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Biomedical subjects

H Miyachi

Publications and source records attributed to H Miyachi.

At least 109 records · Page 6Linked to original sources
PubMed1991

The influence of tumor cell density on cellular accumulation of doxorubicin or cisplatin in vitro.

The effect of tumor cell density on the cellular pharmacokinetics of doxorubicin (DXR) and cisplatin (CDDP) was studied using MOLT-3 human acute lymphoblastic leukemia cells. As determined by the MTT assay, the growth-inhibitory effect of DXR was approx. 40 times lower when cell density was increased from 10(6) to 10(8) cells/ml (positive inoculum effect), whereas little or no influence of cell density was observed in CDDP-induced cell-growth inhibition. As measured by high-performance liquid chromatography using a fluorescence detector, the cellular accumulation of DXR showed 6- and 18-fold decreases after 1 h incubation when the cells were concentrated from 10(6) to 10(7) and 10(8) cells/ml, respectively. Only at low cell density (10(6) cells/ml) did the amount of DXR in the cells increase with increasing exposure times of up to 6 h. The DXR concentration in the supernatant that was separated from a cell suspension showing a density of 10(8) cells/ml fell to 20% of that obtained at 10(6) cells/ml. The metabolites of DXR, including Adriamycinol and Adriamycinone, were not detectable in the cell extracts or supernatants at any cell density examined. In contrast, the cellular accumulation of CDDP calculated from the platinum concentration, which was measured with a flameless atomic absorption spectrophotometer, was essentially identical at all cell densities examined; moreover, extension of the exposure period resulted in a linear increase in the amount of CDDP in the cells. CDDP concentrations in the supernatants were equally retained, irrespective of cell densities. These observations indicate that the positive inoculum effect shown in DXR-induced cell-growth inhibition results from the decreased cellular accumulation of the drug at high cell densities. We found no influence for cell density on the cellular accumulation of CDDP that might be relevant to the therapeutic potentiation of this drug at high tumor-cell density.

Cell Count↗
PubMed1991

A human leukemia cell line made resistant to two folate analogues, trimetrexate and N10-propargyl-5,8-dideazafolic acid (CB3717).

We established a novel human acute lymphoblastic leukemia cell line made resistant to two folate analogues, trimetrexate (TMQ) and N10-propargyl-5,8-dideazafolic acid (CB3717), by sequential exposure of the 200-fold TMQ-resistant cells (MOLT-3/TMQ200) to CB3717. A 30-fold-resistant subline to CB3717 was selected from the TMQ-resistant cells and designated as MOLT-3/TMQ200-CB371730. This double-folate-resistant cell line was 15-fold more resistant to methotrexate (MTX) than MOLT-3/TMQ200; however, TMQ resistance was decreased to 10-fold as compared to MOLT-3/TMQ200. The doubly resistant cells also showed 2-fold cross-resistance to 5-fluorouracil (5-FU). Equimolar concentrations of leucovorin almost completely reversed the inhibitory effect of MTX on the doubly resistant cells and partially that of CB3717 and TMQ; on the other hand, leucovorin enhanced the inhibitory effect of 5-FU. Thymidylate synthase activities demonstrated little or no difference among these three cell lines, being consistent with no overexpression of mRNA for this enzyme in the doubly resistant cells. MOLT-3/TMQ200 cells displayed classical multidrug resistance; sequential development of CB3717 resistance in the TMQ-resistant cells resulted in an enhancement of the multidrug-resistance phenotype and a concomitant increase of MDR1 mRNA. The development of a complex resistance pattern seen in this double-folate-resistant subline indicates intricacy in the study of drug resistance after multidrug chemotherapy.

ATP Binding Cassette Transporter, Subfamily B, Mem↗
PubMed1991

Clinical heterogeneity in acute myelogenous leukemia with the 8;21 translocation.

Nine acute myelogenous leukemia(AML) patients with a translocation 8;21, who were treated at Keio University Hospital between 1983 and August 1990, were reviewed. All of them were classified into AML-M2 subtype of the French-American-British classification. It formed 43% of all M2 cases. The patients' mean age was 47 years. Neutrophil alkaline phosphatase score was lower than normal and complete remission(CR) was achieved in all cases. In statistical analysis, patients with the t(8;21) showed a longer CR duration and a higher percentage of eosinophils than the other AML-M2 patients without this karyotype (p less than 0.05, p less than 0.01, respectively). As an additional chromosomal abberation, two patients showed a loss of Y chromosome at first diagnosis and another patient did a deletion of 12p at the 3rd relapse and an elongation of 20q in addition to the 12p- at the 4th relapse. Although patients with the t(8;21) are regarded as a favorable group in respect of survival, we found a subset of patients who had poor prognosis. Some of them were accompanied with solid tumor formation. Only one patient has lived longer than 5 years. These findings suggest that AML with the t(8;21) is clinically heterogenous.

Adult↗
PubMed1991

[An evaluation of automated hematology analyzers in detecting abnormal blood cells].

