William Hempel - Academia.edu (original) (raw)
Papers by William Hempel
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The Journal of Applied Laboratory Medicine, 2016
Background Well-collected and well-documented sample repositories are necessary for disease bioma... more Background Well-collected and well-documented sample repositories are necessary for disease biomarker development. The availability of significant numbers of samples with the associated patient information enables biomarker validation to proceed with maximum efficacy and minimum bias. The creation and utilization of such a resource is an important step in the development of blood-based biomarker tests for colorectal cancer. Methods We have created a subject data and biological sample resource, Endoscopy II, which is based on 4698 individuals referred for diagnostic colonoscopy in Denmark between May 2010 and November 2012. Of the patients referred based on 1 or more clinical symptoms of colorectal neoplasia, 512 were confirmed by pathology to have colorectal cancer and 399 were confirmed to have advanced adenoma. Using subsets of these sample groups in case-control study designs (300 patients for colorectal cancer, 302 patients for advanced adenoma), 2 panels of plasma-based protein...
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Cancers, Jan 30, 2018
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La presente invention a pour objet des compositions et des methodes de detection, de gestion ou d... more La presente invention a pour objet des compositions et des methodes de detection, de gestion ou de surveillance du cancer. Linvention concerne egalement des anticorps specifiques pour marqueurs du cancer, des compositions et des puces contenant ceux-ci, ainsi que leurs utilisations pour la detection, la gestion, la surveillance, limagerie ou le traitement du cancer, ainsi que pour le developpement de medicaments. Linvention est particulierement adaptee a la detection, a la gestion ou a la surveillance du cancer du poumon chez les sujets humains.
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Lead (Pb) is an important environmental contaminant due to its widespread use over many centuries... more Lead (Pb) is an important environmental contaminant due to its widespread use over many centuries. While it affects primarily every organ system of the body, the most pernicious effects of Pb are on the central nervous system leading to cognitive and behavioral modification. Despite decades of research, the mechanisms responsible for Pb toxicity remain poorly understood. Recent work has suggested that Pb exposure may have consequences on chromosomal integrity as it was shown that Pb exposure leads to the generation of cH2Ax foci, a well-established biomarker for DNA double stranded break (DSB formation). As the chromosomal localization of cH2Ax foci plays an important role in determining the molecular mechanism responsible for their formation, we examined the localization of Pb-induced foci with respect to telomeres. Indeed, short or dysfunctional telomeres (uncapped or damaged telomeres) may be recognized as DSB by the DNA repair machinery, leading to ‘‘telomere-Induced Foci’ ’ (TI...
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Genes
Dicentric chromosomes are a relevant marker of chromosomal instability. Their appearance is assoc... more Dicentric chromosomes are a relevant marker of chromosomal instability. Their appearance is associated with telomere dysfunction, leading to cancer progression and a poor clinical outcome. Here, we present Telomere and Centromere staining followed by M-FISH (TC+M-FISH) for improved detection of telomere dysfunction and the identification of dicentric chromosomes in cancer patients and various genetic syndromes. Significant telomere length shortening and significantly higher frequencies of telomere loss and deletion were found in the peripheral lymphocytes of patients with cancer and genetic syndromes relative to similar age-matched healthy donors. We assessed our technique against conventional cytogenetics for the detection of dicentric chromosomes by subjecting metaphase preparations to both approaches. We identified dicentric chromosomes in 28/50 cancer patients and 21/44 genetic syndrome patients using our approach, but only 7/50 and 12/44, respectively, using standard cytogeneti...
