bluuebunny/crossref_metadata_2025 huggingface dataset:
PHOTOACI'IVATED GILVOCARCIN V INDUCES DNA‐PROTEIN CROSSLINKING IN GENES FOR HUMAN RIBOSOMAL RNA AND DIHYDROFOLATE REDUCTASE
Authors: Matsumoto Akira , Fujiwara Yoshisada , Elespuru Rosalie K. , Hanawalt Philip C.
Published: January 2008

Abstract The nature of DNA interactions with photoactivated gilvocarcin V has been analyzed at the gene level in both rRNA and dihydrofolate reductase genes of human fibroblasts, utilizing a modified Southern hybridization technique. Neither interstrand DNA crosslinking nor RNA linkage to DNA was detected. However, we consistently observed in both genes retarded DNA bands appearing in a dose‐dependent fashion following exposure to photoactivated gilvocarcin V. These retarded bands were enhanced when genomic DNA was prepared without proteinase K treatment, suggesting involvement of protein in this DNA interaction. Because these bands disappear following proteinase K treatment, it is probable that photoactivated gilvocarcin V induces DNA‐protein crosslinking.
LACK OF CORRELATION BETWEEN SUPPRESSION OF CONTACT HYPERSENSITIVITY BY UV RADIATION AND PHOTOISOMERIZATION OF EPIDERMAL UROCANIC ACID IN THE HAIRLESS MOUSE
Authors: Reeve Vivienne E. , Boehm‐Wilcox Christa , Bosnic Meira , Cope Ranald , Ley Ronald D.
Published: January 2008

Abstract The immunological consequences of exposure to UVA (320–400 nm) radiation are unclear. This study describes the relationship between the generation of epidermal cis‐urocanic acid and the ability to respond to a contact‐sensitizing agent, in hairless mice exposed to different UV radiation sources, which incorporate successively greater short‐wavelength cutoff by filtration of the radiation from fluorescent UV tubes. Mice were exposed to these radiation sources at doses systematically varying in UVB radiation content but supplying increasing proportions of UVA radiation. All radiation sources were found to generate approximately 35%cis‐urocanic acid in the epidermis, thus normalizing the sources for cis‐urocanic acid production. However, only those sources richest in short‐wavelength UVB resulted in suppression of the systemic contact hypersensitivity response. These sources also induced the greatest erythema reaction, measured as its edema component, in the exposed skin. A strong correlation was thus demonstrated between the induction of edema and the suppression of contact hypersensitivity, but there appeared to be no correlation between the generation of epidermal cis‐urocanic acid and suppression of contact hypersensitivity. The sources richest in UVA content did not result in suppression of contact hypersensitivity: furthermore mice previously irradiated with such UVA‐rich sources were refractory to the immunosuppressive action of exogenous cis‐urocanic acid. A protective effect of the increased UVA content thus appeared to be inhibiting immunosuppression by the available endogenously generated or exogenously applied cis‐urocanic acid.
PERSONAL DOSIMETRY OF SOLAR UV RADIATION FOR DIFFERENT OUTDOOR ACTIVITIES
Authors: Herlihy Ellen , Gies Peter H. , Roy Colin R. , Jones Michael
Published: January 2008

Abstract Quantifying individual exposure to ultraviolet radiation (UVR) is critical to understanding the etiology of a number of diseases including nonmelanotic and melanotic skin cancers. Measurements of personal exposure to solar UVR were made in Hobart, Tasmania in February (summer) 1991 for six different outdoor activities using UVR‐sensitive polysulfone (PS) film attached at seven anatomical sites. Concurrent behavioral and environmental observations were also made. To date many studies have relied on subject recall to quantify past solar UVR exposures. To gain insight into the accuracy of subject recall the measured UVR exposures received by different subjects using the PS film were compared to those calculated from personal diaries and ambient solar UVB levels from a monitoring station. In general, when UVR exposure activities took place under close supervision, good correlations were obtained between the PS badges and the ambient measurements/diaries approach. Ultraviolet radiation exposures for the field study involving 94 subjects engaged in a number of outdoor activities are presented.
FEMTOSECOND STUDIES OF HEMATOPORPHYRIN DERIVATIVE IN SOLUTION: EFFECT OF pH AND SOLVENT ON THE EXCITED STATE DYNAMICS
Authors: Zhang J. Z. , O'Neil R. H. , Evans J. E.
Published: January 2008

AbstractWe report direct femtosecond measurements of the excited state dynamics of hematoporphyrin derivative (HpD) in solution. The dynamics are found to be very sensitive to the solvent and pH of aqueous solutions. The decay of the excited singlet states is much faster in acidic and pH 7 buffer aqueous solutions (<230 ps) than in basic aqueous solutions or organic solvents (> 10 ns). The dynamical results show strong correlation with static fluorescence measurements: weaker fluorescence in acidic and pH 7 buffer solutions corresponding to shorter‐lived excited states. A new fast decay component with a time constant around 5 ps is identified both in acidic aqueous solutions and in organic solvents such as acetone and attributed to internal conversion from the second to the first excited singlet state of aggregates or certain oligomers in HpD, in accord with the observation that the fast decay component is larger at a higher concentration. Oxygen is found to have no effect on the dynamics on the time scale investigated, 1 ns, indicating that oxygen quenching of the singlet excited states is insignificant on this time scale. The sensitive solvent and pH dependence of the excited state dynamics has important clinical implications in the use of HpD as a photosensitizing agent.
HEMATOPORPHYRIN DERIVATIVE (PHOTOFRIN®) PHOTODYNAMIC ACTION ON Ca2+TRANSPORT IN MONKEY KIDNEY CELLS (CV‐1)
Authors: Dellinger Marc , Ricchelli Fernanda , Moreno Giuliana , Salet Christian
Published: January 2008

