Myrick J E, Caudill S P, Robinson M K, Hubert I L
Centers for Disease Control, Public Health Service, US Department of Health and Human Services, Atlanta, GA 30341-3724.
Appl Theor Electrophor. 1993;3(3-4):137-46.
To search for new urinary protein biomarkers of cadmium toxicity, we used quantitative two-dimensional electrophoresis (2DE) and analysed urine samples from 18 male cadmium recovery plant employees whose mean age was 47 +/- 15.6 years (+/- 1 SD) and whose urine cadmium levels ranged from 0.14 microgram l-1 to 20.4 micrograms l-1 (0.06-37.1 micrograms g-1 creatinine). Image analysis of the silver-stained gels yielded intensity (concentration) values for a mean number, per person, of 825 +/- 184 urinary proteins (spots) and found 596 +/- 218 matched proteins (the same proteins in two or more gels) per person. Total urinary protein and the sum of all spot intensities were positively correlated (P = 0.0447 and P = 0.0616, respectively) with urinary cadmium (UCD), as measured by atomic absorption spectroscopy. The combined sum of the intensities of all acidic proteins with a relative molecular weight (M(r)) below 40 kDa was correlated with UCD (P = 0.0461), revealing a low M(r), acidic proteinuria as UCD increased. Multiple hypothesis testing by regression analysis of the intensities of matched proteins with UCD revealed 14 unidentified proteins that were considered candidates for biomarkers of cadmium exposure. The best two candidate proteins--those having M(r)s of less than 13.9 kDa and relative glyceraldehyde-3-phosphate dehydrogenase (G3PDHr) coordinates of -19.7 and -27.2--were excellently resolved in the 2DE gels, and their intensities increased by 323% and 857%, respectively, over the UCD range that was tested. Two other proteins with M(r)s of 23.9 kDa and 29.2 kDa and with acidic net charges were not as well resolved. Six very acidic proteins, with M(r)s ranging from 88.8 to 90.7 kDa and with intensities highly correlated with UCD, appeared to be related and were resolved as a 'charge train' (a group of related proteins, or isoforms, differing only by small changes in net charge). Four proteins appeared to increase only when the UCD concentration was above a threshold of 16 micrograms l-1.
为了寻找镉中毒新的尿蛋白生物标志物，我们采用了定量二维电泳（2DE）技术，并分析了18名男性镉回收厂员工的尿液样本。这些员工的平均年龄为47±15.6岁（±1标准差），尿镉水平在0.14微克/升至20.4微克/升之间（0.06 - 37.1微克/克肌酐）。对银染凝胶进行图像分析，得出每人平均825±184种尿蛋白（斑点）的强度（浓度）值，并发现每人有596±218种匹配蛋白（在两张或更多凝胶中出现的相同蛋白）。通过原子吸收光谱法测定，总尿蛋白和所有斑点强度总和与尿镉（UCD）呈正相关（分别为P = 0.0447和P = 0.0616）。相对分子质量（M(r)）低于40 kDa的所有酸性蛋白强度总和与UCD相关（P = 0.0461），表明随着UCD升高出现低M(r)的酸性蛋白尿。通过对匹配蛋白强度与UCD进行回归分析进行多重假设检验，发现14种未鉴定蛋白被视为镉暴露生物标志物的候选蛋白。最佳的两种候选蛋白——M(r)小于13.9 kDa，相对甘油醛 - 3 - 磷酸脱氢酶（G3PDHr）坐标分别为 - 19.7和 - 27.2——在2DE凝胶中得到了很好的分离，在测试的UCD范围内，它们的强度分别增加了323%和857%。另外两种M(r)为23.9 kDa和29.2 kDa且带酸性净电荷的蛋白分离效果不佳。六种非常酸性的蛋白，M(r)在88.8至90.7 kDa之间，其强度与UCD高度相关，似乎相互关联，并作为一个“电荷序列”（一组相关蛋白或同工型，仅在净电荷上有微小变化）被分离出来。四种蛋白似乎仅在UCD浓度高于16微克/升的阈值时才增加。
