PubMed Health⌕ Search

Biomedical subjects

N Uehara

Publications and source records attributed to N Uehara.

At least 19 recordsLinked to original sources
PubMed2006

Human beta-defensin-3 induction in H. pylori-infected gastric mucosal tissues.

AIM: To examine human beta-defensin-3 (hBD-3) expression in inflamed gastric mucosal tissues or MKN45 gastric cancer cells with or without H. pylori infection for better understanding the innate immune response to H. pylori. METHODS: We used reverse transcription-polymerase chain reactions and immunohistochemistry to examine hBD-3 expression in inflamed gastric mucosal tissues or MKN45 gastric cancer cells with or without H. pylori. Effects of hBD-3 against H. pylori were also evaluated. RESULTS: The mean mRNA expression of hBD-3 in H. pylori-positive specimens was significantly higher than that in H pylori-negative specimens (P = 0.0002, Mann-Whitney). In addition, unlike uninfected samples, 8 of 15 (53.33%) infected mucosal samples expressed hBD-3 protein. H. pylori dose-dependently induced mRNA expression of hBD-3 in MKN45 cells, an effect inhibited by adding anti-toll-like receptor (TLR)-4 antibody. HBD-3 protein completely inhibited H. pylori growth. CONCLUSION: Our results suggest that like hBD-2, hBD-3 may be involved in the pathophysiology of H. pylori-induced gastritis.

Antibodies, Anti-Idiotypic↗
PubMed2004

Existence of a threshold for induction of aberrant crypt foci in the rat colon with low doses of 2-amino-1-methyl-6-phenolimidazo[4,5-b]pyridine.

Until recently it has been generally considered that genotoxic carcinogens have no threshold in exerting their potential for cancer induction. However, the nonthreshold theory can be challenged with regard to assessment of cancer risk to humans. In the present study we show that a food derived, genotoxic hepatocarcinogen, 2-amino-1-methyl-6-phenolimidazo[4,5-b]pyridine (PhIP), does not induce aberrant crypt foci (ACF) as preneoplastic lesions at low dose (below 50 ppm) or 8-hydroxy-2'-deoxyguanosine (below 400 ppm) in the rat colon. Moreover PhIP-DNA adducts were not formed at the lowest dose (below 0.01 ppm). Thus, the dose required to initiate ACF is approximately 5000 times higher than that needed for adduct formation. The results imply a no-observed effect level (existence of a threshold) for colon carcinogenesis by a genotoxic carcinogen.

8-Hydroxy-2'-Deoxyguanosine↗
PubMed2003

Human beta-defensin-2 induction in Helicobacter pylori-infected gastric mucosal tissues: antimicrobial effect of overexpression.

The objective of this study was to understand more of the innate immune response to Helicobacter pylori by determining the expression of human beta-defensin-2 (hBD-2) in various gastric mucosal tissues and MKN45 gastric cancer cells with or without H. pylori. Semi-quantitative TaqMan RT-PCR and immunohistochemistry were carried out. The antimicrobial effects of a transfected hBD-2 gene against H. pylori were also evaluated. The results showed that hBD-2 was expressed in inflamed gastric mucosal tissues with H. pylori infection, but not in the absence of H. pylori infection. Expression was also detected in gastric cancers in patients with H. pylori infection. Expression was induced in the MKN45 gastric cancer cell line by H. pylori in a manner dependent on the abundance of bacteria. hBD-2-transfected 3T3J2-1 cells secreted hBD-2 protein into the culture medium and this protein inhibited growth of H. pylori completely. The results suggest that hBD-2 may be involved in the pathophysiology of H. pylori-induced gastritis.

Adult↗
PubMed2002

Pyrazinamide resistance associated with pncA gene mutation in Mycobacterium tuberculosis in Japan.

Thirty Japanese clinical isolates of Mycobacterium tuberculosis were analysed by pyrazinamide susceptibility testing and pyrazinamidase assay, as well as polymerase chain reaction for single-strand conformational polymorphism and direct sequencing of the gene encoding pyrazinamidase (pncA). All sensitive isolates showed pyrazinamidase activity and a wild-type pncA gene, but three resistant isolates had pncA gene mutations and lacked pyrazinamidase activity. The latter isolates showed a minimum inhibitory concentration of at least 100 mg/l by the 7H10 agar proportion method and 400 mg/l by the 7H9 liquid medium method. Isolate 28 showed T-to-C change at position 11, leading to Leu4 --> Ser substitution; isolate 29 had an 8-bp deletion from position 382; and isolate 30 had A-to-C change at position 29, leading to Gln10 --> Pro substitution. The deletion has not been described previously. This is the first demonstration of pncA gene mutations in PZA-resistant M. tuberculosis strains isolated from Japanese patients.

