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T Mitsui

Publications and source records attributed to T Mitsui.

At least 55 records · Page 3Linked to original sources
PubMed2000

Nuclear resonance scattering of synchrotron radiation by 40K

We have observed the excitation of the 29.83 keV nuclear level of the radioactive 40K nuclide, which level is not populated by any radioactive source, by synchrotron radiation for the first time. The absolute energy of the level of 29.834+/-0.011 keV and the half-life of 4.13+/-0.12 ns were obtained from our measurements. Our success in observing the nuclear excitation of radioactive 40K in a KCl powder sample shows the possibility for study of the local vibrational states and the electronic states of potassium in various areas of research.

Journal Article↗
PubMed2000

Functional association between nicotinic acetylcholine receptor and sarcomeric proteins via actin and desmin filaments.

By affinity chromatography utilizing alpha-cobrotoxin from digitonin-solubilized fractions of rabbit skeletal muscle, we found that many proteins are associated with the nicotinic acetylcholine receptor (AChR). In addition to the proteins we previously reported to bind to AChR (including dystrophin-dystrophin-associated protein (DAP) complex, utrophin, rapsyn, and actin; Mitsui et al. [1996] Biochem. Biophys. Res. Commun.224:802-807), alpha-actinin, desmin, myosin, tropomyosin, troponin T, and titin are also identified to be associated with AChR. Alkaline treatment or Triton X-100 solubilization released dystrophin-DAP complex, utrophin, and rapsyn from the AChR fraction, while actin and desmin remained associated. These findings demonstrate that AChR is supported primarily by a submembranous organization of actin and desmin filaments, and is linked to sarcomeric proteins via these filaments. To further investigate whether the association has any functional role, we studied the effect of acetylcoline on ATPase activity of the AChR fraction. Acetylcholine (0.5-4 microM) significantly activated Mg(2+)-ATPase activity of digitonin-solubilized AChR fraction (P < 0.05). Furthermore, we found that desmin as well as actin activated myosin Mg(2+)-ATPase activity. From these findings, it is suggested that desmin and actin form a submembranous organization in the postsynaptic region, and function as mediators of excitation of AChR to the sarcomeric contraction system.

Acetylcholine↗
PubMed2000

Angiotensin-converting enzyme inhibitor prevents plasminogen activator inhibitor-1 expression in a rat model with cardiovascular remodeling induced by chronic inhibition of nitric oxide synthesis.

Plasminogen activator inhibitor-1 (PAI-1) may participate in the development of cardiovascular remodeling by inhibiting extracellular matrix turnover and fibrinolysis. However, little is known about physiological regulators of PAI-1 in vivo. Angiotensin II has been shown to stimulate PAI-1 in vitro. We previously reported that long-term inhibition of nitric oxide (NO) synthesis with Nomega-nitro-L-arginine methyl ester (L-NAME) causes cardiovascular remodeling (vascular medial thickening and fibrosis) associated with increased tissue angiotensin-converting enzyme (ACE) activity. In the present study, we examined whether treatment with an ACE inhibitor modulates the cardiovascular PAI-1 expression in this model in vivo. Wistar-Kyoto rats were treated with either no drugs, L-NAME (100 mg/kg x day), or L-NAME plus the ACE inhibitor imidapril (20 mg/kg day). Marked increases in PAI-1 mRNA and protein levels in the aorta and left ventricle were observed after the first and fourth weeks of PAI-1 treatment. PAI-1 immunoreactivity was increased in the endothelium and the media of the aorta and coronary arteries after treatment of L-NAME. This increase in PAI-1 levels was associated with an increase in ACE activity of the aorta and left ventricle. ACE inhibition with imidapril significantly prevented both the increases in PAI-1 levels and the development of cardiovascular remodeling. These findings suggest that the local renin-angiotensin system regulates PAI-1 expression, and that the increased PAI-1 levels may contribute to the cardiovascular remodeling in this model.

Angiotensin-Converting Enzyme Inhibitors↗
PubMed2000

A new model of lung metastasis for intravital studies.

