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Biomedical subjects

M Azukizawa

Publications and source records attributed to M Azukizawa.

At least 19 recordsLinked to original sources
PubMed1979

Kinetic aspects of the antigen-antibody reaction in various radioimmunoassays: effect of delayed addition of labeled or unlabeled antigens on sensitivity of assay.

The kinetics of the antigen-antibody reaction were examined systematically in four kinds of double-antibody radioimmunoassay (RIA). In all the RIAs, the dose-response curves obtained on delayed addition by 24 to 48 h of labeled antigens (curves B), were shifted downwards and to the left of those obtained on simultaneous addition of the reagents (curves A), resulting in improved sensitivity of the assay. On the contrary, the dose-response curves obtained on delayed addition of unlabeled antigens (curves C), were shifted upwards and to the right of curves A, resulting in reduced sensitivity. In human thyrotropin (hTSH) RIA, curves B and C approached curves A very little, even after 168 h of incubation. A similar phenomenon was observed with anti-hTSH antisera from five different sources at two incubation temperatures, and the dilution curves of 125I-labeled hTSH and unlabeled hTSH appeared to be parallel. Therefore, the phenomenon observed with hTSH RIA could not be attributed to the assay conditions or to peculiar properties of the reagents used. In insulin RIA, the reversibilities of the shifts of curves B and C were slight but comparable to those observed in hTSH RIA. In 1-3,5,3'-triiodothyronine RIA, curves B and C gradually approached curves A on prolonged incubation and curves B became nearly identical with curves A after 98 h of incubation. On the other hand, in alpha-fetoprotein (AFP) RIA, curves B and C did not approach curves A, even on prolonged incubation for up to 288 h. The "equilibrium affinity constants" of the antibodies were of the same order of magnitude, thus it is unlikely that differences in the constants can account for the differences in the reversibility of these RIAs. In APF RIA, a significant amount of the antigen-antibody complex was precipitated without second antibody after centrifugation at 3000 X g. These findings suggest that the extent of dissociation of the immune complexes depends on their size, which in turn is related to the molecular weight of the antigen.

Antigen-Antibody Reactions↗
PubMed1979

Radioimmunoassay for human pancreatic amylase: comparison of human serum amylase by measurement of enzymatic activity and by radioimmunoassay.

A radioimmunoassay (RIA) for human pancreatic amylase has been developed for the determination of human serum amylase content. The assay was shown to be sensitive (7 ng/ml), reproducible and specific, but human pancreatic amylase and salivary amylase could not be distinguished by the antiserum used. In normal subjects, the mean concentration of amylase determined by the RIA was found to be 122.1 ng/ml (range: 55--250 ng/ml). A good correlation was observed between the concentration of amylase and its enzymatic activity in normal subjects. In some instances with high amylase activity, however, the rise in enzymatic activity was not accompanied by increasing amount of amylase content.

Amylases↗
PubMed1979

Longitudinal study or serum thyroid hormones, chorionic gonadotrophin and thyrotrophin during and after normal pregnancy.

Measurements of serum levels of thyroxine (T4), free T4, 3,5,3'-triiodothyronine (T3), free T3, 3,3',5'-triiodothyronine (reverse T3, rT3), thyroxine-binding globulin capacity (TBGcap), chorionic gonadotrophin (hCG) and thyrotrophin (TSH) were carried out prospectively in eight women with uncomplicated pregnancies, in order to examine interrelationships between the thyroid gland and thyroid stimulating hormones during pregnancy. During pregnancy the levels of T4, free T4, T3, rT3 and TBGcap were significantly elevated, and TSH was decreased. It was noted that the elevation of T4 was maintained from the 8th to the 27th week of gestation while the level of TBGcap progressively increased. The levels of free T4 and rT3 in the first and third trimesters were significantly higher than those of age-matched, non-pregnant women. The levels of hCG showed a biphasic variation, with a peak in the 8th to 15th weeks, followed by a decline in the second trimester and a small, secondary elevation in the 32nd to 39th weeks. This later elevation was positively correlated with changes in free T4 and free T3 levels. The increase of serum T4 accompanied by an increase of free T4 in the first trimester appeared due to augmented secretion of T4, rather than being secondary to the elevated levels of TBGcap.

Adolescent↗
PubMed1979

Relationship of iodide-induced increase in TSH response to TRH to changes in serum thyroid hormones.

Large doses of iodide (500 mg three times a day) administered to normal men for 10--12 days caused a rise in basal serum TSH and a concomitant rise in the peak TSH response to TRH. The basal and peak levels of TSH were highly correlated (p less than 0.001). However, the iodide-induced rise in the peak TSH after TRH was poorly correlated with concomitant changes in serum thyroid hormones. Serum T3 wa not lower after iodide and, while serum T4 was somewhat lower, the fall in serum T4 was unexpectedly inversely rather than directly correlated with the rise in the peak TSH response to TRH. Thus, increased TSH secretion after iodide need not always be directly correlated with decreased concentrations of circulating thyroid hormones even when large doses of iodide are used. Clinically, a patient taking iodide may have an increased TSH response in a TRH stimulation test even though there is little or no change in the serum level of T3 or T4.

Adolescent↗
PubMed1979

Effect of a single dose of glucocorticoid on the diurnal variations of TSH, thyroxine, 3,5,3'-triiodothyronine, 3,3'5'-triiodothyronine and cortisol in normal men.

