bluuebunny/crossref_metadata_2025 huggingface dataset:
SINGLET OXYGEN GENERATION BY PORPHYRINS AND THE KINETICS OF 9,10‐DIMETHYLANTHRACENE PHOTOSENSITIZATION IN LIPOSOMES
Authors: Gross Eitan , Ehrenberg Benjamin , Johnson Fred M.
Published: January 2008

Abstract—Two new sensitizers are introduced for a potential use in photodynamic therapy: Zn2+‐ and MG2+‐tetrabenzoporphyrin (ZnTBP and MgTBP). A comparative study of the quantum yields of singlet oxygen generation (ΦΔ) of hematoporphyrin derivative (HpD), Photofrin II (PF‐II), Zn2+‐phthalocyanine tetrahydroxyl [ZnPC(OH)4] and the newly introduced sensitizers ZnTBP and MgTBP in liposomes, as well as the kinetics of a photochemical reaction sensitized by them, was made by employing the fluorescent membrane probe 9,10‐dimethylanthracene (DMA). We followed the photosensitization of DMA in real time by monitoring its fluorescence decrease at 457 nm and found that DMA's photosensitization is oxygen mediated. The kinetic traces of the photosensitization reactions were fitted to an analytical function, and the ΦΔvalues were evaluated. At 10 μMsensitizer in an aqueous suspension of 2 mg/mL egg phosphatidylcholine (EPC), HpD was found to have the largest value of ΦΔ(0.215), followed by PF‐II (0.191), ZnTBP (0.023), MgTBP (0.019) and ZnPC(OH)4(0.005). As a test of the method, ΦΔfor methylene blue in ethanol was measured and found to be 0.45 as compared to 0.52 reported in the literature. Due to difference in the sensitizers' absorbances at the laser's wavelength, the reaction photosensitized by ZnTBP was the fastest with a time constant of 6.7 min, followed by MgTBP (8.7), PF‐II (11.9), HpD (17.1) and ZnPC(OH)4(31.2), all at equal sensitizers' concentrations and laser intensities. The binding constants of the sensitizers to EPC liposomes are also reported.
THE 75°C THERMOLUMINESCENCE BAND OF GREEN TISSUES: CHEMILUMINESCENCE FROM MEMBRANE‐CHLOROPHYLL INTERACTION
Authors: Hideg ÉVa , Vass Imre
Published: January 2008

Abstract— Exposure of thylakoid membranes of green plants to high temperature promotes the appearance of free radicals resulting in a thermoluminesccnce (TL) band peaking around 75°C. The occurrence of this band with the same intensity in prcilluminated and in dark‐adapted samples demonstrates that, contrary to several other TL bands, it is not a result of charge recombination. The high temperature TL band is oxygen dependent. Parallel to TL emission singlet oxygen is formed, as demonstrated by spin trapping EPR measurements and by the decrease of TL intensity in the presencc of sodium‐azide, a singlet oxygen scavenger.

We suggest that the 75°C TL band is a result of a temperature‐enhanced interaction between molecular oxygen and the photosynthetic membrane, possibly involving lipid peroxidation. The spectral maximum of the emission (around 720 nm) implics that light emission occurs upon energy transfer from an excited product to chlorophyll molecules destablized from pigment‐protein complexes.
EVIDENCE FOR THE PHOTOPROTECTIVE EFFECTS OF VITAMIN E
Authors: Fryer Michael J.
Published: January 2008

Abstract—The antioxidant vitamin E (α‐tocopherol) may protect both animal and plant cell membranes from light‐induced damage. The various biochemical and biophysical modes of protection are considered. An examination is made of the evidence that vitamin E plays an important prophylactic role against a number of serious light‐induced diseases and conditions of the eye (cataractogenesis and retinal photodeterioration) and skin (erythrocyte photohem‐olysis, photoerythema, photoaging and photocarcinogenesis) that are mediated by photooxidative damage to cell membranes.
BENZOPHENONE‐SENSITIZED LIPID PEROXIDATION IN LINOLEATE MICELLES
Authors: Markovic Dejan Z. , Patterson L. K.
Published: January 2008

Abstract— Benzophenone‐photosensitized peroxidation in linoleic acid micelles (Type I reaction) has been investigated and quantum yields of both sensitizer photolysis and lipid peroxidation have been obtained. Benzophenone as well as its derivative, benzophenone‐4′‐heptyl‐4‐pentanoic acid (BHPA) have been utilized as sensitizers in this study. A quantum yield of 1.2 for hydroperoxide formation, compared with a benzophenone disappearance quantum yield of 0.41 (in the same linoleate micellar solution) was obtained; yields of 1.3 and 0.6 were found for comparable systems in which BHPA was the sensitizer. Although such data are consistent with the peroxidation mechanism of chain reaction, it is necessary to know the yields of initiating species to arrive at chain reaction lengths in these systems. Such yields have been determined by flash photolysis. The dependencies of sensitizer photolysis and hydroperoxide yields on linoleate concentration have also been determined in order to elucidate the effects of micelle formation or molecular organization on the peroxidative process. Additionally, for comparison in a saturated surfactant (lipid) system hydrogen abstraction was investigated by photolysis techniques in sodium dodecyl sulfate alone using these two sensitizers.
THE ROLE OF DNA DAMAGE IN PM2 VIRAL INACTIVATION BY METHYLENE BLUE PHOTOSENSITIZATION
Authors: Specht Kathleen G.
Published: January 2008

