Biomedical subjects

Y Hirakata

Publications and source records attributed to Y Hirakata.

At least 19 recordsLinked to original sources

PubMed2004

Acute infection with influenza virus enhances susceptibility to fatal pneumonia following Streptococcus pneumoniae infection in mice with chronic pulmonary colonization with Pseudomonas aeruginosa.

We established a mouse model in which fatal pneumonia was induced by pneumococcal superinfection following influenza virus infection in chronic Pseudomonas aeruginosa infected mice. In this mouse model, influenza virus infection caused a significant increase in inflammatory cells, cytokines and severe tissue damage in the lungs of these P. aeruginosa infected mice, before pneumococcal infection. Intrapulmonary virus titres were significantly increased in mice with chronic P. aeruginosa infection, compared with control mice. Neutrophil function analysis showed significant reduction of myeloperoxidase (MPO) activity and lysozyme secretion by influenza virus infection in these mice. Our results suggest that influenza virus infection may play an important role in inducing pneumococcal pneumonia in chronic P. aeruginosa infected mice. Our results suggested that our mouse model is useful for investigating the pathogenesis of influenza virus infection in patients with chronic lung infection.

Acute Disease↗

PubMed2004

Virulence of metallo-beta-lactamase-producing Pseudomonas aeruginosa in vitro and in vivo.

We evaluated the virulence of Pseudomonas aeruginosa carrying bla(IMP), a metallo-beta-lactamase gene, and the efficacy of ceftazidime, imipenem-cilastatin, and ciprofloxacin in the endogenous bacteremia model. The presence of bla(IMP) did not practically change the virulence of the parent strain, and ciprofloxacin was effective against infection with P. aeruginosa carrying bla(IMP).

Animals↗

PubMed2004

Immunokinetics in severe pneumonia due to influenza virus and bacteria coinfection in mice.

Coinfections of bacteria and influenza are a major cause of excessive mortality during influenza epidemics. However, the mechanism of the synergy between influenza virus and bacteria are poorly understood. In this study, mice were inoculated with influenza virus, followed 2 days later by inoculation with Streptococcus pneumoniae. The kinetics of viral titres, bacterial numbers and the immune response (cytokine and chemokine production) were also analysed. Short-term survival correlated with pathological changes in the lungs of infected mice. Influenza virus or S. pneumoniae infection alone induced moderate pneumonia; however, severe bronchopneumonia with massive haemorrhage in coinfected mice, which caused death of these mice approximately 2 days after inoculation with S. pneumoniae, was noted. Intrapulmonary levels of inflammatory cytokines/chemokines, type-1 T-helper cell cytokines and Toll-like receptors, and the related mitogen-activated protein kinase signalling molecules (phosphorylated extracellular signal-regulated kinase -1 and - 2, p38 and c-Jun N-terminal kinase), were increased in coinfected mice. These results suggest that immune mediators, including cytokines and chemokines, through Toll-like receptors/mitogen-activated protein kinase pathways, play important roles in the pathology of coinfection caused by influenza virus and Streptococcus pneumoniae.

Animals↗

PubMed2003

High-dose rabeprazole-amoxicillin versus rabeprazole-amoxicillin-metronidazole as second-line treatment after failure of the Japanese standard regimen for Helicobacter pylori infection.

