bluuebunny/crossref_metadata_2025 huggingface dataset:
DISTRIBUTION AND ELIMINATION OF PHOTOFRIN II IN MICE
Authors: Bellnier David A. , Ho Yau‐Kwan , Pandey Ravindra K. , Missert Joseph R. , Dougherty Thomas J.
Published: January 2008

Abstract—

The distribution and elimination of [14C]PH, the radioisotopically‐labeled equivalent of the mixture of porphyrins known as Photofrin II used in the photodynamic treatment of solid tumors, were determined in tumor‐free and SMT‐F tumor‐bearing DBA/2 Ha‐DD mice. Following i.p. injection, drug was absorbed from the peritoneum with a half‐life of about 1 h; elimination from plasma was rapid, declining about 1.4 logs in concentration over 48 h following i.v. administration. However, some [14C]‐activity was still detectable after 75 days. Normal tissues take up the drug within about 7.5 h after administration, with peak concentrations distributed as follows: liver, adrenal gland, urinary bladder > pancreas, kidney, spleen > stomach, bone, lung, heart > muscle > brain. Only skeletal muscle, brain, and skin located contralaterally to subcutaneously implanted SMT‐F tumors had peak [14C]‐activities lower than tumor tissue; skin overlying SMT‐F tumors showed concentrations not significantly different (P > 0.3) from tumor. After 75 days all tissues examined retained some fraction of [14C]‐activity, ranging from 16% for kidney to 61% for spleen, of the initial peak tissue levels. The primary route of elimination of Photofrin II was through the bile‐gut pathway, with greater than 59% of the administered [14C]‐activity recovered in the feces, and only about 6% in the urine, over 192 h. HPLC analyses of fecal extracts showed that mostly monomeric and other low molecular weight porphyrin components of Photofrin II were eliminated. The higher molecular weight oligomeric fractions of Photofrin II were retained in liver and spleen up to 14 days after injection.
INACTIVATION AND MUTAGENESIS OF Herpes VIRUS BY PHOTODYNAMIC TREATMENT WITH THERAPEUTIC DYES
Authors: Lytle C.D. , Carney P.G. , Felten R.P. , Bushar H.F. , Straight R.C.
Published: January 2008

Abstract—

Dyes which photosensitize membranes may be clinically useful for photodynamic treatment (PDT) of Herpes simplex virus (HSV) infections. It is important to determine whether the enveloped HSV can be inactivated via membrane damage without affecting the genetic material. Selection of appropriate PDT conditions, including the choice of dye, could minimize viral mutagenesis. We determined the mutagenesis caused by PDT employing three membrane‐photosensitizing dyes of potential use in cancer photochemotherapy (Photofrin II, polyhematoporphyrin esters, zinc phthalocy‐anine tetrasulfonates) and a DNA‐photosensitizing dye (proflavine sulfate). The effects were compared to those caused by exposure of HSV to ultraviolet radiation(UV). The procedure consisted of incubating HSV with µ,g/ml (µM) concentrations of the dye, irradiating the samples with broad spectrum visible/near‐UV radition (Daylight fluorescent lamps) and assaying the survival of the treated HSV. Zinc phthalocyanine was the most potent dye per absorbed photon for inactivating HSV. In parallel with determination of survival, progeny of the surviving virus were grown for determination of mutagenesis. The progeny virus was harvested and subsequently assayed in the presence and absence of 40 µ,g/ml iododeoxycytidine (ICrd) to determine the frequency of mutation to ICrd resistance. Mutation frequencies were determined for progeny from the 1–4% survival level. For PDT with each membrane‐photosensitizing dye, only zinc phthalocyanine increased the mutation frequency over the untreated control. This increase was <2‐fold. Proflavine increased the mutation frequency 2–3 fold over the untreated control. Ultraviolet produced a 15–20 fold increase over the untreated control. Therefore, all four dyes were much less mutagenic than UV at the same toxicity level (P<0.0001), and the membrane‐photosensitizing dyes were less mutagenic than the DNA‐photosensitizing proflavine at the same toxicity level (P<.0001).
EFFECTS OF HEMATOPORPHYRIN DERIVATIVE ON THE CELLULAR ENERGY METABOLISM IN THE ABSENCE AND PRESENCE OF LIGHT
Authors: Khanum Farhath , Jain Viney
Published: January 2008

