Taeko Shimizu

Gonadotroph Adenoma of the Pituitary Mimicking a Prolactinoma

In a 41-year-old woman with mild hyperprolactinemia and amenorrhea, preoperative hormonal and neuroradiological findings suggested the diagnosis of a macroprolactinoma. She underwent transsphenoidal surgery since the tumor size had not changed in spite of bromocriptine administration for 5 months. Consequently, this case was diagnosed as a female-type gonadotroph adenoma on the basis of its characteristic ultrastructural features including a honeycomb Golgi complex, even though endocrinological and immunohistochemical findings were not those of a typical gonadotroph adenoma.

Studies on the Accumulation of Thyroxine in Isolated Bovine Thyroid Cells

By the use of isolated bovine thyroid cells (ITC), accumulation of T4 in thyroid tissue has been studied. ITC were chosen to disclose this thyroid cell function per se by eliminating the effect of follicular structure and contaminated serum. Cell/medium ratio (C/M) of 125I-T4, used as an indicator of T4 accumulation, was 17.7 when ITC were incubated in Eagles solution. On the other hand, the ratio in the thyroid slice and erythrocytes was 1.1 and 3.0 respectively. By equilibration chamber method, T4 accumulated more in ITC than in erythrocytes. The observed accumulation of T4 in ITC was reversible when re-incubated with normal human serum. Displacement of 125I-T4 by non-labelled T4 was not observed at the range of added T4 from 10 to 1000 ital. Essentially the same result were obtained when the liver, thyroid slice or erythrocytes were studied. Therefore, the number of T4-binding sites appears to be very large. Increased deiodination of 125I-T4 was observed when 125I-T4 was incubated with ITC, whereas conversion of 125I-T4 to 125I-T3 was not remarkable. It is concluded that ITC obviously concentrate T4 by an entirely different mechanism from that in serum TBP.

The Effect of Thiocyanate (SCN-) and Perchlorate (ClO4-) on Free Thyroxine Fraction (FT4F) of Human Serum

It was reported by Yamada that SCNand C10-4 increase FT4F of rat serum, by displacing T4 from TBPA. However, it has not been known whether these anions affect that of human serum. In this study we tried to demonstrate the effect of these anions on FT4F on human serum and to clarify the possible site and mechanism of actions. The measurement of FT4F was carried out by the same method as described by Sterling and Brenner except that diluted serum was used instead of undiluted. Validity of the measurement was established by demonstrating that SCN-, C10-4 and barbital buffer did not affect Mg-T4 precipitation, though twice the volume of 10% MgCl2 was required when barbital buffer was used (Fig 1) These anions elicited an increase of FT4F at the final concentration which ranged from 5 to 20 tcmols/m1 (Fig 2). The effect of SCNwas more pronounced than that of C104-. When the effect was tested on the sera enriched with T4, it was revealed that T4 did not counteract on the effect of these anions (Fig 3). As a trial to clarify the site of the action, the effect of these anions was compared with normal and TBG-deficient serum dialyzed against phosphate or barbital buffer. The elevation of FT4F by these anions was more pronounced on TBG-deficient serum than on normal serum when dialyzed against phosphate buffer. The effect of these anions on both sera was almost nullified when dialyzed against barbital buffer (Fig 4). These results demonstrated for the first time that SCNand C104affect FT4F of human serum. The fact that the effect was not counteracted by T4 makes it unlikely to be due to simple competition of these anions with T4 against its binding sites. The result that these anions had more pronounced effect on TBG-deficient serum would rule out TBG as the site of the action. Finally, from the nullification of the effect of these anions by barbital buffer, one can conclude that the site of the action would be mainly on TBPA. Thus, our results were compatible with the thought that T4 -binding on TBPA may be affected with these anions by their chaotropic actions. (See pp. 16-,-19)