Objective To assess the antimutagenicity of antioxidant vitamins （vitamins A, C, and E） as expressed by their efficacy to lower aflatoxin-induced mutations. Methods The Muller-5 method for mutation detection was use...Objective To assess the antimutagenicity of antioxidant vitamins （vitamins A, C, and E） as expressed by their efficacy to lower aflatoxin-induced mutations. Methods The Muller-5 method for mutation detection was used to assay the frequency of X-chromosome linked recessive lethal mutations （XRLMs） in Drosophila. Larvae were exposed to dietary concentration of aflatoxins and/or the human therapeutic doses of any of the three antioxidant vitamins. Absence of normal eyed males among M2 progeny gave an indication of mutation induction. Results Aflatoxin supplimentation significantly increased the incidence of XRLMs in Drosophila. Mutation frequency was also raised a little above the control level in case of vitamin treatment. However, notable mitigation in mutation frequency was registered when aflatoxin-treated larvae were concomitantly fed with any of the three antioxidant vitamins. Conclusion Aflatoxin exposure can enhance the frequency of gene mutation in Drosophila which is significantly lowered by each of the three antioxidant vitamins. The degree of amelioration produced by them is almost identical. This mitigation is based on the scavenging/trapping by antioxidant vitamins of DNA-reactive products （metabolites and radicals） emanating from aflatoxin metabolism.展开更多
The title complexes were modeled using the semiempirical MOPAC and the newly developed SPARKLE paramerters of the lanthanides. The calculated bond dis tances and angles agreed well with those found from crystal struct...The title complexes were modeled using the semiempirical MOPAC and the newly developed SPARKLE paramerters of the lanthanides. The calculated bond dis tances and angles agreed well with those found from crystal structure measuremen ts. This technique allows us to screen a large number of molecules and get struc tural information within a very short time.展开更多
Theoretical investigation on the structures of the octacoordinated [Nd(CO3)4]5-and the nonacoordinated [Nd(CO3)4.OH2]5-complexes, using the SPARKLE parameters of the lanthanides within MOPAC, revealed that they posses...Theoretical investigation on the structures of the octacoordinated [Nd(CO3)4]5-and the nonacoordinated [Nd(CO3)4.OH2]5-complexes, using the SPARKLE parameters of the lanthanides within MOPAC, revealed that they possessed dodecahedral and square antiprismatic structures respectively with an average Nd-O distance of 0.249 nm. These structures and the Nd-O distances agreed well with those experimentally found in the crystal structures. Replacing the water molecule with a fluoride ion or a mondentatecarbonato ligand resulted in a nonacoordinated distorted square antiprismatic structures where the trans-carbonato groups were twisted. The corresponding decacoordinated structures with two fluoride ions or a bidentatecarbonato group, [Nd(CO3)4·F2]7-and [Nd(CO3)5]7-, were also investigated. In both cases considerable twisting of the transcarbonato groups was observed.展开更多
文摘Objective To assess the antimutagenicity of antioxidant vitamins （vitamins A, C, and E） as expressed by their efficacy to lower aflatoxin-induced mutations. Methods The Muller-5 method for mutation detection was used to assay the frequency of X-chromosome linked recessive lethal mutations （XRLMs） in Drosophila. Larvae were exposed to dietary concentration of aflatoxins and/or the human therapeutic doses of any of the three antioxidant vitamins. Absence of normal eyed males among M2 progeny gave an indication of mutation induction. Results Aflatoxin supplimentation significantly increased the incidence of XRLMs in Drosophila. Mutation frequency was also raised a little above the control level in case of vitamin treatment. However, notable mitigation in mutation frequency was registered when aflatoxin-treated larvae were concomitantly fed with any of the three antioxidant vitamins. Conclusion Aflatoxin exposure can enhance the frequency of gene mutation in Drosophila which is significantly lowered by each of the three antioxidant vitamins. The degree of amelioration produced by them is almost identical. This mitigation is based on the scavenging/trapping by antioxidant vitamins of DNA-reactive products （metabolites and radicals） emanating from aflatoxin metabolism.
文摘The title complexes were modeled using the semiempirical MOPAC and the newly developed SPARKLE paramerters of the lanthanides. The calculated bond dis tances and angles agreed well with those found from crystal structure measuremen ts. This technique allows us to screen a large number of molecules and get struc tural information within a very short time.
文摘Theoretical investigation on the structures of the octacoordinated [Nd(CO3)4]5-and the nonacoordinated [Nd(CO3)4.OH2]5-complexes, using the SPARKLE parameters of the lanthanides within MOPAC, revealed that they possessed dodecahedral and square antiprismatic structures respectively with an average Nd-O distance of 0.249 nm. These structures and the Nd-O distances agreed well with those experimentally found in the crystal structures. Replacing the water molecule with a fluoride ion or a mondentatecarbonato ligand resulted in a nonacoordinated distorted square antiprismatic structures where the trans-carbonato groups were twisted. The corresponding decacoordinated structures with two fluoride ions or a bidentatecarbonato group, [Nd(CO3)4·F2]7-and [Nd(CO3)5]7-, were also investigated. In both cases considerable twisting of the transcarbonato groups was observed.
