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Biomedical subjects

I Ito

Publications and source records attributed to I Ito.

At least 181 records · Page 10Linked to original sources
PubMed1986

Digital subtraction angiography: image-sequence analysis for regional myocardial perfusion dynamics.

Digital subtraction angiography with selective coronary injections of contrast media has enabled us to obtain clear images, not only of the artery, but of the capillary and venous phases of the myocardial perfusion. In the present study, densitometry was used to estimate regional myocardial perfusion dynamics in 10 control cases and 11 anterior myocardial infarction cases. The time density curve showed that contrast material increased rapidly in the arterial phase and appeared to be washed out monoexponentially in the venous phase. The time from the onset of contrast medium injection to the maximal density of the contrast medium (Tp), and the time constant obtained from the washout curve (Tc) were analyzed. In the control group, Tp in the apical region was slightly prolonged as compared with Tp in the anterobasal region, but the difference was not significant (5.2 +/- 0.5 vs 4.2 +/- 0.4 sec: mean +/- SEM). Tc did not definitely change in any portion of the myocardium (anterobasal 5.1 +/- 0.5, anterior 4.8 +/- 0.5, apex 4.6 +/- 0.5 sec, respectively). In anterior myocardial infarction, Tp in the marginal region was significantly prolonged compared to Tp in the control region (6.0 +/- 0.3 vs 4.7 +/- 0.3 sec, p less than 0.01). Tp was prolonged for more than 10 sec in the infarcted region. Tc in the marginal region was markedly prolonged compared to Tc in the control region (7.4 +/- 0.9 vs 4.4 +/- 0.5 sec, p less than 0.025). Tc could not be determined in the infarcted regions because data acquisition time of our apparatus was inadequate.(ABSTRACT TRUNCATED AT 250 WORDS)

Coronary Angiography↗
PubMed1986

[Sigmoid septum causing left ventricular outflow tract obstruction: a case report].

A 67-year-old man with a sigmoid septum causing the left ventricular outflow obstruction by inotropic stimulation was reported. This patient was admitted to the Hospital of the University of Tsukuba because of chest pain. Phonocardiography revealed a systolic ejection murmur which was intensified by amyl nitrite inhalation. A carotid pulse tracing showed a mid-systolic dip and a secondary slow wave during amyl nitrite inhalation. M-mode echocardiography demonstrated neither systolic anterior motion of the mitral valve (SAM) nor mid-systolic closure of the aortic valve at rest. Two-dimensional echocardiography revealed a basal interventricular septum markedly protruding into the left ventricle (sigmoid septum). The remainder of the septum and the left ventricular free wall were not hypertrophied, and no enlargement of the left ventricular cavity was observed. During exercise tests, blood pressure dropped significantly. Cardiac catheterization showed a pressure gradient within the left ventricle with isoproterenol infusion and post-extrasystolic potentiation. These findings suggest that left ventricular outflow tract obstruction could occur in a patient with sigmoid septum by inotropic stimulation, producing a fall of blood pressure during exercise.

Aged↗
PubMed1985

Mitral valve prolapse syndrome with coronary artery spasm: a possible cause of recurrent ventricular tachyarrhythmia.

A 54-year-old man with mitral valve prolapse syndrome diagnosed by echocardiography complained of anginal pain associated with ventricular tachyarrhythmia. One day he suddenly lost consciousness, and ECG at that time revealed ventricular fibrillation. Thereafter, he developed ST elevation, sporadic premature ventricular contractions, and R on T phenomenon leading to ventricular fibrillation during the attack of anginal pain. His coronary arteriogram was normal. This case implies that coronary artery spasm may be one of the causes of chest pain and ventricular tachyarrhythmias in patients with mitral valve prolapse syndrome.

Coronary Vasospasm↗
PubMed1985

Significance of ST-segment and T wave changes in the resting electrocardiograms of patients with exertional angina, studied by exercise radionuclide angiocardiograms.

In order to investigate the clinical significance of ST-T changes in resting ECG in angina pectoris, symptom-limited ergometer exercise radionuclide angiocardiography with ECG was performed in 60 patients with exertional angina. In those with normal ECG at rest (Group N), left ventricular ejection fraction (EF) did not change during exercise (71 +/- 5% to 71 +/- 6%). In those with only ST change at rest (Group ST) and those with only T change at rest (Group T), EF decreased significantly during exercise (68 +/- 5% to 63 +/- 7%, p less than 0.01; 68 +/- 6% to 61 +/- 7%, p less than 0.001). In those with ST and T changes at rest (Group ST + T), EF was low at rest (58 +/- 11%) and decreased further at exercise (52 +/- 8%, p less than 0.001). In those whose negative or flat T wave became more negative during exercise, EF was low both at rest and at exercise. In conclusion, ST and T changes at rest in patients with exertional angina might suggest a depressed reserve of myocardial function for exercise.