Abstract— This study investigates the importance of DNA damage in viral inactivation by phenothiazines and light. Phenothiazines, including methylene blue (MB), toluidine blue and azure B are of particular interest because of their ability to bind to nucleic acids in vitro. Initial studies employing phages T7, MS2 and PM2 indicated that both DNA and RNA phages as well as enveloped and nonenveloped phages can be inactivated by phenothiazine photosensiti‐zation. PM2, which contains a lipid‐protein bilayer and supercoiled DNA, was used for the mechanistic studies to model blood‐borne viruses. Viral DNA damage was assessed following treatment of phage to known levels of viral inactivation by extracting the DNA and analyzing for both direct and piperidine‐catalyzed strand cleavage by gel electrophoresis. DNA strand cleavage was found to be both sensitizer concentration and light dose dependent. Both viral inactivation and DNA damage were found to be oxygen‐dependent events. In parallel experiments, strand cleavage of isolated PM2 DNA treated with MB and light was also found to be oxygen dependent, in contrast to some previous reports. Transfection studies, which measure the infectivity of the extracted viral DNA, indicated that DNA from MB‐treated phage was just as capable of generating progeny virus as the untreated controls. It was therefore concluded that the observed DNA damage is not correlated with loss of phage infectivity.
STRATOSPHERIC OZONE DEPLETION BETWEEN 1979 and 1992: IMPLICATIONS FOR BIOLOGICALLY ACTIVE ULTRAVIOLET‐B RADIATION and NON‐MELANOMA SKIN CANCER INCIDENCE
Authors: Madronich Sasha , Gruijl Frank R. de
Published: January 2008

Abstract— The depletion of stratospheric ozone (03) has predictable implications for increases in biologically damaging solar ultraviolet‐B radiation (UVB,280–320 nm) reaching the earth's surface. A radiative transfer analysis of satellite‐based O3 measurements between January 1979 and December 1992 shows that surface UVB levels increased substantially at all latitudes except the tropics, if other factors such as cloud cover and local pollutant levels have remained constant over this period. Exposure to UVB radiation is known to induce basal cell and squamous cell skin cancers, and dose‐response relationships derived from epidemiological data can be combined with the UVB enhancements to estimate the seasonal and latitudinal distribution of future expected increases in the incidence of these cancers.
LASER‐INDUCED FLUORESCENCE LINE NARROWING OF NATIVE PORPHYRINS IN ANIMAL TISSUE
Authors: Novikov A. V.
Published: January 2008

Using monochromatic laser excitation, narrowing of the porphyrins 0‐0 fluorescence line in rat muscle tissue to a width of 50‐70 cm−l at 4.2 K is observed. Fluorescence spectra at different excitation wavelengths and excitation spectra are measured. Fluorescence line peak follows the shift of the excitation frequency. Several of the most prominent vibrational frequencies of porphyrins in the excited electronic state are determined.
DIAMINODURENE AS A MEDIATOR OF A PHOTOCURRENT USING INTACT CELLS OF CYANOBACTERIA
Authors: Martens Nicolas , Hall Elizabeth A. H.
Published: January 2008

Abstract –A mediator for the measurement of a photocurrent generated by intact cells of cyanobacteria immobilized onto the working electrode in an electrochemical cell is described. The efficiency of diaminodurene (DAD) as an electron shuttle between the photosynthetic electron transport chain (PET) within the cells and the electrode was compared with ferrocyanide and p‐benzoquinone. A simple Synechococcus‐carbon‐paste electrode containing DAD as the mediator in the electrode material and the photosynthetic cells immobilized in a polymer matrix was constructed. The device required no addition of further reagents to the bulk solution for the generation of a photocurrent. Using cyclic voltammetry the second‐order rate constant for the reaction of DAD with the PET was determined. Diaminodurene compared favorably with p‐benzoquinone in that the overpotential was reduced to 0.2 V. The deterioration of the PET by the DAD was significantly decreased compared with p‐benzoquinone, resulting in a prolonged lifetime of the electrode. A possible mechanism for the reaction of DAD with the PET is discussed.
PHOTOSENSITIZATION BY FENOFIBRATE. II. In vitro PHOTOTOXICITY OF THE MAJOR METABOLITES
Authors: Miranda Miguel A. , Boscaa Francisco , Vargas Franklin , Canudas Nieves
Published: January 2008

Fenofibric acid, the major metabolite of fenofibrate, was found to be photolabile. Its irradiation in aqueous solution gave rise to two photoproducts, whose formation involves photodecarboxylation of the dissociated acid to an aryloxy‐substituted carbanion, which is directly protonated or, alternatively, undergoes a Wittig rearrangement. A comparative in vitro phototoxicity study has been carried out on the anti‐hyperlipoproteinemic drug fenofibrate, its metabolites and the photoproducts of fenofibric acid. Fenofibrate, fenofibric acid and its two photoproducts were found to be active when examined by the photohemolysis test and were able to photosensitize peroxidation of linoleic acid, as evidenced by the UV monitoring of dienic hydroperoxides. In summary, the major metabolite of fenofibrate (fenofibric acid), as well as its photoproducts, are phototoxic in vitro. This behavior can be attributed to the fact that the four compounds retain the benzophenone chromophore present in fenofibrate and is indicative of free radicalmediated photosensitization. In agreement with this rationalization, the metabolites with a reduced ketone functionality exhibit no detectable in vitro phototoxicity.
DELAY OF CELL DIFFERENTIATION IN Anabaena aequalis CAUSED BY UV‐B RADIATION AND THE ROLE OF PHOTOREACTIVATION AND EXCISION REPAIR
Authors: Blakefield Mary K. , Harris Denny O.
Published: January 2008

