bluuebunny/crossref_metadata_2025_split huggingface dataset:
SPECTROSCOPIC STUDIES OF CUTANEOUS PHOTOSENSITIZING AGENTS–III. SPIN TRAPPING OF PHOTOLYSIS PRODUCTS FROM SULFANILAMIDE ANALOGS
Authors: Motten Ann G. , Chignell Colin F. 
Published: January 2008

AbstractThe photodecomposition of sulfanilamide (4‐aminobenzenesulfonamide), sulfacetamide. sulfathiazole. sulfadiazine, carbutamide and tolbutamide has been studied using the spin traps 2‐methyl‐2‐nitrosopropanc and 5,5‐dimethyl‐l‐pyrroline‐l‐oxide. The following radicals were trapped during the photolysis of sulfanilamide in aqueous solution: H' and HNC6H4SO2NH, (α‐fission). SO2NH2 and C6H4NH2 (δ fission). H2NC6H4SO2 and NH2 (δ‐fission). Although the C.,H4SO2NH2 and the SO; radicals were also detected these were not formed directly by homolytic bond fission. Homolytic bond fission was also observed during the irradiation of sulfacetamide (α.δ), sulfadiazine (α). carbutamide (α,δ) and tolbutamide (δ). All of the analogs, with the exception of tolbutamide, generated the SO; radical. Sulfacetamide, sulfadiazine and carbutamide generated the C6H4SO2;NHR radical by some process that did not involve homolytic bond fission. The free radicals generated by these agents may play an important role in their phototoxic and photoallergic effects.
FREE RADICALS FROM PHOTOREDUCTION OF HEMATOPORPHYRIN IN AQUEOUS SOLUTION
Authors: Felix C. C. , Reszka K. , Sealy R. C. 
Published: January 2008

Abstract—The anaerobic photoreduction of hematoporphyrin by organic reducing agents in fluid aqueous solutions has been studied by electron spin resonance spectroscopy. Efficient photoreduction occurs with many hydrogen‐atom or electron donors, including catechols, pyrogallol. hydroquinone. ascorbate, p‐phenylenediamine, cysteine and glutathione. A combination of direct and spin‐trapping measurements (using 2‐methyl‐2‐nitrosopropane) has been used to confirm production of radicals from both the porphyrin and the reducing agent in each system.
THE ROLE OF 4‐THIOURIDINE IN LETHAL EFFECTS AND IN DNA BACKBONE BREAKAGE CAUSED BY 334 nm ULTRAVIOLET LIGHT IN Escherichia coli
Authors: Peak M. J. , Peak J. G. , Nerad Lisa 
Published: January 2008

AbstractStrains of Escherichia coli that lack 4‐thiouridine (4Srd) are killed by monochromatic 334 nm UV light (UV) less efficiently than their wild‐type parents, which contain 4Srd. Oxygen enhancement ratios (OER) at 10% survival are 3.3 for a strain that possesses 4Srd, and 2.6 for one that lacks 4Srd. Single‐strand breaks in DNA caused by 334 nm UV accumulate more than twice as fast in the wild‐type strains than in the strains lacking 4Srd. The results suggest that 4Srd is an important chromophore in some near‐UV lethal effects. The results also suggest that the excitation energy from 334 nm UV light may be passed from RNA to DNA, resulting in single‐strand breaks.
ACTION SPECTRA OF PHOTOGEOTROPIC EQUILIBRIUM IN Phycomyces WILD TYPE AND THREE BEHAVIORAL MUTANTS
Authors: Galland Paul 
Published: January 2008

