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Biomedical subjects

Hayato Miyachi

Publications and source records attributed to Hayato Miyachi.

At least 19 recordsLinked to original sources
PubMed2006

In vivo analysis of the role of aberrant histone deacetylase recruitment and RAR alpha blockade in the pathogenesis of acute promyelocytic leukemia.

The promyelocytic leukemia-retinoic acid receptor alpha (PML-RARalpha) protein of acute promyelocytic leukemia (APL) is oncogenic in vivo. It has been hypothesized that the ability of PML-RARalpha to inhibit RARalpha function through PML-dependent aberrant recruitment of histone deacetylases (HDACs) and chromatin remodeling is the key initiating event for leukemogenesis. To elucidate the role of HDAC in this process, we have generated HDAC1-RARalpha fusion proteins and tested their activity and oncogenicity in vitro and in vivo in transgenic mice (TM). In parallel, we studied the in vivo leukemogenic potential of dominant negative (DN) and truncated RARalpha mutants, as well as that of PML-RARalpha mutants that are insensitive to retinoic acid. Surprisingly, although HDAC1-RARalpha did act as a bona fide DN RARalpha mutant in cellular in vitro and in cell culture, this fusion protein, as well as other DN RARalpha mutants, did not cause a block in myeloid differentiation in vivo in TM and were not leukemogenic. Comparative analysis of these TM and of TM/PML(-/-) and p53(-/-) compound mutants lends support to a model by which the RARalpha and PML blockade is necessary, but not sufficient, for leukemogenesis and the PML domain of the fusion protein provides unique functions that are required for leukemia initiation.

Animals↗
PubMed2006

A cost-effectiveness evaluation of reticulocyte measurement in new outpatients with or without hematologic disorders.

BACKGROUND: Although reticulocyte counts provide very useful information, few studies have analyzed the cost-effectiveness of this testing. METHODS: The yield and cost of reticulocyte count testing were analyzed in 719 new outpatients who visited the comprehensive medicine clinics and received both reticulocyte and complete blood count (CBC) testing. A "useful result" (UR) of the testing was defined as a finding that contributed to a change in a physician's diagnosis or decision-making between the pre- and post-test diagnosis. Patients' medical records were thoroughly reviewed for the assignment of URs. A simulation study was performed, blinding the reticulocyte data to the examiners, for the determination of URs generated by CBC alone. RESULTS: CBC and reticulocyte testing generated a total of 838 URs in 719 patients, while the simulation study demonstrated 612 URs with CBC testing alone. When patients were grouped into 11 major disease categories according to a pre-test diagnosis, clinical effectiveness (UR/patient) varied from 1.69 (hematologic) to 0.13 (metabolic/endocrine patients), with a cost disparity from 206yen to 2784yen/UR. The cost-effectiveness (Deltacost/DeltaUR) of reticulocyte addition against CBC alone was 515yen per additional UR as a whole. Reticulocyte testing showed favorable cost-effectiveness in gastrointestinal ( 234yen) and hematologic patients ( 338yen/additional UR), while the test added few URs in metabolic/endocrine and neurologic patients, resulting in possibly unacceptable cost-effectiveness ( 3240yen and 2916yen/additional UR, respectively). CONCLUSIONS: Wide disparity in its cost-effectiveness among patients apparently indicated that reticulocyte count testing should be performed for selected patient groups on the basis of its cost-effectiveness.

Cost-Benefit Analysis↗
PubMed2006

[A case of tuberculous lymphadenitis found as an abdominal mass penetrating the duodenum].

A 42-year-old woman who complained of epigastralgia was referred to our hospital because of an abdominal mass found by ultrasonography. CT and MRI scans revealed that the abdominal mass, 4 cm in diameter, located on the left side of the right kidney. Gastroduodenoscopy detected a deep ulcerative lesion covered with a yellowish coat in the second portion of duodenum. A sonolucent area at the bottom of the ulcerative lesion seemed to expand to the abdominal mass on ultrasonic endoscopy. Tuberculosis was one possible differential diagnosis. Pathological examination including Ziehl-Neelsen staining using biopsy specimens taken from the bottom of the ulcerative lesion did not show tuberculosis infection. However, polymerase chain reaction analysis using the biopsy specimens revealed that gene expression of tuberculosis was positive. We determined that tuberculous lymphadenitis penetrated the duodenum forming an ulcerative lesion in the duodenum. The administration of anti-tubercular medicine for 6 months male the abdominal mass disappeared and the duodenal ulcerative lesion formed an ulcer scar. We report here a case of tuberculous lymphadenitis penetrating the duodenum which was successfully treated by conservative therapy without surgical treatment.