AbstractAfter 24 h incubation with Photofrinm®(PF), photodynamic action has been studied on Ca2+transport in CV‐1 cells. A moderate increase of the cytosolic free Ca2+concentration [Ca2+] is observed immediately after a dose of irradiation which yields a survival rate of less than 5% at 48 h. In parallel, studies on digitonin‐permeabilized cells indicate that such a treatment inhibits endoplasmic reticulum Ca2+uptake with few alterations of this process in mitochondria. In contrast, ADP‐stimulated respiration is impeded and intracellular ATP level decreases. It is suggested that direct damage to endoplasmic reticulum as well as mitochondrial disturbance are the primary mechanisms responsible for a nontransient elevation of [Ca2+]i preceding cell death.
SHAPE OF THE CHROMOPHOIW BINDING SITE IN pharaonis PHOBORHODOPSIN FROM A STUDY USING RETINAL ANALOGS
Authors: Hirayama Junichi , Imamoto Yasushi , Shichida Yoshinori , Yoshizawa Tǒru , Asato Alfred E. , Liu Robert S. H. , Kamo Naoki
Published: January 2008

Abstract To investigate the shape of the chromophore binding site of pharaonis phoborhodopsin (ppR), ppR‐opsin was incubated with five ring‐modified retinal analogs: an acyclic retinal, phenylretinal, α‐retinal, cyclohexylretinal and 5‐isopropyl‐α‐retinal. The experimental results were compared with those obtained from bacteriorhodopsin‐opsin (bR‐opsin) and the same retinal analogs. It was suggested that ring chain conformation is important in affecting the spectral shoulder unique for the absorption spectrum of ppR. The rate of pigment formation depended greatly on the analogs used with the planar analogs showing rapid formation. Thus, we concluded that the space of the retinal binding site of ppR is restricted to the plane of the cyclohexenyl ring of the chromophore, whereas that of bR is less restricted.
ENHANCED MACROPHAGE CYTOTOXICITY AGAINST TUMOR CELLS TREATED WITH PHOTODYNAMIC THERAPY
Authors: Korbelik Mladen , Krosl Gorazd
Published: January 2008

Abstract In vitro treatment of human lung adenocarcinoma cells A549 with photofrin‐based photodynamic therapy (PDT) resulted in the potentiation of macrophage‐mediated killing of these cells assayed either by measuring 3H‐thymidine release from the prelabeled target cells, or by determining the survival of A549 cells based on colony formation. The effector cells in these experiments were human promyelocytic leukemia cells HL60 induced to differentiate into macrophages. Very similar results were obtained with the murine squamous carcinoma SCCVII cells treated with PDT and subsequently admixed with mouse peritoneal macrophages. This effect increased with PDT dose and reached its maximum (i.e. complete or nearly complete release of the radioactive label) with the photodynamic treatment that was lethal to 40–50% of cells. In contrast, the PDT treatment of normal mouse kidney cells resulted in only a very limited enhancement of their cytolysis by mouse peritoneal macrophages. The exposure of A549 cells to X‐ray irradiation had not affected the macrophage‐mediated killing of these cells. The PDT survival curves of A549 cells cultured either alone or with the effector cells showed that the presence of macrophages even at very low effector: target cells ratios enhanced the PDT response of tumor cells. The enhancement ratio of 3.6 (at S = 0.01) was achieved with the effector: target cell ratio 2.5:1, which was the highest ratio tested with this assay. It is suggested that macrophages may recognize potentially repairable damage induced by PDT in tumor cells (presumably lipid fragments exposed in damaged cellular membranes), which helps them to identify the affected cells as their targets.
BATHOCHROMICITY OF RETINAL SCHIFF BASES IN CELLULOSE MATRIX
Authors: Singh Anil K. , Majumdar Nirmalya
Published: January 2008

AbstractSchiff bases ofall‐trans‐retinal(formed with n‐butylamine, tryptamine and β‐naphthylamine) and of benzaldehyde,trans‐cinnamaldehyde and all‐trans‐retinal with aniline exhibit an appreciable red shift in their UV‐visible maxima on intercalation in cellulose matrix relative to their absorption in solution in the absence of acid. Treatment of these model compounds with trichloroacetic acid in solution gives the corresponding protonated salts. The red shift due to the cellulose environment is, however, less than the red shift in acid solutions. However, an exception is all‐trans‐N‐retinylidenetryptamine for which the red shift in cellulose is quite close to the corresponding value for the protonated salt in heptane and methanol.N‐Benzalideneaniline and trans‐N‐cinnamalideneaniline, with shorter polyenic moieties, tend to show a greater bathochromic shift in cellulose. all‐trans‐N‐Retinylidene‐n‐butylamine, all‐trans‐N‐retinylidenetryptamine and all‐trans‐N‐retinylidene‐β‐naphthylamine show a reduced bathochromic shift when intercalated in cellulose pretreated with a base such asn‐butylamine. The chromophore of all‐trans‐N‐retinylidenetryptamine is stabilized by the presence of the indole moiety. These results indicate the importance of hydrogen‐bond interactions at the chromophore sites of rhodopsins. A mechanistic proposal for explaining protonation, stability and wavelength regulation in the opsin family of proteins is discussed.
PREPARATION AND PHOTOPHYSICAL STUDIES OF PORPHYRIN‐C60 DYADS
Authors: Liddell Paul A. , Sumida John P. , Macpherson Alisdair N. , Noss Lori , Seely Gilbert R. , Clark Kristine N. , Moore Ana L. , Moore Thomas A. , Gust Devens
Published: January 2008

