The Experts below are selected from a list of 20256 Experts worldwide ranked by ideXlab platform
Michael B Kastan - One of the best experts on this subject based on the ideXlab platform.
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development of a cell based high throughput screening assay for atm kinase inhibitors
Journal of Biomolecular Screening, 2014Co-Authors: Kexiao Guo, Michael B Kastan, Anang A Shelat, Kiplin R GuyAbstract:The ATM (ataxia-telangiectasia, mutated) protein kinase is a major regulator of cellular responses to DNA double-strand breaks (DSBs), DNA lesions that can be caused by Ionizing Irradiation (IR), oxidative damage, or exposure to certain chemical agents. In response to DSBs, the ATM kinase is activated and subsequently phosphorylates numerous downstream substrates, including p53, Chk2, BRCA1, and KAP1, which affect processes such as cell cycle progression and DNA repair. Numerous studies have demonstrated that loss of ATM function results in enhanced sensitivity to Ionizing Irradiation in clinically relevant dose ranges, suggesting that ATM kinase is an attractive therapeutic target for enhancing tumor cell kill with radiotherapy. Previously identified small-molecule ATM kinase inhibitors, such as CP466722 and Ku55933, were identified using in vitro kinase assays carried out with recombinant ATM kinase isolated from mammalian cells. Since it has not been feasible to express full-length recombinant ATM in bacterial or baculovirus systems, a robust in vitro screening tool has been lacking. We have developed a cell-based assay that is robust, straightforward, and sensitive. Using this high-throughput assay, we screened more than 7000 compounds and discovered additional small molecules that inhibit the ATM kinase and further validated these hits by secondary assays.
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a novel atm dependent pathway regulates protein phosphatase 1 in response to dna damage
Molecular and Cellular Biology, 2008Co-Authors: Xi Tang, Zhouguang Hui, Xiaoli Cui, Renu Garg, Michael B KastanAbstract:Protein phosphatase 1 (PP1), a major protein phosphatase important for a variety of cellular responses, is activated in response to Ionizing Irradiation (IR)-induced DNA damage. Here, we report that IR induces the rapid dissociation of PP1 from its regulatory subunit inhibitor-2 (I-2) and that the process requires ataxia-telangiectasia mutated (ATM), a protein kinase central to DNA damage responses. In response to IR, ATM phosphorylates I-2 on serine 43, leading to the dissociation of the PP1-I-2 complex and the activation of PP1. Furthermore, ATM-mediated I-2 phosphorylation results in the inhibition of the Aurora-B kinase, the down-regulation of histone H3 serine 10 phosphorylation, and the activation of the G2/M checkpoint. Collectively, the results of these studies demonstrate a novel pathway that links ATM, PP1, and I-2 in the cellular response to DNA damage.
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involvement of the cohesin protein smc1 in atm dependent and independent responses to dna damage
Genes & Development, 2002Co-Authors: Seongtae Kim, Michael B KastanAbstract:Structural maintenance of chromosomes (SMC) proteins play important roles in sister chromatid cohesion, chromosome condensation, sex-chromosome dosage compensation, and DNA recombination and repair. Protein complexes containing heterodimers of the Smc1 and Smc3 proteins have been implicated specifically in both sister chromatid cohesion and DNA recombination. Here, we show that the protein kinase, Atm, which belongs to a family of phosphatidylinositol 3-kinases that regulate cell cycle checkpoints and DNA recombination and repair, phosphorylates Smc1 protein after Ionizing Irradiation. Atm phosphorylates Smc1 on serines 957 and 966 in vitro and in vivo, and expression of an Smc1 protein mutated at these phosphorylation sites abrogates the Ionizing Irradiation-induced S phase cell cycle checkpoint. Optimal phosphorylation of these sites in Smc1 after Ionizing Irradiation also requires the presence of the Atm substrates Nbs1 and Brca1. These same sites in Smc1 are phosphorylated after treatment with UV Irradiation or hydroxyurea in an Atm-independent manner, thus demonstrating that another kinase must be involved in responses to these cellular stresses. Yeast containing hypomorphic mutations in SMC1 and human cells overexpressing Smc1 mutated at both of these phosphorylation sites exhibit decreased survival following Ionizing Irradiation. These results demonstrate that Smc1 participates in cellular responses to DNA damage and link Smc1 to the Atm signal transduction pathway.
