bluuebunny/crossref_metadata_2025_split huggingface dataset:
Control of DNA Hybridization with Photocleavable Adducts¶
Authors: Ghosn Bilal , Haselton Frederick R. , Gee Kyle R. , Monroe W. Todd 
Published: July 2010

ABSTRACTPrevious 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

ABSTRACTNew 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

ABSTRACTRecent 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

ABSTRACTAromatic 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

ABSTRACTEumelanosomes 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

ABSTRACTFormulations 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

ABSTRACT31‐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

ABSTRACTUnderstanding 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

ABSTRACTA 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

AbstractThis 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

ABSTRACTWe 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

AbstractOver 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

ABSTRACTInterleukin 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.
Effect of UV Radiation on the Neonatal Skin Immune System— Implications for Melanoma†
Authors: Muller H. Konrad , Malley Roslyn C. , McGee Heather M. , Scott Deborah K. , Wozniak Teresa , Woods Gregory M. 
Published: July 2010

ABSTRACTThe neonatal immune environment and the events that occur during this time have profound effects for the adult period. While protective immune responses can develop, the neonatal immune system, particularly the skin immune system (SIS), tends to promote tolerance. With this information we undertook a number of studies to identify unique aspects of skin during the neonatal period. Proteomics revealed proteins uniquely expressed in neonatal, but not adult, skin (e.g. Stefin A, peroxiredoxins) and these may have implications in the development of SIS. Vitamin D was found to have a modulating role on SIS and this was apparent from the early neonatal period. Exposure of the neonatal skin to UV radiation altered the microenvironment resulting in the generation of regulatory T cells, which persisted in adult life. As the development of UV radiation‐induced melanoma can occur following a single high dose (equivalent to burning in adults) to transgenic mice (hepatocyte growth factor/scatter factor or TPras) during the neonatal period, the early modulating events which lead to suppression may be relevant for the development of UV radiation‐induced human melanoma. Any attempt to produce effective melanoma immunotherapy has to accommodate and overcome these barriers. Margaret Kripke’s pioneering work on UV‐induced immunosuppression still remains central to the understanding of the development of melanoma and how it frequently escapes the immune system.
Cloning-Independent Expression and Analysis of ω-Transaminases by Use of a Cell-Free Protein Synthesis System
Authors: Kwon Yong-Chan , Lee Kyung-Ho , Kim Ho-Cheol , Han Kyuboem , Seo Joo-Hyun , Kim Byung-Gee , Kim Dong-Myung 
Published: July 2010

ABSTRACT
Herewith we report the expression and screening of microbial enzymes without involving cloning procedures. Computationally predicted putative ω-transaminase (ω-TA) genes were PCR amplified from the bacterial colonies and expressed in a cell-free protein synthesis system for subsequent analysis of their enzymatic activity and substrate specificity. Through the cell-free expression analysis of the putative ω-TA genes, a number of enzyme-substrate pairs were identified in a matter of hours. We expect that the proposed strategy will provide a universal platform for bridging the information gap between nucleotide sequence and protein function to accelerate the discovery of novel enzymes.
Identification of a Novel Class of Membrane-Bound [NiFe]-Hydrogenases in
Thermococcus onnurineus
NA1 by
In Silico
Analysis
Authors: Lim Jae Kyu , Kang Sung Gyun , Lebedinsky Alexander V. , Lee Jung-Hyun , Lee Hyun Sook 
Published: July 2010

ABSTRACT

In silico
analysis of group 4 [NiFe]-hydrogenases from a hyperthermophilic archaeon,
Thermococcus onnurineus
NA1, revealed a novel tripartite gene cluster consisting of dehydrogenase-hydrogenase-cation/proton antiporter subunits, which may be classified as the new subgroup 4b of [NiFe]-hydrogenases-based on sequence motifs.
2-Haloacrylate Hydratase, a New Class of Flavoenzyme That Catalyzes the Addition of Water to the Substrate for Dehalogenation
Authors: Mowafy Amr M. , Kurihara Tatsuo , Kurata Atsushi , Uemura Tadashi , Esaki Nobuyoshi 
Published: July 2010

ABSTRACT

Enzymes catalyzing the conversion of organohalogen compounds are useful in the chemical industry and environmental technology. Here we report the occurrence of a new reduced flavin adenine dinucleotide (FAD) (FADH
2
)-dependent enzyme that catalyzes the removal of a halogen atom from an unsaturated aliphatic organohalogen compound by the addition of a water molecule to the substrate. A soil bacterium,
Pseudomonas
sp. strain YL, inducibly produced a protein named Caa67
YL
when the cells were grown on 2-chloroacrylate (2-CAA). The
caa67
YL
gene encoded a protein of 547 amino acid residues (
M
r
of 59,301), which shared weak but significant sequence similarity with various flavoenzymes and contained a nucleotide-binding motif. We found that 2-CAA is converted into pyruvate when the reaction was carried out with purified Caa67
YL
in the presence of FAD and a reducing agent [NAD(P)H or sodium dithionite] under anaerobic conditions. The reducing agent was not stoichiometrically consumed during this reaction, suggesting that FADH
2
is conserved by regeneration in the catalytic cycle. When the reaction was carried out in the presence of H
2
18
O, [
18
O]pyruvate was produced. These results indicate that Caa67
YL
catalyzes the hydration of 2-CAA to form 2-chloro-2-hydroxypropionate, which is chemically unstable and probably spontaneously dechlorinated to form pyruvate. 2-Bromoacrylate, but not other 2-CAA analogs such as acrylate and methacrylate, served as the substrate of Caa67
YL
. Thus, we named this new enzyme 2-haloacrylate hydratase. The enzyme is very unusual in that it requires the reduced form of FAD for hydration, which involves no net change in the redox state of the coenzyme or substrate.