The Experts below are selected from a list of 1935 Experts worldwide ranked by ideXlab platform
Hideo Okamura - One of the best experts on this subject based on the ideXlab platform.
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effects of metal Pyrithione antifoulants on freshwater macrophyte lemna gibba g3 determined by image analysis
Ecotoxicology, 2012Co-Authors: Hideo Okamura, Luvsantsend Togosmaa, Takuya Sawamoto, Keiichi Fukushi, Tomoaki Nishida, Toshio BeppuAbstract:Copper Pyrithione (CuPT2) and zinc Pyrithione (ZnPT2) are two popular antifouling agents that prevent biofouling. Research into the environmental effects of metal Pyrithiones has mainly focused on aquatic animal species such as fish and crustaceans, and little attention has been paid to primary producers. There have been few reports on residues in environmental matrices because of the high photolabile characteristics of the agents. Residue analyses and ecological effects of the metabolites and metal Pyrithiones are not yet fully understood. This study was undertaken to assess the effects of CuPT2, ZnPT2, and six metabolites (PT2: 2,2′-dithio-bispyridine N-oxide, PS2: 2,2′-dithio-bispyridine, PSA: pyridine-2-sulfonic acid, HPT: 2-mercaptopyridine N-oxide, HPS: 2-mercaptopyridine, and PO: pyridine N-oxide) on a freshwater macrophyte. A 7-day static bioassay using axenic duckweed Lemna gibba G3 was performed under laboratory conditions. Toxic effects of test compounds were assessed by biomass reduction and morphological changes were determined in image analysis. Concentrations of ZnPT2 and CuPT2 and those of PT2 and HPT in the medium were determined by derivatizing 2,2′-dithio-bispyridine mono-N-oxide with pyridine disulfide/ethylene diamine tetra-acetic acid reagent that was equimolar with Pyrithione. The toxic intensity of the compounds was calculated from the measured concentrations after 7-day exposure. ZnPT2, CuPT2, PT2, and HPT inhibited the growth of L. gibba with EC50 ranging from 77 to 140 μg/l as calculated from the total frond number as the conventional index, whereas the other four metabolites had less effect even at 10 mg/l. The presence of the former four toxic derivatives resulted in abnormally shaped and unhealthily colored fronds, whose size was about 20% of the control fronds. EC50, calculated from the healthy frond area determined in image analysis, ranged from 10 to 53 μg/l. Thus, image analysis as part of a duckweed bioassay can detect the toxic effects of Pyrithione derivatives with 3–10 times higher sensitivity than the traditional index.
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Toxicity reduction of metal Pyrithiones by near ultraviolet irradiation.
Environmental toxicology, 2006Co-Authors: Hideo Okamura, Naomasa Kobayashi, Masamitsu Miyanaga, Yusaku NogamiAbstract:Zinc Pyrithione (ZnPT) or copper Pyrithione (CuPT) have been effectively used as ship-antifouling agents, as an alternative to organotin compounds. Because of their instability in light and a lack of suitable analytical procedures, there is little data on their residue levels in environmental matrices. It is possible to investigate the fate of such compounds by toxicity alteration with certain treatments. The purpose of this study was to evaluate the degradation of Pyrithiones through toxicity reduction by near ultraviolet (UV-A) irradiation. Metal Pyrithiones dissolved in acetonitrile were irradiated with a UV-A lamp for 0, 0.5, 1, and 2 h, and were subjected to UV spectral measurement and toxicity evaluation using both sea urchin and freshwater rotifer bioassays. For the bioassays, photolyzed samples were dissolved in dimethyl sulfoxide after evaporation of the acetonitrile. The changes in UV spectra of photolyzed ZnPT or CuPT showed a time-dependent degradation, and the UV spectra at 2 h irradiation suggested substantial decomposition. Toxicities of ZnPT and CuPT were 12 and 5 microg/L as 24 h LC50 to the survival of rotifers and 10(-6) ng/L and 2.3 ng/L as 27 h EC50 to normal pluteus formation, respectively. By evaporation of the acetonitrile, the EC50 of ZnPT was 2.2 ng/L, which was the same as that of CuPT. The EC50s of ZnPT or CuPT for both species increased with longer irradiation times. Photolyzed ZnPT or CuPT demonstrated substantial degradation in the UV spectra, but possessed marked toxicity, which is probably due to toxic degradation products. One reason why photolyzed CuPT was toxic to rotifers was explained by the high toxicity of copper ions formed by UV-A irradiation.
