Biomedical subjects

S Valdemarsson

Publications and source records attributed to S Valdemarsson.

At least 37 records · Page 2Linked to original sources

PubMed1994

Increased ratio between anaerobic and aerobic metabolism in lymphocytes from hyperthyroid patients.

While an increased oxygen consumption is accepted as one consequence of hyperthyroidism, only few data are available on the role of anaerobic processes for the increased metabolic activity in this disease. In this study we evaluated the relative importance of anaerobic and aerobic metabolism for the metabolic activity in lymphocytes from patients before and after treatment for hyperthyroidism. Total lymphocyte heat production rate (P), reflecting total cell metabolic activity, was determined in a plasma lymphocyte suspension using direct microcalorimetry. The contribution from aerobic metabolism (O2-P) was calculated from the product of the lymphocyte oxygen consumption rate and the enthalpy change for glucose combustion, and the anaerobic contribution as the difference between P and O2-P. The total lymphocyte heat production rate P was 3.37 +/- 0.25 (SEM) pW/cell (N = 11) before and 2.50 +/- 0.11 pW/cell (N = 10) after treatment for hyperthyroidism (p < 0.01) as compared to 2.32 +/- 0.10 pW/cell in a control group (N = 18). The aerobic component O2-P amounted to 1.83 +/- 0.11 pW/cell in the patient group before and 1.83 +/- 0.08 pW/cell after treatment and to 1.71 +/- 0.16 pW/cell in 10 controls. Out of P, the O2-P component corresponded to 56.8 +/- 4.4% in the hyperthyroid state and to 73.7 +/- 3.2% after treatment (p < 0.01) as compared to 73.4 +/- 4.4% in the 10 euthyroid controls. It was concluded that the increased metabolic activity demonstrated in lymphocytes from hyperthyroid patients cannot be explained by an increased oxygen-dependent consumption.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗

PubMed1994

Clinical use of laboratory thyroid tests and investigations.

Laboratory thyroid testing involves in vitro tests for autoimmune thyroid disease, thyroid dysfunction and neoplasia, in vivo investigations of thyroid function, and investigations of thyroid morphology. The authors describe, in tabular form, the diagnostic information carried by the tests and their clinical utility as well as clinically relevant interferences.

Adult↗

PubMed1992

Increased lymphocyte thermogenesis in hyperthyroid patients. Role of Na/K pump function. Evaluation of aerobic/anaerobic metabolism.

The role of the Na/K pump for the increased cell energy expenditure in hyperthyroidism was studied by measuring total lymphocyte heat production rate in samples with and without ouabain inhibition of Na/K ATP-ase. In addition, the relative contribution of aerobic processes to lymphocyte thermogenesis was calculated from oxygen consumption measurements. In 12 patients with clinical and laboratory hyperthyroidism total lymphocyte heat production rate was 3.19 +/- 0.21 pW/cell, significantly higher than in 7 patients with subclinical hyperthyroidism (2.14 +/- 0.11 pW/cell) and in 15 euthyroid subjects (2.26 +/- 0.11 pW/cell) (p less than 0.001). The relative decrease in lymphocyte heat production rate after ouabain, giving a quantitative measure of the activity of the Na/K ATP-ase and reflecting the importance of Na/K pump function for the overall rate of lymphocyte metabolism, was not significantly different between the groups: 19.5 +/- 3.6% in hyperthyroid patients, 14.2 +/- 2.3% in subclinical hyperthyroid patients and 17.8 +/- 3.1% in euthyroid subjects. According to the rate of lymphocyte oxygen consumption, aerobic processes represented 58.4 +/- 6.7% of total lymphocyte energy expenditure in hyperthyroid patients, not significantly different from subclinical hyperthyroidism (62.6 +/- 8.4%) or from euthyroidism (66.6 +/- 2.7%). These data do not support the hypothesis of a specific role of the Na/K pump function for the increased cell thermogenesis in hyperthyroidism and indicate a parallel stimulation of aerobic and anaerobic processes by thyroid hormone excess.

Adult↗

PubMed1991

Early postoperative basal serum GH level and the GH response to TRH in relation to the long-term outcome of surgical treatment for acromegaly: a report on 39 patients.