Adult↗
PubMed1985

Significant role of alpha 2-adrenoceptors in coronary artery spasm.

Ergonovine, methoxamine and clonidine were administered intravenously in order to clarify the mechanism of coronary artery spasm in canine experiments. After these administrations, 27.5% of the dogs treated with ergonovine, 59.5% of the dogs treated with methoxamine and 72.7% of the dogs treated with clonidine showed ST segment elevation. The combined application of propranolol with ergonovine or methoxamine could more easily induce ST segment elevation than a single application of ergonovine or methoxamine. Most cases of elevated ST segment returned to the normal after the administration of nitroglycerin and phentolamine. Yohimbine was completely effective for the restoration of normal ST segment. Plasma norepinephrine decreased to 20 +/- 8.0% of the control when ST segment elevation was induced. This is a significantly greater decrease than that seen without ST segment elevation (p less than 0.001). Concomitant with the restoration of normal ST segment, plasma norepinephrine increased after the administration of yohimbine. Methoxamine and clonidine increased (p less than 0.01) and yohimbine decreased (p less than 0.01) coronary vascular resistance. Coronary spasm was visualized on coronary arteriogram after the application of clonidine; also coronary vasodilation was visualized after the administration of yohimbine. These results confirm the hypothesis that coronary artery spasm is mediated by pre- and postsynaptic alpha 2-adrenoceptors.

Animals↗
PubMed1985

[Quantitative analysis of myocardial perfusion by digital subtraction angiography].

Digital subtraction angiography (DSA) has been adopted to detect ischemic myocardial areas and to quantitatively evaluate the degrees of myocardial perfusion abnormalities. Subtraction for selective coronary arteriography was performed sequentially between mask and enhanced images in the same cardiac phases by means of ECG signals. We obtained three distinct perfusion phases which we termed the arterial, capillary, and venous phases. Densitometry of the circumferential cardiac wall was performed on these sequential images. The results were compared with 201Tl myocardial scintigrams and cine angiograms. In the arterial phase, the abnormalities of the coronary artery, such as stenosis, obstruction and collaterals were represented. In the capillary phase, contrast materials served as markers of myocardial perfusion and delineated infarctions as areas of low contrast enhancement compared to the normally perfused myocardium. In the venous phase, the infarcted areas were represented as areas with greater relative contrast enhancement than that of the normal myocardium. Circumferential analysis of perfusion could provide more detailed information about myocardial ischemic areas and the degrees of ischemia. Although we used invasive selective coronary arteriography, DSA techniques have numerous merits such as excellent temporal resolution, spatial resolution, and good contrast resolution, over conventional methods. Quantitative DSA methodology which we developed provided not only anatomical information about the main coronary arteries but new information about abnormalities of peripheral myocardial perfusion.

Angiography↗
PubMed1985

[Regional myocardial perfusion abnormality detected by digital subtraction angiography in a case of patent ductus arteriosus with coronary arterial fistulae].

A 19-year-old woman with patent ductus arteriosus and increasingly severe chest pain received various examinations including exercise stress radionuclide test, which revealed hypokinesis and decreased myocardial perfusion in the apex and left ventricular dilatation. Conventional selective coronary arteriography and newly-developed ECG synchronized digital subtraction angiography (DSA) were performed to identify the genesis of her myocardial ischemia. Selective coronary arteriography revealed congenital coronary arterial fistulae in the right and left coronary arteries. The largest fistula was observed around the obtuse marginal artery terminating in the left ventricle. Although stenosis of the left circumflex and left anterior descending arteries (LAD) were not observed, the LAD appeared to be hypoplastic. Hypoplasia of the LAD and the steal phenomenon by arterial fistula could have been responsible for the myocardial ischemia in the apex, but this method did not clearly reveal the area and the degree of myocardial ischemia in the apex. Sequentially subtracted images during the arterial and capillary phases were obtained by utilizing ECG-synchronized DSA for selective coronary arteriography. For these images, densitometric analysis was adapted to the myocardial region, i.e. circumferential densitometry using 21 segments around the left ventricular wall. Decreased myocardial perfusion was clearly demonstrated in the apex in capillary phase images. Moreover, circumferential analysis provided detailed information about the area and the degree of impaired peripheral circulation in the myocardium. This analysis by DSA may prove useful for evaluating myocardial perfusion abnormalities.

Adult↗
PubMed1985

[Apical hypertrophy and catecholamine].

