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Biomedical subjects

H Okada

Publications and source records attributed to H Okada.

At least 955 records · Page 53Linked to original sources
PubMed1988

[Pharmacokinetic and clinical studies on ceftriaxone in the perinatal period].

The pharmacokinetics of ceftriaxone (CTRX) and its clinical efficacy in perinatal infections were studied. The obtained results are summarized as follows. 1. Concentrations of CTRX in maternal serum, umbilical cord serum and amniotic fluid were determined following intravenous injection with 1 g of CTRX. Maternal serum levels were not lower than 100 micrograms/ml immediately after administration, and gradually decreased to about 10 micrograms/ml in 12 hours, and to 4 micrograms/ml in 24 hours. The half-life of CTRX in maternal serum was 5.6 hours. CTRX levels in umbilical cord serum were about 7 micrograms/ml at 10 minutes after injection, increasing to 12 to 13 micrograms/ml in 12 hours and decreasing to 5 micrograms/ml in 24 hours. CTRX levels in amniotic fluid were slightly lower than those in the umbilical cord serum, and about 2 micrograms/ml at 10 minutes after injection, and they remained at 4 to 8 micrograms/ml thereafter for 28 hours. 2. CTRX (1 g) was intravenously administered twice daily to 9 patients with perinatal infections for 3 to 7 days. Clinical efficacies of CTRX were judged excellent in 2 cases and good in 7, suggesting that CTRX was effective in all cases. No side effects or laboratory abnormalities were observed in any case. As a result of these findings, CTRX may be considered a very useful antibiotic in perinatal infections.

Amniotic Fluid↗
PubMed1987

Catalase gene of the yeast Candida tropicalis. Sequence analysis and comparison with peroxisomal and cytosolic catalases from other sources.

A clone harbouring the genomic DNA sequence for the peroxisomal catalase of an n-alkane-utilizable yeast, Candida tropicalis, has been isolated by the hybrid-selection method and confirmed with a probe of catalase partial cDNA. Nucleotide sequence analysis of the cloned DNA disclosed that the gene fragment coding for catalase had a length of 1455 base pairs (corresponding to 485 amino acids; m = 54937 Da), and that the size of this enzyme was the smallest among all catalases reported hitherto. No intervening sequence was found in this coding region and some portions coincided with the amino acid sequences obtained from the analysis of the purified catalase. The comparison with three peroxisomal catalases from rat liver, bovine liver and human kidney, and one cytosolic catalase from Saccharomyces cerevisiae has revealed that catalase from C. tropicalis was more homologous to the peroxisomal enzymes than to the cytosolic one. C. tropicalis used the codons of the high-expression type. Amino acid residues were all conserved at the active and heme-binding sites. In the N and C-terminal regions there was no characteristic signal sequence or consensus sequence. However, a noticeable region, which can be discriminated between peroxisomal and cytosolic catalases, was proposed.

Amino Acid Sequence↗
PubMed1987

[The inhibitory effect of miconazole on aromatase activity for androstenedione in human placental and ovarian preparations].

The inhibitory effects of miconazole, an antimycotic agent, on aromatase activity for androstenedione in human placenta (105,000 X g pellet fraction) and ovary (800 X g supernatant fraction) were investigated. Various concentrations (0.1-100 microM) of miconazole, aminoglutethimide or delta 1-testololactone were added to the human placental preparation (1 mg protein) and then the mixture was incubated with [1 beta-3 H]-androstenedione (300 pmol) and NADPH (0.5 mg), at 37 degrees C for 30 minutes in air. The reaction was stopped by 10%-trichloroacetic acid (0.8 ml) and the mixture was extracted with chloroform (3 ml). The residual aqueous phase was subjected to Amberlite XAD-II resin-charcoal column chromatography. The amount of 3H2O obtained was regarded as aromatase activity for androstenedione. The effects of miconazole on aromatase activity in human ovarian preparation was also investigated. Aromatase activity in human placenta was suppressed concentration-dependently by miconazole. The inhibition of aromatase activity by miconazole was significantly higher than that by aminoglutethimide and delta 1-testololactone. The I50 values for the inhibition of aromatase activity by miconazole, aminoglutethimide and delta 1-testololactone were 0.60 microM, 15 microM and 34 microM, respectively. The apparent Km value for androstenedione was 320 nM and the apparent Ki value was 120 nM in this assay. The inhibition of aromatase by miconazole in human ovary was also significantly higher than that by aminoglutethimide (I50 value for miconazole = 0.98 microM; I50 value for delta 1-testololactone = 15 microM). These results indicate that miconazole suppresses aromatase activity for androstenedione reversibly in human placenta and ovaries in vitro.

