bluuebunny/crossref_metadata_2025_split huggingface dataset:
In viva PHOTODYNAMIC EFFECTS OF PHTHALOCYANINES IN A SKIN‐FOLD OBSERVATION CHAMBER MODEL: ROLE OF CENTRAL METAL ION AND DEGREE OF SULFONATION
Authors: Leengoed H. L. L. M. Van , Veen N. van der , Versteeg A. A. C. , Ouellet R. , Lier J. E. van , Star W. M. 
Published: January 2008

AbstractSix sulfonated metallophthalocyanines, chelated with either aluminum or zinc and sulfonated to different degrees, were studied in vivo for their photodynamic activity in a rat skin‐fold chamber model. The chamber, located on the back of female WAG/Rij rats, contained a syngeneic mammary carcinoma implanted into a layer of subcutaneous tissue. Twenty‐four hours after intravenous administration of 2.5 μmol/kg of one of the dyes, the chambers received a treatment light dose of 600 J/cm2 with monochromatic light of 675 nm at a power density of 100 mW/ cm2. During light delivery and up to a period of 7 days after treatment, vascular effects of tumor and normal tissue were scored. Tumor cell viability was determined by histology and by reimplantation of the chamber contents into the skin of the same animal, either 2 h after treatment or after the 7 day observation period. Vascular effects of both tumor and subcutaneous tissue were strongest with dyes with the lowest degree of sulfonation and decreased with increasing degree of sulfonation. Tumor regrowth did not occur with aluminum phthalocyanine mono‐ and disulfonate and with zinc phthalocyanine monosulfonate. With the protocol that was used, complete necrosis without recovery was only observed when reimplantation took place at the end of the 7 day follow‐up period. Reimplantation 2 h after treatment always resulted in tumor regrowth. At this interval, the presence of viable tumor cells was confirmed histologically. In general tumor tissue vasculature was more susceptible to photodynamic damage than vasculature of the normal tissue. The effect on the circulation of both tumor and normal tissue increased with decreasing degree of sulfonation. Based on this study, the photodynamic effects using the six sulfonated metallophthalocyanines on the vasculature can be ranked from high to low as: AlPcS2= ZnPcS1 > AIPcS1 > AIPcS4 > ZnPcS2 > ZnPcS4.
SPECTROSCOPIC STUDY OF CHLOROPHYLLaIN ORGANIC SOLVENTS AND POLYMERIZED ANHYDROUS POLYVINYL MATRIX
Authors: Zandvoort Marc A. M. J. van , Wroabel Danuta , Scholten Andries J. , Jager Dries de , Ginkel Glis van , Levine Yehudi K. 
Published: January 2008

AbstractIn this paper we present a spectroscopic study of chlorophyllain solutions and in anhydrous polyvinyl alcohol films. Absorption, excitation and emission spectra, combined with fluorescence lifetime and time‐resolved anisotropy measurements show that chlorophyllain anhydrous polyvinyl alcohol films exists in a purely monomeric state. Furthermore, it appears that the monomeric chlorophyllaexhibits an efficient excitation energy transfer in this polyvinyl alcohol matrix. These results are rationalized in terms of a model in which the chlorophyllamolecules are located within pockets, formed by the polymer chains. It is concluded that the chlorophyll a‐anhydrous polyvinyl alcohol film is a suitable system for studying energy transfer processes, especially because the factors governing energy transfer such as mutual orientation and separation of the molecules can easily be controlled.
HEAT‐ AND LIGHT‐INDUCED CHLOROPHYLL a FLUORESCENCE CHANGES IN POTATO LEAVES CONTAINING HIGH OR LOW LEVELS OF THE CAROTENOID ZEAXANTHIN: INDICATIONS OF A REGULATORY EFFECT OF ZEAXANTHIN ON THYLAKOID MEMBRANE FLUIDITY
Authors: Havaux Michel , Gruszecki Wieslaw I. 
Published: January 2008

