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Toshihiko Kasahara - One of the best experts on this subject based on the ideXlab platform.
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improving predictive capacity of the amino acid derivative reactivity assay test method for skin sensitization potential with an optimal Molar Concentration of test chemical solution
Journal of Applied Toxicology, 2021Co-Authors: Mika Imamura, Sayaka Wanibuchi, Toshihiko Kasahara, Yusuke Yamamoto, Hajime Kojima, Atsushi Ono, Masaharu FujitaAbstract:The Amino acid Derivative Reactivity Assay (ADRA) is a convenient and effective in chemico test method for assessing covalent binding of test chemicals with protein-derived nucleophilic reagents as a means of predicting skin sensitization potential. Although the original Molar-Concentration approach to ADRA testing was not suitable for testing multiconstituent substances of an unknown composition, a weight-Concentration approach that is suitable for such substances was developed, which also led to the realization that test chemical solutions prepared to Molar Concentrations higher than the original 1 mM would reduce false negative results as well as enhance predictive capacity. The present study determined an optimal Molar-Concentration that achieves even higher predictive capacity than the original ADRA. Eight chemicals that were false negatives when tested with 1 mM test chemical solutions were retested with test chemical solutions between 2 and 5 mM, which showed 4 mM to be the optimal Molar-Concentration for ADRA testing. When 82 chemicals used in the original development were retested with 4 mM test chemical solutions, false negative results were reduced by four. When an additional 85 chemicals used to evaluate the weight-Concentration approach to ADRA were retested, the results essentially replicated those obtained with 0.5 mg/ml test chemical solutions and gave 10 fewer false negatives than original ADRA with 1 mM solutions. A comparison of these results for 136 chemicals showed that ADRA testing with 4 mM solutions achieved a four percentage point improvement in accuracy over original ADRA and a two percentage point improvement over DPRA testing.
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expanding the applicability of the amino acid derivative reactivity assay determining a weight for preparation of test chemical solutions that yield a predictive capacity identical to the conventional method using Molar Concentration and demonstratin
Journal of Pharmacological and Toxicological Methods, 2019Co-Authors: Yusuke Yamamoto, Sayaka Wanibuchi, Yasuhiro Katsuoka, Masaru Fujita, Toshihiko KasaharaAbstract:Abstract Introduction The amino acid derivative reactivity assay (ADRA) is a novel in chemico alternative to animal testing for assessment of skin sensitization potential. The conventional ADRA protocol stipulates that test chemical solutions should be prepared to a specific Molar Concentration, allowing only for use of test chemicals with known molecular weights. Since many potential test substances are prepared by weight Concentration or contain multiple unknown chemicals, this study was conducted to verify if it is possible to accurately assess the sensitization potential of test chemical solutions prepared at a specific weight Concentration. Methods (1) Test chemical solutions for 82 chemicals were prepared at four different weight Concentrations. Results were evaluated for agreement with in vivo results. (2) A liquid mixture comprising ten different non-sensitizers was prepared at 1 mg/mL. Ten different sensitizers of varying sensitization potencies were added individually to this mixture. The resulting pseudobinary mixtures were tested to confirm that the sensitizers could be detected. Results (1) The accuracies for test chemical solutions prepared at 0.5 and 0.2 mg/mL were 87.8% and 86.6%, respectively, which were roughly equivalent to the accuracy of 86.6% achieved with a solution prepared at the conventional Molar Concentration of 1 mM. In contrast, the accuracies for solutions prepared at 0.1 and 0.05 mg/mL were 82.9% and 74.4%, respectively, both of which were lower than that obtained with the conventional method. (2) Sensitizers added to the liquid mixture at 0.5 mg/mL were all correctly detected. Discussion Preparing test chemical solutions at a weight Concentration of 0.5 mg/mL decreased false negatives and increased false positives while improving prediction accuracy, which suggests that the sensitization potential of mixtures can also be assessed with this method.
Yusuke Yamamoto - One of the best experts on this subject based on the ideXlab platform.
