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Toshinobu Horii

Publications and source records attributed to Toshinobu Horii.

At least 19 recordsLinked to original sources
PubMed2007

Molecular characterization of 8-methoxyfluoroquinolone resistance in a clinical isolate of methicillin-resistant Staphylococcus aureus.

BACKGROUND: Activity of gatifloxacin against clinical isolates of fluoroquinolone-resistant Staphylococcus aureus is more potent than that of other fluoroquinolones such as norfloxacin and levofloxacin. To date, few reports have described high-level resistance to gatifloxacin in clinical isolates of S. aureus, although in vitro studies have shown that mutations in both DNA gyrase and topoisomerase IV were required for gatifloxacin resistance in S. aureus. METHODS: Minimum inhibitory concentrations were determined for fluoroquinolones and other antimicrobials in a methicillin-resistant S. aureus isolate that was cultured from blood of a patient with septicemia. Fluoroquinolone resistance was characterized by DNA sequencing and microbiologic assay. RESULTS: The isolate showed high-level resistance to fluoroquinolones including an 8-methoxyfluoroquinolone, gatifloxacin (minimum inhibitory concentration 64 microg/ml). Amino acid mutations of Ser80Tyr and Glu84Lys in GrlA and Ser84Leu and Ser85Pro in GyrA were possibly related to this resistance in methicillin-resistant S. aureus HU2000-062, although efflux may play a minor role in resistance as well. CONCLUSION: GyrA and GrlA mutations mainly conferred to 8-methoxyfluoroquinolone resistance in this isolate.

Aged↗
PubMed2006

Acute peritonitis and salpingitis associated with streptococcal toxic shock syndrome caused by Lancefield group G alpha-haemolytic Streptococcus dysgalactiae subsp. equisimilis.

The authors treated a patient for what appears to be the first reported occurrence of acute peritonitis and salpingitis associated with streptococcal toxic shock syndrome (STSS). This was caused by Lancefield group G alpha-haemolytic Streptococcus dysgalactiae subsp. equisimilis TKCH2004-001. The isolate showed M protein type stc36 and carried the spegg gene. To the best of the authors' knowledge, the present report represents the first case of STSS complicating acute peritonitis and salpingitis caused by Lancefield group G alpha-haemolytic S. dysgalactiae subsp. equisimilis.

Acute Disease↗
PubMed2005

Rapid detection of fluoroquinolone resistance by isothermal chimeric primer-initiated amplification of nucleic acids from clinical isolates of Neisseria gonorrhoeae.

To ensure a complete response to fluoroquinolone therapy against Neisseria gonorrhoeae infections, rapid susceptibility determinations are required. We assessed a new approach, an isothermal chimeric primer-initiated amplification of nucleic acids (ICAN)/hybrid-chromatography method to detect rapidly fluoroquinolone resistance in N. gonorrhoeae. Comparison of the amplification results with fluoroquinolone minimum inhibitory concentrations (MICs), which were determined by an agar dilution method, showed that the new method accurately determined fluoroquinolone resistance in all ciprofloxacin- and/or gatifloxacin-resistant isolates, but agreed with results based on MICs in only 6 of 8 (75.0%) ciprofloxacin-susceptible and 7 of 12 (58.3%) gatifloxacin-susceptible isolates. Our results suggest that this method can rapidly and reliably detect point mutations in the gyrA gene as well as fluoroquinolone resistance in resistant isolates of N. gonorrhoeae.

Anti-Infective Agents↗
PubMed2005

Effects of mupirocin at subinhibitory concentrations on biofilm formation in Pseudomonas aeruginosa.

BACKGROUND: Subinhibitory concentrations of mupirocin can suppress flagellar formation in Pseudomonas aeruginosa. In this study, we evaluated the effect of mupirocin on biofilm formation in P. aeruginosa. METHODS: P. aeruginosa PAO-1 (MIC, >1,024 microg/ml for mupirocin) was used. Viable bacteria adhering or forming biofilm on a Cell Desk were counted and observed by scanning electron microscopy. RESULTS: With or without continuous exposure to 256 microg/ml of mupirocin, counts of adherent and/or biofilm-forming bacteria showed no difference until day 10. Whereas biofilm formation with glycocalyx was observed on day 6-10 without mupirocin, mupirocin reduced biofilm formation and glycocalyx production for 10 days. CONCLUSIONS: Subinhibitory concentrations of mupirocin can reduce biofilm formation in vitro in P. aeruginosa.

