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Photochemistry and Photobiology

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https://www.readbyqxmd.com/read/28722754/-31-p-nmr-evidence-for-peroxide-intermediates-in-lipid-emulsion-photooxidations-phosphine-substituent-effects-in-trapping
#1
Prabhu P Mohapatra, Callistus O Chiemezie, Arina Kligman, Michele M Kim, Theresa M Busch, Timothy C Zhu, Alexander Greer
Intralipid is a lipid emulsion used in photodynamic therapy (PDT) for its light scattering and tissue-simulating properties. The purpose of this study is to determine whether or not Intralipid undergoes photooxidation, we have carried out an Intralipid peroxide trapping study using a series of phosphines [2'-dicyclohexylphosphino-2,6-dimethoxy-1,1'-biphenyl-3-sulfonate, 3-(diphenylphosphino)benzenesulfonate, triphenylphosphine-3,3',3''-trisulfonate, and triphenylphosphine]. Our new findings are as follows: (i) An oxygen atom is transferred from Intralipid peroxide to the phosphine traps in the dark, after the photooxidation of Intralipid...
July 19, 2017: Photochemistry and Photobiology
https://www.readbyqxmd.com/read/28715145/the-autophagy-receptor-adaptor-p62-is-up-regulated-by-uva-radiation-in-melanocytes-and-in-melanoma-cells
#2
Ashley Sample, Baozhong Zhao, Chunli Wu, Steven Qian, Xianglin Shi, Andrew Aplin, Yu-Ying He
UVA (315-400 nm) is the most abundant in sunlight and is used in indoor tanning beds. However, much remains to be understood about the regulation of the UVA damage response in melanocytes and melanoma. Here we show that UVA, but not the shorter waveband UVB (280-315 nm), up-regulates adaptor protein p62 in an Nrf2- and ROS-dependent manner, suggesting a UVA-specific effect on p62 regulation. UVA-induced p62 up-regulation was inhibited by a mitochondria-targeted antioxidant or Nrf2 knockdown. In addition, p62 knockdown inhibited UVA-induced ROS production and Nrf2 up-regulation...
July 17, 2017: Photochemistry and Photobiology
https://www.readbyqxmd.com/read/28710897/early-life-uv-and-risk-of-basal-and-squamous-cell-carcinoma-in-new-south-wales-australia
#3
Anne Kricker, Marianne Weber, Freddy Sitas, Emily Banks, Bayzidur Rahman, Chris Goumas, Ahsanul Kabir, Verity S Hodgkinson, Cathelijne H van Kemenade, Tim Waterboer, Bruce K Armstrong
Sun exposure is the main cause of squamous (SCC) and basal cell carcinoma (BCC) although pattern and amount differ by cancer type, and sun sensitivity is the major host risk factor. Our study investigated risk factors and residential ambient UV in a population-based sample of Australian 45 and Up Study participants: 916 BCC cases, 433 SCC cases, 1224 controls. Unconditional logistic regression models adjusting for key covariates demonstrated 60% increased BCC risk and 2-fold increased SCC risk with sun sensitivity, and 3- and 4-fold increased risk respectively with solar keratoses...
July 15, 2017: Photochemistry and Photobiology
https://www.readbyqxmd.com/read/28710892/photochemical-reaction-between-1-2-naphthoquinone-and-adenine-in-binary-water-acetonitrile-solutions
#4
Qiaohui Zhou, Yaxiong Wei, Xiang Liu, Lin Chen, Xiaoguo Zhou, Shilin Liu
The photochemical reaction between 1,2-naphthoquinone (NQ) and adenine was investigated using nanosecond time-resolved laser flash photolysis. With photolysis at 355 nm, the lowest triplet state T1 of NQ was produced via intersystem crossing from its singlet excited state. The triplet-triplet absorption of the state contributes three bands of transient spectra at374, 596 and 650 nm, respectively, in pure acetonitrile and binary water-acetonitrile solutions. In the presence of adenine, the observation of A•(+) (at 363nm) and NQ+H • radical (at 343 and 485 nm) indicates a multi-step mechanism of electron transfer process followed by a proton transfer between (3) NQ* and adenine...
