Temperature-Responsive Polyelectrolyte Complexes for Bio-Inspired Underwater Adhesives

Adhesive proteins of marine organisms contain significant amounts of hydrophobic amino acids. Therefore, inter- and intramolecular hydrophobic interactions are expected to play an important role in both adhesion and cohesion. Here, we mimic the hydrophobicity of adhesive proteins by using temperature-responsive polyelectrolyte complexes (TERPOCs) with a high poly(N-isopropylacrylamide) (PNIPAM) content. Upon mixing aqueous solutions of PNIPAM-b-poly(acrylic acid)-b-PNIPAM and poly(2-(dimethylamino) ethyl methacrylate) (PDMAEMA), complexation between the oppositely charged polyelectrolytes occurs. At low temperatures, complex coacervate core micelles (C3Ms) with a PNIPAM corona are formed, and upon a temperature increase, the solution turns into a hydrogel by the formation of a network of hydrophobic PNIPAM domains. Consequently, an abrupt increase in viscosity is observed upon heating which facilitates injectability of the adhesive. The gelation temperature, Tgel, and (adhesive) strength of the TERPOC can be adjusted by altering the salt and polymer concentration, which changes the balance between the electrostatic and hydrophobic interactions. Despite the importance of hydrophobic groups in strong underwater adhesives, we conclude that TERPOCs with a high PNIPAM content (70 wt%) are unstable due to water release. Consequently, there is a limited amount of hydrophobic groups that can be inserted in this type of systems. Nevertheless, TERPOCs show promising and tunable properties for application as injectable underwater adhesives, for example in biomedical applications

The science case and challenges of space-borne sub-millimeter interferometry

Ultra-high angular resolution in astronomy has always been an important vehicle for making fundamental discoveries. Recent results in direct imaging of the vicinity of the supermassive black hole in the nucleus of the radio galaxy M87 by the millimeter VLBI system Event Horizon Telescope and various pioneering results of the Space VLBI mission RadioAstron provided new momentum in high angular resolution astrophysics. In both mentioned cases, the angular resolution reached the values of about 10–20 microarcseconds (0.05–0.1 nanoradian). Further developments towards at least an order of magnitude “sharper” values, at the level of 1 microarcsecond are dictated by the needs of advanced astrophysical studies. The paper emphasis that these higher values can only be achieved by placing millimeter and submillimeter wavelength interferometric systems in space. A concept of such the system, called Terahertz Exploration and Zooming-in for Astrophysics, has been proposed in the framework of the ESA Call for White Papers for the Voyage 2050 long term plan in 2019. In the current paper we present new science objectives for such the concept based on recent results in studies of active galactic nuclei and supermassive black holes. We also discuss several approaches for addressing technological challenges of creating a millimeter/sub-millimeter wavelength interferometric system in space. In particular, we consider a novel configuration of a space-borne millimeter/sub-millimeter antenna which might resolve several bottlenecks in creating large precise mechanical structures. The paper also presents an overview of prospective space-qualified technologies of low-noise analogue front-end instrumentation for millimeter/sub-millimeter telescopes. Data handling and processing instrumentation is another key technological component of a sub-millimeter Space VLBI system. Requirements and possible implementation options for this instrumentation are described as an extrapolation of the current state-of-the-art Earth-based VLBI data transport and processing instrumentation. The paper also briefly discusses approaches to the interferometric baseline state vector determination and synchronisation and heterodyning system. The technology-oriented sections of the paper do not aim at presenting a complete set of technological solutions for sub-millimeter (terahertz) space-borne interferometers. Rather, in combination with the original ESA Voyage 2050 White Paper, it sharpens the case for the next generation microarcsecond-level imaging instruments and provides starting points for further in-depth technology trade-off studies.</p

Importin-8 and lysyl oxidase : human and murine insights into the pathogenesis of thoracic aortic aneurysm