AbstractPotato leaf discs were infiltrated in darkness with a buffer of pH 5 containing 100 M ascorbate, resulting in a massive conversion of the carotenoid violaxanthin to zeaxanthin. In vivo measurements of modulated chlorophyll a fluorescence indicated that this treatment (1) caused a marked upward shift of the threshold temperature at which photosystem II denatures and (2) noticeably inhibited the rate of dark reoxidation of the reduced plastoquinone (at low temperature). These changes were not induced in leaves infiltrated with a buffer of pH 5 containing no ascorbate or with 100 mM ascorbate at pH >7.2. The above‐mentioned effects were also observed during heat acclimation (34°C for several days) of potato plants and suggested that zeaxanthin interacts with the lipid phase of the thylakoid membranes. Based on those results and the previous data obtained with model systems, it is suggested that the xanthophyll cycle could be a regulatory mechanism adjusting thylakoid membrane fluidity, the significance of which for the photoprotection of the photosynthetic apparatus is discussed.
NON‐NUCLEAR DAMAGE AND CELL LYSIS ARE INDUCED BY UVA, BUT NOT UVB OR UVC, RADIATION IN THREE STRAINS OF L5178Y CELLS
Authors: Beer Janusz Z. , Olvey Kathleen M. , Miller Sharon A. , Thomas Delma P. , Godar Dianne E. 
Published: January 2008

AbstractThe potential to induce non‐nuclear changes in mammalian cells has been examined for (1) UVA1 radiation (340–400 nm, UVASUN 2000 lamp), (2) UVA + UVB (peak at 313 nm) radiation (FS20 lamp), and (3) UVC (254 nm) radiation (GI5T8 lamp). The effects of irradiation were monitored in vitro using three strains of L5178Y (LY) mouse lymphoma cells that markedly differ in sensitivity to UV radiation. Comparisons were made for the effects of approximately equitoxic fluences that reduced cell survival to 1–15%. Depending on the cell strain, the fluences ranged from 830 to 1600 kJ/m2 for the UVASUN lamp, 75 to 390 J/m2 for the FS20 lamp and 3.8 to 17.2 J/m2 for the G15T8 lamp. At the exposure level used in this study, irradiation with the UVASUN, but not the FS20 or G15T8, lamp induced a variety of non‐nuclear changes including damage to cytoplasmic organelles and increased plasma membrane permeability and cell lysis. Cell lysis and membrane permeabilization were induced by the UVA1 emission of the UVASUN lamp, but not by its visible + IR components (>400 nm). The results show that the plasma membrane and other organelles of LY cells are highly sensitive to UVA1 but not to UVB or UVC radiation. Also UVA1, but not UVB or UVC radiation, causes rapid and extensive lysis of LY cells. In conclusion, non‐nuclear damage contributes substantially to UVA cytotoxicity in all three strains of LY cells.
THE TREATMENT OF MASTOCYTOMA CELLS WITH 8‐METHOXYPSORALEN AND LONG‐WAVELENGTH ULTRAVIOLET RADIATION ENHANCES CELLULAR IMMUNOGENICITY: PRELIMINARY RESULTS
Authors: Gasparro Francis P. , Malane Michelle S. , Maxwell Virginia M. , Tigelaar Robert E. 
Published: January 2008

