bluuebunny/crossref_metadata_2025 huggingface dataset:
EFFECT OF MOLECULAR STRUCTURE ON THE PHOTOPHYSICAL PROPERTIES, THE PHOTOREACTIVITY WITH DNA AND THE PHOTOBIOLOGICAL ACTIVITY OF MONOFUNCTIONAL PYRIDOPSORALENS
Authors: Blaisi J. , Averbeck D. , Moron J. , Bisagni E. , Vignv P.
Published: January 2008

Abstract— 7‐Methyl‐pyrido[4,3‐c]psoralen (2N‐MePyPs) has been synthesized in order to investigate the possible effect of the position of the pyridine‐nitrogen atom on the photoreactivity towards DNA and the photobiological activity of pyridopsoralens, a new family of psoralen derivatives. In comparison to its isomer, 7‐methyl‐pyrido[3,4‐c]psoralen (MePyPs), 2N‐MePyPs shows a 2.5 times lower DNA photobinding capacity. Photobiological experiments with diploid yeast (Saccharomyces cerevisiae) reveal that this compound differs strikingly from its isomer MePyPs. It has only a weak antiproliferative potential and, per unit dose, a lower capacity than MePyPs for the induction of nuclear genotoxic effects. With respect to these latter features, 2N‐MePyPs resembles the monofunctional furocoumarin 3‐CPs.
PHOTO‐PROPERTIES OF A SILICON NAPHTHALOCYANINE: A POTENTIAL PHOTOSENSITIZER FOR PHOTODYNAMIC THERAPY*
Authors: Firey P. A. , Rodgers M. A. J.
Published: January 2008

Abstract— The photoproperties of derivatized silicon naphthalocyanine have been investigated in order to assess its potential as a photosensitizer for photo‐dynamic therapy. Absorption, fluorescence, phosphorescence and triplet absorption spectra have been measured. Oxygen quenching of the triplet state formed singlet oxygen in significant yields.
A COMPARISON OF PHOTO‐KILLING AMONG CAROTENE AND CYTOCHROME c ACCUMULATING STRAINS OF THE SMUT FUNGUS Ustilago violacea AT SPECIFIC WAVELENGTHS FROM 400 TO 650 nm
Authors: WillIII Oscar H. , Jankowski Phillip , Jorve Kara , Kovacs Adrienne , Rossing William , Schneider Peggy , Newland Natalie A.
Published: January 2008

Abstract— Variously pigmented strains of Ustilago violacea were exposed to monochromatic light from 400 to 650 nm in 50‐nm increments to determine which wavelengths were most effective for photo‐killing. In addition, liquid nitrogen temperature absorption spectra were determined for intact cells of the fungal strains. The high cytochrome c containing pink strains 1.C429, AB278a‐1, 1.C425 and 2.C427 were more sensitive to cytochrome absorption wavelengths than were their low cytochrome c counterparts 15.10, 1.C2y, 1.C2w and 1.C427, while the carotene accumulating strains 1.C2y and AB278a‐1 were more resistant to photo‐killing than their carotene lacking counterparts 15.10, 1.C2w, 1.C427 and 1.C429, 1.C415, 2.C428 even at wavelengths not absorbed by carotenes. The results suggest that cytochrome c and other cytochromes are photosensitizers and that carotene‐related protection is through the quenching of the photosensitizers as well as by absorption.
INVESTIGATION OF POWER ABSORPTION BY METHYLENE BLUE IN A LIGHT SCATTERING MEDIUM WITH AN INTERNAL PHOTODYNAMIC ACTINOMETER
Authors: Grossweiner Leonard I. , Messina James W.
Published: January 2008

Abstract— Power absorption by aqueous solutions of methylene blue containing high concentrations of polystyrene microspheres was measured at 650 nm, using the photosensitized inactivation of subtilisin Carlsberg as an internal actinometer. The results were analyzed with the one‐dimensional diffusion approximation for a finite slab. It is shown that the power absorption is determined by two macroscopic parameters, the optical penetration depth and the linear absorption coefficient. The optical penetration depth was determined independently by measuring flux profiles with an inserted fiber‐optic method. The results are in satisfactory agreement with the predictions of the diffusion model, with microsphere diameters from 0.5 to 5 μm and a wide range of scatterer and dye concentrations. The presence of the scatterers diminished the power absorbed by the dye in all cases. The predictions of one‐dimensional diffusion model are compared to Kubelka‐Munk theory, and shown to be equivalent for optically dense systems
RADIOSENSITISING NITROIMIDAZOLE DRUGS: TRIPLET STATE ENERGY AND REACTIVITY
Authors: Kemp Terence J. , Parker Anthony W. , Wardman Peter
Published: January 2008

Abstract— Although the radiosensitising drugs metronidazole 1 and misonidazole 2 neither phosphoresce nor yield triplet‐triplet absorption in the region 350–700 nm, it is, nevertheless, possible to determine their triplet state energies ET by kinetic quenching methods using laser flash photolysis, and also by a steady‐state method due to Ullman depending on sensitisation of a colour reaction. Both approaches give acceptable concordance, with figures of 244±4 kJ mol‐1 for both 1 and 2. These lead to estimates of triplet excited state one‐electron reduction potentials for 1 and 2 in water of 2.04 and 2.14 V vs NHE, enabling an assessment of the possible role of excited 1 and 2 in radiosensitisation.
NON‐CLOTTABLE FIBRINOGEN BY PHOTOOXIDATION IN BLOOD PLASMA
Authors: Yoshimoto Takayuki , Saito Yuji , Inada Yuji
Published: January 2008

Abstract— Bovine blood plasma anticoagulated with acid‐citrate dextrose was irradiated with an incandescent lamp in the presence of methylene blue and oxygen. Thrombin‐induced clotting activity of plasma was rapidly reduced and was lost completely in only 10 min of irradiation. This is due to the very rapid photooxidation of fibrinogen regardless of the presence of other proteins.
SPECTROSCOPIC STUDIES OF CUTANEOUS PHOTOSENSITIZING AGENTS—XL PHOTOLYSIS OF CHLORPROMAZINE METABOLITES: A SPIN‐TRAPPING STUDY
Authors: Li Anson S. W. , Chignell Colin F.
Published: January 2008

