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Biomedical subjects

K Miyatake

Publications and source records attributed to K Miyatake.

At least 109 records · Page 6Linked to original sources
PubMed1998

Prognostic factors of small-cell lung cancer in Okayama Lung Cancer Study Group Trials.

In order to elucidate factors influencing the prognosis of small-cell lung cancer (SCLC), we reviewed the records of 253 patients with SCLC and evaluated 20 pretreatment prognostic factors by univariate analysis and Cox's multiple regression analysis. Recursive partitioning and amalgamation (RPA) was employed to identify subgroups with similar survival rates. Cox's multiple regression analysis identified five significant factors: extent of disease, number of metastatic sites, serum albumin, serum lactate dehydrogenase, and presence of weight loss. Among these, extent of disease was the most influential factor. RPA analysis revealed three subgroups predicting significantly different prognoses. The median survival time and 3-year survival rate were 18.4 months and 20.6%, respectively for the good-risk group (limited disease without weight loss), 13.5 months and 9.1%, respectively for the intermediate-risk group (limited disease with weight loss or extensive disease with less than two metastatic sites), and 9.2 months and 0%, respectively for the poor-risk group (extensive disease with two or more metastatic sites). These results will be useful for development of new staging system or subsequent stratification for randomized trials.

Aged↗
PubMed1998

Effects of CO2 and O2 concentrations and light intensity on growth of microalgae (Euglena gracilis) in CELSS.

Green microalgae are likely to play an important role in bioregenerative systems for producing food and converting CO2 to O2 in a controlled ecological life support system (CELSS). In the present study, a method for evaluating the effects of environmental variables on the multiplication rate of microalgal cells was developed to determine the optimum culture condition for a microalgal culture system that can function effectively in the CELSS. The microalga, Euglena gracilis, was cultured in water droplets (3 microliters in liquid volume each) in a vessel (25 ml in air volume) in which the CO2 and O2 concentrations were controlled. The number of Euglena cells cultured at CO2 concentrations ranging from 2% to 6%, O2 concentrations ranging from 5% to 20%, and PPF levels ranging from 50 to 100 micromoles m-2 s-1 was monitored by using a video camera and a microscope. The multiplication rate of cells was highest and the cell number increased by 8.3 times during 48 h under a condition of 4% CO2, 21% O2 and 100 micromoles m-2 s-1 PPF. The multiplication rate of the cells was highest at 4% CO2, followed by 6% and 2% CO2, and it decreased with decreasing O2 concentration and decreasing PPF.

Animals↗
PubMed1998

[Experience of weaning from left ventricular assist system in an acutely-ill patient with dilated cardiomyopathy and severe left ventricular dysfunction: a case report].

A 21-year-old man with dilated cardiomyopathy recovered from terminal heart failure with the long-term use of the left ventricular assist system (LVAS). His heart failure was refractory to maximum medical therapy including beta-blockade and intravenous catecholamines. Application of LVAS restored renal and hepatic function and even cardiac function. Left ventricular size decreased from 79 to 57 mm, and cardiac index increased from 1.6 to 2.2 l/min/m2. After 6 weeks of LVAS application, he could walk in the ward and could start exercise on a bicycle ergometer 3 months after. Ninety-five days after implantation, the LVAS could be removed. His general condition remained good and stable for more than a year after the removal of the LVAS. Timely application of LVAS seems to be one of the most important factors for successful circulatory support. Detailed criteria for LVAS application are not established yet.

Adult↗
PubMed1998

[Evaluation of cardiac function by various cardiac imaging techniques in mitochondrial cardiomyopathy: a case report].

A 39-year-old man with cardiomyopathy due to point mutation of mitochondrial DNA(3243) was admitted to our hospital because of exertional dyspnea accompanied by hearing disturbance and diabetes mellitus. Echocardiography revealed asymmetric hypertrophy of the anterolateral and posterior walls and systolic dysfunction of the left ventricle (fractional shortening = 18%). Pulsed Doppler mitral inflow velocity wave showed a pseudonormalized pattern. Iodine-123 betamethyl-p-iodophenyl-pentadecanoic acid (123I-BMIPP) myocardial scintigraphy showed decreased accumulation in the anterolateral, posterior, and apical walls. Left ventriculography showed moderately decreased ejection fraction (43%), and left ventricular end-diastolic pressure was mildly elevated (18 mmHg). Angiography showed normal coronary arteries, but coronary flow reserve measured by administering intravenous adenosine triphosphate was impaired in the left anterior descending and left circumflex arteries compared to the right coronary artery. Intracellular accumulations of abnormal mitochondria were detected by histologic examination of the cardiac and skeletal muscles. Evaluation of cardiac function showed that the area of myocardial hypertrophy was nearly consistent with the region of decrease in 123I-BMIPP accumulation and coronary flow reserve.

