PubMed Health⌕ Search

Biomedical subjects

Y Katakura

Publications and source records attributed to Y Katakura.

77 records · Page 5Linked to original sources
PubMedDate not supplied

Effect of prenatal exposure to styrene on the neurobehavioral development, activity, motor coordination, and learning behavior of rats.

Maternal Wistar rats were exposed via inhalation to 0, 50, or 300 ppm styrene for 6 h/day during gestation days 7 to 21, and offspring were subsequently evaluated in several neurobehavioral tests. Preliminary results with a small number of litters revealed significant dose-dependent effects in tests performed prior to weaning (surface righting, pivoting locomotion, and bar holding), as well as in tests performed after weaning (motor coordination, open-field behavior, and motor activity). Exposure to low concentrations of styrene (50 ppm) caused disturbances in motor coordination in addition to delaying some motor and reflex developments. Large doses (300 ppm) led to changes in open-field behavior and increases in spontaneous activity in addition to the delay in neurobehavioral developments. Exposure of dams to styrene did not clearly affect the learning behavior of the offspring. It was also observed that age played a role in the differences in styrene's effects on neurobehavioral function. Only subtle effects were found in both open-field behavior and motor-coordination function when compared with control rats at 120 days of age. These results suggest that the functional neurobehavioral development of progeny of dams exposed to styrene (or other solvents) should be further investigated.

Animals↗
PubMedDate not supplied

Fluorescence polarization study of a salt bridge between a single chain Fv and its antigen ribonuclease A.

The interaction between a single chain Fv (sFv) of the monoclonal antibody 3A21 and its antigen, bovine pancreatic ribonuclease A (RNase A), was studied by site-directed mutagenesis of the hypervariable regions and fluorescence polarization analysis. The affinity constants of wild-type sFv and a mutant sFv D31A (Asp31 of heavy chain was replaced by Ala) for RNase A were found to be 2.7 x 10(7) and 4.7 x 10(6) M(-1) in PBS at pH 7.2 and 37 degrees C, respectively. Whereas the affinity constant of D31A is not affected by NaCl concentration, that of wild-type sFv is almost the same as that of D31A in the presence of more than 1 M NaCl. These results demonstrate that Asp31 of the heavy chain interacts electrostatically with a positively charged amino acid residue of RNase A.

Animals↗
PubMedDate not supplied

Amplified gene location in chromosomal DNA affected recombinant protein production and stability of amplified genes.

Previously, we established an easy and quick construction method for obtaining a stable and highly productive gene-amplified recombinant Chinese hamster ovary (CHO) cell line. With a gradual increase in methotrexate (MTX) concentration, gene-amplified cell pools had high and stable specific growth and production rates. Moreover, the phenotype of gene-amplified cells seemed to be affected by the location of the amplified gene in chromosomal DNA. We suspected that various kinds of gene-amplified cells might appear during the long-term selection to construct gene-amplified cell pools. To clarify the behavior of gene-amplified cell pools during a stepwise increase of MTX concentration, we isolated gene-amplified clones derived from gene-amplified cell pools. We compared the characteristics of isolated clones, such as the productivity of recombinant protein, stability of amplified genes, and the location of amplified genes. As a result, telomere-type clones, in which the amplified gene was located near the telomeric region, were found to be more stable and productive than other types of clones. Telomere-type clones had over 100 copies of amplified genes in the chromosomal DNA. In contrast, a large number of other types of clones had less than 10 copies of amplified genes. During long-term cultivation in the absence of MTX, in other types of clones, amplified genes rapidly decreased in the chromosomal DNA.

Animals↗