bluuebunny/crossref_metadata_2025 huggingface dataset:
Unexpected Photolysis of the Sunscreen Octinoxate in the Presence of the Sunscreen Avobenzone¶
Authors: Sayre Robert M. , Dowdy John C. , Gerwig Andre J. , Shlelds William J. , Lioyd Roger V.
Published: July 2010

A major concern raised about photostability studies of sunscreen products is that the photodegradation of sunscreens does not readily translate into changes in product performance. This study examines the correlation between photochemical degradation of sunscreen agents and changes in protection provided by sunscreen films. Films of a commercial sunscreen product containing avobenzone, oxybenzone and octinoxate were irradiated using a fluorescent UV‐A phototherapy lamp with additional UV‐B blocking filter. Periodically, during irradiation the transmittances of the films were measured and samples collected for chemical analysis of the sunscreen agents using high‐performance liquid chromatography techniques. The results show that UV‐induced changes in UV transmittance of sunscreen films correlate with changes in concentration of sunscreen agents. In a parallel experiment, we also irradiated a thin film of the same product in the cavity of an electron spin resonance (ESR) spectrometer. We report the concomitant photolysis of avobenzone and octinoxate that predominates over expected E/Z photoisomerization and that irradiation of a film of this product produced free radicals detected by ESR spectroscopy that persisted even after exposure had ended.
In Vivo Optical Analysis of Quantitative Changes in Collagen and Elastin During Arterial Remodeling¶
Authors: Christov Alexander , Korol Renee M. , Dai Erbin , Liu Liying , Guan Haiyan , Bernards Mark A. , Cavers Paul B. , Susko David , Lucas Alexandra
Published: July 2010

Altered collagen and elastin content correlates closely with remodeling of the arterial wall after injury. Optical analytical approaches have been shown to detect qualitative changes in plaque composition, but the capacity for detection of quantitative changes in arterial collagen and elastin content in vivo is not known. We have assessed fluorescence spectroscopy for detection of quantitative changes in arterial composition in situ, in rabbit models of angioplasty and stent implant. Fluorescence emission intensity (FEI) recorded at sites remote from the primary implant site was correlated with immunohistochemical (IH) analysis and extracted elastin and collagen. FEI was significantly decreased (P < 0.05) after treatment with anti‐inflammatory agents, and plaque area decreased on comparison with saline‐treated rabbits after stent implant or angioplasty (P≤ 0.013). Excellent correlations for FEI with elastin and collagen I, III and IV content measured by IH (R2≥ 0.961) analysis were detected by multiple regression (MR) analysis. Good correlations also were found for FEI with elastin and collagen measured by high‐performance liquid chromatography; MR analysis provided highly predictive values for collagen and elastin (R2≥ 0.994). Fluorescence spectroscopic analysis detects quantitative compositional changes in arterial connective tissue in vivo, demonstrating changes at sites remote from primary angioplasty and stent implant sites.
Photobiology of Ocular Melanocytes and Melanoma¶
Authors: Hu Dan‐Ning
Published: July 2010

There are two different types of ocular melanocytes and melanomas. Conjunctival melanocytes are located on the surface of the eye and are exposed to visible light and UV radiation. Recently, epidemiological studies demonstrated that sunlight plays a definite role in the occurrence of conjunctival melanoma, as it does in cutaneous melanoma. Uveal melanocytes consist of the iridal melanocytes, which are exposed to visible light and UV radiation; and the ciliary body melanocytes and choroidal melanocytes, which are not exposed to light radiation. Epidemiological studies demonstrated that sunlight may play a role in the occurrence of iridal melanoma, but may not be a major factor in the etiology of ciliary body and choroidal melanomas. Uveal melanocytes differ from epidermal melanocytes in that epidermal melanocytes respond to UV radiation and skin color becomes darker after exposure to sunlight; but uveal melanocytes do not respond to UV radiation and the iris color remains stable after exposure to sunlight. Recently, in vitro studies indicate that this phenomenon is determined both by cellular factors and environmental factors.
Physical and Chemical Characterization of Iris and Choroid Melanosomes Isolated from Newborn and Mature Cows¶
Authors: Hong Lian , Simon John D.
Published: July 2010

Bovine iris and choroid melanosomes at two ages (<1 week and >2 years) wer examined by inductively coupled plasma mass spectrometry (ICP‐MS), elemental analysis, infrared spectrometry (IR) and X‐ray photoelectron spectrometry (XPS). When iris and choroid melanosomes at the same age were compared, the quantification of metal elements by ICP‐MS revealed that choroid melanosomes had a higher binding capacity for the carboxylate‐binding metal ions (e.g. Na+, K+, Mg2+, Ca2+ and Zn2+). Elemental analysis showed a higher O:N ratio in choroid melanosomes. Both observations suggested that choroid melanosomes have a higher content of carboxylate‐containing monomer than iris melanosomes. IR spectrometric analysis showed a red shift (∼8 cm−1) ofthe absorption peak of aromatic C=C, C=N and C=O at ∼1630 cm−1 in the IR spectrum of iris melanosomes relative to choroid melanosomes. Increased conjugation in the molecular structure of the pigment is proposed to contribute to this peak shift. It is also notable that although the elemental anlaysis showed different C, N and O contents is the two types of melanosomes, XPS showed almost the same elemental compositions on the surface of two types of iris and choroid melanosomes studied. When the melanosomes from the same tissues at different ages were compared, ICP‐MS analysis suggested that the number of carboxylate groups in the melanosomes decreased with age. Both elemental analysis and XPS showed that C:N ratio decreased with age, which was proposed to be due to both a decrease in carboxylate groups in mature samples and to the fissure of phenol rings caused by age‐associated oxidation. Such age‐related oxidative damage diminishes conjugation and is manifested by blue shifts of absorption peaks for aromatic double bonds in the IR spectra of mature melanosomes. XPS analysis showed that the ratio of C‐O:C=O decreased with age. These tissue‐related and age‐related chemical differences between samples affected the optic density and metal binding properties of melanosomes, which are believed to be closely associated with the biological functions of melanins.
Anthocyanins Protect Against A2E Photooxidation and Membrane Permeabilization in Retinal Pigment Epithelial Cells¶
Authors: Jang Young P. , Zhou Jilin , Nakanishi Koji , Sparrow Janet R.
Published: July 2010