During a 10-year period 39 patients with acromegaly, aged 23-73 years, underwent selective adenomectomy via a trans-sphenoidal or transfrontal (one case) approach. Six to 12 months after the operation, the serum level of growth hormone (GH) was reduced to less than 5 micrograms l-1 in 28 patients (74%) in at least two of three random samples and/or suppressed to less than 3 micrograms l-1 during an oral glucose load, thus fulfilling the commonly used criteria for a successful operation. In 10 patients these criteria for adequate GH reduction were not fulfilled, but their median S-GH level was reduced from 38 to 11 micrograms l-1 (P less than 0.01) after the operation. Surgery was successful in 11 of 13 (85%) patients with a microadenoma (less than 10 mm in diameter), in 10 of 14 (71%) patients with an adenoma of diameter greater than 10 mm but still enclosed in the sella, and in seven of 11 (64%) patients with locally invasive tumours. Impaired pituitary function was observed in 23% of the patients after surgery, independent of tumour size. In one patient the postoperative period was complicated by a lethal intracranial infection. During follow-up for 1-10 years, four patients relapsed, after 1, 1.5, 6 and 9 years, respectively. Patients for whom surgery appeared to have been ineffective at the evaluation 6-12 months postoperatively, or who later relapsed were identified by early (within 7 d) postoperative serum GH with a sensitivity of 90%. The accuracy for identification of a satisfactory outcome of surgery was 85%, and the predictive value was 90%. The corresponding values for the GH response to TRH measured 6-12 months postoperatively were 47, 40 and 54%, respectively. It is concluded that the basal level of serum GH measured 1-7 d postoperatively has higher sensitivity and specificity than the GH response to TRH 6-12 months postoperatively for evaluation of the effect of surgery on GH overproduction, and that it has a higher predictive power with regard to the long-term outcome of surgery for acromegaly.

Acromegaly↗

PubMed1991

Increased plasma level of substance P in patients with severe congestive heart failure treated with ACE inhibitors.

The effects of angiotensin-converting-enzyme (ACE) inhibitors on circulatory regulating mechanisms in congestive heart failure (CHF) were studied by comparison of plasma levels of catecholamines, neuropeptide Y-like immunoreactivity (NPY-LI), substance P (SP-LI), calcitonin gene-related peptide (CGRP-LI), vasopressin (ADH-LI), atrial natriuretic peptide (ANP-LI) and renin activity (PRA) in patients with severe CHF (NYHA III-IV) with (n = 15) or without (n = 17) ACE inhibitors in addition to digoxin and diuretic therapy. Data were also compared with those for healthy subjects (n = 31) and patients with moderate CHF (NYHA I-II). Catecholamines and NPY-LI were increased to the same extent in both groups with severe CHF. CGRP-LI showed no changes relative to controls in any of the patient groups, and was not affected by ACE inhibitors. The SP-LI level was significantly increased in all patient groups. Patients with severe CHF on ACE inhibition had a SP-LI level of 4.05 +/- 0.79 pmol l-1, compared to a concentration of 2.28 +/- 0.30 pmol l-1 (P less than 0.05) in the patient group with a comparable degree of CHF but without ACE inhibition. In the latter group, an inverse relationship appeared between the SP-LI and the serum sodium levels (r = -0.68, P less than 0.05). The patients with severe CHF who received ACE inhibitors had significantly lower ADH-LI levels than the patients with a comparable degree of CHF who were not treated with ACE inhibitors, while the ANP-LI levels was increased to a similar extent in both groups.

Aged↗

PubMed1990

Congestive heart failure: involvement of perivascular peptides reflecting activity in sympathetic, parasympathetic and afferent fibres.

In controls and in patients suffering from congestive heart failure (CHF) the circulating levels of catecholamines, neuropeptide Y-like immunoreactivity (NPY-LI), vasoactive intestinal peptide-LI (VIP-LI), substance P-LI (SP-LI) and calcitonin generated peptide-LI (CGRP-LI) markers of sympathetic, parasympathetic and sensory nervous systems, respectively, have been examined. There was a significant rise in the levels of noradrenaline, NPY-LI and SP-LI already in moderate CHF (New York Heart Association Stage I and II). In patients with severe CHF (NYHA Stage III and IV) the circulating levels of noradrenaline, adrenaline, NPY-LI and SP-LI were significantly increased. CGRP-LI was not altered, despite the fact that this peptide co-exists in many tissues with SP. There was no change in VIP-LI. The pathophysiological significance of this pattern of reaction of circulating catecholamines and neuropeptides is unclear; however, the rise in SP-LI may be a reaction to counterbalance the vasoconstrictive effects of the activation of the sympatho-adrenal system.

