bluuebunny/crossref_metadata_2025_split huggingface dataset:
VUV/SOFT‐X‐RAY SPECTROSCOPIC FACILITIES AT THE SYNCHROTRON RADIATION LABORATORIES IN JAPAN
Authors: Namioka Takeshi 
Published: January 2008

AbstractThe present status is described of the vacuum ultraviolet/soft‐X‐ray spectroscopic facilities at the synchrotron radiation laboratories in Japan. An overview is presented of the spectroscopic instruments available and under development at the SOR‐RING at the Institute for Solid State Physics, University of Tokyo, the Photon Factory‐ring at the National Laboratory for High Energy Physics, the UVSOR at the Institute for Molecular Science, and the TERAS at the Electrotcchnical Laboratory. Emphasis is placed upon the unique features of the instruments developed in Japan.
VUV ABSORPTION AND ITS RELATION TO THE EFFECTS OF IONIZING CORPUSCULAR RADIATION*
Authors: Inokuti Mitio 
Published: January 2008

AbstractElements of the physics of photoabsorption as well as of energy transfer from fast charged particles are discussed. Among the key notions there are oscillator‐strength spectra, quantum yields, and action spectra. Throughout the discussion, emphasis is put on the important role of soft X‐rays and VUV light as obtained from a synchrotron radiation source in the understanding of actions of ionizing radiations in general.
EFFECTS OF UV, SUNLIGHT AND X‐RAY RADIATION ON QUIESCENT HUMAN CELLS IN CULTURE
Authors: Kantor G. J. 
Published: January 2008

AbstractNondividing human diploid fibroblasts (HDF) in culture have been used to study the effect on cell lethality of ultraviolet light, natural sunlight and X‐rays. A lethal effect is defined as cellular degeneration, loss from the culture and inability to exclude vital strains. Far‐and mid‐UV have a readily observable lethal effect (cell loss), with DNA and DNA damage as the critical target and critical damage respectively. In part, natural sunlight kills cells by a similar mechanism but has an additional lethal effect at longer exposure times. This additional effect is expressed by the retention of the dead cells in culture, in contrast to the UV‐induced promotion of cell degeneration and loss. Relatively large doses of X‐rays that destroy proliferative capacity, have no detectable lethal effect on the maintenance of nondividing cells. The biological response of nondividing HDF to radiations from different parts of the electromagnetic spectrum is dissimilar.
PHOTOCHEMICAL BEHAVIOR AND EMISSION CHARACTERISTICS OF 9‐VINYLANTHRACENE
Authors: Ebeid E. M. , El‐Gamal M. A. , Morsi S. E. 
Published: January 2008

Abstract9‐Vinylanthracene (9‐VA) is an efficient fluorescer of fluorescence quantum yield = 0.91 0.03 in methanol (ex= 365 nm). This is consistent with its low photochemical quantum yields c (cx= 365 nm) of 0.005 in the absence of azobisisobutyronitrile (AIBN) radical initiator and c= 0.02 in the presence of 10‐2M dm‐3 AIBN. 9‐Vinylanthracene was shown to behave as a 9‐substituted anthracene undergoing photodimerization rather than the typical vinyl aryl monomer photopolymerization. The photodimer formation is supported by spectroscopic techniques. 9‐Vinylanthracene undergoes efficient fluorescence quenching in the presence of AIBN. Stern‐Volmer plots indicate a collisional mechanism. 9‐Vinylanthracene crystals as well as polycrystalline films give excimeric emission (max= 510 nm, cx= 380 nm) which is considerably red shifted (ca. 100 nm) compared with molecular emission.
ENDOGENOUS GLUTATHIONE PROTECTS HUMAN SKIN FIBROBLASTS AGAINST THE CYTOTOXIC ACTION OF UVB, UVA AND NEAR‐VISIBLE RADIATIONS
Authors: Tyrrell Rex M. , Pidoux Mireille 
Published: January 2008

