Sastry Chandan M, Whitmore Susan E, Breysse Patrick N, Morison Warwick L, Strickland Paul T
Johns Hopkins University, Bloomberg School of Public Health, Baltimore, Maryland, USA.
Dermatol Online J. 2005 Dec 1;11(3):1.
Terrestrial ultraviolet radiation (UVR) exposure, consisting of ultraviolet A (320-40 nm) and B (290-320 nm), results in the photoisomerizion of epidermal trans-urocanic acid (trans-UCA) to cis-urocanic acid (cis-UCA), a potential suppressor of local and systemic immune responses. This study examines urinary UCA isomers as biomarkers of UVA/B exposure. It presents results measuring both cis- and trans-UCA in human urine samples collected from a group of study subjects (skin types II/III) that underwent controlled UVA/B exposures similar to those administered in commercial suntanning parlors. The UCA isomers were purified from urine using C18 solid-phase extraction columns followed by high-performance liquid chromatography (HPLC) with UV absorbance (268 nm) detection. The UCA biomarker was expressed as the ratio of cis-UCA to trans-UCA (UCA ratio), or as cis-UCA concentration corrected for urine volume using creatinine (cis-UCA-Cr). The UCA ratio increased over baseline in the urine of individuals exposed to UVA/B. A single exposure to approximately 70 percent minimal erythema dose (MED) of UVR (95 % UVA/5 % UVB to approximately 90 % of skin area) produced a 4.75-fold increase in the UCA ratio (p< 0.001) relative to baseline. Repeated daily UV exposures of similar doses produced a minimal increase in UCA ratio above that of the single UV exposure. These findings indicate that UCA cis-trans ratio holds promise as a biomarker for recent solar UV exposure.
陆地紫外线辐射（UVR），由紫外线A（320 - 400nm）和紫外线B（290 - 320nm）组成，会导致表皮反式尿刊酸（trans-UCA）光异构化为顺式尿刊酸（cis-UCA），后者是局部和全身免疫反应的潜在抑制剂。本研究将尿刊酸异构体作为UVA/B暴露的生物标志物进行检测。研究呈现了从一组研究对象（II/III型皮肤）收集的人类尿液样本中顺式和反式尿刊酸的测量结果，这些研究对象接受了与商业晒黑沙龙中类似的可控UVA/B暴露。尿刊酸异构体通过C18固相萃取柱从尿液中纯化，随后采用紫外吸光度（268nm）检测的高效液相色谱法（HPLC）进行分析。尿刊酸生物标志物表示为顺式尿刊酸与反式尿刊酸的比值（尿刊酸比值），或以肌酐校正尿量后的顺式尿刊酸浓度（顺式尿刊酸 - Cr）表示。暴露于UVA/B的个体尿液中尿刊酸比值相对于基线有所增加。单次暴露于约70%最小红斑剂量（MED）的紫外线辐射（95% UVA/5% UVB至约90%的皮肤面积）会使尿刊酸比值相对于基线增加4.75倍（p < 0.001）。每日重复暴露于类似剂量的紫外线会使尿刊酸比值相较于单次紫外线暴露仅有最小程度的增加。这些发现表明，尿刊酸顺反比值有望成为近期太阳紫外线暴露的生物标志物。
