bluuebunny/crossref_metadata_2025_split huggingface dataset:
INVOLVEMENT OF DRUG‐DERIVED PEROXIDES IN THE PHOTOTOXICITY OF NAPROXEN and TIAPROFENIC ACID
Authors: Castell Jose V. , Gomez‐Lechon Maria J. , Grassa Carmina , Martinez Luis A. , Miranda Miguel A. , Tarrega Pilar 
Published: January 2008

AbstractPhotodegradation of naproxen and tiaprofenic acid in aqueous buffered solutions leads to decarboxylated products with ethyl, 1‐hydroxyethyl and/or acetyl side chains. The photomixtures obtained in the presence of oxygen were clearly more toxic to cultured hepatocytes than those obtained under anaerobic conditions. This effect was more noticeable in the case of naproxen. Based on the composition of the oxygenated photomixtures and the relative toxicity of the different photoproducts, it is possible to account for most of the observed toxicity in the case of tiaprofenic acid but not in the case of naproxen. This is explained as a result of the presence of drug‐derived peroxidic species in the photomixtures and their contribution to the observed toxicity. Peroxides were determined by the peroxidase‐catalyzed oxidation of dichlorodihydrofluorescein to its fluorescent analog. The amount of peroxides present in naproxen photomixtures was much higher than in the case of tiaprofenic acid. A dose‐dependent depletion of intracellular glutathione was observed when hepatocytes were incubated with peroxide‐containing naproxen photomixtures. This effect was prevented by the addition of catalase or jV‐acetylcysteine to the culture medium.
SEASONAL TRENDS IN ERYTHEMAL and CARCINOGENIC ULTRAVIOLET RADIATION AT MID‐SOUTHERN LATITUDES1989–1991
Authors: Smith Gerald J. , White Malcolm G. , Ryan Ken G. 
Published: January 2008

AbstractA network of solar carcinogenic/erythemal ultraviolet radiometers has been established in New Zealand. Daily integrated irradiances of this biologically harmful ultraviolet radiation for 1989, 1990 and 1991 are reported from radiometers located at Wellington (41°S) and Christchurch (43.5°S) and for 1990 and 1991 from the Auckland (37°S) radiometer. Although the monitoring program has not been running sufficiently long to discern any long‐term changes in levels of solar ultraviolet radiation, shorter term trends are apparent, which are attributed to a seasonal cycle in levels of ozone at midlatitudes and changes in atmospheric aerosols.
ABSORPTION SPECTRA OF LEAVES CORRECTED FOR SCATTERING and DISTRIBUTIONAL ERROR: A RADIATIVE TRANSFER and ABSORPTION STATISTICS TREATMENT
Authors: Fukshansky L. , Remisowsky A. Martinez V. , McClendon J. , Ritterbusch A. , Richter T. , Mohr H. 
Published: January 2008

AbstractA comprehensive treatment of light propagation through intact leaves based on the theories of radiative transfer and absorption statistics was used to calculate the theoretical absorption spectra of the chlorophyll‐containing particles under conditions of multiple scattering and pigment spatial distribution equivalent to those in a leaf. These spectra were compared with the experimental in vivo spectra of leaves and in vitro spectra of chlorophyll‐protein complexes extracted form these leaves. We conclude that the main discrepancies between the in vivo and in vitro spectra are apparently due to the optical artifacts specific for light propagation in leaves‐multiple scattering and distributional error. Alterations of the pigment properties upon extraction significantly contribute to these discrepancies. The method has an estimated accuracy of about 10% and can be applied to derive the intrinsic optical properties of the photosynthetic mechanism in a leaf, as well as for the systematic study of their changes in the course of light adaptation.
PHOTOSENSITIZATION OF MITOCHONDRIA BY LIPOSOME‐BOUND PORPHYRINS
Authors: Ricchelli Fernanda , Gobbo Silvano , Jori Giulio , Moreno Giuliana , Vinzens Françoise , Salet Christian 
Published: January 2008