AbstractBoth the UVB (290‐320 nm) and UVA (320‐380 nm) regions of sunlight damage human skin cells but, particularly at the longer wavelengths, information is scant concerning the mechanism(s) of damage induction and the roles of cellular defense mechanisms. Following extensive glutathione depletion of cultured human skin fibroblasts, the cells become strongly sensitized to the cytotoxic action of near‐visible (405 nm), UVA (334 nm, 365 nm) and UVB (313 nm) but not UVC (254 nm) radiations. In the critical UVB region, the magnitude of the protection afforded by endogenous glutathione approaches that of the protection provided by excision repair. The results suggest that a significant fraction of even UVB damage can be mediated by free radical attack and that a major role of glutathione in human skin cells is to protect them from the cytotoxic action of sunlight.
LIGHT‐INDUCIBLE ABSORBANCE CHANGES AND VANADATE‐SENSITIVE ATPase ACTIVITY ASSOCIATED WITH THE PRESUMPTIVE PLASMA MEMBRANE FRACTION FROM CAULIFLOWER INFLORESCENCES
Authors: Caubergs Roland J. , Asard Han H. , DeGreef Jan A. , Leeuwerik Frans J. , Oltmann Fred L. 
Published: January 2008

AbstractSucrose density gradient centrifugation of a microsomal membrane fraction of cauliflower inflorescences showed a strong correlation between a blue light mediated cytochrome b reduction (LIAC) and an ion stimulated nitrate‐insensitive but a vanadate‐sensitive ATPase activity at 38‐40% sucrose. LIAC activity and vanadate‐sensitive ATPase might be assigned to the same type of membrane different from ER, Golgi, tonoplast and mitochondria. The Mg2+‐dependent ATP‐hydrolytic activity obtained after purification of the microsomal fraction on an aqueous polymer two phase system was partially characterized. Temperature optimum (40°C), pH optimum (pH 7.0), vanadate inhibition (I50 at 20 μM), substrate kinetics (Km= 1.37 mM Mg.ATP) and inhibitor studies all point to the presence of the frequently described plasma membrane ATPase. Potassium and Na+ stimulated the enzyme activity (20‐40%). In general our data arc strongly in favour of the hypothesis that LIAC activity is localized on the plant plasma membrane. The cytochrome b involved in the light reaction has a midpoint potential near +150 mV. This cytochrome which has been previously shown in a cauliflower microsomal fraction is a constituent of the plasma membrane.
BIOLUMINESCENCE OF THE BRITTLE STAR OPHIOPSILA CALIFORNICA
Authors: Shimomura Osamu 
Published: January 2008

AbstractThe light‐emitting principle of the brittle star Ophiopsila californica has been isolated and purified. It was found to be a green‐fluorescent photoprotein (molecular weight 45000) which emits green light (λmax 500 nm) when H2O2 is added, independently of the presence or absence of O2. The green fluorescence (emission maximum 500 nm, excitation maximum 440 nm) spectrally coincided with the H2O2‐triggered luminescence, indicating that the green fluorescent chromophore is the light‐emitter of the photoprotein luminescence.
PHOTOELECTROCHEMICAL OXIDATION OF OXALATE ION IN AQUEOUS DISPERSIONS OF ZINC OXIDE
Authors: Domenech J. , Costa J. M. 
Published: January 2008

AbstractThe photooxidation of oxalate ions in aqueous dispersions of ZnO under UV‐illumination has been investigated in order to determine the efficiency of oxalate ions as hole scavangers. The process has been studied by measuring the quantity of oxalate ions photooxidized at different experimental conditions. It is observed that the number of moles of oxalate photodecomposed increases with irradiation time and with the mass of semiconductor in suspension, attaining in this case a limiting value. Also, the amount of oxalate ions photooxidized increases with both initial oxalate concentration and light intensity. These results are discussed in terms of the different redox processes that take place at the semiconductor particle‐electrolyte interface.
PHOTOLYSIS OF PHEOMELANIN PRECURSORS: AN ESR‐SPIN TRAPPING STUDY
Authors: Pilas Barbara , Felix Christopher C. , Sarna Tadeusz , Kalyanaraman B. 
Published: January 2008

