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Biomedical subjects

S Yasui

Publications and source records attributed to S Yasui.

At least 163 records · Page 9Linked to original sources
PubMed1986

[Severity and extent of coronary artery disease and their relationship to left ventricular functional reserve in the chronic disease state].

Our previous observations showed that left ventricular wall motion abnormality (asynergy) induced by stress was observed in the phase response of radionuclide technique, and the severity and extent of coronary artery disease (CAD) assessed by the Pujadas score (PS) correlated well with the maximal phase delay response (delta MPD) but not with the ejection fraction response (delta EF) in patients with CAD without old myocardial infarction (MI). This study evaluated the usefulness of EF, MPD and the first-third filling fraction (FF, divided by the volume accrued throughout diastole) at rest and during stress, using ergometer and first-pass radionuclide angiocardiography (RNA), to determine the severity of CAD, and to evaluate any abnormalities in the systolic and diastolic coupling in left ventricular function during stress. Seventy-four patients with significant CAD, including 41 with previous transmural MI (MI group) and 33 without MI (angina group) were the subjects of this study. EF at rest and during stress inversely correlated, and MPD on stress linearly correlated with PS in angina group with PS greater than 10, while no such correlations were found in MI group. A normal EF response (delta EF greater than or equal to 5%) was accompanied by a greater-than-normal response in FF (delta FF) in both groups. A lower EF response was accompanied by a smaller delta FF in angina group, but by a larger delta FF in MI group. The difference was statistically significant (p less than 0.03), without significant differences by age, PS, peak heart rate, systolic blood pressure, and ischemia on ECG during stress. Resting EF and FF by the RNA method correlated with those by left ventriculography (LVG), respectively. It was suggested that RNA is an accurate method for determining EF and FF, while phase analysis may provide some additional information different from that provided by LVG. We concluded that EF and MPD during stress are as useful as delta MPD with the exception of a few cases in predicting the severity of CAD, and that scar tissue within the ventricular wall in MI may play an important role in determining the ventricular diastolic mechanical property during stress.

Angina Pectoris↗
PubMed1985

GABA activates different types of chloride-conducting receptor-ionophore complexes in a dose-dependent manner.

We report here evidence for 3 new subtypes (alpha 1, alpha 2 and beta) of type-A GABA receptor-channel complexes that conduct chloride ions. The chloride current, ICl, was isolated in the frog sensory neuron by a combination of voltage clamp and internal perfusion. Analysis of the variance of GABA-induced ICl fluctuations shows that the channel population N decreases exponentially with single-channel conductance gamma in such a way that alpha 2 less than alpha 1 less than beta for gamma and alpha 2 much greater than alpha 1 greater than beta for N, and that the population-rank plot fits Zipf's law. Various aspects of the GABA-induced ICl are understood from dose-dependent activation and inactivation of these functionally distinct receptor-channel types. The steady-state ICl is mediated by alpha 1 at low but by beta units at high GABA concentrations, and the pronounced ICl peak at intermediate and high doses reflects the desensitization of alpha 1 and alpha 2 receptors, respectively. Picrotoxin blocks alpha 1 and alpha 2 and has no effect on beta channels. Patch-clamp recordings indicate two distinct classes of GABA-gated chloride conductances that appear to correspond to the alpha 1 and beta types. The presence of these different ICl components explains why the dose-response relationship cannot be fitted well by a single Hill equation; the fitting requires a synthesis of 3 suitable Hill equations.

Animals↗
PubMed1985

Monomolecular surface film and tubular myelin figures of the pulmonary surfactant in hamster lung.

Perfusion fixation via pulmonary trunk was applied to the alveolar lining layer in situ at different lung volumes using a fixative containing tannic acid-ferrocyanide osmium. The monomolecular surface film and hypophasic tubular myelin figures were enhanced. In the range of transpulmonary pressure (1-10 cmH2O), the surface film appeared in the form of a single, electron-dense leaflet, 2.7 +/- 0.6 nm (M +/- SD) in thickness while trilaminar membrane structure was retained in all parts of the tubular myelin figures of the hypophase. The surface film was attached underneath at right angles with trilaminar membranes which formed the outermost parts of the tubular myelin. Such structural continuity was taken to support a view that the phospholipid unit membrane of the tubular myelin figure would be transformed at the hydrophobic phase into a pair of monomolecular leaflets, eventually forming the surface film.

Animals↗
PubMed1985

Improvement of data acquisition and analysis to evaluate regional ventilation.