Adult↗
PubMed1998

[Precipitating factors in patients with repetitive exacerbation of chronic left heart failure].

The precipitating factors of repetitive exacerbation were investigated in 110 consecutive patients with chronic left heart failure admitted due to acute exacerbation more than twice to the medical emergency ward of National Cardiovascular Center from January, 1992 to December, 1996. The controls were 189 consecutive patients with chronic left heart failure admitted to the ward due to acute exacerbation only once during the same period. Excessive intake of water or sodium, overwork and infection were common precipitating factors in the first decompensation of left heart failure, but the former two factors became less common with repeated admission. Patient mistakes such as excessive intake of water or sodium, overwork and noncompliance with medications, and new onset arrhythmias were common precipitating factors in patients (n = 13) admitted to the ward more than four times. Infection was a common precipitating factor (63%) in patients with a time interval between readmission and the last discharge of longer than 2 years. Despite repeated admission, infection was a common precipitating factor in patients with valvular heart disease (n = 31), patient mistakes were common in heart disease with left ventricular hypertrophy (n = 20), and infection and new onset arrhythmias were common in dilated cardiomyopathy (n = 28) and old myocardial infarction (n = 31). Patient mistakes and new onset arrhythmias were the common factors that led to repetitive exacerbation of left heart failure, and precipitating factors were characterized by the etiology of left heart failure.

Aged↗
PubMed1998

[Effectiveness of surgical repair of mitral regurgitation concomitant with dilated cardiomyopathy].

Dilated cardiomyopathy (DCM) is often accompanied by severe mitral regurgitation (MR) which deteriorates the clinical course. Mitral reconstruction for severe MR may improve the symptoms and prognosis. Five patients with DCM and one patient with dilated phase of hypertrophic cardiomyopathy underwent mitral reconstruction for severe MR (4 males, 2 females, mean age 50 +/- 17 years) from 1983 to 1995. Their New York Heart Association (NYHA) functional class and findings of echocardiography and cardiac catheterization were compared before and after surgery. Five patients underwent annuloplasty and one patient underwent mechanical valve replacement. There was no operative or in-hospital death. NYHA class improved from 3.2 to 1.8 (p < 0.05). The degree of MR was reduced from 3.5 to 1.2 (p < 0.05), and left ventricular end-diastolic pressure decreased from 18 +/- 7 to 13 +/- 8 mmHg (p < 0.05). Left ventricular fractional shortening, ejection fraction and cardiac index (2.4 +/- 0.4 to 2.7 +/- 1.1 l/min/m2) did not change significantly. Two patients died within one year due to exacerbation of congestive heart failure (2.5 month later) or sudden death (6 months later). Three patients died at 21 months, 5 and 8 years after the operation (renal insufficiency, heart failure, sudden death, respectively). Mitral reconstruction improved the symptoms in patients with DCM and severe MR in the short term. However, 5 of 6 patients died in the intermediate or long-term. Mitral reconstruction may be a therapeutic option for early outcome in patients with refractory congestive heart failure due to DCM and severe MR.

Adult↗
PubMed1998

[Relationship between apoptosis-related markers and cardiomyopathy].

