The Experts below are selected from a list of 243 Experts worldwide ranked by ideXlab platform

E P Grimsrud - One of the best experts on this subject based on the ideXlab platform.

  • Improvements in the detection and analysis of CF3-containing compounds in the background atmosphere by gas chromatography-high-resolution mass spectrometry
    Journal of Chromatography A, 2000
    Co-Authors: J. A. Culbertson, Jan M. Prins, E P Grimsrud
    Abstract:

    An improved method for the gas chromatography/mass spectrometry analysis of CF3-containing compounds in air is described. This method replaces a GS-Q porous layer open tubular (PLOT) column previously used with a 30 m x 0.32 mm GS-GasPro PLOT column. For this exceedingly volatile set of compounds the GS-GasPro column provides improved peak shapes, better signal-to-noise responses and no coelution of compounds. These improvements have allowed eleven CF3-containing compounds to be detected in background air, including CF4 (FC 14), C2F6 (FC 116), CF3Cl (CFC 13), CF3H (HFC 23), CF3Br (Halon 1301), C3F8 (FC 218), CF3CF2Cl (CFC 115), CF3CHF2 (HFC 125), CF3CH3 (HFC 143a), CF3CH2F (HFC 134a), and CF3CFCl2 (CFC 114a). Three of these compounds have not been previously detected in background air, to our knowledge. Quantitative determinations for each of these compounds in the background atmosphere of Montana are also reported. (C) 2000 Elsevier Science B.V.

  • Detection of CF3-containing compounds in background air by gas chromatography high-resolution mass spectrometry
    Journal of Geophysical Research-Atmospheres, 1998
    Co-Authors: M A Engen, V A Wagner, L J Sears, E P Grimsrud
    Abstract:

    The application of a dual-sector high-resolution mass spectrometer (HRMS) to the detection of several CF3-containing compounds in Earth's atmosphere is described. By this technique, the contents of air samples collected in remote areas surrounding Bozeman, Montana, are introduced to the HRMS by gas chromatography (GC) while the HRMS is tuned to the exact masses of the ions expected in the electron impact ionization of each compound. By the analysis procedure developed here, the mass scale of the instrument is continuously recalibrated during the analysis so that any level of mass resolution that is required for the complete separation of hydrocarbon-based from halocarbon-based ions of the same nominal mass can be selected. Owing to the unusually large ion optic system of the mass spectrometer, high ion throughput to the detector is maintained even when higher levels of mass resolution are selected. By this technique, the sensitive detection of CF4 (CFC-14), CF3Cl (CFC-13), CHF3 (HFC-23), CF3CF2Cl (CFC-115), CF3Br (halon-1301), and CF3CH2F (HFC-134a) in background air samples is demonstrated using essentially all of the major ions that appear in the electron impact mass spectrum of each compound. Most of these compounds are thought to be present in background air at the low parts-per-trillion by volume level. This is one of only two reports, to date, of CHF3 presence in background air. A potential source of this compound is suggested by additional measurements provided here.

M A Engen - One of the best experts on this subject based on the ideXlab platform.

  • Detection of CF3-containing compounds in background air by gas chromatography high-resolution mass spectrometry
    Journal of Geophysical Research-Atmospheres, 1998
    Co-Authors: M A Engen, V A Wagner, L J Sears, E P Grimsrud
    Abstract:

    The application of a dual-sector high-resolution mass spectrometer (HRMS) to the detection of several CF3-containing compounds in Earth's atmosphere is described. By this technique, the contents of air samples collected in remote areas surrounding Bozeman, Montana, are introduced to the HRMS by gas chromatography (GC) while the HRMS is tuned to the exact masses of the ions expected in the electron impact ionization of each compound. By the analysis procedure developed here, the mass scale of the instrument is continuously recalibrated during the analysis so that any level of mass resolution that is required for the complete separation of hydrocarbon-based from halocarbon-based ions of the same nominal mass can be selected. Owing to the unusually large ion optic system of the mass spectrometer, high ion throughput to the detector is maintained even when higher levels of mass resolution are selected. By this technique, the sensitive detection of CF4 (CFC-14), CF3Cl (CFC-13), CHF3 (HFC-23), CF3CF2Cl (CFC-115), CF3Br (halon-1301), and CF3CH2F (HFC-134a) in background air samples is demonstrated using essentially all of the major ions that appear in the electron impact mass spectrum of each compound. Most of these compounds are thought to be present in background air at the low parts-per-trillion by volume level. This is one of only two reports, to date, of CHF3 presence in background air. A potential source of this compound is suggested by additional measurements provided here.

