bluuebunny/crossref_metadata_2025 huggingface dataset:
Dermatological Risk of Indoor Ultraviolet Exposure from Contemporary Lighting Sources¶†‡§
Authors: Sayre Robert M. , Dowdy John C. , Poh‐Fitzpatrick Maureen
Published: July 2010

Discussions of risks and implications of cutaneous exposure to indoor lighting, including hypothetical contribution to causality of melanoma, have mainly concentrated on ultraviolet (UV) A and B (UVA, UVB) spectral emissions from fluorescent bulbs. Only studies of quartz halogen lamps have suggested that users might sustain UVC‐induced injury. Examination of light sources in the home and school of a child with xeroderma pigmentosum revealed that several different types emitted surprising levels of UV. Our purpose was to assess the extent of UV emissions from a variety of commonly used light sources to identify potential dermatological risks. UV and visible spectral emissions of commercially obtained lamps of several types were measured using a calibrated spectral radiometer traceable to the National Institute of Standards and Technology. Indoor light sources including fluorescent, quartz halogen and even tungsten filament incandescent lamps provided UVA, UVB and sometimes UVC emissions. Intensities of some emissions were of similar magnitude to those in sunlight. Chronic exposure to indoor lighting may deliver unexpected cumulative UV exposure to the skin and eyes. Patients with UV‐exacerbated dermatoses should be cautioned about potential adverse reactions from indoor lighting.
Suppression of Different Phases of Systemic Contact Hypersensitivity by Urocanic Acid Oxidation Productsfn1
Authors: Kammeyer Arthur , Garssen Johan , Sleijffers Annemarie , van Loveren Henk , Eggelte Teunis A. , Bos Jan D. , Teunissen Marcel B. M.
Published: July 2010

On exposure to UV‐B, the epidermal component trans‐urocanic acid (UCA) is not only photoisomerized into cis‐ UCA but will also, at least in part, be photooxidized into UCA oxidation products (UOPs). We hypothesized that UOPs can mimic UV‐induced systemic immunosuppression comparable to the suppressive properties already established for cis‐UCA. A crude mixture of UOPs showed a significant suppression of the sensitization phase of the systemic contact hypersensitivity (CHS) response to picryl chloride (PCI). Three of the UOPs were selected for this study: imidazole‐4‐carboxylic acid (ImCOOH), immidazole‐4‐carboxaldehyde (ImCHO) and imidazole‐4‐acetic acid (ImAc). Effects on the sensitization, elicitation and postelicitation phases of CHS to PCI in BALB/c mice were studied and compared with the effects of cis‐UCA. ImCHO was equally effective at suppressing the sensitization phase as cis‐UCA. The triplet combination of the imidazoles (1:1:1) showed more pronounced suppression than that induced by cis‐UCA. The most effective compounds for the suppression of the elicitation phase appeared to be ImAc and cis‐UCA. Significant suppression of the postelicitation phase was only obtained with the triplet combination of ImCHO, ImCOOH and ImAc, the combination that appeared to be effective at all three tested phases. Because these three UOPs are present in UV‐B‐exposed human stratum corvneum, these compounds may play a role in UV‐B‐induced immunosuppression.
Effects of UV‐B Irradiation on a Marine Microecosystem¶
Authors: Marangoni Roberto , Messina Nicola , Gioffré Domenico , Colombetti Giuliano
Published: July 2010

Purpose of this work was to study the effect of UV irradiation on a microecosystem consisting of several interacting species. The system chosen was of a hypersaline type, where all the species present live at high salt concentration; it comprises different bacteria; a producer, the photosynthetic green alga Dunaliella salina; and a consumer, the ciliated protozoan Fabrea salina, which form a complete food chain. We were able to establish the initial conditions that give rise to a selfsustaining microecosystem, stable for at least 3 weeks. We then determined the effect of UV irradiation on this microecosystem under laboratory‐controlled conditions, in particular by measuring the critical UV exposure for the two main components of the microecosystem (algae and protozoa) under UV‐B irradiances comparable to those of solar irradiation. In our experiments, we varied irradiance, total dose and spectral composition of the actinic light. The critical doses at irradiances of the order of 56 kJ/m2 (typical average daily irradiance in a sunny summer day in Pisa), measured for each main component of the microecosystem (algae and ciliates), turned out to be around 70 kJ/m2 for ciliates and 50 kJ/m2 for D. salina. By exposing microecosystems to daily UV‐B irradiances of the order of 8 kJ/m2 (typical average daily irradiance in a sunny winter day in Pisa), we found no effect at total doses of the order of the critical doses at high irradiances, showing that the reciprocity law does not hold. We have also measured a preliminary spectral‐sensitive curve of the UV effects, which shows an exponential decay with wavelength.
Characterization of the Fe(III)‐binding Site in Sepia Eumelanin by Resonance Raman Confocal Microspectroscopy¶
Authors: Samokhvalov Alexander , Liu Yan , Simon John D.
Published: July 2010

The resonance Raman spectrum of Sepia eumelanin is discussed by analogy to model compounds containing catechol (CAT)‐like structural units. These data are then compared with the analogous data on Fe(III)‐enriched Sepia eumelanin. In contrast to the natural eumelanin, the Fe(III)‐enriched samples exhibit absorption features in the visible and near‐IR spectral regions, which are attributed to ligand‐to‐metal charge‐transfer (LMCT) bands. Resonance Raman spectra collected by exciting these LMCT bands reveal bands at 580 and 1470 cm−1; the intensity of these features increases wioth increasing Fe(III) content. The 580 and 1470 cm−1 bands are assigned to Fe‐OR stretching and ring deformation modes, respectively. These data further substantiate that the Fe(III)‐ melanin‐binding site in melanin is composed of CAT‐like structural units.
Photophysical Properties of Coumarin‐30 Dye in Aprotic and Protic Solvents of Varying Polarities¶
Authors: Senthilkumar Sadasivam , Nath Sukhendu , Pal Haridas
Published: July 2010

