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Biomedical subjects

K Miyatake

Publications and source records attributed to K Miyatake.

At least 271 records · Page 15Linked to original sources
PubMed1984

Clinical applications of a new type of real-time two-dimensional Doppler flow imaging system.

The clinical significance of a newly developed real-time 2-dimensional (2-D) Doppler flow imaging technique was assessed. In the instrumentation of the echocardiograph, the pulsed Doppler mechanism was incorporated in a wide-angle, phased-array system. The Doppler flow signals obtained from the cardiac chamber were processed on the basis of the autocorrelation principle. The direction, velocity and variance of the intracardiac blood flow were calculated in real time and displayed in the color-coded mode on the television screen, and were superimposed on the 2-D echocardiographic image of the heart. The technique was used in 20 healthy subjects and 100 cardiac patients. The new technique clearly visualized the whole aspect of intracardiac blood flow by the cine mode in real time; thus, the technique may be called Doppler cineangiocardiography. The mitral inflow and the aortic ejection flow were clearly demonstrated. A regurgitant jet from the valve orifices was dynamically visualized as seen in the cineangiogram. The spatial orientation and extent of the regurgitant jet were easily assessed. The jet stream through the stenotic mitral orifice was well imaged in the left ventricular cavity, showing a variety of stream directions. Intracardiac shunts in ventricular septal defect and atrial septal defect were clearly visualized. The defect could be localized on the interventricular septum on the basis of the site where the shunt flow spurted, although the echocardiographic interruption was not demonstrated in the 2-D echocardiographic image of the cardiac structure. Although some technical problems remain, our new technique greatly improves the diagnostic efficacy of ultrasound.

Adolescent↗
PubMed1984

Fructose 2,6-bisphosphate, a potent regulator of carbohydrate metabolism, inhibits trehalose phosphorylase from protist Euglena gracilis.

Partially purified trehalose phosphorylase (EC 2.4.1.64) from Euglena gracilis SM-ZK was inhibited by fructose 2,6-bisphosphate in both synthetic and degradative directions. Ki value for trehalose phosphorolysis was 1.2 microM and that for trehalose synthesis was 0.5 microM. Functions of fructose 2,6-bisphosphate in Euglena, particularly in the regulative mechanism of the two reserve carbohydrates, paramylon and trehalose, are discussed.

Adenine Nucleotides↗
PubMed1984

Fatty acid synthesis in mitochondria of Euglena gracilis.

A malonyl-CoA-independent fatty acid synthetic system, different from the systems in other subcellular fractions, occurred in mitochondria of Euglena gracilis. The system had ability to synthesize fatty acids directly from acetyl-CoA as both primer and C2 donor using NADH as an electron donor. Fatty acids were synthesized by reversal of beta-oxidation with the exception that enoyl-CoA reductase functioned instead of acyl-CoA dehydrogenase in degradation system. A fairly high activity of enoyl-CoA reductase was found on various enoyl-CoA substrates (C4-C12) with NADH or NADPH. Three species of enoyl-CoA reductase, distinct from each other by their chain-length specificity, were found in Euglena mitochondria, and one of them was highly specific for crotonyl-CoA. It is also discussed that the mitochondrial fatty-acid synthetic system contributes to wax ester fermentation, the anaerobic energy-generating system found in the organism.

Acetyl Coenzyme A↗
PubMed1984

Augmentation of atrial contribution to left ventricular inflow with aging as assessed by intracardiac Doppler flowmetry.

The influence of aging on the left ventricular (LV) function in diastole was investigated from the aspect of the mitral inflow pattern using 2-dimensional Doppler echocardiography. The subjects for the investigation were 69 persons who were diagnosed as healthy by a checkup examination. The peak velocity in the rapid filling phase and that in the atrial contraction phase tended to decrease and to increase with aging, respectively. However, these tendencies were not statistically significant. However, the ratio of the atrial contraction phase to the rapid filling phase showed a significant increase with aging (r = 0.82, p less than 0.001). Therefore, it is considered that the mitral flow conditions are influenced by aging. The result obtained is also interpreted to mean that the LV distensibility in early diastole is impaired with aging and that the contribution of the atrial contraction to LV filling is compensatorily augmented.

Adult↗
PubMed1984

Occurrence of oxygen-sensitive, NADP+-dependent pyruvate dehydrogenase in mitochondria of Euglena gracilis.

