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Photochemie - Neueste Forschungsartikel der Fachverlage


 
Aktuelle Fachartikel zur Photochemie und Photobiologie, sortiert nach Erscheinungsdatum.

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Photochemical & Photobiological Sciences - published by The Royal Society of Chemistry -
PPS meets the growing information needs of scientists working in the areas of photochemistry and photobiology, and indeed, encourages a synergism between these two important research areas. This international journal is published monthly on behalf of the European Photochemistry Association (EPA), the European Society for Photobiology (ESP), the Asia and Oceania Society for Photobiology (AOSP) and the Korean Society of Photoscience (KSP), and is available in both print and electronic formats.

Photochemistry and Photobiology - published by Wiley-Interscience -
... publishes original research articles and reviews on current topics in photoscience.



Aktuelle wissenschaftliche Fachartikel der genannten Journale:


Distinct Role of Sesn2 in Response to UVB-induced DNA Damage and UVA-induced Oxidative Stress in Melanocytes

Abstract

Ultraviolet (UV) radiation, including both UVB and UVA irradiation, is the major risk factor for causing skin cancer including melanoma. Recently we have shown that Sesn2, a member of the evolutionarily conserved stress-inducible protein family Sestrins (Sesn), is up-regulated in human melanomas as compared to melanocytes in normal human skin, suggesting an oncogenic role of Sesn2. However, the role of Sesn2 in UVB and UVA response is unknown. Here we demonstrated that both UVB and UVA induce Sesn2 up-regulation in melanocytes and melanoma cells. UVB induces Sesn2 expression through the p53 and AKT3 pathways. Sesn2 negatively regulates UVB-induced DNA damage repair. In comparison UVA induces Sesn2 up-regulation through mitochondria but not Nrf2. Sesn2 ablation increased UVA-induced Nrf2 induction and inhibits UVA-induced ROS production, indicating that Sesn2 acts as an upstream regulator of Nrf2. These findings suggest previously unrecognized mechanisms in melanocyte response to UVB and UVA irradiation and potentially in melanoma formation.

This article is protected by copyright. All rights reserved.

Quelle: Photochemistry and Photobiology | 27 Jul 2016 | 4:50 pm CEST

Attitudes, Beliefs and Measures Taken by Parents to Protect Their Children from the Sun in Guangzhou City, China

Abstract

Excessive sun exposure can cause sunburn, suntan, skin photoaging, and even skin cancer. Skin photoaging conflicts with the human pursuit of a young and beautiful appearance. Some research data indicate that the incidence of skin cancer in the Chinese has been increasing, although it remains lower than in whites. To estimate the prevalence of sun protection used on Chinese children aged 3–13 years and identify its predictors, a population-based cross-sectional questionnaire was give to 3,684 parents/guardians of children in Guangzhou, China of which 3,083 questionnaires were returned. Of those returned, 35.5% of parents/guardians reported regularly using sun protection on their children and the primary reason cited was to prevent sunburn. Hats and handheld umbrellas were the most frequently used measures; sunscreen was less common, and when used, 48.8% of parents/guardians still reapplied sunscreen on their children every 2.0–3.0 h. Parental age, parents using sun protection measures themselves when outdoors, and the child's sex were factors associated with regular use of sun protection on children. These results suggest that sun protection campaigns targeted toward parents and children need to be conducted in Guangzhou, or throughout China, to strengthen awareness about sun protection and address any inadequate protocols of sun protection.

This article is protected by copyright. All rights reserved.

Quelle: Photochemistry and Photobiology | 27 Jul 2016 | 4:45 pm CEST

FAD and MTHF are the in-planta Cofactors of Arabidopsis thaliana Cryptochrome 3

Abstract

Members of the cryptochrome/photolyase family (CPF) of proteins utilize non-covalently bound light-absorbing cofactors for their biological function. Usually, the identity of these cofactors is determined after expression in heterologous systems leaving the question unanswered whether these cofactors are identical to the indigenous ones. Here, cryptochrome 3 from Arabidopsis thaliana was expressed as a fusion with the green fluorescent protein in Arabidopsis plants. Besides the confirmation of the earlier report of its localization in chloroplasts, our data indicate that fractions of the fusion protein are present in the stroma and associated with thylakoids, respectively. Furthermore, it is shown that the fusion protein expressed in planta contains the same cofactors as the His6-tagged protein expressed in Escherichia coli, i.e., flavin adenine dinucleotide and N5,N10-methenyltetrahydrofolate. This demonstrates that the heterologously-expressed cryptochrome 3, characterized in a number of previous studies, is a valid surrogate of the corresponding protein expressed in plants. To our knowledge, this is also a first conclusive analysis of cofactors bound to an Arabidopsis protein belonging to the CPF and purified from plant tissue.

This article is protected by copyright. All rights reserved.

Quelle: Photochemistry and Photobiology | 27 Jul 2016 | 4:45 pm CEST

Selective Photoreceptor Gene Knock-out Reveals a Regulatory Role for the Growth Behavior of Pseudomonas syringae

Abstract

The plant pathogen Pseudomonas syringae (Ps) is a well-established model organism for bacterial infection of plants. The genome sequences of two pathovars, pv. syringae and pv. tomato, revealed one gene encoding a blue and two genes encoding red/far red light-sensing photoreceptors. Continuing former molecular characterization of the photoreceptor proteins, we here report selective photoreceptor gene disruption for pv. tomato aiming at identification of potentially regulatory functions of these photoreceptors. Transformation of Ps cells with linear DNA constructs yielded interposon mutations of the corresponding genes. Cell growth studies of the generated photoreceptor knock-out mutants revealed their role in light-dependent regulation of cell growth and motility. Disruption of the blue-light (BL) receptor gene caused a growth deregulation, in line with an observed increased virulence of this mutant (Moriconi et al., Plant J., 2013, 76, 322). Bacterial phytochrome-1 (BphP1) deletion mutant caused unaltered cell growth, but a stronger swarming capacity. Inactivation of its ortholog, BphP2, however, caused reduced growth and remarkably altered dendritic swarming behavior. Combined knock-out of both bacteriophytochromes reproduced the swarming pattern observed for the BphP2 mutant alone. A triple knock-out mutant showed a growth rate between that of the BL (deregulation) and the phytochrome-2 mutant (growth reduction).

Thumbnail image of graphical abstract

The plant-pathogenic bacterium Pseudomonas syringae expresses three photoreceptors: one flavin-binding BL-sensing LOV-domain protein and two bilin-binding red-/far red-sensing bacterial phytochromes. All three photoreceptors communicate their biological signal via classical two-component systems composed of histidine kinases and response regulators. Stepwise single and multiple photoreceptor gene knock-out identifies important regulatory functions of light. Active photoreceptors in P. syringae keep tissue damage of plant leaves upon infection at a moderate level, whereas gene knock-out increases virulence. In addition, mutant cells with deleted phytochrome genes show either increased growth (Δphy1) or highly altered dendritic swarming behavior (Δphy2, Figure).

Quelle: Photochemistry and Photobiology | 26 Jul 2016 | 9:38 am CEST

Peroxyoxalate High-Energy Intermediate is Efficiently Decomposed by the Catalyst Imidazole

Abstract

The peroxyoxalate reaction is a highly efficient chemiluminescence system, its chemiexcitation process involving the intermolecular interaction between an activator (ACT) and the high-energy intermediate (HEI) of the reaction. Typically, the HEI is generated through the reaction of an oxalate ester with H2O2, in the presence of a basic/nucleophilic catalyst, such as imidazole (IMI-H). IMI-H, besides catalyzing the formation of the HEI, is also known to decompose this peroxidic intermediate. Despite that, up to now, no rate constant value has been determined for such significant interaction. Through kinetic measurements, we have observed that IMI-H is roughly four times more efficient than 9,10-diphenylanthracene (DPA), a classic ACT, in catalyzing the decomposition of the HEI by a bimolecular electron transfer reaction through a Chemically Initiated Electron Exchange Luminescence-like process. For instance, when IMI-H and DPA are at the same concentration, 78% of the generated HEI is actually consumed by the nonemissive bimolecular interaction with IMI-H. We have obtained an average singlet excited state formation quantum yield, at infinite ACT concentration, of (5.5 ± 0.5) × 10−2 E mol−1, determined at five different IMI-H concentrations. This ultimately suggests that the yield of formation of HEI actually does not depend on the IMI-H concentration.

Thumbnail image of graphical abstract

When the high-energy intermediate (HEI) of the light-emitting peroxyoxalate reaction is generated in the presence of imidazole and an activator (i.e. 9,10-diphenylanthracene), with both at the same concentration, up to 78% of this intermediate is actually consumed by a bimolecular imidazole-catalyzed dark decomposition pathway. This HEI is generated based on the reaction between an aryl oxalate ester with H2O2 and, paradoxically, imidazole is known to be the best basic/nucleophilic catalyst available for such reaction.