Abstract Porphyrin‐C60 dyads in which the two chromophores are linked by a bicyclic bridge have been synthesized using the Diels‐Alder reaction. The porphyin singlet lifetimes of both the zinc (Pzn‐C60) and free base (P‐C60) dyads, determined by time‐resolved fluorescence measurements, are ≦17 ps in toluene. This substantial quenching is due to singlet‐singlet energy transfer to C60 The lifetime of Pzn‐1C60 is ‐5 ps in toluene, whereas the singlet lifetime of an appropriate C60 model compound is 1.2 ns. This quenching is attributed to electron transfer to yield Pznbull;+‐C60bull;‐. In toluene, P‐1C60 is unquenched; the lack of electron transfer is due to unfavorable thermodynamics. In this solvent, a transient state with an absorption maximum at 700 ran and a lifetime of‐10 μs was detected using transient absorption methods. This state was quenched by oxygen, and is assigned to the C60 triplet. In the more polar benzonitrile, P‐1C60 underoes photoinduced electron transfer to give P•+‐C60bull;‐. The electron transfer rate constant is −2 × 1011 s−1.
SYNTHESIS AND PHOTOCHEMICAL PROPERTIES OF NITROTHIENYL DERIVATIVES
Authors: Dauria Maurizio , Mauriello Giacomo
Published: January 2008

AbstractSome 2‐nitrothienyl derivatives characterized by the presence of an aryl or heteroaryl substituent in the C‐5 position were synthesized by using a photochemical coupling procedure. All synthesized compounds were demonstrated to be singlet oxygen sensitizers in the trans‐α,α'‐dimethylstilbene photooxidation.
A PHOTOCHEMICAL TECHNIQUE TO ENHANCE SENSITIVITY OF DETECTION OF FLUORESCENCE RESONANCE ENERGY TRANSFER
Authors: Mekler Vladimir M.
Published: January 2008

Abstract –A photochemical kinetic method of measuring small values of efficiency of fluorescence resonance energy transfer (FRET) between special probes is proposed. The FRET efficiency (Ω) is determined from kinetics of the photochemical reaction of the energy acceptor sensitized by FRET from the energy donor. The choice of an appropriate donor‐acceptor pair permits the minimization of background reactions. Application of the method is demonstrated by the detection of FRET from 2,5‐W.s(5‐tert‐butyl‐2‐benzoxasolyl)thiophen (BBOT) to acridine orange (AO) in phospholipid vesicles. Photobleaching of AO in the presence of CBr4 was applied as a photochemical reaction of the acceptor. The reaction was monitored by steady‐state fluorescence measurements. The FRET measurements were carried out by the proposed technique when the probe/lipid ratio and Ω were as small as 1.1 times 10‐5M/Mand 0.0017, respectively. Under these conditions, the rate constant of AO photobleaching was increased by 26% as compared with that of the reference sample without BBOT. The results suggest that applications of the technique may be useful in the study of the membrane topography.
THIOPYRONINE‐ AND 8‐METHOXYPSORALEN‐SENSITIZED PHOTODYNAMIC EFFECT ON CELL GROWTH, COLONY FORMING ABILITY and RNA SYNTHESIS IN Saccharomyces MUTANTS DEFICIENT IN DNA REPAIR
Authors: Roth Robert M. , Takamori Yasuhiko , Lochmann Ernst‐Randolf
Published: January 2008

Abstract –We compared the photodynamic effects of thiopyronine (TP) and visible light, and 8‐methoxypsoralen (8‐MOP) and ultraviolet A (UV‐A) light, on growth, colony forming ability and RNA synthesis in a repair‐proficient Saccharomyces strain and three mutants deficient in DNA repair mechanisms (DNA repair assays). With 8‐MOP and UV‐A repair‐deficient mutants were significantly more sensitive than the repair‐proficient strain indicating that the system is sensitive for the detection of DNA damage. With TP and visible light, the photodynamic effects were comparable in the mutants and the control, indicating no DNA damage. These results support previous work showing that the main target of TP photosensitization in eukaryotes is not nuclear DNA.
ACOUSTIC DETECTION OF TRIPLET STATES FORMED BY RADICAL PAIR RECOMBINATION IN QUINONE‐DEPLETED PHOTOSYNTHETIC REACTION CENTERS, BY MAGNETIC FIELD MODULATION (MAGNETOPHOTOACOUSTIC EFFECT)‐A FEASIBILITY STUDY
Authors: Malkin Shmuel , Hoff Arnold J.
Published: January 2008

Abstract –An acoustic method is outlined to detect triplet states formed by radical pair recombination in photosyn‐thetic reaction centers. It is based on magnetic field effect on the probability of triplet state formation by recombination. Using a periodically modulated magnetic field in the presence of constant exciting light, a periodic modulation of the triplet state concentration is set in the sample, which is detected through the corresponding modulated heat emission, transduced to acoustic vibration of the gas phase around the sample. This effect is similar to the photoacoustic effect, except that here the light is not modulated. The feasibility of detecting such an effect was proven experimentally, by obtaining a signal from quinone‐depleted reaction centers of Rhodobacter sphaeroides. The signal had twice the frequency of the magnetic field modulation; it was proportional to the light intensity and significantly stronger at the lower temperatures (in the investigated range 113–278 K). No signal was obtained from quinone‐containing reaction centers, which do not produce triplets. A theoretical outline of the effect and the experimental set‐up are described. The “magnitude of the effect was calibrated against ordinary photoacoustic measurements, allowing numerical evaluation of certain parameters of the triplet state (e.g. triplet energy or yield) with the aid of auxiliary information from the literature.
(1‐PYRENYL)METHYL CARBAMATES FOR FLUORESCENT “CAGED” AMINO ACIDS AND PEPTIDES
Authors: Okada Shigeto , Yamashita Senichi , Furuta Toshiaki , Iwamura Michiko
Published: January 2008

