bluuebunny/crossref_metadata_2025_split huggingface dataset:
Photodynamics of Cataract: An Update on Endogenous Chromophores and Antioxidants¶
Authors: Balasubramanian D. 
Published: July 2010

ABSTRACTCataract of the eye lens is characterized by (1) Progressive opacification or los of transparency; (2) accumulation of molecules that absorb in the UV ‐visible range of the spectrum; and (3) formation of fluid‐filled vacuoles, particularly in diabetics when sugar levels in teh lens are high. Of the various causative factors for cataract, light is an important one. Because the level of light below 320 nm reaching the lens is quite low, photodynamic effects of endogenous compounds absorbing in the UV‐A‐visible region become important in this connection. In this uupdate we summarize a list of accumulant chrompphores tha have been identified in aging and cataract human lenses and theilr roles as potential sensitizers, antioxidants or as benign filters. Because such photodynamic cataractogenesis is oxidative in nature, we also cite examples where administratiion of antioxidants could help delay cataract progression.
Time‐resolved Microspectrofluorimetry and Fluorescence Lifetime Imaging of Hypericin in Human Retinal Pigment Epithelial Cells¶
Authors: Taroni Paola , Valentini Gianluca , Comelli Daniela , D'Andrea Cosimo , Cubeddu Rinaldo , Hu Dan‐Ning , Roberts Joan E. 
Published: July 2010

ABSTRACTHypericin is the active ingredient of the off‐the‐shelf antidepressant St. John's Wort. It is an effective phototoxic agent and its systemic administration at therapeutic doses could induce particular damage in the eye due to continuous light exposure. Hypercin is strongly fluorescent and its fluorescence properties can be monitored to investigate noninvasively its localization and interactions. To this aim, time‐resolved microspectrofluorimetry and fluorescence life‐time imaging were used to assess the spectral and temporal properties as well as the spatial distribution of the fluorescence emitted by retinal pigment epithelium (RPE) cells treated with Hyp at concentrations in the micromolar range (0.5–10 μM). In the presence of hypericin, the emission peaks at 600‐605 nm and the fluorescence decay is best fitted with three lifetimes (5.5‐7 ns, 1.9‐2.5 ns and < 0.8 ns). Spectral and temporal differences were observed between high (≥5 μM) and low hypericin concentrations. In particular, upon increasing concentration, the emission spectrum of the slow component broadens and its lifetime shortens. The latter change is observed also when high concentrations are reached locally, due to more efficient localization within the cell.
Rhodopsin Phosphorylation in Rats Exposed to Intense Light¶
Authors: Ablocnzy Z. , Darrow R. M. , Knapp D. R. , Organisciak D. T. , Crouch R. K. 
Published: July 2010

ABSTRACTThe damaging effects of intense light on the rat retina are known to vary depending on the time of day of exposure. The purpose of this study was to determine if rhodopsin phosphorylation patterns, a measure of the activity of the pigment, varied in a similar manner. After 10 min in strong light (1400 lux), all six threonine and serine sites in the rat rhodopsin C‐terminus were phosphorylated, with mono‐ to tetraphosphorylation being substantially more prominent than penta‐ to hexaphosphorylation. The level and multiplicity of rhodopsin phosphorylations were reduced both with the duration of light exposure and the duration of subsequent darkness. Although showing vast differences in susceptibility to light damage, rats exposed at 5 P.M. or 1 A.M. showed similar rhodopsin phosphorylation levels and patterns. These data indicate that a process controlled by circadian rhythm other than rhodopsin phosphorylation is involved either in damaging or mediating the damage evoked by intense light exposure.
A Comparison of the Sensitivity of Photodamage Assays in Rat Basophilic Leukemia Cells¶
Authors: Barth Erin E. , Hallworth Richard , Nichols Michael G. 
Published: July 2010