Quelle: Photochemistry and Photobiology | 26 Jul 2016 | 9:38 am CEST

Editorial

Quelle: Photochemistry and Photobiology | 26 Jul 2016 | 9:38 am CEST

Diffuse Reflectance Spectroscopy Versus Mexameter® MX18 Measurements of Melanin and Erythema in an African Population

Abstract

Melanin provides protection against excess exposure to solar ultraviolet radiation (UVR) and related adverse health effects. Diffuse reflectance spectroscopy (DRS) can be used to calculate cutaneous melanin and erythema, but this is complex and has been mostly used for light-to-medium pigmented skin. Handheld reflectance spectrophotometers, such as the Mexameter® MX18, can also be used. We compared DRS-calculated melanin and erythema values with Mexameter melanin and erythema index values to understand how these techniques/measurements correlate in an African population of predominantly deeply pigmented skin. Five hundred and three participants comprised 68.5% self-identified Black African, 9.9% Indian/Asian, 18.4% White and 2.9% Colored. The majority of Black African (45%), Indian/Asian (34%) and Colored (53%) participants self-identified their skin as being “brown.” Measured melanin levels increased with darker self-reported skin color. DRS-calculated and Mexameter melanin values demonstrated a positive correlation (Spearman rho = 0.87, P < 0.001). The results from both instruments showed erythema values were strongly correlated with their own melanin values. This finding is considered spurious and may result from the complexity of separating brown and red pigment when using narrowband reflectance techniques. Further work is needed to understand melanin, erythema and color in Black skin given sun-related health risks in vulnerable groups in Africa.

Thumbnail image of graphical abstract

Melanin provides protection against excess sun exposure. Diffuse Reflectance Spectroscopy (DRS) is used to calculate melanin and erythema, but has mostly been used for light-to-medium pigmented skin. We compared DRS-calculated melanin and erythema values with a handheld reflectance Mexameter melanin and erythema values to understand how these techniques/measurements correlate among Africans with predominantly deeply pigmented skin. DRS-calculated and Mexameter melanin values demonstrated a positive correlation. Both instruments' results showed that erythema values were strongly correlated with their own melanin values. Further work is needed to understand melanin, erythema and color in Black skin, given sun-related health risks posing vulnerable groups in Africa.

Quelle: Photochemistry and Photobiology | 26 Jul 2016 | 9:38 am CEST

Red Light Treatment in an Axotomy Model of Neurodegeneration

Abstract

Red light has been shown to provide neuroprotective effects. Axotomizing the optic nerve initiates retinal ganglion cell (RGC) degeneration, and an early marker of this is dendritic pruning. We hypothesized that 670 nm light can delay axotomy-induced dendritic pruning in the retinal explant. To test this hypothesis, we monitored the effects of 670 nm light (radiant exposure of 31.7 J cm−2), on RGC dendritic pruning in retinal explants from C57BL/6J mice, at 40 min, 8 h and 16 h post axotomy. For sham-treated retinae, area under the Sholl curve, peak of the Sholl curve and dendritic length at 8 h post axotomy showed statistically significant reductions by 42.3% (P = 0.008), 29.8% (P = 0.007) and 38.4% (P = 0.038), respectively, which were further reduced after 16 h by 40.56% (< 0.008), 33.9% (< 0.007), 45.43% (< 0.006), respectively. Dendritic field area was also significantly reduced after 16 h, by 44.23% (< 0.019). Such statistically significant reductions were not seen in light-treated RGCs at 8 or 16 h post axotomy. The results demonstrate the ability of 670 nm light to partially prevent ex vivo dendropathy in the mouse retina, suggesting that it is worth exploring as a treatment option for dendropathy-associated neurodegenerative diseases, including glaucoma and Alzheimer's disease.

Thumbnail image of graphical abstract

Red light has been shown to provide neuroprotective effects. Axotomizing the optic nerve initiates retinal ganglion cell (RGC) degeneration, and an early marker of this is dendropathy. We demonstrate the ability of 670 nm light to partially prevent ex vivo dendropathy in the mouse retina. The area under the Sholl curve, the peak of the Sholl curve, dendritic length and dendritic field area showed statistically significant reductions after 16 h by 40.56% (< 0.008), 33.9% (< 0.007), 45.43% (< 0.006) and 44.23% (< 0.019), respectively, in sham-treated retinae. Such statistically significant reductions were not seen in red light-treated retinae.

Quelle: Photochemistry and Photobiology | 26 Jul 2016 | 9:38 am CEST

Relative Contributions of UVB and UVA to the Photoconversion of (6-4) Photoproducts into their Dewar Valence Isomers

Abstract

Dewar valence isomers are photoisomerization products of pyrimidine (6-4) pyrimidone photoproducts, a major class of UV-induced DNA lesions, which exhibits a maximal absorption around 320 nm. However, Dewar isomers are not produced in significant amounts in cells exposed to biologically relevant doses of UVB. In contrast, they are readily produced when cells are exposed to a combination of UVA and UVB. The present computational work demonstrates that, on the basis of known absorption properties and formation quantum yields, the difference in Dewar formation between the two types of radiation can be explained by the role of normal bases. In the UVB range, at the low level of (6-4) photoproducts present in cells exposed to realistic doses, normal bases are present in overwhelming amounts and absorb the vast majority of the incident photons. In contrast, the absorption of DNA bases is much weaker in the UVA range while that of (6-4) photoproducts is still significant, making photoisomerization possible. This two-photon process makes it difficult to define an action spectrum for the formation of Dewar isomers.

Thumbnail image of graphical abstract

The formation of Dewar isomers in DNA is efficient upon exposure to combinations of UVA and UVB. In contrast, UVB alone is not efficient at inducing the photoisomerization of (6-4) photoproducts while pure UVA does not induce the latter class of damage.

Quelle: Photochemistry and Photobiology | 26 Jul 2016 | 9:38 am CEST

Issue Information

Quelle: Photochemistry and Photobiology | 26 Jul 2016 | 9:38 am CEST

Synthesis of TiO2/CNT Composites and its Photocatalytic Activity Toward Sudan (I) Degradation

Abstract

Semiconductor photocatalysis has the potential for achieving sustainable energy generation and degrading organic contaminants. In TiO2, the addition of carbonaceous nanomaterials has attracted extensive attention as a means to increase its photocatalytic activity. In this study, composites of TiO2 and carbon nanotubes (CNT) in various proportions were synthesized by the hydrothermal method. The crystalline structures, morphologies, and light absorption properties of the TiO2/CNT photocatalysts were characterized by PXRD, TEM and UV–Vis absorption spectra. The photocatalytic efficiency of the composites was evaluated by the degradation of Sudan (I) in UV–Vis light. Introducing 0.1–0.5 wt% CNT was shown to substantially improve the photoactivity of TiO2. The composite with 0.3 wt% CNT showed the best catalytic activity, and its reaction activation energy was calculated as 39.57 kJ mol−1 from experimental rates. The degradation products of Sudan (I) with different irradiation durations were characterized by Fourier transform infrared spectroscopy, and a degradation reaction process was proposed.

Thumbnail image of graphical abstract

The Sudan (I) peak at 2345 nm−1 disappeared in all the irradiated samples, indicating the fast degradation of –N=N. This led to changes in the conjugate structure of Sudan (I), causing the absorption peaks of benzene and -CH functional groups blue-shifted to the 1525, 1457, 1389, 1330 nm−1 and 669 nm−1, respectively. The spectra confirmed that Sudan (I) was effectively degraded by the catalyst.

Quelle: Photochemistry and Photobiology | 26 Jul 2016 | 9:38 am CEST

A new orange emitting luciferase from the Southern-Amazon Pyrophorus angustus (Coleoptera: Elateridae) click-beetle: structure and bioluminescence color relationship, evolutional and ecological considerations

Photochem. Photobiol. Sci., 2016, Advance Article
DOI: 10.1039/C6PP00165C, Paper
Danilo T. Amaral, Gabriela Oliveira, Jaqueline R. Silva, Vadim R. Viviani
The new orange bioluminescence eliciting luciferase from the Amazon P. angustus click-beetle was cloned and sequenced, showing that the substitutions at position 247 is critical for modulating bioluminescence colors in click beetle luciferases.
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Quelle: RSC - Photochem. Photobiol. Sci. latest articles | 25 Jul 2016 | 1:00 am CEST

Validation and in-vivo assessment of an innovative satellite-based solar UV dosimeter for a mobile app dedicated to skin health

Photochem. Photobiol. Sci., 2016, Accepted Manuscript
DOI: 10.1039/C6PP00129G, Paper
Marco Morelli, Andrea Masini, Emilio Simeone, Marina Khazova
We present an innovative satellite-based solar UV (ultraviolet) radiation dosimeter with a mobile app interface that has been validated by exploiting both ground-based measurements and an in-vivo assessment of the...
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Quelle: RSC - Photochem. Photobiol. Sci. latest articles | 25 Jul 2016 | 1:00 am CEST

Red light activated "caged" reagents for micro RNA research

Photochem. Photobiol. Sci., 2016, Accepted Manuscript
DOI: 10.1039/C6PP00046K, Communication
Andreas Meyer, Margot Schikora, vytaute starkuviene, Andriy Mokhir
"Caged" reagents for miRNA research (siRNA targeting EGFR, involved in miRNA maturation, and mimics of miR-20a, playing a key role in tumor formation and metastasis) were prepared. It was demonstrated...
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Quelle: RSC - Photochem. Photobiol. Sci. latest articles | 25 Jul 2016 | 1:00 am CEST