A highly fluorescent 1‐pyrenylmethyloxycarbonyl amino acid (Pmoc‐amino acid) is obtained in moderate yield by the reaction of (1‐pyrenylmethyl)‐4‐nitrophenylcarbonate with an amino acid in the presence of sodium carbonate. The condensation of Pmoc‐amino acid with an amino acid gives Pmoc‐peptide in the presence of 1‐ethyl‐3‐(3‐dimethylaminepropyl)carbodiimide and 1‐hydroxyben‐zotriazole. The amino acid is recovered from an H2O‐dioxane (2:3) solution of Pmoc‐amino acid by irradiation through a Pyrex filter with a medium pressure Hg lamp or at 340 nm. Although the quantum yield of the photolysis is rather low (ca 0.01), the photolysis proceeds fast and efficiently due to the large absorption coefficient of Pmoc‐amino acid at around 340 nm. Thus, the use of Pmoc‐amino acid as a “caged” amino acid is promising.
THE INFLUENCE OF MOLECULAR CONFORMATION ON THE STABILITY OF ULTRAVIOLET STABILIZERS TOWARD DIRECT AND DYE‐SENSITIZED PHOTOIRRADIATION: THE CASE OF 2‐(2'‐HYDROXY‐5'‐METHYPHENYL)BENZOTRIAZOLE (TIN P)
Authors: Catalán Javier , Valle Juan C. Del , Fabero Fernando , Garcia Norman A.
Published: January 2008

Abstract— The mechanism for photodegradation of the ultraviolet photostabilizer 2‐(2'‐hydroxy‐5'‐methylphenyl)benzotriazole (TIN P) upon direct and dye‐sensitized (singlet molecular oxygen [O2(1Δg)]‐mediated) irradiation was studied. From the experimental TIN P photodegradation rate data, and low temperature (77 K) fluorescence and phosphorescence quantum yields, one can conclude that the photodegradative process involves phosphorescent states of TIN P. The open conformer of TIN P quenches O2(1Δg) by physical scavenging with a rate constant (kq) in dimethylsulfoxide of 2.8 times 106M‐1 s‐1. The intramolecular hydrogen‐bonded conformer does not appreciably interact with O2(1Δg). In the presence of a relatively high concentration of OH‐ (either 5 times 10‐2M KOH in ethanol or water at pH 13), the ionic form of TIN P (with an ionized phenol group) physically and chemically quenches O2(1Δg). The reaction rate constant (kr) is 1 times 108M‐1 s‐1, and the ratio kq/kr is approximately three in alkaline aqueous media.
THE EFFECT OF IRRADIANCE ON VIRUS STERILIZATION AND PHOTODYNAMIC DAMAGE IN RED BLOOD CELLS SENSITIZED BY PHTHALOCYANINES
Authors: Ben‐Hur E. , Geacintov N. E. , Studamire B. , Kenney M. E. , Horowitz B.
Published: January 2008

Abstract— Phthalocyanines are being studied as photosensitizers for virus sterilization of red blood cells (RBC). During optimization of the reaction conditions, we observed a marked effect of the irradiance on production of RBC damage. Using a broad‐band light source (600–700 nm) between 5 and 80 mW/ cm2, there was an inverse relationship between irradiance and rate of photohemolysis. This effect was observed with aluminum sulfonated phthalocyanine (AlPcSn) and cationic silicon (HOSiPc‐OSi[CH3]2 [CH2]3N+[CH3]3I‐ phthalocyanine (Pc5) photosensitizers. The same effect occurred when the reduction of RBC negative surface charges was used as an endpoint. Under the same treatment conditions, vesicular stomatitis virus inactivation rate was unaffected by changes in the irradiance. Reduction in oxygen availability for the photochemical reaction at high irradiance could explain the effect. However, theoretical estimates suggest that oxygen depletion is minimal under our conditions. In addition, because the rate of photohemolysis at 80 mW/cm2 was not increased when irradiations were carried out under an oxygen atmosphere this seems unlikely. Likewise, formation of singlet oxygen dimoles at high irradiances does not appear to be involved because the effect was unchanged when light exposure was in D2O. While there is no ready explanation for this irradiance effect, it could be used to increase the safety margin of RBC virucidal treatment by employing exposure at high irradiance, thus minimizing the damage to RBC.
ACTION SPECTRUM FOR ERYTHEMA IN HUMANS INVESTIGATED WITH DYE LASERS
Authors: Anders Angelika , Altheide Hans‐Jürgen , Knälmann Marita , Tronnier Hagen
Published: January 2008

Abstract— Erythema reactions of human skin were reevaluated with improved experimental methods: a tunable, highly monochromatic irradiation source as well as an instrumental measurement of skin reactions were used. The irradiation system consisted of an excimer laser pumped dye laser and a U V fiber optic system. The skin color after irradiation was determined with a colorimeter in the three‐dimensional norm system of the Commission Internationale d'Eclairage (CIE). The wavelength dependence for delayed erythema was investigated in the UVB and UVA region from 294 nm to 374 nm in skin type II and III individuals. The maximum of the action spectrum in the UVB range was measured at 298.5 nm and an additional maximum was found at 362 nm in the UVA range. The action spectrum is compared with previous spectra from the literature and with the current standard erythema curve of the CIE as well as with other photobiological action spectra. Our results suggest a UVA/UVB boundary at 330 nm.
In vivo SPECTROPHOTOMETRIC EVALUATION OF NEOPLASTIC AND NONNEOPLASTIC SKIN PIGMENTED LESIONS. III. CCD CAMERA‐BASED REFLECTANCE IMAGING
Authors: Marchesini R. , Tomatis S. , Bartoli C. , Bono A. , Clemente C. , Cupeta C. , Prato I. Del , Pignoli E. , Sichirollo A. E. , Cascinelli N.
Published: January 2008

Abstract— Reflectance spectroscopy, which allows an objective evaluation of the color of surfaces, has recently been proposed as a useful tool to discriminate cutaneous melanoma from other pigmented cutaneous lesions. A novel spectrophotometric system based on the use of a charge coupled device camera provided with a set of interference filters has been developed to acquire images of cutaneous pigmented lesions at selected wavelengths ranging from 420 to 1040 nm. For each filter, an image was captured, digitized by a frame grabber and stored in a personal computer to perform off‐line data handling. Reflectance images were acquired of 22 cutaneous pigmented lesions including melanoma and dysplastic, compound and junctional nevus. From each spectral image, three parameters, i.e. mean reflectance, variegation index and lesion area, were derived at the corresponding wavelength. The wavelength dependence of the three parameters was significantly different when melanoma was compared to the other investigated lesions. Although preliminary, our results suggest that telespectrophotometry gives useful information and could be utilized as an aid in the clinical diagnosis of cutaneous pigmented lesions.
CHLOROPHYLLS IN POLYMERS. I. STATE OF CHLOROPHYLL a IN UNSTRETCHED POLYMER SYSTEMS
Authors: Zandvoort M. A. M. J. van , Wróbel D. , Lettinga P. , Ginkel G. van , Levine Y. K.
Published: January 2008

