Lipoprotein lipase (LPL) is known to be attached to the luminal surface of vascular endothelial cells in a complex with membrane-bound heparan sulfate, and released into blood stream by heparin. LPL that catalyzes hydrolysis of triglyceride (TGL) on chylomicron and VLDL into two fatty acids and monoacylglycerol, is also implicated to participate in an enhancement of cholesterol uptake by arterial endothelial cells in vitro. But little is known about the LPL-mediated cholesterol uptake in physiological state. In this study, changes in blood lipid composition and levels of lipoproteins were determined after the injection of heparin in human. The level of LPL in plasma was increased from 0 to 11 mU/ml within 30-40 min post-heparin administration and decreased to the basal level within 2 h. The level of TGL in plasma decreased from 70 mg/dl to 20 mg/dl within 1 h and gradually increased to 80 mg/dl within 4 h. However the level of total cholesterol in plasma remained at 140 mg/dl during an experimental period of 4 h. Analysis of Lipoproteins in plasma by NaBr density gradient ultracentrifugation showed that the level of VLDL decreased from 50 mg/dl to 10 mg/dl within 1-2 h and returned to normal plasm level at 4 h. However there were no significant changes in the level of LDL and HDL. These results suggest that, at least, in normo-lipidemic subjects, increased free plasm LPL acts primarily on VLDL and failed to show any significant uptake of cholesterol-rich lipoproteins in human.
Adult ; Cholesterol/blood ; Heparin/pharmacology* ; Heparin/administration & dosage ; Human ; Immunoblotting ; Lipoprotein Lipase/blood* ; Lipoproteins/blood* ; Lipoproteins, HDL/blood ; Lipoproteins, LDL/blood ; Lipoproteins, VLDL/blood ; Triglycerides/blood

BACKGROUND: In 2001, the third report the National Cholesterol Education Program (NCEP) has concluded that LDL cholesterol levels should be a major goal for preventing coronary artery disease and atherosclerotic events. Those in the higher risk groups should then have lipoprotein analysis to determine LDL cholesterol levels. LDL cholesterol has traditionally been estimated by the Friedwald forrmula : LDL-C=total cholesterol-[high density lipoprotein cholesterol (HDL-C)+trigryceride/5]. However, when trigryceride level is >400 mg/dL, this formula is inaccurate. Therefore, We have compared the direct LDL cholesterol immunoseparation method with Friedwald formula from both normotriglyceridemic (triglyceride400 mg/dL). METHODS: The direct LDL cholesterol immunoseparation method was performed on 53 sera with triglyceride levels 61 to 1,684 mg/dL (classified as400 mg/dL : 31). Total cholesterol was measured enzymatic colorimetry. HDL cholesterol was measured in the supernatant after precipitating LDL by HDL cholesterol precipitating reagent containing dextran sulfate and magnesium chloride for serum. Direct LDL cholesterol was measured by immunoseparation method (Sigma Diagnostics, St Louis, Mo) that is based on selective absorption of HDL cholesterol and VLDL cholesterol by polystylene beads coated with goat polyclonal antibodies to human apolipoproteins. The cholesterol was measured by an enzamatic method on Hitachi 747. The linear regression and paird t-test were performed to evaluate the differences of data from Immunoseparation method and Friedwald formula. RESULTS: In triglyceridecholesterol value obtained by the direct LDL-C assay on the 22 fresh sera studied was not significantly different from that of Friedwald formula (103+/-45.1; 105+/-42.9 mg/dL). Almost identical linear regression equations for direct LDL cholesterol assay(y) and Friedwald formula(x) were obtained for samples with triglyceride400 mg/dL, the LDL cholesterol value obtained by the direct LDL-C assay on the 31 frozen sera studied was significantly different from that of Friedwald formula (103+/-38.4; 50.4+/-56.2 mg/dL). Therefore, Friedwald formula is unreliable in triglyceride>400 mg/dL. CONCLUSION: Guidelines for treatment decisions, including diet and drug initiation, and therapeutic goals for high risk groups are based entirely on the LDL cholesterol level. At triglyceride levels >400 mg/dL, Friedwald fomula is inaccurate. Immunoseparation method is more rapid, higher specific, precise and helps monitor LDL lowering drugs and diets in triglyceride level>400 mg/dL.
Absorption ; Antibodies ; Apolipoproteins ; Cholesterol* ; Cholesterol, HDL ; Cholesterol, LDL ; Cholesterol, VLDL ; Colorimetry ; Coronary Artery Disease ; Dextran Sulfate ; Diet ; Education ; Goats ; Humans ; Linear Models ; Lipoproteins* ; Magnesium Chloride ; Triglycerides