The effect of ultraviolet light on cell differentiation was studied in the cyanobacterium Anabaena aequalis. Exposure of cells to UV‐B wavelengths (280‐320 nm) significantly delayed the differentiation of vegetative cells into heterocysts and akinetes at doses up to 56 kJ m‐2. Heterocyst differentiation was essentially stopped at all exposure levels when photoreactivation was prevented, even when excision repair was available to the cells. Photoreactivated samples produced heterocysts at doses through 28 kJ m‐2, after which differentiation dropped steeply to near zero levels. Some recovery of differentiation was evident at higher doses but at levels much below that of controls. Akinete differentiation was only slightly delayed by the exposures when cells were photoreactivated. Samples then showed rapid differentiation with the numbers of akinetes significantly greater than controls. Cells that did not receive photoreactivating light showed a greater initial delay in differentiation but 2 weeks after the exposures had recovered to control levels. Caffeine had more effect on the differentiation of akinetes than heterocysts. Inhibition of excision repair greatly reduced differentiation in photoreactivated samples and essentially eliminated differentiation in the nonphotoreactivated samples.
PHOTOCHEMICAL ALTERATIONS IN DNA REVEALED BY DNA‐BASED LIQUID CRYSTALS
Authors: Nikogosyan D. N. , Repeyev Yu. A. , Yakovlev D. Yu. , Salyanov V. I. , Skuridin S. G. , Yevdokimov Yu. M.
Published: January 2008

AbstractThe preparations of chicken erythrocyte linear double‐stranded DNA and superhelical plasmid pBR322 DNA were irradiated by continuous low‐intensity UV radiation (I = 25‐50 W/m2, λ= 254 nm) as well as by highintensity picosecond laser UV radiation (I = 1011‐1013W/m2, λ= 266 nm). The effect of DNA secondary structure alterations on the formation of liquid‐crystalline dispersions from UV‐irradiated DNA preparations was studied. It was shown that in the case of linear DNA, watching the disappearance of abnormal optical activity characteristic for cholesteric liquid crystal we managed to detect the presence of photochemical alterations in DNA irradiated by low‐intensity UV radiation at an absorbed energy of more than 20 quanta per nucleotide. In the case of superhelical DNA using enzyme treatment of liquid‐crystalline dispersions and monitoring the appearance of abnormal optical activity, we detected the presence of photochemical alterations in DNA molecules after low‐intensity UV irradiation at an absorbed energy of less than 4 quanta per nucleotide. Under the latter approach using picosecond UV laser irradiation at three different light intensities we were able to distinguish the different mechanisms of fine alterations in DNA secondary structure at an absorbed energy value of about 3 quanta per nucleotide.
OPTICAL AND THERMAL CHARACTERIZATION OF NATURAL (Sepia officinalis) MELANIN
Authors: Vitkin I. Alex , Woolsey Joshua , Wilson Brian C. , Anderson R. Rox
Published: January 2008

Abstract The optical properties and the thermal diffusivity of natural cuttlefish (Sepia officinalis) melanin have been measured. The optical absorption and scattering properties of melanin particles were determined at 580 nm and 633 nm, using photometric and photothermal techniques. For the photometric studies, the absorption and the transport scattering coefficients were determined from the measurements of diffuse reflectance and transmittance. The scattering anisotropy was obtained from an additional measurement of the total attenuation coefficient and independently obtained by goniometry. For photothermal studies, pulsed photothermal radiometry was used to deduce the absorption and transport scattering coefficients via a model based on optical diffusion theory. Pulsed photothermal radiometry was also used to provide the thermal diffusivity of solid melanin pressed pellets.
PHOTODYNAMIC THERAPY WITH PHOTOFRIN II INDUCES PROGRAMMED CELL DEATH IN CARCINOMA CELL LINES
Authors: He Xiao‐Yan , Sikes Robert A. , Thomsen Sharon , Chung Leland W. K. , Jacques Steven L.
Published: January 2008

Abstract The mode of cell death following photodynamic therapy was investigated from the perspective of programmed cell death or apoptosis. Human prostate carcinoma cells (PC3), human non‐small cell lung carcinoma (H322a) and rat mammary carcinoma (MTF7) were treated by photodynamic therapy. An examination of extracted cellular DNA by gel electrophoresis showed the characteristic DNA ladder indicative of internucleosomal cleavage of DNA during apoptosis. The magnitude of the response and the photodynamic therapy dosage required to induce DNA fragmentation were different in PC3 and MTF7. The MTF7 cells responded with rapid apoptosis at the dose of light and drug that yielded 50% cell death (LD50). In contrast, PC3 showed only marginal response at the LD50 but had a marked response at the LD85. Thus, apoptosis did not ensue as quickly in PC3 as in MTF7. The H322a cells were killed by photodynamic therapy but failed to exhibit any apoptotic response. The results also suggested that apoptosis in these cell lines has a minor requirement for de novo protein synthesis and no requirement for de novo RNA synthesis. This study indicates that although apoptosis can occur during photodynamic therapy‐induced cell death, this response is not universal for all cancer cell lines.
EPR AND TREPR SPECTROSCOPIC STUDIES OF ANTIOXIDANT SESAMOLYL AND RELATED PHENOXYL RADICALS
Authors: Nakagawa Kouichi , Tero‐Kubota Shozo , Ikegami Yusaku , Tsuchihashi Nobuaki
Published: January 2008

Abstract Sesamolyl and related phenoxyl radicals were studied by conventional and time‐resolved electron paramagnetic resonance (EPR) spectroscopic techniques. Continuous UV irradiation of sesamol in benzene produces two types of radicals. Based on the hyperfine coupling values obtained we determined that one is the neutral sesamolyl radical and the others are the dimer radicals. Comparison was made with related compounds, especially 3,4‐dime‐thoxyphenol. We found that the 3,4‐dimethoxyphenoxyl radical had a shorter lifetime than the neutral sesamolyl radical. The EPR results obtained suggest that a near perpendicular orientation of the oxygen p‐orbitals with respect to the benzene ring of sesamol makes the radical more stable. This stability may be important for the antioxidant properties.
THE INTERACTION OF MELANIN WITH 8‐METHOXYPSORALEN: EFFECT ON RADIATIVE and NONRADIATIVE TRANSITIONS. A FLUORESCENCE and PULSED PHOTOACOUSTIC STUDY
Authors: Losi Aba , Viappiani Cristiano , Crippa Pier Raimondo
Published: January 2008

