The Experts below are selected from a list of 309 Experts worldwide ranked by ideXlab platform
Stenbjörn Styring - One of the best experts on this subject based on the ideXlab platform.
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the role of cytochrome b559 and tyrosined in protection against photoinhibition during in vivo Photoactivation of photosystem ii
Biochimica et Biophysica Acta, 1999Co-Authors: Ann Magnuson, Fikret Mamedov, Maria Rova, Perolof Fredriksson, Stenbjörn StyringAbstract:The role of cytochrome b559 and tyrosineD in protection against photoinhibition during in vivo Photoactivation of Photosystem II
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changes in the oxidation state of cytochrome b559 and tyrosine d during in vivo Photoactivation of photosystem ii
11th Photosynthesis Congress, 1998Co-Authors: Ann Magnusson, Fikret Mamedov, Maria Rova, Perolof Fredriksson, Stenbjörn StyringAbstract:Changes in the oxidation state of cytochrome b559 and tyrosine-D during in vivo Photoactivation of photosystem II
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Photoactivation and Photoinhibition Are Competing in a Mutant of Chlamydomonas reinhardtii Lacking the 23-kDa Extrinsic Subunit of Photosystem II
The Journal of biological chemistry, 1996Co-Authors: E. Maria Rova, Birgitta Mc Ewen, Perolof Fredriksson, Stenbjörn StyringAbstract:Abstract The process of Photoactivation has been studied in dark grown cells of Chlamydomonas reinhardtii. A mutant, FUD 39, lacking the Cl−-concentrating 23-kDa psbP protein of photosystem II was found to have a decreased capability to perform Photoactivation. The yield of the process never reached wild type level, and contrary to the wild type, it was highly dependent on the intensity of the activating light, with a very narrow optimum around 1 μE m−2 s−1. The different behavior in the mutant can be explained by a requirement for a longer dark period, between the two photoacts, during the Photoactivation. This is proposed to reflect the decreased Cl− affinity in the mutant. Photoactivation in the mutant was also found to be very sensitive to competing photoinhibitory processes. The inhibition was located to the donor side of photosystem II and affected the Photoactivation capability before electron transfer from Tyrz was inhibited. We propose an extended model for Photoactivation in which an intermediate that is sensitive to photoinhibition is formed if Cl− is not functionally bound to the manganese cluster.
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Photoactivation and photoinhibition of photosystem II in a mutant of Chlamydomonas reinhardtii lacking the 23 kDa extrinsic subunit
1995Co-Authors: Maria Rova, Perolof Fredriksson, Birgitta Mc Ewen, Stenbjörn StyringAbstract:Photoactivation and photoinhibition of photosystem II in a mutant of Chlamydomonas reinhardtii lacking the 23 kDa extrinsic subunit
Jonathan Silver - One of the best experts on this subject based on the ideXlab platform.
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Photoactivation of quantum dot fluorescence following endocytosis.
Nano letters, 2005Co-Authors: Jonathan SilverAbstract:We studied the fluorescence of quantum dots in cells. Coating quantum dots with cationic peptides caused them to be endocytosed and transported to lysosomes. After overnight incubation, their fluorescence apparently dimmed but became markedly “photoactivatable”, increasing more than 3-fold within minutes on exposure to bright light, and decaying over hours in the dark. Photoactivation was greater in the presence of water than ethanol, and UV illumination compensated for lack of water during Photoactivation. Dimming and Photoactivation could affect the use of quantum dots as quantitative probes in vivo and lead to new uses, such as tracking molecular movement.
Mario Alexandre Coelho Sinhoreti - One of the best experts on this subject based on the ideXlab platform.
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Influence of Photoactivation method and mold for restoration on the Knoop hardness of resin composite restorations
Lasers in Medical Science, 2013Co-Authors: William Cunha Brandt, Eduardo Jose Carvalho Souza-junior, Laís Regiane Da Silva-concílio, Ana Christina Claro Neves, Mario Alexandre Coelho SinhoretiAbstract:The aim of this study was to evaluate in vitro the Knoop hardness in the top and bottom of composite photo activated by different methods when different mold materials were used. Z250 (3M ESPE) and XL2500 halogen unit (3M ESPE) were used. For hardness test, conical restorations were made in extracted bovine incisors (tooth mold) and also metal mold (approximately 2 mm top diameter × 1.5 mm bottom diameter × 2 mm in height). Different Photoactivation methods were tested: high-intensity continuous (HIC), low-intensity continuous (LIC), soft-start, or pulse-delay (PD), with constant radiant exposure. Knoop readings were performed on top and bottom restoration surfaces. Data were submitted to two-way ANOVA and Tukey’s test ( p = 0.05). On the top, regardless of the mold used, no significant difference in the Knoop hardness (Knoop hardness number, in kilograms–force per square millimeter) was observed between the Photoactivation methods. On the bottom surface, the Photoactivation method HIC shows higher means of hardness than LIC when tooth and metal were used. Significant differences of hardness on the top and in the bottom were detected between tooth and metal. The Photoactivation method LIC and the material mold can interfere in the hardness values of composite restorations.