Facile preparation of N-doped TiO2 at ambient temperature and pressure under UV light with 4-nitrophenol as the nitrogen source and its photocatalytic activities

Photochem. Photobiol. Sci., 2016, Advance Article
DOI: 10.1039/C6PP00167J, Paper
Satoshi Horikoshi, Yutaro Shirasaka, Hiroshi Uchida, Natsuko Horikoshi, Nick Serpone
This article reports the facile preparation of N-doped TiO2 (P25) in aqueous media at ambient temperature and pressure under inert conditions with 4-nitrophenol as the nitrogen source.
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Quelle: RSC - Photochem. Photobiol. Sci. latest articles | 19 Jul 2016 | 1:00 am CEST

Near–infrared–Responsive Peptide that Targets Collagen Fibrils to Induce Cytotoxicity

Abstract

A novel conjugate, PHG10–dye, was synthesized using a collagen peptide and a near-infrared (NIR) responsive dye to achieve targeted cytotoxicity. The collagen peptide motif, -(Pro-Hyp-Gly)10- (PHG10), was incorporated for targeting collagen fibrils that are excessively produced by activated fibroblasts around tumor cells. PHG10–dye was purified by HPLC and identified by MALDI-MS. The phototoxicity and cytotoxicity of PHG10–dye were examined using human glioma cells (HGCs). Fluorescent images indicated that PHG10–dye preferably assembled to collagen-coated HGCs compared with non-coated HGCs. Under irradiation with NIR light, effective cytotoxicity was observed on collagen-coated HGCs within 20 min. Because phototoxicity and cytotoxicity are dependent on the assembled amount of PHG10–dye, the targeting of collagen fibrils by the collagen peptide motif PHG10 is assured.

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Quelle: Photochemistry and Photobiology | 18 Jul 2016 | 6:15 pm CEST

The Effects of Ultraviolet Ray Eye Irradiation on DSS-induced Ulcerative Colitis in Mice

Abstract

Ultraviolet (UV) eye irradiation denatures the cells of the intestine. This study examined the action of UVA and UVB on dextran sodium sulfate (DSS)-induced ulcerative colitis. We produced a mouse model of ulcerative colitis by administering DSS for five days, and irradiated the eye with UVB or UVA for each day of the DSS-treatment period. DSS-induced ulcerative colitis was deteriorated by the UVB eye irradiation. Conversely, the symptoms improved with UVA eye irradiation. The levels of adrenocorticotropic hormone (ACTH), corticotropin-releasing hormone (CRH), urocortin 2, interleukin (IL)-18, IL-6, and histamine in the blood increased after the UVB eye irradiation of DSS-treated mice (UVB/DSS-treated mice). In contrast, the β-endorphin level in the blood of the UVA/DSS-treated mice increased and the levels urocortin 2, tumor necrosis factor (TNF)-α and histamine decreased. Furthermore, in the colon, the expression of melanocortin-2 receptors (MC2R) increased in the UVB/DSS-treated mice, while the expression of μ-opioid receptors increased in the UVA/DSS-treated mice. When an ACTH inhibitor was administered, UVB eye irradiation caused the deterioration of DSS-treated ulcerative colitis, while the effect of UV eye irradiation disappeared with a μ-opioid receptor antagonist. These results suggested that UV eye irradiation plays an important role in DSS-induced ulcerative colitis.

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Quelle: Photochemistry and Photobiology | 18 Jul 2016 | 6:06 pm CEST

Differential Laser-induced Perturbation Spectroscopy for Analysis of Mixtures of the Fluorophores L-Phenylalanine, L-Tyrosine, and L-Tryptophan Using a Fluorescence Probe

Abstract

Quantitative detection of common endogenous fluorophores is accomplished using differential laser-induced perturbation spectroscopy (DLIPS) with a 193-nm UV fluorescence probe and various UV perturbation wavelengths. In this study, DLIPS is explored as an alternative to traditional fluorescence spectroscopy alone, with a goal of exploring natural fluorophores pursuant to biological samples and tissue analysis. To this end, aromatic amino acids, namely, L-Phenylalanine, L-Tyrosine and L-Tryptophan are mixed with differing mass ratios and then classified with various DLIPS schemes. Classification with a traditional fluorescence probe is used as a benchmark. The results show a 20% improvement in classification performance of the DLIPS method over the traditional fluorescence method using partial least squares (PLS) analysis. Additional multivariate analyses are explored and the relevant photochemistry is elucidated in the context of perturbation wavelengths. We conclude that DLIPS is a promising biosensing approach with potential for in vivo analysis given the current findings with fluorophores relevant to biological tissues.

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Quelle: Photochemistry and Photobiology | 15 Jul 2016 | 10:05 am CEST

Photoprotective Potential of Baccharis antioquensis (Asteraceae) as Natural Sunscreen

Abstract

In the quest for new natural agents of photoprotection, we evaluated the photoprotective and antioxidant activity of B. antioquensis leaf extracts as well as its phenolic composition. The methanolic extract treated with activated carbon showed the highest absorption coefficients for UVA-UVB radiation, as well as an antioxidant capacity comparable to BHT. Furthermore, the formulation containing this extract showed suitable sensorial and photostable characteristics for topical use, and significant values of UVAPF, critical wavelength (λc), UVA/UVB ratio and SPF (5.3, 378 nm, 0.78 and 9.1±0.1, respectively). In addition, three glycoside derivatives of quercetin, a kaempferol glycoside and a derivative of caffeic acid were the main polyphenolic compounds identified. These results demonstrate the potential of B. antioquensis extracts to be used as active components of novel, natural sunscreens.

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Quelle: Photochemistry and Photobiology | 15 Jul 2016 | 10:05 am CEST

Isomerization controlled photopolymerization: effect of dye photophysics on photoinitiation efficiency

Photochem. Photobiol. Sci., 2016, Advance Article
DOI: 10.1039/C6PP00028B, Paper
C. Ley, A. Ibrahim, X. Allonas
The efficiency of free radical polymerization by photoinitiating systems based on two Astrazon orange cyanine dyes was shown to be directly related to the isomerization process of the dye in the excited states.
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Quelle: RSC - Photochem. Photobiol. Sci. latest articles | 15 Jul 2016 | 1:00 am CEST

A theoretical study of ruthenium complexes with 2,2[prime or minute]-biimidazole-like ligands: structural, optical and emissive properties

Photochem. Photobiol. Sci., 2016, Advance Article
DOI: 10.1039/C6PP00148C, Paper
Shu-Hua Xia, Wei-Hai Fang, Ganglong Cui, Chantal Daniel
A detailed theoretical analysis of the specific structural, optical and emission properties of ruthenium complexes with 2,2[prime or minute]-biimidazole-like ligands synthesized for their photophysical and photooxidative properties under visible light is presented.
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Quelle: RSC - Photochem. Photobiol. Sci. latest articles | 13 Jul 2016 | 1:00 am CEST

The DGAT1 inhibitor pradigastat does not induce photosensitivity in healthy human subjects: a randomized controlled trial using three defined sunlight exposure conditions

Photochem. Photobiol. Sci., 2016, Accepted Manuscript
DOI: 10.1039/C6PP00042H, Paper
Daniel Bauer, Rachel L. Soon, Kenneth Kulmatycki, Yuming Chen, Adele Noe, Jin Chen, Jonathan S. Dosik, Dan Meyers
The DGAT1 inhibitor, pradigastat, demonstrated a mild phototoxicity signal in preclinical studies. Therefore, this clinical trial was conducted to assess the risk of photosensitivity in humans. 47 healthy adults were...
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Quelle: RSC - Photochem. Photobiol. Sci. latest articles | 13 Jul 2016 | 1:00 am CEST

Control of the intermolecular photodimerization of anthracene derivatives by hydrogen bonding of urea groups in dilute solution

Photochem. Photobiol. Sci., 2016, Advance Article
DOI: 10.1039/C6PP00125D, Paper
Hisato Matsumoto, Yoshinobu Nishimura, Tatsuo Arai
The control of the photodimerization reaction of anthracene-urea compounds was achieved by (1) aggregate conformation depending on the substitution site and (2) inhibition of aggregation by the addition of TBAAc.
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Quelle: RSC - Photochem. Photobiol. Sci. latest articles | 13 Jul 2016 | 1:00 am CEST

Germ Cell Testicular Cancer Incidence, Latitude and Sunlight Associations in the United States and Australia

Abstract

International patterns suggest germ cell testicular cancer (GCTC) incidence may be lower in lower latitudes. To investigate this possibility, we examined GCTC incidence by latitude (population-centroid in 2000) for men >15 years within two reasonably homogeneous countries, the United States (US) and Australia. In the US, we examined age-adjusted incidence/latitude trends using data from states (2001-2010) and local-area registries (1980-2011). In Australia, we evaluated incidence/latitude trends in 61 Statistical Divisions (2000-2009). In White US men (68,566 cases), state incidences increased by latitude, rising 5.74% (4.45-7.05%) per 5°North latitude increment. Similar trends were found for seminoma and non-seminoma subtypes (p<0.001). In Black US men (2,256 cases), the association was also seen (4.9%; 0.2 to 9.7%). In local US data, similar increases in incidence with latitude were present in each of the last three decades. In Australia (6,042 cases), the incidence increased by 4.43% (95% CI: 1.54-7.39%) per 5°South, and trends for subtypes were similar. Thus, we found that incidence of GCTC in both White and Black men increased significantly with distance from the equator, approximately 1% per degree within the range of latitudes studied.