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involvement of brca1 in s phase and g 2 phase checkpoints after Ionizing Irradiation
Molecular and Cellular Biology, 2001Co-Authors: Seongtae Kim, Michael B KastanAbstract:Cell cycle arrests in the G(1), S, and G(2) phases occur in mammalian cells after Ionizing Irradiation and appear to protect cells from permanent genetic damage and transformation. Though Brca1 clearly participates in cellular responses to Ionizing radiation (IR), conflicting conclusions have been drawn about whether Brca1 plays a direct role in cell cycle checkpoints. Normal Nbs1 function is required for the IR-induced S-phase checkpoint, but whether Nbs1 has a definitive role in the G(2)/M checkpoint has not been established. Here we show that Atm and Brca1 are required for both the S-phase and G(2) arrests induced by Ionizing Irradiation while Nbs1 is required only for the S-phase arrest. We also found that mutation of serine 1423 in Brca1, a target for phosphorylation by Atm, abolished the ability of Brca1 to mediate the G(2)/M checkpoint but did not affect its S-phase function. These results clarify the checkpoint roles for each of these three gene products, demonstrate that control of cell cycle arrests must now be included among the important functions of Brca1 in cellular responses to DNA damage, and suggest that Atm phosphorylation of Brca1 is required for the G(2)/M checkpoint.
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dna damage induces phosphorylation of the amino terminus of p53
Genes & Development, 1997Co-Authors: Janet D Siliciano, Ettore Appella, Christine E Canman, Yoichi Taya, Kazuyasu Sakaguchi, Michael B KastanAbstract:Data are presented demonstrating that DNA damage leads to specific post-translational modifications of p53 protein. Using two-dimensional peptide mapping of in vivo radiolabeled p53 tryptic phosphopeptides, recombinant truncated p53 protein, and synthetic p53 tryptic peptides, a unique p53 phosphopeptide was identified after exposure of ML-1 cells to Ionizing Irradiation. This peptide represents the first 24 amino acids of p53 and contains three phosphorylated serine residues. A specific p53 phosphopeptide antibody identified serine-15 as one of the two serines in p53 that becomes phosphorylated following DNA damage induced by either Ionizing Irradiation (IR) or ultraviolet (UV) Irradiation in multiple cell types. IR-induced phosphorylation of p53 does not affect the kinetics of p53 binding to or dissociating from DNA as assessed by electrophoretic mobility-shift assays. However, p53 phosphorylation induced by DNA damage correlates with enhanced transcription of downstream p53 target genes. Low levels of phosphoserine-15 p53 are detectable within 6 hr after IR in AT cells, whereas lymphoblasts from normal individuals exhibit this modification within 1 hr. In contrast, phosphorylation of p53 on serine-15 is similar in normal and AT cells after UV Irradiation. Our results indicate that p53 is phosphorylated in response to DNA damage, that this de novo phosphorylation may be involved in the subsequent induction and activation of p53, and that although ATM affects the kinetics of p53 phosphorylation after IR, it is not absolutely required for phosphorylation of p53 on serine-15.
Joel S. Greenberger - One of the best experts on this subject based on the ideXlab platform.
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radioprotection in vitro and in vivo by minicircle plasmid carrying the human manganese superoxide dismutase transgene
Human Gene Therapy, 2008Co-Authors: Xichen Zhang, Michael W. Epperly, Darcy Franicola, Mark A Kay, Zhiying Chen, Tracy Dixon, Benjamin A Greenberger, Paavani Komanduri, Joel S. GreenbergerAbstract:Abstract Manganese superoxide dismutase plasmid liposomes (MnSOD-PL) confer organ-specific in vivo Ionizing Irradiation protection. To prepare for potential intravenous clinical trials of systemic MnSOD-PL for radioprotection in humans, plasmid and bacterial sequences were removed and a new minicircle construct was tested. Minicircle MnSOD was purified and then cotransfected into 32D cl 3 murine interleukin-3-dependent hematopoietic progenitor cells along with another plasmid carrying the neo gene. Cells were selected in G418 (50 μg/ml) and cloned by limiting dilution. Biochemical analysis of minicircle MnSOD-transfected cells showed an MnSOD biochemical activity level of 5.8 ± 0.5 U/mg compared with 2.7 ± 0.1 U/mg for control 32D cl 3 cells (p = 0.0039). 32D-mc-MnSOD cells were as radioresistant as full-length MnSOD-PL transgene-expressing 2C6 cells, relative to 32D cl 3 parent cells, with an increased shoulder on the radiation survival curve (\documentclass{aastex}\usepackage{amsbsy}\usepackage{amsfonts...
