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M Yonezawa

Publications and source records attributed to M Yonezawa.

At least 55 records · Page 3Linked to original sources
PubMed1995

Analysis of the NH2-terminal 83rd amino acid of Escherichia coli GyrA in quinolone-resistance.

Artificial mutations of Gyrase A protein (GyrA) in Escherichia coli by site-directed mutagenesis were generated to analyze quinolone-resistant mechanisms. By genetic analysis of gyrA genes in a gyrA temperature sensitive (Ts) background, exchange of Ser at the NH2-terminal 83rd position of GyrA to Trp, Leu, Phe, Tyr, Ala, Val, and Ile caused bacterial resistance to the quinolones, while exchange to Gly, Asn, Lys, Arg and Asp did not confer resistance. These results indicate that it is the most important for the 83rd amino acid residue to be hydrophobic in expressing the phenotype of resistance to the quinolones. These findings also suggest that the hydroxyl group of Ser would not play a major role in the quinolone-gyrase interaction and Ser83 would not interact directly with other amino acid residues.

4-Quinolones↗
PubMed1995

Analysis of the NH2-terminal 87th amino acid of Escherichia coli GyrA in quinolone-resistance.

The functional contributions of amino acid residue Asp87 of Escherichia coli gyrase A protein (GyrA) was analyzed by site-directed mutagenesis. We generated a series of mutants, in which Asp87 of GyrA was changed to Ala, Val, Phe, Asn, Ser, and Lys. By genetic analysis of gyrA genes in a gyrA temperature-sensitive (Ts) background, it was shown that all these mutations caused the quinolone-resistance. These results indicate that the 87th amino acid of E. coli GyrA must have negative charge in expressing the phenotype of quinolone sensitivity. These findings also suggest that the carboxyl group of Asp87 may interact with quinolone drugs.

4-Quinolones↗
PubMed1995

DNA gyrase gyrA mutations in quinolone-resistant clinical isolates of Pseudomonas aeruginosa.

The mutations in the quinolone resistance-determining region of the gyrA gene from clinical isolates of Pseudomonas aeruginosa were determined by DNA sequencing. The strains were isolated in 1989 and 1993. No mutations were detected in the clinical isolates in 1989, while five types of mutations were identified in the isolates in 1993. These mutations were as follows: group 1, a Thr residue to an Ile residue at position 83 (Thr-83-Ile); group 2, Asp-87-Asn; group 3, Thr-83-Ile and Asp-87-Gly; group 4, Thr-83-Ile and Asp-87-Asn; group 5, Thr-83-Ile and Asp-87-His. Three types of double mutations (groups 3, 4, and 5) have not been described previously. These mutations were homologous to the Ser-83-Leu, Asp-87-Asn, and Asp-87-Gly changes observed in Escherichia coli. Thus, DNA gyrase A subunit mutations are implicated in resistance to quinolones in P. aeruginosa as well as E. coli.

4-Quinolones↗
PubMed1994

Factors related to resistance to hematopoietic death in mice.

Mouse strain difference in the radiosensitivity to hematopoietic death is thought to be determined by several factors besides radiosensitivity and the initial number of hematopoietic stem cells. Factors related to the survival of mice exposed to X-irradiation were analyzed using BALB/cHeA and STS/A strains whose LD50/30 values differ markedly (BALB/cHeA, 5.55 Gy; STS/A, 8.45 Gy). STS/A mice exposed to 4 Gy of X-irradiation showed a small reduction but rapid recovery of blood cells (leukocytes, erythrocytes, and thrombocytes) when compared with BALB/cHeA mice. The survival of endogenous and exogenous CFU-S was much higher, by a magnitude of one log or more, in STS/A mice than those in BALB/cHeA mice; whereas the initial numbers of femoral CFU-S were similar for the two strains. The recovery of exogenous CFU-S was much more rapid in STS/A mice than it was in BALB/cHeA mice after 4 Gy of X-irradiation. Furthermore, spleen colonies produced by the transfusion of STS/A marrow cells into syngeneic recipients were significantly larger than those produced by BALB/cHeA marrow cells, regardless of whether the mice used for sources of marrow cells had been irradiated. But, there was no such difference when unirradiated marrow cells from the two strains were transfused into (BALB/cHeA X STS/A) F1 recipients. These results indicate the possible contribution of a host factor (s) that stimulates the growth of spleen colonies after radiation to the radioresistance of STS/A mice, in addition to the primary effect of higher number of survivals of endogenous and exogenous CFU-S in STS/A mice.

