bluuebunny/crossref_metadata_2025_split huggingface dataset:
Photodynamic Studies and Photoinactivation of Escherichia coli Using meso‐Substituted Cationic Porphyrin Derivatives with Asymmetric Charge Distribution¶
Authors: Lazzeri Débora , Rovera Marisa , Pascual Liliana , Durantini Edgardo N. 
Published: July 2010

ABSTRACTThe photodynamic activities of novel asymmetrically meso substituted cationic porphyrins, 5,10‐di(4‐methylphenyl)‐ 15,20‐di(4‐trimethylammoniumphenyl)porphyrin iodide 1 and 5‐(4‐trifluorophenyl)‐10,15,20‐tris(4‐trimethylammoniumphenyl)porphyrin iodide 2 and its metal complex with Pd(II) 3, have been investigated in both homogeneous medium bearing photooxidizable substrates and in vitro on a typical gram‐negative bacterium Escherichia coli. The amphiphilic character of porphyrin 2 was increased by the presence of a high‐lipophilic trifluoromethyl group and its photophysical properties changed by forming a complex with Pd(II). Absorption and fluorescence spectroscopic studies were compared in different media. Fluorescence quantum yields (øF) of 0.16 for 1 in tetrahydrofuran and 0.08 for 2 in N, N‐dimethylformamide (DMF) were calculated, whereas no significant emission was detected for Pd(II) porphyrin 3. The singlet molecular oxygen, O2(1Δ(g), production was evaluated using 9,10‐dimethylanthracene in DMF yielding relative values of 1, 0.55 and 0.47 for porphyrins 3, 2 and 1, respectively. A faster decomposition of L‐tryptophan was obtained using Pd(II) porphyrin 3 as sensitizer with respect to the free‐base porphyrins 1 and 2. In biological medium, the behavior of cationic porphyrins 1‐3 were compared with that of 5‐(4‐carboxyphenyl)‐10,15,20‐tris(4‐methylphenyl)porphyrin 4, which was used as a noncationic sensitizer. These porphyrins are rapidly bound to E. coli cells in 5 min and the amount of cell‐bound sensitizer is not appreciably changed incubating the cultures for longer times. The recovered porphyrin 2 after one washing step reaches a value of ∼2.9 nmol/106 cells and this amount remains high even after three washes, indicating that this sensitizer is tightly bound to cells. Photosensitized inactivation of E. coli was analyzed using cells without and with one washing step. In both cases, a higher photoinactivation of cells was found for tricationic porphyrin 2 and 3, causing a ‐5.5 log (99.999%) decrease of cell survival, when treated with 10 μM of sensitizer. Under these conditions, a lower effect was found for porphyrin 1 (‐4 log) whereas sensitizer 4 did not produce appreciable photodamage. The results were also confirmed by growth delay experiments. These studies show that the amphiphilic tricationic porphyrin 2 and 3 bearing a trifluoromethyl group can be a promising model for phototherapeutic agents with potential applications in inactivation of bacteria by photodynamic therapy.
Measurements of the Solar UVR Protection Provided by Shade Structures in New Zealand Primary Schools¶
Authors: Gies Peter , Mackay Christina 
Published: July 2010

ABSTRACTTo reduce ultraviolet radiation (UVR) exposure during childhood, shade structures are being erected in primary schools to provide areas where children can more safely undertake outdoor activities. This study to evaluate the effectiveness of existing and purpose built shade structures in providing solar UVR protection was carried out on 29 such structures in 10 schools in New Zealand. Measurements of the direct and scattered solar UVR doses within the central region of the shade structures were made during the school lunch break period using UVR‐sensitive polysulfone film badges. These measurements indicate that many of the structures had UVR protection factors (PF) of 4‐8, which was sufficient to provide protection during the school lunch hour. However, of the 29 structures examined, only six would meet the suggested requirements of UVR PF greater than 15 required to provide all‐day protection.
A Novel Mitochondrial Signaling Pathway Activated by Visible‐to‐near Infrared Radiation¶
Authors: Karu Tiina I. , Pyatibrat Ludmila V. , Afanasyeva Natalia I. 
Published: July 2010

