bluuebunny/crossref_metadata_2025 huggingface dataset:
TIME‐RESOLVED STUDIES OF SINGLET‐OXYGEN EMISSION FROM L1210 LEUKEMIA CELLS LABELED WITH 5‐(N‐HEXADECANOYL)AMINO EOSIN. A COMPARISON WITH A ONE‐DIMENSIONAL MODEL OF SINGLET‐OXYGEN DIFFUSION AND QUENCHING
Authors: Baker Ayse , Kanofsky Jeffrey R.
Published: January 2008

Abstract— Time‐resolved measurements were made of near‐infrared emission from 5‐(N‐hexadecanoyl)amino‐eosinlabeled L1210 leukemia cells following pulsed‐laser excitation. The cells were suspended in phosphate‐buffered saline made with deuterium oxide solvent. A significant fraction of the emission occuring10–80 μs after the laser pulse was due to singlet oxygen. This singlet‐oxygen emission is believed to result from singlet oxygen generated near the cell‐membrane surface, where 5‐(N‐hexadecanoyl)amino eosin is known to concentrate, and then diffusing out into the buffer. The intensity and the kinetics of the experimentally observed singlet‐oxygen emission were in excellent agreement with the predictions of a theoretical one‐dimensional model of singlet‐oxygen diffusion and quenching.

During the10–80 μs time period studied, most of the singlet oxygen was located in the buffer. Thus, the use of water‐soluble singlet‐oxygen quenchers, such as histidine, provide one means of separating the singlet‐oxygen emission quenchers, such as histidine, provide one means of separating the singlet‐oxygen emission from other sources of light during this time interval.
INHIBITION OF PHTHALOCYANINE‐SENSITIZED PHOTOHEMOLYSIS OF HUMAN ERYTHROCYTES BY QUERCETIN
Authors: Ben‐Hur E. , Rosenthal I. , (Graziani) Y. Granot
Published: January 2008

Abstract—Photohemolysis of erythrocytes in the presence of aluminum phthalocyanine tetrasulfonate as a sensitizer is inhibited by quercetin. D2O (98.5%) stimulated photohemolysis regardless of quercetin presence, suggesting the participation of singlet oxygen in the process. Since it has been shown that this flavonoid reacts with singlet oxygen, the protective effect might be attributed, at least partially, to its competitive reaction with singlet oxygen. At the molecular level, the alterations of membrane proteins that escort the process of photohemolysis, such as cross‐linking of spectrin monomers and of other membrane proteins, were selectively inhibited by quercetin. This effect was qualitatively similar to that induced by NaF, suggesting that quercetin may, like NaF, also inhibit type I photooxidations, which contribute to hemolysis. The lipophilicity of quercetin seems to be an essential factor in the inhibition process; rutin, a water‐soluble 3‐rutinoside of quercetin, had only a negligible protective effect on photohemolysis.
ISOLATION OF BLEPHARISMIN‐BINDING 200 kDa PROTEIN RESPONSIBLE FOR BEHAVIOR IN Blepharisma
Authors: Matsuoka Tatsuomi , Murakami Yasunori , Kato Yoji
Published: January 2008

Abstract— The ciliated protozoan, Blepharisma, shows an avoidance reaction (step‐up photophobic response) in response to light stimulation. A profile of a gel‐permeation of a crude detergent‐solubilized sample of the cells resulted in several red‐colored fractions. Among these blepharismin‐containing fractions, the fractions III‐V did not contain amino acids. The peak of fraction II monitored by 580 nm absorbance was much smaller. A prominent peak appeared in fraction I, which contained a large amount of amino acids. The absorption spectrum of fraction I was well fitted to the action spectrum of the step‐up photophobic response, although free pigment (blepharismin) also fitted. Sodium dodecyl sulfate‐polyacrylamide gel electrophoresis of this fraction resulted in a thicker band corresponding to molecular mass of 200 kDa. These results suggest that the 200 kDa chromoprotein (blepharismin‐protein complex) is responsible for the step‐up photophobic response in Blepharisma. The absorption spectrum of free chromophore dissociated from the chromophore‐protein complex was identical to free red pigment termed blepharismin. The absorption spectrum of the other fractions agreed with that of thin‐layer chromatography‐purified red pigment, indicating that the pigments contained in these fractions are free pigment dissociated from the chromophore‐protein complex.
TEMPORAL and SPECTRAL SEPARATION OF SINGLET OXYGEN LUMINESCENCE FROM NEAR INFRARED EMITTING PHOTOSENSITIZERS
Authors: Näther Dirk U. , Gilchrist John R. , Gensch Thomas , Röder Beate
Published: January 2008

Abstract— The luminescence emission of singlet molecular oxygen (1O2) generated by bacteriopheophytin a, a near‐infrared‐emitting photosensitizer, was measured using a new high‐sensitivity spectrometer system for time‐ and spectral‐resolved near‐infrared detection. The instrument uses a low energy pulsed nitrogen laser (40 μJ per pulse) to excite the photosensitizer optically and is capable of a time resolution of 40 ns per data point and an instrument response function of 350 ns FWHM (full width at half maximum). The use of a low‐energy (and relatively low cost) source provides sufficient system sensitivity to measure time‐resolved spectra in the near infrared with high spectral and temporal resolution. The simultaneous detection, with high accuracy and repeatability, of both the temporal and spectral dependence of the photoprocesses of 1O2 generation, especially with near‐infrared‐emitting photosensitizers, may further stimulate the current intensive investigations concerning the activity of 1O2 to biomolecules.
LASER CROSS‐LINKING OF PROTEINS TO NUCLEIC ACIDS: PHOTODEGRADATION AND ALTERNATIVE PHOTOPRODUCTS OF THE BACTERIOPHAGE T4 GENE 32 PROTEIN
Authors: Kubasek William L. , Spann Dennis , Hockensmith Joel W.
Published: January 2008

