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Rose Bengal (rose + bengal)
Terms modified by Rose Bengal Selected AbstractsInduction of bilateral plasticity in sensory cortical maps by small unilateral cortical infarcts in ratsEUROPEAN JOURNAL OF NEUROSCIENCE, Issue 3 2003S. Reinecke Abstract Behavioural impairments caused by brain lesions show a considerable, though often incomplete, recovery. It is hypothesized that cortical and subcortical plasticity of sensory representations contribute to this recovery. In the hindpaw representation of somatosensory cortex of adult rats we investigated the effects of focal unilateral cortical lesions on remote areas. Cortical lesions with a diameter of ,,2 mm were induced in the parietal cortex by photothrombosis with the photosensitive dye Rose Bengal. Subsequently, animals were kept in standard cages for 7 days. On day seven, animals were anaesthetized and cutaneous receptive fields in the cortical hindpaw representations ipsi- and contralateral to the lesion were constructed from extracellular recordings of neurons in layer IV using glass microelectrodes. Receptive fields in the lesioned animals were compared to receptive fields measured in nonlesioned animals serving as controls. Quantitative analysis of receptive fields revealed a significant increase in size in the lesioned animals. This doubling in receptive field size was observed equally in the hemispheres ipsi- and contralateral to the lesion. The results indicate that the functional consequences of restricted cortical lesions are not limited to the area surrounding the lesion, but affect the cortical maps on the contralateral, nonlesioned hemisphere. [source] Aegyptin displays high-affinity for the von Willebrand factor binding site (RGQOGVMGF) in collagen and inhibits carotid thrombus formation in vivoFEBS JOURNAL, Issue 2 2010Eric Calvo Aegyptin is a 30 kDa mosquito salivary gland protein that binds to collagen and inhibits platelet aggregation. We have studied the biophysical properties of aegyptin and its mechanism of action. Light-scattering plot showed that aegyptin has an elongated monomeric form, which explains the apparent molecular mass of 110 kDa estimated by gel-filtration chromatography. Surface plasmon resonance identified the sequence RGQOGVMGF (where O is hydroxyproline) that mediates collagen interaction with von Willebrand factor (vWF) as a high-affinity binding site for aegyptin, with a KD of approximately 5 nm. Additionally, aegyptin interacts with the linear peptide RGQPGVMGF and heat-denatured collagen, indicating that the triple helix and hydroxyproline are not a prerequisite for binding. However, aegyptin does not interact with scrambled RGQPGVMGF peptide. Aegyptin also recognizes the peptides (GPO)10 and GFOGER with low affinity (,m range), which respectively represent glycoprotein VI and integrin ,2,1 binding sites in collagen. Truncated forms of aegyptin were engineered, and the C-terminus fragment was shown to interact with collagen and to attenuate platelet aggregation. In addition, aegyptin prevents laser-induced carotid thrombus formation in the presence of Rose Bengal in vivo, without significant bleeding in rats. In conclusion, aegyptin interacts with distinct binding sites in collagen, and is useful tool to inhibit platelet,collagen interaction in vitro and in vivo. Structured digital abstract ,,MINT-7299280, MINT-7299290: Collagen (uniprotkb:P02461) binds (MI:0407) to Aegyptin (uniprotkb:O01949) by enzyme linked immunosorbent assay (MI:0411) ,,MINT-7298991, MINT-7299153, MINT-7299208: Collagen (uniprotkb:P02452) binds (MI:0407) to Aegyptin (uniprotkb:O01949) by surface plasmon resonance (MI:0107) ,,MINT-7299266: Collagen (uniprotkb:P02452) binds (MI:0407) to Aegyptin (uniprotkb:O01949) by fluorescence microscopy (MI:0416) ,,MINT-7299256: Collagen (uniprotkb:P02452) binds (MI:0407) to Aegyptin (uniprotkb:O01949) by solid phase assay (MI:0892) [source] Surveys for Beet Necrotic Yellow Vein Virus (the Cause of Rhizomania), other Viruses, and Soil-borne Fungi Infecting Sugar Beet in SyriaJOURNAL OF PHYTOPATHOLOGY, Issue 11-12 2002A. M. Mouhanna Abstract Production of sugar beet, the most important source of sugar in Syria, has suffered from many problems in the past, especially