The pyridinium bisretinoid A2E, an autofluorescent pigment that accumulates in retinal pigment epithelial cells with age and in some retinal disorders, can mediate a detergent‐like perturbation of cell membranes and light‐induced damage to the cell. The photodynamic events initiated by the sensitization of A2E include the generation of singlet oxygen and the oxidation of A2E at carbon‐carbon double bonds. To assess the ability of plant‐derived anthocyanins to modulate adverse effects of A2E accumulation on retinal pigment epithelium (RPE) cells, these flavylium salts were isolated from extracts of bilberry. Nine anthocyanin fractions reflecting monoglycosides of delphinidin, cyanidin, petunidin and malvidin were obtained and all were shown to suppress the photooxidation of A2E at least in part by quenching singlet oxygen. The anthocyanins tested exhibited antioxidant activity of variable efficiency. The structural characteristics relevant to this variability likely included the ability to form a stable quinonoidal anhydro base at neutral pH, a conjugated diene structure in the C (pyrane) ring, the presence of hydroxyl groups on the B (benzene) ring and the relative hydrophobicity conferred by the arrangement of substituents on the B ring. Cells that had taken up anthocyanins also exhibited a resistance to the membrane permeabilization that occurs as a result of the detergent‐like action of A2E.
Time‐resolved Microscopy of ChromatinIn VitroandIn Vivo¶
Authors: Davis Sara K. , Bardeen Christopher J.
Published: July 2010

In eukaryotic cell nuclei, double‐stranded DNA is found in the form of chromatin, a large fiber made up of DNA complexed to histone proteins. In this article, recent studies using fluorescence techniques to look at the dynamics of chromatin, bothin vivoandin vitro, are reviewed. Two‐photon counter‐propagating fluorescence recovery after patterned photobleaching is used to examine chromatin fluctuations on lengthscales ranging from less than 100 nm to microns. By combiningin vivostudies with data on isolated nuclei and by measuring how these fluctuations depend on variables like ionic strength and photochemical cross‐linking, it is demonstrated that the relatively large‐scale motions of chromatin observedin vivoare consistent with smaller scale modifications of the histone‐DNA interaction. This connection may provide a means to use conformational dynamics as anin vivoprobe of the biochemical events involved in gene expression.
Novel Aspects of Intrinsic and Extrinsic Aging of Human Skin: Beneficial Effects of Soy Extract¶
Authors: Südel Kirstin M. , Venzke Kirsten , Mielke Heiko , Breitenbach Ute , Mundt Claudia , Jaspers Sören , Koop Urte , Sauermann Kirsten , KnuBmann‐Hartig Elke , Moll Ingrid , Gercken Günther , Young Antony R. , Stäb Franz , Wenck Horst , Gallinat Stefan
Published: July 2010

Biochemical and structural changes of dermal connective tissue substantially contribute to the phenotype of aging skin. To study connective tissue metabolism with respect to ultraviolet (UV) exposure, we performed an in vitro (human dermal fibroblasts) and an in vivo complementary DNA array study in combination with protein analysis in young and old volunteers. Several genes of the collagen metabolism such as Collagen I, III and VI as well as heat shock protein 47 and matrix metalloproteinase‐1 are expressed differentially, indicating UV‐mediated effects on collagen expression, processing and degradation. In particular, Collagen I is time and age dependently reduced after a single UV exposure in human skin in vivo. Moreover, older subjects display a lower baseline level and a shorter UV‐mediated increase in hyaluronan (HA) levels. To counteract these age‐dependent changes, cultured fibroblasts were treated with a specific soy extract. This treatment resulted in increased collagen and HA synthesis. In a placebo‐controlled in vivo study, topical application of an isoflavone‐containing emulsion significantly enhanced the number of dermal papillae per area after 2 weeks. Because the flattening of the dermal‐epidermal junction is the most reproducible structural change in aged skin, this soy extract appears to rejuvenate the structure of mature skin.
Comparison by PAM Fluorometry of Photosynthetic Activity of Nine Marine Phytoplankton Grown Under Identical Conditions¶
Authors: Juneau P. , Harrison P. J.
Published: July 2010

