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S Senda

Publications and source records attributed to S Senda.

At least 37 records · Page 2Linked to original sources
PubMed1998

Evaluation of acoustic properties of the live human smooth-muscle cell using scanning acoustic microscopy.

This study was performed to measure the acoustic propagation speed in live human aortic smooth-muscle cells (HASMC), using scanning acoustic microscopy (SAM) and a novel measurement theory that permits the measurement of the acoustic propagation speed in biological samples of unknown thickness. C-mode and X-Z-mode images of HASMC under three different conditions: growing (G); differential (D); and on hypotonic loading (H), were acquired using 100-MHz, 450-MHz and 600-MHz ultrasound. The images exhibit features related to the cell surface curvature and intracellular structure. The theory supporting the methodology is derived in this article and makes use of the interference fringes within the focusing lens of the high-frequency transducer. The propagation speed in the cells was calculated from the location of the interference fringe on the C-mode images and the fringe shift on the X-Y-mode images with 450-MHz ultrasound. The propagation speed in D (1624 +/- 16 m/s) was significantly higher than those in G (1571 +/- 14 m/s, p < 0.05) and H (1585 +/- 8 m/s, p < 0.05). Scanning acoustic microscope measurements, along with the described theory, are useful for studying the acoustic properties of live cells ex vivo and have applications in both pathophysiology and biomechanics.

Acoustics↗
PubMed1998

[Mitral valve tissue characterization using acoustic microscopy].

Mitral valve hardness in the rough and clear zones was evaluated by measuring the propagation velocity (m/sec) of ultrasound through the valve, based on the hypothesis that harder tissues will have larger ultrasonic velocity values passing through the tissue. Mitral valve specimens were obtained from 16 normal subjects (age, 15-72 years) at autopsy. An acoustic microscope, operating at 450 MHz, was used to measure the ultrasonic velocity through the three layers of the valve: the atrialis; the spongiosa; and the fibrosa. Furthermore, the mean ultrasonic velocity through the three layers was measured. These measurements were conducted in the rough and clear zones of the valve. In the rough zone, the ultrasonic velocities were 1,634 +/- 71 in the atrialis, 1,574 +/- 37 in the spongiosa, and 1,726 +/- 97 m/sec in the fibrosa. In the clear zone, the ultrasonic velocities were 1,691 +/- 117 in the atrialis, 1,575 +/- 44 in the spongiosa, and 1,909 +/- 131 m/sec in the fibrosa. There were significant differences between velocities in the three layers in both the rough and clear zones. Furthermore, the mean ultrasonic velocity in the three layers in the clear zone (1,887 +/- 138 m/sec) was higher than that in the rough zone (1,642 +/- 53 m/sec; p < 0.001). These findings show that fibrosa, which is rich in collagen fibers, is harder than atrialis, which is rich in elastic fibers, and the spongiosa, which is poor in connective tissues, is the softest. The higher mean ultrasonic velocity in the clear zone than in the rough zone indicates that the clear zone is harder than the rough zone, although the clear zone is thinner than the rough zone.

Adolescent↗
PubMed1997

Effects of short-term administration of sublingual nifedipine on coronary arterial wall elastic properties: evaluation by intravascular ultrasound.