Pulsed laser cross‐linking provides a means of introducing a covalent bond between proteins and the nucleic acids to which they are bound. This rapid cross‐linking effectively traps the equilibrium that exists at the moment of irradiation and thus allows examination of the protein‐nucleic acid interactions that existed. Laser irradiation may also induce photodestruction of protein and we have used the bacteriophage T4 gene 32 protein to investigate this phenomenon. Our results show that both nonspecific and specific photoproducts can occur, specifically at wavelengths where the peptide backbone of proteins is known to absorb. These results demonstrate that nonspecific photodegradation can be correlated with the formation of a specific photodegradation product. The formation of this product was monitored to show that product yield is nonlinearly dependent on laser power and wavelength. We have also investigated an unexpected photoproduct whose formation is dependent on the length of the polynucleotide to which the gene 32 protein binds and that further demonstrates the complexities of analyzing protein‐nucleic acid interactions through the use of UV laser cross‐linking. These data provide essential information for the establishment of appropriate conditions for future studies that use UV cross‐linking of protein‐nucleic acid complexes.
QUANTIFICATION OF THE SOLVENT EFFECTS ON THE TRIPLET QUANTUM YIELD OF PSORALEN BY THE “LINEAR SOLVATION ENERGY RELATIONSHIP”
Authors: Melo Teresa Sae , Bazin Marc , Ronfard‐Haret Jean‐Claude , Santus René
Published: January 2008

Triplet formation quantum yields (Φτ) of psoralen in a set of 17 pure solvents ranging from n‐hexane to water and in dioxane: water mixtures were obtained by nanosecond laser flash photolysis. The triplet yield increases with solvent polarity. The extremum values are 0.009 and 0.545 in n‐hexane and water, respectively. Good correlations of the experimental Φτ values with empirical “polarity” scales (Dimroth/Reichardt's ET [30], Kamlet/Taft's solva‐tochromic parameters β, and α, and Swains acity/basity AS/BS) were obtained: Ln(φT‐1 ‐ 1) = 8.86 ‐ 0.143ET(30) Ln(φT‐1 ‐ 1) = 4.40 ‐ 2.34τ ‐ 1.70α Ln(φT‐1 ‐ 1) = 4.65 ‐ 3.72As ‐ 1.12Bs The results are discussed in terms of the sensitivity of psoralen triplet quantum yield to solvent polarity and hydrogen‐bonding abilities.
ABSORPTION AND FLUORESCENCE SPECTROSCOPIC STUDIES ON DIMERIZATION OF CHLOROALUMINUM (III) PHTHALOCYANINE TETRASULFONATE IN AQUEOUS ALCOHOLIC SOLUTIONS
Authors: Yoon Minjoong , Cheon Youngjin , Kim Dongho
Published: January 2008

Dimerization of chloroaluminum (III) phthalocyanine tetrasulfonates (AIPCS) has been observed in different aqueous alcoholic solvents at room temperature by absorption and fluorescence spectroscopic methods. Both absorption and fluorescence spectral bands of the dimer are red shifted by ca 550 cm‐1 from the monomer Q bands in the corresponding spectra, suggesting that the interaction energy between the two monomer subunits is very weak. The fluorescence lifetime of the dimer is longer (ca 9.5 ns) than that of the monomer (ca 7–8 ns). These spectral behaviors of AIPCS dimer contrast with those of transition‐metallaloid phthalocyanine dimers, which usually have a nonfluorescent face‐to‐face stacking conformation. The dimer fluorescence is interpreted to be due to the fact that the lowest excited singlet state of the dimer is lower in energy than a charge‐resonance state, based on the excitoncoupling theory applied to the face‐to‐face slipping conformation. The dimerization constant determined spectrometrically decreases with an increase of water content in the aqueous alcoholic solution. Propanol and ethanol have been observed to be more effective than methanol in promoting dimerization. These results indicate that a specific interaction of water with AIPCS plays an important role in the inhibition of dimerization of AIPCS.
THE CHLOROPHYLL a AGGREGATE ABSORBING NEAR 685 nm IS SELECTIVELY FORMED IN AQUEOUS TETRAHYDROFURAN*
Authors: Uehara Kaku , Hioki Yuko , Mimuro Mamoru
Published: January 2008

An aqueous solution of 2–12% (vol/vol) tetrahydrofuran (THF) induced the selective aggregation of chlorophyll a (Chl a) to form a novel species, A‐685, absorbing near 685 nm. The formation of A‐685 was closely correlated with a decrease in water activity of the solution. A Raman spectrum of the Chl a species formed in the presence of 6% THF suggests a unique interaction among Chl a, solvent THF and water molecules to give a stacked aggregate (Chl a.THF.H2O.THF.Chl a). The circular dichroic spectrum of the Chl a species formed in the 6% THF aqueous solution showed an intense signal that had negative and positive wings with about 100‐fold larger molar ellipticity for the A‐685 than for monomer. However, Chl a', the C10 epimer of Chl a, and chlorophyllide, with a phytyl chain replaced by an ethyl group, did not form A‐685 in 6% THF. These clearly indicate that 10‐methylcarboxylate and the phytyl chain have a significant role in stabilizing A‐685. A possible structure for A‐685 is proposed as a novel in vitro model for the P‐680 Chl a dimer.
A PHOTOPHYSICAL STUDY OF SOLVATOCHROMIC PROBE 6‐PROPIONYL‐Z(N,N‐DIMETHYLAMINO)NAPHTHALENE (PRODAN) IN SOLUTION
Authors: Bunker Christopher E. , Bowen Tracey L. , Sun Ya‐Ping
Published: January 2008

A photophysical study of 6‐propionyl‐2‐(N,N‐dimethylamino)naphthalene (PRODAN) in room‐temperature solutions under various conditions is reported. The results show no unusual photophysical properties, except for an extremely large solvatochromic shift of PRODAN fluorescence spectrum. The previously reported extra blue emission band for PRODAN in an aqueous solution is identified to be due entirely to trace water‐soluble impurities in the sample. The excited‐state dipole moment of PRODAN is determined based on solvatochromic results using a known twisted intramolecular charge transfer (TICT) molecule p‐(N,N‐diethylamino)ethylbenzoate (DEAEB) as a reference to probe specific solute‐solvent interactions. The possibility of TICT state formation in PRODAN is discussed, and a solvation equilibrium mechanism is proposed to account for the photophysical behavior of PRODAN.
AN ANIMAL MODEL AND NEW PHOTOSENSITIZERS FOR PHOTOPHERESIS
Authors: Iperen H. P. Van , Henegouwen G. M. J. Beijersbergen van
Published: January 2008

Recently, photopheresis was introduced as a therapy for several T cell‐mediated disorders. The treatment results in a specific immune response against the pathogenic clone of T cells involved. However, although promising there is controversy concerning the use of photopheresis in some diseases, e.g. systemic sclerosis. One of the problems is that there is not yet sufficient insight into the mechanism underlying the therapy. This lack of knowledge is partly caused by the fact that there are no easy‐to‐handle animal models available for photopheresis.

