bluuebunny/crossref_metadata_2025 huggingface dataset:
CHLOROPHYLLS IN POLYMERS. II. PHEOPHYTINaIN POLYMERS and THE INFLUENCE OF STRETCHING ON THE STATE OF CHLOROPHYLLS IN ANHYDROUS POLYMER FILMS
Authors: Wróbei D. , Zandvoort M. A. M. J. van , Lettinga P. , Ginkel G. van , Levine Y. K.
Published: January 2008

Abstract—Inthe first part of this study the spectral properties of pheophytinain rigid, unstretched anhydrous polyvinyl alcohol and nitrocellulose films have been studied in order to establish the influence of the central magnesium atom on the state of chlorophylls in polymer systems. The absorption, fluorescence, excitation spectra and fluorescence intensity decays in the polymer films and in the solutions from which they are cast are reported. It is shown that pheophytinaaggregate formation is influenced by the nature of the polymer system. An aggregate of pheophytinais found in polyvinyl alcohol films over a wide concentration range. On the other hand, pheophytinaexists in the monomeric form in unstretched nitrocellulose films at concentrations below 6 × 10‐6mol/g.

In the second part of this work, the influence of stretching of the films on the state and distribution of embedded chlorophyll pigments, is described. Here we show that the chlorophyllamolecules are found to undertake a heterogenous distribution in polyvinylalcohol matrices, since stretching partially disrupts the pocket‐like structures present in unstretched films. In contrast, chlorophyllaand pheophytinamolecules can be embedded in a monomeric state in nitrocellulose matrices and moreover they remain homogeneously distributed upon stretching. The chlorophyll/nitrocellulose system is concluded to be a useful model system for studies of donor‐donor energy transfer processes.
THE ORIENTATION OF THE TRANSITION DIPOLE MOMENTS OF CHLOROPHYLLaand PHEOPHYTIN a IN THEIR MOLECULAR FRAME
Authors: Zandvoort M. A. M. J. van , Wróbel D. , Lettinga P. , Ginkel G.van , Levine Y. K.
Published: January 2008

Abstract—In this paper we describe the determination of the orientation of the absorption and emission transition dipoles of chlorophyllaand pheophytinain their molecular frame. For this purpose we have embedded the pigments in anhydrous nitrocellulose films with a concentration of 2 × 10‐7mol/g. We have shown previously that under these conditions the pigments are in a purely monomeric state, are distributed uniformly both before and after stretching and that no intermolecular energy transfer among the molecules takes place.

Using a combination of steady‐state anisotropy experiments on unstretched films and angle‐resolved fluorescence depolarization measurements on stretched films, we obtain the orientation of the transition dipole moments of both pigments in their molecular frame and the orientational distribution function of the molecules relative to the stretching direction of the film.

The steady‐state anisotropy measurements indicate that chlorophyllahas two distinct emission dipole moments and that excitation in the Soret‐region results in simultaneous excitation of two or more absorption transition dipole moments. On the other hand, excitation in the QY‐band involves only a single dipole moment. The directions of the transition dipole moments in the molecular frame are obtained from the angle‐resolved measurements. Pheophytinaalso exhibits two emission dipole moments, but the angle between them is much smaller than that between the corresponding dipoles for chlorophylla. As a consequence the dipole moments contributing to the Soret‐region could not be resolved and only an effective absorption transition dipole moment in the Soret‐region is extracted.
LOW‐TEMPERATURE TRAPPING OF EARLY PHOTOINTERMEDIATES OF α‐ISORHODOPSIN
Authors: Mah T. L. , Lewis J. W. , Sheves M. , Ottolenghi M. , Kliger D. S.
Published: January 2008

Abstract—a‐Isorhodopsin, an artificial visual pigment with a 9‐cis‐4,5‐dehydro‐5,6‐dihydro(a)retinal chromophore, was photolyzed at low temperatures and absorption difference spectra were collected as the sample was warmed. A bathorhodopsin (Batho)‐like intermediate absorbing atca495 nm was detected below 55 K, a blue‐shifted intermediate (BSI)‐like intermediate absorbing atca453 nm was observed when the temperature was raised to 60 K and a lumirhodopsin (Lumi)‐like intermediate absorbing atca470 nm was found when the sample was warmed to 115 K. Photointermediates from this pigment were compared to those of native rhodopsin and 5,6‐dihydroisorhodopsin. As in native rho‐dopsin, Batho is the first intermediate detected in a‐isorhodopsin, though unlike native rhodopsin at low temperatures BSI is observed prior to Lumi formation. a‐Isorhodopsin behaves similarly to 5,6‐dihydroisorhodopsin, with the same early intermediates observed in both artificial visual pigments lacking the C5‐C6double bond. The transition temperature for BSI formation is higher in a‐isorhodopsin, suggesting an interaction involving the chromophore ring in BSI formation. The transition temperature for Lumi formation is similar for these two pigments as well as for native rhodopsin, suggesting comparable changes in the protein environment in that transition.
SINGLET OXYGEN LUMINESCENCE SPECTRA: A COMPARISON OF INTERFEROMETER‐ AND GRATING‐BASED SPECTROMETERS
Authors: Wessels Jurina M. , Charlesworth Paul , Rodgersf Michael A. J.
Published: January 2008

