Biomedical subjects

H Miyachi

Publications and source records attributed to H Miyachi.

At least 91 records · Page 5Linked to original sources

PubMed1993

Differential alterations of dihydrofolate reductase gene in human leukemia cell lines made resistant to various folate analogues.

In order to clarify a molecular mechanism of folate resistance in leukemia cells, we studied alterations of the dihydrofolate reductase (DHFR) gene in a human leukemia cell line, MOLT-3, and its sublines made resistant to methotrexate (MTX), trimetrexate (TMQ) and N10-propargyl-5,8-dideazafolic acid (CB3717), alone or in combination. Major alterations of the DHFR gene were examined by Southern analysis of high-molecular-weight DNA. The presence of a base change (T-->C) at nucleotide position 91 of the DHFR gene, which is reported to be responsible for the reduced affinity of the enzyme for MTX in an MTX-resistant human colon carcinoma cell, was examined by allele-specific oligonucleotide hybridization. In a 10,000-fold MTX-resistant subline (MOLT-3/MTX10,000), the normal allele of DHFR gene had been amplified. In contrast, a 200-fold TMQ-resistant subline (MOLT-3/TMQ200) and a 30-fold CB3717-resistant subline selected from MOLT-3/TMQ200 (MOLT-3/TMQ200-CB-3717(30)) were shown to have the mutant allele. Furthermore, the mutant allele had been amplified in a 500-fold MTX-resistant subline, which was established by the continuous exposure of the MOLT-3/TMQ200 cells to stepwise increases of drug concentration and designated as MOLT-3/TMQ200-MTX500. On the other hand, a 40-fold-resistant subline to CB3717 alone (MOLT-3/CB3717(40)) showed the normal allele without amplification. These data suggest that complex alterations of the DHFR gene are involved in the molecular mechanisms of folate resistance that can be differentially introduced into leukemia cells by exposure to various folate analogues, alone or in combination.

Antineoplastic Agents↗

PubMed1993

[Importance of primer selection in 5'NC region for the detection of hepatitis C virus RNA by polymerase chain reaction].

We compared two primer sets (A: 167bp, B: 269bp) derived from highly conserved domains within the 5' noncoding region (5'NC) of the hepatitis C virus (HCV) genome for their ability to detect HCV-RNA in a nested cDNA polymerase chain reaction assay (nested-PCR) in sera from 31 patients suspected of having HCV infection. Seventeen (54%) of 31 patients were positive for HCV-RNA with both primer sets. Using primer set A, 14(93%) of 15 samples with positive and 3(19%) of 16 samples with negative anti-HCV antibody test gave positive results for HCV-RNA. With primer set B, 15(100%) of 15 antibody positive samples and 2(13%) of 16 negative samples were positive for HCV-RNA. One antibody negative sample from a patient with alcoholic liver cirrhosis was positive for HCV-RNA only with primer set A. Another sample with positive antibody test, from a patient with chronic renal failure, was positive for HCV-RNA only with primer set B. A combination of more than one set of primers directed to the highly conserved 5'NC region, as well as proper selection of the exact nucleotide sequences, are important in improving the detection rate of HCV-RNA by PCR in serum of infected patients.

Base Sequence↗

PubMed1993

[Detection of drug resistant-gene in cisplatin-resistant colon carcinoma cells by RT-PCR assay. I].

Expression of the TS and DNA polymerase beta genes as a drug resistant-gene were compared with the human colon carcinoma cell line HCT8S and a subline that was 4.5 fold resistant to cisplatin. Resistant cells (HCT8DDP) exhibited 3.4 fold and 2.5 fold increase in mRNA for both TS and DNA polymerase beta gene when compared with the parent cells by Northern blotting analysis, respectively. The RT (reverse transcription)-PCR (polymerase chain reaction) method has been modified to quantify a sequence of a drug resistance gene. This method exhibited greater sensitivity than conventional methods (Northern blotting analysis), requiring less than 1 fetogram of mRNA from cell lines. The RT-PCR assay could be an effective device in the early detection of resistance to chemotherapy.

Base Sequence↗

PubMed1993

[Estimation of megakaryothrombopoiesis by mean platelet volume in leukemia patients during the course of chemotherapy and patients undergoing bone marrow transplantation].