Abstract— Effects of Photofrin II on energy metabolism and metabolic viability were studied in a mammalian transformed cell line (BHK‐21) in dark and after photo‐irradiation with visible light. Cells were allowed to accumulate Photofrin by incubating for 4 h in buffer containing Photofrin (5–60µg/ml). The results show that Photofrin significantly affects the cellular energy metabolism even in the absence of light; activity of cytochrome c oxidase is decreased and glucose utilization and lactate production (glycolysis) are increased. Irradiation with light resulted in a significant decrease in the activity of cytochrome c oxidase, glycolysis, ATP content, energy charge, ratios of adenine nucleotides likeATP/ADP, ATP/AMP and cell viability (dye exclusion test). Presence of inhibitors of energy metabolism, potassium cyanide (respiration) and 2‐deoxyglucose (glycolysis), further enhanced the cytotoxic effects induced by hematoporphyrin derivative and light.
ULTRAVIOLET ACTION SPECTRA (280 to 380 nm) AND SOLAR EFFECTIVENESS SPECTRA FOR HIGHER PLANTS
Authors: Coohill Thomas P.
Published: January 2008

Several ultraviolet (UV) action spectra that typify the responses of higher plants to irradiation by wavelengths between 280 nm and 380 nm are shown. An attempt is made to generate common spectra that may be used, at least temporarily, to represent the effects of UV on such important biological parameters as photosynthesis. The goal is to provide an estimate of plant response to solar UV and to the potential increase in ground level UV postulated for a depleted stratospheric ozone layer. Solar plant damage effectiveness curves are generated under “normal” solar UV conditions, and under an assumed UV increase corresponding to a 16% depletion in total ozone. Additional effects due to ozone depletion are concentrated in the UV‐B region, especially at wavelengths between about 297 nm and 315 nm. Common features of these effectiveness curves are noted, and limitations are pointed out. As expected, no common spectrum has been found that can substitute for any specific spectrum nor that is unique enough to provide more than a limited first approximation of a plant damage spectrum. Additional information must be generated to fulfill this need.
POTENTIAL EFFECTS OF ALTERED SOLAR ULTRAVIOLET RADIATION ON HUMAN SKIN CANCER
Authors: Urbach Frederick
Published: January 2008

–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

–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

Abstract

The 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

Abstract

The 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

Abstract

The 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

Abstract

Linear 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

Abstract

Both 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.
SINGLET OXYGEN INVOLVEMENT IN THE INACTIVATION OF CULTURED HUMAN FIBROBLASTS BY UVA (334 nm, 365 nm) AND NEAR‐VISIBLE (405 nm) RADIATIONS
Authors: TYRRELL REX M. , PIDOUX MIREILLE
Published: January 2008

Abstract— The UVA (320–380 nm) radiation inactivation of mammalian cells is dependent upon the presence of oxygen. In order to examine the intermediates involved, we have irradiated cells in the presence of chemical probes which are able to modify the activity of various oxygen species. We have also examined the possibility that UVA inactivates cultured human fibroblasts via generation of intracellular hydrogen peroxide. An iron scavenger (desferrioxamine) and a hydroxyl radical scavenger (dimethylsulfoxide) protect the cells against hydrogen peroxide. Diethyldithiocarbamate (a superoxide dismutase inhibitor) and aminotriazole (a catalase inhibitor) sensitize the cells to this oxidizing agent. These data support previous reports that hydrogen peroxide inactivates as a result of the iron‐catalyzed generation of hydroxyl radical. None of these agents significantly alter the fluence‐dependent inactivation of cell populations by radiation at 365 nm. In contrast, the cells are sensitized to radiation at 334, 365 and 405 nm in the presence of deuterium (an enhancer of singlet oxygen lifetime) and are protected against radiation at 365 nm by sodium azide (a quencher of singlet oxygen). These results are consistent with the conclusion that the generation of singlet oxygen, but not hydrogen peroxide or hydroxyl radical, plays an important role in the inactivation of cultured human cells by UVA and near‐visible radiations.
MORE EFFICIENT EXCISION REPAIR OF PYRIMIDINE DIMERS IN THE SPECIFIC DNA SEQUENCE THAN IN THE GENOME OVERALL IN GOLDFISH CELLS
Authors: KOMURA JUN‐ICHIRO , MITANI HIROSHI , SHIMA AKIHIRO
Published: January 2008