Abstract— The current trend in methodology for determining IR and near‐IR absorption spectra is to employ interferometer‐based instruments to replace the monochromator‐based devices used heretofore. As a dispersion element, the interferometer offers major improvements in spectral resolution (Connes advantage), light throughput (Jacquinot advantage) and data acquisition through multiplexing (Felgett advantage). We have compared signal‐to‐noise (S/N) ratios of grating‐based and interferometer‐based instruments for making spectral determinations of near‐IR luminescence. Our results show that under identical excitation and detector conditions the interferometer instrument easily outperforms the grating, giving a 10‐fold improvement in S/N at high signal amplitude (A488nm= 0.97) and a 20‐fold improvement when the signal amplitude is low (A488nm= 0.06). Although some spectral resolution is sacrificed when scan times on the Fourier transform (FT)IR are significantly shortened, the S/N ratio was found only to decrease by a factor of 2 for a 10‐fold decrease in scan time. This adds to the advantages of the FT1R technique because the S/N will thus improve for the same total acquisition time.
EVALUATION OF NEW BENZOPORPHYRIN DERIVATIVES WITH ENHANCED PDT EFFICACY*
Authors: Pandeyi Ravindra K. , Potter William R. , Meunier Isabelle , Sumlin Adam B. , Smith Kevin M.
Published: January 2008

Abstract— A first report on the biological evaluation of a series of isomerically pure benzoporphyrin derivatives (cis‐ and frarcs‐isomers) as methyl esters is described. In preliminary in vivo studies, the n‐bexyl ether analogues of both cis‐ and trans‐isomers of benzoporphyrin derivatives were found to be more active than the industrially prepared benzoporphyrin derivative, a mixture of monocarboxylic acids (BPDMA, Quadralogic Technologies, Vancouver). Further studies with 4‐de‐vinyl‐4‐(I‐hexyloxyethyl) benzoporphyrin derivative showed that, like BPDMA, it had reduced residual skin phototoxicity compared in mice with Photofrin®. The uptake and clearance characteristics of BPDMA were also compared with the 4‐(1‐hexyloxyethyl)‐derivative by in vivo reflection spectroscopy.
OZONE EXPOSURE DECREASES UVB SENSITIVITY IN A UVB‐SENSITIVE FLAVONOID MUTANT OF Arabidopsis
Authors: Rao Mulpuri V. , Ormrod D. P.
Published: January 2008

Abstract— The impact of sequential exposure to ozone (O3) and UVB (290–320 nm) was studied using two genotypes of Arabidopsis thaliana differing in UVB sensitivity. The negative impact of UVB on dry matter production and photosynthetic pigments was absent in the ecotype Landsberg erecta (LER), while the negative impact of UVB was more pronounced when LER plants preexposed to O3 were irradiated with UVB. However, the growth of tt5 plants (a mutant virtually incapable of synthesizing flavonoids) was significantly affected by the UVB exposures, while the impact of UVB was significantly counteracted when tt5 plants pre‐exposed to O3 were irradiated with UVB. These results suggest that pre‐exposure to O3 decreased sensitivity of tt5 but increased sensitivity of LER to UVB. Concentrations of UV‐absorptive compounds were almost the same in plants exposed to UVB alone or sequentially to O3 and UVB. Exposures of LER and tt5 to UVB enhanced both ascorbic acid and glutathione as well as their redox state compared to control plants. Pre‐exposure to O3 enhanced the total ascorbic acid and glutathione as well as the redox state of ascorbate and glutathione in tt5 but decreased the redox state in LER. Irradiation of plants pre‐exposed to O3 with UVB enhanced the redox state of ascorbate and glutathione slightly in tt5 but decreased it further in LER. The high redox state of ascorbate and glutathione in tt5 pre‐exposed to O3 would have protected plants from UVB and decreased their sensitivity to UVB in spite of their inability to synthesize flavonoids. The decreased redox state in O3‐exposed LER plants would have enhanced their sensitivity to UVB. These results suggest that O3 influences plant response to UVB in environments enriched with both O3 and UVB.
Likely Mechanism of the Hydrophobic Sensitizer Accumulation in Tumor Cells: Mathematical Models
Authors: Stepanova N. V. , Zhorina L. V. , Chernyaeva E. B.
Published: January 2008

Abstract—Two mathematical models describing the accumulation kinetics of hydrophobic sensitizers in the cell membrane and cytoplasm and the influence of intra‐ and extracellular pH values on intracellular accumulation are suggested. Numerical calculations were done for hematopor‐phyrin (Hp) as an example. When compared with the experimental data, both models gave satisfactory results describing the accumulation time and level. A biphasic character of the sensitizer accumulation process was obtained as a result of the difference in the accumulation times characteristic for the plasma membrane and cytoplasm. The ratio of characteristic times was determined by the ratio of membrane and cytoplasm volumes and a “water‐lipid” partition coefficient reflecting the height of the membrane barrier for the sensitizer penetration through the plasma membrane lipid bilayer. Generally, the enhanced uptake of Hp molecules by cells was obtained when both extracellular and intracellular pH (pH,.,) values were lower than the physiological ones. A “selectivity” of accumulation was achieved in “tumor” cells for reasonable pHinvalues (about 6.0). But when compared with the experimental data, the value of selectivity was not high enough, indicating that, though the pH value is an important factor in Hp intracellular accumulation, it might be less important as a factor for selectivity of Hp accumulation in tumors.
Mechanism of UVB‐Induced Suppression of the Immune Response to Mycobacterium bovis Bacillus Calmette‐Guerin: Role of Cytokines on Macrophage Function
Authors: Jeevan Amminikutty , Ullrich Stephen E. , Gracia Maria De , Shah Rupa , Sun Yan
Published: January 2008