Anti-Bacterial Agents↗
PubMed2005

Release of exotoxin A, peptidoglycan and endotoxin after exposure of clinical Pseudomonas aeruginosa isolates to carbapenems in vitro.

BACKGROUND: Production of several cell-associated components and extracellular enzymes can play important roles in the pathogenesis of Pseudomonas aeruginosa infections. METHODS: We characterized the time course of morphological changes, production of exotoxin A (ETA) and release of peptidoglycan (PG) and endotoxin (ET) in clinical P. aeruginosa isolates after exposure to carbapenems including imipenem, panipenem, meropenem and biapenem at 0.5, 2, 8 and 32 microg/ml. RESULTS: The amount of ETA in the supernatant of bacterial cultures exposed to carbapenems correlated with the number of viable cells, independently of morphological changes. Formation of ovoid cells and rapid cell lysis induced by carbapenems above the minimal inhibitory concentrations (MICs) decreased ETA production and ET release, while filamentation and prolonged cell lysis increased ETA production and/or ET release. Neither the number of viable cells nor bacterial morphology was related to the amount of PG released throughout the 6-hour observation period. CONCLUSION: Exposure to concentrations of carbapenems above the MIC resulted in rapid cell lysis of P. aeruginosa and decreased ETA levels and ET release, while filamentation and prolonged cell lysis induced by exposure to sub-MICs of carbapenems were associated with increased ETA production and/or greater ET release.

ADP Ribose Transferases↗
PubMed2005

Mechanisms of resistance to fluoroquinolones and carbapenems in Pseudomonas putida.

OBJECTIVES: Pseudomonas putida is an uncommon opportunistic pathogen, usually susceptible to antimicrobial agents. Data concerning resistance to antimicrobial agents in clinical P. putida isolates are limited. PATIENTS AND METHODS: Susceptibilities to fluoroquinolones, carbapenems and other antibiotics were characterized in five clinical isolates of P. putida recovered from different patients with urinary tract infections as causative pathogens. Fluoroquinolone and carbapenem resistance were characterized genetically by the methods of PCR and DNA sequencing. Outer membrane protein (OMP) profiles were characterized by SDS-PAGE. RESULTS: Four of five isolates were resistant or intermediate to both fluoroquinolones and carbapenems. Nucleotide sequences in the quinolone resistance-determining regions suggested that amino acid mutations such as Thr-83-->Ile in GyrA and Glu-469-->Asp in GyrB may contribute to high resistance to fluoroquinolones. Four metallo-beta-lactamase-producing isolates that showed resistance to carbapenems carried the IMP-type metallo-beta-lactamase genes. A combined effect of reduced production of 46 kDa OMP and metallo-beta-lactamase production was shown by a P. putida isolate exhibiting the highest MICs of carbapenems. CONCLUSIONS: This study identified mechanisms of resistance to fluoroquinolones and carbapenems in clinical P. putida isolates.

Amino Acid Substitution↗
PubMed2005

Characterization of fluoroquinolone and carbapenem susceptibilities in clinical isolates of levofloxacin-resistant Pseudomonas aeruginosa.

BACKGROUND: Pseudomonas aeruginosa can rapidly acquire resistance to antibiotics, including fluoroquinolones and carbapenems. METHODS: We characterized fluoroquinolone, carbapenem and other beta-lactam susceptibilities and analyzed fluoroquinolone and carbapenem resistance in 16 clinical isolates of levofloxacin-resistant P. aeruginosa. RESULTS: All levofloxacin-resistant isolates showed high MICs (> or =32 microg/ml) for fluoroquinolones including norfloxacin, levofloxacin, sparfloxacin, gatifloxacin and pazufloxacin, whereas the MICs for sitafloxacin were between 2 and 16 microg/ml. These isolates had both a Thr83Ile mutation in GyrA and a Ser87Leu mutation in ParC. An additional mutation, Glu469Asp in GyrB, was detected in 3 isolates. Three of 16 isolates found during antibiotic therapy showed resistance to carbapenems (MIC, 16-32 microg/ml) because of a reduced production of OprD. Fluoroquinolones, beta-lactams and sulfamethoxazole-trimethoprim were used for 3 months before the isolation of levofloxacin-resistant P.aeruginosa. CONCLUSIONS: Emergence of resistant isolates to both fluoroquinolones and carbapenems during antibiotic therapy is a serious clinical problem. Our results suggest that susceptibilities to fluoroquinolones as well as carbapenems should be monitored during a prolonged course of antibiotic therapy against P. aeruginosa infection.

