:C4S ratio (r = 0.307, r = 0.225, and r = 0.237, respectively), and little correlation was seen between sex and the HA concentration. Conclusion The CS concentrations and the sulfation patterns in normal synovial fluid vary with age and sex, and these physiologic variations need to be taken into account when using synovial fluid CS as markers for arthritic conditions. [source] Gender, light and water effects in carbon isotope discrimination, and growth rates in the dioecious tree Ilex aquifoliumFUNCTIONAL ECOLOGY, Issue 5 2000R. Retuerto Abstract 1.,Detailed understanding of the specific physiology of sexes in dioecious species is required to explain patterns in gender dimorphism. Under controlled-environment conditions we tested the hypothesis that sexes of the dioecious tree holly Ilex aquifolium L. (Aquifoliaceae) differed in growth and long-term potential water-use efficiency, as measured by carbon isotope discrimination (,13C), and that these differences were dependent on the environmental context. 2.,Patterns of response in ,13C to the various combinations of light and water were gender-specific. Under more xeric conditions, females maintained significantly higher ,13C than males. 3.,Female plants exhibited significantly greater relative diameter growth rates than male plants. 4.,As expected, ,13C significantly increased with decreasing irradiance, and decreased with increasing limitation in water supply. Light and water effects were not independent, with a more pronounced drought effect in decreasing leaf ,13C under unshaded than under shaded conditions. 5.,Our results suggest that between-sex differences in physiology are context-dependent. Future studies attempting to assess gender dimorphism should take more account of gender-specific interactions with the environment. Gender-specific efficiency in water use could play a decisive role in explaining gender differences in growth and ecological interactions. [source] Sex-specific physiological, allocation and growth responses to water availability in the subdioecious plant Honckenya peploidesPLANT BIOLOGY, Issue 2 2009J. Sánchez-Vilas Abstract The gender of dimorphic plant species is often affected by ecophysiological variables. Differences have been interpreted as a response of the sexes to meet specific resource demands associated with reproduction. This study investigated whether sex-specific variations in ecophysiological traits in response to water availability determine the performance of each sex in different habitats, and therefore promote extreme spatial segregation of the sexes in the subdioecious plant, Honckenya peploides. Twenty-seven plants of each sex were individually potted in dune sand and assigned randomly to one of three water treatments. Well-watered plants were watered daily to field capacity, whereas plants in the moderate and high-water stress treatments received 40% and 20%, respectively, of the water given to well-watered plants. Photochemical efficiency, leaf spectral properties and components of relative growth rate (leaf area ratio and net assimilation rate) were measured. Photochemical efficiencies integrated over time were higher in male than in female plants. Water deficit decreased maximum quantum yield in female plants more rapidly than in male plants, but female plants (unlike male plants) had recovered to initial values by the end of the experiment. Maximum quantum yield in male plants was more affected by water stress than in female plants, indicating that male plants were more susceptible to photoinhibition. The two sexes did not differ in growth rate, but male plants invested a higher proportion of their biomass in leaves, had a higher leaf area per unit biomass and lower net assimilation rate relative to female plants. Female plants had a higher water content and succulence than male plants. Differences in stomatal density between the sexes depended on water availability. The results suggest that the two sexes of H. peploides have different strategies for coping with water stress. The study also provides evidence of sex differences in allocation traits. We conclude that between-sex differences in ecophysiological and allocation traits may contribute to explain habitat-related between-sex differences in performance and, therefore, the spatial segregation of the sexes. [source] | |||||||||||||