Low density lipoprotein density and composition in hypercholesterolaemic men treated with HMG CoA reductase inhibitors and gemfibrozil

1991 ◽  
Vol 229 (5) ◽  
pp. 427-434 ◽  
Author(s):  
M. TILLY-KIESI ◽  
M. J. TIKKANEN
1997 ◽  
Vol 133 (1) ◽  
pp. 51-59 ◽  
Author(s):  
Masakazu Sakai ◽  
Shozo Kobori ◽  
Takeshi Matsumura ◽  
Takeshi Biwa ◽  
Yoshihiro Sato ◽  
...  

Blood ◽  
2007 ◽  
Vol 110 (11) ◽  
pp. 4192-4192
Author(s):  
Laura Connelly-Smith ◽  
Joanne Pattinson ◽  
Martin Grundy ◽  
Shili Shang ◽  
Claire Seedhouse ◽  
...  

Abstract P-glycoprotein (pgp) is a membrane transporter encoded by the multidrug resistance (MDR1, ABCB1) gene. Pgp is a poor prognostic factor in elderly patients with acute myeloid leukaemia (AML). In addition to its role in drug efflux, pgp has been implicated in cellular cholesterol homeostasis. We investigated the effects of exogenous cholesterol removal on pgp expression and function. KG1a drug-naïve, primitive leukaemia cells were cultured in serum free medium with or without the addition of low density lipoprotein (LDL) cholesterol. After 72 hours pgp expression and function was assessed by flow cytometry and total cholesterol content of the KG1a cells was determined by the Amplex Red® cholesterol assay. The addition of clinically available cholesterol lowering agents, HMG-CoA (3-hydroxy-3-methylglutaryl coenzyme A) reductase inhibitors to KG1a cells was also assessed. There was a 39% (SEM 8.3% P=0.03) decrease in pgp protein expression after 3 days of serum free culture without HMG-CoA reductase inhibitors. Message was decreased by 40% (P=0.01) and pgp function was also reduced by 40% (P=0.005). The addition of low density lipoprotein (LDL) cholesterol restored pgp expression to 86% of the basal value. The addition of a HMG-CoA reductase inhibitor to KG1a cells in serum free culture resulted in a further 26% (lovastatin, P=0.03) and 16% (pravastatin, P=0.05) reduction in pgp respectively. Lovastatin also significantly reduced cellular cholesterol levels by 47% (P=0.002) under serum free conditions. Furthermore, the toxicity of the pgp substrate drug daunorubicin was significantly enhanced following lovastatin pre-culture (P=0.04). We conclude that LDL/cholesterol contributes to pgp expression and chemoresistance in primitive leukaemia cells. The use of HMG-CoA reductase inhibitors may be of clinical value in lowering pgp expression in AML.


1988 ◽  
Vol 22 (7-8) ◽  
pp. 542-545 ◽  
Author(s):  
Frederick P. Zeller ◽  
Karen C. Uvodich

Lovastatin is the first 3-hydroxy-3-methylglutaryl-coenzyme A (HMG-CoA) reductase inhibitor approved for the treatment of primary hypercholesterolemia. It is indicated as adjunctive therapy to dietary control and should be initiated at 20 mg/d in the evening. With higher dosages, twice-daily dosing is preferred, particularly when the dosage reaches the maximum recommended 80 mg/d. Compared with other drugs available, lovastatin has been shown to have good efficacy and a low incidence of side effects. Limited pharmacokinetic information available from the manufacturer reports absorption ∼ 30 percent, protein binding > 95 percent, and a dual pathway for elimination through both urine (10 percent) and feces (83 percent). The drug has been clinically tested versus placebo and in combination with other cholesterol-lowering drugs. Lovastatin is effective in lowering total cholesterol and low-density lipoprotein cholesterol by 25–30 percent, with nonfamilial (hypercholesterolemic) patients responding better than those with the familial form of the disease. One percent of lovastatin patients have discontinued therapy because of intolerable side effects. The most common complaints are flatulence and diarrhea; more severe abnormalities include elevation of liver enzymes and an unclear propensity for producing lens opacities. The monthly cost to a patient taking 20 mg/d is approximately $44. Although the drug should be added to hospital formularies, long-term safety experience and competition from other HMG-CoA reductase inhibitors will determine lovastatin's final therapeutic role.