Anti-Bacterial Agents↗
PubMed2005

Pilot study of arbitrarily primed PCR-single stranded DNA conformation polymorphism analysis for screening genetic polymorphisms related to specific phenotypes.

BACKGROUND: To investigate relationships between phenotypes and genotypes is not simple. We propose a phenotype-to-genotype screening strategy and pooled DNA system. As a pilot study of this strategy, we used arbitrarily primed polymerase chain reaction (AP-PCR) in combination with single-stranded DNA conformation polymorphism (SSCP) to screen for genetic polymorphisms associated with longevity. METHODS: Study subjects were separated into 3 age groups, individuals aged >100 years, 90-99 years and 60-69 years. Genomic DNAs were prepared from each individual, pooled to represent the 5 study groups, and then the pooled genomic DNAs were subjected to AP-PCR-SSCP analysis. RESULTS: We found 1 SNP more frequently in senior citizens with longevity. The genotype frequency of the 82133G>A polymorphism of human chromosome 3 clone RP11-61K12 (AC011199) differed significantly (P=0.0189, Fisher's exact test) between older subjects (>90 years) and younger subjects (<70 years). It is noteworthy that the strategy we describe herein was useful for identifying an SNP that showed statistically significant differences in its distribution across the subject groups. CONCLUSIONS: The pooled DNA strategy and quantitative genotype discrimination can also be applied to screening for the relationship between phenotype and genotype more effectively.

Adult↗
PubMed2005

Close correlation of streptococcal DNase B (sdaB) alleles with emm genotypes in Streptococcus pyogenes.

DNase B is a major nuclease and a possible virulence factor in Streptococcus pyogenes. The allelic diversity of streptococcal DNase B (sdaB) gene was investigated in 83 strains with 14 emm genotypes. Of the 15 alleles identified, 11 alleles carried only synonymous nucleotide substitutions. On the other hand, 4 alleles had a non-synonymous substitution other than synonymous substitutions, resulting in the substitution of a single amino acid. The distribution of each allele was generally emm genotype-specific. Only sdaB7 was found in both emm2 and emm4. The promoter region was highly conserved and DNase B protein was similarly expressed in all alleles.

Alleles↗
PubMed2005

Use of a three-dimensional microarray system for detection of levofloxacin resistance and the mec A gene in Staphylococcus aureus.

We evaluated a novel three-dimensional microarray (Pam Chip microarray) system to detect the presence of levofloxacin-related resistance mutations and the mec A gene. The results were compared to those obtained for 27 Staphylococcus aureus isolates by conventional DNA sequencing or PCR methods. Hybridization and fluorescence detection were performed using an FD 10 system designed for Pam Chip microarray under conditions optimized for each target/probe on the array. In dilution series analysis using multiplex PCR samples, the sensitivity of the microarray was about 10 times greater than that of conventional PCR methods. A high level of data reproducibility was also confirmed in those analyses. Various point mutations in quinolone resistance-determining regions detected by our system corresponded perfectly to the results obtained by conventional DNA sequencing. The results of the mec A gene detection using our system also corresponded to the PCR method; that is, signal/band was detected in all isolates of methicillin-resistant S. aureus, and no signal/band was detected in any isolate of methicillin-susceptible S. aureus. In conclusion, our novel three-dimensional microarray system provided rapid, specific, easy, and reproducible results for the simultaneous detection of levofloxacin resistance and the mec A gene in S. aureus.

Anti-Bacterial Agents↗
PubMed2005

Two patients with all-trans retinoic acid-resistant acute promyelocytic leukemia treated successfully with gemtuzumab ozogamicin as a single agent.

Acute promyelocytic leukemia (APL) cells express a considerable level of CD33, which is the target of gemtuzumab ozogamicin (GO), and a significantly lower level of P-glycoprotein (P-gp). Therefore, GO is predicted to be a successful treatment for APL. In this article, we report on the GO treatment of 2 patients with APL, who had fully relapsed after induction therapy with all-trans retinoic acid (ATRA) following chemotherapy. Both patients had relapsed 3 times and were resistant to reinduction therapy with ATRA. GO (9 mg/m2) was administered on days 1 and 15. After GO treatment, both patients achieved complete hematologic and molecular remission. GO may be another promising agent for the treatment of ATRA-resistant relapsed APL when given as salvage chemotherapy.

ATP Binding Cassette Transporter, Subfamily B, Mem↗
PubMed2005

[In vitro susceptibilites to levofloxacin and various antibacterial agents of 11,475 clinical isolates obtained from 52 centers in 2002].

