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Biomedical subjects

M Yamaki

Publications and source records attributed to M Yamaki.

At least 145 records · Page 8Linked to original sources
PubMed1988

Three Epstein-Barr virus (EBV)-determined nuclear antigens induced by the BamHI E region of EBV DNA.

In our previous study (Takada et al., 1986a), we showed that the BamHI E fragment of Epstein-Barr virus (EBV) DNA induces a nuclear antigen that is detected by human antisera against EBV-determined nuclear antigen (EBNA), when transfected into baby hamster kidney (BHK) cells. The present study shows that the sub-fragment containing the central open reading frame BERF2b of the BamHI E fragment (Baer et al., 1984) is responsible for nuclear antigen induction. In addition, 2 fragments corresponding to 2 other open reading frames of the BamHI E, BERFI and BERF4 also induce nuclear antigens upon transfection into BHK cells. These 3 antigens, designated RF2b, RFI and RF4 antigens, were serologically classified as EBNA and antigenically distinct. In immunoblotting analysis of latently EBV-infected BJ-B95-8 cells, 3 high-molecular-weight polypeptides (136, 142 and 147 kDa) were identified by anti-EBNA sera. Immunoblotting analysis of transfected BHK cells indicated that the RF2b antigen is 145 kDa in its native form and antigenically related to the 147-kDa protein of BJ-B95-8 cells. Although RFI and RF4 antigens were not detected by immunoblotting, reactivities of sera with RFI and RF4 antigens in the immunofluorescence test were correlated with those of sera with the 136- and 142-kDa polypeptides of BJ-B95-8 cells, respectively. The results suggest that 3 high-molecular-weight proteins of latently EBV-infected cells are encoded by 3 open reading frames of the BamHI E DNA fragment.

Animals↗
PubMed1988

Local conduction delay causes R-wave amplitude increase in patients with effort angina.

Eighty-seven unipolar electrocardiograms distributed over the entire thorax were simulataneously recorded before and after treadmill exercise in 43 patients. Exercise-induced R-wave amplitude change (delta R) and peak R time (time from the onset of QRS to the peak of R wave), were calculated for each lead. The maximal delta R of 87 leads was designated as the max delta R. After exercise, regional delay of peak R time (greater than or equal to 10 msec) on the chest was observed in 13 patients. These patients had significantly higher max delta R than those without such regional peak R time delay (0.71 +/- 0.31mV vs. 0.33 +/- 0.20mV, p less than 0.01). In each case, the site of peak R time delay was almost the same as the site of max delta R. There was no significant difference in the peak heart rate, rise of the systolic blood pressure (delta BPs) during exercise or extent of ischemic ST depression between patients with and without peak R time delay. We concluded that ventricular condition delay plays an important role in the increase of R-wave amplitude after exercise in patients with effort angina pectoris.

Adult↗
PubMed1988

Diagnosis of right ventricular involvement in chronic inferior myocardial infarction by means of body surface QRS changes.

ST segment elevation in right precordial leads is thought to be good predictor of right ventricular involvement in patients with acute inferior myocardial infarction. This view, however, is rapidly disappearing. Therefore, using QRS changes in body surface potential maps in the chronic phase, we have attempted to differentiate patients with or without right ventricular involvement. Thirty patients with chronic inferior myocardial infarction (2 or more months after onset) were studied, in whom 87 unipolar ECGs and right ventriculograms were recorded. The patients were then divided into three groups depending on the locations of their abnormal QRS potentials (-2SD area) exceeding the normal range (mean -2SD). In group A, the -2SD area was located predominantly on the right inferior chest, in group B on the left inferior chest, and in group N on both the right and left inferior chests equally. The results showed that group A had a lower right ventricular ejection fraction (RVEF) compared with group B (A, 40 +/- 7%; B, 53 +/- 10%; p less than .001), while there was no difference in left ventricular ejection fraction between the two groups (49 +/- 11% and 49 +/- 11%, respectively). Moreover, right ventricular asynergy occurred in 14 of the 18 patients (78%) of group A but in only one of the 10 patients (10%) of group B. Group N was presumed to be intermediate between groups A and B.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1988

Analysis of photo-initiators in visible-light-cured dental composite resins.

