bluuebunny/crossref_metadata_2025 huggingface dataset:
STATIC QUENCHING OF EXCITED STATE OF TRIS(BIPYRIDINE)RUTHENIUM(II) COMPLEX‐CONTAINING POLYMER BY SODIUM ANTHRAQUINONE‐2‐SULFONATE
Authors: Sumi Katsuhiro , Furue Masaoki , Nozakura Shun‐ichi
Published: January 2008

Abstract— Quenching of excited state of Ru(bpy)2(poly‐4‐methyl‐4'‐vinyl‐2,2'‐bipyridine)Cl2 by sodium anthraquinone‐2‐sulfonate was found to be a static process. The quenching was interpreted by application of a modified Perrin model. Radius of the quenching sphere was estimated to correspond to 6.65 monomer units and was unchanged on varying the Ru2+ content of the polymer. Energy migration along the polymer chain was denied.
RESOLUTION OF OVERLAPPING BANDS IN THE NEAR‐UV ABSORPTION SPECTRUM OF INDOLE DERIVATIVES
Authors: Ragone Raffaele , Colonna Giovanni , Servillo Luigi , Irace Gaetano
Published: January 2008

Abstract— The second derivative spectra of tryptophan in water and in ethylene glycol at 22°C have been integrated in order to obtain the corresponding primitive functions. The integration was carried out by making use of Tchebychev polynomials. The results show that the integrated primitive functions do not correspond to the original absorption spectra of tryptophan in various solvents, but they reflect only the contributions of the 1Lb bands of the indolic chromophore. The identification of the electronic component, which generates the second derivative spectrum, was based on the solvent insensitivity of the derivative peaks. The comparison between the absorption spectra reported in this paper and those calculated for the 1Lb←1A electronic transition of indole confirmed the assumption that the derivation process eliminates the broad, although more intense, contributions coming from the 1La←1A electronic transition.
ENERGY TRANSFER FROM CHEMIEXCITED ACETONE TO SUBSTANCES THAT DISPLAY ANOMALOUS FLUORESCENCE
Authors: Adam Waldemar , Baader Wilhelm J. , Catalani Luiz H. , Cilento Giuseppe , Rychlá Lyda
Published: January 2008

Abstract— Excited acetone generated in the thermolysis of tetramethyldioxetane elicits the anomalous S2→ S0 fluorescence from azulene and from xanthione. In the case of azulene it could be demonstrated that (i) only the acetone singlets transfer energy to the S2 state and (ii) the acetone triplets are quenched. These energy transfer processes are diffusion‐controlled.
RED: FAR‐RED RATIO DOES NOT MODULATE THE ABUNDANCE OF TRANSCRIPTS FOR TWO MAJOR CHLOROPLAST POLYPEPTIDES IN LIGHT‐GROWN Pisum sativum TERMINAL SHOOTS*
Authors: Jenkins G. I. , Smith H.
Published: January 2008

Abstract— We have used specific, cloned cDNA hybridisation probes to measure the abundance of transcripts for the small subunit (SSU) of ribulose bisphosphate carboxylase‐oxygenase, and the major apoprotein (LHCP) of the light‐harvesting chlorophyll alb complex, in total RNA extracts of Pisum sativum shoots grown under different light qualities. The plants were grown in continuous white light of a constant fluence rate (50 p.mol m−2s−1;400–700 nm) supplemented with far‐red light to give different ratios of red: far‐red light, and hence different in vivo phytochrome photoequilibria. Variation of the red: far‐red ratio over the range 1.87 to 0.10, calculated to give in vivo Pfr: Ptotal ratios of 0.78 to 0.37, had no significant effect on leaf expansion but had a marked effect on internode extension rate. The abundances of the SSU and LHCP RNAs in RNA extracts from the terminal shoot were not significantly different in the four light quality treatments. The results are discussed in relation to the photoregulation of expression of these genes in light‐grown plants.
RED‐LIGHT‐INDUCED GERMINATION OF LETTUCE SEEDS: RELATIONSHIP BETWEEN ESCAPE FROM REVERSIBILITY AND FLUENCE*
Authors: Blaauw‐Jansen G. , Sewmar R.
Published: January 2008

Abstract— Dormant seeds of Lactuca saliva L. (cv. ‘May Queen’) germinate after a brief light treatment. The seeds escape from photoreversibility by far‐red irradiation after a lag time. The duration of the lag decreases with increasing levels of the far‐red absorbing form of phytochrome (Pfr). During the lag time the percentage of seeds germinating after the reversing far‐red irradiation is slowly rising. This is not due to an escape reaction proper, but to an increase of sensitivity to Pfr.
INTERACTION BETWEEN PHYTOCHROME AND THE BLUE LIGHT PHOTORECEPTOR SYSTEM IN Mougeotia*
Authors: Gabrys Halina , Walczak Tadeusz , Haupt Wolfgang
Published: January 2008

Abstract— Face‐to‐profile chloroplast movement in Mougeotia was induced by sequences of strong blue and red short irradiations. This type of response occured only when blue light was applied prior to or simultaneously with red light, and far‐red irradiation was necessary after the sequence to cancel the remaining gradient of the far‐red absorbing form of phytochrome Pfr. The dependence of the response magnitude on blue and red light sequences was studied for a wide range of light durations and dark intervals. The relationship between the response and the dark interval points to the lack of direct coupling between phytochrome and blue‐absorbing “cryptochrome”. It was postulated that a photoproduct having a life‐time of2–3 min is formed by the blue‐light‐mediated reaction. This photoproduct interacts with phytochrome during its transformation or with its final Pfr form.
FATTY ACID ANALYSIS AS A FUNCTION OF PHOTO‐OXIDATION IN EGG YOLK LECITHIN VESICLES
Authors: Dearden S. J. , Hunter T. F. , Philp J.
Published: January 2008

Abstract— The photo‐oxidation by O2(1Δg) of individual lipid components in egg yolk lecithin is examined as a function of time. The rate of oxidation is correlated with the degree of unsaturation in the fatty‐acid chains.
UROCANIC ACID PHOTOBIOLOGY. PHOTOCHEMICAL BINDING TO CALF THYMUS DNA*
Authors: Morrison H. , Mauclair B. , Deibel R. M. , Pandey G. , Baird W. M.
Published: January 2008