Afferent Pathways↗

PubMed1990

Gamma 2-MSH in congestive heart failure: relation to atrial natriuretic peptide, arginine vasopressin and catecholamines.

A possible role of the proopiomelanocortin derived peptide gamma 2-melanocyte stimulating hormone (gamma 2-MSH) has been studied in patients with various degrees of congestive heart failure (CHF). The profile of changes in circulating levels of gamma 2-MSH-like immunoreactivity (-LI) has been compared with those of atrial natriuretic peptide (ANP)-LI, arginine vasopressin (AVP)-LI and catecholamines in CHF. Patients with moderate CHF (New York Heart Association stages I-II) showed significantly higher levels of h-alpha ANP-LI and NA (P less than 0.05) compared to controls. Patients with severe CHF (stages III-IV) had significantly higher levels of all hormones measured compared to controls: noradrenaline, P less than 0.001; adrenaline, P less than 0.001; gamma 2-MSH-LI, P less than 0.001; h-alpha ANP-LI, P less than 0.05; AVP-LI, P less than 0.01. For the catecholamines and gamma 2-MSH-LI there was a significant increase from moderate to severe forms of CHF. A significant correlation was observed between gamma 2-MSH-LI and noradrenaline, and between h-alpha ANP-LI and noradrenaline in patients with CHF. The present results show that gamma 2-MSH-LI is increased only in severe forms of cardiac failure, and that this change is more closely related to the increase in circulating levels of noradrenaline than to increased levels of ANP-LI or AVP-LI.

Aged↗

PubMed1990

Gamma 2-MSH increases during graded exercise in healthy subjects: comparison with plasma catecholamines, neuropeptides, aldosterone and renin activity.

To evaluate the possibility that the proopiomelanocortin (POMC)-derived peptide gamma 2-melanocyte stimulating hormone (gamma 2-MSH) has a role in circulatory regulation in man we studied circulating levels of this peptide at three different stages of physical activity in 10 young healthy subjects. The results were compared to simultaneously measured plasma levels of catecholamines, neuropeptide Y, vasopressin, renin activity, aldosterone and human alpha-atrial natriuretic peptide (alpha-hANP) and of the vasodilatory peptides calcitonin gene-related peptide, substance P and vasoactive intestinal peptide. The plasma levels of gamma 2-MSH-LI (like immunoreactivity) increased from 1009 +/- 101 pmol l-1 at supine rest to 1281 +/- 79 pmol l-1 when measured after 10 min walking (P less than 0.05), and remained at this increased level also after a consecutive further increase of physical activity (4 min stair rush), 1293 +/- 87 pmol l-1 (P less than 0.05 vs. at rest). The increase in circulating gamma 2-MSH-LI levels preceded the elevation of the venous plasma noradrenaline level, but did not rise further with more pronounced activation of the sympathetic nervous system at the highest grade of physical activity examined.

Aldosterone↗

PubMed1990

Cell metabolic activity in acromegaly: a microcalorimetric study of lymphocyte metabolism.

A discrepancy between the clinical impression of disease activity and basal serum levels of growth hormone is often seen in patients with acromegaly. A slightly better relation has been found to serum levels of IGF-I, but a technique for evaluation of cell metabolic activity in this disease is still missing. For this purpose we used microcalorimetry to determine heat production rate in lymphocytes from 15 patients with acromegaly. The mean heat production rate was 2.90 +/- 0.15 pW/cell, significantly higher than in 13 healthy subjects, 2.31 +/- 0.12 pW/cell (p less than 0.01). Heat production rates did not correlate significantly with basal growth hormone levels, but increased, in a statistically significant manner (p less than 0.001), in parallel with the score index used to evaluate the clinical activity of the disease. Using the technique of microcalorimetry we could thus demonstrate an increased metabolic activity at a cellular level in patients with acromegaly, a finding that is in accordance with the view that an increased cell metabolic activity is a component of the disease process in acromegaly.

Acromegaly↗

PubMed1990

Hormonal influence on calcitonin gene-related peptide in man: effects of sex difference and contraceptive pills.

Calcitonin gene-related peptide (CGRP) is one of the peptides encoded for by the calcitonin gene. It has been demonstrated in man to be located in the thyroid and in perivascular nerves and to possess potent vasodilatory properties. In the present study we found plasma levels of calcitonin gene-related peptide-like immunoreactivity (CGRP-LI) to be significantly higher in females than in males and that women on contraceptive pills had significantly higher CGRP-LI levels than women not taking contraceptives. These data are in accordance with one earlier report on an increased CGRP level during pregnancy and suggest a positive influence of the female sex hormones on the plasma CGRP level in man, which should be considered in the establishment of a reference range for this analysis.

