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Biomedical subjects

T Kumada

Publications and source records attributed to T Kumada.

At least 109 records · Page 6Linked to original sources
PubMed1992

[The signal transduction of serotonin secretion involves protein tyrosine phosphorylation in rat basophilic leukemia cells].

We investigated the signal transduction of serotonin secretion by stimulation with DNP-Ascaris antigen or ionomycin in rat basophilic leukemia cells (RBL-2H3). The modes of action of antigen and ionomycin for serotonin secretion were shown to be similar. The treatment of cells with antigen resulted in increased tyrosine phosphorylation of 105 and 72 KDa proteins, in particular, the tyrosine phosphorylation of 72 KDa protein seemed to correlate with serotonin secretion. Furthermore, we observed that antigen stimulation caused a marked increase in inositol polyphosphates production, which derived from the tyrosine phosphorylation of phospholipase C-gamma in RBL-2H3 cells. On the other hand, treatment with ionomycin also resulted in an increase in tyrosine phosphorylation of 72 KDa protein, but did not induce inositol polyphosphates production. These results suggested that the activation of tyrosine kinase may be related to serotonin secretion, and that intracellular Ca2+ increase may also play an important role in this activation.

Animals↗
PubMed1992

[New oral drugs for the treatment of congestive heart failure].

The crucial issues in the management of congestive heart failure (CHF) are improvement of depressed myocardial contractility and reduction of excessive load. For this purpose, positive inotropic agents and vasodilators have been developed as new oral drugs. The former include Denopamine which possesses beta 1 stimulating effect, Xamoterol which is a unique agent acting as a beta 1-partial agonist, and Ibopamine, Docarpamine and Phosphodiesterase Inhibitors which possess both inotropic and vasodilating effects and are called "Inodilators". The latter include Angiotensin Converting Enzyme Inhibitors. In addition, new vasodilators, such as, Vasopressin Antagonist have also been developed. However, careful long-term clinical trials are required with regard to the efficacy and adverse effects before these agents are widely used with safety in the management of CHF.

Administration, Oral↗
PubMed1992

[The pitfalls in the clinical diagnosis of dissecting aortic aneurysm].

It is sometimes very difficult to diagnose dissecting aortic aneurysms (DAA), particularly in its early stage, due to manifold signs and symptoms. The purpose of this study is to clarify the reasons for such erroneous diagnoses. A total of 41 patients with DAA were referred to our hospitals for further examination and/or surgery from April 1986 to August 1989. In 18 of these patients, the diagnostic possibility of an underlying DAA was overlooked by the referring physicians. Among these 18 patients, 2 were mistakenly diagnosed as uncomplicated myocardial infarction (MI), one as pneumonia, 2 as cerebral infarction, 6 as acute abdominal disease, one as cholelithiasis, 5 as thrombosis of the lower extremities, and one as malignant metastasis to the pericardium. The following is the detail: In 2 cases thought to be uncomplicated MI, an expanding dissecting ascending aorta had crushed the lumen of the left coronary artery, causing MI, in turn, wasting clinical treatment and consuming precious time. In one case, enlargement of the descending aorta on the chest radiography was overlooked and the patient's symptoms were mistakenly attributed to pneumonia. In 2 cases in which symptoms of cerebral ischemia were thought to be attributed to cerebral thrombosis, the real cause turned out to be occlusion of the brachiocephalic artery following aortic dissection. Among 6 cases which were initially considered to have only acute abdominal disease, 3 presented with symptoms and signs of ileus, and their exploratory laparotomies yielded no positive findings.(ABSTRACT TRUNCATED AT 250 WORDS)

Aged↗
PubMed1991

Effect of ticlopidine and other antithrombotics on the venous thrombosis induced by endothelial damage of jugular vein in rats.

A venous thrombosis model was produced by vessel wall damage generated by freezing a small segment of the rat jugular vein. The process of thrombus formation was investigated by electron microscopic study. Ultrastructural studies demonstrated that the initiation of thrombus formation could be deendothelialization caused by freezing of vessel. When blood flow was reestablished, platelets adhered to subendothelium within 1 min. Then platelets aggregated on the adhering platelets, and fibrin net was formed. Finally, thrombi composed predominantly of fibrin and red blood cells with platelet aggregates and leukocytes were generated. An anti-platelet agent, ticlopidine, revealed a potent antithrombotic effect in this model. Because ticlopidine decreased the number of platelet aggregates, reduced the size of aggregates, and inhibited platelet degranulation, it is conceivable that platelet aggregation in early phase of thrombus formation plays a crucial role even in venous thrombosis model. A synthetic thrombin inhibitor, argatroban, also showed a potent antithrombotic effect, but a thrombolytic agent, urokinase, was less effective. In conclusion, this model is both platelet- and coagulation-dependent.

