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R Gärtner

Publications and source records attributed to R Gärtner.

At least 91 records · Page 5Linked to original sources
PubMed1985

Involvement of cyclic AMP, iodide and metabolites of arachidonic acid in the regulation of cell proliferation of isolated porcine thyroid follicles.

Experiments with primary cultures of isolated porcine thyroid follicles were performed in serum-free well-defined medium to investigate different pathways that may be involved in the regulation of thyroid cell growth. The incorporation of [3H]thymidine into DNA within 72 h was about 25-fold with fetal calf serum (FCS, 1%), 20-fold with epidermal growth factor (EGF, 1 ng/ml) and 3.5-fold with insulin (10 micrograms/ml) as compared to controls. Bovine TSH significantly reduced the basal and insulin-induced growth rate at concentrations of 10(-6) to 10(-4) U/ml and 10(-4) U/ml, respectively. Forskolin stimulated cyclic AMP accumulation in thyroid cells and significantly reduced FCS-, EGF- or insulin-induced growth. In contrast, a 2- to 7-fold increase in FCS-, insulin- or EGF-induced growth rate was found, when cyclic AMP formation was inhibited by 2',5'-dideoxyadenosine (DDA). Iodide was stimulatory at low concentrations (1 microM) and inhibitory at higher concentrations (40-80 microM) on FCS-induced growth rate. The inhibitory effect of iodide was blocked by propylthiouracil (PTU), indicating that an iodinated compound is responsible for this effect. Indomethacin, a cyclooxygenase inhibitor, did not inhibit EGF- and insulin-induced growth up to a concentration of 100 microM. However, nordihydroguaiaretic acid (NDGA) and BW-755C, which are lipoxygenase inhibitors, strongly inhibited the growth of thyroid cells at micromolar concentrations. These data clearly show that (1) bovine TSH is not a growth factor for isolated thyroid cells in vitro, (2) thyroid cell proliferation, induced by FCS, EGF and insulin is under negative control of cyclic AMP. (3) Iodide controls dose-dependently thyroid cell growth by iodinated metabolites, probably modulating 2 different pathways: (a) at low iodide concentrations, an iodinated compound enhances the growth rate by inhibition of cyclic AMP formation, and (b) at high concentrations, iodide diminishes the growth rate by inhibiting the response to growth factors. (4) Metabolite(s) of lipoxygenase appear to be involved in intracellular signal transduction evoked by growth factors in thyroid cells.

4,5-Dihydro-1-(3-(trifluoromethyl)phenyl)-1H-pyraz↗
PubMed1985

Preparation of porcine thyroid follicles with preserved polarity: functional and morphological properties in comparison to inside-out follicles.

One of the main problems in establishing isolated thyroid follicles in vitro is their tendency to form inside-out follicles. The reason for this change in polarity is unknown. We describe here a method for the preparation of stable thyroid follicles with preserved polarity for at least 6 days. Isolated follicles were obtained by infusion of collagenase (1.5 mg/ml) dissolved in minimal essential medium into the artery of intact thyroid glands. The morphological and functional properties of these follicles were compared to inside-out follicles. These inside-out follicles were obtained by digestion of minced thyroid tissue in a collagenase (1 mg/ml) solution. The polarity of follicles was proved by morphological criteria. Follicles with preserved polarity did not change polarity for at least 6 days in the presence of 1% or 5% fetal calf serum. As the culture conditions for both preparation methods were identical, we conclude that the preparation method rather than the culture condition is responsible for the preservation of cell polarity of isolated thyroid follicles in our system. Increases in cyclic AMP levels induced either by bovine thyrotropin (10(-3) U/ml) or by isoproterenol (10(-6) M) as well as iodide uptake and organification were rapid and significant in right-side-right follicles but not in inside-out follicles. Therefore the TSH receptor and the beta-adrenergic receptor appear to be exclusively located at the basal membrane of follicular cells. In addition, iodide uptake apparently is unidirectional.

Animals↗
PubMed1985

Characterization of microheterogeneity of human thyroglobulin from different thyroid disorders.

Human thyroglobulin (Tg) was isolated to apparent purity from various thyroid tissue samples obtained after surgery. Iodine and iodothyronine content of Tg was determined. Isoelectric focussing (IEF) was performed on thin layer agarose gels. Tg revealed a microheterogeneity of 6 bands in the range between pH 4.2 and 4.6. The intensity of the single bands depended on the iodothyronine content of Tg. With increasing degree of iodination, the bands with a lower pI (pI 4.35, 4.40) became more prominent, whereas the bands with higher pI (pI 4.55, 4.60) diminished. This typical change in microheterogeneity pattern could be confirmed by kinetic in vitro iodination and consecutive iodothyronine formation of low iodinated Tg (0.05% iodine). After in vitro desialylation, the bands shifted to a higher pH range (pH 4.60 to pH 4.90), but no reduction of the number of bands occurred. Even in desialylated Tg microheterogeneity is still dependent on iodine content. These results suggest, that the microheterogeneity of Tg is influenced, but not caused by different iodine and NANA content. Different polypeptide composition may be responsible for the microheterogeneity of Tg. In thyroid diseases without disturbance in Tg synthesis (endemic, diffuse and nodular goitre, Graves' disease) variations in relative intensity of single bands could be related to differences in iodine content. In thyroid cyst fluid and cold nodules in addition to low iodinated Tg, further bands were found with pI-values comparable to desialylated Tg.

