PubMed Health⌕ Search

Biomedical subjects

J Kataoka

Publications and source records attributed to J Kataoka.

At least 19 recordsLinked to original sources
PubMed2002

The acceleration of cosmic-ray protons in the supernova remnant RX J1713.7-3946.

Protons with energies up to approximately 10(15) eV are the main component of cosmic rays, but evidence for the specific locations where they could have been accelerated to these energies has been lacking. Electrons are known to be accelerated to cosmic-ray energies in supernova remnants, and the shock waves associated with such remnants, when they hit the surrounding interstellar medium, could also provide the energy to accelerate protons. The signature of such a process would be the decay of pions (pi(0)), which are generated when the protons collide with atoms and molecules in an interstellar cloud: pion decay results in gamma-rays with a particular spectral-energy distribution. Here we report the observation of cascade showers of optical photons resulting from gamma-rays at energies of approximately 10(12) eV hitting Earth's upper atmosphere, in the direction of the supernova remnant RX J1713.7-3946. The spectrum is a good match to that predicted by pion decay, and cannot be explained by other mechanisms.

Journal Article↗
PubMed2000

Molecular cloning and characterization of a gene encoding glutaminase from Aspergillus oryzae.

A glutaminase from Aspergillus oryzae was purified and its molecular weight was determined to be 82,091 by matrix-assisted laser desorption ionization time-of-flight mass spectrometry. Purified glutaminase catalysed the hydrolysis not only of L-glutamine but also of D-glutamine. Both the molecular weight and the substrate specificity of this glutaminase were different from those reported previously [Yano et al. (1998) J Ferment Technol 66: 137-143]. On the basis of its internal amino acid sequences, we have isolated and characterized the glutaminase gene (gtaA) from A. oryzae. The gtaA gene had an open reading frame coding for 690 amino acid residues, including a signal peptide of 20 amino acid residues and a mature protein of 670 amino acid residues. In the 5'-flanking region of the gene, there were three putative CreAp binding sequences and one putative AreAp binding sequence. The gtaA structural gene was introduced into A. oryzae NS4 and a marked increase in activity was detected in comparison with the control strain. The gtaA gene was also isolated from Aspergillus nidulans on the basis of the determined nucleotide sequence of the gtaA gene from A. oryzae.

Amino Acid Sequence↗
PubMed1997

IFN-gamma-inducing factor (IGIF) is a costimulatory factor on the activation of Th1 but not Th2 cells and exerts its effect independently of IL-12.

We have previously reported the cloning of a novel cytokine, IFN-gamma-inducing factor (IGIF), which shared some biologic activities with IL-12. In this study, we analyzed the effects of murine IGIF on the activation of T cells, and compared the effects with those of IL-12. IGIF alone had no effect on the activation of T cell lines or Th1 clones, while IGIF increased the IFN-gamma production by antigen-stimulated T cell lines, but had no effect on IL-4 or IL-10 production. As reported with IL-12, IGIF served as a costimulatory factor for Th1 clones stimulated with Ag on B cell APC, immobilized anti-CD3, Con A, or IL-2 to augment IFN-gamma production and to induce IL-2R alpha-chain expression and proliferation of the Th1 clones, whereas IGIF had little or no effect on the IL-4 production and proliferation of Th2 clones stimulated with anti-CD3 or Ag. However, IGIF synergized with IL-12 to further augment the IFN-gamma production of the Th1 clones. Even in the presence of saturated amounts of IL-12, IGIF still augmented the IFN-gamma production and proliferation and enhanced the IL-2R alpha-chain expression of the Th1 clones. In contrast with IL-12, IGIF induced IL-2 production by Ag- or anti-CD3-stimulated Th1 clones. These two findings indicate that IGIF and IL-12 are utilizing different signal transduction pathways. We also found that IGIF as well as IL-12 was endogenously released through interaction between Th1 cells and spleen cell APC in the presence of specific Ag, and that it regulated IFN-gamma production. These results further suggest that IGIF may act as an immunoregulatory factor in the immune response.

