| 1. |
- Hansson, P, et al.
(författare)
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Experimental hyperthyroidism in man: effects on plasma lipoproteins, lipoprotein lipase and hepatic lipase
- 1983
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Ingår i: Hormone and Metabolic Research. - 1439-4286. ; 15:9, s. 449-452
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Tidskriftsartikel (refereegranskat)abstract
- We have studied the effects of triiodothyronine administration (20-40 micrograms three times daily over one week) in six healthy young men, on the activities of lipoprotein lipase and hepatic lipase and on plasma lipoprotein concentrations. Hepatic lipase activity in post-heparin plasma rose by 46 +/- 25% (p less than 0.025), whereas the activity of lipoprotein lipase did not change significantly. Plasma cholesterol concentrations decreased by about 20% (p less than 0.025), whereas there was no change in plasma triglyceride levels. The fall in plasma cholesterol could be accounted for by a reduction of HDL cholesterol (-11%, p less than 0.025) as well as LDL cholesterol (-27%, p less than 0.025). The data emphasize the role of hepatic lipase in the lipoprotein alterations associated with thyroid dysfunction.
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| 2. |
- Valdemarsson, Stig, et al.
(författare)
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Hepatic lipase and the clearing reaction: studies in euthyroid and hypothyroid subjects
- 1987
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Ingår i: Hormone and Metabolic Research. - 1439-4286. ; 19:1, s. 28-30
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Tidskriftsartikel (refereegranskat)abstract
- Eight patients with primary hypothyroidism were compared to eleven euthyroid subjects with regard to the effects of a single i.v. dose of heparin on plasma lipoprotein concentrations (the "clearing reaction"). The hypothyroid patients were moderately hypercholesterolemic but had normal plasma triglyceride levels. Maximal activities of hepatic lipase (HL) and lipoprotein lipase (LPL) were lower in the hypothyroid than in the normal subjects. The hypothyroid patients demonstrated a significant decrease in total plasma cholesterol levels after heparin injection (from 8.36 +/- 0.70 mmol/l to 7.55 +/- 0.62 mmol/l, P less than 0.02). The maximal activity of HL after heparin was significantly correlated to the decrease in plasma cholesterol levels (P less than 0.05) and in LDL-cholesterol levels (P less than 0.01). The euthyroid subjects demonstrated a smaller decrease in total plasma cholesterol concentrations (from 5.53 +/- 0.31 to 5.08 +/- 0.28 mmol/l, P less than 0.05). In this group, the fall in cholesterol levels was not correlated to maximal HL activity. The reduction in plasma triglyceride levels after heparin was similar and significant (P less than 0.01) in both groups. These data support the view that decreased activity of HL contributes to the dyslipoproteinemia seen in hypothyroidism. They are also in accordance with the notion that HL is involved in the elimination of cholesterol from plasma.
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| 3. |
- Valdemarsson, Stig, et al.
(författare)
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Increase in hepatic lipase activity after testosterone substitution in men with hypogonadism of pituitary origin
- 1987
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Ingår i: Acta Medica Scandinavica. - 0001-6101. ; 221:4, s. 363-366
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Tidskriftsartikel (refereegranskat)abstract
- Ten men with hypogonadism of pituitary origin were studied before and during testosterone substitution therapy with regard to effects on the activities of hepatic lipase (HL) and lipoprotein lipase (LPL) in postheparin plasma, and on plasma lipoprotein concentrations. The mean (+/- SEM) testosterone level increased from 1.8 +/- 0.5 to 16.3 +/- 2.4 nmol/l. The mean activity of HL rose from 327.1 +/- 35.2 to 432.8 +/- 57.2 mU/ml (p less than 0.02), while the activity of LPL did not change significantly, 71.0 +/- 9.1 mU/ml before and 62.2 +/- 3.8 mU/ml after treatment. No significant alterations in lipoprotein concentrations were recorded. These results indicate that a normal testosterone level is of importance for maintaining the activity of HL in men, thereby contributing to the sex difference previously recorded for HL activity.