AbstractWe have compared the photodynamic activities of hematoporphyrin (HP) and protoporphyrin (PP) on isolated rat liver mitochondria by measuring the decline of the respiratory control ratio (RCR) after irradiation at 365 nm. Before addition to the respiratory mcdium, the dyes were dissolved in phosphate‐buffered saline (PBS) or incorporated into unilamellar liposomes of dipalmitoyl‐phosphatidylcholine (DPPC), sometimes enriched with cholesterol (Chol) or cardiolipin (Card), which are naturally present in mitochondrial membranes. Chol and especially Card strongly increase the porphyrin uptake by mitochondria. In all experimental conditions, PP is taken up by mitochondria to a higher extent than HP. Nevertheless, under conditions giving the same amount of mitochondriabound dye, HP is a morc efficient photosensitizer than PP. As the efficiency of singlet oxygen production has been shown to be equivalent for the two porphyrins in monomeric state, the resulting photobiological effects are explained in terms of different localization of HP and PP in the mitochondrial membrancs. In particular, HP preferentially localizes in the protein‐rich polar domains of the inner mitochondrial membrane, whereas PP dissolvcs in the lipid regions of the mcmbrancs.
LINEAR DICHROISM STUDY OF METALLOPORPHYRIN TRANSITION MOMENTS IN VIEW OF RADIATIONLESS INTERACTIONS WITH TRYPTOPHAN IN HEMOPROTEINS
Authors: Gryczynski Zygmunt , Bucci Enrico , Kuba Joazee: 
Published: January 2008

AbstractWe measured the linear dichroism of several metalloporphyrins embedded in stretched polyvinyl alcohol (PVA) films to estimate the orientation of the absorption transition moments, which in hemoproteins are relevant to the radiationless energy transfer between tryptophan and heme. The metalloporphyrins were derivatives of protoporphyrin IX (PPIX), namely Fe3+‐PPIX (ferric‐heme) and Fe2+CO‐PPIX (CO‐heme), Mg‐PPIX (Mg‐heme) and Zn‐PPIX (Zn‐heme). Measurements were conducted between 300 and 700 nm. In all cases the linear dichroism was wavelength dependent, indicating the presence of several transition moments with different orientations. We focused our attention on the near‐UV (300–380 nm) and Soret (380450 nm) absorption bands. Deconvolution in terms of Gaussian components gave three components between 380 and 450 nm and only one in the 300–380 nm region. Deconvolution of the near‐UV and Soret spectra of oxy‐, deoxy‐ and carbonmonoxyhemoglobin gave very similar results, suggesting a very similar orientation of the various transition moments in the free and protein‐embedded hemes. It should be stressed that the single 300–380 nm band is the only one responsible for the overlap integral that regulates the energy transfer from tryptophan to heme in hemoproteins (Gryczynski et al., Biophys. J. 63, 648–653, 1992). The dichroism of this single band indicated that its transition moment is oriented at about 60 from the α‐γ meso‐axis of the heme moiety. We conclude that the heme should be considered a linear oscillator when it acts as acceptor of energy transfer from tryptophans.
THE EFFECT OF CHANGES OR DIFFERENCES IN ROBERTSON‐BERGER RADIOMETER RESPONSIVITY ON SOLAR ULTRAVIOLET‐B MEASUREMENT
Authors: Smith Gerald J. , Ryan Ken G. 
Published: January 2008

