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Biomedical subjects

T Kuusi

Publications and source records attributed to T Kuusi.

At least 91 records · Page 5Linked to original sources
PubMed1981

Effect of probucol on the activity of postheparin plasma lipoprotein lipase and hepatic lipase.

The effect of discontinuation of long term (34-56 months) probucol treatment on serum lipids, lipoproteins and on the activity of postheparin plasma lipoprotein and hepatic lipase ahs been studied in 10 healthy males participating in a primary prevention programme of coronary heart disease. A significant increase was observed in the activity of postheparin plasma lipoprotein lipase, in the total serum cholesterol concentration and in the serum concentrations of high density lipoprotein (HDL) cholesterol, HDL phospholipids and apoprotein AI after withdrawal of the drug No changes were seen in the serum triglyceride levels or in the activity of postheparin plasma hepatic lipase. The activity of postheparin plasma hepatic lipase tended to correlate with the serum concentration of HDL. No correlations were present between the individual changes in the serum levels of HDL and in the activity of postheparin plasma triglyceride lipases.

Apolipoprotein A-I↗
PubMed1981

Reduction of plasma high-density lipoprotein cholesterol and increase of postheparin plasma hepatic lipase activity during progestin treatment.

Twenty-seven menopausal women were given the synthetic progestin levonorgestrel for two weeks. The mean plasma high-density lipoprotein (HDL) cholesterol concentration decreased from 1.32 mmol/l to 1.01 mmol/l (p less than 0.001) during treatment. This was due to the selective reduction in plasma HDL2 cholesterol from 0.73 mmol/l to 0.44 mmol/l, whereas the plasma HDL3 cholesterol was not changed. The mean hepatic lipase (HL) activity of postheparin plasma increased from 20.6 to 35.3 mumol.h-1.ml-1 (p less than 0.001) while the lipoprotein lipase (LPL) activity was not changed. A significant inverse correlation existed between the HDL2 cholesterol concentration and HL activity both before (r=-0.49, p less than 0.01) and after (r=-0.39, p less than 0.05) treatment, and a significant correlation was observed between the changes in these two variables (r=0.39, p less than 0.05). These results are compatible with the hypothesis that HL participates in the regulation of plasma HDL2 levels and they suggest that progestin treatment reduces plasma HDL2 cholesterol concentration by increasing the hepatic lipase activity. It is not known whether this type of HDL2 reduction is accompanied by increased atherogenesis but as long as the issue is unresolved some caution is needed in the long-term use of levonorgestrel, particularly in women who simultaneously are given some other drug depressing plasma HDL2 concentration.

Cholesterol↗
PubMed1980

Post-heparin plasma lipoprotein and hepatic lipases. Relationships to high density lipoprotein cholesterol and to apolipoprotein CII in familial hyperalphalipoproteinemic and in normal subjects.

Post-heparin lipoprotein lipase (PH-LPL)-high density lipoprotein cholesterol (HDL-C) interrrelationships were assessed in 9 subjects with documented familial hyperalphalipoproteinemia (FHA) and in 8 controls to focus on potential biochemical etiologies of FHA and relationships of HDL-C to triglyceride hydrolysis and PH-LPL. FHA subjects had mean HDL-C and HDL2-C levels > twice controls; their PH-LPL levels (mean +/- SEM) (3.14 +/- 2.3 mumol FFA/h/ml) were also > twice that of controls (15.0 +/- 1.6) (P < 0.01), but post-heparin hepatic lipase levels (PH-HL) in the FHA and control subjects did not differ (18.1 +/- 1.6 vs 26.6 +/- 4.3, P > 0.1). For all subjects (FHA and controls) PH-LPL was positively correlated with HDL-C (r = 0.79, P < 0.01) and with HDL2-C (r = 0.90, P < 0.01), but not with HDL3-C (r = --0.02). There were no significant PH-HL and HDL-C interrelationships, P > 0.1. The amount of apo CII (the primary activator of PH-LPL) in HDL2 was greater in the FHA (mean +/- SEM) (16.1 +/- 2.5 microgram/ml plasma) than in control subjects (4.7 +/- 0.9, P < 0.01). There were strong positive correlations between HDL2 apo CII and both PH-LPL (r = 0.79, P < 0.01) and HDL2-C (r = 0.80, P < 0.01). Apo CII as a percentage of HDL2 protein was higher in FHA than control subjects (mean +/- SEM) (1.2 +/- 0.3% vs 0.5 +/- 0.2%, P < 0.01). Apo CII as a percentage of HDL3 protein was similar in FHA and control subjects. We postulate that increased turnover rate of triglyceride-rich lipoproteins due to high LPL activity may be an important factor leading to the elevation of HDL-C in FHA. The highly significant positive correlation between HDL2-C and PH-LPL provides strong clinical evidence for the theory that HDL2 is formed during the hydrolysis of triglycceride-rich lipoproteins. The high concentration of HDL2 apo CII in FHA subjects may be caused by increased catabolism of triglyceride-rich lipoproteins in the presence of high endothelial LPL, with transfer of apo CII from very low to high density lipoproteins.

