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Biomedical subjects

Y Kudo

Publications and source records attributed to Y Kudo.

At least 451 records · Page 25Linked to original sources
PubMedDate not supplied

Codon usage and tRNA genes in eukaryotes: correlation of codon usage diversity with translation efficiency and with CG-dinucleotide usage as assessed by multivariate analysis.

The species-specific diversity of codon usage in five eukaryotes (Schizosaccharomyces pombe, Caenorhabditis elegans, Drosophila melanogaster, Xenopus laevis, and Homo sapiens) was investigated with principal component analysis. Optimal codons for translation were predicted on the basis of tRNA-gene copy numbers. Highly expressed genes, such as those encoding ribosomal proteins and histones in S. pombe, C. elegans, and D. melanogaster, have biased patterns of codon usage which have been observed in a wide range of unicellular organisms. In S. pombe and C. elegans, codons contributing positively to the principal component with the largest variance (Z1-parameter) corresponded to the optimal codons which were predicted on the basis of tRNA gene numbers. In D. melanogaster, this correlation was less evident, and the codons contributing positively to the Z1-parameter corresponded primarily to codons with a C or G in the codon third position. In X. laevis and H. sapiens, codon usage in the genes encoding ribosomal proteins and histones was not significantly biased, suggesting that the primary factor influencing codon-usage diversity in these species is not translation efficiency. Codon-usage diversity in these species is known to reflect primarily isochore structures. In the present study, the second additional factor was explained by the level of use of codons containing CG-dinucleotides, and this is discussed with respect to transcription regulation via methylation of CG-dinucleotides, which is observed in mammalian genomes.

Animals↗
PubMedDate not supplied

The regulation of type-I collagen synthesis by insulin-like growth factor-I in human osteoblast-like SaOS-2 cells.

The effect of insulin-like growth factor-I on collagen synthesis was studied using cultured human osteoblast-like SaOS-2 cells by measuring the incorporation of tritiated L-proline into immunoprecipitable type-I collagen. Tritiated L-proline incorporation into collagen was significantly stimulated by insulin-like growth factor-I in a time- and concentration-dependent manner. Unlabelled L-proline and alpha-(methylamino) isobutyric acid inhibited either the influx into cells, or the incorporation into collagen, of tritiated L-proline. The increase in incorporation of tritiated L-proline was significantly reduced by cycloheximide and actinomycin D. L-Proline incorporation into collagen was also stimulated by insulin-like growth factor-II, insulin-like growth factor-I analogues and insulin. The insulin-like growth factor-I-stimulated L-proline incorporation was inhibited by one of its binding proteins, insulin-like growth factor binding protein-4, in a concentration-dependent manner.

Cell Line↗
PubMedDate not supplied

The chloride-dependent depression by GABA in the frog spinal cord.

Spontaneous activities from ventral and dorsal roots of the isolated perfused spinal cord of the bullfrog were inhibited by GABA. beta-Alanine showed a strong and glycine a weaker inhibitory effect. The inhibitory effect of GABA was markedly reduced in a chloride-free medium, whereas glycine and beta-alanine still showed an inhibitory effect similar to that seen in normal medium. Employing the sucrose-gap method, a marked depolarization in the dorsal root and a small but obvious hyperpolarization in the ventral root were found by the application of GABA. These results support the view that GABA is one of the transmitters involved in pre- and postsynaptic inhibition of the spinal cord. The postsynaptic hyperpolarizing effect of GABA on motoneurones would be caused directly through increased permeability of the membrane to chloride ion. The depolarizing effect of GABA on primary afferent terminals is discussed in connection with chloride dependency.

Alanine↗
PubMedDate not supplied

The vestibular nerve: its course to the anterior and lateral ampullae.

The course of the ampullary nerve to the anterior and lateral ampullae was studied using 25 human temporal bones. Sudan Black B staining was applied to decalcified temporal bones in order to stain nerve fibers. After removing the external and middle ear, each temporal bone was divided into four blocks by three parallel planes, making an angle of 45 degrees to the long axis of the stapes footplate or a line along the stapedial tendon. Two planes were in contact with the anterior and posterior margin of the oval window, respectively. The third plane passed through the capitulum of the stapes. Distances from the upper margin of the oval window, to the distal and proximal part of the ampullary nerve, to the facial nerve, and to the utricular macula were measured in the third plane. The thickness of the thinnest part of the wall of the facial canal facing the stapes was also measured. A new surgical approach to the ampullary nerve is discussed.

Aged↗
PubMedDate not supplied

Expression of p53 and p21CIP1/WAF1 proteins in oral epithelial dysplasias and squamous cell carcinomas.

The expression of tumor suppressor gene, p53 and cyclin-dependent kinase inhibitor, p21 in oral epithelial dysplasia and oral squamous cell carcinoma (OSCC) was examined immunohistochemically and its relationship with clinicopathological findings was analyzed. Among 24 epithelial dysplasias, 4 cases (17%) expressed p53 protein and 23 cases (96%) expressed p21 protein. On the other hand, expression of p53 was observed in 64% of OSCCs, and expression of p21 was observed in 77% of OSCCs. In the analyses of the correlation between the expression of p53 and p21 in epithelial dysplasia and OSCC, 79% of epithelial dysplasias were p53-negative and p21-positive, compared to 25% of the OSCCs. p21 expression did not correlate with p53 expression. These results were also demonstrated in OSCC cell lines by western blot analysis. Cumulative survival rate of the patients p53-negative and p21-positive was higher than those p53-positive and p21-negative, those p53-negative and p21-negative and those p53-positive and p21-positive. These findings suggest that p53 expression and p21 negative expression may involve in neoplastic transformation of oral epithelium. In the present study, we did not observe correlation between the expression of p53 and p21 proteins in OSCC. p21 expression may be regulated by p53-independent pathways as well as p53-dependent ones. However, combination of the p21 and p53 expression may be useful as a prognostic marker.

Adult↗