Amidohydrolases↗
PubMed2002

Comparison of arbitrarily primed-polymerase chain reaction and pulse-field gel electrophoresis for characterizing methicillin-resistant Staphylococcus aureus.

AIMS: The aim of this study was to analyse genotypes for clinical isolates of methicillin-resistant Staphylococcus aureus (MRSA), including hetero-vancomycin-resistant Staph. aureus (VRSA), at a Japanese university hospital. METHODS AND RESULTS: Seventy-eight clinical isolates of MRSA were analysed by arbitrarily primed-polymerase chain reaction (AP-PCR) using ERIC2 primer and by pulse-field gel electrophoresis (PFGE) following SmaI digestion. Analyses of the nine genotypes and 28 subtypes defined by PFGE, and of the three genotypes and 22 subtypes defined by AP-PCR, both facilitated epidemiological tracing. Used in combination, AP-PCR and PFGE provided more precise classification than the use of a single genotyping method. The six hetero-VRSA isolates were classified into four genotypes defined by the combination of both methods, but these genotypes contained non-VRSA isolates. CONCLUSIONS: The results suggest that both PFGE and AP-PCR are useful in discriminating MRSA, but not hetero-VRSA, isolates for epidemiological analysis. SIGNIFICANCE AND IMPACT OF THE STUDY: Combining the results of PFGE with the results of AP-PCR can provide more detail differentiation of MRSA and hetero-MRSA isolates than either method alone.

DNA, Bacterial↗
PubMed2001

Distribution of aminoglycoside resistance genes in recent clinical isolates of Enterococcus faecalis, Enterococcus faecium and Enterococcus avium.

Aminoglycoside modifying enzymes (AMEs) are major factors which confer aminoglycoside resistance on bacteria. Distribution of genes encoding seven AMEs was investigated by multiplex PCR for 279 recent clinical isolates of enterococci derived from a university hospital in Japan. The aac(6')-aph(2"), which is related to high level gentamicin resistance, was detected at higher frequency in Enterococcus faecalis (42.5%) than in Enterococcus faecium (4.3%). Almost half of E. faecalis and E. faecium isolates possessed ant(6)-Ia and aph(3')-IIIa. The profile of AME gene(s) detected most frequently in individual strains of E. faecalis was aac(6')aph(2") + ant(6)-Ia + aph(3')-IIIa, and isolates with this profile showed high level resistance to both gentamicin and streptomycin. In contrast, AME gene profiles of aac(6')-Ii+ ant(6)-Ia+aph(3')-IIIa, followed by aac(6')-Ii alone, were predominant in E. faecium. Only one AME gene profile of ant(6)-Ia+aph(3')-IIIa was found in Enterococcus avium. The ant(4')-Ia and ant(9)-Ia, which have been known to be distributed mostly among Staphylococcus aureus strains, were detected in a few enterococcal strains. An AME gene aph(2")-Ic was not detected in any isolates of the three enterococcal species. These findings indicated a variety of distribution profiles of AME genes among enterococci in our study site.

Aminoglycosides↗
PubMed2001

Molecular cloning and functional characterization of two kinds of betaine-aldehyde dehydrogenase in betaine-accumulating mangrove Avicennia marina (Forsk.) Vierh.

Glycinebetaine is an important osmoprotectant in bacteria, plants, and animals, but only little information is available on the synthesis of glycinebetaine in tree plants. Among four mangrove species, glycinebetaine could be detected only in Avicennia marina. Pinitol was the main osmoprotectant in the other three species. The level of glycinebetaine in A. marina increased under high salinity. Betaine-aldehyde dehydrogenase (BADH) was detected in all four species, but choline monooxygenase could not be detected. A cDNA library was constructed from the leaves of A. marina. Two kinds of BADH cDNAs were isolated, one homologous to the spinach chloroplast BADH, and the other with unique residues SKL at the end of C-terminus. The BADH transcription levels of the former were higher than those of the latter. The levels of the former BADH increased at high salinity whereas those of the latter were independent of salinity. BADHs were expressed in Escherichia coli and purified. Two kinds of A. marina BADHs exhibited similar kinetic and stability properties, but were significantly different from those of spinach BADH. A. marina BADHs efficiently catalyzed the oxidation of betainealdehyde, but not the oxidation of omega-aminoaldehydes and were more stable at high temperature than the spinach BADH.