AbstractEvidence for the increased immunogenicity of mastocytoma cells (P815) treated with 8‐methoxypsoralen (8‐MOP) and long‐wavelength ultraviolet radiation (UVA) is presented. A highly tumorigenic clone (P1) became much less tumorigenic (tum‐) after repetitive phototreatments with 8‐MOP (16 ng/mL) and UVA (1 J/cm2). The yield of tum‐ clones was proportional to the number of phototreatments. In a pilot study in which P1 cells were treated with three successive rounds of 8‐MOP/UVA, one clone out of 73 was tum‐. In a second series of experiments, the P1 cells were treated 10 times and 4 out of 100 clones were much less tumorigenic. When some of the tum‐clones were administered intraperitoneally to DBA/2 mice, significant protection against challenge with the original P1 clone was observed. In addition, the transfer of immune cells from tum‐‐treated mice allowed the transfer of resistance to other tum‐ clones to immunosuppressed mice (650 rad). These results are consistent with earlier literature showing the potent mutagen, N‐methyl‐N′‐nitrosoguanidine, led to mutations in P1 that altered the expression of new surface antigens, which stimulated the murine immune system such that there was also cross recognition of shared antigens on untreated P1 cells used to challenge the immunized mice. The increased immunogenicity that resulted from the less mutagenic 8‐MOP/UVA treatment may arise by a similar mechanism and may be responsible in part for the efficacy of 8‐MOP/UVA photochemotherapy for the treatment of cutaneous T cell lymphoma.
PROTECTION AGAINST ULTRAVIOLET B RADIATION‐INDUCED EFFECTS IN THE SKIN OF SKH‐1 HAIRLESS MICE BY A POLYPHENOLIC FRACTION ISOLATED FROM GREEN TEA
Authors: Agarwal Rajesh , Katiyar Santosh K. , Khan Sikandar G. , Mukhtar Hasan 
Published: January 2008

AbstractIn prior studies we and others have shown that oral feeding of a polyphenolic fraction isolated from green tea (GTP) or water extract of green tea affords protection against ultraviolet B (UVB) radiation‐induced carcinogenesis in SKH‐1 hairless mice (Wang et al., Carcinogenesis 12, 1527–1530, 1991). It is known that exposure of murine skin to UVB radiation results in cutaneous edema, depletion of the antioxidant‐defense system and induction of ornithine decarboxylase (ODC) and cyclooxygenase activities. In this study we assessed the protective effect of GTP on these UVB radiation‐caused changes in murine skin. Oral feeding of 0.2% GTP (wt/vol) as the sole source of drinking water for 30 days to SKH‐1 hairless mice followed by irradiation with UVB (900 mJ/cm2) resulted in significant protection against UVB radiation‐caused cutaneous edema (P <0.0005) and depletion of the antioxidant‐defense system in epidermis (P <0.01–0.02). The oral feeding of GTP also resulted in significant protection against UVB radiation‐caused induction of epidermal ODC (P <0.005–0.01) and cyclooxygenase activities (P <0.0001) in a time‐dependent manner. Our data indicate that the inhibition of UVB radiation‐caused changes in these markers of tumor promotion in murine skin by GTP may be one of the possible mechanisms of chemopreventive effects associated with green tea against UVB‐induced tumorigenesis. The results of this study suggest that green tea, specifically polyphenols present therein, may be useful against inflammatory responses associated with the exposure of skin to solar radiation.
SOLVENT EFFECT ON SPHEROIDENE IN NONPOLAR AND POLAR SOLUTIONS AND THE ENVIRONMENT OF SPHEROIDENE IN THE LIGHT‐HARVESTING COMPLEXES OFRhodobacter sphaeroides2.4.1 AS REVEALED BY THE ENERGY OF THE1Ag−→1Bu+ABSORPTION AND THE FREQUENCIES OF THE VIBRONICALLY COUPLED C=C STRETCHING RAMAN LINES IN THE1Ag−AND1Bu−STATES
Authors: Kuici Michitaka , Nagae Hiroyoshi , Cogdell Richard J. , Shimada Keizo , Koyama Yasushi 
Published: January 2008

Abstract–The1Ag−→1Bu+electronic absorption band and the vibronically coupled, C=C stretching Raman lines in the1Ag−and 21Ag−states were recorded for spheroidene free in nonpolar and polar solvents as well as for spheroidene bound to the LH1 and LH2 complexes ofRhodobacter sphaeroides2.4.1. The1Bu+energy exhibited a linear dependence on R(n) = (n2‐ 1)/(n2+ 2) in both nonpolar and polar solvents; the line for polar solvents had a gentler slope and crossed the line for nonpolar solvents at R(n) = 0.3. The above characteristic of polar solvents was ascribed to the electric field generated by fluctuation of the solvent permanent dipoles; it stabilizes the1Bu+energy and reduces the polarizability of the solvent. The vibronically coupled, C=C stretching frequencies in the1Ag−and 21Ag−states [ν(Ag) and [ν(2Ag)] also showed similar dependence on R(n), which is explained in terms of vibronic coupling among the1Ag−, 21Ag−and 31Ag−states.The environment of spheroidene in the LH2 and LH1 complexes was assessed on the basis of the1Bu+energy and the ν(Ag) and [ν(2Ag) frequencies: Spheroidene in the LH2 complex is located in an environment with high polarizability, while spheroidene in the LH1 complex is located in an environment with lower polarizability.
CONTINUOUS, NONINVASIVE MEASUREMENT OF In Vivo pH IN CONSCIOUS MICE
Authors: Russell David A. , Pottier Roy H. , Valenzeno Dennis P. 
Published: January 2008