AbstractTwo long‐term solar UV measurement campaigns, in the USA and in Austria, using Robertson‐Berger radiometers found opposite trends for measured levels of ultraviolet‐B radiation reaching the earth's surface. This could be a consequence of the method used to calibrate the radiometers. Changes or differences in responsivity were compensated for by adjusting the sensitivity of the field radiometers to match the output of a reference radiometer.This radiometer intercomparison procedure has been evaluated in terms of the normalization wavelength to which the Robertson‐Berger effective irradiance refers. There are small differences in spectral responsivities apparent in the radiometers used in the USA campaign, which require the field radiometers to be normalized at different wavelengths to match the response of the reference radiometer. This normalization wavelength is shown to depend on the time‐averaged spectrum experienced by the instruments during the intercomparison. As a result there are substantial interradiometer variations in their calculated response to solar radiation when the measured spectral distribution is different from the spectrum used for the radiometer intercomparison procedure.
FLUORESCENCE LINE‐NARROWING STUDIES OF ANTIBODY‐BENZO[a]PYRENE TETROL COMPLEXES
Authors: Singh Kuldip , Skipper Paul L. , Tannenbaum Steven R. , Dasari Ramachandra R. 
Published: January 2008

AbstractBenzo[a]pyrene tetrol (BPT) was used as a fluorescent probe to investigate the nature of antigen binding by two different monoclonal antibodies (MAb) that recognize a variety of derivatives of anti‐7,8‐dihydroxy‐9,10‐epoxy‐7,8,9,10‐tetrahydrobenzo[a]pyrenes (BPDE). Fluorescence line‐narrowed spectra of the physical complexes of BPT formed with antibodies 8E11 and 3C3 were recorded at 4 K by employing vibronic excitation into the S, electronic state. The frequencies of the vibrational modes of the S1 state were only marginally affected, though changes in relative intensities of some bands were observed. Fluorescence spectra recorded at 77 K by excitation into the S2 state showed that the (0,0) fluorescence emission of BPT was shifted to red on complex formation. Intensity ratios of the (0,0) band and the main vibrational band at 1300 cm‐1 were used to assess the degree of interior binding of the chromophore. Quenching studies with acrylamide were employed to designate the complexes as type I, solvent inaccessible, or type II, solvent accessible. These studies also indicated that antibody 3C3 complexes tend to be more heterogeneous compared to the 8E11 complex. Deuterated BPT‐d‐12 also formed complexes with both antibodies, however, with different quenching behavior.
RELAXATION OF VASCULAR SMOOTH MUSCLE INDUCED BY LOW‐POWER LASER RADIATION
Authors: Chaudhry Hina , Lynch Mary , Schomacker Kevin , Birngruber Reginald , Gregory Kenton , Kochevar Irene 
Published: January 2008

AbstractThe relaxation of rabbit aorta rings induced by low‐power laser radiation was investigated in vitro to determine the location of the chromophore(s) responsible for this response and evaluate possible mechanisms. An action spectrum for relaxation was measured on rabbit thoracic aorta rings precontracted with norepinephrine. The decrease in isometric tension was measured during exposure to laser light (351–625 nm) delivered via a fiber optic to a small spot on the adventitial surface. The shortest UV wavelength (351 nm) was 35‐fold more effective than 390 nm and 1700‐fold more effective than 460 nm. Ultraviolet wavelengths also produced greater maximum relaxation (0.40–0.45) than visible wavelengths (0.20–0.25), suggesting that photovasorelaxation involves more than one chromophore.The adventitial layer was not necessary for photovasorelaxation, indicating that the light is absorbed by a chromophore in the medial layer. The same degree of relaxation was obtained on rings without adventitia when either one‐half of the ring, or a small spot was irradiated indicating that communication between smooth muscle cells spreads a signal from the area illuminated to the entire ring.The mechanism for photovasorelaxation was investigated using potential inhibitors. N‐monomethyl‐l‐arginine and N‐amino‐L‐arginine, inhibitors of nitric oxide synthase, did not alter photovasorelaxation nor did indomethacin, an inhibitor of cyclooxygenase, and zinc protoporphyrin, an inhibitor of heme oxygenase.
AGGREGATION OF 2,3‐DIHYDROXY‐ETIOCHLORIN I. AN AMPHIPHILIC MODEL COMPOUND FOR PHOTODYNAMIC THERAPY AND GREEN HEME d
Authors: Senge Mathias O. , Hope Hakon , Iakovides Panos , Smith Kevin M. 
Published: January 2008