Abstract— Excision repair of pyrimidine dimers induced by 254 nm UV was examined in the genome overall and in a specific sequence containing a transfected gene for hygromycin B resistance, in RBCF‐1 cells derived from a goldfish, by the use of UV endonuclease of Micrococcus luteus and alkaline agarose gel electrophoresis. More than 40% of dimers were removed from the specific sequence, while about 20% were removed from the genome overall, within 24 h after exposure to UV (2.5–7.5 J/m2).
SYSTEMIC IMMUNOSUPPRESSION INDUCED BY PHOTODYNAMIC THERAPY (PDT) IS ADOPTIVELY TRANSFERRED BY MACROPHAGES
Authors: LYNCH DAVID H. , HADDAD SANDRA , KING VERNON J. , OTT MARK J. , STRAIGHT RICHARD C. , JOLLES CHRISTOPHER J.
Published: January 2008

Abstract— Some derivatives of hematoporphyrins are strongly retained by tumor tissue as compared to normal tissue, and exposure of these photosensitizers to radiation in the visible spectrum can cause serious biological damage. These properties have been exploited in the development of a new treatment for cancer termed photodynamic therapy (PDT). However, recent studies have also demonstrated that PDT can also induce a state of systemic immunosuppression. The purpose of this study was to determine whether PDT‐induced suppression of contact hypersensitivity (CHS) responses was an active phenomenon that could be adoptively transferred by viable splenocytes from PDT‐treated mice. Although induction of adoptively transferable suppressor cells in PDT‐treated mice required exposure to antigen, the suppressor cells were found to be antigen nonspecific in their function. Furthermore, splenocytes from PDT‐treated mice were capable of generating levels of allospecific cytotoxic T lymphocyte (CTL) activity which were comparable to those generated by normal control mice, but the ability of irradiated spleen cells from PDT‐treated mice to stimulate a mixed lymphocyte response (MLR) was dramatically impaired. Finally, chromatographic separation of T cells, B cells and macrophages showed that the cell type which mediates adoptively transferable suppression of CHS responsiveness is in the macrophage lineage.
TOPICAL UROCANIC ACID ENHANCES UV‐INDUCED TUMOUR YIELD AND MALIGNANCY IN THE HAIRLESS MOUSE
Authors: REEVE VIVIENNE E. , GREENOAK GAVIN E. , CANFIELD PAUL J. , BOEHM‐WILCOX CHRISTA , GALLAGHER CLIFFORD H.
Published: January 2008

Abstract— Epidermal urocanic acid has been postulated to be the mediator of the specific state of immunosuppression induced by UV irradiation, by which UV‐initiated tumour cells are able to evade normal recognition and can survive to grow progressively into malignant tumours. These experiments demonstrate that topical application of UV‐irradiated urocanic acid systemically suppresses the contact type hypersensitivity response to oxazolone in hairless mice. In addition, topically applied urocanic acid markedly increases the overt tumour yield and the degree of malignancy in hairless mice exposed chronically to daily minimally erythema] doses of simulated solar UV light. Topical urocanic acid also increases the number of latent UV‐initiated tumours, detectable by croton oil promotion. Therefore UV photoproducts of urocanic acid can both systemically suppress contact hypersensitivitv in the epidermis, and also enhance early survival of UV‐initiated tumour cells resulting in augmentation of UV photocarcinogenesis.
NEAR UV‐INDUCED FREE RADICALS IN OCULAR LENS, STUDIED BY ESR AND SPIN TRAPPING
Authors: MURAKAMI JUNKO , OKAZAKI MASAHARU , SHIGA TAKESHI
Published: January 2008