To evaluate the regional ventilation using 133Xe under different conditions, the respiratory flow and the phase with image were measured simultaneously, and sequential frames were made breath by breath. The flow signal and phase signal were converted to pulse signals by a microcomputer and stored with image data in the same file. Thus, the tidal volume and duration of each breath were measured. From sequential frames compiled breath by breath, an activity breath-number curve was made in each pixel, and the half-clearance breath number (B1/2) was calculated. The changes in conventional half-clearance time (T1/2) and B1/2 were compared under different ventilatory conditions in normal subjects and in patients with chronic pulmonary emphysema. Values of B1/2 indicated the change of turnover rate more accurately than T1/2. It is considered that B1/2 is a better parameter than T1/2 for evaluating the change in regional ventilatory function under different conditions.

Analog-Digital Conversion↗
PubMed1985

Hyperkinetic contraction of a nonischemic segment of ischemic left ventricle in anesthetized dogs.

Regional myocardial function during acute coronary artery occlusion was studied with ultrasonic dimension gauges in 20 open-chest anesthetized dogs. Two pairs of ultrasonic crystals were implanted in the left ventricular free wall near the epicardium in an ischemic segment and in a control nonischemic segment, and the segment length (SL) and maximum velocity of systolic shortening (max dL/dt) were measured. In six dogs, the wall thickness (WT) was measured simultaneously in the same regions with sonomicrometry. Left ventricular pressure (LVP), aortic pressure (AoP), and plasma norepinephrine concentration in the coronary sinus (NECS) were also measured. The heart rate was kept constant (180 beats/min) with atrial pacing. The left anterior descending coronary artery was occluded at its distal portion without propranolol in 12 dogs (group 1) and 30 min after propranolol in eight dogs (group 2). In the ischemic region, coronary artery occlusion resulted in an increase in end-diastolic SL (50% at 3 min after occlusion in group 1, P less than 0.005), and a decrease in max dL/dt in systole (36% at 5 min after occlusion in group 1, P less than 0.02). In the nonischemic region, end-diastolic SL did not change significantly, but an increase in max dL/dt (29% at 10 min after occlusion in group 1, P less than 0.005) was observed in systole. Under propranolol (group 2), the results were similar to those of group 1. There were no significant changes in LVP, AoP, AoP, and NECS during occlusion.(ABSTRACT TRUNCATED AT 250 WORDS)

Anesthesia, Intravenous↗
PubMed1985

Body surface distributions of ST segment changes after exercise in effort angina pectoris without myocardial infarction.

To investigate the sites of exercise-induced ST segment changes on the body surface in effort angina pectoris without myocardial infarction, we performed 87-lead ECG mapping in 61 patients before and 1.5 and 5 minutes after treadmill exercise. ST segment depression most often occurred in the left anterior chest leads and ST segment elevation developed mainly in the right upper chest leads. There was a good correlation between the number of lead points that showed ST segment depression (nSTd) and the number of those that showed ST segment elevation (nSTe) 1.5 minutes after exercise (r = 0.92). From 1.5 to 5 minutes after exercise, changes in nSTd for individual patients correlated well with changes in nSTe (r = 0.89). It was suggested that the ST segment elevation observed in this study directly reflected the subendocardial ischemia of the left ventricle. In patients with one-vessel disease (n = 32), there was wide overlap in the sites of ST segment changes among patients with left anterior descending artery disease (n = 19), those with left circumflex artery disease (n = 6), and those with right coronary artery disease (n = 7). These findings should lead to a better understanding of exercise-induced ST segment changes for the diagnosis of coronary artery disease.

Adult↗
PubMed1985

Noninvasive assessment of left ventricular wall motion abnormalities by QRS isointegral maps in previous anterior infarction.

In order to determine to what extent left ventriculographic abnormalities can be predicted from ECG changes in myocardial infarction (MI), 87 unipolar ECGs were simultaneously recorded in 22 patients with previous anterior MI with no conduction defects. We adopted a QRS isointegral mapping technique for analyzing body surface mapping data. Particular attention was given to the area where the QRS time-integral value was less than the lower limit (mean minus two standard deviations) of the normal, and this area was designated as the departure area. Left ventricular wall motion was assessed by left ventriculography and correlated with the departure area. The departure area demonstrated a close correlation with the left ventricular ejection fraction (r = -0.93) and the extent of asynergy (r = 0.74). It is suggested that the departure area reflects the loss of electromotive force due to MI. We conclude from this study that the QRS isointegral map is a useful method for evaluating left ventricular function in patients with anterior MI.