Pyruvate dehydrogenase found in mitochondria of Euglena gracilis was active on NADP+ but not NAD+, and FAD and methyl viologen also served as electron acceptors. For 2-oxoglutarate dehydrogenase both NAD+ and NADP+ were utilized and the ratio of its activity on NAD+ and NADP+ was about 1:5. The activity of pyruvate dehydrogenase was inhibited by pyruvate in aerobiosis, while not in anaerobiosis.

Aerobiosis↗
PubMed1984

Analysis of blood flow in pulmonary hypertension with the pulsed Doppler flowmeter combined with cross sectional echocardiography.

Blood flow patterns were analysed at nine points in the pulmonary area using the pulsed Doppler technique combined with cross-sectional echocardiography in 53 patients with heart disease and 10 healthy subjects. In subjects with a normal pulmonary artery pressure the blood flow pattern in systole showed a gradual acceleration and deceleration with a rounded summit in mid systole, designated the round type. In patients with pulmonary hypertension it showed a rapid acceleration and early deceleration with a sharp peak in early systole, designated the triangular type. The acceleration time index, defined as the ratio of the time interval from the beginning to the peak of ejection to the ejection time, showed a significant inverse correlation with mean pulmonary artery pressure. In pulmonary hypertension a prominent reverse flow occurred in the right posterior part of the pulmonary trunk during mid-systole and early diastole, indicating the presence of a vortex. Similar flow patterns were also seen in patients with idiopathic pulmonary artery dilatation. The factors responsible for the triangular type were principally the reduced capacitance and increased impedance of the pulmonary vascular tree. Those responsible for the reverse flow were the curved path of the blood flow and dilatation of the pulmonary artery.

Adult↗
PubMed1984

Doppler echocardiographic features of coronary arteriovenous fistula. Complementary roles of cross sectional echocardiography and the Doppler technique.

The Doppler echocardiographic features of coronary arteriovenous fistula were investigated in eight patients with left or right coronary arteriovenous fistulas who had a continuous heart murmur in the upper precordial area and whose diagnoses were confirmed by coronary angiography. In four patients the dilated lumen of the coronary arteriovenous fistula was visualised by cross sectional echocardiography. Of these, three showed abnormal unidirectional continuous flow signals with broad velocity spectra in the fistula. Abnormal, powerful, unidirectional or bidirectional continuous Doppler signals were detected in part of the pulmonary artery in two of the eight patients, in part of the right ventricle in two, and in part of the right atrium in one; these signals were interpreted as indicating shunt flow. Although the opening of the fistula was difficult to visualise by cross sectional echocardiography, the pulsed Doppler technique helped identify the site in patients with dilatation of the coronary artery. In the remaining three patients with a small shunt no abnormal findings were obtained with cross sectional echocardiography or the Doppler technique. The size of the fistula below which no abnormal findings may be obtained by Doppler echocardiography still needs to be determined.

Adult↗
PubMed1984

[Noninvasive determination of the ratio of pulmonary to systemic blood flow with two-dimensional Doppler echocardiography: efficacy and limitation].

Noninvasive determination of the ratio of the pulmonary to systemic blood flow (Qp/Qs) was attempted in 31 cases with intracardiac shunt using two-dimensional pulsed Doppler echocardiography. The Qp/Qs of these cases was ranged from 0.99 to 4.55 with an average of 2.63 by cardiac catheterization. Technical problems in the measurement were also studied. Seventeen cases with no shunt were served as controls. Systemic and pulmonary flow volumes, Qp and Qs (ml/min), were calculated by the following equation: Q (ml/min) = mean flow velocity (cm/sec) X cross sectional area of the semilunar valve ring (cm2) X 60 Here, the sample volume was set in the center of the valve ring at the phase when the flow velocity attained its peak in a pulse period. The mean velocity was obtained by dividing the integration of instantaneous mean frequency in the sample volume for a pulse period by RR interval. The ultrasonic incident angle was measured on the echocardiogram. The velocity profile at the valve ring was assumed to be a plane wave. The diameter (D) of the valve ring was measured on the echocardiograms of the long-axis view of the outflow tract. To make a correction referring to the value obtained by angiocardiography, 0.22 cm was added to the value obtained on the echocardiogram (D). The cross sectional area of the valve ring was calculated according to the following formula: Cross sectional area (cm2) = pi X [(D + 0.22/2)]2 The Qp/Qs ratio by the Doppler method in the cases with no intracardiac shunt was 1.11 (S.D. = 0.21) on an average and the Qp/Qs in the cases with an intracardiac shunt was well correlated with that by catheterization (r = 0.82). These results suggested the feasibility of the clinical application of the Doppler method for noninvasive determination of Qp/Qs. In 17 cases, pulmonary and systemic flow volumes measured by the direct Fick method were compared with those by the Doppler method, respectively. Considerable differences were observed between them. There was a tendency that both pulmonary and systemic flow volumes were under-estimated by the Doppler method in cases with a large shunt.(ABSTRACT TRUNCATED AT 400 WORDS)

