Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts: Gene/Protein Disease Symptom Drug Enzyme Compound   Target Concepts: 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)

Lipoprotein lipase activity was measured at short time intervals in cardiac and skeletal muscles of normal and streptozotocin-treated diabetic rats fed ad libitum or deprived of food. In normal animals fed ad libitum, lipoprotein lipase activities of heart, diaphragm, soleus, and fast-twitch red fibers of the quadriceps muscle showed rhythmic oscillations that appeared to coincide with the nocturnal feeding habits of the animals. During the day (7 A.M. to 7 P.M.), when food consumption by the rats was greatly reduced, lipoprotein lipase activity in all muscles increased, followed by a decline to basal levels during the night. Similar oscillatory changes in lipoprotein lipase activity were observed in the muscles of diabetic rats fed ad libitum. In normal rats deprived of food, however, the oscillatory changes in muscle lipoprotein lipase activity were not abolished and persisted for at least 48 h. In diabetic rats starved during a 48-h period, the oscillatory changes in muscle lipoprotein lipase activity were markedly altered. In all animals, muscle lipoprotein lipase activities were not correlated to plasma glucagon levels.
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PMID:Oscillatory changes in muscle lipoprotein lipase activity of fed and starved rats. 14 95

In a study of the aetiopathogenesis of primary hyperlipoproteinaemias, which has not yet been elucidated, we paid attention to the heparin-activated lipolytic enzymes. Lipoprotein lipase (LPL) and postheparin esterase (PHE) activity was determined in 35 patients with primary hyperlipoproteinaemia (HLP) type IV (average age 50 years), 28 with type V (average age 48 years) and 2 with type III (57 and 62 years). Since PHE activity is correlated to sex and in women also to age, these factors had to be taken into account. The average activity values for the given enzymes in the patients group did not differ from the results in the control group. From these enzymes activities we tried to analyse the findings in individual cases in which the values were lower or higher than the control group range. The low PHE activity in some patients with type IV and V was evidently secondary and due to hepatobiliary disorder (most frequently liver steatosis). The simultaneous elevation of LPL and PHE activity in type IV and V patients with a high serum lipoprotein concentration shows that the response of patients with extreme HLP to heparin is more pronounced. The low PHE activity in type III (tested in only 2 patients) could possibly indicate the liver disorder on which this metabolic disease may be based.
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PMID:Lipoprotein lipase and postheparin esterase activity in primary hyperlipoproteinaemia type IV and V. 20 76

Hepatic lipase activity and lipoprotein lipase activity were studied in postheparin plasma from 14 patients with various liver disorders. Plasma lecithin: cholesterol acyltransferase (LCAT) activity and lipoprotein composition and structure were also estimated. Five patients had lower hepatic lipase activity than the lowest control value, and in three of these no hepatic lipase activity was detected. Lipoprotein lipase was low in 5 patients, but in only one of them was hepatic lipase activity also low. Hepatic lipase was not significantly correlated to the concentration of plasma triglycerides, either in controls or in patients, whereas lipoprotein lipase was negatively correlated with plasma triglycerides both in controls and patients. Lipoprotein lipase and LCAT activity, but not hepatic lipase, was negatively correlated to the triglyceride content of the low density lipoproteins (density 1.019-1.063 g/ml) from the patients. No specific lipid or lipoprotein pattern was found in plasma from the patients with a low or without any hepatic lipase activity. The results suggest an important role of lipoprotein lipase and LCAT, for the increased content of triglycerides in the low density lipoproteins in patients with liver disease. The role of hepatic lipase remains unclear.
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PMID:Triglyceride lipase activity in postheparin plasma and plasma lipoproteins in liver disease. 20 7

