Vermeer C, Ulrich M M
Department of Biochemistry, University of Limburg, Maastricht, The Netherlands.
Adv Space Res. 1986;6(12):139-42. doi: 10.1016/0273-1177(86)90077-3.
The rapid loss of bone mass is one of the serious problems which have to be solved before long-lasting manned spaceflights may be considered. In this paper we describe investigations in which we have checked whether the bone loss in astronauts as well as in osteoporotic patients may be related to abnormalities in a recently discovered calcium-binding protein, named osteocalcin. It was observed that in all subjects of a limited number of osteoporotic patients, the amount of calcium-binding groups (Gla-residues) in the circulating osteocalcin was substantially reduced. The Gla-content could be normalized, however, by the oral administration of vitamin K (1 mg/day). We also analyzed the Gla-content of plasma-osteocalcin from 4 astronauts before and after the D-1 mission. The amount of Gla-residues was reduced by more than 50% in the post-flight samples. It seems probable, that an increased vitamin K-intake by the astronauts will correct the observed abnormality, but whether this will lead to a decrease of the microgravity-induced bone-loss remains to be seen.
骨量的快速流失是在考虑进行长期载人太空飞行之前必须尽快解决的严重问题之一。在本文中，我们描述了一些研究，在这些研究中，我们检查了宇航员以及骨质疏松患者的骨质流失是否可能与一种最近发现的名为骨钙素的钙结合蛋白的异常有关。据观察，在数量有限的骨质疏松患者的所有受试者中，循环骨钙素中钙结合基团（γ-羧基谷氨酸残基）的数量大幅减少。然而，通过口服维生素K（1毫克/天），γ-羧基谷氨酸含量可以恢复正常。我们还分析了4名宇航员在D-1任务前后血浆骨钙素的γ-羧基谷氨酸含量。飞行后样本中γ-羧基谷氨酸残基的数量减少了50%以上。宇航员增加维生素K的摄入量似乎有可能纠正观察到的异常情况，但这是否会导致微重力引起的骨质流失减少还有待观察。
