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Biomedical subjects

A Aakvaag

Publications and source records attributed to A Aakvaag.

At least 55 records · Page 3Linked to original sources
PubMed1991

[Rapid calcium infusion in the diagnosis of hypoglycemia].

The diagnosis of beta cell tumours of the pancreas is a clinical problem. It is also difficult to exclude this diagnosis in patients who are suspected of suffering from recurrent hypoglycemia, but do not have beta cell tumours. The most widely used diagnostic procedure has been suppression of endogenous insulin production with prolonged fasting up to 72 hours. This procedure is troublesome to the patient, time-consuming and expensive, and demands the complete cooperation of the patient. Therefore several diagnostic tests have been developed, but none has been generally accepted. A newly described test involving calcium infusion, 2 mg/kg in one minute, seems to give a diagnostic response in most patients with insulinomas, few false positive results and few side effects. We have used this test for four years and found it safe and easy to perform. It has given diagnostic response in three patients with insulinomas and no false positive results in 27 other patients.

Calcium Gluconate↗
PubMed1991

Gonadal endocrine dysfunction in patients with lung cancer: relation to responsiveness to chemotherapy, respiratory function and performance status.

Male lung cancer patients with poor performance status [Eastern Cooperative Oncology Group (ECOG) index 3-4] have an endocrinological dysfunction as assessed by serum testosterone and sex hormone-binding globulin (SHBG) levels. Patients who respond to therapy regain normal free testosterone levels within 12 weeks post chemotherapy, whereas non-responders continue to exhibit subnormal levels. The perturbations of endocrinological variables in patients with lung cancer is not due to development of hypoxia, as patients with respiratory failure maintain a significantly lower testosterone level compared to cancer patients. The development of a deficiency in total testosterone concentrations in lung cancer patients is correlated to their performance status, and not to the presence of metastatic disease. The mechanisms responsible for the endocrinological dysfunction in patients with lung cancer remain unknown.

Aged↗
PubMed1991

The influence of supine relaxation on blood pressure, heart rate and atrial natriuretic peptide in normal subjects.

The effect of recumbent rest on plasma atrial natriuretic peptide (ANP) concentration, mean blood pressure (MBP) and heart rate was studied in 26 normal human volunteers. Plasma ANP concentration, MBP and heart rate were determined after 10 min sitting and after 2, 5, 8, 15 and 30 min of recumbency. During the first 5 min of recumbency there were significant decreases in both MBP (p less than 0.001) and heart rate (p less than 0.001) compared with sitting. There was a small but significant fall in plasma ANP concentration (p = 0.02) after 30 min of recumbency compared with sitting. No further reduction in MBP or heart rate occurred after 5 min supine. The level of MBP following 5 min supine correlated significantly (r = 0.44; p = 0.02) with the plasma ANP concentration 25 min later. Blood pressure and heart rate are highly dependent on posture and relaxation, and plasma ANP concentration in lesser degree. It is necessary to wait for stable baseline values to develop before any comparisons between blood pressure and plasma ANP are done. If it is assumed that a causative relation exists between blood pressure and plasma ANP level, it appears there may be a delay of 20-30 min between a change in blood pressure and the physiological response of plasma ANP level. This observation may have implications for the interpretation of the relation between blood pressure and plasma ANP concentration in healthy individuals.

Adult↗
PubMed1990

Growth control of human mammary cancer cells (MCF-7 cells) in culture: effect of estradiol and growth factors in serum-containing medium.

