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Biomedical subjects

M R Taskinen

Publications and source records attributed to M R Taskinen.

At least 235 records · Page 13Linked to original sources
PubMed1982

Lipoprotein lipase activity of adipose tissue, skeletal muscle and post-heparin plasma in primary endogenous hypertriglyceridaemia: relation to lipoprotein pattern and to obesity.

The lipoprotein lipase (LPL) activity was determined from heparin eluates of adipose tissue and skeletal muscle and from post-heparin plasma of sixty-five males with hypertriglyceridaemia and of seventy males with normal serum lipid levels. The patients were subgrouped by their lipoprotein concentrations into types 2b, 4 and 5. The mean LPL activity of adipose tissue (per tissue weight) of nonobese type 2b, 4 and 5 patients was reduced to 54%, 41% and 13%, respectively, of the corresponding value of normolipidaemic men. On the other hand, among obese hyperglyceridaemic men only those with type 5 showed a decreased LPL activity in adipose tissue (44%). The mean skeletal muscle LPL was subnormal in nonobese type 4 (55%) and in type 5 patients (34%) but was normal in type 2b and in obese type 4 patients. The post-heparin plasma LPL activity was significantly reduced in all nonobese hyperglyceridaemic groups but was normal in obese patients apart from cases with type 5 who had low values. One exceptional subject with type 5 had high post-heparin plasma LPL activity. It is concluded that a low LPL activity may be a crucial factor in the pathogenesis of hypertriglyceridaemia in nonobese subjects and in patients having type 5 disorder.

Adipose Tissue↗
PubMed1982

Characterization of lipase activities in obese Pima indians. Decreases with weight reduction.

Adipose tissue and muscle lipoprotein lipase and postheparin hepatic and lipoprotein lipase activities have been measured in a group of 21 Pima Indian males over a wide range of body weight to determine the relationship between obesity and these lipase activities. There was a significant positive correlation between adipose tissue lipoprotein lipase and obesity; muscle and postheparin lipoprotein lipase and hepatic lipase were not related to degree of obesity. Fasting insulin levels were not related to any of the measurements of lipase activity. There were racial differences in adipose and postheparin lipoprotein lipase activities; both were significantly lower in the Pimas as compared with a group of weight-matched Caucasian males. Lipase activities were remeasured in eight subjects after a period of weight reduction including several weeks of stabilization at the reduced weights. After the period of weight reduction adipose tissue lipoprotein lipase declined in all subjects. Hepatic lipase also declined in all but two patients. Muscle and postheparin lipolytic activities were not affected by weight loss. The data indicate that (a) there are racial differences in adipose tissue lipoprotein lipase; and (b) the elevated adipose lipoprotein lipase associated with obesity, like many other biochemical variables in the obese state, returns toward normal after weight reduction.

Adipose Tissue↗
PubMed1982

Effect of parenteral nutrition on the blood levels of insulin, glucagon, growth hormone, thyroid hormones and cortisol in catabolic patients.

The changes in plasma insulin (IRI) glucagon (IRG), IRI:IRG ration, growth hormone (HGH), cortisol and thyroid hormones during two different but isocaloric parenteral nutrition regimens were investigated in 11 malnourished patients and 21 postoperative patients. The nutrition program which used glucose as a non-nitrogen energy source favoured anabolism by a higher rise in plasma IRI and by a higher rise in the initially low plasma IRI:IRG ratio in both malnourished and postoperative patients more than the alimentation regimen with glucose and lipid. The glucose program augmented the IRI:IRG ratio to an average of 5.5 +/- 1.2 (SEM) in malnourished patients and to 8.4+/-2.7 in postoperative patients. The corresponding values for the glucose-lipid program were 3.9+/- 1.0 and 1.9 +/- 0.4. In malnourished patients the difference between the anabolic effect of these nutrition regimens was further increased by a fall in the plasma HGH level to 0.7 +/- 0.3 microgram/l during fat infusion. Over a period of four days both alimentation programs similarly increased in the initially low serum T3 and free T3 index to the normal reference interval and decreased serum rT3 to a subnormal level (0.18+/-0.7 nmol/l) in malnourished patients. In postoperative patients the only change in thyroid hormones which was dependent on the four-day parenteral nutrition was the decrease in the initially elevated serum rT3 to the normal reference interval by both alimentation programs (by 54% in the glucose and by 30% in the glucose-lipid program).

Adult↗
PubMed1981

High density lipoprotein subfractions in relation to lipoprotein lipase activity of tissues in man--evidence for reciprocal regulation of HDL2 and HDL3 levels by lipoprotein lipase.

