据最近出版的《科学》杂志报道,美国研究人员已鉴定出一种可对胆固醇肠内吸收产生重要作用的蛋白质。该研究发现可指导今后进行新的降血脂治疗。来自于美国新泽西州Kenilworth市Schering-Plough研究所的Scott W Altmann博士及其同事应...据最近出版的《科学》杂志报道,美国研究人员已鉴定出一种可对胆固醇肠内吸收产生重要作用的蛋白质。该研究发现可指导今后进行新的降血脂治疗。来自于美国新泽西州Kenilworth市Schering-Plough研究所的Scott W Altmann博士及其同事应用基因组学-生物信息学方法对胆固醇吸收过程中所涉及的主要基因进行探寻,随后鉴定出一种可靠的候选基因NPCI LI(Niemann-Pick C1 like 1)。为进一步揭示NPC1L1基因,研究人员在将一种对胆固醇肠吸收产生关键作用的蛋白进行编码后,发现NPC1L1基因在小肠内的表达有所增加。实验表明缺乏NPC1L1基因的小鼠的胆固醇吸收可减少70％左右,且胆汁酸的补充不会影响此过程。展开更多
Iron is an essential trace metal in the human diet due to its obligate role in a number of metabolic processes. In the diet, iron is present in a number of different forms, generally described as haem （from haemoglob...Iron is an essential trace metal in the human diet due to its obligate role in a number of metabolic processes. In the diet, iron is present in a number of different forms, generally described as haem （from haemoglobin and myoglobin in animal tissue） and non-haem iron （including ferric oxides and salts, ferritin and lactoferrin）. This review describes the molecular mechanisms that co-ordinate the absorption of iron from the diet and its release into the circulation. While many components of the iron transport pathway have been elucidated, a number of key issues still remain to be resolved. Future work in this area will provide a clearer picture regarding the transcellular flux of iron and its regulation by dietary and humoral factors.展开更多
The human body requires about 1-2 mg of iron per day for its normal functioning, and dietary iron is the only source for this essential metal. Since humans do not possess a mechanism for the active excretion of iron, ...The human body requires about 1-2 mg of iron per day for its normal functioning, and dietary iron is the only source for this essential metal. Since humans do not possess a mechanism for the active excretion of iron, the amount of iron in the body is determined by the amount absorbed across the proximal small intestine and, consequently, intestinal iron absorption is a highly regulated process. In recent years, the liver has emerged as a central regulator of both iron absorption and iron release from other tissues. It achieves this by secreting a peptide hormone called hepcidin that acts on the small intestinal epithelium and other cells to limit iron delivery to the plasma. Hepcidin itself is regulated in response to various systemic stimuli including variations in body iron stores, the rate of erythropoiesis, inflammation and hypoxia, the same stimuli that have been known for many years to modulate iron absorption. This review will summarize recent findings on the role played by the liver and hepcidin in the regulation of body iron absorption.展开更多
Intestinal absorption of two oxovanadium complexes, vanadyl acetylacetonate (VO(acac)2) and bis (maltolato)-oxovanadium (VO(ma)2), has been compared using Caco-2 monolayers as a model system. The two compounds are sim...Intestinal absorption of two oxovanadium complexes, vanadyl acetylacetonate (VO(acac)2) and bis (maltolato)-oxovanadium (VO(ma)2), has been compared using Caco-2 monolayers as a model system. The two compounds are similar in chemical structures but different in glucose-lowering effects. Our experimental results show that they are both transported via passive diffusion with apparent permeabilty coefficients (apical→basolateral) of (82.0 ± 6.7)× 10-7 and (14.6 ± 0.7)× 10-7 cm· s-1, respec-tively. This suggests that absorptivity of VO(acac)2 is much higher than that of VO(ma)2. This difference may be related to the metabolism of either compound, or its ligand, or both in the course of the transport. However, This difference in absorption will cause the great difference in bioavailability,which might account for better efficacy of VO(acac)2 than VO(ma)2 as the insulin-mimic agent.展开更多
文摘据最近出版的《科学》杂志报道,美国研究人员已鉴定出一种可对胆固醇肠内吸收产生重要作用的蛋白质。该研究发现可指导今后进行新的降血脂治疗。来自于美国新泽西州Kenilworth市Schering-Plough研究所的Scott W Altmann博士及其同事应用基因组学-生物信息学方法对胆固醇吸收过程中所涉及的主要基因进行探寻,随后鉴定出一种可靠的候选基因NPCI LI(Niemann-Pick C1 like 1)。为进一步揭示NPC1L1基因,研究人员在将一种对胆固醇肠吸收产生关键作用的蛋白进行编码后,发现NPC1L1基因在小肠内的表达有所增加。实验表明缺乏NPC1L1基因的小鼠的胆固醇吸收可减少70％左右,且胆汁酸的补充不会影响此过程。
文摘Iron is an essential trace metal in the human diet due to its obligate role in a number of metabolic processes. In the diet, iron is present in a number of different forms, generally described as haem （from haemoglobin and myoglobin in animal tissue） and non-haem iron （including ferric oxides and salts, ferritin and lactoferrin）. This review describes the molecular mechanisms that co-ordinate the absorption of iron from the diet and its release into the circulation. While many components of the iron transport pathway have been elucidated, a number of key issues still remain to be resolved. Future work in this area will provide a clearer picture regarding the transcellular flux of iron and its regulation by dietary and humoral factors.
文摘The human body requires about 1-2 mg of iron per day for its normal functioning, and dietary iron is the only source for this essential metal. Since humans do not possess a mechanism for the active excretion of iron, the amount of iron in the body is determined by the amount absorbed across the proximal small intestine and, consequently, intestinal iron absorption is a highly regulated process. In recent years, the liver has emerged as a central regulator of both iron absorption and iron release from other tissues. It achieves this by secreting a peptide hormone called hepcidin that acts on the small intestinal epithelium and other cells to limit iron delivery to the plasma. Hepcidin itself is regulated in response to various systemic stimuli including variations in body iron stores, the rate of erythropoiesis, inflammation and hypoxia, the same stimuli that have been known for many years to modulate iron absorption. This review will summarize recent findings on the role played by the liver and hepcidin in the regulation of body iron absorption.
基金supported by the National Natural Science Foundation of China(Grant No.20101001)
文摘Intestinal absorption of two oxovanadium complexes, vanadyl acetylacetonate (VO(acac)2) and bis (maltolato)-oxovanadium (VO(ma)2), has been compared using Caco-2 monolayers as a model system. The two compounds are similar in chemical structures but different in glucose-lowering effects. Our experimental results show that they are both transported via passive diffusion with apparent permeabilty coefficients (apical→basolateral) of (82.0 ± 6.7)× 10-7 and (14.6 ± 0.7)× 10-7 cm· s-1, respec-tively. This suggests that absorptivity of VO(acac)2 is much higher than that of VO(ma)2. This difference may be related to the metabolism of either compound, or its ligand, or both in the course of the transport. However, This difference in absorption will cause the great difference in bioavailability,which might account for better efficacy of VO(acac)2 than VO(ma)2 as the insulin-mimic agent.