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effects of new antifouling compounds on the development of sea urchin
Marine Pollution Bulletin, 2002Co-Authors: Naomasa Kobayashi, Hideo OkamuraAbstract:Abstract Tributyltin oxide (TBTO) has been used worldwide in marine antifouling paints as a biocide for some time. However, it produced toxic effects, especially in marine water/sediment ecosystems. Consequently, its use in antifouling paints has been prohibited in many countries. In this study, the toxicity of alternative and/or new antifouling biocides compared with TBTO is assessed by a biological method. The effects of these chemicals on marine species have not been well studied. This paper assesses, comparatively, the effects of eight biocides on sea urchin eggs and embryos. The chemicals assessed were TBTO, Irgarol 1051, M1 (the persistent degradation product of Irgarol), Diuron, zinc Pyrithione, `KH101', `Sea-Nine 211', and copper Pyrithione. For these chemicals, toxicity appears to be in the order zinc Pyrithione > Sea-Nine 211> KH101 > copper Pyrithione > TBTO > Diuron ∼ Irgarol 1051> M1 . Here, we show that zinc Pyrithione, Sea-Nine 211, KH101, and copper Pyrithione are much more toxic to sea urchins than TBTO or the other chemicals.
Michael S. Roberts - One of the best experts on this subject based on the ideXlab platform.
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Optical Characterization of Zinc Pyrithione.
Photochemistry and photobiology, 2019Co-Authors: Lydia Sandiford, Amy Holmes, Sean E. Mangion, Yousuf H. Mohammed, Andrei V. Zvyagin, Michael S. RobertsAbstract:Zinc Pyrithione is ubiquitous in commercial products particularly antidandruff shampoos. For the efficacy of zinc Pyrithione therapeutic cleansers to be assessed accurately, the distribution of particles on the scalp needs to be visualized. Currently, no technique is available which provides the chemical specificity and sensitivity required. Here, we report application of fluorescence-lifetime imaging microscopy (FLIM) for high-contrast mapping of zinc Pyrithione distribution on the scalp. Characterization of the zinc Pyrithione emission by using both one-photon excitation at five specific wavelengths and two-photon excitation in the range of 740-820 nm revealed its FLIM fingerprint-a characteristic short average time-weighted emission lifetime of Τ = 250 ps. Bandpass-filtering FLIM signals at Τ enabled an efficient discrimination between the zinc Pyrithione and major endogenous skin species in comparison with that of the conventional reflectance confocal microscopy. Our findings provide means for in vivo high-sensitivity assaying and high-contrast imaging of zinc Pyrithione in biological systems.
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imaging the penetration and distribution of zinc and zinc species after topical application of zinc Pyrithione to human skin
Toxicology and Applied Pharmacology, 2018Co-Authors: Amy Holmes, Ivan M Kempson, Tyron Turnbull, David L Paterson, Michael S. RobertsAbstract:Zinc Pyrithione is an active component incorporated in an extensive range of topically applied commercial products that are used worldwide. Despite its prevalence, no published study has investigated the penetration of zinc from the zinc Pyrithione complex into human skin. Zinc is crucial for healthy skin function however an elevated concentration of labile zinc is toxic outside a narrow concentration range. Synchrotron X-ray fluorescence microscopy in conjunction with X-ray absorption near edge structure spectroscopy was used to map the deposition of zinc, quantitate the amount of zinc within the skin and to identify a change in the chemical form of zinc after application. This study has demonstrated a similar to 3.8 fold increase in zinc concentration within the viable epidermis (VE) after 24 h topical application of zinc Pyrithione that increased significantly by similar to 250 fold after 48 h when compared to control skin. Confocal microscopy using a labile zinc specific dye, ZinPyr-1, showed that zinc Pyrithione disrupted the skin cells zinc homeostasis and significantly increased the intracellular zinc concentration leading to cell toxicity. Overall, this study demonstrates that topical application of zinc Pyrithione formulations leads to an increase in zinc penetration in human skin, consequently, raising concerns for potential localised toxicity to occur.
