bluuebunny/crossref_metadata_2025_split huggingface dataset:
POTENTIAL EFFECTS OF ALTERED SOLAR ULTRAVIOLET RADIATION ON HUMAN SKIN CANCER
Authors: Urbach Frederick 
Published: January 2008

Abstract–There is highly significant evidence that non‐melanoma skin cancers are primarily due to chronic repeated exposure to solar ultraviolet radiation, and that there is a significant, although somewhat different relationship between solar radiation and the development of cutaneous malignant melanoma.Recent experimental and epidemiologic studies show that the biologically most effective UVR wavelengths are in the segment of the solar UVR spectrum that would be significantly augmented by decreases in stratospheric ozone content.A recent report on measurements of column ozone changes in the stratosphere has shown that in the past 18 yr, there has been an ozone decrease between 2 and 3%, greater in the winter months, and somewhat differing with latitude in the Northern Hemisphere.Calculations of the relationship of ozone decrease to increase in biologically effective UVR show great dependence on the biologic action spectrum assumed.Based on extensive epidemiologic studies of skin cancer incidence, it appears that the estimated increase in biologically effective UVR due to the measured ozone decreases in the past (almost) two decades are not likely to be the cause of the sharp increase in skin cancer incidence which have been observed. Most likely these increases in incidence are the result of increasing personal exposure, due to striking changes in personal behavior that have taken place for social reasons.However, there is every reason to believe that increases in biologically effective UVR due to stratospheric ozone decreases will have significant impact on human skin cancer incidence in the future.
CONTROL OF PHOTOSYNTHETIC REDUCTANT: THE ROLE OF LIGHT AND TEMPERATURE ON SUSTAINED HYDROGEN PHOTOEVOLUTION BY Chlamydomonas sp. IN AN ANOXIC, CARBON DIOXIDE‐CONTAINING ATMOSPHERE*
Authors: Graves Duane A. , Tevault Carol V. , Greenbaum Elias 
Published: January 2008

Abstract–Sustained hydrogen photoevolution fromChlamy domonas reinhardtiiandC. Moewusiiwas measured under an anoxic, CO2‐containing atmosphere. It has been discovered that light intensity and temperature influence the partitioning of reductant between the hydrogen photoevolution pathway and the Calvin cycle. Under low incident light intensity (1‐3 W m‐2) or low temperature (approx. 0°C), the flow of photosynthetic reductant to the Calvin cycle was reduced, and reductant was partitioned to the hydrogen pathway as evidenced by sustained H2photoevolution. Under saturating light (25 W m‐2) and moderate temperature (20±5°C), the Calvin cycle became the absolute sink for reductant with the exception of a burst of H2occurring at light on. This burst of H2corresponded to the expression of about 450 electrons for each photosynthetic electron transport chain. These results suggest that the hydrogen pathway and the Calvin cycle compete for reductant under anoxic conditions and that partioning between the two pathways can, to a certain extent, be controlled by the appropriate choice of experimental conditions.
PHOTOINTERACTION OF BENZOPHENONE TRIPLET WITH LYSOZYME
Authors: ENCINAS M. V. , LISSI E. A. , VASQUEZ M. , OLEA A. F. , SILVA E. 
Published: January 2008

AbstractThe quenching of the benzophenone triplet by lysozyme and its constituent amino acids in aqueous solutions have been studied. Native lysozyme quenches the benzophenone triplet with a high rate constant, 4 × 109M‐1s‐1. The quenching process takes place with production of significant amounts of free ketyl radicals, φketyl=0.56, but with a very low benzophenone consumption yield (0.022). The consumption yield is considerably smaller than that observed for the free amino acids. This difference can be explained in terms of a dominant back hydrogen transfer to the protein in the disproportionation of the free radicals produced. Reduced and carboxymethylated lysozyme shows a higher quenching rate (7.8 × 109M‐1s‐1) and a larger benzophenone consumption yield (0.07).The deactivation of the benzophenone triplet by the native protein leads to its inactivation, with a quantum yield of 0.01. Tryptophan and arginine residues are destroyed with a quantum yield of 0.01. In the modified enzyme tryosine and methionine groups are also consumed.
UV LASER INDUCED RNA‐PROTEIN CROSSLINKS AND RNA CHAIN BREAKS IN TOBACCO MOSAIC VIRUS RNAin situ
Authors: DOBROV E. N. , ARBIEVA Z. KH. , TIMOFEEVA E. K. , ESENALIEV R. O. , ORAEVSKY A. A. , NIKOGOSYAN D. N. 
Published: January 2008