Experimental results on various photophysical properties of coumarin‐30 (C30) dye, namely, Stokes' shift (Δv), fluorescence quantum yield (τf), fluorescence lifetime (τf), radiative rate constant (kf) and nonradiative rate constant (knr), as obtained using absorption and fluorescence measurements have been reported. Though in most of the solvents the properties of C30 show more or less linear correlation with the solvent polarity function, Δf= [(ε ‐ 1)/(2ε+ 1) ‐ (n2 ‐ 1)/ (2n2+ l)], they show unusual deviations in nonpolar solvents at one end and in high‐polarity protic solvents at the other end. From the solvent polarity and temperature effect on the photophysical properties of the dye, following inferences have been drawn: (1) in nonpolar solvents, the dye exists in a nonpolar structure, where its 7‐NEt2 substituent adopts a pyramidal configuration and the amino lone pair is out of resonance with the benzopyrone π cloud; (2) in medium to higher polarity solvents, the dye exists in a polar intra‐molecular charge transfer structure, where the 7‐NEt2 group and the 1,2‐benzopyrone moiety are in the same plane and the amino lone pair is in resonance with the benzopyrone π cloud; (3) in protic solvents, the dye‐solvent intermolecular hydrogen bonding influences the photophysical properties of the dye; and (4) in high‐polarity protic solvents, the excited C30 undergoes a new activation‐controlled nonradiative deexcitation process because of the involvement of a twisted intra‐molecular charge transfer (TICT) state. Contrary to most other TICT molecules, the activation barrier for this deexcitation process in C30 is observed to increase with solvent polarity. A rational for this unusual behavior has been given on the basis of the solvent polarity‐dependent stabilization and crossing of relevant electronic states and the relative propensity of interconversion among these states.
The Fluorescence Properties of Hypocrellin B and its Amino‐substituted Derivative: Photinduced Intramolecular Proton Transfer and Photoinduced Intramolecular Electron Transfer¶
Authors: Xu Shangjie , Zhang Xiaoxing , Chen Shen , Zhang Manhua , Shen Tao
Published: July 2010

We report on the emission spectra and emission quantum yields of a newly synthesized hypocrellin dye, Z‐demethoxy‐ 2,3‐ethylenediamino hypocrellin B (EDAHB), and its parent HB in different solvents of varying polarity. Our results demonstrate that EDAHB is one of the few dyes that exhibit highly solvent polarity‐dependent fluorescence in the useful region (680–730 nm). Therefore, it offers some applications in the biomedical field as a fluorescent probe molecule. The solvatochromic effect of EDAHB is proposed to be due to a distinct change in the dipole moment of the dye on excitation. A photoinduced intramolecular proton transfer and a photoinduced intramolecular electron transfer process are considered relevant for the fluorescence properties of HB and EDAHB, respectively.
Light Modulates Electric Phenomena in Hornet Cuticle¶
Authors: Ishay Jacob S. , Sverdlov Anna , Pertsis Vitaly , Gavrilov Yulla , Steinberg David
Published: July 2010

In the cuticle of live social hornets, such as Vespa orientalis (Hymenoptera, Vespinae), endogenous electric effects are encountered, i.e. voltages of 100–200 mV under illumination and currents amounting to several microamperes on its subjection to darkness—clearly a process of charging and discharging. Of the various wavelengths of sunlight, UV was found to be the most contributory to the active cuticular voltage generation. Throughout the warm season of the yearthe–the active period in colonies of social hornets and wasps—colony members exit from the dark nest during the daytime and fly to the field under the hot sun for various foraging purposes, ultimately returning to the nest. Thus, each hornet, be it queen, worker or drone, probably undergoes daily cyclical process of electric charge and discharge in the exterior part of their integument, cuticle, which lasts up to 30–40 min. Such photoelectric phenomenon was detected in both live, ether‐anaesthetized hornets and dead hornets, albeit in the latter the electric values recorded were lower. The present study addresses the possible impact of the phenomenon on vespan daily life and also compares it with a parallel occurrence in electric fish.
Energy Dissipation Processes of singlet‐excited 1‐Hydroxyfluorenone and its Hydrogen‐bonded Complex with N‐methylimidazole¶
Authors: Sebök‐Nagy Krisztina , Biczók László , Morimoto Akimitsu , Shimada Tetsuya , Inoue Haruo
Published: July 2010

Effects of solvent, pH and hydrogen bonding with N‐methylimidazole (MIm) on the photophysical properties of 1‐hydroxyfluorenone (1HOF) have been studied. Fluorescence lifetime, fluorescence quantum yield and triplet yield measurements demonstrated that intersystem crossing was the dominant process in apolar media and its rate constant significantly diminished with increasing solvent polarity. The acceleration of internal conversion in alcohols paralleled the strength of intermolecular hydrogen bonding. The faster energy dissipation from the singlet‐excited state in cyclohexane was attributed to intramolecular hydrogen bonding. The pKa of 1HOF decreased from 10.06 to 5.0 on light absorption, and H3O+ quenched the singletexcited molecules in a practically diffusion‐controlled reaction. On addition of MIm in toluene, dual fluorescence was observed, which was attributed to reversible formation of excited hydrogen‐bonded ion pair. Rate constants for the various deactivation pathways were derived from the combined analysis of the steady‐state and the time‐resolved fluorescence results.
The Effects of the Substitution on the lmidazole Ligand on the Photochemical Properties of fac[Mn(CO)3(phen)(lmidazole)](SO3CF3) Complexes¶
Authors: Carlos Rose Maria , Neto Benedito S. Lima , Neumann Miguel G.
Published: July 2010