The photosynthetic activity of marine phytoplankton from five algal classes (Phaeodactylum tricornutum, Skeletonema costatum, Thalassiosira oceanica, Thalassiosira weissflogii, Dunaliella tertiolecta, Mantoniella squamata, Emiliania huxleyi, Pavlova lutheri and Heterosigma akashiwo) was investigated under identical growth conditions to determine interspecies differences. Primary photochemistry and electron transport capacity of individual species were examined by pulse amplitude‐modulated (PAM) fluorescence. Although few differences were found in maximal photosystem II (PSII) photochemical efficiency between various species, large differences were noticed in their PSII‐photosystem I (PSI) electron transport activity. We found that species such as T. oceanica and M. squamata have much lower photochemical activity than H. akashiwo. It appeared that processes involved in electron transport activity were more susceptible to change during algal evolution compared with the primary photochemical act close to PSII. Large variations in the nonphotochemical energy dissipation event among species were also observed. Light energy required to saturate photosynthesis was very different between species. We have shown that M. squamata and H. akashiwo required higher light energy (>1300 μmol m−2 s−1) to saturate photosynthesis compared with S. costatum and E. huxleyi (ca 280 μmol m−2 s−1). These differences were interpreted to be the result of variations in the size of lightharvesting complexes associated with PSII. These disparities in photosynthetic activity might modulate algal community structure in the natural environment where light energy is highly variable. Our results suggest that for an accurate evaluation of primary productivity from fluorescence measurements, it is essential to know the species composition of the algal community and the individual photosynthetic capacity related to the major phytoplankton species present in the natural phytoplankton assemblage.
Clinical Outcome of a Novel Photodynamic Therapy Technique Using Acridine Orange for Synovial Sarcomas¶
Authors: Kusuzaki Katsuyuki , Murata Hiroaki , Matsubara Takao , Miyazaki Shinichi , Shintani Ken , Seto Masashi , Matsumine Akihiko , Hosol Hajime , Sugimoto Touru , Uchida Atsumasa
Published: July 2010

Synovial sarcoma (SS) is one of common malignant softtissue tumors and is encountered most commonly in children and young adults. It frequently involves or invades major neurovascular structures and bones, and its local recurrence rate after simple resection has been reported to be as high as up to 80%. Because major nerves and vessels, as well as an adequate amount of bone, must be preserved to restore excellent limb function in cases of SS, a surgical technique entailing a low risk of local recurrence is needed. Based on the findings of recent experimental studies conducted by using a mouse osteosarcoma model, we developed a novel therapeutic technique for SS, consisting of reduction surgery followed by photodynamic therapy using acridine orange (AO‐PDT), with or without X‐ray irradiation at 5 Gy. A preliminary study revealed that low‐dose X‐rays also excite AO like photons. After an initial study on cell cultures, this novel technique was applied to six cases of SS. A follow‐up of the subjects to determine the clinical outcome revealed that none of the cases treated by AO‐PDT, including the four cases treated by additional 5 Gy irradiation and the two cases not receiving any radiation, showed any evidence of recurrence or local/systemic complications during the follow‐up period of 19‐51 months after the surgery. Therefore, we believe that AO‐PDT with 5 Gy irradiation may be an excellent novel therapeutic modality with reduction surgery to salvage excellent limb function in SS involving major nerves and vessels or bones.
UV Doses Worldwide¶†
Authors: Godar Dianne E.
Published: July 2010

UV radiation affects human health. Human exposure to UV radiation causes a few beneficial health effects like vitamin D3 formation but it causes many detrimental health effects: sunburn, ocular damage, photoaging, immune suppression, DNA damage and skin cancer. In countries with fair‐skinned populations, skin cancer is the most diagnosed of all cancers. In the United States in 2002, there were over one million new skin cancer cases. That means one out of every 285 people got skin cancer. Skin cancer of fair‐skinned individuals is increasing at an alarming rate (4–6% per year) around the world and has now reached so‐called “pandemic” proportions. Thus, it is important to know what UV doses people around the world get throughout their lives. This review covers how the outdoor UV doses are weighted for different biological effects, the most commonly used measuring devices for terrestrial and personal UV doses, the natural and other effects on terrestrial and personal UV doses, the time people spend outside, their ambient exposures and the terrestrial and personal UV doses of adult outdoor and indoor workers as well as children and adolescents around the world. Overall, outdoor‐working adults get about 10%, while indoor‐working adults and children get about 3% (2–4%) of the total available annual UV (on a horizontal plane). People's UV doses increase with increasing altitude and decreasing latitude; most indoor‐working adult Europeans get 10 000–20 000 J/m2 per year, Americans get 20 000–30 000 J/m2 per year and Australians are estimated to get 20 000–50 000 J/m2 per year (excluding vacation, which can increase the dose by 30% or more).
Drug Delivery of Aminolevulinic Acid from Topical Formulations Intended for Photodynamic Therapy¶
Authors: Donnelly Ryan F. , McCarron Paul A. , Woolfson A. David
Published: July 2010

Topical photodynamic therapy is used for a variety of malignant and pre‐malignant skin disorders, including Bowen's Disease and Superficial Basal Cell Carcinoma. A haem precursor, typically 5‐aminolevulinic acid (ALA), acting as a prodrug, is absorbed and converted by the haem biosynthetic pathway to photoactive protoprophyrin IX (PpIX), which accumulates preferentially in rapidly dividing cells. Cell destruction occurs when PpIX is activated by an intense light source of appropriate wavelength. Topical delivery of ALA avoids the prolonged photosensitivity reactions associated with systemic administration of photo‐sensitisers but its clinical utility is influenced by the tissue penetration characteristics of the drug, its ease of application and the stability of the active agent in the applied dose. This review, therefore, focuses on drug delivery applications for topical, ALA‐based PDT. Issues considered in detail include physical and chemical enhancement strategies for tissue penetration of ALA and subsequent intracellular accumulation of PpIX, together with formulation strategies and drug delivery design solutions appropriate to various clinical applications. The fundamental aspects of drug diffusion in relation to the physicochemical properties of ALA are reviewed and specific consideration is given to the degradation pathways of ALA in formulated systems that, in turn, influence the design of stable topical formulations.
The Influence of the Ethanol‐water Molar Ratio in the Precursor Solution on Morphology and Photocatalytic Activity of Pyrolytic ZnO Films¶
Authors: Quintana Maria , Rodriguez Juan , Solis José , Estrada Walter
Published: July 2010