Abstract— Urocanic acid (UA) has previously been shown to photochemically react with N, N‐dimethylthymine and with phage G4 single‐stranded DNA. In this study, E‐[ring‐2‐14C]‐U A and calf thymus DNA have been irradiated with UV light (Λ > 270 nm) in buffered, aqueous solutions. Rc‐isolation of the DNA indicates covalent binding of UA at levels of up to 80 nmol UA/mg DNA. Binding is observed for both native and heat denatured DNA. Equilibrium dialysis studies give no evidence for complexation of UA to either form of DNA in the dark. Enzymatic cleavage of the UA bound DNA and analysis by HPLC shows peaks for l4C‐labelled products with retention volumes identical to those of a marker mixture prepared by irradiating UA with [3H‐methyl]thymidine. Photolysis of the DNA before irradiation with U A leads to the formation of a second product with a retention volume corresponding to that for a deoxyadenosine/UA marker.
LONG WAVELENGTH UV RADIATION AFFECTS CHEMILUMINESCENCE OF HUMAN POLYMORPHONUCLEAR LEUCOCYTES
Authors: Bredberg Anders , Forsgren Arne
Published: January 2008

Abstract— Luminol‐enhanced chemiluminescence in suspensions of human polymorphonuclear leucocytes stimulated with the chemotactic oligopeptide formyl‐methionyl‐leucyl‐phenylalanine was increased by exposure of the cells to long wavelength UV radiation (mainly320–400 nm). Leucocytes treated with 0.3 × 104 J m‐2 of UV responded with doubled peak values, and 4 × 104 J m‐2 lead to a five‐fold increase in peak chemiluminescence, as compared with non‐exposed cells. Supernatants isolated from irradiated leucocytes contained increased amounts of both myeloperoxidase and lactate dehydrogenase and showed higher chemiluminescence values, when compared with supernatants from sham‐irradiated cells. The results suggest that leucocyte degranulation contributes to the inflammatory properties of long wavelength UV.
HYDROGEN PEROXIDE INDUCED RESISTANCE TO BROAD‐SPECTRUM NEAR‐ULTRAVIOLET LIGHT(300–400 nm) INACTIVATION IN Escherichia coli
Authors: Sammartano Lauri J. , Tuveson R. W.
Published: January 2008

Abstract— Strains of Escherichia coli carrying the four possible combinations of the alleles nur, nur+, uvrAb, and uvrA+ were either untreated or pretreated with a sublethal dose of H202 prior to inactivation with NUV radiation. Pretreated cells exhibited a greater resistance to NUV than did untreated cells. Pretreatment with H2O2 did not induce resistance to FUV radiation. The induction of resistance to NUV inactivation by H2O2 pretreatment apparently leads to protection against the damage caused by NUV radiation. Although pretreatment of cells with H202 leads to resistance of such cells to inactivation by H2O2 and NUV, survival of H2O2 treated bacteriophage PI cml clr100 is not enhanced when assayed on H2O2 pretreated E. coli host cells.
3‐CARBETHOXYPYRANOCOUMARIN, A PHOTOREACTIVE DERIVATIVE OF XANTHYLETIN WITH INTERESTING PHOTOBIOLOGICAL PROPERTIES
Authors: Averbeck D. , Nocentini S. , Faulques M. , Rene L. , Royer R.
Published: January 2008

Abstract— The photobiological activity of the newly synthesized pyranocoumarin derivative 3‐carbethoxypyranocoumarin, so‐called 3‐carbethoxyhomopsoralen (3‐CHPs) was studied in comparison to the known bifunctional furocoumarin 8‐methoxypsoralen {8‐MOP) and to the monofunctional furocoumarin 3‐carbethoxypsoralen (3‐CPs) in the presence of 365 nm irradiation using two eukaryotic cell systems, the yeast Saccharomyces cerevisiae and cultured normal human skin fibroblasts. 3‐Carbethoxyhomopsoralen is shown to be a photobiologically active compound capable of effectively photoinducing cytoplasmic “petite” mutants (mitochondrial damage), nuclear reversions and mitotic gene conversion in the diploid yeast strain D7. Per unit dose it is more effective than 8‐MOP and 3‐CPs for the induction of cytoplasmic “petite” mutants but less effective than 8‐MOP for the induction of nuclear reversions and mitotic gene conversion. A very moderate effect on cell survival is accompanied by a relatively strong genetic activity per viable cell. In human fibroblasts 3‐CHPs produces a stronger inhibition of DNA synthesis than 8‐MOP and 3‐CPs at low doses of 365 nm radiation. During post‐treatment incubation human fibroblasts recovered more easily from DNA synthesis and growth inhibitions photoinduced by 3‐CHPs than from those photoinduced by 8‐MOP. The results are in accord with the notion that 3‐CHPs is a highly photoreactive monofunctional compound inducing easily repairable lesions with a low lethal but significant mutagenic potential.
A DETAILED RESONANCE RAMAN STUDY OF THE M412 INTERMEDIATE IN THE BACTERIORHODOPSIN PHOTOCYCLE
Authors: Deng H. , Pande C. , Callender R. H. , Ebrey T. G.
Published: January 2008

Abstract— Resonance Raman spectra of various M412 species associated with the bacteriorhodopsin photocycle have been obtained. These correspond to the two forms observed during the formation of M412 and the two forms that are observed during its decay in absorption experimeents. We do not see any significant difference between the Raman spectra of any of these forms. We therefore conclude that the differences in these species are due to the differences in the protein structure and not in the chromophore.
EVIDENCE FOR BRANCHING IN THE PHOTOCYCLE OF BACTERIORHODOPSIN AND CONCENTRATION CHANGES OF LATE INTERMEDIATE FORMS
Authors: Beach J. M. , Fager R. S.
Published: January 2008