The susceptibilities of bacteria to fluoroquinolones (FQs), especially levofloxacin, and other antimicrobial agents were investigated using 11,475 clinical isolates collected in Japan during 2002. Methicillin susceptible staphylococci, Streptococcus pyogenes, Streptococcus pneumoniae, Moraxella catarrhalis, the family of Enterobactericeae, Haemophilus influenzae and Acinetobacter spp. exhibited stable and high susceptibilities to FQs. The rate of FQs-resistant MRSA was 80 approximately 90%, being markedly higher than that of FQs-resistant MSSA. The FQs-resistance rate of MRCNS was also higher than that of MSCNS, however, it was lower than that of MRSA. No FQs-resistant clinical isolates of Salmonella spp. were detected in any of the surveys. Thirteen of Escherichai coli 696 isolates, 8 of Klebsiella pneumoniae 630 isolates and 33 of Proteus mirabilis 373 isolates produced extended-spectrum beta-lactamase (ESBL), furthermore 6 of 13 in E. coli, 1 of 8 in K. pneumoniae and 14 of 31 ESBL-producing isolates, and in P. mirabilis were FQs resistant. Attention should be focused in the future on the emergence of ESBL in relation to FQs resistance. The rate of FQs-resistant P. aeruginosa isolated from urinary tract infection (UTI) was 40 approximately 60%, while 15 approximately 25% of isolates from respiratory tract infection (RTI) were resistant. IMP-1 type metallo beta-lactamase producing organisms were found in 49 of P. aeruginosa 1,095 isolates, 7 of S. marcescens 586 isolates and 4 of Acinetobacter spp. 474 isolates, respectively. Glycopeptide-resistant enterococci or S. aureus was not found.

Anti-Bacterial Agents↗
PubMed2005

[Nationwide surveillance of parenteral antibiotics containing meropenem activities against clinically isolated strains in 2004].

The antibacterial activity of meropenem (MEPM) and other parenteral antibiotics against clinical isolates of 907 strains of Gram-positive bacteria, 1790 strains of Gram-negative bacteria, and 192 strains of anaerobic bacteria obtained from 30 medical institutions during 2004 was measured. The results were as follows; 1. MIC90 of MEPM for almost all of enterobacteriaceae and Haemophilus influenzae were 4-fold to 32-fold lower than those of other carbapenems. MEPM was more active than other carbapenem antibiotics against Gram-negative bacteria, especially against enterobacteriaceae and H. influenzae. MEPM were active against most of the species tested in Gram-positive and anaerobic bacteria, except for multi-drug resistant strains including methicillin-resistant Staphylococcus aureus. 2. As for Pseudomonas aeruginosa, imipenem (IPM) showed high cross-resistant rate againt meropenem-resistant P. aeruginosa (87.9%). MEPM showed low cross-resistant rate both againt IPM-resistant P. aeruginosa (49.2%) and ciprofloxacin-resistant P. aeruginosa (38.0%). 3. The proportion of extended-spectrum beta-lactamase (ESBL) strains was 3.1% (4 strains) in Escherichia coli, 8.0% (2 strains) in Citrobacter koseri, 2.5% (3 strains) in Klebsiella pneumoniae, 2.5% (2 strains) in Enterobacter cloacae, 0.9% (1 strains) in Serratia marcescens, and 2.2% (2 strains) in Proteus mirabilis. The proportion of metallo-beta-lactamase strains was 1.6% (5 strains) in P. aeruginosa. 4. Of all species tested, Peptostreptococcus spp. was the only species, which MIC90 of MEPM was more than 4-fold higher than that in our previous study using clinical isolates during 2002 (0.25 microg/ml --> 1 microg/ml). Therefore, there is almost no siginificant decrease in susceptibility of clinical isolates to meropenem. In conclusion, the results from this surveillance study suggest that MEPM retains its potent and broad antibacterial activity and therefore is a clinically useful carbapenem at present, 9 years after available for commercial use.

Anti-Infective Agents↗
PubMed2004

Deletion 6p23 and add(11)(p15) leading to NUP98 translocation in a case of therapy-related atypical chronic myelocytic leukemia transforming to acute myelocytic leukemia.

