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Biomedical subjects

Y Shishiba

Publications and source records attributed to Y Shishiba.

At least 91 records · Page 5Linked to original sources
PubMed1983

The presence of myoglobin in human thyroid tissue.

In the present study we sought to determine the presence of myoglobin in human thyroid tissue. When reacted with antihuman myoglobin antibody on the Ouchterlony plate, homogenates of human thyroid tissue formed a precipitation line. When the human thyroid extract was included in human myoglobin RIA, the dilution curve of thyroid extract was parallel to the standard curve of myoglobin. When the myoglobin immunoreactivity in thyroid extract was fractionated with Sephadex G 75 column, the immunoreactivity was eluted in a peak identical with authentic myoglobin. The position of the peak was different from that of thyroglobulin. Myoglobin concentration in thyroid tissue was estimated to be 0.7-110 mg/g wet wt, being about 1/6000 to 1/40 of that in skeletal muscle. Histochemical studies demonstrated the presence of myoglobin immunoreactivity in thyroid tissue, especially in the apical border of thyroid epithelial cells, implying a functional role in iodinating process or exocytotic-endocytotic process.

Adolescent↗
PubMed1983

The suppression of TSH in the presence of the normal PRL responses to TRH out of 26 patients with primary hyperparathyroidism.

The responses of TSH and PRL to intravenous doses of 500 micrograms of TRH were investigated in 26 patients with primary hyperparathyroidism. Fourteen patients (54%) showed low responses of TSH with peak values of less than 5 microU/ml (Group A). Twelve patients showed normal responses of TSH to TRH (Group B). Among the 26, 12 cases belonging to Group A and eight in Group B were reexamined after the correction of serum calcium level by parathyroidectomy. After successful treatment, the responses of TSH to TRH in six of the 12 patients in Group A returned to normal, whereas those in the remaining six were unchanged. The responses in the eight patients in Group B after surgery were not changed when compared to those before treatment. The basal values of PRL and the responses of PRL to TRH were normal in all patients and did not change after treatment. We showed that patients with primary hyperparathyroidism have a high incidence (54%) of suppressed TSH response to TRH. Hypercalcemia was obviously one of the causative factors in inducing this abnormality in six patients. However, persistently suppressed responses of TSH to TRH were observed in the other six patients in Group A even after the correction of the serum calcium level by surgery. This finding suggests a primary failure of the TSH-regulatory mechanism in some cases of primary hyperparathyroidism.

Adult↗
PubMed1983

Erythrocyte ouabain binding capacity as a possible cellular index of hyperthyroid status.

The maximum ouabain binding capacity in erythrocytes from 8 normal subjects and 14 patients with hyperthyroidism was assessed by measuring [3H]-ouabain binding. The mean value for maximum ouabain binding capacity was significantly lower in the patients than in normals (0.422 +/- 0.084 vs 0.671 +/- 0.095 pmol per 10(9) cells, p less than 0.001). Furthermore, a close inverse correlation was found between the ouabain binding capacity and serum T3 (r = 0.766; p less than 0.01) or T4 (r = -0.870; p less than 0.001) levels. These results suggest that the maximum ouabain binding capacity in erythrocytes may provide a useful index of the peripheral effect of thyroid hormone.

Adult↗
PubMed1983

Presence of heparan sulfate proteoglycan in thyroid tissue.

Glycosaminoglycan (GAG) was extracted from the porcine thyroid gland with a buffer containing 5.3 M guanidine-HCl and proteolytic enzyme inhibitors and was fractionated by subsequent isodensity CsCl centrifugation. 60% of uronic acid positive materials was accumulated in the bottom one-fourth fraction with high buoyant density. More than 90% of this uronic acid positive material in the thyroid tissue was heparin or heparan sulfate (sensitive to nitrous acid treatment) and the rest was chondroitin sulfate or dermatan sulfate (sensitive to chondroitinase ABC treatment). When the accumulated high buoyant density GAG was analyzed on a Sepharose CL-6-B column, approximately 14% of the heparin sulfate were in the macromolecular portion as a form of proteoglycan because it was destroyed by the papain digestion or alkaline borohydride treatment which extensively digests protein or releases GAG from protein by the elimination reaction, respectively. This study demonstrates the existence of heparin sulfate proteoglycan in thyroid tissue for the first time.