Photochemical and photophysical data are reported for a series of fac‐[Mn(CO)3(phen)(Im‐R)](SO3CF3) complexes, where phen is 1,10‐phenanthroline and Im is imidazole. Intraligand and metal‐to‐ligand charge transfer (MLCT) transitions are observed in the electronic absorption spectra of these complexes and are sensitive to the nature of the ligand substituent. At room temperature the emission spectra show a clear progression from broad structureless MLCT to highly structured π‐π* emission on going from R = ‐H, ‐CH3, ‐C6H5, to ‐Metro, where Metro is 2‐methyl‐5‐nitroimidazole. Even at low temperatures the latter complexes show only the π‐π* emission. The trend in the photophysical properties found in the emission spectra parallels the changes in the photochemical properties with the electron‐donating or electron‐withdrawing power of the substituent on the imidazole ligand. Although MLCT irradiation of the complexes with R = ‐H, ‐CH3 leads to the mer‐[Mn(CO)3(phen)(Im‐R)]+ isomers, the complexes with the imidazole ligand substituted by ‐C6H5 or ‐Metro release the Im‐R ligand and produce the stereoretentive fac‐[Mn(CO)3(phen)(S)]+ complexes. The stereochemical fate and mechanistic implications of the photolysis reactions are discussed in terms of the nature of ligand substitution.
Isolation and Characterization of a Novel Cross‐link Lesion in d(CpC) Induced by One‐electron Photooxidation¶
Authors: Liu Zhenjiu , Gao Yuan , Zeng Yu , Fang Fang , Chi Dahn , Wang Yinsheng
Published: July 2010

Recently we reported the identification and characterization of a novel cross‐link lesion formed between two adjacent cytosines in d(CpC), which is the major product formed upon 365 nm photoirradiation of d(CpC) in the presence of 2‐methyl‐1,4‐naphthoquinone. In this study we discuss the isolation and structure characterization of another cross‐link lesion formed under the same irradiation condition. Electrospray ionization mass spectroscopy, tandem mass spectrometry and two‐dimensional nuclear Overhauser effect spectroscopy results demonstrate that the C6 carbon atom of the 5’cytosine and the N3 nitrogen atom of the 3’cytosine are covalently bonded. In addition, the 5’cytosine moiety deaminated and the C5 carbon atom in this cytosine is oxidized to a carbonyl group.
Correlation Between Oxygen Consumption and Photobleaching During In Vitro Photodynamic Treatment with ATX‐S10‐Na(II) Using Pulsed Light Excitation: Dependence of Pulse Repetition Rate and Irradiation Time¶
Authors: Kawauchi Satoko , Sato Shunichi , Morimoto Yuji , Kikuchi Makoto
Published: July 2010

We revealed that in ATX‐S10‐Na(II)(13,17‐bis (1‐carboxypropionyl) carbamoylethyl‐8‐etheny‐2‐hydroxy‐3‐hydroxyiminoethylidene‐2,7,12, 18‐tetraethyl porphyrin sodium)‐mediated photodynamic therapy using 667 nm nanosecond‐pulsed light excitation at a peak intensity of 2.0 MW/cm2, photoxicity increased with decreasing pulse repetition rate in the range of 5‐30 Hz for A549 cell cultures. To examine the relation between the reaction mechanism and measured phototoxicity, we carefully measured the kinetics of photochemical oxygen consumption and photobleaching during irradiation of ATX‐S10‐Na(II)‐sensitized A549 monolayer cultures. Measurements of oxygen consumption with a microelectrode, which was performed just above the cells, showed that there was no significant difference between the magnitudes of decrease in oxygen at the three repetition rates at the same cumulative fluence. Loss of ATX‐S10‐Na(II) fluorescence intensity also exhibited little repetition rate dependence when compared at the same cumulative fluence. We investigated the correlation between oxygen consumption and photobleaching during irradiation and obtained “fluorescence‐oxygen diagrams.” The diagrams showed dynamic changes between oxygen‐dependent and oxygen‐independent photobleaching at the higher repetition rates of 10 and 30 Hz, whereas such change was not clearly seen over the whole irradiation time at 5 Hz. These results suggest that the reduced phototoxicity at high repetition rates might be due to an oxygen‐independent reaction. We presumed that the change in the reaction mechanism was associated with the local concentrations of the photosensitizer and oxygen in cells during irradiation.
Plant Responses to Current Solar Ultraviolet‐B Radiation and to Supplemented Solar Ultraviolet‐B Radiation Simulating Ozone Depletion: An Experimental Comparison¶
Authors: Rousseaux M. Cecilia , Flint Stephan D. , Searles Peter S. , Caldwell Martyn M.
Published: July 2010

Field experiments assessing UV‐B effects on plants have been conducted using two contrasting techniques: supplementation of solar UV‐B with radiation from fluorescent UV lamps and the exclusion of solar UV‐B with filters. We compared these two approaches by growing lettuce and oat simultaneously under three conditions: UV‐B exclusion, near‐ambient UV‐B (control) and UV‐B supplementation (simulating a 30% ozone depletion). This permitted computation of “solar UV‐B” and “supplemental UV‐B” effects. Microclimate and photosynthetically active radiation were the same under the two treatments and the control. Excluding UV‐B changed total UV‐B radiation more than did supplementing UV‐B, but the UV‐B supplementation contained more “biologically effective” shortwave radiation. For oat, solar UV‐B had a greater effect than supplemental UV‐B on main shoot leaf area and main shoot mass, but supplemental UV‐B had a greater effect on leaf and tiller number and UV‐B‐absorbing compounds. For lettuce, growth and stomatal density generally responded similarly to both solar UV‐B and supplemented UV‐B radiation, but UV‐absorbing compounds responded more to supplemental UV‐B, as in oat. Because of the marked spectral differences between the techniques, experiments using UV‐B exclusion are most suited to assessing effects of present‐day UV‐B radiation, whereas UV‐B supplementation experiments are most appropriate for addressing the ozone depletion issue.
Comparison of Nonmetal and Metal Hydrophilic Photosensitizer, ATX‐S10 (Na) and ATN‐2, Binding with Human Serum Proteins Using Spectrophotometry¶
Authors: Yamaguchi M. , Tanabe S. , Nakajima S. , Takemura T. , Ogita K. , Kuwayama H. , Sakata I. , Miyaki S. , Suzuki K. , Namiki H. , Uzuka Y. , Sarashina T.
Published: July 2010