ABSTRACTMany aspects of cellular function or physiology can be used to indicate the level of damage resulting from the application of potentially deleterious agents such as drugs, solvents or even light. The dose required to reach a specific biological endpoint will necessarily depend on the characteristics of the damage induced by the agent. By using multiple biological probes, it is possible to get a more complete description of the type of damage induced. Photodamage was induced in rat basophilic leukemia cells by either 254‐nm UVC light exposure or rose bengal photosensitization. Damage was measured by three quantitative assays employing fluorescent probes: calcein, to measure nonspecific esterase activity, propidium iodide (PI), to measure loss of plasma membrane integrity, rhodamine 123 (R123) to measure mitochondrial depolarization, and the incorporation of 5′‐bromodeoxyuridine (BrdU), to measure the progress of cell replication. BrdU incorporation was found to be the most sensitive indicator for both forms of photodamage. For UVC photodamage, the BrdU assay was 330 times more sensitive than the other two assays. For rose bengal photosensitization, the BrdU assay was 48 or 62 times more sensitive than either the R123 or calcein/PI assays, respectively.
Environmental UV‐A and UV‐B Threshold Doses for Apoptosis and Necrosis in Humans Fibroblasts¶
Authors: Matta Jaime L. , Ramos Juan M. , Armstrong Roy A. , D'Antoni Hector 
Published: July 2010

ABSTRACTApoptosis involves a highly organized and programmed series of events aimed at maintaining genomic stability by eliminating defective host cells. The purpose of this study was to determine the threshold doses and environmental UV‐A and UV‐B exposure times necessary to produce apoptosis and necrosis in the normal cells of a human fibroblast cell line. Enviromental UV‐A and UV‐B doses were measured over a 6 year period with a four‐channel UV radiometer. The fibroblasts were irradiated once using an Oriel UV Solar Simulator with six doses of environmentally‐based UV. Doses corresponded to 0,11,19,23 and 45 min of average environmental UV‐A and UV‐B radiation at solar noon in Puerto Rico. The Annexin‐V binding method was used to differentiate between normal fibroblasts and apoptotic or necrotic fibroblasts. The threshold dose from apoptosis to necrosis was found between 24–28 kJ/m2, which corresponded to 19 and 23 min of environmental UV‐A and UV‐B exposure. This study provides the first data that specify the environmental threshold doses of UV‐A and UV‐B at which human fibroblasts undergo apoptosis and necrosis. These results may provide valuable dose‐response thresholds for apoptosis and necrosis for future mechanistic studies and baseline data for skin cancer prevention programs.
Studies on the Subcellular Localization of the Porphycene CPO¶
Authors: Kessel David , Conley Mary , Graç M. , Vicente H. , Reiners John J. 
Published: July 2010

ABSTRACTThis study was designed to provide more detailed information on the subcellular sites of binding of the porphycene, termed 9‐capronyloxytetrakis (methoxyethyl) porphycene (CPO), with a fluorescence resonance energy transfer (FRET) technique. The proximity of CPO to two fluorescent probes was determined: nonyl acridine orange (NAO), a dye with specific affinity for the mitochondrial lipid cardiolipin, and dihexaoxacarbocyanine iodide (DiOC6), an agent that labels the endoplasmic reticulum (ER). FRET spectra indicated energy transfer between DiOC6 and CPO but no significant transfer between NAO and CPO. These results confirm data obtained by fluorescence microscopy, suggesting a similar pattern of subcellular localization by CPO and DiOC6 but not by CPO and NAO. However, when cells containing CPO were irradiated and then loaded with NAO, FRET between the two fluorophores was observed. Hence, a relocalization of CPO can occur during irradiation. These data provide an explanation for recent studies on CPO‐catalyzed photodamage to both ER and mitochondrial Bcl‐2.
Photosynthetically Active Sunlight at High Southern Latitudes¶
Authors: Frederick John E. , Liao Ylxiang 
Published: July 2010