Seven commercial visible-light-cured (VL) dental composite resins were analytically studied for identification of the photo-initiator consisting of photo-sensitizer and reducing agent. Gas-liquid chromatography (GC) was used for the determination of the dilute components extracted from the composite resin. Mass spectroscopy (GC-MS) was used for confirmation of the qualitative data obtained by GC. The results showed that all composite resins examined included camphorquinone (CQ) as a photo-sensitizer. The concentration of CQ in the resin phase, however, ranged from 0.17 to 1.03% w/w. The composite resin with hybrid-sized filler tended to have a higher concentration of CQ than did the micro-filled composite resin. As for the reducing agent, two out of seven brands contained dimethylaminoethyl methacrylate (DMAEMA), and one included dimethyl-p-toluidine (DMPTI). The mixing ratio between CQ and the amine in these three composite resins also varied. Another four brands did not contain either DMAEMA or DMPTI, and would utilize different reducing agents.

Chromatography, Gas↗
PubMed1988

Studies on iridoid-related compounds. V. Antitumor activity of iridoid dervs. periodate oxidation products.

In the course of a modification study of iridoid glucosides to investigate their antitumor and antimicrobial activity, we found that about all metaperiodate oxidation products of iridoid glucosides which had no antitumor activity showed potent activity against the leukemia P388 in mice. They were found to be more active than the corresponding aglycones obtained by enzymic hydrolysis of iridoid glucosides. Among them, periodate oxidation product of sweroside showed the most potent activity, of which the maximum total/control (T/C) value was 198% at 200 mg/kg.

Animals↗
PubMed1988

Clinical significance of body surface isochrone maps for predicting ventricular arrhythmias in patients with previous myocardial infarction.

To investigate the utility of body surface isochrone maps for estimating ventricular arrhythmias in patients with previous myocardial infarction, we compared findings of body surface isochrone maps with those of signal-averaged electrocardiograms (SAECGs) and an incidence of ventricular tachycardia (VT). Body surface isochrone mapping was performed in 50 patients with previous myocardial infarction. Eighty-seven unipolar electrocardiograms distributed over the patient's anterior chest and back were recorded simultaneously. For each lead, the activation time was measured as the duration from the onset of QRS to the peak of the R wave. SAECGs were recorded in the same patients to detect late potential (LP) which was considered to last more than 30 msec. Activation delay on isochrone maps (D) was found in 31 of 50 patients. The group D+ had a lower ejection fraction and higher incidence of VT (8/31 (25.8%) vs. 1/19 (5.3%)) and LP (13/31 (41.9%) vs. 2/19 (10.5%)) than the group D-. There were four patients with sustained VT who had both D and LP. For predicting VT, D has a sensitivity of 88.9% and a specificity of 43.8%. It was decided that abnormal delay on body surface isochrone maps indicates slow conduction of the surviving myocardium and is related to the occurrence of ventricular arrhythmias. We concluded that body surface isochrone maps can be useful in predicting life-threatening arrhythmias in patients with previous myocardial infarction.

Aged↗
PubMed1988

[Laboratory and clinical studies on cefotetan in respiratory tract infections].

Seventy five patients with respiratory infections, including 40 cases of acute pneumonia, 33 cases of secondary infection after chronic pulmonary diseases and 2 cases of pulmonary abscess, were treated with cefotetan (CTT, Yamatetan) by drip infusion in order to evaluate its clinical efficacy. The overall rate of effectiveness was 83.8%. CTT was examined comparatively with other beta-lactam antibiotics for antibacterial activity on clinically isolated strains of 3 major respiratory pathogens including Haemophilus influenzae, Branhamella catarrhalis and Streptococcus pneumoniae. Minimum inhibitory concentrations (MIC's) of CTT on H. influenzae were less than 3.13 micrograms/ml regardless of the production of beta-lactamase by these organisms. As to B. catarrhalis, CTT also exerted an antibacterial activity enough to control the proliferation of all the strains at a level of 1.56 micrograms/ml. Against S. pneumoniae, on the other hand, CTT exhibited the lowest activity of all the drugs tested but still showed MIC's of 3.13 micrograms/ml or less. Drip infusion of CTT at a dose of 2 g brought about an average maximum blood concentration of 342 +/- 25.7 micrograms/ml and an average half-life in blood of 2.48 +/- 0.41 hours Maximum sputum concentration of the drug, however, was variable among the cases tested, ranging from 0.40 to 1.80 micrograms/ml. Side effects of the drug were observed in 5 cases or 6.7%. Four of them had some allergic symptoms; i.e., pyrexia and eruption. One patient was especially diagnosed as possible drug-induced interstitial pneumonia during the treatment with the drug. The diagnosis was confirmed by transbronchial lung biopsy and lymphocyte blastogenesis by CTT in vitro. As to abnormal laboratory findings, blood transaminases were elevated during drug administration in 13 cases or 17.3%, but were reduced back to the normal level after the withdrawal of the drug.