Intermolecular interactions of human serum proteins with a hydrophilic nonmetalloporphyrin, 13,17‐bis(1‐carboxy‐propionyl)carbomoylethyl‐8‐ethenyl‐2‐hydroxy‐3‐hydroxy‐iminoethylidene‐2,7,12,18‐tetramethylporphyrin sodium salt (ATX‐S10 (Na)), or a hydrophilic gallium‐metalloporphyrin, diethylenetriamine pentaacetic acid ester of 2‐[1‐(2‐hydroxyethoxy)ethyl]‐4‐vinyl‐deuteroporphyrin (IX) Ga complex (ATN‐2), were investigated using spectrophotometry. ATX‐S10 (Na) caused a bathochromic shift with albumin, high‐density lipoprotein and low‐density lipoprotein, but little or no shift was observed with hemopexin, transferrin and immuno‐globulin G. In contrast, ATN‐2 displayed a bathochromic shift only with hemopexin. These results suggest that the association energy of ATX‐S10 (Na) with albumin might be slightly greater than that with lipoproteins and that of ATN‐2 with hemopexin might be greater than that with other serum proteins.
Cellular Uptake and Photocytotoxicity of Glycoconjugated Porphyrins in Hela Cells.¶
Authors: Hirohara Shiho , Obata Makoto , Salto Atsuhiro , Ogata Shin‐ichi , Ohtsuki Chikara , Higashida Suguru , Ogura Shun‐ichiro , Okura Ichiro , Sugal Yuko , Mikata Yuji , Tanihara Masao , Yano Shigenobu
Published: July 2010

Thirty‐two glycoconjugated porphyrins were synthesized by a modification of Lindsey method in the presence of Zn(OAc)2.2H2O as a template. The Zn2+ ion template strategy improved the yield about three‐fold in the case of meta ‐substituted tetraphenylporphyrins. In addition, free‐base porphyrins were obtained almost quantitatively by demetalation with 4 M HCI. Sixteen deacetylated glycoconjugated porphyrins were tested as candidate photodynamic therapy (PDT) drugs using HeLa cells. Most of the deacetylated glycoconjugated porphyrins showed higher cellular uptake than tetraphenylporphyrin tetrasulfonic acid (TPPS), and 5,10,15, 20‐tetrakis[4‐(β‐D‐arabinopyranosyloxy)phenyl]porphyrin p‐5d) in particular showed 18.5‐fold higher uptake than TPPS. The photocytotoxicity of 5,10,15,20‐tetrakis[4‐(β‐D‐glucopyranosyloxy) phenyl]porphyrin (p‐5a), (p‐5d and TPPS was examined with HeLa cells, using a light dose of 16 J/cm2. These photosensitizers had no cytotoxicity in the dark, but their photocytotoxicity increased in the order of TPPS p‐5a p‐5d. These results suggest p‐5d is a good candidate for a PDT drug.
Photochemical Behavior of a New Long‐chain UV Absorber† Drived from 4‐tert‐Butyl‐4′‐Methoxydibenzoylmethane¶
Authors: Wetz Fabienne , Routaboul Corinne , Lavabre Dominique , Garrigues Jean‐Christophe , Rico‐Lattes Isabelle , Pernet Ingrid , Denis Alain
Published: July 2010

A new W filter, the 1‐(4‐tert‐butylphenyl)‐2‐decanyl‐3‐(4′‐methoxyphenyl)‐propane‐1,3‐dione, called C10‐DBM, was prepared by grafting a 10‐carbon aliphatic chain to the acarbonyl position of 4‐tert‐butyl‐4′‐methoxydibenzoylmethane (BM‐DBM), a well‐known and often used UV filter. The UV‐A absorption efficiency of organic solutions containing the new filter was tested and compared with identical solutions containing BM‐DBM with or without irradiation (xenon lamp). The originality of this new filter is that its UV‐A absorbance appeared during irradiation of the molecule. Although the molar absorption coefficient of C10‐DBM in the UV‐A domain was lower than that of BM‐DBM, the solutions absorption exhibited a much more photostable behavior under irradiation. In this study, we first demonstrated that C10‐DBM was a precursor of BM‐DBM (enol isomer) by means of high performance liquid chromatography followed by mass spectrometry. Indeed, we showed that the UV‐A absorption of C10‐DBM solutions appearing during the irradiation of the molecule was due to a Norrish‐II reaction (β‐cleavage), which induced the release of the BM‐DBM enol form and l‐decene. Then, we established a kinetic model for the photochemistry of C10‐DBM and fitted the variation of W absorption spectra to confirm the proposed mechanism.
Removing UV‐A and UV‐C Radiation from UV‐B Fluorescent Lamp Emissions. Differences in the Inhibition of Photosynthesis in the Marine Alga Dunaliella tertiolecta Using Chromate Versus Cellulose Acetate‐Polyester Filters¶
Authors: White Andrea L. , Jahnke Leland S.
Published: July 2010

