日韩av大片在线观看欧美成人不卡|午夜先锋看片|中国女人18毛片水多|免费xx高潮喷水|国产大片美女av|丰满老熟妇好大bbbbbbbbbbb|人妻上司四区|japanese人妻少妇乱中文|少妇做爰喷水高潮受不了|美女人妻被颜射的视频,亚洲国产精品久久艾草一,俄罗斯6一一11萝裸体自慰,午夜三级理论在线观看无码

N-terminal propeptide of type 1 precollagen （P1NP） is one of the markers of bone formation. Osteoblasts contain a large amount of typeⅠprecollagen. During bone formation, typeⅠprocollagen is secreted outside the cell and cleaved by specific protease to form typeⅠcollagen N-terminal procollagen of type 1 precollagen （P1NP） and C-terminal procollagen of type 1 precollagen, PICP） and typeⅠcollagen 3 fragments. Type I collagen is assembled in osteoid where inorganic minerals （calcium and phosphorus） are deposited to form hydroxyapatite （osteoid mineralization）. P1NP and PICP enter the blood and urine as metabolites, so the detection of P1NP and PICP can reflect the level of bone formation. As the research evidence of P1NP reflecting bone formation is richer than PICP, P1NP is a better marker of bone formation. P1NP has good specificity, little influence on circadian rhythm and feeding, and is stable at room temperature. At present, P1NP is generally recommended as the preferred bone formation marker.