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Quelle: Photochemistry and Photobiology | 11 Jul 2016 | 3:26 pm CEST

Effects of organic acids and initial solution pH on photocatalytic degradation of bisphenol A (BPA) in a photo-Fenton-like process using goethite ([small alpha]-FeOOH)

Photochem. Photobiol. Sci., 2016, Advance Article
DOI: 10.1039/C6PP00051G, Paper
Guangshan Zhang, Qiao Wang, Wen Zhang, Tian Li, Yixing Yuan, Peng Wang
Proposed reaction mechanism of BPA photodegradation in an [small alpha]-FeOOH-oxalate synergistic system.
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Quelle: RSC - Photochem. Photobiol. Sci. latest articles | 11 Jul 2016 | 1:00 am CEST

Ultra-weak Photon Emission from the Seed Coat in Response to Temperature and Humidity - A Potential Mechanism for Environmental Signal Transduction in the Soil Seed Bank

Abstract

Seeds beneath the soil sense the changing environment to time germination and seedling emergence with the optimum time of year for survival. Environmental signals first impact with the seed at the seed coat. To investigate whether the seed coat has a role in environmental sensing we investigated their ultra-weak photon emission (UPE) under the variable temperature, relative humidity and oxygen conditions they could experience in the soil seed bank. Using a custom built luminometer we measured UPE intensity and spectra (300-700 nm) from Phaseolus vulgaris seeds, seed coats and cotyledons. UPE was greatest from the internal surface of the seed coat. Seed coat UPE increased concomitantly with both increasing temperature and decreasing relative humidity. Emission was oxygen dependent and it was abolished by treatment with dinitrophenylhydrazine demonstrating the key role of seed coat carbonyls in the phenomenon. We hypothesize that beneath the soil surface the attenuation of light (virtual darkness: low background noise) enables seeds to exploit UPE for transducing key environmental variables in the soil (temperature, humidity and oxygen) to inform them of seasonal and local temperature patterns. Overall, seed coats were found to have potential as effective transducers of key fluctuating environmental variables in the soil.

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Quelle: Photochemistry and Photobiology | 8 Jul 2016 | 8:55 am CEST

Albumin–Folate Conjugates for Drug-targeting in Photodynamic Therapy

Abstract

Photodynamic therapy (PDT) is based on the cytotoxicity of photosensitizers in the presence of light. Increased selectivity and effectivity of the treatment is expected if a specific uptake of the photosensitizers into the target cells, often tumor cells, can be achieved. An attractive transporter for that purpose is the folic acid receptor α (FRα), which is overexpressed on the surface of many tumor cells and mediates an endocytotic uptake. Here, we describe the synthesis and photobiological characterization of polar β-carboline derivatives as photosensitizers covalently linked to folate-tagged albumin as the carrier system. The particles were taken up by KB (human carcinoma) cells within <90 min and then co-localized with a lysosomal marker. FRα antibodies prevented the uptake and also the corresponding conjugate without folate was not taken up. Accordingly, a folate-albumin-β-carbolinium conjugate proved to be phototoxic, while the corresponding albumin–β-carbolinium conjugates without FA were nontoxic, both with and without irradiation. An excess of free folate as competitor for the FRα-mediated uptake completely inhibited the photocytotoxicity. Interestingly, the albumin conjugates are devoid of photodynamic activity under cell-free conditions, as shown for DNA as a target. Thus, phototoxicity requires cellular uptake and lysosomal degradation of the conjugates. In conclusion, albumin–folate conjugates appear to be promising vehicles for a tumor cell targeted PDT.

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Folate-tagged albumin mediates the endocytotic uptake of covalently attached photosensitizer molecules (cHa) into target cells (tumor cells), which thereby become photosensitive. The cytotoxicity of the particles totally depends on (1) the presence of the folate receptors (FRα) on the target cells and (2) the subsequent irradiation with light.

Quelle: Photochemistry and Photobiology | 7 Jul 2016 | 9:35 am CEST

Different hollow and spherical TiO2 morphologies have distinct activities for the photocatalytic inactivation of chemical and biological agents

Photochem. Photobiol. Sci., 2016, Advance Article
DOI: 10.1039/C6PP00093B, Paper
Yuichi Yamaguchi, Takahito Shimodo, Sho Usuki, Kanjiro Torigoe, Chiaki Terashima, Ken-ichi Katsumata, Masahiko Ikekita, Akira Fujishima, Hideki Sakai, Kazuya Nakata
TiO2 hollows and spheres are a suitable morphology for photocatalytic decomposition of dimethyl sulfoxide and anti-pathogen performance, respectively.
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Quelle: RSC - Photochem. Photobiol. Sci. latest articles | 6 Jul 2016 | 1:00 am CEST

Metallophthalocyanines as triplet sensitizers for highly efficient photon upconversion based on sensitized triplet-triplet annihilation

Photochem. Photobiol. Sci., 2016, Advance Article
DOI: 10.1039/C6PP00172F, Paper
J. L. Han, J. You, H. Yonemura, S. Yamada, S. R. Wang, X. G. Li
Photon upconversion emission from rubrene in the 550-620 nm region was achieved using new soluble palladium and platinum phthalocyanine sensitizers with maximum PUC efficiency [similar]5.6%, excited by a 633 nm laser with power <20 mW cm-2.
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Quelle: RSC - Photochem. Photobiol. Sci. latest articles | 5 Jul 2016 | 1:00 am CEST

Influence of Donor on the Sensing Performance of a Series of Through-Bond Energy Transfer-Based Two-photon Fluorescent Cu2+ Probes

Abstract

Optical properties of a series of molecular two-photon fluorescent Cu2+ probes containing the same acceptor (rhodamine group) are analyzed using time-dependent density functional theory in combination with analytical response theory. Special emphasis is placed on evolution of the probes' optical properties in the presence of Cu2+. In this study, the compound with naphthalene as the donor is shown to be excellent ratiometric fluorescent chemosensor, whereas the compound with quinoline derivative as the donor shows off/on-typed colorimetric fluorescent response. For the compound with naphthalimide derivative as the donor, changing the connection between the donor and acceptor can efficiently prevent the fluorescent quenching of the probe both in the absence and presence of Cu2+. The donor moiety and the connection between donor and acceptor are thus found to play dominant roles on sensing performance of these probes. Moreover, distributions of molecular orbitals involved in the excitation and emission of the probes are analyzed to explore responsive mechanism of the probes. The through-bond energy transfer process is theoretically demonstrated. Our results are used to elucidate the available experimental measurements. This work is helpful to understand the relationships of structure with optical properties for the studied probes.

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Two-photon fluorescent probe is regarded as an excellent tool of sensing various detected subjects. Sensing performances of two typical two-photon fluorescent probes based on through-bond energy transfer are validated theoretically and two more probes are designed to investigate the donor effect. Analysis of molecular orbitals is presented to explore responsive mechanism of the probes.

Quelle: Photochemistry and Photobiology | 30 Jun 2016 | 6:45 am CEST

Shielding effects in spacious macromolecules: a case study with dendronized polymers

Photochem. Photobiol. Sci., 2016, Advance Article
DOI: 10.1039/C6PP00191B, Communication
Chiara Gstrein, Peter Walde, A. Dieter Schluter, Thomas Nauser
The first experimental evidence is shown for the obvious suggestion that diffusion into the backbone of a dendronized polymer is increasingly hindered with increasing dendron generation, i.e. size.
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Quelle: RSC - Photochem. Photobiol. Sci. latest articles | 30 Jun 2016 | 1:00 am CEST

Heat Shock Proteins in the context of photodynamic therapy: autophagy, apoptosis and immunogenic cell death

Photochem. Photobiol. Sci., 2016, Accepted Manuscript
DOI: 10.1039/C6PP00097E, Perspective
Matias Exequiel Rodriguez, Ingrid Sol Cogno, Laura Natalia Milla Sanabria, Yanina Moran, Viviana Alicia Rivarola
Photodynamic therapy (PDT) is an anti-tumor treatment administered for the elimination of early-stage malignancies and the palliation of symptoms in patients with late -stage tumors, which involves the activation of...
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Quelle: RSC - Photochem. Photobiol. Sci. latest articles | 30 Jun 2016 | 1:00 am CEST

Effect of substitution on the ultrafast deactivation of the excited state of benzo[b]thiophene-arylamines

