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Biomedical subjects

M Sugihara

Publications and source records attributed to M Sugihara.

At least 73 records · Page 4Linked to original sources
PubMed1989

Calmodulin and free oxygen radicals interaction with steady-state calcium accumulation and passive calcium permeability of cardiac sarcoplasmic reticulum.

The generation of free oxygen radicals from the xanthine-xanthine oxidase system produced a decrease in the steady-state calcium load of canine cardiac sarcoplasmic reticulum (SR) vesicles and an increase in the SR passive calcium permeability. This effect of free oxygen radicals was completely inhibited by superoxide dismutase, a scavenger of superoxide anion radical (.O2-). Treatment of intact SR with a specific calmodulin antagonist, compound 48/80 or W-7, lead to the enhancement of the free oxygen radical-mediated reduction of steady-state calcium accumulation with little effect on passive calcium permeability and Ca,Mg-adenosine triphosphatase activity. The effects of free oxygen radicals and the calmodulin antagonists on steady-state calcium accumulation, but not on passive calcium permeability, were only observed in the presence of the endogenous calmodulin of SR vesicles. These results indicate that stimulation by .O2- and/or a closely related species of free oxygen radical of the passive calcium leak pathway is not calmodulin-dependent and is not a potent way of changing the steady-state calcium accumulation. Hence, we propose that calmodulin-dependent component of calcium fluxes in cardiac SR vesicles is modified directly by free oxygen radicals, and that free oxygen radicals can reduce steady-state calcium accumulation due to increased calcium release through a calcium efflux pathway which is inhibited by calmodulin, but not due to reduced catalytic activity of the pump.

Animals↗
PubMed1989

[Angiotensin II-induced hypertension chemotherapy of bone and soft-tissue sarcomas].

We treated 14 patients with high grade sarcomas by angiotensin II-induced hypertension chemotherapy. The chemotherapy protocol described by Rosen was selected according to histological classification of sarcomas (small cell sarcoma, spindle cell sarcoma, pleomorphic sarcoma). The level of angiotensin-induced hypertension was one and half times as high as blood pressure at rest. Induced hypertension was maintained for 30-60 minutes. In three cases of 5 primary osteosarcomas, induced hypertension resulted in the increase of tumor stain and/or vascularity angiographically, and chemotherapeutic effects were CR or PR. The six cases with soft-tissue sarcomas were 2 cases each of CR, PR, and NC. The decrease of relative tumor blood flow under the condition of angiotensin II-induced hypertension was detected in 5 cases of 6 soft-tissue sarcomas by 133Xe clearance method. In the case of rhabdomyosarcoma, the decrease of tumor stain and vascularity by induced hypertension was observed on angiogram. As the side effects accompanying induced hypertension, nausea and chest oppression were noted in 2 cases, respectively. In this study it was suggested that angiotensin II-induced hypertension chemotherapy was effective for osteosarcoma, but that it might be ineffective for soft-tissue sarcomas.

Adolescent↗
PubMed1989

[Combined effect of cisplatin and caffeine on murine B16-BL6 melanoma cells].

Combined effect of cisplatin and caffeine on murine B16-BL6 melanoma cells was studied. Synergistic inhibition of the cell growth was observed when caffeine (2 mM) was added continuously after one hour exposure of cisplatin. On the other hand, when caffeine was added before one hour exposure of cisplatin or one hour simultaneous exposure with cisplatin, synergistic effect was not shown. In the analysis of DNA histogram obtained from flow cytometry, S and G2/M accumulation was observed by the treatment of cisplatin and that accumulation was reduced by the combination of cisplatin and caffeine. From this findings, it was suggested that caffeine would inhibit DNA repair process. Furthermore, according to morphological studies with hematoxylin-eosin stain and Fontana-Masson stain, the addition of caffeine alone resulted in mild swelling of melanoma cells and the decrease of nuclear-cytoplasmic ratio. The combination of cisplatin and caffeine caused marked swelling of melanoma cells and remarkable increase of dendrite-like processes. Melanogenesis was also enhanced by the addition of these two drugs. Many matured melanosomes, increases of mitochondria, Golgi's apparatus and endoplasmic reticula were observed by the use of electron microscope. These findings implied that the combination of cisplatin and caffeine induced a differentiation of murine melanoma cells.

Animals↗
PubMed1989

[Clinical usefulness of three-dimensional brain imaging with N-isopropyl-p-[123I]iodoamphetamine (IMP)].

