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Biomedical subjects

K Torizuka

Publications and source records attributed to K Torizuka.

At least 271 records · Page 15Linked to original sources
PubMed1983

Partial purification and properties of the TSH receptors from human thyroid plasma membranes.

Human thyroid plasma membranes were solubilized with 0.5% Triton X-100 and TSH receptors were purified by using DEAE-Sephadex, Con A and TSH affinity chromatography. A TSH binding activity was bound to DEAE-Sephadex equilibrated with 0.05 M sodium acetate, pH 6.3, 0.2% Triton X-100 and was eluted by a linear gradient of 0.1 M to 1.0 M ammonium acetate, pH 6.3. Eighty-five percent of the activity was absorbed to Con A Sepharose and was eluted with 0.5 M alpha-methyl-D-mannoside, 0.05 M sodium acetate, pH 6.0. Seventy-five per cent of the TSH binding capacity could be absorbed to TSH-affinity column and was eluted with 0.1 M glycine-HCl, pH 3.0. By sequential application of the above procedures, more than 100-fold purification of the receptor activity was attainable. [125I]TSH binding of this fraction was inhibited by addition of unlabelled TSH in a dose-dependent manner. Scatchard analysis gave a curvilinear plot with a high affinity association constant of 0.72 X 10(9)M-1. By using Ultrogel AcA 34 gel filtration, the molecular size of the hormonereceptor complex was estimated to be 180 000.

Cell Membrane↗
PubMed1983

[Stress thallium-201 myocardial emission CT: comparative evaluation with coronary arteriography and left ventriculography].

Thallium-201 emission computed tomography (ECT) using a rotating gamma camera was performed during stress and redistribution phases in 70 cases admitted for cardiac catheterization. A series of transaxial, ventricular short-axis, and long-axis sections were reconstructed, and segmental analysis was performed to predict individual coronary artery involvement. A perfusion defect was observed in 54 of 57 cases with coronary artery disease (95%). Ninety of 108 diseased coronary arteries (83%) were correctly identified (91% of single-vessel disease, 82% of two-vessel disease and 80% of three-vessel disease). No significant perfusion defect was seen in 11 of 13 cases with normal coronary arteries (specificity 85%). Number of diseased coronary arteries was accurately predicted in 78% of those with single-vessel disease, 65% of those with two-vessel disease and 47% of those with three-vessel disease, indicating relatively poor accuracy for predicting multivessel disease. The sensitivity for detecting individual coronary artery involvement was 90% for the right coronary artery (RCA), 89% for the left anterior descending artery (LAD) and 67% for the left circumflex artery (LCX). The specificity was 87%, 91%, and 100%, respectively. Even in those with three-vessel disease, a perfusion defect was seen in 82% of RCA and LAD segments, and 76% of LCX segment. Thus, there were high sensitivity and specificity for detecting individual coronary involvement by ECT imagings. Segmental analysis of ECT imagings was comparatively performed with the findings of contrast ventriculography. Normal wall motion was seen in 95% of normally perfused myocardial segments.(ABSTRACT TRUNCATED AT 250 WORDS)

Coronary Disease↗
PubMed1983

[Detection of cancer by radionuclide imaging].

Tumor imaging by radiopharmaceuticals classified into two modalities; The one is a negative imaging, whereby a tumor is depicted as a non-functional cold spot. The other is a positive imaging on the use of tumor seeking agents. The detectability of the tumor as a cold spot has enhanced by introducing the emission computed tomography. A variety of effort to develop specific tumor seeking agents are in progress, by radio-labeling tumor specific antigen and its abnormal metabolic conditions using cyclotron produced radioactive metabolites as well as radiometal compounds.

Humans↗
PubMed1983

[Evaluation of myocardial infarction by thallium emission computed tomography].

Thallium myocardial emission computed tomography (ECT) using a rotating gamma camera was undertaken to assess three-dimensional thallium distribution in the myocardium in cases with myocardial infarction (MI). Ninety-one cases with MI and 29 normal persons were examined by thallium ECT and the conventional planar imaging. Diagnostic performance and quantification of MI, and characterization of non-transmural MI were also investigated. In the detection of a perfusion defect, the ECT imaging showed significantly higher sensitivity (96%) than the planar imaging (77%) (p less than 0.001), especially in those with inferior wall MI (95% vs 73%, p less than 0.02) and nontransmural MI (82% vs 27%) (p less than 0.01). The specificity was the same in both techniques (90%), and therefore, higher overall accuracy was obtained by the ECT imaging (94%) than by the planar imaging (80%) (p less than 0.01). The receiver operating characteristic (ROC) curves were obtained from three independent observers for quantitative evaluation of observer detection performance. The ECT curves in each observer were situated in the upper left corner, indicating excellent diagnostic performance. Infarct size was estimated from the extent of the perfusion defect expressed as a percentage of the planar imaging (% defect) and as a volume of the infarcted myocardium (infarct volume). Those parameters were significantly correlated with peak CPK (r = 0.80 and 0.94, respectively), and inversely correlated with left ventricular ejection fraction (r = -0.78 and -0.85, respectively). Thus, the infarct volume calculated from the ECT is considered to permit estimation of infarct size more accurately than % defect from the planar imaging. To characterize nontransmural MI, 11 cases with nontransmural MI were examined by ECT and the findings were compared with those of transmural MI. A perfusion defect was detected in nine of the 11 patients (82%). As compared to those with transmural MI, infarct volume was smaller and the residual activity in an infarct region was higher in cases with nontransmural MI. Thus, the thallium ECT imaging, providing any-angle multisection of the myocardium, permits qualitative and quantitative evaluation of MI accurately.

Humans↗
PubMed1983

[Regional renogram and functional imaging with I-123-orthoiodohippurate in obstructive nephropathy].

Renal scintigraphy and regional renography using I-123- orthoiodohippurate were performed in 26 cases of obstructive nephropathy. After 1 mCi of I-123- orthoiodohippurate was given intravenously, serial renal scintigrams were obtained for 25 minutes and regional renogram curves were derived from the whole kidney, the cortical and pelvic areas. At the same time, renal functional images with Tmax as the peak arrival time were processed. Tmax in normal cases ranged from 2 to 3 minutes in the cortex and from 4 to 5 minutes in the pelvis, while there was some delay in Tmax in the obstructive nephropathy. In the case of acute ureteral obstruction by stones, most of the regional renograms in the cortex and pelvis improved soon after the removal of the obstruction. On the contrary, in the case of chronic obstructive nephropathy obstructive patterns on renogram curves was usually observed postoperatively. However, in some cases, functional images in cortical and/or pelvic areas showed marked recovery before improvement of findings on renograms or IVP. I-123- orthoiodohippurate renoscintigraphy is a useful adjunct for assessing pre- and post-operative renal function in obstructive nephropathy. Particularly, the analysis of regional renogram curves enables early prediction of postoperative recovery, and the functional image enables early detection of the functional recovery of the hydronephrotic kidney.

Adolescent↗