The mean platelet volume (MPV) was measured in 14 patients with acute leukemia during the course of chemotherapy for remission induction and 21 patients undergoing bone marrow transplantation, in order to assess its usefulness as an indicator for megakaryothrombopoiesis at bone marrow suppression and recovery. In patients with acute leukemia, the MPV fell from 9.7 +/- 0.8 fl to 9.2 +/- 0.4 fl during the myelosuppression, and then it rose transiently to 10.2 +/- 0.5 fl and fell to 9.3 +/- 0.5 fl during recovery of platelet count. Similarly, in patients undergoing bone marrow transplantation, the MPV elevation was followed by the recovery of platelet count. Thus, when engraftment was defined as this MPV elevation, engraftment was confirmed significantly earlier by MPV (19.9 +/- 5.8 days) than by platelet count (24.8 +/- 6.7 days). MPV should be a useful indicator for engraftment or recovery from marrow aplasia in cases of acute leukemia and those of bone marrow transplantation.

Acute Disease↗

PubMed1993

[Detection of drug resistant-genes in cisplatin-resistant colon carcinoma cells by RT-PCR assay. II].

The c-fos, c-Ha-ras and c-myc oncogenes have been proposed to play an important role in DNA synthesis. Expression of c-fos, c-Ha-ras and c-myc genes were compared with the human colon carcinoma cell line HCT8S cells and a subline that was 4.5 resistant to cis-diamminedichloro-platinum (cisplatin). Resistant cells (HCT8DDP) exhibited a 4.0, 2.8 and 1.1 fold in mRNA for these genes when compared with the parent cells by Northern blotting analysis, respectively. The reverse transcription (RT)-PCR method has been demonstrated to quantify a sequence of these oncogenes. This method allowed the detection of gene expression from minimal cells. Thus RT-PCR assay could be an effective device in th early detection of oncogenes to cisplatin-resistance.

Base Sequence↗

PubMed1993

[Detection of methicillin-resistant Staphylococcus aureus by in vitro enzymatic amplification of mecA and femA genes].

In the treatment of methicillin-resistant Staphylococcus aureus (MRSA) infection, rapid detection of MRSA is extremely important. The mecA gene codes the new drug resistant polypeptides called penicillin-binding protein 2a (PBP2a) or 2'(PBP2'), which mediates the clinically relevant resistance to all beta-lactam antibiotics. This gene could be beneficial in the detection of MRSA using the polymerase chain reaction (PCR). However, the identical mecA gene has been found in both coagulase-positive and coagulase-negative Staphylococcus with the appropriate methicillin-resistant phenotype. The second gene related to the expression of methicillin-resistance has been called femA. In this study, we amplified both mecA and femA genes by PCR in 97 strains and 32 clinical specimens. The mecA gene was positive in all 63(100%) MRSA strains and 2(6%) of the 34 methicillin-sensitive Staphylococcus aureus (MSSA) strains. Two strains with the methicillin-sensitive phenotype and the mecA gene resulted in methicillin-resistance when cultured on an agar plate containing 4.5% NaCl. The mecA gene was also present in all 10(100%) coagulase-negative Staphylococcus strains with the methicillin-resistant phenotype. The femA gene was positive in all 97(100%) MRSA and MSSA strains. On the other hand, the femA gene was absent from coagulase -negative Staphylococcus strains with the methicillin-resistant phenotype. Although the mechanism by which the product of femA gene influences the expression of methicillin-resistance is unknown, the gene appears to be restricted only in coagulase-positive Staphylococcus, regardless of methicillin-resistance. In conclusion, in vitro enzymatic amplification of both mecA and femA genes would lead to rapid and definite diagnosis of the MRSA infection.

Base Sequence↗

PubMed1993

[Detection of alterations of dihydrofolate reductase gene in folate-resistant leukemia cells by in vitro enzymatic amplification].

Three methods for analyzing the products of polymerase chain reaction were applied to detect complex alterations of dihydrofolate reductase (DHFR) gene, in order to assess their value in detection of folate-resistance in leukemia cells. A single point mutation in the second position of codon 31, a T-to-C transition, in trimetrexate (TMQ) resistant MOLT-3/TMQ200 cells was detected by either allele-specific oligonucleotide hybridization or restriction pattern of the PCR product. These two analyses allowed us to detect not only the presence of the mutation, but also the amplification of the mutated gene in TMQ-methotrexate (MTX) doubly-resistant MOLT-3/TMQ200-MTX500 cells. The base change was confirmed by direct sequencing method of the PCR product. Using these analyses of the PCR product, the complex alterations of DHFR gene are to be examined in leukemic patient cells.

Base Sequence↗

PubMed1993

MDR1 (multidrug resistance) gene expression in adult acute leukemia: correlations with blast phenotype.

