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Biomedical subjects

K Manabe

Publications and source records attributed to K Manabe.

141 records · Page 8Linked to original sources
PubMed1974

Phytochrome-dependent Reduction of Nicotinamide Nucleotides in the Mitochondrial Fraction Isolated from Etiolated Pea Epicotyls.

When mitochondria isolated from etiolated pea (Pisum sativum cv. Alaska) epicotyls were exposed briefly to red light, their ability to reduce exogenous NADP was enhanced. The red light effect was reversed by far red light. Photoreversible absorbance changes between 730 nm and 800 nm were spectrophotometrically detected in the purified mitochondria and its membrane fraction. The dehydrogenase activity in the mitochondria was heat-labile and was dependent on the presence of magnesium ion and appropriate substrates such as glucose 6-phosphate, isocitrate, pyruvate, 6-phosphogluconate, and succinate. The photoreversible effect was seen only for a few minutes after the irradiation, and was cancelled by hypotonic treatment or addition of Triton X-100. A similar but lesser effect was observed in the pea microsome fraction, whereas no photoreversible response was seen with a supernatant fraction resulting from centrifugation at 10(5)g for 30 minutes.

Journal Article↗
PubMedDate not supplied

Comparison of antibody titer to human and rat acetylcholine receptor in myasthenia gravis.

Antibody titer to acetylcholine receptor (AChR Ab) was measured in 34 patients with myasthenia gravis (MG) using an immunoprecipitation method with human and rat AChR as antigens, to study the reliability of these assay systems and the cross-reactivity between human and rat AChR. There was a good correlation in the titer of Ab to AChR between human and rat (P < 0.01) when Ab titers were expressed logarithmically. The titer of Ab to human AChR was higher in a group of patients with a high concentration of AChR Ab and lower in a group with a low concentration of AChR Ab than that to rat AChR. This indicates that there may be distinctive characteristics in AChR Ab between groups of patients with high and low concentrations of AChR Ab.

Adolescent↗
PubMedDate not supplied

Transesophageal echocardiographic evaluation of mitral regurgitation in hypertrophic cardiomyopathy: contributions of eccentric left ventricular hypertrophy and related abnormalities of the mitral complex.

This study was designed to evaluate the contribution of eccentric left ventricular hypertrophy and its related organic and spatial abnormalities of the mitral complex to the occurrence of mitral regurgitation in patients with hypertrophic cardiomyopathy We selected 45 consecutive patients with systolic mitral regurgitation by color Doppler echocardiography and performed transesophageal echocardiography in all patients. Eighteen patients were in the obstructive group and 27 patients were in the nonobstructive group of hypertrophic cardiomyopathy with asymmetric septal hypertrophy. Twenty subjects without any cardiac disorders served as the control group. The maximum area of mitral regurgitation was significantly greater in the obstructive group than in the nonobstructive group. Mitral regurgitation appeared more frequently during pansystole in the two groups with hypertrophic cardiomyopathy, particularly in the obstructive group. Mitral valve prolapse was observed in 20 (44%) of the 45 patients with hypertrophic cardiomyopathy. Distances between the posterior papillary muscle and anterior or posterior mitral anulus were significantly smaller in the two groups with hypertrophic cardiomyopathy than in the normal control group. In the obstructive group, the length of the anterior mitral leaflet and the thickness of the rough zone of the anterior mitral leaflet at mid-diastole were significantly greater than in the other groups. Systolic anterior motion was observed in all patients with obstructive cardiomyopathy and contact between the interventricular septum and the anterior mitral leaflet during early diastole was observed in 17 of the 18 patients in the obstructive group.(ABSTRACT TRUNCATED AT 250 WORDS)

Cardiomyopathy, Hypertrophic↗
PubMedDate not supplied

Assessment of right-to-left shunt flow in atrial septal defect by transesophageal color and pulsed Doppler echocardiography.

