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Biomedical subjects

Akihiro Takeshita

Publications and source records attributed to Akihiro Takeshita.

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

Pharmacokinetics of arsenic species in Japanese patients with relapsed or refractory acute promyelocytic leukemia treated with arsenic trioxide.

PURPOSE: To investigate the pharmacokinetics of arsenic species in Japanese patients with relapsed or refractory acute promyelocytic leukemia (APL) treated with arsenic trioxide (ATO) at a daily dose of 0.15 mg/kg. METHODS: Inorganic arsenic (AsIII and AsV) and the major metabolites monomethylarsonic acid (MAA(V)) and dimethylarsinic acid (DMAA(V)) in plasma and urine collected from 12 Japanese patients were quantified by HPLC/ICP-MS. RESULTS: The plasma concentrations of AsIII and AsV on day 1 reached the similar Cmax (12.4 +/- 8.4 and 10.2 +/- 3.9 ng/ml) immediately after completion of administration followed by a biphasic elimination. The AUC(0-infinity) of AsV was about twice that of AsIII. The appearance of methylated metabolites in the blood was delayed. During the repeated administration, the plasma concentrations of inorganic arsenic reached the steady state. In contrast, the MAA(V) and DMAA(V) concentrations increased in relation to increased administration frequency. The mean total arsenic excretion rate including inorganic arsenic and methylated arsenic was about 20% of daily dose on day 1 and remained at about 60% of daily dose during week 1-4. CONCLUSIONS: This study demonstrates that ATO is metabolized when administered intravenously to APL patients and methylated metabolites are promptly eliminated from the blood and excreted into urine after completion of administration, indicating no measurable accumulation of ATO in the blood.

Adult↗
PubMed2006

Role for interleukin-6 and insulin-like growth factor-I via PI3-K/Akt pathway in the proliferation of CD56- and CD56+ multiple myeloma cells.

OBJECTIVES: Several studies including ours have suggested that lack of CD56 in multiple myeloma (MM) defines a unique patient subset with poorer prognosis. However, the mechanism underlying this aggressive behavior of CD56(-) MM has not been well elucidated. Interleukin-6 (IL-6) or insulin-like growth factor I (IGF-I) induce proliferation of MM cells. In this study, we report about the relationship between CD56 expression and responsiveness to these cytokines. METHODS: We sorted out both CD56(-) and CD56(+) fractions from MM cell lines such as KMS-21-BM and U-266, and investigated their different responsiveness to IL-6 or IGF-I. Furthermore, we compared the effects of these cytokines on the regulation of cell-cycle distribution between CD56(-) and CD56(+) cells. RESULTS: Although CD56(-) cells in both KMS-21-BM and U-266 cells responded significantly to IL-6, CD56(+) cells did not. Ki-67(+) cells in the CD56(-) cells were significantly increased by IL-6. Western blotting showed that IL-6 phosphorylated Akt, and upregulated and downregulated the level of cyclin D1 and p27 protein in the CD56(-) KMS-21-BM cells, respectively. LY-294002 completely blocked these effects of IL-6. On the other hand, Ki-67(+) cells in the CD56(+) cells did not respond to IL-6. Anti-IGF-I mAb significantly reduced Ki-67(+) cells only in the CD56(+) cells. IGF-I phosphorylated Akt and upregulated cyclin D1 in the CD56(+) KMS-21-BM cells, which was completely blocked by LY294002. CONCLUSIONS: These results suggest that CD56(-) and CD56(+) MM cells could be stimulated by IL-6 and IGF-I, respectively, via PI3-K/Akt pathway, and provide useful information for anticytokine therapies.

Antibodies, Monoclonal↗
PubMed2006

Clinicopathological and prognostic characteristics of CD33-positive multiple myeloma.

There have been few reports about the CD33 expression on multiple myeloma (MM) cells so far, showing that only a few patients expressed CD33 homogenously on their MM cells. However, in these reports, neither detailed clinical information nor its prognostic significance was described. Therefore, we analyzed the CD33 expression on MM cells from 63 newly diagnosed patients by flow cytometry and the correlation with other clinical parameters to determine the clinicopathological significance of this molecule. Fourteen (22%) patients were positive for CD33. Of the 14 patients with CD33+ MM, >80% of MM cells were positive in six (9.5%). The CD33+ patients had higher beta 2 microglobulin and lactate dehydrogenase levels and higher incidence of anemia and thrombocytopenia than did CD33- patients. The estimated 3-yr overall survival in CD33+ patients was significantly lower than in the CD33- ones (31% and 50%, respectively, P = 0.042). Especially, mortality within a year from diagnosis in the CD33+patients was higher than that in CD33- patients (43% and 10%, respectively, P = 0.005). Serial evaluation of CD33 expression showed that the amount of CD33 significantly increased after a variety of treatment including melphalan and steroid in individual patients. These results suggest that the CD33 expression might be associated with drug resistance to these conventional agents, and CD33 might be a useful target for the development of new therapeutic agents in MM.