High density lipoprotein subfractions HDL2 and HDL3 were separated from plasma of 22 normolipidemic healthy human subjects and analyzed for cholesterol, triglyceride, phospholipid and protein. In the same subjects the heparin-releasable lipoprotein lipase activity was assayed from biopsies of adipose tissue and skeletal muscle. A significant inverse correlation was found between the plasma concentrations of HDL2 and HDL3 (4= -0.55, p less than 0.01). The HDL2 cholesterol and HDL2 phospholipid levels were negatively correlated with HDL3 protein levels. The total HDL2 and HDL2 cholesterol, phospholipid and protein concentrations were all positively correlated with lipoprotein lipase activity of both adipose tissue and skeletal muscle. In contrast, the corresponding HDL3 values did not show any correlation with adipose tissue lipoprotein lipase but the HDL3 cholesterol, triglyceride and protein levels were inversely correlated with skeletal muscle lipoprotein lipase activity. The results suggest that plasma HDL2 and HDL3 concentrations are reciprocally regulated by the activity of lipoprotein lipase. THe data are compatible with a concept proposing conversion of HDL3 to HDL2 through assimilation of cholesterol, phospholipids and apoproteins from triglyceride-rich lipoproteins during their degradation by lipoprotein lipase. Particularly the concentration of the HDL2 is closely related to the rat of intravascular lipolysis.

Adipose Tissue↗
PubMed1981

Effect of parenteral hyperalimentation on serum lipoproteins and on lipoprotein lipase activity of adipose tissue and skeletal muscle.

This study reports on the effects of parenteral nutrition with glucose along or in combination with Intralipid on heparin-releasable lipoprotein lipase (LPL) activity of adipose tissue and skeletal muscle and on serum lipoproteins. Thirteen patients with postoperative hypercatabolism and nine patients with caloric malnutrition were studied. The average adipose tissue LPL activity increased 5-fold during 4-day glucose infusion (P less than 0.001) and 7.4-fold during Intralipid plus glucose infusion (P less than 0.001). In contrast, no change occurred in the LPL activity of skeletal muscle. Glucose infusion caused a significant increase in VLDL and LDL triglyceride concentrations and the Intralipid plus glucose infusion was followed by a rise in LDL and HDL triglyceride concentrations. HDL cholesterol decreased by 26% (P less than 0.01) during glucose and by 19% (P less than 0.05) during Intralipid plus glucose. Apoprotein A I was very low already at the start of parenteral alimentation and it did not change during either nutrition. The HDL cholesterol and apoprotein A I and A II levels were each positively correlated with adipose tissue LPL activity before parenteral nutrition but not after it.

Adipose Tissue↗
PubMed1981

Lipoprotein lipase activity in adipose tissue and skeletal muscle of human diabetics during insulin deprivation and restoration.

Twelve insulin-dependent diabetic patients were deprived of insulin for 12 h, and thereafter given an 8-h i.v. infusion of insulin. Lipoprotein lipase (LPL) activity was determined from heparin eluates of adipose tissue and skeletal muscle before and after insulin infusion. In spite of development of marked hyperglycemia and hyperketonaemia during the insulin deprivation the LPL activity of the two tissues remained mostly within normal range. During the subsequent insulin administration the LPL activity of adipose tissue increased by 36% (p less than 0.05) whereas the skeletal muscle LPL remained unchanged. The result is compatible with the view that human adipose tissue LPL is more sensitive to insulin than the corresponding enzyme of muscle.

3-Hydroxybutyric Acid↗
PubMed1981

Catabolism of human very low density lipoproteins in vitro: a fluorescent phospholipid method for monitoring lipolysis.

The catabolism of human plasma very low density lipoproteins (VLDL) by purified bovine milk lipoprotein lipase has been measured in vitro using a fluorescent phospholipid as a method to monitor lipolysis. Dansyl phosphatidylethanolamine (DPE) was incorporated into VLDL to form DPE-VLDL, and the rate of catabolism was followed by measuring the increase in fluorescence at 490 nm after the addition of the enzyme. The studies were performed with VLDL isolated from 20 normal individuals. In addition, the VLDL from 8 mildly obese subjects with primary hypertriglyceridemia (Type IV phenotype) was studied. With this in vitro system and with a constant amount of lipoprotein lipase, the rate of lipolysis did not differ in normal and in these hypertriglyceridemic subjects. Furthermore, there was no correlation between the rates of hydrolysis and the plasma levels of triglyceride or high density lipoprotein cholesterol.

Adult↗
PubMed1980

A micromethod for assay of lipoprotein lipase activity in needle biopsy samples of human adipose tissue and skeletal muscle.

