High-Content Screening (HCS) is a form of high throughput screening (HTS) that couples automated microscopy with high throughput image analysis to quantify biological effects. Thus, it can be thought of as applied biology bridging basic bench research to drug discovery and clinical medicine. The first aim of this proposal is to develop a HCS strategy to identify small molecules that stimulate the differentiation of murine embryonic stem cells (mESC) toward the cardiac lineage. Screening campaigns are difficult and expensive, and success can be undermined by variation or errors in the underlying biology, robotics, instrumentation and data analysis. Some of these problems can result in systematic errors resistant to correction by established methods. Thus, the second aim of this proposal focuses on development and testing of a novel correction method for redressing systematic errors. The third aim is to implement the HCS campaign and analyze the most interesting hits through confirmatory and secondary screens, medicinal chemistry optimization, and then mechanism of action and target identification. Two libraries were screened : 1) ̃14,000 small synthetic compounds screened at 2 doses and added 1 molecule per sample well, and 2) a chemical mixture library where each sample well is tested against thousands of structurally similar molecules at equimolor concentration. Two molecules from the individual compound screen and one compound from the mixture library screen were selected for structure activity relationship (SAR) analyses. For each compound class, the data define an SAR for cardiomyogenesis from ESCs. Studies focused on the biological mechanism of action studies have revealed two molecules bias germ layer commitment toward early endoderm at the expense of mesoderm. Biotin-tethered probes used to affinity capture small molecule protein targets together with biological assays have suggested metabolic stress is a modulator of mESC specification of the 3 germ layers

This paper applies a social-ecological theory of power to posit that individual HIV-related vulnerability stems from how power is leveraged across situations over time. The current study identified six power domains and explored how the interchangeability of power shapes HIV-related vulnerability among men who have sex with men of colour. Data were collected as part of a mixed-methods study on the social networks and experiences of racial/ethnic and sexual minority status. A total of 35 Asian/Pacific Islander, Black and Latino men who have sex with men were recruited and individual in-depth interviews were conducted. Results showed that men who have sex with men of colour actively traded upon various domains to alter their relative power within a given situation. Results suggest that power interchangeability, or the degree to which power from one domain can be leveraged to gain power in another, may shape HIV-related vulnerability. Findings offer a dynamic understanding of the nature of HIV risk as derived from everyday power exchanges and provide theoretical foundation for future work on individual resilience against HIV-related risks over time.

While many studies have established the relationship between experiences of racism and sexual risk among men who have sex with men of colour, the pathways by which this occurs are underdeveloped. To address this gap, we must better investigate the lived realities of racism in the gay community. In this study, we had the unique opportunity to examine experiences of racism among African American, Latino and Asian/Pacific Islander men who have sex with men living in Los Angeles through focus groups and individual in-depth interviews. We found three themes of racism: exclusion from West Hollywood and the mainstream gay community, sexual rejection based on race/ethnicity, and sexual stereotypes. There were differences across the three racial groups in the experiences of each theme, however. We then considered how racism impacted partner selection and found that race played a salient role in determining power differentials within mixed-race partnerships. Finally, we discussed several future areas for research that can better establish pathways between racism and sexual risk.

The deleterious effects of racism on a wide range of health outcomes, including HIV risk, are well documented among racial/ethnic minority groups in the United States. However, little is known about how men of color who have sex with men (MSM) cope with stress from racism and whether the coping strategies they employ buffer against the impact of racism on sexual risk for HIV transmission. We examined associations of stress and coping with racism with unprotected anal intercourse (UAI) in a sample of African American (N = 403), Asian/Pacific Islander (N = 393), and Latino (N = 400) MSM recruited in Los Angeles County, CA during 2008-2009. Almost two-thirds (65 %) of the sample reported being stressed as a consequence of racism experienced within the gay community. Overall, 51 % of the sample reported having UAI in the prior 6 months. After controlling for race/ethnicity, age, nativity, marital status, sexual orientation, education, HIV serostatus, and lifetime history of incarceration, the multivariate analysis found statistically significant main effects of stress from racism and avoidance coping on UAI; no statistically significant main effects of dismissal, education/confrontation, and social-support seeking were observed. None of the interactions of stress with the four coping measures were statistically significant. Although stress from racism within the gay community increased the likelihood of engaging in UAI among MSM of color, we found little evidence that coping responses to racism buffered stress from racism. Instead, avoidance coping appears to suggest an increase in UAI.