AbstractThe efficiency of RNA‐protein crosslink and RNA chain break formation under nanosecond or picosecond UV‐laser pulse irradiation of tobacco mosaic virus was determined. It was found that on high‐intensity UV‐laser irradiation the quantum yields of both reactions increase considerably as compared to the usual (low‐intensity) UV‐irradiation. The RNA‐protein crosslink quantum yield was found to be 1.8 × 10‐5and 1.2 × 10‐4and that of RNA chain breaks 1.7 × 10‐4and 8.9 × 10‐4for nanosecond and picosecond irradiation, respectively.
EFFECT OF PHOTODYNAMIC THERAPY ON ANTITUMOR IMMUNE DEFENSES: COMPARISON OF THE PHOTOSENSITIZERS HEMATOPORPHYRIN DERIVATIVE AND CHLORO‐ALUMINUM SULFONATED PHTHALOCYANINE
Authors: MARSHALL J. F. , CHAN W.‐S. , HART I. R. 
Published: January 2008

AbstractThe effects of the two photosensitizers chloroaluminum sulfonated phthalocyanine (CIAlSPc) and hematoporphyrin derivative (HpD) on the functional activities of macrophages and natural killer (NK) cells, two immunocyte populations implicated in the control of tumor development and spread, have been investigated. Murine peritoneal macrophages treated in vivo with CIAlSPc or HpD at 10 mg/kg body weight showed no impairment of Fc‐mediated phagocytic capacity and only minor disturbances of in vitro tumoricidal/tumoristatic function. The NK cell activity of splenocytes obtained from photosensitizer‐treated mice, assayed 24 or 48 h after i.v. injection of CIAlSPc or HpD at 10 mg/kg was unaffected compared to controls. However significant inhibition of NK activity was observed when splenocytes obtained from mice with or without subcutaneous Colo 26 tumors, treated with CIAlSPc plus laser therapy (675 nm) were used as effector cells. The results show that impairment of some anti‐tumor activity can be observed in phthalocyanine treated or phthalocyanine + laser‐treated animals but this relatively minor impairment may augur well for the use of systemic phthalocyanine administration in photodynamic therapy.
SPECTROSCOPIC AND ORIENTATIONAL PROPERTIES OF CHLOROPHYLLaAND CHLOROPHYLLbIN LIPID MEMBRANES
Authors: GURP M. VAN , HEIDE U. VAN DER , VERHAGEN J. , PITERS T. , GINKEL G. VAN , LEVINE Y. K. 
Published: January 2008

AbstractLinear dichroism and fluorescence depolarization measurements on chlorophyllaand chlorophyllbmolecules incorporated into macroscopically oriented multibilayers of the plant lipid digalactosyldiacylglycerol (DGDG) are presented. The results are combined with measurements of fluorescence anisotropy to obtain both the order parameters describing the orientational statistics and the directions of the absorption and emission transition moments in the frame of the molecules. The problem presented by the overlapping nature of the absorption and emission bands is overcome by determining the fluorescence depolarization at the two maxima of the emission spectrum.
PHOTOINDUCED ELECTRON TRANSFER ACROSS LIPID BILAYERS CONTAINING MAGNESIUM OCTAETHYLPORPHYRIN
Authors: ILANI ASHER , WOODLE MARTIN , MAUZERALL DAVID 
Published: January 2008