Abstract— Flash photolysis transients of bacteriorhodopsin were recorded with a spectrograph ‐multielement photodiode array combination and the recordings were analyzed to determine the concentrations of bacteriorhodopsin intermediates “M” and “O” relative to the amount of “bR” cycling (pH 7.1,10–40°C). Estimated concentration time courses were simulated with solutions to two kinetic decay models which could account for photocycle temperature dependence. A unidirectional unbranched decay model overpredicts our estimated levels of [O(r)], whereas a model branched at the “M” intermediate describes each of the later intermediate levels well (with no evidence for an independent “N” form). Our results are consistent with “M” decay regulating the level and rates of change of [bR(t)] and (bR(f)]‐ and also suggest that two temperature‐dependent pathways form “bR” from “M”, one directly, and the other indirectly through “O”.
ACTION SPECTRA FOR ACCUMULATION OF INORGANIC CARBON IN THE CYANOBACTERIUM, Anabaena variabilis
Authors: Ogawa Teruo , Ogren William L.
Published: January 2008

Abstract— Action spectra for accumulation of inorganic carbon were obtained for Anabaena variabilis, strainM–2, in the presence and absence of photosynthetic CO2 fixation. The action spectrum for inorganic carbon accumulation in the presence of CO2 fixation showed a peak around 684 nm, corresponding to chlorophyll a absorption in PS 1, while that for CO2 fixation showed a peak around 630 nm, corresponding to phycocyanin absorption in PS 2. The action spectra obtained in the presence of iodoacetamide or diuron, which inhibit CO2 fixation, showed two peaks, one at about 684 nm and the other at 630 nm, with the 630 nm peak height 80 to 90% of the 684 nm peak. These results indicate that inorganic carbon transport in A. variabilis can be driven with near equal efficiency by energy derived from absorption in photosystem 1 alone and with energy transferred to PS 1 after absorption by PS 2.
BLUE AND WHITE LIGHT EFFECTS ON CHLOROPLAST DEVELOPMENT IN A SOYBEAN MUTANT
Authors: Duysen Murray , Eskins Kenneth , Dybas Linda
Published: January 2008

Abstract—

Phenotypic difference for chloroplast development between the normal green (CL1) and the Cy9y9 soybean mutant was observed when the plants were grown under 18W m−2 white or blue light. Under these conditions the mutant soybean accumulated less Chi b, neoxanthin, carotene and less total pigment than the CL1 genotype. Chloroplasts of the Cy9y9 line were deficient in the LHP complex relative to that of chloroplasts from the normal soybean. Specific differences were noted between chloroplasts from plants grown under blue and white light. Accumulations of a 34 kD (PSII) and a 16–17 kD (PSI) membrane polypeptide were decreased by blue light in both soybean genotypes. Blue light induced a greater accumulation of a 32 kD (PSII) polypeptide than white light. Blue light reduced granal thylakoid stacking and increased the proportion of stroma thylakoids compared to those that developed under white light. PSI electron transport activity was stimulated by the blue light treatment more than that of PSII.
EFFECTS OF 8‐METHOXYPSORALEN AND NEAR ULTRAVIOLET RADIATION ON THE SURVIVAL OF THE LOWER EUKARYOTE D. Discoideum
Authors: Graetzer R. , Morrison T. W.
Published: January 2008

Abstract— Seven axenic wild‐type and repair‐deficient mutant strains of the cellular slime mold Dictyostelium discoideum have been treated with the furocoumarin 8‐methoxypsoralen (8‐MOP) up to 50 μg/mζ and then exposed to near ultraviolet light (UVA 320‐400 nm) up to 21 kJ/m2. Fluence‐response survival curves exhibit shoulders at lower fluences and an exponential lethal response at higher fluences. Neither the psoralen alone nor the irradiation alone produced any measurable lethal effect. Wild‐type strains, which show resistance to 254 nm UV and gamma radiation, also show resistance to psoralen plus UVA. The moderate sensitivity of a rad D repair‐deficient mutant strain and the extreme sensitivity of a rad B mutant strain to 8‐MOP plus UVA parallel their responses to UV and gamma radiation. However a rad C mutant which is sensitive to UV, exhibits wild‐type response to photoactivated psoralen.
PHOTOISOMERIZATION OF ζ‐CAROTENE STEREOISOMERS IN CELLS OF Euglena gracilis MUTANT W3BUL AND IN SOLUTION*
Authors: Cunningham Francis X. , Schiff Jerome A.
Published: January 2008

Abstract— Dark‐grown cells of Euglena gracilis var. bacillaris bleached mutant W3BUL are shown by a novel alumina HPLC method to accumulate a cis isomer of ζ‐carotene (cis I; δmax at 286,296,377,398,422 nm; εmM= 97 at 398 nm). Illumination of cells with saturating blue light converts nearly all of this to the trans isomer (δmax at 379,400,425 nm) and a small amount of a second cis isomer (cis II; δmax at 285.5,296, 374, 394.5, 419 nm; εmM= 111 at 394.5 nm) with no significant changes in any other carotenoids. Photoisomerization of the purified isomers in hexane yields the same mixture of stereoisomers in all three cases, and this mixture is similar to that produced in the cells. Photoisomerization of the purified cis isomers in hexane occurs readily with first order kinetics indicating that no additional photosensitizer or catalyst is necessary for the reaction in vivo. Wild‐type cells grown in darkness in the presence of 72 μM J334 accumulate ζ‐carotene almost exclusively with approximately equal amounts of the cis I and trans isomers, thus cis I is not unique to the mutant. Cis I is identified as 15‐cis‐ζ‐carotene by UV, visible, infrared and mass spectra; cis II may be the 13‐eis isomer. Since W3BUL also accumulates cis isomers of phytoene and phytofluene while the other carotenoids are trans, it is suggested that, in Euglena, ζ‐carotene is the point of isomerization from cis to trans in the biosynthetic pathway.
ELECTRON AND PROTON PHOTOTRANSPORTS IN A BILAYER MEMBRANE. ACIDIC PORPHYRIN AND SUPEROXIDE ION AS ΔpH SENSITIVE CHARGE CARRIERS
Authors: Hofmanova A. , Bienvenue E. , Seta P. , Momenteau M.
Published: January 2008