Aminoglutethimide↗
PubMed1987

Isolation of several cDNAs encoding yeast peroxisomal enzymes.

Several candidate clones carrying partial cDNAs for yeast peroxisomal enzymes, such as catalase, carnitine acetyltransferase, isocitrate lyase, malate synthase and acyl-CoA oxidase, were efficiently isolated at a single plating from a phage lambda gt11 recombinant cDNA library prepared with poly(A)-rich RNA from an n-alkane-grown yeast, Candida tropicalis, with a mixture of antibodies against the respective purified enzymes. Among them, one candidate clone carrying partial cDNA for catalase was subcloned and subjected to nucleotide sequence analysis. We succeeded in determining that the amino acid sequence deduced from the nucleotide analysis included the sequences derived from the two peptide fragments obtained from the purified enzyme.

Amino Acid Sequence↗
PubMed1987

Structure and expression of genes coding for xylan-degrading enzymes of Bacillus pumilus.

The complete nucleotide sequence of the beta-xylosidase gene (xynB) of Bacillus pumilus IPO and its flanking regions was established. A 1617-bp open reading frame for beta-xylosidase, a homodimer enzyme, was observed. The amino acid sequence of the N-terminal region and the molecular mass 62607 Da) of the beta-xylosidase subunit, deduced from the DNA sequence, agreed with the result obtained with the purified enzyme. The Shine-Dalgarno sequence was found 8 bp upstream of the initiation codon, ATG. The xylanase gene (xynA) of the same strain was 4.6 kbp downstream of the 3' end of xynB, and its DNA sequence was reported in our previous paper [Fukusaki, E., Panbangred, W., Shinmyo, A. & Okada, H. (1984) FEBS Lett. 171, 197-201]. The results of the Northern hybridization suggested that the mRNA of xynA and xynB were produced separately. The 5' and 3' ends of the xynA and xynB gene were mapped with nuclease S1. The '-10' regions for promoter sequences of both genes were similar to the consensus sequence for B. subtilis RNA polymerases, the '-35' regions were different from all the known promoters for B. subtilis RNA polymerases.

Amino Acid Sequence↗
PubMed1987

Crystallization and preliminary X-ray studies of Bacillus pumilus IPO xylanase.

The xylan-degrading enzyme xylanase, from Bacillus pumilus IPO, has been crystallized. The crystals are monoclinic, space group P21 with a = 40.8 A, b = 66.8 A, c = 34.7 A and beta = 103.0 degrees. The asymmetric unit contains one molecule of Mr 22,500. The crystals diffract to at least 2.5 A resolution, and they are suitable for X-ray crystal structure analysis at high resolution.

Bacillus↗
PubMed1987

Sensitization of human tumor cells to homologous complement by vaccinia virus treatment.

Although cell membranes have potent inhibitors which protect the activation of complement on the self cell membranes, some viruses have been shown to activate complement via the alternative pathway on the virus-infected cells. Tumour cells have been made reactive to homologous complement following treatment with such viruses and became highly immunogenic to syngeneic host guinea pigs and mice. Vaccinia virus (VV) made murine tumour cells highly immunogenic thus generating complement activating capacity on the infected cells. Since it has been suggested that VV can make some human tumour cells immunogenic to the cancer patients, we examined VV to see if the virus also has the capacity to make human tumour cells reactive with homologous human complement. Our present results indicate that not only is this the case but ultraviolet-treated VV also has the same effect.

Complement Activation↗
PubMed1987

Blood type compatibility of lower vertebrates: phylogenetic diversity in blood transfusion between fish species.

Bidirectional transfusion was investigated using phylogenetically different fish species, including twelve from ten genera. Three different modalities were used: long-lasting persistence when rainbow trout received allogenic erythrocytes, slow rejection when rainbow trout received heterogenic erythrocytes (salmon) and acute rejection after receiving xenogenic erythrocytes (goldfish, carp and Tilapia). Changes were measured in serum using transfused erythrocytes and hemolytic assays. The responses were species specific for large taxonomic fish groups characteristic of their phylogenetic interrelations. Findings concerning the evolution of compatibility of fish blood types, in view of the taxonomy and phylogeny of vertebrates, are interesting since phylogenetic diversity in transfusion demonstrates that erythrocyte types and serum types exist even in lower vertebrates.

Animals↗