Animals↗
PubMed1997

Morphological changes and hypomethylation of DNA in transgenic tobacco expressing antisense RNA of the S-adenosyl-L-homocysteine hydrolase gene.

S-adenosyl-L-homocysteine hydrolase (SAHH) is a key enzyme in the regulation of intracellular methylation reactions. To investigate the role of SAHH in methylation reactions and morphogenesis in planta, we have made transgenic plants expressing antisense RNA of tobacco SAHH. The transgenic plants displayed distinct morphological changes including a floral homeotic change. We hypothesized that the changes were caused by increased levels of cytokinin. In those transgenic plants, we observed that a repetitive DNA sequence appeared less methylated than controls. We speculated that altered gene expressions by the hypomethylation of DNA might be involved in the changes.

Adenosylhomocysteinase↗
PubMed1996

Reliability of inferred age, and coincidence between inferred age and chronological age.

Outdoor research is restricted by many factors. The age inference was one of the biggest problems for the outdoor researchers. We have investigated the reliability of inferred age for the Japanese people, and took out the estimation formula for the age, even if it was based on the inferred age. The age classification was the most popular method for this purpose, and there were many classifications. We took the classification of young, middle aged, and elderly groups, in which classification of the SDs were rather small, that is, 4, 5, and 7 years for the young, middle aged, and elderly age groups, respectively.

Adult↗
PubMed1995

Prolidase from Xanthomonas maltophilia: purification and characterization of the enzyme.

Prolidase (iminodipeptidase, EC 3.4.13.9) was purified from an extract of Xanthomonas maltophilia, by ammonium sulfate fractionation and sequential chromatographies on DEAE-Toyopearl, Toyopearl HW65C, FPLC-Hiload Superdex 200 pg, and FPLC-Hitrap Q columns, which an activity recovery of 2.3%. The enzyme was the most active at pH 7.5 with Leu-Pro as substrate. It was stable between pH 6.0 and 8.5 for 60 min at 37 degrees C and retained half of activity after 60 min at 37 degrees C. The isoelectric point of the enzyme was 3.7. Its molecular weight was estimated to be 100,000 by gel filtration on FPLC-Hiload Superdex 200 and 51,000 by SDS-PAGE, suggesting that it is a dimer. It hydrolyzed dipeptides only if proline is located at the carboxyl terminal position. The enzyme was inhibited by PCMB and o-phenanthroline, and was activated by Mn2+.

Chromatography, Ion Exchange↗
PubMed1994

X-ray structure of a pokeweed antiviral protein, coded by a new genomic clone, at 0.23 nm resolution. A model structure provides a suitable electrostatic field for substrate binding.

We have determined the crystal structure of alpha-pokeweed antiviral protein, a member of ribosome-inactivating proteins, at 0.23 nm resolution, by the molecular-replacement method. The crystals belong to the space group P2(1)2(1)2 with unit-cell dimensions a = 4.71, b = 11.63 and c = 4.96 nm, and contain one protein molecule/asymmetric unit based on a crystal volume/unit protein molecular mass of 2.1 x 10(-3) nm3/Da. The crystallographic residual value was reduced to 17.2% (0.6-0.23 nm resolution) with root-mean-square deviations in bond lengths of 1.9 pm and bond angles of 2.2 degrees. The C alpha-C alpha distance map shows that alpha-pokeweed antiviral protein is composed of three modules, the N-terminal (Ala1-Leu76), the central (Tyr77-Lys185) and the C-terminal (Tyr186-Thr266) modules. The substrate-binding site is formed as a cleft between the central and C-terminal modules and all the active residues exist on the central module. The electrostatic potential around the substrate-binding site shows that the central and C-terminal module sides of this cleft have a negatively and a positively charged region, respectively. This charge distribution in the protein seems to provide a suitable interaction with the substrate rRNA.

Amino Acid Sequence↗
PubMed1994

Improved crystals of the toxic protein MAP by protein engineering towards the host specificity.