This report describes such a model—a Wistar‐derived rat with contact hypersensitivity (CHS); a T cell‐mediated immune response. White blood cells from CHS rats were simultaneously exposed to 8‐methoxypsoralen (8‐MOP) and ultraviolet A radiation (UVA) and subsequently intravenously injected into other syngeneic rats suffering from the same disorder. This treatment appears to be very efficacious in suppressing the immunological response against the applied contact allergen, 2,4‐dinitroAuorobenzene (DNFB). In addition, the generated suppression of CHS is highly specific and transferable. Furthermore, drugs other than 8‐MOP (chlordiazepoxide, nitrofurantoin and chlor‐promazine) also appear to be active in our model.
ENHANCED RESPONSE TO DAUNOMYCIN OF NORMAL, TUMOR AND METASTATIC CELL LINES via DRUG PHOTO ACTIVATION
Authors: Andreoni Alessandra , Colasanti Alberto , Kisslinger Annamaria , Mastrocinque Mlchele , Portella Giuseppe , Riccio Patrizia , Roberti Giuseppe
Published: January 2008

Abstract— We have compared the cytotoxicity of daunomycin in vitro to highly differentiated normal epithelial cells (Fisher rat thyroid cells, FRTL‐5) and to two neoplastic cell lines, a thyroid carcinoma (TK‐6) and its lung metastasis (MPTK‐6). Whereas the cell lines are equally sensitive to the drug in the dark, if irradiated during incubation with daunomycin (86 J/cm2 at 488 nm), they become more and differently sensitive. Namely, the drug doses producing 50% mortality decrease by factors of about 22, 28 and 16 for FRTL‐5, TK‐6 and MPTK‐6 cell lines, respectively. This result correlates with differences in drug uptake and resistance observed in the normal and neoplastic cell lines.
THE EFFECTS OF ASPIRIN ON MICROVASCULATURE AFTER PHOTODYNAMIC THERAPY
Authors: Taber Scott W. , Wieman T. Jeffery , Fingar Victor H.
Published: January 2008

Abstract— The effects of aspirin (acetylsalicylic acid: ASA) on vessel behavior and tumor response were measured during and after photodynamic therapy (PDT). Changes to vessel constriction, macromolecular leakage, tumor interstitial pressure, and tumor response were examined. Animals were randomly placed into treatment groups and injected with 0–25 mg/kg Photofrin® and given 0 or 135 J/cm2 light treatment. The light treatment was standardized to 75 mW/cm2 at 630 nm over a 30 min treatment interval (135 J/cm2). The treatment groups were further subdivided to receive Photofrin® alone or Photofrin® plus 100 mg/kg ASA. A cremaster muscle model in Sprague‐Dawley rats was used to directly observe microvascular response and changes in vessel permeability to macromolecules. A tumor interstitial pressure model was designed to measure pressure changes in a chondrosarcoma tumor over time. This model indirectly measures macromolecular leakage, among other factors, in the tumor tissue. Groups of 10–20 rats were implanted subcutaneously with chondrosarcoma and were subjected to PDT to assess tumor response to the various treatments. Statistically significant differences in vessel leakage and changes in interstitial pressure were observed between animals given ASA plus PDT as compared to animals given PDT alone. The administration of ASA significantly inhibited venule leakage of albumin and reduced increases in interstitial pressure after treatment. The use of ASA had no effect on vessel constriction or tumor response after PDT. These findings suggest that the increases in vessel permeability observed during and after PDT, using Photofrin®, do not significantly contribute to tumor response.
PHOTOLYSIS OF SUBSTITUTED NAPHTHALENES ON SiO2 AND Al2O3
Authors: Barbas John T. , Sigman Michael E. , Buchanan A. C. , Chevis Eddie A.
Published: January 2008

Abstract— Photolysis of naphthalene on the surface of SiO2 under an atmosphere of air produces phthalic acid as the only major photoproduct, accounting for 49%o of the consumed naphthalene. Photolysis on Al2O3 also produces phthalic acid, in 31% yield. Photolysis of 1 ‐methylnaphthalene on SiO2 proceeds under similar conditions to produce 2‐acetylbenzoic acid (35%) as the major photoproduct with the production of a small amount of I‐naphthaldchyde (6%). 1‐Cyanonaphthalene does not photooxidize under similar conditions. The presence of oxygen is necessary for the photodecomposition of naphthalene and 1‐methylnaphthalene to proceed. Superoxide formed from the photolysis of naphthalene at the SiO2/air interface is readily observed by electron paramagnetic resonance spectroscopy. In the absence of naphthalene no superoxide is observed. A mechanism involving electron transfer from the S1 state of the naphthalene to O2 is proposed on the basis of these observations and related literature precedent.
In vivo FLUORESCENCE KINETICS OF PHTHALOCYANINES IN A SKIN‐FOLD OBSERVATION CHAMBER MODEL: ROLE OF CENTRAL METAL ION AND DEGREE OF SULFONATION
Authors: van Leengoed H. L. L. M. , van der Veen N. , Versteeg A. A. C. , Ouellet R. , van Lier J. E. , Star W. M.
Published: January 2008