Abstract— Glycerolmonooleate planar bilayer membranes containing a zinc‐mesotetraphenyl l‐[3‐propionic acid] porphyrin separate two buffered aqueous phases, an oxidizing and a reducing one. Under illumination stationary photocurrents are recorded, that depend on the respective acidities of the aqueous phases. A strong enhancement is observed when the oxidizing solution is more acidic than the reducing solution. This phenomenon is attributed to the double role of the acidic porphyrin acting as an electron and a proton carrier. A second mechanism, also pH dependent, intervenes concurrently. The excited zinc‐porphyrin reduces oxygen and the resulting superoxide ion translocates through the membrane lipidic core.
PHOTOTOXICITY INDUCED BY HEMATOPORPHYRIN DERIVATIVE IN C5‐DEFICIENT, MAST CELL‐DEFICIENT AND LEUKOPENIC MICE
Authors: Lim Henry W. , Hagan Michael , Gigli Irma
Published: January 2008

Abstract— The phototoxic response induced by hematoporphyrin derivative and irradiation was evaluated in mice congenitally deficient in the fifth component of complement (C5), those congenitally deficient in mast cells, and in cyclophosphamide‐treated, leukopenic mice. Hematoporphyrin derivative, 10 mg/kg, was injected intraperitoneally, and 6 h later, the animals were irradiated (6.5 kj/m2 at396–407 nm). Phototoxicity was quantified by measurement of the increase in ear‐thickness. In control mice, at the end of the irradiation (0 h), an increase in the ear‐thickness of28–37% was noted; it reached a peak of51–81 % at 24 h. The phototoxic response in C5‐deficient mice was markedly suppressed both at 0 h and at 24 h (P vs control, < 0.02 and < 0.05, respectively), while mast cell‐deficient mice has a suppressed response at 24 h (P vs control, < 0.001). In both groups of mice, the intensity of dermal mononuclear and polymorphonuclear infiltrates was not different from that of the respective controls. The response in leukopenic mice was suppressed at both 24 h and 48 h (P < 0.001). These results indicate that intimate and complex interactions among the complement system, mast cells, and leukocytes are necessary for the complete manifestation of the phototoxic response.
ABSORPTION SPECTRA OF DEOXYRIBOSE, RIBOSEPHOSPHATE, ATP AND DNA BY DIRECT TRANSMISSION MEASUREMENTS IN THE VACUUM‐UV (150—190 nm) AND FAR‐UV (190—260 nm) REGIONS USING SYNCHROTRON RADIATION AS A LIGHT SOURCE
Authors: Ito Atsushi , Ito Takashi
Published: January 2008

Transmission measurements of 2‐deoxy‐D‐ribose, D‐ribose‐5‐phosphate, ATP and DNA at 5 nm intervals were made with thin films in the wavelength region between 150 nm and 260 nm using synchrotron radiation. ATP and DNA exhibited two peaks in the absorption spectra around 260 nm and 190 nm, and a steep increase below 170 nm, while ribose phosphate and deoxyribose only exhibited the increase below 190 nm with no appreciable absorption above 190 nm. Since adenine does not exhibit the increase of absorption below 180 nm, these results indicate that the absorption of the sugar‐phosphate group, rather than adenine, contributed to the increase below 170 nm in the absorption spectra of ATP and DNA.
LETHAL AND MUTAGENIC ACTION OF VACUUM‐AND FAR‐ULTRAVIOLET RADIATIONS ON DRY X174 PHAGE
Authors: Maezawa Hiroshi , Furusawa Yoshiya , Suzuki Kenshi
Published: January 2008

Killing and mutation of dry X174 phages (amber mutant) were investigated with vacuum‐UV (130, 150 and 190 nm) and far‐UV (254 nm) radiations. The sensitivity to killing was greatest at 130 nm; the sensitivity (in terms of energy fluence) at 130 nm was about 17 times higher than that at 150 nm. The reversion frequency of amber mutants to pseudo‐wild type at 190 nm was lower than at 254 nm. Comparison of the induction rate of revertants per survivor showed that mutagenicity after 130 nm radiation, which may raise the ionization process, and after X‐rays was similar.
PHYTOCHROME MODELS: PART 10. CONCENTRATION, SONICATION AND TEMPERATURE AFFECTING THE POPULATION OF THE GROUND‐STATE CONFORMERS OF BILIVERDIN DIMETHYL ESTER IN SOLUTION*
Authors: Al‐Ekabi Hussain , Tegmo‐Larson Inga‐Mai , Braslavsky Silvia E. , Holzwarth Alfred R. , Schaffner Kurt
Published: January 2008

UV‐vis absorption and fluorescence spectroscopy were used to show that in alcoholic solutions (methanol, ethanol, 2‐methylbutan‐1‐ol, and 2‐octanol) concentration, temperature, and sonication affect the relative populations of the more rigid stretched and the more flexible helically coiled conformers of biliverdin dimethyl ester. In aromatic solvents, e.g. toluene, no such effects could be detected. At concentrations larger than 3 10‐5M in the alcoholic solvents aggregates and monomeric coiled species prevail. Upon dilution, the fraction of stretched monomeric conformers increases. Heating and sonication at concentrations smaller than 3 10‐5M further and irreversibly increase the fraction of the stretched conformers. The activation parameters for this change are compatible with the assessment that no equilibrium is attained between the two families of conformers even after several hours at room temperature, since the barriers arc higher than kT at this temperature. The present results and those previously reported on the excited‐state processes of biliverdin dimethyl esters are explained on the basis of a scheme in which the eight possible ring B/C isomers of biliverdin dimethyl ester are interconverted through intra‐and intermolecular proton transfers, rotations around C‐C single bonds, and E‐Z photoisomerizations around C = C double bonds.
EXCITED‐STATE PROPERTIES OF DNA METHYLATED AT THE NV7 POSITION OF GUANINE AND ITS FREE FLUOROPHORE AT ROOM TEMPERATURE
Authors: Georghiou S. , Saim A. M.
Published: January 2008