Adenoma↗
PubMed1983

The first external quality control survey (EOCS) for antithyroglobulin- and antimicrosomal antibody determination.

Fourteen laboratories participated in an external quality control survey (EQCS) for antithyroglobulin- and antimicrosomal-antibody determination. Seventeen frozen serum samples from individuals suffering from various thyroid diseases were dispatched by mail. Different test systems were used by the participants including the haemagglutinatin test, radioimmunoassay (RIA), enzyme immunoassay (ELISA) and immunofluorescence test. The different test results of each participant were sized and could be compared by giving place numbers to each test result. Inter-laboratory quality control was performed by evaluation of a rank correlation coefficient. There was close agreement between the haemagglutination test results of antimicrosomal antibody determination with different test kits, and these tests showed good precision. Antithyroglobulin antibody titers from the two haemagglutination test-kits used, however, were not directly comparable. When sized by place numbers, antithyroglobulin antibody results from haemagglutinatin test, RIA and ELISA were in close agreement. The least correspondence was shown by the immunofluorescence test, in the antithyroglobulin antibody determination.

Antibodies↗
PubMed1981

Thyroxine-binding globulin: investigation of microheterogeneity.

Preparations of T4-binding globulin (TBG) from human serum was performed using only two affinity chromatography steps. Purity of the protein was demonstrated by a single band in overloaded disc and sodium dodecyl sulfate electrophoresis, equimolar binding to T4, and linearity in sedimentation velocity run. The molecular weight was calculated to be 60,000 +/- 3,000 daltons (n = 3), the sedimentation coefficient was 3.95S, and the Stokes' radius was 37 A. The amino acid composition was found to be in good agreement with the calculations of other authors. By isoelectric focussing (IEF), pure TBG showed four main bands at pH 4.25, 4.35, 4.45, and 4.55 together with several fainter bands. The N-acetylneuraminic acid (NANA) content of the four TBG bands isolated by preparative IEF was found to decrease from 10.2 mol NANA/mol TBG in the band at pH 4.25 to 4.8 mol NANA/mol TBG in the band at pH 4.55. No significant difference in the affinity constants of the TBG bands to T4 was found. The affinity constants for TBG ranged from 3.1 x 10(9) to 7.2 x 10(9) M-1. Sequential kinetic desialylation of pure TBG resulted in a progressive tendency toward one major band at pH 6.0. In native sera, microheterogeneity of TBG was detected after IEF on polyacrylamide gel plates by immunofixation. The typical TBG patterns shown by pure TBG were also found in normal subjects. Characteristic deviations from this pattern were found in the sera of females during estrogen therapy or pregnancy, where there was a gradual increase in density of the band at pH 4.25 and the appearance of an additional band at pH 4.15. In sera from patients with liver disease and elevated TBG levels, there was a fading of the acidic bands, whereas the more alkaline band at pH 4.55 was intensified. It is therefore proposed that microheterogeneity of TBG is caused by differences in NANA content and that variations of TBG patterns in native sera may reflect altered TBG synthesis or degradation. A genetically related microheterogeneity of TBG could not be demonstrated after examination of 800 sera, including 2 families with quantitative TBG deficiency.

Amino Acids↗
PubMed1977

[Therapeutic experience with 5-chloro-8-hydroxyquinoline].

This paper reports on the clinical trials of an antimycoticum using 5-chlorine-8-hydroxychinolin as an antimycotic agent. 142 patients with surface dermatomycoses were treated locally with the preparation for 5 to 6 weeks. Clinical and mycological healing was achieved in 68% of the cases. The results of the treatment, the epicutaneous tests and the additional UV exposition are discussed. The best results of treatment were obtained in the case of superficial dermatomycoses, in particular Trichophytia inguinalis.

1-Propanol↗
PubMed1976

[Muscle metabolism of glucose, lactate, free fatty acids, and glycerol at rest and during electrically stimulated exercise in the perfused rat hind limb (author's transl)].

The influence of insulin on muscle metabolism at rest and during electrically stimulated exercise was examined in the perfused rat hind limb. Basal glucose uptake of muscle tissue was enhanced threefold both by muscle contraction an by addition of physiological amounts of insulin. A further increase in glucose uptake was seen, when muscle was exercised in the presence of insulin. Lactate production rose 7 - 8fold by contractions. Insulin had no additional effect on lactate production during exercise. The work-induced lactate output exceeded glucose uptake, corresponding to a significantly reduced glycogen content after exercise. Basal lipolysis was not stimulated by muscle contractions. At rest the addition of both corticosterone and thyroxine did not increase the basal lipolysis. Yet, glycerol release rose twofold by the addition of serum to the perfusion medium. It is assumed that in the perfused rat hind limb glycogenolysis will promptly be stimulated by muscle contractions, whereas lipolysis can not be enhanced by exercise alone.

Animals↗