BACKGROUND: There is currently no optimal second-line treatment after failure of Helicobacter pylori triple therapy. AIM: To determine effective salvage therapy after failure of lansoprazole-amoxicillin-clarithromycin. METHODS: After failure of lansoprazole-amoxicillin-clarithromycin 123 out-patients were randomized to receive either 2-week rabeprazole (20 mg b.d.) + amoxicillin (1000 mg b.d.) (RA group) or 1-week rabeprazole (10 mg b.d.) + amoxicillin (750 mg twice b.d.) + metronidazole (250 mg b.d.) (RAM group). Eradication was assessed by the 13C-urea breath test. We also evaluated cytochrome p450 (CYP) 2C19 genotype status, determined by polymerase chain reaction - restriction fragment length polymorphism, and susceptibility to clarithromycin and metronidazole. RESULTS: On an intention-to-treat basis, H. pylori infection cure was achieved in 37 of 63 (59%) patients in the RA group and in 49 of 60 (82%) patients in the RAM group. Per protocol-based eradication rates in the RA and RAM groups were 66% (37/56) and 88% (49/56), respectively. In both analytic sets there were significant differences between the treatment groups (P < 0.01 in each). Mild adverse events were observed in eight and five patients from the RA and RAM groups, respectively. Genetic predisposition of CYP2C19 and antibiotic resistance did not influence the treatment outcome either regimen. CONCLUSIONS: The rabeprazole + amoxicillin + metronidazole therapy yielded satisfactory results. In contrast, the cure rate in high-dose rabeprazole + amoxicillin was below an acceptable level.

2-Pyridinylmethylsulfinylbenzimidazoles↗

PubMed2003

Significance of HTLV-1 proviral load quantification by real-time PCR as a surrogate marker for HTLV-1-infected cell count.

We developed a real-time (RT) PCR quantitative assay to measure the level of the integrated viral genome of HTLV-1 in host peripheral blood-mononuclear cells (PB-MNC) from healthy carriers and patients with adult T-cell leukemia (ATL). All of the clinical specimens were serologically and molecularly characterized by enzyme-linked immunosorbent assay (ELISA) and Southern blot hybridization (SBH) analyses. The assay system for quantifying the proviral copy level was sensitive, accurate, and reproducible over a wide range of density from 100 to 0.1% with a coefficient of variation (%) of 4.5 to 9.6. The proviral load of the healthy carriers and patients with ATL was 301 +/- 339 copies per 10(4) MNC (3 +/- 3.4%) on average and varied depending on the ATL cell number and the SBH band-status of single or multiple bands. In ATL cases with multiple bands detected by SBH analysis, their ATL cells were shown to harbor multiple copies within one ATL cell, so that the corrected copy number interpolated by the band number in SBH was closely equivalent to the expected ATL cell number in PB, corresponding to the virus-infected cell burden. The proviral load in healthy carriers ranged from 0.1 to 15% of PB-MNC, and, in combination with the fraction (%) of ATL-like flower cells defined by PB smear morphology, enabled carriers to be subgrouped into three categories. This result indicates that the detection of proviral load by(RT) PCR is sufficient and relevant to monitor the infected cell number in the PB and to evaluate the HTLV-1 pathologic status.

Biomarkers↗

PubMed2003

Detection of Legionella DNA by PCR of whole-blood samples in a mouse model.

A detection system for Legionella DNA in blood samples based on the PCR was developed and evaluated in A/J mice with experimentally induced Legionella pneumonia. Primers were designed to amplify a 106 bp DNA fragment of the 16S rRNA gene specific to Legionella species. The PCR system could detect clinically relevant Legionella species including Legionella pneumophila, Legionella micdadei, Legionella bozemanae, Legionella dumoffii, Legionella longbeachae, Legionella gormanii and Legionella jordanis. The sensitivity of the PCR system was 20 fg extracted DNA. In the mouse model, the blood PCR was compared with results obtained by PCR on bronchoalveolar lavage fluid (BALF) samples, cultures of blood and BALF and detection of Legionella urinary antigen. Blood PCR was positive until 8 days after infection, while BALF PCR became negative on day 4. These results indicate that PCR using blood samples may be a useful, convenient and non-invasive method for the diagnosis of Legionella pneumonia.

Animals↗

PubMed2002

Chemotherapy targeting methylthioadenosine phosphorylase (MTAP) deficiency in adult T cell leukemia (ATL).