Abstract. The photochemistry of chlorpromazine (CPZ) and its metabolites, 7‐hydroxychlorpromazine (7OHCPZ), desmethylchlorpromazine (DCPZ), didesmethylchlorpromazine (DDCPZ) and chlorpromazine sulfoxide (CPZSO) was studied by the spin trapping technique with 2‐methyl‐2‐nitrosopropane and 5,5‐dimethyl‐l‐pyrroline‐N‐oxide. 7‐Hydroxychlorpromazine generated hydroxyl radicals when excited at 330 nm under either anaerobic or aerobic conditions. 7‐Hydroxychlorpromazine, DCPZ and DDCPZ all underwent dechlorination upon photoexcitation which was enhanced in the absence of air. Chlorpromazine sulfoxide did not undergo photodechlorination but instead generated a high yield of the hydroxyl radical. A comparison among CPZ and its derivatives shows that the yield of the photodechlorinated product is directly related to the degree of phototoxicity. This suggests photodechlorination is an important factor in the phototoxicity of CPZ and its metabolites.
EFFECT OF TEMPERATURE ON SULFITE‐MEDIATED DARK REVERSION OF UROCANASE IN Pseudomonas putida
Authors: O'Donnell Peter S. , Hug Daniel H.
Published: January 2008

Abstract. Cultures of Pseudomonas putida produce inactive but photoactivatable urocanase. The ratio of active to inactive urocanase is much lower in cells grown above 30°C than below 30°C. Inactivation results from the addition of sulfite to the tightly but noncovalently bound nicotinamide adenine dinucleotide. Ultraviolet light restores activity by dissociation of the adduct. The Arrhenius plot of the inactivation of purified urocanase by sulfite appeared linear from 22 to 38°C. Urocanase does not have an increased vulnerability to sulfite above 30°C because of a change in the rate‐limiting step or a conformational change of the protein. Cell extracts and growth medium were analyzed for sulfite and sulfite was confirmed by susceptibility to sulfite oxidase. As the growth temperature was raised from 24 to 32°C, intracellular sulfite rose from 270 μM to 400 μM and the ratio of active to inactive urocanase dropped from 11.8 to 1.9. Above 32°C the intracellular sulfite concentration decreased, the sulfite concentration of the growth medium rose sharply, and the ratio of active to inactive urocanase activity fell further. P.‐putida became leaky, at least to sulfite, above 32°C. We conclude that sulfite formation or degradation is altered to produce more sulfite in cultures grown at elevated temperatures resulting in reversion of urocanase to a photoactivatable form.
CHANGES IN THE PROTEIN COMPLEMENT FOLLOWING UV IRRADIATION AND THEIR PHOTOREVERSAL IN SEA URCHIN (Hemicentrotus pulcherrimus) EMBRYOS
Authors: Akimoto Yoshihiro , Shiroya Tsugio
Published: January 2008

Abstract. Ultraviolet (254 nm, 200 J/m2) irradiation of sea urchin (Hemicentrotus pulcherrimus) embryos during the cleavage stage caused inhibition of morphogenesis, that is, pluteus larva formation. Exposure of the embryos to visible light just after UV irradiation caused the complete reversal of the UV effect, that is, UV‐irradiated embryos can be reprogrammed for normal development (photorever‐sal; PR). We used two‐dimensional electrophoresis to determine the patterns of accumulating proteins in normal, UV‐irradiated and photoreversed embryos. Many qualitative and quantitative variations in the accumulating proteins in the UV‐irradiated embryos were demonstrated. When embryos reached the pluteus larva stage at 48 h after fertilization, the amounts of actin and tubulin were less in the UV‐irradiated embryos than in normal embryos. One extracellular protein (mol. wt. 63 k) did not appear in the UV‐irradiated embryos. Most of the UV effect on the protein pattern was photoreversed.
ABSORPTION SPECTRA AND ACID‐BASE DISSOCIATION OF THE 4‐ALKYL DERIVATIVES OF 7‐HYDROXYCOUMARIN IN SELF‐ASSEMBLED SURFACTANT SOLUTION: COMMENTS ON THEIR USE AS ELECTROSTATIC SURFACE POTENTIAL PROBES
Authors: Drummond Calum J. , Grieser Franz
Published: January 2008

Abstract— The absorption spectra of the un‐ionized and ionized forms of 4‐heptadecyl‐7‐hydroxycoumarin (HHC) in aqueous self‐assembled surfactant solution have been investigated. From a comparison with the absorption spectra of 7‐hydroxycoumarin, 7‐hydroxy‐4‐methylcoumarin (MHC) and HHC in neat organic solvents and organic solvent/water mixtures it is shown that the 7‐hydroxycoumarin chromophore of HHC in self‐assembled surfactant solution resides, on average, in an interfacial microenvironment which has a lower effective dielectric constant than that of the bulk aqueous solution. The absorption spectrum of the ionized form of HHC in aggregates of self‐assembled surfactant molecules with cationic quaternary ammonium headgroups is found to be consistent with there being specific molecular interaction between the anionic chromophore and the quaternary ammonium headgroup. pH titrations performed with MHC in pure water and in four molar aqueous solutions of sodium chloride and tetra‐methylammonium chloride indicate that the acid‐base dissociation of HHC in charged micelles and vesicles should not be substantially influenced by any interfacial salt‐effects, and that the acid‐base dissociation of HHC in cationic micelles and vesicles with quaternary ammonium headgroups should not be markedly affected by the specific molecular interaction that exists. Estimates of the electrostatic surface potentials of a number of self‐assembled surfactant aggregates are made by utilising the acid‐base dissociation of HHC and assuming that the nonionic micelles of n‐dodecyl octaoxyethylene glycol monoether (C12E8) can serve as a reference state of zero surface potential. The validity of this assumption in relation to both micelles and vesicles is discussed in detail.
TIME RESOLVED QUENCHING STUDY OF SERINE‐195 LABELED α‐CHYMOTRYPSIN
Authors: Desie G. , Deynse D. Van , Schryver F. C. De
Published: January 2008