from diseases. No previous surveys have been made in Syria for viral diseases and soil-borne fungi of sugar beet. In 1998, samples were collected from plants showing symptoms of virus infection (yellowing, wilting, necrosis and mosaic). Root samples (341) were collected from crops of autumn-sown seed from 115 localities in seven provinces, 173 root samples from spring-sown crops and 39 leaf samples were collected during both seasons. The root samples were tested for the presence of viruses by double antibody sandwich-enzyme-linked immunosorbent assay (ELISA) and triple antibody sandwich-ELISA, and for soil-borne fungi by red plate (Rose Bengal) dishes. We have shown for the first time the presence of Beet necrotic yellow vein virus, Beet soil-borne virus, Beet yellows virus and Beet mild yellowing virus in Syrian sugar beet fields in which Rhizoctonia sp. and Fusarium sp. were also widely distributed. [source] Optical probing and imaging of live cells using SERS labelsJOURNAL OF RAMAN SPECTROSCOPY, Issue 1 2009Janina Kneipp Abstract During surface-enhanced Raman scattering (SERS), molecules exhibit a significant increase in their Raman signals when attached, or in very close vicinity, to gold or silver nanostructures. This effect is exploited as the basis of a new class of optical labels. Here we demonstrate robust and sensitive SERS labels as probes for imaging live cells. These hybrid labels consist of gold nanoparticles with Rose Bengal or Crystal Violet attached as reporter molecules. These new labels are stable and nontoxic, do not suffer from photobleaching, and can be excited at any excitation wavelength, even in the near infrared. SERS labels can be detected and imaged through the specific Raman signatures of the reporters. In addition, surface-enhanced Raman spectroscopy in the local optical fields of the gold nanoparticles also provides sensitive information on the immediate molecular environment of the label in the cell and allows imaging of the native constituents of the cell. This is demonstrated by images based on a characteristic Raman line of the reporter as well as by displaying lipids based on the SERS signal of the CH deformation/bending modes at ,1470 cm,1. Copyright © 2008 John Wiley & Sons, Ltd. [source] Reactive oxygen species stimulate homologous recombination in plantsPLANT CELL & ENVIRONMENT, Issue 9 2003I. KOVALCHUK ABSTRACT Coping with the continuous production of free radicals is a daily routine of the cell. Despite their toxicity, the reactive oxygen species (ROS) are involved in dual physiological action , signal transduction and immune response. We analysed the influence of oxidative stress-generating compounds, rose Bengal (RB), paraquat (PQ) and amino-triazole (ATZ) on the genome stability of Arabidopsis using transgenic recombination-monitoring plants. Homologous recombination frequencies in plants were increased upon the treatment with RB and PQ but not ATZ. Application of the N -acetyl- L -cysteine (NAC), radicals scavenging compound, decreased the DNA damage caused by RB. Interestingly, the incubation of plants with very low concentration of RB (less than 0.2 µM) led to the subsequent increase in plant tolerance to methyl methane sulfonate (MMS): stronger plants with a lower increase of homologous recombination frequency. In contrast, the incubation of plants with 0.5 µM of RB resulted in the potentiation of the MMS effect: the weaker plants with higher frequency of recombination. The data of the present study suggest the existence of a dual concentration-dependent role of ROS in plants. [source] Systemic plant signal triggers genome instabilityTHE PLANT JOURNAL, Issue 1 2004Jody Filkowski Summary Previously, we have shown that infection of tobacco plants with a viral pathogen triggers local and systemic induction of homologous recombination (HR). Here, we have tested the hypothesis of whether free radicals are potentially involved in the induction of the systemic effect. We report a significant induction of HR in tobacco plants treated with radical-generating agents, UVC or rose Bengal (RB). Importantly, the recombination increase was observed in local (treated) as well as systemic (non-treated) tissue. The systemic increase in recombination implies the existence of a