Adult↗
PubMed2005

Clubbed fingers in a patient with inflammatory gingival hyperplasia.

The association of clubbing with miscellaneous diseases and its diagnostic implications are such that its detection should prompt consideration of the underlying etiology. We encountered a 48-year-old woman with clubbed fingers and a cauliflower-like gingival swelling on the hard palate of the upper jaw. There were no conventionally well-known causes for clubbing. Histological examination of gum biopsy specimen revealed a diagnosis of inflammatory gingival hyperplasia. As an etiology of clubbed fingers, gingivitis was suggested, since clubbing was regressed in parallel with remission of the gingivitis after the treatment by extraction of anterior teeth. Possible involvement of an autoimmune process in the pathogenesis was also considered, because of concomitant elevation of serum anti-double strand DNA antibodies. We recommend examination of the oral cavity for search of an inflammatory disease in cases with clubbed fingers, particularly when other common causes are not apparent.

Antibodies, Antinuclear↗
PubMed2005

Virus-associated hemophagocytic syndrome in an international traveler as a differential diagnosis of SARS.

During the epidemic of severe acute respiratory syndrome in 2003, a 27-year- old Japanese woman presented a high fever and acute respiratory distress with pulmonary infiltrates after traveling to a high-risk area. An alternative diagnosis was made as Epstein-Barr virus-associated hemophagocytic syndrome, based on the proliferation of macrophages with hemophagocytosis in the bone marrow and Epstein-Barr viral marker profiles. Virus-associated hemophagocytic syndrome in an international traveler should be included in the differential diagnosis of severe acute respiratory syndrome.

Adult↗
PubMed2004

A competitive nucleic acid sequence-based amplification assay for the quantification of human MDR1 transcript in leukemia cells.

BACKGROUND: Because clinical drug resistance is caused by low-grade expression of a responsible gene, highly sensitive methods are desirable for its detection in clinical settings. We developed a quantitative nucleic acid sequence-based amplification (NASBA) assay for multidrug resistance-1 (MDR1) transcripts, and applied it to clinical samples. METHOD: MDR1 transcripts were amplified using the NASBA technique combined with sandwich hybridization of amplified MDR1 mRNA followed by chemiluminescence detection on an automated analyzer. Quantification of MDR1 mRNA was achieved through competitive coamplification of in vitro-generated RNA, which acts as an internal control. RESULTS: The competitive NASBA assay exhibited higher sensitivity (reliable detection limit was 100 copies of MDR1 mRNA) and linearity over a broader dynamic range (7 logarithmic orders) than the competitive reverse transcription-polymerase chain reaction assay. All 33 clinical samples obtained from patients with leukemia were successfully assayed, demonstrating its feasibility. MDR1 expression-compensated with beta-actin expression-ranged from 1.4 x 10(2) to 2.5 x 10(6) (median 4.8 x 10(5)) copies/microg RNA, while the range of MDR1 expression in peripheral blood samples from 15 healthy adults was from 8.9 x 10(4) to 5.2 x 10(5) (median 2.2 x 10(5)) copies/microg RNA. MDR1 expression in 8 of 33 clinical samples exceeded the median of healthy adult samples. CONCLUSIONS: The competitive NASBA assay is applicable to MDR1 mRNA quantification in clinical samples and would contribute to detection of clinical multidrug resistance.

ATP Binding Cassette Transporter, Subfamily B, Mem↗
PubMed2004

Expression level of MDR1 message in peripheral blood leukocytes from healthy adults: a competitive nucleic acid sequence-based amplification assay for its determination.