Ultraviolet‐B (UV‐B; 280‐320 nm)‐emitting lamps unavoidably emit ultraviolet‐A (UV‐A; 320‐400 nm) and ultraviolet‐C (UV‐C; < 280 nm) radiation. Short‐wavelength‐blocking filters are generally used to limit the wave bands of UV under investigation. The widespread use of such filters means that all exposures to UV‐B radiation will have a significant UV‐A component. Therefore, the physiological effects unique to UV‐B exposure are difficult to clearly isolate. This study presents a method to remove the UV‐A and UV‐C “contamination” using a liquid potassium chromate (K2CrO4) filter, thus allowing more direct assessment of the effects of UV‐B exposure. Cultures of the green marine alga Dunaliella tertiolecta were grown in the absence of UV radiation. Sunlamps supplied the UV radiation for a 24 h exposure (solar radiation was not used in this study). The UV radiation was filtered either by the standard method (i.e. cellulose acetate (CA) with polyester = Mylar controls) or by a liquid filter of potassium chromate. Photosynthetic responses were compared. Major decreases in the ratio of variable to maximal fluorescence in dark‐adapted cells and photosynthetic capacity were observed in CA‐filtered cultures, whereas no change was observed in cells exposed to the same UV‐B flux with the UV‐A removed by K2CrO4. The use of a CA filter with a Mylar control does not link results unequivocally to UV‐B radiation. Such results should be interpreted with caution.
Quantum Dot Nanocrystals for In Vivo Molecular and Cellular Imaging¶
Authors: Smith Andrew M. , Gao Xiaohu , Nie Shuming
Published: July 2010

Semiconductor quantum dots (QD) are nanometer‐sized crystals with unique photochemical and photophysical properties that are not available from either isolated molecules or bulk solids. In comparison with organic dyes and fluorescent proteins, QD are emerging as a new class of fluorescent labels with improved brightness, resistance against photobleaching and multicolor fluorescence emission. These properties could improve the sensitivity of biological detection and imaging by at least 10‐to 100‐fold. Further development in high‐quality near‐infrared‐emitting QD should allow ultrasensitive and multicolor imaging of molecular targets in deep tissue and living animals. Here, we discuss recent developments in QD synthesis and bioconjugation, applications in molecular and cellular imaging as well as promising directions for future research.
Behaviors Producing Photodispersal in Stentor coeruleus¶
Authors: Menzies Erin , Das NII , Wood David C.
Published: July 2010

The ciliate Stentor coeruleus exhibits photodispersal, that is, these cells swim away from light sources and collect in dimly lighted areas. We imaged and reconstructed the tracks of 48 Stentor to determine which swimming behaviors produced their photodispersal. We observed that their photodispersal is not due to a change in their swimming speed but rather to a change in the frequency with which they reorient their swimming direction. Therefore, their photodispersal must be due to either (1) a gradual reorientation of the organism's swimming direction determined by the direction of the light beam (phototaxis) or (2) multiple randomly directed reorientations in swimming direction that occur less frequently when the cell is swimming away from the light source (biased random walk). Sixteen (19%) of the 83 observed forward swimming tracks lasting three or more seconds exhibited a gradual bending away from the light source consistent with a phototaxis. However, most tracks were interrupted repeatedly by abrupt reorientations resulting from ciliary reversals and “smooth turns” that caused cells to reorient through 5.4 times as many degrees as were needed to direct them away from the light source. When cells were swimming away from the light source, their probability of reorienting was reduced and photodispersal resulted.
Biological Weighting Function of the UV‐B‐induced Impairment of Phototaxis in the Freshwater Ciliate Ophryoglena flava¶
Authors: Marangoni Roberto , Marroni Fabio , Gioffré Domenico , Ghetti Francesco , Colombetti Giuliano
Published: July 2010

We determined the biological weighting function (BWF) of the effect of UV radiation on phototaxis of the freshwater, histophagous ciliate Ophryoglena flava. Dose‐effect curves were measured by exposing the cells to 12 different irradiation regimens obtained with two different levels of UV‐B radiation and by using six filters with cutoff wavelengths ranging from 280 to 335 nm. The results show that there are significant damages to phototaxis at the doses used and that the effect increases when the cutoff is shifted toward short wavelengths. The data were used to calculate the BWF of phototaxis impairment by applying a nonlinear fit procedure. The BWF thus obtained decays exponentially with increasing wavelength in agreement with similar findings reported in the literature for other systems.
Ship‐in‐a‐Bottle Synthesis of Fluorescence‐labeled Nanoparticles: Applications in Cellular Imaging¶
Authors: Chrétien Michelle N. , Shen Biao , García Hermenegildo , English Ann M. , Scaiano J. C.
Published: July 2010

Fluorescein (2‐(6‐hydroxy‐3‐oxo‐(3H)‐xanthen‐9‐yl) benzoic acid) has been prepared inside the pores of zeolite‐Y via ship‐in‐a‐bottle synthesis. Fluorescein, whose dimensions prevent it from entering through the ∼7 Å windows of the faujasite zeolite used, was prepared by the acid‐catalyzed reaction of resorcinol and phthalic anhydride. In this article we report initial spectroscopic data as well as an example of the usefulness of these fluorescence‐labeled nanoparticles for imaging applications such as confocal fluorescence microscopy. Encapsulated fluorescein shows a remarkable increase in photostability.
Surface Plasmon‐coupled Polarized Emission of N‐Acetyl‐l‐Trytophanamide¶
Authors: Gryczynski Ignacy , Malicka Joanna , Lukomska Joanna , Gryczynski Zygmunt , R. Lakowicz Joseph
Published: July 2010

We report an observation of ultraviolet (UV) surface plasmon‐coupled emission (SPCE) of N‐acetyl‐l‐tryptophanamide (NATA). The sample was spin coated from poly(vinyl alcohol) (PVA) solution on 20 nmaluminium film deposited on a quartz substracte. The directional UV SPCE occurs within a well‐defined narrow angle at 52dG from the normal to the coupling hemicylinder quartz prism. The NATA directional emission is highly p polarized as expected for surface plasmon‐coupled radiation.The 10 nm protective SiO2 layer deposited on top of the aluminum film significantly neutralized the fluorophore quenching by the metal surface. SPCE of NATA demonstratees a remarkable intrinsic dispersive property–the maximum of the emission spectrum depends on the observation angle. The efficient spectral resolution of SPCE can be used in the construction of miniaturized spectrofluorometers. The observation of SPCE of tryptophan opens a new possibility for the study of many unlabeled proteins with the technique complementary to surface plasmon resonance analysis.
Structural Requirements for Efficient Cellular Photoprotection by Carotenoid Derivatives¶†
Authors: Kanofsky Jeffrey R. , Sima Paul D.
Published: July 2010