We report a case of type III hyperlipoproteinemia associated with xanthoma eruptivum. Xanthoma tuberosum, and xanthoma striatum palmare whose clinical symptoms have been improved by the treatment of gemfibrozil. A 31-year-old male patient visited our clinic for evaluation of multiple yellowish nodules on the elbows, multiple yellowish plaques on the buttocks and linear yellowish plaques along with the palmar creases on both palms. The blood chemistry showed an elevation of cholesterol and triglyceride. Lipoprotein electrophoresis showed broad betazone and plasma standing test showed turbid plasma. Lipoprotein ultracentrifugation showed that the ratio of VLDL cholesterol and plasma triglyceride was 0.38. According to the above findings, we diagnosed this patient as type III hyperlipoproteinemia. After 4 months of treatment with diet and gemfibrozil, the serum level of cholesterol and triglyceride were reduced to normal range. The skin lesions of both palms showed marked improvement but the skin lesions on elbows and buttocks were not much improved.
Adult ; Buttocks ; Chemistry ; Cholesterol ; Cholesterol, VLDL ; Diet ; Elbow ; Electrophoresis ; Gemfibrozil ; Humans ; Hyperlipoproteinemia Type III* ; Lipoproteins ; Male ; Plasma ; Reference Values ; Skin ; Triglycerides ; Ultracentrifugation ; Xanthomatosis*

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, beta-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 (ILRP) and VLDLR were detected by semi-quantitative RT-PCR. The results demonstrated that VLDL, beta-VLDL and LDL could increase the contents of TG and TC in macrophages. Cells treated with VLDL or beta-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.
Animals ; Arteriosclerosis ; metabolism ; pathology ; Cells, Cultured ; Cholesterol, LDL ; metabolism ; pharmacology ; Female ; Foam Cells ; cytology ; metabolism ; Lipoproteins, VLDL ; pharmacology ; Macrophages, Peritoneal ; cytology ; metabolism ; Mice ; Receptors, LDL ; metabolism ; Triglycerides ; metabolism

MED1 is a key transcription co-activator subunit of the Mediator complex that is essential for RNA polymerase II-dependent transcription. MED1 functions as a co-activator for PPARs and other nuclear receptors and transcription factors, and plays an important role in lipid metabolism. To examine how MED1 might affect plasma lipids, plasma triglyceride, cholesterol levels, and lipoprotein profiles, were measured in MED1(deltaLiv) mice fasted for 24, 48 and 72 hours. Histological changes in liver sections from MED1(deltaLiv) mice after 72 hours of fasting were also examined using H&E staining. There was no fat accumulation in livers of MED1(deltaLiv) mice compared to MED1(fl/fl) and PPARalpha -/- control mice after 72 hours of fasting. Compared with MEDl(fl/fl) mice, plasma triglycerides in MED1(deltaLiv) mice were significantly increased after 24, 48 and 72 hours of fasting, and plasma cholesterol was significantly increased after 48 and 72 hours of fasting. Lipoprotein profiles were similar in fed MED1(fl/fl) and MED1(deltaLiv) mice. However, very low density lipoprotein (VLDL) was significantly increased in MED1(deltaLiv) mice after 24 hours of fasting. We conclude that, hyperlipidemia in MED1(deltaLiv) mice in response to fasting is due to the accumulation of VLDL, which suggests that MED1 plays a pivotal role in the regulation of plasma triglyceride and cholesterol levels.
Animals ; Cholesterol ; blood ; Fasting ; Hyperlipidemias ; blood ; Lipoproteins, VLDL ; blood ; Liver ; chemistry ; Mediator Complex Subunit 1 ; genetics ; physiology ; Mice ; Mice, Knockout ; Triglycerides ; blood

INTRODUCTIONThis study aimed to compare the effects of the two most commonly prescribed atypical antipsychotics, olanzapine and risperidone, on fasting blood sugar and serum lipid profile of the recipients.

