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Biomedical subjects

S Valdemarsson

Publications and source records attributed to S Valdemarsson.

45 records · Page 3Linked to original sources
PubMed1985

Glucose tolerance and insulin and C-peptide responses after various insulin secretory stimuli in hyper- and hypothyroid subjects before and after treatment.

Immunoreactive insulin (IRI) and C-peptide secretory responses to terbutaline, glucagon, glucose and a standardized meal during continuous blood glucose monitoring were investigated in hyper- and hypothyroid patients before and after treatment. The beta 2-adrenoceptor agonist terbutaline (125 micrograms IV) induced prompt IRI and C-peptide responses in hyperthyroid patients. On the contrary, in the hypothyroid, no insulin or C-peptide responses were seen despite a slight enhancement of blood glucose concentrations. Thyroxine treatment of these patients improved the IRI and C-peptide responses and no blood glucose increment was then seen. Glucagon (250 micrograms IV) induced prominent IRI and C-peptide responses of similar magnitude in hyper- and hypothyroid patients before as well as after treatment. Before treatment, the blood glucose increment was greater in the hypothyroid patients than in the hyperthyroid but after treatment no difference between the 2 groups was seen. After a small load of glucose (6 g IV) no apparent difference in glucose tolerance was seen between hyper- and hypothyroid patients. However, the hyperthyroid patients had greater IRI and C-peptide responses to glucose than the hypothyroid but the differences diminished after treatment. Before treatment, hypothyroid patients had lower blood glucose response to a meal intake than hyperthyroid patients but no differences were seen between the 2 patient groups with regard to IRI- and C-peptide responses. After treatment, no differences between the 2 groups were seen with regard to blood glucose, IRI or C-peptide responses to the meal.(ABSTRACT TRUNCATED AT 250 WORDS)

Adolescent↗
PubMed1984

Treatment of hyperthyroidism: effects on hepatic lipase, lipoprotein lipase, LCAT and plasma lipoproteins.

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.

Adolescent↗
PubMed1983

Experimental hyperthyroidism in man: effects on plasma lipoproteins, lipoprotein lipase and hepatic lipase.

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.

Adult↗
PubMed1983

Dyslipoproteinaemia in hypothyroidism of pituitary origin: effects of L-thyroxine substitution on lipoprotein lipase, hepatic lipase, and on plasma lipoproteins.

We have studied the effects of L-thyroxine substitution on lipoprotein concentrations, on the activities of lipoprotein lipase (LPL) and hepatic lipase (HL), and on the elimination rate of exogenous triglyceride in a homogeneous group of patients with hypothyroidism of pituitary origin. All were deficient of sex hormones but not of corticosteroids during the observation period. Before treatment total plasma cholesterol, LDL cholesterol, and triglyceride levels were significantly higher than in a euthyroid control group but not as high as in patients with overt primary hypothyroidism. The activities of LPL and HL were also intermediate between those of euthyroid and overt primary hypothyroid subjects, and there was a significant reduction of the elimination rate of exogenous triglyceride. No changes were found for HDL cholesterol levels. When the patients with secondary hypothyroidism were compared to patients with primary hypothyroidism, matched for thyroid function levels, age, sex, and weight, there were no differences with regard to plasma lipoprotein concentrations or post-heparin lipase activities. In 3 patients with secondary hypothyroidism the lipoprotein profiles were studied by zonal ultracentrifugation and found to agree well with changes observed in primary hypothyroidism. L-thyroxine substitution produced a normalization of lipase activities and lipoprotein concentrations in patients with secondary hypothyroidism. We conclude that there are no fundamental differences in the disturbances of the lipoprotein metabolism in primary and secondary forms of hypothyroidism.

Adolescent↗
PubMed1983

Relations between thyroid function, hepatic and lipoprotein lipase activities, and plasma lipoprotein concentrations.

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.

Adult↗
PubMed1982

Reversal of decreased hepatic lipase and lipoprotein lipase activities after treatment of hypothyroidism.

Plasma lipoprotein concentrations, activities of hepatic lipase and lipoprotein lipase in post-heparin plasma, and the removal rate of exogenous triglyceride were measured in fourteen patients with severe primary hypothyroidism before and after 4 months substitution therapy with 1-thyroxine. Before treatment plasma LDL cholesterol concentrations were markedly increased while HDL cholesterol and plasma triglycerides were in the upper reference range. Thyroxine substitution led to a normalization of LDL cholesterol in all patients. Plasma triglycerides and HDL cholesterol decreased moderately. Hepatic lipase and lipoprotein lipase activities were initially reduced but increased significantly after treatment, by about 170% and 55%, respectively. The increase in hepatic lipase activities was significantly correlated to the increase in serum triiodothyronine levels and also to the reduction in LDL cholesterol concentrations. The decrease in LDL cholesterol was also significantly correlated to the increase in serum triiodothyronine concentration. In two patients initially treated with triiodothyronine, the activity of hepatic lipase, but not that of lipoprotein lipase, increased after 24 and 48 h, while LDL cholesterol levels decreased substantially. We suggest that the reduced activities of hepatic lipase as well as of lipoprotein lipase are important pathogenetic factors for the dyslipoproteinaemia occurring in hypothyroidism and that the low serum triiodothyronine concentration is of major importance for the alterations in lipid transport.

Adolescent↗
PubMed1981

HLA antigens in two siblings with autoimmune Addison's disease.

The diagnosis of autoimmune Addison's disease was established in two siblings by demonstration of serum antibodies against adrenal cortex antigen, elevated P-ACTH combined with a low P-cortisol, and the absence of P-cortisol response to exogenous ACTH. HLA typing in the two siblings and their parents revealed the same HLA phenotype in the two patients. This is compatible with an autosomal recessive mode of inheritance and indicates that a supposed trait for autoimmune Addison's disease may segregate with the HLA complex in the familial form of autoimmune Addison's disease.

Addison Disease↗