Abstract—Model systems for the study of energy transfer processes are useful for the elucidation of the various factors governing the mechanism of energy transfer in photosynthetic systems. Here we describe the characterization of two systems, consisting of chlorophyllaincorporated in anhydrous nitrocellulose and polyvinylalcohol films. First, optical spectroscopy and time‐resolved fluorescence techniques are used to characterize the state of the chlorophyll molecules in the films. We find that in nitrocellulose films the state of chlorophylladepends strongly on the ratio of nitrocellulose to dimeth‐ylsulfoxide in the solutions from which the films are cast. The state of chlorophyllain polyvinylalcohol films does not depend on the amount of polymer originally dissolved in dimethylsulfoxide. In these films the pigment is monomeric at low concentrations of chlorophylla,but aggregates are formed at much lower concentrations than in nitrocellulose. The latter fact is explained by the existence of pockets in polyvinylalcohol, leading to high local concentrations.

To further test the suitability of the nitrocellulose polymer films as model systems for energy transfer processes, time‐resolved fluorescence anisotropy profiles are measured in dependence of the concentration of pigments in the matrix. Fits of the observed decay profiles to the predicted decay show good correspondence, as long as no traps are present. Furthermore, the fitted decay times yield the correct value of the Forster radius R0as compared to the value obtained spectroscopically. We thus conclude that the chlorophyll a‐nitrocellulose system can be very appropriate for the study of energy transfer processes between photosynthetic pigment, since the pigments are uniformally distributed in the matrix.
CLONING, EXPRESSION and SEQUENCE ANALYSIS OF cDNA FOR THE LUCIFERASES FROM THE JAPANESE FIREFLIES, Pyrocoelia tniyako AND Hotaria parvula
Authors: Ohmiya Yoshihiro , Ohba Nobuyoshi , Toh Hiroyuki , Tsuji Frederick I.
Published: January 2008

Abstract—Cloning and sequence analysis of cDNA for the luciferases ofPyrocoelia miyakoandHotaria parvulawere carried out (GenBank accession numbers L39928 and L39929, respectively). The amino acid sequence, deduced from the nucleotide sequence, showedP. miyakoluciferase to consist of 548 amino acid residues with a molecular weight of 60955, while the luciferase ofH. parvulaconsisted of 548 amino acid residues with a molecular weight of 60 364.Pyrocoelia miyakoluciferase showed 82.1 % homology with the luciferase ofPhotinus pyralisand less than 70% homology with other firefly luciferases, whereasH. parvulaluciferase showed 98%, 82.5% and 81.2% homology with the luciferases ofLuciola mingrelica, Luciola lateralisandLuciola cruciata,respectively. Two regions in the enzymes were found to be highly conserved. The amino acid sequences were used to construct a phylogenetic tree, which showed that the fireflies could be divided into two groups.
STRUCTURE‐ACTIVITY RELATIONSHIP OF PORPHINES FOR PHOTOINACTIVATION OF BACTERIA
Authors: Nitzan Y. , Dror R. , Ladan H. , Malik Z. , Kimel S. , Gottfried V.
Published: January 2008

Abstract— The antibacterial photodynamic effects of uncharged (o‐tetrahydroxyphenyl porphine [THPP], m‐THPP and p‐THPP), cationic (5,10,15,20‐tetra[4‐N‐methylpyridyllporphine [TMPyP]) and anionic (5,10,15,20‐tetra[4‐sulfonatophenyl porphine] [TPPS4]) porphines on Staphylococcus aureus and Escherichia coli bacteria inactivation were examined. The results show that uncharged porphines provoked antibacterial photodynamic activity on S. aureus, and also on E. coli in the presence of the membrane‐disorganizing peptide polymixin B nonapeptide (PMNP). The TMPyP compound was highly photoactive toward gram‐positive bacteria but only marginally effective on gram‐negative cells, whereas TPPS4 showed no activity on either gram‐positive or gram‐negative bacteria. The photoactivity of TMPyP is due to the electrostatic attraction between the positively charged sensitizer molecule and the negatively charged membrane of the gram‐positive target cells. For TPPS4, the inactivity toward gram‐positive bacteria is due to electrostatic repulsion between the charged sensitizer molecule and the cell membrane. For gram‐negative bacteria, the inactivity is conceivably due to preferential (electrostatic) binding to the positively charged PMNP, which is an adjuvant for membrane disorganization, but has no effect on cell viability. For hydrophobic sensitizers, the photoactivity depends on the state of aggregation. The extent of deaggregation of the different THPP isomers was determined by fluorescence measurements of bound sensitizers and could be positively correlated with their photoinactivation capacity. We conclude that the structure‐activity relationships of these porphines are affected by their net charge and by aggregation.
QUANTITATIVE ASSESSMENT OF CUMULATIVE DAMAGE FROM REPETITIVE EXPOSURES TO SUBERYTHEMOGENIC DOSES OF UVA IN HUMAN SKIN
Authors: Lavker R. M. , Veres D. A. , Irwin C. J. , KAIDBEY K. H.
Published: January 2008