Adolescent↗
PubMed1980

High density lipoprotein and apolipoprotein A-i during physical inactivity. Demonstration at low levels in patients with spine fracture.

Lack of physical activity appears to have deleterious effects on serum lipoproteins. Twenty-three patients who were completely immobilised by traumatic fracture of the spine had significantly lower (P < 0.001) plasma high density lipoprotein cholesterol (HDL-C) and apolipoprotein A-I levels than normally mobile paired control subjects. The low density lipoprotein cholesterol (LDL-C) levels of the immobile patients were not different from those of controls but the LDL triglyceride (LDL-TG) of the patients was increased. The patients had a significantly higher LDL/HDL-C ratio and HDL-C/apoprotein A-I ratio than the controls. These results suggest that the increased risk of ischemic heart disease in physically inactive people is partially accounted for by low plasma HDL levels. On the other hand, caution is needed in the interpretation of HDL findings in clinical conditions where the physical activity of the patients is limited.

Adolescent↗
PubMed1980

Immunochemical assay of rat postheparin plasma triacylglycerol lipases.

Immunochemical methods for selective measurement of lipoprotein lipase and hepatic lipase activities in rat postheparin plasma are described and validated. Lipoprotein lipase was measured using a substrate containing 10% serum and 0.1 M NaCl after inactivation of hepatic lipase with a specific antiserum. Hepatic lipase was measured at 1.0 M NaCl with a serum-free substrate. The heparin dose-response curve indicated maximum relase of both activities at a heparin dose of 500 IU/kg. The lipase activities in rat postheparin plasma were 3 to 4-fold higher than those in human postheparin plasma. The LPL activity in female rats was significantly higher than in males whereas there was no sex difference for hapatic lipase.

Animals↗
PubMed1980

Evidence for the role of hepatic endothelial lipase in the metabolism of plasma high density lipoprotein2 in man.

Previous animal studies have shown that the heparin-releasable hepatic lipase (HL) is located on the luminal surface of the liver endothelial cells and may have a function in the removal of high density lipoprotein lipids from plasma. We therefore examined the relationship between plasma HDL levels and the HL activity of postheparin plasma in a group of young, very fit men who were living under strictly controlled comparable conditions (military academy studients). HDL2 cholesterol, HDL2 phospholipid and HDL2 protein concentrations each showed a highly significant negative correlation with postheparin HL activity. A similar but slightly lower inverse relationship was also present between total HDL lipids and HL activity, whereas no correlation could be observed between any of the HDL3 lipids and HL activity. The cholesterol/protein ratio of HDL2 correlated negatively with the HL activity. These results support the hypothesis that the hepatic endothelial lipase has a physiological role in the degradation and removal of circulating HDL2.

Adult↗
PubMed1980

Serum and tissue distribution of benzol[a]pyrene from intravenously injected chylomicrons in rat in vivo.