ABSTRACTA network of scanning spectroradiometers has acquired a multiyear database of visible solar irradiance, covering wavelengths from 400 to 600 nm, at four sites in the high‐latitude Southern Hemisphere, from 55°S to 90°S. Monthly irradiations computed from the hourly measurements reveal the character of the seasonal cycle and illustrate the role of cloudiness as functions of latitude. Near summer solstice, the combined influences of solar elevation and the duration of daylight would produce a monthly irradiation with little latitude dependence under clear skies. However, the attenuation associated with local cloudiness varies geographically, with the greatest effect at the most morthern locations, Ushuaia, Argentina and Palmer Station on the Antartic Peninusula. Near summer solstice, the South Pole experiences the largest monthly irradiation of the sites studied, where relatively clear skies contribute to this result. Scaling factors derived from radiative‐transfer calculations combined with the measured 400–600 nm irradiances allow estiamting irradiances integrated over the wavelength band 400–700 nm. This produces a climatology of photosynthetically active radiation for each month of the year at each site.
Protective Effects of Cyanidin‐3‐O‐β‐glucopyranoside Against UVA‐induced Oxidative Stress in Human Keratinocytes¶
Authors: Tarozzi Andrea , Marchesl Alessandra , Hrelia Silvana , Angeloni Cristina , Andrisano Vincenza , Fiori Jessica , Cantelli‐Forti Giorglo , Hrella Patrizia 
Published: July 2010

ABSTRACTUltraviolet‐A (UVA) radiation causes significant oxidative stress because it leads to the generation of reactive oxygen species (ROS), leading to extensive cellular damage and eventual cell death either by apoptosis or necrosis. We evaluated the protective effects of cyanidin‐3‐O‐β‐glucopyranoside (C‐3‐G) against UVA‐induced apoptosis and DNA fragmentation in a human keratinocyte cell line (HaCaT). Treatment of HaCaT cells with C‐3‐G before UVA irradiation inhibited the formation of apoptotic cells (61%) and DNA fragmentation (54%). We also investigated antioxidant properties of C‐3‐G in HaCaT cells against ROS formation at apoptotic doses of UVA; C‐3‐G inhibited hydrogen peroxide (H2O2) release (an indicator of cellular ROS formation) after UVA irradiation. Further confirmation of the potential of C‐3‐G to counteract UVA‐induced ROS formation comes from our demonstration of its ability to enhance the resistance of HaCaT cells to the apoptotic effects of both H2O2 and the superoxide anion (O2•−), two ROS involved in UVA‐oxidative stress. Furthermore, in terms of Trolox Equivalent Antioxidant Activity, C‐3‐G treatment led to a greater increase in antioxidant activity in the membrane‐enriched fraction than in the cytosol (55%vs 19%). The protective effects against UVA‐induced ROS formation can be attributed to the higher membrane levels of C‐3‐G incorporation. These encouraging in vitro results support further research into C‐3‐G (and other anthocyanins) as novel agents for skin photoprotection.
Photooxidative Treatment of Sulfurous Water for Its Potabilization¶
Authors: Hernández Fernando , Geissler Gunther 
Published: July 2010

ABSTRACTThe feasibility of potabilization of sulfurous water was investigated by photochemical oxidation processes using a batch photoreactor and a continuous‐flow photoreactor, equipped with UV lamps of 1000 W and 1500 W, respectively. Additionally, two advanced processes of oxidation were applied i.e. with a use of a UV light/H2O2/air and UV light/H2O2/O3/air. These two processes were compared for their efficiency to the direct oxidation process where ozone is used in the absence of UV light. Results obtained for both advanced processes showed better oxidation than takes place by ozone in the absence of UV light. After the photooxidation processes, different processes for the absorption or precipitation of sulfates were investigated to comply with the World Health Organization (WHO) norm that demands a limit of ≤250 mgL−1 of SO42− in drinking water. Additionally, reverse osmosis was simulated using Osmonics Inc. software to predict the feasibility of lowering the salt concentration below WHO limits.
Synthesis, Photophysical, Photochemical and Biological Properties of Caged GABA, 4‐[[(2H‐1‐Benzopyran‐2‐one‐7‐amino‐4‐methoxy) carbonyl] amino] Butanoic Acid¶
Authors: Cürten Beate , Kullmann Paul H. M. , Bier Mark E. , Kandler Karl , Schmidt Brigitte F. 
Published: July 2010