AbstractPhotogeotropic equilibrium action spectra in the range from 301 to 740 nm were made for Phycomyces wild type and the three behavioral mutants C47 (madA35), C109 (madBlOl) and LI (madCIIQ), all of which have a raised phototropic threshold. In addition to two broad peaks at 365 and 455 nm, typical for flavins, the wild type action spectrum shows three novel peaks, which have not been observed previously. These peaks are located at 414, 491 and 650 nm. The 650 nm peak has a relative quantum efficiency of 3 × 10−8 compared to the peak at 414 nm. The wavelength dependent shapes of the fluence‐response curves of the bending angle and the aiming error angle indicate more than one receptor pigment for phototropism. The shape of the action spectrum of C47 is basically unaltered in comparison to wild type. C109 and LI show substantial differences from the wild type. In the near UV two small peaks at 334 and 365 nm appear; the 414 and 491 nm peaks present in wild type and C47 are missing and two new peaks at 529 nm (not well resolved in C109) and 567 nm are found. None of the three mad mutations affects the 650 nm peak. A model of the sensory transduction chain is presented, which incorporates these and other known features.
WAVELENGTH‐DEPENDENT PROPERTIES OF PHOTOTAXIS IN LARVAE OF Bombyx mori
Authors: Kitabatake Seiji , Shimizu Isamu , Kato Masaru 
Published: January 2008

AbstractPhototactic responses of newly hatched silkworm larvae to monochromatic lights and their mixtures were measured to determine wavelength‐dependent properties. Each fluence rate‐response curve for a monochromatic light was composed of a log‐linearly increasing part, a plateau and a decreasing part. Curves were classified into two groups according to the slopes of the linear parts: responses to UV‐blue light (364‐482 nm) and responses to green‐red light (513‐681 nm). Different plateau values were found for both groups. The action spectrum had its maximum at 557 nm and showed another large value at about 364 nm, and its minimum was at 447 nm. When green‐orange lights (540‐577 nm) were added to 557 nm, the silkworms were attracted more by the mixed lights than by the 557 nm component light only. Mixed lights of UV (364 nm) and blue (447 nm) attracted the silkworms more than either component. The magnitude of the response decreased remarkably when green light was mixed with U V or blue light. We conclude that the silkworm possesses colour vision and responds differently to green‐red lights (≥ 513 nm) from UV‐blue lights (≲ 482 nm).
AN EVALUATION OF NALIDIXIC ACID FILM AS A UV‐A RADIATION DOSIMETER
Authors: Gobbs N. K. , Young A. R. 
Published: January 2008

AbstractNalidixic Acid (NA)* incorporated into a polyvinyl chloride film has recently been proposed as a UV‐A radiation dosimeter. A trial, in which two different batches of NA film were exposed to both solar simulating and monochromatic 330 nm radiation is described. With both batches of film a linear relationship was observed between the UV‐A fluence derived from the NA film and the fiuence determined with conventional electronic radiometric equipment. There was, however, considerable batch variation in response to UV‐A radiation. Corrections may be made for batch differences. If the batch response can be standardized, our results would support the use of NA film as a simple routine method of measuring UV‐A radiation.
CHARACTERIZATION OF PHOTOCYCLOADDITION PRODUCTS FROM REACTION BETWEEN THYMIDINE and THE MONOFUNCTIONAL 3‐CARBETHOXYPSORALEN
Authors: Cadet J. , Voituriez L. , Gaboriau F. , Vigny P. , Dellanegra S. 
Published: January 2008

AbstractThe photochemical reaction of 3‐carbethoxypsoralen. a monofunctional furocoumarin. with thymidine was investigated as a model system for its photoaddition to DNA. Near UV irradiation (320 nm > λ > 400 nm) of a mixture of thymidine and 3‐carbethoxypsoralen as a dry film gave rise to two main nucleoside diastereoisomers which were isolated by reverse phase high performance liquid chromatography. The structure of these products was assigned on the basis of UV absorption, fluorescence.‘H‐NMR and plasma desorption mass spectra analysis. The results are consistent with 1:1 C, cycloadducts involving the 5,6 double bond of thymine and the 4′, 5′double bond of 3‐carbethoxypsoralen. These two cycloadducts ofcis‐synstereoconfiguration show opposite circular dichroism suggesting a diastereoisomeric relationship.
SIMILARITIES IN THE INDUCTION OF SYNTHESIS OF A CELL‐SURFACE POLYPEPTIDE IN Arthrobacter sp. BY NEAR‐UV IRRADIATION and PHOTODYNAMIC CONDITIONS
Authors: Hoober J. Kenneth , Franzi Joseph 
Published: January 2008

