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Biomedical subjects

R Takeda

Publications and source records attributed to R Takeda.

At least 271 records · Page 15Linked to original sources
PubMed1988

Electrophysiological properties of respiratory laryngeal motoneurons and effects of thiopental.

Transmembrane potentials of the respiratory laryngeal motoneurons were recorded in decerebrate, vagotomized and paralyzed cats. Twenty inspiratory and thirteen postinspiratory neurons were identified. Periodic membrane potential (MP) fluctuations as well as patterns of postsynaptic potentials (PSPs) were characterized in each type of neurons by measuring the input resistance and injecting Cl- to reverse inhibitory PSPs. On the basis of PSP patterns, two subtypes of inspiratory neurons could be distinguished. Thiopental (2-3 mg/kg, i.v.) produced depolarization together with reduction of firing in most laryngeal neurons. Excitatory and inhibitory PSPs were both depressed and MP fluctuations became smaller in each phase of the respiratory cycle. Elevation of the firing threshold and separation of IS-SD spikes often occurred after thiopental. These results suggest that thiopental depresses the laryngeal motoneuron through inhibition of synaptic transmission and of spike generation.

Animals↗
PubMed1988

[Diastolic dysfunction and its relation to myocardial fibrosis in essential hypertension].

This study elucidated diastolic left ventricular dysfunction and whether myocardial interstitial fibrosis correlates with diastolic dysfunction in mild to moderate systemic hypertension (HT). Six normotensive subjects, 18 hypertensive patients without left ventricular hypertrophy (LVH) and 10 hypertensive patients with significant LVH were evaluated. M-mode echocardiography was used to determine fractional shortening (FS), isovolumic relaxation time (IRT), and left ventricular filling volume during rapid and slow filling periods and the atrial contraction period (RFV, SFV, ACV). The quotients of the left ventricular filling volume and the end-diastolic volume and stroke volume were also calculated. Simultaneous biventriculography was used to determine the end-diastolic thickness of the interventricular septum and posterior wall. Right ventricular endomyocardial biopsies were performed to calculate the percentages of fibrosis. The FS was normal in all groups. The percentages of fibrosis in the two HT groups were significantly greater than those in the normals. The IRT of the HT groups was significantly greater, and the RFV, RFV/EDV and RFV/SV were significantly less than those of the normals. Multiple regression analysis showed that the wall thickness and the percentages of fibrosis correlated significantly with IRT, RFV, RFV/EDV and RFV/SV. The standard coefficients of correlation of wall thickness and the percentages of fibrosis were 0.333 and 0.239 in respect to IRT, and -0.304 and -0.473 in respect to RFV. There were significant correlations between the percentages of fibrosis and RFV (r = -0.675), RFV/EDV (r = -0.664) and RFV/SV (r = -0.602) in the normals and in cases of HT without LVH.(ABSTRACT TRUNCATED AT 250 WORDS)

Cardiac Catheterization↗
PubMed1988

A new technique for repair of mitral insufficiency caused by ruptured chordae of the anterior leaflet.

Prolapse of the anterior leaflet of the mitral valve is the result of ruptured chordae, elongated chordae, or elongated or ruptured papillary muscle. Several techniques have been described for the correction of mitral valve insufficiency. However, when there is severe rupture of the chordae, the most widely accepted solution is valve replacement. We describe a technique for the creation of a neochorda with a strip of tissue from the anterior leaflet of the mitral valve. This technique was used in two patients with severe mitral valve regurgitation. Formation of a neochorda and placement of a Carpentier ring to remodel the anulus obviated the need for a valve replacement. Both patients had an uneventful recovery. Studies performed 3 and 4 months postoperatively showed competent and well-functioning valves. One patient required a valve replacement for acute mitral insufficiency 5 years later, but the other patient was doing well 3 years after the operation. Despite the limited experience, we believe this technique offers a reasonable alternative to valve replacement.

Chordae Tendineae↗
PubMed1988

[Serial changes in left ventricular configuration and function in hypertrophic cardiomyopathy].