signal that is transmitted to non-treated tissue. Several sets of grafting experiments proved the generation of said signal by both RB and UVC exposure. A statistically significant increase in HR was observed in tissue that received a systemic signal via a grafted leaf. Similar data were obtained from transgenic plants naphthalene degrading salicylate 1-hydroxylase (NahG) unable to accumulate salicylic acid (SA). Interestingly, pre-treatment of plants with the radical-scavenging compound N -acetyl- l -cysteine (NAC) led to a significantly lower recombination increase upon grafting after treatment with UVC and RB. Moreover, leaves taken for grafting from NAC-pre-treated plants exhibited a lower level of oxidized organic compounds. Our data suggest the involvement of free radical production in either generation or maintenance of the recombination signal. We discuss potential mechanisms for generation of the signal and possible adaptive advantages of enhanced genomic flexibility following exposure to DNA-damaging agents. [source] Screening Xanthene Dyes for Visible Light-Driven Nicotinamide Adenine Dinucleotide Regeneration and Photoenzymatic SynthesisADVANCED SYNTHESIS & CATALYSIS (PREVIOUSLY: JOURNAL FUER PRAKTISCHE CHEMIE), Issue 16 2009Sahng Ha Lee Abstract Regeneration of the nicotinamide cofactor is a critical issue in biocatalysis. Herein we have screened xanthene dyes for a highly efficient, visible light-driven photochemical regeneration of cofactors and enzymatic synthesis. Superior catalytic performance was observed with several xanthene dyes such as phloxine B, erythrosine B, eosin Y, and rose bengal. We found that the photo- and electrochemical properties of the xanthene dyes were affected by the halogen atom substitution, which is a key factor in the efficient light-induced electron transfer from the donor molecule to the catalytic mediator. [source] Photoprotection by Porcine Eumelanin Against Singlet Oxygen Production,PHOTOCHEMISTRY & PHOTOBIOLOGY, Issue 3 2008Alice Wang Melanin, a major pigment found in retinal pigment epithelium (RPE) cells, is considered to function in dual roles, one protective and one destructive. By quenching free radical species and reactive oxygen species (ROS) melanin counteracts harmful redox stress. However, melanin is also thought to be capable of creating ROS. In this destructive role, melanin increases redox strain in the cell. This study uses readily available eumelanin extracted from porcine RPE cells as a more authentic model than synthetic melanin to determine specific mechanisms of melanin activity with regard to singlet oxygen in the presence and absence of rose bengal, a singlet-oxygen photosensitizer. Optical detection of singlet-oxygen was determined by monitoring the bleaching of p -nitrosodimethylaniline in the presence of histidine. Production of singlet oxygen in aqueous oxygen-saturated solutions of rose bengal without eumelanin was readily accomplished. In contrast, detection of singlet oxygen in oxygen-saturated solutions of eumelanin without rose bengal failed, consistent with results of others. However, a significant decrease in singlet oxygen production by rose bengal was observed in the presence of eumelanin. After correction for light absorption and chemical bleaching of eumelanin, the results show that eumelanin also provides a photoprotective mode arising from chemistry, that is, not just the physical process of light absorption followed by energy dissipation as heat. [source] Spatial Distribution of Protein Damage by Singlet Oxygen in KeratinocytesPHOTOCHEMISTRY & PHOTOBIOLOGY, Issue 1 2008Yu-Ying He Singlet oxygen may be generated in cells by either endogenous or exogenous photosensitizers as a result of exposure to UV or visible irradiation. We have used immuno-spin trapping (Free Radic. Biol. Med. 36: 1214, 2004) to identify the subcellular targets of singlet oxygen generated by rose bengal (RB). Confocal fluorescence microscopy of HaCaT keratinocytes incubated with RB clearly showed that the dye entered the cells and was located mainly in the perinuclear region, probably associated with the Golgi apparatus and endoplasmic reticulum. Previous studies by Wright et al. (Free Radic. Biol. Med.34: 637, 2003) have shown that long-lived protein