ABSTRACTThe photorelease of a caged neurotransmitter can be used to investigate the function of neuronal circuits in tissues. We have designed and synthesized a stable, caged γ‐aminobutyric acid (GABA) derivative, 4‐[[(2H‐1‐benzopyran‐2‐one‐7‐amino‐4‐methoxy)carbonyl]amino] butanoic acid (BC204), that releases the neurotransmitter in physiological medium when irradiated with UV light at 300–400 nm in PBS at pH 7.4. The release of GABA occurs with the formation of the major photoproduct, 7‐amino‐4‐(hydroxymethyl)‐2H‐1‐benzopyran‐2‐one, via a solvolytic photodegradation mechanism of the coumarin moiety and was confirmed by electrospray mass spectrometry/mass spectrometry (ESI MS/MS). BC204 is chemically stable and shows no intrinsic activity after many hours under physiological dark conditions. These properties suggest that BC204 is an excellent form of caged GABA that is well suited for long‐term biological studies.
Adaptation of the Human Skin by Chronic Solar‐simulating UV Irradiation Prevents Ultraviolet‐B Irradiation‐induced Rise in Serum C‐Reactive Protein Levels¶
Authors: Laihia Jarmo K. , Koskinen Janne O. , Waris Matti E. , Jansén Christer T. 
Published: July 2010

ABSTRACTExposure of the skin to UV radiation induces local inflammation. We hypothesized that inflammation induced by erythemal UV‐B irradiation could elevate levels of serum C‐reactive protein (CRP) and that suberythemal repeating doses of solar‐simulating UV radiation (SSR) would produce photoadaptation to such inflammation. Separation‐free high‐sensitivity assays of CRP show an increase by 42% (P= 0.046) in CRP concentrations in healthy human subjects 24 h after a 3 minimal erythemal dose (MED) dose of UV‐B delivered onto a 100 cm2 skin area. Preceding daily suberythemal doses of whole‐body SSR for 10 or 30 consecutive days completely prevented the CRP increase. UV‐B‐induced skin erythema was partially attenuated by 30 preceding days of SSR only (P= 0.00066). After 10 daily SSR doses, the mean baseline CRP concentrations (0.24 ± 0.21 mg/L) declined by 35% (P= 0.018). Using high‐sensitivity analysis of serum CRP as the endpoint marker for cutaneous inflammation, we show that acute exposure of even a relatively small skin area to erythemal UV‐B induces skin inflammation detectable also at the systemic level and that photoadaptation by preceding repeating suberythemal doses of SSR reduces signs of inflammation. Our data complement the view given by previous studies in that local photoadaptation also has systemic manifestations.
Determination of Stereochemistry of Bacteriochlorophyll gF and 81‐Hydroxy‐chlorophyll aF from Heliobacterium modesticaldum¶
Authors: Mizoguchi Tadashi , Oh‐oka Hirozo , Tamiaki Hitoshi 
Published: July 2010

ABSTRACTThe reaction center complex of heliobacteria contains three kinds of chlorophyll pigments, bacteriochlorophyll gF (BChl gF), its 132‐epimer BChl g′F and 81‐hydroxy‐chlorophyll aF (81‐OH‐Chl aF). Because the full stereochemistry of these naturally occurring chlorophyllous pigments has remained unknown, we determined the stereochemistry of both BChl gF and 81‐OH‐Chl aF extracted from Heliobacterium modesticaldum. The configurations of the specific functional groups at ring‐B as well as those at ring‐D and ‐E were investigated by use of nuclear Overhauser effect correlations in their 1H‐NMR spectra and circular dichroism spectra, as well as by modified Mosher's method in their chemical modification: (1) E‐configuration was confirmed for the 8‐ethylidene group at ring‐B in BChl gF, (2) R‐configuration was identified for the 1‐hydroxyethyl group at ring‐B in 81‐OH‐Chl aF and (3) 132‐(R)‐, 17‐(S)‐ and 18‐(S)‐configurations at ring‐D and ‐E in both BChl gF and 81‐OH‐Chl aF were confirmed. These stereo‐chemistries enabled us to discuss their biosynthesis and to propose possible routes for preparation of ethylidene and 1‐hydroxyethyl groups at the 8‐position.
Photophysical Properties of Tyrosine and Its Simple Derivatives in Organic Solvents Studied by Time‐resolved Fluorescence Spectroscopy and Global Analysis¶
Authors: Guzow Katarzyna , Rzeska Alicja , Mrozek Justyna , Karolczak Jerzy , Majewski Radoslaw , Szabelski Mariusz , Ossowski Tadeusz , Wiczk Wieslaw 
Published: July 2010