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neuronal mitochondrial nitric oxide synthase homologous deletion recombinant negative mice nos1 long term bone marrow cultures ltbmcs demonstrate increased longevity and radioresistance of derived cell lines
Blood, 2006Co-Authors: Michael W. Epperly, Shaonan Cao, Darcy Franicola, Hongmei Shen, Emily E. Greenberger, Laura D. Epperly, Joel S. Greenberger, Xichen ZhangAbstract:Neuronal NOS (NOS1) is localized to mitochondria. Ionizing Irradiation results in influx of calcium into mitochondria stimulating production of nitric oxide (NO), and also increases production of superoxide which reacts with NO to produce peroxynitrite. Peroxidation of mitochondrial lipids, release of cytochrome C and apoptosis is directly related to mitochondrial peroxynitrite. We hypothesized that reduction of mitochondrial NO production should provide radioresistance. In addition, since ROS production is associated with aging NOS1−/− mouse LTBMCs should demonstrate greater hematopoietic longevity. LTBMCs established from NOS1 −/− mice demonstrated increased cumulative adherent cobblestone islands (adherent stem cell containing islands), production of total nonadherent cells, and cumulative day 7 and day 14 CFU-GEMM hematopoietic multi-lineage colony forming cells (over 65 weeks) compared to NOS1 +/+ controls (22 weeks) (p
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hematopoietic progenitor cell line 32d cl 3 and squamous cancer cell line scc vii are sensitized to Ionizing Irradiation by thalidomide
Cancer Research, 2006Co-Authors: Emily E. Greenberger, Michael W. Epperly, Xichen Zhang, Darcy Franicola, Samuel A Jacobs, Joel S. GreenbergerAbstract:Proc Amer Assoc Cancer Res, Volume 47, 2006 4395 Thalidomide (TL) has been used in the treatment of multiple myeloma and due to its anti-angiogenic effects has been postulated to be a potential radiosensitizer for squamous cancers in vivo. We first investigated the effect of TL on growth of IL-3 dependent murine hematopoietic 32D cl 3 cells in semisolid methylcellulose containing medium also supplemented with TL ranging from 0 to 200 μM. The cells were incubated at 37°C for 7 days at which time colonies of greater than 50 cells were counted. TL increased cell colony formation 2-fold over the dose range of 10 to 100 μM. In serially decreasing concentrations of IL-3, TL (50 μM) was growth stimulatory of 32D cl 3 colony formation in 15% IL-3 and 10% IL-3 conditioned medium (146.2 ± 7.2 and 89.3 ± 2.4 colonies/500 cells plated in TL vs. 110.8 ± 11.4 and 58.0 ± 2.1 without TL, p = 0.0304 or 0.0006). To determine whether TL was a radiosensitizer, cells were placed in: 0, 50, or 150 μM TL in three protocols: 1) 1 hour before Irradiation; 2) 1 hour before Irradiation plus also in methylcellulose following Irradiation; or 3) were placed in TL containing methylcellulose only following Irradiation. Cells were irradiated to doses ranging from 0 to 800 cGy and plated in methylcellulose containing medium. Seven days later, colonies of greater than 50 cells were counted and analyzed by single hit, multi-target or linear quadratic models. Cells grown in 50 μM TL which stimulated cell growth resulted in an increased radiation resistance compared to control irradiated cells (D = 1.87 ± 0.02 vs. 1.30 ± 0.09 Gy, respectively, p = 0.0366). However, 150 μM TL (which did not stimulate cell growth) increased radiation sensitivity compared to control irradiated cells (D = 1.22 ± 0.5 vs. 1.64 ± 0.11 Gy, respectively, p = 0.0245). To determine whether TL radiosensitized tumor cells in the therapeutic 150 μM range, SSC-VII murine squamous cell carcinoma cells were grown in TL at concentrations ranging from 0 to 200 μM and were assayed for colony formation. In contrast, SSC-VII cells showed no detectable stimulation or inhibition of cell growth for unirradiated cells in any concentration of TL. However, at 150 μM TL, SSC-VII cells were radiosensitive when incubated in TL before Irradiation compared to control irradiated cells (D = 2.02 vs. 2.55 Gy, respectively). Thus, thalidomide may be a clinically valuable radiosensitizer.