Increasing interest has been focused on the role of apoptosis in pathogenesis of idiopathic cardiomyopathy. Interactions between soluble Fas, tumor necrosis factor-alpha (TNF-alpha) and Fas ligand have been reported to play a pivotal part in signal transduction of apoptosis. Thus, we measured serum levels of apoptosis-related markers, namely sFas, TNF-alpha and two types of its receptor TNF-RI and TNF-RII in the patients with idiopathic cardiomyopathy. Serum level of TNF-alpha was higher in dilated cardiomyopathy (DCM) group as well as in hypertrophic cardiomyopathy (HCM) group than in the control group. There were significant correlation among TNF-alpha, TNF-RI and TNF-RII in DCM group. However, only slight tendencies among these parameters in HCM group, indicating different pathogenesis from DCM. No transcardiac production of TNF-alpha, TNF-RI and TNF-RII was found in cardiomyopathies in the present study. These data suggested that apoptosis-related markers could be used for the detailed classification of cardiomyopathy. Furthermore, the simultaneous measurement of receptors and their ligands of apoptosis-related markers might underscore clinical implications.

Apoptosis↗
PubMed1997

Usefulness of low doses of atropine to quantify the vagal stimulus-response relation in patients with congestive heart failure.

The response of low doses of atropine is reported to be attenuated in patients with congestive heart failure (CHF). Judging from the main site of action of low doses of atropine, we may be able to assess the functional state of the vagal center in the central nervous system. This study examines the clinical significance of heart rate (HR) response to a low dose of atropine in patients with CHF. Low and high doses of atropine were administered intravenously in 72 patients with CHF. HR after a low (parasympathomimetic) dose injection was assessed by the ratio Rm (minimal HR/basal HR), and after a high (parasympatholytic) dose by the ratio R1 (augmented HR/basal HR). Rm and R1 were related to indexes of CHF. Rm increased with progression of CHF (0.92 +/- 0.03 in New York Heart Association functional class I, 0.98 +/- 0.05 in class II, and 1.00 +/- 0.04 in class III). It also correlated with ejection fraction (r = -0.48, p <0.01) and more importantly, with peak oxygen uptake (r = -0.59, p <0.01). R1 exhibited weak correlation with basal HR (r = -0.33, p <0.05) and ejection fraction (r = 0.31, p <0.05), but had no correlation with other indexes. The vagal center may be already blunted in New York Heart Association class II with respect to increased Rm, which may be related to depressed exercise capacity. A low dose of atropine injection offers a simple and safe method for providing important information on the functional state of the vagal center in the central nervous system in patients with CHF.

Adult↗
PubMed1997

Intravascular ultrasonic evidence for importance of plaque distribution (eccentric vs circumferential) in determining distensibility of the left anterior descending artery.

Although previous studies have shown that coronary atherosclerosis is accompanied by impaired vessel wall compliance, few data exist regarding the regional vessel distensibility that may be important in order to gain an insight into the mechanism of atherosclerotic plaque rupture. Therefore, we analyzed 45 coronary sites of the proximal left anterior descending artery from 40 patients. Using intravascular ultrasound, luminal area in diastole (A) and in systole was measured at the diseased sites. With the ratio of luminal area changes (dA) to coronary pressure changes (dP) during a cardiac cycle, the total distensibility index was obtained by the formula: [(dA/A)/dP] x 10(3). At the sites with noncircumferential disease perimeters in diastole (L) and in systole were measured at the normal and narrowed portions. Using the changes in perimeters (dL) during a cardiac cycle, the regional distensibility index was obtained by the formula: [(dL/L)/dP] x 10(3). In 22 sites with circumferential disease, the total distensibility index was 1.03 +/- 0.61/mm Hg (mean +/- SD), and significantly lower than that from 23 sites with noncircumferential disease that showed 1.45 +/- 0.89/mm Hg (p <0.05). In noncircumferential disease, the regional distensibility index at narrowed portions was significantly lower, 0.33 +/- 0.47/mm Hg, than that at normal portion, 1.11 +/- 0.75/mm Hg (p <0.01), suggesting the heterogenous distribution of regional wall distensibility in noncircumferential lesions. These results indicate that the heterogeneous regional wall distensibility exists at the sites with noncircumferential disease where the total vessel distensibility is preserved by the presence of the compliant normal portion.

Adult↗
PubMed1997

Oscillation of ADP-ribosyl cyclase activity during the cell cycle and function of cyclic ADP-ribose in a unicellular organism, Euglena gracilis.

