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Biomedical subjects

I Sakuma

Publications and source records attributed to I Sakuma.

At least 145 records · Page 8Linked to original sources
PubMed1987

Behavioral and biochemical changes following acute administration of MPTP and MPP+.

The acute effects of 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP) and 1-methyl-4-phenylpyridinium ion (MPP+) on mouse locomotor activity and striatal dopamine (DA) and 5-hydroxytryptamine (5-HT) levels were investigated. A single dose of either MPTP (10-30 mg/kg, i.p.) or MPP+ (5-20 ug/mouse, i.c.v.) decreased locomotor activity 10-40 min after injection: this locomotor effect was significantly suppressed by either pretreatment with nomifensine or 1-deprenyl alone, or by the combination of desmethylimipramine and 6-hydroxydopamine. Pretreatment with clorgyline did not suppress this behavior and a single dose of haloperidol enhanced the effect. The striatal levels of DA, 3-methoxytyramine and 5-HT increased in parallel with the decrease in locomotor activity caused by MPTP or MPP+. In contrast, levels of 3,4-dihydroxyphenylacetic acid, homovanillic acid and 5-hydroxyindoleacetic acid were decreased by injection of either MPTP or MPP+. Possible mechanism(s) of the behavioral and biochemical changes caused by the acute actions of MPTP and MPP+ with respect to their neurotoxic effects on the nigrostriatal DA system are discussed.

1-Methyl-4-phenyl-1,2,3,6-tetrahydropyridine↗
PubMed1987

Peptidoleukotrienes induce an endothelium-dependent relaxation of guinea pig main pulmonary artery and thoracic aorta.

The purpose of our investigation was to assess the role of the endothelium in the vasomotor effects of leukotrienes. Norepinephrine-preconstricted rings isolated from guinea pig main pulmonary artery and thoracic aorta responded to LTC4 and LTD4 with a concentration-dependent relaxation. In endothelium-denuded rings, both LTC4 and LTD4 caused a concentration-dependent contraction. The LTD4 receptor antagonist ICI 198,615 inhibited both LTC4- and LTD4-induced relaxation and contraction. Inhibition of gamma-glutamyl transpeptidase with AT-125 prevented the effects of LTC4, but not those of LTD4. The relaxant effect of LTD4 was not modified by indomethacin, but was abolished by methylene blue. We conclude that: 1) LTD4 induces a receptor-mediated endothelium-dependent relaxation of cavian pulmonary artery and aorta; 2) the vasorelaxant effect of LTC4 requires its conversion to LTD4; 3) the vasorelaxant effect of LTD4 is unrelated to PGI2 release, and is probably due to the release of an "EDRF"; 4) the removal of the endothelium reveals a direct receptor-mediated vasoconstricting effect of leukotrienes.

Animals↗
PubMed1987

Pharmacological analysis of the cardiac actions of xamoterol, a beta adrenoceptor antagonist with partial agonistic activity, in guinea pig heart: evidence for involvement of adenylate cyclase system in its cardiac stimulant actions.

The pharmacological effects of xamoterol, a beta adrenoceptor antagonist with partial agonistic activity, were examined in guinea pig cardiac preparations and compared with those of isoproterenol to assess possible mechanisms of its cardiac stimulant actions. Xamoterol produced a positive inotropic effect in the papillary muscles and a positive chronotropic effect in the spontaneously beating right atria in a concentration-dependent manner. The maximum inotropic and chronotropic effects of xamoterol were about 33 and 35% of those of isoproterenol, respectively. Although xamoterol failed to produce a consistent increase in contractile force in the left atria, the positive inotropic effect of the agent was observed clearly in preparations obtained from reserpine-pretreated animals. The positive inotropic and chronotropic effects of xamoterol were antagonized by atenolol, but not by ICI 118,551. On the other hand, xamoterol antagonized competitively the positive inotropic and chronotropic responses to isoproterenol. In papillary muscles the increases in contractile force induced by xamoterol and isoproterenol were depressed markedly in the presence of carbachol or adenosine. In all of left atria, right atria and papillary muscles obtained from reserpine-pretreated animals, xamoterol caused a significant elevation in cyclic AMP levels, while inhibiting the isoproterenol-induced increase in cyclic AMP levels. Computer-assisted analysis of concentration-response curves for the inhibition by xamoterol of the binding of [125I]iodocyanopindolol in the membranes from guinea pig ventricles showed the existence of the 5'-guanylylimidodiphosphate sensitive, highly affinity site of beta adrenoceptors for xamoterol, suggesting that xamoterol may induce the formation of a ternary complex with the beta adrenoceptor and a stimulatory guanine nucleotide regulatory protein.(ABSTRACT TRUNCATED AT 250 WORDS)