Methylthioadenosine phosphorylase (MTAP) is an important enzyme used for the salvage of adenine and methionine. Cells lacking this enzyme are expected to be sensitive to purine synthesis inhibitors and/or methionine starvation. We reported previously that the MTAP gene is deleted in adult T cell leukemia (ATL) cells. In the present study, we expanded our series and used a real-time quantitative PCR assay for accurate diagnosis of the deletion and nine of 65 primary ATL samples (13.8%) were MTAP negative. In spite of this low incidence, ATL cells showed significantly higher sensitivity to L-alanosine, an inhibitor of de novo adenosine monophosphate (AMP) synthesis, than normal lymphocytes, suggesting that the MTAP gene is inactivated not only by deletion but also by other mechanisms. Indeed, a real-time quantitative RT-PCR assay disclosed that primary ATL cells had significantly lower MTAP mRNA expression than normal lymphocytes. Since MTAP-negative ATL cell lines also showed much higher sensitivity to L-alanosine than MTAP-positive ATL cell lines, we used these cell lines to investigate whether it is possible to develop selective therapy targeting MTAP deficiency. A substrate of MTAP, methylthioadenosine (MTA) or its substitutes rescued concanavalin A (Con A)-activated normal lymphocyte proliferation from L-alanosine toxicity. All the compounds except 5'-deoxyadenosine, however, also caused the undesirable rescue of MTAP-negative ATL cell lines. 5'-Deoxyadenosine had the desired ability to rescue hematopoietic progenitor cells without rescuing ATL cell lines. These results support the rationale for a chemotherapy regimen of L-alanosine combined with 5'-deoxyadenosine rescue in MTAP-deficient ATL.

Adenosine Monophosphate↗

PubMed2001

Aberrant expression of caspase cascade regulatory genes in adult T-cell leukaemia: survivin is an important determinant for prognosis.

Derangement of either apoptosis or cell division is known to play an important role in tumorigenesis. Fas-mediated apoptosis on normal and leukaemic T cells is finely tuned by inhibitory proteins, such as FAP-1, FLIP and survivin, and defective caspase isoform which can attenuate the function of its intact caspase as a decoy molecule. However, complex involvement of such inhibitors in tumour biology relating to apoptotic pathology remains unclear in the neoplasms. We report the aberrant expression of FAP-1, FLIP and survivin mRNAs on leukaemic T cells from adult T-cell leukaemia (ATL) patients. Among these inhibitors, only survivin was aberrantly expressed in all ATL cases, but not in any normal peripheral blood mononuclear cells (PBMCs). Furthermore, survivin mRNA expression level was characteristic in each subtype of ATL and represented an important determinant for ATL prognosis. However, the apoptotic effector of casp-8, which is essential in Fas-mediated signal transduction, was dominant in defective casp-8 rather than intact casp-8 in ATL cells, suggesting a favourable biological situation for escape from apoptosis. Taken together, ATL cells probably possess many different regulatory mechanisms in order to attenuate Fas-mediated signalling and subsequently expand their populations under escape from apoptosis. Among these inhibitors, survivin is a useful bio-marker to assess tumour biology and may be a potential new target for apoptosis-based selective therapy in neoplasms as the expression is a general feature of neoplasia, but not normal tissues.

Apoptosis↗

PubMed2001

Effects of parenterally administered ciprofloxacin in a murine model of pulmonary Pseudomonas aeruginosa infection mimicking ventilator-associated pneumonia.

BACKGROUND AND METHODS: We compared the bacteriological, pharmacological and histopathological effects of parenterally administered ciprofloxacin (CPFX) to those of imipenem/cilastatin (IMP/CS) and cefozopran (CZOP) in a murine model of mucoid Pseudomonas aeruginosa pneumonia mimicking ventilator-associated pneumonia. RESULTS: The minimum inhibitory concentrations (MICs) of CPFX, IMP and CZOP were 1.0, 1.0 and 4.0 mg/l, respectively. Treatment with CPFX resulted in a significant decrease in the number of viable bacteria [control, IMP/CS, CZOP and CPFX (mean +/- SEM): 5.02 +/- 0.20, 4.96 +/- 0.38, 5.44 +/- 0.13 and 3.27 +/- 0.02 log(10) colony-forming units lung, respectively]. Histopathological examination revealed that inflammatory changes in the CPFX-treated group were less marked than in other groups. Of the drugs analyzed, the pharmacokinetic parameters of area under the time-concentration curve (AUC)/MIC, AUC exceeding MIC and the time that lung concentrations of drug remained above the MIC were highest for CPFX. CONCLUSION: Our results suggest that parenterally administered ciprofloxacin is effective in ventilator-associated P. aeruginosa pneumonia.

