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Biomedical subjects

T Yagi

Publications and source records attributed to T Yagi.

At least 757 records · Page 42Linked to original sources
PubMedDate not supplied

Protective effects of sodium selenite on killing and mutation by N-methyl-N'-nitro-N-nitrosoguanidine in E. coli.

Sodium selenite was found to protect Escherichia coli cells against killing and mutagenic effects of N-methyl-N'-nitro-N-nitrosoguanidine (MNNG). Such protective effects were not observed when cells were treated with N-methyl-N-nitrosourea (MNU). The protection by sodium selenite was not controlled by the ada gene, which is responsible for the repair of alkylated damage in DNA. A reduction of the amount of glutathione was found when cells were treated with sodium selenite, and glutathione is known to be involved in the methylation of DNA by MNNG, not by MNU. Reduced methylation by MNNG due to the reduction of the amount of glutathione caused by abundant sodium selenite was suggested to be the mechanism of protection.

Escherichia coli↗
PubMedDate not supplied

Excision repair of mouse and human fibroblast cells, and a factor affecting the amount of UV-induced unscheduled DNA synthesis.

Excision-repair ability and the amount of unscheduled DNA synthesis (UDS) after UV irradiation of fibroblast cells (in vitro passage 5) from C57BL mouse embryos were compared with those of human skin fibroblast cells. UDS in the mouse cells was approximately 75% of that in the human cells, although the disappearance of T4 endonuclease-V-susceptible sites and the accumulation of single-strand breaks in the mouse cell DNA indicated that the excision-repair capacity of the mouse cells was 20-35% of that in the human cells. This apparent discrepancy was ascribed to the difference in intracellular dTTP pool size, which was approximately twice as large in the human cells as in the mouse cells. UDS may not be suitable as a quantitative measure of excision repair when comparing the cells from different species.

Animals↗
PubMedDate not supplied

Amino acid sequence and function of rubredoxin from Desulfovibrio vulgaris Miyazaki.

Rubredoxin was purified from Desulfovibrio vulgaris Miyazaki. It was sequenced and some of its properties determined. Rubredoxin is composed of 52 amino acids. It is highly homologous to that from D. vulgaris Hildenborough. Its N-terminal methionyl residue is partially formylated. The millimolar absorption coefficients of the rubredoxin at 489 nm and 280 nm are 8.1 and 18.5, respectively, and the standard redox potential is +5 mV, which is slightly higher than those of other rubredoxins. Rubredoxin, as well as cytochrome c-553, was reduced with lactate by the action of lactate dehydrogenase of this organism, and the reaction was stimulated with 2-methyl-1,4-naphthoquinone. It is suggested that rubredoxin, in collaboration with membranous quinone, functions as a natural electron carrier for cytoplasmic lactate dehydrogenase of this organism, whereas cytochrome c-553 plays the same role for periplasmic lactate dehydrogenase.

Amino Acid Sequence↗
PubMedDate not supplied

A role for Fyn tyrosine kinase in the suckling behaviour of neonatal mice.

Non-receptor-type tyrosine kinases of the Src family, such as Src, Yes and Fyn, are strongly expressed in the brain and have been suggested to have an important function in the central nervous system. We generated Fyn-deficient mice by inserting the beta-galactosidase gene (lacZ) into the fyn gene. The homozygous Fyn-mutant neonates from homozygous Fyn-deficient parents died because of a suckling problem. Neonates were, however, able to suckle milk normally when the homozygous mother's mammary glands had been activated by suckling of a heterozygous or wild-type pup. In these homozygous pups, the modified glomerular complex of the olfactory bulb, which had been suggested to play a role in perceiving pheromones, was abnormal in shape and reduced in size, and the hippocampal cell-layer was undulated. These results suggest that Fyn may be involved in the initial step of instinctive suckling behaviour in neonates.

Animals↗
PubMedDate not supplied

Visual abnormalities and occipital EEG discharges: risk factors for West syndrome.

