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John Pierce Wise - One of the best experts on this subject based on the ideXlab platform.
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Carcinogenesis vol.14 no.3 pp.429-434, 1993 Inhibition of Lead Chromate dastogenesis by ascorbate: relationship to particle dissolution and uptake
2016Co-Authors: John Pierce Wise, Jan Marc Orenstein, Steven R. PatierwAbstract:3To whom all correspondence should be addressed Chromium metal salts are considered to be human car-cinogens, especially the salts of low solubility. Lead Chromate, a highly insoluble chromium metal salt, has been shown to be tumorigenk, genotoxic and clastogenic. In this study, the roles of particle-cell contact, particle dissolution and parti-cle uptake in the clastogenic activity of Lead Chromate were investigated. Using Pb51CrO4 it was found that Lead Chromate particles (1.2 /tin mean diameter,- 2 8 mV surface charge) were slightly soluble in water; solubility increased 2-fold when particles were incubated in culture medium, but was not increased further by the addition of serum. The extra-cellular concentration of chromium increased 7-fold when Lead Chromate was incubated in the presence of Chinese hamster ovary (CHO) cells compared with culture medium alone. The intracellular concentration of ionic chromium increased in a dose-dependent manner following exposure of CHO cells to clastogenic doses of Lead Chromate reaching estimated levels as high as 1.2 mM per cell. Treatment of cells with Lead Chromate particles in the presence of a nontoxic dose of vitamin C blocked uptake of ionic chromium and eliminated the clastogenic activity of the particles. Transmission electron microscopy showed that Lead Chromate particles were inter-nalized by CHO cells in phagocytic vacuoles in as little as 1 h; internalization was unaffected by co-treatment with vitamin C. It was demonstrated that particle-cell contact was required for Lead Chromate-induced dastogenesis. These data show that although phagocytic particle uptake occurs, particle-cell contact and extracellular dissolution are responsible for the clastogenic activity of Lead Chromate. These data also demonstrate that the genotoxicity of participate hexavalent Chromates can be blocked by vitamin C
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abstract 3102 hexavalent chromium induces chromosome instability Leading to dna double strand break repair deficiency and neoplastic transformation
Cancer Research, 2012Co-Authors: Sandra S Wise, Amie L Holmes, Douglas W Thompson, Hong Xie, John Pierce WiseAbstract:Proceedings: AACR 103rd Annual Meeting 2012‐‐ Mar 31‐Apr 4, 2012; Chicago, IL Chromosome instability (CIN) is a hallmark of lung cancer with cells exhibiting both translocations and aneuploidy. Hexavalent chromium (Cr(VI)) is a well known respiratory carcinogen. The ability of Cr(VI) to induce chromosomal translocations is unknown. We exposed human lung cells to Lead Chromate for three sequential 24 h periods, each separated by about a month. After each treatment, cells were seeded at colony forming density, cloned, expanded and retreated. Each generation of clones was tested for chromium sensitivity, chromosome complement, ability to repair DNA double strand breaks (DSB), and growth in soft agar. We found that after the first treatment, Lead Chromate-treated cells exhibited a normal chromosome complement though a few clones showed a decrease in cell survival. After the second exposure, more than half of the clones acquired an abnormal karyotype including numerical and structural changes. The third treatment resulted in additional abnormal clones as well as previously abnormal clones acquiring more abnormalities. Clones were treated with soluble Cr(VI) for 24 h followed by a 24 h recovery period to measure DNA DSB repair. Abnormal clones showed persistent H2A.X and 53BP1 foci formation after 24 h recovery suggesting that these clones had acquired a DNA DSB repair-deficient phenotype. In addition, clones from the third generation were able to form colonies in soft agar suggesting that the cells have neoplastically transformed. This work was supported by NIEHS grant ES016893 (J.P.W.) and the Maine Center for Toxicology and Environmental Health. Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 103rd Annual Meeting of the American Association for Cancer Research; 2012 Mar 31-Apr 4; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2012;72(8 Suppl):Abstract nr 3102. doi:1538-7445.AM2012-3102
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The cytotoxicity and genotoxicity of hexavalent chromium in Steller sea lion lung fibroblasts compared to human lung fibroblasts.
Comparative Biochemistry and Physiology C-toxicology & Pharmacology, 2010Co-Authors: John Pierce Wise, Carolyne Lacerte, Sandra S Wise, Amie L Holmes, Fariba Shaffiey, Abouel-makarim AboueissaAbstract:Abstract In this study we directly compared soluble and particulate Chromate cytotoxicity and genotoxicity in human (Homo sapiens) and sea lion (Eumetopias jubatus) lung fibroblasts. Our results show that hexavalent chromium induces increased cell death and chromosome damage in both human and sea lion cells with increasing intracellular chromium ion levels. The data further indicate that both sodium Chromate and Lead Chromate are less cytotoxic and genotoxic to sea lion cells than human cells, based on an administered dose. Differences in chromium ion uptake explained some but not all of the reduced amounts of sodium Chromate-induced cell death. By contrast, uptake differences could explain the differences in sodium Chromate-induced chromosome damage and particulate Chromate-induced toxicity. Altogether they indicate that while hexavalent chromium induces similar toxic effects in sea lion and human cells, there are different mechanisms underlying the toxic outcomes.