Intravascular ultrasound is suited to measure coronary cross-sectional anatomy. Therefore the regional coronary wall elasticity was evaluated by examining the response to nifedipine. In 20 patients, coronary ostial pressure (P) and intravascular ultrasound images were simultaneously recorded before and after sublingual administration of 10 mg nifedipine. We identified the perimeter of the vessel wall, with normal or atherosclerotic plaque, on ultrasound image. At the atherosclerotic site, we measured segmental perimeter (S) for each normal or plaque segment. The ratio of the individual segment length (delta S/delta P) and cyclic variation of cross-sectional area (delta A/delta P) per mm Hg increase in P were calculated. Nifedipine decreased pressure (133/79-120/73 mm Hg) and increased heart rate (79-82 beats/min). After nifedipine, delta A/delta P increased from 8.5 +/- 10.2 x 10(-3) to 16.5 +/- 14.4 x 10(-3) mm2/mm Hg at 20 normal sites (p = 0.005) but was unchanged at 17 atherosclerotic sites (6.6 +/- 7.0 x 10(-3) to 6.7 +/- 7.1 x 10(-3) mm2/mm Hg). Nifedipine increased delta S/delta P in normal segments (4.5 +/- 8.7 x 10(-3) to 9.9 +/- 10.9 x 10(-3) mm/mm Hg; p = 0.02) but produced no change in segments with calcified or soft plaque (-1.1 +/- 0.3 x 10(-3) to 1.4 +/- 1.6 x 10(-3) mm/mm Hg and 5.0 +/- 3.6 x 10(-3) to 6.1 +/- 4.8 x 10(-3) mm/mm Hg, respectively). This study demonstrated that nifedipine increases regional coronary arterial elasticity at normal segments but not at that containing mildly atherosclerotic segment, and likely that the arterial wall function indicated by the response to nifedipine was impaired at an early stage of atherosclerosis.

Administration, Sublingual↗
PubMed1997

Left ventricular diastolic filling dynamics during isometric exertion in syndrome X assessed with Doppler flowmetry.

To study left ventricular diastolic properties in syndrome X, we analyzed transmitral filling dynamics during handgrip exertion. In 14 normal subjects (N), 17 with syndrome X (Syn X), 16 with single-vessel disease (SVD), and 8 with multiple-vessel disease (MVD), transmitral inflow was recorded at baseline and during handgrip (50% of maximal effort for one minute) using pulsed Doppler echocardiography. We measured early diastolic (E) and late atrial (A) inflow velocities, A/E ratio and percent change of A/E from baseline (%A/E). Blood pressure and heart rate increased to the same degree in each group during handgrip. In normal subjects, E did not change with handgrip; A (51 +/- 10 vs 54 +/- 11 cm/sec, P < 0.05) and A/E (1.16 +/- 0.22 vs 1.25 +/- 0.33, P < 0.05) increased minimally. In Syn X subjects, E decreased (51 +/- 10 vs 38 +/- 10 cm/sec, P < 0.0001), A increased (52 +/- 11 vs 60 +/- 14 cm/sec, P < 0.005), and A/E increased markedly (1.07 +/- 0.31 vs 1.68 +/- 0.51, P < 0.0001). The %A/E in Syn X and MVD were significantly larger than that in SVD and N (Syn X: 58 +/- 29%; MVD: 45 +/- 25%; SVD: 22 +/- 21%; N: 8 +/- 13%). Handgrip-induced changes in diastolic filling in syndrome X and are similar to those in MVD and more marked than in SVD. These changes are consistent with impaired ventricular relaxation and support a generalized left ventricular (LV) abnormality in syndrome X.

Adult↗
PubMed1997

Adult Still's disease with myocardial dysfunction induced by microangiopathy.

A 52-year-old man with inflammatory disease of unknown origin but no specific laboratory abnormalities was referred to our hospital. He has subsequently diagnosed as having adult Still's disease. During an episode of severe inflammation he suffered reversible myocardial damage as revealed by electrocardiography, echocardiography and 201Tl myocardial scintigraphy; this was ameliorated by treatment with steroids and immunosuppressive drugs. No significant stenosis of the coronary artery was observed on coronary angiography. Interstitial mononuclear infiltration was apparent in the right ventricle on endomyocardial biopsy. Myocardial injury with adult Still's disease, which may result in heart failure, has rarely been reported. We report a case of adult Still's disease with myocardial dysfunction that may have been caused by microangiopathy.

Heart↗
PubMed1995

Stiffness of human arterial wall assessed by intravascular ultrasound.