The room‐temperature optical properties of calf thymus DNA, with about 75% of its guanine residues methylated at position N‐7, are compared with those of 7‐methyl GMP which has the same fluorophore. The fluorescence spectrum of the methylated guanine residues depends strongly on the excitation wavelength, shifting to the blue as the wavelength increases. The fluorescence quantum yield, corrected for the contribution to absorption by the other virtually nonfluorescent residues, exhibits a pronounced drop at long excitation wavelengths relative to that for excitation at 265 nm. The degree of fluorescence polarization exhibits a weak dependence on the excitation and emission wavelengths. For 7‐methyl GMP, the fluorescence spectrum is very weakly dependent on the excitation wavelength and its fluorescence quantum yield shows a moderate increase at long wavelengths. The degree of fluorescence polarization increases with increasing excitation wavelength particularly when monitoring the emission in the short wavelength region of the fluorescence spectrum. A pronounced drop of unknown origin is observed when exciting at 265 nm, which is not observed for methylated DNA. The methylated DNA data are interpreted in terms of a combination of (i) a heterogeneous environment of the methylated guanine residues, which results from sequence‐dependent stacking interactions, and (ii) transfer of excitation energy from the other residues to the fluorescing methylated guanine residues. From the values of the quantum yields and those of the decay times, which we have recently reported (Georghiou et al., 1985), the following values are obtained for the radiative, kt, and the sum of the nonradiative, σk1, rate constants for deexcitation of the excited states of methylated DNA and its free fluorophore: 1.6 × 108 s‐1 7 × 107 s‐1 and 5 × 1010 s‐lvs 6 × 109 s‐1. Because of energy transfer from the other residues. the kf value for the methylated guanine residues is overestimated but their σk1, value is not affected significantly and is by about an order of magnitude larger than that for 7‐methyl GMP, apparently because of stacking interactions.
A NEW HYPOTHESIS FOR THE TARGET IN PHOTOHEMOLYSIS: DIMERS OF THE BAND 3 PROTEIN
Authors: Pooler John P.
Published: January 2008

Abstract— Photohemolysis has been investigated extensively during the past 20 years, but the membrane target has eluded identification. It is proposed here that the target is the dimer of the band 3 anion exchange protein. This new hypothesis is based on three observations from the literature: (1) the kinetics of photohemolysis sensitized by exogenous sensitizers or induced by UV light obey a power dependence with light dose, with an exponent near two. From target theory this implies a two‐component target. (2) Band 3 molecules exist in the erythrocyte membrane as dimers. (3) Binding of eosin to band 3 via an isothiocyano group markedly increases its potency to sensitize hemolysis. Experiments with eosin isothiocyanate bound to band 3 show that lytic rate varies as the 1.45 power of light dose, and that the bound sensitizer bleaches considerably, thereby blunting the effectiveness of higher light doses.
LIGHT‐INDUCED FOURIER TRANSFORM INFRARED SPECTROSCOPIC INVESTIGATIONS OF THE INTERMEDIARY ELECTRON ACCEPTOR REDUTION IN BACTERIAL PHOTOSYNTHESIS
Authors: Nabedryk E. , Mäntele W. , Tavitian B. A. , Breton J.
Published: January 2008

Abstract— Molecular changes associated with the light‐induced reduction of the intermediary electron acceptor I (bacteriopheophytin, BPh) in bacterial photosynthesis were studied by means of Fourier transform infrared (FTIR) difference spectroscopy. Chromatophore membranes and reconstituted reaction centers (RCs) of Rhodopseudomonas viridis were prereduced with sodium dithionite and illuminated in order to trap photochemically the state I−. Fourier transform infrared spectra of these samples were recorded before, during and after illumination, with an accuracy better than 10−3 absorbance units. Difference spectra of I− in chromatophores and in RCs closely correspond to each other. In the carbonyl stretching frequency region between 1640 and 1750 cm−1, bands are tentatively attributed to a shift (from 1713 to 1683 cm−1) of a keto carbonyl group, a change of an acetyl carbonyl grou at 1656 cm−1 and a decrease in absorbance strength of ester carbonyl groups (at 1746 and 1732 cm−P) after reduction of I. These groups likely belong to the BPh molecule, although at least one of the ester carbonyls could be assigned to an amino acid side chain. The absence of strong bands in the amide I and amide II region excludes large protein conformational changes associated with I reduction.
SENSITIVITY OF HemA MUTANT Escherichia coli CELLS TO INACTIVATION BY NEAR‐UV LIGHT DEPENDS ON THE LEVEL OF SUPPLEMENTATION WITH δ‐AMINOLEVULINIC ACID
Authors: Tuveson R. W. , Sammartano Lauri J.
Published: January 2008

Abstract— Four strains carrying all four possible combinations of the alleles nur, nur+, uvr A6 and uvr A+ were transduced to hemA8. The hemA8 mutation blocks the synthesis of δ‐aminolevulinic acid (δ‐ALA), one of the first steps in the synthesis of porphyrin and, ultimately, cytochromes essential for aerobic respiration. The cells were grown either with or without δ‐ALA and treated with broad‐spectrum near‐ultraviolet light (NUV; 300–400 nm). hemA8 defective cells grown without δ‐ALA were resistant to inactivation by NUV while hemA8 cells were sensitive to such inactivation when supplemented with δ‐ALA. The sensitivity to NUV inactivation conferred by the nur gene was retained in the hemA8 derivatives. The sensitivity of such cells to NUV inactivation can be controlled by varying the level of δ‐ALA supplementation. The level of δ‐ALA supplementation did not influence the sensitivity of the cells to inactivation by far‐UV light (FUV; 200–300 nm). The near‐UV sensitivity of hemA+ cells was not significantly altered when grown with δ‐ALA suppiementation suggesting that endogenously formed δ‐ALA supports the normal, regulated level of porphyrin synthesis. These results can be interpreted to mean that porphyrin components of the respiratory chain in E. coli represent chromophores involved specifically in broad‐spectrum NUV inactivating events.
SPECTRAL OBSERVATION OF SINGLET MOLECULAR OXYGEN FROM AROMATIC ENDOPEROXIDES IN SOLUTION
Authors: Wilson Thérèse , Khan Ahsan U. , Mehrotra Mukund M.
Published: January 2008