2021 ◽  
Vol 24 (3) ◽  
pp. 101-107
Author(s):  
Bella Fatima Dora Zaelani ◽  
Mega Safithri ◽  
Dimas Andrianto

Cholesterol plaque buildup in artery walls occurs due to oxidation of Low-Density Lipoprotein (LDL) molecules by free radicals, which are a risk factor for coronary heart disease. Piper crocatum contains active compounds that can act as HMG-CoA reductase inhibitors, such as flavonoids, alkaloids, polyphenols, tannins, and essential oils. This study aimed to predict the potential of Piper crocatum extract and fraction compounds as HMG-CoA reductase inhibitors by investigating the ligand affinity to the HMG-CoA reductase enzyme. Ligand and receptor preparation was conducted using BIOVIA Discovery Studio Visualizer v16.1.0.15350 and AutoDock Tools v.1.5.6. Molecular docking used AutoDock Vina, while ligand visualization and receptor binding used PyMOL(TM) 1.7.4.5.Edu. The receptor used was HMG-CoA reductase (PDB code: 1HWK) with atorvastatin as a control ligand. Catechin, schisandrin B, and CHEMBL216163 had the highest inhibition with affinity energies of -7.9 kcal/mol, -8.2 kcal/mol, -8.3 kcal/mol, respectively. Amino acid residues that played a role in ligand and receptor interactions were Ser684, Asp690, Lys691, Lys692.


1990 ◽  
Vol 272 (1) ◽  
pp. 181-186 ◽  
Author(s):  
T A Berkhout ◽  
L M Havekes ◽  
N J Pearce ◽  
P H E Groot

(-)-Hydroxycitrate, a potent inhibitor of ATP citrate-lyase, was tested in Hep G2 cells for effects on cholesterol homoeostasis. After 2.5 h and 18 h incubations with (-)-hydroxycitrate at concentrations of 0.5 mM or higher, incorporation of [1,5-14C]citrate into fatty acids and cholesterol was strongly inhibited. This most likely reflects an effective inhibition of ATP citrate-lyase. Cholesterol biosynthesis was decreased to 27% of the control value as measured by incorporations from 3H2O, indicating a decreased flux of carbon units through the cholesterol-synthetic pathway. After 18 h preincubation with 2 mM-(-)-hydroxycitrate, the cellular low-density-lipoprotein (LDL) receptor activity was increased by 50%, as determined by the receptor-mediated association and degradation. Measurements of receptor-mediated binding versus LDL concentration suggests that this increase was due to an increase in the numbers of LDL receptors. Simultaneously, enzyme levels of 3-hydroxy-3-methylglutaryl-CoA (HMG-CoA) reductase as determined by activity measurements increased 30-fold. Our results suggest that the increases in HMG-CoA reductase and the LDL receptor are initiated by the decreased flux of carbon units in the cholesterol-synthetic pathway, owing to inhibition of ATP citratelyase. A similar induction of HMG-CoA reductase and LDL receptor was also found after preincubations of cells with 0.3 microM-mevinolin, suggesting that the underlying mechanism for this induction is identical for both drugs.


1991 ◽  
Vol 6 (3) ◽  
pp. 223-230 ◽  
Author(s):  
J.-G. Lehoux ◽  
A. Lefebvre

ABSTRACT Low-density lipoprotein (LDL) receptor mRNA was found in both rat and hamster adrenals. Within 30 min after ACTH administration a significant increase in the levels of both LDL receptor and 3-hydroxy-3-methylglutaryl coenzyme A (HMG-CoA) mRNAs was observed in rat adrenals; these levels remained increased for up to 240 min. The increase in the levels of LDL receptor and HMG-CoA reductase mRNAs produced by ACTH was reduced by co-administration of aminoglutethimide while, at the same time, the adrenal cholesterol content of rats treated with both aminoglutethimide and ACTH was significantly increased compared with that in groups treated with ACTH alone. Cycloheximide also induced increased levels of rat adrenal mRNAs for LDL receptor and HMG-CoA reductase, but this effect was not additive with that of ACTH. These results suggest that, in the rat, the short-term effect of ACTH on the levels of mRNAs for the LDL receptor and HMG-CoA reductase is similarly controlled and might be mediated through changes in the adrenal cholesterol content. In the hamster adrenal, however, no significant fluctuations were found in the level of LDL receptor mRNA, although a marked increase was found in the level of HMG-CoA reductase mRNA, 2 h after ACTH administration. This indicates that an important effect of ACTH on cholesterol metabolism in the hamster adrenal is at the level of HMG-CoA reductase. In the hamster, therefore, where the main source of cholesterol for the adrenal gland is de-novo synthesis, it seems that a complex mechanism is involved in the control of LDL receptor gene expression.


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