Abstract— Daily exposures to relatively small suberythemogenic fluences of UVA (50–200 kj/m2) for 8 days resulted in cumulative morphological skin alterations indicative of early tissue injury. Histologically, irradiated skin revealed epidermal hyperplasia, inflammation and deposition of lysozyme along the dermal elastic fiber network. Sunburn cells were also present within the epidermis. These changes were quantified by image analysis and were found to be related to the cumulative UVA fluence. A long UVA waveband (UVAI, 340–400 nm) was as effective as a broad UVA band (320–400 nm), suggesting that these changes are induced by longer UVA wavelengths.
FLUORESCENCE OF TYROSINE AND TRYPTOPHAN IN PROTEINS USING ONE‐ AND TWO‐PHOTON EXCITATION
Authors: Kierdaszuk Borys , Gryczynski Ignacy , Modrak‐Wojcik Anna , Bzowska Agnieszka , Shugar David , Lakowicz Joseph R.
Published: January 2008

Abstract— We examined the emission spectra of tyrosine‐ and tryptophan‐containing proteins using one‐photon (270–310 nm) and two‐photon (565–610 nm) excitation. Emission spectra for two‐photon excitation of native and denatured human serum albumin and of three purine nucleoside phosphorylases indicated an absence of the tyrosine emission normally seen for one‐photon excitation below 290 nm. We examined the one‐photon and two‐photon excitation spectra of tyrosine‐tryptophan mixtures to determine the origin of selective excitation of the tryptophan residues. These results confirmed a short‐wavelength shift of the tyrosine two‐photon excitation spectrum relative to that of tryptophan, as recently reported by Rehms and Callis (1993) Chem. Phys. Lett. 208, 276–282.
SENSITIVITY OF Porphyromonas AND Prevotella SPECIES IN LIQUID MEDIA TO ARGON LASER
Authors: Henry Clay A. , Judy Mel , Dyer Barbara , Wagner Martin , Matthews James L.
Published: January 2008

Abstract— The phototoxicity of argon laser irradiation was studied in aqueous suspensions of Porphyromonas endodontalis (American Type Culture Collection [ATCC] 35406), Porphyromonas gingivalis (ATCC 33277), Prevotella denticola (ATCC 33184) and two strains of Prevotella intermedia (ATCC 15033 and 49046), all “black‐pigmented bacteria,” BPB, that accumulate cellular porphyrins. Several of these species have been implicated in the etiology of Periodontol disease. Non‐black‐pigmented bacteria were also studied to test the specificity of irradiation as a potential photodynamic treatment for Periodontol infections. Cell suspensions were irradiated with an argon laser at fluences of 20–200 J/cm2. When cultured in hemin‐supplemented media, ATCC 15033 was the most sensitive to irradiation. However, a second strain of the same species (ATCC 49046) was resistant. The photosensitivity of other species ranked ATCC 33277 > 35406 = 33184 = 35496. When hemin was replaced in media by hemoglobin, ATCC 33277 became resistant to irradiation. Protoporphyrin IX content in BPB cells was shown not to be a major factor determining photosensitivity. Oxygen was required during irradiation for BPB species to be affected. Non‐black‐pigmented bacteria were much less sensitive to irradiation than BPB.
RESEARCH NOTE
Authors: Baraldi Rita , Bertazza Gianpaolo , Bogino Judit , Luna Virginia , Bottini Ruben
Published: January 2008

Abstract— The endogenous levels of indole‐3‐acetic acid (IAA), abscisic acid (ABA) and gibberellins (GA) were examined by gas chromatography‐mass spectrometry in Prunus cerasus plantlets grown under different light conditions in relation to previous work on the photocontrol of stem elongation. The endogenous levels of free and conjugated IAA in the apical sections of red‐grown shoots were about two‐fold higher than those in the blue‐treated plants, and these corresponded with maximum shoot elongation. By contrast, greater concentrations of ABA and GA were found in blue‐grown plants compared to red with intermediate shoot growth. When blue was combined with red or far red, lower levels of IAA, ABA and GA correlated with less growth. These results suggest that the regulation of stem elongation by phytochrome and a blue‐absorbing pigment may, at least in part, occur through a modulation of hormone levels.
EFFECT OF THYMINE DIMER INTRODUCTION IN A 21 BASE PAIR OLIGONUCLEOTIDE
Authors: Barone Flavia , Bonincontro Adalberto , Mazzei Filomena , Minoprio Anna , Pedone Francesco
Published: January 2008

Abstract— It is well known that the pyrimidine dimers are the main damage produced by UV radiation on the DNA structure. However, while studies on the photoproduct structure have been carried out extensively, uncertainties still exist on the implication that a single damaging event has on the overall conformation. In particular, the extension of the damage influence on the polynucleotide chain is a matter of debate. This problem is especially important to understanding some steps of the repair mechanisms. In this study we performed a chemical‐physical characterization of 21 base pair oligonucleotides containing a single thymine dimer in one strand. Thermodynamic parameters were determined by means of thermal denaturation experiments, and static fluorescence measurements were performed to unequivocally define the primary structure‐conformation relationship in this specific case. We used hydroxyl radicals, produced by means of γ‐irradiation of the sample solution, to detect fine structure changes. Our data show that the introduction of a single thymine dimer might cause only a slight distortion of the helix geometry, as judged by the evaluation of the enthalpic and the entropic terms and by the small changes observed in the binding of ethidium bromide to DNA. The modifications in the sugar phosphate backbone subsequent to the damaging event are especially evident, near the thymine dimer, toward the 5′‐end direction in the strand containing the dimer.
Fluorescence Study of the Conformational Properties of Recombinant Tick Anticoagulant Peptide (Ornithodorus moubata) Using Multifrequency Phase Fluorometry
Authors: Sillen Alain , Vos Rita , Engelborghs Yves
Published: January 2008