Abstract— The characteristic near‐infrared emission band of O2 (1Δg) at 1.28 μm has been recorded from carbon tetrachloride solutions of the 1, 4‐endoperoxides of 1,4‐dimethyInaphthalene and 1, 4‐dimethoxy‐9.10‐diphenylanthracene undergoing thermal decomposition.
PHOTODYNAMIC EFFECTS INDUCED BY THE LUCIFERIN/LUCIFERASE SYSTEM
Authors: Van Steveninck J. , Boegheim J. P. J. , Dubbelman T. M. A. R.
Published: January 2008

Abstract— Luciferin from Photinur pyralis is an effective sensitizer, when excited with UV light in the range of 310–390 nm. With histidine or dithiothreitol as substrate, a type II photooxidation occurs, as judged from the inhibitory effect of sodium azide. During the ATP‐driven luciferin‐luciferase reaction, the resulting bioluminescence does not induce photodynamic reactions, as there is no overlap between the bioluminescence spectrum and the excitation spectrum of luciferin. However, in the presence of a second sensitizer, excitable by the bioluminescent light, photodynamic reactions can take place in the absence of exogenous light. As a consequence several photosensitizers can thus provoke photodynamic inactivation of luciferase.
EFFECT OF FAR‐UV AND NEAR‐UV RADIATION ON THE CELL SURFACE CHARGE OF THE PROTOZOAN
Authors: Filho Fernando Costa E Silva , Elias Cezar Antonio , de Souza Wanderley
Published: January 2008

Abstract— Cell electrophoresis was used to detect the effect of far‐UV or near‐UV radiation on the cell surface charge of the pathogenic protozoan Tritrichomonas foerus. Either far‐UV or near‐UV radiation interfered with the surface charge of T. foetus at fluences which inhibited cell growth by 50%. Both UV‐radiations induced a significant decrease on surface charge of T. foetus, as evaluated by measurement of its electrophoretic mobility (EPM). Determinations of EPM of protozoa in solution of low ionic strength indicated that the decrease in the EPM induced by far‐UV is much less pronounced than that observed for near‐UV or control cells.
PHOTOCHEMICAL MODIFICATIONS OF Lac REPRESSOR–II. TRYPTOPHAN PHOTOCHEMISTRY AS A PROBE IN STUDYING THE ALLOSTERIC BEHAVIOUR OF THE PROTEIN*
Authors: Spodheim‐Maurizot Melanie , Culard Franchise , Charlier Michel
Published: January 2008

Abstract Irradiation of lac repressor under aerobic conditions in the near UV region (295‐400 nm) decreases the Trp fluorescence of the protein. A total loss of fluorescence corresponds to the destruction of all tryptophanyl residues. Irradiation with light of wavelength between 250 and 400 nm quenches fluorescence completely when only half of the Trp residues are destroyed. An internal photodynamic effect, in which N‐formylkynurenine, a principal photoproduct of Trp, sensitizes further the destruction of the other Trp residues, accounts for our results. Experiments performed in the presence of sodium azide suggest that singlet oxygen is not involved in the destruction of Trp, but may be responsible for histidine degradation. Irradiating the repressor complexed with non‐operator E. coli DNA has the same effect on Trp residues as irradiating repressor alone. On the contrary, when repressor is complexed to lac operator, both tryptophanyl residues seem to be destroyed simultaneously. This indicates that binding of specific operator DNA at the DNA site induces changes in the environment of the tryptophanyl residues (mainly for Trp 220) which cannot further transfer its excitation energy to the photoproduct of the other Trp. A prolonged irradiation destroys the complex, leading to the same result observed for non‐specific complex or for repressor alone. These results are discussed in terms of the proximity of Trp from the inducer binding site and the allosteric behaviour of the repressor.
PHOTOSENSITIZED LYSIS OF RED BLOOD CELLS BY PHOTOTOXIC ANTIMALARIAL COMPOUNDS
Authors: Epling Gary A. , Sibley Michele T.
Published: January 2008

Abstract A family of 12 phototoxic quinolinemethanol antimalarials and three other non‐phototoxic clinically used compounds were irradiated in the presence of red blood cells to determine if the resulting hemolysis would be a reliable predictor of phototoxicity. The most phototoxic compounds from in vivo tests were also the most phototoxic in this study. Quinine caused little RBC lysis, paralleling its non‐phototoxicity in humans. The quinolinemethanol‐induced photohemolysis occurs both in the presence and absence of oxygen. Enriching the RBC with BHA and cholesterol was particularly effective at protecting the cells from photohemolysis. Other compounds offered some measure of protection, while superoxide dismutase and sodium azide, among others, afforded no protection.
INHIBITION OF NUCLEIC ACID SYNTHESIS IN CELLS EXPOSED TO 200 MICROMETER RADIATION FROM THE FREE ELECTRON LASER
Authors: Berns Michael W. , Bewley William
Published: January 2008

Vertebrate tissue culture cells were exposed to 200 um wavelength radiation (1CO W/cm2) from a free electron laser (FEL) of the electrostatic generator type. Cell cultures demonstrated no morphological alterations but a statistically significant (P .05) proportion of the cells exhibited inhibition of DNA synthesis. This study demonstrates the first biological effects of the FEL and the feasibility of performing biological investigations with this device.
CERTAIN SINGLET OXYGEN QUENCHERS AFFECT THE PHOTOREACTION BETWEEN 8‐MOP and DNA
Authors: Bordin Franco , Conconi Maria Teresa , Capozzi Alma
Published: January 2008