July 15, 2017: Photochemistry and Photobiology
https://www.readbyqxmd.com/read/28708285/various-led-wavelengths-affected-myofiber-development-and-satellite-cell-proliferation-of-chick-embryos-via-the-igf-1-signaling-pathway
#5
Yao Wang, Xinjie Bai, Zixu Wang, Jing Cao, Yulan Dong, Yanjun Dong, Yaoxing Chen
An effect of monochromatic light illumination on muscle mass has been discovered in chickens; however, its effect on the development of embryonic muscle remains unclear. Our previous studies demonstrated that monochromatic green light promoted satellite cell proliferation and muscle growth in post-hatching broilers. In this study, we investigated the effects and mechanisms of monochromatic light exposure on muscle development in late-embryogenesis. Seven hundred and fifty (750) fertile broiler eggs were randomly assigned to blue (B-group), green (G-group), red (R-group), white (W-group) lights or darkness (D-group) throughout the incubation period...
July 14, 2017: Photochemistry and Photobiology
https://www.readbyqxmd.com/read/28696576/nad-p-h-and-flavin-autofluorescence-correlation-with-atp-in-rat-livers-with-different-metabolic-steady-state-conditions
#6
Anna C Croce, Andrea Ferrigno, Laura G Di Pasqua, Clarissa Berardo, Giovanni Bottiroli, Mariapia Vairetti
The monitoring of NAD(P)H and flavin autofluorescence (AF) is at the basis of numerous investigations on energy metabolism. Nevertheless, the ability of these AF biomarkers to accurately represent the energy currency, ATP, is poorly explored. Here we focused on the AF/ATP correlation in lean and fatty livers with different steady-state metabolic conditions, achieved after organ isolation, preservation and recovery, in a likely dependence on both liver intrinsic metabolic features and externally induced perturbations...
July 11, 2017: Photochemistry and Photobiology
https://www.readbyqxmd.com/read/28696570/effects-of-combined-lysosomal-and-mitochondrial-photodamage-in-a-non-small-cell-lung-cancer-cell-line-the-role-of-paraptosis
#7
David Kessel, John J Reiners
We previously reported that a low-level of lysosomal photodamage potentiated the phototoxic effect of subsequent mitochondrial photodamage mediated by the benzoporphyrin derivative BPD in murine hepatoma 1c1c7 cells. This was attributed to release of Ca(2+) from damaged lysosomes and a calpain-mediated conversion of the autophagy-related protein ATG5 to a pro-apoptotic fragment. We now report a comparison of these results with those obtained with the human non small-cell lung cancer A549 cell line. A549 cells contained lower levels of ATG5 and were less responsive than 1c1c7 cultures to the PDT combination...
July 11, 2017: Photochemistry and Photobiology
https://www.readbyqxmd.com/read/28608526/clothing-protection-from-uvr-a-new-method-for-assessment
#8
Ryan Gage, William Leung, James Stanley, Anthony Reeder, Michelle Barr, Tim Chambers, Moira Smith, Louise Signal
Clothing modifies ultraviolet radiation exposure from the sun, and has an impact on skin cancer risk and the endogenous synthesis of vitamin D3 . There is no standardized method available for assessing body surface area covered by clothing, which limits generalizability between study findings. We calculated the body cover provided by 38 clothing items using diagrams of body surface area (BSA), adjusting the values to account for differences in BSA by age. Diagrams displaying each clothing item were developed and incorporated into a coverage assessment procedure (CAP)...
June 13, 2017: Photochemistry and Photobiology
https://www.readbyqxmd.com/read/28599356/an-in-vitro-model-for-fibroblast-photoaging-comparing-single-and-repeated-uva-irradiations
#9
Wongnapa Nakyai, Aurasorn Saraphanchotiwitthaya, Celine Viennet, Philippe Humbert, Jarupa Viyoch
The current method for efficient evaluation of anti-photoaging compounds is an in vitro skin culture model using a single ultraviolet A (UVA) irradiation of fibroblasts. However, skin photoaging is caused by repeated exposure to UVA radiation. The objective of this study was to develop an appropriate model for in vitro skin photoaging by comparing the different effects of single (5 J/cm(2) ) and repeated exposures (5 J/cm(2) x 3 times) of fibroblasts to UVA irradiation. Our results demonstrated that a single and repeated exposure to UVA irradiation had different effects on fibroblasts...
June 9, 2017: Photochemistry and Photobiology
https://www.readbyqxmd.com/read/28597944/a-quantum-mechanical-study-of-the-binding-pocket-of-proteorhodopsin-absorption-and-vibrational-spectra-modulated-by-analogue-chromophores
#10
Francesco Buda, Tom Keijer, Srividya Ganapathy, Willem J de Grip
Proteorhodopsin is a light-driven proton pumping membrane protein related to bacteriorhodopsin. It contains an all-trans retinal A1 chromophore covalently bound to a lysine residue via a protonated Schiff base. In this study, we exploited density functional theory (DFT) calculations to investigate the retinal binding pocket in the dark state and after mimicking photoisomerization. The model of the binding pocket is constructed incrementally by adding the residues near the retinal that are necessary to ensure a stable protonated Schiff base...
