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Biomedical subjects

K Kamikubo

Publications and source records attributed to K Kamikubo.

At least 37 records · Page 2Linked to original sources
PubMed1990

Similar nuclear factors mediate stimulation of rat thyroglobulin gene transcription by thyrotropin and insulin-like growth factor-I.

Transcription of the thyroglobulin (TG) gene in rat thyroid FRTL-5 cells is stimulated by two hormones, TSH and insulin-like growth factor-I (IGF-I). The effect of TSH is mimicked by cAMP. Promoter regions of the rat TG gene responsible for hormonal action as well as the nuclear regulatory proteins that interact with these regions were characterized. Minimal promoter that responds to both hormones has been found to be up to -171 basepairs from the transcription initiation site. In DNase-I footprinting analysis, nuclear extracts from cells treated with either of these hormones protected the same two major regions within the minimal promoter. Mutations in these two regions abolished basal, TSH-stimulated, as well as IGF-I-stimulated expression of the fused reporter gene chloramphenicol acetyltransferase. DNA mobility shift assay revealed that cAMP and IGF-I induce binding of similar nuclear proteins to these promoter regions. These results suggest that rat TG gene transcription is regulated by the convergent action of two distinct signaling pathways, possibly involving similar DNA-binding nuclear proteins and regulatory sequences of the TG gene promoter.

Animals↗
PubMed1989

Thyroid hormone autoantibodies (THAA) in three sisters: a four-year follow up.

We have found three sisters who had thyroid hormone autoantibodies (THAA) in serum. Two of them were hypothyroid due to Hashimoto's thyroiditis. They were treated with synthetic thyroxine (T4) (Case 1) or T4 and triiodothyronine (T3) (Case 2). The other sister (Case 3) was euthyroid throughout the investigation period. Changes in the titers of THAA, antithyroglobulin (Tg) antibodies as well as in the concentrations of thyrotropin (TSH), and total and free thyroid hormones (T3, T4, FT3, and FT4) in sera from each patient were examined for four years. A significant positive correlation was observed between titers of THAA and anti-Tg antibodies in both Case 1 (anti-T3 and anti-T4) and 2 (anti-T4). On the other hand, a significant negative correlation between titers of anti-T3 and anti-Tg antibodies was observed in Case 3. These results suggest that antigen of THAA might be Tg in Case 1 and 2 and mechanism(s) of the production of THAA of Case 1 might be different from that of Case 1 and 2 in terms of their antigen or immune recognition of Tg.

Adolescent↗
PubMed1988

[A case of pseudo-Bartter's syndrome associated with hypokalemic myopathy].

A case of pseudo-Bartter's syndrome associated with hypokalemic myopathy was presented. A 37-year-old housewife was admitted to our hospital because of muscle cramps with muscle weakness and tetany. There was a history of facial edema and constipation, which have been managed with "Kanpo medicine (Chinese medicine)" and laxatives for several years. The patient was amenorrhea 3 months before entry. She began to experience muscle weakness and muscle cramps associated with gait disturbance 2 or 3 months before admission. On physical examination, she was thin with positive Trousseau's and Chvostek's signs. Laboratory studies revealed hypokalemia, low urinary excretion of potassium, hypocalcemia, metabolic alkalosis, elevated creatine phosphokinase (CPK), increased levels of plasma renin activity and plasma aldosterone concentration, and decreased sensitivity to pressor effect of angiotensin II. Potassium supplementation resulted in restoration of her symptoms and normalization of low serum calcium and elevated CPK levels. She was diagnosed to be pseudo-Bartter's syndrome due to anorexia nervosa. The mechanism(s) of hypokalemia in our case was discussed.

Adult↗
PubMed1988

Evidence for disulfide bonds in membrane-bound and solubilized opioid receptors.

