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【medical-news】更年期早期阶段，维他命K水平过低
Reuters Health
Thursday, October 5, 2006
NEW YORK (Reuters Health) - As estrogen levels drop in early menopause, vitamin K function - which is essential to maintain normal clotting -- in bone is impaired before any actual bone loss occurs, new research shows.
"Our study suggests that the generally accepted level of vitamin K in healthy women is inadequate to maintain bone health just at the onset of menopause," lead author Dr. Jane L. Lukacs, from the University of Michigan at Ann Arbor, said in a statement.
The findings, which appear in the current issue of Menopause, indicate that the percentage of osteocalcin is a marker for the bone condition of health women in early postmenopause.
Binding of osteocalcin to calcium is necessary for normal bone formation. However, only a modified form of the protein will bind to calcium, and this modification is dependent on adequate vitamin K levels. Thus, without enough vitamin K, bone formation can be impaired.
The current study involved a comparison of various hormone and vitamin K-related biomarkers in 19 cycling young women (20 to 30 years), 19 cycling older women (40 to 52 years) and in 21 women in early postmenopause (40 to 52 years).
The estradiol and vitamin levels in the cycling older women were similar to that of their younger peers, but they did have lower osteocalcin and bone mineral density at the total hip.
Bone mineral was similar at all sites in the two older groups of women, but osteocalcin was elevated in the early postmenopausal group, indicating increased bone turnover. Circulating vitamin K levels were highest in early postmenopausal subjects, yet they also had the highest percentage of unmodified osteocalcin.
The findings show that there is an association between early menopause and unusable osteocalcin, suggesting that the levels of vitamin K common in healthy women -- and presumed to be adequate to maintain normal clotting mechanisms -- are inadequate to maintain postmenopausal bone health," the researchers conclude.
SOURCE: Menopause, September/October, 2006. 认领了 文章中经常出现osterocalcin这个词，查字典（n年前的版本）也没找到，于是上网搜索，并选摘下来与大家分享一下。
Osteocalcin是骨头中最丰富的非成胶蛋白，由人体中总蛋白的几乎2%组成。它在骨代谢中起重要作用，被用作骨周转的一种临床标记，但其精确功能仍然不很清楚。由于没有已知的酶活性，这种蛋白的功能取决于其结构。现在，研究人员用X-射线晶体学方法确定了这一结构，该结构显示一个带负电的蛋白表面，这个表面将5个钙离子放在与羟磷灰石（骨头中一种重要的矿物质）中的钙离子位置互补的位置。利用这种识别机制，Osteocalcin就有可能调节羟磷灰石的晶体形态和生长。在这种复合物中，Osteocalcin的羧基端点（在骨发育中促进造骨细胞和破骨细胞的粘附）很容易被接触到。
(摘自http://www.biosino.org/news-2003/200311/03110414.htm）
Vitamin K levels may be too low in early menopause
绝经初期维生素k水平过低
Reuters Health
路透社健康
Thursday, October 5, 2006
2006年10月5日星期四
NEW YORK (Reuters Health) - As estrogen levels drop in early menopause, vitamin K function - which is essential to maintain normal clotting -- in bone is impaired before any actual bone loss occurs, new research shows.
纽约（路透社健康）—最新研究显示，随着绝经初期雌激素水平下降，在骨质开始流失前骨骼中的维生素K已减少作用。维生素k是维持正常凝血功能的重要因子。
"Our study suggests that the generally accepted level of vitamin K in healthy women is inadequate to maintain bone health just at the onset of menopause," lead author Dr. Jane L. Lukacs, from the University of Michigan at Ann Arbor, said in a statement.
来自Ann Arbor密歇根大学的主要作者Jane L. Lukacs博士表示，根据他们的研究结果，现时被公认的健康女性维生素K水平在绝经初期是不足以维持骨骼健康的。
The findings, which appear in the current issue of Menopause, indicate that the percentage of osteocalcin is a marker for the bone condition of health women in early postmenopause.
研究结果公布在最新一期《Menopause》上，提示骨钙素水平是绝经初期女性骨骼健康状况的指标。
Binding of osteocalcin to calcium is necessary for normal bone formation. However, only a modified form of the protein will bind to calcium, and this modification is dependent on adequate vitamin K levels. Thus, without enough vitamin K, bone formation can be impaired.
骨钙素与钙结合对正常骨骼结构来说是至关重要的。然而，骨钙素只有一种经改造的结构能与钙结合，这种结构的改变取决于维生素K的水平。也就是说，没有足够的维生素K，骨骼结构就可能受到破坏。
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作者:admin@医学,生命科学 2011-03-01 05:12
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