Little is known about the elastic properties of human arteries. Intravascular ultrasound (IVUS) can measure the instantaneous circumference or diameter of the arteries during a cardiac cycle, and so investigate human arterial elasticity in vivo. We studied 36 patients aged from 35 to 72 years classified into the ischemic heart disease (IHD) group (21 patients aged 39 to 71 years) and the non-ischemic heart disease (NIHD) group (15 patients aged 35 to 76 years) who had no atherogenic factors. The stiffness and wall morphology of six portions from the thoracic descending aorta to common iliac artery were measured by 8F, 15 MHz IVUS. The stiffness parameter, beta, was calculated as 1n (Pmax/Pmin)/(Cmax/Cmin-1), where P is arterial pressure, and C is the circumference of the artery. The thickness of the intima-media complex echo (Th) was used as a substitute for the wall thickness, and Th/D was calculated as an index of relative wall thickness, where D is the minimum luminal diameter. The pulse wave velocity (PWV) was measured with a conventional method. beta increased after branching of the renal artery and increased much more toward the periphery in comparison with the thoracic descending aorta in both groups. At all portions except the abdominal aorta after branching of the renal artery and the common iliac artery, beta was significantly larger in the IHD than the NIHD group. Th/D increased as well as beta in both groups. At all portions except after branching of the renal artery, Th/D was significantly larger in the IHD than the NIHD group.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1994

Noninvasive estimation of left ventricular Max(dP/dt) from aortic flow acceleration and pulse wave velocity.

The Doppler method of obtaining left ventricular Max(dP/dt) proposed recently was based on the measurement of mitral regurgitation velocity. Since Max(dP/dt) is an isovolumic phase index, its use in cases of mitral regurgitation may be open to argument. However, we had proposed a noninvasive method of estimating left ventricular Max(dP/dt) based on different principles. In our method, Max(dP/dt) had been given by Max(dP/dt) = (rho)cMax (du/dt), where rho is the blood density, c is the pulse wave velocity, and u is the flow velocity in the aorta. We had derived the above equation theoretically, and confirmed its validity by animal experiments. In our previous study, we also applied our method in the clinical setting. The aortic flow velocity was measured by Doppler echocardiography, and the pulse wave velocity by mechanocardiography or Doppler echocardiography. (Rho)cMax(du/dt) obtained noninvasively was compared with Max(dP/dt) measured with a catheter-tip micromanometer. We found an excellent correlation between (rho)cMax(du/dt) and Max(dp/dt), and concluded that (rho)Max(du/dt) is useful in assessing noninvasively the contractile state of the left ventricle. Here, we summarize our method, review previous results, and report new results of the clinical application of our method.

Blood Flow Velocity↗
PubMed1993

The effect of obesity on ventilatory response and anaerobic threshold during exercise.

To facilitate making the physical fitness programs for obesity control, we investigated the effects of obesity on the ventilatory response during exercise and exercise tolerance. One hundred eighteen adults were divided into a normal group and fatty group by percentage of body fat. Each subject performed a submaximal exercise test under the gas-exchange measurement. The fatty group was inferior to the normal group in exercise tolerance. The respiratory mode, during exercise, in the fatty group was characterized by higher respiratory rate and less tidal volume compared with the normal group. This mode may result in increased dead space and therefore unavailable ventilation capacity. These data suggest that the characteristic respiratory mode in the fatty group was a factor in the lower exercise tolerance.

Adult↗
PubMed1993

Contrast echocardiography for evaluation of left ventricular flow dynamics using densitometric analysis.