Three-dimensional reconstruction from N-isopropyl-p-[123I]iodoamphetamine (IMP) tomography has been applied clinically to the detection of perfusion defects in 22 cases (15 cerebrovascular diseases and 7 normal controls confirmed by CT and MRI), with data being analyzed in terms of receiver operating characteristic curves (ROC). The results showed that three-dimensional (3-D) image could make better diagnostic capability especially in inexperienced examiner and that it was useful decreasing of difference of diagnostic capability. 3-D image could be taken within 1 minute and 15 seconds. We concluded that the three-dimensional brain imaging with IMP using this system was clinically useful because examiner could easily diagnose perfusion defects.

Aged↗
PubMed1988

Microcomputer-assisted filing system of cardiac catheterization records using a relational database management system.

To efficiently store and retrieve cardiac catheterization records, we have developed a computer-assisted database, which comprises a 16-bit microcomputer with dual floppy disk drives, a 20 MB random-access memory, hard disk drive, and a line printer. All programmings were accomplished using a relational database management system (R:base 5000, Microrim, Inc.). Data inquiry procedures could be performed with direct operational commands of the system as well as with preprogrammed command files, and final results of searches were printed out with a line printer. The major advantages of the present system described in this report include: (1) the relatively easy and rapid creation of the database, (2) ease of modification of the database structures even after the system design is finished, (3) operational commands in combination with conditional operator(s) are flexible and powerful enough to allow the end user to retrieve data based on various kinds of criteria, (4) a high-level programming language provided by the R:base automates a series of database procedures with relative ease, (5) relational capabilities of the database management system can enhance the possibility of reconstruction of a new data file from a single or several preexisting data files, and (6) the system can be realized at reasonable cost.

Cardiac Catheterization↗
PubMed1987

Long-term prognosis of vasospastic angina without significant atherosclerotic coronary artery disease.

Long-term prognosis of 90 patients with vasospastic angina without significant coronary artery disease (less than 50% reduction in luminal diameter) was examined for a mean follow-up period of 4 years. All patients had episodes of angina at rest and were treated with calcium antagonists. One patient developed myocardial infarction and 2 died suddenly during the follow-up period. In the patient with myocardial infarction, there was an abrupt worsening of angina prior to the infarction despite therapy with a calcium antagonist. One of the sudden death patients discontinued his calcium antagonist before his death. Of the sudden death patients, one had ventricular tachycardia and the other had a complete atrioventricular block during an anginal attack. The incidence of such serious arrhythmias was higher (p less than 0.01) in sudden death patients (2/2) than that in survivors (6/88). The treatment with calcium antagonists reduced the severity and frequency of angina in all patients. These results suggest that long-term prognosis of vasospastic angina without significant coronary artery disease is good as characterized by the low incidence of myocardial infarction and death and the favorable response to treatment with calcium antagonists.

Adult↗
PubMed1985

Cyclic loading on the red cell membrane in a shear flow: a possible cause of hemolysis.

The fluid force acting on single human red cells in a high shear flow was analyzed. A two-dimensional elliptical microcapsule as a model of the deformed red cells was adopted to numerically calculate the distributions of the shear forces on both sides of the cell membrane. It is theoretically shown that the cell membrane undergoes an unsteady cyclic loading under the rotational motion around the interior. The mechanism leading to blood cell trauma is examined by repeatedly loading the continuously moving cell membrane.

Biomechanical Phenomena↗
PubMed1985

Motion and deformation of a red blood cell in a shear flow: a two-dimensional simulation of the wall effect.

The motion and deformation of a single red blood cell in a simple shear flow between two parallel walls is studied theoretically. A two-dimensional deformable microcapsule is adopted as a model for the cell, which has a thin moving membrane, like a tank-tread, around the interior and is deformed into an elliptical shape with a constant area. Applying the finite element method to the Stokes equations, the tank-tread motion and deformation is determined in a stationary motion, under fluid dynamic interaction between the cell and the walls. It is shown that the motion and deformation of the microcapsule crucially depends on the channel width between the two walls. As the width decreases, the microcapsule is more elongated and the frequency of tank-tread motion decreases at a constant shear rate. In addition, the angle of inclination decreases at the low range of the viscosity ratio of internal to external fluids and increases at the high range. The results obtained are compared with experimental observations and applied to the behavior of cells under mutual interaction.

Erythrocyte Deformability↗