ABSTRACTThe number of cells attached to glass substratum increases if HeLa cell suspension is irradiated with monochromatic visible‐to‐near infrared radiation before plating (the action spectrum with maxima at 619, 657, 675, 700, 740, 760, 800, 820, 840 and 860 nm). Treating of cell suspension with sodium azide (2 × 10−5M), sodium nitroprusside (5 × 10−5M), ouabain (1 × 10−6M) or amiloride (1.7 × 10−5M) before irradiation significantly modifies the spectrum of cell attachment enhancement. A light‐induced mitochondrial signaling pathway can be regulated by small ligands directly binding to the catalytic center of cytochromecoxidase (N3, NO) as well as by chemicals specifically binding to plasma membrane enzymes (ouabain, amiloride). The comparative analysis of action spectra allows the conclusions that first, CuAand CuBchromophores of cytochromecoxidase could be involved as photoacceptors and second, various signaling pathways (reaction channels) between cytochromecoxidase and cell attachment regulation are at work.
The Topical Isoflavonoid NV‐07α Reduces Solar‐simulated UV‐induced Suppression of Mantoux Reactions in Humans¶
Authors: Friedmann Adam C. , Halliday Gary M. , Barnetson Ross StC. , Reeve Vivienne E. , Walker Catherine , Patterson Clare R. S. , Damian Diona L. 
Published: July 2010

AbstractUV radiation suppresses delayed‐type hypersensitivity responses to intradermally injected tuberculin purified protein derivative in Mantoux‐positive individuals. The effect of the topically administered isoflavonoid NV‐07α, a synthetic derivative of the isoflavonoid equol, on UV‐induced suppression of Mantoux reactions was assessed in 18 healthy Mantoux‐positive volunteers. A single, fixed dose of solar‐simulated UV radiation was delivered to the volunteers'lower backs. Different concentrations of NV‐07α or its vehicle were applied to different sites within the irradiated field immediately after UV exposure and again 24 h later. Forty‐eight hours after irradiation, Mantoux testing was performed at both the irradiated sites and adjacent, unirradiated sites. The intensity of Mantoux reactions was measured 72 h later with a reflectance erythema meter and by measuring the diameter of each reaction. Although lower concentrations of NV‐07α (0.5 and 2 mM) did not prevent UV immunosuppression, 4 mM NV‐07α partially but significantly attenuated UV‐induced suppression of Mantoux‐induced erythema. Minimal erythema doses were also determined for sites treated with NV‐07α or its vehicle immediately after UV exposure. NV‐07α had no significant effects on UV erythema. We conclude that 4 mM NV‐07α prevented the suppressive effects of UV radiation on Mantoux responses in humans but did not affect UV‐induced erythema at the concentrations used.
Solar Ultraviolet‐B Radiation in Urban Environments: The Case of Baltimore, Maryland¶†
Authors: Heisler Gordon M. , Grant Richard H. , Gao Wei , Slusser James R. 
Published: July 2010

AbstractUltraviolet‐B radiation (UV‐B, 280–320 nm) has important effects in urban areas, including those on human health. Broadband UV‐B radiation is monitored in Baltimore, MD, as part of the Baltimore Ecosystem Study, a long‐term ecological research program. We compare broadband UV‐B irradiance in Baltimore with UV‐B at two nearby locations: a more rural station 64 km southeast and a suburban station 42 km southwest. The monitoring station in Baltimore is on the roof of a 33‐m‐tall building; there are no significant obstructions to sky view. The U.S. Department of Agriculture UV‐B Monitoring and Research Program provided all sensors, which were calibrated at the National Oceanic and Atmospheric Administration Central UV Calibration Facility. UV‐B irradiances at the three sites generally were similar. Over all conditions, Baltimore and the suburban site measured 3.4% less irradiance than the rural site. This difference is within the anticipated ±3% calibration uncertainty of the pyranometers. On 59 days with cloud‐free conditions at all three sites, average differences in measured UV‐B among the three sites were even smaller; Baltimore measured 1.2% less irradiance than the rural site. High aerosol optical thickness strongly reduced daily UV‐B dose, whereas [SO2] had no influence. Surface O3 increased with increasing UV‐B dose when [NO2] exceeded 10 ppb.
The Triplet‐state Lifetime of Indole Derivatives in Aqueous Solution¶
Authors: Strambini Giovanni B. , Kerwin Bruce A. , Mason Bruce D. , Gonnelli Margherita 
Published: July 2010