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neoplastic transformation of human bronchial cells by Lead Chromate particles
American Journal of Respiratory Cell and Molecular Biology, 2007Co-Authors: Hong Xie, Sandra S Wise, Amie L Holmes, Shouping Huang, Cheng Peng, John Pierce WiseAbstract:Particulate hexavalent chromium (Cr(VI)) is a well-established human lung carcinogen with widespread exposure among people in occupational settings and the general public. However, no studies have examined the Chromate-induced malignant transformation of human lung epithelial cells, its predominant target. Human papillomavirus–immortalized human bronchial epithelial (BEP2D) cells were used to better understand the mechanisms involved in human bronchial carcinogenesis induced by particulate Chromate. We found that aneuploid cells increased in a concentrationdependent manner after chronic exposure to Lead Chromate. Moreover, chronic exposure to Lead Chromate induced BEP2D cell transformation. Transformed BEP2D cells developed through a series of sequential steps, including altered cell morphology, loss of cell contact inhibition and anchorage-independent growth. Specifically, a 5-day exposure to Lead Chromate induced foci formation with 0, 1, 5, and 10 mg/cm 2 Lead Chromate inducing 0, 7, 3, and 15 foci in 10 dishes. Anchorage independence was observed in cell lines derived from these foci. These foci-derived cells also showed centrosome amplification and increases in aneuploid metaphases. Our study demonstrates that particulate Cr(VI) is able to transform human bronchial epithelial cells, and that chromosome instability may play an important role in particulate Cr(VI)-induced neoplastic trans
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role of the fancg gene in protecting cells from particulate Chromate induced chromosome instability
Mutation Research-genetic Toxicology and Environmental Mutagenesis, 2007Co-Authors: Laura C Savery, Sandra S Wise, Eliza Grlickovaduzevik, Douglas W Thompson, John M Hinz, Larry H Thompson, John Pierce WiseAbstract:Particulate hexavalent chromium (Cr(VI)) is a known human lung carcinogen. Cr(VI)-induced tumors exhibit chromosome instability (CIN), but the mechanisms underlying these effects are unknown. We investigated a possible role for the Fanconi anemia (FA) pathway in particulate Cr(VI)-induced chromosomal damage by focusing on the Fancg gene, which plays an important role in cellular resistance to DNA interstrand crosslinks. We used the isogenic Chinese hamster ovary (CHO) KO40 fancg mutant compared with parental and gene-complemented cells. We found that fancg cells treated with Lead Chromate had lower intracellular Cr ion levels than control cell lines. Accounting for differences of Cr ion levels between cell lines, we discovered that fancg cells treated with Lead Chromate had increased cytotoxicity and chromosomal aberrations, which was not observed after restoring the Fancg gene. Chromosomal damage was manifest as increased total chromosome damage and percent metaphases with damage, specifically an increase in chromatid and isochromatid breaks. We conclude that Fancg protects cells from particulate Cr(VI)-induced cytotoxicity and chromosome damage, which is consistent with the known sensitivity of fancg cells to crosslinking damage and the ability of Cr(VI) to produce crosslinks.
Sandra S Wise - One of the best experts on this subject based on the ideXlab platform.
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abstract 3102 hexavalent chromium induces chromosome instability Leading to dna double strand break repair deficiency and neoplastic transformation
Cancer Research, 2012Co-Authors: Sandra S Wise, Amie L Holmes, Douglas W Thompson, Hong Xie, John Pierce WiseAbstract:Proceedings: AACR 103rd Annual Meeting 2012‐‐ Mar 31‐Apr 4, 2012; Chicago, IL Chromosome instability (CIN) is a hallmark of lung cancer with cells exhibiting both translocations and aneuploidy. Hexavalent chromium (Cr(VI)) is a well known respiratory carcinogen. The ability of Cr(VI) to induce chromosomal translocations is unknown. We exposed human lung cells to Lead Chromate for three sequential 24 h periods, each separated by about a month. After each treatment, cells were seeded at colony forming density, cloned, expanded and retreated. Each generation of clones was tested for chromium sensitivity, chromosome complement, ability to repair DNA double strand breaks (DSB), and growth in soft agar. We found that after the first treatment, Lead Chromate-treated cells exhibited a normal chromosome complement though a few clones showed a decrease in cell survival. After the second exposure, more than half of the clones acquired an abnormal karyotype including numerical and structural changes. The third treatment resulted in additional abnormal clones as well as previously abnormal clones acquiring more abnormalities. Clones were treated with soluble Cr(VI) for 24 h followed by a 24 h recovery period to measure DNA DSB repair. Abnormal clones showed persistent H2A.X and 53BP1 foci formation after 24 h recovery suggesting that these clones had acquired a DNA DSB repair-deficient phenotype. In addition, clones from the third generation were able to form colonies in soft agar suggesting that the cells have neoplastically transformed. This work was supported by NIEHS grant ES016893 (J.P.W.) and the Maine Center for Toxicology and Environmental Health. Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 103rd Annual Meeting of the American Association for Cancer Research; 2012 Mar 31-Apr 4; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2012;72(8 Suppl):Abstract nr 3102. doi:1538-7445.AM2012-3102
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The cytotoxicity and genotoxicity of hexavalent chromium in Steller sea lion lung fibroblasts compared to human lung fibroblasts.
Comparative Biochemistry and Physiology C-toxicology & Pharmacology, 2010Co-Authors: John Pierce Wise, Carolyne Lacerte, Sandra S Wise, Amie L Holmes, Fariba Shaffiey, Abouel-makarim AboueissaAbstract:Abstract In this study we directly compared soluble and particulate Chromate cytotoxicity and genotoxicity in human (Homo sapiens) and sea lion (Eumetopias jubatus) lung fibroblasts. Our results show that hexavalent chromium induces increased cell death and chromosome damage in both human and sea lion cells with increasing intracellular chromium ion levels. The data further indicate that both sodium Chromate and Lead Chromate are less cytotoxic and genotoxic to sea lion cells than human cells, based on an administered dose. Differences in chromium ion uptake explained some but not all of the reduced amounts of sodium Chromate-induced cell death. By contrast, uptake differences could explain the differences in sodium Chromate-induced chromosome damage and particulate Chromate-induced toxicity. Altogether they indicate that while hexavalent chromium induces similar toxic effects in sea lion and human cells, there are different mechanisms underlying the toxic outcomes.
