This study examined the effect of insulin on the expression of very low density lipoprotein receptor (VLDLR) subtypes of SGC7901 cells and discussed its biological implication.In vitro, moderately or poorly-differenti...This study examined the effect of insulin on the expression of very low density lipoprotein receptor (VLDLR) subtypes of SGC7901 cells and discussed its biological implication.In vitro, moderately or poorly-differentiated human gastric adenocarcinoma cell line SGC7901 was incubated with insulin for different lengths of time, and then the expression of protein and RNA level in VLDLR subtypes were detected by Western blotting and real-time PCR, respectively.The results showed that, at certain time interval, insulin could down-regulate expression of type Ⅰ VLDLR and up-regulate the expression of type Ⅱ VLDLR in SGC7901 cells, at both protein and RNA level.We are led to conclude that insulin serves as a regulator in maintaining the balance between glucose and lipid metabolism in vivo, possibly through its effect on the differential expression of VLDLR subtypes.展开更多
AIM: This study was undertaken to evaluate the hepatic effects of silybum marianum on non alcoholic fatty liver disease (NAFLD). METHODS: In 72 patients affected by NAFLD, main metabolic, hepatic and anti-inflammatory...AIM: This study was undertaken to evaluate the hepatic effects of silybum marianum on non alcoholic fatty liver disease (NAFLD). METHODS: In 72 patients affected by NAFLD, main metabolic, hepatic and anti-inflammatory parameters were assayed after 3 mo of a restricted diet and before silymarin treatment (twice a day orally). The brightness of liver echography texture (hepatorenal ratio brightness) was also defined at same time. These evaluations were repeated after 6 mo of treatment. RESULTS: Serum levels of some metabolic and anti-inflammatory data nonsignificantly lowered after 6 mo of silymarin. On the contrary, Steato test, alanine aminotransferase (ALT), aspartate aminotransferase (AST) and gamma-glutamyl transpeptidase were significantly (P < 0.001) reduced. Instead, the AST/ALT ratio unchanged. Finally, the hepatorenal brightness ratio, as an index of hepatic steatosis, significantly (P < 0.05) dropped. CONCLUSION: The obtained results indicate that silymarin appears to be effective to reduce the biochemical, inflammatory and ultrasonic indices of hepatic steatosis. Some parameters indicative of early stage of atherosclerosis were also lowered.展开更多
Cholesterol plays several structural and metabolic roles that are vital for human biology. It spreads along the entire plasma membrane of the cell, modulating fluidity and concentrating in specialized sphingolipid-ric...Cholesterol plays several structural and metabolic roles that are vital for human biology. It spreads along the entire plasma membrane of the cell, modulating fluidity and concentrating in specialized sphingolipid-rich domains called rafts and caveolae. Cholesterol is also a substrate for steroid hormones. However, too much cholesterol can lead to pathological pictures such as atherosclerosis, which is a consequence of the accumu- lation of cholesterol into the cells of the artery wall. The liver is considered to be the metabolic power station of mammalians, where cholesterol homeostasis relies on an intricate network of cellular processes whose deregulations can lead to several life-threatening pathologies, such as familial and age-related hypercholesterolemia. Cholesterol homeostasis maintenance is carried out by: biosynthesis, via 3-hydroxy-3-methylglutaryl coenzyme A reductase (HMGR) activity; uptake, through low density lipoprotein receptors (LDLr); lipoprotein release in the blood; storage by esterification; and degradation and conversion into bile acids. Both HMGR and LDLr are transcribed as a function of cellular sterol amount by a family of transcription factors called sterol regulatory element binding proteins that are responsible for the maintenance of cholesterol homeostasis through an intricate mechanism of regulation. Cholesterol obtained by hepatic de novo synthesis can be esterified and incorporated into apolipoprotein B-100-containing very low density lipoproteins, which are then secreted into the bloodstream for transport to peripheral tissues. Moreover, dietary cholesterol is transferred from the intestine to the liver by high density lipoproteins (HDLs); all HDL particles are internalized in the liver, interacting with the hepatic scavenger receptor (SR-B1). Here we provide an updated overview of liver cholesterol metabolism regulation and deregulation and the causes of cholesterol metabolism-related diseases. Moreover, current pharmacological treatment and novel hypocho-lesterolemic strategies will also be introduced.展开更多