Kyozo Ishikawa - One of the best experts on this subject based on the ideXlab platform.

  • Effects of rhIL-1 alpha, rhIL-1 beta, and rhIL-1 receptor antagonist on erythroid progenitors (CFU-E and BFU-E) in human bone marrow.
    Experimental Hematology, 1995
    Co-Authors: Isao Aoki, Masashi Homori, Kazuhiko Nakahara, Higashi K, Kyozo Ishikawa
    Abstract:

    : Interleukin-1 (IL-1) is known to promote the production of colony-stimulating factor (CSF) and to possess the ability to protect the bone marrow suppression in granulocyte-macrophage (GM) series associated with radiotherapy or chemotherapy. There are conflicting reports concerning the action of IL-1 on erythroid progenitors, however, and no consensus has been established. In the present study, the influences of recombinant human IL-1 alpha (rhIL-1 alpha), rhIL-1 beta, and rhIL-1 receptor antagonist (rhIL-1ra) on erythroid progenitors (colony-forming units-erythroid, CFU-E; and burst-forming units-erythroid, BFU-E) in human bone marrow were studied. rhIL-1 alpha and rhIL-1 beta (1-1000 pg/mL) enhanced the CFU-E and BFU-E growth in human nonadherent (NA) bone marrow cells. rhIL-1 alpha and rhIL-1 beta also stimulated the formation of CFU-E and BFU-E in the NA and T cell-depleted bone marrow fraction. Moreover, rhIL-1 alpha and rhIL-1 beta enhanced the CFU-E and BFU-E in the CD34+ bone marrow cell fraction. These data and the results of limiting dilution analysis indicate that the stimulatory effect of IL-1 may consist of direct actions on erythroid progenitors. The enhancing effect of rhIL-1 alpha and rhIL-1 beta on erythroid progenitors was inhibited by rhIL-1ra. These data suggest that the stimulatory effect of IL-1 on CFU-E and BFU-E is mediated via the IL-1 receptor.

  • Stimulatory effect of human insulin on erythroid progenitors (CFU-E and BFU-E) in human CD34+ separated bone marrow cells and the relationship between insulin and erythropoietin.
    Stem Cells, 1994
    Co-Authors: Isao Aoki, Masashi Homori, Kyozo Ishikawa, M. Taniyama, K. Toyama
    Abstract:

    : Erythropoietin is known to be effective for the treatment of anemia in chronic renal failure, but the efficacy of erythropoietin for anemia in other diseases is not so great. Insulin exerts a growth promoting activity in various kinds of cells. In the present study, the effects of insulin on erythroid progenitors (colony forming units-erythroid, CFU-E; and burst forming units-erythroid, BFU-E) in human bone marrow were examined at various concentrations of recombinant human erythropoietin (rh-Epo) to clarify the relationship between erythropoietin and insulin. Human insulin stimulated the formation of CFU-E and BFU-E in the presence of three concentrations (0.25, 5, and 100 U/ml) of rh-Epo. Stimulatory effects of human insulin on CFU-E and BFU-E were also observed in the nonphagocytic and nonadherent bone marrow fraction (NP-NA fraction) and in the NP-NA and T cell-depleted fraction at each concentration of rh-Epo. Human insulin further stimulated the CFU-E and BFU-E growth in CD34+ separated bone marrow cells. These results indicate that the enhancing effect of human insulin on erythroid progenitors is not mediated through monocytes and macrophages or T cells, suggesting a direct action on erythroid progenitors.

  • Responsiveness of bone marrow erythroid progenitors (CFU-E and BFU-E) to recombinant human erythropoietin (rh-Ep) in vitro in multiple myeloma.
    British Journal of Haematology, 1992
    Co-Authors: Isao Aoki, K Nishijima, Masashi Homori, Kazuhiko Nakahara, Katsumi Higashi, Kyozo Ishikawa
    Abstract:

    : The responsiveness of bone marrow erythroid progenitors (CFU-E and BFU-E) to recombinant human erythropoietin (rh-Ep) was investigated in vitro in 21 patients with multiple myeloma to assess the clinical usefulness of rh-Ep in this disease. CFU-E and BFU-E assays were performed by methylcellulose culture methods. The myeloma patients were divided into two groups according to the percentage of plasma cells in the bone marrow (over 50% and under 50%). Among the patients with few plasma cells, some revealed normal CFU-E and BFU-E growth at 2 units of rh-Ep, and no further increase was observed even with an increasing dose of rh-Ep. Among the other patients, more than half demonstrated a good response to rh-Ep. Among the patients with a high percentage of plasma cells, some revealed no response to rh-Ep, but there were patients with a high percentage of plasma cells in the bone marrow who had a good response to rh-Ep. High doses of rh-Ep may be clinically effective in some patients with multiple myeloma independently of the level of plasma cells in the bone marrow.