Adenosine↗
PubMed1987

[A comparative study of apical hypertrophy with giant negative T waves and non-obstructive hypertrophic cardiomyopathy: evaluation by computed tomography, echocardiography and left ventriculography].

To assess the relationships between patterns of left ventricular hypertrophy and giant negative T waves (greater than 15 mm, GNT), 24 patients with GNT were categorized in two groups: Group A consisted of 12 patients with GNP but without left ventricular hypertrophy (greater than 13 mm at the chorda level of the interventricular septum and/or left ventricular posterior wall by UCG, LVH); and group-B consisted of 12 patients with GNT and LVH. Twelve patients with LVH but no GNT compromised as group-C. Left ventriculography (LVG) was performed, and left ventricular mass (LVM) and apical hypertrophy were assessed by CT. The configurations of the end-diastolic left ventricle by LVG (RAO 30 degrees) were as follows, by group: A: spade in eight patients and papillary muscle hypertrophy (PMH) shape in four. B: spade in five, PMH in four, banana in one and oval in two. C: banana in nine and oval in three. The LVM (g/BSAm2) were as follows; A: 121.5 +/- 14.9, B: 130.5 +/- 14.8, C: 190.6 +/- 42.1 (C greater than A, B, p less than 0.001). The apex/base ratios calculated by CT were as follows; A: 1.43 +/- 0.31, B: 1.21 +/- 0.19, C: 1.09 +/- 0.20 (C greater than A, p less than 0.05). The left ventricular mass in patients with GNT was less than that of those without GNT. Giant negative T waves were most often associated with apical hypertrophy.

Adult↗
PubMed1986

[Effects of the intravenous injection of an ionic contrast medium on the circulating plasma volume: an assessment with plasma colloid oncotic pressure].

UNLABELLED: We investigated effects of intravenous injection of ionic contrast medium (ICM) on circulating plasma volume (CPV) by measurements of changes in plasma colloid oncotic pressure (COP). METHOD: ICM (60% meglumine iothalamate 30 ml) was injected intravenously as a bolus into 7 healthy male volunteers. The venous blood samples were drawn before, and 1, 2, 3, 5 and 10 minutes after the injection. Relatively massive doses of the ICM (150-180 ml) were infused intravenously into 6 male cardiac patients with normal cardiac and renal function during ECG gated cardiac X-ray computed tomography. The blood samples were drawn before, soon after and an hour after the infusion. The plasma COP values of the blood samples were measured with a needle-type osmometer and the sequences of CPV were estimated from the changes of COP values. RESULTS: The bolus injection of the ICM increased the CPV by 10%, 8-9 ml of the CPV per 1 ml of the ICM, and the increase continued during the study (at least for 10 minutes). The massive infusion of the ICM resulted in about 20% increase of the CVP soon after the infusion, and then induced a diuletic effect. The CVP returned to the basal level in one hour, but some patients became rather dehydrated. CONCLUSION: These findings suggested that an intravenous injection of ICM produced considerable expansion of CPV and subsequent dehydration. Careful considerations would be necessary when patients with impaired cardiac or renal function are treated with intravenous ICM during X-ray computed tomography or digital subtraction angiography.

Adult↗
PubMed1986

[Right ventricular function assessed by scintigraphy using continuous infusion of krypton-81 m].