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improving predictive capacity of the amino acid derivative reactivity assay test method for skin sensitization potential with an optimal Molar Concentration of test chemical solution
Journal of Applied Toxicology, 2021Co-Authors: Mika Imamura, Sayaka Wanibuchi, Toshihiko Kasahara, Yusuke Yamamoto, Hajime Kojima, Atsushi Ono, Masaharu FujitaAbstract:The Amino acid Derivative Reactivity Assay (ADRA) is a convenient and effective in chemico test method for assessing covalent binding of test chemicals with protein-derived nucleophilic reagents as a means of predicting skin sensitization potential. Although the original Molar-Concentration approach to ADRA testing was not suitable for testing multiconstituent substances of an unknown composition, a weight-Concentration approach that is suitable for such substances was developed, which also led to the realization that test chemical solutions prepared to Molar Concentrations higher than the original 1 mM would reduce false negative results as well as enhance predictive capacity. The present study determined an optimal Molar-Concentration that achieves even higher predictive capacity than the original ADRA. Eight chemicals that were false negatives when tested with 1 mM test chemical solutions were retested with test chemical solutions between 2 and 5 mM, which showed 4 mM to be the optimal Molar-Concentration for ADRA testing. When 82 chemicals used in the original development were retested with 4 mM test chemical solutions, false negative results were reduced by four. When an additional 85 chemicals used to evaluate the weight-Concentration approach to ADRA were retested, the results essentially replicated those obtained with 0.5 mg/ml test chemical solutions and gave 10 fewer false negatives than original ADRA with 1 mM solutions. A comparison of these results for 136 chemicals showed that ADRA testing with 4 mM solutions achieved a four percentage point improvement in accuracy over original ADRA and a two percentage point improvement over DPRA testing.
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expanding the applicability of the amino acid derivative reactivity assay determining a weight for preparation of test chemical solutions that yield a predictive capacity identical to the conventional method using Molar Concentration and demonstratin
Journal of Pharmacological and Toxicological Methods, 2019Co-Authors: Yusuke Yamamoto, Sayaka Wanibuchi, Yasuhiro Katsuoka, Masaru Fujita, Toshihiko KasaharaAbstract:Abstract Introduction The amino acid derivative reactivity assay (ADRA) is a novel in chemico alternative to animal testing for assessment of skin sensitization potential. The conventional ADRA protocol stipulates that test chemical solutions should be prepared to a specific Molar Concentration, allowing only for use of test chemicals with known molecular weights. Since many potential test substances are prepared by weight Concentration or contain multiple unknown chemicals, this study was conducted to verify if it is possible to accurately assess the sensitization potential of test chemical solutions prepared at a specific weight Concentration. Methods (1) Test chemical solutions for 82 chemicals were prepared at four different weight Concentrations. Results were evaluated for agreement with in vivo results. (2) A liquid mixture comprising ten different non-sensitizers was prepared at 1 mg/mL. Ten different sensitizers of varying sensitization potencies were added individually to this mixture. The resulting pseudobinary mixtures were tested to confirm that the sensitizers could be detected. Results (1) The accuracies for test chemical solutions prepared at 0.5 and 0.2 mg/mL were 87.8% and 86.6%, respectively, which were roughly equivalent to the accuracy of 86.6% achieved with a solution prepared at the conventional Molar Concentration of 1 mM. In contrast, the accuracies for solutions prepared at 0.1 and 0.05 mg/mL were 82.9% and 74.4%, respectively, both of which were lower than that obtained with the conventional method. (2) Sensitizers added to the liquid mixture at 0.5 mg/mL were all correctly detected. Discussion Preparing test chemical solutions at a weight Concentration of 0.5 mg/mL decreased false negatives and increased false positives while improving prediction accuracy, which suggests that the sensitization potential of mixtures can also be assessed with this method.
Umesh Kumar Gaur - One of the best experts on this subject based on the ideXlab platform.