AbstractExtracellular pH was measured continuously and noninvasively in hairless mice using a transcutaneous spectronuorometric technique and a fluorescent pH probe, bis‐carboxyethyl carboxyfluorescein (BCECF). The acid form of BCECF was injected intravenously. An optical fiber system excited the florescent probe at 450 and 500 nm alternately, using one branch of a bifurcated, fiber optic bundle. The other branch of the bundle collected the emitted fluorescence which was measured by a photomultiplier tube. The ratio of fluorescence intensities from the two excitation wavelengths was pH dependent. Measurements could be obtained for approximately 60 min following a single injection. Mice exposed to elevated partial pressures of CO2 demonstrated changes in the fluorescence ratio indicative of a dramatic decrease in extracellular pH. If the exposure was brief, the fluorescence signal recovered within 20 min. The fluorescence intensity ratio was calibrated against aqueous BCECF samples in vitro. Fluorescence pH values determined using the in vitro calibration were compared with measurements made on blood samples taken from seven mice. Extracellular pH in hairless mice was found to be approximately 7.5, within the expected physiological range. The variability of the pH signal derived from the fluorescence signal was approximately 0.05 units.
(1‐PYRENYL)METHYL CARBAMATES FOR FLUORESCENT “CAGED” AMINO ACIDS AND PEPTIDES
Authors: Okada Shigeto , Yamashita Senichi , Furuta Toshiaki , Iwamura Michiko 
Published: January 2008

AbstractA highly fluorescent 1‐pyrenylmethyloxycarbonyl amino acid (Pmoc‐amino acid) is obtained in moderate yield by the reaction of (1‐pyrenylmethyl)‐4‐nitrophenylcarbonate with an amino acid in the presence of sodium carbonate. The condensation of Pmoc‐amino acid with an amino acid gives Pmoc‐peptide in the presence of 1‐ethyl‐3‐(3‐dimethylaminepropyl)carbodiimide and 1‐hydroxyben‐zotriazole. The amino acid is recovered from an H2O‐dioxane (2:3) solution of Pmoc‐amino acid by irradiation through a Pyrex filter with a medium pressure Hg lamp or at 340 nm. Although the quantum yield of the photolysis is rather low (ca 0.01), the photolysis proceeds fast and efficiently due to the large absorption coefficient of Pmoc‐amino acid at around 340 nm. Thus, the use of Pmoc‐amino acid as a “caged” amino acid is promising.
CHLOROPHYLLS IN POLYMERS. I. STATE OF CHLOROPHYLL a IN UNSTRETCHED POLYMER SYSTEMS
Authors: Zandvoort M. A. M. J. van , Wróbel D. , Lettinga P. , Ginkel G. van , Levine Y. K. 
Published: January 2008