Animals↗
PubMed1991

Importance of left ventricular systolic function in the assessment of left ventricular diastolic function with Doppler transmitral flow velocity recording.

To study the effect of left ventricular systolic function on the Doppler transmitral flow velocity pattern, Doppler echocardiographic variables were correlated with hemodynamic indexes in 11 control subjects and 58 patients with heart disease. All underwent cardiac catheterization performed with use of a Millar micromanometer. The time constant of left ventricular isovolumetric pressure decrease and left ventricular end-diastolic myocardial stiffness was calculated. The 58 patients were classified into two groups according to ejection fraction: group I (n = 30; ejection fraction greater than 55%) and group II (n = 28; ejection fraction less than 50%). Compared with the control subjects, patients in group I had impairment only of left ventricular relaxation (time constant 47 +/- 9 vs. 38 +/- 3 ms; p less than 0.01), whereas patients in group II had, in addition to impaired left ventricular relaxation (time constant 52 +/- 11 vs. 38 +/- 3 ms; p less than 0.01), increased preload, increased pulmonary capillary pressure (12 +/- 8 vs. 5 +/- 3 mm Hg; p less than 0.01) and increased myocardial stiffness (2,018 +/- 980 vs. 1,050 +/- 218 g/cm2; p less than 0.01). In group I, there was a significant partial correlation coefficient between the time constant and deceleration half-time (r = 0.54). In group II, a strong correlation existed between myocardial stiffness and peak atrial filling velocity (r = -0.71) and between myocardial stiffness and the ratio of peak atrial to peak rapid filling velocity (r = -0.71).(ABSTRACT TRUNCATED AT 250 WORDS)

Blood Flow Velocity↗
PubMed1991

Left ventricular regional relaxation and its nonuniformity in hypertrophic nonobstructive cardiomyopathy.

BACKGROUND: Regional nonuniformity has been suggested to be closely related to left ventricular (LV) relaxation in diseased heart. The purpose of the present study was to assess LV global and regional relaxation in patients with nonobstructive hypertrophic cardiomyopathy (HCM). METHODS AND RESULTS: Left ventriculography was conducted simultaneously with pressure micromanometry in 10 normal control subjects and 11 patients with nonobstructive HCM. LV silhouettes in the right anterior oblique projection were divided into eight regions, and regional wall stress during isovolumic relaxation was computed for six regions from the midventricle to the apex. In HCM patients, isovolumic relaxation time (IRT) and the time constant of LV pressure decrease (Tp) were greater than in control subjects (IRT, 84 +/- 13 versus 66 +/- 6 msec; Tp, 51 +/- 8 versus 36 +/- 5 msec, respectively; p less than 0.01). In HCM patients, the (-)dP/dt upstroke pattern was convex-downward, and dP/dt(20/60), the ratio of dP/dt values 20 and 60 msec after peak (-)dP/dt, was less than in control subjects (1.46 +/- 0.16 versus 2.15 +/- 0.14, p less than 0.01). These findings suggest that there is impaired LV relaxation in HCM patients. End-systolic regional wall stress was lower, and the time constant of regional stress decrease (Tst) was prolonged for each region in HCM patients compared with control subjects. In the HCM group, Tst tended to be more prolonged in regions with increased wall thickness than in regions with normal wall thickness (60 +/- 15 versus 50 +/- 11 msec, p less than 0.01). The coefficient of variation for Tst values in six areas of the left ventricle was calculated in each subject and was greater in HCM patients than in control subjects (13 +/- 7% versus 7 +/- 3%, p less than 0.05), indicating regional nonuniformity in Tst during isovolumic relaxation in HCM patients. CONCLUSIONS: Significant correlations existed between the coefficients of variation for Tst and Tp (r = 0.80, p less than 0.01), IRT (r = 0.79, p less than 0.01), and dP/dt(20/60) (r = -0.67, p less than 0.05) in the HCM group. Thus, regional nonuniformity is closely related to the impairment of LV relaxation in HCM.

Cardiac Catheterization↗
PubMed1991

Hemodynamic efficacy of E-1020 in comparison with dopamine on acute mitral regurgitation in anesthetized dogs.