AbstractThe photolysis of 5‐S‐cysteinyldopa, 2,5‐S,S‐dicysteinyldopa, 4‐hydroxybenzothiazole and cysteinyldopa melanins has been studied by ESR‐spin trapping methods using 5.5‐dimethyl‐1‐pyrroline‐1‐oxide and 2‐methyl‐2‐nitrosopropane as spin traps for hydrated electrons, hydrogen atoms, and carbon‐centered alanyl radicals. The photochemistry of these materials is shown to resemble dopa in that both photoionization and photohomolysis occur. However, unlike dopa, the cysteinyldopa also forms the carbon‐centered alanyl radicals via photodecomposition of the cysteinyl group. Action spectra and quantum yields are reported. Mechanism(s) of radical formation are discussed.
PHOTOBINDING OF PSORALENS TO BACTERIAL MACROMOLECULES IN SITU AND INDUCTION OF GENETIC EFFECTS IN A BACTERIAL TEST SYSTEM. EFFECTS OF SINGLET OXYGEN DIAGNOSTIC AIDS D2O AND DABCO
Authors: Mol N. J. de , van Henegouwen G. M. J. Beijersbergen , Weeda B. , Knox C. N. , Truscott T. G. 
Published: January 2008

AbstractThe photobinding of radiolabeled psoralen and 8‐methoxypsoralen (8‐MOP) to biological macromolecules under conditions that affect the lifetime of singlet oxygen (1O2) is reported. These conditions are: increase of 1O2 lifetime in D2O and 1O2 quenching with DABCO. The photobinding to calf thymus DNA was studied in vitro and the covalent photobinding to DNA and other biological macromolecules (RNA, proteins) was also studied in intact bacteria. The results of the DNA photobinding experiments have been related to the induction of genetic damage in a bacterial test system. In addition, laser flash photolysis has been used to measure the effect of D2O and DABCO on the psoralen and 8‐MOP triplet lifetimes. In general D2O increases the triplet lifetimes and DABCO quenches the triplet states with the probable formation of radicals. The results suggest that the covalent photobinding of 8‐MOP to various biological macromolecules in situ is a basis for cell damage occurring at various cellular targets. Analysis of the results of the mutagenicity test suggests that in the presence of D2O the mechanism of induction of genetic lesions is not changed and therefore largely seems to be independent of singlet oxygen.
IDENTIFICATION AND LOCALIZATION OF PHOTOALKYLATED BASES IN DNA FRAGMENTS
Authors: (Noy) Etta Livneh , Sperling Joseph 
Published: January 2008

Abstract— Antibodies directed toward 8‐(2‐hydroxy‐2‐propyI)‐deoxyguanosine‐5′‐monophosphate (8‐hpdGMP), a product of the photoalkylation of deoxyguanosine‐5‘‐monophosphate with 2‐propanol, were shown to be highly specific and sensitive in detecting 8‐hpdGMP residues in photoalkylated DNA.The antibodies were further used to determine the distribution of modified guanine residues in DNA. The irradiated DNA was digested with restriction enzymes and the fragments obtained were separated electrophoretically and blotted onto diazotized paper. The covalently bound DNA fragments were probed with the antibodies and then with 125I Staphylococcus aureus protein A. These experiments indicate a non‐random distribution of modified guanine residues in øX174 RF DNA molecules.
ANALYSIS OF FLASH PHOTOLYSIS DATA BY A GLOBAL FIT WITH MULTI‐EXPONENTIALS–II. DETERMINATION OF CONSISTENT NATURAL RATE CONSTANTS and THE ABSORPTION SPECTRA OF THE TRANSIENT SPECIES IN THE BACTERIORHODOPSIN PHOTOCYCLE FROM MEASUREMENTS AT DIFFERENT TEMPERATURES
Authors: Maurer R. , Vogel J. , Schneider S. 
Published: January 2008

AbstractA procedure is described which allows one to deduce from flash photolysis data (absorbance change vs time) recorded at different temperatures the natural rate constants for the elementary reaction steps and the transient absorption spectra of the intermediates within a given kinetic scheme. The selected solutions fulfil two requirements: (i) the rate constants for different temperatures follow Arrhenius’law; (ii) the absorption spectra of the intermediates are independent of temperature. The method is applied to the photocycle of bacteriorhodopsin; the selected model comprises two L‐species, a branching at the M‐intermediate directly back to BR and an equilibrium between M and O.
THE QUANTUM EFFICIENCY FOR THE INTERPHOTOCONVERSION OF THE BLUE and PINK FORMS OF PURPLE MEMBRANE
Authors: Liu S. Y. , Ebrey T. G. 
Published: January 2008

