Vitamin D deficiency is associated with development of subclinical coronary artery disease in HIV-infected African American cocaine users with low Framingham-defined cardiovascular risk

Chronic cocaine use may lead to premature atherosclerosis, but the prevalence of and risk factors for coronary artery disease (CAD) in asymptomatic cocaine users have not been reported. The objective of this study was to examine whether vitamin D deficiency is associated with the development of CAD in human immunodeficiency virus (HIV)-infected African American cocaine users with low CAD risk. METHODS: In this prospective follow-up study, we investigated 169 HIV-infected African American cocaine users with low Framingham risk at baseline. The main outcome measures were incidence of subclinical CAD and development of subclinical CAD. RESULTS: Fifty of the 169 African Americans had evidence of subclinical disease on the initial cardiac computed tomography. A second cardiac computed tomography was performed on the 119 African Americans without disease on the first scan. The total sum of person-years of follow-up was 289.6. Subclinical CAD was detected in 11 of these, yielding an overall incidence of 3.80/100 person-years (95% confidence interval 1.90–6.80). Among the factors investigated, only vitamin D deficiency was independently associated with development of subclinical CAD. The study did not find significant associations between CD4 count, HIV viral load, or antiretroviral treatment use and the incidence of subclinical CAD. This study appears to suggest that there is a threshold level of vitamin D (10 ng/mL) above which the effect of vitamin D on subclinical CAD is diminished. CONCLUSION: The incidence of subclinical CAD in HIV-infected African American cocaine users with low CAD risk is high, especially in those with vitamin D deficiency. Well designed randomized clinical trials are warranted to confirm the role of vitamin D deficiency in the development of CAD in HIV-infected African American cocaine users with low CAD risk

Quantitative Comparison of Techniques Used to Measure Complement-Mediated Cytotoxicity of Nucleated Cells

Abstract The cytotoxicity of nucleated cells by specific antibody and complement can be quantitated in vitro by several methods. Trypan blue exclusion, 51Cr release, inhibition of uptake of 3H-thymidine, and inhibition of colony formation are the four assays that we used to quantitatively compare the C-mediated cytotoxicity of Chinese hamster lung (CHL) cells. CHL cells were sensitized with either guinea pig or rabbit anti-CHL antisera, and exposed to guinea pig, human, or rabbit C. We found that the relative activities of the antibodies and the complements were not dependent on the method of measurement of cytotoxicity, i.e., a given pair of antiserum-complement combination had the same antiserum-complement titer, regardless of the assay used to measure cytotoxicity. However, the titers of the different antibody-complement pairs differed from each other.</jats:p