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Biomedical subjects

D Saito

Publications and source records attributed to D Saito.

At least 19 recordsLinked to original sources
PubMed1992

Papillary fibroelastoma in the left ventricular outflow tract.

We report a case of a papillary fibroelastoma originating from the left ventricular endocardium in the outflow tract which was discovered by echocardiography in an asymptomatic patient. Two echocardiographic features were observed: (1) the tumor surface was smooth, and characteristic papillary formation was not detected; and (2) the outline of the mass was clearly defined as a dense echo, with the central, radiolucent, portion surrounded by a highly refractive linear echo at the level of the maximum diameter of the mass. The excised tumor was covered with a gelatinous substance that masked multiple papillae on the surface, but its echolucent center could not be explained by the pathology of the tumor which was solid centrally. Our case indicates that a papillary fibroelastoma may sometimes show echocardiographic findings similar to those of a myxoma, although other investigators have not noted the smooth surface and the echolucent center makes it indistinguishable from a myxoma. Thus, in some cases, it is difficult to distinguish papillary fibroelastoma from myxoma by echocardiography.

Connective Tissue↗
PubMed1991

Oxygen metabolism of the hypertrophic right ventricle in open chest dogs.

STUDY OBJECTIVE: The aim was to investigate oxygen metabolism of the hypertrophic right ventricle in anaesthetised open chest dogs. DESIGN: Right ventricular hypertrophy was induced by right ventricular pressure overload with banding the pulmonary artery for six months. Coronary blood flow and myocardial oxygen metabolism of the hypertrophic right ventricle were determined during control and after increasing right ventricular oxygen consumption, and compared with those of the normal right and left ventricles. SUBJECTS: Seven mongrel dogs with right ventricular hypertrophy and 21 normal dogs were used. All were anaesthetised with pentobarbitone sodium. MEASUREMENTS AND MAIN RESULTS: Oxygen extraction [(A-V)O2] of the hypertrophic right ventricular myocardium was greater than that of normal right ventricle in controls and almost identical to the (A-V)O2 of the normal left ventricle. It showed no increase when coronary blood flow and right ventricular oxygen consumption were raised in response to a further elevation of the right ventricular pressure and isoprenaline infusion. However, the right ventricular interventions which increased right ventricular oxygen consumption produced an elevation of (A-V)O2 of the right ventricle with an increase in right coronary blood flow. CONCLUSIONS: Higher oxygen extraction during control and no response of oxygen extraction of the hypertrophied right ventricle in response to stimuli which increase right ventricular oxygen consumption indicate that oxygen supply to the hypertrophic right ventricle is different from that of the normal right ventricle, and is more like that of the left ventricle.

Animals↗
PubMed1991

An early phase II study of 5-fluorouracil combined with cisplatinum as a second line chemotherapy against metastatic gastric cancer.

Twenty-two patients with measurable metastatic gastric cancer, refractory to prior chemotherapy, were treated with a combination chemotherapy of 5-fluorouracil (5FU) and cisdiamminedichroloplatinum (II) (CDDP). 5FU was continuously infused for five consecutive days at a dose of 800 mg/m2/day, and CDDP was given intravenously for five days at a dose of 20 mg/m2/day over 30 min every four weeks. All patients had received only one regimen of prior chemotherapy, and 10 of the 22 had been pretreated with combination of etoposide, doxorubicin and CDDP (EAP). It was possible to evaluate 20 of the 22 patients treated for response and toxicity. Nine of the 20 patients achieved a partial response, the response rate being 45% (23-67% with 95% confidence limits). The nine patients who responded included three who had been pretreated with EAP, indicating that 5FU + CDDP can be used as a second line chemotherapy against gastric cancer, even when the initial intensive chemotherapy, such as EAP, has failed to obtain or maintain a response. High grade toxicities (WHO grade 3 or 4) of leukocytopenia, thrombocytopenia and stomatitis were seen in 20, 25 and 40%, respectively. No treatment-related death was, however, observed. The above results suggest that 5FU + CDDP could be promising in a phase II trial with a large number of cases.

Adenocarcinoma↗
PubMed1991

Inhibitory effect of 8-chloro-cyclic adenosine 3',5'-monophosphate on cell growth of gastric carcinoma cell lines.

