Towler M R, Wren A, Rushe N, Saunders J, Cummins N M, Jakeman P M
Materials and Surface Science Institute, University of Limerick, National Technological Park, Limerick, Ireland.
J Mater Sci Mater Med. 2007 May;18(5):759-63. doi: 10.1007/s10856-006-0018-9. Epub 2006 Nov 30.
Dual X-ray absorptiometry (DEXA) is the current gold standard for the diagnosis of osteoporosis. However, patients can suffer osteoporotic fractures despite normal bone mineral density, partly because of unmeasured influences of both the protein and mineral phases of bone that are affected in osteoporosis. There is currently no clinically applicable method of evaluating the health of the protein phase. The proteins in human nail (keratin) and bone (collagen) require sulphation and disulphide bond (S-S) formation for structural integrity and disorders of either sulphur metabolism or cystathione beta-synthase can lead to structural abnormalities in these tissues. Raman protein spectra provide a method of non-invasive measurement of the degree of sulphation of structurally related proteins that may be indicative of bone health. Raman spectroscopy was used to evaluate the disulphide (S-S) content of fingernails. The nail samples came from from 169 women (84 pre- and 85 post-menopausal), of which 39 had a history of osteoporotic fracture. BMD was measured by DXA at the spine. Analyses included parametric and non-parametric tests, dependent on the distribution of the test variable. Mean disulphide content of the nail reduced with age and was slightly higher in pre-, compared to post-menopausal women (P = 0.187). Significantly lower disulphide content was observed in nails obtained from subjects with a history of fracture (P = 0.025). When either disulphide content or BMD was used as a predictor, the odds ratio of these two measures were found to be comparable predictors for fracture status. This suggests that measurements of change in the protein phase of structural proteins such as keratin in the human nail may be correlated with clinically relevant changes in bone proteins that are important in fracture risk.
双能X线吸收法（DEXA）是目前诊断骨质疏松症的金标准。然而，尽管骨矿物质密度正常，患者仍可能发生骨质疏松性骨折，部分原因是骨质疏松症会影响骨骼的蛋白质和矿物质阶段，但这些影响难以测量。目前尚无临床适用的评估蛋白质阶段健康状况的方法。人指甲（角蛋白）和骨骼（胶原蛋白）中的蛋白质需要硫酸化和二硫键（S-S）形成才能保持结构完整性，硫代谢或胱硫醚β-合酶的紊乱会导致这些组织出现结构异常。拉曼蛋白质光谱提供了一种非侵入性测量结构相关蛋白质硫酸化程度的方法，这可能指示骨骼健康状况。拉曼光谱用于评估指甲的二硫键（S-S）含量。指甲样本来自169名女性（84名绝经前和85名绝经后），其中39名有骨质疏松性骨折病史。通过DEXA测量脊柱的骨密度。分析包括参数检验和非参数检验，具体取决于测试变量的分布。指甲的平均二硫键含量随年龄降低，绝经前女性略高于绝经后女性（P = 0.187）。在有骨折病史的受试者的指甲中观察到二硫键含量显著降低（P = 0.025）。当将二硫键含量或骨密度用作预测指标时，发现这两种测量方法的优势比是骨折状态的可比预测指标。这表明，测量人指甲中角蛋白等结构蛋白的蛋白质阶段变化可能与骨骼蛋白质的临床相关变化有关，而骨骼蛋白质变化对骨折风险很重要。