Abstract— The fluorescence pharmacokinetics of a series of metallosulfophthalocyanines, chelated with either aluminum or zinc and sulfonated to different degrees, was studied by fluorescence measurements in vivo. Dyes were administered systemically to female WAG/RIJ rats with an isogeneic mammary carcinoma transplanted into the subcutis in a transparent observation chamber located on their backs. Following an intravenous injection of 2.5 μmol/ kg of the dye, fluorescence dynamics was observed up to 7 h postinjection. The phthalocyanines were excited at 610 nm with a power density of 0.1 mW/cm2 without causing photodynamic damage to the vasculature. Fluorescence was detected above 665 nm using a fluorescence imaging system based on an image intensifier. Dye retention in the blood vessels and tumor tissue was expressed as ratios relative to the fluorescence signal of the surrounding subcutaneous tissue. Phthalocyanincs chelated with aluminum gave the highest fluorescence signal with tumor‐over‐subcutis ratios of up to a value of 4. The zinc complexes exhibited the highest vascular‐over‐subcutis ratios with maximum values exceeding a value of 6. They also displayed the longest retention times in the vascular system of well over 7 h. Overall, decreasing the degree of sulfonation of the metallophthalocyanines results in lower tumor‐over‐normal tissue fluorescence ratios, and furthermore aluminum‐based dyes seem superior tumor localizers over zinc‐based dyes. The advantages of phthalocyanines over porphyrins with respect to tumor localization and photodynamic therapy are discussed.
SPECTROSCOPIC STUDIES OF CUTANEOUS PHOTOSENSITIZING AGENTS. XVIII. INDOMETHACIN
Authors: Dabesrani Reza , Sik Robert H. , Davis Donald G. , Dubay George , Chignell Colin F.
Published: January 2008

Abstract—The photochemistry, photophysics, and photosensitization (Type I and II) of indomethacin (IN) (N‐[p‐chlorobenzoyl]‐5‐methoxy‐2‐methylindole‐3‐acetic acid) has been studied in a variety of solvents using NMR, high performance liquid chromatography‐mass spectroscopy, transient spectroscopy, electron paramagnetic resonance in conjunction with the spin trapping technique, and the direct detection of singlet molecular oxygen (lO2) luminescence. Photodecomposition of IN (λex> 330 nm) in degassed or air‐saturated benzene proceeds rapidly to yield a major (2; N‐[p‐chlorobenzoyl]‐5‐methoxy‐2‐methyl‐3‐methylene‐indoline) and a minor (3; N‐[p‐chlorobenzoyl]‐5‐methoxy‐2, 3‐dimethyl‐indole) decarboxylated product and a minor indoline (5; 1‐en‐5‐methoxy‐2‐methyl‐3‐methylene‐in‐doline), which is formed by loss of the p‐chlorobenzoyl moiety. In air‐saturated solvents two minor oxidized products 4 (N‐[p‐chlorobenzoyl]‐5‐methoxy‐2‐methylindol‐3‐aldehyde) and 6 (5‐methoxy‐2‐methyl‐indole‐3‐aldehyde) are also formed. When photolysis was carried out in18O2‐saturated benzene, the oxidized products 4 and 6 contained18O, indicating that oxidation was mediated by dissolved oxygen in the solvent. In more polar solvents such as acetonitrile or ethanol, photodecomposition is extremely slow and inefficient. Phosphorescence of IN at 77 K shows strong solvent dependence and its emission is greatly reduced as polarity of solvent is increased. Flash excitation of IN in degassed ethanol or acetonitrile produces no transients. A weak transient is observed at 375 nm in degassed benzene, which is not quenched by oxygen. Irradiation of IN (λex> 325 nm) in N2‐gassed C6H6in the presence of 5, 5‐dimethyl‐1‐pyrroline‐N‐oxide (DMPO) results in the trapping of two carbon‐centered radicals by DMPO. One adduct was identified as DMPO/.COC6H4‐p‐CI, while the other was probably derived from a radical formed during IN decarboxylation. In air‐saturated benzene, (hydro) peroxyl and alkoxyl radical adducts of DMPO are observed. A very weak luminescence signal from1O2at 1268 nm is observed initially upon irradiation (λex= 325 nm) of IN in air‐saturated benzene or chloroform. The intensity of this1O2signal increases as irradiation is continued suggesting that the enhancement in1O2yield is due to photoproduct(s). Accordingly, when 2 and 3 were tested directly, 2 was found to be a much better sensitizer of1O2than IN. In air‐saturated ethanol or acetonitrile no IN1O2luminescence is detected even on continuous irradiation. The inability of IN to cause phototoxicity may be related to its photo stability in polar solvents, coupled with the low yield of active oxygen species (1O2, O2−‐) upon UV irradiation.
A SPIN TRAPPING STUDY OF THE PHOTOCHEMISTRY OF 5,5‐DIMETHYL‐1‐PYRROLINE N‐OXIDE (DMPO)
Authors: Chignell Colin F. , Motten Ann G. , Sik Robert H. , Parker Carol E. , Reszka Krzysztof
Published: January 2008

The photochemistry of 5,5‐dimethyl‐l‐pyrroline N‐oxide (DMPO) has been studied in benzene, cyclohexane and aqueous buffer solutions (pH 7.4) by means of electron paramagnetic resonance (EPR) and the spin trapping technique. Ultraviolet irradiation of DMPO in aqueous buffer with unfiltered UV radiation from a Xe arc lamp results in photoionization of the spin trap and the generation of the DMPO cation radical, DMPO+. The aqueous electron, eaq−, was trapped by DMPO and detected as the DMPO/H adduct. The DMPO+‐ reacted with the water to yield the DMPO/OH adduct. Ultraviolet irradiation of DMPO in nitrogen‐saturated benzene gave an unidentified carbon‐centered DMPO adduct that was replaced by hydroperoxyl and alkoxyl adducts of DMPO when oxygen was present. Experiments employing 17O2 gas indicated that the oxygen in the DMPO alkoxyl adduct was derived from molecular oxygen. However, UV irradiation of DMPO in cyclohexane yielded the cyclohexyl and cyclohexyloxyl adducts of DMPO in nitrogen‐saturated and air‐saturated solutions, respectively. These observations suggest that in aprotic solvents UV irradiation of DMPO generates a carbon‐centered radical (R−), derived from the trap itself, which in benzene reacts with oxygen to yield an alkoxyl radical (RO−), possibly via a peroxyl radical (ROO−) intermediate. In cyclohexane R− abstracts a hydrogen atom from the solvent to yield the cyclohexyl radical in the absence of oxygen and the cyclohexyloxyl radical in the presence of oxygen. These findings indicate that when DMPO is used as a spin trap in studies employing short‐wavelength UV radiation (λ < 300 nm) the photochemistry of DMPO cannot be ignored.
ISOLATION AND CHARACTERIZATION OF PROTEINS FROM THE PUTATIVE PHOTORECEPTOR FOR POSITIVE PHOTOTAXIS IN THE DINOFLAGELLATE, Peridinium gatunense NYGAARD
Authors: Liu Shi‐Mei , Häder Donat‐P.
Published: January 2008