Scintigraphy using continuous infusion of krypton-81m, (81mKr) is a reproducible, noninvasive method for determining right ventricular ejection fraction (RVEF). Radionuclide determinations of RVEF by 81mKr scintigraphy were compared with those by the technetium-99m (99mTc) first-pass technique in 25 patients; the results obtained by both methods correlated well (r = 0.86, p less than 0.005). In 20 additional patients, the RVEF determined by 81mKr was compared with the RVEF as measured by multislice ECG-gated cardiac X-ray computed tomography, and there was good correlation between RVEFs obtained by the two methods (r = 0.76, p less than 0.005). Furthermore, the RVEF by the 81mKr technique and the LVEF by the 99mTc gated blood pool technique were compared with hemodynamic measurements. There was a significant inverse correlation between RVEF and pulmonary artery pressure or total pulmonary resistance. Other determinants of right ventricular systolic function were the presence of proximal right coronary artery disease, reduced left ventricular function and associated tricuspid regurgitation.

Heart↗
PubMed1986

[Analysis of ventricular wall motion using multislice ECG-gated cardiac X-ray CT: application of the three-dimensional reconstruction technique].

A new computer system was proposed to evaluate abnormal motion of the ventricular wall in patients with myocardial infarction. Multi-slice ECG-gated cardiac X-ray CT (MSECT), a new technique developed in our laboratory, was the source of the original image. Using this system, we reconstructed three-dimensional images, calculated % shortening values of the entire heart, and visualized abnormal wall motion on the ventricular surface, displaying three-dimensionally. Our initial study of five patients with myocardial infarction showed good correlation between the findings using this system and conventional echocardiography and cine-ventriculography. Since the development of the ECG-gated method, the application of CT to the study of heart diseases has progressed rapidly. In patients with myocardial infarction, ECG-gated cardiac CT is used to visualize infarcted myocardium and to evaluate impaired cardiac function. However, such analyses were limited to single slices, because a large dose of contrast medium was required to distinguish the ventricular chamber from the myocardium. By adopting multi-slice ECG-gated cardiac X-ray CT images as the data source and using three-dimensional reconstruction technique, this system is useful for evaluating abnormal wall motion.

Adult↗
PubMed1985

Changes in DOPAC and 5-HIAA after acute cerebral hemorrhage induced by hypertonic glucose solution (i.p.)--in vivo voltammetry study.

Intraperitoneal injection of hypertonic glucose solution induced intracranial hemorrhage in rats. Simultaneously determined plasma norepinephrine exponentially increased followed by death. Using in vivo voltammetry, the present study was undertaken to estimate the relationship between neurochemical parameters and intracranial bleedings induced by hypertonic glucose injection. When placed in a solution of dihydroxyphenylacetic acid (DOPAC) and 5-hydroxyindole acetic acid (5-HIAA), electrically pretreated carbon fiber electrodes produced a 3 distinct peaks. Peak 1 and 2 refer to the extracellular fraction of ascorbic acid and DOPAC. Peak 3 refers to that of 5-HIAA. The peaks of the voltammograms obtained in vivo from different areas of the brain are similar to those observed in vitro using DOPAC and 5-HIAA solutions. Electrodes implanted in the ventricular CSF showed that DOPAC increased immediately after glucose injection, while 5-HIAA did not change significantly. When the electrode was inserted into the putamen, 5-HIAA exponentially increased followed by death, whereas DOPAC showed only a small change. It was presumed that the stroke-induced major oxidizable compounds are different in the lateral ventricle and the putamen. These results suggest that during cerebral bleeding, plasma norepinephrine increases accompanied with a potentiation of the central DOPAC and 5-HIAA system in rats.

3,4-Dihydroxyphenylacetic Acid↗
PubMed1985

[Giant aneurysm of the right coronary artery with complete proximal obstruction: a case report].

A 46-year-old woman was admitted to our hospital for evaluation of oppressive chest pain and ECG abnormalities. Her ECG on admission showed old inferior myocardial infarction. Chest radiography on admission indicated cardiomegaly (cardiothoracic ratio was 60%). The echocardiogram showed compression of the right atrium, right ventricle, and tricuspid annulus by a tumor which was located between the liver and the heart. The tumor's echo density was heterogenous. Cardiac computed tomography showed compression of the tricuspid annulus by the tumor which was located anterior to the right atrium and the right ventricle. The tumor registered 65.1 HU and was not enhanced by contrast medium. These findings strongly suggested a giant right coronary aneurysm filled with thrombus, and this diagnosis was confirmed at surgery and pathologically. Coronary aneurysms are rarely diagnosed during life, and usually are incidental findings during coronary arteriography performed to evaluate myocardial infarction or angina pectoris. The coronary aneurysm of the present case was clearly and easily recognized using computed tomography and appeared as a pericardial tumor. Computed tomography may be helpful for observing the growth of tumor and thrombus formation within it.