Abstract: Thoracic aortic aneurysm (TAA) is caused by a pathological dilatation of the aorta due to vessel wall weakness. TAA is associated with a high mortality rate as the aneurysm can lead to sudden dissection or rupture (TAAD). Until now, more than 40 genes have been discovered that are associated with TAAD development. Still, most TAAD patients, about 70%, is missing a genetic diagnosis. The discovered genes are involved in extracellular matrix remodeling, vascular smooth muscle cell contraction and TGF-\uf062 signaling pathway. TAAD is a key characteristic of several genetic syndromes of which the most common disorders are Marfan syndrome (MFS) and Loeys-Dietz syndrome (LDS). Bi-allelic loss-of-function variants in IPO8 were identified in patients phenotypically characterized by severe early-onset TAAD development, resembling the Loeys-Dietz syndrome phenotype. IPO8 encodes for the ubiquitously expressed transport-receptor Importin-8 which is a member of the importin-\uf062 family and is involved in the translocation of cargoes such as proteins, RNAs and ribonucleoprotein complexes from the cytosol into the nucleus in a RanGTP-dependent manner. To study the pathogenesis in depth, a C57BL/6N Ipo8 knock-out (Ipo8-/-) mouse model was generated, and the cardiovascular phenotype was investigated. The Ipo8-/- mouse model recapitulates severe early-onset TAA and aortic dissection. Ipo8-/- aortic tissue studies revealed elastic fiber fragmentation, an increase in nuclear pSmad2 levels, increase in downstream transcriptional targets of the TGF-\uf062 signaling pathway, Ccn2 and Mmp2 and downregulation of Smad6 and Smad7, suggesting a role for TGF-\uf062 dysregulation in IPO8 deficiency. On the contrary, the Sv129 Ipo8-/- mouse model, mice generated on a different genetic background, did not show aortic aneurysms or dissection/ruptures, indicating the importance of the genetic background of mouse models. Additionally, an embryonic lethality of 50% was observed in C57BL/6N Ipo8-/- mice, whereas no embryonic lethality was observed in Sv129 Ipo8-/- mice. Another gene contributing to the genetic landscape of TAAD is lysyl oxidase, an extracellular matrix crosslinking enzyme, encoded by LOX. Patients carrying LOX LOF variants have heterogeneous phenotype and show a spectrum of connective tissue manifestations, aortic and arterial aneurysmal disease

Generation of one induced pluripotent cell (iPSC) line (BBANTWi011-A) from a patient carrying an IPO8 bi-allelic loss-of-function mutation

Patients carrying IPO8 bi-allelic loss-of-function variants have a highly consistent phenotype that resembles the phenotype of Loeys-Dietz syndrome. They present with early onset thoracic aortic aneurysm (TAA) and connective tissue findings such as arachnodactyly and joint hypermobility. Other recurrent phenotypic manifestations include facial dysmorphisms, a high arched or cleft palate/bifid uvula and motor developmental delay. An iPSC line (BBANTWi011-A) was generated started from peripheral blood mononuclear cells (PBMCs) from a patient carrying a homozygous variant in the IPO8 gene (MIM: 605600, NM_006390.3: c.1420C>T, p.(Arg474*)). PBMCs were reprogrammed using the Cytotune®-iPS 2.0 Sendai Reprogramming Kit (Invitrogen). The generated iPSCs are expressing pluripotency markers and are able to differentiate into the three germ layers

Self-assembly of oppositely charged polyelectrolyte block copolymers containing short thermoresponsive blocks

\u3cp\u3eThe assembly of oppositely charged block copolymers, containing small thermoresponsive moieties, was investigated as a function of salt concentration and temperature. Aqueous solutions of poly-[N-isopropylacrylamide]-b-poly[dimethylaminoethyl methacrylate] (NIPAM\u3csub\u3e44\u3c/sub\u3e-b-DMAEMA\u3csub\u3e216\u3c/sub\u3e) and PNIPAM-b-poly[acrylic acid]-b-PNIPAM (NIPAM\u3csub\u3e35\u3c/sub\u3e-b-AA\u3csub\u3e200\u3c/sub\u3e-b-NIPAM\u3csub\u3e35\u3c/sub\u3e) were mixed in equal charge stoichiometry, and analysed by light scattering (LS), NMR spectroscopy and small angle X-ray scattering (SAXS). At room temperature, two different micelle morphologies were found at different salt concentrations. At NaCl concentrations below 0.75 M, complex coacervate core micelles (C3M) with a PNIPAM corona were formed as a result of interpolyelectrolyte complexation. At NaCl concentrations exceeding 0.75 M, the C3M micelles inverted into PNIPAM cored micelles (PCM), containing a water soluble polyelectrolyte corona. This behavior is ascribed to the salt concentration dependence of both the lower critical solution temperature (LCST) of PNIPAM, and the complex coacervation. Above 0.75 M NaCl, the PNIPAM blocks are insoluble in water at room temperature, while complexation between the polyelectrolytes is prevented because of charge screening by the salt. Upon increasing the temperature, both types of micelles display a cloud point temperature (T\u3csub\u3ecp\u3c/sub\u3e), despite the small thermoresponsive blocks, and aggregate into hydrogels. These hydrogels consist of a complexed polyelectrolyte matrix with microphase separated PNIPAM domains. Controlling the morphology and aggregation of temperature sensitive polyelectrolytes can be an important tool for drug delivery systems, or the application and hardening of underwater glues.\u3c/p\u3