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effect of naoh Molar Concentration on optical and ferroelectric properties of zno nanostructures
Applied Surface Science, 2015Co-Authors: Prakash Chand, Anurag Gaur, Ashavani Kumar, Umesh Kumar GaurAbstract:Abstract The present study reports the effects of NaOH Concentrations in hydrothermally grown ZnO nanostructures on structural, optical and ferroelectric properties at different selected NaOH Molar Concentrations (3–7 M). X-ray diffraction, Raman and photoluminescence analysis confirms the formation of pure phase of ZnO. FESEM images show that the average grain size of ZnO nanostructures increases from 61 to 95 nm as Molar Concentration increases from 3 to 7 M, respectively. Transmission electron microscope analysis also reveals that an average grain size of ZnO nanostructures increases from 34 to 55 nm as Molarity increases from 3 to 7 M Concentrations. A significant reduction in the optical band gap is observed from 4.41 to 3.96 eV by increasing Molar Concentration from 3 to 7 M, respectively. The decrease in the band gap with Molar Concentration could be due to the increase of density of localize state in the conduction band. Furthermore, ferroelectricity is observed in ZnO nanostructures at room temperature which is interesting and adds an additional dimension to its applications.
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effect of naoh Molar Concentration on morphology optical and ferroelectric properties of hydrothermally grown cuo nanoplates
Materials Science in Semiconductor Processing, 2015Co-Authors: Prakash Chand, Anurag Gaur, Ashavani Kumar, Umesh Kumar GaurAbstract:Abstract In this paper, structural, morphology, optical and ferroelectric properties of well uniform rectangular shaped copper oxide nanoplates prepared by hydrothermal technique at different 3, 5 and 6 Molar Concentrations are reported. X-ray diffraction confirmed that CuO nanoplates have a monoclinic phase with lattice constants a =4.689 A, b =3.426 A, and c =5.132 A. Transmission electron microscope analysis reveals that in CuO nanoplates average length and width increases from 80 and 246 to 115 and 290 nm as the Molarities Concentration increases from 3 to 6 M. Selected area electron diffraction patterns confirm that the crystallinity of CuO nanostructures increases with increasing NaOH Concentrations. Photoluminescence and Raman spectrum also confirm the phase formation of CuO nanostructures. A significant decrease in optical band gap is found from 3.55 to 2.95 eV as Molar Concentration increases from 3 to 6 M, respectively. The refractive index ( n ), optical static ( e o ) and high frequency dielectric constant ( e ∞ ) values were calculated through energy band gap as function of Molar Concentration of NaOH solution. Moreover, room temperature ferroelectricity has been notice in hydrothermally grown CuO nanoplates which are interesting and adds a further dimension to its applications.
Sayaka Wanibuchi - One of the best experts on this subject based on the ideXlab platform.
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improving predictive capacity of the amino acid derivative reactivity assay test method for skin sensitization potential with an optimal Molar Concentration of test chemical solution
Journal of Applied Toxicology, 2021Co-Authors: Mika Imamura, Sayaka Wanibuchi, Toshihiko Kasahara, Yusuke Yamamoto, Hajime Kojima, Atsushi Ono, Masaharu FujitaAbstract:The Amino acid Derivative Reactivity Assay (ADRA) is a convenient and effective in chemico test method for assessing covalent binding of test chemicals with protein-derived nucleophilic reagents as a means of predicting skin sensitization potential. Although the original Molar-Concentration approach to ADRA testing was not suitable for testing multiconstituent substances of an unknown composition, a weight-Concentration approach that is suitable for such substances was developed, which also led to the realization that test chemical solutions prepared to Molar Concentrations higher than the original 1 mM would reduce false negative results as well as enhance predictive capacity. The present study determined an optimal Molar-Concentration that achieves even higher predictive capacity than the original ADRA. Eight chemicals that were false negatives when tested with 1 mM test chemical solutions were retested with test chemical solutions between 2 and 5 mM, which showed 4 mM to be the optimal Molar-Concentration for ADRA testing. When 82 chemicals used in the original development were retested with 4 mM test chemical solutions, false negative results were reduced by four. When an additional 85 chemicals used to evaluate the weight-Concentration approach to ADRA were retested, the results essentially replicated those obtained with 0.5 mg/ml test chemical solutions and gave 10 fewer false negatives than original ADRA with 1 mM solutions. A comparison of these results for 136 chemicals showed that ADRA testing with 4 mM solutions achieved a four percentage point improvement in accuracy over original ADRA and a two percentage point improvement over DPRA testing.
