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Biomedical subjects

H Uchimura

Publications and source records attributed to H Uchimura.

At least 145 records · Page 8Linked to original sources
PubMed1978

Interactions of bovine thyrotropin and human chorionic gonadotropin with adenylate cyclase in bovine thyroid membranes.

Previous studies have shown that crude preparations of human chorionic gonadotropin bind to bovine thyroid membranes, displace 125I-labeled bovine thyrotropin therefrom, and are weak agonists therein with respect to the activation of adenylate cyclase. The present studies reveal that concentrations of chorionic gonadotropin sufficient to elicit a maximal agonistic response of adenylate cyclase are strongly antagonistic to the stimulatory action of bovine thyrotropin in the thyroid membrane system. This effect is reminiscent of the inhibitory effects of crude human chorionic gonadotropin on other extragonadal tissues in vitro, and, like them, appears to be mediated by some factor(s) other than human chorionic gonadotropin itself, since highly purified human chorionic gonadotropin was without effect.

Adenylyl Cyclases↗
PubMed1977

Iodinating activity of thyroid tissue in toxic diffuse goiter.

Thyroid tissue obtained from 12 patients with Graves' disease and treated with thionamide drugs for 3-7 mo before subtotal thyroidectomy, from 12 patients with Graves' disease, similarly treated, and given 50 mug of triiodothyronine (T3) for 10 days before surgery, and from 12 euthyroid patients with solitary cold nodules was investigated to compare in vitro iodination of thyroglobulin in toxic diffuse goiter and in normal thyroid tissue. The supernates of the homogenates (105,000g) were subjected to sucrose density gradient centrifugation (5--28%) to separate the thyroglobulin fraction. The precipitates were treated with 1% digitonin and centrifuged to collect the supernate (particulate fraction). When thyroglobulin and particulate fractions obtained from the same patient were incubated with 125I-, iodide, glucose, and glucose oxidase, the amount of iodine bound to thyroglobulin was several times greater in toxic diffuse goiter than in normal thyroid tissue; administration of T3 did not affect iodination in toxic diffuse goiter. When the thyroglobulin fraction from each patient was incubated with a standardized quantity of peroxidase instead of the individual particulate fraction, the amount of iodine bound to thyroglobulin was the same among the three groups of patients. Finally, when bovine serum albumin was substituted for thyroglobulin from each of the patients, iodination of bovine serum albumin was several times greater with the particulate fraction obtained from toxic diffuse goiter tissue than with that obtained from normal tissue. The guaiacol-oxidizing activity oty. These results suggest that in vitro iodination of thyroglobulin is increased in toxic diffuse goiter even when patients are made euthyroid by treatment with thionamide drugs as well as when they are given additional T3 for 10 days before operation. The increase in iodination of thyroglobulin appears to be due to an increase in peroxidase activity in the particulate fraction.

Adult↗
PubMed1976

Induction of cholinergic enzymes in chick ciliary ganglion and iris muscle cells during synapse formation.

1. In chick ciliary ganglia and irises, cholineacetyltransferase (ChAc) and acetylcholinesterase (AChE) activities were measured from the fifth day of incubation until 1 week after hatching. The changes in enzyme activity were correlated in time with previous electrophysiological and morphological findings of synapse formation in these tissues. 2. At Stage 26 (Hamburger & Hamilton, 1951; before synapse formation in the ganglia) low activities of ChAc (12 +/- 4 [mean +/- S.E.] p-mole of ACh synthesized/hr) were measured in the iris nerve terminals, indicating that ganglion cells are biochemically differentiated, immediately after cell migration is completed. The specific acitivities of ChAc and AChE rose during development and these increases were closely related to the onset and maturation of ganglionic and iris synaptic transmission. These increases in enzyme activities can be used in cholinergic synapses as an index of synapse formation. 3. The 200-fold specific increase of ChAc in iris nerve terminals which occurs at Stage 34 probably reflects an increase in synthesis of the enzyme in ganglion cells and suggests that the formation of the iris neuromuscular junction triggers the enzyme induction. It is implied that the cell responds to a signal ascending the axon from the terminal. 4. The initial increase of AChE specific activity in the ganglion occurs after transmission is established in all cells between Stage 30 and 34 and is mainly due to enzyme synthesis by the ganglion cells. In the iris there is a twofold increase in specific activity after the formation of neuromuscular junctions which probably reflects enzyme induction in the muscle subneural region. It is concluded that the specific induction of AChE in post-junctional cells is due to an influence of the prejunctional element. 5. During synaptic formation in the ciliary ganglion, reciprocal interactions between the neurones and their targets result in the induction of ChAc in the prejunctional elements and AChE in the post-junctional cells.

Acetylcholinesterase↗
PubMed1976

Measurements of free thyroxine: comparison of per cent of free thyroxine in diluted and undiluted sera.

The effect of dilution on values of the per cent of free T4 in serum (%FT4) measured by equilibrium dialysis, was determined by comparing the values for %FT4 in diluted and undiluted specimens. The specimens studied were sera obtained from 10 normal subjects, 10 patients with hyperthyroidism, 5 with hypothyroidism, and 9 women with normal pregnancy. The method of analysis employed was that described by Sterling and Brenner, except that the 125I-thyroxine used was predialyzed to remove non-thyroxine contaminants and that "corrected" values for %FT4 were calculated by dividing measured values by the numerical extent to which the serum had been diluted.

Female↗