AbstractAn important feature of tryptophan phosphorescence, crucial for probing protein structure and dynamics, is the drastic reduction of the lifetime (τ) in fluid solutions. Initial reports of indole and derivatives showed that τ decreases from 6 s in rigid glasses to about 1 ms in aqueous solutions at ambient temperature. Recently a report by Fischer et al. questioned the validity of the millisecond lifetime, claiming that in millimolar electrolyte solutions τ is about 40 μs, similar to the 12–30 μs of earlier determinations based on flash photolysis. Longer lived phosphorescence was detected in pure water but because it exhibited an initial growing phase and an anomalously large triplet yield, the emission was attributed to an artifact arising from the slow, first‐order, geminate recombination of the radical cation and electron generated by photochemistry. In this study, we reexamine both the phosphorescence lifetime and the triplet quantum yield of indole, N‐acetyl tryptophanamide (NATA), N‐methyl tryptophan and the tryptophan‐glycine‐glycine tripeptide under the same conditions adopted by Fischer et al. as well as over a wider range of electrolyte and buffering salts concentrations, pH, solvent and temperture. Throughout, the results show that the phosphorescence decay is slow and uniform down to the 12 μs resolution of the instrument, with no evidence of short‐lived, 40 μs‐like components. Most compelling was the similarity between the fluorescence‐normalized triplet yield of indole derivatives in water and that of W59 in the protein ribonuclease T1 or of NATA in rigid glasses. Its invariance over experimental conditions that varied the production of photoproducts several fold and the characteristic susceptibility of the triplet lifetime to O2, proton and ground state quenching demonstrated that the triplet state was formed predominantly through normal intersystem crossing and that its unquenched lifetime was at least 9 ms.
High‐resolution Studies of Lung Surfactant Collapse¶
Authors: Aga Rachel Sibug , Dunn Robert C. 
Published: July 2010

ABSTRACT Survanta is a replacement lung surfactant (LS) used in the treatment of respiratory distress syndrome (RDS), the fourth leading cause of infant mortality in the United States. It consists of purified LS from bovine sources and retains the surfactant proteins (SP) SP‐B and SP‐C, both thought to be important in proper respiratory function. As such, it provides a useful and biologically relevant model system to probe the structure and function of natural LS. Here, we report results from high‐resolution studies on model monolayers formed from Survanta to probe the mechanism of collapse at high surface pressure. Our results show the formation of two different collapse structures. At 62 mN/m, slightly below the collapse pressure, monolayer collapse occurs through buckling. Confocal fluorescence measurements on supported films reveal regions of overlapping phase structure in the films that mark the transition from monolayer to multilayer. Simultaneous near‐field scanning optical microscopy fluorescence and force measurements show that the transition seen in the fluorescence measurements accompanies corresponding ∼4–5 nm changes in membrane topography. This change in height is consistent with bilayer formation on monolayer collapse. Analysis of the phase structure near the transitions also suggests that the buckling occurs from a continuous film. However, when the film is compressed to its collapse pressure of 65 mN/m, buckling is no longer evident in the collapsed region. In addition, multilayers and lipid‐protein aggregates that are up to 40 nm higher than the monolayer are observed in the collapsed film at this pressure.
Effects of Low‐power Laser Irradiation on Cell Locomotion in Protozoa¶
Authors: Koutna Marketa , Janisch Roman , Unucka Marek , Svobodnik Adam , Mornstein Vojtech 
Published: July 2010

AbstractLow‐power lasers are commonly used in human medicine for treatment of various pathological conditions, but mechanisms of their healing effects are still poorly understood. The results of this study provide information related to these effects at the cellular level. Two different protozoan species, Euglena gracilis and Tetrahymena thermophila, were used to study changes in locomotion behavior in response to low‐power lasers. The cells were irradiated at 830 and 650 nm generated by a semiconductor laser (99 J/cm2, 360 mW) and a laser pointer (0.75 J/cm2, 5 mW), respectively, and their locomotion was recorded by a TV camera and analyzed using computer software. Exposure to laser light, regardless of the wavelength, resulted in increased cell velocity in both species (P < 0.001). Exposure to 650 nm produced an equal increase in median cell velocity in both E. gracilis (19.0%) and T. thermophila (18.2%), and some increase persisted in the postirradiation 30 s period. Irradiation by the 830 nm laser resulted in a markedly higher response in Tetrahymena (29.4%) than in Euglena (15.2%), and the two median values remained increased after irradiation was discontinued. Different reactions found in the species studied and some mechanisms underlying the response of cells to radiation are discussed.
Protective Effect of Superoxide Dismutase Against Hair Graying in a Mouse Model¶
Authors: Emerit I. , Filipe P. , Freitas J. , Vassy J. 
Published: July 2010

