Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: EC:3.1.1.34 (lipoprotein lipase)
7,025 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Factors contributing to fasting hypertriglyceridaemia were studied in 20 patients with non-insulin-dependent diabetes--nine with normal triglyceride concentrations [fasting triglyceride 0.94 (range 0.58-1.23) mmol l-1] and eleven with mild fasting hypertriglyceridaemia [fasting triglyceride 2.4 (1.82-4.0) mmol l-1]. The patients with hypertriglyceridaemia were more obese [body mass index 29.0 (24.6-33.8) vs. 25.7 (21.9-30.1) kg m-2, P less than 0.05] and demonstrated impaired glucose disposal in response to exogenous insulin at isoglycaemia [insulin sensitivity index, SIp 0.7 (0.27-2.5) vs. 2.4 (0.62-5.1) ml m-2 min per mU l-1, P less than 0.001]. Basal non-esterified fatty acid (NEFA) and glycerol concentrations were higher and were suppressed to a lesser extent during isoglycaemic hyperinsulinaemia. Fasting glucose and apolipoprotein B concentrations were higher in the hypertriglyceridaemic patients, but lipoprotein lipase activities were similar in the two groups. When the effect of obesity was removed (by weight-matching six normotriglyceridaemic with seven hypertriglyceridaemic patients) basal NEFA and glycerol concentrations and the suppression of NEFA in response to insulin remained significantly different between the two groups. We propose that defects in both the glucoregulatory and antilipolytic actions of insulin contribute to mild fasting hypertriglyceridaemia in NIDDM, and that these defects cannot be attributed solely to obesity. These disorders of insulin action may also have important implications for the postprandial metabolism of triglyceride-rich lipoproteins and hence atherogenesis.
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PMID:Determinants of mild fasting hypertriglyceridaemia in non-insulin-dependent diabetes. 200 44

Non-insulin-dependent diabetic (NIDDM) subjects exhibit abnormalities in their plasma lipid and lipoprotein profiles that increase the risk of ischemic heart disease. This study was designed to examine the metabolic behavior of very-low-density (VLDL), intermediate-density (IDL), and low-density (LDL) lipoproteins in NIDDM patients before treatment and after 4 wk of insulin therapy. Basal turnover studies of 131I-labeled VLDL1 (svedberg units [Sf] 60-400) and 131I-labeled VLDL2 (Sf 20-60) apolipoprotein B (apoB) were conducted in a group of seven NIDDM patients who had been off oral therapy for 1 wk. The subjects exhibited higher than normal transport rates for VLDL1 and a diminished input of apoB into the VLDL2 density range. These observations are concordant with the hypothesis that NIDDM patients overproduce VLDL triglyceride but not apoB. VLDL1 and VLDL2 were converted to IDL and ultimately to LDL at approximately normal rates, although the delipidation pathway by which apoB-containing particles were processed exhibited different properties from that seen in control subjects. Insulin therapy reduced plasma triglyceride by 38%, and this was associated with a 41% fall in VLDL1 mass (P less than 0.01). VLDL2 was less affected (19% reduction, P less than 0.05), IDL was unchanged, and LDL fell 17% (P less than 0.05). Repeat metabolic studies revealed that the major effects of insulin were to reduce VLDL1-apoB transport (from 811 to 488 mg/day) and increase the direct input of VLDL2 into the plasma (from 182 to 533 mg/day, P less than 0.05). These alterations in VLDL production led to normalization of apoB kinetics in IDL and LDL. The fractional catabolic rate of LDL increased 19% (P less than 0.05), whereas direct input into this fraction, which had been high before treatment, was reduced. Postheparin plasma lipoprotein lipase (LPL) and hepatic lipase levels were unaffected by insulin, although the hormone did increase LPL in adipose tissue. This lack of effect on lipase activities correlated well with the observation that the rates of catabolism of apoB in VLDL1, VLDL2, and IDL were not significantly affected by insulin therapy.
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PMID:Effect of insulin therapy on metabolic fate of apolipoprotein B-containing lipoproteins in NIDDM. 220 Jul 27