METHODSA randomised, comparative, open clinical study was conducted on 60 schizophrenic patients. The patients were divided into two groups, one receiving olanzapine and the other receiving risperidone. The patients were assessed for changes in fasting blood sugar and serum lipid profile (triglycerides [TG], high-density lipoprotein [HDL], low-density lipoprotein [LDL], very-low-density lipoprotein [VLDL] and total cholesterol) eight weeks after starting treatment. The number of patients positive for fasting blood sugar and lipid profile criteria of metabolic syndrome was calculated by applying the modified National Cholesterol Education Programme Adult Treatment Panel III guidelines (NCEP ATP III) criteria at eight weeks.

RESULTSPatients treated with olanzapine showed a highly significant increase in the observed parameters, whereas those treated with risperidone showed a significant increase in fasting blood sugar, HDL and LDL levels, and a highly significant increase in other parameters. Intergroup comparison was insignificant except for TG, VLDL and total cholesterol levels. More men as compared to women fulfilled the NCEP ATP III criteria for metabolic syndrome in both groups.

CONCLUSIONOlanzapine has a higher propensity to cause derangement of some parameters of lipid profile than risperidone. These parameters include TG, VLDL and total cholesterol levels.

Adolescent ; Adult ; Antipsychotic Agents ; pharmacology ; Benzodiazepines ; pharmacology ; Blood Glucose ; drug effects ; Cholesterol ; blood ; Female ; Humans ; Lipids ; blood ; Lipoproteins, HDL ; drug effects ; Lipoproteins, LDL ; blood ; Lipoproteins, VLDL ; drug effects ; Male ; Metabolic Syndrome ; complications ; diagnosis ; Reproducibility of Results ; Risperidone ; pharmacology ; Schizophrenia ; blood ; drug therapy ; Triglycerides ; blood

OBJECTIVETo investigate the effects of very low-density lipoprotein (VLDL) on cellular lipid accumulation and the expression of monocyte chemoattractant protein-1 (MCP-1) in human mesangial cells.

METHODSAn established stable human mesangial cell line (HMCL) was used in all experiments. VLDL-induced cellular lipid deposition was visualized by Oil Red O staining and analyzed quantitatively by standard enzymatic procedures. MCP-1 mRNA and protein expression levels in treated HMCLs were determined by real-time quantitative RT-PCR and enzyme-linked immunosorbent assay, respectively. For adhesion study, HMCLs were treated with VLDL for 12 hours, followed by a one-hour incubation with THP-1 cells.

RESULTSVLDL induced cellular lipid accumulation in HMCLs in a time- (0-24 h) and dose- (0-200 microg/ml) dependent manner, and the principal component of accumulated lipid is triglyceride. In HMCLs, MCP-1 mRNA expression was promoted by VLDL in a time- (0-6 h) and dose- (0-100 microg/ml) dependent manner, and VLDL also enhanced MCP-1 secretion in a dose-dependent manner. Such an effect was accompanied by increased adhesion of monocytes to HMCLs.

CONCLUSIONSVLDL can induce cellular triglyceride accumulation and upregulate the expression of MCP-1 in human mesangial cells. Hence, VLDL may be involved in the pathogenesis of lipid-mediated renal injury.

Cell Line ; Chemokine CCL2 ; genetics ; metabolism ; Humans ; Lipoproteins, VLDL ; pharmacology ; toxicity ; Mesangial Cells ; cytology ; metabolism ; RNA, Messenger ; genetics ; metabolism ; Triglycerides ; metabolism

BACKGROUNDThe plasma concentration of very low density lipoprotein (VLDL) is negatively correlated to renal function in glomerular diseases. Effects of VLDL on renal function have been partially attributed to the proliferation of mesangial cells. This study examined the potential role of the p42/44 mitogen activated protein kinase (MAPK) in mesangial cell proliferation induced by VLDL.