AbstractOxygen free radicals play a role in the aging process, and the protective effect of various antioxidants has been intensively studied, in particular for cutaneous aging. Besides hereditary factors, free radical‐mediated damage to melanocytes of the hair follicle has been considered as a mechanism for aging of the hair. It was the aim of this study to evaluate the role of photosensitization reactions for hair graying and to demonstrate potential protective effects of superoxide dismutase (SOD). Mice with black hair were depilated with the fingertips on a surface of 6 × 2.5 cm on both sides of the dorsum. The right side received five applications of a SOD‐containing gel before exposure to psoralen (concentration 0.5 mg/mL) plus UV‐A (365 nm, 4 J/cm2). The left side was pretreated in the same way with a gel free of SOD. When the hair started growing again, the SOD‐protected side was covered with black hair, whereas the hair on the vehicle‐treated side was gray or white in 27 of the 30 animals studied. The 0.01% SOD concentration was as protective as the 0.1% concentration. Heat‐inactivated SOD, applied in another five animals, was not protective. Using fluorescent labeling of the SOD with fluorescein isothiocyanate, epifluorescence microscopy and digital imaging processing, we show that SOD applied to the skin surface penetrates through the follicular appendages, as well as through the unbroken stratum corneum. Our findings suggest that superoxide radicals, generated by interaction of UV‐A light with the sensitizer, initiated the formation of secondary products with well‐known DNA‐damaging effects, such as lipid peroxidation products and tumor necrosis factor alpha. SOD prevented the damage to melanocyte DNA by dismutating superoxide. Photosensitization may be another mechanism for hair graying, which can be influenced by antioxidants. Given the large number of exogenous and endogenous sensitizers, this mechanism deserves further study for human hair graying.
pH‐Dependent modification of lipophilicity of porphyrin‐type photosensitizers
Authors: Čunderliková Beata , Kaalhus Olav , Čunderlik Róbert , Mateášik Anton , Moan Johan , Kongshaug Magne 
Published: July 2010

AbstractStructural modifications of photosensitizers (changes in protonation, ionic state and aggregation state) under different environmental conditions should be precisely determined to understand the interaction of the photosensitizers with biological systems. In the present study partition coefficients of hematoporphyrin IX (HpIX), disulfonated meso‐tetraphenylporphine, meso‐tetra(3‐hydroxyphenyl) porphine (mTHPP) and meso‐tetra (3–hydroxyphenyl)chlorin in the 1‐octanol‐phosphate buffer system were determined in the pH region 4.0‐8.0. Only the partition coefficients of HpIX and mTHPP were found to be pH dependent. Computer processing of fluorimetric titration data was applied to estimate pKa values of the imino nitrogens of mTHPP. Monoprotonated species of mTHPP seem to be unstable or nonexistent. The possibility that both imino nitrogens of this dye are protonated according to a common pKa is proposed. The pKa value of the imino nitrogens of mTHPP was found to be 2.99 ± 0.04 after the application of a model taking aggregation of the drug into account. The contributions of various qqueous ionic species of mTHPP as functions of pH were calculated and compared with partition coefficients.
Preliminary study on photoproduction of hydroxyl radicals in aqueous solution with Aldrich humic acid, algae and Fe(III) under high‐pressure mercury lamp irradiation
Authors: Liu Xianli , Xu Dong , Wu Feng , Liao Zhenhuan , Liu Jiantong , Deng Nansheng 
Published: July 2010

AbstractUnder a high‐pressure mercury lamp (HPML) and using an exposure time of 4 h, the photoproduction of hydroxyl radicals (*OH) could be induced in an aqueous solution containing humic acid (HA). Hydroxyl radicals were determined by high performance liquid chromatography using benzene as a probe. The results showed that *OH photoproduction increased from 1.80 to 2.74 μM by increasing the HA concentration from 10 to 40 mg L−1 at an exposure time of 4 h (pH 6.5). Hydroxyl radical photoproduction in aqueous solutions of HA containing algae was greater than that in the aqueous solutions of HA without algae. The photoproduction of *OH in the HA solution with Fe(III) was greater than that of the solution without Fe(III) at pH ranging from 4.0 to 8.0. The photoproduction of *OH in HA solution with algae with or without Fe(III) under a 250 W HPML was greater than that under a 125 W HPML. The photoproduction of *OH in irradiated samples was influenced by the pH. The results showed that HPML exposure for 4 h in the 4‐8 pH range led to the highest *OH photoproduction at pH 4.0.
The role of the carotenoids in the photoadaptation of the brown‐colored sulfur bacterium Chlorobium phaerobacteroides
Authors: Hirabayashi Hiroki , Ishii Takasada , Takaichi Shinichi , Inoue Kazuhito , Uehara Kaku 
Published: July 2010