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plasmid liposome transfer of the human manganese superoxide dismutase transgene prevents Ionizing Irradiation induced apoptosis in human esophagus organ explant culture
International Journal of Cancer, 2000Co-Authors: Michael W. Epperly, Christine A Sikora, S J Defilippi, J Bray, Gary Koe, Denny Liggitt, James D Luketich, Joel S. GreenbergerAbstract:Esophagitis is a major limiting factor in the treatment of lung cancer by radiation alone or in combination with chemotherapy. We have previously demonstrated that intraesophageal injection of manganese superoxide dismutase–plasmid/liposome (MnSOD–PL) complex into C3H/HeNsd mice blocks Irradiation-induced esophagitis. To determine whether the human esophagus can be similarly transfected, normal human esophageal sections obtained from the margins of esophagectomy specimens from esophageal cancer patients were transfected in vitro with alkaline phosphatase (AlkP)–PL complex and stained for AlkP activity, and the percent of cells expressing AlkP was calculated. At 24 hr after transfection with 20 or 200 μg of AlkP–PL complex, 55.0% and 85.8% of esophageal epithelial cells expressed detectable AlkP, respectively. Other sections transfected with MnSOD–PL complex showed transgene mRNA by nested reverse transcriptase-polymerase chain reaction (RT-PCR) assay and increased MnSOD biochemical activity for at least 96 hr after transfection. Irradiated MnSOD–PL complex–transfected sections demonstrated a significantly decreased percentage of apoptotic cells when compared to irradiated control sections. Following 1,000 cGy, MnSOD–PL-treated samples showed 7.5 ± 2.8% and 33.3 ± 7.3% apoptotic cells at 24 and 48 hr compared to 53.6 ± 6.9% and 59.0 ± 13.8% for nontransfected controls (P < 0.0001 and P < 0.1175). After 2,000 cGy, results at 24 and 48 hr were 25.0 ± 7.6% and 66.9 ± 4.9% for MnSOD-transfected sections compared to 65.6 ± 4.3% and 90.0 ± 4.1% for control sections (P < 0.0001 and P = 0.0353), respectively. Thus, human esophageal sections can be transfected with MnSOD–PL complex in vitro and thereby protected against Ionizing Irradiation-induced apoptosis. Int. J. Cancer (Radiat. Oncol. Invest.) 90, 128–137 (2000). © 2000 Wiley-Liss, Inc.
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prevention of late effects of Irradiation lung damage by manganese superoxide dismutase gene therapy
Gene Therapy, 1998Co-Authors: Michael W. Epperly, J Bray, S Kraeger, Ralf M Zwacka, John F Engelhardt, Elizabeth L Travis, Joel S. GreenbergerAbstract:Organ and tissue damage caused by Ionizing Irradiation is directly related to volume irradiated, total dose and dose rate. The acute effects are in part mediated by cellular activation of early response genes, including those for transcriptional activators of genes for humoral cytokines. In the lung, as in other organs, recovery from the acute effects of Ionizing Irradiation does not always correlate with prevention of the critical fate effects, including fibrosis, which contribute to organ failure. An interventional technique by which to protect normal organs from the late effects of Irradiation has remained elusive. We now demonstrate that overexpression of a transgene for human manganese superoxide dismutase (MnSOD) delivered by plasmid-liposome, or adenovirus to the lungs of C57BL/6J or Nu/J mice, respectively, before Irradiation exposure, decreases the late effects of whole lung Irradiation (organizing alveolitis/fibrosis). These data provide a rational basis for the design of gene therapy approaches to organ protection from Irradiation damage.
Michael M C Lai - One of the best experts on this subject based on the ideXlab platform.