Abstract— Pyrenebutylmethylphosphonofiuoridate or pyrenepropylmethylphosphonofluoridate reacts with the serine 195 residue of α‐chymotrypsin to yield a stoichiometric fluorescent derivative. The fluorescence decay of the modified enzyme was studied using a frequency‐doubled, synchronously pumped picosecond rhodamine‐6G laser excitation source with time‐correlated single‐photon‐counting detection. Upon excitation above 330 nm, it could only be described adequately by a triple exponential decaying function. The exact reason for complexity of the emission has not yet been understood. Heterogeneous labeling seems irrelevant. The presence of different enzyme conformations on the single‐photon‐counting time‐scale seems more plausible. The enzyme conformations where the pyrene label is situated close to the side groups of certain residues such as tryptophan and lysine show a much shorter fluorescence decay time resulting in non‐exponential fluorescence behaviour. Dynamic fluorescence quenching experiments indicate that the pyrene label is located in a more polar region of the enzyme characterized by a negative charge. It seems that the pyrene group is too large to fit well in the hydrophobic pocket of the enzyme but is bent more towards the entrance of the cavity which is characterized by a higher polarity. Upon excitation at 296 nm, the excitation energy is transferred from the tryptophan chromophores towards the pyrene label.
PHOTOINDUCED VOLTA POTENTIAL IN A PORPHYRIN MONOLAYER
Authors: Seta Patrick , Bienvenue Elisabeth , D'Epenoux Bertrand , Tenebre Louis , Momenteau Michel
Published: January 2008

Abstract— When spread on an oxidizing aqueous subphase, an amphipathic basket handle zinc porphyrin (P) monolayer gives rise to a photoinduced Volta potential change. This surface photopotential is interpreted on the basis of an interfacial electron transfer in the interphase; upon light excitation, electrons are transferred from the chromophores in the monolayer to electron acceptors diffusing from the subphase. A kinetic model for charge separation and stabilization is proposed to account for the influences of the electron acceptor concentration, the pH of the subphase and the light intensity.
PHOTOISOMERIZATION OF RETINOIC ACID AND ITS PHOTOPROTECTION IN PHYSIOLOGIC‐LIKE SOLUTIONS
Authors: Curley Robert W. , Fowble John W.
Published: January 2008

AbstractThe long wavelength UV‐induced photoisomerization of retinoic acid has been investigated in physiologic‐like solutions. By high‐performance liquid chromatographic analysis seven isomers of the parent molecule were observed at the photostationary state. The structures of these isomers have been determined using high‐field nuclear magnetic resonance spectroscopy. While addition of a non‐ionic detergent had no effect on the retinoic acid photoisomerization, a number of proteins, as well as a phospholipid, completely inhibited this process. Possible reasons for differences in observed isomer distribution relative to earlier studies, as well as for the effects of the photoprotectant compounds, are discussed.
REGENERATION OF BLUE AND PURPLE MEMBRANES FROM DEIONIZED BLEACHED MEMBRANES OF Halobacterium halobium
Authors: Chang C.‐H. , Jonas R. , Govindjee R. , Ebrey T. G.
Published: January 2008

Abstract— Bleached purple membrane normally binds Ca2+ and Mg2+, which can be removed by the divalent cation chelator ethylenediaminetetraacetic acid (EDTA). Regeneration of pigments from EDTA‐treated bleached membrane (apomembrane) and retinal leads to the formation of blue membrane at pH 4.8, and purple membrane at neutral pH. The pigments take much longer to regenerate than with un‐deionized apoprotein. Adding back cations to the deionized apomembrane only partially speeds up the regeneration process. Like native purple membrane, the regenerated purple membrane also undergoes a photocycle and shows a light‐induced proton release and uptake, although with much slower kinetics than the native species. Thus, cations control the kinetics of pigment regeneration, and also some aspects of the pigment's conformation which controls the photocycle kinetics. The removal and replacement of the cations is not completely reversible, suggesting the cations are not merely bound in the double layer.
PHOTOREACTIVATION OF Halobacterium halobium: ACTION SPECTRUM AND ROLE OF PIGMENTATION
Authors: Iwasa Tatsuo , Tokutomi Satoru , Tokunaga Fumio
Published: January 2008

Abstract— An action spectrum for photoreactivation was measured with Halobacterium halobium R1m1 to prove a role of carotenoid pigments in photoreactivation of the bacteria. The action spectrum obtained showed a main peak at 435 nm and a minor peak at about 325 nm. The action spectrum was similar to that of Streptomyces pigment (Eker et al., 1981) suggesting that the chromophore of the photoreactivating enzyme in Halobacterium halobium is 8‐OH‐5‐deazaflavin. The minor peak may be due to photochemical cleavage of a pyrimidine6–4 hetero adduct. The result indicates that carotenoid pigments do not play a positive role in enhancing photoreactivation. This was confirmed also by comparing the efficiency of photoreactivation at 465 nm among three strains of Halobacterium halobium having different carotenoid pigments; R1m1. R1 and W5002–1.
STRUCTURE OF 3‐CARBETHOXYPSORALEN PHOTOLYSIS PRODUCTS
Authors: Moysan A. , Cazaussus A. , Gaboriau F. , Blais J. C. , Sellier N. , Vlgny P.
Published: January 2008

Abstract— Upon UV‐A irradiation(320–400 nm), the photorcaction of psoralens either with a solvent molecule or with a second psoralen molecule competes with the well‐known photoaddition of psoralens to DNA. In the present study, a structural assignment of the 3‐carbethoxypsoralen (3‐CPs) photolysis products is proposed on the basis of their chromatographic (high performance liquid chromatography) and of their spectroscopic (absorption, fluorescence, mass spectrometry and 1H Nuclear Magnetic Resonance) properties. Four photolysis products have been isolated and identified. The first one results from a water molecule addition on the 4′,5′ double bond of 3‐CPs, the second from an ethanol molecule addition on the 4′,5′ double bond. Two cyclobutane type dimers of 3‐CPs have also been characterized. These results confirm that, in protic solvents, the furan(4′,5′) double bond of 3‐CPs is more photoreactive than the pyrone(3,4) double bond.
PHOTOCHEMICAL‐LIKE BEHAVIOUR OF RIBOFLAVIN IN THE DARK PROMOTED BY ENZYME‐GENERATED TRIPLET ACETONE
Authors: ROJAS JORGE , SILVA EDUARDO
Published: January 2008