AbstractBoth photoinitiated (thermodynamically downhill) and photodriven (thermodynamically uphill) electron transfer reactions across lipid bilayers are sensitized by magnesium octaethyl porphyrin (MgOEP). It is shown that the reaction mechanism is via reduction of photoexcited MgOEP at the reducing (ascorbate) side of the bilayer and the charge carrier is likely the neutral protonated MgOEP anion. The MgOEP cation (or its neutral form) does not contribute to charge passage across the bilayer even though it is readily formed at the acceptor (ferricyanide or methyl viologen) side of the membrane. Photoelectric measurements on planar bilayers show that the time constant for reduction of excited MgOEP is about 10 µS with 10 mM ascorbate. The membrane transport of the mediator appears to be rate limiting when the reaction is photoinitiated and the interfacial reaction appears to be limiting when the reaction is photodriven. The quantum yield of the process is about 0.1 in the latter case and about 0.02 in the former. The former yield is increased to about 0.15 in the presence of a redox mediator, duroquinone. In these systems, the magnesium porphyrin is both sensitizer and trans membrane redox mediator.
MODEL FOR THE GLOBAL IRRADIANCE OF THE SOLAR BIOLOGICALLY‐EFFECTIVE ULTRAVIOLET‐RADIATION ON INCLINED SURFACES
Authors: Schauberger Günther 
Published: January 2008

Abstract— The body surface area of man is the relevant receiving surface for solar UV radiation. To consider this body surface geometry, the biologically‐effective UV radiation of the solar global radiation was measured. This was done at 26 differently aligned measuring points whose orientation was determined by the angle of inclination (vertical) and the azimuth (horizontal). Approximately eight hundred sets of measurement series were carried out at 33 different sites. A simple model, developed from the data obtained, made it possible to calculate relative irradiance as a function of the angle of inclination and the ground reflection (UV albedo). Thus relative risk of solar UV exposure to different regions of the body can be assessed.In addition to this, if the irradiance on a horizontal plane (measured or calculated by a corresponding model) is taken into consideration, the absolute values for UV irradiance on tilted planes can be determined.
ULTRAVIOLET‐RADIATION and SKIN CANCER. EFFECT OF AN OZONE LAYER DEPLETION
Authors: Henriksen Thormod , Dahlback Arne , Larsen Søren H.H. , Moan Johan 
Published: January 2008

AbstractThe effect of changes in the ozone layer on the incidence of skin cancer was explored using data for Norway. Attempts were made to arrive at a relationship between the ‘environmental effective UV‐dose’ and the skin cancer incidence. Norway is well suited for this purpose because of the large variation in the annual UV‐dose from north to south. Furthermore we have a well developed cancer registry and a homogeneous population with regard to skin type.Four different regions of the country, each with a broadness of 1° in latitude (approximately 111 km), were selected (located around 69.5, 63.5, 60 and 58.5° N). The annual effective UV‐doses for these regions were calculated, assuming normal ozone conditions throughout the year and the action spectrum proposed by CIE, which extends up to 400 nm. The incidence rate (in the period 1970–1980) of malignant melanoma and non‐melanoma skin cancer (mainly basal cell carcinoma) increased with the annual environmental UV‐doses. For both these types of cancer a quadratic dose‐effect relationship seems to be valid to a first approximation.The present data indicate that the incidence of skin cancer would increase by approximately 2% for each percent ozone reduction.
PHOTOSENSITIZED PROCESSES in vivo: PROPOSED PHOTOTHERAPEUTIC APPLICATIONS*
Authors: Jori Giulio 
Published: January 2008