Adult↗

PubMed1989

Reduced size of a hormonally silent pituitary adenoma during treatment with CV 205-502, a new dopamine agonist mainly stimulating D2 receptors.

A 39-year-old woman with secondary amenorrhea and visual field defects underwent craniotomy for a large pituitary tumor that was hormonally silent according to measurement of plasma hormone levels and immunohistochemical analysis. During the preoperative investigation, bromocriptine was administered for 1 month, but there was no change in the tumor size as seen on computed tomographic scans. One month after surgery, visual field defects recurred, and a tumor mass comparable to the preoperative state was found on computed tomographic scan. The tumor size gradually diminished during treatment with CV 205-502, a tricyclic benzoquinoline which stimulates mainly D2 receptors and is better tolerated than bromocriptine. The visual fields were completely normalized after 3 months of treatment with the drug, and surgical management of the tumor mass was no longer considered to be necessary. Thus, as in many similar cases, the hormonally silent pituitary tumor in this patient proved unresponsive to bromocriptine treatment. In contrast, the tumor was reduced by therapy with CV 205-502, a drug that is better tolerated and might permit a more intense stimulation of D2 receptors.

Adenoma↗

PubMed1988

Fatty acid composition in plasma and platelet phospholipid in hypothyroid patients before and after 1-thyroxine substitution.

The relative concentration of fatty acids in plasma and platelet phospholipids (phosphatidylcholine) was determined in 11 patients with overt hypothyroidism (S-TSH greater than 80 mU/l) before and after 1-thyroxine substitution therapy. During therapy, the linoleic (C18:2) acid content decreased (p less than 0.01) whereas longer and more desaturated fatty acids, including arachidonic (C20:4) acid, increased (p less than 0.01) in plasma phospholipids. Also, oleic (C18:1) acid decreased (p less than 0.01) while the major saturated fatty acids, palmitic (C16:0) and stearic (C18:0) acids, were stable. In platelet membrane phospholipids, a similar reciprocal change in the relative content of linoleic (C18:2) and arachidonic (C20:4) acids, respectively, occurred. In plasma, these changes in linoleic and arachidonic acids were found to be inversely correlated (r = 0.56, p less than 0.05). The change in the linoleic acid content in plasma was also correlated to that in platelets (r = 0.64, p less than 0.05). Thus, we have found that thyroid hormones positively influence the conversion of linoleic acid to longer and more polyunsaturated fatty acids in a way that affects fatty acid composition not only in plasma but also in platelet membrane phospholipids.

Adult↗

PubMed1987

Erythrocyte thermogenesis in hyperthyroid patients: microcalorimetric investigation of sodium/potassium pump and cell metabolism.

Erythrocyte thermogenesis was studied by microcalorimetry in 11 patients before and after treatment for hyperthyroidism. Cell heat production rate and intracellular Na+ and K+ levels were measured in plasma suspensions of erythrocytes with and without specific inhibition of Na/K ATPase by ouabain. The ouabain induced change in the heat production rate (the Na/K pump thermal power); the erythrocyte intracellular Na+ content and the ouabain sensitive Na+ transport were used to estimate the Na/K pump function. The mean value for heat production rate was 131 +/- 4 mW/L erythrocytes before treatment, which is significantly higher than in euthyroid subjects. A significant decrease (P less than 0.01) to normal levels was recorded following therapy. This decrease, as determined in samples with ouabain, correlated to changes in serum levels of triiodothyronine, T3, (r = .74, P less than 0.01). The Na/K pump thermal power was 11 +/- 2 mW/L erythrocytes (8 +/- 2% of total heat production rate) before and 9 +/- 2 mW/L erythrocytes (8 +/- 2%) after treatment. These two values were not different from those obtained in euthyroid subjects. The erythrocyte Na+ content decreased from 9.9 +/- 2.1 to 4.9 +/- 0.5 mmol/L erythrocytes (P less than 0.001) following normalization of thyroid function. The decrease in intracellular Na+ concentration correlated to the decrease in serum T3 levels, but only when calculated from the data obtained in samples with ouabain (r = .60, P less than 0.05). The relative increase in intracellular Na+ concentrations following addition of ouabain was significantly lower (P less than 0.05) before than after treatment for hyperthyroidism, 37 +/- 10% and 61 +/- 5%, respectively.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗

PubMed1987

Hepatic lipase and the clearing reaction: studies in euthyroid and hypothyroid subjects.