AbstractIrradiation of aerobic suspensions of Arthrobacter sp. with near‐UV light (310‐400 nm) induced synthesis of a 21 000 dalton, cell‐surface polypeptide. Synthesis of this polypeptide also was induced by visible light in the presence of photodynamic dyes, as shown previously (Hoober, 1978). Induction of the polypeptide in near‐UV light and with visible light plus dyes was inhibited by histidine. Hemin inhibited induction in near‐UV light and in visible light with methylene blue, neutral red and acrifiavin, which are cationic dyes, but failed to inhibit induction in visible light with rose bengal, an anionic dye. These results suggested that inhibition by hemin required electrostatically favored interaction between the anionic porphyrin and the sensitizer, and that the near‐UV light effect was mediated by a cationic or neutral endogenous sensitizer. The similarities in the responses of the cells to near‐UV irradiation and visible light plus dyes suggested that the mechanism of induction under the two conditions was the same.
STATE I‐STATE II TRANSITIONS IN THE GREEN ALGA Scenedesmus obliquus*
Authors: Satoh Kazuhiko , Fork David C. 
Published: January 2008

AbstractIllumination of dark adaptedScenedesmuscells with system II light induced a typical fluorescence transient known as the Kautsky effect. Fluorescence spectra at 77 K showed no change in transfer of light energy from system II to I during this system II illumination. By contrast, illumination of the dark adapted cells with system I light induced an increase of one of system II fluorescence bands (at – 700 nm) at 77 K and a shift of system I fluorescence to a shorter wavelength. This change was accompanied by an increase of system II activity and by a decrease of system I activity and hence can be considered to be a state II‐I transition. A mutant which lacks light‐harvesting chlorophyllalbproteins (LHCP) also showed similar changes.These results show (1) that the dark adapted state is state II. (2) that the Kautsky effect is not related to state I–II transitions, (3) that the state I–II transition preferentially affected only one of the system II fluorescence bands at 77 K. and (4) that the presence of the LHCP chromophore is not necessary for the state changes.
EFFECT OF SPATIAL NON‐UNIFORMITY OF ILLUMINATION IN NON‐LINEAR INTENSITY‐DEPENDENT PHOTO PHYSICAL EXPERIMENTS. APPLICATION TO SOME FLUORESCENCE YIELD MEASUREMENTS IN PHOTOSYNTHETIC SYSTEMS
Authors: Paillotin Guy , Geacintov Nicholas E. , Breton Jacques 
Published: January 2008

AbstractThe spatial non‐uniformity of a light beam must be taken into account in interpreting phenomena which depend on the light intensity in a non‐linear manner. Omission of this effect may lead to incorrect values of parameters obtained from a fitting of theoretical curves, which describe the dependence of a given phenomenon on light intensity, to the experimental data. The effect of spatial non‐uniformity of excitation light beams is illustrated utilizing non‐linear intensity‐dependent fluorescence phenomena in photosvnthetic svstems and a Gaussian light beam profile.
THE LIPID SOLUBILITY OF PORPHYRINS MODULATES THEIR PHOTOTOXICITY IN MEMBRANE MODELS
Authors: Emiliani Carla , Delmelle Michel 
Published: January 2008

AbstractThe photosensitizing activities of hematoporphyrin, Cu‐hematoporphyrin, protoporphyrin. Zn‐protoporphyrin, deuteroporphyrin and uroporphyrin are studied. The relative yields of1O2are measured in buffer (pH 8.0) and compared to the yields of Type II photodamages induced on cholesterol embedded in egg lecithin liposomes. Results show that the solubilization of the sensitizer in the lipid bilayer is a prerequisite for its photosensitizing activity at the membrane level. In this context, the partition coefficient represents an important parameter.
LIGHT SENSITIVE LIPOSOMES
Authors: Pidgeon Charles , Hunt C. Anthony 
Published: January 2008