  • Effects of ubenimex on erythroid progenitors (CFU-E and BFU-E) in human bone marrow.
    Experimental Hematology, 1991
    Co-Authors: Isao Aoki, K Higashi, K Nishijima, Masashi Homori, H Chikazawa, Kyozo Ishikawa
    Abstract:

    : Ubenimex (UBX, bestatin) is known to be an immunomodulator and host-mediated antineoplastic agent. Effects of UBX on human bone marrow erythroid progenitors (erythroid colony-forming units, CFU-E; and erythroid burst-forming units, BFU-E) were investigated in vitro. UBX enhanced CFU-E and BFU-E growth in the nonseparated bone marrow mononuclear cell fraction at concentrations from 0.005 to 5 micrograms/ml. The enhancements of CFU-E and BFU-E were independent of the concentration of erythropoietin added to culture system. In the T-cell-depleted bone marrow fraction, UBX also increased CFU-E and BFU-E growth, but it failed to stimulate these cells in the nonphagocytic and nonadherent bone marrow fraction. These findings indicate that UBX may stimulate erythroid progenitors mediated through monocytes and macrophages.

  • Responsiveness of bone marrow erythropoietic stem cells (CFU‐E and BFU‐E) to recombinant human erythropoietin (rh‐Ep) in vitro in aplastic anemia and myelodysplastic syndrome
    American Journal of Hematology, 1990
    Co-Authors: Isao Aoki, Masashi Homori, Kyozo Ishikawa, Hiroo Chikazawa, Katsumi Higashi
    Abstract:

    : Responsiveness of bone marrow erythropoietic stem cells (CFU-E and BFU-E) to recombinant human erythropoietin (rh-Ep) was examined in vitro in 23 patients with aplastic anemia and 14 with myelodysplastic syndrome (MDS) to investigate the clinical use of rh-Ep for these diseases. Bone marrow mononuclear cells were cultured by methylcellulose methods for CFU-E and BFU-E assays. In normals, the CFU-E numbers reached a plateau of increase at Ep doses of almost 2-5 units, and no further increase was observed with the addition of larger Ep doses. In aplastic anemia, the responses of CFU-E to Ep were relatively good in nonsevere type and generally poor in severe type. However, the CFU-E numbers increased with increasing doses of Ep in some of the patients with aplastic anemia. Among the patients with MDS, the responses of CFU-E to Ep were relatively good in primary acquired refractory anemia (PARA) and primary acquired sideroblastic anemia. On the other hand, the responses of CFU-E to Ep were poor in refractory anemia with an excess of blasts (RAEB) and RAEB in transformation among the MDS patients. BFU-E responses to Ep were poor in severe aplastic anemia, RAEB, and RAEB-T. However, there are Ep responsive patients in some of aplastic anemia and PARA. High titers of rh-Ep were suggested to be effective clinically in some patients with aplastic anemia and those with PARA.

Amin M Arnaout - One of the best experts on this subject based on the ideXlab platform.

  • differential role of the transcription factor zbp 89 in hemangioblast fate determination zbp 89 is a direct regulator of scl
    Blood, 2007
    Co-Authors: Xiangen Li, C S Shelley, Amin M Arnaout
    Abstract:

    Several molecular pathways have been identified that regulate distinct stages in the developmental progression from mesoderm to the formation of the hematopoietic and vascular lineages. Our previous work indicated that ectopic expression of the zinc finger transcription factor ZBP-89 promotes hematopoietic lineage development and represses endothelial cell lineage differentiation from hemangioblasts in murine embryonic stem cells. Here we evaluated the functional consequences of stable knockdown of ZBP-89 in embryonic stem cells (ESC) on hematopoietic and vascular development. Stable knock down of ZBP-89 in ESC significantly decreased the number of Blast Colony Forming Cells (BL-CFC) hemangioblasts, as well as primitive and definitive hematopoietic progenitor colonies BFU-E, GM-CFU, G-CFU, M-CFU and GEMM-CFU in vitro. In contrast, sprouting angiogenesis was markedly increased in EB cultures. Flow cytometric analysis of the lineages derived from ZBP-89 deficient EB cultures showed that the early (C-kit+Sca-1+) and definitive (CD45+) hematopoietic stem cells populations were reduced, but the endothelial cell population (CD31+ VE-Cadherin+) was increased. RT-PCR analysis of EB cultures revealed a direct correlation between the expression levels of ZBP-89 and hematopoietic markers (including SCL and Runx1) but an inverse correlation with the vascular marker CD31, with no change in Oct4 expression level. To investigate the mechanism underlying the role of ZBP-89 in hematopoiesis, the effect of ZBP-89 on expression of SCL, a master regulator of hematopoiesis, was examined. The murine SCL promoter transduced into the ZBP-89-expressing MEL cell line drove luciferase gene expression. ZBP-89 knockdown in MEL cells markedly reduced SCL expression. ChIP analysis showed that endogenous ZBP-89 protein bound directly to the murine SCL promoter in MEL cells. Thus ZBP-89 plays a central role in fate determination of hemangioblasts; its induction suppresses angiogenesis but enhances differentiation of hemangioblasts along the hematopoietic pathway, an effect mediated through the regulated expression of SCL.

Isao Aoki - One of the best experts on this subject based on the ideXlab platform.

  • Effects of rhIL-1 alpha, rhIL-1 beta, and rhIL-1 receptor antagonist on erythroid progenitors (CFU-E and BFU-E) in human bone marrow.
    Experimental Hematology, 1995
    Co-Authors: Isao Aoki, Masashi Homori, Kazuhiko Nakahara, Higashi K, Kyozo Ishikawa
    Abstract:

    : Interleukin-1 (IL-1) is known to promote the production of colony-stimulating factor (CSF) and to possess the ability to protect the bone marrow suppression in granulocyte-macrophage (GM) series associated with radiotherapy or chemotherapy. There are conflicting reports concerning the action of IL-1 on erythroid progenitors, however, and no consensus has been established. In the present study, the influences of recombinant human IL-1 alpha (rhIL-1 alpha), rhIL-1 beta, and rhIL-1 receptor antagonist (rhIL-1ra) on erythroid progenitors (colony-forming units-erythroid, CFU-E; and burst-forming units-erythroid, BFU-E) in human bone marrow were studied. rhIL-1 alpha and rhIL-1 beta (1-1000 pg/mL) enhanced the CFU-E and BFU-E growth in human nonadherent (NA) bone marrow cells. rhIL-1 alpha and rhIL-1 beta also stimulated the formation of CFU-E and BFU-E in the NA and T cell-depleted bone marrow fraction. Moreover, rhIL-1 alpha and rhIL-1 beta enhanced the CFU-E and BFU-E in the CD34+ bone marrow cell fraction. These data and the results of limiting dilution analysis indicate that the stimulatory effect of IL-1 may consist of direct actions on erythroid progenitors. The enhancing effect of rhIL-1 alpha and rhIL-1 beta on erythroid progenitors was inhibited by rhIL-1ra. These data suggest that the stimulatory effect of IL-1 on CFU-E and BFU-E is mediated via the IL-1 receptor.

  • Stimulatory effect of human insulin on erythroid progenitors (CFU-E and BFU-E) in human CD34+ separated bone marrow cells and the relationship between insulin and erythropoietin.
    Stem Cells, 1994
    Co-Authors: Isao Aoki, Masashi Homori, Kyozo Ishikawa, M. Taniyama, K. Toyama
    Abstract:

    : Erythropoietin is known to be effective for the treatment of anemia in chronic renal failure, but the efficacy of erythropoietin for anemia in other diseases is not so great. Insulin exerts a growth promoting activity in various kinds of cells. In the present study, the effects of insulin on erythroid progenitors (colony forming units-erythroid, CFU-E; and burst forming units-erythroid, BFU-E) in human bone marrow were examined at various concentrations of recombinant human erythropoietin (rh-Epo) to clarify the relationship between erythropoietin and insulin. Human insulin stimulated the formation of CFU-E and BFU-E in the presence of three concentrations (0.25, 5, and 100 U/ml) of rh-Epo. Stimulatory effects of human insulin on CFU-E and BFU-E were also observed in the nonphagocytic and nonadherent bone marrow fraction (NP-NA fraction) and in the NP-NA and T cell-depleted fraction at each concentration of rh-Epo. Human insulin further stimulated the CFU-E and BFU-E growth in CD34+ separated bone marrow cells. These results indicate that the enhancing effect of human insulin on erythroid progenitors is not mediated through monocytes and macrophages or T cells, suggesting a direct action on erythroid progenitors.