We created anexperimental model of pulmonary metastasis based on subcutaneously implanted Lewis lung cancer in mice and observed in vivo the microcirculation of spontaneously metastasized tumors in the lung. The mice lung was held by a small handmade suction ring to stop cardiac and respiratory movement. Using fluorescent microscopy, tumor microcirculation and normal lung microcirculation in the same lung lobe were compared by measuring microvessel diameter and blood flow velocity [red blood cell (rbc) velocity]. In normal microcirculation, the mean values of microvessel diameter and rbc velocity were 10.4 +/- 2.7 microm and 188 +/- 63 microm/s, respectively. In tumor microcirculation, the mean values of the same were 10.6 +/- 3.3 microm and 105 +/- 40 microm/s. The rbc velocity in normal microcirculation was significantly higher (P < 0.001) than that in tumor microcirculation. The calculated shear rates of normal microcirculation and tumor microcirculation were 73.4 +/- 23.4 (/s) and 41.2 +/- 16.1 (/s), respectively. The shear rate of the tumor microcirculation was significantly slower (P < 0.001) than that of the normal microcirculation. We demonstrated a feasibility of observation and measurement of tumor microcirculation in the lung and confirmed that the physiologic data were compatible to those in the brain or in the liver reported by others. This model might be useful for studying metastatic tumor pathophysiology in the lung microcirculation.

Animals↗
PubMed2000

Right ventricular volume unloading evaluated by tangential magnetocardiography.

OBJECTIVE: The evaluation of right ventricular volume overload in the presence of a right bundle branch block based solely on the results of an electrocardiogram is difficult. The purpose of this study was to purify acute right ventricular volume unloading from the tangential magnetocardiography. METHODS: We measured the tangential (x-y plane) magnetocardiogram and electrocardiogram simultaneously in nine patients with a secundum atrial septal defect. The magnetocardiograms were obtained before surgical closure and during the immediate postoperative period using the 32-channel superconducting quantum interference device system in a magnetically shielded room. RESULTS: The QRS duration on the surface electrocardiogram decreased significantly (p < 0.05) in the immediate postoperative period. The right ventricular depolarization time as measured by the magnetocardiogram was shortened from 40.3 +/- 6.1 to 25.3 +/- 7.4 milliseconds (p < 0.0005). The maximum peak amplitude during right ventricular depolarization decreased from 17.9 +/- 4.8 to 11.1 +/- 4.9 pT (p < 0.01). CONCLUSIONS: We conclude that acute volume unloading of the right ventricle was indicated quantitatively by shortening of the right ventricular depolarization time and a reduction in the amplitude of current vectors originating from the right ventricular depolarization on the tangential magnetocardiography.

Adolescent↗
PubMed2000

Acute heart failure due to local dehiscence of aortic wall at aortic valvular commissure.

Spontaneous dehiscence of the aortic wall at the aortic commissure is not recognized as one of the usual pathological causes of aortic regurgitation. We describe the case of a 56-year-old man with hypertension, who experienced acutely progressive congestive heart failure due to massive aortic regurgitation. Local layer dehiscence around the commissure was noted with partial detachment of the commissure resulting in the loss of commissural support with secondary rupture of a non-coronary cusp, which led to massive aortic regurgitation.

Acute Disease↗
PubMed2000

Acute aortic thrombosis after intra-aortic balloon pumping.

Acute aortic occlusion is a rare but devastating complication of intra-aortic balloon pumping. Prompt diagnosis of aortic occlusion and immediate therapeutic decision making are keys for saving patients in such cases. We describe a 72-year-old man who underwent emergency surgical removal of a thrombus and aortoiliac bifurcated grafting for acute aortic occlusion after withdrawal of the intra-aortic balloon pumping catheter. The presence of a small unrecognized abdominal aortic aneurysm was considered to be the cause of thrombosis in this patient. Ultrasonographic screening for an abdominal aortic aneurysm is recommended for patients who require intra-aortic balloon pumping support.

Acute Disease↗
PubMed2000

Minimally invasive direct coronary artery bypass grafting in a patient with brainstem infarction.

Brainstem infarction associated with the primitive trigeminal artery is rare. We describe the case of a 61-year-old man with an acute myocardial infarction as well as a brainstem infarction. The patient was referred for coronary artery bypass grafting. Minimally invasive direct coronary artery bypass grafting (left internal thoracic artery to the second diagonal branch anastomosis) could be safely performed 10 weeks after an episode of brainstem infarction.

Brain Stem↗
PubMed2000

Extended septoplasty for subaortic stenosis developed 19 years after double-outlet right ventricle repair.