Abstract— Triplet acetone obtained enzymically by the isobutyraldehyde/peroxidase/O2 system transfers its energy to the riboflavin, which changes into a decomposition product of lumichrome type and produces aggregates. When riboflavin and tryptophan are added to this system, further products—formylkynurenine and an adduct between the riboflavin and the tryptophan—are formed. The adduct can be separated by gel filtration and ion exchange chromatography and is similar to that prepared by irradiating riboflavin in the presence of tryptophan.
PHOTOCHEMICAL PROPERTIES OF ERYTHROCYTE GHOSTS CONTAINING PORPHYRIN
Authors: FIREY P. A. , RODGERS M. A. J.
Published: January 2008

Abstract— Rabbit erythrocyte cell ghosts were prepared containing tetrasodium meso‐tetra (4‐sulfona‐to‐phenyl) porphine (12‐hydrate), a water soluble porphyrin. Laser flash kinetic spectroscopy of the suspension revealed a difference spectrum consistent with the porphyrin T, state. The time profiles of the signal decay were bi‐exponential, and oxygen quenched each of the two components differently. Triplet‐triplet extinction coefficients and quantum yields were lower for the ghost suspension than for porphyrin in solution. Fluorescence lifetime studies of the suspension also showed the presence of two components. Singlet oxygen luminescence, as measured by germanium diode detection, was observed, with a lifetime of 46 (jls and a 4>A of 0.09.
SUPEROXIDE DISMUTASE AS AN AMPLIFIER OF THE CHEMICAL REACTIVITY OF PORPHYRIN RADICAL‐CATIONS
Authors: Bazin M. , Patterson L. K. , Ronfard‐Haret J. C. , Santus R.
Published: January 2008

Abstract— Porphyrin radical‐cations have been produced using laser flash photolysis via oxidation of the porphyrin triplets by metronidazole. This radical‐cation reacts with OJ as shown by its increased half‐life in the presence of native superoxide dismutase. Comparable results are obtained when porphyrin radical‐cations are formed by Br2‐O2‐oxidation of porphyrins produced in pulse radiolysis of oxygen‐saturated aqueous solutions containing 20 mM Br‐O‐. These results provide an explanation for the enhancement by superoxide dismutase of the photosensitizing capacity of porphyrins in the presence of electrophilic nitroimidazoles (Bazin and Santus, 1986). They may also apply to porphyrin radical‐cations formed by monophotonic or biphotonic photoionization processes.
BILIPROTEINS FROM THE BUTTERFLY Pieris brassicae STUDIED BY TIME‐RESOLVED FLUORESCENCE AND COHERENT ANTI‐STOKES RAMAN SPECTROSCOPY
Authors: Schneider S. , Baumann F. , Geiselhart P. , Kayser H. , Scheer H.
Published: January 2008

Abstract— The fluorescence decay time of the biliverdin IX7 chromophore present in biliproteins isolated from Pieris brassicae is determined to be 44 ± 3 ps. This value suggests a cyclic helical chromophore structure. The vibrational frequencies determined by CARS‐spectroscopy are compared with those of model compounds. The data confirm that the chromophore in the protein‐bound state adopts a cyclic‐helical, flexible conformation.
SUNLIGHT‐INDUCED PYRIMIDINE DIMERS IN HUMAN SKIN FIBROBLASTS IN COMPARISON WITH DIMERIZATION AFTER ARTIFICIAL UV‐IRRADIATION
Authors: Niggli Hugo J. , Röthlisberger Rudolf
Published: January 2008

Abstract— We compared artificial UV‐sources such as germicidal‐ or sun‐lamps with summer noon sunlight in Switzerland for selective efficiency in the induction of pyrimidine dimers in the DNA of human cells. In our studies we determined cytosine‐thymine (C‐T) as well as thymine‐thymine dimer densities (T‐T) by high pressure liquid chromatography in cultures of xeroderma pigmentosum cells of group A. Using far‐UV light from a germicidal lamp, we found a rate of formation per Jirr2 for C‐T and T‐T of 0.0019% and 0.0024%, respectively, of the total thymine radioactivity in hydrolysates of [3H]thymidine labeled cells. After irradiation with an unfiltered sunlamp we measured a rate of formation of 0.0005% per Jm‐2 both for C‐T and T‐T, based on the sunlamp emission of 297 ±4 nm wavelength. Utilization of Kodacel‐ or Mylar‐filters lowered the rate of dimerization by a factor of 2 and 60, respectively. One hour of irradiation with noon summer sunlight induced 0.038 ±0.012% C‐T and 0.036 ±0.011% T‐T. This extent of dimer production is equivalent to 15 Jm‐2 of far‐UV exposure at 254 nm.
STANDARDS FOR UV INSTRUMENTS AND RISK OF EXISTING DEVICES
Authors: Kaase H. , Metzdorf J. , Berger H.
Published: January 2008

Abstract— Different methods for measurements of UV‐radiation of various light sources are quantitatively compared: direct measurements, based on detectors of known responsivity, as well as indirect measurements, based on a spectral irradiance calibration. The optical arrangement of an accurate spectroradiometric equipment, and the structure and parameters for a new type of cosine corrected detector for the measurement of actinic radiation are described, too. The measurements of actinic radiation with commercial devices are affected by great relative errors.

A standard for natural irradiance will allow a comparison of weighted irradiances and threshold irradiations with natural insolation and with artificial UV radiation. The risk of existing irradiation apparatuses will be calculable by this comparison.
CARBON‐14 LABELING AND BIOLOGICAL ACTIVITY OF THE TUMOR‐LOCALIZING DERIVATIVE OF HEMATOPORPHYRIN
Authors: Ho Yau‐Kwan , Pandey Ravindra K. , Missert Joseph R. , Bellnier David A. , Dougherty Thomas J.
Published: January 2008

Abstract— Carbon‐14‐labeled hematoporphyrin ([14C]HP) was synthesized by two methods, (i) Using an in vitro avian whole‐blood system, [14C]protoheme was obtained biosynthetically by incorporating [4C]aminolevulinic acid into the porphyrin ring structure. Subsequently, the [14C]protoheme was converted to [4C]HP by standard procedures, (ii) By adopting several well‐characterized chemical reactions, deuteroporphyrin was treated with [14C]acetyl chloride, giving [14C]diacetyl deuteroporphy‐rin which was readily reduced and hydrolyzed to [14C]HP (with thecarbon–14 label on the hydroxyethyl side‐chains). These two methods are simple and afford good yields of [14C]HP with moderate to high specific activities.