We have synthesized five carotenoid derivatives: (1) Girard's reagent P (GRP)‐retinal from GRP and retinal; (2) GRP‐carotenal from GRP and β‐apo‐8′‐carotenal; (3) Girard's reagent T (GRT)‐carotenal from GRT and β‐apo‐8′‐carotenal; (4) (GRP)2‐canthaxanthin from 2 mol of GRP and 1 mol of canthaxanthin; and (5) dansyl hydrazine (DH)‐carotenal from DH and β‐apo‐8′‐carotenal. The first three derivatives are cations, whereas the fourth is a dication and the fifth is a weak base. Using K562 cells, we compared the subcellular distribution of the synthetic carotenoid derivatives with two uncharged natural carotenoids, β‐carotene and β‐apo‐8′‐carotenal. The two natural carotenoids were present mainly within the cell membranes. The synthetic carotenoid derivatives were more broadly distributed among the cell organelles. The positively charged derivatives had relatively high concentrations in mitochondria, whereas DH‐carotenal had a relatively high concentration in lysosomes. We also measured the amount of photoprotection provided by the synthetic and natural carotenoids for K562 cells labeled with a photosensitizer (hypericin, protoporphyrin IX or cis‐di[4‐sulfonatophenyl]diphenylporphine). In this model system, only carotenoid derivatives with a permanent positive charge provided significant photoprotection. Neither the two natural carotenoids nor DH‐carotenal were effective photoprotectors.
Laboratory UV Exposure: Risk Assessment and Protective Measures¶
Authors: Cazzuli Orietta , Giroletti Elio
Published: July 2010

In research laboratories ultraviolet radiation is widely used, particularly in photochemistry and photobiology, as a sterilizing agent and for the characterization of samples. The results of a survey conducted near several university laboratories are presented with the aim of quantifying exposure levels to UV‐incoherent radiation and to assess individual risk for researchers and students. It has been shown that exposure is not negligible, especially if safety procedures are neglected and personal protective equipments, described in this study, are not used.
Effect of Carotenoids and Monogalactosyl Diglyceride on Bacteriochlorophyll c Aggregates in Aqueous Buffer: Implications for the Self‐assembly of Chlorosomes¶
Authors: Klinger Pavel , Arellano Juan B. , Vácha František , Hála Jan , PšenčíK Jakub
Published: July 2010

Aggregation of bacteriochlorophyll (BChl) c from chlorosomes, the main light‐harvesting complex of green bacteria, has been studied in aqueous buffer. Unlike other chlorophyll‐like molecules, BChl c is rather soluble in aqueous buffer, forming dimers. When BChl c is mixed with carotenoids (Car), the BChl c Qy transition is further redshifted, in respect to that of monomers and dimers. The results suggest that Car are incorporated in the aggregates and induce further aggregation of BChl c. The redshift of the BChl c Qy band is proportional to the Car concentration. In contrast, the mixture of bacteriochlorophyllide (BChlide) c, which lacks the nonpolar esterifying alcohol, does not form aggregates with Car in aqueous buffer or nonpolar solvents. Instead, the position of the BChlide c Qy transition remains unshifted in respect to that of the monomeric molecule, and Car precipitates with the course of time in aqueous buffer. Similar effects on both BChl c and BChlide c are also observed when monogalactosyl diglyceride (MGDG), which forms the monolayer envelope of chlorosomes, is used instead of (or together with) Car. The results show that the hydrophobic interactions of the BChl c esterifying alcohols with themselves and the nonpolar carbon skeleton of Car, or the fatty acid tails of MGDG, are essential driving forces for BChl aggregation in chlorosomes.
An Evaluation of Exogenous Application of Protoporphyrin IX and its Dimethyl Ester as a Photodynamic Diagnostic Agent in Poorly Differentiated Human Nasopharyngeal Carcinoma¶
Authors: Tammilmani Vanaja , Yee Karen kar Lye , Heng Paul Wan Sia , Soo Khee Chee , Ollvo Mallni
Published: July 2010

5‐Aminolevulinic acid and its esterified analogues have been under much investigation to enhance the endogenous production of protoporphyrin IX (PpIX) in tumor cells. However, in this work, we studied the in vitro and in vivo efficacy of exogenously administered PpIX and its esterified analogue, PpIX dimethyl ester (PME), in poorly differentiated human nasopharyngeal carcinoma (NPC/CNE‐2) as a photodynamic diagnostic (PDD) agent. NPC/CNE‐2 at its earliest time, 1 h after incubation with PME in in vitro studies, has exhibited 64% (P < 0.01) higher tumor to normal cell (T/N) fluorescence ratio than with PpIX. In an in vivo mouse xenograft model, comparable photosensitizer concentration in tumor after intravenous administration was observed at 1–3 h time points, but at 9 h, PME had 31% (P = 0.05) greater concentration in tumor compared with PpIX. In addition, by constituting PME and PpIX in different topical gel composites, of which, PME gel composition of 8:2 Plasdone® and Gantrez® resulted in the highest T/N ratio at 6 h after application (34%; P < 0.05) in comparison with other gel composites. Evaluation of PME and PpIX constituted in the delivery vehicles investigated showed comparable selectivity for tumor at 1–3 h, thus neither photosensitizer is more efficient than the other for PDD at the early time points; however, beyond 6 h, PME had higher selectivity for tumor compared with PpIX. Thus, further investigation is warranted to improve the drug delivery vehicle for greater tumor selectivity at a shorter incubation time.
Separation, Identification and Quantification of Riboflavin and its Photoproducts in Blood Products using High‐performance Liquid Chromatography with Fluorescence Detection: A Method to Support Pathogen Reduction Technology¶
Authors: Hardwick Christopher C. , Herivel Troy R. , Hernandez Shiloh C. , Ruane Patrick H. , Goodrich Raymond P.
Published: July 2010