Abstract –The interaction of 8‐methoxypsoralen (8‐MOP) with synthetic eumelanin was investigated using static and time‐resolved fluorescence and pulsed photoacoustic calorimetry. Due to the strong overlap of the absorption bands of melanin and 8‐MOP, a method is presented to account for the systematic errors introduced by the optical filter effect exerted by each absorbing species in the fluorescence and the photoacoustic measurements. As a preliminary step to the understanding of the nonradiative behavior of the psoralen‐melanin complexes, the photoacoustic parameters of 8‐MOP in various solvents were determined. Spectroscopic data indicate the absence of interaction at the ground‐state level, whereas the singlet excited state of 8‐MOP is quenched by the pigment; the average fluorescence lifetimes are independent of the melanin concentration, thus indicating a static quenching mechanism. The photoacoustic data show that the quenching process involves an increased intersystem crossing probability, which is almost unaffected by the presence of oxygen, as expected for a molecule essentially acting as a type I photosensitizing agent.
PHOTOPHYSICAL STUDIES ON HUMAN RETINAL LIPOFUSCIN
Authors: Gaillard Elizabeth R. , Atherton Stephen J. , Eldred Graig , Dillon James
Published: January 2008

Fluorescent material generated in the human retina accumulates within lipofuscin granules of the retinal pigment epithelium (RPE) during aging. Its presence has been suggested to contributed to various diseases including age‐related macular degeneration. Because this material absorbs light at wave lengths as long as 550 nm, photophysical studies were performed to determine whether lipofuscin could contribute to light damage and to determine if its composition is similar to a synthetically prepared lipofuscin. Time‐resolved experiments were performed to monitor (1) fluorescence decay, (2) the UV‐visible absorption of longer‐lived excited states and (3) the formation and decay of singlet oxygen at 1270 nm. Steady‐state and time‐resolved fluorescence studies indicate that human and synthetic lipofuscin have fluorophores in common. Time‐resolved absorption experiments on human retinal lipofuscin and synthetic lipofuscin showed the presence of at least two transient species, one absorbing at 430 nm (lifetime caμs) and a second absorbing at 580 nm, which decays via second order kinetics. In addition, there is a third absorbing species stable to several hundred milliseconds. The transient species at 430 nm is quenched by oxygen, suggesting that it is a triplet state. Subsequent studies showed the formation of singlet oxygen, which was monitored by its phosphorescence decay at 1270 nm. These studies demonstrate that lipofuscin can act as a sensitizer for the generation of reactive oxygen species that may contribute to the age‐related decline of RPE function and blue light damage.
REGULATION and INHIBITION OF COLLAGENASE EXPRESSION BY LONG‐WAVELENGTH ULTRAVIOLET RADIATION IN CULTURED HUMAN SKIN FIBROBLASTS*
Authors: Petersen Marta , Hamilton Tiffani , Li Hai‐Li
Published: January 2008

Abstract—

The cellular mechanisms responsible for the connective tissue changes produced by chronic exposure to UV light are poorly understood. Collagenase, a metalloproteinase, initiates degradation of types I and III collagen and thus plays a key role in the remodeling of dermal collagen. Collagenase synthesis by fibroblasts and keratinocytes involves the protein kinase C (PKC) second messenger system, and corticosteroids have been shown to suppress its synthesis at the level of gene transcription. Long‐wavelength UV light (UVA,320–400 nm) stimulates the synthesis of interstitial collagenase, as well as increasing PKC activity, in human skin fibroblasts in vitro. This study explores the regulation of collagenase expression by UVA in cultured human skin fibroblasts. Specifically, the time course, the effect of actinomycin D, an inhibitor of RNA synthesis, as well as the effect of PKC inhibitors and dexa‐methasone on expression of collagenase following UVA irradiation were examined. After UVA irradiation, collagenase mRNA rose rapidly between 4 and 12 h postirradiation, peaking 18 h post‐UVA. Actinomycin D completely suppressed the UVA‐induced increase in collagenase mRNA. Thus, new RNA synthesis is required for the UVA‐induced increase in collagenase mRNA. The PKC inhibitor, H‐7, blocked the increase in collagenase mRNA in response to UVA in a dose‐dependent manner. Similarly, dexamethasone also inhibited collagenase gene expression induced by UVA in a dose‐dependent fashion; the majority of the inhibitory effect was seen within the first 4 h after irradiation. These studies demonstrate that the effect of UVA on collagenase gene expression is regulated at the pretranscriptional level and may involve the PKC pathway.
BIOLUMINESCENCE OF BRAZILIAN FIREFLIES (COLEOPTERA: LAMPYRIDAE): SPECTRAL DISTRIBUTION and pH EFFECT ON LUCIFERASE‐ELICITED COLORS. COMPARISON WITH ELATERID and PHENGODID LUCIFERASES
Authors: Viviani Vadim R. , Bechara Etelvino J. H.
Published: January 2008

Abstract—

Twenty‐five Brazilian species (nine genera: Phorinus, Photinoides, Macrolampis, Aspisoma, Cratomorphus, Amydetes, Photuris, Bicellonychia, Pyrogaster) of adult fireflies were found to emit light in vivo in the green‐yellow range (Λmax=548–573 nm) of the spectrum, more frequently near the green region, in contrast with North‐American species, which predominantly emit yellow light. Distinct ecological contexts where these species evolved, such as the habitat (open field vs forests) and the duration of twilight, are discussed as possible factors responsible for these differences. Except for Photuris and Bicellonychia spp., the in vivo and in vitro bioluminescence spectra for various species of a given genus agree within ±5 nm. Lowering the pH caused the typical red shift in the in vitro bioluminescence spectrum from lampyrid luciferases (six species), which has been interpreted as due to the presence of a basic residue in the enzyme active site catalyzing fast enolization of the initially formed excited keto‐oxyluciferin (red emitter) to the excited enol form (yellow‐green emitter). The in vitro bioluminescence colors obtained from larval or adult elaterid (five species) and phengodid (three species) luciferases studied here, spanning the green‐red region, do not respond to pH changes. This could indicate either the absence of the neighboring basic center (in red‐emitting luciferases) or the presence of a non‐pH affected proximal basic residue in the active site of the luciferase (in yellow‐green‐emitting luciferases).
RESONANCE RAMAN EVIDENCE FOR 15‐cis TO MA,‐trans PHOTOISOMERIZATION OF SPIRILLOXANTHIN BOUND TO A REDUCED FORM OF THE REACTION CENTER OF Rhodospirillum rubrum SI
Authors: Kuki Michitaka , Naruse Mitsuru , Kakuno Tomlsaburo , Koyamai Yasushi
Published: January 2008

