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Biomedical subjects

K Machida

Publications and source records attributed to K Machida.

At least 235 records · Page 13Linked to original sources
PubMed1987

Optimal preprocessing Butterworth-Wiener filter for Tl-201 myocardial SPECT.

The optimal frequency characteristic of Butterworth-Wiener filters (BWF) for improving the image quality of 201Tl myocardial SPECT was determined by a phantom experiment. Thirty two projection images of the phantom containing 11.1 MBq of 201Tl with 4 different cold lesions were collected during a 180 degree arc of a gamma camera. A set of the projection images were processed with each of 27 different BWFs, and SPECT images were reconstructed by Shepp-Logan filtered backprojection. The SPECT images were evaluated for their diagnostic ability to visibly detect the cold lesions by four nuclear medicine physicians. The lesion contrasts were used as an adjunctive tool to determine the optimum filter. The optimal combination of the parameters determining BWF characteristics (for the data of about 100 count/pixel at the myocardium) is: 1) cutoff of 0.25/pixel, 2) FWHM of 3 pixels, 3) noise/signal ratio of 0.02. FWHM and noise/signal ratio affected lesion contrast much less than cutoff frequency. Clinical myocardial SPECT images processed with the optimal BWF showed less noise and sharper delineation of the myocardium.

Filtration↗
PubMed1987

Iodine-123 IMP SPECT before and after bypass surgery in a patient with occlusion of left anterior and middle cerebral arteries with basal abnormal telangiectasis (unilateral Moyamoya disease).

A case of left anterior and middle cerebral arterial occlusion with angiographic features similar to Moyamoya disease was reported. IMP SPECT of the patient revealed the success of bypass surgery clearly. The patient complained of transient right hemiparesis with aphasia 4 times. The cerebral arteriography disclosed occlusions of left anterior and middle cerebral arteries at their proximal portions. Right internal carotid and its branches were normal. I-123 IMP SPECT study showed hypoperfusion in left temporal lobe, basal ganglia with incomplete reperfusion on the delayed (4 hours after injection) SPECT images. After the superficial temporal-middle cerebral artery anastomosis, I-123 IMP SPECT showed improvement of the brain blood flow. I-123 IMP SPECT was very useful in detecting the ischemic areas and evaluating the revascularizing surgery in this case.

Adult↗
PubMed1987

Genetic control of immune response to staphylococcal exfoliative toxin A in mice.

Different inbred and congenic resistant strains of mice were immunized with staphylococcal exfoliative toxin A (ETA). In antibody responses measured in sera of mice by a passive hemagglutination technique, A/J, DBA/2, BALB/c, B10A, B10D2, B10S, and A.SW were high responders. C57BL/10 (B10), A.BY, and DBA/1 were low responders. The congenic C3H/HeJ and C3H.SW mice were, respectively, high and low responders. The observation that the immune responses of the mice to ETA were closely linked with the haplotypes of their H-2 complexes suggests the existence of an H-2-linked immune response (Ir) gene coding for the production of humoral antibodies to ETA. Four B10A recombinants were used to map this gene within the H-2 complex. The finding that B10A(2R) and B10A(4R) were high responders, whereas B10A(3R) and B10A(5R) were low responders, indicates that the gene controlling antibody response to ETA is located in the I-A subregion or the H-2K end within the H-2 complex. We wish to propose the name Ir-ETA for this gene. The function of Ir-ETA seems to be at least related to antigen recognition at the T-lymphocyte level. Neonatal mice are generally susceptible to ETA regardless of their H-2 haplotypes. However, the neonatal mice born to a high-responder mother immunized with ETA were resistant to the subcutaneous challenge of ETA, but those born to an immunized low-responder mother were susceptible to the challenge. This result suggests that if the mother is a high responder to ETA and is effectively immunized with ETA, the maternal immunity makes it possible to neutralize this toxin in neonatal mice.

Animals↗
PubMed1987

[Results obtained from the group study on the clinical efficacy of SPECT of the liver].

The influence of SPECT over the detectability of SOL in the liver was evaluated by the Subcommittee on Efficacy Study, which belongs to Medical and Pharmaceutical Committee of Japan Radioisotope Association, under the participation of 9 hospitals including some university hospitals. In this study segmental reading of the SOL was requested. The film reading was performed twice on the different patient-groups and the results from well-experienced doctors (11 doctors) were summarized, indicating a slight increase in sensitivity as a whole although there were some doctors showing a reverse effect in each performance. Sensitivity was determined in the patient-group without SOL, which showed a slight decrease as a whole, indicating that SPECT had some possibility of increasing false positive cases. In the study of SOL detectability based on its segmental location, a marked positive effect of SPECT was noted in the right anterior and right posterior segments whereas a marked negative effect in the left lateral segment. The left medial segment also showed a slight decrease in the detectability of SOL.