The role of very low density lipoprotein receptor (LVLDR) in the process of foam cell formation was investigated. After the primary cultured mouse peritoneal macrophages were incubated with VLDL, β VLDL or low densi...The role of very low density lipoprotein receptor (LVLDR) in the process of foam cell formation was investigated. After the primary cultured mouse peritoneal macrophages were incubated with VLDL, β VLDL or low density lipoprotein (LDL), respectively for 24 h and 48 h, foam cells formation was identified by oil red O staining and cellular contents of triglyceride (TG) and total cholesterol (TC) were determined. The mRNA levels of LDLR, LDLR related protein (LRP) and VLDLR were detected by semi quantitative RT PCR. The results demonstrated that VLDL, β VLDL and LDL could increase the contents of TG and TC in macrophages. Cells treated with VLDL or β VLDL showed markedly increased expression of VLDLR and decreased expression of LDLR, whereas LRP was up regulated slightly. For identifying the effect of VLDL receptor on cellular lipid accumulation, ldl A7 VR cells, which expresses VLDLR and trace amount of LRP without functional LDLR, was used to incubate with lipoproteins for further examination. The results elucidated that the uptake of triglyceride rich lipoprotein mediated by VLDLR plays an important role in accumulation of lipid and the formation of foam cells.展开更多
The aim of this review is to enlighten the critical roles that the liver plays in cholesterol metabolism. Liver transplantation can serve as gene therapy or a source of gene transmission in certain conditions that aff...The aim of this review is to enlighten the critical roles that the liver plays in cholesterol metabolism. Liver transplantation can serve as gene therapy or a source of gene transmission in certain conditions that affect cholesterol metabolism, such as low-density-lipoprotein(LDL) receptor gene mutations that are associated with familial hypercholesterolemia. On the other hand, cholestatic liver disease often alters cholesterol metabolism. Cholestasis can lead to formation of lipoprotein X(Lp-X), which is frequently mistaken for LDL on routine clinical tests. In contrast to LDL, Lp-X is non-atherogenic, and failure to differentiate between the two can interfere with cardiovascular risk assessment, potentially leading to prescription of futile lipid-lowering therapy. Statins do not effectively lower Lp-X levels, and cholestasis may lead to accumulation of toxic levels of statins. Moreover, severe cholestasis results in poor micellar formation, which reduces cholesterol absorption, potentially impairing the cholesterol-lowering effect of ezetimibe. Apolipoprotein B-100 measurement can help distinguish between atherogenic and non-atherogenic hypercholesterolemia. Furthermore, routine serum cholesterol measurements alone cannot reflect cholesterol absorption and synthesis. Measurements of serum non-cholesterol sterol biomarkers- such as cholesterol precursor sterols, plant sterols, and cholestanol- may help with the comprehensive assessment of cholesterol metabolism. An adequate cholesterol supply is essential for liver-regenerative capacity. Low preoperative and perioperative serum cholesterol levels seem to predict mortality in liver cirrhosis and after liver transplantation. Thus, accurate lipid profile evaluation is highly important in liver disease and after liver transplantation.展开更多
Objective To investigate the effect of insuline-like growth factor-Ⅰ （IGF-Ⅰ） on progesterone genesis and regulation. Methods Cytotrophoblast cells were collected by trypsin-collagenase digestion and percoll gradie...Objective To investigate the effect of insuline-like growth factor-Ⅰ （IGF-Ⅰ） on progesterone genesis and regulation. Methods Cytotrophoblast cells were collected by trypsin-collagenase digestion and percoll gradient centrifugation for primary culture. After stimulated with different concentrations（100 μg/ml, 10 μg/ml, 1 μg/ml, 0.1 μg/ml） of IGF-Ⅰ at the same time and with different duration（12 h,24 h,48 h, 72 h） of IGF-Ⅰ with the same concentration, progesterone levels in the media were measured by radioimmunoassay. Simultaneously, semiquantitative reverse transcriptase polymerase chain reaction （RT-PCR） was applied to determine the expression of low density lipoprotein receptor （LDLR） mRNA. Results Progesterone levels correlated positively with IGF-Ⅰ along with the IGF-Ⅰ concentration increasing, progesterone level began to increase at 12 h, and reached the climax at 48 h when cultured with 100 μg/L IGF-Ⅰ. The expression of LDLR mRNA was detectable in every group and accordant with variation of progesterone level. Conclusion Progesterone secretion has time- and dose-dependent effect on IGF-Ⅰ, and IGF-1 can up-regulate the expression of LDLR mRNA. IGF-Ⅰ may play an important role in promoting secretion of progesterone in trophoblast cells.展开更多