METHODSMesangial cells were treated with VLDL at different concentrations or for different time. The cell cycle of the mesangial cells was analyzed by XTT assay and flow-cytometry; MAPK activity was also assayed. In some experiments, cells were treated with VLDL together with or without 0.1 µmol/L PD 98059.

RESULTSTen to 500 µg/ml VLDL stimulated the proliferation of mesangial cells cultured in vitro in a concentration-dependent manner. The effect was associated with an increase in p42/44 MAPK activity. Increased proliferation of mesangial cells by VLDL was significantly attenuated by PD98059, a specific p42/44 MAPK inhibitor.

CONCLUSIONThese results indicate that the p42/44 MAPK pathway is an important regulator of mesangial cell proliferation and of renal functions.

Animals ; Cell Cycle ; drug effects ; Cell Proliferation ; drug effects ; Cells, Cultured ; Lipoproteins, VLDL ; pharmacology ; Male ; Mesangial Cells ; cytology ; drug effects ; Mitogen-Activated Protein Kinase 1 ; metabolism ; Mitogen-Activated Protein Kinase 3 ; metabolism ; Rats ; Rats, Sprague-Dawley

To explore the intracellular signal pathways for beta-VLDL induced very low density lipoprotein receptor (VLDL-R) transcription up-regulation and their effects on lipid accumulation in macrophages, Western Blot was used to examine phosphorylated ERK1/2 protein and regulated effects by different singal kinase inhibitants. It was found that beta-VLDL induced an increase in ERK1/2 activity in a protein kinase C (PKC)-dependent manner in murine RAW264.7 macrophages. By using different protein kinases inhibitors or activators, it was observed that the effect of beta-VLDL induced VLDL receptor transcription, which was monitored by RT-PCR analysis of VLDL receptor mRNA, was not affected by the inhibitor of p38 kinase and cAMP analog, but extremely abolished by pretreating cells with PD98059, an inhibitor of ERK and GF 109203X, an inhibitor of PKC. These results demonstrated that the PKC-ERK1/2 cascade is the essential signaling pathway by which beta-VLDL activated VLDL-R mRNA expression. Inhibition of the ERK1/2 signaling cascade resulted in suppression of the cellular lipid accumulation induced by beta-VLDL in macrophages.
Cells, Cultured ; Lipoproteins, VLDL ; metabolism ; Macrophages ; cytology ; metabolism ; Mitogen-Activated Protein Kinase 1 ; metabolism ; physiology ; Mitogen-Activated Protein Kinase 3 ; metabolism ; physiology ; Protein Kinase C ; antagonists & inhibitors ; metabolism ; Receptors, LDL ; biosynthesis ; genetics ; Signal Transduction ; Transcription Factors ; metabolism ; Transcription, Genetic ; Up-Regulation

To elucidate the intracellular signaling pathways for VLDL-induced VLDLR transcription, Western blot analysis was used to examine phosphorylated ERK1/2 protein. It was found that that VLDL induced an increase in ERK1/2 activity in a protein kinase C (PKC)-dependent manner in murine RAW264.7 macrophages. By using different protein kinases inhibitors or activators it was observed that the effect of VLDL-induced VLDL receptor transcription, which is monitored by RTPCR analysis of VLDL receptor mRNA, was not affected by the inhibitor of p38 kinase and cAMP analog, but completely abolished by pretreatment of the cells with PD 98059, an inhibitor of MEK and GF 109203X, an inhibitor of PKC. These results demonstrated that the PKC/ERK1/2 cascade is the essential signaling pathway by which VLDL activates VLDL receptor mRNA expression.
Animals ; CCAAT-Binding Factor ; metabolism ; Cattle ; Cells, Cultured ; Gene Expression Regulation ; Humans ; Lipoproteins, VLDL ; metabolism ; Macrophages ; cytology ; metabolism ; Mitogen-Activated Protein Kinase 1 ; metabolism ; Mitogen-Activated Protein Kinase 3 ; Mitogen-Activated Protein Kinases ; metabolism ; physiology ; Muscle, Smooth, Vascular ; metabolism ; Phosphorylation ; RNA, Messenger ; metabolism ; Rats ; Receptors, LDL ; metabolism ; Signal Transduction ; Transcription Factors ; metabolism ; Transcription, Genetic