Evaluation Studies as Topic↗
PubMed1987

[A cooperative group study of clinical efficacy of the liver SPECT].

The purpose of this study is to evaluate the clinical efficacy of the liver SPECT about detectability of SOLs (space occupying lesion). The images were interpreted with the planar scintigram (PS) only and combination of PS and SPECT (single photon emission computed tomography) by 11 physicians. Changes of false positive and false negative rate were calculated to evaluate the influence of the diffuse parenchymal liver disease and the localization of the SOLs. Addition of SPECT to PS in the cases who are suspected SOLs is effective in right hepatic lobe (right anterior and posterior segment) to detect the SOLs, but not effective in left lateral segment. Addition of SPECT to PS in the cases with diffuse parenchymal liver disease and SOLs increases the false positive rate.

Chronic Disease↗
PubMed1987

Evaluation of regurgitant fraction of the left ventricle by gated cardiac blood-pool scanning using SPECT.

Regurgitant fraction (RF) of patients with and without mitral regurgitation (MR) and/or aortic regurgitation (AR) was evaluated by gated cardiac blood-pool scanning using single photon emission computed tomography (SPECT). Using the stroke count image of a short-axis tomogram to separate the right atrium and ventricle, the left ventricular stroke count (LVSC) and right ventricular stroke count (RVSC) were determined. The RF equaled (LVSC - RVSC)/LVSC. Calculated RF in 14 subjects without significant regurgitation by contrast angiography was 5.8 +/- 5.9% (mean +/- s.d.), RF of 17 cases with angiographic regurgitation was 42.5 +/- 16.8% (p less than 0.001). The sensitivity of the radionuclide method compared to angiography was 94% (16/17 cases), and specificity was 100% (14/14 cases). RF of mild Re (1+ or 2+) was 26.0 +/- 8.9% (n = 6) and RF of severe Re (3+ or 4+) was 51.5 +/- 12.7% (n = 11) (p less than 0.001). Correlation between the RF determined with the radionuclide method and with cardiac catheterization was good (y = 5.85 + 0.700 x, r = 0.821, n = 17). We conclude that RF of MR and/or AR can be accurately evaluated by gated cardiac blood-pool scanning using SPECT.

Cardiac Catheterization↗
PubMed1986

Characterization of a newly established feline lymphoma-derived cell line (BKD) lacking T and B cell surface markers.

A new feline lymphoma-derived cell line, designated BKD, was isolated from an anterior mediastinal tumor. Cells of this line were characterized as lymphoid based on morphology, the lack of intracellular esterase and peroxidase activity, and absence of phagocytic function. In contrast with other established feline lymphoma-derived cell lines, cells of the BKD line lack characteristics of both feline T-cells and B-cells in that they neither form rosettes with guinea pig erythrocytes nor have demonstrable surface or cytoplasmic immunoglobulin. Approximately one third of BKD cells form EAC rosettes, a significant number of rosette forming cells (p = 0.0001) when compared to background sheep E-rosetting activity. In addition, a consistently titratable level of interleukin-2-like activity was produced when BKD cells were coincubated with concanavalin A and phorbol-12-myristate-13-acetate. Chromosome analysis showed that a majority of BKD cells are diploid. This new cell line has been continuously replicating in culture for over one year and produces feline leukemia virus as demonstrated by several analyses.

Animals↗
PubMed1986

Protective effect of zinc against lethality in irradiated mice.

The protective effect of zinc against radiation hazard was observed by comparing LD50(30) values of irradiated mice with and without the administration of zinc before irradiation. Two hundred male mice, 7 weeks old, were irradiated with an intestinal dose at 5.62, 6.31, 7.08, 7.94, 8.91, or 10.00 Gy, with or without oral administration of zinc from 10 days prior to gamma irradiation until the end of the study. The reduction of mortalities in zinc-administered mice in comparison to controls was most prominent at the dose of 7.94 Gy, i.e., the mortality rate in the zinc-administered group was 0.44 and that in the control group was 1.00. At a dose of 8.91 Gy, zinc-administered mice survived significantly longer than controls. The LD50(30) of zinc-administered mice was 7.70 Gy, while that of the control was 6.90 Gy. In zinc-administered mice the acceleration of turnover and elevated excretion of radioactive zinc were observed, while the concentration of stable zinc in organs remained constant. The effect of zinc was not observed in experiments in vitro using human melanoma cells. Therefore it can be assumed that the protective effect of zinc against radiation would correlate with the homeostatic mechanism of zinc which exists in the whole body of mammalians.

Animals↗