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Biomedical subjects

K Endo

Publications and source records attributed to K Endo.

At least 883 records · Page 49Linked to original sources
PubMed1979

[Studies on the radioreceptor assay of TSH: the binding of 125I-TSH to the human thyroid receptor and the interaction of LATS-IgG (author's transl)].

The radioreceptor assay system for TSH is considered to be useful in quantitating the hormone and analyzing the mechanism of its action. The assay was established, and the interaction of abnormal thyroid stimulators in Graves' patients was evaluated in this assay system. A 10,000xg fraction of human thyroid homogenates was used as the receptor. Human TSH supplied from NIH was iodinated by using lactoperoxidase. The binding of 125I-TSH to the receptor was small, and 125I-TSH was further purified by the receptor binding. The receptor (25mg equivalent), purified 125I-TSH, and standard TSH or a sample were incubated at 37 degrees C for 60 min in a final volume of 300 microliters. The binding of 125I-TSH to the receptor was time- and temperature-dependent with optimal binding under the conditions described above. The binding was completely inhibited by the addition of human, bovine and ovine TSH and partially inhibited by high concentrations of HCG, FSH-LH. However, there was no cross reactivity with insulin, prostaglandin E1, E2, T3, T4 and Nal. The assay was sensitive enough to detect 5 to 50 microU of TSH. The amount of TSH bound to the receptor was almost parallel to the TSH concentration which is necessary to stimulate human thyroid adenylate cyclase activity. Studies of dissociation kinetics and Scatchard plot indicated that there were two classes of TSH receptors in the human thyroid. A higher association constant was calculated as 1.5 x 10(8)M-1. LATS-IgG from a patient with Graves' disease completely inhibited the binding of 125I-TSH to the receptor, and studies of Lineweaver-Burk, plot suggested that TSH and LATS-IgG shared common binding sites. The radioreceptor assay of TSH appears to be useful in evaluating the abnormal thyroid stimulators present in Graves' disease.

Binding, Competitive↗
PubMed1979

[Studies on the radioreceptor assay of TSH: the properties of TSH-binding inhibitor immunoglobulins (TBII) in patients with Graves' disease (author's transl)].

In the radioreceptor assay system for TSH, serum immunoglobulin G (IgG) from some patients with Graves' disease has been shown to inhibit the binding of labelled TSH to its receptor sites. In order to clarify the properties of these TSH-binding inhibitor immunoglobulins (TBII) in patients with Graves' disease, TBII were measured in sera from 31 untreated and 51 131I-treated patients, and their relation to clinical and laboratory findings was studied. TBII were detected in 18 (60%) out of 31 patients with untreated Graves' disease. TBII levels in these patients correlated well with thyroidal 99mTc uptake at 30 min and also with the grade of epithelial hyperplasia of thyroid follicles. There was no significant correlation between TBII and serum T3, serum T4, free T4 index, antibody titers against thyroglobulin and microsomes, or association of exophthalmos. There were many patients with Graves' disease whose sera contained high TBII levels but no detectable bioassayable thyroid-stimulating activity (LATS), and in these patients a close correlation was observed between serum levels of TBII and bioassayable LATS-protector activity. In patients with Graves' disease who had been treated by 131I from 5 to 17 years before, the incidence of TBII was very low at 20% (10/51). All except two cases having TBII were found to be still thyrotoxic. Thus, TBII were detected in 8 out of 10 thyrotoxic patients and in only 2 out of 18 euthyroid and none of 23 hypothyroid patients. These findings suggest that TBII in patients with Graves' disease were in close association with human thyroid stimulating activity, and that TBII might be useful as an indicator for checking the effectiveness of the treatment.

Autoantibodies↗
PubMed1979

[Studies on the radioreceptor assay of TSH: the properties of TSH-binding inhibitor immunoglobulins (TBII) in patients with Hashimoto's thyroiditis (author's transl)].

TSH-binding inhibitor immunoglobulins (TBII) have been detected not only in patients with Graves' disease but also in those with Hashimoto's thyroiditis by using the radioreceptor assay of TSH. In the present study, the properties of TBII in patients with Hashimoto's thyroiditis are discussed. Two (7%) of 29 patients with Hashimoto's thyroiditis had detectable levels of TBII in their gamma-globulin fractions. Both patients were untreated and clinically hypothyroid. One of them had no goiter, and her thyroidal 99mTc uptake was 0% (normal range: 0.4 approximately 3.0%). Despite having potent TSH-binding inhibitor activity in the TSH radioreceptor assay, her serum or its IgG fraction (H-IgG) did not contain any significant anti-TSH antibody, LATS, LATS-protector or human thyroid adenylate cyclase (AC) stimulating activity. This H-IgG inhibited both human thyroid AC stimulation and c-AMP increase in mice thyroid glands induced by TSH or LATS. Furthermore, her serum caused significant inhibition of 131I-release by LATS in a McKenzie mouse bioassay. The present study demonstrates that the serum of one patient with Hashimoto's thyroiditis contained antibodies which 1) blocked the binding of lablled TSH to the receptor, 2) had no thyroid-stimulating activity by themselves, and 3) inhibited AC stimulation by TSH. Such antibodies may cause unresponsiveness to TSH stimulation, hypothyroidism, and, if this state persists for a long time, eventually may result in atrophy of the thyroid tissue. Further, these data indicate that TBII detected by the TSH radioreceptor assay did not always show thyroid stimulating activities.

Adolescent↗
PubMed1979

Effects of the host matrix on the 57Fe-species produced through EC-decay in 57Co-labelled tris(phenanthroline) cobalt (II) perchlorate.

Emission Mössbauer spectroscopic studies of 57Co-labelled [Co(phen)3]clO4)2 in host matrices [M(II)(phen)3](ClO4)2(M=Co, Fe, and Ni) indicate that the relative intensities of the anomalous species produced through the EC-decay depend on the kind of the host matrix. The largest intensity was observed with the cobalt (II) matrix, and the smallest with the iron (II) matrix. Emission spectra of 57Co-labelled [Co(2-CH3-phen)3](ClO4)2 2H2O in the matrix of [Fe(2-CH3-phen)3](ClO4)2 were also studied. The high-spin state (5T2) was predominantly observed at 4.2 K in the emission spectrum, while the low-spin state (1A1) was mainly observed in the absorption spectrum at 78 K. The results are discussed in terms of the stability of the lattice.

Cobalt Radioisotopes↗