Abstract—

The reaction center (RC) of Rhodospirillum rubrum SI, which was prepared by ultrafiltration, showed one peak in molecular‐sieve HPLC, but it showed two peaks in diethylaminoethyl (DEAE) ion‐exchange HPLC; they were named as RC‐α and RC‐β in the order of elution, Nonequilibrated isoelectric electrophoresis, together with DEAE ion‐exchange HPLC, showed that RC‐β is electronically more negative than RC‐α. Oxidation of RC‐β by addition of ferricyanide caused its transformation into RC‐α, while reduction of RC‐α by adding ascorbate and subsequent illumination caused its transformation into RC‐β. Resonance Raman spectroscopy of the RC at liquid nitrogen temperature detected the all‐trans and the 15‐cis isomers in a ratio of 1:1, but HPLC analyses of the carotenoid extracted from the RC before and after the Raman measurements detected the pair of isomers in a ratio of 1:6. Thus, the 15‐cis to all‐trans isomerization takes place during irradiation at liquid nitrogen temperature, while the reverse isomerization takes place in the dark. The isolated RC‐α and RC‐β exhibited the bleaching of the 868 nm band, and contained the H, M and L subunits and 1.2‐1.4 molecules of ubiquinone‐10 per RC. Each RC slowly equilibrated in the dark toward a mixture of RC‐α and RC‐β. Generation of the all‐trans isomer in the light was found not in RC‐α but in RC‐β.
NEAR‐INFRARED FOURIER‐TRANSFORM RAMAN STUDY OF CHLOROPHYLL a IN SOLUTIONS
Authors: Sato H. , Okada K. , Uehara K. , Ozaki Y.
Published: January 2008

Abstract— The 1064 nm excited Fourier‐transform (FT) Raman spectra have been measured for chlorophyll a (Chl‐a) in various solutions. Features of the obtained spectra are largely different from those of Soret‐resonant Raman spectra of Chl‐a. For example, a band due to the C=0 stretching mode of the 13‐keto group is much stronger in the former than in the latter. Although the excitation wavelength is rather far from that of the Qy absorption of Chl‐a, notable enhancements of bands due to the C=O stretching mode of the 131‐keto group and to the C=C stretching mode of the vinyl group and those in the 1250–600 cm‐1 region suggest that the 1064 nm‐excited Raman spectra of Chl‐a are preresonance enhanced via the Qy band. Some of the marker bands for the coordination number of the central Mg atom, which have been used in the visible‐excited resonance Raman spectra, are not valid in the 1064 nm‐excited Raman spectra. Instead, new marker bands are found in the latter. The 1064‐nm excited Raman spectra of Chl‐a in a hydrated hexane solution reveal that the dehydrated oligomer of Chl‐a as well as Chl‐a‐water micelles coexist in the solution. They also suggest that the size of the oligomer is considerably larger and the hydrogen bonding of the 131‐keto group in the oligomer is weaker than that in the micelles.
CIRCADIAN RHYTHM OF Robinia pseudoacacia LEAFLET MOVEMENTS: ROLE OF CALCIUM AND PHYTOCHROME
Authors: Gómez Luis Angel , Simón Esther
Published: January 2008

Abstract— The effect of external calcium level, calcium ionophore A23187 and red light on the circadian rhythm of Robinia pseudoacacia leaflet movements has been studied. Fifteen minute red light pulses shifted the phase of leaflet rhythmic movement with a phase‐response curve type 0. Maximum advances and delays (about 10 h and 8 h, respectively) were obtained between circadian time (CT) 10 and CT 12 at the end of a subjective day. An almost null effect was obtained at the end of a subjective night. Phytochrome is the photoreceptor involved in phase shifting since this effect of red light is reversed by 5 min of far red light. Two hour pulses of external calcium, applied as CaCl2 (10 mM), and 2 h pulses of calcium ionophore A23187 (10–50 μM) also shifted the phase of leaflet circadian movement and caused the same type of phase‐response curve, with maximum advances and delays at the same time as those produced by red light. Two hour pulses of an external calcium chelator, EGTA (5 mM), and a calcium channel blocker, LaCl3 (10–50 mM), damped the circadian rhythm or did not change the phase when they were applied at lower concentration. These results indicate that phytochrome could control the circadian oscillator, which drives Robinia leaflet movements by increasing the intracellular calcium concentration.
THE INTERACTION OF THE EXCITED STATES OF SAFRANINE T WITH ALIPHATIC AMINES IN ORGANIC SOLVENTS
Authors: Encinas Maria V. , Previtali Carlos M. , Bertolotti Sonia G. , Neumann Miguel G.
Published: January 2008

Abstract—

The reactions of the excited states of safranine T with aliphatic amines have been studied in methanol and acetonitrile. Quenching of the singlet and triplet states occurs by different mechanisms. Whereas the former excited state is quenched by a charge‐transfer mechanism, the triplet state is quenched through proton transfer from the excited dye to the amine. This process leads to the unprotonated form of the dye in the triplet state, which is later quenched by amines to form the corresponding semireduced species. The monoprotonated triplet also undergoes self‐quenching in both solvents (k= 1.2 × 108M‐1 s‐1).
INDUCTION OF CYCLOBUTANE PYRIMIDINE DIMER PHOTOLYASE IN CULTURED FISH CELLS BY FLUORESCENT LIGHT AND OXYGEN STRESS
Authors: Mitani Hiroshi , Shima Akihiro
Published: January 2008