Adult↗
PubMed2006

Arrhythmogenic effects of arsenic trioxide in patients with acute promyelocytic leukemia and an electrophysiological study in isolated guinea pig papillary muscles.

BACKGROUND: Arsenic trioxide (As(2)O (3)) is a new promising regimen for patients with a relapse of acute promyelocytic leukemia (APL), but causes life-threatening arrhythmias. This study aimed to investigate the incidence and mechanism of arrythmogenesis caused by As(2)O(3). METHODS AND RESULTS: Standard 12-lead ECGs were monitored throughout As(2)O(3) therapy in 20 APL patients. As(2)O (3) (0.15 mg/kg) significantly prolonged the corrected QT interval (QTc: 445+/-7 to 517+/-17 ms, means+/-SE, p<0.01), and also increased the QTc dispersion and transmural dispersion of repolarization. Non-sustained ventricular tachycardias and torsades de pointes occurred in 4 and 1 patients, respectively. The action potentials and isometric contraction were measured in guinea pig papillary muscles during As(2)O (3) perfusion (350 micromol/L). The action potential duration was prolonged (APD(90): 150+/-11 to 195+/-12 ms at 60 min, p<0.01, n=5) and perfusion of As(2)O(3) in a low K(+) solution with a low stimulation rate augmented the prolongation of APD, and provoked early after-depolarizations and triggered activities. The prolonged exposure to As(2)O(3) induced muscle contracture, aftercontractions, triggered activities and electromechanical alternans. Tetrodotoxin or butylated hydroxytoluene partially prevented the As(2)O(3)-induced prolongation of APD. CONCLUSIONS: The prolonged QTc and spatial heterogeneity are responsible for the As(2)O(3)-induced ventricular tachyarrhythmias. In addition to prolongation of the APD, cellular Ca(2+) overload and lipid peroxidation might contribute to the electrophysiological abnormalities caused by As(2)O(3).

Action Potentials↗
PubMed2006

Two cases of acute promyelocytic leukemia complicated by torsade de pointes during arsenic trioxide therapy.

We describe 2 patients with acute promyelocytic leukemia (APL) in whom torsade de pointes (TdP) developed during treatment with arsenic trioxide. Patient 1 was a 23-year-old woman with second-relapse APL. Ventricular premature beat bigeminy developed on day 27 of treatment, and episodes of TdP developed on day 28. Patient 2 was a 51-year-old woman with second-relapse APL who had cardiomyopathy due to prior anthracycline treatment. TdP developed on day 17 of treatment. Arsenic trioxide is known to cause electrocardiographic abnormalities, such as ventricular tachycardia and prolongation of QT interval. Patient 1 was given fluconazole as a concomitant drug. Patient 2 had cardiomyopathy and hypokalemia. Careful management is needed during arsenic trioxide therapy because this treatment prolongs the QT interval, possibly inducing episodes of TdP.

Adult↗
PubMed2005

Clinical characteristics and prognostic implications of NPM1 mutations in acute myeloid leukemia.

Recently, somatic mutations of the nucleophosmin gene (NPM1), which alter the subcellular localization of the product, have been reported in acute myeloid leukemia (AML). We analyzed the clinical significance of NPM1 mutations in comparison with cytogenetics, FLT3, NRAS, and TP53 mutations, and a partial tandem duplication of the MLL gene (MLL-TD) in 257 patients with AML. We found NPM1 mutations, including 4 novel sequence variants, in 64 of 257 (24.9%) patients. NPM1 mutations were associated with normal karyotype and with internal tandem duplication (ITD) and D835 mutations in FLT3, but not with other mutations. In 190 patients without the M3 French-American-British (FAB) subtype who were treated with the protocol of the Japan Adult Leukemia Study Group, multivariate analyses showed that the NPM1 mutation was a favorable factor for achieving complete remission but was associated with a high relapse rate. Sequential analysis using 39 paired samples obtained at diagnosis and relapse showed that NPM1 mutations were lost at relapse in 2 of the 17 patients who had NPM1 mutations at diagnosis. These results suggest that the NPM1 mutation is not necessarily an early event during leukemogenesis or that leukemia clones with NPM1 mutations are sensitive to chemotherapy.

Adolescent↗
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

Increased creatine kinase BB activity and CKB mRNA expression in patients with hematologic disorders: relation to methylation status of the CKB promoter.

BACKGROUND: We encountered 2 patients with increased activities of the creatine kinase (CK)-BB isoenzyme in their sera. Here we examined the relation among CK-BB activity, expression of CKB mRNA in peripheral blood, and hypermethylation of the CKB. METHODS: The 2 patients and other 26 patients with hematologic malignancies, and some cancer cell lines were subjected to measurement of serum CK activity, CK isoenzyme analysis, CKB mRNA expression analysis by RT-PCR, and methylation analysis of the CKB promoter region. RESULTS: CK-BB activity and proportion of leukemia blasts were correlated in the 2 patients. CKB mRNA was increased in peripheral blood during an increase in leukemia blast numbers. In contrast, none of the other 26 patients showed CK-BB activity or expression of CKB mRNA. In all of the patients with hematologic disorders, the analyzed region of CKB promoter was mostly unmethylated. However, some of cancer cell lines showed the methylated pattern. CKB mRNA was expressed at higher levels in cells with an unmethylated CKB promoter than in cells with a methylated promoter. CONCLUSIONS: Expression of CKB mRNA and CK-B sometimes occurred in blastic transformation of the hematopoietic system. A relation between CKB mRNA expression and methylation of the CKB promoter was suggested.

