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  • Author: Kiyoshi Miyai x
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Yoshiaki Kawai, Mizuo Azukizawa, Nobuyuki Ashida, Yuichi Kumahara and Kiyoshi Miyai

Abstract. TRH (10 and 1000 μg/kg body weight) was administered ip daily to neonatal rats from day 0 to 9 after birth (Neo-TRH rats) and their pituitary-thyroid axis was examined on days 4, 10, 21 and 90. The pituitary TSH content in Neo-TRH rats was significantly smaller than in controls on days 4 and 10. The serum TSH levels in Neo-TRH rats were significantly lower than those in controls on days 4 (male group only), 10 and 21 (only 10 μg/kg group).

The serum T4 levels in Neo-TRH rats were lower than in controls on day 10. The reduced pituitary TSH content and serum TSH and T4 were restored to control levels on day 90. However, the response of serum TSH to exogenous TRH (10 μg/kg/ip) was blunted in Neo-TRH rats on days 10, 21 and 90. It is concluded that repetitive administration of TRH during the neonatal period suppresses the pituitary-thyroid axis in neonatal life, even after the basal hormone level has been restored to normal.

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Minoru Fukuchi, Tohru Matsuoka, Tadashi Inoue, Kiyoshi Miyai and Yuichi Kumahara

ABSTRACT

Serial changes in TSH, LATS, and thyroxine levels in the sera were studied following administration of an antithyroid drug or a thyroid hormone to thyrotoxic patients who became euthyroid after treatment. These changes were simultaneously determined by means of human TSH radioimmunoassay, McKenzie's bioassay. and the method of Murphy, respectively.

Administration of 1-methyl-2-mercaptoimidazole (MMI) led to a decrease in thyroxine concentration and to a 6–10 times increase of the initial values in serum TSH concentration. Following administration of thyroxine at the end of the MMI treatment, the elevated serum TSH was rapidly decreased with an increase in thyroxine concentration. LATS activity, however, showed no significant changes throughout these experiments in which the reciprocal changes between TSH and thyroxine concentrations were observed.

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Yuichi Endo, Kiyoshi Miyai, Yasushi Iijima, Toshihiro Nakajima, Yasuyuki Eda, Haruo Fujita and Masanori Unoki

Abstract. Epitope mapping of hTSH was carried out using 19 monoclonal antibodies prepared with hTSH or its β-subunit as antigen. The affinity constants of the monoclonal antibodies ranged from 9.6 × 107 to 5.7 × 109 mol/l for hTSH. The binding activities of monoclonal antibodies were maintained or in some cases rather enhanced after removal of the sugar moeity of the subunits of hTSH, and completely diminished after reduction of intramolecular S-S bonds in the subunits of hTSH. Ten monoclonal antibodies recognized the epitopes on hTSH (α:β subunit combined form) and on free α-subunit form. Eight other antibodies recognized the epitopes on free/or combined form of β-subunit, all of which did not recognize any other human glycoprotein hormones. The monoclonal antibodies directed against the α-subunit could bind also other human glycoprotein hormones to a varying extent. On the basis of results from competitive binding studies, the antibodies directed against α-subunit and those against β-subunit were each classified into five subgroups recognizing different antigenic determinants. The remaining one antibody recognized an epitope expressed only by hTSH and not by the free subunits. In addition, a positive cooperativity on the binding of hTSH was observed between monoclonal antibodies directed towards a particular epitope on the α-subunit and those towards an epitope on the β-subunit. From these data, two-dimensional map of epitopes on hTSH was constructed. The epitopes on each subunit were found to form a cluster with complicated overlapping, suggesting a highly conformational structure.