Abstract— An electron spin resonance (ESR) study on UV‐photolysis of human and canine lens nuclei was carried out at room temperature. (1) At least two kinds of free radical signals, a narrow signal and a broad one, were detected at around g=2.004. The latter is similar to that observed upon irradiation of a model solution containing both tryptophan and cysteine. (2) Two spin adducts were detected upon irradiation of canine lens in the presence of a spin trapping reagent (DMPO, 5,5‐dimethyl‐1‐pyrroline N‐oxide), i.e. a spin adduct of sulphur‐centered radical (most likely glutathione thiyl radical) and the protonated adduct of solvated electron (presumably due to photo‐ionization of tryptophan). (3) A tentative and simplified reaction mechanism of UV‐induced damage is discussed on the basis of these observations.
POTENTIAL PHOTOSENSITIZERS FOR PHOTODYNAMIC TUMOR THERAPY—I. PHOTOPHYSICAL PROPERTIES OF TWO CHLORIN DERIVATIVES
Authors: Schermann G. , Volcker A. , Seikel K. , Schmidt R. , Brauer H.‐D. , Montforts F.‐P
Published: January 2008

Abstract— Photophysical properties of two chlorin type molecules (CHLI) and (CHLII) were investigated in different solvents. Quantum yields of fluorescence φF of S, → T, intersystem crossing φT, and of singlet oxygen (1Δg) formation φΔ, as well as the Stern‐Volmer constants for the quenching of the S, states by oxygen and the bimolecular rate constants of quenching of 1Δg by the chlorins were measured. The values of φT and φΛ can be given as 0.57 and 0.58 for CHLI and 0.69 and 0.58 for CHLII. The values of the fluorescence quantum yields, the strong absorption of the chlorins in the red (Λ > 630 nm) and the high values of the quantum yields for 1Δg formation recommend the chlorin derivatives as potential markers and photosensitizers for tumor therapy.
FLUORESCENCE SPECTRA OF BLOWFLY METAXANTHOPSINS
Authors: Kruizinga B. , Stavenga D. G.
Published: January 2008

Abstract— The main visual pigment of blowflies (xanthopsin, Vogt, 1983 Z. Naturforsch.38c,329–333) photoconverts into two thermostable metaxanthopsin states M and M'(e.g. Stavenga et al., 1984 Photochem. Photobiol.40,653–659). The fluorescence spectra of the two photoproducts were studied by microspectrofluorometry in vivo. The emission spectra of M and M'are very similar and peak at 660 nm. The excitation spectra of M and M'have peak wavelengths at Λmax ' 584 nm and = 568 nm respectively.
THE MOLECULAR and STEREOCHEMICAL STRUCTURES OF PHOTOPRODUCTS GENERATED BY UV‐IRRADIATION OF 4'‐HYDROXYMETHYL‐4,5',8'‐ TRIMETHYLPSORALEN IN AQUEOUS SOLUTION
Authors: Kao Joseph P. Y. , Isaacs Stephen T. , Hearst John E.
Published: January 2008

Abstract— UV irradiation of 4'‐hydroxymethyl‐4,5',8‐trimethyl psoralen (HMT) in aqueous solution yields three major photoproducts. We have isolated and characterized (1) a cyclobutane‐bridged dimer in which a cissyn linkage occurs between the furan end of one HMT moiety and the pyrone end of the other; (2) a cyclobutane‐bridged dimer wherein both HMT moieties are linked at their pyrone ends with probable cissyn configuration; and (3) an isomer of HMT for which we have proposed a structure in which the furan and pyrone ring oxygens assume a para orientation via photoisomerization.
In vivo TESTS OF THE CONCEPT OF PHOTODYNAMIC THRESHOLD DOSE IN NORMAL RAT LIVER PHOTOSENSITIZED BY ALUMINUM CHLOROSULPHONATED PHTHALOCYANINE
Authors: Patterson Michael S. , Wilson Brian C. , Graff Ronald
Published: January 2008