A cAMP analogue, 8-chloro-cAMP (8-Cl-cAMP), selectively binds to site 1 receptor of type II regulatory subunit (RII) of cAMP-dependent protein kinase. The effects of 8-Cl-cAMP on human gastric carcinoma cell lines were studied. Twenty microM 8-Cl-cAMP clearly inhibited cell growth in six cell lines (TMK-1, KATO-III, MKN-7, -28, -45, and -74) but not in MKN-1. Cell population in the G1 phase was increased in KATO III cells, which were more responsive to 8-Cl-cAMP, while cell cycle progression in TMK-1 and MKN-1 cells was apparently not influenced by 8-Cl-cAMP. The various changes induced by 8-Cl-cAMP were further analyzed in TMK-1 cells. Decrease of type I regulatory subunit (RI) of cAMP-dependent protein kinase and translocation of RII from cytosol to nucleus were induced by 8-Cl-cAMP treatment. 8-Cl-cAMP increased the level of cAMP-response element (CRE) binding protein in addition to inducing FOS mRNA, whose promoter contains CRE. 8-Cl-cAMP decreased the expression of mRNA for transforming growth factor-alpha (TGF-alpha), while the expression of epidermal growth factor receptor was not changed. Expression of HRAS and MYC mRNAs was slightly increased, whereas the amounts of HRAS and MYC proteins remained unchanged. Our results overall suggest that 8-Cl-cAMP might be a useful tool for antitumor therapy of gastric cancers and that cell growth inhibition by 8-Cl-cAMP might account for the decrease of TGF-alpha expression by tumor cells.

8-Bromo Cyclic Adenosine Monophosphate↗
PubMed1991

Reproducibility of diurnal variation of heart rate.

Heart rate variation has been utilized as a parameter for validating autonomic nerve and sinus node function. However, few reports are available on the reproducibility of such data. In the present study, we studied the reproducibility of the diurnal variation of heart rate in 15 patients, and the effect of age differences on the variation in 30 normal men using a Holter ECG monitoring method. For investigating reproducibility, Holter ECG monitoring was performed twice, the two measurements being separated by a short interval. A moving average method applied on heart rate of every 3h exhibited essentially the same diurnal pattern of heart rate between two records in each patient. Excellent reproducibility of the pattern was also demonstrated by a lag correlation analysis. Variability of heart rate in normal men was independent of age. These results suggest that heart rate variation was essentially constant in each subject, at least within a short period.

Adult↗
PubMed1991

Interaction between adenosine and beta-adrenoceptors.

Interaction between adenosine and isoproterenol (ISP) on myocardial inotropic action was studied in open-chest dog hearts. The local myocardial force and the left ventricular (LV) dP/dt were measured as indices of myocardial contractility. Isoproterenol [ISP, 9.47 microM (2 micrograms/ml)] was infused into the left circumflex coronary artery at rates of 0.05 ml/min (low dose ISP) or 0.2 ml/min (high dose ISP). Two mM adenosine or 0.5 mM N6-phenylisopropyl-adenosine (PIA) were infused into the coronary artery at rates of 0.2 (4 x 10(-7) mol/min), 0.5 (1 x 10(-6) mol/min) and 10 ml/min (2 x 10(-5) mol/min) in the presence of either a low or a high dose of ISP. Adenosine infusion at a rate of 0.2 ml/min did not modify myocardial contractility in the presence of the both doses of ISP. The larger doses of adenosine, 0.5 ml/min and 10 ml/min, decreased myocardial-developed tension and LVmax dP/dt dose-dependently. However, the dose of adenosine which affected myocardial contractility was inphysiologically high in comparison with the concentration in the ischemic myocardium. PIA, a potent agonist of adenosine A1-receptor, attenuated an increase in myocardial contractility in a dose-dependent manner which was caused by intracoronary ISP infusion. This indicates that A1-adenosine receptors exist, but a functional adenosine-catecholamine antagonism does not play a significant role in the canine left ventricle.

Adenosine↗
PubMed1991

[Relationship between QRS transition zone and the interventricular septum: using CT scan].