Photochem. Photobiol. Sci., 2016, Advance Article
DOI: 10.1039/C6PP00140H, Paper
J. Pina, M.-J. R. P. Queiroz, J. Seixas de Melo
A complete and systematic study of the spectroscopic and photophysical properties of five novel diarylamines in the benzo[b]thiophene series (oligoanilines) was performed.
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Quelle: RSC - Photochem. Photobiol. Sci. latest articles | 30 Jun 2016 | 1:00 am CEST

Room temperature phosphorescence from a guest molecule confined in the restrictive space of an organic-inorganic supramolecular assembly

Photochem. Photobiol. Sci., 2016, Advance Article
DOI: 10.1039/C6PP00124F, Communication
Yohei Ishida, Tetsuya Shimada, Elamparuthi Ramasamy, Vaidhyanathan Ramamurthy, Shinsuke Takagi
Supramolecular double walls composed of organic capsules and inorganic nanosheets realized stable room-temperature phosphorescence of enclosed guest molecules due to the effective suppression of oxygen quenching.
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Quelle: RSC - Photochem. Photobiol. Sci. latest articles | 30 Jun 2016 | 1:00 am CEST

Remarkably high homoselectivity in [2 + 2] photodimerization of trans-cinnamic acids in multicomponent systems

Photochem. Photobiol. Sci., 2016, Advance Article
DOI: 10.1039/C6PP00201C, Communication
Thanh Binh Nguyen, Ali Al-Mourabit
[2 + 2] homoadducts were exclusively obtained with total regio- and stereo-selectivities when a suspension of several solid photoactive trans-cinnamic acids in cyclohexane was stirred and irradiated.
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Quelle: RSC - Photochem. Photobiol. Sci. latest articles | 30 Jun 2016 | 1:00 am CEST

Photodynamic therapy with intralesional methylene blue and a 635 nm light-emitting diode lamp in hidradenitis suppurativa: a retrospective follow-up study in 7 patients and a review of the literature

Photochem. Photobiol. Sci., 2016, Advance Article
DOI: 10.1039/C6PP00082G, Paper
Eugenia Agut-Busquet, Jorge Romani, Yolanda Gilaberte, Ana Garcia-Malinis, Miquel Ribera-Pibernat, Jesus Luelmo
Hidradenitis suppurativa is a chronic inflammatory skin disease which has an estimated prevalence 1%. It is characterized by the formation of recurrent painful suppurative nodules and abscesses in the flexural areas of the body.
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Quelle: RSC - Photochem. Photobiol. Sci. latest articles | 29 Jun 2016 | 1:00 am CEST

Synergetic adsorption and photocatalytic degradation of pollutants over 3D TiO2-graphene aerogel composites synthesized via a facile one-pot route

Photochem. Photobiol. Sci., 2016, Advance Article
DOI: 10.1039/C6PP00133E, Paper
Jing-Jie Zhang, Yu-Hui Wu, Jin-Ya Mei, Guang-Ping Zheng, Ting-Ting Yan, Xiu-Cheng Zheng, Pu Liu, Xin-Xin Guan
A series of 3D TiO2-GA composites were successfully self-assembled, which exhibited excellent adsorption capacities and visible light photocatalytic activity in the degradation of RhB.
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Quelle: RSC - Photochem. Photobiol. Sci. latest articles | 28 Jun 2016 | 1:00 am CEST

Plantamajoside Inhibits UVB and Advanced Glycation End Products-induced MMP-1 Expression by Suppressing the MAPK and NF-ĸB Pathways in HaCaT Cells

Abstract

Photoaging and glycation stress are major causes of skin deterioration. Oxidative stress caused by ultraviolet B (UVB) irradiation can upregulate matrix metalloprotease 1 (MMP-1), a major enzyme responsible for collagen damage in the skin. Advanced glycation end products (AGEs) accumulate via gradual formation from skin proteins, especially from long-lived proteins such as dermal elastin and collagen. Plantamajoside (PM), isolated from Plantago asiatica, has various biological effects including anti-inflammatory and antioxidant effects. In this study, we assessed the protective effects of PM on a human keratinocyte cell line (HaCaT) and primary human dermal fibroblasts (HDF) against stress caused by glyceraldehyde-induced AGEs (glycer-AGEs) with UVB irradiation. We found that PM attenuated UVB-and-glycer-AGEs–induced MMP-1 expression in HaCaT and HDF cells and proinflammatory cytokines expression by inhibiting the phosphorylation of mitogen-activated protein kinases (MAPKs) activated by reactive oxygen species. Specific inhibitors of NF-κB and MAPKs attenuated the induced expression of MMP-1. PM also inhibited the phosphorylation of IκBα, and reduced nuclear translocation of NF-κB in these cells. Furthermore, PM attenuated the upregulation of receptor for AGEs (RAGE) by glycer-AGEs with UVB irradiation. Therefore, our findings strongly suggest that PM is a promising inhibitor of skin photoaging.

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Quelle: Photochemistry and Photobiology | 27 Jun 2016 | 10:05 am CEST

Ground and excited state interactions of metalloporphyrin PtTMPyP4 with polynucleotides [poly(dG-dC)]2 and [poly(dA-dT)]2

Photochem. Photobiol. Sci., 2016, Advance Article
DOI: 10.1039/C6PP00105J, Paper
Paraic M. Keane, John M. Kelly
Binding of PtTMPyP4 to synthetic polynucleotides poly(dA-dT)2 and poly(dG-dC)2 results in an increase in triplet state emission quantum yield and lifetime.
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Quelle: RSC - Photochem. Photobiol. Sci. latest articles | 27 Jun 2016 | 1:00 am CEST

Harnessing and storing visible light using a heterojunction of WO3 and CdS for sunlight-free catalysis

Photochem. Photobiol. Sci., 2016, Advance Article
DOI: 10.1039/C6PP00091F, Paper
Seonghun Kim, Yiseul Park, Wooyul Kim, Hyunwoong Park
A heterojunction of CdS/WO3 is a suitable candidate to convert sunlight to electrons and store them for use during periods of unavailable sunlight.
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Quelle: RSC - Photochem. Photobiol. Sci. latest articles | 27 Jun 2016 | 1:00 am CEST

A Possible Phenom of Persistence in Pseudomonas aeruginosa Treated With Methylene Blue and Red Light

Abstract

Planktonic Pseudomonas aeruginosa cells harvested in stationary phase were exposed to red light in presence of methylene blue to study the potential occurrence of persistence in bacterial populations submitted to photodynamic antimicrobial therapy. Survival curves revealed the existence of small subpopulations of cells exhibiting increased ability to tolerate the treatment. These subpopulations were detected even using high concentrations of photosensitizer, whether added in a single step or following a fractionated scheme, and when the irradiation medium was modified to delay the photodecomposition of methylene blue. When cells grown from survivors to the treatment were cultured and exposed to red light and dye, their responses were similar to that of the original strain. These results exclude exhaustion of the photosensitizer and selection of resistant mutants as explanations for the features of the survival curves. Cells able to tolerate the treatment were found even when radiation was imparted at a high dose rate. They exhibit a response typical of persisters, which tolerate antimicrobial agents due to transient and reversible changes in their phenotype, suggesting that persistence is a factor to consider upon evaluating the efficacy of photodynamic antimicrobial therapy.

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Quelle: Photochemistry and Photobiology | 25 Jun 2016 | 4:50 pm CEST

Surface Arginine Saturation Effect on Unfolding Reaction of Firefly Luciferase: A Thermodynamic and Kinetic Perspective

Abstract

Replacement of some hydrophobic solvent-exposed residues in Lampyris turkestanicus luciferase with arginine increases thermostability of this enzyme. Herein, thermodynamic and kinetic of unfolding reactions of wild type (WT), E354R/356R, E354R/356R-I232R and E354R/356R-Q35R/L182R/I232R variants has been investigated. Fluorescence and Far-UV circular dichroism signals using urea as chemical denaturant indicated that the value of ∆G(H2O) for all variants is greater than that of WT enzyme. Analysis of m-values, as a measure of difference in the solvent accessible surface area between the native and denatured states of protein, revealed that higher stability of mutants is related to their higher degree of compactness in the folded state. Results of unfolding kinetic experiments showed that all variants have three-exponential behavior in which, they unfolded with three rate constants and corresponding amplitudes. Increasing the rate constants of fast unfolding phase in mutants relative to WT protein may be attributed to more compactness and more kinetic sensitivity of their folded state to urea. However, more population of WT protein was unfolded from fast unfolding phase. Results of this investigation highlight kinetic stability of luciferase via a slow rate of unfolding.

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Quelle: Photochemistry and Photobiology | 25 Jun 2016 | 4:45 pm CEST

Mechanism and analyses for extracting photosynthetic electrons using exogenous quinones - what makes a good extraction pathway?

