The Experts below are selected from a list of 243 Experts worldwide ranked by ideXlab platform
Thomas J. Slaga - One of the best experts on this subject based on the ideXlab platform.
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comparison of the skin tumor promoting potential of different organic Peroxides in sencar mice
Toxicology and Applied Pharmacology, 1998Co-Authors: Irma B Gimenezconti, R L Binder, Dennis A. Johnston, Thomas J. SlagaAbstract:The skin tumor-promoting activities of three organic Peroxides were evaluated and compared to the activity of benzoyl Peroxide, a well-characterized tumor promoter. Two of the compounds (di-t-butyl Peroxide and dicumyl Peroxide) were dialkyl Peroxides and the other (di-m-chlorobenzoyl Peroxide) was a diacyl Peroxide. These compounds were selected based on a previous study in which we evaluated their capacity to induce epidermal hyperplasia, ornithine decarboxylase activity, and dark basal keratinocytes, which have been reliable short-term markers of tumor promotion. Dicumyl Peroxide was a weak tumor promoter despite its high activity in inducing hyperplasia. Like benzoyl Peroxide, di-m-chlorobenzoyl Peroxide generally had intermediate activity as an inducer of short-term markers of tumor promotion and was a moderately effective tumor promoter. However, compared to benzoyl Peroxide, di-m-chlorobenzoyl Peroxide was more toxic to the skin, which may have limited its tumor-promoting activity. The final compound, di-t-butyl Peroxide, which was essentially inactive in short-term assays, was also totally inactive in promoting papillomas or carcinomas in initiated skin. Tumor-promoting efficacy generally showed an inverse association with thermal stability for the compounds tested, suggesting that the rate of formation of free radicals is a key factor contributing to tumor promotion by organic Peroxides. However, a number of other factors can potentially affect the activity of different organic Peroxides as tumor promoters. Each compound evaluated had a different spectrum of activities, and these compounds should be useful for studying mechanisms of organic Peroxide-induced tumor promotion.
Alan B. Fleischer - One of the best experts on this subject based on the ideXlab platform.
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Interaction of Topical Sulfacetamide and Topical Dapsone With Benzoyl Peroxide
Archives of dermatology, 2009Co-Authors: Meghan I. Dubina, Alan B. FleischerAbstract:Background A recent study demonstrated evidence of a yellow-orange discoloration of the skin and hair when topical dapsone gel was combined with benzoyl Peroxide. This phenomenon had previously been observed by one of us (A.B.F.) when sulfasalazine was combined with benzoyl Peroxide. To investigate these interaction phenomena, topical dapsone gel and sulfacetamide sodium lotion were combined with various topical acne treatments, including benzoyl Peroxides, clindamycin phosphate, and retinoids. Observations Products containing benzoyl Peroxide produced an orange-brown discoloration when mixed with either sulfacetamide or dapsone. Conclusions Knowledge of the chemical reaction between benzoyl Peroxide and sulfacetamide and dapsone will help minimize the occurrence of this interaction on our patients' skin.
Christine Bösch-saadatmandi - One of the best experts on this subject based on the ideXlab platform.