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| 4. |
- Valdemarsson, Stig, et al.
(författare)
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Relations between thyroid function, hepatic and lipoprotein lipase activities, and plasma lipoprotein concentrations
- 1983
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Ingår i: Acta Endocrinologica. - 0001-5598. ; 104:1, s. 50-56
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Tidskriftsartikel (refereegranskat)abstract
- Lipoprotein concentrations and activities of lipoprotein lipase (LPL) and hepatic lipase (HL) were measured in 70 subjects with thyroid function ranging from overt hypothyroidism over subclinical hypothyroidism and euthyroidism to hyperthyroidism. In parallel with serum T3 (S-T3) concentrations increasing from low in hypothyroidism to high in hyperthyroidism there were gradually higher HL activities over the full spectrum of thyroid function, accompanied by decreasing levels of total and low density lipoprotein (LDL) cholesterol. High density lipoprotein (HDL) cholesterol was lower (P less than 0.05) in hyperthyroidism than in euthyroidism but not significantly changed in the hypothyroid groups. HL was correlated to S-T3 (r = 0.77, P less than 0.001), LDL cholesterol to log S-T3 (r = -0.76, P less than 0.001), and LDL cholesterol to log HL (r = -0.55, P less than 0.001). The activity of LPL was decreased (P less than 0.001) in overt hypothyroidism compared to euthyroidism but, in contrast to HL, the activity of LPL was not increased in hyperthyroidism. The plasma triglyceride (P-TG) concentration was elevated (P less than 0.01) in overt hypothyroidism but not significantly changed in subclinical hypothyroidism or in hyperthyroidism. The LPL activity was correlated to log S-T3 (r = 0.45, P less than 0.001), P-TG to log S-T3 (r = -0.37, P less than 0.01) and P-TG to log LPL activity (r = -0.71, P less than 0.001). Our results demonstrate that thyroid hormones influence HL and LPL activities in different ways, suggesting different mechanisms of action. Changes in HL activity seem to be an important mechanism for the disturbance of cholesterol metabolism in thyroid dysfunction while the thyroid hormone influence on LPL seems to be of importance mainly for the disturbance in triglyceride metabolism.
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| 5. |
- Valdemarsson, Stig, et al.
(författare)
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Treatment of hyperthyroidism: effects on hepatic lipase, lipoprotein lipase, LCAT and plasma lipoproteins
- 1984
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Ingår i: Scandinavian Journal of Clinical & Laboratory Investigation. - : Informa UK Limited. - 1502-7686 .- 0036-5513. ; 44:3, s. 183-189
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Tidskriftsartikel (refereegranskat)abstract
- The activities of hepatic lipase and of lipoprotein lipase, the elimination rate of exogenous triglyceride and the cholesterol esterification rate were determined and related to plasma lipoprotein concentrations in 16 patients before and after treatment for hyperthyroidism. The activity of hepatic lipase was significantly higher (65%) before than after treatment, while the activity of lipoprotein lipase and the elimination rate of exogenous triglyceride remained unchanged. The endogenous cholesterol esterifying ability decreased after treatment, whereas no change occurred in the fractional cholesterol esterification rate measured with normal plasma as substrate. The concentrations of LDL-cholesterol and HDL-cholesterol increased significantly after treatment. The decrease in hepatic lipase activities was correlated to the decrease in S-T3 concentrations (r = 0.77, P less than 0.001) and to the increase in HDL-cholesterol concentrations (r = 0.51, P less than 0.05). The activities of lipoprotein lipase were positively correlated to the concentrations of HDL-cholesterol both before (r = 0.54, P less than 0.05) and after (r = 0.59, P less than 0.05) treatment. These results support the view that hepatic lipase and lipoprotein lipase are both important determinants of plasma HDL concentrations and suggest that an increased hepatic lipase activity contributes to the lower HDL levels in hyperthyroid patients.