A medical device using riboflavin (RB) and light is being developed for the reduction of pathogens in platelet concentrates (MIRASOLTM pathogen reduction technology [PRT]). A high‐performance liquid chromatography (HPLC) method for the quantification of RB and its main photoproduct, lumichrome (LC) in blood components has been developed and validated. In addition, the same method has been used to identify and quantify the presence of additional photoproducts‐catabolites of RB. Levels of these agents before and after treatment as well as endogenous levels present in normal donor blood are reported using this analytical technique. The method allows for quantitative and qualitative analysis of RB and LC in blood components using HPLC fluorescence detection, a Zorbax® SB‐CN (stable bond cyano) column and a methanol‐water mobile phase. Quantitation and qualitative analysis of additional photoproducts of RB was also performed, but the method has not been validated for these other components. The method described has passed an 8 day validation and has been found to be adequate for its intended use. The range of the method for RB is 0.016–1.500 μM and for LC is 0.060–1.500 μM. The method detection limit for RB is 0.0006 μM and for LC is 0.012 μM. The acceptance criteria for repeatability were met; the relative standard deviation for RB was 0.64% and for LC was 0.76%. The acceptance criteria for bias were met with a 97% average recovery for RB and a 102% recovery for LC. Samples were centrifuged and diluted 1:50 with 0.9% saline before analysis. No protein precipitation or extraction was required. A mass balance of approximately 93.4–94.4% was achieved after exposure of products to UV light in the intended pathogen reduction treatment method. The method permitted the identification of photoproducts in blood that were both naturally occurring and produced after photolysis of blood samples treated with the PRT process. The identity of these photoproducts has been established using HPLC Tandem Mass Spectrometry (MS/MS) and UV spectroscopic methods and has been correlated with known metabolites and catabolites of RB. HPLC with fluorescence detection using a reverse phase cyano‐column allows for accurate separation, identification and quantification of both RB and LC in blood products without the need for solvent extraction or protein precipitation. Additional photoproducts could also be identified and quantified using this method. The presence of these agents in normal, untreated blood suggests that their presence in blood is ubiquitous.
UV radiation effects on pathogens and insect pests of greenhouse‐grown crops
Authors: Raviv Michael , Antignus Yehezkel
Published: July 2010

Production of high‐value crops is often performed under protected cultivation. In recent years various spectral modifications have been made in greenhouse covers. Two of the main reasons to modify the spectral characteristics of greenhouse covers have been to suppress the proliferation of several foliar diseases and to protect crops from insects and insect‐borne virus diseases of greenhouse‐grown crops. These goals were achieved by complete or partial absorption of solar UV radiation, which interrupts the life cycle of several fungal pathogens and alters the visual behavior of many insects. Examples of these management strategies are described in this article.
Photophysical and photobiological behaviour of antimalarial drugs in aqueous solutions
Authors: Aloisi Gian Gaetano , Barbafina Arianna , Canton Marcella , Dall'Acqua Francesco , Elisei Fausto , Facciolo Laura , Latterini Loredana , Viola Giampietro
Published: July 2010

This article describes the results of a combined photophysical and photobiological study aimed at understanding the phototoxicity mechanism of the antimalarial drugs quinine (Q), quinacrine (QC) and mefloquine (MQ). Photophysical experiments were carried out in aqueous solutions by stationary and time‐resolved fluorimetry and by laser flash pbotolysis to obtain information on the various decay pathways of the excited states of the drugs and on transient species formed on irradiation. The results obtained showed that fluorescence and intersystem crossing account for all the adsorbed quanta for Q and MQ (quantum yield of about 0.1 and 0.9, respectively) and only for 24% in the case of QC, which has a negligible fluorescence quantum yield (0.001). Laser flash photolysis experiments evidenced, for QC and, MQ, the occurrence of photoionization processes leading to the formation of the radical cations of the drugs. The effects of tryptophan and histidine on the excited states and transient species of the three drugs were also investigated. In parallel, the photoactivity of the antimalarial drugs was investigated under UV irradiation on various biological targets through a series ofin vitroassays in the presence and in the absence of oxygen. Phototoxicity on 3T3 cultured fibroblasts and lipid photoperoxidation were observed for all the drugs. The photodamage produced by the drugs was also evaluated on proteins by measuring the photosensitized cross‐linking of spectrin. The combined approaches were proven to be usefulfor understanding the mechanism of phototoxicity induced by the antimalarial drugs.
Changes in matrix gene and protein expressions after single or repeated exposure to one minimal erythemal dose of solar‐simulated radiation in human skin in vivo
Authors: Seité Sophie , Colige Alain , Deroanne Christophe , Lambert Charles , Piquemal‐Vivenot Pascale , Montastier Christiane , Fourtanier Anny , Lapière Charles , Nusgens Betty
Published: July 2010

ASTRACT

Damage to the skin extracellular matrix (ECM) is the hallmark of long‐term exposure to solar UV radiation. The aim of our study was to investigate the changes induced in unexposed human skin in vivo after single or repeated (five times a week for 6 weeks) exposure to 1 minimal erythemal dose (MED) of UV solar‐simulated rediation. Morphological and iochemical analyses were used to evaluate the stuctural ECM components and the balance between teh degrading enzymes the their physiologic inhibitors. a three‐fold increse in matrix metalloproteinase 2 messenger RNA (mRNA) (P < 0.02, unexposed versus exposed) was observed after both single and repeated exposures. Fibrillin 1 mRNA level was incresed by chronic exposure (P <0.02) and unaltered y a single MED. On the cotrary, a single MED singnificantly enhanced mRNA levels of interleukin‐1α (1L‐1α), IL‐1β (P < 0.02) and plasminogen activator inhibitor‐1 (P < 0.05). Immkunohistochemistry demonstrated a singnificant decrese in Type‐I procollagen localized just below the dermal‐epidermal junction in both types of expozed sites. at the same location, teh immunodetected tenascin was singnificantly enhanced, whereas a slight increase in Type‐III procollagen deposits was also unale to observe any change in elastic iers in chronically exposed uttock skin, a significant increase in lysozyme and alpha‐1 antitrypsin deposits on these fibers was oserved. These results demonstrate the existence of diffenentaia regulation, after chronic exposure compared with an acute one, of some ECM components and inflammatory mediators.
Interexperimental and interindividual variations of DNA repair capacities after UV‐B and UV‐C irradiations of human keratinocytes and fibroblasts
Authors: Chazal Marjorie , Roux Emeric , Alapetite Claire , Roulin Christophe , Moustacchi Ethel , Douki Thierry , Baudouin Caroline , Charveron Marie , Basset‐Séguin Nicole
Published: July 2010

