PubMed Health⌕ Search

Biomedical subjects

M Yasui

Publications and source records attributed to M Yasui.

At least 181 records · Page 10Linked to original sources
PubMed1985

Structure of ferricytochrome c' from Rhodospirillum rubrum at 6 A resolution.

The structure of a ferricytochrome c' extracted from Rhodospirillum rubrum has been determined at 6 A resolution by the X-ray crystallographic method. The crystals, obtained by dialyzing the protein solution against polyethylene glycol 4000, belong to the hexagonal space group P6(1). Two heavy atom derivatives were obtained by soaking the native crystals in K2PtCl6 and CH3HgCl solution. The phases calculated by the multiple isomorphous replacement method gave an overall figure of merit of 0.90 at 6 A resolution. The resulting electron density map showed the molecular boundary clearly, and gave molecular dimensions of 50 X 25 X 30 A for a monomer molecule. From visual examination of this map, the cytochrome c' from Rhodospirillum rubrum has a similar chain-folding pattern to the cytochrome c' from Rhodospirillum molischianum, the structure determination of which has already been carried out.

Crystallography↗
PubMed1984

A new crystal form and preliminary crystallographic data for ferricytochrome c' from Rhodospirillum rubrum.

A new crystal form of ferricytochrome c' from the photosynthetic bacteria, Rhodospirillum rubrum, has been obtained by dialysing protein solution against polyethylene glycol 4000. The crystals belong to the space group P61 (or its enantiomorph P65) with unit cell dimensions: a = b = 51.63 A and c = 155.39 A. The asymmetric unit contains one dimer molecule of 28,000 molecular weight and the solvent content of the unit cell is approximately 38%.

Crystallization↗
PubMed1984

Kinetic properties of binding of myosin subfragment-1 with F-actin in the absence of nucleotide.

The rate constant for the binding of myosin subfragment-1 (S-1) with F-actin in the absence of nucleotide, k1, and that for dissociation of the F-actin-myosin subfragment-1 complex (acto-S-1), k-1, were measured independently. The rate of S-1 binding with F-actin was measured from the time course of the change in the light scattering intensity after mixing S-1 with various concentrations of F-actin and k1 was found to be 2.55 X 10(6) M-1 X S-1 at 20 degrees C. The dissociation rate of acto-S-1 was determined using F-actin labeled with pyrenyl iodoacetamide (Pyr-FA). Pyr-FA, with its fluorescence decreased by binding with S-1, was mixed with acto-S-1 complex and the rate of displacement of F-actin by Pyr-FA was measured from the decrease in the Pyr-FA fluorescence intensity. The k-1 value was calculated to be 8.5 X 10(-3) S-1 (or 0.51 min-1). The value of the dissociation constant of S-1 from acto-S-1 complex, Kd, was calculated from Kd = k-1/k1 to be 3.3 X 10(-9) M at 20 degrees C. Kd was also measured at various temperatures (0-30 degrees C), and the thermodynamic parameters, delta G degree, delta H degree, and delta S degree, were estimated from the temperature dependence of Kd to be -11.3 kcal/mol, +2.5 kcal/mol, and +47 cal/deg . mol, respectively. Thus, the binding of the myosin head with F-actin was shown to be endothermic and entropy-driven.

Actins↗
PubMed1983

Heterogeneity of sugar composition of factor VIII/von Willebrand factor in von Willebrand's disease: analysis by crossed affinoimmunoelectrophoresis using lectin (ricinus communis agglutinin-120).

The nature of sugar chain of factor VIII/von Willebrand factor in plasma of normal subjects and patients with von Willebrand's disease (vWd) was examined by crossed affinoimmunoelectrophoresis using anti-human factor VIII rabbit serum, with inserted Ricinus communis agglutinin-120 (RCA-120) agarose layer (RCA - CIE). Molecular weights of factor VIII-related antigen (VIIIR:Ag) were estimated by SDS polyacrylamide gel electrophoresis - crossed affinoimmunoelectrophoresis (SDS PAGE - RCA - CIE). VIIIR:Ag, in normal plasma and in classical form of vWd, showed two precipitin peaks on RCA - CIE. The slower moving component of VIIIR:Ag with molecular weights over 3 x 10(6) daltons from normal subjects and patients with classical form of vWd showed a high affinity for RCA-120. The faster moving component of VIIIR:Ag below 3 x 10(6) daltons from the above-mentioned subjects and patients with a variant form (Type IIA) showed a very weak affinity for RCA-120. These results suggested that all of VIIIR:Ag in these variant cases may have a deficiency of galactose residues reactive with RCA, in addition to an incomplete polymerization of VIIIR:Ag, similar to that of the faster moving component of normal subjects.