Aldehyde Oxidoreductases↗
PubMed2001

Determination of trace amounts of boron in steel by reversed-phase high-performance liquid chromatography with azomethine-H as a precolumn derivatizaion agent.

The determination of trace amounts of boron in steel by reversed-phase high-performance liquid chromatography (HPLC) is described. As a derivatizing reagent for the HPLC determination of boron, 8-hydroxy-1-(salicylideneamino)-3,6-naphtalenedisulfonic acid (azomethine-H) was used with a spectrophotometric detection. A peak of boron-azomethine-H chelate was resolved from other peaks using an acetonitrile-water (29 + 71 m/m) eluent containing 8 x 10(-3) mol kg(-1) tetrabutylammonium bromide and 5 x 10(-3) mol kg(-1) acetate buffer (pH 5.0). The lower determination limit (10sigma) of boron was 3.3 x 10(-8) mol dm(-3) for a solution injected into HPLC, which is translated to 0.09 microgB/g when 0.1 g of a steel sample was subjected to the analysis. The analytical results of certified steel samples were in good agreement with the guaranteed values. The addition of ethylenediamine-N,N,N',N'-tetraacetate as a masking agent for the iron(III) matrix with the optimized eluent enables one to achieve the direct determination of trace amounts of boron in such steel sample solutions without any tedious matrix removal or preconcentration.

Journal Article↗
PubMed2001

Spectrophotometric characterization of diazacrown ethers having two carbodithioate groups.

Diazacrown ethers having two carbodithioate groups were synthesized, and their spectrophotometric properties were studied. Diammonium 1,4,10,13-tetraoxa-7,16-diazacycrooctadecane-N,N'-bis(carbodithioate) (DA18CC) and ammonium 1,4,10-trioxa-7,13-diazacycropentadecane-N,N'-bis(carbodithioate) (DA15CC) reacted with most heavy-metal ions through their two carbodithioate groups, and also reacted with alkali-metal ions or alkaline earth-metal ions through their diazacrown rings. Although the UV-VIS absorption spectra of DA18CC and DA15CC were hardly influenced by the addition of alkali-metal ions or alkaline earth-metal ions, the spectra of some heavy-metal chelates of DA18CC and DA15CC were influenced. The composition ratio (metal:ligand) of Cu(II) and Pb(II) chelates of DA18CC and DA15CC was altered from 1:1 to 1:2 by the addition of alkali-metal ions or alkaline earth-metal ions. It is suggested that the change in the absorption spectra and the composition ratio of the chelates can be attributed to an alteration of the equilibrium among species of the heavy-metal chelates of DA18CC and DA15CC due to the coordination of alkali-metal ions or alkaline earth-metal ions into the diazacrown ring.

Journal Article↗
PubMed2001

[Nationwide sensitivity surveillance of various antibiotic activities against bacteria isolated from patients with severe infections].

The susceptibility of 3,058 bacterial strains isolated between January and March, 1997 from patients with severe infections in Japan to ciprofloxacin and other injectable antimicrobial agents was measured using broth microdilution method. Methicillin-resistant Staphylococcus aureus (MRSA) strains were generally sensitive to vancomycin, teicoplanin and arbekacin, and resistant to CPFX and other antibacterial agents. MIC90 of CPFX against Streptococcus pneumoniae, to which MIC of ampicillin was more than 4 micrograms/mL, was below 2 micrograms/mL. PRSP (Penicillin resistant S. pneumoniae), which was also resistant to cephalosporins and carbapenems, showed no cross-resistance to CPFX. The susceptibility of Gram-negative bacteria to CPFX was as high as that to carbapenems. Especially, MIC90 against Pseudomonas aeruginosa was 2 micrograms/mL. 3 strains of isolated 446 P. aeruginosa strains had blaIMP gene. CPFX and pazufloxacin demonstrated good susceptibility with 0.25 microgram/mL of MIC to 2 strains of these 3 strains. The susceptibility rate of the most common isolates from patients suffering from lower respiratory tract infections excluding MRSA to CPFX was more than 80% (indication: % strains < pneumonia break point).

Anti-Bacterial Agents↗
PubMed2000

[Changes in the antibacterial activity of chemotherapeutic agents (especially carbapenems) for 10 species of clinical isolates between 1994 and 1996. Surveillance group of the sensitivities of clinical isolates to antibacterial agents].