AbstractWhen the cations bound to purple membrane are removed it turns blue, and when this blue membrane is irradiated its color changes to pink. Irradiation of pink membrane leads to the reformation of blue membrane. We have determined that the quantum efficiency for the formation of pink membrane from deionized blue membrane is 1.6 ± 0.6 ± 10 4 at 0oC, pH 5.0. We also found that the quantum efficiency for the back photoconversion, i.e. the formation of blue membrane from pink membrane, is 8.8 ± 1.6 ± 10‐3 at 0oC, 55 times greater than that of the forward photoconversion reaction. The extinction coefficients of the pink membrane and blue membrane were determined to be 44 500 ± 670 cm‐1 M‐1 at 491 nm and 54 760 ± 830 cm‐1M‐1 at 603 nm, respectively, assuming light‐adapted purple membrane is 63 000 cm‐1M‐1 at 568 nm. The quantum efficiency for forming pink membrane from blue membrane is much lower than that for forming the photointermediate of the blue membrane's photocycle. Their relationship is similar to that of light‐adaptation and photocycle of the dark‐adapted purple membrane.
ALL‐trans β‐CAROTENE‐5,6‐EPOXIDE IN THYLAKOID MEMBRANES
Authors: Ashikawa Ikuo , Kito Mariko , Satoh Kimiyuki , Koike Hiroyuki , Inoue Yorinao , Saiki Kayoko , Tsukida Kiyoshi , Koyama Yasushi 
Published: January 2008

AbstractAll‐transβ‐carotene‐5,6‐epoxide has been found in the thylakoid membranes of spinach and of the cyanobacterium Synechococcus vulcanus Copeland. The epoxide was extracted from the thylakoid membranes with acetone, and was isolated by high‐performance liquid chromatography (HPLC). The structure of the epoxide was identified by means of mass, Raman, and electronic absorption spectroscopy. Changes in the amount of the epoxide, as a result of epoxidation and (apparent) de‐epoxidation reactions in the membranes, were traced by analysis of extracts on HPLC. In isolated thylakoid membranes, only the epoxidation reaction took place. The reaction was caused by irradiation or by the addition of ferricyanide, suggesting that electron transport reactions in the membranes are involved in the epoxidation. In intact spinach leaves, however, both epoxidation and de‐epoxidation took place; the extent of epoxidation correlated with the intensity of light incident on the leaves. The epoxidation and de‐epoxidation of all‐transβ‐carotene are contrasted with those of xanthophylls (in the violaxanthin cycle).
CHEMISTRY OF SINGLET OXYGEN—48. ISOLATION and STRUCTURE OF THE PRIMARY PRODUCT OF PHOTOOXYGENATION OF 3,5‐DI‐t‐BUTYL CATECHOL
Authors: Jensen Frank , Foote ChristopherS. 
Published: January 2008

AbstractThe dye‐sensitized photooxygenation of t‐butyl substituted catechols has been investigated. The primary product from 3,5‐di‐t‐butyl catechol has been isolated and shown to be a hydroperoxydienone by single crystal X‐ray diffraction. The absence of sensitizer effects and the faster reaction rate in polar solvents suggest that the reaction proceeds with singlet oxygen as the primary oxygenating species. Charge‐transfer or full electron‐transfer from the catechol to singlet oxygen is probably involved. Substituent effects are in agreement with this mechanism. The products from thermal breakdown of the hydroperoxydienone are inconsistent with a Baeyer‐Villiger mechanism.
PORPHYRIN‐LIPID INTERACTIONS AT THE AIR‐WATER INTERFACE IN SPREAD MONOLAYERS. A FLUORESCENCE STUDY.
Authors: Bohorquez Maria , Patterson Larry K. , Brault Daniel 
Published: January 2008

