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Biomedical subjects

T Suda

Publications and source records attributed to T Suda.

At least 1,009 records · Page 56Linked to original sources
PubMed1975

Effects of parathyroid hormone on the accumulation of cyclic AMP in bone of vitamin D-deficient rats.

The mechanism of skeletal refractoriness to parathyroid hormone (PTH) in vitamine D-deficient animals was studied in terms of the adenylate cyclase-cyclic AMP system in rat calvaria. In vitamin D-deficient, thyroparathyroidectomized rats, plasma calcium concentration was not elevated by iv administration of PTH, while responsiveness to the hormone was recovered within 24 h after a single dose (2.5 mug) of vitamin D3. In spite of the remarkable dependency of PTH on vitamin D for mobilization of calcium from bone, PTH stimulated adenylate cyclase activity in particulate bone cell fractions in vitro. PTH also enhanced the levels of cyclic AMP in the skeletal tissues of vitamin D-deficient rats in vivo and in vitro to an extent similar to those found in rats given 2.5 mug of D3. Administration of theophylline or dibutyryl cyclic AMP to the vitamin D-deficient rats did not cause any significant hypercalcemic effects, while these drugs enhanced plasma calcium concentration significantly in the rats given vitamin D3. These data strongly indicate that the cause of the skeletal refractoriness to PTH in vitamin D-deficient animals is not a defective activation of adenylate cyclase, but must be related to a later step or steps in the biochemical events leading to bone cell activation.

Adenylyl Cyclases↗
PubMed1975

Hypothalamic-pituitary functions in patients with idiopathic pituitary dwarfism.

To investigate hypothalamic-pituitary functions and the primary site of the lesion in idiopathic pituitary dwarfism, various pituitary function tests, especially the pituitary hormone responses to the hypophysiotropic hormones were studied in 23 patients with idiopathic pituitary dwarfism. A few cases showed slight responses of GH to GH stimulation tests. Gonadotropin deficiencies were most frequently noted among pituitary hormones. The basal levels and the responses of plasma LH and FSH to LH-RH test were diminished markedly in all of the cases except in 5 cases with isolated GH deficiency. Responses of LH and FSH to LH-RH improved markedly after a long term administration of LH-RH for a period of one month in 2 patients with gonadotropin deficiency. As to TSH axis, half of the cases accompanied hypothyroidism. However, the responses of TSH to TRH were normal in all of the cases regardless of the thyroid function. The basal levels and the responses of plasma cortisol and 11-deoxycortisol to the rapid metopirone test were also impaired in about half of the cases. Basal levels of plasma prolactin were normal in all of the cases and the responses of prolactin to TRH were normal in cases with normal thyroid function, but slightly delayed in cases with hypothyroidism. It is concluded from the above observations that the incidences of various pituitary hormone deficiencies were quite high in this disorder and hypophysiotropic hormone deficiencies may cause pituitary hormone deficiencies. Therefore, it is suggested that the primary site of the lesion in this disorder might be at the hypothalamus.

Adolescent↗