Blood Circulation↗
PubMed1984

[Phonocardiographic findings of atypical patent ductus arteriosus with pulmonary hypertension].

Among 71 patients with proved patent ductus arteriosus (PDA) as a sole anomaly, 13 were diagnosed as having "atypical PDA" because of a lack of a continuous murmur. Of these, 10 had find-pulmonary hypertension and were the materials of the present study, in which the phonocardiographic findings were correlated with the findings by other techniques including pulsed Doppler echocardiography. Six cases with equal pulmonary arterial and aortic pressures showed a diastolic murmur alone. The murmur started with the pulmonic component of the second heart sound and continued throughout diastole. All cases showed inspiratory augmentation or presystolic accentuation of the diastolic murmur. Pulsed Doppler echocardiograms disclosed that the murmur was produced by pulmonary regurgitation in five of six cases and by a left-to-right shunt via the ductus plus pulmonary regurgitation in one case. A to-and-fro murmur was observed in three cases. Pulmonary artery pressure was significantly lower than that of the systemic artery in two of three cases. These hemodynamic findings and pulsed Doppler echocardiograms indicated that the murmur of the two cases was produced by both a left-to-right shunt through the ductus and pulmonary regurgitation. A systolic murmur only was seen in one case and the cause of this murmur was not clear. In four of five cases with grade IV and V murmur, division or plugging of the ductus was performed with uneventful clinical course in three and sudden death in one. On the other hand, four of five cases with grade II and III murmur showed Eisenmenger reaction and the surgery was not attempted. The second heart sound showed normal splitting in eight cases, abnormally wide splitting in one case and was single in one case.

Adolescent↗
PubMed1984

[Analysis of left ventricular blood flow in cases of myocardial infarction: a preliminary report].

Analysis of left ventricular blood flow in cases of myocardial infarction was attempted by two-dimensional Doppler echocardiography. Subjects consisted of 25 cases of myocardial infarction with and without ventricular aneurysm, and 15 healthy persons as controls. The Doppler recordings were made in nine areas within the left ventricular cavity from the apical approach. For healthy subjects, ejection flows were recorded in the main cavity and directed towards the aortic orifice in systole, and diastolic flows in the left ventricular inflow were recorded from the mitral orifice to the apex. However, diastolic flows toward the aortic orifice were also recorded along the interventricular septum, and interpreted as eddy currents from the apical cavity. There were no high velocity flows in the phases of isometric contraction and relaxation. In seven of 25 cases of myocardial infarction, abnormally high velocity flows of more than 30 cm/sec were recorded in the isometric relaxation phase, which were directed away from the asynergic part. In eight of the 25 patients examined, high velocity flows toward the cardiac apex were recorded at the posteroapical area in systole. Such flows have never been observed in healthy subjects. Inertia of the diastolic mitral inflow is considered to continue during systole due to impairment of contractions of the apicoinferior wall.

Adolescent↗
PubMed1984

[Aortic flow patterns in heart diseases with left-to-right shunts from the aorta, and their clinical significance: a Doppler echocardiographic study].

Aortic flow patterns were analyzed using two-dimensional Doppler echocardiography for 15 patients with patent ductus arteriosus, seven with ruptured aneurysms of the sinus of Valsalva, two with coronary artery fistulae and for 22 healthy persons, with special reference to diastolic flow patterns. The conclusions were as follows: In healthy subjects, there was a tiny and transient reversed flow signal in early diastole followed by a slow and sustained diastolic forward flow signal. The velocity of the diastolic forward flow was slower and the duration was shorter in the lower abdominal aorta than in the upper portion. In patients with shunts from the aorta to the right-sided chambers, the early diastolic reverse flow was enhanced, and another reversed flow developed in mid- and late diastole, which was the most evident in the lower portion of the abdominal aorta. The extent of the reversed flow correlated significantly with Qp/Qs by catheterization (r = 0.73). Thus, the abdominal flow patterns in cases with left to right shunts from the aorta to the right-sided chambers of the heart provided information for estimating the size of the shunt volume. In patients with bi-directional shunts, the dominant direction of the shunt during diastole can apparently be determined by analyzing the aortic flow patterns.