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neoplastic transformation of human bronchial cells by Lead Chromate particles
American Journal of Respiratory Cell and Molecular Biology, 2007Co-Authors: Hong Xie, Sandra S Wise, Amie L Holmes, Shouping Huang, Cheng Peng, John Pierce WiseAbstract:Particulate hexavalent chromium (Cr(VI)) is a well-established human lung carcinogen with widespread exposure among people in occupational settings and the general public. However, no studies have examined the Chromate-induced malignant transformation of human lung epithelial cells, its predominant target. Human papillomavirus–immortalized human bronchial epithelial (BEP2D) cells were used to better understand the mechanisms involved in human bronchial carcinogenesis induced by particulate Chromate. We found that aneuploid cells increased in a concentrationdependent manner after chronic exposure to Lead Chromate. Moreover, chronic exposure to Lead Chromate induced BEP2D cell transformation. Transformed BEP2D cells developed through a series of sequential steps, including altered cell morphology, loss of cell contact inhibition and anchorage-independent growth. Specifically, a 5-day exposure to Lead Chromate induced foci formation with 0, 1, 5, and 10 mg/cm 2 Lead Chromate inducing 0, 7, 3, and 15 foci in 10 dishes. Anchorage independence was observed in cell lines derived from these foci. These foci-derived cells also showed centrosome amplification and increases in aneuploid metaphases. Our study demonstrates that particulate Cr(VI) is able to transform human bronchial epithelial cells, and that chromosome instability may play an important role in particulate Cr(VI)-induced neoplastic trans
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role of the fancg gene in protecting cells from particulate Chromate induced chromosome instability
Mutation Research-genetic Toxicology and Environmental Mutagenesis, 2007Co-Authors: Laura C Savery, Sandra S Wise, Eliza Grlickovaduzevik, Douglas W Thompson, John M Hinz, Larry H Thompson, John Pierce WiseAbstract:Particulate hexavalent chromium (Cr(VI)) is a known human lung carcinogen. Cr(VI)-induced tumors exhibit chromosome instability (CIN), but the mechanisms underlying these effects are unknown. We investigated a possible role for the Fanconi anemia (FA) pathway in particulate Cr(VI)-induced chromosomal damage by focusing on the Fancg gene, which plays an important role in cellular resistance to DNA interstrand crosslinks. We used the isogenic Chinese hamster ovary (CHO) KO40 fancg mutant compared with parental and gene-complemented cells. We found that fancg cells treated with Lead Chromate had lower intracellular Cr ion levels than control cell lines. Accounting for differences of Cr ion levels between cell lines, we discovered that fancg cells treated with Lead Chromate had increased cytotoxicity and chromosomal aberrations, which was not observed after restoring the Fancg gene. Chromosomal damage was manifest as increased total chromosome damage and percent metaphases with damage, specifically an increase in chromatid and isochromatid breaks. We conclude that Fancg protects cells from particulate Cr(VI)-induced cytotoxicity and chromosome damage, which is consistent with the known sensitivity of fancg cells to crosslinking damage and the ability of Cr(VI) to produce crosslinks.
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the clastogenic effects of chronic exposure to particulate and soluble cr vi in human lung cells
Mutation Research-genetic Toxicology and Environmental Mutagenesis, 2006Co-Authors: Amie L Holmes, Sandra S Wise, Sarah J Sandwick, John Pierce WiseAbstract:Hexavalent chromium (Cr(VI)) is a well-designated human lung carcinogen, with solubility playing an important role in its carcinogenic potential. Although it is known that particulate or water-insoluble Cr(VI) compounds are more potent than the soluble species of this metal, the mechanisms of action are not fully elucidated. In this study, we investigated the hypothesis that the difference in potency between particulate and soluble Cr(VI) is due to more chronic exposures with particulate Chromate because it can deposit and persist in the lungs while soluble Chromate is rapidly cleared. Chronic exposure to both insoluble Lead Chromate and soluble sodium Chromate induced a concentration and time-dependent increase in intracellular Cr ion concentrations in cultured human lung fibroblasts. Intracellular Pb levels after chronic exposure to Lead Chromate increased in a concentration-dependent manner but did not increase with longer exposure times up to 72 h. We also investigated the effects of chronic exposure to Cr(VI) on clastogenicity and found that chronic exposure to Lead Chromate induces persistent or increasing chromosome damage. Specifically, exposure to 0.5 microg/cm(2) Lead Chromate for 24, 48 and 72 h induced 23, 23 and 27% damaged metaphases, respectively. Contrary to Lead Chromate, the amount of chromosome damage after chronic exposure to sodium Chromate decreased with time. For example, cells exposed to 1 microM sodium Chromate for 24, 48 and 72 h induced 23, 13 and 17% damaged metaphases, respectively. Our data suggest a possible mechanism for the observed potency difference between soluble and insoluble Cr(VI) compounds is that chronic exposure to particulate Cr(VI) induces persistent chromosome damage and chromosome instability while chromosome damage is repaired with chronic exposure to soluble Cr(VI).
Amie L Holmes - One of the best experts on this subject based on the ideXlab platform.
