Biotransformation of dihydroisosteviol and the effects of transformed products on steroidogenic gene expressions.

The biotransformation of dihydroisosteviol with Absidia pseudocylindrospora ATCC 24169, Streptomyces griseus ATCC 10137, Mucor recurvatus MR36, and Aspergillus niger BCRC 31130 yielded 15 metabolites, eight of which were previously unknown. Structures of metabolites were established by 2D NMR techniques and HRMS data, two of which were further corroborated by chemical means, and another via single-crystal X-ray diffraction analysis. Subsequently, two steroidogenic cell lines (Y-1 mouse adrenal tumor and MA-10 mouse Leydig tumor cells) were used in a reverse transcription-PCR analysis to assess the effects of all compounds on steroidogenic gene expressions using forskolin as a positive control. The tested gene expressions included steroidogenic factor-1 (SF-1), steroidogenic acute regulatory protein (StAR), and cytochrome P450 side-chain cleavage (P450scc) enzyme. Gene expression profiles showed that ten of the tested compounds effectively suppressed P450SCC mRNA expression in both Y-1 and MA-10 cells. Several induced SF-1 gene expression and two enhanced StAR gene expression in Y-1 cells. By contrast, in MA-10 cells, one compound effectively suppressed StAR mRNA expression, whereas for others effectively suppressed SF-1 gene expression. The results suggest that analogs of dihydroisosteviol can be potential modulators to alter steroidogenic gene expressions and subsequent enzyme activities.

Dynamic ankle control in athletes with ankle instability during sports maneuvers.

BACKGROUND: Ankle sprain is a common sports injury. While the effects of static constraints in stabilizing the ankle joint are relatively well understood, those of dynamic constraints are less clear and require further investigation. PURPOSE: This study was undertaken to evaluate the dynamic stability of the ankle joint during the landing phase of running and stop-jump maneuvers in athletes with and without chronic ankle instability (CAI). STUDY DESIGN: Controlled laboratory study. METHODS: Fifteen athletes with CAI and 15 age-matched athletes without CAI performed running and stop-jump landing tasks. The dynamic ankle joint stiffness, tibialis anterior (TA)/peroneus longus (PL) and TA/gastrocnemius lateralis (GL) co-contraction indices, ankle joint angle, and root-mean-square (RMS) of the TA, PL, and GL electromyographic signals were measured during each task. RESULTS: During running, the CAI group exhibited a greater ankle inversion angle than the control group in the pre-landing phase (P = .012-.042) and a lower dynamic ankle joint stiffness in the post-landing phase (CAI: 0.109 ± 0.039 N·m/deg; control: 0.150 ± 0.068 N·m/deg; P = .048). In the stop-jump landing task, athletes with CAI had a significantly lower TA/PL co-contraction index during the pre-landing phase (CAI: 49.1 ± 19; control: 64.8 ± 16; P = .009). In addition, the CAI group exhibited a greater ankle inversion (P = .049), a lower peak eversion (P = .04), and a smaller RMS of the PL electromyographic signal in the post-landing phase (CAI: 0.73 ± 0.32; control: 0.51 ± 0.22; P = .04). CONCLUSION: Athletes with CAI had a relatively inverted ankle, reduced muscle co-contraction, and a lower dynamic stiffness in the ankle joint during the landing phase of sports maneuvers and this may jeopardize the stability of the ankle. CLINICAL RELEVANCE: Sports training or rehabilitation programs should differentiate between the pre-landing and post-landing phases of sports maneuvers, and should educate athletes to land with an appropriate ankle position and muscle recruitment.

Postural control while dressing on two surfaces in the elderly.

Falling is a worldwide problem faced by the elderly, and it has serious consequences. The elderly falls in the bathroom very often, and this raises the concern of the connection between the high incidence of falls in the bathroom and postural control of putting on shorts. Because little is known about postural control while putting on shorts of any age group, this study investigated the effects of age and surface on postural control while putting on shorts. Healthy young adults (n =15; age range: 21-27 years) and the elderly participants (n = 15; age range: 63-78 years) were compared in the temporal-spatial parameters, movement of center of mass (COM), and its interactions with center of pressure (COP) and kinematic measures under two conditions: anti-slipping mat and tile. The results demonstrated that the elderly had lengthened cycle time, decreased single-limb-support ratio, decreased medial-lateral velocity of COM, decreased relative displacement between COM and COP, decreased hip abduction-adduction angle, knee flexion angle, and the height of foot elevation. The elderly demonstrated a conservative strategy that may reduce the mechanical load on the supporting limb but preserve medial-lateral balance during the task. The adopted strategy may be relevant to the reduction of muscle strength and proprioception loss during natural aging process. Although surface did not affect the motion patterns of participants while putting on shorts, the slippery surface should be avoided. Other environmental modification such as a grab bar and bright illumination may have advantages in reducing the risk of falls.