Resistance to multiple chemotherapeutic agents is related to the production of P-glycoprotein, a transmembrane drug efflux pump that is encoded by the multidrug resistance gene (MDR1). To detect low-level or heterogenous expression of the MDR1 gene in acute leukemia, we have developed sensitive, specific and semi-quantitative protocols for measuring levels of MDR1 mRNA, based on the polymerase chain reaction. Using this assay, we screened blasts from 20 patients with untreated adult acute leukemia for evidence of MDR1 gene expression. The level of MDR1 mRNA was normalized to beta 2-microglobulin mRNA and was defined by reference to the highly resistant trimetrexate-selected leukemia cells MOLT-3/TMQ200 (1.80). MDR1 mRNA was observed in 14 out of 20 patients. Higher MDR1 mRNAs were observed in three patients with phenotypes of undifferentiated or minimally differentiated nonlymphocytic acute leukemia, as compared with other types of acute leukemia (0.98 vs. 0.25). In contrast, lower MDR1 mRNAs were found in five patients with acute promyelocytic leukemia, as compared with other types of acute leukemia (0.08 vs. 0.45). These findings suggest that MDR1 gene expression is correlated with the leucocyte differentiation stage of leukemia. MDR1 gene expression may, in part, explain the responsiveness to chemotherapy in these distinct subtypes of acute leukemia.

Acute Disease↗

PubMed1992

Effect of verapamil on the class I major histocompatibility complex antigen expression in K562 chronic myelogenous leukemia cells treated with recombinant human interferon-gamma.

The effects of various compounds which modulated the intracellular signal transduction on the induction of class I major histocompatibility complex (MHC) antigens by recombinant human interferon-gamma (rIFN-gamma) were investigated using K562, chronic myelogenous leukemia cells. Class I or class II MHC antigens were not expressed in untreated K562 cells and rIFN-gamma (600 units/ml) weakly induced class I antigens on the cells. Among the compounds tested, verapamil but not the calcium ionophore A23187 enhanced the rIFN-gamma-induced class I antigen expression at both the surface molecule and mRNA levels and enhancement by verapamil occurred in a dose-dependent manner at non-toxic concentrations examined (approximately 50 microM). Verapamil alone had no inducible effect on MHC antigen expression. Deprivation of Ca2+ in culture medium by ethylene glycol-bis(beta-aminoethyl ether) N,N,N',N'-tetraacetic acid (EGTA) could not cause an enhancement of class I antigen induction by rIFN-gamma. Simultaneous exposure of K562 cells to rIFN-gamma (600 units/ml) and recombinant human tumor necrosis factor (rTNF; 1000 units/ml) in combination with verapamil (50 microM) resulted in a further increase of class I antigens in the cells. The expressions of c-myc oncogene in K562 cells were not changed when the cells were treated with rIFN-gamma (600 units/ml) or verapamil (50 microM), either alone or in combination. These results indicate that verapamil synergistically interacts with rIFN-gamma on the class I antigen induction in K562 cells irrespective of c-myc gene expression and that class I antigen induction in this cell line may not be relevant to calcium influx triggered by IFN-gamma.

1-(5-Isoquinolinesulfonyl)-2-Methylpiperazine↗

PubMed1992

Structure model of core proteins in photosystem I inferred from the comparison with those in photosystem II and bacteria; an application of principal component analysis to detect the similar regions between distantly related families of proteins.

A principal component analysis based on the physico-chemical properties of amino acid residues is developed to assign similar regions between distantly related families of proteins, taking account of the species diversities in respective families. The most important advantage of this analysis should be that it reflects different physico-chemical properties and thus can predict more detailed structural properties, including the transmembrane helices, than the hydropathy analysis. Its first application reconfirms the similarity between the core proteins of photosynthetic reaction center in purple bacteria and those of photosystem II, indicating that the low percentage of identical amino acid residues estimated previously between them is due to much allowance for amino acid substitutions in purple bacteria. The application of this analysis to the core proteins of photosystem I reveals that any of these proteins includes two domains, each showing high similarity to the amino acid sequences of core proteins in photosystem II and purple bacteria. A core structure model of A1 and A2 proteins folded into four layers of sheets of transmembrane helices is proposed to provide a molecular basis for the electron pathway suggested by spectroscopic experiments as well as for the interaction sites with plastocyanin, 9 kDa protein and LHC proteins.

Amino Acid Sequence↗

PubMed1992

The role of folates in the development of methotrexate resistance in human leukemia cell line K562.