Abstract—Model systems for the study of energy transfer processes are useful for the elucidation of the various factors governing the mechanism of energy transfer in photosynthetic systems. Here we describe the characterization of two systems, consisting of chlorophyllaincorporated in anhydrous nitrocellulose and polyvinylalcohol films. First, optical spectroscopy and time‐resolved fluorescence techniques are used to characterize the state of the chlorophyll molecules in the films. We find that in nitrocellulose films the state of chlorophylladepends strongly on the ratio of nitrocellulose to dimeth‐ylsulfoxide in the solutions from which the films are cast. The state of chlorophyllain polyvinylalcohol films does not depend on the amount of polymer originally dissolved in dimethylsulfoxide. In these films the pigment is monomeric at low concentrations of chlorophylla,but aggregates are formed at much lower concentrations than in nitrocellulose. The latter fact is explained by the existence of pockets in polyvinylalcohol, leading to high local concentrations.To further test the suitability of the nitrocellulose polymer films as model systems for energy transfer processes, time‐resolved fluorescence anisotropy profiles are measured in dependence of the concentration of pigments in the matrix. Fits of the observed decay profiles to the predicted decay show good correspondence, as long as no traps are present. Furthermore, the fitted decay times yield the correct value of the Forster radius R0as compared to the value obtained spectroscopically. We thus conclude that the chlorophyll a‐nitrocellulose system can be very appropriate for the study of energy transfer processes between photosynthetic pigment, since the pigments are uniformally distributed in the matrix.
Characterization of psal and psaL Mutants of Synechococcus sp. Strain PCC 7002: A New Model for State Transitions in Cyanobacteria
Authors: Schluchter Wendy M. , Shen Gaozhong , Zhao Jindong , Bryant Donald A. 
Published: January 2008

AbstractThe psal and psaL genes were characterized from the cyanobacterium Synechococcus sp. strain PCC 7002. The gene organization was different from that reported for other cyanobacteria with psal occurring upstream and being divergently transcribed from the psaL gene. Mutants lacking Psal or PsaL were generated by interposon mutagenesis and characterized physiologically and biochemically. Mutant strains PR6307 (Δpsal−), PR6308 (psal) and PR6309 (psaL−) had doubling times similar to that of the wild type under both high‐ and low‐intensity white light, but all grew more slowly than the wild type in green light. Only monomeric photosystem I (PS I) complexes could be isolated from each mutant strain when Triton X‐100 was used to solubilize thylakoid membranes; however, approximately 10% of the PS I complexes from the psal mutants, but not the psaL mutant, could be isolated as trimers when n‐do‐decyl β‐D‐maltoside was used. Compositional analyses of the mutant PS I complexes indicate that the presence of PsaL is required for trimer formation or stabilization and that Psal plays a role in stabilizing the binding of both PsaL and PsaM to the PS I complex. Strain PR6309 (psaL−) was capable of performing a state 2 to state 1 transition approximately three times more rapidly than the wild type. Because the monomeric PS I complexes of this mutant should be capable of diffusing more rapidly than trimeric complexes, these data suggest that PS I complexes rather than phycobilisomes might move during state transitions. A “mobile‐PS I” model for state transitions that incorporates these ideas is discussed.
Study of Photoinduced Energy and Electron Transfer in α‐Terthienyl‐Bovine Serum Albumin Conjugates: A Laser Flash Photolysis Study*
Authors: Boch R. , Mohtat N. , Lear Y. , Arnason J. T. , Durst T. , Scaiano J. C. 
Published: January 2008

AbstractThe photochemistry of α‐terthienyl (α‐T) has been examined in bovine serum albumin (BSA). Freely associated and covalently conjugated α‐T chromophores show similar behavior toward nonpolar quenchers such as oxygen and benzoquinone but show significant differences in the case of quenching by methyl viologen, a water‐soluble cationic electron acceptor; in this case, triplet quenching reveals two distinct α‐T populations, attributed to chromophores in sites showing very different accessibility from the aqueous phase. Rate constants for triplet quenching in BSA are generally slower than those observed in homogeneous solution for free α‐T. For example, in the case of oxygen, the rate constant is about one order of magnitude smaller when α‐T is associated or conjugated with the protein compared with α‐T in solution. While triplet yields for α‐T are essentially the same in solution and in the protein environment, the yield of detectable singlet oxygen is substantially reduced in the protein. This is attributed to a geminate reaction within the protein involving singlet oxygen trapping in the vicinity of the generation site.
Photoinactivation of Superoxide Synthases of the Plasma Membrane from Rose (Rosa damascena Mill.) Cells
Authors: Murphy Terence M. , Vu Han 
Published: January 2008

