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Biomedical subjects

K Torizuka

Publications and source records attributed to K Torizuka.

At least 307 records · Page 17Linked to original sources
PubMed1982

Assessment of severity of tricuspid regurgitation by analog computer analysis of dilution curves recorded by scintillation camera.

To estimate the severity of tricuspid regurgitation, we developed a new mathematical model of the circulatory system, in which the right atrium and the right ventricle were represented by a single mixing chamber and tricuspid regurgitation was expressed as a reverse flow from the right ventricle to the right atrium with a time delay equivalent to one cardiac cycle. The actual dilution curves obtained from the right atrium and the right ventricle following rapid intravenous injection of Technetium-99m-macroaggregated human albumin were fitted to the theoretical curves based on the above-described model. The use of macroaggregated albumin avoided the contamination of the dilution curves by radio-activity from the left heart or by the recirculation of the tracer due to left to right shunt. Mean transit times and percentage of regurgitation, as given by the ratio of regurgitant flow to total outflow from the right ventricle, were determined by an analog computer. The correlations of these results with the findings of other examinations, including contrast echocardiography, demonstrated that the present method may be useful in detecting tricuspid regurgitation and in grading its severity.

Cardiac Output↗
PubMed1982

Technetium-99m pyrophosphate uptake in spontaneously occurring perimyocardial lesions in an inbred strain of DBA/2 mice.

The spontaneous occurrence of perimyocardial calcification localized in the right ventricle has been reported in an inbred strain of DBA/2 mice. In this paper we examined the correlation between the myocardial uptake ratio of technetium-99m pyrophosphate (99mTc-PYP) and pathological findings in these mice ranging in age from one to 12 months and became lower with age, while calcification and fibrosis in the perimyocardium of the right ventricle became more prominent in aged mice. This may be due to an insidious onset of degeneration with calcification and fibrosis in spontaneously occurring perimyocardial lesions in these mice. Persistent abnormal uptake of 99mTc-PYP observed in the present study suggests the usefulness of such scintigrams in the diagnosis of chronic perimyocardial disease.

Animals↗
PubMed1982

Identification of patients with coronary artery disease using a scoring system of coronary risk factors, electrocardiography and myocardial perfusion imaging.

To determine whether clinical variables of coronary risk factors and electrocardiographic and scintigraphic findings could reliably detect the presence of coronary artery disease and of coronary stenosis in the individual coronary arteries, 11 clinical and 7 electrocardiographic and scintigraphic variables were compared with the findings of coronary angiography in 107 patients. Sixty-seven patients had angiographic evidence of coronary artery disease and forty did not. Exercise electrocardiograms were diagnostic in 43 patients (64%) and exercise thallium-201 scintigraphy in 56 (84%). A coronary scoring using all the above variables based on multiple discriminant analysis increased the diagnostic accuracy (sensitivity 96% and specificity 95%). This scoring system was applied to a prospective series of 59 cases with similarly selected patients. Fifty-five cases (93%) were correctly diagnosed. The coronary scoring system to assess the stenosis of individual arteries was less satisfactory and 51 cases (86%) of the right coronary, 51 (86%) of the left anterior descending and 44 (75%) of the left circumflex artery were accurately diagnosed. It is concluded that statistical multivariate analysis of clinical, electrocardiographic and scintigraphic variables facilitates the detection of coronary artery disease and that this scoring system is helpful in assessing the probability of individual coronary artery involvement.

Angina Pectoris↗
PubMed1982

Adipocyte-TSH-receptor-related antibodies in Graves' disease detected by immunoprecipitation.

Fat cell TSH receptor-related antibodies were detected by immunoprecipitation of 125I-TSH-receptor complexes and the nature of the antibodies was analyzed. To 125I-TSH prebound to Triton-solubilized receptors from guinea pig fat tissues, 50 micrograms of immunoglobulin G (IgG) was added and precipitation was effected by the addition of antihuman IgG. Immunoprecipitation values in 13 patients with Graves' disease were significantly (p less than 0.05) higher than those in 11 normal subjects. No significant increase in the values was seen in 8 patients with Hashimoto's disease. No correlation was observed between immunoprecipitation values and titers of antimicrosomal and antithyroglobulin antibodies. Neither was there any correlation between the values and TSH-binding inhibitor immunoglobulins (TBII) detected by the radioreceptor assay. The IgG fractions positive for the immunoprecipitation antibody were found to be poor human thyroid stimulators (HTS) relative to their TBII activities. And a highly significant correlation was observed between TBII and HTS activities among IgGs without detectable antibody by immunoprecipitation (r=0.907; p less than 0.005; n=7). These findings 1) demonstrate that immunoprecipitation assay using fat cell TSH receptor may detect TSH receptor-related antibodies different from TBII in patients with Graves' disease and 2) suggest the antibodies may recognize determinants on the receptor or its vicinity that do not participate in the binding of TSH or thyroid stimulating antibody, and may interfere with thyroidal response to these stimulators.