During October and December of each year of from 1994 to 1996, 3,849 strains of 10 species of bacteria were isolated from clinical materials in 21 institutions nationwide. The minimum inhibitory concentrations (MICs) for these bacteria of four carbapenems (imipenem [IPM], panipenem [PAPM], meropenem [MEPM], and biapenem [BIPM]) and other representative antibacterial agents were measured to investigate annual changes in antibacterial activity. Carbapenems showed potent activity against methicillin-sensitive S. aureus (MSSA), S. pneumoniae, E. faecalis, H. influenzae, E. coli, K. pneumoniae, E. cloacae, S. marcescens, and the B. fragilis group, with the activity being stable. However, these drugs showed weak activity against methicillin-resistant S. aureus (MRSA) and P. aeruginosa. The antibacterial activity (MIC90) against the tested organisms generally remained stable. Particularly, there was annual improvement of the MIC90 values of IPM and BIPM for S. pneumoniae, as well as the values of IPM and PAPM for H. influenzae, and those of IPM, PAPM, and BIPM for S. marcescens. On the other hand, the activity of carbapenems (including IPM) against MRSA was not necessarily strong, but there was annual improvement of MIC90 values.

Bacteria↗
PubMed2000

[Activities of antimicrobial agents against 5,180 clinical isolates obtained from 26 medical institutions during 1998 in Japan. Levofloxacin--Surveillance Group].

The surveillance study was conducted to determine the antimicrobial activity of fluoroquinolones (ofloxacin, levofloxacin, ciprofloxacin, tosufloxacin) and other 20 antimicrobial agents against 5,180 clinical isolates obtained from 26 medical institutions during 1998 in Japan. The resistance to fluoroquinolones was remarkable in Enterococci, methicillin-resistant staphylococci and Pseudomonas aeruginosa from UTI. However, many of the common pathogens such as Streptococcus pneumoniae including penicillin-resistant isolates, methicillin-susceptible Stahylococcus aureus, Moraxella catarrhalis, the family of Enterobacteriaceae, Haemophilus influenzae including ampicillin-resistant isolates have been kept to be susceptible to fluoroquinolones. About 90% of P. aeruginosa isolates from RTI were susceptible to fluoroquinolones. In conclusion, the results from this surveillance study suggest that fluoroquinolones are useful in the treatment of various bacterial infections including respiratory infections.

Anti-Infective Agents↗
PubMed1999

Heterocyclic amine mixture carcinogenesis and its enhancement by caffeine in F344 rats.

In order to elucidate whether mixed exposure to environmental carcinogens and caffeine increases the risk of cancer induction, we investigated the relationship between preneoplastic lesion development in the liver and colon and drug metabolizing enzyme induction and DNA adduct formation, in rats treated with a mixture of heterocyclic amines (HCAs) and caffeine. In Experiment 1, male F344 rats were administered 3 different HCAs, the food carcinogens, 2-amino-3-methylimidazo[4,5-f]quinoline (IQ), 2-amino-3,8-dimethylimidazo[4,5-f]quinoxaline (MeIQx), and 2-amino-1-methyl-6-phenylimidazo[4,5-b]pyridine (PhIP), alone or in combinations of 2 or 3 at 50 ppm in the diet for 16 weeks. The numbers of hepatic glutathione-S-transferase P form positive (GST-P+) foci and colonic aberrant crypt foci (ACF) were greater in the IQ + MeIQx group than expected from simple summation and increased levels of HCA-DNA adducts were noted. However, no summation was obtained when combined with PhIP, which rather caused inhibition. In Experiment 2, the effects of concurrent caffeine administration on the PhIP carcinogenicity were assessed. Caffeine at 1000 and 500 ppm in the drinking water for 2 weeks significantly increased levels of CYP1A2. Ten weeks concurrent administration of caffeine (1000 ppm) and PhIP (400 ppm) resulted in significant increase of colon ACFs and CYP1A2 expression. Thus, concurrent administration of IQ and MeIQx caused elevation of their carcinogenicity but other mixtures with PhIP did not enhance carcinogenicity. However, a non-carcinogen, caffeine, enhanced PhIP colon carcinogenesis, possibly due to induction of CYP1A2.

Animals↗
PubMed1999

Heterozygous p53-deficient mice are not susceptible to 2-amino-3,8-dimethylimidazo[4,5-f]quinoxaline (MeIQx) carcinogenicity.