Abstract— The expression of a gene for photolyase in RBCF‐1 cells, a line of cultured goldfish cells, is known to be enhanced by fluorescent light. We have now found that H2O2 is another strong inducer of cyclobutane pyrimidine dimer photolyase. Northern blot analysis suggested that regulation by H2O2 occurs at the transcriptional level and the time course of induction of photolyase by H2O2 was similar to that by fluorescent light. Treatment with fluorescent light in the presence of riboflavin, which is known as an endogenous photosensitizer, also enhanced the induction of photolyase. These results suggest the involvement of oxygen stress in the induction of photolyase by fluorescent light. A cell clone with high‐level expression of the goldfish gene for photolyase was obtained by transfection with plasmids that expressed the goldfish photolyase in OL32 cells derived from another fish, the medaka (Oryzias latipes). The induction of the medaka gene for photolyase was not affected by the high‐level expression of the goldfish gene for this enzyme.
INDUCTION KINETICS OF DELAYED LUMINESCENCE IN PHOTOSYNTHETIC ORGANISMS AS MEASURED BY AN LED‐BASED PHOSPHORIMETER
Authors: Schmidt Werner , Schneckenburger Herbert
Published: January 2008

Abstract—Induction kinetics of delayed luminescence of photosynthetic organisms were measured with a computer‐controlled spectrophotometer based on a 3 × 3 array of novel, red superbright light‐emitting diodes (LED). Compared to the conventional Becquerel phosphoroscope, the computer‐controlled setup is characterized by superior measuring properties, simplicity, small size and a rugged construction with no mechanical moving parts. Time resolution of approximately 10 ms allows the observation of early processes of photosynthesis reflecting the light‐induced build‐up of an electrochemical potential across thylakoid membranes. A complex kinetic time course of light induction of delayed luminescence is observed in all dark‐adapted photosynthetic organisms, but the crude pattern is always similar: a fast initial increase within 40 ms, followed by a slower drop within some 300 ms, a second increase to a maximum within a few seconds and finally a slow decrease within 30 s toward a low emission steady state. The results are interpreted in terms of photosynthetic reaction steps. Preliminary data obtained from needles of a healthy and a declining spruce as monitored during the growing season 1994 are presented. Light emission of delayed light as observed both within 500 ms and within 30 s time periods is interpreted in terms of “vitality.”
CARCINOGENIC and MELANOGENIC EFFECTS OF A FILTERED METAL HALIDE UVA SOURCE and A TUBULAR FLUORESCENT UVA TANNING SOURCE WITH OR WITHOUT ADDITIONAL SOLAR‐SIMULATED UV RADIATION IN HAIRLESS MICE
Authors: Bech‐Thomsen Niels , Wulf Hans Christian
Published: January 2008

Abstract— The carcinogenic and melanogenic effects of a filtered metal halide source (UVASUN) that emits UV radiation in a range from 340 to 400 nm and a bank of Philips TL 09R tubes (TL 09) emitting in a range from 310 to 400 nm were studied in lightly pigmented hairless hr/hr C3H/Tif mice. Both the carcinogenic effect of the two UVA radiation sources alone and in combination with a UV source, consisting of one Philips TL 12 and five Bellarium‐S SA‐1–12 tubes emitting radiation somewhat similar to the UV part of the solar spectrum (SOLAR UV), were investigated. Finally, the melanogenic effect of exposure to the two UVA sources were studied. The mice were exposed to the UVA sources 30 min/ day, 5 days/week, in equal erythemogenic doses, calculated by using the Commission Internationale de 1'Eclairage human erythema action spectrum. Equal erythemogenic doses of TL 09 and UVASUN induced the same degree of skin pigmentation, but skin tumor development was enhanced in mice exposed to TL 09 compared with UVASUN (P < 0.0005). For all but one tumor, endpoint pretreatment with TL 09 or UVASUN for 91 days did not influence tumor development during subsequent exposure to SOLAR UV radiation 10 min/day, 4 days/week. Exposure to the two UVA radiation sources after 91 days of SOLAR UV exposure significantly enhanced skin tumor development. Overall, the data on the interaction between exposure to the UVA sources and SOLAR UV indicated that the risk of SOLAR UV‐induced carcinogenesis was independent of the type of prior‐UVA exposure and post‐UVA exposure.
Confocal Fluorescence Lifetime Imaging of Chlorophyll Molecules in Polymer Matrices
Authors: Sanders R. , van Zandvoort M. A. M. J. , Draaijer A. , Levine Y. K. , Gerritsen H. C.
Published: January 2008

Abstract—Confocal fluorescence lifetime imaging has been used to establish the microscopic disposition of chlorophyll molecules in polymer matrices. This study provides a direct test of models proposed on the basis of fluorescence measurements on bulk Alms. We show that whereas chlorophyllbmolecules are uniformly distributed in nitrocellulose matrices, they form pocket‐like structures in polyvinyl alcohol matrices. The shape of the structures, seen as bright fluorescent spots on a uniform background, is modified on stretching the polyvinyl alcohol matrix.
Separation, Identification and Determination of Luciferin in the Iranian Firefly, Lampyris turkestanicus by HPLC and Spectroscopic Methods
Authors: Hadj‐Mohammadi M. R. , Chaichi M. J.
Published: January 2008

Abstract— Iranian firefly larvae, Lampyris turkestanicus collected from north of Iran and their luciferin were analyzed by HPLC, TLC, MS and spectroscopic Fourier transform ([FT]‐IR, FT‐NMR, UV and fluorescence) methods. The results showed that luciferin in L. turkestanicus lanterns was the same as in the American firefly, Photinus pyralis and synthetic D‐luciferin.
Decarboxylation of lndole‐3‐Acetic Acid and Inhibition of Growth inAvena sativaSeedlings by Plant‐Derived Photosensitizers*
Authors: Brennan Thomas M.
Published: January 2008

