Search

Reversibly photoswitchable fluorescent proteins (rsFPs) are gaining popularity as tags for optical nanoscopy because they make it possible to image with lower light doses. However, green rsFPs need violet-blue light for photoswitching, which is potentially phototoxic and highly scattering. We developed new rsFPs based on FusionRed that are reversibly photoswitchable with green-orange light. The rsFusionReds are bright and exhibit rapid photoswitching, thereby enabling nanoscale imaging of living cells.

Objective: To identify the presence of phlebitis and the factors that influence the development of this complication in adult patients admitted to hospital in the western Brazilian Amazon., Method: Exploratory study with a sample of 122 peripheral intravenous catheters inserted in 122 patients in a medical unit. Variables related to the patient and intravenous therapy were analyzed. For the analysis, we used chi-square tests of Pearson and Fisher exact test, with 5% significance level., Results: Complication was the main reason for catheter removal (67.2%), phlebitis was the most frequent complication (31.1%). The mean duration of intravenous therapy use was 8.81 days in continuous and intermittent infusion (61.5%), in 20G catheter (39.3%), inserted in the dorsal hand vein arc (36.9 %), with mean time of usage of 68.4 hours. The type of infusion (p=0.044) and the presence of chronic disease (p=0.005) and infection (p=0.007) affected the development of phlebitis., Conclusion: There was a high frequency of phlebitis in the sample, being influenced by concomitant use of continuous and intermittent infusion of drugs and solutions, and more frequent in patients with chronic diseases and infection., Objetivo: Identificar a presença de flebite e os fatores que influenciam o desenvolvimento desta complicação em pacientes adultos internados em hospital da Amazônia Ocidental Brasileira., Método: Estudo exploratório, com amostra de 122 cateteres intravenosos periféricos instalados em 122 pacientes de uma unidade de clínica médica. Foram analisadas variáveis relacionadas ao paciente e à terapia intravenosa. Para a análise utilizaram-se os testes de Qui-quadrado de Pearson e Exato de Fisher, com nível de significância de 5%., Resultados: A complicação foi o principal motivo da retirada do cateter (67,2%), e a flebite a complicação mais frequente (31,1%). O tempo médio de uso de terapia intravenosa foi de 8,81 dias, em infusão contínua e intermitente (61,5%), em cateter calibre 20G (39,3%), inseridos nas veias do arco dorsal da mão (36,9%), com média de tempo de permanência de 68,4 horas. O tipo de infusão (p=0,044) e a presença de doença crônica (p=0,005) e de infecção (p=0,007) influenciaram o desenvolvimento de flebite., Conclusão: Houve alta frequência de flebite na amostra estudada, sendo influenciada pelo emprego concomitante de infusão contínua e intermitente de fármacos e soluções, e mais frequente em pacientes com doenças crônicas e infecção.

A cross-sectional study was conducted to determine the distribution of serum cadmium (Cd) levels in blood donors in Rio Branco, Acre State, Brazil. Blood samples were obtained from 922 volunteer blood donors from 18 to 65 years of age at the Hemoacre blood center in 2010-2011. Mean serum Cd was 0.37µg/L (95%CI: 0.33-0.41). Increased serum Cd was associated with lower schooling; individuals with less than five years of schooling showed a mean Cd of 0.61µg/L (95%CI: 0.34-0.89), compared to 0.34µg/L (95%CI: 0.28-0.40) among those with more than nine years of schooling. Mean serum Cd was three times higher among smokers. Smoking showed a positive association with Cd level, with an OR of 12.36 (95%CI: 7.70-19.84). Meanwhile, serum Cd was lower among individuals that regularly drank tea, as compared to non-tea drinkers. Serum Cd levels were mostly below the reference value (88.3% of participants). Mean serum Cd in the current study indicates that in general the population studied here is not exposed to worrisome Cd levels.

Xylella fastidiosa is responsible for a wide range of economically important plant diseases. We report here the crystal structure and kinetic data of Xylellain, the first cysteine protease characterized from the genome of the pathogenic X. fastidiosa strain 9a5c. Xylellain has a papain-family fold, and part of the N-terminal sequence blocks the enzyme active site, thereby mediating protein activity. One novel feature identified in the structure is the presence of a ribonucleotide bound outside the active site. We show that this ribonucleotide plays an important regulatory role in Xylellain enzyme kinetics, possibly functioning as a physiological mediator., (Copyright © 2013 Federation of European Biochemical Societies. Published by Elsevier B.V. All rights reserved.)

Photoactivatable fluorescent proteins are essential players in nanoscopy approaches based on the super-localization of single molecules. The subclass of reversibly photoswitchable fluorescent proteins typically activate through isomerization of the chromophore coupled with a change in its protonation state. However, the interplay between these two events, the details of photoswitching pathways, and the role of protein dynamics remain incompletely understood. Here, by using a combination of structural and spectroscopic approaches, we discovered two fluorescent intermediate states along the on-switching pathway of the fluorescent protein Padron. The first intermediate can be populated at temperatures as low as 100 K and results from a remarkable trans-cis isomerization of the anionic chromophore taking place within a protein matrix essentially deprived of conformational flexibility. This intermediate evolves in the dark at cryotemperatures to a second structurally similar but spectroscopically distinct anionic intermediate. The final fluorescent state, which consists of a mixture of anionic and neutral chromophores in the cis configuration, is only reached above the glass transition temperature, suggesting that chromophore protonation involves solvent interactions mediated by pronounced dynamical breathing of the protein scaffold. The possibility of efficiently and reversibly photoactivating Padron at cryotemperatures will facilitate the development of advanced super-resolution imaging modalities such as cryonanoscopy.

We have studied the photoswitching behaviour of a number of photochromic fluorescent proteins at cryo-temperature. Spectroscopic investigations at the ensemble level showed that EYFP, Dronpa and IrisFP all exhibit reversible photoswitching at 100 K, albeit with a low quantum yield. The photophysics of the process were studied in more details in the case of EYFP. The data suggest that photoinduced protonation of the chromophore is responsible for off-switching at cryo-temperature, and thus is possible in the absence of significant conformational freedom. This finding is consistent with the hypothesis that chromophore protonation may precede large amplitude conformational changes such as cis-trans isomerisation during off-photoswitching at room temperature. However, our data suggest that low-barrier photoinduced protonation pathways may in fact compete with room-temperature off-switching reactions in photochromic fluorescent proteins. The occurrence of reversible photoswitching at low-temperature is of interest to envisage cryo-nanoscopy experiments using genetically encoded fluorophores.