Animals↗
PubMed1983

Rapid improvement of thyroid function by using glucocorticoid indicated for the preoperative preparation of subtotal thyroidectomy in Graves' disease.

Glucocorticoid therapy is not considered as an authentic method for obtaining euthyroid in Graves' disease. We tried the administration of prednisolone as a preoperative preparation for subtotal thyroidectomy in 4 hyperthyroid patients with Graves' disease who had suffered adverse effects of thionamide antithyroid drugs, including agranulocytosis, liver damage and skin eruptions. Following oral administration of a 30 mg daily dose of prednisolone, with or without other antithyroid reagents, both serum T4 and T3 concentrations decreased rapidly and reached the normal range within 2 weeks. The clinical signs and symptoms of hyperthyroidism also improved rapidly and subtotal thyroidectomies were performed uneventfully in all cases. These results suggest that 1) glucocorticoid medication can normalize the circulating hormone levels rapidly in Graves' disease, 2) it is a useful method as preoperative preparation for subtotal thyroidectomy, especially when other conventional methods are not available or effective in obtaining euthyroid, and 3) mechanisms other than thyroid stimulation by circulating immunoglobulin seem to play an important role in causing hyperfunction of the gland.

Adult↗
PubMed1983

An inter- and intralaboratory quality-control survey of radioimmunoassay of insulin, thyroxin, thyrotropin, cortisol, digoxin, gastrin, beta 2-microglobulin, and IgE in Japan with commercially available kits.

We report results of a quality-control survey of radioimmunoassay (RIA) of eight analytes, participated in by 249 laboratories of various types throughout Japan. For the purpose of the external control survey, lyophilized specimens containing two different concentrations of each analyte were sent to the participating laboratories, which supplied both their assay values and their raw data for the standard curves and for the samples. The individual data for the standard curve were analyzed by the RIA data-processing program described by Faden and Rodbard. The precision profile obtained for the individual assay was used as the estimate of the quality of each assay. Although there was a wide scatter in assay values, the quality of the assay by the individual laboratories was not the major contributor to this scattering, because the values they reported for the assays and precision profiles of the standard curves were almost identical with those obtained from the kit manufacturers. When the reported assay values were analyzed according to the brand of kits, by analysis of variance, the treatment mean square due to difference in the make of the kits significantly exceeded the error mean square due to "within-kit" variation in the assay of insulin, thyroxin, thyrotropin, cortisol, gastrin, and digoxin. The CVs for "between-kit," "within-kit," "between-assay" and "within-assay" variations (the latter two aspects were studied in a representative laboratory, for convenience of comparison) were about 20, 15, 13, and 7%, respectively. Because the observed within-kit variation is of almost the same magnitude as that expected from the combination of within-assay and between-assay variation, the skill of the users probably was equal and the accuracy and precision of the kits probably had the greatest impact on assay variation. This survey also emphasizes the criteria for commercially available RIA kits.

Analysis of Variance↗
PubMed1982

[The relationship between the number of anti-thyroglobulin antibody forming cells from the cultured peripheral lymphocytes and the serum antibody titers in patients with chronic thyroiditis (author's transl)].

Anti-thyroglobulin antibody forming cells (AFC) were generated from the cultured peripheral lymphocytes of patients with chronic thyroiditis. In order to clarify whether this reflects the antibody formation in vivo, the number of antibody forming cells generated in the culture was related to the serum antibody titer in 121 cases. There was no case which produced more than 10 AFC from 2 x 10(5) B-cells in the group with the low serum antibody titer (less than 10(2)), while 29.4% produced more than 10 AFC in the patients with antibody titer of 20(2) and 20(4) and 65.2% in the group with titer of 80(2) approximately 640(2). The average number of AFC of the last group was 31.4 +/- 17.7 (SD). AFC and serum antibody titers were estimated on various occasions with the same patients. A good relationship was observed between these two parameters. There was no significant correlation between the numbers of AFC and serum antimicrosome antibody titers.

Adolescent↗
PubMed1982

The effects of sulphydryl reagents on the neutralization of LATS by human thyroid extracts.