hydroperoxides (POOH) are present in cells exposed to singlet oxygen-generating dyes. The addition of reducing metal ions such as Cu+ to POOH results in the generation of protein-derived radicals, POO, and PO,, which react with the spin trap 5,5-dimethyl-1-pyrroline N -oxide (DMPO) to give relatively stable spin adducts. In order to determine the subcellular localization of the protein-DMPO adducts, we exposed keratinocytes to RB/light exposure and then incubated the cells with Cu+ and DMPO. After staining with antibody against DMPO followed by a secondary Alexa Fluor 488 goat anti-rabbit IgG, the intracellular distribution of protein-DMPO adducts was determined by confocal microscopy. The subcellular localization of the protein DMPO adducts was coincident with that of RB. This approach may provide information on the spatial distribution of singlet oxygen generated in cells. [source] Sensitized Photooxidation of Thyroidal Hormones.PHOTOCHEMISTRY & PHOTOBIOLOGY, Issue 2 2005Evidence for Heavy Atom Effect on Singlet Molecular Oxygen [O2(, g)]-mediated Photoreactions ABSTRACT Thyronine derivatives are essential indicators of thyroid gland diseases in clinical diagnosis and are currently used as standards for developing ordinary biochemical assays. Photooxidation of gland hormones of the thyronine (TN) family and structurally related compounds (TN, 3,5-diiodo-thyronine,3,3,,5-triiodothyronine and 3,3,,5,5,-tetraiodothyronine or thyroxine) was studied using rose bengal, eosin and perinaphthenone (PN) as dye sensitizers. Tyrosine (Tyr) and two iodinated derivatives (3-iodotyrosine and 3,5-diiodotyrosine) were also included in the study for comparative purposes. Irradiation of aqueous solutions of substrates containing xanthene dyes with visible light triggers a complex series of competitive interactions, which include the triplet excited state of the dye (3Xdye*) and singlet molecular oxygen [O2(1,g)]-mediated and superoxide ion-mediated reactions. Rate constants for interaction with the 3Xdye*, attributed to an electron transfer process, are in the order of 108 -109M,1 s,1 depending on the dye and the particular substrate. The photosensitization using PN follows a pure Type-II (O2(1,g) mediated) mechanism. The presence of the phenolic group in Tyr, TN and iodinated derivatives dominates the kinetics of photooxidation of these compounds. The reactive rate constants, kr, and the quotient between reactive and overall rate constants (krlkt values, in the range of 0.7,0.06) behave in an opposite fashion compared with the overall rate constants and oxidation potentials. This apparent inconsistency was interpreted on the basis of an internal heavy atom effect, favoring the intersystem-crossing deactivation route within the encounter complex with the concomitant reduction of effective photooxidation. [source] Cationic Dye,sensitized Degradation of Sodium Hyaluronate Through Photoinduced Electron Transfer in the Upper Excited State,PHOTOCHEMISTRY & PHOTOBIOLOGY, Issue 3 2001Masanobu Kojima ABSTRACT The formation of ground-state complexes of methylene blue (MB) and thionine (TN) with sodium hyaluronate (NaHA) was clearly observed by means of absorption spectra in aqueous solution. Irradiation of the complexes using 313 nm light caused significant degradation of NaHA under oxygen and argon. However, the use of visible light over 400 nm, which gives the lowest excited singlet state of the cationic dyes, caused no degradation. MB and TN were more efficient sensitizers for the degradation of NaHA than rose bengal (RB), although RB is a more efficient singlet oxygen (1O2) sensitizer than the cationic dyes. Under similar conditions the polysaccharides with carboxyl groups, such as alginic acid and polygalacturonic acid, also photodecomposed. However, the polysaccharides without carboxyl groups, such as pullulan and methyl cellulose, did not. The irradiation of the polysaccharides in the presence of powdered titanium dioxide as a photocatalyst to generate the hydroxyl radical (·OH) in aerated aqueous solution caused the fragmentation of all the polymers. It was confirmed that methyl viologen, an electron-accepting sensitizer, formed a charge-transfer complex with NaHA, the irradiation of which caused the efficient degradation of