Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UMLS:C0242339 (dyslipidemia)
 13,927 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

For the last 30 years fibrates have been widely prescribed to treat human dyslipidemia. However, the primary mechanism by which they lower plasma lipid levels is still unknown. Studies with transgenic mice have suggested that changes in apoC-III expression levels have a dramatic influence on plasma triglyceride levels. These results suggested that fibrates could reduce lipid levels by lowering apoC-III gene expression. In the current studies, we sought to determine whether the selected fibrates, bezafibrate, clofibrate, fenofibrate, and gemfibrozil, could reduce hepatic apoC-III mRNA and plasma apoC-III levels. Chow-fed rats were orally gavaged daily with a dosing vehicle alone or with 100 mg/kg of each of the fibrates for 1 week and in addition with gemfibrozil for 2 weeks. Bezafibrate and fenofibrate lowered plasma triglyceride by approximately half and dramatically reduced hepatic apoC-III mRNA and plasma apoC-III levels. In contrast, clofibrate did not reduce plasma triglyceride levels and only partially reduced apoC-III mRNA and plasma protein levels. Gemfibrozil strongly reduced plasma triglyceride levels and had an intermediate but significant effect on apoC-III mRNA and plasma apoC-III levels. Some of the fibrates, especially gemfibrozil also reduced plasma apoC-II levels, an effect that could contribute to the observed triglyceride-lowering effect. In addition, the ratio of plasma apoE to plasma apoC-II plus apoC-III was strongly and inversely correlated with plasma triglyceride levels. As plasma apoE levels were not reduced in gemfibrozil-treated animals, this could also have contributed to the triglyceride-lowering effect of this fibrate. Fibrate-mediated triglyceride lowering was not the result of a decreased apoB or VLDL production and, therefore, suggested an enhanced VLDL remnant catabolism. Our results suggest that the mechanism by which fibrates lower plasma triglycerides is by reducing the level of hepatic apoC-III expression.
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PMID:Hypolipidemic activity of select fibrates correlates to changes in hepatic apolipoprotein C-III expression: a potential physiologic basis for their mode of action. 884 80

Apolipoprotein (apo) E is associated with several classes of lipoproteins and serves as a ligand for the receptor mediated uptake of cholesterol-rich particles by hepatocytes and peripheral tissues. Variant forms of apo E is also associated with dyslipidemia and late-onset of Alzheimer's Disease (AD). We report here expression of apoE in various mouse tissues, and regulation of apoE in liver, kidney, brain and testes by supraphysiological doses of estrogen. ApoE mRNA was quantified by RNase protection assay and translatable apoE mRNA by in vitro translation. As an internal control the levels of beta-actin mRNA were also quantified. Highest levels of apoE were expressed in liver (220-280 pg/mu g RNA) with negligible levels in small intestine. Brain expressed highest levels of total (35-40 pg/mu g RNA) and translatable apoE mRNA next only to liver. Other tissues that expressed relatively higher levels of apoE were adrenals, testes and ovary. ApoE was also found to be expressed in heart, lung, kidney and spleen. Regulation of apoE gene expression by estrogen (3 mu g 17beta-estradiol/ g body weight/ day for 5 consecutive days) was studied in liver, kidney, brain and testes of 4 mouse strains. Hepatic apoE mRNA did not change significantly in any of the mouse strains following estradiol administration. Of note was significant increases in the levels of brain apoE mRNA in the strain C3H. These studies demonstrate that estrogen regulates apoE gene expression in a tissue-specific manner in mice, and increases in apoE mRNA in the brain by estrogen may have implications in late-onset of Alzheimer's Disease.
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PMID:Apolipoprotein E gene expression in various tissues of mouse and regulation by estrogen. 893 23

In accordance with the principles of protein biochemistry, apolipoprotein is the only protein which: 1) forms a protein-lipid complex (PLC) mainly from one class of lipids; 2) determines its functional role; 3) causes dyslipidemia in the genetic destruction of apoproteins or their quantitative ratio. Blood flow lipid transport is based on the functional specificity of their apoproteins; each apoprotein forms a functionally independent PLC; each PLC is formed from one class of lipids; each PLC has one protein-vector; each protein-vector interacts only with receptor. The basis of a united cycle functioning in lipid transport is the difference of primary apoprotein structure. Cholesterol performs an auxiliary function in triglyceride transport by providing circulation in the functional cycle. Lipid transport in blood flow is based, first, on the principles of protein biochemistry and, second, on those of lipidology.
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PMID:[Blood flow lipid transport from viewpoint of protein biochemistry]. 898 7