Animals↗
PubMed1994

Successful treatment of metastatic pulmonary tumors by bronchial arterial infusion chemotherapy in two patients with locally well controlled uterine cancer.

Pulmonary metastatic tumors in two patients with locally well controlled uterine cancer were treated with bronchial arterial infusion chemotherapy. The first patient underwent a radical hysterectomy and pelvic lymphadenectomy for stage IIb cervical cancer. Fifteen months after the operation, pulmonary metastasis was identified. Clinical evidence of tumor was negative after bronchial arterial infusion chemotherapy, systemic chemotherapy and radiotherapy. The patient continues to be healthy without recurrent signs six years after bronchial arterial infusion chemotherapy. The second patient underwent a radical hysterectomy and pelvic lymphadenectomy for stage II endometrial cancer. Fifteen months after the operation, pulmonary metastasis was identified. After bronchial arterial infusion chemotherapy and systemic chemotherapy, regression of the tumors was observed. This patient has also survived for two years since the lung metastases. These results indicate that bronchial arterial infusion chemotherapy is a potent treatment for pulmonary metastases of uterine cancer.

Adult↗
PubMed1993

Establishment of an enzyme immunoassay system for gliostatin/platelet-derived endothelial cell growth factor (PD-ECGF).

A two-site enzyme immunoassay for gliostatin (GLS)/platelet-derived endothelial cell growth factor (PD-ECGF) has been developed. The detection limit of gliostatin/PD-ECGF was 30 pg/well, and the optimal assay range was 0.1 to ng/well. This assay system enabled us to confirm the immunochemical identity of both factors and to detect immunoreactive gliostatin/PD-ECGF (IR-GLS/PD-ECGF) in human biological body fluids. The age-related analysis from newborn to 69 years revealed that the serum IR-GLS/PD-ECGF level was high in infants younger than 1 year old (1.8 ng/ml) and in the 20-year-old age group (1.8 ng/ml), and highest in the umbilical cord blood (2.1 ng/ml). Curiously high concentrations were detected in saliva with a significant sex difference (11.3 ng/ml for males and 48.7 ng/ml for females), and in synovial fluids (3.7 ng/ml). A number of human tumor cells, gastric cancer cells, MKN-74, neuroblastoma cells, GOTO, as well as epidermoid carcinoma cells, A431, were found to produce a significant amount of IR-GLS/PD-ECGF (0.2 to 21.8 ng/mg protein), and some of them secreted the IR-GLS/PD-ECGF in the conditioned medium (approximately 0.5 ng/ml). The enzyme immunoassay system is sufficiently sensitive for the basic and clinical study of gliostatin/PD-ECGF in human body fluids, tissues and organs.

Adolescent↗
PubMed1993

MRI visualization of complete bilateral optic nerve involvement by pituitary adenoma: a case report.

With large pituitary adenomas, the optic nerves and chiasm usually lie on the tumour capsule and are displaced superiorly. We report a large invasive pituitary adenoma, with complete involvement of both optic nerves. Review of the preoperative MR images demonstrated the optic nerves, with signal intensity close to that of cerebral white matter, and different from the flow void of the basal cerebral arteries. Correlation of this observation with intraoperative findings is discussed.

Adenoma↗
PubMed1993

Role of the amino-terminal amino acid sequences determining the in vitro refolding process of prochymosin polypeptide.