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influence of the light curing unit and thickness of residual dentin on generation of heat during composite Photoactivation
Journal of Oral Science, 2008Co-Authors: Ricardo Danil Guiraldo, Mario Alexandre Coelho Sinhoreti, Luis Felipe Jochims Schneider, Simonides Consani, Thais Lympius, Lourenco CorrersobrinhoAbstract:The aim of this study was to determine the effect of different types of composites (Filtek Z250, Esthet X and Filtek Supreme) and dentin thicknesses (0.5 or 1.0 mm) on the generation of heat during Photoactivation by QTH (conventional halogen light), LED (light emitting diode), and PAC (xenon plasma light) light-curing units. Temperature changes were recorded with a thermocouple type K connected to a digital thermometer. Twenty chemically polymerized acrylic resin bases were prepared in order to guide the thermocouple and to support the dentin disks. On the acrylic resin base, elastomer molds of 2.0-mm thickness were adapted. The temperature increase was measured after composite Photoactivation and the matrix was stored at 37°C. After 24 hours, Photoactivation was performed again and the temperature increase was measured. Obtained data were analyzed by ANOVA and Tukey's test (α= 0.05). The mean temperature increase produced by QTH was significantly lower than that of the other photoactivating units (P 0.05). The immediate temperature rise was statistically higher when compared to the increase after additional polymerization (24 h), in all groups (P < 0.05). Light intensity and exposure time appeared to be the most important factors causing temperature change. (J. Oral Sci. 50, 137-142, 2008)
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Effect of resin liners and Photoactivation methods on the shrinkage stress of a resin composite.
Journal of esthetic and restorative dentistry : official publication of the American Academy of Esthetic Dentistry ... [et al.], 2006Co-Authors: Leonardo Gonçalves Cunha, Roberta Caroline Bruschi Alonso, Lourenço Correr Sobrinho, Mario Alexandre Coelho SinhoretiAbstract:Purpose: This study was undertaken to evaluate the effect of three different Photoactivation methods on the polymerization shrinkage stress of a resin composite using different resin liners. Materials and Methods: Three Photoactivation methods using a quartz-tungsten-halogen light were evaluated: continuous light, soft start, and intermittent light. Three lining groups were tested: one or three coats of adhesive, and flowable composite. The stress was measured using a universal testing machine. After the stress measurement, Knoop hardness numbers (KHNs) were evaluated to verify indirectly the degree of conversion of the composite using the three Photoactivation methods. The data were submitted to analysis of variance and Tukey's test (p < .05). Results: Intermittent light was always associated with statistically lower stress values when compared with continuous light. Statistical differences were not observed when continuous light and soft start were compared. The use of a flowable composite liner significantly reduced the stress generation when compared with the use of one adhesive coat. The three adhesive coats groups showed intermediate stress values. The hardness test showed no statistical difference between that achieved with continuous light and soft start. These two methods showed statistically higher KHNs when compared with results with intermittent light. CLINICAL SIGNIFICANCE Photoactivation using intermittent light may lead to a significant reduction in shrinkage stress levels. This effect could be attributed to a significant reduction of the polymerization rate and/or a decrease in the degree of conversion. The use of a flowable composite liner reduced the stress levels when compared with levels when one coat of adhesive was used. This is possibly related to the higher thickness of the flowable composite layer.
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Effect of Photoactivation methods and base materials on the stress generated by the polymerization shrinkage of a resin composite
Brazilian Journal of Oral Sciences, 2004Co-Authors: Leonardo Gonçalves Cunha, Mario Alexandre Coelho Sinhoreti, Roberta Caroline Bruschi Alonso, Mario Fernando De Goes, Lourenço Correr SobrinhoAbstract:The aim of this study was to evaluate the effect of different Photoactivation methods and base materials on the stress generated by the polymerization shrinkage of composites. The evaluated groups for the base material were: (G1) 1 coat of adhesive; (G2) 3 coats of adhesive, and (G3) flowable composite as a liner. The groups were divided in agreement with the Photoactivation method: Continuous light (CL); Stepped Light (SL); Intermittent Light (IL); LED and Xenon Plasma Arc (XP). The generated stress was measured in a universal testing machine 5 minutes after the end of the Photoactivation. The results were submitted to ANOVA and the averages values compared by Tukey test (5%). Inside of G1 group the mean values varied between 1.62 MPa (XP) to 2.22 MPa (CL), in which the XP method presented statistically inferior values to the other appraised methods. The values inside of G2 and G3 varied from 1.64 MPa (LED) to 2.15 MPa (CL) and 1.24 MPa (IL) to 1.92 MPa (SL), respectively, and the methods LED and IL presented statistically inferior values comparatively to the method CL inside of G2 and CL and SL inside of G3. The use of base materials was shown efficient in the reduction of the stress level generated by the polymerization shrinkage of restorative composites when LED or Intermittent light Photoactivation methods are used.