Recombinant human interleukin-2 (rIL-2) is used to treat refractory cancers. During such treatment, patients develop severe hypocholesterolemia along with striking alterations in the concentration and composition of the circulating lipoproteins. The present study was undertaken to gather information about the pathogenesis of these abnormalities. Patients were studied before-, during- and after a 5-day course of high dose i.v. rIL-2. Whole plasma cholesterol was markedly reduced by rIL-2 administration (52%; P < 0.001), whereas the triglyceride concentration did not change. Thus, the lipoproteins became triglyceride enriched (P = 0.004). Low density lipoprotein cholesterol, apolipoprotein B (apoB), high density lipoprotein cholesterol, and apoA-I concentrations all decreased. Esterified cholesterol levels were markedly reduced. Total plasma apoE increased markedly, and two kinds of abnormal particles appeared: 1) beta-migrating, very low density lipoproteins; and 2) discoidal, apoE- and phospholipid-containing particles with abnormal density and electrophoretic mobility. The activities of two lipoprotein triglyceride hydrolases, lipoprotein lipase and hepatic lipase, fell significantly during treatment and returned promptly to pretreatment levels after rIL-2 was discontinued. Lecithin:cholesteryl acyltransferase (LCAT) activity also decreased significantly (64%) during treatment, but in contrast to the lipases, remained low for at least 5 days after the last dose of rIL-2 (P < 0.001). High dose i.v. rIL-2 induces severe dyslipidemia with deficiencies of both postheparin lipases and acute LCAT deficiency. Most, if not all, of the lipoprotein changes observed are explained by the LCAT deficiency that follows IL-2-induced hepatocellular injury and cholestasis.
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PMID:Acute dyslipoproteinemia induced by interleukin-2: lecithin:cholesteryl acyltransferase, lipoprotein lipase, and hepatic lipase deficiencies. 914 52

The epidemiologic approach to investigation of atherosclerotic cardiovascular disease has provided many insights into the preclinical and clinical spectrum of the disease. The hazard of developing atherosclerotic cardiovascular disease is substantial with coronary heart disease (CHD), the most common and most lethal feature. The outlook in those who manage to survive the initial episode is also serious, with a 10-year mortality rate of 37% for persons with angina and a 55% rate for those sustaining a myocardial infarction. Fifteen percent of persons developing CHD present with a fatal event, and 38% of infarctions go unrecognized. The presence of atherosclerosis in one vascular territory imposes an increased risk of its appearing in another area at two to six times the general population rate. The major cardiovascular risk factors adversely affect all arterial vascular territories so that correction of risk factors targeted at one particular atherosclerotic outcome may also favorably influence the other risk factors. Coronary disease is the most prevalent lethal hazard of hypertension, dyslipidemia, glucose intolerance, and cigarette smoking. These risk factors cluster and optimal therapy must improve the whole risk profile. Women share the same risk factors for CHD as men. Although women have a lower absolute risk for most risk factors, a high total/HDL cholesterol ratio, left ventricular hypertrophy, and diabetes each tend to eliminate the female advantage. Menopause also promptly escalates risk threefold. Although women tend to have a lower incidence than men, the initial attack is just as highly lethal in women, and their subsequent outlook as survivors is at least as serious as for men. Sudden death is a pre-eminent feature of coronary disease and cardiac failure. Coronary disease increases sudden death risk 3.3-fold and cardiac failure 4.8-fold. Sudden death incidence varies in relation to the same cardiovascular risk factors as coronary heart disease, with no unique risk factors identified. However, multivariate combinations of these in a profile can identify high-risk candidates for sudden death as well as coronary attacks in general. The key to prevention of sudden death is to prevent coronary attacks and cardiac failure. Despite aggressive cardiac revascularization and treatment of hypertension, congestive heart failure (CHF) has not decreased in prevalence, and innovations in the treatments of overt failure have not substantially improved survival. Median survival is only 1.7 years for men and 3.2 years for women. The conditional probability of developing CHF can be estimated using a logistic function comprised of age, systolic pressure, vital capacity, heart rate, ECG-left ventricular hypertrophy (LVH), glucose intolerance, x-ray enlargement, and presence of CHD and heart murmurs. Eighty percent of CHF events occur in persons in the upper quintile of multivariate risk. Continued clinical, metabolic, and epidemiologic research have expanded and refined atherosclerosis risk factors. The lipid connection is now concerned with the apoprotein makeup of the lipids, subfractions of lipids, and Lp(a). The diabetic influence is now focused on insulin resistance. Ambulatory monitoring is being used to evaluate blood pressure and silent ischemia. Fibrinogen and leukocyte counts have emerged as possible indicators of unstable lesions. Prospects for primary and secondary prevention are good if public health measures, health education, and preventive medicine are implemented based on existing knowledge of correctable or avoidable risk factors. The potential for more effective prevention continues to expand, and great advances have already been made in countries where aggressive preventive measures have been implemented to correct the major established risk factors.
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PMID:Hazards, risks, and threats of heart disease from the early stages to symptomatic coronary heart disease and cardiac failure. 921 Oct 12