Animals↗

PubMed2001

[Extended-spectrum beta-lactamases (ESBLs) producing bacteria].

TEM- or SHV-type extended-spectrum beta-lactamases(ESBLs) are of clinical concern in Europe and the United States, whereas bacterial strains producing such types of ESBLs had not been reported in Japan for many years. Toho-1, a different type class A ESBL, has been reported in 1995, in which any prototypical enzyme has not been identified so far. At present Toho-1 is the major ESBL in Japan, however, SHV5 alpha has been reported in 1998, followed by TEM-26, SHV-2, and SHV12. More recently, SHV-24, a novel SHV-derived ESBL has also been found. Since Toho-1-type ESBL, AmpC-type beta-lactamase, and class B metallo-beta-lactamase have been widely found in Japan, a novel detection system for ESBLs suitable for this country should be developed.

Bacteria↗

PubMed2001

[Susceptibilities of bacteria isolated from patients with lower respiratory infectious diseases to antibiotics (1999)].

From October 1999 to September 2000, we collected the specimen from 430 patients with lower respiratory tract infections in 17 institutions in Japan, and investigated the susceptibilities of isolated bacteria to various antibacterial agents and antibiotics and patients' characteristics. Of 515 strains that were isolated from specimen (mainly from sputum) and assumed to be bacteria causing in inflammation, 506 strains were investigated. The breakdown of the isolated bacteria were: Staphylococcus aureus 78, Streptococcus pneumoniae 101, Haemophilus influenzae 104, Pseudomonas aeruginosa (non-mucoid) 58, P. aeruginosa (mucoid) 11, Moraxella subgenus Branhamella catarrhalis 41, Klebsiella pneumoniae 18, etc. Of 78 S. aureus strains, those with 4 micrograms/ml or above of MIC of oxacillin (methicillin-resistant S. aureus: MRSA) occupied 57.7%. Vancomycin and arbekacin showed the most potent activities against MRSA without detection of ABK-resistant strain (MIC: 64 micrograms/ml) and decrease of VCM-sensitive strains those were found in 1998. The frequency of S. pneumoniae exhibiting low sensitivity to penicillin (penicillin-intermediate S. pneumoniae: PISP + penicillin-resistant S. pneumoniae: PRSP) decreased to 34.7% from 46.0% in 1998. The frequency of PRSP was 3.0%, being the least number after 1991. Carbapenems showed strong activities against S. pneumoniae. Especially, panipenem inhibited the growth of all 101 strains with MIC of 0.063 microgram/ml. Generally, all drugs showed strong activities against H. influenzae with MIC80s of 4 micrograms/ml or below. MICs of ofloxacin ranged between 0.063 microgram/ml and 4 micrograms/ml in 1998, however, those were 0.125 microgram/ml or below in all H. influenzae in 1999 showing the strongest activity. Tobramycin and ciprofloxacin showed strong activities against P. aeruginosa (both mucoid and non-mucoid) with MIC80s of 1 microgram/ml. Number of isolated P. aeruginosa (mucoid) was little as 11, however, the susceptibilities to all drugs were better than P. aeruginosa (non-mucoid). K. pneumoniae showed good susceptibilities to all drugs except for ampicillin with decreasing of low-sensitive strains compared to those detected in 1998. Also, all drugs generally showed strong activities against M. (B.) catarrhalis. MIC80s of all drugs were 2 micrograms/ml or below. The drug which showed the strongest activity was imipenem inhibiting all 41 strains with MIC of 0.063 microgram/ml. On the patients' characteristics, the number of patients aged 80 years or older who had been increased was decreased in 1999 in the distribution by age. The percentage of the elderly patients aged 70 years or older was 47.0%, which occupied almost a half number of the total patients as in the last year. As for the incidence by disease, bacterial pneumonia and chronic bronchitis were the highest. They were noted in 37.9% and 30.5% of the patients, respectively. In 1999, bronchial asthma was frequently observed as compared in recent years. It was noted in about 10% of the patients which is the same % as in bronchiectasis. We examined the number of strains from these patients with infections before and after administration of antibiotics. In patients with bacterial pneumonia, the number of isolated strains was almost the same between those before and after administration. However, in patients with chronic bronchitis, the number of strains remarkably decreased to less than the half of the total after administration of antibiotics in the last year, but it decreased to 2/3 of the total in 1999. On the administration of antibiotics and isolated bacteria by the day of administration, the bacteria which were isolated more before administration were H. influenzae in 28.4%, S. pneumoniae in 25.7%, M. (B.) catarrhalis in 12.0% and S. aureus in 10.6%. The frequency of S. aureus after administration over 15 days was almost the same as that before administration, but the frequency of P. aeruginosa (both mucoid and non-mucoid) was 36.8% which was higher than that before administration. The frequency of isolated S. pneumoniae was decreased after administration and none of them was isolated after completion of administration. However, that of H. influenzae was decreased to 7.1% after administration within 3 days, and many H. influenzae were isolated after completion of administration as 21.4%.