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| 6. |
- Back, S E, et al.
(författare)
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Age dependence of renal function: clearance of iohexol and p-amino hippurate in healthy males
- 1989
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Ingår i: Scandinavian Journal of Clinical & Laboratory Investigation. - 1502-7686. ; 49:7, s. 641-646
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Tidskriftsartikel (refereegranskat)abstract
- Iohexol, a newly developed non-ionic contrast agent, has been recently documented as a reliable glomerular filtration marker. This study describes the age dependence of the single injection clearance of iohexol in a sample of healthy male volunteers ranging from 21 to 77 years of age. In parallel, renal plasma flow was studied by measuring the total clearance of p-amino hippuric acid administered as a continuous infusion. In subjects older than 50 years a negative correlation to age was found for both p-amino hippuric acid and iohexol clearance, with a reduction of 52 ml/min and 12 ml/min per decade, respectively, whereas no age dependence was found for younger subjects. Correlation between p-amino hippuric acid and iohexol clearances was 0.81. However, the filtration fraction, defined as the ratio of iohexol to p-amino hippuric acid clearance, was higher in the elderly subjects. A consistent discrepancy was found between total and renal clearances of p-amino hippuric acid, indicating significant renal metabolism. Renal clearance of creatinine was poorly correlated to iohexol clearance and did not show any relationship to age.
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| 7. |
- Persson, E, et al.
(författare)
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Plasma lipolytic activity after subcutaneous administration of heparin and a low molecular weight heparin fragment
- 1987
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Ingår i: Thrombosis Research. - : Elsevier BV. - 1879-2472 .- 0049-3848. ; 46:5, s. 697-704
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Tidskriftsartikel (refereegranskat)abstract
- The effect of heparin and a low molecular weight heparin fragment (LMWH, mean molecular weight 4000-6000) on plasma anticoagulation and lipolysis was studied in eight healthy men. The activities of antifactor Xa (antiFXa), lipoprotein lipase (LPL), hepatic lipase (HL) and plasma levels of free fatty acids (FFA) were analysed after the injection of 5000 antiFXa units of heparin or LMWH subcutaneously. In comparison with heparin, the administration of LMWH resulted in a significantly higher antiFXa activity (p less than 0.001) but a lower release of LPL and HL (p less than 0.001), which did not increase plasma FFA. It is concluded that subcutaneous injection of LMWH in men elicits an adequate anticoagulant effect measured as antiFXa activity but has a negligible effect on plasma lipolytic activity.
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| 8. |
- Quensel, M, et al.
(författare)
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High density lipoprotein concentrations after cessation of smoking: the importance of alterations in diet
- 1989
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Ingår i: Atherosclerosis. - : Elsevier BV. - 1879-1484 .- 0021-9150. ; 75:2-3, s. 189-193
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Tidskriftsartikel (refereegranskat)abstract
- Cessation of smoking is followed by a rapid rise in plasma HDL concentrations. An earlier study has demonstrated a significant relationship between the increase in HDL concentrations and spontaneous changes in food intake, specifically an increased fat intake. In this investigation we have dissociated the effects of cessation of smoking as such from those of dietary alterations by monitoring plasma lipid and lipoprotein concentrations after cessation of smoking in 12 subjects whose diet was kept constant during an initial 2-week control period and during 2 weeks following cessation of smoking. Under these conditions plasma HDL-cholesterol levels did not increase significantly (1.01 +/- 0.26 mmol/l (mean +/- SD) before and 1.04 +/- 0.27 mmol/l after cessation of smoking). Similarly, no significant alterations were recorded for other plasma lipid or lipoprotein concentrations. Activities of lipoprotein lipase and hepatic lipase were unchanged throughout the study. These results suggest that the marked rise in HDL concentrations after stopping smoking is largely related to spontaneous changes in dietary habits which occur upon cessation of smoking.
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| 9. |
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| 10. |
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