Satellite cell contribution to disease pathology in Duchenne muscular dystrophy

Progressive muscle weakness and degeneration characterize Duchenne muscular dystrophy (DMD), a lethal, x-linked neuromuscular disorder that affects 1 in 5,000 boys. Loss of dystrophin protein leads to recurrent muscle degeneration, progressive fibrosis, chronic inflammation, and dysfunction of skeletal muscle resident stem cells, called satellite cells. Unfortunately, there is currently no cure for DMD. In this mini review, we discuss how satellite cells in dystrophic muscle are functionally impaired, and how this contributes to the DMD pathology, and the tremendous potential of restoring endogenous satellite cell function as a viable treatment strategy to treat this debilitating and fatal disease

Sol-gel derived nano-silica suspensions for inclusion in cement paste

Nano-silica (NS) is one of the most widely used nanomaterials in the cement industry, the addition of which delivers many advantages in improving the properties of hardened cement. It has been proven that NS can increase the strength, reduce the permeability, increase the durability, and reduce the CO2 emissions by lessening the usage of cement. However, the associated problems such as the agglomeration of NS and uneven dispersion of NS in the cement pastes limit its potential benefits. These problems were addressed in this research by optimizing the method of NS incorporation. NS was synthesized by the sol-gel method and was utilized in cement as a suspension of calcium hydroxide. The hydration of cement with the sol-gel derived NS was studied using various techniques such as isothermal calorimetry, differential scanning calorimetry, mercury intrusion porosimetry, scanning electron microscopy, non-evaporable water content measurements, and X-ray diffraction with Rietveld refinement as well as mechanical properties. The optimum amount of NS was determined to be approximately 4% and perhaps as low as 2% if ultra sonification is utilized. It was shown that the NS synthesized by this method increased the rate of hydration by 12% in two days in terms of energy. Calcium hydroxide consumption and refinement of the microstructure and pore structure improved until this optimum amount. Moreover, the mechanical strength was improved up 35% in two days and 50% in seven days. The limitations of the NS usage can be minimized by this novel approach of NS incorporation

The kinetics of antibody binding to Plasmodium falciparum VAR2CSA PfEMP1 antigen and modelling of PfEMP1 antigen packing on the membrane knobs

<p>Abstract</p> <p>Background</p> <p>Infected humans make protective antibody responses to the PfEMP1 adhesion antigens exported by <it>Plasmodium falciparum </it>parasites to the erythrocyte membrane, but little is known about the kinetics of this antibody-receptor binding reaction or how the topology of PfEMP1 on the parasitized erythrocyte membrane influences antibody association with, and dissociation from, its antigenic target.</p> <p>Methods</p> <p>A Quartz Crystal Microbalance biosensor was used to measure the association and dissociation kinetics of VAR2CSA PfEMP1 binding to human monoclonal antibodies. Immuno-fluorescence microscopy was used to visualize antibody-mediated adhesion between the surfaces of live infected erythrocytes and atomic force microscopy was used to obtain higher resolution images of the membrane knobs on the infected erythrocyte to estimate knob surface areas and model VAR2CSA packing density on the knob.</p> <p>Results</p> <p>Kinetic analysis indicates that antibody dissociation from the VAR2CSA PfEMP1 antigen is extremely slow when there is a high avidity interaction. High avidity binding to PfEMP1 antigens on the surface of <it>P. falciparum</it>-infected erythrocytes in turn requires bivalent cross-linking of epitopes positioned within the distance that can be bridged by antibody. Calculations of the surface area of the knobs and the possible densities of PfEMP1 packing on the knobs indicate that high-avidity cross-linking antibody reactions are constrained by the architecture of the knobs and the large size of PfEMP1 molecules.</p> <p>Conclusions</p> <p>High avidity is required to achieve the strongest binding to VAR2CSA PfEMP1, but the structures that display PfEMP1 also tend to inhibit cross-linking between PfEMP1 antigens, by holding many binding epitopes at distances beyond the 15-18 nm sweep radius of an antibody. The large size of PfEMP1 will also constrain intra-knob cross-linking interactions. This analysis indicates that effective vaccines targeting the parasite's vulnerable adhesion receptors should primarily induce strongly adhering, high avidity antibodies whose association rate constant is less important than their dissociation rate constant.</p