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Health Physics
PURPOSE Biological dosimetry, based on the relationship between the absorbed dose after exposure ... more PURPOSE Biological dosimetry, based on the relationship between the absorbed dose after exposure to ionizing radiation and the frequency of scored aberrations, has been and continues to be an important tool for estimating the dose after exposure. Dicentric chromosomes are considered to be the most specific and sensitive aberration related to radiation exposure. Here, we established the dose-response curve following in vitro irradiation of circulating lymphocytes from healthy donors from three African countries after scoring unstable chromosomal aberrations. MATERIALS AND METHODS Blood samples from 16 African donors were exposed to various doses (0 to 4 Gy) using an X-RAD320 x-ray system with a maximum photon energy of 250 kV at a dose rate of 0.1 Gy min. Blood lymphocytes were cultured for 48 h, and chromosomal aberrations were scored during the first mitosis by telomere and centromere staining. The distribution of dicentric chromosomes was determined. RESULTS No dicentric chromosomes were found after the analysis of 2,669 first-division metaphases before in vitro exposure. We established a linear-quadratic dose-response curve based on the frequency of dicentric and ring chromosomes and calculated double-strand breaks, taking into account all scored aberrations. CONCLUSION The generation of a specific dose-response curve for African donors will allow the practice of precise biological dosimetry in these countries. This work is the first step towards realizing an African biodosimetry network and the establishment of a biological dosimetry laboratory, which could play a major role in the application of radioprotection norms.
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Cancers
Background: Microsatellite and chromosomal instability have been investigated in Hodgkin lymphoma... more Background: Microsatellite and chromosomal instability have been investigated in Hodgkin lymphoma (HL). Materials and Methods: We studied seven HL cell lines (five Nodular Sclerosis (NS) and two Mixed Cellularity (MC)) and patient peripheral blood lymphocytes (100 NS-HL and 23 MC-HL). Microsatellite instability (MSI) was assessed by PCR. Chromosomal instability and telomere dysfunction were investigated by FISH. DNA repair mechanisms were studied by transcriptomic and molecular approaches. Results: In the cell lines, we observed high MSI in L428 (4/5), KMH2, and HDLM2 (3/5), low MSI in L540, L591, and SUP-HD1, and none in L1236. NS-HL cell lines showed telomere shortening, associated with alterations of nuclear shape. Small cells were characterized by telomere loss and deletion, leading to chromosomal fusion, large nucleoplasmic bridges, and breakage/fusion/bridge (B/F/B) cycles, leading to chromosomal instability. The MC-HL cell lines showed substantial heterogeneity of telomere le...
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Cancers
To identify the cells responsible for the initiation and maintenance of Hodgkin lymphoma (HL) cel... more To identify the cells responsible for the initiation and maintenance of Hodgkin lymphoma (HL) cells, we have characterized a subpopulation of HL cells grown in vitro and in vivo with the aim of establishing a reliable and robust animal model for HL. To validate our model, we challenged the tumor cells in vivo by injecting the alkylating histone-deacetylase inhibitor, EDO-S101, a salvage regimen for HL patients, into xenografted mice. Methodology: Blood lymphocytes from 50 HL patients and seven HL cell lines were used. Immunohistochemistry, flow cytometry, and cytogenetics analyses were performed. The in vitro and in vivo effects of EDO-S101 were assessed. Results: We have successfully determined conditions for in vitro amplification and characterization of the HL L428-c subline, containing a higher proportion of CD30−/CD15− cells than the parental L428 cell line. This subline displayed excellent clonogenic potential and reliable reproducibility upon xenografting into immunodeficient...
