Skin Color and Self-reported Sun Exposure Scores are Associated with Serum 25-Hydroxyvitamin D Concentrations in a Multi-ethnic Population Living in South Florida.

Aims: The aim was to investigate the association between serum 25-hydroxyvitamin D [25(OH)D], skin color and sun exposure score. Study Design: Cross-sectional. Place and Duration of Study: Florida International University, Robert Stempel College of Public Health and Social Work, Department of Dietetics and Nutrition, Miami, Florida from July 2012 to October 2012. Methodology: Seventy six adults, ages 18-36 years living in South Florida participated in the study. Skin color was quantified by a IMS Smart Probe 400 scanner and 25(OH)D was measured by ELISA. A sun exposure questionnaire was used to record the weekly sun exposure scores. A food frequency questionnaire was used to record daily vitamin D intake. Results: Multiple-linear regression analysis indicated that sun exposure, forearm skin color and vitamin D intake were significant predictors of 25(OH)D (P=.004, P=.003 and P=.021 respectively). This association held after controlling for covariates (B=.371, P=.027 for forearm, B=.031, P=.005 for total sun exposure and B=.689, P=.003 for vitamin D intake). Conclusion: Skin color, sun exposure along with vitamin D intake may be used as an indirect non-invasive tools to estimate 25(OH)D levels in healthy individuals in South Florida.

Expression of Heat Shock Protein 70 in Human Skin Cells as a Photoprotective Function after UV Exposure

BACKGROUND: Human skin is exposed to various environmental stresses, such as heat, cold, and ultraviolet (UV) radiation. Heat shock proteins (HSPs) induced by temperature elevations, as a physiologic response to mediate repair mechanisms and reduce cellular damage. OBJECTIVE: The purpose of this study was to investigate the induction of HSPs in human skin cells after UV exposure. METHODS: We performed immunoblotting using a specific monoclonal antibody to the HSP70 family, one of the best-conserved stress proteins in humans, with cultured normal human keratinocytes, A431 cells, human melanocytes, SK30 cells, and human dermal fibroblasts (HDF). RESULTS: Our results indicated that high expression of HSP70 in the unstressed state was noted in epidermal cells, including normal human keratinocytes, A431 cells, human melanocytes, and SK30 cells, but epidermal cells showed no additional up-regulation of HSP70 after UV irradiation. On the other hand, HDF expressed very small amounts of HSP70 at baseline, but significantly higher amounts of HSP70 after UV exposure. CONCLUSION: These findings suggest that constitutive expression of HSP70 in epidermal cells may be an important mechanism for protection of the human epidermis from environmental stresses, such as sunlight exposure.