The influence of purified human apolipoprotein C-II on phospholipase A1 and triglyceridase activities of lipoprotein lipase were compared. Lipoprotein lipase was obtained from rat hearts by perfusion with a medium containing heparin and purified on a heparin Sepharose 4-B column. Using phosphatidyl-ethanolamine-coated triglyceride particles as substrate it was found that the phospholipase A1 and triglyceridase activities of lipoprotein lipase similarly depend on the presence of apolipoprotein C-II. Apolipoprotein C-III cannot replace apolipoprotein C-II. However, addition of apolipoprotein C-III in the presence of C-II affects both lipase activities. While strong inhibition of triglyceridase activity was observed under these conditions, phospholipase A1 activity was slightly stimulated. On the basis of these findings a model was constructed for the role of apolipoprotein C-II in lipoprotein lipase action.
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PMID:Triglyceridase and phospholipase A1 activities of rat-heart lipoprotein lipase. Influence of apolipoproteins C-II and C-III. 21 Aug 32

A clonal cell line that responds to insulin and to lipolytic hormones has been established from the epididymal fat pad of the C57BL/6J ob/ob mouse. This line, designated ob 17, has a doubling time of 12.5 or 19 hr in 10% or 1% fetal calf serum, respectively. It presents a heterogeneous chromosome number with 40% of the cells containing 35-44 chromosomes and expresses the characteristic H2-LA antigen. After cessation of growth, ob 17 cells accumulate droplets of triglycerides; this accumulation occurs to a significant extent even in the absence of insulin normally added after confluence. Lipoprotein lipase activity is negligible in exponentially growing cells but appears at its maximal level just after confluence with or without insulin. Acid:CoA ligase and acylCoA:diglyceride acyltransferase develop later than lipoprotein lipase. The appearance of lipolytic and lipogenic enzymes, but not of triglycerides, seems to be independent of the presence of lipoproteins or of unesterified fatty acids in the culture medium. Therefore, the differentiation program becomes operative when growth is arrested, and differentiation occurs, providing a source of exogenous lipids. Differentiated ob 17 cells in which endogenous triglycerides have been prelabeled on the fatty acid moiety do respond to epinephrine and corticotropin by release of radioactive fatty acid. This lipolytic response is counteracted by prior addition of insulin. The ob 17 cell line appears to be a useful model for study of growth and differentiation of adipose cells as compared to preadipocyte cell lines from the nongenetically obese mouse.
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PMID:Establishment of preadipocyte clonal line from epididymal fat pad of ob/ob mouse that responds to insulin and to lipolytic hormones. 21 11

Lipoprotein lipase activity was studied in rat heart cell cultures grown in the presence of 20% fetal calf and horse serum and a medium concentration of triacylglycerol of 0.03 mg/ml. After 6--8 days, when the enzyme activity had reached high levels, the cells were incubated for 24 h in a medium containing 20% serum derived from fasted or fed rats. No change in enzyme activity occurred in the presence of fasted rat serum, but a 50% fall was observed with fed rat serium. When the complete culture medium was supplemented with rat plasma VLDL (0.075--0.75 mg triacylglycerol) a pronounced decrease in lipoprotein lipase activity occurred after 3--5 h of incubation. Similar extent of enzyme fall was observed also in the presence of triacylglycerol-rich lipoproteins isolated from rat plasma after feeding of safflower oil or lard, even though the fatty acid composition of the triacylgylcerol varied markedly. As the addition of VLDL to the culture medium resulted in a lesser fall of heparin releasable than residual activity it seems that there was no direct inhibition of surface bound enzyme activity and that the transport of the enzyme to the cell surface was not affected. These data indicate that addition of VLDL to the culture medium resulted in a fall in enzyme synthesis, while total protein synthesis as determined by incorporation of [3H]leucine, remained unchanged. This inhibition could be reproduced by increasing free fatty acid concentration of the medium, however addition of excess albumin to VLDL-containing medium did not prevent the fall in enzyme activity. The present results obtained with cultured rat hearts cells suggest that in vivo plasma levels of triacylglycerol-rich lipoproteins could modulate the lipoproteins could modulate the lipoprotein lipase activity of the heart.
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PMID:Lipoprotein lipase of cultured mesenchymal rat heart cells. IV. Modulation of enzyme activity by VLDL added to the culture medium. 22 46