Abstract—The use of photosensitizing dyes having intense absorption bands in the 600–900 nm spectral interval opens up new prospects in the field of photochemotherapy, because it allows the illumination of relatively large tissue volumes with no significant damage to photosensitizer‐free tissues. Special interest is currently focused on the photodynamic therapy of solid tumors, because of the property of several dyes with a macrocyclic chemical structure (porphyrins, chlorins, phthalocyanines, xanthenes) to accumulate in significant amounts and be retained for prolonged periods of time by neoplastic lesions. Strategies are being developed for enhancing the selectivity of tumor targeting by photosensitizers through the exploitation of functional or biochemical differences between normal and malignant cells.
THE PHOTODYNAMIC EFFECT OF ROSE BENGAL ON PROTEINS OF THE MITOCHONDRIAL INNER MEMBRANE
Authors: Giulivi Cecilia , Sarcansky Monica , Rosenfeld Esteban , Boveris Alberto 
Published: January 2008

Abstract— Photodynamic action promoted by Rose Bengal was evaluated in solutions of unsaturated fatty acids or histidine, and on beef heart submitochondrial particles. Rose Bengal‐promoted photo‐oxidation of histidine was mainly due to the opening up of the imidazole ring by singlet oxygen. Photosensitization of polyunsaturated fatty acids (PUFA) resulted in oxygen consumption and thiobar‐bituric acid‐reactive substances (TBARS) formation, the extent of which was linearly related to the increasing degree of unsaturation. Photosensitization of submitochondrial particles caused oxygen consumption and TBARS production. These processes involved two different reaction components: during the first, most of the mitochondrial proteins were inactivated, the most sensitive being succinate dehydrogenase and cytochrome c. The values for the rate ratios of [TBARS] formation/[02] consumption for the first and second phase were 0.36 and 1.32%, respectively, pointing to a larger contribution of lipid peroxidation during the second phase.The calculation of the rate constants for reaction of singlet oxygen with mitochondrial proteins suggests that singlet oxygen is more reactive towards proteins than to PUFA. The biological role of this selectivity is discussed in terms of the mitochondria as one of the first targets for photosensitized reactions.
LIGHT DAMAGE IN THE RAT RETINA: EFFECT OF A RADIOPROTECTIVE AGENT (WR‐77913) ON ACUTE ROD OUTER SEGMENT DISK DISRUPTIONS
Authors: Remé Charlotte E. , Braschler Urs F. , Roberts Joan , Dillon James 
Published: January 2008

AbstractPrimary events in the course of light induced retinal lesions are still not fully elucidated. Under chronic conditions, lipid peroxidation in the retina and death of photoreceptor cells are observed. The radioprotective agent WR‐77913 scavenges singlet oxygen, hydrated electrons and free radicals. WR‐77913 was used to protect against acute light induced photoreceptor outer segment membrane disruptions in the rat retina. There was a partial but not complete protection at higher illuminance levels (800 lx for 30 min), whereas threshold lesions (400 lx for 30 min) were almost completely prevented. These observations indicate an involvement of photodynamic reactions in causing acute ohotoreceDtor lesions.
In vitro UPTAKE OF DICARBOXYLIC PORPHYRINS BY HUMAN ATHEROMA. KINETIC and ANALYTICAL STUDIES
Authors: Delettre E. , Brault D. , Bruneval P. , Vever‐Bizet C. , Dellinger M. , Delgado O. , Camilleri J. P. , Gaux J. C. , Peronneau P. 
Published: January 2008

AbstractHuman atheromatous aorta segments as well as presumably disease‐free control aorta were obtained at autopsy. They were incubated with solutions of various purified dicarboxylic porphyrins including hematoporphyrin (HP) and hydroxyethylvinyldeuteroporphyrin (HVD), and with solutions of Photofrin®. Selective labelling of the atheroma was shown by macroscopic and microscopic observations of the characteristic porphyrin fluorescence associated with the atheromatous plaques. The time dependence of the uptake, monitored by absorption spectrophotometry or by high performance liquid chromatography, was inferred from the disappearance of the porphyrins in the incubation medium. Significant binding was observed in the absence of albumin or serum proteins. The uptake of HP was less than that of the more hydrophobic compounds HVD or Photofrin when these porphyrins were used alone. The presence of albumin or serum drastically reduces atheroma labelling. Some competition between HP and HVD for binding sites is also seen. The present results do indicate that hydrophobic porphyrins have an intrinsic affinity for atheroma and that they can be taken up through passive processes. Taking into account previous data on animal models (Photochem. Photobiol. (1989) 49,731–737), it appears however that, in vivo, interactions with proteins and pharmacokinetics will primarily determine plaque labelling.
METABOLISM OF 5‐METHOXYPSORALEN BY Saccharomyces cerevisiae
Authors: Morichetti E. , Ceragioli C. , Cundari E. , Carratore R. Del , Fiorio R. , Bronzetti G. , Averbeck D. 
Published: January 2008