The growth control of estrogen-dependent mammary cancer is very complex and only partly understood. The present study was undertaken in order to establish conditions for growth control of MCF-7 cells in monolayer culture with focus on the effect of estradiol-17 beta, fetal calf serum, and growth factors. The effect of charcoal-stripped fetal calf serum (CSFCS) on cell growth was dependent upon the presence of hormones or growth factors in the medium. In the presence of insulin (or insulin-like growth factor 1) and in the absence of estradiol-17 beta, increasing concentrations of CSFCS, 0.625-20%, produced a bell-shaped growth response curve. Serum concentrations greater than 2.5% inhibited cell growth in the absence of estradiol-17 beta, whereas CSFCS in a dose-dependent way up to 10% stimulated growth in the presence of estradiol-17 beta (5 x 10(-10) mol/liter). The growth inhibitory effect of CSFCS could not be demonstrated in the absence of insulin (or insulin-like growth factor 1) and estradiol-17 beta. CSFCS stimulated growth in a dose-dependent way in the presence of estradiol-17 beta and also in the absence of insulin. Both the putative growth inhibitor and stimulator were found to be heat stable and not dialyzable. Epidermal growth factor stimulated growth but was unable to eliminate the growth inhibitory effect of 5-10% CSFCS. Interleukin-1 alpha inhibited MCF-7 cell growth in a dose-dependent way and produced a 75% reduction in cell number at a concentration of 5 x 10(-10) mol/liter. This inhibition was almost totally overcome by estradiol-17 beta. It is concluded that serum appears to contain factors with both stimulatory and inhibitory effects on the growth of MCF-7 cells. The inhibitory effect can be eliminated by estradiol (5 x 10(-10) mol/liter). In the presence of estradiol cell growth is stimulated by CSFCS in a dose-related way up to 5-10%. Taken together these data seem to indicate that estradiol stimulates cell growth in two principal ways: partly by eliminating the effect of an inhibitor, in support of a "negative hypothesis," and partly by an effect whereby estradiol permits a growth stimulator in CSFCS to be expressed, in support of the "indirect positive hypothesis."

Breast Neoplasms↗
PubMed1990

Phosphorylation of the estradiol receptor in MCF-7 human breast cancer cells in culture.

Double labelling and Western blot techniques were used to demonstrate phosphorylation of estradiol receptor. Cells in monolayer culture were incubated with [32P]orthophosphate for 18 h followed by covalent whole cell labelling of the estradiol receptor with tritiated tamoxifen aziridine [( 3H]TA). Labelled receptor was precipitated with the monoclonal antibodies H222 or JS 34/32, coupled to protein A-Sepharose, and purified by sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE), or transferred to nitrocellulose paper. Receptor protein was detected on the Western blot with the monoclonal antibody H222 and rabbit anti-rat peroxidase conjugate. Phosphorylated receptor was visualized by autoradiography. Tritium and 32P activities were monitored in the gels. Two phosphorylated forms of the receptor (molecular weights 67 and 50 kDa) have been detected in MCF-7 cells. Estradiol treatment of the cells was found to increase phosphorylation of the receptor. In estradiol-treated cells both phosphorylated receptor forms were present mainly in the nuclear extract. Both forms bound [3H]TA as evidence by SDS-PAGE. [3H]TA binding was abolished by excess non-radioactive estradiol. In addition two phosphorylated proteins of approximately 120 and 90 kDa were regularly coprecipitated with receptor in cytosol. These proteins did not bind [3H]TA. The 90 kDa phosphorylated protein was identified as a heat shock protein (hsp-90).

Blotting, Western↗
PubMed1990

Estradiol increases phosphorylation of the 90 kDa heat shock protein not associated with estradiol receptor in MCF-7 cells in culture.

MCF-7 cells in monolayer culture were incubated with [32P]orthophosphate for 18 h followed by covalent whole cell labelling of the estradiol receptor with tritiated tamoxifen aziridine [( 3H]TA). The heat shock protein (hsp-90) bound to receptor was precipitated with monoclonal antibodies H222 or JS 34/32, coupled to protein A-Sepharose and purified by sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) under reducing conditions. Hsp-90 not associated with receptor was similarly purified after isolation with the monoclonal antibody AC88. It was found that estradiol treatment of the cells markedly increased phosphate incorporation in the free hsp-90, without affecting heat shock protein bound to receptor. A 6-fold increase in phosphate content was observed after 10 min incubation of the cells with estradiol. A similar effect was seen after treatment of the cells with the phorbol ester 12-O-tetradecanoylphorbol 13-acetate (TPA). The calcium ionophore A23187 had no influence on hsp-90 phosphorylation, and treatment of the cells with forskolin to increase the cellular content of cAMP had a reverse effect. A 50% reduction of the phosphate content in the free hsp-90 was observed after 15 min treatment. The observation that estradiol, TPA and forskolin had effect only on hsp-90 not bound to receptor is an indication that the receptor-hsp-90 complex exists in vivo. Time course studies show that the effect of estradiol is non-genomic. Two possible explanations of the results seem to exist. Either estradiol induces an increase in the degree of phosphorylation of hsp-90, or hsp-90 is translocated to the cytosol from a different cellular compartment.

Blotting, Western↗
PubMed1990

Effect of ATP on the regulation of the steroid binding activity of the oestradiol receptor.

