Search PubMed⌕ Search

Biomedical subjects

J Yoshikawa

Publications and source records attributed to J Yoshikawa.

At least 217 records · Page 12Linked to original sources
PubMed1997

Changes in plasma cardiac natriuretic peptides concentrations during 1 year treatment with angiotensin-converting enzyme inhibitor in elderly hypertensive patients with left ventricular hypertrophy.

Plasma concentrations of atrial and brain natriuretic peptides (ANP and BNP) are high in patients with hypertension and congestive heart failure. The present study examined changes in plasma ANP and BNP concentrations during 1 year of monotherapy with enalapril in elderly hypertensive patients with left ventricular (LV) hypertrophy. Eight elderly hypertensive patients with LV hypertrophy were treated with enalapril for 1 year, during which time serial changes were recorded in LV mass index, LV systolic function, and plasma concentrations of ANP and BNP. Enalapril maintained systolic and diastolic blood pressure in the normal range for over 1 year. Treatment significantly reduced posterior wall thickness at 6 months, and more so at 1 year, and tended to reduce septal wall thickness and LV mass index at 1 year. LV ejection fraction was slightly but significantly increased at 1 year. Plasma ANP and BNP, which were markedly elevated at study entry, both decreased after 1 year of enalapril. These results suggest that 1 year of treatment with enalapril caused both a modest regression of LV hypertrophy and a modest improvement in LV systolic function in our selected group of elderly hypertensive patients. The drug reduced elevated plasma ANP and BNP levels but did not alter BUN and serum creatinine levels. Enalapril appears to be useful for the treatment of elderly hypertensive patients with LV hypertrophy.

Aged↗
PubMed1997

Three-dimensional echocardiographic evaluation of configuration and dynamics of the mitral annulus in patients fitted with an annuloplasty ring.

BACKGROUND AND AIMS OF THE STUDY: Three-dimensional (3D) echocardiography permits the objective analysis of structures and of pathologic conditions of complex geometry. Multiplane transesophageal echocardiography (TEE) permits 3D image sets of the heart to be produced from multiple 2D images by rotating the transducer, without changing its position. The purpose of this study was to clarify the capability of 3D echocardiography to evaluate the configuration and dynamics of the mitral annulus in patients fitted with an annuloplasty ring. METHODS: Twenty patients who underwent mitral valve repair for pure mitral regurgitation (10 with a flexible Duran ring and 10 with a rigid Carpentier ring) were studied. Using a multiplane transesophageal probe, sequential tomographic images were obtained by rotating the transducer at 2 degrees angular intervals around a 180 degrees arc. 3D reconstructions were performed to produce dynamic 3D images of the mitral annulus in a manner that simulated visualization from the left atrium. Mitral annular configuration was assessed from volume-rendered display and extractive 3D imaging. Mitral annular area change was evaluated from selected long-axis cut planes. RESULTS: The configuration and dynamics of the mitral annulus were visualized by 3D displays. In patients with a Duran ring, the mitral annulus had a non-planar configuration and mitral annular area changed during cardiac cycle (increased in diastole; reduced in atrial and ventricular systole; percentage reduction 25 +/- 2%). In patients with a Carpentier ring, the mitral annulus had a planar configuration and mitral annular area was effectively unchanged during the cardiac cycle. CONCLUSIONS: 3D echocardiography using a multiplane transesophageal probe is useful in evaluating the configuration and dynamics of the mitral annulus in patients fitted with an annuloplasty ring.

Adult↗
PubMed1997

[Evaluation of left ventricular ejection fraction using an automated contour tracking method: comparison with equilibrium radionuclide angiography].

A recently developed contour tracking method provides automated edge detection of left ventricular endocardium without a region of interest. The accuracy of this automated contour tracking (ACT) method in the evaluation of left ventricular ejection fraction was assessed in 20 patients (16 males and 4 females, mean age 58 years) using both the ACT method and equilibrium radionuclide angiography. Ejection fractions measured by the ACT method correlated well with those measured by equilibrium radionuclide angiography (y = 0.8x + 11.9, r = 0.91, SEE = 4.0%, p < 0.01). The ACT method provides an accurate estimate of left ventricular ejection fraction.

