Biomedical subjects

Yosuke Aoki

Publications and source records attributed to Yosuke Aoki.

11 recordsLinked to original sources

PubMed2005

Quantitative microarray-based DNA-DNA hybridization assay for measuring genetic distances among bacterial species and its application to the identification of family Enterobacteriaceae.

Quantitative DNA-DNA hybridization to measure the genetic distances among bacterial species is indispensable for taxonomical determination. In the current studies, we developed a method to determine bacterial DNA relatedness on a glass microarray. Reference DNAs representing a total 93 species of Enterobacteriaceae were arrayed on a glass microplate, and signal intensities were measured after 2 hr of hybridization with Cy3-labeled bacterial DNAs. All immobilized DNAs from members of the family Enterobacteriaceae were identified by this method except for DNAs from Yersinia pseudotuberculosis and Y. pestis. These results suggest that quantitative microarray hybridization could be an alternative to conventional DNA-DNA hybridization for measuring chromosome relatedness among bacterial species.

DNA, Bacterial↗

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↗

PubMed2004

[The isolation frequency and antimicrobial susceptibility of Haemophilus influenzae isolated in Saga University Hospital].

Isolation frequency and antimicrobial susceptibility of Haemophilus influenzae isolated in Saga University hospital from October 2002 to September 2003 were investigated. Out of 155 H. influenzae strains subjected 77 were isolated from pediatrics specimens. beta-Lactamase negative ampicillin (ABPC)-resistant H. influenzae (BLNAR), against which MICs of ABPC were higher than 4 microg/mL, were 32 strains (20.6%), and it became 63 strains (41.3%) when Low-BLNAR, against which MICs of ABPC were higher than 2 microg/mL, were included. beta-Lactamase positive ABPC-resistant H. influenzae (BLPAR) were 8 strains (5.2%). Although those BLNAR were also resistant to variety of beta-lactams, fluoroquinolones and other antibiotics were not affected by the level of ABPC-resistance. Resistant strains of BLPAR against SBT/ABPC, a combination of a beta-lactamase inhibitor, were detected but all of them were sensitive to TAZ/PIPC, an another combination. Those strains were able to be considered as beta-lactamase positive amoxicillin-clavulanate resistant H. influenzae (BLPACR). PIPC, TAZ/PIPC, CTRX, CDTR, MEPM, LVFX and CPFX showed good activity among tested antibiotics.

Adolescent↗

PubMed2003

[Efficacy of docetaxel (TXT) combined with cisplatin (CDDP) in non-small cell lung cancer].

A multicenter cooperative study of docetaxel (60 mg/m2) combined with cisplatin (60 mg/m2) was performed in stage III and IV patients with inoperable non-small cell lung cancer from March 1998 to September 1999. Of 37 patients enrolled, 36 patients were eligible. One patient obtained a complete response (CR) and nine patients had a partial response (PR). The overall response rate in 36 patients was 28.6%. The median survival time was 360 days. The response rates of stage III and stage IV patients were 36.8% and 18.7%, respectively. The median survival times of stage III and stage IV patients were 502 days and 286 days, respectively. The major toxicities were grade 3 leukopenia (16.2%), grade 3 neutropenia (32.4%), and grade 4 neutropenia (10.8%).

Adult↗

PubMed2003

[Antibacterial activity of oral Cephems against various clinically isolated strains].