Previously we demonstrated that treatment of mice with either UVB radiation or supernatants derived from UVB‐irradiated PAM 212 keratinocytes decreased the induction of the delayed‐type hypersensitivity (DTH) response to Mycobacterium bovis bacillus Calmette‐Guerin (BCG), impaired the clearance of bacteria from their lymphoid organs and also altered macrophage functions. In order to characterize the cytokines involved in these phenomena, UV‐irradiated mice were injected with antibodies to interleukin‐10 (IL‐10), transforming growth factor‐β1 (TGF‐β1), or tumor necrosis factor‐α (TNF‐α). Injection of UVB‐irradiated mice with anti‐IL‐10 immediately after UV irradiation restored the DTH response and reversed the UV‐induced inhibition of bacterial clearance. Injection of UV‐irradiated mice with anti‐TGF‐β only partially restored the DTH response although it allowed a better clearance of BCG than injection of mice with the control antibody. In contrast, injection of anti‐TNF‐α did not affect the UVB‐induced suppression of DTH or impaired bacterial clearance. Similarly, the ability of macrophages to phagocytose BCG and kill the intracellular organisms was restored to almost normal levels after injecting UV‐irradiated mice with antibodies specific for IL‐10 or TGF‐β. Injection of mice with either recombinant IL‐10 or TGF‐β mimicked the effect of whole‐body UV irradiation on immune function. These results suggest that IL‐10 has a major role in UV‐induced suppression of both DTH to BCG and impairment in the clearance of bacteria and that TGF‐β has a more significant role in blocking bacterial clearance. Furthermore, these cytokines seem to modulate immune responses by altering macrophage functions in UVB‐irradiated mice.
Spectroscopic and Biological Testing of Photobleaching of Porphyrins in Solutions*
Authors: Bezdetnaya L. , Zeghari N. , Belitchenko I. , Barberl‐Heyob M. , Merlin J. ‐L. , Potapenko A. , Gulllemin F.
Published: January 2008

The photobleaching of protoporphyrin IX (PP IX) and hematoporphyrin derivative (HpD) solutions was followed using three different methods: spectrophotometry, fluorometry and photodynamically induced cytotoxicity. The latter entails photoirradiation of HT29 human colon adenocarcinoma cells in the presence of preirradiated solutions of HpD and PP IX (λ 415 nm). The highest cytotoxicity was observed in the presence of unirradiated dye and decreased with the time of preirradiation. This decay in photocytotoxicity was further used to determine the porphyrin photobleaching kinetics in solution. For both sensitizers, quantum yields of photobleaching obtained by matching fluoresence were higher than that obtained from absorbance measurements (10 and 11 times for HpD and PP IX, respectively). This difference reflects preferential photobleaching of photolabile monomeric forms compared to aggregates. The highest quantum yield was obtained in the biological test (decay in cytotoxicity) which was 14 times higher for HpD and 30 times higher for PP IX than the quantum yield obtained from absorbance measurements. The absence of correlation between biological and fluorescence measurements has to be taken into account in the in vivo situation. Dark storage of preirradiated sensitizers (37°C, 24 h) completely restored photocytotoxity for PP IX but only partially for HpD, whereas fluorescence patterns were partially restored for both sensitizers.
Depopulation of Highly Excited Singlet States of DNA Model Compounds: Quantum Yields of 193 and 245 nm Photoproducts of Pyrimidine Monomers and Dinucleoside Monophosphates
Authors: Gurzadyan Gagik G. , Görner Helmut
Published: January 2008

Abstract—Formation of uracil and orotic acid photodimers, uridine and 5′‐UMP photohydrates, TpT photodimers and (6‐4)photoproducts, dCpT photohydrates and (6‐4)photo‐products and UpU, CpC and CpU photohydrates were studied in neutral deoxygenated aqueous solution at room temperature upon irradiation at either 193 or 254 nm. The photoproducts were identified and quantified and the contribution from photoionization to substrate decomposition, using λirr= 193 nm, was separated. The ratio of the quantum yields of respective stable products,η=φ193/φ254is indicative of the yield of internal conversion from the second to the first excited singlet state, S2→ S1. For the observed photodimers η decreases from 0.94 for uracil to 0.7 for TpT and further to 0.55 for orotic acid. For the (6‐4)photoproducts of TpT and dCpT T| = 0.5‐0.8 and for the photohydrates in the cases of UpU, CpC, CpU and dCpT TJ ranges from 0.55 to 1.
Singlet Excited States and the Light‐Harvesting Function of Carotenoids in Bacterial Photosynthesis
Authors: Koyama Yasushi , Kuki Michitaka , Andersson Per Ola , Gillbro Tomas
Published: January 2008

Abstract— The recent results of stationary‐state and time‐resolved absorption, fluorescence and Raman spectroscopies of some typical carotenoids are summarized. Theoretical analyses of carotenoid singlet states and of carotenoid‐to‐bacteriochlorophyll singlet‐energy transfer are also included. On the bases of the energies, the lifetimes and other properties of singlet excited states of the carotenoids in solution and bound to the light‐harvesting complexes, the energetics and the dynamics of the light‐harvesting function in purple photosynthetic bacteria are discussed with emphasis on the 2Ag and Bu+ states.
UVA‐Potentiated Damage to Calf Thymus DNA by Fenton Reaction System and Protection by para‐Aminobenzoic Acid
Authors: Shih Ming‐Kuei , Hu Miao‐Lin
Published: January 2008

Abstract— Calf thymus DNA was irradiated with low‐intensity UVA (main output at 365 nm, 2 mW cm−2 or 36 kj m 2 for 30 min), and the role of metal ions, hydrogen peroxide and reactive oxygen species (ROS) was examined. DNA damage was measured as thiobarbituric acid‐reactive substances (possibly from degradation of deoxyribose) and as changes in ethidium bromide‐DNA fluorescence due to unwinding from strand breaks. Under the present experimental conditions, UVA alone or in the presence of H202 had no effect on DNA but slightly enhanced the damage by iron/EDTA. Ultraviolet A strongly enhanced DNA damage (ca four‐ to five‐fold) by the Fenton reaction system (50 μM Fe2+/100 μM EDTA + 0.5 mM H202). The results suggest that the Fenton reaction system was “photosensitized” to damage DNA by low‐intensity UVA radiation. The enhanced damage by UVA was attributed in part to the reduction of Fe3+ to Fe2+. Ultraviolet A had no effect when iron (ferric or ferrous) ions were replaced by Cu2+, Zn2+, Mn2+ or Cd2+. The ROS involved in the UVA‐enhanced damage to DNA by the Fenton reagents were OH and, to a lesser extent, superoxide anions. The UVA‐potentiated DNA damage by the Fenton reaction system was then used to examine the protective effect of para‐aminobenzoate (PABA), a UVB‐absorbing sunscreen that protects against photocarcinogenesis in hairless mice. The results show that PABA and mannitol dose‐dependently inhibited the damage with concentrations required for 50% inhibition at 0.1 mM and 3 mM, respectively. The protection by PABA was attributed to its radical‐scavenging ability because PABA does not absorb light in the UVA region. These findings may be relevant to the biological damage by UVA and suggest that PABA is useful in protection against photocarcinogenesis by wide‐range UV radiation.
Isopimpinellin Is Not Phototoxic in a Chick Skin Assay
Authors: Ivie G. Wayne , Beier Ross C.
Published: January 2008

