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)

An investigation was undertaken to determine which plasma factors from normal controls and patients with chronic renal failure (CRF) exert have inhibitory effects on the activity of lipoprotein lipase (LPL) purified from heparinized human plasma by using an accurate LPL assay system. Inhibitors of LPL were found to be present in the plasma. The inhibition of the LPL activity was significantly greater in CRF patients than in normal controls. Following hemodialysis (HD), the same concentration of uremic plasma led to less inhibition. The inhibitors existed only in lipoprotein deficient plasma (LPDS), which demonstrated an LPL-inhibitory activity at extremely high concentrations with a significant difference between the patients and normal controls. There was no difference between the two groups at low concentrations. A specific inhibitory effect on LPL in LPDS was noted in the 7S and 4S fractions separated by gel filtration employing Sephacryl S-200 column chromatography. The inhibitory effect of the 7S fraction was found to be dependent on the concentration, and the difference between the two groups was similar to that for LPDS. The results obtained in the present study suggest that the plasma from CRF patients exhibited a strong inhibitory action on the LPL activity as compared to the plasma from normal controls, and the inhibitory action was due primarily due to poor excretion of dialyzable inhibitors.
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PMID:Study on the inhibitory effect of uremic plasma on lipoprotein lipase. 147 35

We measured lipoproteins, apolipoproteins, lipoprotein lipase (LPL), hepatic triglyceride lipase (HTGL), lecithin: cholesterol acyltransferase (LCAT) and parameters of calcium metabolism to evaluate the roles of these enzymes and hypertriglyceridemia for impaired high-density lipoprotein (HDL) metabolism in chronic renal failure, and to examine the impact of altered calcium homeostasis on the lipoprotein-regulating enzymes. The subjects were 25 healthy volunteers and 66 uremic patients, 24 treated with hemodialysis (HD) and 42 with continuous ambulatory peritoneal dialysis (CAPD). Lipoprotein analysis revealed: (1) reduction in HDL cholesterol especially in HDL2 subfraction; (2) increase in HDL triglyceride; and (3) decreased ratio of HDL2 cholesterol to HDL3 cholesterol in both HD and CAPD patients. Simple regression analysis showed: (1) a positive correlation between VLDL triglyceride and triglyceride/cholesterol ratio of HDL; (2) positive correlations of LPL level in post-heparin plasma to cholesterol concentrations in HDL2, HDL3 and total HDL, and to apolipoproteins A-I and A-II; and (3) inverse correlations of HTGL to HDL2 cholesterol and to the ratio of HDL2 cholesterol/HDL3 cholesterol. Multiple regression analysis of HDL cholesterol indicated positive association with LPL and inverse correlation with VLDL triglyceride. Four variables including LPL, HTGL, LCAT and VLDL triglyceride explained 51.5% of the variation of HDL cholesterol. HDL2 cholesterol was associated positively with LPL and negatively with VLDL triglyceride in the model. HDL3 cholesterol was associated positively with LPL, HTGL and LCAT and inversely with VLDL triglyceride. Stepwise multiple regression analysis indicated that independent predictors of HTGL were gender, parathyroid hormone levels by a mid-portion assay, ionized calcium and age, and that those of LCAT were ionized calcium and age.(ABSTRACT TRUNCATED AT 250 WORDS)
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PMID:Impaired metabolism of high density lipoprotein in uremic patients. 150 22