Adult↗
PubMed1985

Detection of posterior myocardial infarction by body surface mapping: a comparative study with 12 lead ECG and VCG.

To examine the diagnostic ability of body surface mapping in posterior myocardial infarction (PMI), mapping was performed in 11 patients with PMI proven by left ventriculography and T1-201 myocardial perfusion imaging (PMI group) and in 44 normal subjects (N group). Map data was analysed by the following methods: (1) potential departure maps at 10, 20, 30, 40 and 50 msec after the onset of QRS; each map indicates the area of decreased potential out of the normal range at the time. (2) AQRS departure map which indicates the area of decreased time-integral value of QRS out of the normal range. True positive (TP) in the PMI group and false positive (FP) in the N group were calculated for each method, and were compared with those of various criteria for PMI with standard 12-lead electrocardiogram (ECG) and Frank lead vectorcardiogram (VCG). The potential departure maps and the AQRS departure map had high TP (10/11 and 8/11) and low FP (0/44 and 0/44). The diagnostic ability of mapping is considered to be higher than that of ECG and VCG. Mapping, especially the departure map technique, is a sensitive and specific method to detect posterior infarction.

Electrocardiography↗
PubMed1985

P-wave changes in obstructive and restrictive lung diseases.

To evaluate the P wave changes in the electrocardiogram (ECG) in chronic lung diseases, we examined ECGs from twenty patients with interstitial pulmonary fibrosis (the FLD group) and twenty patients with chronic obstructive lung disease (fifteen with pulmonary emphysema and five with bronchial asthma, the COLD group). In the COLD group, the amplitude of P waves in leads II and III increased and the axis of the P wave shifted rightward. In the FLD group, however, these changes were not observed. Furthermore, the axis of the P wave exceeded +70 degrees in all the patients in the COLD group, and was less than +70 degrees for all the patients in the FLD group. The increased P wave terminal force in lead V1 was found in nine patients (45%) of the FLD group and in ten patients (50%) in the COLD group. We concluded that the rightward shift of the axis of the P wave was a characteristic of obstructive lung disease and that it was mainly caused by the overinflation of the lung. This P wave change was not observed in interstitial pulmonary fibrosis.

Adult↗
PubMed1985

Detection of local abnormalities in ventricular activation sequence by body surface isochrone mapping in patients with previous myocardial infarction.

Body surface isochrone mapping was performed in 36 normal subjects and in 85 patients with previous myocardial infarction. Eighty-seven unipolar electrocardiograms distributed over the anterior chest and the back were recorded simultaneously. For each lead, activation time was measured as the time from the onset of QRS to the peak of the R wave. The lead points where R waves were not observed were designated the "no R wave area" (NR area). Isochrone maps of normal subjects had a consistent pattern, with isochrone lines extending from the right upper anterior chest to the left anterior chest and then to the back. NR area was small and was located only on the right upper chest or the upper back. On the isochrone maps of patients with myocardial infarction, abnormal findings were observed; NR area was found in 26 of 28 patients with anterior infarction on the upper to middle anterior chest, in 13 of 22 patients with inferior infarction on the lower chest, and in 24 of 25 patients with anterior and inferior infarction on the upper to lower anterior chest. Activation time was delayed near the NR area (peri-NR area delay) in 37 patients. In patients with apical infarction, an islandlike zone of delayed activation was typically found on the left precordium. These abnormal patterns are considered to indicate local abnormalities in the activation of infarcted myocardium; the NR area indicates dead unexcitable scar, and the peri-NR area delay and islandlike zone of delayed activation indicate partially infarcted myocardium of slow activation. Patients with NR area had greater degree of left ventricular asynergy and lower ejection fraction than those without.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1985

Effects of lung volume on body surface electrocardiogram. Isointegral analysis of body surface maps in patients with chronic pulmonary emphysema.

To evaluate the effects of lung volume changes on the body surface electrocardiogram, we performed body surface potential mapping (87 lead points) in 20 normal subjects (group N) and in 21 patients with chronic pulmonary emphysema (group CPE). P-wave, QRS, ST-segment, ST-T and QRST iso-integral maps were constructed. Group-mean maps and the mean value of the maximum (max) and the minimum (min) on each map were compared between group N and group CPE. In group CPE, the body surface distribution of the P, QRS, ST, ST-T and QRST time integrals were all positioned downwards compared with those of group N. In addition, we also detected an increase in the max of P and decreases in the min of P; max and min of QRS; and in max of ST-T and QRST integrals. It was suggested that these changes were caused by the downward shift and clockwise rotation of the heart, and also by the decreased electrical conductivity of the lungs.