Abstract—Synthetic isopimpinellin (5,8‐dimethoxypsoralen), confirmed to contain as impurities only trace quantities at most of psoralen, bergapten (5‐methoxypsoralen) and xanthotoxin (8‐methoxypsoralen), is not phototoxic when tested in a chick skin bioassay system. These findings are at variance with earlier studies showing isopimpinellin to be phototoxic against chick skin and support the conclusion that isopimpinellin is photobiologically inactive. As recently proposed by others, the several reports of isopimpinellin photoactivity are most likely attributable to contamination by small amounts of highly active psoralens such as bergapten or xanthotoxin.
Nonmammalian Models for Sunlight Carcinogenesis: Genetic Analysis of Melanoma Formation in Xiphophorus Hybrid Fish
Authors: Nairn Rodney S. , Morizot Donald C. , Kazianis Steven , Woodhead Avril D. , Setlow Richard B.
Published: January 2008

Abstract— Genetic hybrids of Xiphophorus fishes have been used for decades to study heritable melanoma formation. In these models, overexpression of pigmentation patterns from melanin‐producing pigment cells can lead to genetically regulated melanoma formation in backcross hybrids. In the best studied of these models, the Gordon‐Kosswig hybrid melanoma, tumors form spontaneously in all individuals of a subset of backcross hybrids between the platyflsh Xiphophorus maculatus Jp 163 A and the swordtail species Xiphophorus helleri. Backcross hybrids susceptible to melanoma formation inherit a sex‐linked oncogene, Xmrk, associated with the spotted dorsal (Sd) pigment pattern and have lost both copies of an autosomal gene, DIFF, from the X. maculatus parent. Spontaneous melanoma formation conforms to simple, two‐gene Mendelian inheritance in which DIFF behaves as a recessive tumor suppressor gene. Recently, Xiphophorus hybrids in which melanomas can be induced by UV and near‐UV visible light exposure have been described. We report here results of genetic linkage analysis of one of these Xiphophorus light‐inducible hybrid melanoma models, in backcross hybrids between the two platyflsh species X. maculatus Jp 163 B and Xiphophorus couchianus. Our linkage results provide the first estimate of recombination between the tumor suppressor locus, DIFF, and glycerate‐2‐dehydrogenase (GLYDH) in Xiphophorus linkage group V. Also, they demonstrate that DIFF regulates hyperplasia of spotted side (Sp) pigment cells in this hybrid model, analogous to its regulation of hyperplasia of Sd pigment cells in the “classical” Gordon‐Kosswig hybrid. Joint segregation analyses of melanoma‐bearing fish indicate that segregation of DIFF is genetically linked to melanoma induction by 405 nm light in this model but that induction of melanomas by UV wavelengths apparently does not depend on segregation of the DIFF locus.
Structure and Biodistribution Relationships of Photodynamic Sensitizers*
Authors: Boyle Ross W. , Dolphin David
Published: January 2008

Abstract— Photodynamic therapy (PDT) has, during the last quarter century, developed into a fully fledged biomedical field with its own association, the International Photodynamic Association (IPA) and regular conferences devoted solely to this topic. Recent approval of the first PDT sensitizer, Photofrin® (porfimer sodium), by health boards in Canada, Japan, the Netherlands and United States for use against certain types of solid tumors represents, perhaps, the single most significant indicator of the progress of PDT from a laboratory research concept to clinical reality.

The approval of Photofrin® will undoubtedly encourage the accelerated development of second‐generation photo‐sensitizers, which have recently been the subject of intense study. Many of these second‐generation drugs show significant differences, when compared to Photofrin®, in terms of treatment times postinjection, light doses and drug doses required for optimal results. These differences can ultimately be attributed to variations in either the quantum efficiency of the photosensitizer in situ, which is in turn affected by aggregation state, localized concentration of endogenous quenchers and primary photophysics of the dye, or the intratumoral and intracellular localization of the photosensitizer at the time of activation with light. The purpose of this review is to bring together data relating to the biodistribution and pharmacokinetics of second‐generation sensitizers and attempt to correlate this with structural and electronic features of these molecules. As this requires a clear knowledge of photosensitizer structure, only chemically well‐characterized compounds are included, e.g. Photofrin® and crude sulfonated phthal‐ocyanines have been excluded as they are known to be complex mixtures. Nonporphyrin‐based photosensitizers, e.g. rose bengal and the hypericins, have also been omitted to allow meaningful comparisons to be made between different compounds. As the intracellular distribution of photosensitizers to organelles and other subcellular structures can have a large effect on PDT efficacy, a section will be devoted to this topic.
Photophysical Properties of Pyrazinopsoralen, A New Monofunctional Psoralen*
Authors: Han Gyu Seok , Yoo Dong Jin , Kim Sung Ki , Shim Sang Chul , Kang Ho Kwon
Published: January 2008

