The authors' observations about the use in the clinical practice of the most important biochemical tests of functional investigation of the parathyroid gland are reported here. In diagnosing hypoparathyroidism, the utility of the parathyroid stimulation test through sodium versenate and through phosphorus over load, and of the parathyroid inhibition test through calcium overload, is indicated. In diagnosing hyperparathyroidism, the stimulation test through versenate and the inhibition test through a low-phosphorus diet are recommended as well. It is excluded, up to this time, that the investigation with radioactive isotopes of the calcium turnover may be of any practical use in diagnosing parathyroid disorders.

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A new procedure for estimating thyroxine secretion rate by checking the changes in the level of alkaline phopshatase in the chicken serum is described, and is compared with the goiter prevention technique. Five and 9-week-old cockerels and pullets were used, divided into several groups. All of the birds except the last group, received 0.1% thiouracil in diet and the graded dose of L-thyroxine for 10 days. The group average of thyroxine secretion rate was estimated by solving the regression equation between the percentage of the finalvalue to theinitial value of alkaline phosphatase unit (Y) and thyroxine dose (X), giving the initial percentage of the enzyme of non-thiouracil-treated control group to Y.
The estimates of thyroxine secretion rate obtained by the new method roughly correlated to those derived from the goiter prevention assay.

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C¹⁴-incorporation into blood glucose and liver glycogen from C¹⁴-labelled alanine was studied in rats with acute or chronic CCl₄ liver damage.
In rats with CCl₄ liver damage, C¹⁴-incorporation from alanine into blood glucose and liver glycogen was found to be decreased, especially in rats with acute CCl₄ liver damage. Such a disturbed C¹⁴-incorporation was improved by the administration of 2.5mg of cortisone to rats with chronic CCl₄ poisoning. However, in rats with acute CCl₄ liver damage, cortisone treatment caused a marked increase in C¹⁴-incorporation into blood glucose and failed to increase C¹⁴-incorporation into liver glycogen.
The latter finding may be related to the increased incidence of steroid diabetes in patients with liver damage.

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An increase in body weight took place in hypophysectomized immature rats in parabiosis with actively growing rats of the same age with their hypophysis intact. In contract, hypophysectomized rats failed to grow after union with slowly growing older parabionts. It appears likely that in unions of immature rats growth hormone actively secreted by the hypophysis of one member is transferred to its hypophysectomized partner to stimulate its growth. The average per cent increase in body weight in immature hypophysectomized rats during a period of 28 to 30 days was 116.4%, while that of their partners with hypophysis intact was 134.4%, the ratio of the two values being almost constant in different pairs (0.881±0.018, on the average), regardless of the age at union, the strain and sex of parabionts, and various treatments given to the animals. The growth of immature rats with hypophysectomized parabionts was retarded as compared with that of single intact rats as well as those with partners having hypophysis intact. These findings were discussed in relation to the regulatory mechanism of growth hormone secretion.

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I¹³¹-TSH was made by the reaction of elemental iodine (I₂¹²⁷) and TSH preparation (Pretiron) containing 5.15% tyrosine, using radioiodine I¹³¹ as a tracer. In 1 JS of TSH preparation the amount of tyrosine was 1.83γ and 1 JS of TSH was saturated with about 2.5γ of iodine and then its activity was lost completely with iodination, but it was possible to made variously active TSH by various iodination. Tyrosine residue was changed to DIT and/or MIT in the case of iodination of TSH. Therefore, it was ascertained that tyrosine residue mainly participated in this iodination and absolutely necessary residue for the activity of TSH was tyrosine. So we can calculate the amounts of the iodine bound. TSH. If the molecular weight of TSH is 25, 000 as reported by Bates and Condriffe (1960), 1 JS of TSH would be saturated and inactivated with 0.2γ of iodine.
It is pressumed that the action of Lugol's solution in Grave's disease is the inactivation of TSH by the formation of iodinated TSH in the thyroid gland before the appearance of TSH effect. The addition of Mercazole mainly inhibits the iodination of TSH by the reduction of elemental iodine, and free I¹³¹ is not removed from I¹³¹-TSH by the treatment with Mercazole.

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The role of the mechanism of the hypothalamus in the regulation of the reproductive function in rats has been investigated from the view point of the monoamine oxidase activity in the brain. Coincidentally with the estrous cycle, the enzyme activity in the hypothalamus, especially in its posterior part, showed cyclic fluctuation. Cyclic changes in the hypothalamus were characterized by the proestrous elevation in monoamine oxidase activity and the proestrous and estrous depression in choline acetylase activity. Following castration, the monoamine oxidase activity in the hypothalami of female rats showed a temporary decrease in the anterior part at the earlier stages after castration and, thereafter, a marked increase in both the anterior and posterior parts. The reciprocal relationship of the enzyme activities between monoamine oxidase and choline acetylase was also observed in the hypothalamus after castration. These data support the concept that acetylcholine and catecholamine or serotonin metabolism in the hypothalamus play an important role in the neural control of ovulation.

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Biochemical analysis of intracellular water, sodium, potassium and nitrogen in biopsied muscle was attempted in 24 thyrotoxic myopathy, in 10 thyrotoxic periodic paralysis and in 19 control subjects. Water and electrolytes studies were done by chloride assumption.
1. Serum electrolytes in all groups remained in normal range except remarkable fall of potassium during paralytic attack of thyrotoxic periodic paralysis.
2. In thyrotoxic myophathy, total and intracellular water in solid tissue basis decreased by 11.6% and 12.9% respectively, through no significant alteration was observed in thyrotoxic periodic paralysis during either paralytic or non-paralytic state.
3. Intracellular sodium content and concentration in muscle specimen increased in thyrotoxicosis and in thyrotoxic periodic paralysis during non-paralytic state. Intracellular potassium, in reverse, decreased significantly in either thyro toxicosis or during paralytic attack of thyrotoxic periodic paralysis. However in non-paralytic state intracellular potassium concentration did not differ significantly from control subjects.
4. Since decrease of total nitrogen in biopsied specimen (10.4%) limited by half of the decrease of intracellular potassium (20.8%), this potassium depletion was not the result by muscle destruction.
5. Linear correlation between grip strength and intracellular potassium concentration of biopsied muscle was proved in thyrotoxic myopathy.

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