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The Journal of Immunology, 1992
ABSTRACT
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The Journal of Immunology
ABSTRACT
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The Journal of Immunology
Ligand-induced activation of T cells results in stimulation of phosphatidylinositol-specific phos... more Ligand-induced activation of T cells results in stimulation of phosphatidylinositol-specific phospholipase C (PI-PLC). A structurally diverse family of PI-PLC isoforms has recently been defined, and more than one isoform is frequently coexpressed in a single cell or tissue, suggesting that different forms may play distinct roles in cellular activation, proliferation, or differentiation. We show here that both PLC-alpha and PLC-gamma are expressed in rat splenic T cells and in Jurkat cells (a human T cell line). Activation of Jurkat cells with the combination of PMA and PHA leads to increased expression of PLC-alpha message and decreased expression of PLC-gamma message after 4 h of stimulation. The increase in PLC-alpha transcripts was detectable at 4 h, maximal at 6 h, and remained elevated for at least 24 h. The decrease in PLC-gamma message was transient, with a maximal effect at 4 h, and a return to basal levels by 6 h. Changes in PI-PLC transcripts were also induced by the combination of PMA and the calcium ionophore, ionomycin. These data demonstrate that the expression of transcripts for PLC-alpha and PLC-gamma can be differentially regulated during a cellular response, and raise the possibility that these two isoforms of PI-PLC subserve distinct functions in T cell activation.
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Methods in molecular biology (Clifton, N.J.), 2004
Active genes in eukaryotic genomes are typically found in open, nuclease-sensitive regions of chr... more Active genes in eukaryotic genomes are typically found in open, nuclease-sensitive regions of chromatin. This chapter presents an overview of the techniques used to assay restriction endonuclease cleavage of chromosomal DNA as an approach to assess general accessibility at a genomic region of interest. We describe protocols to (1) prepare nuclei templates, (2) treat chromosomal DNA with a restriction enzyme(s), and (3) visualize and quantify chromosomal cleavage(s), with an emphasis on ligation-mediated (LM) PCR techniques.
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Journal of immunology (Baltimore, Md. : 1950), 1991
Cross-linking of membrane (m) Ig, the B cell receptor for Ag, activates protein tyrosine phosphor... more Cross-linking of membrane (m) Ig, the B cell receptor for Ag, activates protein tyrosine phosphorylation and hydrolysis of phosphotidylinositol 4,5-bisphosphate. The latter signal transduction pathway is an important mediator of antigen receptor engagement. The initial event in this pathway is the activation of phospholipase C (PLC). The identity of the isozyme of PLC used in B cells and the mechanism by which it becomes activated are currently unknown. The cDNA encoding five different isozymes have been cloned. As a first step in identifying the isozyme of PLC that is coupled to mIgM, murine cDNA fragments for the five cloned PLC isozymes were generated by the polymerase chain reaction (PCR), cloned, and used to screen a panel of B cell lines representing different stages of development for PLC mRNA expression. All the B cell lines tested expressed high levels of PLC alpha and PLC gamma 2 mRNA, whereas PLC beta and PLC delta mRNA expression were undetectable by both Northern blot a...
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Nature, 1995
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Cancers, Jan 26, 2018
The study of Hodgkin lymphoma (HL), with its unique microenvironment and long-term follow-up, has... more The study of Hodgkin lymphoma (HL), with its unique microenvironment and long-term follow-up, has provided exceptional insights into several areas of tumor biology. Findings in HL have not only improved our understanding of human carcinogenesis, but have also pioneered its translation into the clinics. HL is a successful paradigm of modern treatment strategies. Nonetheless, approximately 15-20% of patients with advanced stage HL still die following relapse or progressive disease and a similar proportion of patients are over-treated, leading to treatment-related late sequelae, including solid tumors and organ dysfunction. The malignant cells in HL are characterized by a highly altered genomic landscape with a wide spectrum of genomic alterations, including somatic mutations, copy number alterations, complex chromosomal rearrangements, and aneuploidy. Here, we review the chromosomal instability mechanisms in HL, starting with the cellular origin of neoplastic cells and the mechanisms ...