The effect of reduced and oxidized folates on the development of methotrexate (MTX) resistance has been examined in human leukemia cell line K562 (K562/S). K562/S cells were made resistant to MTX by soft-agar cloning either in RPMI-1640 medium (K562/MTX-PGA) or in folic-acid-free RPMI-1640 medium containing 10 nM leucovorin (K562/MTX-LV). The optimal concentrations of leucovorin for the growth of K562/S, K562/MTX-PGA and K562/MTX-LV cells were 1 nM, 5 nM and 10 nM respectively. K562/MTX-PGA cells were 24-fold resistant to MTX as noted by impaired MTX transport. In contrast, K562/MTX-LV cells were 26-fold resistant to MTX as noted by gene amplification of dihydrofolate reductase. Furthermore cross-resistance to cytosine arabinoside was only demonstrated in K562/MTX-PGA, while the K562/MTX-LV cells showed no significant cross-resistance to cytosine arabinoside. These results suggest that the type and level of folates used during the development of MTX resistance may play a role in the mechanism for MTX resistance. Leukemia cells that are grown in leucovorin might serve as a model for acquired MTX resistance in vivo.

Cell Cycle↗

PubMed1992

[Frequency of the development of RNA-rich reticulocytes in allogeneic bone marrow transplant recipients].

We measured appearance rates of RNA-rich reticulocytes in 8 patients undergoing allogeneic bone marrow transplantation, using a Sysmex R-1000 reticulocyte counter which utilizes laser flow cytometry. The changes in proportion of RNA-rich reticulocytes (high fluorescence ratio: HFR) and maturation index (MI: HFR + middle fluorescence ratio/low fluorescence ratio) were compared with those of WBC, neutrophil or reticulocyte counts. Engraftment was defined as an HFR of greater than or equal to 5% or a MI of greater than or equal to 15%. Engraftment was confirmed significantly earlier by HFR (13.5 +/- 2.4 days) and MI (13.1 +/- 2.9 days) than by neutrophils (17.1 +/- 3.2 days) or reticulocytes (20.4 +/- 6.2 days). The maturation of reticulocytes would be a useful indicator for engraftment or recovery from marrow aplasia in cases of bone marrow transplantation.

Adolescent↗

PubMed1992

[Diagnostic value of measurement of RNA in platelets by fluorescence flow cytometry].

We analyzed the RNA in platelets by fluorescence flow cytometry after staining with thiazole orange(TO) in whole blood samples from hematologically normal subjects and patients with thrombocytopenia. The percentage of TO-positive platelets and their mean fluorescence channel number in 32 control subjects were 6.2 +/- 2.5% (mean +/- SD) and 6.9 +/- 0.7, respectively. In 11 patients with idiopathic thrombocytopenic purpura, the percentage of fluorescently labeled platelets was significantly elevated (p less than 0.05) to 21.5 +/- 14.3%. By contrast, the proportion of positively stained platelets in 14 patients with thrombocytopenia due to impaired platelet production did not significantly differ from that of the controls, whereas the absolute counts of TO-positive platelets were significantly lowered (p less than 0.05). In both patient groups, the mean fluorescence channel numbers of TO-positive platelets were significantly elevated to 16.1 +/- 16.8 and 6.9 +/- 0.7, respectively (p less than 0.05, 0.005). We conclude that flow cytometric analysis of platelets after staining with TO provides information on the thrombopoietic activity in thrombocytopenic disorders. The main advantages of this method for clinical use are its simplicity and the rapidity.

Blood Platelets↗

PubMed1992

Differential effects of IL-3, GM-CSF and G-CSF in an adult with congenital neutropenia.

Using a methylcellulose culture system, we studied the effects of recombinant human interleukin-3 (IL-3), recombinant human granulocyte-macrophage colony-stimulating factor (GM-CSF), and recombinant human granulocyte colony-stimulating factor (G-CSF) on the growth of myeloid progenitor cells (CFU-C) from an adult patient with congenital neutropenia. The moderate clinical course and the maturation arrest at blast-promyelocyte stage in the marrow differentiated this patient from those described as having Kostmann-type congenital neutropenia. CFU-C growth in bone marrow cells from the patient responded to IL-3 normally in a dose-dependent manner. GM-CSF stimulated only macrophage colony formation in a dose-dependent manner comparable to that in normal subjects. Neither GM-CSF nor G-CSF stimulated any significant granulocyte colony formation. This evidence suggests that the hematopoietic progenitor cells in this patient had the potential for developing CFU-C with IL-3, and that the neutropenia in this patient could be a result of an intrinsic defect in myelopoiesis along a granulocytic pathway responsive to GM-CSF or G-CSF.

Adult↗

PubMed1992

[Rapid diagnosis of tuberculous lymphadenitis by amplification of mycobacterial DNA].