We determined the antibacterial activities of oral Cephems against isolated from the patients with the respiratory infections, the urinary tract infections, and infections in the obstetrics field of an adult and a child, during the period from 2002 to 2003; Streptococcus pyogenes, Streptococcus pneumoniae, Haemophilus influenzae, Branhamella catarrhalis, Klebsiella pneumoniae and Escherichia coli of 40 strains of each, and Peptostreptococcus spp. 22 strains. S. pneumoniae and H. influenzae strains that resistant is regarded were collected mainly, penicillin-intermediate S. pneumoniae (PISP), penicillin-resistant S. pneumoniae (PRSP) and beta-lactamase negative ampicillin-resistant H. influenzae (BLNAR) strains. The MICs of Cephems except cefaclor (CCL) were < or = 0.03 microgram/mL against all strains of S. pyogenes. The MICs of cefteram (CFTM) and cefditoren (CDTR) were < or = 0.0125 microgram/mL activity against 7 strains penicillin-susceptible S. pneumoniae (PSSP). However the MIC90s of cefditoren (CDTR) was 1 microgram/mL, cefteram (CFTM), and cefcapene (CFPN) were 2 micrograms/mL against PISP and PRSP, were higher than those of other drugs, but showed slightly higher than PSSP. The MIC90s of Cephems. were 0.5-4 micrograms/mL against strains of E. coli. The MIC90s of CFTM was 0.5 microgram/mL, and CDTR, CFPN were 1 microgram/mL against E. coli were higher than those of other drugs. The four strains of E. coli however were highly-resistant which MIC90s of CCL were more than 32 micrograms/mL were obtains. Furthermore it is necessary to pay much attention to the trend of resistant such as E. coli of Cephems. Although all strains showed resistant to AMPC, MIC90 of Cephems were 0.25-1 microgram/mL, good activities against K. pneumoniae. Against beta-lactamase negative ampicillin-susceptible H. influenzae (BLNAS) 23 strains the MIC90s of CCL and other Cephems were 64 micrograms/mL and 0.25-8 micrograms/mL. The MIC90s of CDTR and CFTM were < or = 1 microgram/mL of BLNAR (15 strains). However there of CFDN and CPDX were 8 micrograms/mL and CCL were > or = 16 micrograms/mL. Two strains which were produced beta-lactamase were highly--ABPC resistant. Although B. catarrhalis all strains were produced beta-lactamase and Cephems except for CCL showed better susceptibility than AMPC. The MIC90s of Cephems were 0.25-2 micrograms/mL against Peptostreptococcus spp.

Administration, Oral↗

PubMed2002

Effect of Shiga toxins on granulocyte function.

We already showed that injection of Shiga toxin (Stx) 2 into mice caused severe granulocytosis in the peripheral blood. In this study we further clarified changes of granulocyte function by Stx 2. The activity of medullasin, a neutral serine protease in granulocytes that injures endothelial cells in vessels, significantly increased when Stx 2 was injected into mice intraperitoneally. Since granulocyte count in the peripheral blood of mice was markedly increased after intraperitoneal injection of Stx 2, medullasin activity in the peripheral blood was remarkably elevated. In contrast to Stx 2, injection of Stx 1 into mice caused no elevation of medullasin activity in granulocytes nor increase in granulocyte count in the peripheral blood. Cathepsin G levels in granulocytes increased only slightly after Stx 2 injection. Granulocytes obtained from mice injected with Stx 2 showed reduced superoxide-producing activity compared with those from controls. Addition of Stx 2 or Stx 1 to human mature granulocytes in vitro decreased their superoxide-producing activity when stimulated with agonists. Therefore, these toxins produced from Escherichia coli augment toxic effect of the bacteria by reducing bactericidal activity of granulocytes. Tissue injury in organisms infected with Shiga toxin-producing E. coli is mainly derived from elevated neutral proteases, such as medullasin, in granulocytes rather than direct toxic effect of superoxide from granulocytes. Hemolytic uremic syndrome caused by Shiga toxin-producing E. coli infection is due, at least in part, to the elevation of medullasin levels produced by granulocytes.

Animals↗

PubMed2002

Pyogenic vertebral osteomyelitis caused by Prevotella intermedia.

We describe a case of vertebral osteomyelitis caused by Prevotella intermedia, which is an extremely unusual cause of vertebral osteomyelitis. The organism was isolated from vertebral biopsies and the patient was treated successfully with intravenous ampicillin-sulbactam and clindamycin. Diagnosis and management of this condition are described, and the importance of anaerobic bacteria in the pathogenesis of vertebral osteomyelitis is discussed.