This paper presents a case of typical hyperlipoproteinemia type I in a young woman. Her serum triglycerides varied between 2 and 90 mmol/l and she had substantial amounts of apolipoprotein B-48 in fasting plasma. She had no detectable lipoprotein lipase (LPL) activity in post-heparin plasma (less than 0.2 percent of normal). Southern blot analysis suggested no major defect in her LPL gene and Northern blot analysis of adipose tissue RNA showed normal-sized LPL-mRNA. A 2-h [35S]methionine incorporation experiment with adipose tissue pieces in vitro showed that she produced normal-sized LPL and had LPL catalytic activity in the tissue. The amounts were, however, only 5-10% of control. No detectable LPL radioactivity or catalytic activity was released from patient tissue even in the presence of heparin in the incubations. Immunofluorescent staining of adipose tissue biopsies from the patient showed LPL immunoreactivity only in adipocytes and little or none within the capillaries. Treatment of immunoprecipitated labeled LPL with endoglycosidase H showed that the oligosaccharide chains on her enzyme were of the high-mannose type and not processed as in controls. Taken together the data suggest that the patient synthesizes a relatively normal LPL protein which is core-glycosylated and folded into active enzyme as in normal subjects, but is not effectively transported via the Golgi to the cell surface.
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PMID:Hyperlipoproteinemia type I in a patient with active lipoprotein lipase in adipose tissue and indications of defective transport of the enzyme. 220

Large (Sf greater than 100) and small (Sf 100-20) very low density lipoprotein (VLDL) particles were isolated by density gradient ultracentrifugation and characterized chemically in 8 patients with primary hypertriglyceridemia before and after 6 weeks treatment with 4 grammes daily of nicotinic acid (NA). Concomitant changes in high density lipoprotein (HDL) subclass distribution were determined by gradient gel electrophoresis. Small VLDL was subjected to lipolysis in vitro by incubation with bovine lipoprotein lipase before and after NA, and the change in the lipolytic end-product isolated in the low density lipoprotein (LDL) fraction was investigated. Reductions were achieved in the plasma levels of triglycerides, free and esterified cholesterol, phospholipids and proteins in the two VLDL subfractions. In all, the composition of both large and small VLDL particles changed towards potentially less atherogenic particles that were poorer in cholesteryl esters. The HDL cholesterol concentration increased and the HDL protein distribution on gradient gel electrophoresis changed towards larger particles. The mechanism behind the change in cholesterol distribution between VLDL and HDL after NA treatment is unclear, but it could possibly relate to decreased lipid transfer activity. NA reduced the content of apolipoprotein B in both VLDL subclasses and did not decrease the calculated particle size or the number of triglyceride molecules per particle, indicating a reduction of VLDL particle number rather than of particle size. The LDL density fraction isolated after lipolysis in vitro of small VLDL contained less total cholesterol and phospholipids and had a density profile more similar to native LDL after the patients had been treated with NA.
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PMID:Normalisation of the composition of very low density lipoprotein in hypertriglyceridemia by nicotinic acid. 228

When bezafibrate therapy was interrupted in patients who had been on continuous treatment for hyperlipoproteinemia for 4-10 years, there were significant increases in the serum cholesterol, triglyceride and apolipoprotein B concentrations corresponding to an increase of the very low density lipoprotein (VLDL) levels by approximately 50%. This increase of VLDL was accompanied by reduced levels of the post-heparin lipoprotein lipase activity (LPLA) (P = 0.07) and hepatic lipase (P = 0.05) activity with a significant reduction of the skeletal muscle LPLA (P less than 0.05), but not the adipose tissue LPLA, and a retarded removal of an i v injected fat emulsion (P less than 0.01). There were no significant changes of the low or high density lipoprotein cholesterol or the apolipoprotein A-I or A-II concentrations. Three months after bezafibrate treatment the content of linoleic and gammalinoleic acid in the plasma cholesterol ester had increased significantly, while the palmitoleic and oleic acids were reduced in spite of unchanged dietary treatment. Taken together, the data indicate that a lipid-lowering effect of bezafibrate, particularly on the VLDL lipids, is maintained throughout long treatment periods. One mechanism for the reduced level of the triglyceride-rich lipoproteins is an increased activity of the lipoprotein-lipase activity in the skeletal muscle, which decreased when the treatment was interrupted. The significance of the changes of the plasma lipid fatty acid spectrum during bezafibrate treatment remains unclear.
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PMID:Interruption of long-term lipid-lowering treatment with bezafibrate in hypertriglyceridaemic patients. Effects on lipoprotein composition, lipase activities and the plasma lipid fatty acid spectrum. 236 Sep 15