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Scientific reports, Jan 12, 2017
The mechanisms behind the transmission of chromosomal aberrations (CA) remain unclear, despite a ... more The mechanisms behind the transmission of chromosomal aberrations (CA) remain unclear, despite a large body of work and major technological advances in chromosome identification. We reevaluated the transmission of CA to second- and third-division cells by telomere and centromere (TC) staining followed by M-FISH. We scored CA in lymphocytes of healthy donors after in vitro irradiation and those of cancer patients treated by radiation therapy more than 12 years before. Our data demonstrate, for the first time, that dicentric chromosomes (DCs) decreased by approximately 50% per division. DCs with two centromeres in close proximity were more efficiently transmitted, representing 70% of persistent DCs in ≥M3 cells. Only 1/3 of acentric chromosomes (ACs), ACs with four telomeres, and interstitial ACs, were paired in M2 cells and associated with specific DCs configurations. In lymphocytes of cancer patients, 82% of detected DCs were characterized by these specific configurations. Our findi...
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Scientific reports, Sep 2, 2016
Telomeres are specific structures that protect chromosome ends and act as a biological clock, pre... more Telomeres are specific structures that protect chromosome ends and act as a biological clock, preventing normal cells from replicating indefinitely. Mammalian telomeres are replicated throughout S-phase in a predetermined order. However, the mechanism of this regulation is still unknown. We wished to investigate this phenomenon under physiological conditions in a changing environment, such as the immortalization process to better understand the mechanism for its control. We thus examined the timing of human telomere replication in normal and SV40 immortalized cells, which are cytogenetically very similar to cancer cells. We found that the timing of telomere replication was globally conserved under different conditions during the immortalization process. The timing of telomere replication was conserved despite changes in telomere length due to endogenous telomerase reactivation, in duplicated homologous chromosomes, and in rearranged chromosomes. Importantly, translocated telomeres, ...
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Frontiers in Oncology, 2016
Carbon ions are an up-and-coming ion species, currently being used in charged particle radiothera... more Carbon ions are an up-and-coming ion species, currently being used in charged particle radiotherapy. As it is well established that there are considerable interindividual differences in radiosensitivity in the general population that can significantly influence clinical outcomes of radiotherapy, we evaluate the degree of these differences in the context of carbon ion therapy compared with conventional radiotherapy. In this study, we evaluate individual radiosensitivity following exposure to carbon-13 ions or γ-rays in peripheral blood lymphocytes of healthy individuals based on the frequency of ionizing radiation (IR)-induced DNA double strand breaks (DSBs) that was either misrepaired or left unrepaired to form chromosomal aberrations (CAs) (simply referred to here as DSBs for brevity). Levels of DSBs were estimated from the scoring of CAs visualized with telomere/centromere-fluorescence in situ hybridization (TC-FISH). We examine radiosensitivity at the dose of 2 Gy, a routinely administered dose during fractionated radiotherapy, and we determined that a wide range of DSBs were induced by the given dose among healthy individuals, with highly radiosensitive individuals harboring more IR-induced breaks in the genome than radioresistant individuals following exposure to the same dose. Furthermore, we determined the relative effectiveness of carbon irradiation in comparison to γ-irradiation in the induction of DSBs at each studied dose (isodose effect), a quality we term "relative dose effect" (RDE). This ratio is advantageous, as it allows for simple comparison of dose-response curves. At 2 Gy, carbon irradiation was three times more effective in inducing DSBs compared with γ-irradiation (RDE of 3); these results were confirmed using a second cytogenetic technique, multicolor-FISH. We also analyze radiosensitivity at other doses (0.2-15 Gy), to represent hypo- and hyperfractionation doses and determined that RDE is dose dependent: high ratios at low doses, and approaching 1 at high doses. These results could have clinical implications as IR-induced DNA damage and the ensuing CAs and genomic instability can have significant cellular consequences that could potentially have profound implications for long-term human health after IR exposure, such as the emergence of secondary cancers and other pathobiological conditions after radiotherapy.