Abstract –A chromoprotein fraction was isolated from the freshwater dinoflagellate, Peridinium gatunense, which is assumed to contain the photoreceptor chromoproteins for phototaxis, as its absorption and fluorescence spectra correspond to the action spectrum for phototaxis. The chromoproteins of this fraction were separated by anion‐exchange column chromatography and further by sodium dodecylsulfate gel electrophoresis.
CYTOKINE RELEASE BY PERIPHERAL BLOOD MONONUCLEAR CELLS IS AFFECTED BY 8‐METHOXYPSORALEN PLUS UV‐A
Authors: Neuner Peter , Charvat Birgit , Knobler Robert , Kirnbauer Reinhard , Schwarz Agatha , Luger Thomas A. , Schwarz Thomas
Published: January 2008

Psoralen plus UV‐A (PUVA) is an effective therapy for psoriasis but also for other inflammatory dermatoses. The precise mechanisms of action, however, are not absolutely clear. Therefore, the effect of PUVA on the release of the proinflammatory cytokines interleukin (IL)‐1, IL‐6, IL‐8 and tumor necrosis factor alpha (TNFα) was studied. Peripheral blood mononuclear cells (PBMC) obtained from humans were incubated with 8‐methoxypsoralen (8‐MOP) and exposed to UV‐A (20 kJ/m2). This treatment resulted in a significant reduction of IL‐6 and IL‐8 amounts in the supernatants. In addition, an inhibition of IL‐1β and TNFα production by lipopolysaccharide (LPS)‐stimulated PBMC was observed upon PUVA treatment. Accordingly, northern blot analysis showed decreased levels of mRNA encoding for IL‐1β, IL‐6, IL‐8 and TNFα in PUVA‐treated PBMC. Finally PBMC were obtained from psoriatics undergoing oral photochemotherapy before the beginning and after completion of treatment. The PBMC collected after PUVA spontaneously produced significantly less IL‐6 and IL‐8 in comparison to the respective samples obtained before therapy. A similar suppression of IL‐1β and TNFα by in vivo PUVA was found in LPS‐stimulated PBMC. The present data demonstrate that PUVA both in vitro and in vivo suppresses the production of the proinflammatory cytokines IL‐1β, IL‐6, IL‐8 and TNFα by PBMC. Because these cytokines are important in the mediation of inflammatory reactions, one may speculate that the inhibitory effects could contribute to the antiinflammatory activity of PUVA.
ALKALI‐LABILE PHOTOLESIONS MAPPING TO PURINE SITES IN ULTRAVIOLET‐IRRADIATED DNA
Authors: Hejmadi Vidyasagar , Stevenson Clarke , Kumar Shiv , Davies R. Jeremy H.
Published: January 2008

Gel sequencing experiments with the 5′‐ and 3′‐end‐labeled oligonucleotides d(A3GA4GA5GA6GA3G) and d(AT) 10 have demonstrated that dimeric adenine photoproducts and thymine‐adenine photoadducts constitute alkali‐labile lesions in UV‐irradiated DNA. On treatment with hot piperidine, DNA strand breakage occurs predominantly at the sites of 5′‐adenines in the dimeric photoproducts and of 3′‐adenines in the thymine‐adenine photoadducts. With 5′‐end‐labeled oligonucleotides of mixed sequence, major UV‐induced loci for alkaline cleavage map to purine bases flanked on their 5′‐side by two pyrimidines. This behavior does not arise from enhanced photoreactivity of purines in this sequence context as has been inferred from photofootprinting studies. Instead, as shown by 3′‐labeling and selective substitution with 5‐methylcytosine, it results from the anomalous electrophoretic mobility of 5′‐end‐labeled fragments produced by alkaline cleavage of DNA at adjacent pyrimidine (6‐4) pyrimidone photoproducts.
SOLVENT EFFECTS ON TRIPLET‐STATE BACTERIOCHLOROPHYLL a AS DETECTED BY TRANSIENT RAMAN SPECTROSCOPY AND THE ENVIRONMENT OF BACTERIOCHLOROPHYLL a IN THE LIGHT‐HARVESTING COMPLEX OF Rhodobacter sphaeroides R26
Authors: Nishizawa Ei‐ichi , Limantara Leenawaty , Nanjou Noriyuki , Nagae Hiroyoshi , Kakuno Tomisaburo , Koyama Yasushi
Published: January 2008

The frequency of BChl that was bound to the light‐harvesting complex (LHC) of Rhodobacter sphaeroides R26 was found to be 1598 cm‐1, a result which suggests that a pair of BChl molecules form a dimer in the LHC in the T1 state.
REACTION AND QUENCHING OF SINGLET MOLECULAR OXYGEN WITH ESTERS OF POLYUNSATURATED FATTY ACIDS
Authors: Tanielian C. , Mechin R.
Published: January 2008

Abstract The rate constants for the reactive (kR) and unreactive (kQ) interaction of singlet molecular oxygen with three esters of polyunsaturated fatty acids (PUFA: cis‐methyl oleate, MO; cis‐methyl linoleate, MLA and cis‐ethyl linolenate, ELN) are determined. The values of the ratio kQ/kR are 0.51, 0.26 and 0.20 for MO, MLA and ELN, respectively. This variation results principally from that of kR because the values of kQ are only slightly different (1.24 × 104M−1 s−1 for MO and ∼1.0 × 104M−1 s−1 for MLA and ELN). It is shown that the rate constant kQ characterizes mainly an interaction with the unreactive part of the molecule rather than with the double bonds (solventlike quenching).

Contrary to the already reported case of 1,5‐polyenes for which kQ <<kR, the present results and those obtained from a number of literature data show that for PUFA and their esters, neither kR+ kQ nor kR are proportional to the total number of double bonds or of methylene groups adjacent to the double bonds. Instead, a linear correlation is observed by plotting kRvs the number of methylene groups adjacent to two double bonds. It is deduced that contrary to a common assumption, biallylic hydrogens have a reactivity higher than that of singly allylic hydrogens (reactivity ratio 1.19).