Abstract—Pyrazinopsoralen (PzPs), a new monofunctional psoralen, has a UV absorption spectrum similar to other psoralens except that it absorbs more strongly in the long‐UVA than 8‐methoxypsoralen. The solvent effects on the UV absorption and fluorescence emission spectra indicate that the lowest excited singlet state is the π,π* state like other psoralen derivatives. It shows a much lower fluorescence quantum yield (0.0008 in ethanol at room temperature) than the other psoralens as expected by the increased proximity effect (vibronic perturbation) due to close1(n,π*) to1(π,π*) states. The fluorescence lifetime was 1.05 ns in methylcyclohexane with a single exponential decay, while more than two components were observed in other solvents with the short‐lived component being the major (>95%). The triplet state of PzPs could not be detected by phosphorescence, laser flash excitation (T‐T absorption) and singlet oxygen formation probably due to very low φisc, or short lifetime of the triplet state (τT) caused by the fast T1→ S0intersystem crossing.
Causes of Cell Death Following Ultraviolet B and C Exposures and the Role of Carotenes
Authors: Cerdá‐Olmedo Enrique , Martín‐Rojas Virginia , Cubero Beatriz
Published: January 2008

Abstract— Ultraviolet B radiation (wavelength 290–310 nm) does not induce any specific lethal effects in the fungus Phy‐comyces blakesleeanus, according to a heterokaryon test that responds to the nature of the lethal damage. This agent is about 10 times less lethal than UVC radiation from germicidal lamps (254 nm), but it kills cells through the same photoreactivable lesions, due to the UV absorption of DNA. Carotenes do not protect Phycomyces against UV damage, either B or C, lethal or not. This was shown by Darwinian competition experiments between strains containing very different carotene concentrations and between strains containing similar concentrations of different carotenes (phytoene, lycopene, β‐car‐otene). A shading effect of carotenes against UV radiation is likely, but it was insignificant under the conditions of the experiments.
Ultraviolet B Wavelength Dependence for the Regulation of Two Major Matrix‐Metalloproteinases and Their Inhibitor TIMP‐1 in Human Dermal Fibroblasts
Authors: Brenneisen Peter , Oh Jinsook , Wlaschek Meinhard , Wenk Jutta , Briviba Karlis , Hommel Christina , Herrmann Gemot , Sies Helmut , Scharffetter‐Kochanek Karin
Published: January 2008

Abstract— The wavelength dependence for the regulation of two major matrix‐metalloproteinases, interstitial collagenase (MMP‐1) and stromelysin‐1 (MMP‐3), and their major inhibitor, tissue inhibitor of metalloproteinases (TIMP‐1), was studied in human dermal fibroblasts in vitro. Monochromatic irradiation at 302, 307, 312 and 317 nm with intensities ranging from 20 to 300 J/m2 increased MMP‐1 and MMP‐3 mRNA steady‐state levels and the secretion of the corresponding proteins up to 4.4‐fold, whereas almost no increase was observed at wavelengths <290 nm. In contrast, the synthesis of TIMP‐1 increased only marginally. This imbalance may contribute to the severe connective tissue damage related to photoaging of the skin. The wavelengths responsible for MMP‐1 and MMP‐3 induction reported here are distinct from the absorption spectrum of DNA and are different from results previously reported in the literature. Importantly, they overlap with wavelengths whose intensity is predicted to increase on the earth's surface upon ozone depletion. Intensities and particular wavelengths used in our studies in vitro can be absorbed readily by fibroblasts within the skin in vivo and, thus, are relevant for risk assessment and development of protective agents.
Photodynamic Therapy with a Diode Laser for Implanted Fibrosarcoma in Mice Employing Mono‐L‐Aspartyl Chlorin E6
Authors: Katsumi Toichiro A. , Aizawa Katsuo , Kuroiwa Yukari , Saito Kouichi , Kurata Yasushi , Li Yoshiteru , Okunaka Tetsuya , Konaka Chimori , Kato Harubumi
Published: January 2008

Abstract— The authors performed photodynamic therapy (PDT), avoiding any hyperthermic effects, using a newly developed diode laser and photosensitizer, mono‐L‐aspar‐tyl chlorin e6 (NPe6), of Meth‐A fibrosarcoma implanted in mice and achieved tumor therapeutic benefit. The photodynamic light treatment was performed 5 h following the photosensitizer administration. With 5.0 mg/kg NPe6 and light doses of 50, 100, 150 and 200 J/cm2, the tumor cure rates were 20, 50, 70 and 90%, respectively. With 100 J/cm2 laser exposure and NPe6 doses of 1.25, 2.5, 5.0, 7.5 and 10.0 mg/kg, the tumor cure rates were 0, 20, 50, 70 and 90%, respectively. A charge‐coupled device (CCD) camera system was employed to measure the NPe6 fluorescence intensity correlating with the residual amount of the photosensitizer at deferent depth from the tumor surface. The ratios of the NPe6 fluorescence intensity at 3 mm from the tumor surface following 50, 100, 150 and 200 J/cm2 laser exposure to no laser exposure were 0.73, 0.36, 0.22 and 0.16, respectively. With samples sectioned at 1 mm depth, after 50 J/cm2 and the same photosensitizer dose (5 mg/kg) this ratio was 0.19. These results suggest that a certain increase in the tumor tissue level of NPe6 and a certain increase of laser light dose reaching deeper layers of tumor caused an increase in percent cure. In addition, the effectiveness of PDT depends on the total laser dose reaching deeper layers of tumors. Furthermore, the effectiveness of PDT tends to correlate with the amount of NPe6 photobleaching by PDT.
Mexoryr SX Protects Against Solar‐Simulated UVR‐lnduced Photocarcinogenesis in Mice
Authors: Fourtanier Anny
Published: January 2008