Biopsy, Needle↗

PubMed2002

[A case of bacteremic group A streptococcus infection with organ dysfunction following a minor skin abrasion].

A 20-year-old male was admitted to our hospital with the chief complaints of high fever and pain around his right hip joint. He had his right knee injured with a slight abrasion three weeks before. The diagnosis of suppurative lymphadenitis of inguen was made, and intravenous cefotiam was started. Despite these treatments his fever continued, general edema and dry cough appeared. Arterial blood gas showed severe hypoxia and chest X ray revealed marked cardiomegaly associated with ground-glass opacity over bilateral lower pulmonary fields. Slight renal insufficiency was also observed. On the fifth hospital day, the culture specimens of both blood and pus from the abrasion on admission yielded Streptococcus pyogenes. His condition was diagnosed as severe group A Streptococcus infection, then antibiotics were switched to intravenous administration of high dose aminobenzyl penicillin and clindamycin in combination with protease inhibitor, urinastatin. After these treatments, his condition improved and he was discharged from the hospital after one month. Group A Streptococcus may cause uncommon but life-threatening infection such as septicemia. Early recognition of the disease and prompt initiation of appropriate treatment may lead to successful outcome.

Adult↗

PubMed2002

Shiga toxin 2 induces macrophage-granulocyte colonies from human bone marrow and cord blood stem cells.

Addition of Shiga toxin 2 to human bone marrow or cord blood cell culture induced macrophage-granulocyte colonies. Although Shiga toxin 2 alone induced colonies mainly composed of macrophages, it induced colonies mainly consisting of granulocytes when combined with physiological doses of interleukin-1beta, granulocyte colony-stimulating factor, or stem cell factor with interleukin-3.

Bone Marrow Cells↗

PubMed2002

An involvement of granulocyte medullasin in phenytoin-induced gingival overgrowth in rats.

To investigate the relationship between histological changes and distributions of medullasin, a neutrophil elastase-like serine proteinase, in phenytoin-induced gingival overgrowth, we established a rat model of gingival overgrowth. Thirty-two, 20-day-old male Fischer 344 rats were fed a diet containing phenytoin and sacrificed at 1, 2, 4 and 8 weeks. Control rats (n = 40) were fed the same diet, but without the drug and killed at the same weeks as experimental rats (n = 32) and 0 week (n = 8). The mandible specimens were resected and sectioned bucco-lingually between the first and second molars. A marked inflammatory-cell infiltration and elongated rete pegs were seen in the phenytoin-treated group. The extent of the overgrowth assessed by computer image analysis and the density of medullasin-positive cells by immunohistochemistry in the approximal gingiva showed a significant increase in the phenytoin-treated group compared to the control group. A marked infiltration of the positive cells in experimental rats was observed as early as 2 weeks when gingival overgrowth was not fully established. Medullasin-positive cells were mostly neutrophils and partly macrophage-like cells. These findings suggest that medullasin may be involved in mainly host defense and secondarily collagen metabolism in the phenytoin-induced rat model of gingival overgrowth.

Animals↗

PubMed2002

[Determination of medullasin levels for the diagnosis of multiple sclerosis].

Medullasin levels in granulocytes of patients with neurological diseases and healthy volunteers were determined by the enzyme immunoassay using mouse monoclonal antibodies against human medullasin and o-phenylenediamine-H2O2 as the detection system of the enzyme activity. One hundred twenty-one out of 159 patients with multiple sclerosis (76.1%) showed positive results (above means of normals + 2SD) in this test, while only 16.9% (24/142) of patients with non-inflammatory neurological diseases had positive results. This enzyme immunoassay method for medullasin is considered to be an useful paraclinical test for the diagnosis of multiple sclerosis.

Adolescent↗