AbstractTwo phospholipids were designed and synthesized that have the property of forming liposomes which undergo a dramatic increase in permeability when irradiated with light (360 nm). Liposomes prepared from these phospholipids leak 100% of entrapped aqueous space marker, carboxyfluorescein, when irradiated for 30‐120 s (average light intensity 50 W/m2). Liposomes not irradiated showed much lower rates of temperature dependent release. Such liposomes may be useful as biochemical tools or drug delivery systems in vitro and in vivo.
INHIBITION OF ORNITHINE DECARBOXYLASE INDUCTION BY PSORALEN PLUS NEAR ULTRAVIOLET LIGHT IN HUMAN CELLS: THE ROLE OF MONOADDUCTS VS DNA CROSSLINKS
Authors: Prager A. , Green M. , Ben‐Hur E. 
Published: January 2008

AbstractTreatment of plateau‐phase human breast carcinoma cells with 4,5′,8‐trimethyl psoralen (TMP)‐plus‐near UV light (PUVA) inhibited the transcriptionally‐controlled induction of ornithine decarboxylase (ODC). The fluence response curve had a shoulder (Dq= 560 Jm−2) followed by an exponential decline (Do= 690 Jm−2). The cells could not recover from a PUVA dose that inhibited ODC induction by 50% or more. This is consistent with the lack of removal of TMP monoadducts and DNA crosslinks following a similar dose. However, removal of labeled TMP and DNA crosslinks was observed after lower doses during a 24 h period. Using the two‐dose approach (Ben‐Hur and Elkind, 1973) it was shown that crosslinks are more efficient than TMP monoadducts in inhibiting ODC induction. The same phenomenon was also found with regard to inhibition of RNA synthesis.
SUNLIGHT‐INDUCED KILLING OF NONDIVIDING HUMAN CELLS IN CULTURE
Authors: Kantor G.J. , Ritter C. 
Published: January 2008

AbstractNondividing populations of human diploid fibroblasts that are DNA excision repair proficient (WS‐1, KD. SSCW) and repair deficient (XP12BE) were exposed to mid‐day summer sunlight for a determination of survival based on an ability of cells to remain attached to a culture vessel surface. Whereas mid‐ and far‐UV wavelengths and radiation emitted from a sunlamp cause a gradual degeneraton and detachment of cells in a dose‐dependent manner, sunlight does not promote cell killing that is evidenced by these criteria in repair proficient cells. Detachment of repair deficient cells is promoted to a limited extent but only at sunlight exposure times that are low with respect to the amount of DNA damage (pyrimidine dimers) induced. Repair proficient and deficient cells exposed to sunlight for longer times do not detach but are incapable of excuding a viable stain several days after exposure and appear as histologically fixed cells. Pyrimidine dimer levels in these sunlight irradiated cells were great enough to have promoted detachment had these levels been induced by UV (254 nm) alone. Other photodamage induced by these exposures evidently inhibits the dimer‐induced cell degeneration that leads to cell detachment. We conclude that pyrimidine dimers are responsible for cell killing at short sunlight exposure times (< 40 min) but that at longer exposures (> 80 min) cells arc killed by a different mechanism that is independent of dimer‐caused death.
PREVENTION BY PHYTOCHROME OF PHOTODELAY IN CHLOROPHYLL ACCUMULATION
Authors: Oelze‐Karow H. , Rösch H. , Mohr H. 
Published: January 2008

AbstractA photodelay in chlorophyll‐a and ‐b accumulation is observed in mustard (Sinapis alba L.) cotyledons during the first 3 h after the onset of white light even at medium light fluxes (3500 lx). A pretreatment of two red light pulses or a 12 h far‐red light pretreatment, both operating through phytochrome. prevent the photodelay completely. This is a specific phytochrome effect since'it can be separated from the effects of phytochrome on the rates during pre‐steady state and steady state phases of chlorophyll accumulation in saturating white light. Thus, photostability of chlorophyll in nature is a photoresponse mediated through phytochrome.
SPECTRAL CHANGES IN CHLOROPLASTS DURING AGING
Authors: Brody S. S. 
Published: January 2008