Adult↗
PubMed1987

ST segment changes in exercise body surface mapping after myocardial infarction in patients with isolated left anterior descending coronary artery disease.

To investigate the clinical significance of exercise-induced ST segment elevation and ST segment depression after myocardial infarction (MI), we performed 87-lead ECG mapping after previous anterior infarction in 24 patients with isolated left anterior descending coronary artery disease before and 1.5 minutes after treadmill exercise. Thirteen patients showed ST segment elevation only, seven patients showed both ST segment elevation and depression, and four patients showed ST segment depression only. ST segment elevation most frequently occurred in the left anterior chest leads corresponding to the QS area, and ST segment depression developed in the left lower chest and left lower back leads. There was good correlation between the number of lead points showing ST segment elevation (nSTe) after exercise and the number of lead points showing QS waves (nQS) before exercise (r = 0.65). nSTe was also correlated with the asynergy index (r = 0.43). These findings suggest that ST segment elevation is mainly the result of aggravation of wall motion abnormalities of the infarcted myocardium. Body surface distribution of ST segment depression was similar to that in effort angina pectoris without MI. We conclude that exercise-induced ST segment depression in MI mainly reflects the ischemia of the surviving myocardium of small infarcts or the peripheral area of large infarcts.

Adult↗
PubMed1987

Temporal changes in body surface peak R isochrone maps and left ventricular function in patients with myocardial infarction.

Body surface peak R isochrone mapping and radionuclide ventriculography were performed twice in 22 patients with myocardial infarction. Eighty-seven unipolar electrocardiograms distributed over the anterior chest and the back were recorded simultaneously. For each lead, the time from the onset of QRS to the peak of the R wave was measured. From this data for 87 leads an isochrone map was constructed. The lead points where R waves were not observed were designated the no R-wave area (No-R area), which was postulated to correspond to the unexcited regional myocardium. Other abnormal findings, i.e., delay of peak R time near the No-R area (peri-No-R area delay), crowding of isochrone lines, and an island-like zone of delayed peak R times were postulated to indicate slow conduction in the partially excited regional myocardium. In three patients, abnormal patterns in the peak R isochrone maps during the acute phase (within a month from the onset of myocardial infarction) improved in the chronic phase with a significant increase in left ventricular ejection fraction. In two patients, the No-R area decreased after the left ventricular aneurysmectomy. In other patients, abnormal patterns of the isochrone maps and the ejection fraction remained unchanged during the chronic phase of myocardial infarction. We conclude that the comparison of peak R isochrone map patterns between the acute and chronic phase may be useful in evaluating the balance of reversible and irreversible regional damage in myocardial infarction.

Electrocardiography↗
PubMed1987

Inhibition of dipyridamole-induced myocardial ischemia by diltiazem in patients with coronary artery disease.

We investigated the effect of diltiazem on dipyridamole-induced myocardial ischemia in eight patients with coronary artery disease. Dipyridamole was infused at a rate of 0.142 mg/kg/min for 4 min, and 87-lead mapping was performed to determine the number of leads with ischemic ST-segment depression greater than or equal to 0.05 mV (nST). The range of nST was 8-24 (mean, 13.8) in the control study. Of eight patients studied, a single dose of 90 mg diltiazem administered 3 h before dipyridamole infusion inhibited dipyridamole-induced ST-segment depression completely in seven (nST = 0) and incompletely in one (nST = from 24 to 5). It was concluded that diltiazem could suppress the myocardial ischemia following dipyridamole infusion.

Aged↗
PubMed1987

Molecular characterization of novel reciprocal translocation t(6;14) in an Epstein-Barr virus-transformed B cell precursor.