A rapid and simple procedure for assay of lipoprotein lipase (LPL) activity in small amounts of human adipose tissue and skeletal muscle is described and validated. The enzyme is eluted from tissues with heparin and the activity is determined from the eluate by measuring the release of [14C]oleic acid from a gum arabic stabilized emulsion of glycerol-tri[14C]oleate in a Tris-buffer medium containing albumin and pooled normal human serum. Reproducible results are obtained with amounts of tissue ranging from 2 to 25 mg. The Km values of the adipose tissue and skeletal muscle LPL for the triolein substrate were 0.74 +/- 0.06 and 0.77 +/- 0.05 mmol/l, respectively. The standard radioactive triolein emulsion was hydrolyzed by adipose tissue LPL at a rate closely similar to rat VLDL-triglyceride labeled in vivo with [1-14C]palmitic acid, suggesting that the experimental substrate behaved in a similar manner to the natural substrate. The LPL activity was much higher in adipose tissue than in muscle. In adipose tissue the LPL activity was 2--4 times higher in women than in men whereas no sex difference was present in the LPL activity of muscle.

Adipose Tissue↗
PubMed1980

Dansyl phosphatidylethanolamine-labeled very low density lipoproteins. A fluorescent probe for monitoring lipolysis.

The fluorescent phospholipid dansyl phosphatidylethanolamine (DPE) (dansyl, 5-dimethylaminonaphthalene-1-sulfonyl) was incorporated into very low density lipoproteins (VLDL) to form DPE-VLDL. The addition of milk lipoprotein lipase to DPE-VLDL in the presence of albumin resulted in a greater than 3-fold fluorescence increase and a 20 nm blue shift in the wavelength of the emission maxima of the dansyl fluorophore. The lipoprotein lipase-induced fluorescence changes occurred concomitantly with the release of free fatty acids from VLDL. Lipoprotein lipase did not produce fluorescence changes in DPE incorporated into either low or high density lipoproteins. The rate of fluorescence increase in DPE-VLDL was maximal at 37 degrees C, dependent on the concentration of lipoprotein lipase and VLDL, and followed typical Michaelis-Menten kinetics with a Km of 1.0 for lipoprotein lipase. Both the initial rate and the total fluorescence increase correlated well (r = 0.98 and 0.95) with the release of free fatty acids. We conclude that the lipoprotein lipase-induced fluorescence increases in DPE-VLDL provide an accurate, convenient, and the only noninvasive means of following continuously the lipolysis of human VLDL.

Animals↗
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

Effect of acute vigorous exercise on lipoprotein lipase activity of adipose tissue and skeletal muscle in physically active men.

Ten well-trained men ran a distance of 20 km in the morning after overnight fasting. Lipoprotein lipase (LPL) activity was determined from heparin eluates of adipose tissue and skeletal muscle before and after the exercise. The mean LPL activity rose 2.1-fold in skeletal muscle (p < 0.01) and by 20 % in adipose tissue (p < 0.05) during the running. No significant change occurred in serum lipid or lipoprotein concentrations. The plasma insulin decreased and plasma glucagon increased during the exercise. The muscle LPL increment was significantly related to the fall of insulin/glucagon ratio. The results show that during exercise the skeletal muscle is adapted for increased uptake of circulating triglycerides which are either utilized immediately or used for restoration of muscle lipid stores after the end of exercise.

Adipose Tissue↗
PubMed1979

Effects of caloric restriction on lipid metabolism in man: changes of tissue lipoprotein lipase activities and of serum lipoproteins.

Heparin-releasable lipoprotein lipase (LPL) activity was measured in biopsy samples of adipose tissue and skeletal muscle of 8 normal healthy females, first during an isocaloric diet and then after 2 and 7 days on a 400-kcal diet. In adipose tissue the LPL activity expressed per tissue weight fell to 38% and to 22% of the initial level after 2 and 7 days' caloric restriction, respectively. In skeletal muscle the LPL activity rose slightly after two days (+24%) but decreased to 49% of the initial value after seven days on diet. The estimated total body LPL activity decreased to 50% and to 20% of the baseline value after 2 and 7 days, respectively, but the relative contribution of skeletal muscle to the total LPL increased from 10 to 30%. The triglyceride and VLDL triglyceride concentrations were not significantly changed during the low calorie diet but the LDL triglyceride increased and the HDL cholesterol decreased significantly (P less than 0.01). It is concluded that substantial restriction of calorie intake results in a decrease of over-all triglyceride removal capacity but in an increase of the fraction removed by skeletal muscle. The decrease of HDL cholesterol is probably a consequence of the low turnover of exogenous and endogenous triglyceride-rich lipoproteins.

Adipose Tissue↗