Abstract— In its simplest form, the photodynamic therapy (PDT) threshold dose model states that tissue necrosis due to PDT will occur if the number of photons absorbed by the photosensitizer per unit volume of tissue exceeds a critical value. This threshold is given by the product of photon fluence, photosensitizer concentration and specific absorption coefficient. To test the validity of this concept for PDT of normal rat liver sensitized with aluminum chlorosulphonated phthalocyanine (AISPC), all three of these parameters were varied by changing the injected AISPC dose, the wavelength of excitation and the irradiation geometry. The extent of necrosis caused by the treatment was consistent with the threshold model, except when the concentration of AlSPC in the liver exceeded 20 μg g−1. For this animal model, we estimate the threshold to be (3.8 ± 0.2) x 1019 photons cm −3
PHOTOTHERMAL DEFLECTION SPECTROSCOPY OF PHOTOSYNTHETIC PIGMENTS in vivo and in vitro
Authors: Lorrain Lucie , Havaux Michel , Tessier Alain , Leblanc Roger M.
Published: January 2008

Abstract— This Technical Note describes the design of a photothermal beam deflection apparatus which allows the easy and rapid measurement of thermal dissipation of absorbed light energy in various photosynthetic materials including whole plant leaves. This system is based on the “mirage effect” in which the refractive index gradient induced in a fluid in contact with the sample, irradiated with an intensity‐modulated light, causes the periodic deflection of a laser beam parallel to the sample surface. The deflection of the probe laser beam is detected by a position sensor, the output of which is processed by a lock‐in amplifier. Photothermal deflection signals can be monitored in vivo in intact leaves placed in various (liquid or gaseous) environments with a satisfactory signal‐to‐noise ratio between 100 (in water) and 50 (in air) at low modulation frequencies (ca 30 Hz). It is shown that this new and simple photothermal technique is a very sensitive tool for the measurement of absorption spectra of photosynthetic pigments both in vivo (leaves, algae or chloroplasts) and in model systems (Langmuir‐Blodgett and solid films of chlorophyll).
PHOTODYNAMIC LIPID PEROXIDATION IN BIOLOGICAL SYSTEMS*
Authors: Girotti Albert W.
Published: January 2008

Abstract— Oxidative degradation of cell membrane lipids in the presence of molecular oxygen, a sensitizing agent and exciting light is termed photodynamic lipid peroxidation (photoperoxidation). Like other types of lipid peroxidation, photoperoxidation is detrimental to membrane structure and function, and could play a role in many of the toxic as well as therapeutic effects of photodynamic action. Recent advances in our understanding of photoperoxidation and its biomedical implications are reviewed in this article. Specific areas of interest include (a) reaction mechanisms; (b) methods of detection and quantitation; and (c) cellular defenses (enzymatic and non‐enzymatic).
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

The 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.
PHOTOCHEMICAL STUDIES ON THE ANTIINFLAMMATORY DRUG DICLOFENAC
Authors: Moore Douglas E. , Roberts‐Thomson Sarah , Zhen Dong , Duke Colin C.
Published: January 2008

Abstract— Irradiation with UVA light of the anti‐inflammatory drug diclofenac [2‐(2,6‐dichloroanilino) phenylacetic acid] in aqueous buffer or methanol solution leads to sequential loss of both chlorine substituents and ring closure to carbazole‐1‐acetic acid as the major product. Minor products result from substitution by the solvent. The photosensitizing properties of diclofenac and its major photoproduct were tested with singlet oxygen substrates and in the free radical polymerization of acrylamide. Although the major carbazole product is a weakly phototoxic agent, able to generate singlet oxygen more efficiently than diclofenac, the free radical photodechlorination process is postulated as the probable initiation step of in vivo photosensitivity responses.
POTENTIAL PHOTOSENSITIZERS FOR PHOTODYNAMIC THERAPY—II. PHOTOPHYSICAL PROPERTIES OF [26] PORPHYRIN
Authors: Schermann G. , Schmidt R. , Völcker A. , Brauer H.‐D. , Mertes H. , Franck B.
Published: January 2008

Abstract— –Photophysical properties of [26] porphyrin (26 P) were investigated in chloroform. The quantum yields of fluorescence, of S1→ T1 intersystem crossing and singlet oxygen formation were measured. The purity, stability, the strong absorption in the red (δmax= 783 nm; εmax= 28 000 M1 cm‐1) and the ability of singlet oxygen formation recommend 26 P as potential photosensitizer for tumor therapy.
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

