Publications by authors named "Katsumi Higashi"

Although it is known that red blood cell (RBC) parameters and platelet count depend on ethnicity and sex, their reference intervals in healthy Asian populations are limited. The aim of this study was to establish reference intervals for RBC parameters and platelet count for healthy adults in Japan. A total of 750 healthy adults (447 women and 303 men; median age 40 years (18-67 years) at seven Japanese centers who participated in regular medical checkups entered this study.

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In petals of picotee petunia (Petunia hybrida) cultivars, margin-specific post-transcriptional gene silencing (PTGS) of chalcone synthase A (CHSA) inhibits anthocyanin biosynthesis, resulting in marginal white tissue formation. In this study, we found that a low molecular mass compound, fluacrypyrim, inhibits PTGS of CHSA, and we explored the site-specific PTGS mechanism of operation. Fluacrypyrim treatment abolished the picotee pattern and eliminated site-specific differences in the levels of anthocyanin-related compounds, CHSA expression, and CHSA small interfering RNA (siRNA).

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In recent years, the diagnostic and therapeutic approaches for malignant neoplasms have significantly improved. With the development of molecular targeted diagnosis or therapeutic drugs, marked progress has been achieved in predicting the therapeutic effect and the prognosis. In this context, progress in molecular biology and immunological cellular antigen-searching techniques has played an important role.

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Human embryonic stem cells (hESCs) proliferate infinitely and are pluripotent. Only a few reports, however, describe specific and efficient methods to induce hESCs to differentiate into mature blood cells. It is important to determine whether and how these cells, once generated, behave similarly with their in vivo-produced counterparts.

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Autotaxin (ATX) is a tumour cell motility-stimulating factor originally isolated from melanoma cell supernatants. ATX is identical to lysophospholipase D, which produces a bioactive lipid mediator, lysophosphatidic acid (LPA), from lysophosphatidylcholine. ATX is overexpressed in various malignancies, including Hodgkin lymphoma, and ATX may stimulate tumour progression via LPA production.

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Lysophosphatidic acid (LPA) promotes survival, growth, differentiation, and motility in a variety of cell types, and has been reported to act as a cell survival and growth factor in B lymphocytes. Autotaxin (ATX), through its lysophospholipase D activity, generates LPA from lysophosphatidylcholine (LPC). In this study, we investigated the effects of LPA and also the expression of ATX and LPA receptor, in the human pre-B-cell line Nalm-6.

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To provide insights into the mechanisms by which receptors for pathogenic elicitors activate defense signaling, we investigated the duration of cryptogein treatment required for induction of various defense responses including programmed cell death in synchronized tobacco BY-2 cells. Transient cryptogein treatment induced only a rapid and transient phase of oxidative burst and mitogen-activated protein kinase (MAPK) activation. Prolonged production of *O(2)(-) and prolonged activation of MAPKs, as well as accumulation of transcripts of defense-related genes and cell death, required continuous recognition of cryptogein for several hours.

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Studies of carrot embryogenesis have suggested that abscisic acid (ABA) is involved in somatic embryogenesis. A relationship between endogenous ABA and the induction of somatic embryogenesis was demonstrated using stress-induced system of somatic embryos. The embryonic-specific genes C-ABI3 and embryogenic cell proteins (ECPs) were expressed during stress treatment prior to the formation of somatic embryos.

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The molecular links between the cell cycle and defense responses in plants are largely unknown. Using synchronized tobacco BY-2 cells, we analyzed the cell cycle dependence of elicitor-induced defense responses. In synchronized cultured apoaequorin-expressing cells, the increase in cytosolic free Ca2+ induced by a proteinaceous elicitor, cryptogein, was greatly suppressed during the G2 and M phases in comparison with G1 or S phases.