Zinc oxide films were fabricated by a homemade spray pyrolysis system equipped with an optical setup ensuring the in situ control of the film growth. Zinc acetate (0.1 M) diluted in a mixture of ethanol and water was used as the precursor solution. The ethanol‐water molar ratio, Γ, in the precursor solution was varied from 0 to 0.92. The deposition temperature and the pH of the precursor solution were kept at 350°C and 4.5, respectively. X‐ray diffraction patterns revealed that films were zincitelike with a grain size depending on the ethanol‐water molar ratio in the precursor solution. The interference pattern obtained during film deposition was used to monitor the film roughness; it was found that this is related with those results of surfaces and optical analysis obtained by scanning electron microscopy and spectrophotometric measurements, respectively. The morphology of the ZnO films obtained from Γ equal to either 0 or 0.92 are dense with agglomerates uniformly distributed, whereas the films obtained from Γ equal to either 0.03 or 0.06 are very rough with irregular agglomerates. The films obtained from Γ equal to 0.12, 0.18 and 0.31 are rough. Photoelectrocatalytic results indicated that there is a correlation of the partial molar volume of ethanol with respect to water in the spraying solution, with the photocatalytic efficiency of the ZnO films. We found that the maximum photodegradation of methyl orange in the solution occurs using ZnO films obtained with Γ= 0.12.
Laser Flash Photolysis in a O3/Cl2 Mixture at 266 nm in a Very Low‐Pressure Flow System¶
Authors: Codnia Jorge , Manzano Francisco , Azcárate María Laura
Published: July 2010

The laser flash photolysis in a very low‐pressure flow system with mass spectrometry detection technique was developed for the study of oxidation reactions of chlorofluorocarbons. In this work, we have studied the UV photolysis of O3 in the presence of Cl2 at room temperature, which presents two catalytic cycles of O3 depletion with efficiencies dependent on the partial pressures in the photoreactor. The ozone dissociation was initiated with fourth harmonic pulses of a Nd:YAG laser. The detection of the reactants and the final and intermediate reaction products was performed with real‐time mass spectrometry. The variations of the O3, Cl2 and ClO concentration were measured. The equations system associated to a proposed kinetic scheme was solved numerically and excellent agreement with the experimental results was obtained. The results from this work allowed the determination of the wall loss rates of the O(1D), Cl and ClO radicals.
Impact of Solar Ultraviolet Radiation on Marine Phytoplankton of Patagonia, Argentina¶
Authors: Helbling E. Walter , Barbieri Elena S. , Marcoval M. Alejandra , Gonçalves Rodrigo J. , Villafañe Virginia E.
Published: July 2010

Patagonia area is located in close proximity to the Antarctic ozone “hole” and thus receives enhanced ultraviolet B (UV‐B) radiation (280–315 nm) in addition to the normal levels of ultraviolet A (UV‐A; 315–400 nm) and photosynthetically available radiation (PAR; 400‐700 nm). In marine ecosystems of Patagonia, normal ultraviolet radiation (UVR) levels affect phytoplankton assemblages during the three phases of the annual succession: (1) prebloom season (late summer‐fall), (2) bloom season (winter‐early spring) and (3) postbloom season (late spring‐summer). Small‐size cells characterize the pre‐and postbloom communities, which have a relatively high photosynthetic inhibition because of high UVR levels during those seasons. During the bloom, characterized by micro‐plankton diatoms, photosynthetic inhibition is low because of the low UVR levels reaching the earth's surface during winter; this community, however, is more sensitive to UV‐B when inhibition is normalized by irradiance (i.e. biological weighting functions). In situ studies have shown that UVR significantly affects not only photosynthesis but also the DNA molecule, but these negative effects are rapidly reduced in the water column because of the differential attenuation of solar radiation. UVR also affects photosynthesis versus irradiance (P vs E) parameters of some natural phytoplankton assemblages (i.e. during the pre‐ but not during the postbloom season). However, there is a significant temporal variability of P vs E parameters, which are influenced by the nutrient status of cells and taxonomic composition; taxonomic composition is in turn associated with the stratification conditions (e.g. wind speed and duration). In Patagonia, wind speed is one of the most important variables that conditions the development of the winter bloom by regulating the depth of the upper mixed layer (UML) and hence the mean irradiance received by cells. Studies on the interactive effects of UVR and mixing show that responses of phytoplankton vary according to the taxonomic composition and cell structure of assemblages; therefore cells use UVR if >90% of the euphotic zone is being mixed. In fact, cell size plays a very important role when estimating the impact of UVR on phytoplankton, with large cells being more sensitive when determining photosynthesis inhibition, whereas small cells are more sensitive to DNA damage. Finally, in long‐term experiments, it was determined that UVR can shape the diatom community structure in some assemblages of coastal waters, but it is virtually unknown how these changes affect the trophody‐namics of marine systems. Future studies should consider the combined effects of UVR on both phytoplankton and grazers to establish potential changes in biodiversity of the area.
Induced and Photoinduced DNA Damage by Quinolones: Ciprofloxacin, Ofloxacin and Nalidixic Acid Determined by Comet Assay¶
Authors: Sánchez Georgina , Hidalgo María Eliana , Vivanco José Miguel , Escobar Jorge
Published: July 2010