AbstractIncubation of methoxypsoralen (5‐MOP) in the presence of diploid yeast cells (Saccharomyces cerevisiae) before UV‐A exposure leads to an incubation‐time dependent decrease of photoinduced genotoxic effects. The reduction in photoinduced genotoxicity is stronger in cells grown in the presence of 20% glucose and containing high levels of cytochrome P‐450 than in cells grown in the presence of 0.5% glucose and containing undetectable levels of cytochrome P‐450. Inhibition of P‐450 activity by specific inhibitors, such as tetrahydrofuran and metyrapone, strongly affects the observed decrease in 5‐MOP genotoxicity, indicating the involvement of P‐450 in 5‐MOP metabolism. As demonstrated by spectrophotometric and chromatographic (HPLC) analysis during incubation of 5‐MOP with P‐450 containing yeast cells, 5‐MOP gradually disappears from the cell supernatant of the incubation mixture. The reduction in the chromatographic peak corresponding to 5‐MOP is accompanied by the appearance of a new peak that probably corresponds to a metabolite. As shown by the use of P‐450 specific inhibitors, the metabolite appears to be due to P‐450 mediated 5‐MOP metabolisation. Its UV absorption spectrum suggests an alteration of the pyrone moiety of the 5‐MOP molecule.
THE EFFECT OF FLUORIDE ON BINDING and PHOTODYNAMIC ACTION OF PHTHALOCYANINES WITH PROTEINS
Authors: Ben‐Hur E. , Dubbelman T. M. A. R. , Steveninck J. Van 
Published: January 2008

AbstractFluoride inhibits chloroaluminum phthalocyanine tetrasulfonate (AIPcS)‐induced photo‐hemolysis when added to dye loaded cells prior to light exposure. The mechanism by which F˜ exerts this effect was studied by measuring the binding of phthalocyanine (Pc) to various proteins in the absence and presence of F−. Parallel measurements were made of the photodynamic action under these conditions. Fluoride reduced the binding to proteins of AIPcS and CoPcS. The binding of CuPcS, ZnPcS and H2PcS was not affected. When bound to bovine serum albumin and exposed to light, H2Pc, ZnPc and AIPcCI were bleached at a biphasic rate. Only the photobleaching of AIPcCI was affected by F−. The effect of F” was to inhibit the initial rapid phase without affecting the slower phase. In the presence of D2O only the second phase of photobleaching was enhanced, in the absence or presence of F−. No effect of F− was observed on tryptophan photooxidation or glyceraldehyde‐3‐phosphate dehydrogenase photoinactivation by AIPcS. Crosslinking of spectrin monomers photosensitized by AIPcS was inhibited by F− in parallel with the reduced binding of dye to the protein. It is concluded that F˜ exerts its effect by complexing with metal ligands of Pc. As a result, the dye may be released from the protein or the binding mode may be changed in such a way that effective photochemistry is prevented. Primary photophysical processes of Pc most probably are not affected by F−
DEACTIVATION OF SINGLET MOLECULAR OXYGEN BY ORGANO‐SELENIUM COMPOUNDS EXHIBITING GLUTATHIONE PEROXIDASE ACTIVITY and BY SULFUR‐CONTAINING HOMOLOGS*
Authors: Scurlock R. , Rougee M. , Bensasson R.V. , Evers M. , Dereu N. 
Published: January 2008