Familial lipoprotein lipase (LPL) deficiency is a rare genetic disorder accompanied by well-characterized manifestations. The phenotypic expression of heterozygous LPL deficiency has not been so clearly defined. We studied the pedigree of a proband known to be homozygous for a mutation resulting in nonfunctional LPL. Hybridization of DNA from 126 members with allele-specific probes detected 29 carriers of the mutant allele. Adipose tissue LPL activity, measured previously, was reduced by 50% in carriers, but did not reliably distinguish them from noncarriers. Carriers were prone to the expression of a form of familial hypertriglyceridemia characterized by increased plasma triglyceride, VLDL cholesterol and apolipoprotein B, and decreased LDL and HDL cholesterol concentrations. These manifestations were age modulated, with conspicuous differences between carriers and noncarriers observed only after age 40. Several noncarriers exhibited similar lipid abnormalities, but without the inverse relationship between VLDL cholesterol and LDL cholesterol noted among carriers. In addition to age and carrier status, the potentially reversible conditions, obesity, hyperinsulinemia and lipid-raising drug use were contributory. Thus heterozygous lipoprotein lipase deficiency, together with age-related influences, may account for a form of familial hypertriglyceridemia.
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PMID:Phenotypic expression of heterozygous lipoprotein lipase deficiency in the extended pedigree of a proband homozygous for a missense mutation. 239 28

Hypothyroidism is a major cause of secondary hypercholesterolemia. Amiodarone treatment alters both the levels of serum lipids and thyroid hormones. We investigated whether the amiodarone-induced changes in lipid metabolism are related to the changes in thyroid hormone levels. Eighteen patients received amiodarone (31 +/- 3 g cumulative dose) for six weeks. Serum triglyceride, total-cholesterol, high density lipoprotein-cholesterol and its subfractions, apolipoproteins B and AI, and plasma post-heparin lipoprotein lipase and hepatic triglyceride lipase activities were determined. Amiodarone treatment caused significant increases in serum total-cholesterol (baseline 4.4 +/- 0.21 (SE), 6 weeks 5.12 +/- 0.26 mmol/l, P less than 0.01), in low density lipoprotein cholesterol (baseline 2.61 +/- 0.26, 6 weeks 3.36 +/- 0.21 mmol/l, P less than 0.05) and in apolipoprotein B (baseline 1.95 +/- 0.15, 6 weeks 2.26 +/- 0.13 mmol/l, P less than 0.01) concentrations. Serum high density lipoprotein and its subfractions, or apolipoprotein AI levels did not change. Plasma post-heparin lipoprotein lipase activity increased (baseline 137 +/- 21, 6 weeks 168 +/- 21 U/ml, P less than 0.01) while hepatic triglyceride lipase did not change. Amiodarone also caused an increase in serum thyroxine (baseline 110 +/- 8, 6 weeks 136 +/- 6 mmol/l, P less than 0.05), although values remained in euthyroid range. In summary, amiodarone therapy increased the concentrations of atherogenic lipoproteins in the serum similar to that seen in hypothyroidism. On the other hand the effect of amiodarone on lipoprotein lipase was opposite to that seen in hypothyroidism. Therefore, amiodarone-induced changes in lipid metabolism cannot be explained solely on the basis of the changes in circulating thyroid hormone levels.
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PMID:Amiodarone-induced changes in lipid metabolism. 240 48