Abstract DNA repair plays a central role in the cellular response to UV. In this work we have studied the response of skin cells (i.e. fibroblasts and keratinocytes) from the same or from different individuals after both ultraviolet‐B (UV‐B) and ultraviolet‐C (UV‐C) irradiations using the comet assay to characterize the specific cellular response to UV‐induced DNA damage. Cells were irradiated with increasing doses of UV‐B or UV‐C. To study the UV dose dependency of initial steps of DNA repair, namely recognition and incision at DNA damage level, the comet assay was performed, under alkaline conditions, 60 min after UV irradiation to allow detection of DNA strand breaks. Comparative analysis of tail moment values after UV exposure of cells from the same or from different individuals showed interexperimental and interindividual variations, implying that repeated assays are necessary to characterize the individual DNA repair capacity. With increasing doses of UV in keratinocytes, a plateau was rapidly reached after irradiation, whereas in fibroblasts a linear dose‐effect relationship was observed. These interindividual variations associated with cellular specificity in DNA response may be of significance in skin cell and individual susceptibility toward UV‐induced carcinogenesis.
Matrix Metalloproteinase‐1 Production Observed After Solar‐Simulated Radiation Exposure is Assumed by Dermal Fibroblasts but Involves a Paracrine Activation Through Epidermal Keratinocytes¶
Authors: Fagot Dominique , Asselineau Daniel , Bernerd Françoise
Published: July 2010

Chronic exposure of human skin to solar UV radiation leads to serious dermal damages, a hallmark of photoaging. In vivo, acute UV radiation has been shown previously to induce various matrix‐degrading proteases. Among them, matrix metalloproteinase‐1 (MMP‐1) has been suggested to be involved in skin photodamage. The purpose of this study was to investigate the effects of solar‐simulated radiation (SSR) on MMP‐1 production in normal human skin cells. SSR exposure of human skin reconstructed in vitro comprising both a differentiated epidermis and a fibroblast‐populated dermal equivalent led to an increase in MMP‐1 production, which was abolished when epidermis was removed immediately after SSR exposure. In addition, SSR exposure of differentiated keratinocytes grown on an acellular collagen gel did not induce MMP‐1 production. Experiments on cell cultures grown on plastic confirmed that keratinocytes failed, in contrast with fibroblasts, to produce MMP‐1 in response to SSR exposure. However, when conditioned medium from SSR‐exposed keratinocytes was added to human fibroblasts in culture, MMP‐1 production was induced. Altogether, these data show that MMP‐1 production observed after SSR exposure involved the release of soluble epidermal factors, which could modulate its production by dermal fibroblasts.
Photovoltaic Effects in Hornets Are Correlated with the Time of Day¶
Authors: Sverdlov Anna , Ishay Jacob S.
Published: July 2010

This study deals with voltage values recorded off the cuticle of live specimens of the Oriental hornet Vespa orientalis (Hymenoptera, Vespidae). The relevant measurements were taken between the two tip of their bodies at various hours of the day and were made on a total of 90 worker hornets. Recorded voltage values varied within a range of 60‐180 mV, with the lower values measured during the morning hours and the afternoon and the highest values during the noon hours. Measurements were made by direct contact of the electrodes with the hornet cuticle and did not prove lethal to the measured specimens. An additional 60 live hornets were measured in the same fashion but in the dark. The values recorded in the dark varied between 40 and 70 mV and displayed considerable fluctuations but were not found to be dependent on the time of measurement. The distribution of the voltage values in hornets measured at various hours in the daytime closely resembled that of the global radiations (in W/m2) on the same days the measurements were taken.
A Monochromatic Action Spectrum for the Photoinduction of the UV‐Absorbing Mycosporine‐like Amino Acid Shinorine in the Red Alga chondrus crispus¶
Authors: Kräbs Gudrun , Watanabe Masakatsu , Wlencke Christian
Published: July 2010

To determine the action spectrum for photoinduction of the ultraviolet (UV)‐absorbing mycosporine‐like amino acid shinorine, specimens of the marine red alga Chondrus crispus were irradiated with monochromatic light of various wavelengths using the Okazaki large spectrograph at the National Institute for Basic Biology, Okazaki, Japan. Fluence response curves were determined for the wavelengths between 280 and 750 nm, by irradiating the algae with monochromatic light for 10 h, followed by 4 h of 25 μmol m−2 s−1 photosynthetically active radiation and 10 h darkness. Samples were taken after the second exposure interval. A linear correlation between fluence rate and accumulated shinorine concentration was detected for wavelengths between 350 and 490 nm in the fluence rate range of 20–30 μmol m−2 s−1, whereas there was no induction above 490 nm. Below 350 nm a decline in shinorine concentration could be observed at fluence rates above 30 μmol m−2 s−1, probably due to an inhibition of photosynthetic activity and a subsequent impairment of shinorine biosynthesis. The constructed action spectrum indicated that the photoreceptors mediating shinorine photoinduction might be an unidentified UV‐A‐type photoreceptor with absorption peaks at 320, 340 and 400 nm.