Biomedical subjects

K M Gautvik

Publications and source records attributed to K M Gautvik.

At least 163 records · Page 9Linked to original sources

PubMed1976

Rat submandibular gland kallikreins: purification and cellular localization.

1 Four submandibular gland kallikreins (E.C.3.4.21.8) were isolated by chromatography on DEAE-Sephadex A-50 and hydroxyapatite, followed by gel filtration and electrofocusing. The pI values were 3.87, 3.96, 4.07 and 4.16, and a common molecular weight of 34,000 was found. 2 The kallikreins were localized by direct immunofluorescence with an antibody to rat urinary kallikrein, to the granular tubules, striated duct cells and some main duct cells in the submandibular gland, and to striated duct cells in the sublingual gland. Kallikrein was not found in acini and stroma. 3 Several non-kallikrein esterases present in the submandibular gland reacted with the antibody to rat urinary kallikrein. The antibody was made monospecific for kallikrein by absorption with the crossreacting esterases. 4 We suggest that kallikrein is produced in striated duct cells. Granular tubules, which are differentiated from striated duct cells, have preserved the ability to produce kallikrein. These cells also store large quantities of kallikrein.

Animals↗

PubMed1976

Measurements of prolactin and growth hormone synthesis and secretion by rat pituitary cells in culture.

A specific and sensitive immunoprecipitation method for measurements of biosynthesized radioactive prolactin and growth hormone is described. Antisera to rat prolactin and growth hormone were developed in the rabbit and monkey, respectively. The specificity of the immune sera was assessed by polyacylamide gel electrophoresis of the dissolved immunoprecipitates. The two antisera showed cross-reactions with the nonhomologous hormone of less than 1%. Separation of tritium-labelled prolactin and growth hormone by immunoprecipitation, followed by polyacrylamide gel electrophoresis in the presence of sodium dodecyl sulphate was shown to be 95-57% complete. When both hormones were measured in the same microsample by sequential immunoprecipitation, the reaction was 97% complete for determination of intra- and extracellular prolactin and extracellular growth hormone, but 85% complete for determination of intracellular growth hormone. This method has been used to characterize the basal synthesis and secretion of prolactin and growth hormone in three different but related, pituitary cell strains. Radioactive prolactin and growth hormone was obtained from monolayer cultures when the cells were grown in the presence of [3H]L-leucine. The rate of prolactin synthesis and extracellular accumulation was higher than that of growth hormone in a cell strain which produced both hormones. In these cells prolactin synthesis represents 1-5%, and growth hormone 0.1-0.6% of total protein synthesis.

Animals↗

PubMed1976

Effects of prostaglandins on prolactin and growth hormone synthesis and secretion in cultured rat pituitary cells.

The effects of prostaglandins E1, E2, F1alpha, and F2alpha on prolactin and growth hormone synthesis and secretion were studied in cultured rat pituitary cells. Total extracellular accumulation of prolactin was measured by radioimmunoassay. When hormone synthesis was studied, the cells were cultured in the presence of [3H]leucine for the last hour of each treatment period. The intra- and extracellular radioactive hormones were determined in the same microsample by a specific and quantitative immunoprecipitation method, employing polyacrylamide gel electrophoresis in the presence of sodium dodecyl sulphate. The results show that all prostaglandins stimulated the extracellular accumulation of prolactin at 3-30 nM. Prostaglandin E1 was more effective in stimulating extracellular accumulation of prolactin than prostaglandin E2 and the F compounds. Prostaglandin F2alpha at 3 nM doubled the rate of prolactin synthesis, but had no effect on growth hormone or total cell protein synthesis after 24 h of treatment. The first effect of prostaglandin F2alpha was observed after 5 h of incubation, and the time-course of effect on prolactin synthesis was similar to that of thyrotropin-releasing hormone.

Animals↗

PubMed1976

A possible role of cyclic AMP in mediating the effects of thyrotropin-releasing hormone on prolactin release and on prolactin and growth hormone synthesis in pituitary cells in culture.