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.

Adult↗

PubMed1987

Increase in hepatic lipase activity after testosterone substitution in men with hypogonadism of pituitary origin.

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.

Adult↗

PubMed1987

Erythrocyte metabolism in hyperthyroidism: a microcalorimetric study on changes in the Embden-Meyerhof and the hexose monophosphate pathways.

Erythrocyte metabolism was studied in vitro by microcalorimetry in 10 hyperthyroid subjects before and after treatment. By inhibiting the enzyme enolase in the Embden-Meyerhof pathway with sodium fluoride (NaF) we have recorded the anaerobic and aerobic contributions in erythrocyte thermogenesis. The decrease in heat production rate in samples with NaF corresponds to the anaerobic contribution, whereas the values from samples with NaF reflect aerobic processes. Before treatment, total heat production rate was 120 +/- 2 mW/l erythrocytes which was higher than the post-treatment value of 99 +/- 2 (P less than 0.001) as well as the value for 14 euthyroid subjects, 108 +/- 2 mW/l (P less than 0.001). The NaF inhibitable rate was 73 +/- 2 before and 63 +/- 1 mW/l after therapy (P less than 0.01). These values correspond to 61 +/- 1 and 64 +/- 1% (n.s.) of the total heat production rate, and were similar to that of 61 +/- 2% for the controls. Heat production rates in the presence of NaF were 47 +/- 1 before and 36 +/- 1 mW/l after therapy (P less than 0.001), representing 39 +/- 1 and 36 +/- 1% of total values, respectively. The present results show that overall metabolism is increased in erythrocytes from hyperthyroid subjects before treatment and returns to normal after normalization of the thyroid function. Moreover, by using microcalorimetry we found that the metabolic activity along the Embden-Meyerhof anaerobic pathway as well as along the hexose monophosphate aerobic pathway in erythrocytes is stimulated by thyroid hormones.

Adult↗

PubMed1985

Reversal of increased whole blood and plasma viscosity after treatment of hypothyroidism in man.

Blood and plasma viscosity was measured in 13 patients with hypothyroidism before and during replacement therapy with l-thyroxine. Blood viscosity was measured at natural hematocrit and after adjustment to 40%. The values were compared to those of 12 healthy subjects. Both blood viscosity at hematocrit 40% and plasma viscosity were increased in the hypothyroid state and decreased to the levels of the reference group after treatment. The therapy-induced changes in blood and plasma viscosity were intercorrelated at low but not at high shear rates. The changes in viscosity were not correlated to the reductions in lipoprotein concentrations resulting from therapy. The institution of l-thyroxine replacement therapy was also followed by reductions in erythrocyte sedimentation rate and diastolic blood pressure, both with significant correlations to the decrease in blood viscosity. It is concluded that in hypothyroidism there are changes in both plasma and erythrocytes that increase blood viscosity, with normalization upon treatment with l-thyroxine to euthyroidism.

Adult↗

PubMed1985

Platelet and adipocyte thermogenesis in hypothyroid patients: a microcalorimetric study.

Direct microcalorimetry was used for measurements of heat production in cell suspensions of platelets and adipocytes, obtained from hypothyroid patients before and after 3 months on full L-thyroxine substitution. Platelet heat production was significantly lower than normal before treatment and increased in all 10 patients studied; the mean value increased from 51.3 +/- 1.6 fW/cell before to 57.1 +/- 1.8 fW/cell after therapy (P less than 0.001). Similarily, adipocyte heat production was initially significantly lower than normal and increased during treatment in all 6 patients investigated. The mean value for heat production per adipocyte was 18.8 +/- 1.7 pW/cell before and 32.4 +/- 2.5 pW/cell after therapy (P less than 0.025), which is still below the level recorded in lean healthy subjects. The adipocyte size did not change significantly. The increase in adipocyte heat production was correlated to the increase in S-triiodothyronine levels (r = 0.84, P less than 0.05). In hypothyroidism, the total metabolic activity seems to be comparatively more reduced in adipocytes than in platelets. A difference may exist between these cells with regard to recovery of normal metabolic activity during treatment for hypothyroidism. Direct microcalorimetry appears to be an adequate method for monitoring net metabolic effects of thyroid hormones in these cells.

Adipose Tissue↗