In Euglena gracilis, the activity of ADP-ribosyl cyclase, which produces cyclic ADP-ribose, oscillated during the cell cycle in a synchronous culture induced by a light-dark cycle, and a marked increase in the activity was observed in the G2 phase. Similarly, the ADP-ribosyl cyclase activity rose extremely immediately before cell division started, when synchronous cell division was induced by adding cobalamin (which is an essential growth factor and participates in DNA synthesis in this organism) to its deficient culture. Further, cADPR in these cells showed a maximum level immediately before cell division started. A dose-dependent Ca2+ release was observed when microsomes were incubated with cADPR.

ADP-ribosyl Cyclase↗
PubMed1997

Usefulness of myocardial velocity gradient derived from two-dimensional tissue Doppler imaging as an indicator of regional myocardial contraction independent of translational motion assessed in atrial septal defect.

Independence of myocardial velocity gradient from translational motion of the heart was tested by comparing normal subjects and patients with atrial septal defect. Myocardial velocity gradient obtained from patients fit within the normal range, even though the translation of the left ventricle was exaggerated in patients, demonstrating the translation independence of myocardial velocity gradient in clinical settings.

Adolescent↗
PubMed1997

Attenuated inhibition of adrenergic contraction by nitric oxide in injured guinea pig femoral artery.

The present study aimed to examine the altered modulation of adrenergic contraction by nitric oxide and sensory neuropeptides in balloon-injured muscular artery. A guinea pig femoral artery (GPFA) was injured by a newly developed silastic microballoon catheter. The contralateral GPFA served as the control. The studied GPFAs consisted of six groups; control (C) and injured (I) GPFA, isolated at 0 days, and 2 and 8 weeks after injury (C0, I0, C2, I2, C8, and I8). Isometric tension was measured in the presence of indomethacin (10(-5) M), to exclude effects of cyclooxygenase-generated eicosanoids. Endothelial removal with the catheter was confirmed by histological examination. In each group, except for 10, NG-nitro-I-arginine methyl ester (L-NAME, 10(-6) M) induced significant augmentation of perivascular nerve stimulation (PNS)-evoked adrenergic contraction, which was blocked by L-arginine (3 x 10(-4) M). The degree of L-NAME augmentation in I8 was significantly smaller than that in C8 and I2. Capsaicin (10(-6) M) did not significantly affect PNS-contraction in any group, indicating that there was no sensory neuropeptide involvement in this contraction. In I8, acetylcholine (10(-6) M)-induced relaxation after noradrenaline (10(-5) M)-precontraction was significantly smaller than that seen in the other groups, except for I0, which was lacking in acetylcholine-induced relaxation. Histologically, injured GPFAs showed progressive intimal thickening. The present findings thus showed attenuated nitric oxide-mediated inhibition of adrenergic contraction, accompanying intimal thickening, in balloon-injured muscular artery, 8 weeks after injury.

Acetylcholine↗
PubMed1997

Extension of hemorrhage after reperfusion of occluded coronary artery: contrast echocardiographic assessment in dogs.

OBJECTIVES: The aim of this study was to elucidate the progression of intramural hemorrhage complicated by reperfusion with the use of myocardial contrast echocardiography. BACKGROUND: Although hemorrhagic infarction is known to occur in ischemia followed by reperfusion, its onset and sequence have not been well characterized. METHODS: In 20 anesthetized dogs, 3-h occlusion of the left circumflex-coronary artery was followed by reperfusion. The area at risk during coronary occlusion was approximately 25%. Myocardial contrast echocardiogram was examined, and the time-intensity curves for both ischemic and nonischemic areas were obtained at baseline, at 3 min after reperfusion and then at 15-min intervals until 90 min after reperfusion. The wall thickness of both areas was also measured. RESULTS: Gross hemorrhage in the reperfused areas was observed in five dogs (Group H) but not in seven dogs (Group NH). All wall segments were opacified at 3 min after reperfusion in both groups. However, the contrast defect spread significantly with time after reperfusion in Group H but not in Group NH (18.7 +/- 3.4% and 3.3 +/- 1.8%, respectively, at 90 min after reperfusion p < 0.005). The wall of the risk area at 90 min after reperfusion had thickened to 1.3 times baseline thickness in Group H but was unchanged in Group NH. The other eight dogs were excluded from study because of fatal arrhythmias or the existence of collateral circulation during coronary occlusion. CONCLUSIONS: Both progression of the contrast defect area on myocardial contrast echocardiography and a gradual thickening of the wall with reperfusion are characteristic of hemorrhagic infarction.

