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Biomedical subjects

K Torizuka

Publications and source records attributed to K Torizuka.

At least 487 records · Page 27Linked to original sources
PubMed1975

Estimation of thyroxine and triiodothyronine distribution and of the conversion rate of thyroxine to triiodothyronine in man.

Studies on peripheral metabolism of simultaneously administered 125-I-labeled L-thyroxine ([125-I]T4) and 131-I labeled L-trilodothyronine ([131-I]T3) were performed in five normal subjects, in four patients with untreated hypothyroidism, and in 3 hypothyroid patients made euthyroid by the administration of T4. The fractional turnover rate (lambda 03) of thyroid hormones irreversibly leaving the site of degradation and the volumes of pool 1 (serum V1) of pool (interstitial fluid, V2), and of pool 3 (all tissues, V3)were obtained by using a three-compartment analysis. In addition to the turnover studies, the ratios for the in vivo T4 to T3 conversion were determined by paper chromatographic study in sera obtained 4, 7, and 10 daysafter the injection. The rate (K12) of the extrathyroidal conversion of T4 to T3 was also estimated by the compartment analysis. The T3 distribution volume (V3) of pool 3, in which T3 is utilized and degraded, was about 60% of totaldistribution volume (V=V1+V2+V3) in normal subjects, whereas only about 25% of the extrathyroidal T4 pool was in the intracellular compartment, indicating that T3 is predominantly an intracellular hormone..

Adult↗
PubMed1975

Radioimmunoassay for human calcitonin employing synthetic calcitonin M: its clinical application.

A sensitive and reliable radioimmunoassay for human calcitonin was described and applied to preliminary clinical studies. 125I-labelled synthetic human calcitonin M was purified by gel filtration with Sephadex G-25 and G-100. A nonequilibrium incubation system was applied at the final volume of incubation mixture of 500 mul, in which pooled plasma from normal subjects or hormone free serum was used as carrier protein at 20% incubation mixture. Dextran T 40 coated charcoal, resuspended in 1% bovine serum albumin buffer, was used for the separation of free from bound tracer. This showed the least nonspecific adsorption of tracer to charcoal. The assay was sensitive to 0.1 ng per milliliter of plasma. Recovery of synthetic human calcitonin added to plasma was found to be 101% (S. D., +/- 8). Diluted plasma from a patient with medullary thyroid carcinoma showed a dilution curve parallel to standards. Basal calcitonin levels were less than 0.3 ng/ml in normal subjects. Relatively high values were found in patients with chronic renal failure and in patients with malignant tumors. Extremely elevated values were found in patients with medullary thyroid carcinoma. Provocative calcium infusion tests were also performed.

Bone Neoplasms↗
PubMed1975

Functional imaging of intrarenal blood flow using scintillation camera and computer.

In order to obtain spatial distribution of an index for regional blood flow at each element on a scintigraphic image of the kidney, we attempted the construction of the so-called functional image. After injecting a single bolus of 133Xe into a renal artery by means of a catheter, this objective was accomplished using digital computer processing for a sequence of scintillation camera recordings of the following washout process from the kidney. This is expressed in a form of matrix of disappearance rate constant. Calculation for the rate constant, the flow index of the functional image, was done using either the least squares (LS) method or height-over-area (H/A) method. Although the former method was considered to be theoretically suitable without undue participation of background activities, the latter was preferred because of stable results for image construction. On reviewing the functional image thus obtained from 22 patients representing a variety of renal diseases, the H/A gave specific information concerning regional distribution of the perfusion integrity mainly related to the cortical part of the kidney. This is often difficult to accomplish utilizing the conventional method of compartmental analysis of the xenon washout curve or selective renal angiography.

Angiography↗
PubMed1975

Tumor imaging after administration of 99mTc-labeled bleomycin.

Bleomycin, an anticancer drug, was labeled with 99mTc using stannous chloride and ascorbic acid and specific activities of 1-3 mCi/mg-eq with labeling efficiencies of 50-75% were achieved. Very rapid excretion of 99mTc-bleomycin through the kidney and concomitant rapid decrease of radioactivity in blood, various tissues and organs, and whole body were observed after intravenous administration of the radiopharmaceutical into tumor-bearing mice. In such animals, approximately 1% of the label was found in a transplanted fibrosarcoma within 30 min while 0.58% was recovered in such lesions even after 24 hr. In patients positive tumor images were obtained by scintigraphy as early as 1 hr after intravenous administration of 3-5 mCi of 99mTc-bleomycin. A total of 142 cases were examined by scintigraphy after administration of 99mIc-bleomycin and/or 67Ga-citrate. In 93 cases with various malignant tumors, tumor was detected in 80% using 99mTc-bleomycin and in 63% using 67Ga-citrate. Technetium-99m-bleomycin scintigraphy successfully detected tumors of the thyroid, lung, face, breast, extremity, and digestive tract and was also useful in finding metastatic lesions and brain tumors. However, 67Ga scintigraphy gave superior results in detecting lesions in patients with malignant lymphomas. In patients with inflammatory diseases, accumulation in lesions was detected in 13% using 99mTc-bleomycin and in 48% using 67Ga-citrate. The further use of 99mTc-bleomycin scintigraphy for tumor detection in patients appears to be warranted.

Abdominal Neoplasms↗
PubMed1974

Conventional and dual competitive binding analyses of thyroxine using the Thyopac-4 kit.

A simple method is described for the simultaneous determinations of thyroxine and the effective thyroxine ratio (ETR) using a single kit of Thyopac-4. Thyopac ETR values obtained were 1.00 +/- 0.03 for normal subjects; 1.22 +/- 0.11 for hyperthyroid; 0.87 +/- 0.04 for hypothyroid; and 1.02 +/- 0.05 for pregnant women. Cases with TBG deficiency and the nephrotic syndrome indicated normal values. The value (x) was correlated significantly (gamma = + 0.961) with the free Thyopac index (y), representing a regression equation of y = 71.7x(2) - 88.4x + 24.2. Thyopac ETR was shown to be useful in differentiating normal thyroid states from abnormal, irrespective of changes in T(4)-binding globulin (TBG). Further, the T(4) value obtained simultaneously made it possible to detect changes in the TBG level by noting an inconsistent value for the effective thyroxine ratio.

Binding, Competitive↗