Thyrotropin-releasing hormone (TRH) has 3 effects on clonal strains of rat pituitary cells in culture (GH-cells). Two long-term effects of TRH on GH-cells, which are measurable after 3 h or longer, have been previously reported; these are an increase in prolactin synthesis and a decrease in growth hormone production. We report here that TRH also stimulates the rapid release of stored intracellular prolactin. We have investigated the role of cyclic AMP as a possible mediator of the effects of TRH on GH-cells. Cyclic AMP concentrations are higher in cells treated with TRH compared with paired controls; a maximum difference of greater than 150% of control values is detected at 15 min if the incubation is performed in serum-free medium in the presence of 1 mM theophylline. The concentration of TRH required to give half-maximum increases in both prolactin release and cyclic AMP accumulation is 0.3 nM; half-maximal increases in prolactin synthesis occur at 3 nM TRH. Exogenous cyclic AMP (1 mM) causes only a slight increase in prolactin release; 8-bromo-cyclic AMP and 8-methylthio-cyclic AMP (1 mM) do not cause significant release. Phosphodiesterase inhibitors (0.3 mM theophylline, 0.03 mM isobutyl-methylxanthine) increase prolactin release but their effects on hormone synthesis are more complicated. Isobutylmethylxanthine, 8-bromo-cyclic AMP and 8-methylthio-cyclic AMP (0.4 MM) increase prolactin synthesis, but do not significantly affect growth hormone synthesis. Theophylline increases the synthesis of both hormones. Dibutyryl cyclic AMP (0.5 mM or more) increases prolactin release and both growth hormone and prolactin synthesis, but equivalent amounts of sodium butyrate have the same effects. We conclude that in GH-cells under carefully defined experimental conditions: 1) TRH causes an increase in intracellular cyclic AMP concentrations; 2) the increase in endogenous cyclic AMP and the effects of phosphodiesterase inhibitors are consistent with a model with cyclic AMP as a mediator of the effects of TRH on prolactin release; however, they do not prove this model, because the interpretation of these results depends on assumptions which may not all be valid; and 3) none of the analogs of cyclic AMP or the phosphodiesterase inhibitors tested mimic the decrease in growth hormone production caused by TRH.

Animals↗

PubMed1976

Effects of sex steroids on prolactin secreting rat pituitary cells in culture.

A clonal strain of rat pituitary tumor cells (GH3) was used to study the effects of different sex steroids on the production of prolactin (PRL). Hormone production was measured by radioimmunoassay and expressed as the amount of hormone which accumulated in the medium of monolayer cultures during 24 h. The stimulatory effect of 17beta-estradiol (10(-11)M-10(-6)M) on PRL production was significant after 4 days and the maximum effect (300% of control cultures) was observed at 10(-8)M after 10 days of treatment. After removal of added 17beta-estradiol, the production of PRL returned to control levels in 5 days. Progesterone (10(-11)M-10(-6)M) caused a dose-related decrease in PRL production reaching 60% of control values at 10(-6)M. Testerone (10(-6)M) stimulated the production of PRL (130% of controls), whereas 5alpha-dihydrotestosterone (10(-6)M) had a small effect (107% of controls) which was not always reproducible. None of the sex steroids affected cell growth. Progesterone (10(-6)M) inhibited the stimulatory effect of 17beta-estradiol (10(-8)M) on PRL production. The effect of 17beta-estradiol (10(-8)M) and thyrotropin releasing hormone (TRH) (3 X 10(-7) M) was addititive, while no additional stimulatory effect was observed when 17beta-estradiol (10(-8)M) was combined with testosterone (10(-6)M). If the properties of the GH3 cells are analogous to those of normal lactotropes, the sex steroids may alter PRL production at the pituitary level, an influence that may be further modulated by TRH.

Cell Line↗

PubMed1976

Radioimmunoassay of rat prolactin and its use in measuring prolactin production by cultured pituitary cells.