Abstract— The aim of this study was to determine, for regulatory purposes, the potential of MexoryP SX, a broad UVA absorber that also absorbs to some extent in the UVB, to modify the UV radiation (UVR)‐induced murine skin tumor development and growth. Skh‐hrl mice were exposed to solar‐simulated UVR 5 days per week for 40 weeks. Two control groups were irradiated without topical application, three groups received a sunscreen preparation containing either the UVA absorber, MexoryP SX at 5 or 10% concentration, or a filter that absorbs principally in the UVB, 2‐ethylhexyl‐p‐methoxycinna‐mate (2‐EHMC) at 5% concentration, introduced as a comparator test article. Sunscreen application was performed before UVR exposure 3 days per week and after UVR exposure on the other 2 days (consistent with the design of a standard photocarcinogenesis safety test). Two different weekly UVR doses were administrated: the lower dose was given to one group of unprotected animals, whereas the higher dose was administrated to the other unprotected group and to the three sunscreen‐treated groups. The two UVR control groups demonstrated a UVR‐dependent response for cumulative tumor prevalence, tumor yield and median latent period. Neither concentration of Mexoryl SX increased the probability of tumor development; consistent with the principles for safety testing, this provides evidence in that it is safe for use in sunlight. Although this study was explicitly designed as a safety test, the results also provide some clues about the efficacy of MexoryP SX in decreasing the probability of tumor development. Topical administration of Mexoryl* SX, at both concentrations, resulted in a 6 week delay in the median latent period compared to high UVR controls, whereas 5% 2‐EHMC delayed the median latent periods only by 2 weeks. Tumor prevalence and yield show the same efficacy differences between the two sunscreen ingredients. Tumor protection factors were calculated from these results and found to be equal to 2.4 for the two preparations containing Mexoryl* SX and to 1.3 for the 5% 2‐EHMC preparation.
Photodynamic Therapy of Human Glioma (U87) in the Nude Rat
Authors: Chopp Michael , Madigan Lara , Dereski Mary , Jiang Feng , Li Yi
Published: January 2008

Abstract— We measured the response of normal brain and the human U87 glioma implanted in the brain of rats (n = 65) to photodynamic therapy (PDT) using Photofrin as the sensitizer. Normal brain and U87 tumor implanted within brain of athymic (nude) rats were subjected to PDT (12.5 mg/kg of Photofrin) at increasing optical energy doses (35 J/cm2, 140 J/cm2, 280 J/cm2) of 632 nm light. Photofrin concentration in tumor, brain adjacent to tumor and normal brain were measured in a separate population of rats. Twenty‐four hours after PDT, the brains were removed, sectioned, stained with hematoxylin and eosin (H&E), and the volumes of the PDT‐induced lesion measured. Photofrin concentration in tumor greatly exceeded that of normal brain and brain adjacent to tumor (>20×). Both normal brain and U87 tumor exhibited superficial tissue damage with PDT at 35 J/cm2. However, both normal and tumor‐implanted brain exhibited tissue damage with increasing optical dose. A heterogeneous pattern of pannecrosis along with a uniform volume of pannecrosis was detected in the tumor. In contrast, normal brain exhibited a uniform sharply demarcated volume of necrosis. Our data indicate that the U87 human brain tumor model and the normal brain in the athymic rat are sensitive to PDT and Photofrin with an optical dose‐dependent response to treatment.
Effects of Ultraviolet‐B Exposure on the Resistance to Listeria monocytogenes in the Rat
Authors: Goettsch Wim , Garssen Johan , De Klerk Arja , Herremans Tineke M. P. T. , Dortant Paul , De Gruijl Frank R. , Van Loveren Henk
Published: January 2008

A rat infection model using the bacterial pathogen Listeria monocytogenes was employed to analyze the im‐munosuppressive activity of UVB radiation. Rats were exposed to suberythemal doses of UVB radiation for 5 or 7 consecutive days, using Kromayer or FS40 lamps respectively. Subsequently, the rats were infected subcuta‐neously or intravenously with Listeria. Exposure to UVB resulted in an increased number of bacteria in the spleen 4 days after infection. Listeria‐specific lymphocyte proliferation assays as well as delayed‐type hypersensitivity reactions demonstrated that T cell‐mediated immunity to Listeria was impaired by UVB as measured 4 and 8 days after infection. In addition, UVB exposure decreased phagocytotic activity of peripheral blood macrophages. This study demonstrated that suberythemal doses of UVB radiation caused a delay in the clearance of Listeria bacteria from the spleen of the rats and that this was probably caused by impaired nonspecific phagocytosis of Listeria by macrophages in addition to an impaired activity of Listeria‐specific T cells.
Melanocyte‐stimulating Properties of Secretory Phospholipase A2
Authors: Maeda Kazuhisa , Naganuma Masako
Published: January 2008

Abstract— Phospholipase A2 (PLA2) catalyzes the release of free fatty acids from membrane phospholipids, and its products derived from these fatty acids, such as prostaglandins and leukotrienes, significantly up‐regulate the key mela‐nogenic enzyme, tyrosinase, in melanocytes. This has led to suggestions that PLA2 itself triggers melanin synthesis in melanogenesis following UV irradiation or inflammation.

We have examined the effect of secretory PLA2 (sPLA2) on melanogenesis in cultured human melanocytes. Secretory PLA2 stimulated DNA synthesis and melanin synthesis, and these phenomena were completely inhibited by treatment with a phospholipase inhibitor, p‐bromophenacyl bromide, demonstrating that the catalytic activity of sPLA2 is required for melanogenesis. Secretory PLA2 also stimulated tyrosinase activity, increased the amount of tyrosinase‐related protein‐1 and up‐regulated the expression of both mRNA. These findings suggest that sPLA2 is an important mediator of UV‐induced or postinflammatory pigmentation.
Langmuir‐Blodgett and X‐ray Diffraction Studies of Isolated Photosystem II Reaction Centers in Monolayers and Multilayers: Physical Dimensions of the Complex*
Authors: Uphaus R. A. , Fang J. Y. , Picorel R. , Chumanov G. , Wang J. Y. , Cotton T. M. , Seibert M.
Published: January 2008