The [14C]HP was then treated with acetic acid/sulfuric acid followed by sodium hydroxide to give [14C]HPD. Upon gel‐ and ultra‐filtration, the [14C]HPD was enriched in the so‐called tumor‐localizing fraction of HPD, giving [14C]PII with specific activities of 0.4 Ci/mol (biosynthesis) and 10 Ci/mol (chemical synthesis). These [14C]PII preparations were equivalent with respect to chromatographic and spectrophotometric characteristics, as well as tumoricidal photodynamic activity in the DBA/2 Ha‐DD mouse: SMT‐F tumor system, to the unlabeled commercial product Photofrin™ II. The distribution of [14C]PII in mouse tissues was in close agreement to that previously reported, after adjustment for dose, for [14C]HPD biosynthetically labeled in vivo (Gomer and Dougherty, 1979), as well as for Photofrin™ II, where tissue levels were determined spectrophotometrically after extraction (Dougherty and Mang, unpublished).
ACCUMULATION OF PORPHYRINS IN CELLS: INFLUENCE OF HYDROPHOBICITY AGGREGATION AND PROTEIN BINDING
Authors: Oenbrink Georg , Jurgenlimke Petra , Gabel Detlef
Published: January 2008

Abstract— For a variety of chemically defined, synthetic and natural porphyrins, the tendency for self aggregation, binding to serum albumin, distribution coefficient betweenoctanol–1 and water and uptake in V79 Chinese hamster cells have been determined. A strong correlation was found between cell uptake and distribution into octanol. None of the other factors could be correlated with cell uptake. These observations might have an impact on the use of porphyrins in photodynamic and boron neutron capture therapy of tumors.
STIMULATION OF Escherichia coli DIVISION BY LOW‐INTENSITY MONOCHROMATIC VISIBLE LIGHT
Authors: Tiphlova Olga , Karu Tuna
Published: January 2008

Abstract— Bacterial suspensions in a phosphate buffer were irradiated at 364, 404, 434, 454, 484, 520, 560. 570, 599, 619, 630, 633, 640, 693, 730 and 750 nm, incubated in Hottinguer broth, and assayed for viability by the standard surface plating technique. When irradiated at 404, 454, 560, 619, and 750 nm, the cells started dividing more rapidly, the growth stimulation effect reaching170–180% 60 min after irradiation. The shape of the action spectrum and the reduced‐minus‐oxidized difference spectrum of the bacterial suspensions suggest that respiratory chain components of the bacterium such as dehydrogenases and cyt d might be the photoacceptors involved. The growth stimulation effect is believed to be due to the ability of the irradiation‐activated respiratory chain to produce the necessary pH gradient more rapidly, thus enabling the cells to start dividing earlier.
RESONANCE RAMAN SPECTRA OF THE II‐CATION RADICALS OF COPPER, COBALT, AND NICKEL METHYLOCTAETHYLCHLORINS: VIBRATIONAL CHARACTERISTICS OF CHLOROPHYLL MODELS
Authors: Salehi Asaad , Oertling Nthony , Fonda AroldN. , Babcock Erald T. , Chang C. K.
Published: January 2008

Abstract— By using excitation at 363.8 nm, resonance Raman (RR) spectra were obtained for Cu(II), Co(II), and Ni(II) complexes of methyloctaethylchlorin (MeOEC) and their ir‐cation radicals. Additionally, the Raman spectra of the Cu(II) derivatives of (rarcs‐octaethylchlorin (r‐OEC) were included for comparison. The alkyl‐substituted CuMeOEC exhibits a Raman spectrum that is nearly identical to that of the simpler (‐CuOEC in both the neutral and oxidized states. Unlike the latter species, the cation radical of CuMeOEC is immune to oxidative dehydrogenation to porphyrin, and this has facilitated vibrational characterization of the ring‐oxidized species. This study aims to compare the vibrational characteristics in the 1450 to 1700 cm‐t region of the metallochlorin ir‐cation radicals to those of the corresponding oxidized metalloporphyrins. We focus on two modes in the1500–1520 cm‐1 and1620–1650 cm‐1 region that are analogous to the v3 and v10 vibrations, respectively, in the metalloporphyrin analogs. These vibrational modes are clearly defined in all species and exhibit a strong core‐size dependency in the porphyrin complexes. The core‐size study as well as the frequency changes upon oxidation support the conclusion that the v3‐like vibration in the chlorin species features substantial CbCb in addition to CaCm stretching character. The v,0‐like mode of the chlorin macrocycle, on the other hand, displays characteristics that closely resembles that of the porphyrin analog; consequently, these vibrations are of predominantly CaCm stretching character in both cases.
SEPARATION OF PHOTOINDUCED CHLOROPHYLL‐a CATION AND p‐TETRABROMOBENZOQUINONE ANION ELECTRON SPIN RESONANCE LINES AT 35 GHz IN FROZEN VESICLE SOLUTIONS
Authors: Hiff Thomas , Kevan Larry
Published: January 2008

Abstract— The photoionization products of chlorophyll‐a with p‐tetrabromobenzoquinone as an electron scavenger in rapidly frozen phospholipid vesicles have been detected by electron spin resonance. The asymmetric line resulting from the overlap of the chlorophyll‐fl cation radical and the scavenger anion radical at 9 GHz (X band) has been resolved into two symmetric lines with different g values at 35 GHz (Q band).
DEGRADATION OF OLIGONUCLEOTIDES BY VACUUM‐UV RADIATION IN SOLID: ROLES OF THE PHOSPHATE GROUP AND BASES
Authors: Ito Takashi , Saito Mikio
Published: January 2008