The effect of certain chemicals known as singlet oxygen quenchers on the photoreaction between 8‐MOP and DNA has been studied in vitro; sodium azide, l,4‐diazabicyclo‐(2,2,2)‐octane, p‐carotene and dimethylsolfoxide (used as a solvent) appeared to be capable of reducing significantly the 8‐MOP ability to induce both monoadducts and cross‐links in DNA. Therefore, these chemicals seem to be not useful in studying the singlet oxygen implication in the induction of biological effects of 8‐MOP sensitization.
IMPROVED QUANTITATION OF DNA‐PROTEIN CROSSLINKING CAUSED BY 405‐nm MONOCHROMATIC NEAR‐UV RADIATION IN HUMAN CELLS
Authors: Peak Jennifer G. , Peak Meyrick J. , Blazek Ed Robert
Published: January 2008

An improved alkaline elution analysis has been used to estimate the yield of DNA‐protein crosslinks induced in human P3 cells by monochromatic 405‐nm near‐ultraviolet radiation. Crosslinks are induced linearly over the fluence range studied, at a rate of 1.22 crosslinks per 1010 daltons per MJ m‐2± 0.066 (one standard error of the slope, N= 37). This rate is equivalent to 1360 crosslinks per cell genome per lethal event.
VERDINS: NEW PHOTOSENSITIZERS FOR PHOTODYNAMIC THERAPY
Authors: Morgan AlanR. , Rampersaud A. , Keck RickW. , Selman StevenH.
Published: January 2008

The in vivo cytotoxic effect of verdins was determined by histological methods, using the FANFT‐induced urothelial tumor line (AY‐27). The results indicate that the verdins may be good alternatives to hematoporphyrin derivative for photodynamic therapy.
QUANTITATION OF PYRIMIDINE DIMERS BY IMMUNOSLOT BLOT FOLLOWING SUBLETHAL UV‐IRRADIATION OF HUMAN CELLS
Authors: Wani Altaf A. , D'Ambrosio Steven M. , Alvi Nasir K.
Published: January 2008

An immunoslot blot assay was developed to detect pyrimidine dimers induced in DNA by sublethal doses of UV (254 nm) radiation. Using this assay, one dimer could be detected in 10 megabase DNA using 200 ng or 0.5 megabase DNA using 20 ng irradiated DNA. The level of detection, as measured by dimer specific antibody binding, was proportional to the dose of UV and amount of irradiated DNA used. The repair of pyrimidine dimers was measured in human skin fibroblastic cells in culture following exposure to 0.5 to 5 J m‐2 of 254 nm UV radiation. The half‐life of repair was approximately 24, 7 and 6 h in cells exposed to 0.5, 2 and 5 J m‐2 UV radiation, respectively. This immunological approach utilizing irradiated DNA immobilized to nitrocellulose should allow the direct quantitation of dimers following very low levels of irradiation in small biological samples and isolated gene fragments.
IRREVERSIBLE PHOTOBINDING TO SKIN CONSTITUENTS AFTER SYSTEMIC ADMINISTRATION OF CHLORPROMAZINE TO WISTAR RATS
Authors: Schoonderwoerd S. A. , Henegouwen G. M. J. Beijersbergen van
Published: January 2008

From in vitro experiments it is known that chlorpromazine binds to protein and DNA/ RNA upon UV‐irradiation. In the present study the possible photobinding of chlorpromazine (or its metabolites) in vivo was examined. Tritium labeled drug was administered intraperitoneally to female albino Wistar rats after which they were irradiated with light with maximum intensity at 310, 370 or 420 nm. After homogenization, unbound radioactivity in tissue of several organs was removed by dialysis. In the ears, eyes and skin of the back irreversibly bound radioactivity could be detected after irradiation with 310‐ and 370‐ but not with 420 nm light. Binding in the skin of the back after UVA irradiation was examined in more detail by separating epidermal lipids, DNA/RNA and proteins by a selective extraction/precipitation method. Radioactivity appeared to be bound to lipids and proteins but not to DNA/RNA.
INTERPRETATION OF THE ‘DICHROIC ORIENTATION’ OF PHYTOCHROME
Authors: Sugimoto Tohru , Ito Etsuro , Suzuki Hideo
Published: January 2008

The dichroic orientation of phytochrome observed both in the phytochrome‐mediated phototropism in Adiantum protonemata and in the phytochrome‐mediated chloroplast movement in Mougeotia were analyzed in terms of the orientation of the transition moment associated with the long‐wavelength absorption band, assuming that phytochrome, associated with the plasma membrane, rotates around the normal to the membrane. The orientation of the long‐wavelength transition moment of the phytochrome chromophore was calculated using the zero‐differential overlap approximation of the molecular orbital theory for ir‐electrons. The results indicate that the orientation of the long‐wavelength transition moment mainly changes later than 2 ms after red light excitation of Pr, and that the different dichroic orientations of Pr and Pfr can be attributed to the change in the angle of the long‐wavelength transition moment of phytochrome with the plasma membrane from 18o to 72o during phototransformation.
CHEMISTRY OF HEMATOPORPHYRIN‐DERIVED PHOTOSENSITIZERS
Authors: Kessel David , Thompson Paul , Musselman Brian , Chang C. K.
Published: January 2008

Abstract The hematoporphyrin‐derived tumor‐localizing preparation HPD consists of porphyrin monomers, which are‘inactive’(not tumor‐localizing), and a dimer/oligomer fraction which is responsible for the localizing phenomenon. In an organic solvent system, gel‐exclusion chromatography can separate HPD into fractions containing porphyrin monomers, dimers or oligomers. The relative amount of the dimer/oligomer fraction of HPD was a function of the pH of the mixture used to transform HP mono/di acetate to HPD. HPD prepared by the‘Upson’procedure contained dimer/oligomer linkages which are labile to 1 M NaOH (in 50% tetrahydrofuran), and are reduced by LiAlH4 to alcohols. These properties are characteristic of esters. But a commercial product, Photofrin II, contained approx. 50% of material refractory to both reagents described above. This behavior is characteristic of an ether linkage. These observations show that the nature of the linkage joining the porphyrin units is sensitive to conditions employed in HPD preparation. Tumor localization derives, in part, from affinity of these oligomers for plasma lipoprotein, and is associated with conformational alterations characteristic of these porphyrin‐porphyrin linkages.
THE PREPARATION OF RADIOLABELED PORPHYRINS and THEIR USE IN STUDIES OF PHOTODYNAMIC THERAPY
Authors: Vernon David I. , Brown Stanley B.
Published: January 2008

