Characterization of primary human skeletal muscle cells from multiple commercial sources.

There is a significant unmet need for safe, anabolic muscle therapies to treat diseases and conditions associated with severe muscle weakness and frailty. The identification of such therapies requires appropriate cell-based screening assays to select compounds for further development using animal models. Primary human skeletal muscle cells have recently become available from a number of commercial vendors. Such cells may be valuable for studying the mechanisms that direct muscle differentiation, and for identifying and characterizing novel therapeutic approaches for the treatment of age- and injury-induced muscle disorders. However, only limited characterization of these cells has been reported to date. Therefore, we have examined four primary human muscle cell preparations from three different vendors for their capacity to differentiate into multinucleated myotubes. Two of the preparations demonstrated robust myotube formation and expressed characteristic markers of muscle differentiation. Furthermore, these myotubes could be induced to undergo morphological atrophy- and hypertrophy-like responses, and atrophy could be blocked with an inhibitor of myostatin signaling, a pathway that is known to negatively regulate muscle mass. Finally, the myotubes were efficiently infected with recombinant adenovirus, providing a tool for genetic modification. Taken together, our results indicate that primary human muscle cells can be a useful system for studying muscle differentiation, and may also provide tools for studying new therapeutic molecules for the treatment of muscle disease.

Social integration, social contacts, and blood pressure dipping in African-Americans and whites.

OBJECTIVE: Both the size and diversity of an individual's social network are strongly and prospectively linked with cardiovascular morbidity and mortality. Social relationships may influence cardiovascular outcomes, at least in part, via their impact on physiologic pathways influenced by stress, such as daytime blood pressure (BP) levels. However, scant research has examined whether social relationships influence key nocturnal pathways, such as nocturnal BP dipping. METHODS: The current study examined the degree to which social integration, as measured by participants' reported engagement in a range of different types of social relationships, and the frequency of daily social contacts influence the ratio of night/day mean arterial pressure (MAP) in a community sample of African-American and white men and women (N = 224). In addition, we examined the degree to which observed associations persisted after statistical adjustment for factors known to covary with nocturnal BP, including objective measures of sleep, catecholamines, health behaviors, and comorbidities. RESULTS: In fully adjusted models, there was a significant association between both social integration and frequency of social contacts and the ratio of night/day MAP, indicating that socially isolated individuals were more likely to have blunted nocturnal BP-dipping profiles. There was also a significant interaction between social contact frequency and ethnicity, suggesting that the benefits of social relationships were particularly evident in African-Americans. CONCLUSIONS: These findings contribute to our understanding of how social integration or conversely, social isolation, influences cardiovascular risk.

Race and financial strain are independent correlates of sleep in midlife women: the SWAN sleep study.

STUDY OBJECTIVES: To examine racial differences in sleep in a large cohort of midlife women and to evaluate whether indices of socioeconomic status (SES) are associated with racial differences in sleep. DESIGN: Cross-sectional study. SETTING: Participants' homes. PARTICIPANTS: Caucasian (n=171), African American (n=138) and Chinese women (n=59). INTERVENTIONS: None. MEASUREMENTS: Sleep quality was assessed with the Pittsburgh Sleep Quality Index. Polysomnographically assessed sleep duration, continuity, architecture, and NREM electroencephalograhic (EEG) power were calculated over multiple nights. Sleep disordered breathing and periodic leg movements were measured on a separate night. Linear regression analysis was used to model the independent and synergistic effects of race and SES on sleep after adjusting for other factors that impact sleep in midlife women. Indices of SES were self-reported educational attainment and financial strain. RESULTS: Sleep was worse in African American women than Caucasian participants as measured by self-report, visual sleep stage scoring, and NREM EEG power. Slow wave sleep differences were also observed between Chinese and Caucasian participants. Racial differences persisted after adjustment for indices of SES. Although educational attainment was unrelated to sleep, financial strain was associated with decreased sleep quality and lower sleep efficiency. Financial strain-by-race interactions were not statistically significant, suggesting that financial strain has additive effects on sleep, independent of race. CONCLUSIONS: Independent relationships between race and financial strain with sleep were observed despite statistical adjustment for other factors that might account for these relationships. Results do not suggest that assessed indices of SES moderate the race-sleep relationship, perhaps due to too few women of low SES in the study.

Influence of race and socioeconomic status on sleep: Pittsburgh SleepSCORE project.

OBJECTIVE: To examine the independent and interactive effects of race and socioeconomic status (SES) on objective indices and self-reports of sleep. METHODS: The sleep of 187 adults (41% black; mean age = 59.5 +/- 7.2 years) was examined. Nine nights of actigraphy and two nights of inhome polysomnography (PSG) were used to assess average sleep duration, continuity, and architecture; self-report was used to assess sleep quality. Psychosocial factors, health behaviors, and environmental factors were also measured. RESULTS: Blacks had shorter sleep duration and lower sleep efficiency, as measured by actigraphy and PSG, and they spent less time proportionately in Stage 3-4 sleep, compared with others (p < .01). Lower SES was associated with longer actigraphy-measured latency, more wake after sleep onset as measured by PSG, and poorer sleep quality on the Pittsburgh Sleep Quality Index (p < .05). CONCLUSIONS: Blacks and perhaps individuals in lower SES groups may be at risk for sleep disturbances and associated health consequences.

Socioeconomic status variables predict cardiovascular disease risk factors and prospective mortality risk among women with chest pain. The WISE Study.

This study examined the relationship between socioeconomic status (SES), coronary artery disease (CAD) risk factors, and all-cause mortality in a cohort of women with chest pain. A total of 743 women (mean age = 59.6 years) with chest pain who were referred for coronary angiography completed a diagnostic protocol including CAD risk factor assessment, ischemic testing, psychosocial testing, and queries of SES. Patients were followed for about 2 years to track subsequent all-cause mortality. Results indicated that low SES was associated with CAD risk factors, including higher BMI and waist-hip ratios, cigarette smoking, lower reported activity levels, and a greater probability of hypertension. Low income also predicted all-cause mortality (RR = 2.7, 95% CI 1.4, 5.2), including after adjusting for proposed psychosocial and behavioral variables (RR = 5.9, 95% CI 1.2-29.7). Future research will require a thorough a priori focus on potential mechanisms to better understand SES effects on health.