AbstractThe bimolecular rate constants (k) of quenching of molecular singlet oxygen 1O2 (1DLg) by organo‐seleniura compounds exhibiting glutathione peroxidase activity and by sulfur analogs have been determined by time resolved phosphorescence detection of 1O2 in CD3OD and C6D6, with no solvent effect.The rate constants of quenching by the Se‐containing compounds were found to be approximately one order of magnitude higher than those of the S‐containing homologs. A linear correlation was observed between log k and the Hammett constant σortho with p = ‐0.89, the rate constant being higher for molecules with an electron‐donating substituent and lower for those with an electron‐withdrawing substituent. This observation is consistent with the involvement of a charge transfer complex in the deactivation of singlet oxygen.
INVOLVEMENT OF THYLAKOID MEMBRANE‐DEPENDENT PHOTOSENSITIZATION IN PHOTOINHIBITION OF THE CALVIN CYCLE ACTIVITY IN SPINACH CHLOROPLASTS
Authors: Jung Jin , Kim Yong Wook 
Published: January 2008

AbstractPhotoinhibition of the light‐regulated key enzymes of the photosynthetic carbon reduction (PCR) cycle was investigated using chloroplasts isolated from spinach leaves. Light quality dependence of the light‐induced activity change (activation or inactivation) of key PCR enzymes in situ demonstrated that, while light activation is promoted mainly by red light (Λ.> 600 nm), inactivation takes place largely in the region of blue light (Λ < 500 nm). Inactivation was suppressed by a lipid soluble singlet oxygen (1O2,1Δg) quencher. When “stromal protein” was subjected to a severe photoinhibitory treatment, no significant loss of activity was observed for any PCR enzyme assayed. However, the inclusion of thylakoids in the photolysis system resulted in a substantial inactivation of the enzymes; this inactivation was significantly diminished in the presence of imidazole and enhanced to some extent by a partial deuteration of medium. In contrast, superoxide dismutase did not exert any effect. The blue light‐induced inactivation of the enzymes was remarkably decreased in the presence of thylakoids whose Fe‐S centers were destroyed. The results obtained in this study suggest that photoinactivation of the PCR enzymes in situ is mediated mainly by 1O2, which is photoproduced primarily by the Fe‐S centers of thylakoids and diffuses into the stroma.
INVOLVEMENT OF PHYTOCHROME IN LIGHT CONTROL OF STEM ELONGATION IN CUCUMBER (Cucumis sativus L.) SEEDLINGS
Authors: DRUMM‐HERREL H. , MOHR H. 
Published: January 2008

Abstract—Stem growth in cucumber (Cucumis sativus L.) is strongly affected by blue light (B). The pending problem has been to what extent the action of B is related to phytochrome action.Hypocotyl growth in the etiolated cucumber seedling responds weakly to 5 min red (R) and B pulses whereas far‐red (FR) and long wavelength far‐red (RG9) light pulses have no effect. Blue and RG9‐light pulses were given in sequence or 5 min B was applied simultaneously with high fluence rate R (phytochrome photoequilibrium, Pfr/Ptot =∼ 0.8) or RG9‐light (? 0.01) to maintain a high or low during application of the B pulse. The results show that there is no expression of a B effect if the level of Pfr is kept low. A specific effect of B probably occurs but cannot be expressed in the absence of Pfr.Hypocotyl elongation is strongly affected by continuous R, FR and B. Light ← dark transfer experiments suggest that growth in darkness of seedlings de‐etiolated by R or B is controlled by phytochrome through a threshold mechanism.The results of dichromatic experiments (long wavelength far‐red light, 756 nm, applied simultaneously with B or R) show that the action of B on axis elongation is related to the level of Pfr, even in long‐term light. When > 0.01, the action of B is largely abolished. The residual B effect may not be attributed to a phytochrome‐independent action of B on axis elongation, because a small residual effect is also observed with dichromatic R/756 nm‐light.