Abstract：
A novel simplified method is presented for the estimation of the metabolism of plasma proteins (albumin, fibrinogen, α, β and γ-globulin, glycoprotein) with regard to the whole body protein metabolism in a young male volunteer (22 years, 81 kg body mass). This method is based on multiple oral administration of [15N]glycine followed by measurement of 15N in plasma proteins, total free amino acids, urea and excreted urinary N. The fractional synthesis rate of albumin was estimated to 6.8 % d-1 based on amino acids and 3.3 % d-1 based on urea, respectively. The fractional synthesis rate of the other plasma proteins ranged from 4.3 % d-1 (γ-globulin) to 26.4 % d-1 (α-globulin, fibrinogen). We conclude that the simplified approach using [15N]glycine provides results which are similar to results based on the simultaneously applied 131I-human serum albumin technique as \'gold standard\' and to those reported in literature. The compartmental analysis considering comprehensive tracer kinetic data ensures reliable data treatment and enables statistical evaluation. The analytical effort is minimal because the 15N enrichment of plasma protein after chemical digestion may be directly used. Therefore, the novel stable isotope 15N method is suitable for studies in clinical and nutritional research and practice.
摘要：
提出了一种新的简化方法来估计血浆蛋白（白蛋白，纤维蛋白原，α,β和γ-球蛋白，糖蛋白）关于年轻男性志愿者（22岁，81公斤体重)。该方法基于多次口服[15N]甘氨酸，然后测量血浆蛋白中的15N，总游离氨基酸，尿素和排泄的尿N。基于氨基酸，白蛋白的分数合成率为6.8％d-1，基于尿素，白蛋白的分数合成率为3.3％d-1，分别。其他血浆蛋白的合成率范围为4.3％d-1（γ-球蛋白）至26.4％d-1（α-球蛋白，纤维蛋白原）。我们得出的结论是，使用[15N]甘氨酸的简化方法提供的结果与基于同时应用131I-人血清白蛋白技术作为“金标准”的结果以及文献报道的结果相似。考虑全面示踪剂动力学数据的隔室分析确保了可靠的数据处理并实现了统计评估。分析工作是最小的,因为可以直接使用化学消化后血浆蛋白的15N富集。因此,新的稳定同位素15N方法适用于临床和营养研究与实践。