AbstractThe crystal structure of 2,3‐dihydroxy‐etiochlorin I has been determined to obtain information on its aggregation behavior. Cis‐dihydroxychlorins serve as model compounds for green heme d and show promising photonecrotic activity in photodynamic therapy. The compound shows strong aggregation in the solid state facilitated by intramolecular hydrogen bonding between one hydroxy group and pyrrole nitrogens of neighboring molecules. This novel type of aggregation leads to chain‐type aggregates in the crystal. The title compound 4 crystallized in the monoclinic space group Ia (Z = 4) with unit cell dimensions a = 9.902(4) Å, b = 26.430(9) Å, c = 10.823(5), β= 104.47(3) Å, V = 2743(2) Å3. The structure was refined to an R‐value of 0.097 on the basis of 1150 reflections with F > 4.0σ (F) (130 K).
SYNTHESIS OF AMPHIPATHIC PORPHYRINS AND THEIR PHOTOINDUCED ELECTRON TRANSFER REACTIONS AT THE LIPID BILAYER‐WATER INTERFACE
Authors: Hwang Kuo Chu , Mauzerall David , Wagner Richard W. , Lindsey Jonathan S. 
Published: January 2008

AbstractA one flask synthesis of cis‐substituted amphipathic porphyrins is reported. These porphyrins were used to study electrostatic effects on photoinduced electron transfer across the lipid bilayer‐water interface. A neutral porphyrin undergoes only dynamic interfacial electron transfer reactions irrespective of charge of the acceptor, although ionic strength effects indicate a negative charge on the porphyrin donor species. A dianionic porphyrin forms an interfacial static complex with a dicationic electron acceptor, methyl viologen, at low ionic strength. The electron transfer rate within the complex is slow, 105∼ 106 s‐1, which is attributed to a near orthogonal orientation between the donor and the acceptor ∼ orbitals.
SPECTROSCOPIC STUDIES OF COUMARIN IN MICELLES
Authors: Marques A. D. S. , Marques G. S. S. 
Published: January 2008

AbstractSteady‐state and time‐resolved emission spectroscopic techniques have been employed to characterize the coumarin species and identify which species is solubilized in the hydrocarbon core micelles of triton X‐100 (neutral), hexadecyltrimethyl ammonium bromide (cationic) and dodecyl lithium sulfate (anionic) solutions under physiological conditions at 77 K. The emission and absorption spectra for the following species of coumarin—monomer, hydrogenbonded complex, molecular aggregation and strong hydrophobic aggregates—were recorded in methylcyclohexane (MCH), ethanol, buffers and aqueous solutions. The fluorescence and phosphorescence emissions of monomer in MCH at 77 K are assigned as resulting from 1(*)1 and 3(*)1 states, respectively, originated from the ethylenic bond and carbonyl of the pyrone ring. Molecular orbital calculations using the Hydrogenic Atoms in Molecule, version 3, method were carried out to help interpretation of the spectroscopic results. The photophysical properties from each species are used to probe which species penetrates in the hydrophobic region of micelles. It was found that a fifth species of coumarin assigned as the “action species” is solubilized into the interior of micelles. These observations could lend some insight into the mechanism of transporting coumarins across the membrane.
PHOTODYNAMIC TREATMENT OF YEAST WITH CHLOROALUMINUM‐PHTHALOCYANINE: ROLE OF THE MONOMERIC FORM OF THE DYE
Authors: Paardekooper M. , Gompel A. E. Van , Bont H. J. G. M. De , Nagelkerke J. F. , Steveninck J. Van , Broek P. J. A. Van den 
Published: January 2008