Accurate quantification of multidrug resistance-1 gene (MDR1) expression in target cells would be of important therapeutic value in predicting cellular response to anticancer drugs. Because certain normal cells in peripheral blood physiologically express MDR1, increasing the sensitivity of the detection methods might result in confounding low-degree expression in tumor cells with physiologic expression in normal cells. The purpose of this study was to determine MDR1 mRNA expression levels in peripheral blood leukocytes obtained from healthy adult volunteers using a competitive nucleic acid sequence-based amplification (NASBA) assay. We determined the reference intervals of MDR1 mRNA expression in peripheral blood obtained from 98 healthy adults by measuring its expression with the quantitative NASBA assay between 5.50 x 10(4) copies/microg RNA and 6.76 x 10(5) copies/microg RNA. The new reference intervals were evaluated using a number of sensitive or resistant cell lines as control; positive or negative MDR1 expression was clearly demonstrated. We also reevaluated MDR1 expression levels in leukemia cells obtained from patient peripheral blood; 18 of 31 samples (58%) exceeded the newly established upper reference limit. The cutoff value established could be used to distinguish significant MDR1 expression in tumor cells from physiologic expression in certain normal cells coexistent in peripheral blood.

ATP Binding Cassette Transporter, Subfamily B, Mem↗
PubMed2004

TEL/AML1 overcomes drug resistance through transcriptional repression of multidrug resistance-1 gene expression.

The t(12;21)(p12;q22) chromosomal aberration, which is frequently observed in pediatric precursor B-cell acute lymphoblastic leukemia (ALL), generates the TEL/AML1 chimeric gene and protein. TEL/AML1-positive ALL has a favorable prognosis, and one possible reason is that this subtype of ALL rarely shows drug resistance. AML1/ETO, another AML1-containing chimeric protein, has been shown to transcriptionally repress the activity of the multidrug resistance-1 (MDR-1) gene promoter; thus, we examined whether TEL/AML1 also represses MDR-1 gene expression, possibly preventing the emergence of multidrug resistance. In this study, we show that the TEL/AML1 protein binds to the consensus AML1 binding site in the MDR-1 promoter and transcriptionally represses its activity. Following transient transfection of TEL/AML1 protein into Adriamycin-resistant K562/Adr cells, we also demonstrate that TEL/AML1 can down-regulate the expression of P-glycoprotein, a product of the MDR-1 gene, and restore the chemosensitivity to the cells. Furthermore, we report that MDR-1 mRNA levels in leukemic cells obtained from TEL/AML1-positive ALL patients are lower than those from TEL/AML1-negative ALL patients. Thus, TEL/AML1 protein acts as a transcriptional repressor of MDR-1 gene expression, and although TEL/AML1 has been implicated in leukemogenesis, its effects on the MDR-1 gene may contribute to the excellent prognosis of TEL/AML1-positive ALL with current therapy.

ATP Binding Cassette Transporter, Subfamily B, Mem↗
PubMed2003

Simple, rapid, and automated method for detection of hyperaggregability of platelets using a hematology analyzer.

Estimation of hyperaggregability of platelets is important for diagnosis and prevention of vascular events. We have developed and evaluated a simple and rapid method for detection of a hyperaggregable state of platelets by using an Abbott CELL-DYN(R) 4000 hematology analyzer. Citrated blood samples were collected from 62 patients with chronic cerebral infarction (CCI), of whom 19 patients were treated with ticlopidine, and from 9 healthy subjects. Platelet clumps were detected in the scatter plots for white blood cell populations with the hematology analyzer. Platelet clumps were positive in 20 of 43 (46.5%) CCI patients who were not treated with anti-platelet agents but not at all in 9 healthy subjects and in 19 CCI patients treated with ticlopidine. The detection of platelet clumps in citrated blood by the hematology analyzer was proved useful in detecting a platelet hyperaggregability in CCI patients. This method is simple, rapid, and automated and thus should be suitable for routine clinical use for monitoring indications and the efficacy of anti-platelet drugs.

Aged↗
PubMed2003

Sonographic evaluation of the anterior liver surface in chronic liver diseases using a 7.5-MHz annular-array transducer: correlation with laparoscopic and histopathologic findings.