Abstract— Vacuum‐UV induced degradation of deoxyoligonucleotides in solid form was studied by thin‐layer chromatography with special emphasis on the fragmentation products. First, the degradation scheme previously proposed for 2′‐deoxyadenylyl‐(3′‐5′)‐2′‐deoxyadenosine (dApdA), which states that deoxypentose of the adenylyl moiety is the initial site of destruction, was confirmed by employing 258, 275, and 285 nm, in combination, as scanning wavelengths of chromatograms. Consistent results were obtained with 2′‐deoxyadenylyl‐(3′‐5′)‐2′‐deoxycytidine (dApdC), for which adenine and 5′‐monophosphate of deoxycytidine are the predicted products, although the efficiency for such degradation mode was found to be lower with dApdC than with dApdA. Cytosine residue, thus, appeared to exert a suppressive effect on the destruction of deoxypentose of the adenylyl moiety. Second, with 2′‐deoxycytidylyl‐(3′‐5′)‐2′‐deoxyadenosine (dCpdA) the same spectroscopic analysis revealed that both adenine and cytosine were released, as well as some unidentified products, which could not be precisely identified by their chromatographic positions as dAMP or dCMP, although they showed characteristic absorption properties of adenine or cytosine containing species. This suggests that the photodegradation mode of dideoxynucleoside monophosphates is not so unique as hypothesized above, but that it depends also on the sequence of base residues. Finally, a very poor sensitivity to photodegradation of thymidylyl‐(3′‐5′)‐2′‐deoxycytidine(dTpdC) and thymidylyl‐(3′‐5′)‐thymidine (dTpdT) to vacuum‐UV radiation suggests that any pyrimidine could decrease the damaging effect of high energy vacuum‐UV photons.
PHOTODYNAMIC EFFECTS OF HEMATOPORPHYRIN DERIVATIVE ON THE UPTAKE OF RHODAMINE 123 BY MITOCHONDRIA OF INTACT MURINE L929 FIBROBLASTS AND CHINESE HAMSTER OVARY Kl CELLS
Authors: Boegheim J. P. J. , Lagerberg J. W. M. , Dubbelman T. M. A. R. , Tussen K. , Tanke H. J. , Van der Meulen J. , Van Steveninck J.
Published: January 2008

Abstract— It was shown that the cationic fluorescence probe rhodamine 123 accumulates in mitochondria of murine L929 fibroblasts and Chinese hamster ovary Kl epithelial cells due to the driving force of both plasma membrane and mitochondrial membrane potentials. Photodynamic treatment of L929 cells with hematoporphyrin derivative resulted in an increased uptake of rhodamine 123 and a diminished uptake of 1,1,3,3,3′,3′‐hexamethylindocarbocyanine iodide. This indicates a considerably increased mitochondrial membrane potential, which most likely is the result of a direct or secondary inhibition of the ATP‐synthetase, and a decreased plasma membrane potential. The oxygen consumption rate and the ATP level decreased due to photodynamic treatment. Post‐incubation of L929 cells subsequent to photodynamic treatment revealed that the uptake of rhodamine 123. the ATP content and the oxygen consumption rate were restored. For all parameters similar results were obtained with CHO‐K1 cells, with the exception that during post‐incubation the intracellular ATP content remained at the level reached after illumination. These results indicate that photodynamically induced disturbance of mitochondrial functions and the ATP level are not crucial for the loss of clonogenicity of L929 cells. In CHO‐K1 cells however, the continuously lowered ATP level may have detrimental consequences for cell survival. The photodynamic stimulation of the rhodamine 123 uptake may be a rather general phenomenon. Because rhodamine 123 exhibits a much higher toxicity towards carcinoma cells than towards other cells, a synergistic interaction between this drug and photodynamic therapy (PDT) may be anticipated, if PDT also stimulates mitochondrial rhodamine 123 accumulation in carcinoma in vivo.
EFFECT OF DIETARY LIPID ON UV LIGHT CARCINOGENESIS IN THE HAIRLESS MOUSE
Authors: Reeve Vivienne E. , Matheson Melissa , Greenoak Gavin E. , Canfield Paul J. , Boehm‐Wilcox Christa , Gallagher Clifford H.
Published: January 2008

Abstract— Isocaloric feeding of diets varying in lipid content to albino hairless mice has shown that their susceptibility to skin tumorigenesis induced by simulated solar UV light was not affected by the level of polyunsaturated fat, 5% or 20%. However a qualitative effect of dietary lipid was demonstrated. Mice fed 20% saturated fat were almost completely protected from UV tumorigenesis when compared with mice fed 20% polyunsaturated fat. Multiple latent tumours were detected in the saturated fat‐fed mice by subsequent dietary replenishment, suggesting that a requirement for dietary unsaturated fat exists for the promotion stage of UV‐induced skin carcinogenesis.
POSSIBLE LONG‐TERM CHANGES IN BIOLOGICALLY ACTIVE ULTRAVIOLET RADIATION REACHING THE GROUND
Authors: Frederick John E. , Lubin Dan
Published: January 2008

Abstract— Three scenarios for long‐term changes in atmospheric ozone over the time period 1960 to 2030 lead to different projections for the ultraviolet radiation flux at the earth's surface. Biologically effective fluxes for damage to DNA and generalized damage to plants vary by a factor of 10 or more with latitude and season irrespective of possible changes in ozone. The natural latitudinal gradient in radiation corresponds to spatial changes in biologically effective fluxes which are large compared to temporal changes expected from trends in ozone over the time period analyzed. In an extreme scenario of ozone change, based on an assumed increase in chlorofluorocarbon release rates of 3% per year after 1980, the annually integrated effective flux for damage to DNA increases by 13.5% at latitude 40°N between 1960 and 2030. With chlorofluorocarbon release rates held fixed at their 1980 values, the corresponding radiation increase is only 2.3%. In a scenario where atmospheric chlorine remains fixed at its 1960 value, trends in atmospheric methane and nitrous oxide imply a decrease in biologically effective flux at 40°N of 5.3% between 1960 and 2030.
STRUCTURE AND STABILITY OF γ‐CRYSTALLINS‐V. COVALENT AND NONCOVALENT PROTEIN‐PROTEIN INTERACTIONS IN PHOTOSENSITIZED REACTIONS
Authors: Kono Masahiro , Mandal Krishnagopal , Chakrabarti Bireswar
Published: January 2008