The relationship between the QRS transition zone of the standard 12-lead ECG and interventricular septum was studied. The position and the angle to the horizontal line of the interventricular septum were evaluated with computed tomography (CT) and compared to the QRS transition zone. The subjects were 36 patients with no cardiovascular diseases. The patients were divided into 3 groups according to the position of QRS transition zone: V1-V2 (8 cases), V3-V4 (21 cases), and V5-V6 (7 cases). The interventricular septum on CT was directed to the anterior chest wall between V3 and V4 in all 3 groups. The mean value of the interventricular septal angle did not differ from group to group, 52.1 degrees for V1-V2 group, 49.8 degrees for V3-V4 group, 48.2 degrees for V5-V6. It was concluded that the direction of the interventricular septum was not one of the major determinants of the QRS transition zone in the standard 12-lead ECG.

Aged↗
PubMed1991

[Acute hemodynamic effect of cigarette smoking and its relationship with nicotine content].

We studied the acute effects of cigarette smoking on the cardiovascular system, especially regarding nicotine-related hemodynamic effects using cigarettes with low and high nicotine contents. 40 healthy men who were habitual smokers were divided into two groups: 20 subjects smoked cigarettes of low nicotine content [0.4 mg/cigarette; group 1 (G1)] and another 20 tested cigarettes containing high nicotine [2 mg/cigarette; group 2 (G2)]. All of the subjects were requested to abstain from cigarette smoking for at least 12 hours prior to study, and to rest in the supine position for 30 minutes just prior to the test. They smoked two consecutive cigarettes for 10 minutes, inhaling every 30 seconds by drawing on the cigarette for two seconds, and holding the smoke for three seconds before exhaling. Blood pressure (BP), heart rate (HR) and cardiac output (CO) were measured and blood samples were taken before, and 5, 10 and 30 minutes after the start of smoking. Smoking with a high nicotine content (G2) produced a significant increase in both systolic and diastolic BP (124 +/- 14/78 +/- 8----138 +/- 21/90 +/- 10 mm Hg), but no significant changes in BP were observed in the low nicotine group. HR and CO increased predominantly in both groups (HR: G1; 62 +/- 7----66 +/- 7, G2; 64 +/- 7----76 +/- 9/min, CO: G1; 4.85 +/- 1.36----5.31 +/- 1.37, G2; 4.95 +/- 1.58----5.63 +/- 2.01 l/min), but the present increases were significantly less in G1 than in G2.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1991

[Modification of the smoking-induced hemodynamic effect by nifedipine].

Effects of nifedipine, a Ca(++)-channel blocker, on smoking-induced hemodynamic changes were studied in 35 habitual male smokers. They were divided into three groups: 20 healthy persons (G1), 11 patients with essential hypertension (G2) who were under nifedipine treatment, and 4 patients (G3) with essential hypertension but who were receiving no medication. After abstaining from smoking for more than 12 hours, they smoked, within 10 minutes, two filtered cigarettes each containing 2 mg of nicotine. Hemodynamic parameters were measured and blood samples were taken before and 5, 10, and 30 minutes after beginning to smoke. In each group, smoking produced significant increases in blood pressure, heart rate and cardiac output. Plasma adrenaline increased significantly in 3 groups, and tended to be highest in G2. Plasma noradrenaline was the highest in G2 predominantly, but did not change after smoking. These results indicate that a smoking-induced hyperdynamic state including vasoconstriction due to catecholamine release might not depend on the calcium channel which is blocked by nifedipine, and the reflex activation of the sympathetic nerve system would develop in the presence of nifedipine.

Calcium Channel Blockers↗
PubMed1990

Reactive hyperaemic flow characteristics of the right coronary artery compared to the left anterior descending coronary artery in the open-chest dog.