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expanding the applicability of the amino acid derivative reactivity assay determining a weight for preparation of test chemical solutions that yield a predictive capacity identical to the conventional method using Molar Concentration and demonstratin
Journal of Pharmacological and Toxicological Methods, 2019Co-Authors: Yusuke Yamamoto, Sayaka Wanibuchi, Yasuhiro Katsuoka, Masaru Fujita, Toshihiko KasaharaAbstract:Abstract Introduction The amino acid derivative reactivity assay (ADRA) is a novel in chemico alternative to animal testing for assessment of skin sensitization potential. The conventional ADRA protocol stipulates that test chemical solutions should be prepared to a specific Molar Concentration, allowing only for use of test chemicals with known molecular weights. Since many potential test substances are prepared by weight Concentration or contain multiple unknown chemicals, this study was conducted to verify if it is possible to accurately assess the sensitization potential of test chemical solutions prepared at a specific weight Concentration. Methods (1) Test chemical solutions for 82 chemicals were prepared at four different weight Concentrations. Results were evaluated for agreement with in vivo results. (2) A liquid mixture comprising ten different non-sensitizers was prepared at 1 mg/mL. Ten different sensitizers of varying sensitization potencies were added individually to this mixture. The resulting pseudobinary mixtures were tested to confirm that the sensitizers could be detected. Results (1) The accuracies for test chemical solutions prepared at 0.5 and 0.2 mg/mL were 87.8% and 86.6%, respectively, which were roughly equivalent to the accuracy of 86.6% achieved with a solution prepared at the conventional Molar Concentration of 1 mM. In contrast, the accuracies for solutions prepared at 0.1 and 0.05 mg/mL were 82.9% and 74.4%, respectively, both of which were lower than that obtained with the conventional method. (2) Sensitizers added to the liquid mixture at 0.5 mg/mL were all correctly detected. Discussion Preparing test chemical solutions at a weight Concentration of 0.5 mg/mL decreased false negatives and increased false positives while improving prediction accuracy, which suggests that the sensitization potential of mixtures can also be assessed with this method.
Masaharu Fujita - One of the best experts on this subject based on the ideXlab platform.
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improving predictive capacity of the amino acid derivative reactivity assay test method for skin sensitization potential with an optimal Molar Concentration of test chemical solution
Journal of Applied Toxicology, 2021Co-Authors: Mika Imamura, Sayaka Wanibuchi, Toshihiko Kasahara, Yusuke Yamamoto, Hajime Kojima, Atsushi Ono, Masaharu FujitaAbstract:The Amino acid Derivative Reactivity Assay (ADRA) is a convenient and effective in chemico test method for assessing covalent binding of test chemicals with protein-derived nucleophilic reagents as a means of predicting skin sensitization potential. Although the original Molar-Concentration approach to ADRA testing was not suitable for testing multiconstituent substances of an unknown composition, a weight-Concentration approach that is suitable for such substances was developed, which also led to the realization that test chemical solutions prepared to Molar Concentrations higher than the original 1 mM would reduce false negative results as well as enhance predictive capacity. The present study determined an optimal Molar-Concentration that achieves even higher predictive capacity than the original ADRA. Eight chemicals that were false negatives when tested with 1 mM test chemical solutions were retested with test chemical solutions between 2 and 5 mM, which showed 4 mM to be the optimal Molar-Concentration for ADRA testing. When 82 chemicals used in the original development were retested with 4 mM test chemical solutions, false negative results were reduced by four. When an additional 85 chemicals used to evaluate the weight-Concentration approach to ADRA were retested, the results essentially replicated those obtained with 0.5 mg/ml test chemical solutions and gave 10 fewer false negatives than original ADRA with 1 mM solutions. A comparison of these results for 136 chemicals showed that ADRA testing with 4 mM solutions achieved a four percentage point improvement in accuracy over original ADRA and a two percentage point improvement over DPRA testing.