Photochem. Photobiol. Sci., 2016, Advance Article
DOI: 10.1039/C6PP00076B, Paper
G. Longatte, F. Rappaport, F.-A. Wollman, M. Guille-Collignon, F. Lemaitre
The extraction of photosynthetic electrons by exogenous quinones on unicellular green algae was investigated with fluorescence measurements. Zone diagrams were built for defining the most appropriate harvesting conditions.
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Quelle: RSC - Photochem. Photobiol. Sci. latest articles | 24 Jun 2016 | 1:00 am CEST

Photo-induced electron transfer in a diamino-substituted Ru(bpy)3[PF6]2 complex and its application as a triplet photosensitizer for nitric oxide (NO)-activated triplet-triplet annihilation upconversion

Photochem. Photobiol. Sci., 2016, Advance Article
DOI: 10.1039/C6PP00153J, Paper
Kejing Xu, Jianzhang Zhao, Evan G. Moore
The photo-induced electron transfer in the diamino-Ru(bpy)3 complex was studied with ultrafast absorption spectroscopy and was used for nitric oxide (NO)-activated triplet-triplet annihilation upconversion.
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Quelle: RSC - Photochem. Photobiol. Sci. latest articles | 22 Jun 2016 | 1:00 am CEST

Reduced Levels of Tissue Inhibitors of Metalloproteinases (TIMPs) in UVB Irradiated Corneal Epithelium

Abstract

Tissue inhibitors of metalloproteinases (TIMPs) are the major endogenous regulators of metalloproteinase activity in tissues. TIMPs are able to inhibit activity of all known matrix metalloproteinases (MMPs) and thus participate in controlling extracellular matrix synthesis and degradation. We showed previously elevated expressions of MMPs in the rabbit corneal epithelium upon UVB exposure and suggested that these enzymes might be involved in corneal destruction caused by excessive proteolysis. The aim of this study was to investigate TIMPs in the corneal epithelium after UV irradiation using immunohistochemical and biochemical methods. We found that as compared to control rabbit corneas where relatively high levels of TIMPs were present in the epithelium, repeated irradiation of the cornea with UVB rays (not with UVA rays of similar doses) significantly decreased TIMPs in corneal epithelial cells. The results of this study point to the suggestion that the decrease of TIMPs in the corneal epithelium after UVB irradiation contributes to increased proteolytic activity of MMPs in UVB irradiated corneal epithelium found previously.

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Quelle: Photochemistry and Photobiology | 18 Jun 2016 | 9:25 am CEST

Development of a Novel Covalent Folate-Albumin-Photosensitizer Conjugate

Abstract

There is considerable interest in the development of novel and more efficient delivery systems for improving the efficacy of photodynamic therapy (PDT). The authors in this highlighted issue describe the synthesis and the photobiological characterizations of two photosensitizer (PS) conjugates based on β-carboline derivatives covalently conjugated to folic acid (FA) coupled to bovine serum albumin (BSA) as a carrier system specifically targeting cancer cells overexpressing FA receptor alpha (FRα). Accordingly, only the FA–BSA–β-carboline conjugates are internalized specifically in FRα-positive cells and are proved to be phototoxic. On the other hand, albumin–β-carboline conjugates without FA or β-carboline derivatives alone are not internalized and nontoxic. This conjugate is among the first to produce a conjugate composed of a PS and FA molecules that are directly conjugated to BSA. In addition, the in vitro studies are the first evidence that directly conjugated FA-BSA can be used as carriers to selectively enhance cytotoxicity by PDT relative to unmodified PS or nontargeted BSA-PS. This strategy is a positive step forward for the covalent design and construction of a photodynamic nanomedicine for FR-positive tumors.

Quelle: Photochemistry and Photobiology | 17 Jun 2016 | 8:40 pm CEST

Identification of a Fluorescent Protein from Rhacostoma atlantica

Abstract

We have cloned a novel fluorescent protein from the jellyfish Rhacostoma atlantica. The closest known related fluorescent protein is the Phialidium yellow-fluorescent protein, with only a 55% amino acid sequence identity. A somewhat unusual alanine-tyrosine-glycine amino acid sequence forms the presumed chromophore of the novel protein. The protein has an absorption peak at 466 nm and a fluorescence emission peak at 498 nm. The fluorescence quantum yield was measured to be 0.77 and the extinction coefficient is 58,200 M−1 cm−1. Several mutations were identified that shift the absorption peak to about 494 nm and the emission peak to between 512 and 514 nm.

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Quelle: Photochemistry and Photobiology | 11 Jun 2016 | 3:15 pm CEST

Regulation of Black Pepper Inflorescence Quantity by Shading at Different Growth Stages

Abstract

Black pepper is a perennial plant that can bloom throughout the year. It is generally expected that pepper inflorescence quantity could be minimized at the nonfull-bloom stage. The objective of this study was to find an appropriate shading measure that could inhibit blooming at other growing stages except the full-bloom stage and did not cause any reduction in pepper yield and quality. In this study, pepper trees were shaded up to 15%, 30%, 60% and 75%, respectively, and the inflorescence quantity, photosynthetic characteristics, pepper yield and quality traits were investigated at every growing stage. The results showed that the effect of shading on pepper yield decreased as time progressed. Shading treatment did not alter the composition of piperine and volatile oil, but reduced the moisture content. Based on the correlation between photosynthetic parameter and inflorescence number, the appropriate shading intensities for regulating inflorescence quantity at different phenological stages were determined. Moreover, it was found that the regulation of inflorescence quantity could be achieved by controlling leaf temperature during recovery to filling period. This research outcome also will give us some guidelines to develop other management strategies that control leaf temperature and regulate inflorescence quantity to consequently improve pepper yield.

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We examined the effect of duration of shading on pepper yield and quality. An appropriate shading measure could regulate inflorescence quantity.

Quelle: Photochemistry and Photobiology | 8 Jun 2016 | 9:25 am CEST

Vibrationally Resolved Absorption and Fluorescence Spectra of Firefly Luciferin: A Theoretical Simulation in the Gas Phase and in Solution

Abstract

Firefly bioluminescence has been applied in several fields. However, the absorption and fluorescence spectra of the substrate, luciferin, have not been observed at the vibrational level. In this study, the vibrationally resolved absorption and fluorescence spectra of firefly luciferin (neutral form LH2, phenolate ion form LH and dianion form L2−) are simulated using the density functional method and convoluted by a Gaussian function, with displacement, distortion and Duschinsky effects in the framework of the Franck–Condon approximation. Both neutral and anionic forms of the luciferin are considered in the gas phase and in solution. The simulated spectra have desired band maxima with the experimental ones. The vibronic structure analysis reveals that the features of the most contributive vibrational modes coincide with the key geometry-changing region during transition between the ground state and the first singlet excited state.

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This figure shows the simulated absorption and fluorescence spectra of phenolate-carboxylate ion of firefly luciferin in water. They are generally a mirror image of each other. Moreover, the 0–0 band position is also shown.

Quelle: Photochemistry and Photobiology | 8 Jun 2016 | 9:25 am CEST

Problems on the Evaluation of the Critical Wavelength of Sunscreens for “Broad Spectrum” Approval Brought on by Viscous Fingering During Sunscreen Application

Abstract

When a viscous liquid is applied to a solid substrate, a patterned liquid layer is usually formed by the phenomenon called viscous fingering, since the moving liquid surface is in far-from-equilibrium conditions to let the morphological fluctuation to grow. Pseudosunscreen solutions were prepared and applied on a flat quartz plate. A spatially periodic stripe pattern was formed on the pseudosunscreen layer when a block applicator was used, whereas a flat surface layer was formed when a four-sided applicator was used. UV absorbance of the patterned layer was lower than that of the flat layer having the same average thickness. In addition, a larger decrease in the UV absorbance by the pattern formation was observed at wavelengths at which the UV absorbance of the flat layer was large, which was consistent with theoretical simulations. In 2011, US FDA introduced a new rule using the term “Broad Spectrum” for labeling the sunscreens. The different decrease in the UV absorbance at each wavelength was found to change the critical wavelength, which is a criterion for sunscreens to be labeled as “Broad Spectrum” protection. The result of this study makes the problem on the evaluation of the critical wavelength come to the surface.

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Pseudosunscreen solutions were prepared and applied on a flat quartz plate. A spatially periodic stripe pattern was always formed on the pseudosunscreen layer when a block applicator was used. UV absorbance of the patterned layer was lower than that of the flat layer having the same average thickness. Larger decrease in the UV absorbance by the pattern formation was observed at wavelength at which the UV absorbance of the flat layer was large to change the critical wavelength for “Broad Spectrum” approval.

Quelle: Photochemistry and Photobiology | 7 Jun 2016 | 7:55 am CEST

Proteomic and Physiological Studies Provide Insight into Photosynthetic Response of Rice (Oryza sativa L.) Seedlings to Microgravity

Abstract

The mechanisms whereby how photosynthesis is regulated and maintained under conditions of microgravity remain incompletely understood. Herein, we took a combination of proteomic and physiological approaches to examine the response of rice (Oryza sativa L.) seedlings to spaceflight conditions. Our results show that both PSI fluorescence emission peak and P700 absorbance amplitude are severely decreased in spaceflight seedlings under microgravity. This is consistent with an observed significant reduction in PSI efficiency (ϕI). To further analyze global changes of protein profiles under microgravity, isobaric tags for relative and absolute quantization (iTRAQ) labeling technology were deployed. Four hundred fifty-four differentially expressed proteins were identified by comparison of spaceflight and ground control. Of proteins relevant to photosynthesis, 34 were downregulated and 4 were upregulated. The significantly downregulated ones are essential components of PSI, NDH and the Cytb6f complex. This downregulation of PSI proteins and/or protein structure changes may cause the overall reduction in PSI activity. Intriguingly, although abundance of some PSII proteins was altered under microgravity, no significant changes in PSII activity were detected. Taken together, our results suggest that PSI, rather than PSII being usually much more sensitive to environmental stresses, is more susceptible to spaceflight conditions in rice seedlings.