To evaluate the effects of a new phosphodiesterase inhibitor, E-1020 (1, 2-dihydro-6-methyl-2-oxo-5-(imidazo [1, 2-a] pyridin-6-yl)-3-pyridine carbonitrile hydrochloride monohydrate), on cardiovascular hemodynamics in acute heart failure, we compared its effects with those of dopamine on experimentally produced acute mitral regurgitation in dogs. After the production of mitral regurgitation by transmyocardial chordal sectioning and obtaining a stable state, dopamine (5 micrograms/kg/min) was infused until the peak positive dP/dt (peak (+) dP/dt) increased to about 50% of the predopamine value. After complete recovery, E-1020 (30 micrograms/kg) was infused over 5 min and the data were obtained 10 min later. Both drugs equally increased peak (+) dP/dt, decreased systemic vascular resistance, and increased cardiac output. Left ventricular (LV) end-diastolic pressure, LV end-diastolic segment length (EDL), and mean left atrial (LA) pressure decreased with both drugs. The changes in EDL and mean LA pressure were larger with E-1020 than with dopamine (p less than .01 and p less than .05). Although mean inferior vena caval blood flow volume (mIVCF) increased and mean inferior vena caval pressure decreased with both drugs, the increment of mIVCF was smaller with E-1020 (p less than .001). Thus, E-1020 had not only a positive inotropic effect but also a vasodilatory action both on resistance vessels and on capacitance vessels.

Acute Disease↗
PubMed1990

[Catheterization for reservoir implantation by puncturing the left axillary artery directly under ultrasound guidance].

We presented a new method of catheter implantation by puncturing the left axillary artery directly under ultrasound guidance. This method was easy and non-invasive comparing with previous methods. Fifteen patients with advanced cancers were treated with infusion chemotherapy using this method and no severe complication was observed. Therefore, it was considered that our new procedure was beneficial for the management of patients with advanced cancers.

Adult↗
PubMed1990

Effects of the partial beta 1-adrenergic agonist, xamoterol, on hemodynamics and regional myocardial function during acute coronary occlusion in dogs.

Xamoterol is a partial beta 1-adrenergic agonist that has combined beta 1-stimulating and beta 1-blocking actions. We studied the effects of xamoterol on hemodynamics and regional left ventricular (LV) function after circumflex coronary artery occlusion in eight anesthetized dogs. Left ventricular systolic wall thickening (%WT: sonomicrometry) was measured in nonischemic, marginal, and ischemic zones. Xamoterol (350 micrograms/kg i.v.) increased the maximum LV pressure (dP/dt) by 62% and aortic flow (AOF) by 52% and decreased LV end-diastolic pressure (EDP) but did not change heart rate (HR) and peak LV pressure (LVP). Xamoterol increased %WT in nonischemic (23.6 +/- 2.3 to 35.1 +/- 2.6%, p less than 0.05) and marginal (5.0 +/- 0.6 to 12.0 +/- 1.5%, p less than 0.05), but not in the ischemic region [-5.7 +/- 0.7 to -2.7 +/- 0.3%, not significant (NS)]. The beta 1-blocking action of xamoterol was evaluated. Xamoterol significantly attenuated the increase in HR and maximum dP/dt caused by isoproterenol (0.1 microgram/kg/min). %WT in each region was maintained at the level caused by xamoterol after isoproterenol. Thus, xamoterol improved cardiac function, yet prevented excessive stimulation by catecholamine in the presence of acute myocardial ischemia.

Acute Disease↗
PubMed1990

Left ventricular regional wall stress in dilated cardiomyopathy.

Left ventriculography with simultaneous pressure micromanometry was performed in 11 normal control subjects and 17 patients with dilated cardiomyopathy (DCM). Left ventricular silhouettes in the right anterior oblique projection were divided into eight areas, and regional wall stress was computed by Janz's method in each area excluding the two most basal areas. Wall stress was higher in DCM patients than in control subjects (p less than 0.01). The percent area changes from end diastole to end systole in each area were lower in DCM patients than in control subjects (mean for six areas, 22 +/- 14% versus 54 +/- 9%, respectively, p less than 0.01), but the coefficient of variation for the percent area changes in the six areas of the left ventricle in DCM patients was greater than that in control subjects (32 +/- 17% versus 15 +/- 4%, respectively, p less than 0.01), indicating regional differences in hypokinesis. There was a significant negative correlation between end-systolic regional wall stress and percent area change (r = -0.60 to -0.86, p less than 0.05) in each area. Thus, excessive regional afterload may play an important role in causing regional hypokinesis in DCM.