The consequence of this result on the estimation of relative contributions of singlet oxygen and radical mechanisms to oxidation processes is discussed. Moreover, the whole of these results allows prediction of the values of kR and kQ for all unsaturated fatty acids (and their esters) of similar structure.
TUMOR‐LOCALIZING FLUORESCENT DIAGNOSTIC AGENTS WITHOUT PHOTOTOXICITY
Authors: Takemura Takeshi , Nakajima Susumu , Sakata Isao
Published: January 2008

In order to develop tumor‐localizing fluorescent diagnostic agents without phototoxicity, various heterodimers linked by some spacers between a chlorine derivative and its Mn or Cu complex were synthesized. The representative agent of them was named HAT‐D01 and has a molecular formula of m‐phthalyl‐{[13,17‐bispropanoic acid‐3‐ethenyl‐8‐formylethylidene‐7‐hydroxy‐2,7,12,18‐tetramethyl‐porphyrinate]‐manganese (III)}‐[3′‐ethenyl‐8′‐formylethylidene‐7′‐hydroxy‐2′,7′, 12′, 18′‐tetramethyl‐porphine‐13′, 17′‐bispropanoyl aspartic acid]‐bishydrazone.
CURCUMIN‐DERIVED TRANSIENTS: A PULSED LASER AND PULSE RADIOLYSIS STUDY
Authors: Gorman A. A. , Hamblett I. , Srinivasan V. S. , Wood P. D.
Published: January 2008

Abstract In this paper we report a time‐resolved investigation of transients derived from curcumin, which may be intimately involved in the processes leading to its biological activity. Fluorescence and triplet quantum yields are respectively 0.06 and 0.11. The high percentage of internal conversion is proposed to proceed via H‐transfer within the thermodynamically favored enol structure of what is formally a 1,3‐diketone. The triplet energy (191 ± 2 kJ mol−1), natural lifetime (1.5 μs) and self‐quenching rate constant (5.0 × 108 L mol−1 s−1) have been determined. Oxygen quenching of the triplet leads to the production of singlet oxygen with unit efficiency. Curcumin quenches the latter species very inefficiently (2.5 × 105 L mob−1 s−1). The curcumin radical has been produced via three mechanistically distinct methods. This species is unreactive toward oxygen but is repaired by vitamins C and E and anthralin.
POTENCY AND SELECTIVE TOXICITY OF TETRA(HYDROXYPHENYL)‐ AND TETRAKIS(DIHYDROXYPHENYL)PORPHYRINS IN HUMAN MELANOMA CELLS, WITH AND WITHOUT EXPOSURE TO RED LIGHT
Authors: James David A. , Arnold Dennis P. , Parsons Peter G.
Published: January 2008

Abstract A series of tetra(hydroxyphenyl)‐(2‐, 3‐ and 4‐hydroxy; THPP) and tetrakis(dihydroxyphenyl)porphyrins (2,3‐, 2,4‐, 2,5‐, 3,4‐, and 3,5‐dihydroxy; TDHPP) was synthesized and tested for toxicity in HeLa cells and human melanoma cell lines. Irradiation of drug‐treated cells with >600 nm light greatly increased the toxicity of all drugs except the 2,5‐ and 3,5‐TDHPP. The THPP were more toxic than TDHPP in all cell lines, with or without irradiation; of the dihydroxy derivatives, the 3,4‐ and 2,4‐isomers were the most toxic and the 2,5‐isomer was the least toxic. The MM96E melanoma cell line, shown previously to be sensitive to hydrogen peroxide and superoxide ion, was not hypersensitive to killing by any of the above agents. HeLa cells, which lacked glutathione‐S‐transferase activity, were sensitive to the 4‐ and 2,3‐isomers after irradiation; similar amounts of all drugs were taken up by HeLa cells. The pigmented melanoma cell line MM418, resistant to UV‐B and in situ‐generated hydrogen peroxide but sensitive to glutathione (GSH) depletion, was found to be resistant to the 2,3‐isomer (no irradiation) and sensitive to the 3,4‐isomer. The results indicate that (1) phototoxicity in these phenylporphyrins is not mediated by superoxide ions or hydroxyl radicals, (2) toxicity is dependent on the orientation of the hydroxy groups, (3) GSH transferase and possibly GSH itself offer protection from the 4‐ and 3,4‐derivatives, respectively, and (4) the 3,4‐derivative and analogues of similar selectivity should be evaluated further for the treatment of primary melanoma.
THE EFFECTS OF GROWTH‐INHIBITING TREATMENTS ON PHOTOREPAIR IN CULTURED FISH CELLS
Authors: Kondo Mariko , Mitani Hiroshi , Shima Akihiro
Published: January 2008

Abstract Goldfish cells (RBCF‐1) cultured at different cell densities were harvested and their photorepair (PR) abilities were examined in terms of survival. Photorepair ability gradually increased during the phase of logarithmic growth, reaching a maximum in cells at the confluent state. This enhancement of PR ability disappeared 12 h after replating of cells in fresh medium. A number of growth‐inhibiting treatments (serum depletion, UVC, hydroxyurea [HU], change in incubation temperature) were tested for their ability to induce PR. The treatment of cells with HU and serum depletion induced PR while the other treatments did not. The increase in the ability to perform PR after treatment with HU or serum depletion returned to normal levels more rapidly than that after fluorescent light treatment.
ACCESSORY CELL ABILITY OF LANGERHANS CELLS FOR SUPERANTIGEN IS RESISTANT TO ULTRAVIOLET‐B LIGHT
Authors: Tokura Yoshin , Yagi Hiroaki , Hashizume Hideo , Yagi Junji , Furukawa Fukumi , Takigawa Masahiro
Published: January 2008