Plasma lipoproteins (LP) may be identified on the basis of density properties or apolipoprotein (apo) composition. ApoB-containing LP occur in VLDL, IDL and LDL. There are several types of apoB-containing LP characterized by specific composition of minor apolipoproteins (apoC, apoE etc.) and lipid constituents (triglycerides and cholesterol), metabolic properties and relative atherogenicity. The alterations of lipoprotein metabolism in renal disease resulting in elevated levels of apoB-containing LP may be reflected in hyperlipidemia. Whereas nephrotic syndrome and heavy proteinuria are associated with increased formation of cholesterol-rich apoB-containing LP in LDL and VLDL, the characteristic feature in renal failure is the accumulation of intact or partially metabolised triglyceride-rich LP in IDL and VLDL. The potentially atherogenic apoB-containing LP have been linked to the pathogenic processes that result in progressive glomerular and interstitial lesions and ultimate loss of renal function. The mechanisms of injury are not fully understood. Receptor- and non-receptor mediated uptake of LP by mesangial cells may induce or accelerate proliferative and sclerotic processes in the glomerular mesangium that are analogous to atherosclerosis in the arterial wall. Changes in glomerular permeability can result in increased filtration of LP that may be internalized by tubular cells and elicit corresponding lesions in the interstitial tissues. The negative impact of proteinuria on the prognosis of renal disease could be mediated in part through an increased filtration of lipoproteins. Induction of hyperlipidemia accelerates glomerular and interstitial damage in experimental renal failure. This can be attenuated by treatment with hypolipemic agents. In patients, increased concentrations of apoB-containing LP are associated with more rapid progression of renal insufficiency in both primary renal disease and diabetic nephropathy. It is, however, presently not known to what extent treatment of the renal dyslipidemia can modify the progression of chronic renal failure. Experimental and clinical evidence suggest that apoB-containing LP may play a pathogenetic role in the progression of renal disease.
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PMID:Progression of renal failure: role of apolipoprotein B-containing lipoproteins. 940 33

Immediate-release niacin manifests beneficial effects in cardiovascular disease with respect to dyslipidemic states. It lowers low-density lipoprotein (LDL) cholesterol, triglycerides, lipoprotein(a), and apoprotein B; at the same time, it increases high-density lipoprotein (HDL) cholesterol, HDL2, and apoprotein A-I. However, use of crystalline niacin has drawbacks: therapy requires multidose regimens, and side effects include flushing and pruritus. Slowing absorption with sustained-release formulations succeeds in decreasing flushing and increasing tolerance, but increases in hepatic enzyme levels have raised safety concerns. A new extended-release, once-daily formulation of niacin (Niaspan) shows promise in minimizing flushing while avoiding hepatotoxicity. A multicenter, randomized, double-blind clinical trial of Niaspan enrolled 122 patients with confirmed diagnosis of primary dyslipidemia (LDL cholesterol >4.14 mmol/L [160 mg/dL] and triglycerides <9 mmol/L [800 mg/dL]) into 3 treatment groups: (1) Niaspan 1,000 mg/day; (2) Niaspan 2,000 mg/day; and (3) placebo. The primary treatment endpoint was LDL-cholesterol level. This endpoint was not significantly affected by placebo (0.2% increase), but Niaspan decreased LDL cholesterol by 5.8% (1,000 mg/day) and 14.6% (2,000 mg/day) (p <0.001). Likewise, with placebo there were significant changes in total cholesterol, triglycerides, lipoprotein(a), and apoprotein B, whereas both Niaspan 1,000 and 2,000 mg/day significantly (p <0.001) decreased these parameters. In addition, both Niaspan groups showed significant (p <0.001) increases in HDL cholesterol (17% and 23%, respectively), including HDL subfractions. With respect to flushing, 20% of the placebo group reported at least 1 episode, whereas 88% and 83% of the Niaspon 1,000- and 2,000-mg/day groups, respectively, reported episodes. There was no hepatotoxicity as liver enzyme levels remained within clinically accepted limits in all treatment groups. However, Niaspan 2,000 mg/day showed a significant increase in aspartate aminotransferase compared with baseline and placebo. This trial demonstrated a cholesterol-modifying effect of Niaspan consistent with those reported for niacin, but demonstrated a better tolerance for flushing. Moreover, in contrast to sustained-release formulations, Niaspan showed relatively mild hepatic effects.
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PMID:A new extended-release niacin (Niaspan): efficacy, tolerability, and safety in hypercholesterolemic patients. 991 60