Adipose Tissue↗
PubMed1982

Detection of TSH-binding inhibitor immunoglobulins by using the triton-solubilized receptor from human thyroid membranes.

A radioreceptor assay of TSH using Triton-solubilized human thyroid receptors was applied to the detection of TSH-binding inhibitor immunoglobulins (TBII). In 26 untreated patients with Graves' disease, 20 (76.9%) were found positive in this assay, while 18 (69.2%) cases were found positive by the conventional assay using human thyroid particulate receptors. In 25 patients with goitrous Hashimoto's thyroiditis, 2 (8.0%) were found positive by the assay using soluble receptor, while 3 (12.0%) were found positive by the conventional one. A significant correlation was found between TBII activities in the patients with untreated Graves' disease detected by these two assay systems (r=0.69; n=26; p less than 0.001). These data support the concept that TBII are antibodies against the TSH receptor or its closely related structures.

Cell Membrane↗
PubMed1982

Hemodynamic significance of increased lung uptake of thallium-201.

To determine the hemodynamic significance of increased lung thallium-201 uptake, resting thallium images in 23 normal subjects and 90 patients with various cardiac diseases were reviewed. Significant thallium uptake in the lung was observed in 60 cases and was especially frequently in mitral valvular disease (19 of 19 cases) and in myocardial infarction (25 of 37 cases). Chest radiographs of most of these patients showed pulmonary congestion or edema (50 or 69 cases). Pulmonary wedge pressure was measured in 25 of these patients and was significantly higher than in those of normal thallium uptake in the lung. Assessment of lung thallium uptake at the time of myocardial imaging can be used as a noninvasive means for evaluation of pulmonary venous hypertension.

Adolescent↗
PubMed1982

Effect of anti-thyroxin autoantibodies on radioimmunoassay of free thyroxin in serum.

Serum thyroxin was nearly or completely undetectable by radioimmunoassay in an elderly patient with Graves' disease being treated with methimazole. Abnormal binding of thyroxin to antibodies of the IgG variety was shown, the association constant of the complex being 8.0 x 10(8) L/mol and the binding capacity 6.3 nmol/g of IgG. The effect of the antibody on results of radioimmunoassay of free thyroxin was studied with three commercial kits, two of which (Clinical Assays and Damon Diagnostics) gave essentially the same values as did equilibrium dialysis. The third (Amersham International) gave falsely high results because the 125I-labeled thyroxin derivative used in the kit was bound by the autoantibody.

Autoantibodies↗
PubMed1982

Comparative study of thallium emission myocardial tomography with 180 degrees and 360 degrees data collection.

Basic and clinical evaluation of thallium single-photon emission computed tomography (SPECT) using a rotating gamma camera with 180 degrees (LPO to RAO) data collection was carried out and compared with the full 360 degrees rotation. No attenuation correction was used. In a phantom study the reconstructed image from the 180 degrees scan revealed better resolution. Although the 180 degrees scan, when compared with the 360 degrees scan, showed great photon attenuation in the deep location of a line source in water, this problem was not significant in the clinical study of six normal hearts. In 11 cases with myocardial infarction, the perfusion defect was more clearly visualized in the 180 degrees scan. The defect-to-normal (D/N) wall-count ratio was lower in the 180 degrees scan (0.48 +/- 0.16; mean +/- s.d.) than in the 360 degrees scan (0.61 +/- 15, p less than 0.05), indicating superior lesion contrast in the former. These results suggest that for myocardial SPECT the 180 degrees collection method is a more effective technique in the clinical evaluation of coronary artery disease.

Coronary Circulation↗