Prochymosin, a zymogen of an aspartic proteinase chymosin, is produced as inclusion bodies in the recombinant Escherichia coli cells. Solubilization of the inclusion bodies with 8 M urea followed by dialysis at pH 10.5 achieves correctly refolded prochymosin to some extent, which is then activated by self-processing at acidic pHs. Analyses of the alkaline dialysates by anion exchange chromatography revealed broad distribution of prochymosin polypeptides with different conformations. Stepwise dialysis with a slower decreasing rate of urea resulted in marked improvement of the yield of correctly refolded molecules. A hybrid prochymosin (CR601) possessing a short NH2-terminal replacement with the trp-leader peptide was not refolded into the correct conformation by one-step dialysis, but it was by stepwise dialysis. Replacement of Lys at the NH2-terminal second position of CR601 with Asp or Glu caused marked enhancement of correct refolding. These findings suggest that the amino acid sequence in the NH2-terminal region of prochymosin plays a crucial role in determining the whole refolding process of the polypeptide.

Amino Acid Sequence↗
PubMed1993

Changes of hemorheologic properties during normal human pregnancy.

To investigate alterations of hemorheologic properties during pregnancy, we measured the hematocrit (Hct) and fibrinogen levels, blood viscosity, and erythrocyte deformability in 10 healthy nonpregnant women and in 10 women with uncomplicated pregnancies. The Hct decreased during pregnancy, while the plasma fibrinogen concentration was elevated. No significant changes in blood viscosity were observed throughout pregnancy. Erythrocyte deformability was significantly decreased in pregnancy when compared to the nonpregnant state, but returned to the nonpregnant level by the 7th postpartum day. These findings suggest that adequate microcirculation is maintained in the uteroplacental unit during gestation by hemodilution, which prevents an elevation of blood viscosity despite the increase in fibrinogen and the decrease of erythrocyte deformability. These changes are thus thought to be among the physiological maternal adaptations to fetal growth and development.

Adult↗
PubMed1993

Pulmonary carcinoma associated with hamartoma in an 11-year-old boy.

PURPOSE: We describe a poorly differentiated adenocarcinoma of the lung in an 11-year-old boy who had had a pulmonary hamartoma for at least 8 years. CONCLUSIONS: A hamartoma, even if clinically silent, may lead to the development of malignant tumors on rare occasions.

Adenocarcinoma↗
PubMed1992

Developmental changes of glutamate dehydrogenase activity in rat liver mitochondria and its enhancement by branched-chain amino acids.

The developmental changes of glutamate dehydrogenase activity in the fetal and neonatal rat liver were investigated, as well as the effects of branched-chain amino acids on this enzyme. Hepatic glutamate dehydrogenase activity showed a marked increase at the end of the fetal period and peaked on the 5th day of neonate at approximately 3 times higher than the adult level. Glutamate dehydrogenase was activated by leucine, isoleucine, and valine in this order when they were added to isolated intact liver mitochondria in vitro. The enhancement of enzyme activity was more marked in fetal rats than in adults. In contrast, when branched-chain amino acids were added after disrupting the mitochondrial membrane by sonication, only leucine slightly activated glutamate dehydrogenase, while isoleucine and valine slightly inhibited its activity. Our findings suggest that glutamate may be actively synthesized in the developing rat liver mitochondria and then transaminated to other nonessential amino acids for protein synthesis, and that increased intramitochondrial branched-chain amino acid concentrations may enhance glutamate dehydrogenase activity. This anabolic metabolism will contribute to the fetal growth and development.

Amino Acids, Branched-Chain↗
PubMed1992

Development changes of polyamine biosynthesis in rat liver.

To investigate the role of polyamine metabolism in fetal development, we determined the hepatic polyamine content and the activity of enzymes related to polyamine metabolism in fetal, newborn and adult rats. In the fetuses, spermidine was detected at the highest level, followed by spermine and then putrescine. Putrescine and spermidine levels were higher in the fetuses than in adult rats, while the spermine level was significantly lower in the fetuses. The activities of the enzymes investigated were also higher in the fetuses than in adult rats. These findings indicate that polyamine synthesis was enhanced in the fetal liver, and that degradation of spermidine via spermidine N1-acetyltransferase contributes to the increase in putrescine levels. Thus, our study suggests that an increase in putrescine is important for fetal growth and that putrescine per se has a significant role in fetal cellular proliferation.

Acetyltransferases↗