Quinolones are degraded by light with loss of their antimicrobial activity, generating active species or radicals, Evidence exists that some fluoroquinolones (lomefloxacin, fleroxacin and enoxacin) induce damage to the cellular membrane and DNA cleavage by photosensitization. In this study, the genotoxic potential of the quinolones ofloxacin, nalidixic acid and ciprofloxacin (three antimicrobials frequently used in therapy) was evaluated upon irradiation with UV light by using the comet assay on cells of the Jurkat line. The results demonstrate that there are significant differences between the control groups (positive control with 50 μM H2O2, negative controls without drug and with and without irradiation) and the groups of irradiated quinolones (ofloxacin 2.76 × 10−5M, nalidixic acid 2.15 × 10−4M and ciprofloxacin 2.01 × 10−5M), indicating that, at the dose of irradiation employed (necessary to produce 50% photodegradation), the photodecomposition of the quinolones enhanced DNA damage. The unirradiated drugs also exhibited genotoxicity significantly different from that of the negative control.
Spectral Properties of Topical Retinoids Prevent DNA Damage and Apoptosis After Acute UV‐B Exposure in Hairless Mice¶
Authors: Sorg O. , Iran C. , Carraux P. , Grand D. , Hügin A. , Didierjean L. , Saurat J.‐H.
Published: July 2010

We showed in a recent study that topical retinyl palmitate prevented UV‐B‐induced DNA damage and erythema in humans. Given that retinyl palmitate is a precursor of retinoic acid, the biological form of vitamin A that acts through nuclear receptors, we wondered whether these protective effects toward UV‐B exposure were either receptor dependent or linked to other properties of the retinoid molecule such as its spectral properties. We determined the epidermal retinoid profile induced by topical retinoic acid in hairless mice and analyzed its effect on markers of DNA photodamage (thymine dimers) and apoptosis following acute UV‐B exposure; we compared these effects to those induced by other natural topical retinoids (retinaldehyde, retinol and retinyl palmitate) which do not directly activate the retinoid receptors. We then analyzed the direct action of these retinoids on UV‐B‐induced DNA damage and apoptosis in cultured A431 keratinocytes. Topical retinoic acid significantly decreased (∼50%) the number of apoptotic cells, as well as the formation of thymine dimers in the epidermis of mice exposed to acute UV‐B. Interestingly, the other topical retinoids decreased apoptosis and DNA damage in a similar way. On the other hand, neither retinoic acid nor the other retinoids interfered with the apoptotic process in A431 keratinocytes exposed to UV‐B, whereas DNA photodamage was slightly decreased. We conclude that the decrease of apoptotic cells in hairless mouse epidermis following topical retinoids and UV‐B irradiation reflects a protection of the primary targets of UV‐B (DNA) by a mechanism independent of the activation of retinoid nuclear receptors, rather than a direct inhibition of apoptosis.
Standard Ultraviolet Daylight for Nonextreme Exposure Conditions¶
Authors: Christiaens François J. , Chardon Alain , Fourtanier Anny , Frederick John E.
Published: July 2010

The skin is exposed to ultraviolet radiation (UVR) from natural or artificial sources on a daily basis. The effects of chronic low dose exposure merit investigation, even when these effects are neither conspicuous nor clinically assessable. The purpose of the present study was to define a relative spectral UV irradiance that is representative of frequent nonextreme sun exposure conditions and therefore more appropriate for studies of the long‐term and daily effects of solar UV on the skin. Solar spectral UV irradiance values were calculated for different dates and locations by using a radiative transfer model. The spectral irradiance values obtained when the solar elevation is lower than 45° were averaged. An important feature is the dUVA (320–400 nm) to dUVB (290–320 nm) irradiance values ratio, which was found to be 27.3 for the overall average. When the months corresponding to extreme irradiance values (low or high) were excluded from the calculations, the dUVA to dUVB ratio ranged from 27.2 to 27.5. The mean spectral irradiance of the model presented here represents environmental UV exposure conditions and can be used both as a standard to investigate the biological effects of a nonextreme UVR and to assess the effectiveness of products for daily skin protection.
Imaging of Photodynamically Generated Singlet Oxygen Luminescence In Vivo¶
Authors: Niedre Mark J. , Patterson Michael S. , Giles Anoja , Wilson Brian C.
Published: July 2010

We describe a novel scanning‐laser system for imaging type‐II photodynamically generated singlet oxygen (1O2[1Δg]) luminescence and demonstrate it in vivo in an intradermal tumor model in mice. We verify the strong oxygen‐dependence of the signal and show that the images are near the practical resolution limit.
Control of DNA Hybridization with Photocleavable Adducts¶
Authors: Ghosn Bilal , Haselton Frederick R. , Gee Kyle R. , Monroe W. Todd
Published: July 2010