Mirabilis anti-viral protein (MAP) is a ribosome-inactivating protein from Mirabilis jalapa L. Since MAP is effective over a broad spectrum of species, the protein is difficult to express in heterologous hosts such as Escherichia coli. Recently, we obtained a MAP mutant, Y72F which exhibits a lower (1/100) activity against E. coli ribosomes while retaining almost full activity against mammalian cells [Habuka, Miyano, Kataoka, Tsuge & Noma (1992). J. Biol. Chem. 267, 7758-7760]. For the crystallographic studies, the Y72F MAP expression vector with an OmpA leading sequence was constructed and expressed in E. coli. The Y72F MAP mutant was then isolated and purified from the cell culture medium. Crystals were grown using the crystallization conditions for the native MAP crystals [Miyano et al. (1992). J. Mol. Biol. 226, 281-283]: 50% ammonium sulfate containing 50 mM ammonium citrate and 2 mM adenine sulfate, pH 5.4. The crystals belong to space group P3(1)21 (or P3(2)21) with a = b = 104.1 and c = 134.3 A. The crystals are isomorphous with the wild-type crystals but diffract to higher resolution. Imaging-plate photographs of the Y72F mutant showed sharp intense spots without the streaking observed in the native crystals.

Journal Article↗
PubMed1994

Observation study on natural walking in the Tokyo metropolitan.

In this study, data on walking speed, step numbers, cadence of natural walking were collected and their relations to foot wear, clothing, luggage carried and time of the day as well as crowdedness were investigated. This survey was held in Shinjuku, Tokyo in 1991. Six thousand three hundred and seventy nine walking people were observed from 10:00 am to 5:00 pm. Ten students who were trained to observe the walking were employed for the data collection. The observed subjects were divided into three age groups, namely young (less than 30 years), middle (31-60 years) and elder (over 61 years), and their age groups were decided by the students based on their appearance. For the analysis, they were further classified into male and female groups. The factors which affect walking speed, step number and cadence were taken into consideration. It was found that young people were more sensitive to their factors in their natural walking and old people showed lower flexibility to these factors.

Adult↗
PubMed1993

Expression of a pokeweed antiviral protein in Escherichia coli and its characterization.

Two expression vectors were constructed to produce a putative mature alpha-pokeweed antiviral protein (alpha-PAP) in Escherichia coli with its NH2- and COOH-terminal extrapeptides excised. One was for its intracellular expression with a methionine at its NH2-terminal. The other was for its secretion using an ompA signal peptide. The former product was purified from the total soluble proteins of the transformant with a yield of 1.74 mg/liter and the latter had a yield of 5.55 mg/liter. Both products exhibited RNA N-glycosidase activity on wheat ribosomes and inhibitory activity to protein synthesis in a rabbit reticulocyte system.

Amino Acid Sequence↗
PubMed1993

Nucleotide sequence of a genomic gene encoding tritin, a ribosome-inactivating protein from Triticum aestivum.

A genomic gene of tritin, a ribosome-inactivating protein (RIP) from Triticum aestivum, was cloned using a barley RIP gene as a probe. The 5'-non-coding region has potential TATA boxes and three sequences homologous to the binding sequence of the transcriptional activator protein Opaque-2 which activates maize RIP gene expression. The cloned DNA encoded tritin consists of 275 amino acids with no secretion signal sequence. The coding region of tritin was expressed in Escherichia coli using lac promoter and yielded a protein similar to the native one, as determined by SDS-polyacrylamide gel electrophoresis and immunological analysis.

Amino Acid Sequence↗
PubMed1993

Effect of heparin on hemagglutination by pseudorabies virus.

Heparin inhibited hemagglutination (HA) by pseudorabies virus (PRV), but not HA by Akabane virus, bovine adenovirus type 7, Fukuoka virus, Getah virus, Japanese encephalitis virus, and parainfluenza virus type 3 belonging to the families Bunyaviridae, Adenoviridae, Rhabdoviridae, Togaviridae, Flavivi-idae, and Paramyxoviridae, respectively. The minimal inhibitory concentration of heparin required to inhibit 8 HA U of PRV ranged from 0.005 to 0.01 U/ml. Mouse erythrocytes failed to combine with the HA inhibitory factor of heparin. On the other hand, mouse erythrocytes treated with heparinase had greatly reduced agglutinability by PRV. Virus-heparin complex formation could be observed by sedimenting heparin with the virus particles.