Echocardiography↗
PubMed1997

[Transthoracic digital color Doppler assessment of the left anterior descending coronary artery and intramyocardial blood flow].

Noninvasive assessment of the distal left anterior descending coronary artery and intramyocardial blood flow were attempted in 50 consecutive patients (28 males and 22 females, mean age [+/-SD] 58 +/- 12 years) using a 7.5 MHz transducer (Doppler frequency: 5 MHz) and a SSA-380A ultrasound digital system with special optimal settings for the color Doppler examination. Modified apical acoustic windows were used to visualize the blood flow in the distal left anterior descending coronary artery and the intramyocardial artery. By selecting a sample volume (2 mm wide) on the color trace of these blood flows, Doppler spectral tracing of the distal left anterior descending coronary artery and intramyocardial blood flows could be recorded using pulsed-wave Doppler system. Blood flow in the distal left anterior descending coronary artery was detected in 43 (86%, Vmax = 22 +/- 8.7 cm/sec, Vmean = 16 +/- 5.1 cm/sec) of 50 patients, and intramyocardial blood flow in 40 (80%, Vmax = 26 +/- 11.0 cm/sec, Vmean = 19 +/- 8.5 cm/sec) of 50 patients. Distal left anterior descending coronary artery and the intramyocardial blood flows can be imaged by transthoracic digital color Doppler echocardiography in the clinical setting.

Coronary Circulation↗
PubMed1997

[Measurement of plaque volume using three-dimensional intravascular ultrasound: in vitro study].

The usefulness of three-dimensional echocardiography using intravascular ultrasound (3D-IVUS) for the measurement of plaque volume was evaluated by comparing plaque volume derived from 3D-IVUS with that directly measured in 10 autopsied iliac or femoral plaque models (5-15 mm long). Using IVUS (3.5 F, 30 MHz), sequential cross-sectional images for three-dimensional datasets were acquired with a motorized catheter pullback device connected to the three-dimensional reconstruction system. Three-dimensional reconstruction was performed from the sum of the two-dimensional cross-sectional views. Plaque volumes were calculated using a summation of disks algorithm based on the reconstructed multiple short-axis cross-sections from the three-dimensional data. Three-dimensional IVUS demonstrated a good correlation with direct measurement of plaque volume (y = 0.71x + 0.001, r = 0.80, SEE = 0.003 ml), so is useful for the measurement of plaque volumes in the experimental models.

Arteriosclerosis↗
PubMed1997

[Relationship between exercise-induced hypoxemia and long-term survival in patients with chronic obstructive pulmonary disease].

In patients with chronic obstructive pulmonary disease (COPD), exercise-induced hypoxemia (EIH) is an important limiting factor of exercise performance, but there are very few reports of the prognostic value of EIH. We therefore examined whether EIH is related to long-term outcome in patients with COPD. We gathered data on survival of 77 patients with COPD who had undergone three-minute incremental treadmill exercise tests between 1979 and 1988. A plastic catheter was placed percutaneously into a brachial artery to measure arterial blood gases at each stage of exercise. Expired gas was analyzed continuously during exercise with a Respiromonitor RM-300 (Minato Medical Science). As an index of the severity of EIH we used the delta PaO2/delta VO2 (mmHg/L/min), PaO2-slope. Patients were assigned to two groups according to PaO2-slope, and actuarial survival curves were plotted for the two groups. The survival data were analyzed by generalized Wilcoxon analysis. Survival was significantly better in the group with low PaO2-slopes (< 20 mmHg/L/min) than in the group with high PaO2-slopes (> or = 20 mmHg/ L/min) (p = 0.0031). Also, among the patients in whom PaO2 during exercise was less than 60 mmHg, there was a significant difference in survival between those who received home oxygen therapy and those who did not. We conclude that the degree of EIH can be used to predict survival in patients with COPD, and that the degree of EIH should be considered when prescribing continuous home oxygen therapy for these patients.