Previous reports have shown that 1‐(4,5‐dimethoxy‐2‐nitro‐phenyl)ethyl ester (DMNPE) adducts coupled to DNA plasmids block transcription in vitro and in vivo until removed with light. In this report, we explore the use of DMNPE to control DNA hybridization. We found that DMNPE‐caged oligonucleotides have changed spectrophotometric and elec‐trophoretic properties that can be restored with light exposure. Caged oligonucleotides have slower electrophoretic mobility than noncaged oligonucleotides and caged oligonucleotides exposed to light. Effects of caging on hybridization were assessed in a fluorescence‐based assay using a 20mer caged DNA oligonucleotide complementary to a 30mer molecular beacon. Fluorescence results indicate that hybridization is reduced and subsequently restored by light. Subsequent gel shift assays confirmed these results. Hybridization activity of caged oligonucleotides with an average of 14–16 DMNPE adducts per oligonucleotide was 14% of noncaged control oligonucleotides and after 365 nm photolysis, increased to nearly 80% of controls. Spectrophotometric characterization of caged oligonucleotides exposed to light and then filtered to remove the released DMNPE adducts indicates two to four attached cage groups remaining following photoactivation. These results suggest that this light‐based technology can be used as a tool for the spatial and temporal regulation of hybridization‐based DNA bioactivity.
Novel Water‐soluble Bacteriochlorophyll Derivatives for Vascular‐targeted Photodynamic Therapy: Synthesis, Solubility, Phototoxicity and the Effect of Serum Proteins¶
Authors: Brandis Alexander , Mazor Ohad , Neumark Eran , Rosenbach‐Belkin Varda , Salomon Yoram , Scherz Avigdor
Published: July 2010

New negatively charged water‐soluble bacteriochlorophyll (Bchl) derivatives were developed in our laboratory for vascular‐targeted photodynamic therapy (VTP). Here we focused on the synthesis, characterization and interaction of the new candidates with serum proteins and particularly on the effect of serum albumin on the photocytotoxicity of WST11, a representative compound of the new derivatives. Using several approaches, we found that aminolysis of the isocyclic ring with negatively charged residues markedly increases the hydrophilicity of the Bchl sensitizers, decreases their self‐association constant and selectively increases their affinity to serum albumin, compared with other serum proteins. The photocytotoxicity of the new candidates in endothelial cell culture largely depends on the concentration of the serum albumin. Importantly, after incubation with physiological concentrations of serum albumin (500–600 μM), WST11 was found to be poorly photocytotoxic (>80% endothelial cell survival in cell cultures). However, in a recent publication (Mazor, O. et al. [2005] Photochem. Photobiol. 81, 342–351) we showed that VTP of M2R melanoma xenografts with a similar WST11 concentration resulted in ∼100% tumor flattening and >70% cure rate. We therefore propose that the two studies collectively suggest that the antitumor activity of WST11 and probably of other similar candidates does not depend on direct photointoxication of individual endothelial cells but on the vascular tissue response to the VTP insult.
Phototropins and Associated Signaling: Providing the Power of Movement in Higher Plants¶
Authors: Celaya R. Brandon , Liscum Emmanuel
Published: July 2010

Recent developments in phototropin biology have provided exciting new findings on the roles of these photoreceptor proteins in plants. Much of the recent work has focused on phototropin photochemistry and the structural alterations in both the chromophoric and peptide components of the molecule associated with light perception. In this review, specific aspects of phototropin action in higher plants will be discussed in the context of these new findings. Although, as their name suggests, phototropins play a key role in phototropic responses in plants, increasing evidence shows they have many other functions in plants. In this review, the roles of phototropins in additional plant “movement” responses will be addressed; in particular their roles in stomatal aperture control and chloroplast movements. In discussing these various movement responses special attention will be given to identified and hypothesized downstream signaling partners or events that enable the phototropins to selectively participate in any one or more of these responses in a given light condition.
Photoinduced DNA Cleavage and Cellular Damage in Human Dermal Fibroblasts by 2,3‐Diaminophenazine¶
Authors: Fu Patty K.‐L. , Abuzakhm Sonia , Turro Claudia
Published: July 2010

Aromatic amines, such as o‐phenylenediamine (OPD), have been used extensively in commercial hair dyes and in the synthesis of agricultural pesticides. Air oxidation of OPD results in the formation of 2,3‐diaminophenazine (DAP). Although the mutagenic toxicity of DAP has been shown in both prokaryotic and eukaryotic systems, its phototoxicity remains largely unexplored. This study focuses on the pH‐dependent photophysical properties of DAP and demonstrates its ability to photoinduce DNA damage to pUC19 plasmid in vitro. The photocytotoxicity of DAP toward human skin fibroblasts was also measured. DAP exhibits weak intercalative binding to double‐stranded DNA with a binding constant Kb= 3.5 × 103M−1. Furthermore, upon irradiation with visible light, DAP is able to nick plasmid DNA in the presence of oxygen. The concentration of DAP that resulted in 50% cell death was 172 ± 9 μM in the dark and 13 ± 1 μM after irradiation of the DAP‐treated cell cultures with visible light (400–700 nm, 30 min, 5 J/cm2). The 13‐fold increase in toxicity upon exposure to visible light shows the need for further study of the photocytotoxicity of contaminants such as DAP.
Oxidation Potentials of Human Eumelanosomes and Pheomelanosomes¶
Authors: Samokhvalov Alexander , Hong Lian , Liu Yan , Garguilo Jacob , Nemanich Robert J. , Edwards Glenn S. , Simon John D.
Published: July 2010

Eumelanosomes and pheomelanosomes isolated from black and red human hair, respectively, were studied by photo‐electron emission microscopy (PEEM). PEEM images were collected at various wavelengths between 207 and 344 nm, using the spontaneous emission output of the Duke OK‐4 free electron laser (FEL). Analysis of the FEL‐PEEM data revealed ionization thresholds of 4.6 and 3.9 eV corresponding to oxidation potentials of −0.2 and +0.5 V vs normal hydrogen electrode for eumelanosomes and pheomelanosomes, respectively. The difference in oxidation potential is attributed to the pigment content of the melanosome, namely whether it contains primarily eumelanin and pheomelanin. The effect of added melanosomes on the reduction of Fe(III)‐cytochrome showed pheomelanosomes are stronger reducing agents than eumelanosomes, consistent with the measured oxidation potentials. The FEL‐PEEM experiment offers to be an important new approach for quantifying the effects of age, oxidation and metal accumulation on the oxidation potentials of intact melanosomes.
Stability of Tin Etiopurpurin¶
Authors: Poriel Cyril , Kessel David , Vicente M. Graça H.
Published: July 2010