2-Amino-3,8-dimethylimidazo[4,5-f]quinoxaline (MeIQx) is a very potent mutagen which induces tumors in the liver, lung and hematopoietic system of CDF1 mice and the liver, Zymbal gland and skin in F344 rats. The recent development of transgenic knockout mice allows their introduction for sensitive screening of environmental carcinogens due to the rapid development of tumors. P53 gene deficient mice (p53-/-) were found to spontaneously develop malignant lymphoma and hemangiosarcoma, whereas heterozygotes (p53+/-) mice display a high incidence of tumors of the urinary bladder when treated with N-butyl-N-(4-hydroxybutyl)nitrosamine. In the present study, to determine whether p53 gene knockout mice can be utilized in a short-term assay model for the screening of heterocyclic amines (HCAs), the effects of MeIQx, as a representative compound, at low doses were examined. Male and female p53+/- mice and wild type littermates (p53+/+) were continuously given diets containing 0, 0.1, 1, 10 and 100 ppm MeIQx for 1 year. No significant difference in tumor induction was observed other than an increase in liver adenomas in males receiving 10 ppm MeIQx treatment. The results indicate that p53+/- mice have no practical advantages for use in short-term carcinogenicity tests of HCAs.

Alleles↗
PubMed1999

Three point mutations of human butyrylcholinesterase in a Japanese family and the alterations of three-dimensional structure.

Three different mutations at codons 330 (TTA to ATA), 365 (GGA to AGA) and 515 (CGT to TGT) of human butyrylcholinesterase (hBChE) were identified in a Japanese family. We correlated alterations in in the patient's hBChE activity with possible structural alterations in the three-dimensional structure of hBChE caused by the point mutations. This study was performed using the published computer-generated three-dimensional structure of hBChE based on the structure of acetylcholinesterase. The amino acid substitution at L330I was adjacent to hydrophobic residues that form the channel domain of the active center. This side chain faced the side opposite the active center. The amino acid substitution at G365R was located at the position most remote from the active center, and this substitution site was exposed to the surface of the BChE protein. Alpha-helical structure was present to the active center, and the guanidyl residue of native Arg 515 was hydrogen-bonded to the carboxyl group of Asp 395 in the alpha-helix. These point mutations may cause steric effects on the present patient's hBChE activity. This is the first report of three-dimensional structural analysis performed on the L330I, G365R, and R515C mutations of hBChE.

Adult↗
PubMed1999

Analysis of genomic diversity within the Xr-region of the protein A gene in clinical isolates of Staphylococcus aureus.

Protein A of Staphylococcus aureus contains a polymorphic Xr-region characterized by a tandem repeat of eight amino acid units. In this study, the diversity of genes encoding the repeat regions and their relatedness among S. aureus strains was analyzed. Ten different protein-A types characterized by repeat numbers 4-13 were identified in a total of 293 clinical isolates. The protein-A type with 10 repeat units (10 repeats) in the Xr-region was most frequently detected in methicillin-resistant S. aureus, whereas the majority of methicillin-susceptible strains were distributed almost evenly into protein-A types with 7-11 repeats. Strains that belonged to a single coagulase type were classified into multiple protein-A types, e.g. strains with the common coagulase types II and VII were differentiated into 7 and 8 protein-A types, respectively. Nucleotide sequence analysis of the Xr-region of 42 representative strains revealed the presence of 37 different genotypes (spa types), which were constituted by a combination of several of 24 different repeat unit genotypes. Based on the similarity in arrangement of repeat unit genotypes, 34 strains with different repeat numbers were classified into 5 genetic clusters (C1-C5). The clusters C1, C2 and C3 consisted exclusively of strains with identical coagulase types II, III, and IV, respectively. These findings suggested that the protein-A gene of S. aureus has evolved from a common ancestral clone in individual clusters independently.

Amino Acid Sequence↗
PubMed1999

Distribution of insertion sequence-like element IS1272 and its position relative to methicillin resistance genes in clinically important Staphylococci.

The distribution of insertion sequence-like element IS1272 was analyzed for clinical isolates of Staphylococcus aureus, Staphylococcus epidermidis, and Staphylococcus haemolyticus. In each of the staphylococcal species, IS1272 was detected in both methicillin-resistant (MR) and methicillin-susceptible strains of different genetic types. In MR isolates, IS1272 was generally located downstream of the truncated mecR1 gene (DeltamecR1), with an identical junction sequence occurring between DeltamecR1 and IS1272, although insertion of an additional gene sequence in the junction sequence was detected in one S. epidermidis isolate. These findings suggest that the mec element with the rearranged form of mecR1 (DeltamecR1-IS1272) has been transmitted to multiple clones of staphylococci.

Bacterial Proteins↗