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hepatitis c virus ns3 4a protein interacts with atm impairs dna repair and enhances sensitivity to Ionizing radiation
Virology, 2008Co-Authors: Chaokuen Lai, Kingsong Jeng, Keigo Machida, Yisheng Cheng, Michael M C LaiAbstract:Hepatitis C virus (HCV) infection is frequently associated with the development of hepatocellular carcinomas and non-Hodgkin's B-cell lymphomas. Nonstructural protein 3 (NS3) of HCV possesses serine protease, nucleoside triphosphatase, and helicase activities, while NS4A functions as a cofactor for the NS3 serine protease. Here, we show that HCV NS3/4A interacts with the ATM (ataxia-telangiectasia mutated), a cellular protein essential for cellular response to Irradiation. The expression of NS3/4A caused cytoplasmic translocation of either endogenous or exogenous ATM and delayed dephosphorylation of the phosphorylated ATM and γ-H2AX following Ionizing Irradiation. As a result, the Irradiation-induced γ-H2AX foci persisted longer in the NS3/4A-expressing cells. Furthermore, these cells showed increased comet tail moment in single-cell electrophoresis assay, indicating increased double-strand DNA breaks. The cells harboring an HCV replicon also exhibited cytoplasmic localization of ATM and increased sensitivity to Irradiation. These results demonstrate that NS3/4A impairs the efficiency of DNA repair by interacting with ATM and renders the cells more sensitive to DNA damage. This effect may contribute to HCV oncogenesis.
Michael W. Epperly - One of the best experts on this subject based on the ideXlab platform.
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radioprotection in vitro and in vivo by minicircle plasmid carrying the human manganese superoxide dismutase transgene
Human Gene Therapy, 2008Co-Authors: Xichen Zhang, Michael W. Epperly, Darcy Franicola, Mark A Kay, Zhiying Chen, Tracy Dixon, Benjamin A Greenberger, Paavani Komanduri, Joel S. GreenbergerAbstract:Abstract Manganese superoxide dismutase plasmid liposomes (MnSOD-PL) confer organ-specific in vivo Ionizing Irradiation protection. To prepare for potential intravenous clinical trials of systemic MnSOD-PL for radioprotection in humans, plasmid and bacterial sequences were removed and a new minicircle construct was tested. Minicircle MnSOD was purified and then cotransfected into 32D cl 3 murine interleukin-3-dependent hematopoietic progenitor cells along with another plasmid carrying the neo gene. Cells were selected in G418 (50 μg/ml) and cloned by limiting dilution. Biochemical analysis of minicircle MnSOD-transfected cells showed an MnSOD biochemical activity level of 5.8 ± 0.5 U/mg compared with 2.7 ± 0.1 U/mg for control 32D cl 3 cells (p = 0.0039). 32D-mc-MnSOD cells were as radioresistant as full-length MnSOD-PL transgene-expressing 2C6 cells, relative to 32D cl 3 parent cells, with an increased shoulder on the radiation survival curve (\documentclass{aastex}\usepackage{amsbsy}\usepackage{amsfonts...
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neuronal mitochondrial nitric oxide synthase homologous deletion recombinant negative mice nos1 long term bone marrow cultures ltbmcs demonstrate increased longevity and radioresistance of derived cell lines
Blood, 2006Co-Authors: Michael W. Epperly, Shaonan Cao, Darcy Franicola, Hongmei Shen, Emily E. Greenberger, Laura D. Epperly, Joel S. Greenberger, Xichen ZhangAbstract:Neuronal NOS (NOS1) is localized to mitochondria. Ionizing Irradiation results in influx of calcium into mitochondria stimulating production of nitric oxide (NO), and also increases production of superoxide which reacts with NO to produce peroxynitrite. Peroxidation of mitochondrial lipids, release of cytochrome C and apoptosis is directly related to mitochondrial peroxynitrite. We hypothesized that reduction of mitochondrial NO production should provide radioresistance. In addition, since ROS production is associated with aging NOS1−/− mouse LTBMCs should demonstrate greater hematopoietic longevity. LTBMCs established from NOS1 −/− mice demonstrated increased cumulative adherent cobblestone islands (adherent stem cell containing islands), production of total nonadherent cells, and cumulative day 7 and day 14 CFU-GEMM hematopoietic multi-lineage colony forming cells (over 65 weeks) compared to NOS1 +/+ controls (22 weeks) (p
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hematopoietic progenitor cell line 32d cl 3 and squamous cancer cell line scc vii are sensitized to Ionizing Irradiation by thalidomide