Although bone morphogenetic protein-2 (BMP-2) is known to be the most potent stimulator available for bone formation, a major barrier to widespread clinical use is its inherent instability and absence of an adequate delivery system. Heparin is being widely used in controlled release systems due to its strong binding ability and protective effect for many growth factor proteins. In this work, we developed a hydrogel surface that can mimic heparin to stabilize BMP-2 and to enhance osteogenesis by introducing heparin-mimicking sulfonated molecules such as poly-vinylsulfonic acid (PVSA) or poly-4-styrenesulfonic acid (PSS), into photo-crosslinkable hydrogel. Bioactivity of BMP-2 was well preserved in the presence of polysulfonates during exposure to various therapeutically relevant stressors. The heparin-mimicking sulfonated hydrogels were effective to bind BMP-2 compared to unmodified MeGC hydrogel and significantly enhanced osteogenic differentiation of encapsulated bone marrow stromal cells (BMSCs) without the addition of exogenous BMP-2. The sulfonated hydrogels were effective in delivering exogenous BMP-2 with reduced initial burst and increased BMSCs osteogenesis induced by BMP-2. These findings suggest a novel hydrogel platform for sequestering and stabilizing BMP-2 to enhance osteoinductive activity in bone tissue engineering.

Statement of significance

Although bone morphogenetic protein-2 (BMP-2) is believed to be the most potent cytokine for bone regeneration, its clinical applications require supraphysiological BMP dosage due to its intrinsic instability and fast enzymatic degradation, leading to worrisome side effects. This study demonstrates a novel hydrogel platform that mimics a natural protector of BMPs, heparin, to sequester and stabilize BMP-2 for increased osteoinductive signaling. This study will achieve the stabilization of BMPs with prolonged bioactivity by a synthetic heparin mimic that has not been examined previously. Moreover, the heparin mimetic hydrogel surface can augment endogenous BMP activity by sequestering and localizing the cell-produced BMPs. The additional knowledge gained from this study may suggest basis for future development of material-based therapeutics for tissue engineering.

Objectives

To examine how social networks influence HIV risk among US racial/ethnic minority men who have sex with men (MSM) and whether the associations of social network characteristics with risk vary by race/ethnicity.

Methods

A chain-referral sample of 403 African American, 393 Asian/Pacific Islander, and 400 Latino MSM recruited in Los Angeles County, California, completed a questionnaire, which asked about their egocentric social networks, safer sex peer norms, and male anal intercourse partners. HIV-nonconcordant partnerships were those reported by respondents as serodisconcordant or where self and/or partner serostatus was unknown.

Results

Overall, 26% of the sample reported HIV-nonconcordant unprotected anal intercourse (UAI) with a nonprimary male partner in the previous 6 months. In a generalized estimating equation (GEE) logistic model that controlled for race/ethnicity, age, nativity, incarceration history, and HIV status, being in a more dense network was associated with less HIV-nonconcordant UAI [adjusted odds ratio (AOR) = 0.92, 95% confidence interval (CI): 0.86 to 0.99, P = 0.0467]. In addition, the effect of safer sex peer norms on HIV-nonconcordant UAI was moderated by ego-alter closeness (P = 0.0021). Safer sex peer norms were protective among those reporting "medium" or "high" ego-alter closeness (AOR = 0.70, 95% CI: 0.52 to 0.95, P = 0.0213 and AOR = 0.48, 95% CI: 0.35 to 0.66, P < 0.0001, respectively), but not among those reporting "low" ego-alter closeness (AOR = 0.96, 95% CI: 0.63 to 1.46, P = 0.8333). The effects of density, closeness, and norms on HIV-nonconcordant UAI did not differ by race/ethnicity.

Conclusions

The significant association of social network characteristics with UAI point to network-level factors as important loci for both ongoing research and HIV prevention interventions among US MSM of color.

Research has documented deleterious effects of racism among ethnic minorities and of homophobia among men who have sex with men (MSM). Less is known about the impact of multiple forms of stigmatization on ethnic minority MSM. This study examined substance use by African American, Asian/Pacific Islander and Latino MSM, and the associations of experienced racism and homophobia from various sources with polydrug use and stimulant drug use. Experienced racism within the general community was associated with higher levels of use; other forms of discrimination were either not associated with polydrug or stimulant use or had more complex relationships with use. Implications for further research and interventions are discussed.

Objectives

We examined the associations between specific types and sources of discrimination and mental health outcomes among US racial/ethnic minority men who have sex with men (MSM) and how these associations varied by race/ethnicity.

Methods

A chain-referral sample of 403 African American, 393 Asian and Pacific Islander (API), and 400 Latino MSM recruited in Los Angeles County, California completed a standardized questionnaire. Data were obtained from the Ethnic Minority Men's Health Study from May 2008 to October 2009.

Results

Past-year experiences of racism within the general community and perceived homophobia among heterosexual friends were positively associated with depression and anxiety. Past-year homophobia experienced within the general community was also positively associated with anxiety. These statistically significant associations did not vary across racial/ethnic groups. The positive association of perceived racism within the gay community with anxiety differed by race/ethnicity, and was statistically significant only for APIs. Perceived homophobia within the family was not associated with either depression or anxiety.

Conclusions

Higher levels of experiences of discrimination were associated with psychological distress among MSM of color. However, specific types and sources of discrimination were differentially linked to negative mental health outcomes among African American, API, and Latino MSM.