Aneurysm↗
PubMed1983

[An application of X-ray computed tomography for complex cardiac anomalies].

X-ray computed tomography (CT) was performed in two patients with complex congenital heart disease in order to assess the clinical utility in the systemic morphological diagnosis. A Somotom 2 whole body CT scanner (Siemens Co) was used, and contrast enhanced CT scanning and a dynamic CT scanning were performed in one case (Case 2).; Case 1: A 20-year-old female with double outlet right ventricle (S, D, L), pulmonary stenosis and aortic insufficiency. The CT revealed a viscero-atrial situs, ventriculoarterial relation, spatial interrelationship between the great arteries and a run of the stenotic pulmonary artery. The CT clarified spatial relationship among four cardiac chambers, ventricular septal defect and great arteries, contributing to the understanding of the complex cardiac structure. Case 2: A 26-year-old female with single ventricle (III-C solitus), pulmonary stenosis, dextroversion, left superior vena cava and WPW syndrome. The CT documented precisely a viscero-atrial situs, dextroversion, ventriculoarterial relation, spatial interrelationship between the great arteries, stenotic main and left pulmonary arteries and a dilated right pulmonary artery due to the right Blalock-Taussig operation performed 15 years before. A diagnosis of left superior vena cava could be made by CT, and its flow into coronary sinus was visualized by dynamic CT. The dynamic CT also clarified a mixing of venous and arterial blood in the common ventricle, and revealed a rudimentary ventricular septum. Thus, the CT serves useful purposes especially as examination of viscero-atrial situs, ventriculoarterial relation and spatial interrelationship between great arteries, and anomalies of the mediastinal vessels. Furthermore the relationship among four cardiac chambers, ventricular septal defect, and the pattern of blood flow were also clarified. However, the CT failed to define the state of a ventricular loop, because it could not identify ventricular muscular structures and atrioventricular valves as these move rather vigorously. The CT could not locate pulmonary stenosis, valvular or somewhere else. The CT seemed to be a promising noninvasive method in the systemic morphological diagnosis of congenital heart disease as subsidiary to echocardiographic investigation. However, in pediatric patients, it seemed considerably hard to obtain clear cardiac CT images because of the difficulty in halting respiration during procedure.

Adult↗
PubMedDate not supplied

Simultaneous determination of catecholamines, their basic metabolites and serotonin in urine by high-performance liquid chromatography using a mixed-mode column and an eight-channel electrochemical detector.

A high-performance liquid chromatographic method for simultaneous determination of free catecholamines, their basic metabolites and serotonin in human urine was developed. The compounds were separated on a precolumn of cation-exchange resin and a mixed-mode (C18/cation-exchange) column and determined by an eight-channel electrochemical detector. By this method, free norepinephrine (NE), epinephrine (E), dopamine (DA), normetanephrine (NMN), metanephrine (MN), 3-methoxy-tyramine (3-MT) and serotonin (5-HT) were determined in 40 min with inter-assay precision of 1.9, 3.2, 1.2, 1.6, 1.6, 5.5 and 3.2%, respectively. Detection limits were between 0.05 (E) and 0.3 (3-MT) pmol. The mean values of analytical recovery for NE, E, DA, NMN, MN, 3-MT, 5-HT were 99, 104, 104, 99, 102, 109 and 99%, respectively.

Buffers↗
PubMedDate not supplied

Three-dimensional medical imaging display with computer-generated integral photography.

A 3-D display system for medical imaging by computer-generated integral photography (IP) has been developed. Real 3-D images are generated from 3-D medical images and displayed by simple structure. Each point in 3-D space is reconstructed by the convergence of rays from many pixels on the computer display through the lens array. Only the coordinate of the best point is computed for each pixel on the display. The locations of images projected within 40mm from the display were found to be less than 2.0mm in error. Projected images could be observed with motion parallax within 10 degrees from the front of the display.

Algorithms↗