Steven R Feldman - One of the best experts on this subject based on the ideXlab platform.
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the use of 0 25 zinc Pyrithione spray does not enhance the efficacy of clobetasol propionate 0 05 foam in the treatment of psoriasis
Journal of The American Academy of Dermatology, 2003Co-Authors: Tamara Salam Housman, Kimberly A. Keil, Beverly G. Mellen, Martha Ann Mccarty, Alan B. Fleischer, Steven R FeldmanAbstract:Abstract Background: It was discovered that Skin Cap (Cheminova Internacional S.A., Madrid, Spain), an over-the-counter psoriasis therapy with zinc Pyrithione, contained clobetasol propionate and it was withdrawn from the market by the US Food and Drug Administration review. Some suggested that there might be a synergistic effect of zinc Pyrithione with clobetasol propionate. Objective: We sought to evaluate the efficacy of clobetasol propionate 0.05% foam with and without the coadministration of a topical 0.25% zinc Pyrithione spray in treating psoriasis involving sites other than the scalp. Methods: We conducted a randomized, double-blind, right/left study of patients with mild to moderate, generally symmetric, plaque-type psoriasis. Patients were assigned to treatment with clobetasol propionate foam on all psoriatic lesions and then randomly assigned to use zinc Pyrithione spray to either the right or left side of their body (vehicle spray to be applied to the opposite side). There was a 2-week treatment phase (visits at baseline, week 1, and week 2) and a follow-up phase (visit at week 4), and all treatments were administered twice daily for 2 weeks. The primary outcome measure was the change from baseline to week 2 in the composite score of the signs of psoriasis (erythema, scaling, plaque thickness) for symmetric target lesions. Results: A total of 25 patients were enrolled; 24 completed the trial and 1 was lost to follow up. Of those who completed the study, 63% (15 of 24) were men, and the mean age (±SD) was 50 years (±12.2). After 2 weeks of therapy, the average decline in the composite score was 3.5 (±1.8) for monotherapy (clobetasol propionate foam and vehicle) and, similarly, 3.3 (±1.8) for clobetasol propionate foam plus zinc Pyrithione spray ( P = .5). Discussion: Zinc Pyrithione spray does not appear to enhance the efficacy of clobetasol propionate foam after 2 weeks of therapy. (J Am Acad Dermatol 2003;49:79-82.)
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The use of 0.25% zinc Pyrithione spray does not enhance the efficacy of clobetasol propionate 0.05% foam in the treatment of psoriasis.
Journal of The American Academy of Dermatology, 2003Co-Authors: Tamara Salam Housman, Kimberly A. Keil, Beverly G. Mellen, Martha Ann Mccarty, Alan B. Fleischer, Steven R FeldmanAbstract:Abstract Background: It was discovered that Skin Cap (Cheminova Internacional S.A., Madrid, Spain), an over-the-counter psoriasis therapy with zinc Pyrithione, contained clobetasol propionate and it was withdrawn from the market by the US Food and Drug Administration review. Some suggested that there might be a synergistic effect of zinc Pyrithione with clobetasol propionate. Objective: We sought to evaluate the efficacy of clobetasol propionate 0.05% foam with and without the coadministration of a topical 0.25% zinc Pyrithione spray in treating psoriasis involving sites other than the scalp. Methods: We conducted a randomized, double-blind, right/left study of patients with mild to moderate, generally symmetric, plaque-type psoriasis. Patients were assigned to treatment with clobetasol propionate foam on all psoriatic lesions and then randomly assigned to use zinc Pyrithione spray to either the right or left side of their body (vehicle spray to be applied to the opposite side). There was a 2-week treatment phase (visits at baseline, week 1, and week 2) and a follow-up phase (visit at week 4), and all treatments were administered twice daily for 2 weeks. The primary outcome measure was the change from baseline to week 2 in the composite score of the signs of psoriasis (erythema, scaling, plaque thickness) for symmetric target lesions. Results: A total of 25 patients were enrolled; 24 completed the trial and 1 was lost to follow up. Of those who completed the study, 63% (15 of 24) were men, and the mean age (±SD) was 50 years (±12.2). After 2 weeks of therapy, the average decline in the composite score was 3.5 (±1.8) for monotherapy (clobetasol propionate foam and vehicle) and, similarly, 3.3 (±1.8) for clobetasol propionate foam plus zinc Pyrithione spray ( P = .5). Discussion: Zinc Pyrithione spray does not appear to enhance the efficacy of clobetasol propionate foam after 2 weeks of therapy. (J Am Acad Dermatol 2003;49:79-82.)