NaHA. In the presence of ,- and ,-cyclodextrins the MB- and TN-sensitized photodegradation of NaHA was markedly suppressed. This was probably due to the formation of the inclusion complexes comprising the cationic dyes and the cyclodextrins. On the basis of the results obtained we propose that the cationic dye,sensitized degradation of NaHA involves a photoinduced electron-transfer process between the upper excited dyes and the ground-state NaHA and that ·OH and 1O2 do not participate in the degradation. [source] Singlet Oxygen, but not Oxidizing Radicals, Induces Apoptosis in HL-60 Cells,PHOTOCHEMISTRY & PHOTOBIOLOGY, Issue 4 2000Irene E. Kochevar ABSTRACT Oxidizing species (OS), produced by photosensitization or derived from cytotoxic agents, activate apoptotic pathways. We investigated whether two different OS, formed at the same subcellular sites, have equivalent ability to initiate apoptosis in HL-60 cells. Our previous work showed that absorption of visible light by rose bengal (RB) produces singlet oxygen exclusively, whereas absorption of ultraviolet A produces RB-derived radicals in addition to singlet oxygen. Singlet oxygen, but not the RB-derived radicals, induced nuclear condensation and DNA fragmentation into nucleosome-size fragments in a dose dependent manner. In contrast, the RB-derived radicals caused greater lipid oxidation than singlet oxygen. These results indicate that different OS, produced at the same subcellular sites, do not have the same ability to induce apoptosis and that the ability of an OS to initiate lipid oxidation does not necessarily correlate with its ability to induce apoptosis. [source] Photooxidations of phenol, cyclopentadiene and citronellol with photosensitizers ionically bound at a polymeric ion exchanger,POLYMERS FOR ADVANCED TECHNOLOGIES, Issue 3-4 2001Robert Gerdes Abstract Different metal tetrasulfophthalocyanines and rose bengal were employed as photosensitizers in the photooxidation of phenol, cyclopentadiene and (S)-(,)-citronellol. Ionically polymer bound photosensitizers were easily obtained by the reaction of negatively charged low-molecular-weight phthalocyanines with the strong basic anion exchanger Amberlite® IRA 400. The activities of the low-molecular-weight and the polymer systems are compared. Especially immobilized phthalocyanines which exhibit the advantages of good activity, as well as stability against photobleaching, and can be used repeatedly. Copyright © 2001 John Wiley & Sons, Ltd. [source] 2433: A revolutionary hypothesis to explain Marx's line and progressive disease at the lid marginACTA OPHTHALMOLOGICA, Issue 2010AJ BRON Purpose The conjunctiva of the lid margin is protected from direct exposure to the atmosphere, by the tear meniscus. We examine the pathophysiological consequences of evaporation from this compartment. Methods A consideration of empirical data. Results The concave meniscus thins progressively to the point where it is pinned at the mucocutaneous junction (MCJ). We predict that, as a result, over the interblink period, evaporation generates a solute gradient which peaks behind the MCJ and is amplified over multiple cycles of the blink. We hypothesise that this creates a hyperosmolar state here which: i. stresses epithelial cells behind the MCJ, ii. stimulates a high cell turnover and iii. leads to immaturity of the surface cells and their glycocalyx. This is considered to explain an increased permeability to dyes at this site (rose bengal, lissamine green and fluorescein) and the stainability with dyes which is termed Marx's line. This gradient mechanism could also concentrate proteins, such as inflammatory mediators, at this location. Conclusion Since Marx's line lies directly behind the terminal Meibomian ducts and acini, chronic stress in this region is further invoked to explain forward migration of Marx's line and the MCJ which occurs with age and the induction of primary Meibomian gland dysfunction. Arguments are put forward to explain how this mechanism might be accentuated in dry eye and how the globe might be protected from this gradient effect in the region of the ,black line', where the tear film is segregated from the meniscus after the blink. Factors pro and con the hypothesis are discussed. [source] | |||||||||||||