Abstract— Irradiation of γ‐crystallins with 300 nm light or with the photosensitizers riboflavin or methylene blue (MB) leads to intermolecular cross‐linking and insolubilization. Sodium dodecyl sulfate polyacrylamide gel electrophoresis studies reveal that these cross‐links are composed of nondisulfide covalent bonds. The water‐insoluble phase is stabilized by noncovalent forces, as denaturants readily dissolve it. High‐performance liquid chromatography and electrophoresis results further indicate that the higher multimers are part of this water‐insoluble fraction only, with the exception of MB‐sensitized reactions, which are also able to produce a water‐soluble, high‐molecular‐weight protein of at least 1 million. Labeling the external sulfhydryl groups with iodoacetamide does not prevent the photoreac‐tions; however, a reducing agent such as dithiothreitol does. A mechanism involving initial oxidation and interaction of sulfhydryl groups (forming an intramolecular disulfide) buried within the protein as a necessary precursor to polymerization and precipitation has been proposed in the preceding paper. The present study provides support for this mechanism.
PHOSPHORESCENCE MAXIMA AND TRIPLET STATE LIFETIMES OF NAD + AND ε‐NAD+ IN TERNARY COMPLEXES WITH HORSE LIVER ALCOHOL DEHYDROGENASE
Authors: ROUSSLANG KENNETH , ALLEN LYNN , ROSS J. B. ALEXANDER
Published: January 2008

Abstract This paper describes the phosphorescence emission and decay times of NAD and its fluorescent etheno derivative, ε‐NALV+, in the pyrazole ternary complex with horse liver alcohol dehydrogenase (ADH). We show that the ε‐NAD+, triplet state, as well as the tryptophan triplet state, can be utilized to monitor the coenzyme‐enzyme interaction. The decays of NAD+ and AMP are single exponential, and the lifetimes are the same within experimental error. The phosphorescence lifetimes, evaluated as single exponentials, are slightly shorter in ε‐NAD4 than they are in ε‐AMP. Whereas the decay of ε‐AMP was adequately fit by a single exponential with a time constant of very close to 0.5 s, it was necessary to fit the decay of e‐NAD+ to a double exponential. Ternary complexes with NAD+ excited at 297 nm exhibit decay kinetics nearly identical to those of ADH by itself. On the other hand, when excitation of the e‐NAD+ ternary complex is provided at 313 nm. where there is very little absorption by either tryptophan residue, the decay law of the ternary complex is similar to that of ε‐NAD+ in solution. Our results demonstrate that NAD+ and ε‐NAD+ quench tryptophan phosphorescence in ADH. Normalizing the phosphorescence intensity to the 0–0 vibronic band assigned to Trp‐15 (blue‐edge), we calculate a 21% decrease in the phosphorescence associated with Trp‐314 at stoichiometric saturation of the coenzyme binding sites with NAD‐ in the ternary complex. When the active sites are saturated with εS‐NAD+, the relative phosphorescence due to Trp‐314 decreases by 63%. Since ε‐NAD+ can be selectively excited in ternary complexes with ADH, it is a more useful probe than NAD+ for investigating energy transfer in these complexes.
EFFECT OF ULTRAVIOLET RADIATION ON THE ENERGY METABOLISM OF THE CORNEAL EPITHELIUM OF THE RABBIT
Authors: LATTIMORE MORRIS R. , JR
Published: January 2008

Abstract The present research was directed at quantifying, possible alterations in corneal epithelial metabolic activity secondary to in vivo exposure to ultraviolet radiation (UVR). Microfluorometric energy metabolite assays on microgram (μg) sized, freeze‐dried tissue samples were used as an in vitro means of assessing overall metabolic activity in the epithelium of control rabbit corneas and in the epithelium of UVR‐exposed rabbit corneas 2 min after discontinuation of exposure. The specific assays were for glucose, glycogen, adenosine triphosphate (ATP), and phosphocreatine (PCr). The radiant exposures were kept constant at 0.05 J cm‐2 for all UVR wavelengths utilized (290, 300, 310 and 360 nm). Experimental UVR exposure conditions served to increase epithelial glucose and glycogen concentrations. Although the epithelial ATP concentrations were unchanged, the epithelial PCr concentrations (a high energy phosphate bond reservoir) decreased as a result of UVR exposure. Overall, the data demonstrate a decrease in corneal epithelial metabolic activity, which may be wavelength‐dependent, as a result of UVR exposure. It is suggested that immediate metabolic stress can be responsible for the pattern of epithelial cell loss seen in photokeratitis.
OPTIMIZATION OF THE PHOTO‐ENZYMATIC REDUCTION OF THE CARBON‐CARBON DOUBLE BOND OF α‐β UNSATURATED CARBOXYLATES IN REVERSED MICELLES
Authors: VERHAERT R. M. D. , SCHAAFSMA T. J. , LAANEI C. , HILHORST R. , VEEGER C.
Published: January 2008

Abstract A system is described for the photo‐induced biocatalytic reduction of enoates in reversed micelles composed of detergent, buffer and mixtures of alcohol and octane as cosurfactant and dispersant respectively. The photosystem consisted of the sacrificial electron donor tributylamine, Zn(II) meso‐mono(4‐N‐decyipyridyl)‐tri(phenyl)porphyrin as photosensitizer and methylviologen as electron acceptor. The enzyme enoate reductase (EC 1.3.1.31) utilizes the photo‐reduced methylviologen for the stereospecific reduction of enoates. The composition of the reversed micellar medium has been optimized with respect to both the photochemical and the enzymatic part of the system. The yield of the photosystem increased with increasing polarity of the reversed micellar solution. The activity and stability of enoate reductase depended strongly on the nature and concentration of the cosurfactant in the reversed micelles. Increasing the chain length of the cosurfactant stabilizes the enzyme in the presence of enoates, but it leads to a more rapid loss of activity of the reduced form of the enzyme. Reversed micelles were composed in which both operational and storage stability of enoate reductase are at least equal to that in water. The photochemical regeneration of methylviologen coupled to the enzymatic reduction of tiglic acid and cinnamic acid yielded a system that was active for over 100 h in the presence of a cofactor regenerating system in reversed micelles. The enzyme was as stable as in aqueous solution. Therefore this photo‐enzymatic system can be used for the stereospecific reduction of apolar α‐β unsaturated carboxylates.
THE STEPWISE BIPHOTONIC PHOTOIONIZATION OF CHLORPROMAZINE AS SEEN BY LASER FLASH PHOTOLYSIS
Authors: BUETTNER GARRY R. , HALL ROBERT D. , CHIGNELL COLIN F. , MOTTEN ANN G.
Published: January 2008