We report the usefulness and capability of two hematology analyzers with different principles in characterization of abnormal cells such as immature granulocytes and blasts. We studied a total 1635 specimens which included 69 cases with hematopoietic malignancies. THMS H-1 (Technicon Instruments) and NE-8000 (Toa Instruments) were used as analyzers. An effort was made to determine the sensitivity and specificity of positive abnormal cell flag in comparison with the presence of abnormal cells seen on a manual differential. True positive rate for immature granulocytes in H-1 and NE were 43% and 30%, respectively. False positive rate for immature granulocytes in H-1 and NE were 0.01% and 0.03%, respectively. With both analysers, cases with low percentage of immature granulocytes generated negative flag for abnormal cells. True positive rate for blasts in H-1 and NE were 74% and 65%, respectively. False positive rate for blasts in H-1 and NE were 1.8% and 0.2%, respectively. With both instruments, in all cases with blast count over 100/microliters, blasts were detected. Only H-1 detected the cases with blast counts less than 100/microliters. In H-1 all cases with ATL, one case with AMMoL and another with ALL generated negative blast flag. Upon morphologic examination, these blasts were found to be large and peroxidase negative with convoluted and irregularly shaped nuclei. On the other hand, NE detected blasts regardless of those morphology. In conclusion, Both instruments are useful in screening abnormal blood cells, while their unique capability must be considered.

Autoanalysis↗
PubMed1990

Heat radiosensitization and the level of DNA polymerases alpha and beta of human colony-forming unit-granulocyte-macrophage and myeloid leukemias sensitive and resistant to chemotherapeutic agents.

In these studies, heat radiosensitization in normal human colony-forming unit-granulocyte-macrophage (CFU-GM) and several different leukemic cell lines sensitive or resistant to chemotherapeutic agents were measured. Extent of heat radiosensitization was then correlated with the level of DNA polymerases alpha and beta in control and heat-shocked cells in order to examine whether there is a positive correlation between the degree of heat radiosensitization and the level of these enzymes. Our results show that human bone marrow CFU-GM have an x-ray response with D0 of 1.56 Gy and a small amount of heat radiosensitization with a thermal enhancement ratio (TER) of 1.2. K562, a human erythroleukemic cell, showed a D0 of 1.32 +/- 0.2 Gy and TER of 1.4. However, in contrast to normal CFU-GM which showed no shoulder in the X-ray survival curve, K562 cells showed a small shoulder with a quasi-threshold dose, (Dq) of 2 Gy and n of 2. K562 cells resistant to chemotherapeutic drugs such as 1-beta-D-arabinofuranosylcytosine and etoposide (VP-16) showed D0 of 1.47 +/- 0.13, and 1.77 +/- 0.18 Gy; Dq of 4 and 0 Gy; and n of 5 and 1; and TER of 1.6 and 2, respectively. The level of DNA polymerases alpha and beta activity and their respective mRNA levels were approximately the same in all cells. The reduction in the level of DNA polymerase beta after heat treatment however, correlated with the TER obtained for various leukemic cells. These studies indicate that normal CFU-GM and variety of human leukemic cells show only a small amount of heat radiosensitization. However, drug-resistant leukemic cells show a higher amount of heat radiosensitization than their drug-sensitive parent line. This suggests that hyperthermia may be beneficial in eradicating drug-resistant leukemic cells when combined with X-ray. Furthermore, the inactivation of DNA polymerase beta activity results in a higher amount of heat radiosensitization.

Blotting, Northern↗
PubMed1988

Detection of drug resistance in human tumors by in vitro enzymatic amplification.

Both acquired and natural resistance to chemotherapy agents have proved problematic in the treatment of neoplasia. Thymidylate synthase, which catalyzes the synthesis of thymidine precursors, has been shown to be amplified in response to a variety of chemotherapeutic agents. The detection of such amplification could prove beneficial in the development of alternative clinical protocols. In this study we report the use of existing enzymatic amplification methods in order to detect incipient amplification of the thymidylate synthase gene upon resistance to cisplatin. The assay utilizes a modification of the polymerase chain reaction in which a sequence of the thymidylate synthase gene is amplified including two flanking oligonucleotides acting as primers for DNA synthesis. This method exhibits greater sensitivity than conventional nucleic acid detection methods and requires less than 100 ng of total RNA from patient tumors and no in vitro culturing of patient cells.

Cell Line↗
PubMed1987

Hypertrophic osteoarthropathy, cutaneous vasculitis, and mixed-type cryoglobulinemia in a patient with nasopharyngeal carcinoma.

We describe a 27-year-old woman with a primary nasopharyngeal carcinoma who developed hypertrophic osteoarthropathy and cutaneous vasculitis. Her serum contained antibodies to Epstein-Barr virus and U1 RNP antigens. Cryoproteins isolated from her serum contained antibodies to U1 RNP and a protein with a molecular weight of 32 kd which reacted specifically with antibodies to U1 RNP. HLA typing revealed HLA-B7 and DR1; these have been reported to be increased in Japanese patients with rheumatic diseases who have autoantibodies to U1 RNP. These findings indicate that some features of the paraneoplastic syndrome in this patient might have been caused by immune complexes, part of which were formed by specific autoantibodies produced under genetically controlled conditions of immune responsiveness.

Adult↗