Abstract We examined the effects of ultraviolet‐B (UVB) irradiation on the accessory cell ability of Langerhans cells (LC) to induce a T‐cell response to a superantigen, staphylococcal enterotoxin B (SEB). The ability of LC‐enriched epidermal cells (LC‐EC) to evoke a T‐cell response to SEB was retained at the doses of UVB (up to 40 mJ/ cm2) that profoundly affected the antigen‐presenting function of LC‐EC for a hapten, trinitrophenyl (TNP), and a protein antigen, conalbumin. Thus, the LC accessory function for superantigens is more resistant to UVB irradiation than that for ordinary antigens. This UVB resistance is presumably due to no requirement of antigen processing for superantigens as chemically fixed or chloroquine‐treated LC‐EC still retained their ability to induce T‐cell responses to SEB. Higher doses of UVB (more than 60 mJ/cm2) reduced the accessory cell ability of LC‐EC for SEB up to 50% of control. The addition of monoclonal antibodies against adhesion molecules between LC and T cells to the culture resulted in substantial suppression of the T‐cell response to SEB induced by nonirradiated LC‐EC, while the U VB‐irradiated LC‐EC‐induced T‐cell response was not significantly blocked with these monoclonal antibodies. This suggested that the reduction of LC ability for superantigen by high doses of UVB is at least partly due to impairment of adhesion molecules on LC by UVB irradiation.
A FULLY AUTOMATED DUAL‐WAVELENGTH PHOTOMETER FOR PHYTOCHROME MEASUREMENTS AND ITS APPLICATION TO PHYTOCHROME FROM CHLOROPHYLLCONTAINING EXTRACE
Authors: Lamparter Tilman , Hughes Jon , Hartmann Elmar
Published: January 2008

Abstract The photometer described here measures phytochrome photoreversibility of as many as 20 samples fully automatically. Monochromatic light of two laser diodes (670 and 780 nm) is used as a source for the measuring light beam. The whole measuring procedure is controlled by a computer linked to a lock‐in amplifier. This arrangement permits a rather simple construction and allows automatic zeroing and sample change.

In addition the application of a Triton phase partitioning method to allow phytochrome photoreversibility mea surements of extracts of green tissue is described. A single phase partitioning with a chlorophylYphytochrome mixture reduced chlorophyll concentration to less than 10%. Repeated phase partitioning of crude extracts from green moss protonemata reduced chlorophyll content to less than 2% while leaving the phytochrome concentration almost unchanged. In some instances this method has advantages over polyethyleneimine precipitation, which is commonly used to obtain chlorophyll‐free extracts.
AFLOQUALONE PHOTOSENSITIVITY. IMMUNOGENICITY OF AFLOQUALONE‐PHOTOMODIFIED EPIDERMAL CELLS
Authors: Tokura Yoshiki , Ogai Masaaki , Yagi Hiroaki , Takigawa Masahiro
Published: January 2008

Abstract Afloqualone (AQ) is an oral muscle relaxant and evokes ultraviolet A (UVA)‐induced photosensitivity dermatitis as a side effect. Histologic observations of the skin eruption suggest that AQ photosensitivity is mediated not only by phototoxic but also by photoallergic mechanisms. To address the immunological mechanisms of AQ photosensitivity, we examined the immunogenicity of AQ‐photomodified epidermal cells in mice. Afloqualone was covalently coupled with bovine serum albumin by irradiation with UVA but not UVB. Because of this ability of AQ to photobind to protein, murine epidermal cells were easily modified with AQ by exposure to UVA. Subcutaneous inoculation of AQ‐photomodified epidermal cells successfully induced an antigen‐specific delayed‐type hypersensi‐tivity in mice. These findings suggest that AQ‐photoderivatized epidermal cells are highly immunogenic and that photomodification of epidermal cells with AQ is an initial event to evoke AQ photosensitivity dermatitis.
A DOSIMETRIC TECHNIQUE FOR THE MEASUREMENT OF ULTRAVIOLET RADIATION EXPOSURE TO PLANTS
Authors: Parisi A. V. , Wong C. F.
Published: January 2008

Abstract Due to the effects of geometry, orientation, atmospheric conditions and optical properties of leaves and soils, the UV exposure to a plant may differ significantly from that of ambient radiation. This paper presents a method utilizing a passive measuring technique with polysulfone dosimeters that provides the ability of measuring the UV exposure at a number of sites simultaneously. The UV exposures are measured at selected sites over models of three canopy shapes with a computer program interpolating and summing these to provide the total UV exposure incident on the canopy.
PROTEIN STRUCI'URE MODELLING OF THE BACTERIAL LIGHT‐HARVESTING COMPLEX
Authors: Olsen J. D. , Hunter C. N.
Published: January 2008

Abstract Protein structure modelling offers a method of obtaining 3‐dimensional information that can be tested and used to plan mutagenesis experiments when a crystallographically determined structure is not available. At its simplest a model may consist of little more than a secondary structure prediction coupled with a determination of the likely regions of transmembrane/membrane surface/globular configuration. These methods can yield an interesting topology map of the protein, which places the residues in their likely positions with respect to, for example, the membrane interface. If it is a member of a large family of related proteins then aligned protein sequences can be used to predict the residues that have an important function as these. will be largely conserved in the alignments. Using all these methods a model can be constructed (using for example, the Nicholson Molecular Modelling Kit) to visualize the proposed structure in three dimensions following the premise of good design, that is, avoiding obvious steric clashes, packing of helices in a realistic manner, observing the correct H‐bond lengths, etc. In this latter exercise the review of Chothia (Annu. Rev. Biochem. 53, 537–572, 1984) of the principles of protein structure is particularly helpful as it clearly sets out how proteins pack and their preferred configuration. There is a wealth of information about individual amino acid conformational preferences and observed frequencies of occurrence in known protein structures, which can help decide how the residues in the model can be oriented.

In this article we have collated the various protein models of the bacterial light‐harvesting complexes and present our own model, which is a synthesis of the available biophysical data and theoretical predictions, and show its performance in explaining recent results of site‐directed mutants of the LHI and LH2 light‐harvesting complexes of Rhodobacter sphaeroides.
4′‐AMINOMETHYL‐4,5′,8‐TRIMETHYLPSORALEN PHOTOCHEMISTRY THE EFFECT OF CONCENTRATION AND UVA FLUENCE ON PHOTOADDUCT FORMATION IN POLY(dAdT) AND CALF THYMUS DNA
Authors: Oroskar Asha , Olack Gerard , Peak Meyrick J. , Gasparro Francis P.
Published: January 2008