Analysis of the kinetics of band 3 diffusion in human erythroblasts during assembly of the erythrocyte membrane skeleton

P\u3eDuring definitive erythropoiesis, erythroid precursors undergo differentiation through multiple nucleated states to an enucleated reticulocyte, which loses its residual RNA/organelles to become a mature erythrocyte. Over the course of these transformations, continuous changes in membrane proteins occur, including shifts in protein abundance, rates of expression, isoform prominence, states of phosphorylation, and stability. In an effort to understand when assembly of membrane proteins into an architecture characteristic of the mature erythrocyte occurs, we quantitated the lateral diffusion of the most abundant membrane protein, band 3 (AE1), during each stage of erythropoiesis using single particle tracking. Analysis of the lateral trajectories of individual band 3 molecules revealed a gradual reduction in mobility of the anion transporter as erythroblasts differentiated. Evidence for this progressive immobilization included a gradual decline in diffusion coefficients as determined at a video acquisition rate of 120 frames/s and a decrease in the percentage of compartment sizes \u3e 100 nm. Because complete acquisition of the properties of band 3 seen in mature erythrocytes is not observed until circulating erythrocytes are formed, we suggest that membrane maturation involves a gradual and cooperative assembly process that is not triggered by the synthesis of any single protein

Characterization of 65 Epitope-Specific Dystrophin Monoclonal Antibodies in Canine and Murine Models of Duchenne Muscular Dystrophy by Immunostaining and Western Blot

<div><p>Epitope-specific monoclonal antibodies can provide unique insights for studying cellular proteins. Dystrophin is one of the largest cytoskeleton proteins encoded by 79 exons. The absence of dystrophin results in Duchenne muscular dystrophy (DMD). Over the last two decades, dozens of exon-specific human dystrophin monoclonal antibodies have been developed and successfully used for DMD diagnosis. Unfortunately, the majority of these antibodies have not been thoroughly characterized in dystrophin-deficient dogs, an outstanding large animal model for translational research. To fill the gap, we performed a comprehensive study on 65 dystrophin monoclonal antibodies in normal and dystrophic dogs (heart and skeletal muscle) by immunofluorescence staining and western blot. For comparison, we also included striated muscles from normal BL10 and dystrophin-null mdx mice. Our analysis revealed distinctive species, tissue and assay-dependent recognition patterns of different antibodies. Importantly, we identified 15 antibodies that can consistently detect full-length canine dystrophin in both immunostaining and western blot. Our results will serve as an important reference for studying DMD in the canine model.</p></div

MANEX4850D only reacts with dog dystrophin.

<p>Immunofluorescence staining and western blot were performed on mouse and dog muscles from normal and dystrophic animals using MANEX4850D, an epitope specific antibody against exons encoding repeat 19 and hinge 3 of the central rod domain of dystrophin. Scale bar, 50 µm.</p

MANHINGE4A is a heart specific antibody.

<p>Immunofluorescence staining and western blot were performed on mouse and dog muscles from normal and dystrophic animals using MANDYS141, an epitope specific antibody against exons encoding hinge 4 of the central rod domain of dystrophin. Scale bar, 50 µm.</p

Antibodies that we recommend for canine study (immunostaining and western blot).

<p>IF, immunofluorescence staining; Ig, immunoglobulin; WB, western blot.</p><p>CT, C-terminal domain; H, hinge; NT, N-terminal domain; R, spectrin-like repeat.</p><p>+++, strongly positive in immunostaining; ++, positive in immunostaining; +, weakly positive in immunostaining; −, negative in immunostaining.</p><p>Pos, positive in western blot; Weak, weakly positive in western blot.</p