Adult↗
PubMed1985

Diagnosis of coronary artery disease by body surface mapping--body surface distribution of exercise-induced ST changes in patients without myocardial infarction.

In 36 patients with effort angina pectoris without myocardial infarction, the sites of exercise-induced ST changes (depression and elevation) on the body surface were investigated. Exercise-induced ST depression was most often seen in left anterior chest leads. The body surface distribution of ST depression failed to identify the obstructed coronary artery. Exercise-induced myocardial ischemia was thought to extend to the greater part of the subendocardial region of the left ventricle. Exercise-induced ST elevation was mainly found on the upper right anterior chest. It has been suggested that these leads face the interior of the left ventricle and the observed ST elevation directly reflects subendocardial ischemia of the left ventricle. This data is important for evaluating ST changes in exercise electrocardiography.

Coronary Disease↗
PubMed1985

The clinical significance of exercise-induced ST-segment elevation in previous anterior myocardial infarction.

To investigate the mechanism of exercise-induced ST elevation in previous anterior myocardial infarction, exercise body surface mapping was performed on 22 patients with anterior myocardial infarction. ST elevation was compared with the findings of exercise radionuclide ventriculography and exercise thallium-201 myocardial perfusion imaging. ST-segment was quantified by the integral of ST-segment voltage. The maximal value of ST segment integral out of the 87 leads on the body surface was defined as ST max. The percent of change in ST max after exercise was closely correlated to the decrease in ejection fraction (r = 0.76). Furthermore, 9 of the 12 patients with increased ST max after exercise had exercise-induced regional wall motion abnormalities mainly in the apical and anterolateral segments, while other 10 patients without increased ST max did not (p less than 0.01). There was no difference in % change of ST max a) between anterior reversible defect (+) group and the (-) group; b) between inferior reversible defect (+) group and the (-) group; c) between single vessel (isolated left anterior descending artery stenosis) group and the multivessel group. This fact indicated that exercise-induced ST elevation did not result from the exercise-induced myocardial ischemia of the infarctional segment or the remote non-infarctional segment. We concluded that exercise-induced ST elevation in previous anterior myocardial infarction is mainly due to the aggravation of anterior wall motion abnormalities induced by exercise.

Adult↗
PubMed1985

[Monthly changes in serum alpha 2-globulin and immunoglobulin levels in chronic hemodialysis patients--with special reference to the occurrence of cancer and blood transfusion].

Thirty-eight patients with chronic renal failure who were treated by hemodialysis more than 100 times each, including 13 cancer patients, were examined for serum alpha 2-globulin and immunoglobulin values monthly, the relationship between the possibility of cancer occurrence and the frequency of blood transfusion during hemodialysis was discussed. The alpha 2-globulin value of the patients treated with blood transfusion more than 20 times was significantly higher than that of the patients not receiving blood transfusion. Moreover, the IgA value was reduced and the IgM value was increased. The IgA values of cancer patients found before or during hemodialysis were significantly higher than those of patients without cancer. There was no significant difference between the group who had undergone hemodialysis more than 500 times those who had received it less than 500 times.

Adult↗
PubMed1985

Acute effects of nifedipine on patients with chronic obstructive lung disease.

The bronchodilatory effect of nifedipine (Adalat) and the change of arterial blood gas in 5 normal and 25 patients with chronic obstructive lung disease (COLD) were investigated. 10 or 20 mg of nifedipine was orally administered. Before and 2 h after the administration, blood pressure (BP), heart rate (HR), arterial blood gas, respiratory resistance (Rrs) were measured and spirometry was assessed. Decrease of BP and increase of HR were observed in both normal and patient group. The patient group showed an increase of forced vital capacity (FVC) by 150 ml and forced expiratory volume (FEV 1.0) by 140 ml in average. In spite of the improvement of spirometry and Rrs, delta AaPO2 (alveolar arterial oxygen pressure difference) was increased in the patient group. It was considered, that the effect on the cardiovascular system was more remarkable than the bronchodilation, and the use of the drug alone as a bronchodilator may not be appropriate. It may be particularly effective in the cases with cardiovascular disease complicated with COLD.

Adult↗