Reactive hyperaemia, the cardiovascular response to transient occlusion of a vessel, was examined and compared in the right coronary artery (RCA) and the left anterior descending coronary artery (LAD) in the same heart of an open-chest dog. First, to study the relationship between reactive hyperaemia and occlusion time in the RCA and LAD, respective flows were measured and reactive hyperaemia was induced with different occlusion times. Occlusion time required for half the maximum peak percentage reactive hyperaemic flow (%PRH), t 1/2, for the RCA was approximately twice that of the LAD: 11.4 +/- 2.3 s versus 5.9 +/- 1.4 s. Maximum %PRH of the RCA was significantly greater than that of the LAD while the percentage repayment of the RCA was lower than that of the LAD. Augmentation of right ventricular oxygen consumption shortened t 1/2 and increased percentage repayment significantly. Second, to determine "critical pressure", which was defined as the perfusion pressure below which reactive hyperaemia was abolished completely, the RCA and LAD were perfused through a shunt from the carotid artery, perfusion pressure was varied in the range of 100 to 20 mmHg and reactive hyperaemia was induced. Critical pressure in the RCA was significantly lower than in the LAD: 32.2 +/- 5.7 mmHg versus 41.5 +/- 5.0 mmHg. These results suggest that the RCA has a greater flow reserve than the LAD. These results were consistent with the difference of oxygen metabolism between the right and left ventricles. The difference of oxygen metabolism between the two ventricles would, at least partly, account for these results.

Animals↗
PubMed1990

Autoregulation by the right coronary artery in dogs with open chests; comparison with the left coronary artery.

Experiments were conducted to study autoregulatory responses of the right and left coronary arteries in dogs with open chests. The right and left circumflex coronary artery were cannulated and perfused with blood from the femoral artery via a pressurized reservoir. The perfusion pressure was varied in steps over a wide range and coronary blood flow rates were measured. Both the right and left coronary arteries exhibited autoregulation but the pressure at the end of the autoregulatory range was lower in the right (39.8 +/- 9.1 mm Hg) than in the left circumflex coronary artery (57.6 +/- 14.5 mm Hg). The slope of the pressure-flow relationship in the autoregulatory range was less steep in the right than the left circumflex coronary artery. The closed-loop gain when the perfusion pressure was less than 100 mm Hg was greater in the right than in the left circumflex coronary artery. Increases in the right ventricular afterload produced by pulmonary artery constriction decreased the closed-loop gain, shifted the auto-regulatory range upward and to the right, and made the slope steeper. These results indicate that more effective autoregulation is carried out by the right than the left circumflex coronary artery.

Animals↗
PubMed1990

Clinical significance of monitoring serum levels of 5-fluorouracil by continuous infusion in patients with advanced colonic cancer.

Serum concentrations of 5-fluorouracil (5-FU) given by continuous infusion to 19 patients with advanced colonic cancer were measured by an HPLC method, and steady-state concentration (SSc), area under the curve (AUC72) and total body clearance (Cl) were calculated as pharmacokinetic parameters. The serum level of 5-FU rapidly increased, reaching a plateau within 2 h after the start of administration. There were positive correlations between the dose and both SSc (r = 0.578, P less than 0.01) and AUC72 (r = 0.558, P less than 0.05). When the patients were divided into toxic and non-toxic groups according to the degree of toxicity, the values for SSc and AUC72 in the toxic group were significantly higher than those in non-toxic patients. The Cl value in the toxic group was also significantly different from that in the non-toxic group when data were calculated on a log scale. Furthermore, no differences in these parameters between effective and non-effective in these parameters between effective and non-effective groups were detected when the patients were divided into two groups according to anti-neoplastic responses. These results indicate that increased serum concentration does not always provide therapeutic benefits to patients receiving continuous infusions of 5-FU.

Adult↗
PubMed1990

Pilot phase II study of cis-diamminedichloroplatinum (II) against metastatic gastric cancers.

Fifty patients with metastatic gastric cancer were entered for a phase II study of Cis-diamminedichloroplatinum (II) (CDDP), 45 of whom were able to have their responses evaluated. CDDP was given intravenously at a dose of 80 mg/m2 over two hours every three weeks. There were four partial responses (25%) among the 16 patients who had had no prior chemotherapy, and three partial responses (10%) among the 29 patients who had had prior chemotherapy. The total response rate was 16%. The chief manifestations of toxicity were gastrointestinal symptoms, such as nausea and/or vomiting. Severe nephrotoxicity was not observed. From these data, the administration of CDDP at a dose of 80 mg/m2 every three weeks was considered tolerable, and CDDP as a single agent was considered effective against metastatic gastric cancers. In addition, three of the 29 pretreated patients who responded suggested that CDDP could be given as a second-line chemotherapy when initial treatment with other active agents, i.e. fluorinated pyrimidine or mitomycin C, fails to obtain a response.