Adolescent↗

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

Penetration of clinical isolates of Pseudomonas aeruginosa through MDCK epithelial cell monolayers.

Pseudomonas aeruginosa causes both invasive (bacteremic) and chronic noninvasive infections. A simple in vitro system to screen P. aeruginosa clinical isolates for their capacity to penetrate MDCK cell monolayers has been developed. By means of this system, P. aeruginosa clinical isolates, including 32 blood and 45 respiratory isolates, were examined. When monolayers were infected with 3.5x107 cfu of bacteria, significantly more blood (93.7%) than respiratory (54.4%) isolates (P<.001) were detected in the basolateral medium after 3 h. Penetration ability was usually independent of cytotoxicity. Only 8 (4 blood and 4 respiratory) isolates were cytotoxic, possessed exoU, and passed through the monolayer after epithelial cell death, associated with a marked drop in transepithelial electrical resistance. Conversely, noncytotoxic isolates with high penetration ability but without severe epithelial damage were invasive. This system is well suited for screening clinical isolates and their mutants for specific genes conferring the invasiveness phenotype.

Animals↗

PubMed2000

Combination therapy for chronic Pseudomonas aeruginosa respiratory infection associated with biofilm formation.

There had been no reports of investigations into biofilms in chronic respiratory infection in vivo. Recently, we established a new murine model of chronic respiratory infection with Pseudomonas aeruginosa. In the present study, we examined the bacteriological effect of combined clarithromycin and levofloxacin against chronic respiratory infection with P. aeruginosa. Scanning electron micrograph of the surface of the catheter intubated in mouse bronchus for 7 days demonstrated in vivo formation of a biofilm containing blood cells, complex fibrous structures and bacteria. Treatment with either clarithromycin alone or levofloxacin alone had no statistical effect on the number of viable bacteria in lung. The combined use of both drugs resulted in a significant decrease in the number of viable bacteria. The present experiment demonstrates that the newly established murine model was useful to investigate the treatment of biofilm-associated chronic respiratory infection with P. aeruginosa, and combination therapy with clarithromycin and levofloxacin was effective in biofilm-associated chronic respiratory infection.

Animals↗

PubMed2000

In vitro activity of telithromycin (HMR3647), a new ketolide, against clinical isolates of Mycoplasma pneumoniae in Japan.

The in vitro activity of telithromycin (HMR3647), a new ketolide, against Mycoplasma pneumoniae was determined by the broth microdilution test using 41 clinical isolates obtained in Japan, as compared with those of five macrolides (erythromycin, clarithromycin, roxithromycin, azithromycin, and josamycin), minocycline, and levofloxacin. Telithromycin was less potent than azithromycin, but it was more active than four other macrolides, minocycline, and levofloxacin; its MICs at which 50 and 90% of the isolates tested were inhibited were both 0.00097 microg/ml, justifying clinical studies to determine its efficacy for treatment of M. pneumoniae.