Cardiomyopathy, Dilated↗
PubMed1990

[Transesophageal Doppler echocardiography in the diagnosis of atrial septal defect].

To assess the usefulness of transesophageal Doppler echocardiography (TEE) in diagnosing atrial septal defect (ASD), we studied eight cases with secundum type ASD, in which the diagnosis was confirmed by cardiac catheterization and surgery. In all cases, TEE provided clear images of the interatrial septum with its defect. Shunt flow through the defect was observed by color Doppler technique, and its velocity was measured using the FFT mode. In two cases, right-to-left shunt blood flow was detected. Two types of probes were used in this study, a lateral scanning probe and a longitudinal scanning probe. The scanning plane of the former was perpendicular to the axis of the probe, and that of the latter was parallel to it. The two probes facilitated the measurement of the two right-angled dimensions, with which we could calculate the defect area, assuming the defect to be an ellipse. The volume of a left-to-right shunt was obtained by multiplying the defect area by the integration of flow velocity against time. Shunt volume per cardiac cycle obtained by this method correlated well with that obtained by the Fick's method during cardiac catheterization. In six cases without a right-to-left shunt, the coefficient of correlation was 0.98, and in all eight cases it was reduced to 0.72. Thus, we concluded that TEE is useful for diagnosing and evaluating ASD.

Adolescent↗
PubMed1990

[Clinical usefulness of transesophageal Doppler echocardiography].

The usefulness of transesophageal Doppler echocardiography (TEE) was assessed in patients with various cardiovascular diseases including 15 patients with dissecting aortic aneurysm (DAA), two with thoracic aneurysm, 16 with ischemic heart disease and 14 with acquired valvular diseases. In dissecting aortic aneurysms, TEE provided clear images of the intimal flaps even in the aortic arch and descending aorta in which clear images could not be obtained by conventional external Doppler echocardiography. The entry site was detected in 11 of the 15 (73%) cases using TEE, but in only three of the 15 cases using conventional Doppler technique. In two cases of true aortic aneurysms, TEE provided clear images of the aneurysm in the descending thoracic aorta, which was discriminated precisely from DAA. In valvular disease, all four valves (aortic, pulmonary and atrio-ventricular valves) were easily observed without disturbance by any other tissues using a transesophageal approach. In addition, valve aneurysms in the posterior mitral leaflets were detected using TEE in two cases. In two cases of mitral stenosis, a thrombus was observed in the left atrial appendage. These findings were confirmed during surgery, but could not be obtained by the conventional external studies. In 16 cases, TEE was performed during aorto-coronary bypass surgery under general anesthesia. In two of these cases, left ventricular assist devices were applied after surgery. In these cases, where conventional Doppler echocardiography was not applicable, cardiac function could be monitored by TEE. Thus, TEE is useful not only in evaluating morphological function in the cardiovascular system but also in monitoring cardiac hemodynamics during and after heart surgery.

Adult↗
PubMed1990

A clinical and cytogenetic study of institutionalized mental retardates.

One hundred and four out of 110 patients in a residential institution for mental retardates were examined clinically and cytogenetically. Both conventional and folate deficient media were employed in order to detect both conventional chromosomal abnormalities and rare fragile sites. Conventional abnormalities were detected in 18 cases (17%). Rare folate sensitive fragile site at 2q13 was detected in one female patient. The same chromosomal aberration was also detected in the patient's mother who had a normal phenotype. Spontaneous expression of the rare fragile site at 2q13 was also observed.

Adolescent↗
PubMed1990

[Pathophysiological analysis of cardiac function by computer processing of echocardiograms].

Automatic image processing system has been developed for analysis of cardiac function with echocardiograms. Echograms of apical long axis view were transferred to microcomputer system and processed to display three dimensional images of left ventricular myocardium. With this technology, analysis of left ventricular wall thickness in three dimensional manner revealed pathophysiological changes in ischemic heart disease.

Coronary Disease↗
PubMed1990

Autosomal fragile site at 2q13 in a proband with mental retardation.

Folate sensitive fragile site on chromosome 2q13 was detected in a female proband with mild hypertrichosis, negativism, speech disorder, and severe mental retardation. The same chromosomal aberration was also detected in her mother with normal phenotype. Spontaneous expression of fragile site on 2q13 was also observed.

Adult↗