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abstract 3102 hexavalent chromium induces chromosome instability Leading to dna double strand break repair deficiency and neoplastic transformation
Cancer Research, 2012Co-Authors: Sandra S Wise, Amie L Holmes, Douglas W Thompson, Hong Xie, John Pierce WiseAbstract:Proceedings: AACR 103rd Annual Meeting 2012‐‐ Mar 31‐Apr 4, 2012; Chicago, IL Chromosome instability (CIN) is a hallmark of lung cancer with cells exhibiting both translocations and aneuploidy. Hexavalent chromium (Cr(VI)) is a well known respiratory carcinogen. The ability of Cr(VI) to induce chromosomal translocations is unknown. We exposed human lung cells to Lead Chromate for three sequential 24 h periods, each separated by about a month. After each treatment, cells were seeded at colony forming density, cloned, expanded and retreated. Each generation of clones was tested for chromium sensitivity, chromosome complement, ability to repair DNA double strand breaks (DSB), and growth in soft agar. We found that after the first treatment, Lead Chromate-treated cells exhibited a normal chromosome complement though a few clones showed a decrease in cell survival. After the second exposure, more than half of the clones acquired an abnormal karyotype including numerical and structural changes. The third treatment resulted in additional abnormal clones as well as previously abnormal clones acquiring more abnormalities. Clones were treated with soluble Cr(VI) for 24 h followed by a 24 h recovery period to measure DNA DSB repair. Abnormal clones showed persistent H2A.X and 53BP1 foci formation after 24 h recovery suggesting that these clones had acquired a DNA DSB repair-deficient phenotype. In addition, clones from the third generation were able to form colonies in soft agar suggesting that the cells have neoplastically transformed. This work was supported by NIEHS grant ES016893 (J.P.W.) and the Maine Center for Toxicology and Environmental Health. Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 103rd Annual Meeting of the American Association for Cancer Research; 2012 Mar 31-Apr 4; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2012;72(8 Suppl):Abstract nr 3102. doi:1538-7445.AM2012-3102
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The cytotoxicity and genotoxicity of hexavalent chromium in Steller sea lion lung fibroblasts compared to human lung fibroblasts.
Comparative Biochemistry and Physiology C-toxicology & Pharmacology, 2010Co-Authors: John Pierce Wise, Carolyne Lacerte, Sandra S Wise, Amie L Holmes, Fariba Shaffiey, Abouel-makarim AboueissaAbstract:Abstract In this study we directly compared soluble and particulate Chromate cytotoxicity and genotoxicity in human (Homo sapiens) and sea lion (Eumetopias jubatus) lung fibroblasts. Our results show that hexavalent chromium induces increased cell death and chromosome damage in both human and sea lion cells with increasing intracellular chromium ion levels. The data further indicate that both sodium Chromate and Lead Chromate are less cytotoxic and genotoxic to sea lion cells than human cells, based on an administered dose. Differences in chromium ion uptake explained some but not all of the reduced amounts of sodium Chromate-induced cell death. By contrast, uptake differences could explain the differences in sodium Chromate-induced chromosome damage and particulate Chromate-induced toxicity. Altogether they indicate that while hexavalent chromium induces similar toxic effects in sea lion and human cells, there are different mechanisms underlying the toxic outcomes.
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neoplastic transformation of human bronchial cells by Lead Chromate particles
American Journal of Respiratory Cell and Molecular Biology, 2007Co-Authors: Hong Xie, Sandra S Wise, Amie L Holmes, Shouping Huang, Cheng Peng, John Pierce WiseAbstract:Particulate hexavalent chromium (Cr(VI)) is a well-established human lung carcinogen with widespread exposure among people in occupational settings and the general public. However, no studies have examined the Chromate-induced malignant transformation of human lung epithelial cells, its predominant target. Human papillomavirus–immortalized human bronchial epithelial (BEP2D) cells were used to better understand the mechanisms involved in human bronchial carcinogenesis induced by particulate Chromate. We found that aneuploid cells increased in a concentrationdependent manner after chronic exposure to Lead Chromate. Moreover, chronic exposure to Lead Chromate induced BEP2D cell transformation. Transformed BEP2D cells developed through a series of sequential steps, including altered cell morphology, loss of cell contact inhibition and anchorage-independent growth. Specifically, a 5-day exposure to Lead Chromate induced foci formation with 0, 1, 5, and 10 mg/cm 2 Lead Chromate inducing 0, 7, 3, and 15 foci in 10 dishes. Anchorage independence was observed in cell lines derived from these foci. These foci-derived cells also showed centrosome amplification and increases in aneuploid metaphases. Our study demonstrates that particulate Cr(VI) is able to transform human bronchial epithelial cells, and that chromosome instability may play an important role in particulate Cr(VI)-induced neoplastic trans
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the clastogenic effects of chronic exposure to particulate and soluble cr vi in human lung cells
Mutation Research-genetic Toxicology and Environmental Mutagenesis, 2006Co-Authors: Amie L Holmes, Sandra S Wise, Sarah J Sandwick, John Pierce WiseAbstract:Hexavalent chromium (Cr(VI)) is a well-designated human lung carcinogen, with solubility playing an important role in its carcinogenic potential. Although it is known that particulate or water-insoluble Cr(VI) compounds are more potent than the soluble species of this metal, the mechanisms of action are not fully elucidated. In this study, we investigated the hypothesis that the difference in potency between particulate and soluble Cr(VI) is due to more chronic exposures with particulate Chromate because it can deposit and persist in the lungs while soluble Chromate is rapidly cleared. Chronic exposure to both insoluble Lead Chromate and soluble sodium Chromate induced a concentration and time-dependent increase in intracellular Cr ion concentrations in cultured human lung fibroblasts. Intracellular Pb levels after chronic exposure to Lead Chromate increased in a concentration-dependent manner but did not increase with longer exposure times up to 72 h. We also investigated the effects of chronic exposure to Cr(VI) on clastogenicity and found that chronic exposure to Lead Chromate induces persistent or increasing chromosome damage. Specifically, exposure to 0.5 microg/cm(2) Lead Chromate for 24, 48 and 72 h induced 23, 23 and 27% damaged metaphases, respectively. Contrary to Lead Chromate, the amount of chromosome damage after chronic exposure to sodium Chromate decreased with time. For example, cells exposed to 1 microM sodium Chromate for 24, 48 and 72 h induced 23, 13 and 17% damaged metaphases, respectively. Our data suggest a possible mechanism for the observed potency difference between soluble and insoluble Cr(VI) compounds is that chronic exposure to particulate Cr(VI) induces persistent chromosome damage and chromosome instability while chromosome damage is repaired with chronic exposure to soluble Cr(VI).