PURPOSE: We studied the sonographic appearance of the anterior liver surface using an ultrasound scanner equipped with a 7.5-MHz annular-array transducer to determine the accuracy of this imaging modality in monitoring the course of chronic liver diseases. METHODS: We prospectively evaluated patterns of the liver surface in the sonograms of 77 consecutive patients with chronic liver diseases who had undergone sonographic examination with a 7.5-MHz annular-array transducer and a 3.75-MHz convex-array transducer over a 2-year period and compared these findings with those of laparoscopy (using previously described categories) and histopathology. RESULTS: Histopathologically confirmed disease prevalences for inactive chronic hepatitis, active chronic hepatitis, liver cirrhosis, and others were 10% (8/77), 56% (43/77), 29% (22/77), and 5% (4/77), respectively. The sonographic appearance of the liver surface with the 3.75-MHz transducer was classified as either a regular or an irregular pattern. The regular pattern corresponded to 69% (34/50) of the cases in laparoscopic category 200 or 300 and the irregular pattern with 85% (23/27) of the cases in category 400 or 500. The sonographic appearance of the liver surface with the 7.5-MHz transducer was classified as regular, unevenly irregular, diffusely irregular, or nodular. These 4 patterns detected 75% (24/32), 78% (14/18), 52% (12/23), and 75% (3/4) of the cases of laparoscopic categories 200, 300, 400, and 500, respectively. In a comparison of the sonographic patterns of the liver surface with the differential histopathologic findings, the regular sonographic pattern corresponded to 88% (7/8) of the cases of inactive chronic hepatitis, the unevenly irregular pattern with 35% (15/43) of the cases of active chronic hepatitis, and the diffusely irregular and nodular patterns (considered as 1 group) with 68% (15/22) of the cases of liver cirrhosis. CONCLUSIONS: Our results suggest that sonographic evaluation of the liver surface with a 7.5-MHz annular-array transducer using this classification provides detailed information on the evolution of chronic liver diseases that correlates with the laparoscopic and histopathologic findings and thus is a useful noninvasive method for monitoring the disease course to cirrhosis.

Biopsy, Needle↗
PubMed2003

Large diversity in transport-mediated methotrexate resistance in human leukemia cell line CCRF-CEM established in a high concentration of leucovorin.

To elucidate the mechanism(s) of methotrexate (MTX) resistance as a possible reason underlying treatment failure in high-dose MTX regimens combined with leucovorin (LV) rescue, we established MTX-resistant human T-cell leukemia cell line CCRF-CEM cells in the presence of excess LV, and characterized their properties. Continuous exposure of the cells to escalating concentrations of MTX up to 20 microM in the presence of 1000 nM LV resulted in establishment of three MTX-resistant sublines with a wide disparity of resistance degree over a 4 logarithmic range (approximately 40-, 900- and 44,000-fold, respectively). Transmembrane transport of MTX in these sublines was diminished to 52%, 35% and 12%, respectively. Intracellular retention of MTX in these sublines was not different from that of the parent cells. A cell growth study in various concentrations of LV showed that cells with higher resistance to MTX required more LV for optimal growth. In parallel with the resistance levels, there was an increase in mRNA expression of dihydrofolate reductase gene and a decrease in that of thymidylate synthase gene, but no change in that of reduced folate carrier (RFC1) gene, as assessed by northern blot analysis. Sequencing of the RFC1 gene in all 3 sublines revealed a point mutation in codon 47 (TCC-->TTC) resulting in substitution of Phe for Ser residue, and additional deletion of CTG of codon 112 in the subline with the highest resistance. In summary, MTX exposure to CCRF-CEM cells in the presence of 1000 nM LV resulted in the establishment of heterogeneous cell populations with a wide range of transport-mediated MTX resistance, which was associated with differential alterations of RFC gene. These cell lines may serve as models for investigation of the molecular mechanism(s) underlying refractory tumors in high-dose MTX regimens with LV rescue.

Amino Acid Substitution↗
PubMed2003

Quantitative assay of hepatitis C virus RNA using an automated extraction system for specific capture with probes and paramagnetic particle separation.