Adult↗
PubMed1990

[The clinical application and limitation of electrocardiography].

Electrocardiography (EGG) is one of the most useful methods for diagnosis of the heart diseases, including ischemic heart disease, cardiomegaly and arrhythmias. However, image methods such as echocardiography, CT-scan and MRI for diagnosis of heart diseases developed in the recent several years gave rise to some conflictions between the findings obtained by ECG and the imaging methods. Therefore, the diagnostic criteria of ECG had to be re-examined. The body Surface Map (MAP) with 87 leads on the body surface revealed more circumstantial electric phenomena of the heart than the standard 12-lead ECG and vectorcardiography. However, the MAP needs a lot of time for recording and diagnosis because of its many electrodes. Computer diagnosis adequately developed, and simplification and abbreviation of recording are required. Morphologic disorders of the heart can be diagnosed more adequately by imaging methods such as echocardiography and CT-scan than ECGs. However for the study of arrhythmias, ECGs including standard 12-lead, vector and Holter electrocardiographies, and MAP are almost the only methods now available. Each method of ECG has different characteristics and is widely accepted not only for clinical diagnosis but also research of arrhythmias. In the near future, noninvasive examination from the body surface to reveal a minute electric change of the heart will be expected instead of invasive examinations as His-bundle ECGs.

Arrhythmias, Cardiac↗
PubMed1990

[Studies on faint attack due to arrhythmias with Holter electrocardiogram].

Out of 1,400 Holter ECGs, 15 records revealed arrhythmias which would be responsible for faint attack, including 8 sick sinus syndrome with cardiac arrest, 4 non-sustained ventricular tachycardia (VT), 2 paroxysmal atrial fibrillation and 1 paroxysmal supraventricular tachycardia. All of cardiac arrest corresponding to faint attack lasted for longer than 4 sec, and an averaged duration of the arrest was 5.8 +/- 2.3 sec. This was significantly longer than that with no subjective symptoms, 3.4 +/- 0.7 sec. Duration and rate of VT did not show any significant relationship with faint attack. The result suggests that cardiac arrest is mostly responsible for arrhythmia-induced involvement of cerebral circulation and faint attack. It is also suggested that cardiac arrest longer than 4 sec should be extensively treated including pacemaker implantation.

Arrhythmias, Cardiac↗
PubMed1989

Reperfusion through balloon catheter to minimize myocardial infarction during the interval between failed percutaneous transluminal coronary angioplasty and emergency coronary artery bypass grafting.

A 65-year-old man was admitted with chest pain. A diagnosis of spastic angina was made because of symptoms of recurrent anginal attacks associated with ST-segment elevations in the electrocardiogram. A selective coronary arteriogram revealed a 90% diameter narrowing of the proximal left anterior descending coronary artery (LAD). No angiographically visible collaterals from the right coronary artery to the LAD were observed. The ventriculogram showed normal contraction of the left ventricle with an ejection fraction of 65%. Percutaneous transluminal coronary angioplasty (PTCA) failed resulting in total occlusion of the stenosis. Repeat PTCA at a higher pressure and of longer duration failed to redilate the artery. Reperfusion with the blood from the femoral artery through the balloon catheter, which was used for the PTCA, was carried out until coronary artery bypass grafting (CABG). Blood flow rate of perfusion was approximately 25 ml/min. Reperfusion through the balloon catheter reduced chest pain and ST-segment elevations in the electrocardiogram. The patient tolerated the operative procedure well and his post-operative course was uncomplicated. The interval between the acute occlusion and revascularization by CABG was approximately 4 1/4 h. The ventriculogram taken 56 days after the CABG demonstrated normal contraction of the anterior wall of the left ventricle with an ejection fraction of 63%. Abnormal Q waves did not appear in precordial leads of the electrocardiogram after the surgery. The thallium scintigram showed no perfusion defects. In conclusion, this case suggested that autologous blood reperfusion through balloon catheter would be worth attempting in some cases for minimization of myocardial infarction during the interval between failed PTCA and emergency CABG.

Angioplasty, Balloon, Coronary↗