ABSTRACTPhotophysical properties of tyrosine and its derivatives with free and blocked functional groups were studied by steady state and time‐resolved fluorescence spectroscopy and global analysis in organic solvents, such as methanol, 2‐propanol, tetrahydrofuran (THF), and dimethylsulfoxide (DMSO). The mono‐exponential fluorescence intensity decays were observed for all tyrosine derivatives in THF and DMSO solutions, whereas in alcohols some derivatives have bi‐exponential decays. The rotamer population calculated from 1H nuclear magnetic resonance spectroscopy in DMSO does not correspond to the pre‐exponential factors obtained from fluorescence spectroscopy. Moreover in the case of DMSO, the strong interaction of this solvent with the hydroxyl group of the fluorophore's phenol ring causes substantial changes in the fluorescence and nonradiative rate constants of tyrosine derivatives compared with those of tyrosine with a blocked hydroxyl group, Tyr(Me). The steady state and time‐resolved fluorescence measurements in pure organic solvents and water‐organic solvent mixtures indicate that the fluorescence quenching of the phenol chromophore of tyrosine by an acetyl or amide group or both depends on the polarity of the solvent used as well as the ability of the solvent to form hydrogen bonds with functional groups of tyrosine.
Photophysical Properties of Crowned Porphyrins¶
Authors: Pelegrino Alessandra C. , Carolina M. M. , Gotardo A. F. , Simioni Andreza R. , Assis Marilda D. , Tedesco Antonio C. 
Published: July 2010

ABSTRACTIn this study, we evaluated the photophysical properties of 5, 10, 15, 20‐tetrakis[4‐(1, 4, 7, 10, 13‐pentaoxacyclopentadecane‐2‐aminomethyl) 2, 3, 5, 6‐(tetrafluoro)‐phenyl]‐porphyrin (H2C4P) and Zn(II)5, 10, 15, 20‐tetrakis [4‐(1, 4, 7, 10, 13‐pentaox‐acyclopenta‐decane‐2‐aminomethyl) 2, 3, 5, 6‐(tetrafluoro)‐phenyl]‐porphyrinate (ZnC4P). We observed that these porphyrins have unique properties when compared with classical porphyrins. The porphyrins H2C4P and ZnC4P showed efficient transfer energy S1 to T1 by intersystem crossing with high and reasonable yields of triplet excited state and singlet oxygen production. These amphiphilic structures of these porphyrins could improve its localization in the tumor cells due to the presence of the crown ether in its framework. We also believed that the crown ether could modulate the change in ion homeostase (Ca+2, K+, Na+) as already described by some new phthalocyanine dye. This fact makes us believe that it could be reasonably used as a photosensitizer for PDT purposes.
Protection by Food‐derived Antioxidants from UV‐A1‐Induced Photodamage, Measured Using Living Skin Equivalents¶
Authors: Dekker Pim , Parish William E. , Green Martin R. 
Published: July 2010

