Search

Mitochondria are dynamic organelles forming a tubular network that is continuously fusing and dividing to control their morphology and functions. Recent literature has shed new light on a potential link between the dynamic behavior of mitochondria and muscle development. In this study, we investigate the role of mitochondrial fission factor dynamin-related protein 1 (Drp1) in myogenic differentiation. We found that differentiation of C2C12 myoblasts induced by serum starvation was accompanied by a gradual increase in Drp1 protein expression (to ~350% up to 3 days) and a fast reduction of Drp1 phosphorylation at Ser-637 (to ~30%) resulting in translocation of Drp1 protein from the cytosol to mitochondria. During differentiation, treatment of myoblasts with mitochondrial division inhibitor (mdivi- 1), a specific inhibitor of Drp1 GTPase activity, caused extensive formation of elongated mitochondria, which coincided with increased apoptosis evidenced by both enhanced caspase-3 activity and increased number of terminal deoxynucleotidyl transferase-mediated dUTP nick-end labeling (TUNEL)-positive cells. Furthermore, the mdivi-1-treated myotubes (day 3 in differentiation media) showed a reduction in mitochondrial DNA content, mitochondrial mass, and membrane potential in a dose-dependent manner indicating defects in mitochondrial biogenesis during myogenic differentiation. Most interestingly, mdivi-1 treatment significantly suppressed myotube formation in both C2C12 cells and primary myoblasts. Likewise, stable overexpression of a dominant negative mutant Drp1 (K38A) dramatically reduced myogenic differentiation. These data suggest that Drp-1-dependent mitochondrial division is a necessary step for successful myogenic differentiation, and perturbation of mitochondrial dynamics hinders normal mitochondrial adaptations during muscle development. Therefore, in the present study, we report a novel physiological role of mitochondrial dynamics in myogenic differentiation. [ABSTRACT FROM AUTHOR]

The purpose of the study was to determine the influence of varied, controlled distances from the crank axis during arm crank ergometry (ACE) on peak physiological responses and physical work capacity (PWC). Physiological responses to ACE were evaluated using three controlled distances from the crank axis based on 0°, 15°, and 30° from full extension in the elbow while at the furthest point in the crank rotation. Eleven adult, able-bodied women (age = 24.5 ± 4.7 yrs) performed graded maximal ACE tests at each of three distances from the crank axis. Data were analyzed for differences in peak physiological responses and PWC between the three positions. VO2peak at 30° (1.33 L/min) was lower (F(2,20) = 7.171, p < 0.01) than at 0° (1.42 L/min) or at 15° (1.41 L/min). No differences existed between the three distances for any other dependent variable. We conclude that distance from the crank axis during ACE influences VO2peak values, and thus should be controlled for when using ACE to predict aerobic fitness. [ABSTRACT FROM AUTHOR]

Background: Current published data indicate barriers and deficiencies in healthcare for women with physical disabilities. Yet, information regarding the influence of secondary conditions and demographic variables on the actual utilization of general health and rehabilitative services is limited. This research examined this issue., Design: Survey research, Setting: Metropolitan Philadelphia region, Participants: 170 women between 21 and 65 years of age with physical disabilities, Results: Most (96%) women had seen a general healthcare provider (eg, personal physician or gynecologist) in the past 6 months, with 60% reporting seeing such a provider 3 or more times. Despite this high frequency, many women had not had routine preventive gynecologic cancer screening services in the past 5 years. Additionally, respondents reported experiencing on average 12 secondary complications in the past year that moderately impaired their functioning. Many of these complications (fatigue, spasticity, deconditioning, joint pain, depression, social isolation) are preventable. Despite these complications, only about half of the women had seen a rehabilitative service provider (eg, physical therapist, mental health worker) in the past 6 months. Women who saw their general healthcare provider most frequently were more likely to also be receiving services from a rehabilitative service provider., Conclusion: General healthcare providers are frequently seeing women with physical disabilities. Healthcare providers have the ability and opportunity to enhance the health and wellness of this population. Particular attention should be focused on providing preventive healthcare services, including gynecologic cancer screenings and prevention and management of secondary conditions that accompany disability.