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Shenzhou-8 spaceship was launched for a 17-day unmanned mission with a Long March rocket from the Jiuquan Satellite Launch Center. SIMBOX situated on Shenzhou-8 contained 17 biomedical experiments from both Chinese and German researchers. Our group contributed rice seedlings, investigating the role of microgravity on rice seedlings for further studies on photosynthetic physiology and proteomics. Our results indicate that microgravity condition causes reduction in photosystem I (PSI) activity in rice seedlings; and some side effects of the spaceflight conditions seem to have negative effects on PSI.

Quelle: Photochemistry and Photobiology | 6 Jun 2016 | 8:05 am CEST

Melatonin Mediates Monochromatic Light-induced Insulin-like Growth Factor 1 Secretion of Chick Liver: Involvement of Membrane Receptors

Abstract

Monochromatic lights influenced the proliferation and differentiation of skeletal satellite cells in broilers by the enhancement of insulin-like growth factor 1 (IGF-1) secretion. However, whether melatonin (MEL)-mediated monochromatic lights influenced the IGF-1 secretion remains unclear. Newly hatched broilers, including intact, sham operation and pinealectomy groups, were exposed to blue (BL), green (GL), red (RL) and white light (WL) from a light-emitting diode system for 14 days. The results showed that GL effectively promoted the secretion of MEL and IGF-1, the expression of proliferating cell nuclear antigen and MEL receptor subtypes Mel1a, Mel1b and Mel1c in the liver compared to BL and RL in vivo. Moreover, those was a positive correlation between MEL and IGF-1 (r = 0.834). After pinealectomy, however, these parameters declined, and there were no differences between GL and other monochromatic light treatments. In vitro, exogenous MEL increased hepatocyte proliferation and IGF-1 secretion. Meanwhile, the MEL enhancements were suppressed by prazosin (selective Mel1c antagonist), followed by luzindole (nonselective Mel1a/Mel1b antagonist), but not suppressed by 4-phenyl-2-propionamideotetralin (selective Mel1b antagonist). These findings demonstrated that MEL mediated the monochromatic light-induced secretion of IGF-1 in chicks’ livers by Mel1c and that Mel1a may be involved in this process.

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Monochromatic light affects the secretion of avian melatonin by acting on the pineal through the cranium. Melatonin influence the secretion of insulin-like growth factor 1 in hepatocyte through the membrane receptor pathway.

Quelle: Photochemistry and Photobiology | 6 Jun 2016 | 8:05 am CEST

Efficient Degradation of Aqueous Rhodamine B Irradiation Under Indoor Light Using a SiO2–Hypocrellin B Complex

Abstract

An efficient method for the degradation of the dye Rhodamine B (RhB) is reported. A SiO2–hypocrellin B (SiO2–HB) complex was found to work as a catalyst to degrade RhB in aqueous solution at room temperature and atmospheric pressure, over the pH range 1–10, under indoor light conditions. This method is capable of removing 82.68% of RhB within 20 min at pH 9. The SiO2–HB complex was characterized by both scanning electron microscopy and surface area analysis. The reaction progress was examined using ultrahigh pressure liquid chromatography/mass spectrometry and UV–visible spectroscopy. This process represents an efficient means of decontaminating dye-containing wastewaters in either highly acidic or weakly alkaline environments.

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The natural photosensitizer hypocrellin B (HB) was used to prepare a SiO2–HB catalyst to degrade wastewater by an impregnation method. The results demonstrate that the SiO2–HB complex is capable of rapidly degrading Rhodamine B (RhB) at room temperature and ambient atmospheric pressure in aqueous solutions with wide pH values ranging from 1 to 10, and under indoor light. And the SiO2–HB complex appears to be an efficient catalyst for the degradation of the model dye RhB in wastewater and can be separated easily.

Quelle: Photochemistry and Photobiology | 6 Jun 2016 | 8:05 am CEST

Chemiexcitation Efficiency of Intermolecular Electron-transfer Catalyzed Peroxide Decomposition Shows Low Sensitivity to Solvent-cavity Effects

Abstract

Intermolecular chemically initiated electron exchange luminescence (CIEEL) systems are known to possess low chemiluminescence efficiency; whereas, the corresponding intramolecular transformations are highly efficient. As the reasons for this discrepancy are not known, we report in this work our studies of the solvent-cavity effect on the efficiency of two intermolecular CIEEL systems, the catalyzed decomposition of diphenoyl peroxide and of a relatively stable 1,2-dioxetanone derivative, spiro-adamantyl-1,2-dioxetanone. The results indicate a very low medium viscosity effect on the quantum yields of these systems, a priori not compatible with these bimolecular transformations, showing also that their low efficiency cannot be due to solvent-cavity escape of intermediate radical ion pairs. In addition, the solvent-cage effect on the CIEEL efficiency, after the occurrence of the initial electron transfer, proved also to be very low, indicating the intrinsic low viscosity effect on the chemiexcitation step. Therefore, it is concluded that the low efficiency of these systems is intrinsic to the chemiexcitation step and cannot be improved by medium viscosity effects, being possibly due to sterical hindrance on charge-transfer complex formation in the initial step of the CIEEL.

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The low quantum yields determined in the rubrene and perylene catalyzed decomposition of diphenoyl peroxide and spiro-adamantyl-1,2-dioxetanone are not subject to significant solvent cavity effects in binary ethyl acetate/dibutyl phthalate mixtures, indicating that the low efficiency is not due to solvent cavity escape of intermediate radical pairs but might be caused by steric effects on the interaction between the peroxide and the catalyst.

Quelle: Photochemistry and Photobiology | 6 Jun 2016 | 8:05 am CEST

Aggregation induced enhanced emission of 2-(2[prime or minute]-hydroxyphenyl)benzimidazole

Photochem. Photobiol. Sci., 2016, 15,937-948
DOI: 10.1039/C6PP00122J, Paper
Ashim Malakar, Manishekhar Kumar, Anki Reddy, Himadree T. Biswal, Biman B. Mandal, G. Krishnamoorthy
Only cis-enol aggregates form microparticles and the hydroxyl group plays a vital role in the aggregation process. Proton transfer is an intramolecular process even in aggregates.
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Quelle: RSC - Photochem. Photobiol. Sci. latest articles | 6 Jun 2016 | 1:00 am CEST

Angelica archangelia Prevented Collagen Degradation by Blocking Production of Matrix Metalloproteinases in UVB-exposed Dermal Fibroblasts

Abstract

Angelica archangelia (AA), a traditional herb, has attracted attention as an agent with potential for use in the prevention of chronic skin diseases. This study examined the photoprotective effects of AA on the inhibition of matrix metalloproteinases (MMPs) and collagen degradation in UVB-irradiated normal human dermal fibroblasts. Our results showed that AA markedly blocked collagen degradation by restraining the production of MMPs in UVB-exposed fibroblasts. We also investigated the underlying mechanism behind the effects of AA. AA attenuated UVB-triggered interleukin-6 (IL-6) and promoted the expression of transforming growth factor β1. Application of AA extract (10, 100 μg mL−1) significantly diminished UVB-induced extracellular signal-regulated kinase and Jun-N-terminal kinase phosphorylation, which consequently reduced phosphorylated c-Fos and c-Jun. Our results indicated that AA inhibited the UVB-induced expression of MMPs by inhibiting mitogen-activated protein kinase signaling pathways and activator protein-1 activation. Our results suggest that AA is a promising botanical agent for use against skin photoaging.

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Solar ultraviolet radiation is mainly responsible for photoaging. UV-induced radical oxygen species (ROS) increase matrix metalloproteinase (MMPs) expression, which degrades collagen in the extracellular matrix (ECM). Angelica archangelia (AA) extract inhibited UVB-induced MMPs expression by inhibiting mitogen-activated protein kinase (MAPK) signaling pathways and activator protein-1 (AP-1) activation. Our results suggest that AA is a promising botanical agent for use against skin photoaging.