A 27-year-old woman developed subaortic stenosis 19 years after double-outlet right ventricle repair. Subaortic stenosis was caused by a narrow ring of fibromuscular ridge associated with a bulge of the underlying septal muscle. The aortic valve was bicuspid and stenotic. We conducted extended septoplasty, replacing the aortic valve. Postoperative cineangiogram showed an adequate left ventricular outflow pathway. Double-outlet right ventricle repair may thus be followed by subaortic stenosis as long as 19 years after initial surgery. This lesion was assumed due to acquired disease secondary to flow disturbances in the left ventricular outflow, so reconstructing an adequate outflow pathway is effective and appears to help avoid recurring stenosis.

Adult↗
PubMed2000

Is endogenous isoprene the only coeluting compound in the measurement of breath pentane?

Pentane is a widely used index of lipid peroxidation. Although isopentane, an isomer of pentane, is a major component of ambient air in urban areas, many studies have disregarded the possibility that this compound is coeluted in the measurement of breath pentane. In the present study, a gas chromatograph equipped with a cold trap apparatus and a large-bore glass capillary column was used for determination of pentane, isopentane and isoprene in breath and ambient air. Isoprene was detected in all subjects at a concentration higher than that in the ambient air. However, the concentrations of breath pentane and isopentane were similar to, or less than, those of the ambient air. We suggest that great care is required in the measurement of breath pentane so that endogenous isoprene and ambient isopentane are not coeluted.

Adult↗
PubMed2000

Influences of catecholamines on the sudden death induced in dogs by an antifungal agent, D0870.

We previously reported the occurrence of QT prolongation and sudden death owing to torsades de pointes (TdP) in dogs treated with D0870, an antifungal agent. In the present study, we evaluated the influences of epinephrine and isoproterenol on the onset of TdP each time D0870 was given to 6 anesthetized open-chest dogs at a dosage of 20 mg/kg, 5 times every 40 minutes, by the simultaneous measurements of surface electrocardiogram and epicardial monophasic action potential (MAP). D0870 alone induced noticeable prolongation of the QT interval and action potential duration (APD), but neither ventricular premature contraction (VPC) nor sudden death. In contrast, the additional administration of the catecholamines induced a greater shortening of APD during the later phase of repolarization than during its earlier one and VPCs in all dogs tested, and sudden deaths owing to TdPs in 4 of the 6 dogs treated with D0870. These results suggest that D0870 alone does not induce TdP but that catecholamines play an important part in the development of sudden death induced by D0870 in dogs.

Action Potentials↗
PubMed2000

Estimation of nitrate metabolism in intestinal tract by measuring breath nitrous oxide concentration in Chinese and Japanese.

We have previously reported that ingestion of vegetables containing high nitrate (NO3-) increases breath nitrous oxide (N2O) concentration, probably due to denitrification. In the present study, we estimated NO3- metabolism in the intestine by determining exhaled breath N2O concentration after the ingestion of vegetables by 16 healthy Chinese and Japanese. Breath samples were collected at 15-min intervals for 4 hr after subjects ingested 180 g of vegetable juice or 50 g of lettuce. Breath N2O concentration was measured by an IR-PAS analyzer. Lettuce but not vegetable juice increased N2O concentrations similarly in Japanese and Chinese. In control subjects who ingested nothing, there were significant differences between Chinese and Japanese in peak N2O concentrations (334 +/- 91 vs 140 +/- 24 ppb, P = 0.027) and total excretions (535 +/- 143 vs 214 +/- 36 microg, P = 0.036). Although the reason for this difference is unclear, Chinese subjects could produce breath N2O from other metabolic pathways than denitrification of dietary NO3.

Adult↗
PubMed2000

Association of fasting breath nitrous oxide concentration with gastric juice nitrate and nitrite concentrations and Helicobacter pylori infection.

Fasting breath nitrous oxide (N2O) concentration was determined in relation to pH, nitrate (NO3-) and nitrite (NO2-) concentrations in gastric juice, and Helicobacter pylori infection in 86 successive patients. N2O was measured with an infrared-photoacoustic analyzer. NO3- and NO2- were measured using the Griess reaction. Fasting breath N2O concentration in controls (87 +/- 21 ppb) was not significantly different from that in patients with gastric ulcer or other gastric lesions. Breath N2O was significantly correlated with gastric NO3- (P < 0.01) and was higher in patients with elevated gastric NO2- (246 +/- 87 ppb) than in patients without NO2- (75 +/- 13 ppb). Breath N2O did not differ significantly between subjects who were positive or negative for H. pylori. In conclusion, fasting breath N2O concentration is in some manner related to intragastric NO3- and NO2- concentrations. The possible use of measuring breath N2O as predictors of cancer needs further research.