Rats were injected intravenously with chylomicrons (CM) containing benzo[a]pyrene (B[a]P), a carcinogenic aromatic hydrocarbon. The disappearance of B[a]P paralleled the removal of CM, both having a rapid initial decay and a secondary slow decay. After 5 min, at the end of the rapid phase, blood contained 19% of the total injected B[a]P, with 6% in blood cells and 13% in serum. At 60 min, serum contained 5% and blood cells 6% of the total B[a]P. During the slow phase, further distribution of B[a]P within serum albumin and various lipoproteins occurred, most of the label being in low density and very low density lipoproteins. Highest tissue specific activities of [3H]B[a]P were in the lung, liver and kidney tissues. These results suggest that in the rat, distribution of ingested polycyclic aromatic hydrocarbons in vivo tends to be primarily determined by the catabolism of chylomicrons.

Animals↗
PubMed1979

Monoacylglycerol hydrolase in human platelets.

In the present paper we show for the first time monoacylglycerol hydrolase in human platelets. No monoacylglycerol hydrolase activity could be demonstrated in the other blood cells. The monoacylglycerol hydrolase of platelets could not be released from the cells by heparin, thus the enzyme is distinct from the postheparin plasma lipases. The enzyme could be solubilized by a non-ionic detergent, Triton X-100. The solubilized monoacylglycerol hydrolase from platelets was optimally active at pH between 7 and 8 and at ionic strength corresponding to [NaCl] between 0.1 and 0.3 M. The optimal assay temperature was 37 degrees C. The enzyme activity was sensitive to HgCl2 but not to NaF. Accordingly, it was stabilized by 2-mercaptoethanol.

Apolipoproteins↗
PubMed1979

Localization of the heparin-releasable lipase in situ in the rat liver.

Immunofluorescence and immuno-electron microscopy were used for the localization of the heparin-releasable lipase in situ in the rat liver. The lipase is located exclusively on the liver endothelial cells. No labelling could be detected on the parenchymal of Kupffer cells, or in the livers of heparin-pretreated animals. The physiological significance of the endothelial localization of the hepatic lipase is discussed.

Animals↗
PubMed1979

Selective measurement of triacylglycerol lipase activities in pig post-heparin plasma.

Immunochemical methods for the selective measurement of pig post-heparin plasma lipoprotein lipase and hepatic lipase are described and validated. A simple two step purification method for porcine hepatic lipase from hepatic perfusate based on affinity chromatography and gel filtration is reported. The activity of the post-heparin plasma lipoprotein lipase and hepatic lipase in swine is reported. It is demonstrated that fasting decreases the activity of post-heparin plasma lipoprotein lipase activity more than two-fold while it does not affect the hepatic lipase activity significantly.

Animals↗
PubMed1979

Treatment of post-menopausal hypercholesterolaemia with estradiol.

Replacement therapy with estradiol valerate in 29 post-menopausal women reduced low-density lipoprotein (LDL) cholesterol concentrations by 22% and increased high-density lipoprotein (HDL) cholesterol by 21% after 12 months. Apart from a 67% increase of HDL-triglyceride estradiol had only a slight effect on the levels of lipoprotein triglycerides. Post-heparin plasma lipoprotein lipase (LPL) activity was significantly decreased in subjects with normal pre-treatment very-low-density lipoprotein (VLDL) triglyceride levels, and hepatic lipase (HL) activity was significantly decreased in the group as a whole. It is suggested that estradiol replacement therapy should be considered in climacteric women with high LDL-cholesterol or low HDL-cholesterol levels, or both.

Adult↗
PubMed1979

Modification of the substrate specificity of rat hepatic lipase by collagenase treatment.

Collagenase is currently used in the isolation of rat hepatocytes, but it rapidly inactivates the heparin-releasable triacylglycerol lipase of the liver. Since collagenase-isolated liver cells contain a heparin-releasable monoacylglycerol hydrolase, a study was made on the effect of collagenase treatment on the substrate specificity of purified heparin-releasable lipase of rat liver. Incubation of the purified lipase with collagenase selectively decreased the triacylglycerol lipase activity of the enzyme with no effect on the monoacylglycerol hydrolase activity. Gel filtration of the lipase before and after collagenase treatment indicated cleavage of a small molecular weight fragment from the enzyme. This resulted in a preparation with less triacylglycerol lipase activity but still capable of monoacylglycerol hydrolysis.

Animals↗