Extracellular Matrix Molecules Facilitating Vascular Biointegration

All vascular implants, including stents, heart valves and graft materials exhibit suboptimal biocompatibility that significantly reduces their clinical efficacy. A range of biomolecules in the subendothelial space have been shown to play critical roles in local regulation of thrombosis, endothelial growth and smooth muscle cell proliferation, making these attractive candidates for modulation of vascular device biointegration. However, classically used biomaterial coatings, such as fibronectin and laminin, modulate only one of these components; enhancing endothelial cell attachment, but also activating platelets and triggering thrombosis. This review examines a subset of extracellular matrix molecules that have demonstrated multi-faceted vascular compatibility and accordingly are promising candidates to improve the biointegration of vascular biomaterials

Design Optimization of Perfluorinated Liquid-Infused Surfaces for Blood-Contacting Applications

Tethered-liquid perfluorocarbon (TLP) coatings show promise for bloodcontacting medical device applications to reduce blood adhesion and delay thrombosis. However, their fabrication and longevity under external fluid flow is not well characterized. A vapor phase silanization reaction leading to the formation of tethered-perfluorocarbon (TP) layers containing large bumpy aggregates, 300 ± 200 nm thick, on top of an underlying 35 ± 15 nm thick uniform coating is reported. The vapor phase method compares favorably to the well-established liquid phase deposition to reproducibly create slippery coatings on silicon and polystyrene with very low water sliding angles (2° ± 1°), without the need to control humidity conditions. The TP layer retains perfluorinated lubricants up to 20 000 s–1, using a cone-and-plate rheometer, with the higher viscosity lubricant perfluoroperhydrophenanthrene being more resistant to depletion than perfluorodecalin. TLP infused with either of the lubricants effectively reduces adhesion of fibrin from human whole blood relative to TP and control hydrophilic and hydrophobic surfaces. The combination of highly fluorinated TP coatings grafted from the vapor phase to create nanoscale structured surfaces infused with higher viscosity lubricant may be the most suitable combination for clinical applications of liquid-infused surfaces to reduce thrombosis in blood-contacting medical devices under flow

A shear gradient-activated microfluidic device for automated monitoring of whole blood haemostasis and platelet function

Accurate assessment of blood haemostasis is essential for the management of patients who use extracorporeal devices, receive anticoagulation therapy or experience coagulopathies. However, current monitoring devices do not measure effects of haemodynamic forces that contribute significantly to platelet function and thrombus formation. Here we describe a microfluidic device that mimics a network of stenosed arteriolar vessels, permitting evaluation of blood clotting within small sample volumes under pathophysiological flow. By applying a clotting time analysis based on a phenomenological mathematical model of thrombus formation, coagulation and platelet function can be accurately measured in vitro in patient blood samples. When the device is integrated into an extracorporeal circuit in pig endotoxemia or heparin therapy models, it produces real-time readouts of alterations in coagulation ex vivo that are more reliable than standard clotting assays. Thus, this disposable device may be useful for personalized diagnostics and for real-time surveillance of antithrombotic therapy in clinic

Plasma Activation of Microplates Optimized for One-Step Reagent-Free Immobilization of DNA and Protein

Activated microplates are widely used in biological assays and cell culture to immobilize biomolecules, either through passive physical adsorption or covalent cross-linking. Covalent attachment gives greater stability in complex biological mixtures. However, current multistep chemical activation methods add complexity and cost, require specific functional groups, and can introduce cytotoxic chemicals that affect downstream cellular applications. Here, we show a method for one-step linker-free activation of microplates by energetic ions from plasma for covalent immobilization of DNA and protein. Two types of energetic ion plasma treatment were shown to be effective: plasma immersion ion implantation (PIII) and plasma-activated coating (PAC). This is the first time that PIII and PAC have been reported in microwell plates with nonflat geometry. We confirm that the plasma treatment generates radical-activated surfaces at the bottom of wells despite potential shadowing from the walls. Comprehensive surface characterization studies were used to compare the PIII and PAC microplate surface composition, wettability, radical density, optical properties, stability, and biomolecule immobilization density. PAC plates were found to have more nitrogen and lower radical density and were more hydrophobic and more stable over 3 months than PIII plates. Optimal conditions were obtained for high-density DNA (PAC, 0 or 21% nitrogen, pH 3–4) and streptavidin (PAC, 21% nitrogen, pH 5–7) binding while retaining optical properties required for typical high-throughput biochemical microplate assays, such as low autofluorescence and high transparency. DNA hybridization and protein activity of immobilized molecules were confirmed. We show that PAC activation allows for high-density covalent immobilization of functional DNA and protein in a single step on both 96- and 384-well plates without specific linker chemistry. These microplates could be used in the future to bind other user-selected ligands in a wide range of applications, for example, for solid phase polymerase chain reaction and stem cell culture and differentiation