The effects of pretreatment with dithiothreitol (DTT) on opioid binding activities of membrane-bound and digitonin-solubilized opioid receptors from bovine adrenal medulla were studied. Pretreatment of membranes with DTT or mercaptoethanol inhibited [3H]diprenorphine binding by reducing the number of binding sites. The inhibitory action of DTT was time and dose dependent. The binding of [3H]D-Ala2-D-Leu5-enkephalin was also inhibited by DTT pretreatment. Pretreatment of digitonin-solubilized binding sites with DTT also reduced the number of [3H]diprenorphine binding sites. The action of DTT was diminished by preincubating the DTT solution with H2O2. [3H]Diprenorphine protected the opioid binding sites from the inhibitory action of DTT. The present results provide evidence that disulfide bonds are implicated in opioid binding activity of the opioid receptor system.

Adrenal Medulla↗
PubMed1987

[Characterization of adrenal medullary opioid receptors. I. Binding of opioids to adrenal medullary opioid receptors].

We studied the binding of [3H]D-Ala2-D-Leu5-enkephalin ([3H]DADLE) and [3H] diprenorphine to crude plasma membrane fraction obtained from the bovine adrenal medulla (bovine adrenal medullary membranes) in order to characterize adrenal medullary opioid receptors. The [3H] diprenorphine binding was the highest in crude plasma membrane-mitochondrial fraction among all subcellular fractions studied. The amount of [3H] diprenorphine bound to bovine adrenal medullary membranes was proportional to the protein concentration. Association kinetics of the [3H] diprenorphine binding to bovine adrenal medullary membranes showed that the maximal binding was achieved following 8 min incubation and that the binding conformed the second-order kinetics. [3H] DADLE and [3H] diprenorphine bound to bovine adrenal medullary membranes with high affinities. The Kd and Bmax for the [3H] DADLE binding were found to be 2.9 nM and 57.5 fmole/mg protein, respectively, while those for the [3H] diprenorphine binding were 0.31 nM and 250 fmole/mg protein, respectively. Displacement studies showed that the [3H] diprenorphine binding was inhibited dose-dependently by levorphanol, dynorphin (1-13), beta-endorphin and DADLE. Levorphanol was at least 1000-fold more potent to inhibit the [3H] diprenorphine binding than dextrorphan, indicating stereospecificity of the [3H] diprenorphine binding. Na+, Li+ and K+ (100 mM) diminished the [3H] DADLE binding and enhanced [3H] diprenorphine binding. Na+ (100 mM) increased the Kd value for the [3H] DADLE binding from 2.9 nM to 14.1 nM. Mn++, Ca++ and Mg++ diminished the [3H] diprenorphine binding. Mn++ (1 mM) increased the Bmax value for the [3H] DADLE binding from 95 fmole/mg protein to 450 fmole/mg protein. These effects of Na+ and Mn++ on the [3H] diprenorphine binding were found to be dose-dependent. [3H] Diprenorphine binding to the digitonin-solubilized opioid receptor was also inhibited dose-dependently by Mn++. These results suggest that bovine adrenal medullary membranes contain high affinity and stereospecific opioid receptors and that the binding of opioids to the bovine adrenal medullary opioid receptors is influenced by cations. Binding study also revealed the presence of opioid receptors in human malignant pheochromocytoma. The Kd and Bmax of the [3H] diprenorphine binding to crude membrane fraction obtained from malignant pheochromocytoma were found to be 0.14 nM and 10.4 fmole/mg protein, respectively.

Adrenal Medulla↗
PubMed1987

[Characterization of adrenal medullary opioid receptors. II. Coupling of adrenal medullary opioid receptors to GTP binding proteins].