Blood Coagulation Factors↗
PubMed1983

Comparison of analgesic potencies of mu, delta and kappa agonists locally applied to various CNS regions relevant to analgesia in rats.

Analgesic potencies of relatively selective agonists for mu, delta and kappa subtypes of opioid receptors, morphine, [D-Ala2,D-Leu5]-enkephalin (DADL) and ethylketocyclazocine (EKC), respectively, were examined with the tail-pinch test in the rat, when microinjected into the brain stem regions relevant to analgesia such as the nucleus reticularis paragigantocellularis (NRPG), nucleus raphe magnus (NRM) and periaqueductal gray matter (PAG), and into the lumbar subarachnoid space (LSS). Morphine, DADL and EKC produced dose-dependent analgesic effects at the NRPG, NRM, PAG and LSS. The ED50 values indicated that morphine was more potent than DADL at the NRPG and LSS but less at the NRM and PAG. EKC was the weakest at all the injection sites. Further, naloxone (0.1 mg/kg, s.c.) significantly antagonized the analgesic effect of morphine but not that of DADL or EKC at the NRPG. These findings suggest that mu, delta and kappa subtypes of opioid receptors mediate analgesia, and that the extent of contribution of each subtype to the production of analgesia differs among the CNS sites examined in this study.

Analgesics, Opioid↗
PubMed1982

Termination of retinal fibers in lateral preoptic and hypothalamic areas of the crab-eating monkey, Macaca irus.

After a monocular injection of tritiated proline into the vitreous chamber of the eye, the distribution of labeled retinal termination in the hypothalamus of the crab-eating monkey was investigated by autoradiography. The results indicated that a few retinofugal fibers might terminate bilaterally in the lateral hypothalamic areas through the level of the anterior commissure to the infundibulum as well as the suprachiasmatic nuclei. The labeled fibers to the lateral hypothalamic area seemed to leave the dorsocaudal border of the optic chiasma in a dorsolateral direction and then coursed both rostrally and caudally above the supraoptic nucleus: these fibers might progressively diminish in number at more rostral and caudal levels. Further, small clusters of developed silver grains were found bilaterally in the caudal part of the lateral preoptic nuclei.

Animals↗
PubMed1982

An autopsy case of primary hepatoma associated with an oral contraceptive.

Primary hepatoma was found in a 38-year-old female who had been using an oral contraceptive for 28 months. Histologically the hepatoma was a well-differentiated hepatocellular carcinoma. Alpha-fetoprotein was not increased and tests for HBS antigen was negative. Carcinoembryonic antigen was elevated remarkably before death. The findings of hepatic arteriography and peritoneoscopy suggested metastatic tumors of the liver rather than primary hepatoma. During the course of the disease, phlebothrombosis occurred and spread widely in the lower left limb. The observation of erythrocytosis indicated the presence of a tumor producing erythropoietin or an erythropoietin-like substance.

Adult↗
PubMed1980

Studies on amyotrophic lateral sclerosis by neutron activation analysis--2. Comparative study of analytical results on Guam PD, Japanese ALS and Alzheimer disease cases.

Metal analysis of calcium, manganese, aluminum and copper in CNS tissue samples of degenerative CNS disease cases (six Japanese ALS, three Japanese Alzheimer disease, four Guam PD, one Guam ALS) using neutron activation analysis, was conducted with following results: Five of six Japanese ALS cases, two of three Japanese Alzheimer disease cases and all of four Guam PD cases showed a high content of calcium and aluminum in CNS tissue with a significant positive correlation between calcium and aluminum and/or between calcium and manganese. These findings suggest a possible process of metal-induced soft tissue calcification with interaction of other di- and/or trivalent cations such as aluminum, manganese in CNS tissue of these degenerative CNS diseases.

Adult↗