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The molecular links between cell cycle control and the regulation of programmed cell death are largely unknown in plants. Here we studied the relationship between the cell cycle and elicitor-induced cell death using synchronized tobacco BY-2 cells. Flow cytometry and fluorescence microscopy of nuclear DNA, and RNA gel-blot analyses of cell cycle-related genes revealed that the proteinaceous elicitor cryptogein induced cell cycle arrest at the G1 or G2 phase before the induction of cell death.

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Thiopurine S-methyltransferase (TPMT), which exhibits a genetic polymorphism, plays an important role in the metabolism of thiopurine drugs such as mercaptopurine, thioguanine, and azathioprine. To determine the frequency distribution of TPMT activity in 157 Japanese subjects with different TPMT genotypes, ie, TPMT*1/*1 and TPMT*1/*3, the authors measured levels of 6-methylmercaptopurine formed from 6-mercaptopurine in red blood cells lysates by HPLC. The TPMT activities in our Japanese subjects ranged from 11.

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Ca(2+) is the pivotal second messenger for induction of defense responses induced by treatment of pathogen-derived elicitor or microbial infection in plants. However, molecular bases for elicitor-induced generation of Ca(2+) signals (Ca(2+) transients) are largely unknown. We here identified cDNAs for putative voltage-dependent Ca(2+)-permeable channels, NtTPC1A and NtTPC1B, that are homologous to TPC1 (two pore channel) from suspension-cultured tobacco BY-2 cells.

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Ion fluxes and the production of reactive oxygen species (ROS) are early events that follow elicitor treatment or microbial infection. However, molecular mechanisms for these responses as well as their relationship have been controversial and still largely unknown. We here simultaneously monitored the temporal sequence of initial events at the plasma membrane in suspension-cultured tobacco cells (cell line BY-2) in response to a purified proteinaceous elicitor, cryptogein, which induced hypersensitive cell death.

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The transition from vegetative growth to flowering is the most drastic change in plant development. In order to examine the involvement of ethylene in growth transition, we compared the development of ethylene-related mutants, eto1, etr1, ein2-1 and ein3-1, with the wild type (WT) in Arabidopsis thaliana. The ethylene sensitivity of two WT and the mutants is decreased in the following order: eto1 = WT < ein3-1 < ein2-1 = etr1-1.

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Somatic embryogenesis in carrot (Daucus carota) is autonomously inhibited by 4-hydroxybenzyl alcohol (4HBA), which is produced by embryogenic cells. Because somatic embryogenesis is used as a model of zygotic embryogenesis, we assayed for 4HBA in carrot seeds and analyzed the effect of 4HBA on seed formation to determine whether 4HBA is also produced during zygotic embryogenesis. HPLC analysis showed that 4HBA accumulated in flowers and immature and mature fruits, but not in vegetative tissues.

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Article Synopsis
  • Thiopurine S-methyltransferase (TPMT) is crucial for metabolizing thiopurine drugs, and its decreased activity can lead to serious side effects.
  • A high-performance liquid chromatographic (HPLC) assay was developed to measure the conversion of 6-mercaptopurine into 6-methylmercaptopurine in red blood cells.
  • The study found varying TPMT activity levels among healthy individuals, with some showing significantly lower activity linked to specific genetic variants, supporting the need for personalized dosing of thiopurine medications.
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Feline myelodysplastic syndromes (MDS) has been diagnosed in many cats infected with feline leukemia virus, although the pathogenesis of this hematopoietic deficiency has been unclear. In this study, we assayed the bone marrow erythroid colony-forming units (CFU-E) and granulocyte-machrophage CFUs (CFU-GM) to investigate the pathogenesis of feline MDS. The number of CFU-E colonies was decreased in 4 of 7 cats with MDS, and the number of CFU-GM colonies was also decreased in 4 cats.

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Somatic embryogenesis in carrot (Daucus carota L.) is strongly inhibited by certain factors that accumulate in culture medium of high-density cultures of embryogenic cells. We previously identified 4-hydroxybenzyl alcohol (4HBA) as one of the inhibitory factors.

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