AbstractIn membrane systems, carboxylic porphyrins may interact with both the lipid pseudophase and the adjacent aqueous environment through their hydrophobic core and their polar acid chains, respectively. These interactions are monitored in model membrane systems, i.e. spread monolayers of dioleoylphosphatidylcholine as functions of lipid organization and pH of the aqueous subphase using steady state and time resolved fluorescence techniques. In all cases contact between porphyrin and aqueous subphase, as indicated through quenching by I‐, is observed at low surface pressure. This contact decreases and becomes almost insignificant as the monolayer approaches maximum organization through compression. On deprotonation of the monocarboxylic porphyrin, methylpyrroporphyrin, increased contact with water is observed in liquid compressed monolayers. In liquid expanded layers, however, it appears that organization of lipid molecules surrounding this dissymmetric charged form affords some isolation from water. The effect of esterification of carboxylic chains is also examined.
AN INEXPENSIVE STIRRING DEVICE FOR THE ‘MERRY‐GO‐ROUND’ PHOTOREACTOR FOR THE DETERMINATION OF REACTION QUANTUM YIELDS
Authors: De Silva A. Prasanna , Silva S. Sisira K. de , Edwin V. , Ramyalal N. L. D. Sydney , Silva M. Lalith K. 
Published: January 2008

AbstractA simple bar magnet is employed to effect stirring of the contents of reaction cells in a‘merry‐go‐round’photoreactor.
PURIFICATION and ANALYSIS OF HEMATOPORPHYRIN and HEMATOPORPHYRIN DERIVATIVE BY GEL EXCLUSION and REVERSE‐PHASE CHROMATOGRAPHY*
Authors: Kessel David , Thompson Paul 
Published: January 2008

AbstractA ternary‐solvent HPLC method for analysis of the components of the tumor‐localizing product HPD is described. This HPLC system was used to assess the utility of a new method, based on gel exclusion chromatography, for purification of hematoporphyrin.
STANDARDS FOR UV INSTRUMENTS AND RISK OF EXISTING DEVICES
Authors: Kaase H. , Metzdorf J. , Berger H. 
Published: January 2008

Abstract— Different methods for measurements of UV‐radiation of various light sources are quantitatively compared: direct measurements, based on detectors of known responsivity, as well as indirect measurements, based on a spectral irradiance calibration. The optical arrangement of an accurate spectroradiometric equipment, and the structure and parameters for a new type of cosine corrected detector for the measurement of actinic radiation are described, too. The measurements of actinic radiation with commercial devices are affected by great relative errors.A standard for natural irradiance will allow a comparison of weighted irradiances and threshold irradiations with natural insolation and with artificial UV radiation. The risk of existing irradiation apparatuses will be calculable by this comparison.
CARBON‐14 LABELING AND BIOLOGICAL ACTIVITY OF THE TUMOR‐LOCALIZING DERIVATIVE OF HEMATOPORPHYRIN
Authors: Ho Yau‐Kwan , Pandey Ravindra K. , Missert Joseph R. , Bellnier David A. , Dougherty Thomas J. 
Published: January 2008

Abstract— Carbon‐14‐labeled hematoporphyrin ([14C]HP) was synthesized by two methods, (i) Using an in vitro avian whole‐blood system, [14C]protoheme was obtained biosynthetically by incorporating [4C]aminolevulinic acid into the porphyrin ring structure. Subsequently, the [14C]protoheme was converted to [4C]HP by standard procedures, (ii) By adopting several well‐characterized chemical reactions, deuteroporphyrin was treated with [14C]acetyl chloride, giving [14C]diacetyl deuteroporphy‐rin which was readily reduced and hydrolyzed to [14C]HP (with thecarbon–14 label on the hydroxyethyl side‐chains). These two methods are simple and afford good yields of [14C]HP with moderate to high specific activities.The [14C]HP was then treated with acetic acid/sulfuric acid followed by sodium hydroxide to give [14C]HPD. Upon gel‐ and ultra‐filtration, the [14C]HPD was enriched in the so‐called tumor‐localizing fraction of HPD, giving [14C]PII with specific activities of 0.4 Ci/mol (biosynthesis) and 10 Ci/mol (chemical synthesis). These [14C]PII preparations were equivalent with respect to chromatographic and spectrophotometric characteristics, as well as tumoricidal photodynamic activity in the DBA/2 Ha‐DD mouse: SMT‐F tumor system, to the unlabeled commercial product Photofrin™ II. The distribution of [14C]PII in mouse tissues was in close agreement to that previously reported, after adjustment for dose, for [14C]HPD biosynthetically labeled in vivo (Gomer and Dougherty, 1979), as well as for Photofrin™ II, where tissue levels were determined spectrophotometrically after extraction (Dougherty and Mang, unpublished).
DNA DAMAGE and ITS REPAIR IN Dictyostelium discoideum IRRADIATED BY HEALTH LAMP LIGHT (UV‐ B)
Authors: Okaichi Kumio , Kajitani Nobuyuki , Nakajima Katuko , Nozu Keiichi , Ohnishi Takeo 
Published: January 2008