June 9, 2017: Photochemistry and Photobiology
https://www.readbyqxmd.com/read/28574176/a-photosensitizer-lanthanide-nanoparticle-formulation-that-induces-singlet-oxygen-with-direct-light-excitation-but-not-by-photon-or-x-ray-energy-transfer
#11
Rima Chouikrat, Francis Baros, Jean-Claude André, Régis Vanderesse, Bruno Viana, Anne-Laure Bulin, Christophe Dujardin, Philippe Arnoux, Marc Verelst, Céline Frochot
We report the design and synthesis of europium-doped gadolinium oxysulfide nanoscintillators Gd2 O2 S:Eu(3+) conjugated with two different photosensitizers (PSs): a zinc chlorin (ZnTPC) and a zinc phtalocyanine (ZnPc) by covalent bonding through a layer of N-(3-trimethoxysilylpropyl)diethylenetriamine (TPDA). These conjugates were designed to be activated under X-ray excitation to allow a photodynamic effect, although this desired outcome was not achieved in this study. The monodispersed nanoparticles of ∼70 nm diameter were pegylated to be stabilized in aqueous suspension...
June 2, 2017: Photochemistry and Photobiology
https://www.readbyqxmd.com/read/28574149/measurement-of-uv-emission-from-a-diffusing-optical-fiber-using-radiochromic-film
#12
David Welch, Henry M Spotnitz, David J Brenner
Analysis of the emission pattern from optical diffuser tips is vital to their usage in biomedical applications, especially as they find growing functionality beyond established phototherapy techniques. The use of ultraviolet radiation with diffuser tips increases the need to accurately characterize these devices, both for effective application and to avoid potentially dangerous exposure conditions. This study presents a new method to capture the diffusion pattern at a high resolution through the use of radiochromic film...
June 2, 2017: Photochemistry and Photobiology
https://www.readbyqxmd.com/read/28543667/panchromatic-osmium-complexes-for-photodynamic-therapy-solutions-to-existing-problems-and-new-questions
#13
Edith C Glazer
This article is a highlight of the paper by Lazic et al. in this issue of Photochemistry and Photobiology. It describes the validation of osmium coordination complexes as photosensitizers for photodynamic therapy, with very promising in vivo results that demonstrate radical improvements in survival following irradiation with visible (635 nm) or near-IR (NIR; 808 nm) light. An unusual feature in the study is that the different complexes exhibit disparate photophysical and photobiological characteristics, despite sharing common structural motifs...
May 23, 2017: Photochemistry and Photobiology
https://www.readbyqxmd.com/read/28543444/mechanistic-studies-on-the-peroxyoxalate-chemiluminescence-using-sodium-salicylate-as-base-catalyst
#14
Glalci A Souza, André P Lang, Wilhelm J Baader
Mechanistic studies on the peroxyoxalate chemiluminescence are often conducted with imidazole as base and nucleophilic catalyst. However, it is also known that this compound, at high concentrations, leads to a drastic reduction of the chemiluminescence quantum yields, apparently due the destruction of the high-energy intermediate. Consequently, the search for new catalysts for this transformation is of importance for mechanistic studies as well as analytical application. Therefore, we report here a study on the mechanism of the peroxyoxalate reaction with sodium salicylate as base catalyst; which has already been utilized in this reaction, however, no detailed mechanistic investigation is known...
May 23, 2017: Photochemistry and Photobiology
https://www.readbyqxmd.com/read/28510321/novel-zns-carbon-nanofibers-photocatalyst-for-degradation-of-rhodamine-6g-kinetics-tracking-of-operational-parameters-and-development-of-a-kinetics-model
#15
Ali Mehrizad, Parvin Gharbani
A novel nanocomposite in the role of photocatalyst was prepared by composition of zinc sulfide (ZnS) nanoparticles with carbon nanofibers (CNFs) and was characterized. The XRD, EDX, and FE-SEM analysis revealed that ZnS is successfully embedded in CNFs matrix. The DRS results indicated that supporting of ZnS by CNFs led to a decrease of the band gap energy. The photocatalytic degradation of a hazardous xanthine dye, Rhodamine 6 G (Rh-6G), by the prepared ZnS/CNFs composite was examined from the kinetics point of view...