Dyslipidemia of chronic renal failure is of multifactorial origin. Decreased activity of lipoprotein lipase and hepatic triglyceride lipase, peripheral insulin resistance, hyperparathyroidism and L-carnitine deficiency are the contributing factors. This results in a disturbed catabolism of chylomicron, accumulation of very-low-density (VLDL) and intermediate-density (IDL) lipoproteins as well as incompletely cleared remnant particles, whereas low-density lipoprotein (LDL) levels are diminished. There is current debate as to whether cardiovascular disease is accelerated and whether hyperlipidemia should specifically be treated. In addition, there have been few means of influencing these metabolic alterations. Drug incompatibility and consequently side effects render treatment difficult. The drugs that have been most tested for lipid lowering in chronic renal failure are the fibric acids. By their mode of action, they are the logical choice. Dose reduction overcomes major side effects such as myopathy and rhabdomyolysis. The second generation of fibric acid derivatives (gemfibrozil and beclobrate) show several advantages over formerly used derivatives. Treatment with lovastatin and simvastatin appears to be safe and is recommended in a minority of patients with predominantly elevations of LDL. HMG-CoA reductase inhibitors also lower remnant particles effectively in hemodialysis (HD) patients. L-Carnitine and low-molecular-weight heparin have been shown to influence VLDL rich in triglycerides in a subset of patients on HD. In posttransplant hyperlipidemia, diet remains the first course of action in all patients. When this approach fails, the new lipid-lowering agents, especially fibric acids, appear to be safe in short-term studies in azathioprine- and ciclosporin-treated patients. Lovastatin has been shown to be safe in stable renal transplant patients. Its toxicity seems to depend mainly on high ciclosporin whole blood through or plasma levels.
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PMID:Hyperlipoproteinemia in chronic renal failure: pathophysiological and therapeutic aspects. 186 98

Accelerated atherosclerosis is a serious complication of chronic renal failure (CRF) treated by peritoneal dialysis. In order to study the pathological mechanisms underlying its development we are using an animal model, namely the C57BL/6J mouse, which develops foam cell-type atherosclerotic lesions after surgical induction of CRF. During atherogenesis, monocyte/macrophages move from the circulation to the blood vessel wall, migrate through the endothelium, imbibe lipid and transform into foam cells. Migration through the endothelium involves proteolysis by plasminogen activator (PA) and uptake of lipids involves hydrolysis of lipoproteins by lipoprotein lipase (LPL). Both of these enzymes are secreted by macrophages. In this paper we report the results of studies on the effect of uremia on the secretion of PA and LPL by macrophages from C57BL/6J mice. The secretion of PA and LPL by macrophages from uremic mice (as defined by BUN levels) was higher than that by cells from control animals. Furthermore, whereas macrophage secretion of PA and LPL was significantly less in normal mice fed a high fat diet than in mice fed rodent chow, it was increased above control levels in uremic animals fed the atherogenic diet. We conclude that increased secretion of PA and LPL by macrophages may contribute to atherogenesis in uremic C57BL/6J mice.
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PMID:Macrophage secretory activity and atherosclerosis during chronic renal failure. 198 12

A substantial number of patients with chronic renal failure display type IV lipoproteinemia. They have elevated serum levels of very-low-density, intermediate-density, and low-density lipoprotein. Serum cholesterol levels are usually normal and those of high-density lipoprotein are low. It is generally accepted that hypertriglyceridemia is due to decreased removal from the blood secondary to reduced activity of lipoprotein lipase and hepatic lipase. Secondary hyperparathyroidism and elevated blood levels of parathyroid hormone (PTH) may play an important role in the pathogenesis of the triglyceridemia of chronic renal failure. Indeed, parathyroidectomized-normocalcemic dogs with chronic renal failure have normal serum levels of triglyceride, normal fat tolerance, and normal post-heparin lipolytic activity. Available data indicate that the abnormalities in carbohydrate and lipid metabolism in chronic renal failure are linked. Excess PTH suppresses insulin release from pancreatic islets, and the insulin deficiency results in carbohydrate intolerance. Insulin deficiency also causes decreased synthesis of lipoprotein lipase and hence abnormal lipid metabolism. Thus, the hyperparathyroidism of chronic renal failure may play a paramount role in the genesis of the abnormal metabolism of both carbohydrates and lipids.
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PMID:Lipid abnormalities, renal failure, and parathyroid hormone. 248 46