Cancer Research, 2006Co-Authors: Emily E. Greenberger, Michael W. Epperly, Xichen Zhang, Darcy Franicola, Samuel A Jacobs, Joel S. GreenbergerAbstract:Proc Amer Assoc Cancer Res, Volume 47, 2006 4395 Thalidomide (TL) has been used in the treatment of multiple myeloma and due to its anti-angiogenic effects has been postulated to be a potential radiosensitizer for squamous cancers in vivo. We first investigated the effect of TL on growth of IL-3 dependent murine hematopoietic 32D cl 3 cells in semisolid methylcellulose containing medium also supplemented with TL ranging from 0 to 200 μM. The cells were incubated at 37°C for 7 days at which time colonies of greater than 50 cells were counted. TL increased cell colony formation 2-fold over the dose range of 10 to 100 μM. In serially decreasing concentrations of IL-3, TL (50 μM) was growth stimulatory of 32D cl 3 colony formation in 15% IL-3 and 10% IL-3 conditioned medium (146.2 ± 7.2 and 89.3 ± 2.4 colonies/500 cells plated in TL vs. 110.8 ± 11.4 and 58.0 ± 2.1 without TL, p = 0.0304 or 0.0006). To determine whether TL was a radiosensitizer, cells were placed in: 0, 50, or 150 μM TL in three protocols: 1) 1 hour before Irradiation; 2) 1 hour before Irradiation plus also in methylcellulose following Irradiation; or 3) were placed in TL containing methylcellulose only following Irradiation. Cells were irradiated to doses ranging from 0 to 800 cGy and plated in methylcellulose containing medium. Seven days later, colonies of greater than 50 cells were counted and analyzed by single hit, multi-target or linear quadratic models. Cells grown in 50 μM TL which stimulated cell growth resulted in an increased radiation resistance compared to control irradiated cells (D = 1.87 ± 0.02 vs. 1.30 ± 0.09 Gy, respectively, p = 0.0366). However, 150 μM TL (which did not stimulate cell growth) increased radiation sensitivity compared to control irradiated cells (D = 1.22 ± 0.5 vs. 1.64 ± 0.11 Gy, respectively, p = 0.0245). To determine whether TL radiosensitized tumor cells in the therapeutic 150 μM range, SSC-VII murine squamous cell carcinoma cells were grown in TL at concentrations ranging from 0 to 200 μM and were assayed for colony formation. In contrast, SSC-VII cells showed no detectable stimulation or inhibition of cell growth for unirradiated cells in any concentration of TL. However, at 150 μM TL, SSC-VII cells were radiosensitive when incubated in TL before Irradiation compared to control irradiated cells (D = 2.02 vs. 2.55 Gy, respectively). Thus, thalidomide may be a clinically valuable radiosensitizer.
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plasmid liposome transfer of the human manganese superoxide dismutase transgene prevents Ionizing Irradiation induced apoptosis in human esophagus organ explant culture
International Journal of Cancer, 2000Co-Authors: Michael W. Epperly, Christine A Sikora, S J Defilippi, J Bray, Gary Koe, Denny Liggitt, James D Luketich, Joel S. GreenbergerAbstract:Esophagitis is a major limiting factor in the treatment of lung cancer by radiation alone or in combination with chemotherapy. We have previously demonstrated that intraesophageal injection of manganese superoxide dismutase–plasmid/liposome (MnSOD–PL) complex into C3H/HeNsd mice blocks Irradiation-induced esophagitis. To determine whether the human esophagus can be similarly transfected, normal human esophageal sections obtained from the margins of esophagectomy specimens from esophageal cancer patients were transfected in vitro with alkaline phosphatase (AlkP)–PL complex and stained for AlkP activity, and the percent of cells expressing AlkP was calculated. At 24 hr after transfection with 20 or 200 μg of AlkP–PL complex, 55.0% and 85.8% of esophageal epithelial cells expressed detectable AlkP, respectively. Other sections transfected with MnSOD–PL complex showed transgene mRNA by nested reverse transcriptase-polymerase chain reaction (RT-PCR) assay and increased MnSOD biochemical activity for at least 96 hr after transfection. Irradiated MnSOD–PL complex–transfected sections demonstrated a significantly decreased percentage of apoptotic cells when compared to irradiated control sections. Following 1,000 cGy, MnSOD–PL-treated samples showed 7.5 ± 2.8% and 33.3 ± 7.3% apoptotic cells at 24 and 48 hr compared to 53.6 ± 6.9% and 59.0 ± 13.8% for nontransfected controls (P < 0.0001 and P < 0.1175). After 2,000 cGy, results at 24 and 48 hr were 25.0 ± 7.6% and 66.9 ± 4.9% for MnSOD-transfected sections compared to 65.6 ± 4.3% and 90.0 ± 4.1% for control sections (P < 0.0001 and P = 0.0353), respectively. Thus, human esophageal sections can be transfected with MnSOD–PL complex in vitro and thereby protected against Ionizing Irradiation-induced apoptosis. Int. J. Cancer (Radiat. Oncol. Invest.) 90, 128–137 (2000). © 2000 Wiley-Liss, Inc.