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The Journal of Applied Laboratory Medicine, 2016
Background Well-collected and well-documented sample repositories are necessary for disease bioma... more Background Well-collected and well-documented sample repositories are necessary for disease biomarker development. The availability of significant numbers of samples with the associated patient information enables biomarker validation to proceed with maximum efficacy and minimum bias. The creation and utilization of such a resource is an important step in the development of blood-based biomarker tests for colorectal cancer. Methods We have created a subject data and biological sample resource, Endoscopy II, which is based on 4698 individuals referred for diagnostic colonoscopy in Denmark between May 2010 and November 2012. Of the patients referred based on 1 or more clinical symptoms of colorectal neoplasia, 512 were confirmed by pathology to have colorectal cancer and 399 were confirmed to have advanced adenoma. Using subsets of these sample groups in case-control study designs (300 patients for colorectal cancer, 302 patients for advanced adenoma), 2 panels of plasma-based protein...
Bookmarks Related papers MentionsView impact
Cancers, Jan 30, 2018
Bookmarks Related papers MentionsView impact
La presente invention a pour objet des compositions et des methodes de detection, de gestion ou d... more La presente invention a pour objet des compositions et des methodes de detection, de gestion ou de surveillance du cancer. Linvention concerne egalement des anticorps specifiques pour marqueurs du cancer, des compositions et des puces contenant ceux-ci, ainsi que leurs utilisations pour la detection, la gestion, la surveillance, limagerie ou le traitement du cancer, ainsi que pour le developpement de medicaments. Linvention est particulierement adaptee a la detection, a la gestion ou a la surveillance du cancer du poumon chez les sujets humains.
Bookmarks Related papers MentionsView impact
Bookmarks Related papers MentionsView impact
Lead (Pb) is an important environmental contaminant due to its widespread use over many centuries... more Lead (Pb) is an important environmental contaminant due to its widespread use over many centuries. While it affects primarily every organ system of the body, the most pernicious effects of Pb are on the central nervous system leading to cognitive and behavioral modification. Despite decades of research, the mechanisms responsible for Pb toxicity remain poorly understood. Recent work has suggested that Pb exposure may have consequences on chromosomal integrity as it was shown that Pb exposure leads to the generation of cH2Ax foci, a well-established biomarker for DNA double stranded break (DSB formation). As the chromosomal localization of cH2Ax foci plays an important role in determining the molecular mechanism responsible for their formation, we examined the localization of Pb-induced foci with respect to telomeres. Indeed, short or dysfunctional telomeres (uncapped or damaged telomeres) may be recognized as DSB by the DNA repair machinery, leading to ‘‘telomere-Induced Foci’ ’ (TI...
Bookmarks Related papers MentionsView impact
Genes
Dicentric chromosomes are a relevant marker of chromosomal instability. Their appearance is assoc... more Dicentric chromosomes are a relevant marker of chromosomal instability. Their appearance is associated with telomere dysfunction, leading to cancer progression and a poor clinical outcome. Here, we present Telomere and Centromere staining followed by M-FISH (TC+M-FISH) for improved detection of telomere dysfunction and the identification of dicentric chromosomes in cancer patients and various genetic syndromes. Significant telomere length shortening and significantly higher frequencies of telomere loss and deletion were found in the peripheral lymphocytes of patients with cancer and genetic syndromes relative to similar age-matched healthy donors. We assessed our technique against conventional cytogenetics for the detection of dicentric chromosomes by subjecting metaphase preparations to both approaches. We identified dicentric chromosomes in 28/50 cancer patients and 21/44 genetic syndrome patients using our approach, but only 7/50 and 12/44, respectively, using standard cytogeneti...