AbstractThe UVC‐induced synthesis of hydrogen peroxide (H2O2) by cultured rose (Rosa damascena Mill, cv Gloire de Guilan) cells is inhibited by broad‐band radiation containing UVA, UVB and blue wavelengths. In order to understand the basis for this inhibition, we tested the effects of broad‐band radiation and of monochromatic radiation on NADH‐ and NADPH‐dependent O2‐ synthases of purified plasma membranes. Both activities were inhibited by wavelengths from 254 to 435 nm, with the NADPH‐dependent enzyme being more sensitive than the NADH‐dependent enzyme. Incubation in the presence of flavin adenine dinucleotide had a small but significant ameliorative effect on the inhibition of the O2‐ synthase activities of plasma membranes by 300 nm radiation. The data support the hypothesis that the NADH‐ and NADPH‐dependent activities are catalyzed by different enzymes. The NADPH‐dependent activity, but not the NADH‐dependent activity, was sufficiently sensitive to account for the inhibition of H2O2 synthesis by the broad‐band radiation.
Mycosporine‐like Amino Acids Provide Protection Against Ultraviolet Radiation in Eggs of the Green Sea Urchin Strongylocentrotus droebachiensis
Authors: Adams Nikki L. , Shick J. Malcolm 
Published: January 2008

AbstractA photoprotective role of ultraviolet radiation‐absorbing mycosporine‐like amino acids (MAAs) in eggs of the green sea urchin Strongylocentrotus droebachiensis was demonstrated by comparing UV‐induced delays in the first division of embryos having either high or low concentrations of MAAs. Embryos from adult urchins fed Laminaria saccharina (no MAAs) had low concentrations of MAAs and experienced a significantly longer UV‐induced delay in cleavage (25.1%) than MAA‐rich embryos from adults fed Mastocarpus stellatus (12.8% delay) or a combination diet of both macroalgae (12.3% delay). Collectively, these embryos displayed a significant inverse logarithmic relationship between MAA concentration and percentage cleavage delay, so that the greater the MAA concentration in the eggs, the less they were affected by UV radiation. This is the first study to examine such MAA manipulation of cellular MAA concentrations with no prior UV exposure of the experimental subjects. Concentrations of MAAs were also measured in unfertilized eggs, blastulae, gastrulae and early pluteus larvae, providing the first documentation of changes in MAAs during embryological and larval development. The concentration of shinorine (the principal MAA in the eggs) did not change during short‐term UV exposure in vivo or long‐term exposure in vitro; such photostability is a useful attribute of a natural sunscreen.
Effect of Glucose on Photodynamic Action of Methylene Blue in Escherichia coli Cells
Authors: Capella Márcia , Coelho Ana Maria , Menezes Salatiel 
Published: January 2008

AbstractThe results of this work show that the resistance of Escherichia coli cells to the photodynamic action of methylene blue is increased by the addition of glucose to the media in which they are grown. It is postulated that the increased resistance may be due to lowered retention of the dye by cells grown in the presence of glucose, leading to the diminution in DNA damage revealed in the alkaline sucrose gradients. The role of cyclic adenosine‐monophosphate in the protective action of glucose is discussed.
UV Radiation and Mouse Models of Herpes Simplex Virus Infection
Authors: Norval Mary , El‐Ghorr Ali A. 
Published: January 2008

AbstractOrolabial human infections with herpes simplex virus type 1 (HSV‐1) are very common; following the primary epidermal infection, the virus is retained in a latent form in the trigeminal ganglia from where it can reactivate and cause a recrudescent lesion. Recrudescences are triggered by various stimuli including exposure to sunlight. In this review three categories of mouse models are used to examine the effects of UV irradiation on HSV infections: these are UV exposure prior to primary infection, UV exposure as a triggering event for recrudescence and UV exposure prior to challenge with virus in mice already immunized to HSV. In each of these models immunosuppression occurs, which is manifest, in some instances, in increased morbidity or an increased rate of recrudescence. Where known, the immunological mechanisms involved in the models are summarized and their relevance to human infections considered.