Plasma thyrotropin (TSH) and cortisol concentrations were suppressed immediately after an intravenous bolus dose of 8 mg betamethasone in 6 male subjects. The circadian variations of these hormones disappeared for 40 hr (TSH) and 44 hr (cortisol). Plasma thyroxine (T4), 3, 5, 3'-triiodothyronine (T3), 3,3',5'-triiodothyronine (reverse T3) levels did not show diurnal variations before betamethasone administration. Plasma T3 levels decreased to 66% of the basal levels 20 hr after batamethasone administration, whereas plasma reverse T3 levels increased to 163% of the basal levels at 24 hr. These changes were reversed by 3 to 5 days after betamethasone. The earlier recovery of the diurnal rhythm of TSH than that of cortisol suggests that the TSH rhythm is not under the direct control of circulating cortisol.

Adult↗
PubMed1978

Differentiation of thyrotoxicosis induced by thyroid destruction from Graves' disease.

Thyroid function was tested in untreated patients with Graves' disease or thyrotoxic subacute thyroiditis, and in patients with autoimmune thyroiditis who showed postpartum or spontaneous transient thyrotoxicosis. The serum triiodothyronine/thyroxine ratio (T3/T4) was greater than 20 ng/microgram in Graves' disease but less than 20 in all patients with subacute thyroiditis and 9 of 11 patients with autoimmune thyroiditis. Thus, like radioactive iodine uptake, the serum T3/T4 ratio is useful for differentiating destruction-induced thyrotoxicosis from the stimulation-induced hyperthyroidism of Graves' disease.

Adult↗
PubMed1978

Thyroid function in patients undergoing maintenance hemodialysis: unexplained low serum thyroxine concentration.

Thyroid function was studied in 55 patients undergoing maintenance hemodialysis who were all judged to be clinically euthyroid. The dialysis patients, in comparison to normal control subjects, had significantly lower mean values for serum T4 (4.0 +/- 1.4 [SD] microgram/dl versus 7.9 +/- 1.5 microgram/dl, p less than 0.001), T3 (118 +/- 31 ng/dl versus 147 +/- 28 ng/dl, p less than 0.001), free T4 measured by equilibrium dialysis (1.22 +/- 0.38 ng/dl versus 2.15 +/- 0.67 ng/dl, p less than 0.001), free T3, free T4 index, and free T3 index. Serum TBG, measured by radioimmunoassay, was similar to that of the controls and serum TSH, 2.2 +/- 1.3 micromicron/ml, was also similar to that of control values, 2.0 +/- 1.1 micromicron/ml. The serum PBI did not change during the dialysis procedure, but serum inorganic iodine fell slightly from 2.1 +/- 1.1 microgram/dl before dialysis to 1.2 +/- 0.6 microgram/dl after dialysis (p less than 0.05). The marked reduction in serum total T4 and free T4 concentrations and the moderate reduction in serum total T3 and free T3 levels in apparently euthyroid patients undergoing hemodialysis has not been explained. The normal serum TSH levels in the face of these low concentrations of thyroid hormone suggests an abnormality in the control of TSH secretion in these patients.

Adult↗
PubMed1978

A new method of paired thyrotropin assay as a screening test for neonatal hypothyroidism.

A simple and reliable method of paired TSH assay was developed and used in screening for neonatal primary hypothyroidism. In this method, a paired assay is first done. Equal parts of the extracts of dried blood spots on filter paper (9 mm diameter) from two infants 4-7 days old are combined and assayed for TSH by double antibody RIA. If the value obtained is over the cut-off point, the extracts are assayed separately for TSH in a second assay to identify the abnormal sample. Two systems, A and B, with different cut-off points were tested. On the basis of reference blood samples (serum levels of TSH, 80 microU/ml in system A and 40 microU/ml in system B), the cut-off point was selected as follows: upper 5 (A) or 4 (B) percentile in the paired assay and values of reference blood samples in the second individual assay. Four cases (2 in A and 2 in B) of neonatal primary hypothyroidism were found among 25 infants (23 in A and 2 in B) who were recalled from a general population 41,400 infants (24,200 in A and 17,200 in B) by 22,700 assays. This paired TSH neonatal hypothyroidism.

Congenital Hypothyroidism↗
PubMed1977

Transient postpartum hypothyroidism: fourteen cases with autoimmune thyroiditis.

Twenty-five episodes of postpartum primary hypothyroidism were observed in 23 patients without thyroid hormone treatment: three were cases of irreversible hypothyroidism and the others were of transient hypothyroidism. The characteristics of transient postpartum hypothyroidism deduced by serial observations on 14 patients were [1] a high incidence of previous goiter; [2] thyroid enlargement at 1/2 to 4 months postpartum; [3] hypothyroidism at 3 to 5 months postpartum; [4] spontaneous recovery at 5 to 10 months postpartum; [5] high titers of antithyroid microsomal antibodies; and [6] persistence of small goiter. Transient postpartum hyperthyroidism before the occurrence of hypothyroidism and the recurrence of transient postpartum hypothyroidism were observed during two consecutive postpartum periods in two patients. Transient hypothyroidism was also observed in two patients after abortion. Fourteen of the 23 patients first noticed thyroid abnormality after delivery. These changes seem to be induced during the course of autoimmune thyroiditis by the immunologic changes occurring after delivery.

Abortion, Therapeutic↗