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Health Physics
PURPOSE Biological dosimetry, based on the relationship between the absorbed dose after exposure ... more PURPOSE Biological dosimetry, based on the relationship between the absorbed dose after exposure to ionizing radiation and the frequency of scored aberrations, has been and continues to be an important tool for estimating the dose after exposure. Dicentric chromosomes are considered to be the most specific and sensitive aberration related to radiation exposure. Here, we established the dose-response curve following in vitro irradiation of circulating lymphocytes from healthy donors from three African countries after scoring unstable chromosomal aberrations. MATERIALS AND METHODS Blood samples from 16 African donors were exposed to various doses (0 to 4 Gy) using an X-RAD320 x-ray system with a maximum photon energy of 250 kV at a dose rate of 0.1 Gy min. Blood lymphocytes were cultured for 48 h, and chromosomal aberrations were scored during the first mitosis by telomere and centromere staining. The distribution of dicentric chromosomes was determined. RESULTS No dicentric chromosomes were found after the analysis of 2,669 first-division metaphases before in vitro exposure. We established a linear-quadratic dose-response curve based on the frequency of dicentric and ring chromosomes and calculated double-strand breaks, taking into account all scored aberrations. CONCLUSION The generation of a specific dose-response curve for African donors will allow the practice of precise biological dosimetry in these countries. This work is the first step towards realizing an African biodosimetry network and the establishment of a biological dosimetry laboratory, which could play a major role in the application of radioprotection norms.
Bookmarks Related papers MentionsView impact
Cancers
Background: Microsatellite and chromosomal instability have been investigated in Hodgkin lymphoma... more Background: Microsatellite and chromosomal instability have been investigated in Hodgkin lymphoma (HL). Materials and Methods: We studied seven HL cell lines (five Nodular Sclerosis (NS) and two Mixed Cellularity (MC)) and patient peripheral blood lymphocytes (100 NS-HL and 23 MC-HL). Microsatellite instability (MSI) was assessed by PCR. Chromosomal instability and telomere dysfunction were investigated by FISH. DNA repair mechanisms were studied by transcriptomic and molecular approaches. Results: In the cell lines, we observed high MSI in L428 (4/5), KMH2, and HDLM2 (3/5), low MSI in L540, L591, and SUP-HD1, and none in L1236. NS-HL cell lines showed telomere shortening, associated with alterations of nuclear shape. Small cells were characterized by telomere loss and deletion, leading to chromosomal fusion, large nucleoplasmic bridges, and breakage/fusion/bridge (B/F/B) cycles, leading to chromosomal instability. The MC-HL cell lines showed substantial heterogeneity of telomere le...
Bookmarks Related papers MentionsView impact
Cancers
To identify the cells responsible for the initiation and maintenance of Hodgkin lymphoma (HL) cel... more To identify the cells responsible for the initiation and maintenance of Hodgkin lymphoma (HL) cells, we have characterized a subpopulation of HL cells grown in vitro and in vivo with the aim of establishing a reliable and robust animal model for HL. To validate our model, we challenged the tumor cells in vivo by injecting the alkylating histone-deacetylase inhibitor, EDO-S101, a salvage regimen for HL patients, into xenografted mice. Methodology: Blood lymphocytes from 50 HL patients and seven HL cell lines were used. Immunohistochemistry, flow cytometry, and cytogenetics analyses were performed. The in vitro and in vivo effects of EDO-S101 were assessed. Results: We have successfully determined conditions for in vitro amplification and characterization of the HL L428-c subline, containing a higher proportion of CD30−/CD15− cells than the parental L428 cell line. This subline displayed excellent clonogenic potential and reliable reproducibility upon xenografting into immunodeficient...