Abstract— The photosystem II (PSII) reaction center (RC) is a hydrophobic intrinsic protein complex that drives the water‐oxidation process of photosynthesis. Unlike the bacterial RC complex, an X‐ray crystal structure of the PSII RC is not available. In order to determine the physical dimensions of the isolated PSII RC complex, we applied Langmuir techniques to determine the cross‐sectional area of an isolated RC in a condensed monolayer film. Low‐angle X‐ray diffraction results obtained by examining Langmuir‐Blodgett multilayer films of alternating PSII RC/Cd stearate monolayers were used to determine the length (or height; z‐direction, perpendicular to the plane of the original membrane) of the complex. The values obtained for a PSII RC monomer were 26 nm2and 4.8 nm, respectively, and the structural integrity of the RC in the multilayer film was confirmed by several approaches. Assuming a cylindrical‐type RC structure, the above dimensions lead to a predicted volume of about 125 nm3. This value is very close to the expected volume of 118 nm3, calculated from the known molecular weight and partial specific volume of the PSII RC proteins. This same type of comparison was also made with the Rhodobacter sphaeroides RC based on published data, and we conclude that the PSII RC is much shorter in length and has a more regular solid geometric structure than the bacterial RC. Furthermore, the above dimensions of the PSII RC and those of PSII core (RC plus proximal antenna) proteins protruding outside the plane of the PSII membrane into the lumenal space as imaged by scanning tunneling microscopy (Seibert, Aust. J. PL Physiol. 22,161–166, 1995) fit easily into the known dimensions of the PSII core complex visualized by others as electron‐density projection maps. From this we conclude that the in situ PSII core complex is a dimeric structure containing two copies of the PSII RC.
Suppression of Delayed‐type Hypersensitivity and Hemolysis Induced by Previously Photooxidized Psoralen: Effect of Fluence Rate and Psoralen Concentration
Authors: Kyagova Alia A. , Zhuravel Natalia N. , Malakhov Mikhail V. , Lysenko Eugene P. , Adam Waldemar , Saha‐Moller Chantu R. , Potapenko Alexander Ya.
Published: January 2008

Abstract—The kinetics of the formation of biologically active psoralen photooxidation (POP) products were analyzed by the biological effects produced. Effects of the UV light fluence rate and psoralen concentration during the preir‐radiation were investigated to assess the yield of POP products, which were activein vivo(inducing suppression of delayed‐type hypersensitivity [DTH] reaction to sheep red blood cells) andin vitro(altering the human erythrocyte membrane permeability). It was shown that the reciprocity law of the irradiation fluence rate and time was not valid in the case of POP‐induced hemolysis and DTH suppression. Immunosuppressive POP products were more efficiently formed at low fluence rate (20.8 W/m2), whereas POP hemolysins were more efficiently produced at a high fluence rate (180 W/m2) of UV light. The yield of immunosuppressive POP products was enhanced in dilute psoralen solutions, while the POP hemolysins yield increased with increasing psoralen concentration. A kinetic scheme for psoralen photoproduct formation was proposed. Kinetic analysis showed that a labile intermediate was produced as the result of excitation of psoralen. This intermediate was either converted to a stable immunosuppressive POP product, or two intermediates combined to form a POP hemolysin. It is proposed that PUVA therapy conditions are more favorable for the formation of immunosuppressive rather than membrane‐damaging psoralen photooxidation products.
Distinctive Molecular Abnormalities in Benign and Malignant Skin Lesions: Studies by Raman Spectroscopy
Authors: Gniadecka Monika , Wulf Hans C. , Nielsen Ole F. , Christensen Daniel H. , Hercogova Jana
Published: January 2008

Abstract— Near‐infrared Fourier transform Raman spectroscopy is an analytical, nondestructive technique that provides information about the molecular structure of the investigated sample. The molecular structure of proteins and lipids differs between neoplastic and normal tissues and therefore Raman spectroscopy has been considered promising for the diagnosis of cancer. We aimed to compare the molecular structure of normal skin, benign and malignant skin lesions by the near‐infrared Fourier transform Raman spectroscopy. Biopsies were obtained from the following skin lesions: skin tag, dermatofibroma, seborrhoeic keratosis, actinic keratosis, keratoacan‐thoma, basal cell carcinoma, squamous cell carcinoma, nevus intradermal, nevus compositus, dysplastic nevus and lentigo maligna. Control skin was harvested from the vicinity of these lesions. In the Raman spectra, the secondary structure of the proteins was reflected by the amide vibrations of peptide bonds. The principal lipid vibrations were twisting and wagging (CH2) and CH stretching vibrations. Histologically distinguishable lesions showed specific combinations of band changes indicating alterations in the protein conformation and in the molecular structure of the lipids. Histogenetically related lesions (actinic keratosis and sqamous cell carcinoma) produced similar but not identical patterns of spectral changes. Because the examined skin lesions produced reproducible and unique spectra, we suggest that Raman spectroscopy will be useful for diagnosis of skin lesions.
Photochemistry of Water‐soluble Quinones. Production of a Water‐derived Spin Adduct
Authors: Alegria Antonio E. , Ferrer Amaris , Sepulveda Elsa
Published: January 2008