Formulations of the tin etiopurpurin (SnET2) have been observed to undergo a spectral change on storage in dimethyl‐formamide solution. This results in an alteration in the action spectrum, with enhanced photodynamic activity at lower wavelengths and decreased activity at 660 nm. On the basis of structural considerations, a reduced analog of SnET2 was prepared with an absorbance maximum at 640 nm. Formation of this product, termed SnET2H2 relieves steric strain inherent in the parent molecule. Nuclear magnetic resonance, spectral and photodynamic data are consistent with the formation of SnET2H2 during SnET2 storage. Slight modifications in the original synthesis are also reported, resulting in improved yields of intermediate products.
Self‐aggregation of Synthetic Protobacteriochlorophyll‐d Derivatives¶
Authors: Tamiaki Hitoshi , Kitamoto Hiroyuki , Watanabe Takuya , Shibata Reiko
Published: July 2010

31‐Racemically pure zinc 31‐hydroxy‐131‐oxo‐porphyrins (zinc methyl 17,18‐dehydro‐bacteriopheophorbides‐d) as well as their 31‐demethyl form were prepared by modifying chlorophyll‐a through oxidation by 2,3‐dichloro‐5,6‐dicyano‐benzoquinone. From visible, circular dichroism and infrared spectral analyses, these synthetic pigments self‐aggregated in 1%(vol/vol) tetrahydrofuran and cyclohexane to give large oligomers by an intermolecular bonding of 13‐C=O…H‐O(31) … Zn(central) and π‐π interaction of the porphyrin chromophores. The supramolecular structures are similar to those of the corresponding chlorins and a core part of extra‐membranous light‐harvesting antennas of photosynthetic green bacteria. The 17,18‐dehydrogenation of a chlorin to porphyrin moiety did not disturb its self‐aggregation, and the synthetic zinc porphyrins are good models for naturally occurring, self‐aggregative bacteriochlorophylls.
Glacial Influences on Solar Radiation in a Subarctic Sea¶
Authors: Barron Mace G. , Barron Kyle J.
Published: July 2010

Understanding macroscale processes controlling solar radiation in marine systems will be important in interpreting the potential effects of global change from increasing ultraviolet radiation (UV) and glacial retreat. This study provides the first quantitative assessment of UV in the water column of Prince William Sound, a subarctic, semienclosed sea surrounded by mountains, glaciers, rivers, bays and fjords in south central Alaska. Glacial influences on diffuse attenuation coefficients (Kd) were determined along an approximate 120 km transect running NE (61°07′43″N, 146°17′1″W) to SW (60°27′25″N, 148°05′27′″W). Glacial meltwater and flour caused a 10‐fold increase in Kd for visible light, UV‐A and UV‐B, whereas high optical clarity was present in a diversity of areas away from glacial influences. Transition areas and locations affected by calving of a tidewater glacier had intermediate Kd values. Depths at 99% attenuation ranged from less than 0.2 m near glacial streams to greater than 5 m in bays and open ocean distant from sources of glacial sediments. These results suggest that potential global change from increasing UV and glacial retreat may have heterogeneous effects on subarctic marine systems.
Enhancement of Laser Cancer Treatment by a Chitosan‐derived Immunoadjuvant¶
Authors: Chen Wei R. , Korbelik Mladen , Battels Kenneth E. , Liu Hong , Sun Jinghai , Nordquist Robert E.
Published: July 2010

A chitosan derivative, glycated chitosan (GC), has been used as an immunostimulant for cancer treatment in laser immunotherapy. The function of GC is to enhance the host immune response after direct cancer cell destruction by a selective laser photothermal interaction. To further test its effects, laser immunotherapy was extended to include several different adjuvants for immunological stimulation and to include photodynamic therapy (PDT) as a different tumor‐destruction mechanism. Complete Freund (CF) adjuvant, incomplete Freund (IF) adjuvant and Corynebacterium parvum (CP) were selected for treatment of metastatic mammary tumors in rats, in combination with a selective photothermal interaction. The solution of the immunoadjuvants admixed with indocyanine green (ICG), a light‐absorbing dye, was injected directly into the tumors, followed by noninvasive irradiation of an 805 nm laser. Combined with PDT, in the treatment of tumors in mice, GC was administered peritumorally immediately after laser irradiation. The survivals of treated animals were compared with untreated control animals. In the treatment of rat tumors, CF, IF and CP raised the cure rates from 0% to 18%, 7% and 9%, respectively. In comparison, GC resulted in a 29% long‐term survival. In the treatment of EMT6 mammary sarcoma in mice, GC of 0.5% and 1.5% concentrations increased the cure rates of Photofrin‐based PDT treatment from 38% to 63% and 75%, respectively. In the treatment of Line 1 lung adenocarcinoma in mice, a 1.67% GC solution enabled a noncurative meso‐substituted tetra(meta‐hydroxy‐phenyl)chlorin–based PDT to cure 37% of the tumor‐bearing mice. The experimental results of this study confirmed our previous studies, showing that immunoadjuvants played an active role in laser‐related cancer treatment and that GC significantly enhanced the efficacy of laser cancer treatment.
Dynamic Holography in Bacteriorhodopsin/Gelatin Films: Effects of Light–Dark Adaptation at Different Humidity†
Authors: Korchemskaya Elena , Burykin Nikolai , Bugaychuk Svitlana , Maksymova Olena , Ebrey Thomas , Balashov Sergei
Published: July 2010