Seventeen infants (7 boys and 10 girls) with visual abnormalities (such as poor tracking and following and nystagmoid eye movement) and occipital slow activities with irregular polyspikes on EEG were studied. Two thirds of the children showed development of West syndrome with hypsarrhythmia on follow-up EEG. In 1 child, hypsarrhythmia was evident on the follow-up EEG, but no clinical seizures occurred. Because most of the children in our series developed West syndrome, patients with visual abnormalities associated with occipital EEG discharges in early infancy may be at high risk for West syndrome. Occipital abnormalities in early infancy may relate to the occurrence of West syndrome.

Child, Preschool↗
PubMedDate not supplied

Passive transfer of experimental autoimmune labyrinthitis.

The aim of the present study was to establish an animal model of autoimmune labyrinthitis using heterologous inner ear antigen (IEAg) and to elucidate whether the experimentally induced labyrinthitis could be passively transferred. Cochlear and vestibular membranous labyrinthine tissues from bovine temporal bones were used as IEAg. Donor mice were inoculated intracutaneously at multiple sites with an emulsion consisting of equal parts of IEAg and complete Freund's adjuvant. After 10 days, mononuclear cells were collected from lymph nodes, spleen and blood of the donor mice and injected intravenously into naive recipient mice. Cellular infiltration was observed in the perilymphatic space of the cochlea of all donor and recipient mice. Endolymphatic hydrops was also observed in 63% of donor and 42% of recipient mice. These findings suggest that the experimentally induced labyrinthitis observed in this animal model was probably due to an autoimmune reaction to the IEAg and was passively transferred by a cell-mediated immune reaction.

Animals↗
PubMedDate not supplied

Acquired and congenital cholesteatoma: determination of tumor necrosis factor-alpha, intercellular adhesion molecule-1, interleukin-1-alpha and lymphocyte functional antigen-1 in the inflammatory process.

The molecular and cellular factors resulting in the pathologic features of acquired and congenital cholesteatomas are not completely known. Recently, proinflammatory cytokines like interleukin-1 alpha (IL-1 alpha) and tumor necrosis factor-alpha (TNF-alpha) have been shown to induce bone resorption, in vitro. To elucidate the key molecules involved in bone resorption and cell infiltration associated with cholesteatoma, we examined the in vivo levels of IL-1 alpha and TNF-alpha, intercellular adhesion molecule-1 (ICAM-1) and lymphocyte functional antigen-1 (LFA-1) in acquired and congenital cholesteatomas, by reverse transcriptase-polymerase chain reaction, immunohistochemistry, and ELISA. Increased levels of IL-1 and TNF-alpha were detected in both types of cholesteatomas as compared to normal skin. Increased ICAM-1 expression and LFA-1+ cells were detected in acquired but not congenital cholesteatoma. Strong correlation was detected between TNF-alpha and bone resorption in both types of cholesteatoma, and between TNF-alpha and ICAM, TNF-alpha and severity of infection, or cell infiltration in acquired cholesteatoma. No correlation existed between various parameters and IL-1 alpha. These results suggest that TNF-alpha may play a crucial role in the pathogenesis of both acquired and congenital cholesteatomas by regulating bone resorption and cell infiltration.

Adult↗
PubMedDate not supplied

Expression of inducible nitric oxide synthase in the cochlea following immune response in the endolymphatic sac of guinea pigs.

Immunohistochemical study for inducible nitric oxide synthase (iNOS or NOS II) in the cochlea of guinea pigs was performed after the injection of keyhole limpet hemocyanin (KLH) into the endolymphatic sac. Morphological changes were observed in the cochlea of all animals after the injection of KLH. Increased iNOS expression was detected in the lateral wall, organ of Corti and ganglion cells. It is known that high levels of nitric oxide can lead to inner ear dysfunction. Our results suggest that iNOS may mediate the inner ear disturbance as seen in endolymphatic hydrops.

Adjuvants, Immunologic↗
PubMedDate not supplied

Three-dimensional Hi-Vision video imaging in ear surgery.

We report here a newly developed video system which combines a three-dimensional and high-definition television system (Hi-Vision) for microsurgery of the ear. This system provides a high-quality three-dimensional documentation for easy understanding of the otherwise difficult to visualize areas in the of the otomicrosurgical procedure, making it convenient and beneficial for easy understanding of the otherwise difficult to visualize areas in the middle and inner ear, especially in the context of postgraduate training.

Acoustic Impedance Tests↗