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The Journal of Immunology, 1992
ABSTRACT
Bookmarks Related papers MentionsView impact
The Journal of Immunology
ABSTRACT
Bookmarks Related papers MentionsView impact
The Journal of Immunology
Ligand-induced activation of T cells results in stimulation of phosphatidylinositol-specific phos... more Ligand-induced activation of T cells results in stimulation of phosphatidylinositol-specific phospholipase C (PI-PLC). A structurally diverse family of PI-PLC isoforms has recently been defined, and more than one isoform is frequently coexpressed in a single cell or tissue, suggesting that different forms may play distinct roles in cellular activation, proliferation, or differentiation. We show here that both PLC-alpha and PLC-gamma are expressed in rat splenic T cells and in Jurkat cells (a human T cell line). Activation of Jurkat cells with the combination of PMA and PHA leads to increased expression of PLC-alpha message and decreased expression of PLC-gamma message after 4 h of stimulation. The increase in PLC-alpha transcripts was detectable at 4 h, maximal at 6 h, and remained elevated for at least 24 h. The decrease in PLC-gamma message was transient, with a maximal effect at 4 h, and a return to basal levels by 6 h. Changes in PI-PLC transcripts were also induced by the combination of PMA and the calcium ionophore, ionomycin. These data demonstrate that the expression of transcripts for PLC-alpha and PLC-gamma can be differentially regulated during a cellular response, and raise the possibility that these two isoforms of PI-PLC subserve distinct functions in T cell activation.
Bookmarks Related papers MentionsView impact
Methods in molecular biology (Clifton, N.J.), 2004
Active genes in eukaryotic genomes are typically found in open, nuclease-sensitive regions of chr... more Active genes in eukaryotic genomes are typically found in open, nuclease-sensitive regions of chromatin. This chapter presents an overview of the techniques used to assay restriction endonuclease cleavage of chromosomal DNA as an approach to assess general accessibility at a genomic region of interest. We describe protocols to (1) prepare nuclei templates, (2) treat chromosomal DNA with a restriction enzyme(s), and (3) visualize and quantify chromosomal cleavage(s), with an emphasis on ligation-mediated (LM) PCR techniques.
Bookmarks Related papers MentionsView impact
Journal of immunology (Baltimore, Md. : 1950), 1991
Cross-linking of membrane (m) Ig, the B cell receptor for Ag, activates protein tyrosine phosphor... more Cross-linking of membrane (m) Ig, the B cell receptor for Ag, activates protein tyrosine phosphorylation and hydrolysis of phosphotidylinositol 4,5-bisphosphate. The latter signal transduction pathway is an important mediator of antigen receptor engagement. The initial event in this pathway is the activation of phospholipase C (PLC). The identity of the isozyme of PLC used in B cells and the mechanism by which it becomes activated are currently unknown. The cDNA encoding five different isozymes have been cloned. As a first step in identifying the isozyme of PLC that is coupled to mIgM, murine cDNA fragments for the five cloned PLC isozymes were generated by the polymerase chain reaction (PCR), cloned, and used to screen a panel of B cell lines representing different stages of development for PLC mRNA expression. All the B cell lines tested expressed high levels of PLC alpha and PLC gamma 2 mRNA, whereas PLC beta and PLC delta mRNA expression were undetectable by both Northern blot a...
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Nature, 1995
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Cancers, Jan 26, 2018
The study of Hodgkin lymphoma (HL), with its unique microenvironment and long-term follow-up, has... more The study of Hodgkin lymphoma (HL), with its unique microenvironment and long-term follow-up, has provided exceptional insights into several areas of tumor biology. Findings in HL have not only improved our understanding of human carcinogenesis, but have also pioneered its translation into the clinics. HL is a successful paradigm of modern treatment strategies. Nonetheless, approximately 15-20% of patients with advanced stage HL still die following relapse or progressive disease and a similar proportion of patients are over-treated, leading to treatment-related late sequelae, including solid tumors and organ dysfunction. The malignant cells in HL are characterized by a highly altered genomic landscape with a wide spectrum of genomic alterations, including somatic mutations, copy number alterations, complex chromosomal rearrangements, and aneuploidy. Here, we review the chromosomal instability mechanisms in HL, starting with the cellular origin of neoplastic cells and the mechanisms ...