This work examines the kinetics of dynamic holography responses in light‐adapted and dark‐adapted bacteriorhodopsin (BR) films at different humidity. We have demonstrated that the kinetics of the diffraction efficiency in wild type BR films is quite different in dark‐adapted and light‐adapted samples. The holographic recording kinetics, which depends on the duration of incubation in the dark after light adaptation at different humidity values, was studied in depth. A specially designed miniature cell containing a BR film was mounted inside the holographic set up to allow controlled humidity changes over a broad range. The diffraction efficiency kinetics at humidity values of 96–99% were quite different from the kinetics at 60–93% humidity. We found that humidity values of 90–93% were most optimal for dynamic holography recording using a gelatin film containing BR. In agreement with a calculation of the wavelength‐dependent changes of the refractive index for dark‐adapted and light‐adapted BR samples using the Kramers–Kronig relation, the maximum difference in the refractive index and thus in the diffraction efficiency for dark‐adapted and light‐adapted BR films takes place at 630 nm, close to the wavelength of the He–Ne laser used.
Production of Reactive Oxygen Species on Photolysis of Dilute Aqueous Quinone Solutions
Authors: Garg Shikha , Rose Andrew L. , Waite T. David
Published: July 2010

We have examined the generation of the reactive oxygen species (ROS) superoxide and hydrogen peroxide (H2O2) by irradiation of dilute aqueous solutions of disodium anthraquinone‐2‐6‐disulfonate (AQDS) with simulated sunlight. Irradiating a solution of AQDS in 2 mM NaHCO3 and 0.01 M NaCl produced superoxide and H2O2 at nanomolar concentrations. Experiments in which initial concentrations of dioxygen, H2O2, the superoxide radical trap nitroblue tetrazolium and the electron donor dimethyl sulfoxide were varied suggested that the interaction of solvent water with photo‐excited quinone moieties produces dioxygen‐reducing radicals, and that these are the primary source of ROS in the system. A kinetic model for ROS production is proposed based on our experimental data.
Dual Chromophore‐Nitroxides: Novel Molecular Probes, Photochemical and Photophysical Models and Magnetic Materials
Authors: Likhtenstein Gertz I. , Ishii Kazuyuki , Nakatsuji Shin’ichi
Published: July 2010

Over the last decades scientists have faced growing requirements in novel methods of fast and sensitive analysis of antioxidant status of biological systems, spin redox probing and spin trapping, investigation of molecular dynamics, and of convenient models for studies of photophysical and photochemical processes. In approaching this problem, methods based upon the use of dual chromophore‐nitroxide (CN) compounds have been suggested and developed. A CN consists of two molecular sub‐functionality (a chromophore and a stable nitroxide radical) tethered together by spacers. In the dual compound the nitroxide is a strong intramolecular quencher of the fluorescence from the chromophore fragment. Reduction to hydroxylamine, oxidation of the nitroxide fragment or addition of an active radical yield the fluorescence increase and the parallel decay of the fragment electron spin resonance (ESR) signal. At certain conditions the dual molecules undergo photomagnetic switching and form excited state multi‐spin systems. These unique properties of CN were intensively exploited as the basis for several methodologies, which include molecular probing, modeling intramolecular photochemical and photophysical processes, and construction of new magnetic materials.
Involvement of Interleukin‐10 Promoter Polymorphisms in Nonmelanoma Skin Cancers—A Case Study in Non‐Caucasian Skin Cancer Patients†
Authors: Nagano Tohru , Kunisada Makoto , Yu Xijun , Masaki Taro , Nishigori Chikako
Published: July 2010

Interleukin 10 (IL‐10) is a potent immunosuppressive cytokine, therefore elevated IL‐10 expression has been implicated in inhibition of antitumor immune response. IL‐10 gene promoter polymorphism has been shown to be involved in susceptibility to skin cancers, but there has been no report focusing on susceptibility to skin cancers among non‐Caucasian populations. We enrolled 129 patients with skin cancers and 50 age‐ and sex‐matched healthy controls between April 2004 and March 2007. Genomic DNA was extracted from patients’ blood samples and IL‐10 promoter polymorphisms were identified using polymerase chain reaction‐restriction fragment length polymorphism or direct sequencing. The distribution of the frequency of allele or haplotype of IL‐10 gene promoter in Japanese was quite different from that of Europeans. No significant differences could be demonstrated in the frequency of allele or haplotype of IL‐10 gene promoter between the patient group and the control group. However, the frequency of the low‐IL‐10 expression haplotype was significantly high in Bowen’s disease subgroup. The frequency of low expression IL‐10 promoter genotype was significantly less (P = 0.009, χ2 = 6.74) in the group of nonmelanoma skin cancer generated on sun‐exposed areas in comparison with that on covered areas. Our results indicated that low expression haplotype of IL‐10 in Bowen’s disease may inhibit the escape of tumor cells from immune surveillance, resulting in suppression of tumor growth and tumor invasion to the dermis. Moreover, high IL‐10‐expressing haplotype of IL‐10 promoter may be a risk factor for photocarcinogenesis.