AbstractThe effect of photodynamic treatment on the yeast Kluyveromyces marxianus with aluminum‐phthalocyanines has been studied. It was found that the nonsulfonated sensitizer caused light‐dependent loss of colony‐forming capacity, whereas the mono‐ and tetrasulfonated forms did not induce loss of clonogenicity. The effect of the nonsulfonated sensitizer increased with longer preincubation periods of cells with the dye. Formation of cellattached, mostly intracellularly localized monomelic sensitizer also increased with time. The amount of cell‐bound multimeric nonsulfonated phthalocyanine did not vary with time. Experiments designed to specifically increase the amount of cell‐attached monomers led also to an increased photoinactivation of the cells. It is therefore concluded that the photodynamic effect of the nonsulfonated Al‐phthalocyanine is mediated by the monomeric form of the dye.
LIGHT REACTIONS OF THE CILIATE Stentor coeruleus‐A THREE‐DIMENSIONAL ANALYSIS
Authors: Kuhnel‐Kratz Christian , Hader Donat‐P. 
Published: January 2008

AbstractA computer‐controlled three‐dimensional tracking and motion analysis system was developed to study the responses of Stentor coeruleus to short light pulses and to evaluate its distribution patterns. In addition to photokinesis and phototaxis, the step‐up photophobic response was analyzed, which includes a gravity‐controlled component at higher fluence rates and a light direction‐dependent component at lower fluence rates.
PHOTOCYTOTOXICITY OF CURCUMIN
Authors: Dahll Thomas A. , Bilski Piotr , Reszka Krzysztof J. , Chignell Colin F. 
Published: January 2008

AbstractCurcumin, bis(4‐hydroxy‐3‐methoxyphenyl)‐l,6‐diene‐3,5‐dione, is a yellow‐orange dye derived from the rhizome of the plant Curcuma longa. Curcumin has demonstrated phototoxicity to several species of bacteria under aerobic conditions (Dahl, T. A., et al., 1989, Arch. Microbiol. 151 183), denoting photodynamic inactivation. We have now found that curcumin is also phototoxic to mammalian cells, using a rat basophilic leukemia cell model, and that this phototoxicity again requires the presence of oxygen. The spectral and photochemical properties of curcumin vary with environment, resulting in the potential for multiple or alternate pathways for the exertion of photodynamic effects. For example, curcumin photogenerates singlet oxygen and reduced forms of molecular oxygen under several conditions relevant to cellular environments. In addition, we detected carbon‐centered radicals, which may lead to oxidation products (see accompanying paper). Such products may be important reactants in curcumin's phototoxicity since singlet oxygen and reduced oxygen species alone could not explain the biological results, such as the relatively long lifetime (t12= 27 s) of the toxicant responsible for decreased cell viability.
EFFECTS OF LIGHT ON T‐CELLS IN HIV‐INFECTED SUBJECTS ARE NOT DEPENDENT ON HISTORY OF SEASONAL AFFECTIVE DISORDER
Authors: Rosenthal Norman E. , Brown Charlotte , Oren Dan A. , Galetto Giorgio , Schwartz Paul J. , Malley James D. 
Published: January 2008

AbstractIn order to evaluate the effect of light on helper‐ and suppressor‐T‐cell counts in HIV‐infected individuals, with and without a history of seasonal affective disorder (SAD), we treated 35 subjects with 45 min of light therapy in the morning, in a crossover design involving two 2 week treatment conditions: visible white light (half‐peak band width, 530‐620 nm; 10 000 lux) and visible red light (half‐peak band width, 615‐685 nm; 175 lux). We found small but significant differences between the two treatment conditions, with higher CD4 and CD8 levels during the white, as compared with the red, condition. There were no differences between baseline and treatment conditions. Both light treatment conditions were associated with significant mood improvements in the SAD, but not the non‐SAD, subjects. There was no evidence that the higher cell counts seen under the bright light conditions were mediated by the effects of light on mood or on plasma Cortisol levels. While the size of the light effect on T‐cells renders questionable the potential therapeutic value of this treatment modality for HIV, the finding is of theoretical interest and is reassuring for those HIV‐infected individuals who require light treatment for other reasons.
PHOTOPHYSICAL AND PHOTOSENSITIZING PROPERTIES OF BENZOPORPHYRIN DERIVATIVE MONOACID RING A (BPD‐MA)*
Authors: Aveline Béatrice , Hasan Tayyaba , Redmond Robert W. 
Published: January 2008