In the past we have shown that patients with chronic renal failure (CRF) on hemodialysis show evidence of intestinal malabsorption of fat. The present study was designed to verify this finding in an animal model. Male rats weighing +/- 200 g were studied. Uremia (U) was induced by 2-stage subtotal (5/6) nephrectomy. Control (C) animals were sham-operated. Fat absorption was studied after 6 weeks of uremia with the oral fat loading test. Twenty percent intralipid (0.25 g/100 gBW) was given by gastric tube feeding to fasting animals and the appearance of chylomicrons (CHYL) and the rise of triglycerides (TG) in the serum was followed for 5 hrs. In order to isolate the effect of fat absorption, an additional group of U and C animals was pretreated with orotic acid and triton, thus blocking hepatic TG synthesis and neutralizing peripheral lipoprotein lipase activity. The absorption of CHYL was significantly (p less than 0.01) impaired in all U animals and averaged 43 and 70 percent of that of the C animals, 1 and 2 hrs after the load respectively. The rise in serum TG did not differ from C in mildly U animals (Scr 1.0 +/- 0.04). In the more severely uremic animals (Scr 2.6 +/- 0.2), however, pretreated with orotic acid and triton, the rise in serum TG was far less (p less than 0.01) than in C animals (111 +/- 26-903 +/- 111 delta % V.780 +/- 170-5032 +/- 746 delta %) 1 and 5 hrs after the load.(ABSTRACT TRUNCATED AT 250 WORDS)
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PMID:Intestinal fat malabsorption in the uremic rat. 342 36

To define the role of insulin in lipid disturbances of chronic renal failure, chronically uremic rats (U+) were supplemented by continuous insulin infusion over a 35-day experimental period and compared with control ad libitum-fed rats (C) and uremic rats without insulin (U). Uremic rats were characterized by hypoinsulinemia, an increase in both circulating very low-density lipoprotein (VLDL) and their cholesterol concentration, a normal hepatic triglyceride secretion rate (TGSR) determined with Triton WR 1339, and a low adipose tissue lipoprotein lipase (LPL) activity. Chronic insulin infusion at low rate (0.5 IU/24 h) to U+ rats normalized serum insulin (from 17.0 +/- 0.6 mU/l in U rats to 23.4 +/- 1.7 mU/l in U+ rats), serum VLDL triglycerides (from 804 +/- 65 to 410 +/- 36 mg/l), and serum VLDL cholesterol (from 43 +/- 8 to 16 +/- 3 mg/l). Hepatic TGSR decreased significantly after insulin treatment (from 0.58 +/- 0.03 to 0.44 +/- 0.03 mumol/min). Moreover, adipose tissue LPL was restored to normal by insulin supplementation (from 460 +/- 60 to 860 +/- 150 mU per total epididymal fat in U and U+ rats, respectively). Correction of the disturbed VLDL metabolism was associated with multiple actions of insulin including 1) a decrease of peripheral lipolysis, 2) a decrease of hepatic TGSR, and 3) an increase of adipose tissue LPL activity. Because cholesterol-rich VLDL are potentially atherogenic, their normalization with insulin treatment in this animal model suggests a viable area of investigation for the prevention of accelerated atherogenesis in chronic renal failure.
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PMID:Correction by insulin of disturbed TG-rich LP metabolism in rats with chronic renal failure. 351 62