Perolof Fredriksson - One of the best experts on this subject based on the ideXlab platform.
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the role of cytochrome b559 and tyrosined in protection against photoinhibition during in vivo Photoactivation of photosystem ii
Biochimica et Biophysica Acta, 1999Co-Authors: Ann Magnuson, Fikret Mamedov, Maria Rova, Perolof Fredriksson, Stenbjörn StyringAbstract:The role of cytochrome b559 and tyrosineD in protection against photoinhibition during in vivo Photoactivation of Photosystem II
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changes in the oxidation state of cytochrome b559 and tyrosine d during in vivo Photoactivation of photosystem ii
11th Photosynthesis Congress, 1998Co-Authors: Ann Magnusson, Fikret Mamedov, Maria Rova, Perolof Fredriksson, Stenbjörn StyringAbstract:Changes in the oxidation state of cytochrome b559 and tyrosine-D during in vivo Photoactivation of photosystem II
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Photoactivation and Photoinhibition Are Competing in a Mutant of Chlamydomonas reinhardtii Lacking the 23-kDa Extrinsic Subunit of Photosystem II
The Journal of biological chemistry, 1996Co-Authors: E. Maria Rova, Birgitta Mc Ewen, Perolof Fredriksson, Stenbjörn StyringAbstract:Abstract The process of Photoactivation has been studied in dark grown cells of Chlamydomonas reinhardtii. A mutant, FUD 39, lacking the Cl−-concentrating 23-kDa psbP protein of photosystem II was found to have a decreased capability to perform Photoactivation. The yield of the process never reached wild type level, and contrary to the wild type, it was highly dependent on the intensity of the activating light, with a very narrow optimum around 1 μE m−2 s−1. The different behavior in the mutant can be explained by a requirement for a longer dark period, between the two photoacts, during the Photoactivation. This is proposed to reflect the decreased Cl− affinity in the mutant. Photoactivation in the mutant was also found to be very sensitive to competing photoinhibitory processes. The inhibition was located to the donor side of photosystem II and affected the Photoactivation capability before electron transfer from Tyrz was inhibited. We propose an extended model for Photoactivation in which an intermediate that is sensitive to photoinhibition is formed if Cl− is not functionally bound to the manganese cluster.
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Photoactivation and photoinhibition of photosystem II in a mutant of Chlamydomonas reinhardtii lacking the 23 kDa extrinsic subunit
1995Co-Authors: Maria Rova, Perolof Fredriksson, Birgitta Mc Ewen, Stenbjörn StyringAbstract:Photoactivation and photoinhibition of photosystem II in a mutant of Chlamydomonas reinhardtii lacking the 23 kDa extrinsic subunit
Melike Lakadamyali - One of the best experts on this subject based on the ideXlab platform.
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Single-molecule evaluation of fluorescent protein Photoactivation efficiency using an in vivo nanotemplate
Nature methods, 2014Co-Authors: Nela Durisic, Lara Laparra-cuervo, Ángel Sandoval-Álvarez, J. S. Borbely, Melike LakadamyaliAbstract:Photoswitchable fluorescent probes are central to localization-based super-resolution microscopy. Among these probes, fluorescent proteins are appealing because they are genetically encoded. Moreover, the ability to achieve a 1:1 labeling ratio between the fluorescent protein and the protein of interest makes these probes attractive for quantitative single-molecule counting. The percentage of fluorescent protein that is photoactivated into a fluorescently detectable form (i.e., the Photoactivation efficiency) plays a crucial part in properly interpreting the quantitative information. It is important to characterize the Photoactivation efficiency at the single-molecule level under the conditions used in super-resolution imaging. Here, we used the human glycine receptor expressed in Xenopus oocytes and stepwise photobleaching or single-molecule counting photoactivated localization microcopy (PALM) to determine the Photoactivation efficiency of fluorescent proteins mEos2, mEos3.1, mEos3.2, Dendra2, mClavGR2, mMaple, PA-GFP and PA-mCherry. This analysis provides important information that must be considered when using these fluorescent proteins in quantitative super-resolution microscopy.