A sensitive and specific radioimmunoassay has been developed for rat prolactin (rPRL), employing the double antibody solid phase technique for the separation of free and antibody-bound [125I]rPRL. The anti-serum was raised in rabbits and showed no cross-reaction with rat growth hormone (rGH), follicle stimulating hormone (rFSH), luteinizing hormone (rLH) and thyrotrophin (rTSH). The immunosorbent (sheep anti-rabbit IgG bound to cellulose) showed a surprisingly high binding of [125I]rPRL, but not of the other iodinated anterior pituitary hormones. Addition of serum to the incubation mixtures prevented the binding between [125I]rPRL and the immunosorbent. Three different clonal strains of pituitary cells have been examined for production of rPRL, rLH and rTSH, both in the basal state as well as after treatment with thyrotrophin releasing hormone (TRH) and gonadotrophin releasing hormone (LH/FSH-RH). Monolayer cultures of two of the cell strains produced and secreted rPRL spontaneously, and they showed a 2-fold increase in rPRL production after treatment with TRH (3-10(-7) mol/1). The third cell strain did not produce rPRL spontaneously, or after treatment with TRH. None of these cell strains could be stimulated to produce rTSH by treatment with TRH. Treatment of the same three cell strains with LH/FSH-RH (1.2-10(-6) mol/1) failed to induce production of rLH, and there were no changes in production of rPRL. Prostaglandins E1 and E2 (3-10(-8) mol/1) and oestradiol-17beta (10(-7)-10(-10) mol/1), however, stimulated the production of rPRL. The effects of TRH and prostaglandins E1 and E2 were observed within 24 h of treatment, while the first effect of oestradiol-17beta was seen after 3 days. These results suggest that the stimulatory effect of oestradiol-17beta on rPRL production differs from that of TRH and prostaglandins.

Animals↗

PubMed1976

Medullary carcinoma of the thyroid in Norway. Clinical course and endocrinological aspects.

A study of the clinical, biochemical and histological findings of 57 patients with medullary thyroid carcinoma (MCT) in Norway, is presented. The diagnosis was established by light and electron microscopy and by measurements of immunoreactive calcitonin (iCT) in serum. The major factor influencing the prognosis was the extension of the disease at presentation. None of the 24 patients with tumour confined to the thyroid gland have died of the disease, and serum iCT was normal in 15 patients. Of 19 patients with regional lymph node metastes only 11 are alive 1 to 14 years after treatment, and of these 9 had increased serum iCt. 14 patients technically inoperable and/or with distant metastases, 12 have died of MCT, 1 are alive with elevated serum iCT. Of 14 patients with raised serum iCT, 8 have no clinical recurrence of the disease from 1 to 15 years after the operation. MCT-associated diseases were found in 8 patients, chronic thyroiditis in 10. Serum iCT was measured in 249 relatives of 42 patients, and abnormal elevations were found in 11 members of 6 families.

Adolescent↗

PubMed1976

Radioimmunoassay of human calcitonin in serum and tissue from healthy individuals and patients with medullary carcinoma of the thyroid gland.

A specific radioimmunological method for measurement of immunoreactive calcitonin (iCT) in human serum and tissue is decribed. Of healthy individuals of both sexes, 85% had measurable iCT in serum (mean, 0.23 ng/ml). Of 29 patients who had received treatment for medullary carcinoma of the thyroid gland (MCT), 19 had increased serum iCT (0.60 ng/ml to 205 ng/ml). Elevated serum iCT was also found preoperatively in 2 MCT patients. Eleven of the patients with abnormal elevations of serum iCT were alive 4 to 13 years after the operation. Concentration of iCT in extracts from MCT varied from 0.5 to 540 ng/ml wet weight. The diagnostic value of this method and its importance for pre- and post-operative evaluation of these patients are improved by the use of selective venous catheterization in basal state and during stimulation of CT secretion.

Adult↗

PubMed1974