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Biomedical subjects

Y Maeda

Publications and source records attributed to Y Maeda.

At least 1,063 records · Page 59Linked to original sources
PubMed1978

Mössbauer effect: studies of the electronic structures of the heme.

On the basis of experimental Mössbauer evidence, the electronic structures of heme iron are discussed for Mb and Hb. In the deoxygenated state, it is concluded from the electric field gradient tensor and the temperature dependence of the quadrupole splitting that the ferrous iron is not in the tetragonal ligand field with the symmetry axis perpendicular to the heme. The experimental results are well explained solely by rhombic perturbation. The electronic ground state is a component of the 5E term, and the principal axis of the anisotrophy is parallel to the heme plane. In the oxygenated state, there is no decisive conclusion on the bonding structure of the O2 molecule to the heme. Still, the two models of Pauling and Griffith are consistent with experimental results. Considering a relaxation between two possible conformational states, the peculiar temperature dependence of the quadrupole splitting is resolved in Fe-O2 model compounds.

Chemical Phenomena↗
PubMed1977

Membrane structures of human oligodendroglioma.

Plasma membrane particles of four human oligodendrogliomas were distributed at random, and their average number per micronm2 plasma membrane was 1090+/-233 on face A and 230+/-46 on face B. Gap junction was occasionally visible, usually small in size and composed of a polygonal aggregate of several subunits: isodiametric particles, about 70-80 A in diameter, on face A and pits, about 30-40 A in diameter, on face B. Tight junction in two oligodendrogliomas was characterized by a meshwork of circular or ramifying crests on face A and complementary furrows on face B. It was often continuous in distribution, consisting of 5 or more strands. In addition, many particulate structures, occasionally fibrillar ones, of ridge materials were often visible in the bottoms of furrows, and a few particles were scatteredly found on the tops of crests. The ridge materials, if added together on crests and furrows, were linearly continuous in some case and discontinuous in other.

Brain Neoplasms↗
PubMed1977

HLA-BW35 and B5 in Japanese patients with Graves' disease.

Thirty-three Japanese patients with Graves' disease and 106 healthy controls living in the Kagoshima area, the southernmost part of the Japanese mainland, were HLA typed by the NIH method. None of them were related to each other. The only antigen showing an increased frequency in Japanese patients with Graves' disease was HLA-BW35 (corrected P less than 0.02). A decreased frequency of B5 in the patients was also statistically significant (corrected p less than 0.02).

Asian People↗
PubMed1977

[Histological changes of various organs in aged SD-JCL rats (author's transl)].

Age-related histological changes were studied in various organs from SD-JCL rats reared throughout their lifespan. In aged-male rats examined at 5 to 36 months of age were frequently observed nephropathy, periarteritis, skeletal muscle degeneration, pigmentation of the follicular epithelium in the thyroid, fibrosis of the pancreatic islets, hyperplasia of the parathyroid epithelium, and changes of the acini in the extraorbital lacrymal gland. In aged-female rats sinusoid dilatation of the adrenal, and atrophy of the ovary were also noted. Perilobular fat deposition of the liver, dilatation of the gastric gland and severe hemosiderosis of the spleen were observed similar frequency in the both sexes. The nephropathy and cardiovasculopathy were major factors to cause death for males, while the main cause of death for females was tumors, especially of the mammary and pituitary glands. Enlargement of the parathyroid gland, bone resorption and metastatic calcification in the solf tissues were found in rats with severe nephropathy.

Aging↗
PubMed1977

Dynamic characteristics of F-actin and thin filaments in vivo and in vitro.

Measurements of birefringence, ultraviolet dichorism and quasielastic light scattering were carried out on F-actin in solution and on the thin filaments of glycerinated myofibrils. The birefringence of the I-bands of myofibrils was of the same order of magnitude as that of F-actin or the F-actin-tropomyosin-troponin complex oriented in vitro at the same concentration. The ultraviolet dichroism spectrum of the I-bands was very similar to that of F-actin or the F-actin complex in vitro, which is due to orientation of bound ADP and tryptophan residues in F-actin. Quasielastic light scattering measurements, electronmicroscopic observations and the analyses of the electro-optic effect of the I-bands suggested approximately the same flexibility for F-actin in vitro and for the thin filaments in vivo. These optical measurements which were made under various conditions provide evidence for a conformational change induced by calcium ions in F-actin both in vivo and in vitro. This conformational change was found to be amplified by the interaction of F-actin with myosin. This is a brief review of our investigation on the dynamics of F-actin and the thin filament in vivo and in vitro by optical methods.

Actins↗