Base Sequence↗
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

Arsenic trioxide therapy in relapsed or refractory Japanese patients with acute promyelocytic leukemia: updated outcomes of the phase II study and postremission therapies.

Recently, arsenic trioxide (ATO) has been proved to induce complete remission (CR) at a high rate in patients with acute promyelocytic leukemia (APL). We prospectively investigated the safety and efficacy of ATO therapy in patients with relapsed and refractory APL and examined the duration of CR and the postremission therapies. Initially, 0.15 mg/kg ATO was administered until bone marrow remission to a maximum of 60 days. After the patient achieved CR, 1 additional ATO course at the same dosage was administered for 25 days. Of 34 patients, 31 (91%) achieved CR. PML-RAR3 messenger RNA was not detected in the bone marrow of 18 (72%) of the 25 patients evaluated by reverse transcriptase-polymerase chain reaction analysis. At a median follow-up of 30 months, the estimated 2-year overall survival rate was 56%, and the estimated 2-year event-free survival rate was 17%. During the ATO therapy, QTc prolongation was observed in most cases. Fifteen patients developed ventricular tachycardia, and 1 of them showed torsades de pointes. Other adverse events were nausea, water retention, APL differentiation syndrome, skin eruption, liver dysfunction, and peripheral neuropathy, all of which were quite tolerable. ATO therapy was remarkably effective for relapsed APL; however, postremission therapies were necessary to maintain a durable remission.

Adolescent↗
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

Delayed recovery of normal hematopoiesis in arsenic trioxide treatment of acute promyelocytic leukemia: a comparison to all-trans retinoic acid treatment.

OBJECTIVE: To examine laboratory data including total blood cell count, leukocyte morphology and coagulation parameters during treatment for acute promyelocytic leukemia (APL) at a single institute, and compare the precise differences between all-trans retinoic acid (ATRA) and arsenic trioxide (As2O3) treatment. PATIENTS AND METHODS: Sixteen patients with APL who were treated with ATRA or As2O3 alone and achieved complete remission (CR) were analyzed. ATRA 45 mg/m2/day was given orally until CR. As2O3 0.15 mg/kg/day was given intravenously until leukemic blasts and promyelocytes were eliminated from the bone marrow. RESULTS: All 7 patients in the ATRA-treated group were primary cases and all 9 patients in the As2O3-treated group were relapsed cases after the achievement of CR with the ATRA. There was no difference in the data before treatment between these two groups. The duration of leukocytopenia and neutropenia during As2O3 treatment was significantly longer than those of ATRA treatment. The nadir of leukocyte and neutrophil counts was observed later in the As2O3-treated group. Terminal neutrophil differentiation was observed more obviously in the ATRA-treated group. The red blood cell count and hemoglobin concentration decreased significantly at the end of As2O3 treatment and were lower than those of ATRA treatment. Platelets recovered earlier in the ATRA-treated group. Coagulation parameters were not significantly changed between the two groups. CONCLUSION: In comparison with ATRA treatment, the recovery of several components in the peripheral blood cells was delayed in As2O3 treatment. Therefore we should pay more and longer attention in As2O3 treatment.

Antineoplastic Agents↗
PubMed2004

Disease-related potential of mutations in transcriptional cofactors CREB-binding protein and p300 in leukemias.

CREB-binding protein (CBP) and highly related p300 protein are transcriptional co-activators that play an essential role in chromatin remodeling through histone acetyltransferase activity and interaction with other transcriptional regulators. In this study, various hematological malignancies, including nine cell lines and 45 clinical samples (32 acute myeloid leukemias (AML), nine acute lymphoblastic leukemias (ALL), two cases of myelodysplastic syndrome (MDS), one multiple myeloma, and one chronic myelogenous leukemia in blast crisis), were examined to ask whether mutation of the CBP and p300 genes could be involved in leukemogenesis. The answer was approached by employing the reverse transcription-polymerase chain reaction and single-strand conformation polymorphism (RT-PCR/SSCP) technique and subsequent sequence analysis. A T-lymphoblastic cell line, CEM had an in-frame 21-base-pair deletion within the bromodomain of its p300 cDNA. Genomic DNA analysis revealed aberrant splicing caused by mutation of the acceptor site of intron 17 from ag to gg, which should interfere with catalytic step II of the pre-mRNA splicing reaction. In 1 MDS patient, a missense mutation was detected, which caused a replacement from Ser to Gly at codon 507 of p300. This is the first report of CBP/p300 mutations in leukemias, which might be relatively rare but nonetheless contribute to pathogenesis in some fraction of cases.

Acetyltransferases↗