BACKGROUND: Few data exist regarding intraventricular flow patterns in the presence of left ventricular dysfunction. Therefore, we examined the relation between intracavitary left ventricular flow dynamics and the presence of ventricular contractile abnormalities using videodensitometric analysis of transpulmonary contrast echocardiography. METHODS AND RESULTS: Two-dimensional echocardiography was performed before, during, and after intravenous injection of sonicated albumin in 8 normal subjects, 22 patients with infarction, and 6 patients with dilated cardiomyopathy. Time-intensity curves were recorded, and disappearance half-times (in cardiac cycles) were measured for regions of interest at the mitral orifice (Ta) and mid-left ventricular cavity (Tb). We observed contrast enhancement of the left ventricular cavity in 28 of 36 patients. Ta and Tb were identical (19 beats) in all normal patients, but Tb was greater than Ta (19 versus 22 beats, P < .001) in patients with dyssynergy. Patients with dyssynergy were divided in three groups: group A, in whom Tb-Ta < or = 3; group B, in whom Tb-Ta > or = 4; and group C, which was composed of patients without contrast enhancement. Left ventricular end-diastolic dimension was similar in normal patients (46.1 mm) and group A patients (50.3 mm) but was less in each cohort than in groups B (58.7 mm) and C (64.1 mm) (all P < .01). Significant correlation was observed between Tb-Ta and both ejection fraction (r = -.67, P < .001) and wall motion index (r = .62, P < .001). CONCLUSIONS: Clearance of contrast from the mid-left ventricular cavity is prolonged in patients with left ventricular dysfunction. This prolongation may be related to increased left ventricular diastolic volume, impaired intracavitary mixing, or paradoxical systolic flow. Delayed left ventricular contrast washout may have implications regarding the formation of left ventricular thrombi.

Adult↗
PubMed1993

Treatment of ulcerative colitis with camostat mesilate, a serine protease inhibitor.

We were able to induce and maintain remission with camostat mesilate, a serine protease inhibitor, in two patients with ulcerative colitis, to whom salicylazosulfapyridine could not be administered due to previous side effects. The enzymatic activity of proteases from granulocyte, pancreatic juice and bacteria is possibly harmful to the inflamed colonic mucosa. Camostat mesilate can be expected to have an anti-inflammatory effect on the damaged mucosa of inflammatory bowel disease.

Adult↗
PubMed1992

A noninvasive method of measuring Max(dP/dt) of the left ventricle by Doppler echocardiography.

Although slightly affected by alterations in preload, the maximum first derivative of left ventricular pressure with respect to time, Max(dP/dt), is widely regarded as a simple and convenient index of cardiac contractility for clinical use. The feasibility of noninvasive, hence repeatable, measurement of Max(dP/dt) will certainly lead to re-evaluation of its usefulness. Max(dP/dt) is given by the following equation: Max(dP/dt) = rho c Max(du/dt), where rho is the blood density, c the pulse wave velocity, and mu the flow velocity in the aorta. This equation has been previously validated in animal experiments and has now been applied to the clinical setting for the first time. In 20 patients without aortic stenosis, left ventricular pressure was measured with a catheter-tip micromanometer, aortic ejection flow velocity was measured by Doppler echocardiography, and pulse wave velocity by mechanocardiography or Doppler echocardiography. Then, delta c Max (du/dt was calculated from the measured data and compared with measured Max (dP/dt). A significant positive correlation was found between them (rho c Max (du/dt) = 0.96 x Max (dP/dt) + 6.52, r = 0.83, p < 0.001). In 11 patients with hypertension, rho c Max (du/dt) was obtained before and after long-term (average 13.1 months) treatment with antihypertensive drugs. In spite of the expected reduction in blood pressure and the regression of left ventricular mass, rho c Max (du/dt) remaioned unchanged. In 9 patients with dilated cardiomyopathy, the effects of beta 1-agonist were tested at the beginning of therapy (30 mg/day denopamine) and 6 months later. The increase in rho c Max (du/dt) observed 1 hour after oral administration of he drug had not changed significantly 6 months later. We conclude that the index rho c Max (du/dt), is useful in assessing the contractile state of the left ventricle noninvasively.

Antihypertensive Agents↗
PubMed1992

Evaluation of arterial wall histological and physical characteristics using intravascular echography.