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prevention of late effects of Irradiation lung damage by manganese superoxide dismutase gene therapy
Gene Therapy, 1998Co-Authors: Michael W. Epperly, J Bray, S Kraeger, Ralf M Zwacka, John F Engelhardt, Elizabeth L Travis, Joel S. GreenbergerAbstract:Organ and tissue damage caused by Ionizing Irradiation is directly related to volume irradiated, total dose and dose rate. The acute effects are in part mediated by cellular activation of early response genes, including those for transcriptional activators of genes for humoral cytokines. In the lung, as in other organs, recovery from the acute effects of Ionizing Irradiation does not always correlate with prevention of the critical fate effects, including fibrosis, which contribute to organ failure. An interventional technique by which to protect normal organs from the late effects of Irradiation has remained elusive. We now demonstrate that overexpression of a transgene for human manganese superoxide dismutase (MnSOD) delivered by plasmid-liposome, or adenovirus to the lungs of C57BL/6J or Nu/J mice, respectively, before Irradiation exposure, decreases the late effects of whole lung Irradiation (organizing alveolitis/fibrosis). These data provide a rational basis for the design of gene therapy approaches to organ protection from Irradiation damage.
Guy J Hallman - One of the best experts on this subject based on the ideXlab platform.
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Ionizing Irradiation of adults of angoumois grain moth lepidoptera gelechiidae and indianmeal moth lepidoptera pyralidae to prevent reproduction and implications for a generic Irradiation treatment for insects
Journal of Economic Entomology, 2008Co-Authors: Guy J Hallman, Thomas W PhillipsAbstract:Ionizing Irradiation is used as a phytosanitary treatment against quarantine pests. A generic treatment of 400 Gy has been approved for commodities entering the United States against all insects except pupae and adults of Lepidoptera because some literature citations indicate that a few insects, namely, the Angoumois grain moth, Sitotroga cerealella (Olivier) (Lepidoptera: Gelechiidae), and the Indianmeal moth, Plodia interpunctella (Hubner) (Lepidoptera: Pyralidae), are not completely controlled at that dose. Radiotolerance in insects increases as the insects develop, so the minimum absorbed dose to prevent F1 egg hatch for these two species when irradiated as adults was examined. Also, because hypoxia is known to increase radiotolerance in insects, Angoumois grain moth radiotolerance was tested in a hypoxic atmosphere. A dose range of 336–388 Gy prevented F1 egg hatch from a total of 22,083 adult Indianmeal moths. Dose ranges of 443–505 and 590–674 Gy, respectively, prevented F1 egg hatch from a total of 15,264 and 13,677 adult Angoumois grain moths irradiated in ambient and hypoxic atmospheres. A generic dose of 600 Gy for all insects in ambient atmospheres might be efficacious, although many fresh commodities may not tolerate it when applied on a commercial scale.
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potential increase in fruit fly diptera tephritidae interceptions using Ionizing Irradiation phytosanitary treatments
Journal of Economic Entomology, 2008Co-Authors: Guy J HallmanAbstract:Irradiation postharvest phytosanitary treatments are used increasingly and show further promise because of advantages compared with other treatments. Its chief disadvantage is that, unlike all other commercially used treatments, it does not provide acute mortality, although it prevents insects from completing development or reproducing. The objective of this research was to determine to what extent irradiated egg and early instars of tephritids would develop to later instars that could be found by phytosanitary inspectors or consumers. Mexican fruit fly, Anastrepha ludens (Loew), eggs and first instars in grapefruit, Citrus paradisi Macfayden, were irradiated with 70–250 Gy and held at ≈27°C until third instars completed development. The accepted minimum absorbed phytosanitary dose for this pest is 70 Gy, although higher doses may be applied under commercial conditions. The more developed a fruit fly before it was irradiated, the greater the proportion that survived to the third instar. Also, dose was inversely related to developmental success, e.g., a mean of ≈65 and 35%, respectively, of late first instars reached the third instar when irradiated with 70 and 250 Gy. Of those, 65.1 and 23.4%, respectively, pupariated, although no adults emerged. Irradiation may result in a greater frequency of live (albeit incapable of resulting in an infestation) larvae being found than would be expected compared with other treatments that provide acute mortality. The regulatory community should be aware of this and the fact that it does not increase the risk of Irradiation phytosanitary treatments resulting in an infestation of quarantine pests.