Abstract— Steady‐state and multifrequency phase fluorometry were used to characterize the conformational state and conformational dynamics of recombinant tick anticoagulant peptide (Ornithodorus moubata) (TAP). The TAP contains two tryptophan residues at positions 11 and 37. The fluorescence emission varies sigmoidally as a function of pH with a pKa of 6.01 ± 0.07. This pH dependency suggests that tryptophan fluorescence is quenched by His43 at low pH. This is confirmed by modification of the his‐tidine with diethylpyrocarbonate. At pH 9 the fluorescence decay is well described by a sum of three exponentials (0.52,1.9 and 5.4 ns), which decrease all three at pH 4 (0.25, 1.61 and 4.4 ns). From the reactivity of the fluorescence lifetimes toward N‐bromosuccinimide and from the calculation of the accessibility we can attribute the long lifetime to Trpll, the short one to Trp37 and the middle one to both. The anisotropy decay was resolved into two components of 3.85 ns and 0.27 ns at pH 4 and 4.5 ns and 0.6 ns at pH 9. The long anisotropy decay time corresponds to the rotational correlation time of the protein, the short one to local mobility of the tryptophan residues.
UVB Irradiation Upregulation of the Drosophila 1731 Retrotransposon LTR Requires the Same Short Sequence of U3 Region in a Human Epithelial Cell Line as in Drosophila Cells
Authors: Faure E. , Best‐Belpomme M. , Champion S.
Published: January 2008

Abstract— Phylogenetic analysis of the retrotransposon and retrovirus suggests an evolutionary relationship between them and indicates that transactivation of the long terminal repeat (LTR)‐containing retroelements could be ubiquitous. Using constructs expressing a reporter gene under the control of the entire or deleted LTR of 1731, which is a retrotransposable element of Drosophila melanogas‐ter, we were able to show that the UVB‐irradiation activation of the 1731‐LTR requires the same short sequence of U3 region in a human epithelial cell line as in Schneider's Drosophila cell line (S2). This sequence is similar to the binding sequence of the members of the nuclear factor‐kB (NF‐kB)/rel family. In addition, human colonic carcinoma cells (HT29), in response to UVB‐irradiation, produce some extracellular factor(s) that activates the 1731‐LTR in nonirradiated cells.
Significant Reduction of UVB Caused by Smoke from Biomass Burning in Brazil
Authors: Mlms Forrest M.
Published: January 2008

Abstract— Solar UVB radiation, total ozone and the aerosol optical thickness (AOT) of the atmosphere were measured at various sites in Brazil during the burning season of 1995. Smoke from biomass burning caused very significant AOT and up to an 81% reduction in UVB at Cuiabd, hundreds of kilometers from the most widespread burning. Little or no smoke was apparent upwind of the major burning regions at and near Manaus, and UVB was close to the expected values. There is an increased incidence of respiratory, cardiopulmonary and other diseases associated with severe air pollution, but the responsible biological mechanisms are unknown. The bactericidal effects of solar UVB are well known, and significantly reduced UVB resulting from severe air pollution in regions where UVB levels are ordinarily high might enhance the survivability of pathogenic organisms in air and water and on surfaces exposed to sunlight.
EPR Detection of Free Radicals in UV‐lrradiated Skin: Mouse Versus Human
Authors: Jurkiewicz Beth Anne , Buettnerf Garry R.
Published: January 2008

Abstract— Ultraviolet radiation produces free radicals in Skh‐1 mouse skin, contributing to photoaging and carcinogenesis. If a mouse model is a general indicator of free radical processes in human skin photobiology, then radical production observed in mouse and human skin should be directly comparative. In this work we show that UV radiation (Λ > 300 nm, 14 μW/cm2 UVB; 3.5 mW/cm2 UVA) increases the ascorbate free radical (Asc.‐) electron paramagnetic resonance (EPR) signal in both Skh‐1 mouse skin (45%) and human facial skin biopsies (340%). Visible light (Λ > 400 nm; 0.23 mW/cm2 UVA) also increased the Asc.‐ signal in human skin samples (45%) but did not increase baseline mouse Asc.‐, indicating that human skin is more susceptible to free radical formation and that a chromophore for visible light may be present. Using EPR spin‐trapping techniques, UV radiation produced spin adducts consistent with trapping lipid alkyl radicals in mouse skin (α‐[4‐pyridyl 1‐oxide]‐N‐tert‐butyl nitrone/alkyl radical adduct; aN= 15.56 G and aH= 2.70 G) and lipid alkoxyl radicals in human skin (5,5‐dimethylpyrroline‐l‐oxide/alkoxyl radical adduct; aN= 14.54 G and aH= 16.0 G). Topical application of the iron chelator Desferal to human skin significantly decreases these radicals (±50%), indicating a role for iron in lipid peroxidation; Desferal has previously been shown to decrease radical production in mouse skin. This work supports the use of the Skh‐1 mouse as a predictive tool for free radical formation in human skin. These results provide the first direct evidence for UV radiation‐induced free radical formation at near physiological temperatures in human skin and suggest that iron chelators may be useful as photoprotective agents.
Characterization of psal and psaL Mutants of Synechococcus sp. Strain PCC 7002: A New Model for State Transitions in Cyanobacteria
Authors: Schluchter Wendy M. , Shen Gaozhong , Zhao Jindong , Bryant Donald A.
Published: January 2008

The psal and psaL genes were characterized from the cyanobacterium Synechococcus sp. strain PCC 7002. The gene organization was different from that reported for other cyanobacteria with psal occurring upstream and being divergently transcribed from the psaL gene. Mutants lacking Psal or PsaL were generated by interposon mutagenesis and characterized physiologically and biochemically. Mutant strains PR6307 (Δpsal−), PR6308 (psal) and PR6309 (psaL−) had doubling times similar to that of the wild type under both high‐ and low‐intensity white light, but all grew more slowly than the wild type in green light. Only monomeric photosystem I (PS I) complexes could be isolated from each mutant strain when Triton X‐100 was used to solubilize thylakoid membranes; however, approximately 10% of the PS I complexes from the psal mutants, but not the psaL mutant, could be isolated as trimers when n‐do‐decyl β‐D‐maltoside was used. Compositional analyses of the mutant PS I complexes indicate that the presence of PsaL is required for trimer formation or stabilization and that Psal plays a role in stabilizing the binding of both PsaL and PsaM to the PS I complex. Strain PR6309 (psaL−) was capable of performing a state 2 to state 1 transition approximately three times more rapidly than the wild type. Because the monomeric PS I complexes of this mutant should be capable of diffusing more rapidly than trimeric complexes, these data suggest that PS I complexes rather than phycobilisomes might move during state transitions. A “mobile‐PS I” model for state transitions that incorporates these ideas is discussed.
Study of Photoinduced Energy and Electron Transfer in α‐Terthienyl‐Bovine Serum Albumin Conjugates: A Laser Flash Photolysis Study*
Authors: Boch R. , Mohtat N. , Lear Y. , Arnason J. T. , Durst T. , Scaiano J. C.
Published: January 2008