Adult↗
PubMed2000

An iso-integral mapping technique using magnetocardiogram, and its possible use for diagnosis of ischemic heart disease.

We have developed an iso-integral mapping technique that uses magneto-cardiogram (MCG) data to obtain a map as projected total current image on the torso from the heart. We have also investigated the applicability of iso-integral mapping to the diagnosis of ischemic heart disease. We simulated and measured the characteristics of two types of iso-integral maps: one using tangential (Bxy) components, and one using the normal component (Bz). Each vector component was measured by two types of superconducting quantum interference device (SQUID) system to determine the tangential and normal components. The tangential component of the magnetic field appeared to be equivalent to the current image in the myocardium projected on the observing plane, and we were able to obtain a projected total current image by integration of the tangential components during the depolarization and repolarization processes. And we found that the iso-integral maps of normal hearts showed similar pattern in both processes; however, those of ischemic hearts showed different patterns.

Action Potentials↗
PubMed2000

Improvement in bronchiolitis obliterans organizing pneumonia in a child after allogeneic bone marrow transplantation by a combination of oral prednisolone and low dose erythromycin.

We report a 13-year-old boy who developed dyspnea at rest 1 year after the occurrence of cGVHD following an allogeneic bone marrow transplant (BMT). Pulmonary function data, imaging studies, lung biopsy, and bronchoalveolar lavage were consistent with the diagnosis of bronchiolitis obliterans organizing pneumonia (BOOP). Although reports suggest that oral methylprednisolone or methylprednisolone pulse therapies improve BOOP after BMT, we treated our patient with a combination of oral prednisolone (1 mg/kg) and low dose erythromycin (10 mg/kg) to avoid the side-effects of high-dose steroids. With this therapy, our patient showed clinical and radiological improvements within 1 week. The steroids were tapered off 12 months later and erythromycin was given for 14 months. We conclude that therapy consisting of a combination of oral prednisolone and low-dose erythromycin for BOOP after BMT may minimize the dose and duration of steroid use.

Administration, Oral↗
PubMed2000

Unnatural base pairs between 2-amino-6-(2-thienyl)purine and the complementary bases.

The unnatural base, 2-amino-6-(2-thienyl)purine (designated as s), instead of 2-amino-6-(N,N-dimethylamino)purine (designated as x), was designed in order to improve the specificity and efficiency of the base pairing with pyridin-2-one (designated as y). DNA fragments containing s were chemically synthesized, and the thermal stability and the enzymatic reactions involving the s-y pairing were examined. Thermal denaturation experiments showed that the DNA duplex (12-mer) containing the s-y pair was more stable than that containing the x-y pair. The incorporation of dyTP was also more advantageous to the s-y pairing than the x-y pairing in single-nucleotide insertion experiments using the Klenow fragment of Escherichia coli DNA polymerase I.

Base Pairing↗
PubMed2000

Application of SEM-modified X-ray microscope to entomology and histology, and effects of X-ray coherence in imaging.

A projection X-ray microscope has been constructed by modifying a scanning electron microscope (HITACHI S-2500CX). Characteristic internal structures and their changes in an aphid, a fly, an ant, a water bear and a beetle are observed first, non-destructively, by X-ray microscope. Stereo-pair X-ray micrographs of Golgi-stained sections of porcine liver show a network of bile canaliculi and stellate cells. The very clear micrographs presented indicate the usefulness of the microscope in studies of entomology and histology. In some micrographs, very thin whiskers or hairs are visible, which suggests that a phase-contrast effect is present in the imaging. X-ray micrographs of an ant hair taken at various distances between the X-ray source and the specimen, D(s), indicate that the image enhancement due to the phase contrast increases with increasing D(s). Degree of the lateral coherence of X-rays of wave length 0.1 nm is theoretically estimated near the hair, with the result that the coherence increases from about zero (almost complete incoherence) at D(s) = 0.1 mm to about unity (almost complete coherence) at D(s) = 6 mm, in agreement with the observation.

Animals↗