Quelle: Photochemistry and Photobiology | 3 Jun 2016 | 8:12 am CEST

Heterodimerization at the dye sensitized TiO2 surface: an efficient strategy toward quick removal of water contaminants

Photochem. Photobiol. Sci., 2016, 15,920-927
DOI: 10.1039/C6PP00071A, Paper
Zaki S. Seddigi, Saleh A. Ahmed, Samim Sardar, Samir Kumar Pal
Crucial dye sensitization of porous TiO2 MS for filtering pollutants through heterodimerization and their solar light mediated degradation via ROS are demonstrated.
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Quelle: RSC - Photochem. Photobiol. Sci. latest articles | 3 Jun 2016 | 1:00 am CEST

Photochemically-assisted synthesis and photophysical properties of difluoroboronated [small beta]-diketones with fused four-benzene-ring chromophores, chrysene and pyrene

Photochem. Photobiol. Sci., 2016, 15,928-936
DOI: 10.1039/C6PP00089D, Paper
Michitaka Mamiya, Yurie Suwa, Hideki Okamoto, Minoru Yamaji
We report synthesis and photophysical properties of difluoroboronated [small beta]-diketone complexes having chrysene and pyrene. Intense fluorescence is observable in solution and the solid state.
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Quelle: RSC - Photochem. Photobiol. Sci. latest articles | 3 Jun 2016 | 1:00 am CEST

Solvent-induced multicolour fluorescence of amino-substituted 2,3-naphthalimides studied by fluorescence and transient absorption measurements

Photochem. Photobiol. Sci., 2016, 15,842-850
DOI: 10.1039/C6PP00048G, Paper
Mayu Fujii, Misa Namba, Minoru Yamaji, Hideki Okamoto
Amino-substituted 2,3-naphthalimide derivatives showed marked positive solvatofluorochromism, and the fluorescence emission was effectively quenched in methanol via the internal conversion process.
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Quelle: RSC - Photochem. Photobiol. Sci. latest articles | 2 Jun 2016 | 1:00 am CEST

Ethylenediamine-modified graphene oxide covalently functionalized with a tetracarboxylic Zn(II) phthalocyanine hybrid for enhanced nonlinear optical properties

Photochem. Photobiol. Sci., 2016, 15,910-919
DOI: 10.1039/C6PP00063K, Paper
Zongle Li, Chunying He, Zhao Wang, Yachen Gao, Yongli Dong, Cheng Zhao, Zhimin Chen, Yiqun Wu, Weina Song
An investigation of the enhanced optical nonlinearity of ethylenediamine-modified graphene oxide covalently functionalized with a tetracarboxylic Zn(II) phthalocyanine.
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Quelle: RSC - Photochem. Photobiol. Sci. latest articles | 31 May 2016 | 1:00 am CEST

Repartition of oil miscible and water soluble UV filters in an applied sunscreen film determined by confocal Raman microspectroscopy

Photochem. Photobiol. Sci., 2016, 15,861-871
DOI: 10.1039/C6PP00024J, Paper
Myriam Sohn, Theodor Buehler, Georgios Imanidis
Repartition of UV filters responsible for sun protection in the sunscreen film upon application depends on the formulation of the sunscreen.
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Quelle: RSC - Photochem. Photobiol. Sci. latest articles | 25 May 2016 | 1:00 am CEST

Biospectroscopy, biospectrometry and imaging of Ilex paraguariensis. Basis for non-destructive quality evaluation using artificial vision

Photochem. Photobiol. Sci., 2016, 15,879-888
DOI: 10.1039/C6PP00054A, Paper
Tamara L. Parapugna, Gabriela Petroselli, Rosa Erra-Basells, M. Gabriela Lagorio
Optical indicators related to the nutraceutical content derived from fluorescence, reflectance and imaging of Ilex paraguariensis have been developed. The results are complemented with mass spectrometry analysis.
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Quelle: RSC - Photochem. Photobiol. Sci. latest articles | 25 May 2016 | 1:00 am CEST

Chemical quenching of singlet oxygen by betanin

Photochem. Photobiol. Sci., 2016, 15,872-878
DOI: 10.1039/C6PP00037A, Paper
Monika Wendel, Stanislaw Nizinski, Mateusz Gierszewski, Dorota Prukala, Marek Sikorski, Karolina Starzak, Slawomir Wybraniec, Gotard Burdzinski
Singlet oxygen produced upon UV excitation of perinaphthenone in D2O leads to oxidation of betanin.
The content of this RSS Feed (c) The Royal Society of Chemistry

Quelle: RSC - Photochem. Photobiol. Sci. latest articles | 24 May 2016 | 1:00 am CEST

Experimental evidence of incomplete fluorescence quenching of pyrene bound to humic substances: implications for Koc measurements

Photochem. Photobiol. Sci., 2016, 15,889-895
DOI: 10.1039/C6PP00052E, Paper
E. A. Shirshin, G. S. Budylin, N. Yu. Grechischeva, V. V. Fadeev, I. V. Perminova
Fluorescence quenching (FQ) is extensively used for quantitative assessment of partition coefficients (KOC) of polycyclic aromatic hydrocarbons (PAHs) to natural organic materials - humic substances (HS).
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Quelle: RSC - Photochem. Photobiol. Sci. latest articles | 24 May 2016 | 1:00 am CEST

The action spectrum for vitamin D3: initial skin reaction and prolonged exposure

Photochem. Photobiol. Sci., 2016, 15,896-909
DOI: 10.1039/C6PP00034G, Paper
Arjan van Dijk, Peter den Outer, Henk van Kranen, Harry Slaper
The action spectrum concept for vitamin D photosynthesis in skin is assessed for prolonged exposure, including side- and return-reactions. A generalized expression for the action spectrum is presented. Production estimates per erythemal dose are given.
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Quelle: RSC - Photochem. Photobiol. Sci. latest articles | 24 May 2016 | 1:00 am CEST

Coaxial Electrospinning Method for the Preparation of TiO2@CdS/PVA Composite Nanofiber Mat and Investigation on its Photodegradation Catalysis

Abstract

TiO2/PVA composite nanofiber mat was prepared via an electrospinning technology. SH-TiO2-SiO2 hybrid particles and PVA solution were injected through a coaxial syringe, yielding a composite nanofiber mat. The as-prepared SH-TiO2-SiO2/PVA composite nanofiber mat was immersed in Cd2+ cation solution and S2− anion solution in turn. Thus, yellow TiO2@CdS/PVA composite nanofiber mats were prepared. By adjusting the number of times a mat was immersed in the Cd2+ and S2− solutions, different amounts of CdS particles attaching to the mats were obtained. Both SH-TiO2-SiO2/PVA and TiO2@CdS/PVA composite nanofiber mats were employed to catalyze the photodegradation of a model dye, methylene blue. The photodegradation performance could be greatly enhanced by the introduction of CdS particles anchoring onto TiO2 particles. The photodegradation efficiency reached 99.2% within 180 min. Also, the nanofiber mat could be recycled and reused at least 10 times. The photodegradation efficiency of TiO2@CdS/PVA composite nanofiber mats remained 68.8% for 10 cycles.

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A TiO2/PVA composite nanofiber mat was prepared first, and then the mat was immersed in Cd2+ and S2− solutions to obtain a TiO2@CdS/PVA composite nanofiber mat. The as-prepared mat exhibited excellent photodegradation ability for a model dye, methylene blue.

Quelle: Photochemistry and Photobiology | 18 May 2016 | 10:26 am CEST

Promotion of Proapoptotic Signals by Lysosomal Photodamage: Mechanistic Aspects and Influence of Autophagy

Abstract

Prior studies demonstrated that a low level (LD10–15) of lysosomal photodamage can sensitize cells to the apoptotic death that results from subsequent mitochondrial photodamage. We have proposed that this process occurs via a calpain-catalyzed cleavage of the autophagy-associated protein ATG5 to form a proapoptotic fragment. In this report, we provide evidence for the postulated ATG5 cleavage and show that the sequential photodynamic therapy (PDT) protocol can also partly overcome the adverse effect of hypoxia on the initiation of apoptosis. While autophagy can offer cytoprotection after mitochondrial photodamage, this does not appear to apply when lysosomes are the target. This may account for the ability of very low PDT doses directed at lysosomes to evoke ATG5 cleavage. The resulting proapoptotic effect overcomes intrinsic cytoprotection from mitochondrial photodamage along with a further stimulation of phototoxicity.

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Scheme whereby release of calcium from photodamaged lysosomes activates calpain. This enzyme then catalyzes activation of calpain. This enzyme then cleaves the autophagy-associated protein ATG5 to a truncated form that potentiates the initiation of apoptotic death after a subsequent PDT dose directed at mitochondria. The net result is substantially enhanced photokilling that can circumvent suboptimal delivery of light and oxygen.

Quelle: Photochemistry and Photobiology | 18 May 2016 | 10:25 am CEST

The preventive effect of linalool on acute and chronic UVB-mediated skin carcinogenesis in Swiss albino mice

Photochem. Photobiol. Sci., 2016, 15,851-860
DOI: 10.1039/C6PP00075D, Paper
Srithar Gunaseelan, Agilan Balupillai, Kanimozhi Govindasamy, Ganesan Muthusamy, Karthikeyan Ramasamy, Mohana Shanmugam, N. Rajendra Prasad
Acute UVB-exposure induces erythema and edema. Repeated UVB-exposure causes chronic inflammation and mutated p53 expression which leads to carcinogenesis. Linalool through its (i) sunscreen effect, (ii) modulation of NF-[small kappa]B signaling and (iii) apoptotic signaling prevents photocarcinogenesis.
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Quelle: RSC - Photochem. Photobiol. Sci. latest articles | 18 May 2016 | 1:00 am CEST




 


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