Abstract The use of radiolabeled HpD and DHE has potential importance in studies of the mechanism of localisation of these compounds in tumours and their mode of action in promoting light‐mediated cell damage. A number of methods of preparation of radiolabelled HpD and its components have been investigated. In a novel approach, we have developed methods for producing l4C‐ or 3H‐labelled protoporphyrin from photosynthetic algae. In this way haematoporphyrin and HpD can be produced with much higher specific radioactivity than has hitherto been available. We are using this radiolabelled material in several studies relating to PDT. One application has been the precise determination of the molar absorption coefficient of DHE (and other components of HpD) based on the fact that its specific radioactivity per porphyrin unit must be identical to that of the porphyrin from which it was prepared.
OPTIMIZATION OF PHOTODYNAMIC THERAPY LIGHT DOSE DISTRIBUTION and TREATMENT VOLUME BY MULTI‐FIBER INSERTIONS*
Authors: Bolin F. P. , Preuss L. E. , Taylor R. C.
Published: January 2008

Abstract The development of a methodology which optimizes the light dosage in tissue and improves the tailoring of the light with consequent sparing of normal adjacent tissue, will enhance the possibility for routine clinical photodynamic therapy. Specific, important goals for the clinical use of PDT are (a) efficient distribution of light flux to all parts of the tumor at sufficient level to effect eradication. (b) avoidance of the destruction of adjacent normal tissue, and (c) ability to tailor the treatment field, taking into account the varied shapes of tumors. Dividing the available power among several fibers is a promising method of achieving these goals. This is accomplished by (1) extending the volume, and by (2) increasing the flux spatial uniformity. This latter defocussing of the flux field is especially important because it may help to avoid concentrating a high intensity field from an implanted fiber near an essential structure of the normal tissue. The question arises how best to orient these multiple fibers for maximum coverage and uniformity. Hence, theoretical and experimental investigations were made to determine optimal fiber placements. A series of intensity distributions were generated using two and three fibers positioned at various separations within a postulated tumor volume. A criterion for uniformity was defined. Iterative computation produced optimal fiber separation for the given constraints. In the two fiber case, for small values of attenuation coefficient (μ. ≦ 0.2 mm−1), optimal fiber separation ranged from 0.6 to 0.7 times the diameter of the defined volume. For large values of attenuation coefficient (μ. ≧ 0.8), fiber separation was about 0.5 to 0.55 times the region diameter. The effects of fiber separation on volume of treatment were also determined. Maximal treatment volume was found to be dependent on the attenuation coefficient. With μ, = 0.50, a 40% increase in treatment volume over single fiber insertion of equivalent energy input was shown to be obtainable with a dual fiber configuration of 24 mm separation. Experiments using two fibers in vitro in mammalian tissue were performed to substantiate these results. The multiple fiber system is a promising method for delivering optimum light dosage to targeted PDT tissue.
TUMOR IMAGING WITH [111niIn]MONO‐DTPA‐ETHYLENEGLYCOL‐Ga‐DEUTEROPORPHYRIN
Authors: Nakajima S. , Hayashi H. , OHSHIMA K. , Yamazaki K. , Kubo Y. , Samejima N. , Kakiuchi Y. , Shindoh Y. , Koshimizu H. , Sakata I. , Yamauchi H.
Published: January 2008

Abstract Mono‐DPTA‐ethyleneglycol‐Ga‐deuteroporphyrin (MDEGD) was synthesized, by coordinating non‐radioactive Ga in the porphyrin ring and connecting DTPA (diethylene‐triamine‐N,N,N,N,N,‐pentaacetic acid) to its side chain. By labeling with 111In, chemicals for scintigraphy were developed. They were applied to Syrian golden hamsters with implanted pancreatic gland cancers and C57‐black mice with Lewis lung cancer to enable tumor imaging and biodistribution examination. A comparative study was also conducted with [67Ga]citrate. In the resultant data, [111In]MDEGD showed larger tumor/lung, tumor/kidney and tumor/blood ratio with [67Ga]citrate. The affinity of [nIn]MDEGD in inflammatory tissue was much lower than that of 67Ga citrate. [111In]MDEGD lost its photosensitivity.
INTRATUMOR TEMPERATURE MEASUREMENTS DURING PHOTODYNAMIC THERAPY
Authors: Mattiello James , Hetzel Fred , VANDENHEEDE Laura
Published: January 2008

Abstract Photodynamic therapy has been under investigation as a form of cancer treatment for a number of years. This procedure uses a light source of 630 nm to photoactivate the drug, Photofrin II. Researchers in the past have reported temperature increases during photodynamic therapy, by measuring surface temperature of the tumor or a single point temperature within the tumors. Three temperature points within the tumors have been measured in this study, to quantify the temperature distribution within the lesion. These temperatures were measured for photodynamic therapy treated mice and control mice receiving an exposure to the treatment light without the drug. The use of a filtered xenon arc lamp for the 630 nm light source produced larger temperature increases and thermal gradients within the tumors, than when an Argon dye laser was employed. This temperature increase is due in part to the broad wavelength output of this filtered lamp. When this thermal effect is present during PDT treatment, researchers have observed the development of shock proteins resulting in the induction of thermotolerance and resistance to subsequence hyperthermia treatments. Using the filtered arc lamp, mice receiving photodynamic therapy treatments displayed consistently higher temperature increases than control mice. The use of an argon dye laser, with sufficient air cooling of the tumor, can eliminate this thermal effect. It has been demonstrated that the use of filtered lamps produce thermal effects which cannot be eliminated, demonstrating that lasers should be the primary source of light used to photoirradiate animals for photodynamic therapy studies. The intratumor temperature increases should be documented at multiple positions, to determine the amount of thermotolerance which can be induced. When photodynamic therapy is followed with a subsequent hyperthermia treatment, this induced thermotolerance can then be taken into consideration.