To investigate the clinical significance and problems of right-to-left (R-L) shunt flow dynamics in atrial septal defects, we performed transesophageal color and pulsed Doppler echocardiography in 30 patients with atrial septal defects of the ostium secundum type. The 30 patients consisted of 20 with a pulmonary artery systolic pressure of less than 40 mm Hg, four with a pressure of 40 to 60 mm Hg, three with a pressure of 90 mm Hg or more, two patients with pulmonic stenosis, and one patient with Ebstein's anomaly. R-L shunting was determined by the presence of a shunt flow signal across the defect during each cardiac cycle. The time of R-L shunt flow was compared with the various parameters obtained by echocardiography and cardiac catheterization. R-L shunt flow signals were detected at the following times: (1) at the onset of ventricular contraction or the closing phase of the tricuspid valve in five patients with isolated atrial septal defect. These patients showed an increase of mean right atrial pressure but had no severe pulmonary hypertension; (2) during ventricular systole in five of 26 patients with tricuspid regurgitation and one patient with Ebstein's anomaly. The tricuspid regurgitant signal was directed toward the ostium of the defect in three patients and was massive in the other patients; (3) during middiastole in three patients without pulmonary hypertension. These patients showed massive left-to-right shunt flow from end systole to early diastole; and (4) during atrial systole in three patients with severe pulmonary hypertension and two patients with pulmonic stenosis. The former, in particular, showed the aliasing signal as a high-speed shunt flow. In two of the three patients with severe pulmonary hypertension, R-L shunting continued from atrial systole to early ventricular systole and was also observed in early diastole. R-L shunt flow was detected in patients with atrial septal defects not only with pulmonary hypertension but also without pulmonary hypertension and was influenced by the right atrial pressure in the phase of tricuspid valve closing, the volume or direction of tricuspid regurgitation, rebound flow caused by massive left-to-right shunt flow, the grade of right ventricular distensibility or the complication of pulmonary hypertension, and complications with other cardiac anomalies. Thus R-L shunt flow in patients with atrial septal defects was detected easily by transesophageal color and pulsed Doppler echocardiography because of the high efficiency of this method for its detection.

Adolescent↗
PubMedDate not supplied

Influence of aging on left atrial appendage flow velocity patterns in normal subjects.

Transesophageal pulsed Doppler echocardiography was performed to examine changes with age in the left atrial appendage flow velocity patterns in 50 normal subjects (15 to 80 years) in sinus rhythm. There was a significant negative correlation between the peak early diastolic forward and backward left atrial appendage flow velocities and age, as well as a significant positive correlation between the peak early diastolic forward left atrial appendage flow velocity and the peak early diastolic transmitral and pulmonary venous flow velocities. Although there was a significant positive correlation between the peak atrial systolic transmitral flow velocity and age, there was a negative correlation between the peak atrial systolic forward and backward left atrial appendage flow velocities and age. There was a positive correlation between both the maximum left atrial diameter and the amplitude of the interatrial septal motion during atrial systole and age. There was a significant negative correlation between the left atrial appendage ejection fraction during atrial systole and age. Left atrial appendage thrombi and spontaneous echo contrast were detected in two subjects with low peak early diastolic and atrial systolic left atrial appendage flow velocities. In conclusion, both peak early diastolic and atrial systolic left atrial appendage flow velocities decreased with age. A decrease in the peak atrial systolic flow velocity appeared to be an important sign of left atrial appendage thrombus formation even in normal elderly subjects in sinus rhythm.

Adolescent↗
PubMedDate not supplied

Influence of left atrial pressure on left atrial appendage flow velocity patterns in patients in sinus rhythm.

To examine changes in left atrial appendage flow velocity patterns in relation to left atrial pressures during sinus rhythm, transesophageal echocardiography and cardiac catheterization were performed in 31 patients with myocardial diseases in sinus rhythm and 20 control subjects without cardiovascular disease. The 31 patients were divided into two groups according to mean pulmonary capillary wedge pressure: the group with high wedge pressure (19.9 +/- 5.8 mmHg) and the group with low wedge pressure (8.6 +/- 2.9 mmHg). The left atrial appendage peak early emptying velocity was decreased significantly in the groups with both high and low wedge pressure compared with the control group. The left atrial appendage peak late emptying velocity was significantly greater in the group with low wedge pressure compared with the control group, whereas it was decreased significantly in the group, with high wedge pressure compared with the control group. The left atrial appendage peak late emptying velocity had a significant negative correlation with wedge pressure. The maximum left atrial appendage area at end systole in the group with high wedge pressure was significantly greater than that in both the group with low wedge pressure and the control group. There was a significant positive correlation between the maximum left atrial appendage area and the wedge pressure, as well as a significant negative correlation between the left atrial appendage ejection fraction during atrial contraction and the wedge pressure. In the group with high wedge pressure, one patient had evidence of left atrial appendage thrombi and two had spontaneous echo contrast. These results suggest that even in patients in sinus rhythm, a marked elevation in the left atrial pressure is likely to reduce the left atrial appendage peak early and late emptying velocities. These changes may be accompanied by an increased incidence of thrombus formation in the left atrial appendage compared with individuals with normal or only slightly elevated left atrial pressures.