In patients with cervical lymph node swelling, prompt differential diagnosis of tuberculosis leads to an appropriate treatment. A method based on DNA amplification and hybridization for the rapid detection of Mycobacterium tuberculosis was used for demonstrating its specific DNA in cervical lymph nodes biopsied from seven patients. The DNA specific for Mycobacterium tuberculosis was detected in 5 patients. Four of them were histologically diagnosed as tuberculous lymphadenitis. In another case with necrotizing lesions but without granulomatous reactions, culture method subsequently revealed a positive result. In other 2 cases, the diagnosis of tuberculosis was promptly excluded by both this method and conventional methods (histologic diagnosis/direct microscopy). The rapid detection of Mycobacterium tuberculosis by amplification of mycobacterial DNA is helpful particularly in differential diagnosis of cervical lymphadenopathy.

Adolescent↗

PubMed1992

Bone marrow eosinophilia as a prognostic indicator in acute myelogenous leukemia with 8;21 translocation.

The pretreatment characteristics of nine acute myelogenous leukemia (AML) patients with 8;21 translocation were evaluated to assess their value as prognostic indicators. All patients had AML-M2 according to French-American-British classification. The percentage of eosinophils in the bone marrow (EO/BM) correlated negatively with the percentage of blast cells in the peripheral blood (BL/PB) (p less than 0.05) and positively with complete remission duration (p less than 0.01). Three of the six patients with EO/BM under 5% showed aggressive clinical courses complicated with extra marrow lesions, while the patient with the highest EO/BM was the only one who survived for 5 years. These findings suggest that bone marrow eosinophilia could be useful as a prognostic indicator in AML patients with t(8;21).

Adult↗

PubMed1992

[Rapid diagnosis of tuberculosis by amplification of mycobacterial DNA in blood diseases].

In patients with malignant blood disease, infection is the most serious complication. The prompt differential diagnosis of tuberculosis leads to an appropriate treatment. A method based on DNA amplification and hybridization for the rapid detection of Mycobacterium tuberculosis was used to test 10 clinical specimens (sputum, gastric aspirate and pleural effusion) from blood disease patients in whom tuberculosis was suspected. Mycobacterium tuberculosis DNA was detected in 3 specimens, including one which was negative on standard microbiological criteria (microscopy and/or culture). The other 7 specimens with fever or abnormal shadow on a chest X-ray were negative by both our method and the Standard microbiological criteria. Rapid diagnosis of tuberculosis by amplification of mycobacterial DNA in cases of blood disease in clinically useful.

Aged↗

PubMed1991

Antitumor activities of new platinum compounds, DWA2114R, NK121 and 254-S, against human leukemia cells sensitive or resistant to cisplatin.

(R)-(-)-1,1-(2-amino-methylpyrrorodine)-platinum(II) (DWA2114R), cis-1,1-cyclobutanedicarboxylato(2R)-2-methyl-1,4-butanediammin eplatinum(II) (NK121; CI-973) and glycolate-o,-o'-diammine platinum(II) (254-S; NSC375101D) are new platinum compounds developed in Japan. We studied the antitumor effects of these compounds on the cisplatin (cis-diamminedichloroplatinum, DDP)-resistant human leukemia cell line, K562/DDP. K562/DDP cells were 10-fold resistant to DDP, while the cells showed minimal cross-resistance to carboplatin (2.1-fold) and DWA2114R (3.3-fold), and were as sensitive to NK121 (1.6-fold) and 254-S (1.0-fold) as the parent cells. Increases in exposure time of K562 cells to DWA2114R resulted in progressive shifting of the dose-response curve to the left, or more effective cell growth inhibition of the cells. Time dependency indices (ID80 obtained from dose-response curve after 1 hr-exposure of K562 cells to drug followed by 72 hr-culture without drug/ID80 after 24 hr-exposure) of DDP, NK121 and 254-S were 10, 8 and 20, respectively. A multidrug resistant cell-line, MOLT-3/TMQ200, was as sensitive to platinum compounds as the parent MOLT-3 cells. Little or no influence of tumor cell density was observed in the growth inhibition of MOLT-3 or K562 cells induced by these new compounds even if cells were concentrated to a density of 10(8) cells/ml. These results indicate that NK121 and 254-S may overcome the drug resistance developed in the patients after treatment with DDP. The antitumor effect of DWA2114R is more dependent not only on drug-concentration but also on exposure time than that of DDP, suggesting that continuous infusion rather than bolus administration appears the favorable schedule in clinical trials.

Antineoplastic Agents↗