Intestinal Ca2+ absorption is a crucial physiological process for maintaining bone mineralization and Ca2+ homeostasis. It occurs through the transcellular and paracellular pathways. The first route comprises 3steps: ...Intestinal Ca2+ absorption is a crucial physiological process for maintaining bone mineralization and Ca2+ homeostasis. It occurs through the transcellular and paracellular pathways. The first route comprises 3steps: the entrance of Ca2+ across the brush border membranes(BBM) of enterocytes through epithelial Ca2+ channels TRPV6, TRPV5, and Cav1.3; Ca2+ movement from the BBM to the basolateral membranes by binding proteins with high Ca2+ affinity(such as CB9k); and Ca2+ extrusion into the blood. Plasma membrane Ca2+ ATPase(PMCA1b) and sodium calcium exchanger(NCX1) are mainly involved in the exit of Ca2+ from enterocytes. A novel molecule, the 4.1R protein, seems to be a partner of PMCA1 b, since both molecules colocalize and interact. The paracellular pathway consists of Ca2+ transport through transmembrane proteins of tight junction structures, such as claudins 2, 12, and 15. There is evidence of crosstalk between the transcellular and paracellular pathways in intestinal Ca2+ transport. When intestinal oxidative stress is triggered, there is a decrease in the expression of several molecules of both pathways that inhibit intestinal Ca2+ absorption. Normalization of redox status in the intestine with drugs such as quercetin, ursodeoxycholic acid, or melatonin return intestinal Ca2+ transport to control values. Calcitriol [1,25(OH)2D3] is the major controlling hormone of intestinal Ca2+ transport. It increases the gene and protein expression of most of the molecules involved in both pathways. PTH, thyroid hormones, estrogens, p ro l a c t i n, g ro w t h h o r m o n e, a n d g l u c o c o r t i c o i d s apparently also regulate Ca2+ transport by direct action, indirect mechanism mediated by the increase of renal 1,25(OH)2D3 production, or both. Different physiological conditions, such as growth, pregnancy, lactation, and aging, adjust intestinal Ca2+ absorption according to Ca2+ demands. Better knowledge of the molecular details of intestinal Ca2+ absorption could lead to the development of nutritional and medical strategies for optimizing the efficiency of intestinal Ca2+ absorption and preventing osteoporosis and other pathologies related to Ca2+ metabolism.展开更多
目的:比较不同类型骨质疏松症患者血清中骨代谢标志物的水平差异以及骨代谢标志物之间的相关性。方法:采用免疫电化学发光法检测2016年6月至2017年12月在我院确诊为骨质疏松无骨折患者134例,骨质疏松伴骨折患者118例,甲状旁腺功能亢进...目的:比较不同类型骨质疏松症患者血清中骨代谢标志物的水平差异以及骨代谢标志物之间的相关性。方法:采用免疫电化学发光法检测2016年6月至2017年12月在我院确诊为骨质疏松无骨折患者134例,骨质疏松伴骨折患者118例,甲状旁腺功能亢进合并骨质疏松症患者126例和我院体检中心健康人群116例受试对象血清中I型前胶原氨基端延长肽(Procollagen type I N-terminal peptide,P1NP)、骨钙素(N-terminal midfragment of osteocalcin,N-MID)、I型胶原羧基端肽β特殊序列(βisomer of the C-terminal telopeptide of type I collagen,β-CrossLaps)、血清25羟维生素D(25-hydroxyvitamin D,25-OH(vit)D)、甲状旁腺素(Parathyroid hormone,PTH)的水平。结果:三种不同类型骨质疏松症患者血清中PINP及β-Crosslaps的水平均明显高于健康对照组(P<0.05),其中PTH增高性骨质疏松组增加最为明显;各组受试对象中女性患者血清25-OH(vit)D水平均明显低于同组男性患者(P<0.05),PINP、β-CrossLaps、N-MID的水平与同组男性患者相比均呈增加的趋势;Pearson相关性分析结果显示PTH与25-OH(vit)D呈负相关,PINP与N-MID,β-CrossLaps与N-MID,PINP与β-CrossLaps均呈正相关(P<0.05)。结论:分析骨代谢标志在不同类型骨质疏松症患者血清中的水平差异及骨代谢标志物之间的相关性,可合理评价骨组织的转换率,有利于早期发现骨代谢紊乱,能更有效地预防骨质疏松症的发生与发展,减少骨质疏松合并骨折的发生率。展开更多