AbstractThe brown‐colored sulfur bacterium Chlorobium (Cb.) phaeobacteroides 1549 (new name, Chlorobaculum limnaeum 1549) contains many kinds of carotenoids as well as bacteriochlorophyll (BChl) e. These carotenoids were identified with C18‐high‐performance liquid chromatography, absorption, mass and proton nuclear magnetic resonance spectroscopies and were divided into two groups: the first is carotenoid with one or two φ‐end groups such as isorenieratene and β‐isorenieratene and the second is carotenoid with one or two β‐end groups such as β‐zeacarotene, β‐carotene and 7,8‐dihydro‐β‐carotene. The latter 7,8‐dihydro‐β‐carotene was found to be a novel carotenoid in nature. OH‐γ‐Carotene glucoside laurate and OH‐chlorobactene glucoside laurate were also found as minor components. The distribution of BChl e homologs in Cb. phaeobacteroides cultivated under various light intensities did not change, but the carotenoid to BChl e ratio changed markedly: carotenoid with the φ‐end group maintained the same ratio to BChl e, whereas that with the β‐end group increased with increasing light intensity. The cells cultured under low‐light intensity contained more φ‐end carotenoids than β‐end. In Cb. phaeobacteroides the wavelength of the Qy band of BChl e aggregates did not change. We suggested that Cb. phaeobacteroides photoadapts to light intensity by changing the carotenoid composition.
Cooperative Effects in the Photophysical Properties of Self‐associated Triguanosine Diphosphates¶
Authors: Markovitsi Dimitra , Gustavsson Thomas , Sharonov Alexei 
Published: July 2010

ABSTRACTThe present study deals with the photophysical properties of triguanosine diphosphate in aqueous solutins, which are compared with those of the 2′‐deoxyguanosine monophosphate. They are studied by steady‐state absorption and fluorescence spectroscopy as well as by time‐resolved fluorescence spectroscopy with femtosecond resolution. The temperature, salt and concentration dependence of the absorption and fluorescence spectra reveal that association of the trimers takes place. The resulting aggregates could correspond to a tetraplex structure. The aggregate fluorescence quantum yield is higher and the fluorescence lifetime much longer than those of the monomer. These results show the interaction between guanosine residues that may manifest itself via self‐solvation, hydrogen bonding and / or delocalization of the excitation.
Optical Spectroscopy of Hydrophobic Sunscreen Molecules Adsorbed to Dielectric Nanospheres¶
Authors: Krishnan Rajagopal , Carr Aaron , Blair Elizabeth , Nordlund Thomas M. 
Published: July 2010

ABSTRACTFluorescence and absorption spectra of hydrophobic sunscreens, weakly fluorescent octyl methoxycinnamate, moderately fluorescent octyl salicylate and highly fluorescent 2‐ethylhexyl‐4‐(dimethylamino) benzoate (padimate O) adsorbed to dielectric microspheres in aqueous suspension, have been compared with spectra in organic solution. The fluorescence of adsorbed salicylate and padimate is enhanced compared with fluorescence in methanol: about a factor of 6 and 30 in terms of fluorescence yield per molecule of salicylate and padimate, respectively, Cinnamate, which has a low fluorescence yield, does not show a comparable fluorescence enhancement. The fluorescence amplification is independent of sphere diameter from 30 to 1500 nm, at least for salicylate. The enhancement, as well as the location of absorption spectral peaks, is consistent with a low‐dielectric constant environment of the molecules, in spite of the presumed location near the interface between polystyrene (E = 2.4–3.8) and water (E = 78). The adsorbed state of these sunscreens represents a proposed improved in vitro model for the environment of sunscreens in vivo, as well as a general model for chromphores in heterogeneous environments.