Animals↗
PubMed1992

Crystallization and preliminary X-ray crystallographic analysis of Mirabilis antiviral protein.

Mirabilis antiviral protein is a single-chain ribosome-inactivating protein purified from the tuberous root of Mirabilis jalapa L. We obtained several forms of crystals of the protein by the hanging drop vapor diffusion method, but most of these crystals were not suitable for X-ray crystallography. After refining the growth conditions, crystals of crystallographic quality were grown in 20-microliters droplets of an equi-volume mixture of 1.5% (w/v) protein solution and a reservoir solution containing 49 to 50% (w/v) ammonium sulfate and 50 mM-ammonium citrate (pH 5.4) at room temperature. Addition of 2 mM-adenine sulfate reduced twinning and "crystal shower". The resulting trigonal crystals diffract beyond 2.5 A resolution using a rotating anode X-ray generator. The space group was determined to be P3(1)21 or P3(2)21 (a = b = 103.9.A, c = 134.6 A, alpha = beta = 90 degrees, gamma = 120 degrees) based on their precession photography of h0l and hk0 zones. There seems to be three monomers in an asymmetric unit for VM = 2.51 A3/Da.

Antiviral Agents↗
PubMed1992

Specificities of RNA N-glycosidase activity of Mirabilis antiviral protein variants.

Mirabilis antiviral protein (MAP), a ribosome-inactivating protein, inactivates both eukaryotic and prokaryotic ribosomes by means of site-specific RNA N-glycosidase activity. In order to identify the site of this activity, some amino acid residues of MAP, conserved in homologous ribosome-inactivating proteins, were altered to other amino acids by replacing DNA fragments of the total synthetic gene of MAP. When the in vitro proteins synthesis of rabbit reticulocyte was treated with MAP variants secreted into culture media of Escherichia coli transformants, the inhibitory effect of R26L and R48L (R26L designates MAP variant with Arg-26 changed to Leu) was found to be similar to that of native MAP. Both purified Y72F and Y118F had the same effect as native MAP, and E168D had a slightly weaker effect. In contrast, on the protein synthesis of E. coli, Y118F had one-tenth the effect of native MAP, and Y72F and E168D approximately one-hundredth the effect. These three variant proteins also exhibited reduced RNA N-glycosidase activity on substrate E. coli ribosomes. These results suggest that Tyr-72 and Glu-168 are involved in RNA N-glycosidase activity. When the R171K gene was expressed in E. coli, an N-glycosidic bond of the 23 S rRNA of the host ribosome was found to be cleaved, although no product of the gene could be detected. This suggests that MAP variants can maintain their N-glycosidase activity when the conserved Glu-168 and Arg-171 are changed to similarly charged residues.

Amino Acid Sequence↗
PubMed1992

Isolation and analysis of a genomic clone encoding a pokeweed antiviral protein.

Partial cDNAs encoding a pokeweed antiviral protein were obtained by polymerase chain reaction from the poly(A)+ RNA of seeds, leaves, and roots using two specific primers based on the amino acid sequence of a pokeweed antiviral protein from the seeds (PAP-S). Using the cDNAs as a radioactive probe, 17 and 39 positive plaques were isolated from libraries containing the genomic DNA of Phytolacca americana digested with Bam HI partially and completely, respectively. The plaques were grouped into nine types by Southern hybridization. The type alpha genomic clone encodes a protein of 294 amino acids. Its amino acid sequence is similar but not identical to that of PAP-S. A comparison of the two amino acid sequences suggested that the deduced protein contains extrapeptides of 24 and 9 amino acids at the NH2 and the COOH terminals, respectively. The putative protein was expressed in Escherichia coli and shown to depurinate the specific adenine of wheat 25S rRNA, indicating that the protein encoded by a type alpha genomic clone is a functional protein exhibiting RNA N-glycosidase activity.

Amino Acid Sequence↗