文摘Intestinal Ca2+ absorption is a crucial physiological process for maintaining bone mineralization and Ca2+ homeostasis. It occurs through the transcellular and paracellular pathways. The first route comprises 3steps: the entrance of Ca2+ across the brush border membranes(BBM) of enterocytes through epithelial Ca2+ channels TRPV6, TRPV5, and Cav1.3; Ca2+ movement from the BBM to the basolateral membranes by binding proteins with high Ca2+ affinity(such as CB9k); and Ca2+ extrusion into the blood. Plasma membrane Ca2+ ATPase(PMCA1b) and sodium calcium exchanger(NCX1) are mainly involved in the exit of Ca2+ from enterocytes. A novel molecule, the 4.1R protein, seems to be a partner of PMCA1 b, since both molecules colocalize and interact. The paracellular pathway consists of Ca2+ transport through transmembrane proteins of tight junction structures, such as claudins 2, 12, and 15. There is evidence of crosstalk between the transcellular and paracellular pathways in intestinal Ca2+ transport. When intestinal oxidative stress is triggered, there is a decrease in the expression of several molecules of both pathways that inhibit intestinal Ca2+ absorption. Normalization of redox status in the intestine with drugs such as quercetin, ursodeoxycholic acid, or melatonin return intestinal Ca2+ transport to control values. Calcitriol [1,25(OH)2D3] is the major controlling hormone of intestinal Ca2+ transport. It increases the gene and protein expression of most of the molecules involved in both pathways. PTH, thyroid hormones, estrogens, p ro l a c t i n, g ro w t h h o r m o n e, a n d g l u c o c o r t i c o i d s apparently also regulate Ca2+ transport by direct action, indirect mechanism mediated by the increase of renal 1,25(OH)2D3 production, or both. Different physiological conditions, such as growth, pregnancy, lactation, and aging, adjust intestinal Ca2+ absorption according to Ca2+ demands. Better knowledge of the molecular details of intestinal Ca2+ absorption could lead to the development of nutritional and medical strategies for optimizing the efficiency of intestinal Ca2+ absorption and preventing osteoporosis and other pathologies related to Ca2+ metabolism.
文摘目的:比较不同类型骨质疏松症患者血清中骨代谢标志物的水平差异以及骨代谢标志物之间的相关性。方法:采用免疫电化学发光法检测2016年6月至2017年12月在我院确诊为骨质疏松无骨折患者134例,骨质疏松伴骨折患者118例,甲状旁腺功能亢进合并骨质疏松症患者126例和我院体检中心健康人群116例受试对象血清中I型前胶原氨基端延长肽(Procollagen type I N-terminal peptide,P1NP)、骨钙素(N-terminal midfragment of osteocalcin,N-MID)、I型胶原羧基端肽β特殊序列(βisomer of the C-terminal telopeptide of type I collagen,β-CrossLaps)、血清25羟维生素D(25-hydroxyvitamin D,25-OH(vit)D)、甲状旁腺素(Parathyroid hormone,PTH)的水平。结果:三种不同类型骨质疏松症患者血清中PINP及β-Crosslaps的水平均明显高于健康对照组(P<0.05),其中PTH增高性骨质疏松组增加最为明显;各组受试对象中女性患者血清25-OH(vit)D水平均明显低于同组男性患者(P<0.05),PINP、β-CrossLaps、N-MID的水平与同组男性患者相比均呈增加的趋势;Pearson相关性分析结果显示PTH与25-OH(vit)D呈负相关,PINP与N-MID,β-CrossLaps与N-MID,PINP与β-CrossLaps均呈正相关(P<0.05)。结论:分析骨代谢标志在不同类型骨质疏松症患者血清中的水平差异及骨代谢标志物之间的相关性,可合理评价骨组织的转换率,有利于早期发现骨代谢紊乱,能更有效地预防骨质疏松症的发生与发展,减少骨质疏松合并骨折的发生率。