A commercially available automated specimen preparation instrument for specific probe capture and paramagnetic separation has been developed (AmpliCap/GT-12; Roche Molecular Systems). We evaluated assay performance of the AmpliCap/GT-12 in the quantitative assay for hepatitis C virus (HCV) RNA with the AMPLICOR HCV MONITOR Test (version 2.0). Assay linearity using serial dilutions from a serum panel was observed in the range of 500 to 850000 IU/ml, with a slightly compromised slope in the higher viral titers. The overall within-run and between-run reproducibility of the entire detection process for 3 and 5 log(10) (IU/ml) of HCV RNA in samples had a standard deviation of <0.2, which was comparable to a manual method based on organic extraction and isopropanol precipitation (Roche Molecular Systems). Comparison of the test results with those obtained by the manual method showed a good correlation (R(2) = 0.972, n = 86). Using heparin (3, 6.5, and 13 U/ml), dextran sulfate (0.1, 1, and 5 mM), hemoglobin (1.13, 2.25, and 4.5 g/liter), conjugated or unconjugated bilirubin (7.5, 15, and 30 mg/dl), and ATP (1.25, 2.5, and 5.0 mM) as known inhibitors, inhibition was only detected at a dextran sulfate concentration of 1 mM with the manual method but not with the AmpliCap/GT-12 extraction. In summary, the AmpliCap/GT-12 system was shown to permit a stable extraction process and accurate results for the quantitative assay of HCV RNA, successfully eliminating the inhibitory effect of dextran sulfate. This automated extraction system provides reliable and reproducible test results and saves labor; thus, it is suitable for routine diagnostic PCR.

Automation↗
PubMed2003

Reversal of drug resistance mediated by hammerhead ribozyme against multidrug resistance-associated protein 1 in a human glioma cell line.

We examined the effects of suppressing multidrug resistance-associated protein 1 (MRP1) gene expression in a human glioma cell line U87MG. Hammerhead ribozymes, designed to cleave MRP1 mRNA (alphaMRP1-Rz), were transfected into the U87MG cells. The U87MG/alphaMRP1-Rz cells were significantly sensitive to nitrosourea (ACNU) and doxorubicin (DOX) compared with the U87MG cells (p<0.01 and p<0.05, respectively, unpaired t-test). There was no significant difference in the expression of other human genes between the U87MG/alphaMRP1-Rz and controls by cDNA array. The hammerhead ribozyme-mediated specific suppression of MRP1 was sufficient to reverse the resistance of ACNU and DOX in the human glioma cell line.

Antibiotics, Antineoplastic↗
PubMed2003

Analysis of single nucleotide polymorphism C3435T of the multidrug resistance gene MDR1 in acute lymphoblastic leukemia.

Multidrug resistance is an important mechanism responsible for refractoriness of leukemia and worse outcome of patients. Overexpression of the multidrug resistance gene, MDR1, is of prognostic relevance in acute myeloid leukemia, while its role in acute lymphoblastic leukemia (ALL) is still under debate. Single nucleotide polymorphisms (SNP) have been detected in the MDR1 gene. The C3435T polymorphism in this gene seems to have functional and clinical consequences. In the present investigation, we have analyzed the role of the C3435T SNP for drug resistance and prognosis of human ALL. The C3435T SNP was analyzed in 20 T-ALL cell lines and in blood samples from 53 ALL patients and 7 healthy donors. The cell line panel consisted of cell lines not prior exposed in vitro to cytostatic drugs as well as of drug-resistant lines which were selected in vitro by exposure to doxorubicin, vincristine, methotrexate, or hydroxyurea. We have developed a highly sensitive matrix-assisted laser desorption ionization time-of-flight mass spectrometry (MALDI-TOF-MS)-based genotyping approach to survey the C3435T SNP. Furthermore, mRNA expression was determined by real time reverse-transcribed polymerase chain reaction and doxorubicin sensitivity by a growth inhibition assay. Surprisingly, we did not find a significant correlation between C3435T homo- or heterozygote genotypes and MDR1 mRNA expression of cell lines or blood samples from patients and healthy donors. Furthermore, there was no relationship between the response of the cell lines to doxorubicin and the C3435T genotypes. Homo- or heterozygosity did not correlate to survival of patients in the Kaplan-Meier analysis. In conclusion, we do not have reason to assume that the C3435T SNP contributes to drug resistance of ALL and prognosis of ALL patients.

Antineoplastic Agents↗