Animals↗
PubMed1997

Functional myocardial perfusion abnormality induced by left ventricular asynchronous contraction: experimental study using myocardial contrast echocardiography.

OBJECTIVES: The aim of this study was to clarify how myocardial perfusion is impaired by asynchronous contraction. BACKGROUND: False septal hypoperfusion is noted in some patients with left bundle branch block. METHODS: Eight dogs were examined with epicardial pacing at the left ventricular posterior wall, the right ventricular anterior wall and, as a control, the right atrial appendage. The pacing rate was 80, 110 and 150 beats/min (bpm). Myocardial perfusion was assessed by contrast echocardiography. RESULTS: Left ventricular pacing at 80 and 110 bpm did not change systolic wall thickening or contrast intensity at the pacing site, although an early excitation notch was noted at the pacing site. However, at 150 bpm, systolic thickening was impaired (23.3 +/- 4.2% vs. 37.0 +/- 2.6% during atrial pacing, p < 0.05), and the peak intensity ratio of the pacing site to the ventricular septum was significantly decreased (24.1 +/- 5.7% vs. 37.0 +/- 2.8% at a pacing rate of 80 bpm, p < 0.01). The peak intensity ratio correlated with systolic wall thickening at the pacing site (y = 0.413 x -0.028, r = 0.81, p < 0.0001). However, right ventricular pacing did not change either systolic thickening or the peak intensity ratio at any pacing rate, although an early excitation notch was noted on the ventricular septum. CONCLUSIONS: Wall motion abnormalities after early excitation vary depending on the pacing mode. When tachycardia induces regional wall motion abnormalities, the ventricular wall of the pacing site is functionally hypoperfused.

Animals↗
PubMed1997

Inositol 1,4,5-trisphosphate and cyclic ADP-ribose mobilize Ca2+ in a protist, Euglena gracilis.

Inositol 1,4,5-trisphosphate (InsP3) and cyclic ADP-ribose (cADPR) released Ca2+ from microsome fraction prepared from Euglena gracilis in dose-dependent manners. Caffeine, which also induced Ca2+ release from the microsomes, caused desensitization of the Ca2+ response to cADPR, although the Ca2+ response to InsP3 was not affected by caffeine. Further, ruthenium red inhibited the Ca2+ release induced by cADPR, but not by InsP3. These results suggest that cADPR functions as an endogenous messenger to activate a caffeine-sensitive, Ca(2+)-release mechanism, whereas InsP3 induces Ca2+ release by a distinct mechanism in E. gracilis.

Adenosine Diphosphate Ribose↗
PubMed1997

An enhanced method for measuring cardiac output using Doppler color flow echocardiography.

An enhanced method for determining cardiac output using Doppler color flow imaging techniques to measure mitral orifice diameter was developed and validated in an experimental model and in clinical patients. In an in vitro circuit model, color jet width correlated well with actual orifice dimension from 12 to 24 mm (r = 0.99). In the clinical application, mitral valve area was calculated as a X b X pi/4 where a and b represent the width of the color flow stream in the mitral orifice just distal to the annulus in apical long-axis (short-diameter) and 4-chamber (90 degrees rotated, long-diameter) views, respectively. Cardiac output was then computed as the product of mitral valve area and time-velocity integral of transmitral flow from the same site. Cardiac output was also measured by thermodilution and conventional echocardiographic methods using diameters and time-velocity integrals from the left ventricular outflow tract. In 30 patients with nonvalvular heart disease, cardiac output measured by thermodilution ranged from 3.40 to 8.40 L/min. Cardiac output was determined in 28 of 30 patients (93%) by the Doppler color flow imaging technique; it ranged from 3.00 to 8.36 L/min and correlated well with thermodilution: y = 0.90x + 0.63, r = 0.91. Cardiac output was determined in 24 of 30 patients by the conventional left ventricular outflow method (80%). The cardiac output measured by the conventional method correlated less closely with thermodilution (r = 0.84), although there was no statistical difference in correlation coefficiencies between the 2 methods. These results indicate that the Doppler color flow imaging technique can be used to enhance the determination of cardiac output by echocardiography, particularly when the conventional method has resulted in technically inadequate recordings.

Adult↗