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chronic exposure to Lead Chromate causes centrosome abnormalities and aneuploidy in human lung cells
Cancer Research, 2006Co-Authors: Amie L Holmes, Sandra S Wise, Douglas W Thompson, Sarah J Sandwick, Wilma L Lingle, Vivian Negron, John Pierce WiseAbstract:Hexavalent chromium [Cr(VI)] compounds are established human lung carcinogens. The carcinogenicity of Cr(VI) is related to its solubility, with the most potent carcinogens being the insoluble particulate Cr(VI) compounds. However, it remains unknown why particulate Cr(VI) is more carcinogenic than soluble Cr(VI). One possible explanation is that particulates may provide more chronic exposures to Chromate over time. We found that aneuploid cells increased in a concentration- and time-dependent manner after chronic exposure to Lead Chromate. Specifically, a 24-hour Lead Chromate exposure induced no aneugenic effect, whereas a 120-hour exposure to 0.5 and 1 microg/cm2 Lead Chromate induced 55% and 60% aneuploid metaphases, respectively. We also found that many of these aneuploid cells were able to continue to grow and form colonies. Centrosome defects are known to induce aneuploidy; therefore, we investigated the effects of chronic Lead Chromate exposure on centrosomes. We found that centrosome amplification in interphase and mitotic cells increased in a concentration- and time-dependent manner with 0.5 and 1 microg/cm2 Lead Chromate for 120 hours, inducing aberrant centrosomes in 18% and 21% of interphase cells and 32% and 69% of mitotic cells, respectively; however, Lead oxide did not induce centrosome amplification in interphase or mitotic cells. There was also an increase in aberrant mitosis after chronic exposure to Lead Chromate with the emergence of disorganized anaphase and mitotic catastrophe. These data suggest that one possible mechanism for Lead Chromate-induced carcinogenesis is through centrosome dysfunction, Leading to the induction of aneuploidy.
Letizia Monico - One of the best experts on this subject based on the ideXlab platform.
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chromium speciation methods and infrared spectroscopy for studying the chemical reactivity of Lead Chromate based pigments in oil medium
Microchemical Journal, 2016Co-Authors: Letizia Monico, Marine Cotte, Koen Janssens, Lorenzo Sorace, Frederik Vanmeert, Brunetto Giovanni Brunetti, Costanza MilianiAbstract:Abstract Environmental factors, such as light, humidity and temperature are triggering agents for the alteration of organic and/or inorganic constituents of oil paintings. The oxidation of the organic material is favored by increasing of relative humidity and temperature, whereas processes involving changes of the oxidation states of a number of inorganic pigments ( e.g. , vermilion, cadmium yellows, zinc yellows, chrome yellows) are mainly activated by light-exposure. In view of the optimization of the long-term conservation and restoration strategies of paintings it is of relevant interest to establish the consequences of thermal parameters (temperature and relative humidity) on the chemical/photochemical-reactivity and the nature of the alteration products of light sensitive-pigments in oil medium. To this aim here we propose a multi-method analytical approach based on the combination of diffuse reflectance UV–Vis, FTIR, synchrotron radiation (SR)-based micro X-ray fluorescence (μ-XRF)/micro-X-ray absorption near edge structure (XANES) and electron paramagnetic resonance (EPR) spectroscopies for studying the effects of different relative humidity conditions before and after light exposure on the reactivity of a series of Lead Chromate-based pigments [such as PbCrO 4 ∙ PbO (monoclinic), PbCrO 4 (monoclinic) and PbCr 0.2 S 0.8 O 4 (orthorhombic)] in an oil medium. The investigation of paint models was also compared to that of a late 19th century historical orthorhombic PbCr 0.4 S 0.6 O 4 oil paint. Diffuse reflectance UV–Vis and FTIR spectroscopies were used to obtain information associated with chromatic changes and the formation of organo-metal degradation products at the paint surface. SR-based Cr K-edge μ-XANES/μ-XRF mapping analysis and EPR spectroscopy were employed in a complementary fashion to determine the amount, nature and distribution of Cr(III) and Cr(V)-based alteration compounds within the paints with micrometric spatial resolution. Under the employed thermal aging conditions, Lead(II)-carboxylates and reduced Cr-compounds (in abundance of up to about 35% at the surface) have been identified in the Lead Chromate-based paints. The tendency of Chromates to become reduced increased with increasing moisture levels and was favored for the orthorhombic PbCr 0.2 S 0.8 O 4 compounds. The redox process gave rise to the formation of Cr(V)-species in relative amount much higher than that was formed in the equivalent paint which was exposed only to light. After light-exposure of the thermally aged paints, compounds ascribable to the oxidation of the organic binder were detected for all the types of pigments. Nevertheless, the previous thermal treatment increased the tendency toward photo-reduction of only the PbCr 0.2 S 0.8 O 4 pigment. For this light-sensitive compound, the thickness variation of the reduced Cr-rich ( ca. 70%) photo-alteration layer with moisture levels could be ascribed to a surface passivation phenomenon that had already occurred before photochemical aging.
