Higher Alu Methylation Levels in Catch-Up Growth in Twenty-Year-Old Offsprings

Alu elements and long interspersed element-1 (LINE-1 or L1) are two major human intersperse repetitive sequences. Lower Alu methylation, but not LINE-1, has been observed in blood cells of people in old age, and in menopausal women having lower bone mass and osteoporosis. Nevertheless, Alu methylation levels also vary among young individuals. Here, we explored phenotypes at birth that are associated with Alu methylation levels in young people. In 2010, 249 twenty-years-old volunteers whose mothers had participated in a study association between birth weight (BW) and nutrition during pregnancy in 1990, were invited to take part in our present study. In this study, the LINE-1 and Alu methylation levels and patterns were measured in peripheral mononuclear cells and correlated with various nutritional parameters during intrauterine and postnatal period of offspring. This included the amount of maternal intake during pregnancy, the mother’s weight gain during pregnancy, birth weight, birth length, and the rate of weight gain in the first year of life. Catch-up growth (CUG) was defined when weight during the first year was >0.67 of the standard score, according to WHO data. No association with LINE-1 methylation was identified. The mean level of Alu methylation in the CUG group was significantly higher than those non-CUG (39.61% and 33.66 % respectively, P < 0.0001). The positive correlation between the history of CUG in the first year and higher Alu methylation indicates the role of Alu methylation, not only in aging cells, but also in the human growth process. Moreover, here is the first study that demonstrated the association between a phenotype during the newborn period and intersperse repetitive sequences methylation during young adulthood.     

The Human Ankle-Foot Complex as a Multi-Configurable Mechanism during the Stance Phase of Walking

<正> The objective of this study is to investigate the biomechanical functions of the human ankle-toot complex during the stancephase of walking. The three-dimensional (3D) gait measurement was conducted by using a 3D infrared multi-camera system anda force plate array to record the Ground Reaction Forces (GRF) and segmental motions simultaneously. The ankle-foot complexwas modelled as a four-segment system, connected by three joints: talocrural joint, sub-talar joint and metatarsophalangeal joint.The subject-specific joint orientations and locations were determined using a functional joint method based on the particleswarm optimisation algorithm. The GRF moment arms and joint moments acting around the talocrural and sub-talar joints werecalculated over the entire stance phase. The estimated talocrural and sub-talar joint locations show noticeable obliquity. Thekinematic and kinetic results strongly suggest that the human ankle-foot complex works as a mechanical mechanism with twodifferent configurations in stance phase of walking. These lead to a significant decrease in the GRF moment arms therebyincreasing the effective mechanical advantages of the ankle plantarflexor muscles. This reconfigurable mechanism enhancesmuscle effectiveness during locomotion by modulating the gear ratio of the ankle plantarflexor muscles in stance. This studyalso reveals many factors may contribute to the locomotor function of the human ankle-foot complex, which include not only itsre-configurable structure, but also its obliquely arranged joints, the characteristic heel-to-toe Centre of Pressure (COP) motionand also the medially acting GRF pattern. Although the human ankle-foot structure is immensely complex, it seems that itsconfiguration and each constitutive component are well tuned to maximise locomotor efficiency and also to minimise risk ofinjury. This result would advance our understanding of the locomotor function of the ankle-foot complex, and also the intrinsicdesign of the ankle-foot musculoskeletal structure. Moreover, this may also provide implications for the design of bionicprosthetic devices and the development of humanoid robots.