The present study was performed to appreciate the potential role that thyroid deficiency could play in the energy homeostasis and lipid metabolism of experimental chronic renal failure. For this purpose, 12 uremic rats that were supplemented with T3 (0.4 microgram/100 g body weight/day) during 5 weeks by means of osmotically driven minipumps were compared to 12 unsupplemented uremic rats and 12 control rats. The chronic supplementation of uremic rats with T3 induced no significant change in body weight gain or in the serum concentration of insulin, glucose, glycerol, nonesterified fatty acids, total triglycerides (TG), total cholesterol, and total choline phospholipids. Similarly, the metabolism of TG-rich lipoproteins was not affected by the supplementation with T3 in these uremic rats as appreciated by TG production or TG degradation (adipose tissue lipoprotein lipase activity). T3 administration induced a significant decrease in serum beta-hydroxybutyrate concentration and an increase in serum lactate concentration. Furthermore, heparin-releasable hepatic TG lipase activity as expressed per total liver mass was decreased in uremic rats treated with T3. The latter changes were observed in the absence of modifications of serum glucose or TG concentration. We conclude from these observations that rats with a moderate degree of chronic uremia do not seem to have a cellular thyroid deficiency sufficient to disturb their energy or lipid metabolism.
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PMID:Chronic triiodothyronine supplementation does not improve the lipoprotein disorders of mildly uremic rats. 355 Apr 97

The possible mechanisms of the increase in serum triglycerides (TG) and TG-rich lipoproteins were studied in chronically uremic (U) rats by comparison with either ad-lib fed control (C) rats or diet-restricted (DR), sham-operated pair-fed control rats. A first series of animals was studied in the fed state and a second series after a 16-hr fast. In U animals the concentration of serum TG and TG-rich particles was lower than that of C rats in the fed state but significantly higher than that of C and DR rats after a 16-hr fast. Serum glucose and lactate concentrations in the fed or fasted state were unchanged by uremia. Serum insulin concentration was significantly decreased in U rats as compared to C and DR rats in both series. The fast did not increase the concentration of serum nonesterified fatty acids (NEFA) in U or DR animals to the same extent as in C rats, whereas the serum concentration of beta-hydroxybutyrate (BOB), which was higher than that of C rats in the fed state, was significantly lower after a 16-hr fast. In U animals, as compared to control rats of either series, a significant decrease of epididymal lipoprotein lipase (LPL) activity was observed during both nutritional states when expressing the enzymic activity per number of cells. In conclusion, our data provide evidence against hepatic over-production of TG-rich lipoproteins in rats with chronic renal failure and strongly point to an LPL-mediated defect of their peripheral catabolism, probably related to the insulin deficiency state.
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PMID:Factors of increase in serum triglyceride-rich lipoproteins in uremic rats. 388 97

Total post-heparin lipolytic activity (PHLA), hepatic triglyceride lipase (HTGL) and protamine inactivated lipoprotein lipase (LPL) and plasma lipoprotein pattern were investigated in 8 patients with acute renal failure (ARF). PHLA was determined at 5, 10, 15, 30, 45 and 60 minutes after heparin administration (100 U/kg b.w.). Maximal PHLA in ARF was 6.12 +/- 1.56 mumol FFA/ml/h at 10 minutes versus 14.62 +/- 4.29 at 45 min in controls (= 42%, p less than 0.001). PHLA was reduced in ARF throughout the study period (p less than 0.001). Maximal HTGL activity (3.06 +/- 0.84 mumol FFA/ml/h) was obtained at 10 min in ARF versus 8.97 +/- 3.11 after 15 min in controls (= 34%, p less than 0.001). HTGL in ARF differed from controls at all points of determination (p less than 0.001). LPL maximum was 3.12 +/- 1.93 mumol FFA/ml/h at 15 min in ARF and 7.65 +/- 3.44 at 45 min in controls (= 40%, p less than 0.001). LPL activity was different from controls at 30, 45 and 60 min (p less than 0.001) but not at 5, 10 and 15 min after heparin injection. Due to a rapid decrease of LPL activity (half maximal activity after 34 min in ARF versus 94 min in controls, p less than 0.05) activity half life of PHLA was diminished in ARF (49 min in ARF versus 112 min in controls, p less than 0.01). Thus both the activity of HTGL and LPL is impaired in ARF. Because of the different activation kinetics of the two PHLA fractions no conclusions concerning maximal enzyme activities can be drawn from single determinations as suggested in previous studies on chronic renal failure.
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PMID:Post-heparin lipolytic activity in acute renal failure. 402 26


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