We studied possible coupling of opioid receptors to GTP-binding proteins to clarify the mechanism(s) of opioid action in bovine adrenal medullary membranes. Guanylyl imidodiphosphate (Gpp(NH)p) reduced the binding of [3H] D-Ala2-D-Leu5-enkephalin ([3H] DADLE) to bovine adrenal medullary membranes dose-dependently, and enhanced the binding of [3H] diprenorphine to them. Gpp(NH)p (0.1 mM) enhanced the Kd value of the [3H] DADLE binding from 2.9 nM to 3.9 nM, but did not change its Bmax. Pretreatment of bovine adrenal medullary membranes with pertussis toxin (PT) reduced the [3H] DADLE binding. The Gpp(NH)p inhibition for [3H] DADLE binding was diminished by the PT-pretreatment. On the other hand, the [3H] diprenorphine binding to PT-pretreated membranes was higher than that to control membranes. Levorphanol inhibited the adenylate cyclase activity of the rat caudate nucleus crude synaptosomal fraction, but did not change that of bovine adrenal medullary membranes. These results suggest that opioid receptors in bovine adrenal medullary membranes are coupled to PT-sensitive GTP-binding protein which may not influence on adenylate cyclase.

Adenylate Cyclase Toxin↗
PubMed1987

Coupling of adrenal medullary opioid receptors to islet-activating protein-sensitive GTP-binding proteins.

Possible coupling of bovine adrenal medullary opioid receptors to islet-activating protein (IAP, pertussis toxin)-sensitive GTP-binding proteins was investigated by studying effects of guanyl-5'-yl imidodiphosphate (Gpp(NH)p) and IAP treatment of membranes on opioid binding. Gpp(NH)p inhibited [3H]D-Ala2-D-Leu5-enkephalin ([3H]DADLE) binding by increasing the dissociation constant of [3H]DADLE and membranes, and enhanced slightly [3H]diprenorphine binding. IAP treatment of membranes reduced [3H]DADLE binding and abolished almost completely the Gpp(NH)p inhibition of [3H]DADLE binding. Treatment of membranes with IAP and [32P]NAD resulted in radio-labeling of membrane proteins of approximately 39,000 dalton. DADLE inhibited adenylate cyclase activity in rat brain caudate nucleus. However, DADLE, beta-endorphin, levorphanol and dynorphin A(1-13) did not show any significant inhibitory action on bovine adrenal medullary adenylate cyclase activity. These results suggest that bovine adrenal medullary opioid (DADLE) receptors are linked to IAP-sensitive GTP-binding proteins which are not directly coupled to adenylate cyclase.

Adenylate Cyclase Toxin↗
PubMed1987

Solubilization of adrenal medullary opioid receptors.

The opioid-binding activity of digitonin extract of bovine adrenal medullary membranes was studied. [3H]Diprenorphine binding to the solubilized material was rapid and saturable. The dissociation constant of [3H]diprenorphine binding was 0.76 nM. Several opioids displaced the [3H]diprenorphine binding. The complex of [3H]diprenorphine and the solubilized binding sites was eluted as a single peak on a Sepharose 6B column and showed an apparent molecular weight of 200,000. These results indicate that active opioid receptors are solubilized with digitonin from bovine adrenal medullary membranes.

Adrenal Medulla↗
PubMed1987

Phospholipid/Ca2+-dependent protein kinase activity in human parathyroid adenoma.

We have examined the activities of phospholipid/Ca2+-dependent and cyclic AMP-dependent protein kinases of the parathyroid adenomas and the atrophic glands which were resected from three patients with primary hyperparathyroidism. Phospholipid/Ca2+-dependent protein kinase activity of atrophic parathyroid gland was exclusively present in cytosol fraction (90.7 +/- 12.3%). On the other hand, phospholipid/Ca2+-dependent protein kinase activity of parathyroid adenomas was 66.9 +/- 6.4% in cytosol and 33.1 +/- 6.4% in membrane fraction, suggesting a translocation of the enzyme from the cytosol to the membranes. Cyclic AMP-dependent protein kinase activity appeared to be higher in parathyroid adenoma than in atrophic parathyroid gland in both cytosol and membrane fractions.

Adenoma↗
PubMed1986

Opioid and non-opioid binding of beta-endorphin to bovine adrenal medullary membranes.