We have observed that ATP induces a second type of oestradiol binding site with slightly lower affinity (Ka 3.3 x 10(8) M-1) and lower sedimentation coefficient (4 S) in cytosol from immature lamb uterus and MCF-7 cells. A factor isolated from immature lamb uterine nuclear extract was found to decrease the steroid binding activity of oestradiol receptor that had been purified by heparin Sepharose and oestradiol-Sepharose chromatography. Inhibition of this factor by known phosphatase inhibitors, indicated that this factor may be a phosphatase. Another factor isolated from immature lamb uterine cytosol was found to enhance the effect of ATP on receptor binding in cytosol from immature lamb uterus and MCF-7 cells. The ability of this factor to phosphorylate a partially purified cytosol receptor from immature lamb uterus when incubated with [gamma 32P]ATP, indicates that this factor is a phosphokinase. The phosphorylated products after labeling with [3H]tamoxifen aziridine were characterized by sodium dodecyl sulphate-polyacrylamide gel electrophoresis. Three phosphorylated proteins with molecular weights 150, 97, and 67 kDa bound [3H]tamoxifen aziridine. Ammonium sulphate precipitated cytosol oestradiol receptor from immature lamb uterus was inactivated with receptor inactivating factor and then reactivated with receptor activating factor in the presence of [gamma 32P]ATP and substantially affinity labelled with [3H]tamoxifen aziridine. The affinity labelled oestradiol receptor was immunopurified with the monoclonal antibody JS 34/32. Three proteins with molecular weights 67, 50 and 43 kDa specifically bound [3H]tamoxifen aziridine and only 43 kDa receptor fragment was phosphorylated. The relevance of inactivation/reactivation of oestradiol receptor to the dephosphorylation/phosphorylation of receptor is discussed.

Adenosine Triphosphate↗
PubMed1990

Selectivity of hemoregulatory peptide (HP5b) action in culture.

A synthetic analog of a hemoregulatory peptide associated with mature human granulocytes (HP5b) has been investigated for inhibitory effects on various cell types in culture as compared to inhibitory action on mouse and human myelopoietic colonies (CFU-gm), which occurs from 1 X 10(-13) to 1 X 10(-6) M in vitro. This includes colony formation by lymphoid T and B cells in capillary cultures, as well as mitogen activation of T, B and NK cells. At higher concentrations, i.e., above 1 X 10(-7) M, an inhibitory effect was found on colony formation. Neither the production of interleukin (IL) 3 by mitogen-activated T cells, nor the proliferation of the IL-3-dependent L/B cell line were affected by the peptide up to 1 X 10(-5) M. A slight inhibitory effect was found above 1 X 10(-9) M on mouse 3T3 fibroblasts. A series of malignant cell lines was also tested. No effect was seen between 1 X 10(-11) and 1 X 10(-7) M on human mammary carcinoma cells in culture. On Ehrlich ascites mouse mammary carcinoma cells a 30% inhibition was seen at 10(-6) M. On a human glioblastoma cell line (GaMg) no effect was seen, and on a rat glioma cell line (BT5C) an inhibitory effect was seen at 1 X 10(-7) M and above. No significant inhibition of cell growth was seen on SC1 mouse lymphoma cells from 1 X 10(-9) to 1 X 10(-5) M during 7 days of culture. The investigated normal and malignant cell types in culture were thus not inhibited in very low concentrations which act on CFU-gm. However, a variable inhibitory effect was found at higher concentrations where the inhibition of myelopoiesis was maximal and at concentrations where the inhibition is released. The hemoregulatory peptide thus seems to be a concentration-dependent selective inhibitor of myelopoiesis. The finding that various malignant cells do not respond at lower concentrations supports the possibility of using the peptide as a protector of normal cells during cancer chemotherapy.

Amino Acid Sequence↗
PubMed1990

Influence of aminoglutethimide on the metabolism of medroxyprogesterone acetate and megestrol acetate in postmenopausal patients with advanced breast cancer.

