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Biomedical subjects

T Mukai

Publications and source records attributed to T Mukai.

At least 343 records · Page 19Linked to original sources
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

[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

[Ba-induced contraction of the guinea pig ileal longitudinal muscle and its inhibition by D-600, benactyzine, and papaverine].

In the guinea-pig ileal longitudinal smooth muscle, Ba caused an initial phasic contraction, followed by a gradual decrease of the contraction (tonic contraction). In the Ca-free and the Ca-free, K-rich physiological solution, Ba could also contract the longitudinal muscle, but 30 min- and 60 min-immersion of the tissue in the Ca-free solution decreased lower than 20% of control of the Ba contraction. Although the K-induced depolarization intensified the Ba contraction after the 30 min-immersion, within 10 min after the immersion in the two solutions there is no difference in the height of Ba contractions. In the normal physiological solution, Ba seems to serve the contractile protein with free Ca ions rather than itself for the Ba contraction. D-600 induced an equal inhibition on the Ba contractions in the normal physiological solution and in the Ca-free solution, and it inhibited the tonic contraction more than the phasic one. The phasic component may be due to the cellular Ca mobilized by Ba which passes through D-600-sensitive pathway, and at least part of the tonic component may utilize the extracellular Ca. Benactyzine perferentially inhibited the Ba contraction in the Ca-free solution, and it depressed the phasic component more than the tonic one. Treatment with papaverine induced an equal inhibition on the phasic and tonic components of Ba contractions and the Ba contraction in the Ca-free solution. Benactyzine may exert the main influence on the mobilization of the cellular Ca through the competition with Ca. Papaverine seems to inhibit the Ba contractions by diverse actions.

Animals↗
PubMed1983

[Histamine-induced contraction of the guinea pig taenia coli and its inhibition by D-600, papaverine, and benactyzine].

The histamine-induced contractions and effects of some smooth muscle relaxants on their contractions were examined in the guinea-pig taenia coli. Application of Ca to the Ca-free physiological solution caused a contraction of the taenia coli (Ca contraction), and histamine accelerated and increased the Ca contraction (H . Ca contraction). Histamine also contracted the taenia coli in the Ca-free solution (Ca(-) . H contraction). D-600 which preferentially reduces the Ca influx into muscle cells, more effectively depressed the H . Ca contraction and more feebly the Ca(-) . H contraction than histamine-induced contraction in the normal physiological solution. Papaverine inhibited the H . Ca contraction and the Ca(-) . H contraction more than the histamine-induced contraction. Benactyzine was a specific agent against the Ca(-) . H contraction. When the Ca contraction reached the peak, application of histamine induced a further contraction. D-600 effectively inhibited the Ca contraction and the further contraction induced by histamine. Although papaverine blocked the Ca contraction similarly to D-600, the application of histamine produced a large contraction. Benactyzine induced only a feeble inhibition on the Ca contraction, but it was effective against the following contraction caused by histamine. Histamine probably mobilizes the extracellular and cellular Ca and contracts the smooth muscle. Papaverine seems to inhibit smooth muscle contractions by diverse actions. Benactyzine may exert the main inhibition on the mobilization of the cellular Ca through the competition with Ca.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
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↗
PubMed1982

Cloning of rpsO, the gene for ribosomal protein S15 of Escherichia coli.

The gene for Escherichia coli ribosomal protein S15 (rpsO) was cloned on the vector pBR322 from F-prime JCH55 DNA. The recombinant plasmid was transformed to Serratia marcescens cells and it was proved that E. coli S15 was synthesized and incorporated into ribosome particles in S. marcescens cells. A DNA fragment containing rpsO was also inserted into the vector pRF3, which changes its copy number depending on the growth temperature in a temperature-sensitive polA host. By use of this recombinant plasmid it was shown that the relative synthesis rate of S15 increased about twice even when the copy number of the plasmid increased more than twenty-fold.

Cloning, Molecular↗
PubMed1982

Clinical evaluation of emission tomography using seven-pinhole collimator: improved detection of perfusion defect by the addition of the right anterior oblique projection.

The clinical efficacy of thallium emission myocardial tomography using a seven-pinhole collimator in the right anterior oblique (RAO) projection was evaluated. Myocardial tomography in left anterior oblique (LAO) and RAO projections was performed following planar thallium perfusion imaging at rest in 11 patients with myocardial infarction. The RAO tomogram was useful, especially in detecting apical perfusion defects, while the LAO tomogram was useful in detecting inferior and anteroseptal wall defects. For the four patients without an apparent myocardial perfusion defect seen on the planar image, the LAO tomogram showed a perfusion defect in three, and the RAO tomogram also showed the defect in three. One or the other of the two views demonstrated the defect for all 11 patients. The myocardial tomogram in the RAO projection, providing a sufficiently high-quality and high-contrast image, gives useful information complementary to the findings of the commonly used LAO projection in the evaluation of myocardial infarctions.

Adult↗
PubMed1982

Estimation of infarct size by myocardial emission computed tomography with thallium-201 and its relation to creatine kinase-MB release after myocardial infarction in man.

We evaluated emission computed tomography (ECT) for thallium-201 (201TI) myocardial imaging in estimating infarct size (IS). In 18 patients in whom IS was estimated enzymatically at the time of the acute episode, planar 201TI perfusion scintigraphy and ECT with a rotating gamma camera were performed 4 weeks after the first myocardial infarction. From the size of 201TI perfusion defects, the infarct area in planar images and the infarct volume in reconstructed ECT images were measured by computerized planimetry. When scintigraphic IS was compared with the accumulated creatine kinase-MB isoenzyme release (CK-MBr), infarct volume determined from ECT correlated closely with CK-MBr (r = 0.89), whereas infarct area measured from planar images correlated less satisfactorily with the enzymatic IS (for an average infarct area from three views, r = 0.69; for the largest infarct area, r = 0.73). Although conventional scintigraphic evaluation is useful for detecting and localizing infarction, quantification of ischemic injury with this two-dimensional technique has a significant inherent limitation. The ECT approach can provide a more accurate three-dimensional quantitative estimate of infarction, and can corroborate the enzymatic estimate of IS.

Adult↗
PubMed1982

Relationship between the Ba-induced contraction and cyclic AMP levels in the isolated longitudinal smooth muscle from guinea pig ileum.

Relationship between contraction and cyclic AMP levels induced by BaCl2 was examined in the longitudinal smooth muscle isolated from guinea pig ileum. BaCl2 3 X 10(-3)M caused a fast initial contraction, often followed by a gradual decrease of the contractile state. There was an increase in the tissue cyclic AMP 7 min or 14 min after the application of Ba. A phosphodiesterase activator imidazole reinforced the later phase of contraction by Ba and inhibited the increase in cyclic AMP. These results indicate that there is still a positive correlation between relaxation and increase in cyclic AMP and that an inhibitory action mediated by cyclic AMP is veiled behind the Ba contraction. Furthermore, these results may be interpreted by assuming that strong Ba contraction operates a feedback mechanism and that the feedback mechanism is associated with cyclic AMP increase. Indomethacin, an inhibitor of prostaglandins synthesis, little influenced the Ba-induced increase in cyclic AMP and rather inhibited the Ba contraction. Propranolol, a beta-adrenergic blocking agent, failed to exert influence on the Ba contraction. Based on these facts, it is suggested that the increase in cyclic AMP is not mediated by prostaglandins or catecholamines.

Animals↗
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↗