Anti-Bacterial Agents↗

PubMed2000

Toxic shock-like syndrome caused by T serotype B3264 streptococcus.

A 45-year-old woman was transferred from a local hospital to our hospital because of shock-like manifestations in addition to septic polyarthritis and necrotizing cellulitis of the left leg. Since Streptococcus pyogenes was isolated from the blood culture examined one day before admission, the diagnosis of streptococcal toxic shock-like syndrome (TSLS) was made. Antibiotic treatment together with supportive care started at the time of admission, resulting in clinical improvement, although poststreptococcal acute glomerulonephritis occurred during the period. TSLS is a life-threatening disease, but early recognition of the disease and prompt initiation of appropriate treatment may lead to successful outcome.

Anti-Bacterial Agents↗

PubMed1999

Paradoxical synergistic effects of tumour necrosis factor and interleukin 1 in murine gut-derived sepsis with Pseudomonas aeruginosa.

The authors evaluated the synergistic effect of tumour necrosis factor (TNF) and interleukin 1 (IL-1) in gut-derived sepsis in mice. After colonization of Pseudomonas aeruginosa strain D4 in the gastrointestinal tract, cyclophosphamide was administered to induce bacterial translocation of the P. aeruginosa and thereby to cause gut-derived sepsis. In this model, treatment either with 8 microg/kg of recombinant human TNF-alpha (rhTNF-alpha) or 2 microg/kg of recombinant human interleukin 1alpha (rhIL-1alpha) solely did not affect the mortality, whereas combined administration of the same doses of rhTNF-alpha and rhIL-1alpha significantly increased the mortality rate in comparison with saline-treated mice. Bacterial counts in liver and blood were significantly higher in rhTNF-alpha and rhIL-1alpha treated mice than in saline-treated mice. Endogenous TNF-alpha and IL-1beta productions were stimulated after combined treatment with rhTNF-alpha and rhIL-1alpha. On the contrary to these adverse effects, combined treatment with 500 microg/kg of rhTNF-alpha and 50 microg/kg of rhIL-1alpha on the day before the administration of cyclophosphamide significantly reduced the mortality from septic infection. We conclude that TNF and IL-1 synergistically affect the mortality of mice after gut-derived sepsis due to P. aeruginosa in mice and the timing of treatment with these cytokines causes both extremes in their effects.

Animals↗

PubMed1999

Qualitative and quantitative characterization of Fas (APO-1/CD95) on leukemic cells derived from patients with B-cell neoplasms.

Expression density and function of Fas (APO-1/CD95) on malignant B-cells, an antigen thought responsible for abnormal tumor biology, remains to be fully understood. Fifty-five cases with B-cell neoplasms of acute lymphoblastic leukemia (ALL), chronic lymphocytic leukemia (CLL), hairy cell leukemia (HCL), B-cell malignant lymphoma (ML), and myeloma (MM) were studied for qualitative and quantitative expression and function of Fas using flow cytometry and annexin-V staining methods. Fas expression was flow cytometrically unimodal with heterogeneous density and showed quantitatively characteristic features among different diseases; weak in ALL, faint in CLL, moderate in HCL, and strong in ML, respectively. Not only full-length but also alternatively spliced truncated mRNAs were detected even in leukemic B-cells with qualitatively faint or negative Fas, and then band density of the former transcripts by RT-PCR was correlated to the Fas protein expression level. Short-term culture of freshly isolated cells gave rise to increases of Fas density and susceptibility for apoptosis, suggesting that the mRNA and inducible Fas are functional at least in vitro. These results show that Fas is a biological marker for characterizing B-cell neoplasms reflecting various stages of B-cell ontogeny and may have clinical utility as a therapeutic strategy.

Apoptosis↗