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synchrotron based x ray spectromicroscopy and electron paramagnetic resonance spectroscopy to investigate the redox properties of Lead Chromate pigments under the effect of visible light
Journal of Analytical Atomic Spectrometry, 2015Co-Authors: Letizia Monico, Marine Cotte, Koen Janssens, Lorenzo Sorace, Brunetto Giovanni Brunetti, A Romani, Chiara Grazia, Costanza MilianiAbstract:Correction for ‘Synchrotron-based X-ray spectromicroscopy and electron paramagnetic resonance spectroscopy to investigate the redox properties of Lead Chromate pigments under the effect of visible light’ by Letizia Monico et al., J. Anal. At. Spectrom., 2015, 30, 1500–1510.
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degradation process of Lead Chromate in paintings by vincent van gogh studied by means of spectromicroscopic methods part 5 effects of nonoriginal surface coatings into the nature and distribution of chromium and sulfur species in chrome yellow paints
Analytical Chemistry, 2014Co-Authors: Letizia Monico, Marine Cotte, Geert Van Der Snickt, Koen Janssens, Frederik Vanmeert, Brunetto Giovanni Brunetti, Margje Leeuwestein, Johanna Salvant Plisson, Michel Menu, Costanza MilianiAbstract:The darkening of Lead Chromate yellow pigments, caused by a reduction of the Chromate ions to Cr(III) compounds, is known to affect the appearance of several paintings by Vincent van Gogh. In previous papers of this series, we demonstrated that the darkening is activated by light and depends on the chemical composition and crystalline structure of the pigments. In this work, the results of Part 2 are extended and complemented with a new study aimed at deepening the knowledge of the nature and distribution of Cr and S species at the interface between the chrome yellow paint and the nonoriginal coating layer. For this purpose, three microsamples from two varnished paintings by Van Gogh and a waxed low relief by Gauguin (all originally uncoated) have been examined. Because nonoriginal coatings are often present in artwork by Van Gogh and contemporaries, the understanding of whether or not their application has influenced the morphological and/or physicochemical properties of the chrome yellow paint underneath is relevant in view of the conservation of these masterpieces. In all the samples studied, microscopic X-ray fluorescence (μ-XRF) and X-ray absorption near edge structure (μ-XANES) investigations showed that Cr(III)-based alteration products are present in the form of grains inside the coating (generally enriched of S species) and also homogeneously widespread at the paint surface. The distribution of Cr(III) species may be explained by the mechanical friction caused by the coating application by brush that picked up and redistributed the superficial Cr compounds, likely already present in the reduced state as result of the photodegradation process. The analysis of the XANES profiles allowed us to obtain new insights into the nature of the Cr(III) alteration products, that were identified as sulfate-, oxide-, organo-metal-, and chloride-based compounds. Building upon the knowledge acquired through the examination of original paint samples and from the investigation of aged model paints in the last Part 4 paper, in this study we aim to characterize a possible relation between the chemical composition of the coating and the chrome yellow degradation pathways by studying photochemically aged model samples covered with a dammar varnish contaminated with sulfide and sulfate salts. Cr speciation results did not show any evidence of the active role of the varnish and added S species on the reduction process of chrome yellows.
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Degradation Process of Lead Chromate in Paintings by Vincent van Gogh Studied by Means of Spectromicroscopic Methods. Part 5. Effects of Nonoriginal Surface Coatings into the Nature and Distribution of Chromium and Sulfur Species in Chrome Yellow Paints
2014Co-Authors: Letizia Monico, Marine Cotte, Geert Van Der Snickt, Koen Janssens, Frederik Vanmeert, Brunetto Giovanni Brunetti, Margje Leeuwestein, Johanna Salvant Plisson, Michel Menu, Costanza MilianiAbstract:The darkening of Lead Chromate yellow pigments, caused by a reduction of the Chromate ions to Cr(III) compounds, is known to affect the appearance of several paintings by Vincent van Gogh. In previous papers of this series, we demonstrated that the darkening is activated by light and depends on the chemical composition and crystalline structure of the pigments. In this work, the results of Part 2 are extended and complemented with a new study aimed at deepening the knowledge of the nature and distribution of Cr and S species at the interface between the chrome yellow paint and the nonoriginal coating layer. For this purpose, three microsamples from two varnished paintings by Van Gogh and a waxed low relief by Gauguin (all originally uncoated) have been examined. Because nonoriginal coatings are often present in artwork by Van Gogh and contemporaries, the understanding of whether or not their application has influenced the morphological and/or physicochemical properties of the chrome yellow paint underneath is relevant in view of the conservation of these masterpieces. In all the samples studied, microscopic X-ray fluorescence (μ-XRF) and X-ray absorption near edge structure (μ-XANES) investigations showed that Cr(III)-based alteration products are present in the form of grains inside the coating (generally enriched of S species) and also homogeneously widespread at the paint surface. The distribution of Cr(III) species may be explained by the mechanical friction caused by the coating application by brush that picked up and redistributed the superficial Cr compounds, likely already present in the reduced state as result of the photodegradation process. The analysis of the XANES profiles allowed us to obtain new insights into the nature of the Cr(III) alteration products, that were identified as sulfate-, oxide-, organo-metal-, and chloride-based compounds. Building upon the knowledge acquired through the examination of original paint samples and from the investigation of aged model paints in the last Part 4 paper, in this study we aim to characterize a possible relation between the chemical composition of the coating and the chrome yellow degradation pathways by studying photochemically aged model samples covered with a dammar varnish contaminated with sulfide and sulfate salts. Cr speciation results did not show any evidence of the active role of the varnish and added S species on the reduction process of chrome yellows
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degradation process of Lead Chromate in paintings by vincent van gogh studied by means of spectromicroscopic methods 4 artificial aging of model samples of co precipitates of Lead Chromate and Lead sulfate
Analytical Chemistry, 2013Co-Authors: Letizia Monico, Costanza Miliani, Koe Janssens, Marie Radepont, Brunetto Giovanni Brunetti, Geert Van Der Snickt, Mariangela Cestelli Guidi, Marine CotteAbstract:Previous investigations about the darkening of chrome yellow pigments revealed that this form of alteration is attributable to a reduction of the original Cr(VI) to Cr(III), and that the presence of sulfur-containing compounds, most often sulfates, plays a key role during this process. We recently demonstrated that different crystal forms of chrome yellow pigments (PbCrO4 and PbCr1–xSxO4) are present in paintings by Vincent van Gogh. In the present work, we show how both the chemical composition and the crystalline structure of Lead Chromate-based pigments influence their stability. For this purpose, oil model samples made with in-house synthesized powders of PbCrO4 and PbCr1–xSxO4 were artificially aged and characterized. We observed a profound darkening only for those paint models made with PbCr1–xSxO4, rich in SO42– (x ≥ 0.4), and orthorhombic phases (>30 wt %). Cr and S K-edge micro X-ray absorption near edge structure investigations revealed in an unequivocal manner the formation of up to about 60% o...