Binding of human beta-endorphin (beta h-EP) to bovine adrenal medullary membranes was characterized using [125I]Tyr27-beta h-EP [( 125I]beta h-EP) as a primary ligand. The specific binding of [125I]beta h-EP was time-dependent, saturable and stereospecific. Analysis of a saturation isotherm revealed two apparent classes of specific binding sites with dissociation constants of 2.4 and 34 nM. The extent of maximum inhibition of specific [125I]beta h-EP binding by either levorphanol, morphine, naloxone, dynorphin A (1-13) or D-Ala2-D-Leu5-enkephalin was similar to each other and remained partial (60-70%). Levorphanol eliminated the high affinity component but showed no effect on the low affinity component of [125I]beta h-EP binding. beta h-EP(1-31) displaced completely the [125I]beta h-EP binding. However, beta h-EP(1-23) only partially (approximately 80%) inhibited the [125I]beta h-EP binding. beta h-EP(6-31) showed inhibitory activity on [125I]beta h-EP binding. These results suggest that [125I]beta h-EP binding to bovine adrenal medullary membranes consists of a high affinity opioid-sensitive component and a low affinity non-opioid component. The non-opioid component of [125I]beta h-EP binding may be related to COOH-terminal of the beta h-EP molecule.

Adrenal Medulla↗
PubMed1986

Microcomputer-based nonlinear regression analysis of ligand-binding data: application of Akaike's information criterion.

Akaike's information criterion (AIC) (Akaike, H., IEEE Trans. Automat. Contr. AC-19, 716-723 (1974)) was applied to estimate statistically the number of classes of binding sites from ligand-binding data. Several sets of data were analyzed by both the AIC method and the F-test method. Good agreement was obtained between results from both methods. The present results suggest that the AIC method can be a good alternative to the F-test to estimate the number of classes of sites.

Animals↗
PubMed1986

An improved and simplified method for the detection of thyroid hormone autoantibodies (THAA) in serum.

We have developed and evaluated a new and simplified method for the detection of thyroid hormone autoantibodies (THAA) in serum. The method includes acidification of serum followed by adsorption of liberated thyroid hormones onto dextran-coated charcoal and then alkalinisation of the serum in assay buffer prior to performing a binding study. Using our method, specific binding of 125I-T4 to serum THAA in two patients with Hashimoto's thyroiditis was almost the same regardless of whether or not the sera had been preincubated with a large amount of cold T4. On the other hand, without the acid treatment, preincubation with cold T4 considerably inhibited the binding of 125I-T4 to serum THAA in both cases. These results indicate that serum THAA can be easily detected under conditions in which circulating thyroid hormones hardly affect the binding study by using our new sensitive method.

Autoantibodies↗
PubMed1986

Thyroid hormone autoantibodies (THAA) in two cases of Graves' disease: effects of antithyroid drugs, prednisolone, and subtotal thyroidectomy.

Changes in titers of serum thyroid hormone autoantibodies (THAA) and anti-thyroglobulin (Tg) antibodies during treatment with antithyroid drugs (methimazole and propylthiouracil) were examined in two cases of Graves' disease. Effects of prednisolone and subtotal thyroidectomy were also investigated in one case (case 1). Initially both cases had only anti-T4 autoantibodies in their serum. During methimazole therapy, the titer of anti-T4 autoantibodies increased in both cases, and anti-T3 autoantibodies became detectable and their titer increased in case 2. The influence of propylthiouracil on the titer of THAA was not clear. Both prednisolone plus methimazole therapy and subtotal thyroidectomy decreased the level of anti-T4 autoantibodies in case 1. There was a significant correlation between titers of THAA and anti-Tg antibodies in both cases, although titers of anti-Tg antibodies in case 1 stayed within the normal range throughout the investigation period. These results indicate that methimazole treatment could induce and/or enhance the production of THAA and THAA are antibodies against thyroid hormone-containing Tg molecule.