Abstract—Irradiation by health lamp (HL) light (280–320 nm) more efficiently induced cell killing and mutation in a radiation sensitive mutant (TW8) of Dictyostelium discoideum as compared with the parental wild‐type strain (NC4). This light as well as a germicidal lamp‐light (254 nm) produced pyrimidine dimers. The dimers were removed from DNA molecules by excision repair in NC4, but more slowly in TW8. It is suggested that pyrimidine dimers are the main DNA damage caused by HL light in D. discoideum, and that this results in cell killing and induced mutation.
LIGHT PERCEPTION BY PHYTOCHROME in vivo*
Authors: Mancinelli Alberto L. , Lim Jui 
Published: January 2008

Abstract—The rate of phytochrome photoconversion in cotyledons and hypocotyls of dark‐grown seedlings of Cucurbita pepo varies significantly depending on the characteristics of the light field and the position of the sample in the light field. The overall pattern of the effects of light reflectance conditions and angle of incidence of light on phytochrome photoconversion in vivo is predictable and consistent with the results of physiological studies; however, the extent of the effects is much more difficult to predict with a satisfactory degree of approximation. The differences between phytochrome photoconversion kinetics measured in vivo and those predicted from photochemical parameters of purified phytochrome are rather large and suggest that the use of predictions as estimates of the state of phytochrome in vivo may be subject to significant limitations.
THE MICROVASCULAR EFFECTS OF PHOTODYNAMIC THERAPY: EVIDENCE FOR A POSSIBLE ROLE OF CYCLOOXYGENASE PRODUCTS
Authors: Reed Malcolm W. R. , Wieman T. Jeffery , Doak Karola W. , Pietsch Catherine G. , Schuschke Dale A. 
Published: January 2008

Abstract—Photodynamic therapy (PDT) of malignant tumors may involve the interruption of tumor and peritumor microcirculation. We have studied the effect of light activation of the photosensitizing drug dihematoporphyrin ether (DHE) on rat subcutaneous arterioles and the modulation of these effects by cyclooxygenase inhibitors indomethacin and acetyl salicylic acid (ASA). Animals received DHE 48 h prior to light activation and additionally either indomethacin, ASA or saline 3 h prior to treatment. Light activation (630 nm, 60 J/cm2) resulted in a significant reduction to 62 ± 2% SEM of initial blood flow. This effect was inhibited by ASA (98 ± 8% SEM) and indomethacin (87 ± 8% SEM). Results from the administration of various doses of both compounds indicate that this inhibition is dose related. The data presented here show that PDT causes a significant reduction in blood flow in normal arterioles and that this effect was inhibited by ASA and indomethacin indicating that prostaglandins or thromboxane A2 may play an important role in the microvascular response to PDT.
A ROLE FOR STEROLS IN THE PORPHYRIN MEDIATED PHOTOSENSITIZATION OF YEAST
Authors: Casey Warren M. , Parks Leo W. 
Published: January 2008

Abstract–The yeast Saccharomyces cerevisiae was used as a model system to determine the role of sterols in the porphyrin mediated photosensitization of yeast. A sterol auxotroph, RD5‐R, was grown on sterols with different levels of unsaturation and assayed for photosensitivity in the presence of either protoporphyrin IX or hematoporphyrin (both at 100 μ,g/me). Cells grown on the completely saturated sterol (stanol), cholestanol. were substantially more resistant to the photosensitizing effects of the porphyrin. We hypothesize that this resistance arises from the inability of the porphyrin to mediate the oxidation of the membrane sterol. Our results indicate that photodegradation of the native yeast sterol, ergosterol, can account for substantial losses of cell viability.