Adolescent↗
PubMed1983

Characteristics of tubulin aggregation by tubulin-binding proteins from brain and by synthetic polycations.

A basic fraction from brain cytosol was found to contain two or more tubulin-binding proteins, able to induce aggregation of tubulin accompanied by hydrolysis of GTP. In some respects tubulin aggregation by the brain proteins was similar to its aggregation by polylysine. The burst of GTP hydrolysis accompanying tubulin aggregation by polylysine had the following characteristics: enhanced by salt and abolished by low temperature; not stoichiometric with the amount of tubulin precipitated and actually maximal at relatively low polylysine concentration; uncoupled temporally from aggregation, which occurred over a much shorter interval.

Animals↗
PubMed1983

Mitral regurgitation in hypertrophic cardiomyopathy. Non-invasive study by two dimensional Doppler echocardiography.

Mitral regurgitation and its haemodynamic features were investigated non-invasively in cases of hypertrophic cardiomyopathy by means of two dimensional Doppler echocardiography. There were 28 patients, 14 of whom showed systolic anterior motion (SAM) of the mitral echo; the other 14 did not. The following results were obtained. (1) Mitral regurgitation was detected by the Doppler technique in all cases with systolic anterior motion of the mitral echo and in half of those without it. (2) Doppler signals of mitral regurgitation started immediately after the first heart sound. (3) Mitral regurgitant flow was often distributed from the entire mitral orifice over the entire or the posterior half of the left atrium in the cases with systolic anterior motion. In the cases without systolic anterior motion the regurgitation was usually localised near the mitral orifice. These features differ from those of regurgitation usually seen in rheumatic mitral valve disease and idiopathic mitral valve prolapse. (4) The Doppler technique and left ventriculography were equally efficient in detecting mitral regurgitation. (5) The early systolic component of the murmur of hypertrophic myopathy is considered to result in the main from concomitant mitral regurgitation, but not from turbulent blood flow in the left ventricular outflow tract, so that in cases with mitral regurgitation as a complication, mitral regurgitation may also contribute to the development of the midsystolic portion of the systolic murmur, while the main origin of this portion of the murmur is the left ventricular outflow obstruction.

Adult↗
PubMed1983

[Measurement of four chambers' volumes and ventricular masses by cardiac CT examination].

Using cardiac computed tomography (CT), the "mean" volume of each cardiac chamber and both ventricular masses were calculated from summation of a sliced volume by ungated scans obtained using rapid sequential scanning covering the whole heart. Estimation of a normal value of each chamber's volume was attempted in 20 patients with ischemic heart disease and with normal heart function. The "mean" volume of the right atrium (RAMV), right ventricle (RVMV), and left atrium (LAMV) was 22.3 +/- 6.5, 40.3 +/- 6.5 and 28.7 +/- 8.2 ml/m2, respectively. In 54 patients with valvular heart diseases, each chamber's volume obtained by CT was compared with the grade of tricuspid regurgitation (TR) estimated by ultrasonic Doppler technique or the grade of mitral regurgitation (MR) by left ventriculography (LVG). The RAMV (234 +/- 119 ml/m2) and the RVMV (101 +/- 39 ml/m2) were markedly increased in patients with severe TR (grade 3 to 4) (p less than 0.01). The LAMV (487 +/- 231 ml/m2) was also increased in patients with severe mitral regurgitation (grade 3 to 4) (p less than 0.01). In 46 patients with valvular heart diseases, the LVMV by CT was well correlated with end-diastolic volume (EDV) obtained by LVG (r = 0.92), and the LVEDVs by ECG gated CT and by LVG showed a fairly good correlation (r = 0.95). CT examination was performed before and after surgery in 17 patients with MR or TR for evaluation of the change of chamber volumes. The mean reduction ratio (MRR) of the RAMV after tricuspid annuloplasty, the LVMV after mitral valve plasty, and the LAMV after left atrial plication was 44%, 41%, and 60%, respectively.

Cardiac Volume↗