Using a high-frequency ultrasound intravascular imaging system we evaluated the intravascular echo image by comparing it with histological findings in 57 arterial segments of 17 autopsy cases. Moreover, in 8 dogs we estimated the arterial elastic property by observing the change of the arterial section accompanying a reduction of arterial pressure due to hemorrhage (H) or nifedipine infusion (N). The characteristics of the intravascular echograms were as follows: 1) In a normal artery the arterial wall consisted of the inner high echoic, the medial low echoic and the outer high echoic layers. 2) In an aged artery the fibrous thickened intima was seen as the low echo layer giving an echo about the same as that of the normal media, and the intensity of the echo from the degenerated media was lower than that of the normal media. 3) In atheroma the echo intensity of the elastic fiber-rich region was higher than that of the surrounding region, while the calcified region showed as a brighter echo with outer echo free space due to shadowing. We measured the arterial radius, area and circumferential length on the intravascular echo image and calculated the arterial wall tension-circumferential length and the pressure-arterial area relationships. By analysing each relation, we obtained the stiffness and compliance parameters, respectively. The stiffness parameter with N was lower than that with H [(1.5 +/- 0.5) x 10(-2) vs (2.8 +/- 0.9) x 10(-2)] and the compliance parameter with N was higher than that with H (0.92 +/- 0.28 vs. 0.46 +/- 0.12).(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1990

Evaluation of left-sided valvular regurgitation in healthy, hypertensive and myocardial infarction subjects by Doppler echocardiography.

Doppler echocardiography has become a very useful and widely employed imaging technique for evaluating valvular regurgitation, and has thus lead to the discovery of regurgitation in unexpected subjects. In this study, we examined left-sided valvular regurgitation in 31 healthy subjects, 35 patients with hypertension and 43 patients with old myocardial infarction by Doppler echocardiography. Aortic regurgitation was found in 3% of healthy subjects, 8% of hypertensive patients and 5% of patients with myocardial infarction. Mitral regurgitation was found in 35% of healthy subjects, 69% of hypertensive patients and 84% of patients with myocardial infarction. The pathogenesis of mitral regurgitation in hypertension is considered to be the impairment of the mitral leaflets, since neither anatomical nor functional abnormalities were found in the subvalvular mitral apparatus. Left ventricular dilatation and asynergy near the papillary muscles were related to the pathogenesis of mitral regurgitation in myocardial infarction. Mitral regurgitation in healthy subjects and hypertensive patients was mild and resistant to afterload stress, suggesting that it was less pathological. On the other hand, mitral regurgitation in myocardial infarction was easily worsened by afterload stress. Doppler echocardiography has thus provided us with new insights into valvular regurgitation in healthy subjects and patients without rheumatic valvular disease.

Adult↗
PubMed1990

[Intracardiac flow vector measurement by simultaneous dual-frequency two-beam pulsed Doppler echocardiography].

Conventional single-beam pulsed Doppler echocardiography has certain limitations in quantitatively measuring the intracardiac blood flow, because the Doppler incident-angle to the flow stream is uncertain. In the present study, the absolute velocity and direction of the intracardiac blood flow, i.e., flow vector, were measured using our newly-developed dual-frequency two-beam pulsed Doppler echocardiography. This instrument has two transducers with center frequencies of 3.5 MHz (main-beam) and 2.2 MHz (sub-beam) which are linked by two arms. Three potentiometers are set up by the three joints to sense the relative angles. Two velocity components at the intersection of the main- and sub-Doppler beams were measured simultaneously with different directional approaches. The flow vector was calculated manually from the two velocity components. The study population consisted of 18 healthy subjects ranging in age from 23 to 39 years. The left ventricular (LV) inflow vector was measured at the center of the mitral annulus, and the ejection flow vector was measured at the levels of the tip (E1) and the mid-portion (E2) of the anterior mitral leaflet in the LV outflow tract. The results were as follows: 1. The LV rapid inflow (R) was directed slight posteriorly towards the cardiac apex, and its average maximal velocity was 78 +/- 15 cm/sec (mean +/- SD). The LV inflow due to the atrial contraction was directed even more posteriorly than was the R, and its average maximum velocity was 43 +/- 10 cm/sec. 2. The LV ejection flows at E1 and E2 were directed slightly posteriorly rather than parallel to the interventricular septum, and the maximum velocity at E1 and E2 was 53 +/- 20 m/sec and 85 +/- 23 cm/sec, respectively. In conclusion, the dual-frequency two-beam pulsed Doppler technique allows quantitative measurement of the intracardiac blood flow dynamics regardless of the Doppler incident-angle to the flow stream.

Adult↗