Fifteen patients, 12 males and three females, with hypertrophic cardiomyopathy (HCM) including three of obstructive type (HOCM) were investigated to observe the long-term course of HCM. Left ventriculography and bi-ventriculography were performed twice serially in all cases. We studied the correlations between the serial ECG changes, especially the negative T wave, and the left ventricular configuration, wall thickness, and left ventricular function. Serial ECG changes included: 1) negativity of the T wave which developed or increased concomitantly with increased voltages of SV1 + RV5 (A-1 group: five cases), 2) the negativity decreased or resolved with decreased voltages of SV1 + RV5 (A-2 group: four cases), and 3) insignificant changes of both T waves and SV1 + RV5 (B group: six cases). In the right oblique views at end-diastole, the configuration of the left ventricle was classified in three forms; (1) spade form (S), (2) round form (R), and (3) intermediate form (SR). The results were as follows: 1. The A-1 group showed increased thickness of the apical and anterior walls, but the thickness of the posterior wall and interventricular septal wall did not change serially. In three cases, the thickness of the interventricular septum showed mild hypertrophy at the initial and final observations. The configuration changed from the R or SR form to the S form. Diastolic dysfunction (peak dV/dt/V, peak dV/dt/EDV) was progressive, but end-diastolic volume and ejection fraction did not change. 2. The A-2 group showed the significantly decreased thickness of the apical and anterior walls. The thicknesses of the posterior wall and interventricular septal wall tended to decrease in all cases. In three cases (75%), the interventricular septal wall was markedly hypertrophied on the initial observation. The configuration changed from the S or SR form to the R form. Left ventricular diastolic function and ejection fraction decreased significantly and end-diastolic volume increased. Two cases showed clinical pictures of dilated cardiomyopathy at the final observation. 3. In the B group, there were no marked changes in wall thickness, left ventricular configuration, or systolic and diastolic functions. In conclusion, serial changes in left ventricular configuration, wall thickness, especially of the anterior and apical walls, and left ventricular function were all compatible with the serial changes of the ECG in hypertrophic cardiomyopathy.(ABSTRACT TRUNCATED AT 400 WORDS)

Adult↗
PubMed1988

[Regression of giant negative T waves in hypertrophic cardiomyopathy: cases simulating either dilated cardiomyopathy or severe coronary artery stenosis].

Two cases of hypertrophic cardiomyopathy (HCM), in whom giant negative T waves resolved during 10 years, are reported. Case 1: A 33-year-old man was admitted in 1975 for careful evaluation because of an ECG abnormality. The ECG revealed a giant negative T wave (GNT) in V5 (-15 mm) and high voltage (SV1 + RV5 = 81 mm). The thickness of the apical wall was 18 mm; the anterior wall, 12 mm; the posterior wall, 16 mm; and the interventricular septum, 17 mm on the left ventriculogram and biventriculogram. The coronary angiogram was normal. From these data, this patient was diagnosed as having HCM. However, follow-up studies disclosed resolution of the GNT with decreased high voltage (SV1 + RV5 = 26 mm). The catheterization performed in 1985 showed a decrease of wall thickness: the apical wall to 10 mm; the anterior wall, 9 mm; the posterior wall, 14 mm; and the interventricular septum, 14 mm. Ejection fraction was markedly decreased from 79.8% to 27.1%, and the wall motion was generally reduced. The coronary angiogram was normal. These findings resemble the clinical pictures of dilated cardiomyopathy (DCM). Case 2: A 58-year-old man was admitted in 1974 because of easy fatiguability. His ECG revealed a GNT in V4 (-10 mm) and high voltage (SV1 + RV5 = 75 mm). The patient was diagnosed as having HCM by cardiac catheterization, right ventricular biopsy and other procedures. In 1985, the depth of the GNT and the voltage of SV1 + RV5 regressed significantly (SV1 + RV5 = 26 mm). The thickness of the apical wall was, 12 mm; the anterior wall, 19 mm; the posterior wall, 13 mm; and the interventricular septum 14 mm during recatheterization. Coronary angiography disclosed stenoses of the left main trunk (75%), the left anterior descending artery (99%) and the left circumflex artery (50%). The right coronary artery was totally occluded. In conclusion, these two cases of HCM had similar changes in their ECG during long-term follow-up studies, but the process was different. One case finally showed clinical pictures of DCM; the other, severe coronary stenoses. These suggested that blood flow to the myocardium is an important determinant for the development of clinical features simulating DCM in cases with HCM.

Adult↗