Abstract—A number of plant phototoxins, when supplemented with UVA (320–400 nm) radiation, are capable of sensitizing the decomposition of indole‐3‐acetic acid (IAA), as measured by release of14CO2from carboxyl‐labeled IAA. Alpha‐terthienyl (αT) and harmine caused significant rates of IAA decarboxylation at concentrations as low as 1 nMand were approximately 80% as effective as riboflavin and flavin mononucleotide. Partial inhibition by sodium azide indicates that the aT‐induced decarboxylation of IAA is predominately, but not entirely, a type II reaction mediated by singlet oxygen. Based on changes in UV ab sorption spectra, it appears that the hormones gibberellic acid, abscisic acid and 6‐benzylaminopurine (a cytokinin) are less susceptible to photosensitized decomposition than is IAA. Alpha‐terthienyl plus UVA also inhibited elongation growth and reduced endogenous IAA levels inAvena sativaL. coleoptile sections and promoted senescence in intactAvenaseedlings. These results confirm the allelopathic potential of plant photosensitizers such as αT and indicate that the phytohormone IAA may represent an additional target for the action of photosensitizers.
Apoptosis or Necrosis Following Photofrin® Photosensitization: Influence of the Incubation Protocol
Authors: Dellinger M.
Published: January 2008

Photosensitization using the tumor‐localizing porphyrin Photofrin® induces cell death bothin vitroandin vivo, but the mechanism of cell death is not well understood. Cell lysis (necrosis) and apoptosis have both been observed. The latter seems restricted mainly to lymphoma and epithelial cell lines. To check the influence of the incubation protocol on the cell death mechanism, CV‐1 cells were loaded with Photofrin using two different protocols. In both protocols, photosensitized CV‐1 cells underwent severe morphological changes before cell death. Many cells treated with protocol 1 (24 h with 1 μ g/mL of Photofrin in culture medium) underwent apoptosis, as demonstrated by plasma membrane blebbing and fragmentation into vesicles, condensation of the chromatin and fragmentation of the nucleus with oligonucleosomic degradation of the DNA. In contrast, cells treated with protocol 2 (1 h with 10 μg/mL of Photofrin in phosphatebuffered saline) lysed instead of fragmented, without oligonucleosomic degradation of the DNA. This type of cell death looks much like necrosis. However, early morphological changes suggest that it is, in fact, apoptosis stopped by plasma membrane leakage. It is concluded that apoptosis is primarily induced in CV‐1 cells but may be arrested by membrane lysis, depending on the incubation protocol.
Sunscreens Protect from UV‐Promoted Squamous Cell Carcinoma in Mice Chronically Irradiated with Doses of UV Radiation Insufficient to Cause Edema
Authors: Bestak Rosa , Halliday Gary M.
Published: January 2008

Previously we reported that the broad‐spectrum sunscreen microfine titanium dioxide (MTD) could completely protect C3H/HeJ mice from UV radiation‐induced immunosuppression to a contact sensitizer. In contrast, 2‐ethylhexyl p‐methoxycinnamate (2‐EHMC), a UVB‐absorbing sunscreen, only partially protected the skin immune system. In this study we investigated further this differential protection of the skin immune system by comparing the ability of 2‐EHMC and MTD to protect these mice from the promotion phase of tumorigenesis. The mice were initiated using a single subcarcinogenic dose of 7,12‐dimethylbenz(a)anthracene (DMBA) followed by promotion with chronic low‐dose solar‐simulated UV radiation for 32 weeks. We used doses of UV insufficient to cause edema in order to simulate daily human exposure to solar UV radiation. Mice were observed for the appearance of squamous cell carcinomas for 48 weeks. The DMBA‐initiation alone and DMBA‐initiated, sunscreen‐treated groups did not develop tumors. Ultraviolet alone induced the appearance of tumors in 46% of mice at week 48 and therefore some tumors were initiated by UV. Initiation with DMBA prior to UV irradiation enhanced tumorigenesis such that 87% of mice at week 48 had tumors. Both 2‐EHMC and MTD completely protected these mice from UV‐induced promotion as well as from complete carcinogenesis despite the different UV‐absorption spectra of the sunscreens and their differential abilities to protect from UV‐induced immunosuppression. Furthermore, we have shown that, if UV exposure is not increased to compensate for tolerance to edema, protection from tumorigenesis is afforded by sunscreens.
Protective Effect of Magnesium‐L‐Ascorbyl‐2 Phosphate Against Skin Damage Induced by UVB Irradiation
Authors: Kobayashi* Shizuko , Takehana Makoto , Itoh Shinobu , Ogata Eiichi
Published: January 2008

The protective effect of magnesium‐L‐ascorbyl‐2‐phosphate (MAP) on cutaneous photodamage such as lipid peroxidation and inflammation induced by ultraviolet B (UVB) exposure (290–320nm, max. 312 nm) was investigated using hairless mice. When MAP was administered intraperitoneally to mice at a dose of 100 mg of ascorbic acid (AS) per kg body weight base immediately before irradiation (15 kJ/m2), the expected increases in thiobarbituric acid reactive substance (TBARS) formation in skin and serum sialic acid, indices of lipid peroxidation and inflammatory reaction, respectively, were significantly reduced. However, the expected decrease in the level of cutaneous AS was unchanged. Similar results were observed for animals given 100 mg of AS‐Na per kg body weight before UVB irradiation. When MAP was administered intracutaneously immediately before irradiation, the expected UVB‐induced increases in TBARS and sialic acid were again significantly prevented. Ascorbic acid‐Na had a less protective effect than intracutaneous MAP administration. The cutaneous AS level was significantly higher in the MAP‐treated mice than in the controls, and the UVB‐induced decrease in tissue AS was prevented by intracutaneous MAP administration. These results suggest that MAP protects against UVB irradiation‐induced lipid peroxidation and inflammation in cutaneous tissue, regardless of the drug administration route. We found, in an in vitro experiment, that MAP was converted to AS as it crossed the epidermis, but that AS‐Na did not pass through the epidermis. Furthermore, MAP was also converted to AS in serum. These results suggest that the protective effect of MAP on UVB‐induced cutaneous damage is due to conversion of MAP to AS.
Does Exposure to UV Radiation Induce a Shift to a Th‐2‐like Immune Reaction?
Authors: Ullrich Stephen E.
Published: January 2008