Novel LOX variants in five families with aortic/arterial aneurysm and dissection with variable connective tissue findings

Thoracic aortic aneurysm and dissection (TAAD) is a major cause of cardiovascular morbidity and mortality. Loss-of-function variants in LOX, encoding the extracellular matrix crosslinking enzyme lysyl oxidase, have been reported to cause familial TAAD. Using a next-generation TAAD gene panel, we identified five additional probands carrying LOX variants, including two missense variants affecting highly conserved amino acids in the LOX catalytic domain and three truncating variants. Connective tissue manifestations are apparent in a substantial fraction of the variant carriers. Some LOX variant carriers presented with TAAD early in life, while others had normal aortic diameters at an advanced age. Finally, we identified the first patient with spontaneous coronary artery dissection carrying a LOX variant. In conclusion, our data demonstrate that loss-of-function LOX variants cause a spectrum of aortic and arterial aneurysmal disease, often combined with connective tissue findings

Novel LOX Variants in Five Families with Aortic/Arterial Aneurysm and Dissection with Variable Connective Tissue Findings

Thoracic aortic aneurysm and dissection (TAAD) is a major cause of cardiovascular morbidity and mortality. Loss-of-function variants in LOX, encoding the extracellular matrix crosslinking enzyme lysyl oxidase, have been reported to cause familial TAAD. Using a next-generation TAAD gene panel, we identified five additional probands carrying LOX variants, including two missense variants affecting highly conserved amino acids in the LOX catalytic domain and three truncating variants. Connective tissue manifestations are apparent in a substantial fraction of the variant carriers. Some LOX variant carriers presented with TAAD early in life, while others had normal aortic diameters at an advanced age. Finally, we identified the first patient with spontaneous coronary artery dissection carrying a LOX variant. In conclusion, our data demonstrate that loss-of-function LOX variants cause a spectrum of aortic and arterial aneurysmal disease, often combined with connective tissue findings

Morpho-functional comparison of differentiation protocols to create iPSC-derived cardiomyocytes

Cardiomyocytes derived from induced pluripotent stem cells (iPSC-CMs) offer an attractive platform for cardiovascular research. Patient-specific iPSC-CMs are very useful for studying disease development, and bear potential for disease diagnostics, prognosis evaluation and development of personalized treatment. Several monolayer-based serum-free protocols have been described for the differentiation of iPSCs into cardiomyocytes, but data on their performance are scarce. In this study, we evaluated two protocols that are based on temporal modulation of the Wnt/β-catenin pathway for iPSC-CM differentiation from four iPSC lines, including two control individuals and two patients carrying an SCN5A mutation. The SCN5A gene encodes the cardiac voltage-gated sodium channel (Na(v)1.5) and loss-of-function mutations can cause the cardiac arrhythmia Brugada syndrome. We performed molecular characterization of the obtained iPSC-CMs by immunostaining for cardiac specific markers and by expression analysis of selected cardiac structural and ionic channel protein-encoding genes with qPCR. We also investigated cell growth morphology, contractility and survival of the iPSC-CMs after dissociation. Finally, we performed electrophysiological characterization of the cells, focusing on the action potential (AP) and calcium transient (CT) characteristics using patch-clamping and optical imaging, respectively. Based on our comprehensive morpho-functional analysis, we concluded that both tested protocols result in a high percentage of contracting CMs. Moreover, they showed acceptable survival and cell quality after dissociation (>50% of cells with a smooth cell membrane, possible to seal during patch-clamping). Both protocols generated cells presenting with typical iPSC-CM AP and CT characteristics, although one protocol (that involves sequential addition of CHIR99021 and Wnt-C59) rendered iPSC-CMs, which were more accessible for patch-clamp and calcium transient experiments and showed an expression pattern of cardiac-specific markers more similar to this observed in human heart left ventricle samples