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101.
Todorova D Sabatier F Doria E Lyonnet L Vacher Coponat H Robert S Despoix N Legris T Moal V Loundou A Morange S Berland Y George FD Burtey S Paul P 《PloS one》2011,6(10):e26663
Background
Circulating CD34+ cells, a population that includes endothelial progenitors, participate in the maintenance of endothelial integrity. Better understanding of the mechanisms that regulate their survival is crucial to improve their regenerative activity in cardiovascular and renal diseases. Chemokine-receptor cross talk is critical in regulating cell homeostasis. We hypothesized that cell surface expression of the chemokine fractalkine (FKN) could target progenitor cell injury by Natural Killer (NK) cells, thereby limiting their availability for vascular repair.Methodology/Principal Findings
We show that CD34+-derived Endothelial Colony Forming Cells (ECFC) can express FKN in response to TNF-α and IFN-γ inflammatory cytokines and that FKN expression by ECFC stimulates NK cell adhesion, NK cell-mediated ECFC lysis and microparticles release in vitro. The specific involvement of membrane FKN in these processes was demonstrated using FKN-transfected ECFC and anti-FKN blocking antibody. FKN expression was also evidenced on circulating CD34+ progenitor cells and was detected at higher frequency in kidney transplant recipients, when compared to healthy controls. The proportion of CD34+ cells expressing FKN was identified as an independent variable inversely correlated to CD34+ progenitor cell count. We further showed that treatment of CD34+ circulating cells isolated from adult blood donors with transplant serum or TNF-α/IFN-γ can induce FKN expression.Conclusions
Our data highlights a novel mechanism by which FKN expression on CD34+ progenitor cells may target their NK cell mediated killing and participate to their immune depletion in transplant recipients. Considering the numerous diseased contexts shown to promote FKN expression, our data identify FKN as a hallmark of altered progenitor cell homeostasis with potential implications in better evaluation of vascular repair in patients. 相似文献102.
Rachakonda Sreekar Chetana B. Purushotham Katya Saini Shyam N. Rao Simon Pelletier Saniya Chaplod 《PloS one》2013,8(2)
The usage of invasive tagging methods to assess lizard populations has often been criticised, due to the potential negative effects of marking, which possibly cause increased mortality or altered behaviour. The development of safe, less invasive techniques is essential for improved ecological study and conservation of lizard populations. In this study, we describe a photographic capture-recapture (CR) technique for estimating Draco dussumieri (Agamidae) populations. We used photographs of the ventral surface of the patagium to identify individuals. To establish that the naturally occurring blotches remained constant through time, we compared capture and recapture photographs of 45 pen-marked individuals after a 30 day interval. No changes in blotches were observed and individual lizards could be identified with 100% accuracy. The population density of D. dussumieri in a two hectare areca-nut plantation was estimated using the CR technique with ten sampling occasions over a ten day period. The resulting recapture histories for 24 individuals were analysed using population models in the program CAPTURE. All models indicated that nearly all individuals were captured. The estimated probability for capturing D. dussumieri on at least one occasion was 0.92 and the estimated population density was 13±1.65 lizards/ha. Our results demonstrate the potential for applying CR to population studies in gliding lizards (Draco spp.) and other species with distinctive markings. 相似文献
103.
Cyclic peptides are increasingly being shown as powerful inhibitors of fibril formation, and have the potential to be therapeutic agents for combating many debilitating amyloid-related diseases. One such example is a cyclic peptide derivative from the human apolipoprotein C-II, which has the ability to inhibit fibril formation by the fibrillogenic peptide apoC-II(60–70). Using classical molecular dynamics and electronic structure calculations, we were able to provide insight into the interaction between the amyloidogenic peptide apoC-II(60–70) and its cyclic derivative, cyc(60–70). Our results showed that cyc(60–70) induced increased flexibility in apoC-II(60–70), suggesting that one mechanism by which cyc(60–70) inhibits fibrillisation is by destabilising apoC-II(60–70) structure, rendering it incapable of adopting fibril favouring conformations. In contrast, cyc(60–70) shows less flexibility upon binding to apoC-II(60–70), which is predominantly mediated by hydrophobic interactions between the aromatic rings of the peptides. This effectively creates a cap around the fibril-forming region of apoC-II(60–70) and generates an outer hydrophilic shell that discourages further apoC-II(60–70) peptide self-association. We showed that apoC-II(60–70) exhibited stronger binding affinity for the hydrophobic face of cyc(60–70) and weakest binding affinity for the hydrophilic side. This suggests that cyc(60–70) can be an effective fibril inhibitor due to its amphipathic character, like that of the "Janus"-type particles. This property can be exploited in the design of specific inhibitors of amyloid fibril formation. 相似文献
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105.