In this study the influence of amino-glutethimide (AG) on the disposition of medroxyprogesterone acetate (MPA) and megestrol acetate (MA) was studied. When 1,000 mg AG daily was supplementally given to six patients on chronic treatment with MPA (1,000 mg/day) or MA (160 mg/day), mean serum levels of progestin were reduced by 74% as compared with control levels (P less than 0.03). AG did not change the blood clearance rate of MPA when the latter was given i.v. This discrepancy between AG's influence on oral and parenteral progestin disposition could be explained by pharmacokinetic properties of the progestins, and our results suggest that AG stimulates the metabolism of progestins. The decrease in MPA and MA serum levels was accompanied by an increase in serum cortisol, sex hormone-binding globulin (SHBG) and testosterone levels. This suggests that AG reduces the biological activity of progestins.

Administration, Oral↗
PubMed1990

Influence of progestins on serum hormone levels in postmenopausal women with advanced breast cancer--I. General findings.

The influence of oral high dose progestin (medroxyprogesterone acetate, MPA and megestrol acetate, MA) treatment on serum hormone levels was studied in ten postmenopausal women with advanced breast cancer. The gonadotropins and ACTH were significantly reduced by greater than 50 and 23%, respectively. Serum cortisol, DHEAS, androstenedione and testosterone were all significantly reduced (mean reduction between 64 and 76%), while serum estrone, estradiol and estrone sulfate were significantly reduced by 20-30%. Sex hormone binding globulin (SHBG) and corticosteroid binding globulin (CGB) were reduced by 68 and 25%, respectively. Although the dose of MA used (160 mg/day) was only 1/6 of the MPA dose (1000 mg/day), the mean serum level of MA was 2-fold higher than the mean serum level of MPA. MPA treatment gave a more pronounced suppression of SHBG than MA treatment, while estrone sulfate levels were more suppressed by MA. These findings suggest a differential effect of MPA and MA on certain plasma hormones, possibly of importance for understanding the mechanism of action of the two drugs. The reduction of estrone sulfate may be beneficial for the action of MA against breast cancer.

Aged↗
PubMed1990

Plasma atrial natriuretic factor concentration during maximal cardiopulmonary exercise in men with mild heart failure.

The response in terms of production of atrial natriuretic factor to maximal cardiopulmonary exercise was investigated in 13 patients with mild heart failure (New York Heart Association function class II) secondary to previous myocardial infarction. Exercise induced a rapid and gradually increasing production of atrial natriuretic factor. The concentration at the termination of the test was statistically higher than at rest (64.5 +/- 9.7 versus 119.4 +/- 18.3 pmol/l. P = 0.001). Resting levels of the natriuretic factor correlated well to levels at peak exercise (r = 0.797, P = 0.001). The increase in concentration from rest to peak exercise (atrial natriuretic factor delta) was inversely correlated to the peak consumption of oxygen (r = -0.584, P = 0.036), indicating that the response to exercise is not attenuated in the patients with most marked functional impairment. The relationship between resting levels of atrial natriuretic factor and peak consumption of oxygen did not reach statistical significance (r = -0.421, P = 0.152), but a significant inverse relationship was observed between concentration at peak exercise and peak consumption of oxygen (r = -0.671, P = 0.012). Levels of atrial natriuretic factor during peak exercise are related to functional impairment in mild heart failure and may discriminate between the functional capacity of patients belonging in the same class of clinical function.

Aged↗
PubMed1990

Guidelines for description of immunoassay kits.

A provisional recommendation in order to improve manufacturers' and marketers' information to users of immunoassay kits has been compiled by a Nordic Clinical Chemistry project working group.

Chemistry, Clinical↗
PubMed1989

Autologous down-regulation of messenger ribonucleic acid and protein levels for estrogen receptors in MCF-7 cells: an inverse correlation to progesterone receptor levels.