A NUP98 gene translocation occurring with a del(6p23) and an add(11)(p15) was determined in a 61-year-old patient with therapy-related atypical chronic myelocytic leukemia after complete remission from acute promyelocytic leukemia that eventually underwent clonal evolution and transformed to CD56-positive acute myelocytic leukemia (French-American-British classification M0). Precise chromosome analysis by G-banding, spectral karyotyping analysis, and dual-color fluorescence in situ hybridization showed this abnormality as 46,XY,del(6)(p23),add(p15). ish del(6)(NUP98-,D6Z1+),der(7)(NUP98+,D7Z1+),der(11)(NUP98+,D11Z1). A split signal of NUP98 was observed in 68.4% of the 117 cells analyzed, which clearly indicated that the NUP98 partially translocated to chromosome 7. However, the potential fusion partner of the NUP98 was not HOX family or DEK. The fusion gene has not been found by a differential display method. The significance of simultaneously combined del(6)(p23), which also has been reported with secondary leukemogenesis, has not been elucidated. Additional karyotype abnormalities evolved increasingly, and leukocytosis with blasts with more complex karyotypic abnormalities appeared 5 months later. Careful and continuous analysis of karyotype change clarified the process of the clonal evolution after NUP98 translocation. Further investigation of molecular characterization of this NUP98 translocation and interaction with 6p23 abnormalities might be worthwhile for understanding leukemogenesis.

Chromosome Deletion↗
PubMed2004

Three-dimensional microarray compared with PCR-single-strand conformation polymorphism analysis/DNA sequencing for mutation analysis of K-ras codons 12 and 13.

BACKGROUND: We developed a rapid, precise, and accurate microarray-based method that uses a three-dimensional platform for detection of mutations. METHODS: We used the PamChip microarray to detect mutations in codons 12 and 13 of K-ras in 15 cell lines and 81 gastric or colorectal cancer tissues. Fluorescein isothiocyanate-labeled PCR products were analyzed with the microarray. We confirmed the microarray results with PCR-single-strand conformation polymorphism (SSCP) analysis and DNA sequencing. RESULTS: We could correctly identify wild-type, heterozygous, and homozygous mutant genotypes with the PamChip microarray in <3.5 h. The array data were consistent with those of PCR-SSCP analysis and DNA sequencing. All 15 cell lines and 80 of 81 clinical cancer specimens (98.8%; 95% confidence interval, 96.4-100%) were genotyped accurately with the microarray, a rate better than that of direct DNA sequencing (38.9%) or SSCP (93.8%). Only one clinical specimen was misdiagnosed as homozygous for the wild-type allele. Densitometric analysis of SSCP bands indicated that the content of the mutant allele in the specimen was approximately 16%. The PamChip microarray could detect mutant alleles representing more than 25% of the SSCP band proportions. Therefore, the limit for detection of mutant alleles by the PamChip microarray was estimated to be 16-25% of the total DNA. CONCLUSIONS: The PamChip microarray is a novel three-dimensional microarray system and can be used to analyze K-ras mutations quickly and accurately. The mutation detection rate was nearly 100% and was similar to that of PCR-SSCP together with sequencing analysis, but the microarray analysis was faster and easier.

Cell Line, Tumor↗
PubMed2004

Phenylarsine oxide (PAO) more intensely induces apoptosis in acute promyelocytic leukemia and As2O3-resistant APL cell lines than As2O3 by activating the mitochondrial pathway.

We studied the cytotoxic effect of an organic arsenical compound, phenylarsine oxide (PAO) on an acute promyelocytic leukemia (APL) cell line (NB4) and an As2O3-resistant NB4 subline (NB4/As). Cell growth was inhibited by 50% (IC50) upon 2-day treatment with As2O3 or PAO at 0.54 and 0.06 microM, respectively in NB4 cells (P = 0.025), and 2.80 and 0.08 microM, respectively in NB4/As (P = 0.030). 0.1 microM PAO increased the proportion of hypodiploid cells (50.3%) by a greater degree than the same dose of As2O3 (3.8%) in NB4 cells. In NB4 cells, 0.1 microM PAO reduced the mitochondrial transmembrane potential (20.5% in a PI(negative)-Rhodamine123(low) fraction) by a greater degree than 1 microM As2O3 (7.1%). Western blotting showed that 0.1 microM PAO downregulated the expression of both Bcl-2 and Bcl-X(L) proteins, whereas I microM As2O3 downregulated only Bcl-2 expression. These results suggest that the cytotoxic effect of PAO on an APL cell line and As2O3-resistant subline is significantly higher than that of As2O3. PAO-induced apoptosis seems to be related to the activation of the mitochondrial pathway and downregulation of both Bcl-2 and Bcl-X(L). PAO is a considerable agent for relapsed/refractory APL and for purging APL cells following stem cell transplantation.

Apoptosis↗