Abstract— The photolyses of phosphate‐buffered (pH 7) air‐ and nitrogen‐saturated solutions containing the water‐soluble quinones, 1,4‐benzoquinone (BQ), 2‐methyl‐l,4‐ben‐zoquinone (MBQ), sodium 1,4‐naphthoquinones‐sulfonate (NQ2S), 9,10‐anthraquinone‐2‐sulfonate (AQ2S) or 9,10‐anthraquinone‐l,5‐disulfonate (AQDS), and the spin trap 5,5‐dimethylpyrroline‐l‐oxide (DMPO) produce a DMPO‐OH adduct. Electron paramagnetic resonance spectroscopy of the photolyzed samples in 170‐enriched water demonstrates that this adduct derives almost exclusively from water. With the exception of BQ, quantum yields for the formation of DMPO‐OH are larger in air than in nitrogen‐saturated samples, thus supporting the idea of the formation of air‐oxidized intermediates that enhance the DMPO hydroxylation reaction rate. Evidence has been obtained which suggests that BQ and MBQ, but not AQDS, are able to photoox‐idize water, with the consequent production of the free OH radical.
Visualizing Gene Expression in Living Mammals Using a Bioluminescent Reporter
Authors: Contag Christopher H. , Spilman Stanley D. , Contag Pamela R. , Oshiro Masafumi , Eames Brian , Dennery Phyllis , Stevenson David K. , Benaron David A.
Published: January 2008

Abstract— Control of gene expression often involves an interwoven set of regulatory processes. As information regarding regulatory pathways may be lost in ex vivo analyses, we used bioluminescence to monitor gene expression in living mammals. Viral promoters fused to firefly luciferase as transgenes in mice allowed external monitoring of gene expression both superficially and in deep tissues. In vivo bioluminescence was detectable using either intensified or cooled charge‐coupled device cameras, and could be detected following both topical and systemic delivery of substrate. In vivo control of the promoter from the human immunodeficiency virus was demonstrated. As a model for DNA‐based therapies and vaccines, in vivo transfection of a luciferase expression vector (SV‐40 promoter and enhancer controlling expression) was detected. We conclude that gene regulation, DNA delivery and expression can now be noninvasively monitored in living mammals using a luciferase reporter. Thus, real‐time, noninvasive study of gene expression in living animal models for human development and disease is possible.
Identification of Photooxidation Sites in Bovine α‐Crystallin
Authors: Finley Eric L. , Busman Mark , Dillon James , Crouch Rosalie K. , Schey Kevin L.
Published: January 2008

Abstract— Because UV irradiation of proteins can produce reactive oxygen species and exposure to UV light has been implicated in cataractogenesis, the sites of photooxidation of bovine α‐crystallin, a major lens protein with molecular chaperone activity, were identified using tandem mass spectrometry (MS/MS). Bovine α‐crystallin was irradiated with UV light (293 nm) for 1, 4 and 8 h, digested with trypsin and analyzed by matrix‐assisted laser de‐sorption ionization, time‐of‐flight mass spectrometry (MALDI) to identify the oxidized sequences. Tryptic peptides were purified by reverse‐phase HPLC and oxidized peptides were sequenced by MS/MS to determine the sites of oxidation. Tryptophan fluorescence decreased exponentially with increasing time of UV exposure and peptides containing residues 1‐11 of α‐crystallin and 1‐11, 12‐22 and 57‐69 of α‐crystallin were determined to be oxidized by shifts of 16 D or multiples of 16 Da above the mass of the unmodified peptide. The MALDI analysis revealed single oxidation of all four sequences, which increased with increasing time of UV exposure and possible double oxidation of α 12‐22. The specific sites of photooxidation indicate that the N‐terminal regions of α‐and β‐crystallin are exposed to an aqueous environment and are in the vicinity of tryptophan residues from neighboring subunits.
X‐Ray Diffraction Studies of Bacteriorhodopsin. Determination of the Positions of Mercury Label at Several Engineered Cysteine Residues
Authors: Oka Toshihiko , Kamikubo Hironari , Tokunaga Fumio , Lanyi Janos K. , Needleman Richard , Kataoka Mikio
Published: January 2008

Abstract—The single cysteine‐containing bacteriorhodopsin mutants F27C, L100C, T170C, F171C and I222C were labeled withp‐chloromercuribenzoic acid, which specifically reacts with sulfhydryl groups. These cysteines should be located at the cytoplasmic ends of the transmembrane helices A, C, F or G. We determined the positions of the bound mercury atoms by X‐ray diffraction of purple membrane films, with better than 1 Å accuracy. The determined mercury positions were compared with the structural model from cryoelectron microscopy (N. Grigorieff, T. A. Ceska, K. H. Downing, J. M. Baldwin and R. Henderson,J. Mol. Biol259, 393‐421, 1996). Given that the distance between the mercury and the Cα atom of the cysteine in the xy plane must be shorter than 4.5 Å and that the mercury atom is located at the δ position, the positions obtained for the mercury labels agree with their expected positions from the structural model. The present results give a rationale for detecting structural changes upon illumination as shifts occur in the mercury label position.
Photoreception and Phototropism in Phycomyces: Antagonistic Interactions between Far‐UV, Blue, and Red Light
Authors: Galland Paul , Eslava Arturo P. , Alvarez Maria I.
Published: January 2008

Abstract— Phototropism of the sporangiophore of the fungus Phycomyces is mediated by UV and blue light. Classical phototropism action spectra with maxima near 280, 370 and 450 nm indicate a flavin‐like photoreceptor. Blue light mediates positive phototropism while far‐UV light mediates negative phototropism. To better understand the mode of interaction of far‐UV with blue light we performed phototropism experiments in which sporangio‐phores were placed for 4 h between sources of 280 and 454 nm light coming from opposite directions. The fluence rates of the far‐UV were chosen such that unilateral light alone elicited 90° of negative bending. For blue light, moderate fluence rates were applied that elicited about 40° bending. Under conditions of bilateral irradiation the blue light substantially reduced the far‐UV elicited phototropism. In the presence of tonic red light the antagonism between far‐UV and blue light was greatly reduced. Red light, which by itself is phototropically ineffective, also reduced phototropic bending elicited by either far‐UV or blue light. These observations are taken as indications for the existence of a red light‐absorbing intermediate of the blue‐light receptor. Because the far‐UV/ blue‐light antagonism disappeared almost completely in the presence of tonic red light, the antagonism may occur at the level of this receptor intermediate.