Autoantibodies↗
PubMed1986

A case of total thyroxine-binding globulin deficiency with Graves' disease: fluctuations of plasma triiodothyronine/thyroxine ratio.

A 37-year-old male with total thyroxine-binding globulin (TBG) deficiency associated with Graves' disease is described. Both TBG immunoreactivity and TBG capacity were not detectable in his serum. Serum concentrations of thyroxine-binding prealbumin and albumin were normal. He was initially hyperthyroid. During methimazole-treatment he was maintained in an euthyroid state except for two short hypothyroid periods. His plasma triiodothyronine/thyroxine (T3/T4) ratios during both the untreated hyperthyroid and the methimazole-induced hypothyroid states were higher than those during his methimazole-induced euthyroid state. These findings on changes in his T3/T4 ratio accompanying thyroidal dysfunction were qualitatively comparable with those in patients with Graves' disease with normal TBG levels: that both untreated hyperthyroid and methimazole-induced hypothyroid patients showed higher T3/T4 ratios than methimazole-induced euthyroid patients. These results may provide indirect evidence that changes in hormonal secretion and conversion that raise T3/T4 ratio can occur in thyroidal dysfunctions even in the complete absence of TBG.

Adult↗
PubMed1986

Adrenal medullary opioid receptors are linked to GTP-binding proteins, pertussis toxin substrates.

Effects of Gpp(NH)p and pretreatment of membranes with pertussis toxin (PT) were studied on opioid binding to bovine adrenal medullary opioid receptors. Gpp(NH)p inhibited [3H]DADLE binding by increasing the dissociation constant. PT treatment reduced [3H]DADLE binding and almost abolished the Gpp(NH)p inhibition of [3H]DADLE binding. Levorphanol did not show any significant effect on bovine adrenal medullary adenylate cyclase activity. These results suggest that bovine adrenal medullary opioid receptors are linked to PT-sensitive GTP-binding proteins which are not directly coupled to adenylate cyclase.

Adenylate Cyclase Toxin↗
PubMed1986

Varying expression of opioid receptors and GTP-binding proteins in human pheochromocytomas.

The expression of opioid receptors and GTP-binding proteins was studied in 14 pheochromocytomas. The amounts of [3H]diprenorphine bound to membranes varied from 13 to 62 fmole/mg protein, but significantly higher in adrenaline-secreting tumors than in noradrenaline-secreting tumors. None of [3H]DADLE, [125I]beta-endorphin or [3H]ethylketocyclazocine binding was correlated with [3H]diprenorphine binding. Gpp(NH)p inhibition of [3H]DADLE binding was evident in all four normal human adrenal medullae but in only 8 out of 14 pheochromocytomas. The extent of Gpp(NH)p inhibition was not correlated with the amount of pertussis toxin (PT)-sensitive GTP-binding proteins as measured by PT-catalyzed [32P]ADP-ribosylation. The present findings suggest that opioid receptors and PT-sensitive GTP-binding proteins are variously expressed in transformed chromaffin cells, pheochromocytoma.

Adrenal Gland Neoplasms↗
PubMed1985

A case of Graves' disease with anti-triiodothyronine antibodies.

A case of Graves' disease with high serum thyroxine (T4) and low triiodothyronine (T3) levels which was therefore initially diagnosed as a T4-thyrotoxicosis is reported. Examination of the serum from the patient showed the presence of unusual protein which bound T3. It was later confirmed as IgG class anti-T3 antibodies. In addition to treatment with methylmercaptoimidazole (MMI), the patient was treated with prednisolone for 30 days (total amount 500 mg). Titers of anti-T3 antibodies in the sera were unchanged before and after prednisolone treatment. Our present case indicates that it is clinically important to bear the presence of autoantibodies in mind to account for a possible error in measuring T3 and T4 by radioimmunoassay (RIA). In the case that RIA determination gives an unexpectedly high or low T3 and/or T4 value, the presence of autoantibodies to them should be considered and a test for them is recommended.

Antibodies, Anti-Idiotypic↗