Coevolved mutations reveal distinct architectures for two core proteins in the bacterial flagellar motor

Switching of bacterial flagellar rotation is caused by large domain movements of the FliG protein triggered by binding of the signal protein CheY to FliM. FliG and FliM form adjacent multi-subunit arrays within the basal body C-ring. The movements alter the interaction of the FliG C-terminal (FliGC) "torque" helix with the stator complexes. Atomic models based on the Salmonella entrovar C-ring electron microscopy reconstruction have implications for switching, but lack consensus on the relative locations of the FliG armadillo (ARM) domains (amino-terminal (FliGN), middle (FliGM) and FliGC) as well as changes during chemotaxis. The generality of the Salmonella model is challenged by the variation in motor morphology and response between species. We studied coevolved residue mutations to determine the unifying elements of switch architecture. Residue interactions, measured by their coevolution, were formalized as a network, guided by structural data. Our measurements reveal a common design with dedicated switch and motor modules. The FliM middle domain (FliMM) has extensive connectivity most simply explained by conserved intra and inter-subunit contacts. In contrast, FliG has patchy, complex architecture. Conserved structural motifs form interacting nodes in the coevolution network that wire FliMM to the FliGC C-terminal, four-helix motor module (C3-6). FliG C3-6 coevolution is organized around the torque helix, differently from other ARM domains. The nodes form separated, surface-proximal patches that are targeted by deleterious mutations as in other allosteric systems. The dominant node is formed by the EHPQ motif at the FliMMFliGM contact interface and adjacent helix residues at a central location within FliGM. The node interacts with nodes in the N-terminal FliGc α-helix triad (ARM-C) and FliGN. ARM-C, separated from C3-6 by the MFVF motif, has poor intra-network connectivity consistent with its variable orientation revealed by structural data. ARM-C could be the convertor element that provides mechanistic and species diversity.JK was supported by Medical Research Council grant U117581331. SK was supported by seed funds from Lahore University of Managment Sciences (LUMS) and the Molecular Biology Consortium

Effects of Different Up-Dosing Regimens for Hymenoptera Venom Immunotherapy on Serum CTLA-4 and IL-10

BACKGROUND: Cytotoxic T lymphocyte associated antigen-4 (CTLA-4) is involved in the activation pathways of T lymphocytes. It has been shown that the circulating form of CTLA-4 is elevated in patients with hymenoptera allergy and can be down regulated by immunotherapy. OBJECTIVE: to assess the effects on CTLA-4 of venom immunotherapy, given with different induction protocols: conventional (6 weeks), rush (3 days) or ultra rush (1 day). METHODS: Sera from patients with hymenoptera allergy were collected at baseline and at the end of the induction phase. CTLA-4 and IL-10 were assayed in the same samples. A subset of patients were assayed also after 12 months of VIT maintenance. RESULTS: Ninety-four patients were studied. Of them, 50 underwent the conventional induction, 20 the rush and 24 the ultra-rush. Soluble CTLA-4 was detectable in all patients at baseline, and significantly decreased at the end of the induction, irrespective of its duration. Of note, a significant decrease of sCTLA-4 could be seen already at 24 hours. In parallel, IL-10 significantly increased at the end of the induction. At 12 months, sCTLA-4 remained low, whereas IL-10 returned to the baseline values. CONCLUSIONS: Serum CTLA4 is an early marker of the immunological effects of venom immunotherapy, and its changes persist after one year of maintenance treatment