基金supported by grants from National Natural Sciences Foundation of China (No.39970307)Hubei Provincial Natural Sciences Foundation of China (No.2005ABA092)
文摘This study examined the effect of insulin on the expression of very low density lipoprotein receptor (VLDLR) subtypes of SGC7901 cells and discussed its biological implication.In vitro, moderately or poorly-differentiated human gastric adenocarcinoma cell line SGC7901 was incubated with insulin for different lengths of time, and then the expression of protein and RNA level in VLDLR subtypes were detected by Western blotting and real-time PCR, respectively.The results showed that, at certain time interval, insulin could down-regulate expression of type Ⅰ VLDLR and up-regulate the expression of type Ⅱ VLDLR in SGC7901 cells, at both protein and RNA level.We are led to conclude that insulin serves as a regulator in maintaining the balance between glucose and lipid metabolism in vivo, possibly through its effect on the differential expression of VLDLR subtypes.
文摘AIM: This study was undertaken to evaluate the hepatic effects of silybum marianum on non alcoholic fatty liver disease (NAFLD). METHODS: In 72 patients affected by NAFLD, main metabolic, hepatic and anti-inflammatory parameters were assayed after 3 mo of a restricted diet and before silymarin treatment (twice a day orally). The brightness of liver echography texture (hepatorenal ratio brightness) was also defined at same time. These evaluations were repeated after 6 mo of treatment. RESULTS: Serum levels of some metabolic and anti-inflammatory data nonsignificantly lowered after 6 mo of silymarin. On the contrary, Steato test, alanine aminotransferase (ALT), aspartate aminotransferase (AST) and gamma-glutamyl transpeptidase were significantly (P < 0.001) reduced. Instead, the AST/ALT ratio unchanged. Finally, the hepatorenal brightness ratio, as an index of hepatic steatosis, significantly (P < 0.05) dropped. CONCLUSION: The obtained results indicate that silymarin appears to be effective to reduce the biochemical, inflammatory and ultrasonic indices of hepatic steatosis. Some parameters indicative of early stage of atherosclerosis were also lowered.
文摘Cholesterol plays several structural and metabolic roles that are vital for human biology. It spreads along the entire plasma membrane of the cell, modulating fluidity and concentrating in specialized sphingolipid-rich domains called rafts and caveolae. Cholesterol is also a substrate for steroid hormones. However, too much cholesterol can lead to pathological pictures such as atherosclerosis, which is a consequence of the accumu- lation of cholesterol into the cells of the artery wall. The liver is considered to be the metabolic power station of mammalians, where cholesterol homeostasis relies on an intricate network of cellular processes whose deregulations can lead to several life-threatening pathologies, such as familial and age-related hypercholesterolemia. Cholesterol homeostasis maintenance is carried out by: biosynthesis, via 3-hydroxy-3-methylglutaryl coenzyme A reductase (HMGR) activity; uptake, through low density lipoprotein receptors (LDLr); lipoprotein release in the blood; storage by esterification; and degradation and conversion into bile acids. Both HMGR and LDLr are transcribed as a function of cellular sterol amount by a family of transcription factors called sterol regulatory element binding proteins that are responsible for the maintenance of cholesterol homeostasis through an intricate mechanism of regulation. Cholesterol obtained by hepatic de novo synthesis can be esterified and incorporated into apolipoprotein B-100-containing very low density lipoproteins, which are then secreted into the bloodstream for transport to peripheral tissues. Moreover, dietary cholesterol is transferred from the intestine to the liver by high density lipoproteins (HDLs); all HDL particles are internalized in the liver, interacting with the hepatic scavenger receptor (SR-B1). Here we provide an updated overview of liver cholesterol metabolism regulation and deregulation and the causes of cholesterol metabolism-related diseases. Moreover, current pharmacological treatment and novel hypocho-lesterolemic strategies will also be introduced.