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Mechanisms Involved in the Modulation of Astroglial Resistance to Oxidative Stress Induced by Activated Microglia: Antioxidative Systems, Peroxide Elimination, Radical Generation, Lipid Peroxidation
Neurotoxicity Research, 2010Co-Authors: Claudia Röhl, Michael Gülden, Edmund Maser, Elisabeth Armbrust, Eva Herbst, Anne Jess, Gerald Rimbach, Christine Bösch-saadatmandiAbstract:Microglia and astrocytes are the cellular key players in many neurological disorders associated with oxidative stress and neuroinflammation. Previously, we have shown that microglia activated by lipopolysaccharides (LPS) induce the expression of antioxidative enzymes in astrocytes and render them more resistant to hydrogen Peroxide (H_2O_2). In this study, we examined the mechanisms involved with respect to the cellular action of different Peroxides, the ability to detoxify Peroxides, and the status of further antioxidative systems. Astrocytes were treated for 3 days with medium conditioned by purified quiescent (microglia-conditioned medium, MCM[−]) or LPS-activated (MCM[+]) microglia. MCM[+] reduced the cytotoxicity of the organic cumene hydroPeroxide in addition to that of H_2O_2. Increased Peroxide resistance was not accompanied by an improved ability of astrocytes to remove H_2O_2 or an increased expression/activity of Peroxide eliminating antioxidative enzymes. Neither Peroxide-induced radical generation nor lipid peroxidation were selectively affected in MCM[+] treated astrocytes. The glutathione content of Peroxide resistant astrocytes, however, was increased and suPeroxide dismutase and heme oxygenase were found to be upregulated. These changes are likely to contribute to the higher Peroxide resistance of MCM[+] treated astrocytes by improving their ability to detoxify reactive oxygen radicals and oxidation products. For C6 astroglioma cells a protective effect of microglia-derived factors could not be observed, underlining the difference of primary cells and cell lines concerning their mechanisms of oxidative stress resistance. Our results indicate the importance of microglial–astroglial cell interactions during neuroinflammatory processes.
Sebastian Riedel - One of the best experts on this subject based on the ideXlab platform.
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No Fear of Perfluorinated Peroxides: Syntheses and Solid‐State Structures of Surprisingly Inert Perfluoroalkyl Peroxides
Angewandte Chemie (International ed. in English), 2019Co-Authors: Jan H. Nissen, Tony Stüker, Thomas Drews, Simon Steinhauer, Helmut Beckers, Sebastian RiedelAbstract:We report on the solid-state structures of bis(nonafluoro-tert-butyl) Peroxide [(F3 C)3 CO]2 and bis(undecafluoro-2-methyl-2-butyl) Peroxide [(C2 F5 )(F3 C)2 CO]2 . These Peroxides were prepared from the corresponding hypofluorites and fluorinated silver wool. The solid-state structures obtained after in situ crystallisation show unusual COOC dihedral angles of 180°, as well as elongated O-O bonds because of the bulky perfluorinated alkyl groups. The perfluorinated alkyl Peroxides are insensitive to both impact (>40 J) and friction (>360 N), and resistant towards mineral acids (HX; X=F, Cl, Br) and elemental halogens (X2 ). Ferrocene is oxidized by [(F3 C)3 CO]2 to [FeIII Cp2 ][OC(CF3 )3 ].
Y. John Wang - One of the best experts on this subject based on the ideXlab platform.
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Peroxide formation in polysorbate 80 and protein stability.
Journal of pharmaceutical sciences, 2002Co-Authors: Y. John WangAbstract:Nonionic surfactants are widely used in the development of protein pharmaceuticals. However, the low level of residual Peroxides in surfactants can potentially affect the stability of oxidation-sensitive proteins. In this report, we examined the Peroxide formation in polysorbate 80 under a variety of storage conditions and tested the potential of Peroxides in polysorbate 80 to oxidize a model protein, IL-2 mutein. For the first time, we demonstrated that Peroxides can be easily generated in neat polysorbate 80 in the presence of air during incubation at elevated temperatures. Polysorbate 80 in aqueous solution exhibited a faster rate of Peroxide formation and a greater amount of Peroxides during incubation, which is further promoted/catalyzed by light. Peroxide formation can be greatly inhibited by preventing any contact with air/oxygen during storage. IL-2 mutein can be easily oxidized both in liquid and solid states. A lower level of Peroxides in polysorbate 80 did not change the rate of IL-2 mutein oxidation in liquid state but significantly accelerated its oxidation in solid state under air. A higher level of Peroxides in polysorbate 80 caused a significant increase in IL-2 mutein oxidation both in liquid and solid states, and glutathione can significantly inhibit the Peroxide-induced oxidation of IL-2 mutein in a lyophilized formulation. In addition, a higher level of Peroxides in polysorbate 80 caused immediate IL-2 mutein oxidation during annealing in lyophilization, suggesting that implementation of an annealing step needs to be carefully evaluated in the development of a lyophilization process for oxidation-sensitive proteins in the presence of polysorbate.