In the present study we have examined the effects of estradiol on mRNA levels for estrogen (ER) and progesterone receptors (PR) in the estrogen-dependent mammary carcinoma MCF-7 cell line. The changes in ER immunoactivity and specific binding of [3H]R5020 were also assessed. Estradiol (10(-7) M) caused a transient and time-dependent reduction of the level of mRNA for ER, with a maximal effect (30-40% of control; n = 3) after 72 h. This was associated with a similar decrease in ER immunoactivity. Further treatment (96 and 120 h) revealed a return of ER mRNA to control values, whereas the ER immunoactivity remained depressed. The effect on the mRNA level for PR gave almost the inverse curve. Initially (24-72 h), we observed a pronounced increase in this mRNA, with a maximal effect (6-7 times the control value; n = 3) after 72 h. Treatment beyond 72 h was associated with a gradual return of mRNA for PR toward the control level. The variation in specific binding of [3H]R5020 revealed similar changes, except that changes in specific receptor binding were delayed 24 h compared to the levels of mRNA. Incubation with low concentrations (10(-11) and 10(-10) M) of estradiol for 72 h was associated with slightly elevated levels of mRNA for ER, whereas higher concentrations gave a dose-dependent decrease. The mRNA for PR was biphasically stimulated, with a maximal effect at 10(-10)-10(-8) M, where a 10- to 13-fold stimulation was observed. The highest concentration (10(-7) M) gave a lower response. Assessment of concentration-induced variations in protein receptor levels of ER and PR reflected the effects of estradiol on their mRNAs. Low concentrations of estradiol slightly enhanced the ER level, whereas high concentrations clearly reduced ER immunoactivity. The PR level was stimulated by all concentrations used, and 10(-8) M estradiol raised the PR level more than 11-fold. Our results indicate autologous regulation of estrogen receptor gene transcripts and proteins and a clear induction of PR mRNA and receptor proteins by estradiol.

Adenocarcinoma↗
PubMed1989

Chemotherapy and endocrine function in lung cancer.

To investigate whether cyclic chemotherapy for lung cancer influenced endocrine function, we monitored thyroxine, cortisol, testosterone, sex hormone binding globulin (SHBG), estradiol, FSH, LH, and transcortin every three weeks in 12 male patients. Treatment regimens consisted of cisplatin and etoposide in 9 patients, or vincristine, doxorubicin, and cyclophosphamide in 3 patients. SHBG and FSH level were significantly elevated after 6 to 9 weeks of therapy, whereas the other variables were unchanged. The results suggest that the therapy induces endocrine gonadal dysfunction. The increments in SHBG levels reflect a considerable fall in free testosterone, and may effect alterations in total androgen/estrogen ratios. The mechanism underlying the increased SHBG levels is unknown.

Aged↗
PubMed1988

Pharmacokinetics and metabolism of medroxyprogesterone acetate in patients with advanced breast cancer.

The pharmacokinetics and metabolism of medroxyprogesterone acetate (MPA) were studied in patients with advanced breast cancer after i.v. injection and oral administration of [3H]MPA. MPA was distributed very rapidly into three compartments after i.v. injections, revealing half-lives of 4-7 h. Using a nonlinear model fitting metabolic clearance rates (MCR) were found to be 652 1/day before and 601 1/day during MPA treatment, and distribution volumes (V0) 5.9 and 3.41 respectively. The major metabolite of MPA following i.v. injection was a glucuronide of MPA, presumably of the 3-enol form. After oral administration the radioactivity in serum increased rapidly and reached a plateau of about 1% of the dose per litre serum after approx 2 h. About 80-90% of the radioactivity was found in the water phase after hexane extraction, persumably as glucuronides of metabolites more polar than MPA. Radioimmunoassay (RIA) of MPA in untreated serum samples showed 3-8-fold greater MPA values as compared to measurements in hexane extracts of serum. Ethanol extraction did not remove these interfering substances. Extraction of serum with a low polar solvent before RIA of MPA is essential in order to prevent great overestimation, as the glucuronidated polar metabolites most likely will crossreact in an assay with an antiserum raised against a MPA-3-O-carboximethyloxime coupled to bovine serum albumin.

Administration, Oral↗
PubMed1987

Androgen-oestrogen imbalance in men with chronic alcoholism and fatty liver.

The plasma concentrations of oestrone (E1), oestradiol (E2), oestrone sulphate (E1S), testosterone (T), sex hormone binding globulin (SHBG) and apparent free testosterone (AFTC) were measured in 20 normal-weight men with chronic alcoholism and fatty liver. Twenty normal-weight male blood donors matched for age acted as controls. In the alcoholic subjects (patients) the plasma levels of E1, E2 and SHBG were significantly elevated, whereas the concentrations of E1S and AFTC were significantly decreased. No difference in plasma T was seen between the two groups. Both patients and controls showed a significant correlation between SHBG and E2, whereas a significant correlation between SHBG and T, and between E2 and T, was only found in the controls. Eight of the patients showed signs and/or symptoms of hypogonadism or feminization. Only patients with hypogonadism and/or feminization showed significantly higher plasma levels for E2 and decreased T/E2 ratio than matched controls. The ratio E1S/E1 was in every case lower than in the control and tended to be even lower in the patients with hypogonadism and/or feminization.

Adult↗