Aged↗
PubMed1997

[Phasic coronary flow velocity pattern characteristics of myocardial bridging: a Doppler guide wire study].

The phasic coronary flow velocity pattern of myocardial bridging was analyzed using a 0.014 inch, 15 MHz Doppler guide wire. Coronary flow velocities and coronary flow reserve at rest and maximum hyperemic time were measured in nine patients with myocardial bridging and 11 normal subjects. Systolic flow reversal followed by prominent early diastolic peak velocity patterns was observed in seven patients (78%) in vessels with myocardial bridging. The systolic time velocity integral was significantly smaller in patients with myocardial bridging than in normal subjects (-1.3 +/- 1.5 vs 4.0 +/- 1.2 cm, p < 0.01), but the diastolic time velocity integral was not significantly different. However, the time velocity integral throughout a cardiac cycle was significantly different between the two groups (12.8 +/- 2.2 vs 18.8 +/- 6.3 cm, p < 0.05). Maximum hyperemic time-averaged peak velocity was significantly lower in patients with myocardial bridging than in normal subjects (40.7 +/- 10.3 vs 57.6 +/- 15.5 cm/sec, p < 0.01), but there was no significant difference in coronary flow reserve between the two groups (2.9 +/- 0.6 vs 3.3 +/- 0.4). Systolic flow reversal followed by prominent early diastolic peak velocity patterns was observed in patients with myocardial bridging. The systolic time velocity integral was significantly smaller in patients with myocardial bridging, so the time velocity integral throughout a cardiac cycle was significantly smaller. There was no significant correlation between coronary flow reserve and ratio of stenosis, and coronary flow reserve was maintained.

Adult↗
PubMed1997

Fatal pulmonary embolism after total hip arthroplasty. Three Japanese cases.

It has been reported that the incidence of postoperative pulmonary embolism is significantly lower in Asians than in Westerners, however, several recent reports have cited an increase in the incidence in Asia. We have experienced three cases of fatal pulmonary embolism after total hip replacement in Japanese patients. Our three patients had received no preoperative prophylaxis, even though they had risk factors for pulmonary embolism. Prophylaxis for pulmonary embolism seems necessary in Asian patients who are at risk.

Adult↗
PubMed1996

Improved visualization of pulmonary venous flow Doppler signal by intravenous injection of sonicated albumin.

Color Doppler signal of pulmonary venous flow was enhanced, and the optimal recordings could be detected in most cases after intravenous injection of sonicated albumin. Improved visualization of pulmonary venous flow Doppler signal by intravenous injection of sonicated albumin should have important clinical implications for the assessment of left ventricular diastolic function by using Doppler technique.

Adult↗
PubMed1996

Comparison of relation of systolic flow of the right coronary artery to pulmonary artery pressure in patients with and without pulmonary hypertension.

Systolic flow velocity is relatively predominant over diastolic velocity in the proximal right coronary artery and right ventricular branch in patients with normal systolic pulmonary artery pressure. The amount of systolic flow velocity reduction in the proximal right coronary artery and right ventricular branch is inversely related to the level of pulmonary hypertension.

Adolescent↗
PubMed1996

An accelerated increase of plasma adrenomedullin in acute asthma.

A novel vasorelaxant peptide, adrenomedullin (AM), has been isolated from the acid extract of human pheochromocytoma. We have recently shown that AM inhibits histamine- and acetylcholine-induced bronchoconstriction in anesthetized guinea pigs in vivo, and this bronchodilatory effect is long-lasting. Here, we measured plasma AM concentrations in nine patients with an acute attack of bronchial asthma. The results were compared with values in 30 age-matched normal control subjects and seven age-matched stable asthmatic patients. The mean AM concentrations of patients with an acute asthma attack (98 +/- 22 pg/mL) were clearly higher than those of normal control subjects (18 +/- 2 pg/mL) and stable asthmatic patients (21 +/- 3 pg/mL). Reverse-phase high-performance liquid chromatography (HPLC) showed that the major component of plasma immunoreactive AM in patients with an asthma attack and in normal subjects equally corresponded to authentic human AM(1-52). Our results suggest that plasma AM is markedly increased in many of the patients during an acute attack of bronchial asthma, but it is not observed in stable asthmatic patients. Although this report is preliminary, the observed increase of circulating AM during an acute asthma attack may represent a compensatory mechanism against the bronchoconstriction, probably through its bronchodilatory action.