AbstractThe spectral properties of photosynthetic and accessory pigments of chloroplasts can change significantly over the course of an experiment which may last a couple of hours. As chloroplasts age at room temperature, there are decreases in absorbance at 708, 678, 510, 484, 465 and 432 nm. Chlorophylls absorbing at long wavelength (708 nm) and carotenoids (510 nm) are most sensitive to the aging process. The decrease in absorbance at 510 nm could indicate that aging results in a decrease in electrical potential across the thylakoid membrane.
THE LETHAL EFFECT OF LONGWAVE ULTRAVIOLET LIGHT AND PUVA. AN ANALYSIS BASED UPON HUMAN MESENCHYMAL CELLS IN VITRO
Authors: Jongh G. de , BERGERS MIEKE , Boezeman J. B. M. , Verhagen A. R. , Mier P. D. 
Published: January 2008

Abstract— The lethal effect of UVA and PUVA radiation was studied in cultures of fresh and mature monocytes. UVA radiation alone was shown to possess a lethal effect at doses which are attained in the dermis in vivo. The synergistic action of 8‐methoxypsoralen and UVA radiation predominated in PUVA radiation, but again a residual effect of UVA alone was demonstrated mathematically. Mature cells were less sensitive than fresh monocytes.Our results indicate that a monolayer culture of non‐dividing, mesenchymal cells offers considerable advantages over in vivo systems as a model for the study of phototoxicity.
CONFIGURATIONAL PHOTOISOMERIZATION OF BILIRUBIN IN VITRO—I. QUENCHING OF Z→E ISOMERIZATION BY TWO‐WAVELENGTH IRRADIATION
Authors: Pratesi Riccardo , Agati Giovanni , Fusi Franco 
Published: January 2008

Abstract A simple rate‐equation theory of configurational photoisomerization of bilirubin (BR) is presented and used to discuss the Z→E photoisomerization of BR in HSA solutions irradiated with laser light in the blue‐green spectral region. The analytical expression of Z, E‐BR:HSA (PBR) concentration at photoequilibrium (PE) is used to derive the PBR concentration from the spectrophotometric data on absorbance difference spectra. The PBR values are in good agreement with those recently reported in the case of 10 nm‐bandwidth filtered light. Both sets of data give a best‐fit value of the BR, PBR quantum yield ratio equal to 2.3 in the case of BR:HSA ratio equal to 1:2.Successive irradiation of BR/HSA solutions with different wavelengths (457/488/457 nm) provides further support for the reversibility of the photoreaction. However, differences between the intermediate PE values have been found, and may reveal departures from the simple Z,Z→Z,E isomerization in BR/HSA solutions.The possibility of controlling the formation of Z, E‐BR/HSA has been demonstrated using simultaneous irradiation with blue (457 nm) and green (514 nm) laser beams. The two‐wavelength scheme takes advantage of the reversibility of the BRIPBR reaction, and of the differences between BR/PBR absorption spectra and quantum yields. Efficient quenching of PE PBR is achieved when green substantially exceeds (10–40 times) blue light intensity. This experiment may simulate what actually occurs during clinical phototherapy with white and green fluorescent lamps, where the quenching of PBR at the formation sites may prevent diffusion of this slowly excreted isomer and, at the same time, increase the formation of the more rapidly excretable structural, non‐reversible isomers, such as lumirubin.
MONOLAYER STUDIES OF 5‐(4‐CARB‐ OXYPHENYL)‐10,15,20‐TRITOLYL‐PORPHYRIN‐II. PHOTOVOLTAIC STUDY OF MULTILAYER SANDWICH CELLS*
Authors: Bardwell Jennifer A. , Bolton James R. 
Published: January 2008

