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  1. Article ; Online: Photochemical and Photophysical Properties of Carotenoids and Reactive Oxygen Species

    Fritz Boehm / Ruth Edge / T. George Truscott

    Oxygen, Vol 3, Iss 21, Pp 322-

    Contradictions Relating to Skin and Vision

    2023  Volume 335

    Abstract: Molecular mechanisms based on photo-physical processes involving dietary carotenoids, their radicals, and the role of oxygen are discussed and used to suggest explanations of the poorly understood and often contradictory results related to mainly skin ... ...

    Abstract Molecular mechanisms based on photo-physical processes involving dietary carotenoids, their radicals, and the role of oxygen are discussed and used to suggest explanations of the poorly understood and often contradictory results related to mainly skin and vision. Differing and conflicting efficiencies of singlet oxygen reactions with carotenoids of biological importance are discussed in environments from ‘simple’ organic solvents to single He La cells. A range of free radical reactions with carotenoids, and the corresponding radicals of the carotenoids themselves, are compared and used to explain the switch from beneficial to deleterious processes involving dietary carotenoids and to unravel their differing functions; of particular interest is a possible role for vitamin C.
    Keywords carotenoids ; β-carotene ; lycopene ; zeaxanthin ; lutein ; astaxanthin ; Analytical chemistry ; QD71-142 ; Inorganic chemistry ; QD146-197
    Language English
    Publishing date 2023-08-01T00:00:00Z
    Publisher MDPI AG
    Document type Article ; Online
    Database BASE - Bielefeld Academic Search Engine (life sciences selection)

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  2. Article ; Online: Scavenging of Cation Radicals of the Visual Cycle Retinoids by Lutein, Zeaxanthin, Taurine, and Melanin

    Malgorzata Rozanowska / Ruth Edge / Edward J. Land / Suppiah Navaratnam / Tadeusz Sarna / T. George Truscott

    International Journal of Molecular Sciences, Vol 25, Iss 1, p

    2023  Volume 506

    Abstract: In the retina, retinoids involved in vision are under constant threat of oxidation, and their oxidation products exhibit deleterious properties. Using pulse radiolysis, this study determined that the bimolecular rate constants of scavenging cation ... ...

    Abstract In the retina, retinoids involved in vision are under constant threat of oxidation, and their oxidation products exhibit deleterious properties. Using pulse radiolysis, this study determined that the bimolecular rate constants of scavenging cation radicals of retinoids by taurine are smaller than 2 × 10 7 M −1 s −1 whereas lutein scavenges cation radicals of all three retinoids with the bimolecular rate constants approach the diffusion-controlled limits, while zeaxanthin is only 1.4–1.6-fold less effective. Despite that lutein exhibits greater scavenging rate constants of retinoid cation radicals than other antioxidants, the greater concentrations of ascorbate in the retina suggest that ascorbate may be the main protectant of all visual cycle retinoids from oxidative degradation, while α-tocopherol may play a substantial role in the protection of retinaldehyde but is relatively inefficient in the protection of retinol or retinyl palmitate. While the protection of retinoids by lutein and zeaxanthin appears inefficient in the retinal periphery, it can be quite substantial in the macula. Although the determined rate constants of scavenging the cation radicals of retinol and retinaldehyde by dopa-melanin are relatively small, the high concentration of melanin in the RPE melanosomes suggests they can be scavenged if they are in proximity to melanin-containing pigment granules.
    Keywords retinal ; vitamin A ; free radicals ; xanthophylls ; carotenoids ; vitamin E ; Biology (General) ; QH301-705.5 ; Chemistry ; QD1-999
    Subject code 333
    Language English
    Publishing date 2023-12-01T00:00:00Z
    Publisher MDPI AG
    Document type Article ; Online
    Database BASE - Bielefeld Academic Search Engine (life sciences selection)

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  3. Article ; Online: Scavenging of Retinoid Cation Radicals by Urate, Trolox, and α-, β-, γ-, and δ-Tocopherols

    Malgorzata Rozanowska / Ruth Edge / Edward J. Land / Suppiah Navaratnam / Tadeusz Sarna / T. George Truscott

    International Journal of Molecular Sciences, Vol 20, Iss 11, p

    2019  Volume 2799

    Abstract: Retinoids are present in human tissues exposed to light and under increased risk of oxidative stress, such as the retina and skin. Retinoid cation radicals can be formed as a result of the interaction between retinoids and other radicals or ... ...

    Abstract Retinoids are present in human tissues exposed to light and under increased risk of oxidative stress, such as the retina and skin. Retinoid cation radicals can be formed as a result of the interaction between retinoids and other radicals or photoexcitation with light. It has been shown that such semi-oxidized retinoids can oxidize certain amino acids and proteins, and that α-tocopherol can scavenge the cation radicals of retinol and retinoic acid. The aim of this study was to determine (i) whether β-, γ-, and δ-tocopherols can also scavenge these radicals, and (ii) whether tocopherols can scavenge the cation radicals of another form of vitamin A—retinal. The retinoid cation radicals were generated by the pulse radiolysis of benzene or aqueous solution in the presence of a selected retinoid under oxidizing conditions, and the kinetics of retinoid cation radical decays were measured in the absence and presence of different tocopherols, Trolox or urate. The bimolecular rate constants are the highest for the scavenging of cation radicals of retinal, (7 to 8) × 10 9 M −1 ·s −1 , followed by retinoic acid, (0.03 to 5.6) × 10 9 M −1 ·s −1 , and retinol, (0.08 to 1.6) × 10 8 M −1 ·s −1 . Delta-tocopherol is the least effective scavenger of semi-oxidized retinol and retinoic acid. The hydrophilic analogue of α-tocopherol, Trolox, is substantially less efficient at scavenging retinoid cation radicals than α-tocopherol and urate, but it is more efficient at scavenging the cation radicals of retinoic acid and retinol than δ-tocopherol. The scavenging rate constants indicate that tocopherols can effectively compete with amino acids and proteins for retinoid cation radicals, thereby protecting these important biomolecules from oxidation. Our results provide another mechanism by which tocopherols can diminish the oxidative damage to the skin and retina and thereby protect from skin photosensitivity and the development and/or progression of changes in blinding retinal diseases such as Stargardt’s disease and age-related macular degeneration (AMD).
    Keywords vitamin A ; retinol ; retinal ; retinoic acid ; vitamin E ; tocopherol ; free radicals ; antioxidants ; skin ; retina ; Biology (General) ; QH301-705.5 ; Chemistry ; QD1-999
    Subject code 333
    Language English
    Publishing date 2019-06-01T00:00:00Z
    Publisher MDPI AG
    Document type Article ; Online
    Database BASE - Bielefeld Academic Search Engine (life sciences selection)