ABSTRACTIn a study of biomarkers of ultraviolet‐A1 radiation (UV‐A1)‐induced skin damage, living skin equivalent cultures (LSE) were treated with the antioxidants hesperetin and quercetin‐3‐glucoside and irradiated with 25 or 50 J/cm2 UV‐A1. Changes in the following biomarkers were measured; Interleukin 1‐alpha (IL‐1α), Heme Oxygenase‐1 (HO‐1), TdT‐mediated dUTP nick end labeling (TUNEL) and 8‐hydroxy‐2′‐deoxyguanosine (8‐OHdG). IL‐1α and HO‐1 were analyzed by realtime PCR, Western blot, enzyme‐linked immunosorbent assay (ELISA) and immunohistochemistry. TUNEL and 8‐OHdG were determined by (immuno)histochemical techniques. Sections were stained with hematoxylin and eosin (H&E). UV‐A1 induced keratinocyte and fibroblast vacuolation and nuclear pyknosis, intense TUNEL staining of fibroblasts and increased staining of cells and nuclei for 8‐OHdG. Lesser or marginal increases in intensity followed staining for HO‐1 and IL‐1α. The IL‐1α increase was confirmed by ELISA assays of the medium supernatants. Hesperetin and quercetin‐3‐glucoside reduced changes in H&E, 8‐OHdG, TUNEL and IL‐1α. Quercetin‐3‐glucoside reduced the amount of IL‐1α in LSE media. These observations support the use of the selected biomarkers to monitor UV‐A1 damage and provide evidence that dietary ingredients could reduce ultraviolet‐A radiation‐induced damage.
A New Firefly Luciferase with Bimodal Spectrum: Identification of Structural Determinants of Spectral pH‐Sensitivity in Firefly Luciferases¶
Authors: Viviani Vadim R. , Oehlmeyer T. L. , Arnoldi F. G. C. , Brochetto‐Braga M. R. 
Published: July 2010

ABSTRACTFireflies emit flashes in the green‐yellow region of the spectrum for the purpose of sexual attraction. The bioluminescence color is determined by the luciferases. It is well known that the in vitro bioluminescence color of firefly luciferases can be shifted toward the red by lower pH and higher temperature; for this reason they are classified as pH‐sensitive luciferases. However, the mechanism and structural origin of pH sensitivity in fireflies remains unknown. Here we report the cloning of a new luciferase from the Brazilian twilight active firefly Macrolampis sp2, which displays an unusual bimodal spectrum. The recombinant luciferase displays a sensitive spectrum with the peak at 569 nm and a shoulder in the red region. Comparison of the bioluminescence spectra of Macrolampis, Photinus and Cratomorphus firefly luciferases shows that the distinct colors are determined by the ratio between green and red emitters under luciferase influence. Comparison of Macrolampis luciferase with the highly similar North American Photinus pyralis luciferase (91%) showed few substitutions potentially involved with the higher spectral sensitivity in Macrolampis luciferase. Sitedirected mutagenesis showed that the natural substitution E354N determines the appearance of the shoulder in the red region of Macrolampis luciferase bioluminescence spectrum, helping to identify important interactions and residues involved in the pH‐sensing mechanism in firefly luciferases.
Reactions of Excited States of Phenoxazin‐3‐one Dyes with Amino Acids¶
Authors: Villegas M. L. , Bertolotti S. G. , Previtali C. M. , Encinas M. V. 
Published: July 2010

ABSTRACTThe interaction with amino acids of the excited states of the N‐oxide resazurin and its deoxygenation product resorufin, has been studied in aqueous solution at pH 7.5. Steady‐state and time‐resolved studies show that the fluorescence is quenched by amino acids. Complexation of the dyes in the ground state with aromatic amino acids was also observed. The singlet quenching is attributed to electron transfer from the aminoacids to the excited dye based on the dependence of the bimolecular rate constants with the ionization potential of quenchers. Flash photolysis experiments allowed determination of the quenching rate constants for the triplet deactivation of dyes by several amino acids, as well as the characterization of the transients formed in the process. These data show that the triplet is also deactivated by an electron transfer process. However, the deactivation of the N‐oxide dye by tryptophan can be described by a hydrogen atom transfer. The protolytic dissociation constants of the dye radical ions are reported. The irradiation of rezasurin in the presence of amino acids leads to deoxygenation of the dye to give resorufin. This process involves the triplet excited state of resazurin and is efficient only in the presence of amino acids containing the ‐SH group.