Atrial Function↗
PubMedDate not supplied

Sleep patterns and mortality among elderly patients in a geriatric hospital.

BACKGROUND: Sleep disturbance is one of the major and unsolved problems in older people. Most of the previous sleep studies rely on self-reported documents, and memory disturbance in older people might bias sleep complaints and health status. OBJECTIVE: Sleep disturbances were studied as a mortality risk. METHODS: In 272 patients who were aged, infirmed and chronically institutionalized in a skilled-care geriatric hospital, the presence or absence of sleep disturbances were examined by hourly observations of patients over 2 weeks at baseline, and they were prospectively followed up for 2 years to assess mortality. RESULTS: Mortality after 2 years was significantly higher in the nighttime insomnia, daytime sleepiness, and sleep-onset delay groups. Further, adjusted for age, gender and activities of daily living status, the presence of nighttime insomnia and sleep-onset delay remained associated with a higher risk of mortality. CONCLUSION: Sleep disturbance may be one of the symptoms indicating poor health or functional deficits, and be an independent risk factor for survival.

Activities of Daily Living↗
PubMedDate not supplied

Transesophageal pulsed Doppler echocardiographic study of pulmonary venous flow in mitral stenosis.

For evaluation of pulmonary venous flow (PVF) in mitral stenosis, transthoracic and transesophageal echocardiography were performed in 33 patients with mitral stenosis and 20 normal controls. The peak systolic flow velocity of the PVF was significantly lower in patients with mitral stenosis and atrial fibrillation. The peak diastolic flow velocity of the PVF was significantly lower in the patients with mitral stenosis than in normal controls. The diastolic wave recorded as laminar flow in the mitral stenosis group showed a peak in the rapid filling phase with a gradually descending slope of velocity during mid to late diastole. There was a significant negative correlation between the peak diastolic flow velocity of the PVF and the pressure half time from transmitral flow obtained by continuous wave Doppler in the mitral stenosis group. These results demonstrate that evaluation of the PVF is helpful in understanding hemodynamic events between the left atrium and left ventricle in patients with mitral stenosis.

Adult↗
PubMedDate not supplied

[Changes in left ventricular inflow and pulmonary venous flow patterns during preload alteration in dilated heart].

Changes in left ventricular inflow (LVIF) and pulmonary venous flow (PVF) patterns during preload alteration were assessed in 30 patients with dilated heart, including 10 patients with dilated cardiomyopathy and 20 with old myocardial infarction. Transesophageal Doppler echocardiography was performed during lower body negative (LBNP, -40 mmHg) and positive pressure (LBPP, +40 mmHg) in all 30 patients and 20 normal controls. Eight of the 30 patients showed the "pseudonormalization (PN)" pattern, and 22 showed the "decreased early diastolic wave (E) and compensatorily increased atrial contraction wave (A) (N-PN)" pattern of LVIF in the control state. The diastolic wave (PVD) of the PVF and E of the LVIF were significantly higher, and the second systolic wave (PVS2) of the PVF and A of the LVIF were lower in the PN group than in the N-PN group. The amplitude of the atrial contraction wave (PVA) of the PVF in both groups of dilated heart patients was larger than in the normal group. The ratio of the amplitude of the atrial contraction wave to the total vertical deflection (A/H) of the apexcardiogram and mean pulmonary capillary wedge pressure (PCWP) in the PN group were greater than those in the N-PN group in the control state. LVIF in six of the 22 N-PN patients changed to the PN pattern during LBPP, and in three of eight PN patients changed to the N-PN pattern during LBNP. The six patients demonstrating the change from the N-PN to PN pattern showed a significant increase in PVD and PVA during LBPP compared with the control state, and a significant increase in PCWP in the control state compared with the 14 patients without a change in LVIF. Peak velocity of E in each group was decreased during LBNP and increased during LBPP, but peak velocity of A did not change during preload alteration. Peak velocity of PVS2 in the normal group was significantly decreased, and those of the PN and N-PN groups were decreased but not significantly during LBNP. The peak velocity of PVD was decreased during LBNP in the PN and N-PN groups, and the decrease was significantly higher in the former than in the latter.(ABSTRACT TRUNCATED AT 400 WORDS)

Adult↗