Search PubMed⌕ Search

Biomedical subjects

M Itaya

Publications and source records attributed to M Itaya.

At least 73 records · Page 4Linked to original sources
PubMed1983

[Left ventricular performance during exercise in patients with constant heart rate].

In order to evaluate the response of left ventricular (LV) performance in pacemaker implanted patients (PMI pts) with constant heart rate during exercise, supine bicycle ergometer exercise was performed simultaneously in 21 PMI pts and 4 age-matched normal subjects. PMI pts were classified into two groups; Group I consisted of 16 pts with relatively good physical work capacity (maximal load: male; 80 watt or more, female; 60 watt or more), and Group II consisted of 14 pts with depressed physical work capacity (maximal load: male; 60 watt or less, female; 40 watt or less). During dynamic exercise LV end-diastolic dimension (EDD), stroke excursion (SE), percent fractional shortening (%FS) and posterior wall velocity (PWV) showed a significant increase and LV end-systolic dimension (ESD) showed a significant decrease in Group I in contrast with Group II and normal subjects. Systolic blood pressure (sBP) and sBP/ESD ratio significantly increased in Group I and normal subjects than in Group II. Furthermore, resting cardiac parameters were more impaired in Group II than Group I. Thus, it was suggested that Group I adapted to exercise according to Frank-Starling mechanism (increased EDD) and contractility due to probably increasing circulatory catecholamine (increased PWV and decreased ESD). On the other hand, Group II did not adapt sufficiently to exercise because of the limitation of preload-reserve and contractility-reserve on exercise and also at rest.

Cardiac Output↗
PubMed1982

Steady-state kinetic studies of the inhibitory action of Zn2+ on ribonuclease T1 catalysis.

The kinetic mechanism of specific inhibition by Zn2+ of ribonuclease T1 catalysis was studied by steady-state kinetic analysis of transphosphorylation of dinucleotides, GpCp(3'), GpUp(2') and GpUp(3'), and dinucleoside monophosphates, GpC and GpU. The inhibition was not simply competitive, non-competitive or uncompetitive, but the kinetic data were compatible with a mechanism of 'fully mixed inhibition' in which a fully non-competitive action was associated with a partially competitive action. Apparent equilibrium quotients involved in this model of inhibition were determined for the dinucleotide substrates, and we found that binding of either of Zn2+ and substrate was facilitated when the other was bound. The location of Zn2+ was suggested to be near His-40 and/or His-92 of the ribonuclease T1 molecule.

Binding Sites↗
PubMed1982

[Exercise two-dimensional echocardiography: correlation between exercise induced asynergy and coronary artery lesions].

Exercise two-dimensional (2-D) echocardiography was performed in patients with suspected coronary artery disease, and exercise induced left ventricular asynergy was evaluated qualitatively and was compared with the coronary artery stenosis and electrocardiographic ST changes. Subjects were 12 patients with angina of effort, 8 patients with spontaneous angina, 8 patients with chest pain syndrome with the normal coronary artery, and 7 patients with hypertrophic cardiomyopathy (HCM). Cases with myocardial infarction were excluded from this study. 1) Left ventricular asynergy during exercise was observed in 10 and ST depression in 11 of 12 patients with angina of effort. In patients with spontaneous angina, left ventricular asynergy and ST depression during exercise were observed in 2 of 8 patients without anginal pain, and both patients had coronary artery stenosis of 90% or more. 2) Exercise induced asynergy was also observed in 4 of 7 patients with HCM without coronary artery stenosis. It seemed likely that the markedly hypertrophied myocardium and impairment of left ventricular compliance and relaxation may induce relative myocardial ischemia.

Adult↗
PubMed1982

[Cross-sectional echocardiographic visualization of the infarcted site in myocardial infarction: correlation with electrocardiographic and coronary angiographic findings].