The photochemistry of α‐terthienyl (α‐T) has been examined in bovine serum albumin (BSA). Freely associated and covalently conjugated α‐T chromophores show similar behavior toward nonpolar quenchers such as oxygen and benzoquinone but show significant differences in the case of quenching by methyl viologen, a water‐soluble cationic electron acceptor; in this case, triplet quenching reveals two distinct α‐T populations, attributed to chromophores in sites showing very different accessibility from the aqueous phase. Rate constants for triplet quenching in BSA are generally slower than those observed in homogeneous solution for free α‐T. For example, in the case of oxygen, the rate constant is about one order of magnitude smaller when α‐T is associated or conjugated with the protein compared with α‐T in solution. While triplet yields for α‐T are essentially the same in solution and in the protein environment, the yield of detectable singlet oxygen is substantially reduced in the protein. This is attributed to a geminate reaction within the protein involving singlet oxygen trapping in the vicinity of the generation site.
Photoinactivation of Superoxide Synthases of the Plasma Membrane from Rose (Rosa damascena Mill.) Cells
Authors: Murphy Terence M. , Vu Han
Published: January 2008

The UVC‐induced synthesis of hydrogen peroxide (H2O2) by cultured rose (Rosa damascena Mill, cv Gloire de Guilan) cells is inhibited by broad‐band radiation containing UVA, UVB and blue wavelengths. In order to understand the basis for this inhibition, we tested the effects of broad‐band radiation and of monochromatic radiation on NADH‐ and NADPH‐dependent O2‐ synthases of purified plasma membranes. Both activities were inhibited by wavelengths from 254 to 435 nm, with the NADPH‐dependent enzyme being more sensitive than the NADH‐dependent enzyme. Incubation in the presence of flavin adenine dinucleotide had a small but significant ameliorative effect on the inhibition of the O2‐ synthase activities of plasma membranes by 300 nm radiation. The data support the hypothesis that the NADH‐ and NADPH‐dependent activities are catalyzed by different enzymes. The NADPH‐dependent activity, but not the NADH‐dependent activity, was sufficiently sensitive to account for the inhibition of H2O2 synthesis by the broad‐band radiation.
Mycosporine‐like Amino Acids Provide Protection Against Ultraviolet Radiation in Eggs of the Green Sea Urchin Strongylocentrotus droebachiensis
Authors: Adams Nikki L. , Shick J. Malcolm
Published: January 2008

A photoprotective role of ultraviolet radiation‐absorbing mycosporine‐like amino acids (MAAs) in eggs of the green sea urchin Strongylocentrotus droebachiensis was demonstrated by comparing UV‐induced delays in the first division of embryos having either high or low concentrations of MAAs. Embryos from adult urchins fed Laminaria saccharina (no MAAs) had low concentrations of MAAs and experienced a significantly longer UV‐induced delay in cleavage (25.1%) than MAA‐rich embryos from adults fed Mastocarpus stellatus (12.8% delay) or a combination diet of both macroalgae (12.3% delay). Collectively, these embryos displayed a significant inverse logarithmic relationship between MAA concentration and percentage cleavage delay, so that the greater the MAA concentration in the eggs, the less they were affected by UV radiation. This is the first study to examine such MAA manipulation of cellular MAA concentrations with no prior UV exposure of the experimental subjects. Concentrations of MAAs were also measured in unfertilized eggs, blastulae, gastrulae and early pluteus larvae, providing the first documentation of changes in MAAs during embryological and larval development. The concentration of shinorine (the principal MAA in the eggs) did not change during short‐term UV exposure in vivo or long‐term exposure in vitro; such photostability is a useful attribute of a natural sunscreen.
Effect of Glucose on Photodynamic Action of Methylene Blue in Escherichia coli Cells
Authors: Capella Márcia , Coelho Ana Maria , Menezes Salatiel
Published: January 2008

The results of this work show that the resistance of Escherichia coli cells to the photodynamic action of methylene blue is increased by the addition of glucose to the media in which they are grown. It is postulated that the increased resistance may be due to lowered retention of the dye by cells grown in the presence of glucose, leading to the diminution in DNA damage revealed in the alkaline sucrose gradients. The role of cyclic adenosine‐monophosphate in the protective action of glucose is discussed.
UV Radiation and Mouse Models of Herpes Simplex Virus Infection
Authors: Norval Mary , El‐Ghorr Ali A.
Published: January 2008

Orolabial human infections with herpes simplex virus type 1 (HSV‐1) are very common; following the primary epidermal infection, the virus is retained in a latent form in the trigeminal ganglia from where it can reactivate and cause a recrudescent lesion. Recrudescences are triggered by various stimuli including exposure to sunlight. In this review three categories of mouse models are used to examine the effects of UV irradiation on HSV infections: these are UV exposure prior to primary infection, UV exposure as a triggering event for recrudescence and UV exposure prior to challenge with virus in mice already immunized to HSV. In each of these models immunosuppression occurs, which is manifest, in some instances, in increased morbidity or an increased rate of recrudescence. Where known, the immunological mechanisms involved in the models are summarized and their relevance to human infections considered.