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Biomedical subjects

Y Mitsui

Publications and source records attributed to Y Mitsui.

At least 343 records · Page 19Linked to original sources
PubMed1979

Effect of in vitro aging on 6-ketoprostaglandin F1 alpha-producing activity in cultured human diploid lung fibroblasts.

Prostaglandin synthesis in human diploid fibroblasts was studied by incubating [14C]-arachidonic acid with cell homogenates. The majority of prostaglandins produced in young cells was 6-ketoprostaglandin F1 alpha. The 6-ketoprostaglandin F1 alpha-producing activity of cultures declined with in vitro aging, and was almost undetectable at the senescent stage, while total production of thromboxane B2, prostaglandin F2 alpha and prostaglandin E2-like metabolites increased with in vitro aging.

Cells, Cultured↗
PubMed1979

A new cell surface marker of aging in human diploid fibroblasts.

The relationship of cell surface changes to proliferative decline of human diploid fibroblasts was investigated using the concanavalin A-mediated red blood cell adsorption assay. The amount of the red blood cells adsorbed to human diploid fibroblasts via concanavalin A increased continuously from the early phases of cell passage up through cell senescence, while the amount of 3H-concanavalin A binding did not change to a significant extent. The red blood cell adsorption is not a function of cell cycle phase and time spent in culture. Cocultivation of young cells with old cells also did not affect the adsorption capacity of respective cells. Thus, the concanavalin A-mediated red blood cell adsorption can be expected to serve as a new cell surface marker for aging in vitro. Using this marker, it was revealed that transient cell size or 3H-thymidine incorporating capacity di not have a direct relationship with the division age of a cell. Small rapidly dividing cells in old populations resemble large slowly dividing or nondividing cells of the same populations and differ from small rapidly dividing cells in young populations, in terms of cell surface properties.

Cell Adhesion↗
PubMed1978

Studies on the binding of adenylyl-3', 5'-cytidine to ribonuclease.

The interaction of adenylyl-3',5'-cytidine (ApC) with ribonuclease-A (RNAase-A) was studied by steady-state kinetics and ultraviolet difference spectroscopy. X-ray difference Fourier synthesis at 4 A resolution was also used to study the binding of ApC to RNAase-S. Unlike well-studied compounds like uridylyl-3',5'-adenosine, ApC binds in an unique way: (1) the cytidine moiety is bound to the B1 and R1 sites, (2) the adenosine moiety protrudes to the solution and is not fixed spatially and (3) the phosphate group is bound to the non-specific site (the "Po site") previously postulated (Sawada, F. and Irie, M. (1969) J. Biochem. (Tokyo) 66, 415--418) as the binding site for the 5'-phosphate of uridine 2',5'-diphosphate or uridine 3',5'-diphosphate. This conclusion is consistent with that derived for adenylyl-3',5' -4-thiouridine based on CD difference spectroscopy (White, M.D., Keren-Zur, M. and Lapidot, Y. (1977) Nucleic Acid Res. 4, 843--851). The "Po site" is most likely the epsilon-amino group of Lys 66.

Adenine Nucleotides↗
PubMed1978

Crystal structure of monoclinic ribonuclease-S at 4 A resolution. The mode of binding of 4-thiouridylic acid and a fragment of folic acid, p-aminobenzoylglutamic acid.

A four-A electron density map was calculated for the monoclinic crystal of ribonuclease-S (RNase-S) based on two heavy-atom derivatives. Close geometrical similarity was found between the two crystallographically independent RNase-S molecules (called molecules ZA and ZB) in this crystal and that (called molecule Y) in the trigonal crystal. Using the rotational and translational parameters relating these three molecules, it was established that the crystallographic two-fold symmetry between the two molecules ZA in the monoclinic crystal was exactly identical to that between the two molecules Y in the trigonal crystal, suggesting the tendency of RNase-S molecules to associate in this way although the interaction is weak. The 4-A difference Fourier maps calculated for the monoclinic crystal established the following conclusions. (1) 4-Thiouridine-2'(3')-monophosphates binds to the B1 and R1 sites like other pyrimidine nucleoside-2'(3')-monophosphates as expected from previous spectrophotometric studies, but not to the B2 site even at the concentration of 20 mM. An attempt to visualize the photoproduct generated by irradiation of near-ultraviolet light in this complex failed. (2) p-Aminobenzoylglutamic acid, a fragment of folic acid, seems to bind to RNase-S with its benzene ring close to the B2 site and the alpha-carboxylate group close to the p1 site. The model is compatible with most of the chemical results obtained by Sawada et al. ((1977) Biochim. Biophys. Acta 479, 188-197).

4-Aminobenzoic Acid↗