国产精品视频一区二区三区四,亚洲av美洲av综合av,99国内精品久久久久久久,欧美电影一区二区三区电影

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.