In addition to being the primary cause of skin cancer, UV radiation is immune suppressive and there appears to be a link between the ability of UV to suppress the immune response and induce skin cancer. Cytokines made by UV‐irradlated keratinocytes play an essential role in activating immune suppression. In particular, we have found that keratinocyte‐derlved interleukin (IL)‐10 is responsible for the systemic impairment of antigenpresenting cell function and the UV‐induced suppression of delayed‐type hypersensitivity (DTH). Antigen presentation by splenic adherent cells isolated from UV‐irradiated mice to T helper‐1 type T (Th1) cells is suppressed, whereas antigen presentation to T helper‐2 type T (Th2) cells is enhanced. The enhanced antigen presentation to Th2 cells and the impaired presentation to Th1 cells can be reversed in vivo by injecting the UV‐irradiated mice with monoclonal anti‐IL‐10 antibody. Furthermore, immune suppression can be transferred from UV‐irradiated mice to normal recipients by adoptive transfer of T cells. Injecting the recipient mice with anti‐IL‐4 or anti‐IL‐10 prevents the transfer of immune suppression, suggesting the suppressor cells are Th2 cells. In addition, injecting UV‐irradiated mice with IL‐12, a cytokine that has been shown to be the primary inducer of Th1 cells, and one that prevents the differentiation of Th2 cells in vivo, reverses UV‐induced immune suppression. These findings support the hypothesis that UV exposure activates IL‐10 secretion, which depresses the function of Th1 cells, while enhancing the activity of Th2 cells.
Evaluation of an Economical Sunlamp that Emits a Near Solar UV Power Spectrum for Conducting Photoimmunological and Sunscreen Immune Protection Studies
Authors: Beasley Donathan G. , Beard John , Stanfield Joseph W. , Roberts Lee K.
Published: January 2008

Expense and inconvenience have restricted the use of the filtered xenon are lamp (solar simulator) as a UV source for conducting large‐scale animal studies. Because sunscreen immunoprotective levels are significantly affected by the UV power spectrum of the source it is imperative that a solar simulating source be used for accurate measurements of sunscreen protection levels that are relevant to human UV exposures from sunlight. However, relatively inexpensive sunlamps, e. g. the UVA‐340, that emit a UV power spectrum similar to that of a solar simulator are available. Unlike FS‐type UVB sunlamps, which have a significant amount of effective immunosuppressive nonsolar UV energy at wavelengths below 295 nm, the immunosuppression effectiveness spectrum of UVA‐340 sunlamps was nearly identical to that of a solar simulator. The purpose of this study was to evaluate this sunlamp for conducting photoimmunological and sunscreen immune protection studies. Groups of C3H mice were exposed to a range of UVA‐340 sunlamp doses (0.25 KJ/m2 to 20.0 KJ/m2) to establish a dose‐response curve and determine the minimum immune suppression dose (MISD) for induction of local‐type suppression of contact hypersensitivity (CH). The MISD, defined as the lowest UV dose given to produce ∼50% suppression of the CH response in mice, was determined to be 1.0 kJ/m2 for UVA‐340 sunlamps. Immune protection tests on four marketed sunscreen lotions (sun protection factors [SPF] 4, 8, 15 and 30) were then conducted with UVA‐340 sunlamps using MISD as the endpoint. The immune protection factors for these sunscreens were equivalent to the level of protection predicated by their labeled SPF. These results are similar to those we have previously obtained using a solar simulator. We conclude from these data that the immunosuppressive effects of UVA‐340 sunlamps are similar to those of a solar simulator; however, further studies are needed to determine if UVA‐340, or similar, sunlamps are a viable alternative to the solar simulator for conducting large‐scale animal experiments that require a relevant UV solar spectrum.
Ultraviolet B Radiation Increases Hairless Mouse Mast Cells in A Dose‐Dependent Manner and Alters Distribution of UV‐lnduced Mast Cell Growth Factor
Authors: Kligman Lorraine H. , Murphy George F.
Published: January 2008

Abstract— In studies of the effects of chronic UVB irradiation on dermal connective tissue in the hairless mouse, we observed that the number and size of mast cells was increased. Because mast cells are known to be associated with connective tissue remodeling, we examined and quantified the effect of increasing UVB (290‐320 nm) doses on this cell. Groups of mice were exposed to filtered FS‐40 Westinghouse lamps (290‐400 nm: peak irradiance 313 nm) for 1‐5 minimal erythema doses (MED) thrice weekly for 10 weeks. Appropriate controls were included. Biopsies, processed for light microscopy, were stained with toluidine blue. Mast cells were counted in 15 high‐magnification fields per specimen with upper and lower dermis scored separately. Significant increases in large densely granular mast cells occurred at 2 MED in the lower dermis, in association with a UVB‐exacerbated granulomatous reaction. In the upper dermis, mast cells were significantly increased with 3 MED. These findings suggest that mast cells may play a dual role in UV‐irradiated skin with those in the lower dermis related to inflammation processes and those in the upper dermis involved in connective tissue modeling. To gain understanding of the mechanism of mast cell recruitment and maturation, we examined the effect of UVB on mast cell growth factor expression. This was enhanced in the epidermis by UVB, with a shift from cytoplasmic staining to membrane‐associated or intercellular staining at 2 MED and higher. Dermal dendritic and mononuclear cells also showed increased reactivity.