Gabrovska K Ivanov J Vasileva I Dimova N Godjevargova T 《International journal of biological macromolecules》2011,48(4):620-626
A new matrix for enzyme immobilization of urease was obtained by incorporating rhodium nanoparticles (5% on activated charcoal) and chemical bonding of chitosan with different concentration (0.15%; 0.3%; 0.5%; 1.0%; 1.5%) in previously chemically modified AN copolymer membrane. The basic characteristics of the chitosan modified membranes were investigated. The SEM analyses were shown essential morphology change in the different modified membranes. Both the amount of bound protein and relative activity of immobilized enzyme were measured. A higher activity (about 77.44%) was measured for urease bound to AN copolymer membrane coated with 1.0% chitosan and containing rhodium nanoparticles. The basic characteristics (pH(opt), T(opt), thermal, storage and operation stability) of immobilized enzyme on this optimized modified membrane were also determined. The prepared enzyme membrane was used for the construction of amperometric biosensor for urea detection. Its basic amperometric characteristics were investigated. A calibration plot was obtained for urea concentration ranging from 1.6 to 23 mM. A linear interval was detected along the calibration curve from 1.6 to 8.2mM. The sensitivity of the constructed biosensor was calculated to be 3.1927 μAmM(-1)cm(-2). The correlation coefficient for this concentration range was 0.998. The detection limit with regard to urea was calculated to be 0.5mM at a signal-to-noise ratio of 3. The biosensor was employed for 10 days while the maximum response to urea retained 86.8%. 相似文献
106.
Chai Lean Teoh Chi L.L. Pham Nevena Todorova Craig N. Lincoln Yuen Han Lam Katrina J. Binger Neil H. Thomson Trevor A. Smith Andreas Engel Irene Yarovsky Geoffrey J. Howlett 《Journal of molecular biology》2011,405(5):1246-2639
The self-assembly of specific proteins to form insoluble amyloid fibrils is a characteristic feature of a number of age-related and debilitating diseases. Lipid-free human apolipoprotein C-II (apoC-II) forms characteristic amyloid fibrils and is one of several apolipoproteins that accumulate in amyloid deposits located within atherosclerotic plaques. X-ray diffraction analysis of aligned apoC-II fibrils indicated a simple cross-β-structure composed of two parallel β-sheets. Examination of apoC-II fibrils using transmission electron microscopy, scanning transmission electron microscopy, and atomic force microscopy indicated that the fibrils are flat ribbons composed of one apoC-II molecule per 4.7-Å rise of the cross-β-structure. Cross-linking results using single-cysteine substitution mutants are consistent with a parallel in-register structural model for apoC-II fibrils. Fluorescence resonance energy transfer analysis of apoC-II fibrils labeled with specific fluorophores provided distance constraints for selected donor-acceptor pairs located within the fibrils. These findings were used to develop a simple ‘letter-G-like’ β-strand-loop-β-strand model for apoC-II fibrils. Fully solvated all-atom molecular dynamics (MD) simulations showed that the model contained a stable cross-β-core with a flexible connecting loop devoid of persistent secondary structure. The time course of the MD simulations revealed that charge clusters in the fibril rearrange to minimize the effects of same-charge interactions inherent in parallel in-register models. Our structural model for apoC-II fibrils suggests that apoC-II monomers fold and self-assemble to form a stable cross-β-scaffold containing relatively unstructured connecting loops. 相似文献
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110.
Erin M. Stuckey Jennifer Stevenson Katya Galactionova Amrish Y. Baidjoe Teun Bousema Wycliffe Odongo Simon Kariuki Chris Drakeley Thomas A. Smith Jonathan Cox Nakul Chitnis 《PloS one》2014,9(10)