文摘The role of very low density lipoprotein receptor (LVLDR) in the process of foam cell formation was investigated. After the primary cultured mouse peritoneal macrophages were incubated with VLDL, β VLDL or low density lipoprotein (LDL), respectively for 24 h and 48 h, foam cells formation was identified by oil red O staining and cellular contents of triglyceride (TG) and total cholesterol (TC) were determined. The mRNA levels of LDLR, LDLR related protein (LRP) and VLDLR were detected by semi quantitative RT PCR. The results demonstrated that VLDL, β VLDL and LDL could increase the contents of TG and TC in macrophages. Cells treated with VLDL or β VLDL showed markedly increased expression of VLDLR and decreased expression of LDLR, whereas LRP was up regulated slightly. For identifying the effect of VLDL receptor on cellular lipid accumulation, ldl A7 VR cells, which expresses VLDLR and trace amount of LRP without functional LDLR, was used to incubate with lipoproteins for further examination. The results elucidated that the uptake of triglyceride rich lipoprotein mediated by VLDLR plays an important role in accumulation of lipid and the formation of foam cells.
文摘The aim of this review is to enlighten the critical roles that the liver plays in cholesterol metabolism. Liver transplantation can serve as gene therapy or a source of gene transmission in certain conditions that affect cholesterol metabolism, such as low-density-lipoprotein(LDL) receptor gene mutations that are associated with familial hypercholesterolemia. On the other hand, cholestatic liver disease often alters cholesterol metabolism. Cholestasis can lead to formation of lipoprotein X(Lp-X), which is frequently mistaken for LDL on routine clinical tests. In contrast to LDL, Lp-X is non-atherogenic, and failure to differentiate between the two can interfere with cardiovascular risk assessment, potentially leading to prescription of futile lipid-lowering therapy. Statins do not effectively lower Lp-X levels, and cholestasis may lead to accumulation of toxic levels of statins. Moreover, severe cholestasis results in poor micellar formation, which reduces cholesterol absorption, potentially impairing the cholesterol-lowering effect of ezetimibe. Apolipoprotein B-100 measurement can help distinguish between atherogenic and non-atherogenic hypercholesterolemia. Furthermore, routine serum cholesterol measurements alone cannot reflect cholesterol absorption and synthesis. Measurements of serum non-cholesterol sterol biomarkers- such as cholesterol precursor sterols, plant sterols, and cholestanol- may help with the comprehensive assessment of cholesterol metabolism. An adequate cholesterol supply is essential for liver-regenerative capacity. Low preoperative and perioperative serum cholesterol levels seem to predict mortality in liver cirrhosis and after liver transplantation. Thus, accurate lipid profile evaluation is highly important in liver disease and after liver transplantation.
基金This study was supported by the Foundation of Scientific and Technological Development of Shanghai (02DZ19115) and Chinese Post-doctor Fund
文摘Objective To investigate the effect of insuline-like growth factor-Ⅰ （IGF-Ⅰ） on progesterone genesis and regulation. Methods Cytotrophoblast cells were collected by trypsin-collagenase digestion and percoll gradient centrifugation for primary culture. After stimulated with different concentrations（100 μg/ml, 10 μg/ml, 1 μg/ml, 0.1 μg/ml） of IGF-Ⅰ at the same time and with different duration（12 h,24 h,48 h, 72 h） of IGF-Ⅰ with the same concentration, progesterone levels in the media were measured by radioimmunoassay. Simultaneously, semiquantitative reverse transcriptase polymerase chain reaction （RT-PCR） was applied to determine the expression of low density lipoprotein receptor （LDLR） mRNA. Results Progesterone levels correlated positively with IGF-Ⅰ along with the IGF-Ⅰ concentration increasing, progesterone level began to increase at 12 h, and reached the climax at 48 h when cultured with 100 μg/L IGF-Ⅰ. The expression of LDLR mRNA was detectable in every group and accordant with variation of progesterone level. Conclusion Progesterone secretion has time- and dose-dependent effect on IGF-Ⅰ, and IGF-1 can up-regulate the expression of LDLR mRNA. IGF-Ⅰ may play an important role in promoting secretion of progesterone in trophoblast cells.