Human fibroblast cells in culture increased their intracellular triacylglycerol levels when exposed to very low density lipoproteins (VLDL) isolated from human plasma. This response was dependent on the amount of VLDL added. VLDL from normal, type IV or type V sera gave similar results. Lipoprotein lipase enhanced this intracellular triacylglycerol accumulation. It was concluded that human fibroblast cells in culture have at least two mechanisms for triacylglycerol uptake from VLDL: (1) uptake from intact lipoprotein either by surface transfer of lipoprotein lipid or internalization of the entire lipoprotein particle, and (2) re-esterification of lower glyceride and fatty acids released by lipoprotein lipase degradation of VLDL.
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PMID:Cell triacylglycerol accumulation from very low density lipoproteins isolated from normal and hypertriglyceridemic human sera. 22 56

1. Lipoprotein lipase activity of the abdominal fat pad and hepatic triacylglyceride synthetase activity were determined at 2, 7.5, 9, 12.5 and 20 weeks of age. 2. Specific activity of lipoprotein lipase in fat pad was constant at 2-9 weeks, decreasing until 20 weeks. Hepatic triacylglyceride synthetase activity decreased from 2 to 12.5 weeks, increasing by 20 weeks. 3. Lipoprotein lipase activity was higher throughout 20 weeks and triacylglyceride synthetase activity was higher at 7.5 weeks with energy restricted diet. 4. An inverse relationship existed between fat pad weight and specific activity of lipoprotein lipase; higher activity in adipose tissue of energy restricted pullets may have been a function of smaller fat pad size.
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PMID:Influence of diet on adiposal lipoprotein lipase and hepatic triacylglyceride synthetase activities in the developing pullet (Gallus domesticus). 31 70

Needle biopsies of adipose tissue and blood samples were obtained before and at short intervals after a "bolus" injection of 10% Intralipid. Lipoprotein lipase activities were measured in acetone--ether extracts of the tissue samples. Levels of serum triglyceride began to fall less than 5 min after the injection of the Intralipid with a half-life of 20 min. During this time interval, no significant changes were observed in the activities of lipoprotein lipase in adipose tissue. A patient with a severe hypertriglyceridaemia (Type V) underwent plasma exchange with a reduction in serum triglyceride levels from 11 to 4 mm/l. There was a parallel fall in adipose tissue lipoprotein lipase activity. We conclude that lipoprotein lipase in adipose tissue is unaltered during experimental hypertriglyceridaemia and that the activity of the enzyme in adipose tissue is probably not reduced as a secondary feature of an elevated plasma triglyceride level.
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PMID:Lipoprotein lipase activity in human adipose tissue during induced hypertriglyceridaemia. 47 83

1. Subcellular fractions, characterized by using morphological, compositional and enzymic markers, were prepared from rat heart tissue and cells isolated from the hearts of fed and 24 h-starved rats. 2. The lipoprotein lipase activity of fractions from whole tissue and isolated cells was determined in either fresh fractions or in acetone/diethyl ether powders of the fractions. 3. Lipoprotein lipase activity was present in all the fractions from tissue and cells, but was found to be of highest relative specific activity in the microsomal () fractions. 4. In fractions prepared from the isolated cells of hearts from starved rats the proportion of the total lipoprotein lipase present and its relative specific activity in the microsomal fraction were greater than in the equivalent fractions from fed animals. 5. The enhancement of lipoprotein lipase activity as a result of the acetone/diethyl ether powder preparation of fractions was most extensive in the microsomal fractions. 6. Investigation of the microsomal fraction showed that the lipoprotein lipase activity present was in two pools, one of which was within endoplasmic-reticulum vesicles. 7. The observations were consistent with the possibility that the cardiac-muscle cell could be the origin of the lipoprotein lipase activity functional in triacylglycerol uptake by the heart.
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PMID:Lipoprotein lipase activity of rat cardiac muscle. The intracellular distribution of the enzyme between fractions prepared from cardiac muscle and cells isolated from the hearts of fed and starved animals. 48 63


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