Primary 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

Human 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

Incubation 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

Fluoride 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

The 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

Photoinhibition 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.
MEMBRANE LIPID INFLUENCES ON THE ENERGETICS OF THE METARHODOPSIN I and METARHODOPSIN II CONFORMATIONAL STATES OF RHODOPSIN PROBED BY FLASH PHOTOLYSIS*
Authors: Gibson Nicholas J. , Brown Michael F.
Published: January 2008

Abstract– We have investigated the relationship between rhodopsin photochemical function and the retinal rod outer segment (ROS) disk membrane lipid composition using flash photolysis techniques. Bovine rhodopsin was combined with various phospholipids to form recombinant membrane vesicles, in which the lipid acyl chain composition was maintained at that of egg phosphatidylcholine (PC), while the nature of the headgroups was varied. The ratio of metarhodopsin II (MII)/metarhodopsin I (MI) in these recombinants produced by an actinic flash was investigated as a function of pH, and compared with the photochemical activity observed for rhodopsin in native ROS membranes and dimyristoylphosphatidylcholine recombinants. In recombinants made with lipids derived from egg PC, as well as in native ROS membranes, MI and Mil were found to be present in a pH‐dependent, acid‐base equilibrium on the millisecond timescale. The recombinants made with phospholipids containing unsaturated acyl chains were capable of full native‐like Mil production, but each demonstrated a titration curve with a different pK. In addition, some of the recombinants exhibited apparent deviations from the Henderson‐Hasselbalch curve shape. The presence of either phosphatidylethanola‐mine (PE) or phosphatidylserine (PS) headgroups appeared to increase the amount of Mil produced. This may result from alteration of the curvature free energy, in the case of PE, and from the influence of the membrane surface potential in the case of PS. An investigation of the effects of temperature on the MI‐MII transition in native ROS membranes and the recombinants was also carried out. The results suggest that the thermodynamic parameters characterizing the MI and Mil conformational states of rhodopsin are influenced by the membrane bilayer environment, indicating a possible role of lipids in the visual process.
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.
THE MAXIMUM EFFICIENCY OF PHOTOSYNTHESIS *
Authors: BOLTON JAMES R. , HALL DAVID O.
Published: January 2008

Abstract—

Within the ideal assumptions: (1) two Photosystems for photosynthetic fixation of CO2, (2) all solar photons with Λ≥ 700 nm are absorbed, (3) the photon requirement is 8 for each CO2 molecule fixed and O2 molecule evolved and (4) the principal stable product of photosynthesis is d‐glucose, the theoretical maximum efficiency of conversion of light to stored chemical energy in green‐plant type (oxygen‐evolving) photosynthesis in bright sunlight is calculated to be 13.0%. Thermodynamic arguments are presented which indicate that a photosynthetic system with one Photosystem would be highly unlikely to be able to drive each electron from water to evolve O2 and reduce CO2. The practical maximum efficiency of photosynthesis under optimum conditions is estimated to be 8–9%.
PHOTOCHEMISTRY OF MEROCYANINE 540
Authors: DAVILA JORGE , HARRIMAN ANTHONY , GULLIYA KIRPAL S.
Published: January 2008

Abstract— The photophysical properties of merocyanine 540 have been determined in methanol solution over a modest temperature range. Triplet state population is inefficient (the limiting triplet quantum yield being 0.25) due to rapid isomerization of the central double bond from the first excited singlet state. Activation energies have been measured for isomerization from the excited singlet state (20 kJ mol‐1) and for conversion of the resultant cis‐isomer back to the original trans‐form (63 kJ mol‐1), both processes involving formation of a twisted species. The dye is easily oxidized to give an unstable adduct which decomposes on the sub‐ms timescale. Reversible redox chemistry occurs upon excitation in the presence of electron acceptors. These various observations are discussed in terms of the known chemotherapeutic activity of MC540 and it is concluded that the most probable mechanisms for cytotoxicity involve either local thermal disruption of cell membranes or in siru photogeneration of toxins derived from breakdown of the dye.