Acute Disease↗
PubMed1996

Plasma brain natriuretic peptide during ergometric exercise in hypertensive patients with left ventricular hypertrophy.

Cardiac ventricle is shown to be an important source of circulating brain natriuretic peptide (BNP) in hypertensive rats with left ventricular hypertrophy (LVH). This study examined the effect of short-term exercise with a bicycle ergometer on plasma BNP concentrations in 21 essential hypertension patients with LVH established by echocardiography. The results were compared with those from 24 age-matched hypertensives without LVH. Blood pressure, heart rate, plasma renin activity (PRA), and plasma norepinephrine level increased during exercise, but the mean increases of these parameters were not different in the two groups. Resting BNP levels were slightly but significantly higher in the LVH group than in the non-LVH group. This peptide increased during exercise in the two groups, but the exercise-induced increase (percent increase) in plasma BNP was significantly greater in the LVH group than in the non-LVH group (207% +/- 50% v 141% +/- 36%, P < .05). The exercise-induced increase in BNP was significantly correlated with the left ventricular (LV) mass index (N = 45, r = .60, P < .01). By contrast, the exercise-induced increase in BNP was not correlated with the exercise-induced increase in heart rate, systolic blood pressure, diastolic blood pressure, mean blood pressure, PRA, or noradrenaline level. These results suggest that short-term exercise induces an accelerated increase of plasma BNP in hypertensive subjects with LVH. The LV mass appeared to be related to the observed increase of plasma BNP concentration, at least in our hypertensive patients with LVH.

Adult↗
PubMed1996

Adrenomedullin as a novel antiproliferative factor of vascular smooth muscle cells.

OBJECTIVE: The present study was designed to examine whether adrenomedullin affects fetal calf serum (FCS)-stimulated proliferation in cultured rat vascular smooth muscle cells (VSMCs). METHODS: Rat VSMCs were grown from explants of Sprague-Dawley rat aorta and were grown using the standard cell culture method. After incubation for 24 h with various concentrations of adrenomedullin in the presence of 5% FCS, trichloroacetic acid-insoluble tritiated thymidine was measured in a liquid scintillation counter. After incubation for 48 h, cell counts were performed. Cyclic adenosine 3',5'-monophosphate (AMP) levels were determined by radioimmunoassay. RESULTS: Rat adrenomedullin exhibited concentration-dependent inhibition of the FCS-stimulated increase in thymidine incorporation between 10(-7) and 10(-9) mol/l and of cell number at 10(-7) mol/l. However, the calcitonin generelated peptide (CGRP) receptor antagonist human CGRP(8-37) abolished these antiproliferative effects of rat adrenomedullin. Inhibition by adrenomedullin of FCS-stimulated cellular proliferation was paralleled by an increase in the cellular level of cyclic AMP. 8-Bromocyclic AMP, a cyclic AMP analogue, and forskolin, an activator of adenylate cyclase, inhibited the FCS-stimulated increase in thymidine incorporation and cell number. CONCLUSIONS: These results suggest that adrenomedullin inhibits FCS-stimulated proliferation in cultured rat VSMCs, probably through a cyclic AMP-dependent process. Taken together with the finding that adrenomedullin is synthesized in and secreted from vascular endothelial cells, adrenomedullin may play a role as an antiproliferative factor for VSMCs in a paracrine fashion.

8-Bromo Cyclic Adenosine Monophosphate↗