AbstractThe photophysical properties of benzoporphyrin derivative monoacid ring A (BPD‐MA), a second‐generation photosensitizer currently in phase II clinical trials, were investigated in homogeneous solution. Absorption, fluorescence, triplet‐state, singlet oxygen (O2(1Δg)) sensitization studies and photobleaching experiments are reported. The ground state of this chlorin‐type molecule shows a strong absorbance in the red (λ≈ 688 nm, ɛ≈ 33 000 M−1 cm−1 in organic solvents). For the singlet excited state the following data were determined in methanol: energy level, Es= 42.1 kcal mol−1, lifetime, Φf= 5.2 ns and fluorescence quantum yield, Φf= 0.05 in air‐saturated solution. The triplet state of BPD‐MA has a lifetime, τf >. 25 ns, an energy level, ET= 26.9 kcal mol−1 and the molar absorption coefficient is ɛT= 26 650 M−1 cm−1 at 720 nm. A dramatic effect of oxygen on the fluorescence (φf) and intersystem crossing (φT) quantum yields has been observed. The BPD‐MA presents rather high triplet (φT= 0.68 under N2‐saturated conditions) and singlet oxygen (φΔ= 0.78) quantum yields. On the other hand, the presence of oxygen does not significantly modify the photobleaching of this photostable compound, the photodegradation quantum yield (φPb) of which was found to be on the order of 5 × 10−5 in organic solvents.
AGGREGATION OF COLLAGEN EXPOSED TO UVA IN THE PRESENCE OF RIBOFLAVIN: A PLAUSIBLE ROLE OF TYROSINE MODIFICATION
Authors: Kato Yoji , Uchida Koji , Kawakishi Shunro 
Published: January 2008

AbstractRiboflavin‐sensitized photodynamic modification of collagen led to significant formation of cross‐linked molecules. Sodium azide or l,4‐diazabicyclo(2,2,2)octane, which are known to be singlet oxygen quenchers, and catalase could not inhibit the modification. Surprisingly, the collagen modification was accelerated in the presence of superoxide dismutase. The aggregation was accompanied by the loss of tyrosine and histidine residues in the collagen. An inhibitory effect of dissolved oxygen on the modification of collagen was observed. Similarly, the loss of tyrosine residues in the irradiated collagen was inhibited in the presence of dissolved oxygen. Dityrosine formation was also observed with the loss of tyrosine. These results indicate that photodynamic modification of tyrosine probably contributes to the riboflavin‐sensitized cross‐linking of collagen through the formation of dityrosine.
X‐RAY INDUCED VISIBLE LUMINESCENCE OF PORPHYRINS
Authors: Kokotov Sophia , Lewis Aaron , Neumann Ronny , Amrusi Shmuel 
Published: January 2008

AbstractA concept has been presented whereby X‐ray irradiation can be used to induce visible luminescence of chromophores such as porphyrins. The essential aspects of the idea have been demonstrated in a supramolecular assembly consisting of a water‐dispersed polystyrene latex with an embedded scintillating compound, 2,5‐diphenyloxa‐zole, and an externally attached hematoporphyrin. X‐ray excitation of the assembly yields an emission spectra typical for hematoporphyrin with fluorescent yields. of up to 3% with respect to 2,5‐diphenyloxazole emission. Significant quenching in the presence of dioxygen indicates that singlet oxygen is formed at atmospheric conditions.