May 16, 2017: Photochemistry and Photobiology
https://www.readbyqxmd.com/read/28503778/a-topical-zinc-ionophore-blocks-tumorigenic-progression-in-uv-exposed-skh-1-high-risk-mouse-skin
#16
Rebecca Justiniano, Jessica Perer, Anh Hua, Mohammad Fazel, Andrea Krajisnik, Christopher M Cabello, Georg T Wondrak
Nonmelanoma skin cancer (NMSC) is the most common malignancy in the United States representing a considerable public health burden. Pharmacological suppression of skin photocarcinogenesis has shown promise in preclinical and clinical studies, but more efficacious photochemopreventive agents are needed. Here, we tested feasibility of harnessing pharmacological disruption of intracellular zinc homeostasis for photochemoprevention in vitro and in vivo. Employing the zinc ionophore and FDA-approved microbicidal agent zinc pyrithione (ZnPT), used worldwide in over-the-counter (OTC) topical consumer products, we first demonstrated feasibility of achieving ZnPT-based intracellular Zn(2+) overload in cultured malignant keratinocytes (HaCaT-ras II-4; SCC-25) employing membrane-permeable fluorescent probes...
May 15, 2017: Photochemistry and Photobiology
https://www.readbyqxmd.com/read/28503745/interactions-between-phyb-and-pif-proteins-alter-thermal-reversion-reactions-in-vitro
#17
Robert W Smith, Britta Helwig, Adrie H Westphal, Eran Pel, Jan Willem Borst, Christian Fleck
The dynamic behavior of the plant red/far-red light photoreceptor phytochrome B (phyB) has been elucidated in natural and synthetic systems. Red light switches phyB from the inactive Pr state to the active Pfr state, a process that is reversed by far-red light. Alongside light signals, phyB activity is constrained by thermal reversion (that is prominent in the dark) and protein-protein interactions between phyB, other phytochrome molecules, and, among others, PHYTOCHROME INTERACTING FACTORs (PIFs). Requirements for phyB-PIF association have been well studied and are central to light-regulated synthetic tools...
May 15, 2017: Photochemistry and Photobiology
https://www.readbyqxmd.com/read/28477379/tolyporphin-an-unusual-green-chlorin-like-dioxobacteriochlorin
#18
Christian Brückner
The tolyporphins, a family of green tetrapyrrolic pigments isolated from a cyanobacterium-microbial ecological unit, possess unique carbohydrate-derivatized dioxobacteriochlorin frameworks. A brief overview over the history, synthesis, chemistry, and biological properties of the tolyporphins form the backdrop for highlighting the contribution by Hood et al. [Hood, D., D. M. Niedzwiedzki, R. Zhang, Y. Zhang, J. Dai, E. S. Miller, D. F. Bocian, P. G. Williams, J. S. Lindsey and D. Holten (2017) Photochem. Photobiol...
May 6, 2017: Photochemistry and Photobiology
https://www.readbyqxmd.com/read/28477352/study-on-the-basic-performance-of-three-phase-fluidized-bed-equipment-for-solar-photocatalysis-membrane-separation
#19
Li Sha, Liping Xie, Miaomiao Li, Xuening Fei, Jinshan Du, Chenxi Zou
In this study, three-phase fluidized bed equipment for the solar photocatalysis-membrane separation (E-SPME), comprising solar photocatalytic degradation and membrane separation zones, was first introduced, and the photocatalytic degradation of acid red B wastewater (ARBW) with a TiO2 photocatalyst was investigated using the E-SPME. The experimental results indicated the circulating flow of wastewater between the two zones and the increase in the ARBW photocatalytic degradation efficiency with decreasing membrane flux...
May 6, 2017: Photochemistry and Photobiology
https://www.readbyqxmd.com/read/28477350/protonation-state-coupled-conformational-dynamics-in-reaction-mechanisms-of-channel-and-pump-rhodopsins
#20
Ana-Nicoleta Bondar, Jeremy C Smith
Channel and pump rhodopsins use energy from light absorbed by a covalently bound retinal chromophore to transport ions across membranes of microbial cells. Ion transfer steps, including proton transfer, can couple to changes in protein conformational dynamics and water positions. Although general principles of how microbial rhodopsins function are largely understood, key issues pertaining to reaction mechanisms remain unclear. In this review, we compare the protonation-coupled dynamics of pump and channel rhodopsins, highlighting the roles that water dynamics, protein electrostatics, and protein flexibility can have in ion transport mechanisms...
May 6, 2017: Photochemistry and Photobiology
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