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  4. Article ; Online: The Effect of Gamma Irradiation on the Ion Exchange Properties of Caesium-Selective Ammonium Phosphomolybdate-Polyacrylonitrile (AMP-PAN) Composites under Spent Fuel Recycling Conditions

    Alistair F. Holdsworth / Harry Eccles / Daniel Rowbotham / Gary Bond / Parthiv C. Kavi / Ruth Edge

    Separations, Vol 6, Iss 2, p

    2019  Volume 23

    Abstract: The caesium radioisotopes 134 Cs, 135 Cs, and 137 Cs are highly problematic medium-lived species produced during nuclear fission, due to their high radioactivity and environmental mobility. While many ion exchange materials can readily isolate Cs + ions ... ...

    Abstract The caesium radioisotopes 134 Cs, 135 Cs, and 137 Cs are highly problematic medium-lived species produced during nuclear fission, due to their high radioactivity and environmental mobility. While many ion exchange materials can readily isolate Cs + ions from neutral or basic aqueous solutions, only ammonium phosphomolybdate (AMP) functions effectively in acidic conditions, removing caesium even down to trace levels. Composites of AMP in a porous polymeric support such as polyacrylonitrile (PAN) can be used to selectively remove Cs + ions from acidic aqueous decontamination liquors as well as other liquid wastes, and are promising for the isolation of Cs + isotopes in spent fuel reprocessing. While both AMP and PAN have demonstrable acid stability, and PAN has known resistance to gamma radiation, AMP-PAN composites have received only a limited analysis of their physiochemical and ion exchange performance following irradiation. In this publication, we explore the effect of high levels of gamma irradiation on the ion exchange properties of AMP and AMP-PAN as a Cs + -selective adsorbent under spent fuel dissolver liquor concentrations and acidity. We demonstrate no significant reduction in performance with respect to uptake kinetics or capacity upon irradiation, abiding by the same absorption mechanism observed in the established literature.
    Keywords AMP-PAN ; ion-exchange ; composites ; chromatographic separation ; fission product ; caesium ; spent fuel reprocessing ; waste management ; radiation effects ; Physics ; QC1-999 ; Chemistry ; QD1-999
    Subject code 333
    Language English
    Publishing date 2019-04-01T00:00:00Z
    Publisher MDPI AG
    Document type Article ; Online
    Database BASE - Bielefeld Academic Search Engine (life sciences selection)

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  5. Article ; Online: Resurgence of a Nation’s Radiation Science Driven by Its Nuclear Industry Needs

    Laura Leay / Aliaksandr Baidak / Christopher Anderson / Choen May Chan / Aaron Daubney / Thomas Donoclift / Gemma Draper / Ruth Edge / Jeff Hobbs / Luke Jones / Nicholas J. S. Mason / Darryl Messer / Mel O’Leary / Robin Orr / Simon M. Pimblott / Samir de Moraes Shubeita / Andrew D. Smith / Helen Steele / Paul Wady /
    Frederick Currell

    Applied Sciences, Vol 11, Iss 11081, p

    2021  Volume 11081

    Abstract: This article describes the radiation facilities and associated sample preparation, management, and analysis equipment currently in place at the Dalton Cumbrian Facility, a facility which opened in 2011 to support the UK’s nuclear industry. Examples of ... ...

    Abstract This article describes the radiation facilities and associated sample preparation, management, and analysis equipment currently in place at the Dalton Cumbrian Facility, a facility which opened in 2011 to support the UK’s nuclear industry. Examples of measurements performed using these facilities are presented to illustrate their versatility and the breadth of research they make possible. Results are presented from research which furthers our understanding of radiation damage to polymeric materials, radiolytic yield of gaseous products in situations relevant to nuclear materials, radiation chemistry in light water reactor cooling systems, material chemistry relevant to immobilization of nuclear waste, and radiation-induced corrosion of fuel cladding elements. Applications of radiation chemistry relevant to health care are also described. Research concerning the mechanisms of radioprotection by dietary carotenoids is reported. An ongoing open-labware project to develop a suite of modular sample handling components suited to radiation research is described, as is the development of a new neutron source able to provide directional beams of neutrons.
    Keywords radiolysis ; nuclear science ; radiotherapy ; ionizing radiation ; radiation chemistry in nuclear technology ; sources of ionizing radiation ; Technology ; T ; Engineering (General). Civil engineering (General) ; TA1-2040 ; Biology (General) ; QH301-705.5 ; Physics ; QC1-999 ; Chemistry ; QD1-999
    Subject code 535
    Language English
    Publishing date 2021-11-01T00:00:00Z
    Publisher MDPI AG
    Document type Article ; Online
    Database BASE - Bielefeld Academic Search Engine (life sciences selection)

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