Abstract‐The photochemistry of 4′‐aminomethyl‐4,5′,8‐trimethylpsoralen (AMT) with poly(dA‐dT) and calf thymus DNA was studied. The extent of photoadduct formation and the distribution of photoadducts (3,4– and 4′,5′‐monoadducts and crosslinks) were determined by liquid scintillation analysis and HPLC, respectively. The adducts were characterized on the basis of their UV absorption spectra and mass spectral analysis. The high DNA binding constant for AMT (1.5 x 105M−1) led to a high fraction of intercalated molecules, which contributed to the high level of AMT photoadduct formation, as many as 102 adducts per kilobase pair. In addition, there is a distinct difference in the adduct distribution compared to the previously studied 8‐methoxypsoralen (8‐MOP). Under the conditions employed for the photochemical studies, virtually all of the AMT molecules in solution are intercalated, occupying 25% of the base pair sites. Under similar conditions, 8‐MOP molecules occupied 10 times fewer sites. Thus, for AMT, DNA base pair sites other than 5′TA, the well‐characterized strong binding for psoralens in general, are an additional target for photomodification, which results in the formation of a higher percentage of monoadducts. The proportion of photoadducts formed was virtually independent of AMT concentration and UVA (320–400 nm radiation) fluence.
PHOTOACTIVE TERTHIOPHENES: THE INFLUENCE OF SERUM ON ANTI‐HIV (HUMAN IMMUNODEFICIENCY VIRUS) ACTIVITIES
Authors: Hudson J. B. , Marles R. J. , Soucy‐Breau C. , Harris L. , Arnason J. T.
Published: January 2008

Abstract‐A number of carboxylic acid derivatives of the photoactive terthiophene, α‐terthienyl, were found to possess impressive UVA‐dependent activity against the human immunodeficiency virus, HIV‐1; but only when assayed in the absence of serum, indicating that the latter contained interfering components. Good antiviral activity required a high rate of singlet oxygen production, in accordance with previous observations on thiophenes.
PRESUMED PHOTORECEPTOR PROTEIN AND ULTRASTRUCI'URE OF THE PHOTORECEPTOR ORGANELLE IN THE CILIATED PROTOZOAN, Blepharisma
Authors: Matsuoka Tatsuomi , Tsuda Takenori , Ishida Masaki , Kato Yoji , Takayanagi Miyuki , Fujino Takeshi , Mizuta Shun
Published: January 2008

Abstract‐The red pigment granule of Belpharisma japonicum is believed to be a photoreceptor organelle mediating photodispersal. Freeze‐fracture and thin section electron microscopy revealed that the pigment granules contained a honeycomb‐like structure constructed of folded membranes. In the fracture face of the honeycomb‐like structure, small membrane particles were observed, which might correspond to pigment—protein complexes. The pigment granules were isolated and detergent‐solubilized. Sodium dodecyl sulfate‐polyacrylamide gel electrophoresis (SDS‐PAGE) showed that the pigment granules mainly contained a 200 kDa membrane protein. The complex of red pigment and 200 kDa protein was isolated by gel‐filtration chromatography of the detergent‐solubilized components, and the protein was subjected to SDS‐PAGE and amino acid analysis. The 200 kDa protein could not be dissociated into subunits by 2‐mercaptoethanol, indicating that the protein is composed of a single polypeptide chain. Hydrophobic amino acids contained in the 200 kDa protein were not dominant, suggesting that only partial domains may extend across the membrane of the honeycomb‐like structure.
MEMBRANE IONIC CURRENT PHOTOMODIFICATION BY ROSE BENGAL and MENADIONE: ROLE OF SINGLET OXYGEN
Authors: Arriaga Edgar , Frolov Andrey , Tarr Merrill , Valenzeno Dennis Paul
Published: January 2008

Abstract –Photosensitized modification of ionic leak current and potassium current was studied in frog cardiac atrial cells using whole cell patch clamp techniques. Rose bengal (RB) and menadione (MQ) were used as photosensitizers. Separate photophysical studies of the photosensitizers in deuterium oxide solution demonstrated that MQ did not produce singlet oxygen as evidenced by the lack of luminescence at 1270 nm, whereas RB was an efficient singlet oxygen generator. Both photosensitizers sensitized block of potassium current in atrial cells, and both sensitized an increase of ionic leak current. However, when photosensitizer concentrations and illumination intensities were adjusted to match the rate of block of potassium current by the two photosensitizers, there were dramatic differences in leak current increase, both quantitatively and qualitatively. Menadione sensitized a much slower increase in leak current than did RB. Further, the leak current sensitized by MQ had a more positive reversal potential than that sensitized by RB, suggesting a less potassium‐selective leak current pathway. The results suggest that, while the effects of singlet oxygen and non‐singlet oxygen modification of cell membranes may be similar, there may also be significant differences in the resulting membrane permeabilities. The results also demonstrate that MQ and RB may be useful agents to study the role of singlet oxygen versus non‐singlet oxygen modification of biological systems.
ERYTHEMAL UV‐B IRRADIANCE (ROBERTSON‐BERGER SUNBURN METER DATA) UNDER OZONE DEFICIENCIES IN WINTER/SPRING 1993
Authors: Blumthaler Mario , Ambach Walter , Silbernagl Roland , Staehelin Johannes
Published: January 2008

Abstract –Robertson‐Berger sunburn meter data recorded from August 1992 to May 1993 (Innsbruck, 577 m above sea level, Austria) were compared with measurements taken in previous years. In February and March 1993 instantaneous values on clear days were found to be higher by up to 37% than those registered in previous years (1986–1988). However, in winter/spring 1993 daily totals for all days, averaged over 7 days, were within the range of standard deviation of the previous years (1981–1988). Therefore the cumulative UV‐B exposure of the ecosystem is within the general range of variability even under the record low ozone values in winter/spring 1993, while single peak doses were enhanced significantly.
THEORETICAL INVESTIGATION OF EXCIMER AND EXCIPLEX STATES OF URACIL AND HALOGEN DERIVATIVES: EFFECT OF NONPARALLELISM OF BASES
Authors: Pechenaya Vera I. , Danilov Victor I. , Slyusarchuk Oleg N. , Alderfer James L.
Published: January 2008

Theoretical modeling of initial steps of the photodimerization mechanism of uracil, 5‐methyl‐and 5‐halogen derivatives was performed. The interaction energy of bases in stacked dimers in the ground and lowest excited states was calculated as a function of the distance between the base planes and of the rotation angles within the perturbation theory for the extended Hückel treatment. The existence of excimer and exciplex region on the potential surface of the excited state was revealed. The excimer (exciplex) geometry has the planes nonparallel with more close contact of the C5‐C6 bonds as compared to the ground state of dimers. The results provide new information useful for understanding the photodimerization mechanism of bases and testifies that the singlet excimer state can be a precursor of the photodimerization reaction.