  • Responsiveness of bone marrow erythroid progenitors (CFU-E and BFU-E) to recombinant human erythropoietin (rh-Ep) in vitro in multiple myeloma.
    British Journal of Haematology, 1992
    Co-Authors: Isao Aoki, K Nishijima, Masashi Homori, Kazuhiko Nakahara, Katsumi Higashi, Kyozo Ishikawa
    Abstract:

    : The responsiveness of bone marrow erythroid progenitors (CFU-E and BFU-E) to recombinant human erythropoietin (rh-Ep) was investigated in vitro in 21 patients with multiple myeloma to assess the clinical usefulness of rh-Ep in this disease. CFU-E and BFU-E assays were performed by methylcellulose culture methods. The myeloma patients were divided into two groups according to the percentage of plasma cells in the bone marrow (over 50% and under 50%). Among the patients with few plasma cells, some revealed normal CFU-E and BFU-E growth at 2 units of rh-Ep, and no further increase was observed even with an increasing dose of rh-Ep. Among the other patients, more than half demonstrated a good response to rh-Ep. Among the patients with a high percentage of plasma cells, some revealed no response to rh-Ep, but there were patients with a high percentage of plasma cells in the bone marrow who had a good response to rh-Ep. High doses of rh-Ep may be clinically effective in some patients with multiple myeloma independently of the level of plasma cells in the bone marrow.

  • Effects of ubenimex on erythroid progenitors (CFU-E and BFU-E) in human bone marrow.
    Experimental Hematology, 1991
    Co-Authors: Isao Aoki, K Higashi, K Nishijima, Masashi Homori, H Chikazawa, Kyozo Ishikawa
    Abstract:

    : Ubenimex (UBX, bestatin) is known to be an immunomodulator and host-mediated antineoplastic agent. Effects of UBX on human bone marrow erythroid progenitors (erythroid colony-forming units, CFU-E; and erythroid burst-forming units, BFU-E) were investigated in vitro. UBX enhanced CFU-E and BFU-E growth in the nonseparated bone marrow mononuclear cell fraction at concentrations from 0.005 to 5 micrograms/ml. The enhancements of CFU-E and BFU-E were independent of the concentration of erythropoietin added to culture system. In the T-cell-depleted bone marrow fraction, UBX also increased CFU-E and BFU-E growth, but it failed to stimulate these cells in the nonphagocytic and nonadherent bone marrow fraction. These findings indicate that UBX may stimulate erythroid progenitors mediated through monocytes and macrophages.

  • Responsiveness of bone marrow erythropoietic stem cells (CFU‐E and BFU‐E) to recombinant human erythropoietin (rh‐Ep) in vitro in aplastic anemia and myelodysplastic syndrome
    American Journal of Hematology, 1990
    Co-Authors: Isao Aoki, Masashi Homori, Kyozo Ishikawa, Hiroo Chikazawa, Katsumi Higashi
    Abstract:

    : Responsiveness of bone marrow erythropoietic stem cells (CFU-E and BFU-E) to recombinant human erythropoietin (rh-Ep) was examined in vitro in 23 patients with aplastic anemia and 14 with myelodysplastic syndrome (MDS) to investigate the clinical use of rh-Ep for these diseases. Bone marrow mononuclear cells were cultured by methylcellulose methods for CFU-E and BFU-E assays. In normals, the CFU-E numbers reached a plateau of increase at Ep doses of almost 2-5 units, and no further increase was observed with the addition of larger Ep doses. In aplastic anemia, the responses of CFU-E to Ep were relatively good in nonsevere type and generally poor in severe type. However, the CFU-E numbers increased with increasing doses of Ep in some of the patients with aplastic anemia. Among the patients with MDS, the responses of CFU-E to Ep were relatively good in primary acquired refractory anemia (PARA) and primary acquired sideroblastic anemia. On the other hand, the responses of CFU-E to Ep were poor in refractory anemia with an excess of blasts (RAEB) and RAEB in transformation among the MDS patients. BFU-E responses to Ep were poor in severe aplastic anemia, RAEB, and RAEB-T. However, there are Ep responsive patients in some of aplastic anemia and PARA. High titers of rh-Ep were suggested to be effective clinically in some patients with aplastic anemia and those with PARA.