The genomes of two key bumblebee species with primitive eusocial organization

Background: The shift from solitary to social behavior is one of the major evolutionary transitions. Primitively eusocial bumblebees are uniquely placed to illuminate the evolution of highly eusocial insect societies. Bumblebees are also invaluable natural and agricultural pollinators, and there is widespread concern over recent population declines in some species. High-quality genomic data will inform key aspects of bumblebee biology, including susceptibility to implicated population viability threats. Results: We report the high quality draft genome sequences of Bombus terrestris and Bombus impatiens, two ecologically dominant bumblebees and widely utilized study species. Comparing these new genomes to those of the highly eusocial honeybee Apis mellifera and other Hymenoptera, we identify deeply conserved similarities, as well as novelties key to the biology of these organisms. Some honeybee genome features thought to underpin advanced eusociality are also present in bumblebees, indicating an earlier evolution in the bee lineage. Xenobiotic detoxification and immune genes are similarly depauperate in bumblebees and honeybees, and multiple categories of genes linked to social organization, including development and behavior, show high conservation. Key differences identified include a bias in bumblebee chemoreception towards gustation from olfaction, and striking differences in microRNAs, potentially responsible for gene regulation underlying social and other traits. Conclusions: These two bumblebee genomes provide a foundation for post-genomic research on these key pollinators and insect societies. Overall, gene repertoires suggest that the route to advanced eusociality in bees was mediated by many small changes in many genes and processes, and not by notable expansion or depauperation

Stability of Surface-Immobilized Lubricant Interfaces under Flow

The stability and longevity of surface-stabilized lubricant layers is a critical question in their application as low- and nonfouling slippery surface treatments in both industry and medicine. Here, we investigate lubricant loss from surfaces under flow in water using both quantitative analysis and visualization, testing the effects of underlying surface type (nanostructured versus flat), as well as flow rate in the physiologically relevant range, lubricant type, and time. We find lubricant losses on the order of only ng/cm2 in a closed system, indicating that these interfaces are relatively stable under the flow conditions tested. No notable differences emerged between surface type, flow rate, lubricant type, or time. However, exposure of the lubricant layers to an air/water interface did significantly increase the amount of lubricant removed from the surface, leading to disruption of the layer. These results may help in the development and design of materials using surface-immobilized lubricant interfaces for repellency under flow conditions.Chemistry and Chemical BiologyEngineering and Applied Science

Fermented juices as reducing and capping agents for the biosynthesis of size-defined spherical gold nanoparticles

Gold nanoparticles (AuNPs) are of scientific and industrial significance; however, the traditional synthesis methods employ toxic compounds. Hence, non-toxic and environmentally friendly AuNPs synthesis methods are of special interest. Here, AuNPs were produced using four solutions of fermented grape juices. UV/Vis absorption spectrophotometry and transmission electron microscopy indicated that AuNPs synthesized with a solution based on semi-sweet red grapes were mostly spherical with narrow size distribution (average diameter of 82.1 ± 36.2 nm). AuNPs of similar spherical morphology but smaller size were obtained using a solution based on semi-dry red grapes (57.1 ± 16.4 nm). A large variety of AuNPs shapes and broader size distribution were produced when solutions based on semi-sweet or dry white grapes were applied. In this case, the average sizes of the AuNPs were 271.6 ± 130.2 nm and 76.0 ± 47.2 nm, respectively. Using energy dispersive X-ray spectroscopy, Au, C, and O were detected, confirming formation of biogenic AuNPs in all cases. Mie theory calculations for AuNPs synthesized with the aid of solutions based on red grapes suggest that their optical properties are different and best suited for distinct downstream applications. Attenuated total reflectance Fourier transform infrared spectroscopy, the Folin-Ciocalteu assay, and the Bertrand's method were used to examine bioactive compounds present in the solutions applied for synthesis. Phenolics, and to a lesser extent reducing sugars, were identified as likely playing a significant role in reduction and stabilization of the AuNPs. These results display the great potential of these solutions for green synthesis of size defined AuNPs, and illustrate that different grape varieties may be used to obtain AuNPs with unique properties. Keywords: Nanostructures, Bioreduction process, Phenolics, Reducing sugars, Mie scatterin