Catecholamine is suspected to be related to the pathogenesis of hypertrophic cardiomyopathy (HCM). To investigate the contribution of catecholamine to apical hypertrophy (APH) which is a special type of HCM, 16 normal controls, 49 +/- 4 years old; 14 patients with APH, 55 +/- 6 years old; 18 patients with other types of HCM, 53 +/- 8 years old; and 12 patients with left ventricular hypertrophy due to valvular heart diseases (VHD), 49 +/- 10 years old, were studied during treadmill exercise tests, supine ergometer tests and intravenous infusions of isoproterenol (ISP) (0.02 micrograms/kg/min for 5 min). Echocardiograms and/or electrocardiograms were obtained during the procedures. During ergometer exercise, there was no significant difference in increase of heart rates among all groups. Ergometer exercise increased the level of plasma catecholamine in the group VHD, and there was a similar but less marked tendency in the APH. During the ISP infusion, "mechanical" reaction was relatively low in the APH compared to those in the other groups. The giant negative T waves in the HCM, mostly in the APH, lessened during exercise and during the ISP infusion. Among those in whom negative T wave changes of more than 0.5 mV occurred during exercise, the wall motion of the left ventricle was more active during exercise. Giant negative T waves changed diurnally and were less deeper during daytime than at night.(ABSTRACT TRUNCATED AT 250 WORDS)

Cardiomyopathy, Hypertrophic↗
PubMed1984

Ionic mechanism of a hyperpolarizing glutamate effect on two identified neurons in the buccal ganglion of Aplysia.

The ionic mechanism of a membrane effect of L-glutamate on two identified neurons in the buccal ganglion of Aplysia kurodai was investigated with conventional microelectrode techniques and glutamate iontophoresis. Bath-applied and iontophoresed glutamate hyperpolarized the membrane and increased the membrane conductance. The hyperpolarizing glutamate response decreased in amplitude and finally reversed its polarity by conditioning hyperpolarization. The reversal potential of the hyperpolarizing glutamate response was close to the ECl (-60 mV). The reversal potential changed by 22.4 mV when the external chloride concentration was altered by a factor of 5. The relationship between the iontophoretically applied current and the membrane conductance changes was suggestive of two glutamate molecules reacting with a single receptor site. The hyperpolarizing glutamate response was essentially unaffected by 2-amino-4-phosphonobutyric acid (2-APB), L-proline, and quinuclidinyl benzilate (QNB). It was concluded that the hyperpolarizing glutamate response was generated by an activation of Cl- conductance.

Animals↗
PubMed1984

Levamisole in postoperative adjuvant immunochemotherapy for gastric cancer. A randomized controlled study of the MMC + Tegafur regimen with or without levamisole. Report I.

The usefulness of LMS in postoperative immunochemotherapy of gastric cancer was investigated. In compliance with the protocol, MMC was given at a dose of 20 mg on the day of gastrectomy, and an additional 10 mg on the next day IV. The patients receiving 600 mg Tegafur daily were then divided into two groups according to whether LMS was also given or not. LMS was administered for 3 days before the operation in a daily dose of 150 mg and for 1 year or more after operation according to a schedule of 3 days' administration followed by an 11-day interval. The 2-year follow-up demonstrated that in stage III patients, the LMS (+) regimen was superior to the LMS (-) regimen, since the former prolonged the relapse-free interval significantly. The survival rate for stage III disease was also significantly higher in the LMS (+) than in the LMS (-) group. There was no significant difference in the incidence of subjective or objective side-effects between two groups. The incidence of agranulocytosis was comparable in the two groups.

Adult↗
PubMed1984

Effects of 5-hydroxytryptamine on membrane potential, contractility, accumulation of cyclic AMP, and Ca2+ movements in anterior aorta and ventricle of Aplysia.

Effects of 5-hydroxytryptamine (serotonin; 5-HT) on the anterior aorta and ventricle muscle of the marine gastropod Aplysia are characterized. Bath-applied 5-HT depolarizes muscle fibers and causes tension increases in both the anterior aorta and ventricle above ca. 10(-9) M. Iontophoretically applied 5-HT caused localized depolarizations of anterior aorta muscle fibers. 5-HT increases the levels of adenosine-3',5'-cyclic monophosphate (cAMP) markedly in the anterior aorta of A. kurodai and A. californica and in the ventricle of A. kurodai. Effects of 5-HT on the contractility of and cAMP synthesis in the anterior aorta and ventricle are both blocked by methysergide. 5-HT and cAMP analogs stimulate 45Ca2+ efflux from the ventricle, implying that the effects of cAMP on contractility involve intracellular Ca2+ movements.

Animals↗