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low dose Irradiation phytosanitary treatment against mediterranean fruit fly diptera tephritidae
Florida Entomologist, 2007Co-Authors: Zoila Torresrivera, Guy J HallmanAbstract:Abstract The Mediterranean fruit fly, Ceratitis capitata (Wiedemann), is one of the most important quarantine pests in the world. Host commodities shipped from infested parts of the world to non-infested parts that might be susceptible to infestation should undergo a phytosanitary measure to render negligible the risk of shipping viable flies. Ionizing Irradiation is a promising phytosanitary treatment that is tolerated by the great majority of hosts of the Mediterranean fruit fly. The current dose in the US is 150 Gy. This research conducted with cage-infested ‘Haden’ mangoes in Peru showed that 100 Gy is sufficient to provide a high level of quarantine security against this important pest. That dose did not affect pupation when applied to late 3rd instars, but it did prevent any from emerging as adults. A dose of 100 Gy might allow for Irradiation of avocados, one of the few fruits that does not tolerate more than 100-200 Gy.
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Ionizing Irradiation quarantine treatment against oriental fruit moth lepidoptera tortricidae in ambient and hypoxic atmospheres
Journal of Economic Entomology, 2004Co-Authors: Guy J HallmanAbstract:Oriental fruit moth, Grapholita molesta (Busck), is a pest of many rosaceous temperate fruits, including pomes, Malus spp., and stone fruits, Prunus spp., in much of the world. However, some areas are free of the pest, and shipments of fruit hosts from infested to noninfested areas may be regulated. Current quarantine treatments for oriental fruit moth include methyl bromide fumigation and cold storage for several weeks. Methyl bromide use is being restricted because it is a stratospheric ozone-depleting substance, and alternatives are sought. Cold is not tolerated by many hosts of oriental fruit moth. The objective of this research was to develop Irradiation quarantine treatments against the pest under ambient and hypoxic storage conditions because some hosts of oriental fruit moth are stored in hypoxic atmospheres, and hypoxia is known to lessen the effects of Irradiation. In ambient atmospheres, no adults emerged from 58,779 fifth instars (the most radiotolerant stage present in fruit) irradiated with a target dose of 200 Gy (195–232 Gy measured). In atmospheres flushed with nitrogen, 5.3% of adults emerged from 44,050 fifth instars irradiated with a target dose of 200 Gy (194–230 Gy measured), but they died at a faster rate than control adults and without laying eggs. A dose of 232 Gy (the maximum recorded when 200 Gy was targeted) is recommended to disinfest any fruit of oriental fruit moth under ambient and hypoxic atmospheres.
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Ionizing Irradiation quarantine treatment against mexican fruit fly diptera tephritidae in citrus fruits
Postharvest Biology and Technology, 2001Co-Authors: Guy J Hallman, Luis MartinezAbstract:Abstract A low-dose gamma Irradiation quarantine treatment against the Mexican fruit fly, Anastrepha ludens (Loew) was developed for citrus fruits. The measure of efficacy of the treatment was prevention of adult emergence from third instars that were reared and treated in ‘Rio Red’ grapefruit, Citrus paradisi Macf. Depending on the level of quarantine security required, the minimum absorbed dose would be 58 or 69 Gy. When applied on a commercial scale, many irradiated fruit in each load can be expected to receive three times the minimum required dose for treatment efficacy. Several quality parameters of ‘Rio Red’ grapefruit, ‘Marrs’ oranges, C. sinensis (L.) Osbeck, and ‘Dancy’ tangerines, C. reticulata Blanco, including soluble solids content, titratable acidity, appearance, and organoleptic quality, were not affected compared with untreated fruit at the doses tested (up to 500 Gy).