Bookmarks Related papers MentionsView impact
Scientific reports, Jan 12, 2017
The mechanisms behind the transmission of chromosomal aberrations (CA) remain unclear, despite a ... more The mechanisms behind the transmission of chromosomal aberrations (CA) remain unclear, despite a large body of work and major technological advances in chromosome identification. We reevaluated the transmission of CA to second- and third-division cells by telomere and centromere (TC) staining followed by M-FISH. We scored CA in lymphocytes of healthy donors after in vitro irradiation and those of cancer patients treated by radiation therapy more than 12 years before. Our data demonstrate, for the first time, that dicentric chromosomes (DCs) decreased by approximately 50% per division. DCs with two centromeres in close proximity were more efficiently transmitted, representing 70% of persistent DCs in ≥M3 cells. Only 1/3 of acentric chromosomes (ACs), ACs with four telomeres, and interstitial ACs, were paired in M2 cells and associated with specific DCs configurations. In lymphocytes of cancer patients, 82% of detected DCs were characterized by these specific configurations. Our findi...
Bookmarks Related papers MentionsView impact
Scientific reports, Sep 2, 2016
Telomeres are specific structures that protect chromosome ends and act as a biological clock, pre... more Telomeres are specific structures that protect chromosome ends and act as a biological clock, preventing normal cells from replicating indefinitely. Mammalian telomeres are replicated throughout S-phase in a predetermined order. However, the mechanism of this regulation is still unknown. We wished to investigate this phenomenon under physiological conditions in a changing environment, such as the immortalization process to better understand the mechanism for its control. We thus examined the timing of human telomere replication in normal and SV40 immortalized cells, which are cytogenetically very similar to cancer cells. We found that the timing of telomere replication was globally conserved under different conditions during the immortalization process. The timing of telomere replication was conserved despite changes in telomere length due to endogenous telomerase reactivation, in duplicated homologous chromosomes, and in rearranged chromosomes. Importantly, translocated telomeres, ...
Bookmarks Related papers MentionsView impact
Frontiers in Oncology, 2016
Carbon ions are an up-and-coming ion species, currently being used in charged particle radiothera... more Carbon ions are an up-and-coming ion species, currently being used in charged particle radiotherapy. As it is well established that there are considerable interindividual differences in radiosensitivity in the general population that can significantly influence clinical outcomes of radiotherapy, we evaluate the degree of these differences in the context of carbon ion therapy compared with conventional radiotherapy. In this study, we evaluate individual radiosensitivity following exposure to carbon-13 ions or γ-rays in peripheral blood lymphocytes of healthy individuals based on the frequency of ionizing radiation (IR)-induced DNA double strand breaks (DSBs) that was either misrepaired or left unrepaired to form chromosomal aberrations (CAs) (simply referred to here as DSBs for brevity). Levels of DSBs were estimated from the scoring of CAs visualized with telomere/centromere-fluorescence in situ hybridization (TC-FISH). We examine radiosensitivity at the dose of 2 Gy, a routinely administered dose during fractionated radiotherapy, and we determined that a wide range of DSBs were induced by the given dose among healthy individuals, with highly radiosensitive individuals harboring more IR-induced breaks in the genome than radioresistant individuals following exposure to the same dose. Furthermore, we determined the relative effectiveness of carbon irradiation in comparison to γ-irradiation in the induction of DSBs at each studied dose (isodose effect), a quality we term "relative dose effect" (RDE). This ratio is advantageous, as it allows for simple comparison of dose-response curves. At 2 Gy, carbon irradiation was three times more effective in inducing DSBs compared with γ-irradiation (RDE of 3); these results were confirmed using a second cytogenetic technique, multicolor-FISH. We also analyze radiosensitivity at other doses (0.2-15 Gy), to represent hypo- and hyperfractionation doses and determined that RDE is dose dependent: high ratios at low doses, and approaching 1 at high doses. These results could have clinical implications as IR-induced DNA damage and the ensuing CAs and genomic instability can have significant cellular consequences that could potentially have profound implications for long-term human health after IR exposure, such as the emergence of secondary cancers and other pathobiological conditions after radiotherapy.
Bookmarks Related papers MentionsView impact