Lipoprotein lipase (LPL) is a key enzyme in lipoprotein metabolism, and has been hypothesized to exert either pro- or anti-atherogenic effects, depending on its localization. Decreased plasma LPL activity is associated with the high triglyceride (TG);-low HDL phenotype that is often observed in patients with premature vascular disease. In contrast, in the vessel wall, decreased LPL may be associated with less lipoprotein retention due to many potential mechanisms and, therefore, decreased foam cell formation. To directly assess this hypothesis, we have distinguished between the effects of variations in plasma and/or vessel wall LPL on atherosclerosis susceptibility in apoE-deficient mice. Reduced LPL in both plasma and vessel wall (LPL(+/-)E(-/-)) was associated with increased TG and increased total cholesterol (TC) compared with LPL(+/+)E(-/-) sibs. However despite their dyslipidemia, LPL(+/-)E(-/-) mice had significantly reduced lesion areas compared to the LPL(+/+)E(-/-) mice. Thus, decreased vessel wall LPL was associated with decreased lesion formation even in the presence of reduced plasma LPL activity. In contrast, transgenic mice with increased plasma LPL but with no increase in LPL expression in macrophages, and thus the vessel wall, had decreased TG and TC and significantly decreased lesion areas compared with LPL(+/+)E(-/-) mice. This demonstrates that increased plasma LPL activity alone, in the absence of an increase in vessel wall LPL, is associated with reduced susceptibility to atherosclerosis. Taken together, these results provide in vivo evidence that the contribution of LPL to atherogenesis is significantly influenced by the balance between vessel wall protein (pro-atherogenic) and plasma activity (anti-atherogenic).
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PMID:Plasma and vessel wall lipoprotein lipase have different roles in atherosclerosis. 1074 72

Splenomegaly with sea-blue histiocytes is not associated with dyslipidemia, except in severe cases of hypertriglyceridemia, Tangier disease, or lecithin cholesterol acyltransferase deficiency. We describe two kindreds in which the sea-blue histiocyte syndrome was associated with an apoE variant in the absence of severe dyslipidemia. Both patients presented with mild hypertriglyceridemia and splenomegaly. After splenectomy both patients developed severe hypertriglyceridemia. Pathological evaluation of the spleen revealed the presence of sea-blue histiocytes. A mutation of apoE was demonstrated, with a 3-bp deletion resulting in the loss of a leucine at position 149 in the receptor-binding region of the apoE molecule [apoE (delta149 Leu)]. Although both probands were unrelated, they were of French Canadian ancestry, suggesting the possibility of a founder effect. In summary, we describe two unrelated probands with primary sea-blue histiocytosis who had normal or mildly elevated serum triglyceride concentrations that markedly increased after splenectomy. In addition, we provide evidence linking the syndrome to an inherited dominant mutation in the apoE gene, a 3-bp deletion on the background of an apoE 3 allele that causes a derangement in lipid metabolism and leads to splenomegaly in the absence of severe hypertriglyceridemia.
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PMID:Familial splenomegaly: macrophage hypercatabolism of lipoproteins associated with apolipoprotein E mutation [apolipoprotein E (delta149 Leu)]. 1109 79

Current approaches to the treatment of lipid disorders are inadequate for a substantial number of patients with severe hyperlipoproteinemia, isolated low high-density lipoprotein (HDL) cholesterol levels, or other molecular disorders of lipoprotein metabolism. Therefore, dyslipidemias remain important targets for the development of novel therapies. Gene therapy is a logical therapeutic approach to monogenic lipoprotein disorders, such as homozygous familial hypercholesterolemia, familial lipoprotein lipase deficiency, familial lecithin-cholesterol acyltransferase deficiency, and abetalipoproteinemia, for which current therapies are inadequate. Gene therapy could also be used to increase expression of certain proteins, such as apolipoprotein A-I as a strategy to raise HDL cholesterol levels or apoE as a strategy for severe combined hyperlipidemia. With further progress in the development of vectors, gene therapy for severe dyslipidemia is likely to become a clinical reality.
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PMID:Gene therapy for dyslipidemia: clinical prospects. 1112 93


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