An in vitro culture of FLEB14 cells, an Epstein-Barr virus-transformed B cell precursor containing the germ line immunoglobulin genes, gave rise to a uniclonally expanded variant, FLEB14 delta 3, which was rearranged at the immunoglobulin heavy-chain gene locus. Cytogenetic analysis showed that FLEB14 delta 3 had a novel reciprocal translocation, t(6;14)(q15;q32). Molecular cloning of the rearranged DNA fragments and determination of their nucleotide sequence revealed that the recombination event was reciprocal, imprecise, and nonhomologous and took place in the S mu region, like those found in Burkitt's lymphoma cells. We propose a molecular model to explain this genetic event which may be relevant to class switch recombination. The translocated sequence of chromosome 6 did not contain any known oncogenes, although the sequence is conserved among mammals. FLEB14 delta 3 did not show tumorigenicity.

B-Lymphocytes↗
PubMed1987

The body surface distribution of the QT interval in patients with previous myocardial infarction and normal subjects.

In spite of the clinical importance of the QT interval, its body surface distribution is still unclear. To determine the spatial distribution of the QT interval, we studied 20 normal subjects and 45 patients with previous myocardial infarction (25, anterior; 20, infero-posterior). Unipolar electrocardiograms were recorded from 87 torso sites. The QT interval in each lead was determined semi-automatically. In normal subjects, the longer QT intervals were located on the left anterior chest and the right shoulder portion. And, the relatively shorter QT intervals were shown on the right inferior chest. In the anterior MI group, the remarkably longer QT intervals were located on the left anterior chest. In the infero-posterior MI group, the longer QT intervals were found on the left lateral and back. In both MI groups, the sites of longer QT intervals corresponded to the sites of infarcted area. In the aneurysm (+) subgroup of the anterior MI group, the remarkably longer QT intervals could be found on the left anterior chest, while in the aneurysm (-) subgroup, these characteristic patterns could not be recognized. Our data suggest that QT intervals are not equal on a torso. In patients with myocardial infarction, the sites of prolonged QT intervals corresponded to the sites of infarcted area. The QT interval was thought to have some bearing on the abnormal repolarization of the residual myocardium in the infarcted area.

Aneurysm↗
PubMed1987

Body surface mapping for the assessment of left ventricular hypertrophy in patients with essential hypertension.

To investigate the electrocardiographic abnormalities of left ventricular hypertrophy (LVH), body surface potential maps were acquired from 42 patients with essential hypertension. We adopted the time integral technique for analyzing body surface mapping data and used echocardiographic left ventricular muscle mass (LV mass) as the index of advance of LVH. The QRS, ST-T and QRST isointegral maps in normal volunteers all demonstrated smooth bipolar surface distribution patterns, with positive values located over the precordium and negative values over the right upper chest and back. In patients with essential hypertension, changes in the isointegral maps were observed as LVH advanced; A QRS increased on the upper left lateral chest and decreased (became more negative) on the right chest, A ST-T decreased on the lower left lateral chest and increased on the right upper chest, and areas of significant difference in A QRS and A ST-T were expanded as LVH advanced. A QRST decreased on the lower left lateral chest and increased on the right upper chest only in patients with severe LVH. We conclude that the changes of QRS and ST-T isointegral maps depend on the degree of advance of LVH and the severe grade of LVH causes the alterations in intrinsic repolarization properties.

Adult↗
PubMed1986

Non-invasive detection of coronary artery disease by body surface electrocardiographic mapping after dipyridamole infusion.

Electrocardiographic changes after dipyridamole infusion (0.568 mg/kg/4 min) were studied in 41 patients with coronary artery disease and compared with those after submaximal treadmill exercise by use of the body surface mapping technique. Patients were divided into three groups; 19 patients without myocardial infarction (non-MI group), 14 with anterior infarction (ANT-MI) and eight with inferior infarction (INF-MI). Eighty-seven unipolar electrocardiograms (ECGs) distributed over the entire thoracic surface were simultaneously recorded. After dipyridamole, ischemic ST-segment depression (0.05 mV or more) was observed in 84% of the non-MI group, 29% of the ANT-MI group, 63% of the INF-MI group and 61% of the total population. Exercise-induced ST depression was observed in 84% of the non-MI group, 43% of the ANT-MI group, 38% of the INF-MI group and 61% of the total. For individual patients, there were no obvious differences between the body surface distribution of ST depression in both tests. The increase in pressure rate product after dipyridamole was significantly less than that during the treadmill exercise. The data suggest that the dipyridamole-induced myocardial ischemia is caused by the inhomogenous distribution of myocardial blood flow. We conclude that the dipyridamole ECG test is as useful as the exercise ECG test for the assessment of coronary artery disease.

Adult↗