LATS has already been shown to be neutralized by an unknown antigenic substance in human thyroid tissue. This antigen has been presumed to be a TSH receptor. To examine this hypothesis, we sought to determine whether SH reagents capable of altering the characteristics of TSH receptors in thyroidal crude membrane fractions caused an alteration in the LATS neutralization activity of the same fraction. Diamide (10(-3) M) which was shown to enhance 125I-TSH binding to TSH receptors by increasing the binding affinity of the receptor, significantly increased the neutralization of LATS by the crude membrane fraction. Dithiothreitol (10(-3) M) which was shown to inhibit 125I-TSH binding by decreasing the affinity of the receptor, significantly decreased the neutralization of LATS by the fraction. This indicates that TSH receptors and the thyroidal factor capable of neutralizing LATS share a common property in terms of the effects of SH reagents and is compatible with the idea that the lats neutralizing activity of thyroidal crude membrane fraction is due to binding by the TSH receptor or its fragments.

Animals↗
PubMed1982

Effect of sulfhydryl reagents on the conversion of thyroxine to 3,5,3'-triiodothyronine: direct action on thyroxine molecules.

Sulfhydryl reagents are good stimulators of the enzymatic conversion of T4 to T3. Previous studies have suggested that the underlying mechanism for this property is that these reagents may serve as a cofactor in the reaction, or they maintain the enzyme in its active reduced form. We examined another possibility, namely that sulfhydryl reagents affect T4 itself and hence increase T3 generation by the enzyme. The substrate T4 and sulfhydryl reagents dithiothreitol, mercaptoethanol, and reduced glutathione were incubated at 37 C for 1 h and then combined with rat liver homogenate and incubated for additional 15 min to permit the enzymatic formation of T3. For control, substrate T4 was not preincubated with reagents, and those reagents were added just before the incubation. Preincubation of T4 with these reagents markedly enhanced subsequent T3 generation by the homogenate. Without preincubation, however, reduced glutathione and mercaptoethanol did not enhance T3 generation by simultaneous incubation with the homogenate. Dithiothreitol increased T3 generation when introduced into the incubation medium simultaneously with the homogenate and incubated only 15 min. However, the magnitude of stimulation was far less than that obtained from T4 preincubated with this reagent. These procedures did not alter the nonenzymatic generation of T3 significantly. These results suggest that sulfhydryl reagents can affect T4 itself and make it more susceptible to enzymatic outer ring monodeiodination.

Animals↗
PubMed1982

Discrepancy between thyroid-stimulating and thyrotropin-binding inhibitory activities of Graves' immunoglobulin Gs assessed in the mouse.

TSH receptor binding-inhibiting (TBI) and thyroid-stimulating (TSI) activities of Graves' immunoglobulin Gs (IgGs) were measured using the murine TSH receptor (mTBI) and the McKenzie LATS bioassay. In contrast to the expectation that only the IgGs positive for LATS showed mTBI activity, mTBI activity was closely correlated with TBI activity measured at the human TSH receptor regardless of LATS potency (r = 0.79; P less than 0.01), indicating a lack of species specificity of IgG in this particular aspect. In 7 to 15 IgGs positive for both mTBI and LATS, there was a significant correlation between the 2 parameters (r = -0.89; P less than 0.01). However, 4 IgGs among the 15 were positive for mTBI but negative for LATS even when tested at 3- to 7-fold concentrations of IgG.

Animals↗
PubMed1982

The effect of S-adenosyl methionine on the TSH receptor function in human thyroid tissue: increase in binding of TSH and decrease in adenylate cyclase coupling.

To determine the effects of S-Adenosyl methionine (AdoMet) on TSH receptor function and adenylate cyclase coupling, human thyroidal crude membrane fraction was pretreated with AdoMet and with S-Adenosyl homocysteine (AdoHcy), separately or in combination. 125I-TSH binding to the pretreated membrane and adenylate cyclase activity of the membrane were examined. In contrast to the reported effect of AdoMet on the decrease in GH binding to lactogenic receptor, AdoMet 0.5 mumoles/ml significantly increased the binding of TSH to the receptor by increasing the affinity of the binding, whereas it decreased the coupling of adenylate cyclase significantly. The effect of AdoMet was partially counteracted by the pretreatment of the membrane with AdoHcy. This effect of AdoMet is very similar to that of diamide previously reported. The result implies that the effect is due to an alteration in the tertiary structure of receptor protein triggered by methylation.

Adenylyl Cyclases↗