AbstractThe photovoltaic behavior of multilayer sandwich cells fabricated from the title compound has been examined. These multilayers are amorphous and contain a wide range of aggregated species. The action spectrum of the photocurrent agrees qualitatively with the absorption spectrum. This indicates that the photocurrent arises from all species in the film.The shape of the dark current‐voltage characteristics varied with the porphyrin thickness. For thin films, (1 and 3 monolayers) the current can be described by a tunnelling mechanism. For thick cells (29 monolayers) the current‐voltage characteristic can be fitted using either of two models: a modified Shockley equation (suggesting that the dye acts as a p‐type semiconductor) or a combination of Schottky and Frenkel–Poole emission (suggesting that the porphyrin acts as an insulator). The former interpretation is preferred because it is consistent with the observed rectification characteristics; nevertheless, the latter is in agreement with the magnitude of the conductivity of the films.The power‐conversion efficiencies of these cells were quite low (∼4 × 10‐4% for incident white light of intensity 2.72 W m‐2) owing to the very large internal resistance of the cells. The high resistance can be explained by observing that the molecules are in a very unfavorable orientation; maximum conductivity would be expected for the porphyrin ring systems perpendicular to the direction of current flow to give maximum overlap of the systems.
QUANTITATION OF THE PHOTOMUTAGENIC RESPONSE OF Salmonella TO AN EASTERN SHALE OIL AND FLUORESCENT LIGHT
Authors: Selby Christopher , Calkins John , Enoch Harry G. 
Published: January 2008

AbstractThe dose‐response relationship for photomutation (i.e. photosensitized mutation) by a shale‐derived oil was examined. The Ames’Salmonella typhimurium tester strain TA98 was exposed to several concentrations of an Eastern shale oil and UV‐visible radiation from illumination‐type fluorescent lamps. Reversion to histidine prototrophy and survival were assayed following various radiation doses. Reciprocity of shale oil concentration and radiation exposure over approximately 10‐fold ranges of oil concentrations and radiation doses was observed with revertant numbers per plate, percent survival, and the induced frequency of revertants (revertants per survivor). The relationship between mutation frequency and the product (shale oil concentration times radiation exposure) fit well with either a linear model or a power law model in which the frequency of induced mutations was described by the product dose raised to the 1.26th power. Similar dose‐response relationships provide potential criteria for comparing potency of photomutagenic substances, comparisons that may be valuable towards assessing, and perhaps modifying, risks imposed by human exposure to synthetic fuels.
UTILIZATION OF HEAVY‐ATOM EFFECT QUENCHING OF PYRENE FLUORESCENCE TO DETERMINE THE INTRAMEMBRANE DISTRIBUTION OF HALOTHANE
Authors: Washington Kay , Sarasua Martha M. , Koehler Lynda S. , Koehler Karl A. , Schultz John A. , Pedersen Lee G. , Hiskey Richard G. 
Published: January 2008

AbstractThe interaction of halothane (CF3CHBrCl) with dipalmitoylphosphatidylcholine (DPPC) membranes containing varying amounts of dipalmitoylphosphatidylglycerol (DPPG) was examined via heavy atom effect quenching of pyrene fluorescence by halothane. The effect of halothane on pyrene fluorescence is consistent with a kinetic model based upon the assumption of the existence of two populations of pyrene in the membrane: one accessible to interactions with halothane; the second inaccessible to halothane on the time scale of the pyrene fluorescence excited state. Both populations of pyrene are affected by the presence of halothane in the membrane. The rate of halothane quenching of pyrene fluorescence is increased significantly for all DPPG/DPPC membranes compared to pure DPPC membranes indicating that any DPPG in the membrane facilitates interaction between halothane and pyrene even though the measured partition coefficients indicate that little change in total halothane concentration in the membrane as a whole occurs as a function of percent DPPG in DPPG/DPPC mixtures.It is speculated that phase boundaries play an important role in determining the behavior of this model system by determining the location of the pyrene probe. The heavy atom effect quenching of pyrene by halothane provides a useful probe of phase boundaries in membranes.
AN ACTION SPECTRUM OF PHOTOREACTIVATING ENZYME FROM SEA URCHIN EGGS
Authors: Shiroya Tsugio , McElroy Douglas E. , Sutherland Betsy M. 
Published: January 2008

AbstractAn action spectrum for photoreactivating enzyme activity from unfertilized eggs of the sea urchin Hemicentrotus pulcherrimus was determined. The range of the spectrum is 313 to 500 nm, with a maximum at 365 nm. Comparison of this spectrum with that for photorecovery of developmental damage in the sea urchin embryo indicates the general similarity of the two processes.