Factors affecting the association of apolipoprotein E (apoE) with human plasma very low density lipoprotein (VLDL) were investigated in experiments in which the lipid content of the lipoprotein was modified either by lipid transfer in the absence of lipolysis or through the action of lipoprotein lipase. In both cases, lipoprotein particles initially containing no apoE (VLDL-E), isolated by heparin affinity chromatography, were modified until they had the same lipid composition as native apoE-containing VLDL (VLDL+E) from the same plasma. Transfer-modified lipoproteins, unlike native VLDL+E, did not bind apoE or interact with heparin. In contrast, VLDL-E, whose lipid composition was modified to the same extent by lipase, bound apoE and bound to heparin under the same conditions as native VLDL+E. A structural protein (apolipoprotein B) epitope characteristic of VLDL+E was expressed during lipolysis prior to ApoE or heparin binding. The data suggest that the reaction of apoE with VLDL-E is a two-step reaction. The appearance of apoB is modified during lipolysis, with expression of a major heparin-binding site. The modified VLDL then becomes competent to bind apoE. The lipid composition of VLDL appears not to be a major factor in the ability of VLDL to bind apoE or to bind to heparin.
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PMID:A change in apolipoprotein B expression is required for the binding of apolipoprotein E to very low density lipoprotein. 244 29

Twenty-five CAPD patients were given gemfibrozil in increasing doses for a total of 14 weeks. Parameters of lipid metabolism including serum total cholesterol, LDL cholesterol, HDL cholesterol, HDL2 cholesterol, HDL3 cholesterol triglyceride, apolipoprotein A-1, apolipoprotein B, postheparin lipoprotein lipase, and hepatic lipase activities were measured before the commencement, at every increment in the dose of gemfibrozil and 4 weeks after discontinuation of therapy. Gemfibrozil normalized the deranged parameters of lipid metabolism. Thus, with treatment, serum triglyceride, and total cholesterol, LDL cholesterol and apo B decreased, whereas serum HDL cholesterol, HDL2, and HDL3 (predominantly the latter subfraction), hepatic lipoprotein lipase activities increased. Apo A-1 did not change significantly. Even in normotriglyceridemic patients serum HDL cholesterol increased. The side effects consisted of muscle aches and a significant rise in serum CPK. Gemfibrozil produced a significant decrease in gamma-GT activities. A possible mechanism for the interconversion between HDL2 and HDL3 that resulted in a preferential increase in the latter was discussed. It was concluded that gemfibrozil, in a dose not exceeding 300 mg twice a day favorably improved the risk factor for ischemic heart disease in CAPD patients.
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PMID:Gemfibrozil improves abnormalities of lipid metabolism in patients on continuous ambulatory peritoneal dialysis: the role of postheparin lipases in the metabolism of high-density lipoprotein subfractions. 250 77

In 21 non-insulin-dependent diabetic patients with secondary drug failure, once-daily long-acting insulin lead to a moderately improved metabolic control. At the conclusion of the study (eight months) the fasting blood glucose and HbA1c concentrations were significantly decreased, but the postprandial blood glucose concentrations in the afternoon were unaltered. The peripheral insulin sensitivity, as measured by the intravenous insulin tolerance test, and the lipoprotein lipase activity in adipose and skeletal muscle tissue had increased. After initiation of insulin therapy there was a transient decrease of the fasting and glucagon-stimulated C-peptide concentrations. The very low density lipoprotein lipids and apolipoprotein B, A-I and A-II were also reduced transiently. The only significant difference in lipoprotein composition at eight months compared with on admission, was an increased cholesterol and decreased triglyceride concentration in the high density lipoproteins. There were significant relationships between the C-peptide, but not the peripheral insulin, concentrations and the serum lipid concentrations. This may indicate that high peripheral insulin concentrations after administration of exogenous insulin may affect the hepatic lipoprotein production less than the portal insulin concentrations mainly derived from endogenous production.
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PMID:C-peptide but not insulin concentrations are related to the serum lipoprotein levels during insulin treatment of non-insulin-dependent diabetes mellitus (NIDDM) patients. 269 85


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