Three dimensional assessment of the site of myocardial infarct was performed using cross-sectional echocardiography in 68 patients with old myocardial infarction. Patients with a history or electrocardiographic findings suggestive of double or multiple infarctions were excluded from the study. In patients with abnormal Q waves in V1 to V3, a regional wall motion abnormality (asynergy) was observed in the anterior portion of the interventricular septum (IVS) and the anterior free wall of the left ventricle (LV) which was extended from the base to apex. Most of them had a significant stenosis in the left anterior descending artery (LAD) distal to the first diagonal branch. Patients with Q waves in V1 to V5 or V6 showed extensive asynergy in the anterior IVS, anterior and lateral free walls of the LV extended from the base to apex. LAD stenosis proximal to the first diagonal branch seemed to be the corresponding coronary lesion. In patients with Q waves in V3 to V5 or V6, asynergy was limited to the apical half of the anterior wall of the LV. In patients with Q waves in II, III and a VF, asynergy was observed in the basal half of the posterior wall and the posterior portion of the IVS.

Coronary Angiography↗
PubMed1981

[Detection of exercise induced left ventricular asynergy by two-dimensional echocardiography (author's transl)].

In order to detect an exercise induced asynergy, cross-sectional echocardiography was performed during multistage maximal bicycle ergometer stress test in the supine position. 1) Left ventricular (LV) asynergy occurred earlier than or simultaneously with the appreciable ST segment change. 2) In patients with angina, LV asynergy appeared in the area of dominant coronary stenosis, while ST depression was seen in V3-6 as well as II, III and aVF, despite of the localized area of asynergy. 3) In patients with myocardial infarction, LV asynergy increased or extended over or around the infarcted area except one case, ST segment elevated in the leads over the infarction with abnormal Q waves and depressed in the reciprocal leads. These observations revealed that ST depression does not necessarily mean an occurrence of new ischemia over the corresponding area in myocardial infarction. Thus exercise cross-sectional echocardiography was demonstrated to be a good method to detect an exercise induced ischemia and would be particularly valuable in view of the coronary artery bypass.

Adult↗
PubMedDate not supplied

Usefulness of p53 protein, Bcl-2 protein and Ki-67 as predictors of chemosensitivity of malignant tumors.

In various types of human malignant tumors, the presence or absence of expression of apoptosis-associated gene products (p53 protein and Bcl-2 protein) and the tumor proliferation activity-related factor (Ki-67) was assessed by immunohistochemical staining and the correlation between this expression and chemosensitivity to anticancer drugs was investigated. Study subjects comprised 55 preoperative patients with untreated malignant tumors (9 with esophageal cancer, 11 with stomach cancer, 11 with colon cancer, 13 with hepatic cancer and 11 with breast cancer). A chemosensitivity test was carried out with the histoculture drug response assay (HDRA) method using 4 drugs, mitomycin C (MMC), 5-fluorouracil (5-FU), doxorubicin hydrochloride (ADM), and cisplatin (CDDP). Immunohistochemical staining was used to assess expression of p53 protein, Bcl-2 protein and Ki-67. The tumor growth inhibition index (I.I.) of the 4 drugs was significantly lower in a group of the patients with p53 protein overexpression-type (mutant p53 protein positive expression-type) tumors than in a group with p53 protein negative expression-type tumors (p<0.05). No significant correlation was found between the expression of the Bcl-2 protein by and the I.I. of any drug studied in any type of cancer. A negative correlation was found between the labeling index (L.I.) for Ki-67 in all cases and I.I. for MMC and ADM and thus, chemosensitivity of the tumors with high growth activity was lower. Furthermore, a positive correlation existed between the L.I. for Ki-67 and that for p53 protein. The patients with p53 protein overexpression-type (mutant p53 protein positive) tumors showed low chemosensitivity. In addition, overexpression of p53 protein is suggested to be one of the factors involved in the lowered chemosensitivity of the tumors with high growth activity. Summarizing these findings, the p53 protein can play an important role in cancer therapy.

Antineoplastic Agents↗