Abstract It is generally accepted that both promazine (PZ) and chlorpromazine (CPZ) photoionize monophotonically to their respective cation radicals and the corresponding hydrated electrons. It is also supposed that this photoionization has a role in the phototoxic effects of these drugs. However, using laser flash photolysis, we have observed that photoionization of CPZ during S, excitation (Λ > 300 nm) is a stepwise biphotonic process. In the case of PZ our flash photolysis results are less clear‐cut, but are consistent with stepwise biphotonic photoionization for S, excitation. We demonstrate, using computer simulation of the intramolecular kinetics, that the estimated triplet state lifetime of CPZ is sufficiently long (23 ns at room temperature) to account for the apparent monophotonic photoionization that has been observed by others at high light intensities and short pulse times. Our laser flash photolysis results also suggest that the photo‐ionization mechanism of PZ and CPZ is wavelength‐dependent. Both drugs exhibit apparent monophotonic photoionization when they are excited at 266 nm under conditions of laser pulse width and intensity similar to those at 355 nm. We suggest that photoionization is not an important mechanism in the observed phototoxic and photoal‐lergic effects of PZ and CPZ in sunlight.
RING‐OPENING PHOTOREACTIONS OF CYTOSINE AND 5‐METHYLCYTOSINE WITH ALIPHATIC ALCOHOLS
Authors: SHAW ANTHONY A. , SHETLAR MARTIN D.
Published: January 2008

Abstract Several reports in the late 1950s and early 1960s indicated that ultraviolet irradiation of dilute solutions of cytosine or 5‐methylcytosine in aliphatic alcohols, such as methanol or ethanol, leads to reaction mixtures containing products with an absorption maximum around 300 nm. The present work reports the isolation and characterization of the products responsible for this absorption in the photochemical reactions of cytosine and 5‐methylcytosine with methanol, ethanol and 2‐propanol at concentrations in the neighborhood of 200 μM. Under these conditions the reactions have been shown, in each nucleobase/alcohol system, to give almost exclusively a single type of primary photopro‐duct; each product shows an absorption maximum in the region of 300 nm. Structural analysis showed the products to be alcohol adducts with an ester linkage at C2 of the ring‐opened base and an enamine structure at C6. For example, in the case of the reaction of cytosine with methanol, the product is N‐carbomethoxy‐3‐aminoacrylamidine (IIIa). The occurrence of this type of photoreaction suggests a mode by which alcoholic functional groups on amino acid side chains could contribute to photoinduced DNA‐protein cross‐linking.
OXYGEN LIMITATION OF DIRECT TUMOR CELL KILL DURING PHOTODYNAMIC TREATMENT OF A MURINE TUMOR MODEL
Authors: HENDERSON BARBARA W. , FINGAR VICTOR H.
Published: January 2008

Abstract The relationship between levels of in vivo accumulated photosensitizer (Photofrin II), photodynamic cell inactivation upon in vitro or in vivo illumination, and changing tumor oxygenation was studied in the radiation‐induced fibrosarcoma (RIF) mouse tumor model. In vivo porphyrin uptake by tumor cells was assessed by using 14C‐labeled photosensitizer, and found to be linear with injected photosensitizer dose over a range of 10 to 100 mg/kg. Cellular photosensitivity upon exposure in vitro to 630 nm light also varied linearly with in vivo accumulated photosensitizer levels in the range of 25 to 100 mg/kg injected Photofrin II, but was reduced at 10 mg/kg. Insignificant increases in direct photodynamic cell inactivation were observed following in vivo light exposure (135 J/cm2, 630 nm) with increasing cellular porphyrin levels. These data were inconsistent with expected results based on in vitro studies. Assessment of vascular occlusion and hypoxic cell fractions following photodynamic tumor treatment showed the development of significant tumor hypoxia, particularly at 50 and 100 mg/kg of Photofrin II, following very brief light exposures (1 min, 4.5 J/cm2). The mean hyupoxic cell fractions of 25 to 30% in these tumors corresponded closely with the surviving cell fractions found after tumor treatment in vivo, indicating that these hypoxic cells had been protected from PDT damage. Inoculation of tumor cells, isolated from tumors after porphyrin exposure, into porphyrin‐free hosts, followed by in vivo external light treatment, resulted in tumor control in the absence of vascular tumor bed effects at high photosensitizer doses only. These results indicate that the prerequisites for tumor destruction via direct photodynamic tumor cell inactivation in vivo are high photosensitizer content in tumor cells and relative insensitivity of the tissue microvasculature. Under conditions where the tumor bed is sensitive to photodynamic damage, tumor cell kill can occur at a wider range of photosensitizer levels as a consequence of PDT induced ischemia.
THE PROTONATION OF A RETINYL SCHIFF BASE
Authors: BADILESCU SIMONA , DE ALENCASTRO RICARDO BICCA , LE‐THANH HOA , RlCHER GUY , SANDORFY CAMILLE , VAUDREUIL PIERRE‐PAUL , VOCELLE DANIEL
Published: January 2008

Abstract The hydrogen bonding‐protonation equilibrium for retinyl Schiff base/propionic acid or 3‐chloropropionic acid systems was examined by Fourier transform infrared spectroscopy in non polar solutions at temperatures ranging from 25°C to about ‐150°C. The spectra give evidence for the gradual increase in the degree of protonation as temperature is lowered. The bearing of this on applying low temperature spectroscopic results to physiological conditions in rhodopsin research is discussed.