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chromium speciation methods and infrared spectroscopy for studying the chemical reactivity of Lead Chromate based pigments in oil medium
Microchemical Journal, 2016Co-Authors: Letizia Monico, Marine Cotte, Koen Janssens, Lorenzo Sorace, Frederik Vanmeert, Brunetto Giovanni Brunetti, Costanza MilianiAbstract:Abstract Environmental factors, such as light, humidity and temperature are triggering agents for the alteration of organic and/or inorganic constituents of oil paintings. The oxidation of the organic material is favored by increasing of relative humidity and temperature, whereas processes involving changes of the oxidation states of a number of inorganic pigments ( e.g. , vermilion, cadmium yellows, zinc yellows, chrome yellows) are mainly activated by light-exposure. In view of the optimization of the long-term conservation and restoration strategies of paintings it is of relevant interest to establish the consequences of thermal parameters (temperature and relative humidity) on the chemical/photochemical-reactivity and the nature of the alteration products of light sensitive-pigments in oil medium. To this aim here we propose a multi-method analytical approach based on the combination of diffuse reflectance UV–Vis, FTIR, synchrotron radiation (SR)-based micro X-ray fluorescence (μ-XRF)/micro-X-ray absorption near edge structure (XANES) and electron paramagnetic resonance (EPR) spectroscopies for studying the effects of different relative humidity conditions before and after light exposure on the reactivity of a series of Lead Chromate-based pigments [such as PbCrO 4 ∙ PbO (monoclinic), PbCrO 4 (monoclinic) and PbCr 0.2 S 0.8 O 4 (orthorhombic)] in an oil medium. The investigation of paint models was also compared to that of a late 19th century historical orthorhombic PbCr 0.4 S 0.6 O 4 oil paint. Diffuse reflectance UV–Vis and FTIR spectroscopies were used to obtain information associated with chromatic changes and the formation of organo-metal degradation products at the paint surface. SR-based Cr K-edge μ-XANES/μ-XRF mapping analysis and EPR spectroscopy were employed in a complementary fashion to determine the amount, nature and distribution of Cr(III) and Cr(V)-based alteration compounds within the paints with micrometric spatial resolution. Under the employed thermal aging conditions, Lead(II)-carboxylates and reduced Cr-compounds (in abundance of up to about 35% at the surface) have been identified in the Lead Chromate-based paints. The tendency of Chromates to become reduced increased with increasing moisture levels and was favored for the orthorhombic PbCr 0.2 S 0.8 O 4 compounds. The redox process gave rise to the formation of Cr(V)-species in relative amount much higher than that was formed in the equivalent paint which was exposed only to light. After light-exposure of the thermally aged paints, compounds ascribable to the oxidation of the organic binder were detected for all the types of pigments. Nevertheless, the previous thermal treatment increased the tendency toward photo-reduction of only the PbCr 0.2 S 0.8 O 4 pigment. For this light-sensitive compound, the thickness variation of the reduced Cr-rich ( ca. 70%) photo-alteration layer with moisture levels could be ascribed to a surface passivation phenomenon that had already occurred before photochemical aging.
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synchrotron based x ray spectromicroscopy and electron paramagnetic resonance spectroscopy to investigate the redox properties of Lead Chromate pigments under the effect of visible light
Journal of Analytical Atomic Spectrometry, 2015Co-Authors: Letizia Monico, Marine Cotte, Koen Janssens, Lorenzo Sorace, Brunetto Giovanni Brunetti, A Romani, Chiara Grazia, Costanza MilianiAbstract:Correction for ‘Synchrotron-based X-ray spectromicroscopy and electron paramagnetic resonance spectroscopy to investigate the redox properties of Lead Chromate pigments under the effect of visible light’ by Letizia Monico et al., J. Anal. At. Spectrom., 2015, 30, 1500–1510.