Gérald Pierard - One of the best experts on this subject based on the ideXlab platform.
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A multicenter randomized trial of ketoconazole 2% and zinc Pyrithione 1% shampoos in severe dandruff and seborrheic dermatitis.
Skin pharmacology and applied skin physiology, 2002Co-Authors: Claudine Piérard-franchimont, Véronique Goffin, Jacques Decroix, Gérald PierardAbstract:Ketoconazole (KET) and zinc Pyrithione (ZPT) are compounds active against the Malassezia spp. yeasts, which are believed to play a major role in dandruff and seborrheic dermatitis.
Amy Holmes - One of the best experts on this subject based on the ideXlab platform.
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Optical Characterization of Zinc Pyrithione.
Photochemistry and photobiology, 2019Co-Authors: Lydia Sandiford, Amy Holmes, Sean E. Mangion, Yousuf H. Mohammed, Andrei V. Zvyagin, Michael S. RobertsAbstract:Zinc Pyrithione is ubiquitous in commercial products particularly antidandruff shampoos. For the efficacy of zinc Pyrithione therapeutic cleansers to be assessed accurately, the distribution of particles on the scalp needs to be visualized. Currently, no technique is available which provides the chemical specificity and sensitivity required. Here, we report application of fluorescence-lifetime imaging microscopy (FLIM) for high-contrast mapping of zinc Pyrithione distribution on the scalp. Characterization of the zinc Pyrithione emission by using both one-photon excitation at five specific wavelengths and two-photon excitation in the range of 740-820 nm revealed its FLIM fingerprint-a characteristic short average time-weighted emission lifetime of Τ = 250 ps. Bandpass-filtering FLIM signals at Τ enabled an efficient discrimination between the zinc Pyrithione and major endogenous skin species in comparison with that of the conventional reflectance confocal microscopy. Our findings provide means for in vivo high-sensitivity assaying and high-contrast imaging of zinc Pyrithione in biological systems.
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imaging the penetration and distribution of zinc and zinc species after topical application of zinc Pyrithione to human skin
Toxicology and Applied Pharmacology, 2018Co-Authors: Amy Holmes, Ivan M Kempson, Tyron Turnbull, David L Paterson, Michael S. RobertsAbstract:Zinc Pyrithione is an active component incorporated in an extensive range of topically applied commercial products that are used worldwide. Despite its prevalence, no published study has investigated the penetration of zinc from the zinc Pyrithione complex into human skin. Zinc is crucial for healthy skin function however an elevated concentration of labile zinc is toxic outside a narrow concentration range. Synchrotron X-ray fluorescence microscopy in conjunction with X-ray absorption near edge structure spectroscopy was used to map the deposition of zinc, quantitate the amount of zinc within the skin and to identify a change in the chemical form of zinc after application. This study has demonstrated a similar to 3.8 fold increase in zinc concentration within the viable epidermis (VE) after 24 h topical application of zinc Pyrithione that increased significantly by similar to 250 fold after 48 h when compared to control skin. Confocal microscopy using a labile zinc specific dye, ZinPyr-1, showed that zinc Pyrithione disrupted the skin cells zinc homeostasis and significantly increased the intracellular zinc concentration leading to cell toxicity. Overall, this study demonstrates that topical application of zinc Pyrithione formulations leads to an increase in zinc penetration in human skin, consequently, raising concerns for potential localised toxicity to occur.