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degradation process of Lead Chromate in paintings by vincent van gogh studied by means of spectromicroscopic methods part 5 effects of nonoriginal surface coatings into the nature and distribution of chromium and sulfur species in chrome yellow paints
Analytical Chemistry, 2014Co-Authors: Letizia Monico, Marine Cotte, Geert Van Der Snickt, Koen Janssens, Frederik Vanmeert, Brunetto Giovanni Brunetti, Margje Leeuwestein, Johanna Salvant Plisson, Michel Menu, Costanza MilianiAbstract:The darkening of Lead Chromate yellow pigments, caused by a reduction of the Chromate ions to Cr(III) compounds, is known to affect the appearance of several paintings by Vincent van Gogh. In previous papers of this series, we demonstrated that the darkening is activated by light and depends on the chemical composition and crystalline structure of the pigments. In this work, the results of Part 2 are extended and complemented with a new study aimed at deepening the knowledge of the nature and distribution of Cr and S species at the interface between the chrome yellow paint and the nonoriginal coating layer. For this purpose, three microsamples from two varnished paintings by Van Gogh and a waxed low relief by Gauguin (all originally uncoated) have been examined. Because nonoriginal coatings are often present in artwork by Van Gogh and contemporaries, the understanding of whether or not their application has influenced the morphological and/or physicochemical properties of the chrome yellow paint underneath is relevant in view of the conservation of these masterpieces. In all the samples studied, microscopic X-ray fluorescence (μ-XRF) and X-ray absorption near edge structure (μ-XANES) investigations showed that Cr(III)-based alteration products are present in the form of grains inside the coating (generally enriched of S species) and also homogeneously widespread at the paint surface. The distribution of Cr(III) species may be explained by the mechanical friction caused by the coating application by brush that picked up and redistributed the superficial Cr compounds, likely already present in the reduced state as result of the photodegradation process. The analysis of the XANES profiles allowed us to obtain new insights into the nature of the Cr(III) alteration products, that were identified as sulfate-, oxide-, organo-metal-, and chloride-based compounds. Building upon the knowledge acquired through the examination of original paint samples and from the investigation of aged model paints in the last Part 4 paper, in this study we aim to characterize a possible relation between the chemical composition of the coating and the chrome yellow degradation pathways by studying photochemically aged model samples covered with a dammar varnish contaminated with sulfide and sulfate salts. Cr speciation results did not show any evidence of the active role of the varnish and added S species on the reduction process of chrome yellows.
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Degradation Process of Lead Chromate in Paintings by Vincent van Gogh Studied by Means of Spectromicroscopic Methods. Part 5. Effects of Nonoriginal Surface Coatings into the Nature and Distribution of Chromium and Sulfur Species in Chrome Yellow Paints
2014Co-Authors: Letizia Monico, Marine Cotte, Geert Van Der Snickt, Koen Janssens, Frederik Vanmeert, Brunetto Giovanni Brunetti, Margje Leeuwestein, Johanna Salvant Plisson, Michel Menu, Costanza MilianiAbstract:The darkening of Lead Chromate yellow pigments, caused by a reduction of the Chromate ions to Cr(III) compounds, is known to affect the appearance of several paintings by Vincent van Gogh. In previous papers of this series, we demonstrated that the darkening is activated by light and depends on the chemical composition and crystalline structure of the pigments. In this work, the results of Part 2 are extended and complemented with a new study aimed at deepening the knowledge of the nature and distribution of Cr and S species at the interface between the chrome yellow paint and the nonoriginal coating layer. For this purpose, three microsamples from two varnished paintings by Van Gogh and a waxed low relief by Gauguin (all originally uncoated) have been examined. Because nonoriginal coatings are often present in artwork by Van Gogh and contemporaries, the understanding of whether or not their application has influenced the morphological and/or physicochemical properties of the chrome yellow paint underneath is relevant in view of the conservation of these masterpieces. In all the samples studied, microscopic X-ray fluorescence (μ-XRF) and X-ray absorption near edge structure (μ-XANES) investigations showed that Cr(III)-based alteration products are present in the form of grains inside the coating (generally enriched of S species) and also homogeneously widespread at the paint surface. The distribution of Cr(III) species may be explained by the mechanical friction caused by the coating application by brush that picked up and redistributed the superficial Cr compounds, likely already present in the reduced state as result of the photodegradation process. The analysis of the XANES profiles allowed us to obtain new insights into the nature of the Cr(III) alteration products, that were identified as sulfate-, oxide-, organo-metal-, and chloride-based compounds. Building upon the knowledge acquired through the examination of original paint samples and from the investigation of aged model paints in the last Part 4 paper, in this study we aim to characterize a possible relation between the chemical composition of the coating and the chrome yellow degradation pathways by studying photochemically aged model samples covered with a dammar varnish contaminated with sulfide and sulfate salts. Cr speciation results did not show any evidence of the active role of the varnish and added S species on the reduction process of chrome yellows
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degradation process of Lead Chromate in paintings by vincent van gogh studied by means of spectromicroscopic methods 4 artificial aging of model samples of co precipitates of Lead Chromate and Lead sulfate
Analytical Chemistry, 2013Co-Authors: Letizia Monico, Costanza Miliani, Koe Janssens, Marie Radepont, Brunetto Giovanni Brunetti, Geert Van Der Snickt, Mariangela Cestelli Guidi, Marine CotteAbstract:Previous investigations about the darkening of chrome yellow pigments revealed that this form of alteration is attributable to a reduction of the original Cr(VI) to Cr(III), and that the presence of sulfur-containing compounds, most often sulfates, plays a key role during this process. We recently demonstrated that different crystal forms of chrome yellow pigments (PbCrO4 and PbCr1–xSxO4) are present in paintings by Vincent van Gogh. In the present work, we show how both the chemical composition and the crystalline structure of Lead Chromate-based pigments influence their stability. For this purpose, oil model samples made with in-house synthesized powders of PbCrO4 and PbCr1–xSxO4 were artificially aged and characterized. We observed a profound darkening only for those paint models made with PbCr1–xSxO4, rich in SO42– (x ≥ 0.4), and orthorhombic phases (>30 wt %). Cr and S K-edge micro X-ray absorption near edge structure investigations revealed in an unequivocal manner the formation of up to about 60% o...