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Lisa N Chesner, Colin Campbell
The purpose of this method is to provide a flexible, rapid, and quantitative technique to examine the kinetics of DNA-protein crosslink (DPC) repair in mammalian cell lines. Rather than globally assaying removal of xenobiotic-induced or spontaneous chromosomal DPC removal, this assay examines the repair of a homogeneous, chemically defined lesion specifically introduced at one site within a plasmid DNA substrate. Importantly, this approach avoids the use of radioactive materials and is not dependent on expensive or highly-specialized technology...
March 5, 2018: Journal of Visualized Experiments: JoVE
Xiuxiu Wang, Ru Cheng, Liang Cheng, Zhiyuan Zhong
PLGA, a copolymer of lactide and glycolide, is one of the most used biodegradable polymers that find a wide range of biomedical applications including drug delivery and tissue engineering. However, in spite of remarkable advancement, nanotherapeutics based on PLGA might have drawbacks of inadequate stability, drug leakage, and slow drug release at the tumor site, which reduces its targeting ability and therapeutic efficacy. Here, we report that direct modification of star PLGA ends with lipoic acid, a natural antioxidant present in our human body, affords a smart material (sPLGA-LA) that forms reversibly crosslinked and bioresponsive multifunctional nanoparticles (sPLGA XNPs)...
March 19, 2018: Biomacromolecules
Yong-Eun Kim, Chungoo Park, Kyoon Eon Kim, Kee K Kim
Alternative splicing is an essential process in eukaryotes, as it increases the complexity of gene expression by generating multiple proteins from a single pre-mRNA. However, information on the regulatory mechanisms for alternative splicing is lacking, because splicing occurs over a short period via the transient interactions of proteins within functional complexes of the spliceosome. Here, we investigated in detail the molecular mechanisms connecting alternative splicing with epigenetic mechanisms. We identified interactions between histone proteins and splicing factors such as Rbfox2, Rbfox3, and splicing factor proline and glutamine rich protein (SFPQ) by in vivo crosslinking and immunoprecipitation...
March 15, 2018: Biochemical and Biophysical Research Communications
Maria J Rodriguez, Thomas A Dixon, Eliad Cohen, Wenwen Huang, Fiorenzo G Omenetto, David L Kaplan
Freeform fabrication has emerged as a key direction in printing biologically-relevant materials and structures. With this emerging technology, complex structures with microscale resolution can be created in arbitrary geometries and without the limitations found in traditional bottom-up or top-down additive manufacturing methods. Recent advances in freeform printing have used the physical properties of microparticle-based granular gels as a medium for the submerged extrusion of bioinks. However, most of these techniques require post-processing or crosslinking for the removal of the printed structures [1,2]...
March 14, 2018: Acta Biomaterialia
Jie-Lin Wang, Qian Chen, Bei-Bei Du, Lu Cao, Hong Lin, Zhong-Yong Fan, Jian Dong
The composite polylactide PLLA/β-TCP scaffolds were fabricated by solution casting and were coated with gelatin/hydroxyapatite (Gel/HAp) to improve the biological properties of the composite scaffolds. The Gel/HAp mixture was prepared using an in situ reaction, and a grafting-coating method was used to increase the efficiency of coating the PLLA/β-TCP matrix with Gel/HAp. First, free amino groups were introduced by 1,6-hexanediamine to aminolyze the PLLA/β-TCP matrix surface. Second, glutaraldehyde was coupled to Gel/HAp as a crosslinking agent...
June 1, 2018: Materials Science & Engineering. C, Materials for Biological Applications
Loredana Elena Nita, Aurica P Chiriac, Alina Gabriela Rusu, Maria Bercea, Alina Diaconu, Nita Tudorachi
The interpenetrating polymer networks (IPNs) are promising materials due to their unique properties. In this context, in the present study, new IPN structures based on poly(dimethylaminoethyl methacrylate) (PDMAEMA) and poly(itaconic anhydride-co-3,9-divinyl-2,4,8,10-tetraoxaspiro[5.5] undecane) (PITAU) were synthesized. The double network was prepared by synthesizing and crosslinking (with N, N'-methylenebis(acrylamide)) PDMAEMA in the presence of a preformed PITAU network. The effect of the two components upon some properties such us: viscoelasticity, thermal stability and swelling behavior of the new prepared gels were deeply investigated...
June 1, 2018: Materials Science & Engineering. C, Materials for Biological Applications
Kehu Zhang, Jiangtao Liu, Yinzhou Guo, Yan Li, Xiao Ma, Zhongli Lei
Herein, we prepared a novel quintuple-stimuli-responsive shell-crosslinked (SCL) nanocontainer in respond to temperature, pH, light, and oxidation or reduction species. The well-defined amphiphilic diblock copolymer poly(2-methacryloyloxyethyl ferrocenecarboxylate)-(5-propargylether-2-nitrobenzyl bromoisobutyrate)-poly(dimethylaminoethyl methacrylate) (PMAEFc-ONB-PDMAEMA) was synthesized via atom transfer radical polymerization (ATRP) and click chemistry. The diblock copolymer self-assembled into spherical micelles with a uniform size in aqueous media as non-crosslinked (NCL) micelles, and then the micelles were crosslinked by N,N'-bis(bromoacetyl) cystamine (BBAC) through quaternization reaction between the nitrogen of DMAEMA and the bromine of BBAC to receive the SCL micelles which shrunk at higher temperature, swelled at acidic pH or a low concentration of hydrogen peroxide (H2 O2 ), decrosslinked by a small amount of DL-dithiothreitol (DTT), and were disrupted with DTT and UV light...
June 1, 2018: Materials Science & Engineering. C, Materials for Biological Applications
Sidy Ba, Lounès Haroune, Lassine Soumano, Jean-Phillipe Bellenger, J Peter Jones, Hubert Cabana
The increasing presence of pharmaceutical products (PPs) and other organic contaminants of emerging concern (CECs) in aquatic systems has become one of the major global environmental contamination concerns. Sewage treatment plants (STPs) are one of the major sources of PPs discharge into natural waters due to the deficiencies of conventional treatment processes to deal with these micropollutants. Numerous new treatment processes and technologies have been investigated for the removals of CECs in wastewaters with more or less success...
March 5, 2018: Chemosphere
Merve Özkan, Maryam Borghei, Alp Karakoç, Orlando J Rojas, Jouni Paltakari
We systematically investigated the effect of film-forming polyvinyl alcohol and crosslinkers, glyoxal and ammonium zirconium carbonate, on the optical and surface properties of films produced from TEMPO-oxidized cellulose nanofibers (TOCNFs). In this regard, UV-light transmittance, surface roughness and wetting behavior of the films were assessed. Optimization was carried out as a function of film composition following the "random forest" machine learning algorithm for regression analysis. As a result, the design of tailor-made TOCNF-based films can be achieved with reduced experimental expenditure...
March 16, 2018: Scientific Reports
Ditte Beck Jepsen, Jesper Ryg, Niklas Rye Jørgensen, Stinus Hansen, Tahir Masud
BACKGROUND: PaVOS is a randomized controlled trial (RCT) which aims to address the use of whole-body vibration exercise (WBV) in combination with parathyroid hormone 1-34 fragment teriparatide (PTH 1-34) treatment in patients with osteoporosis. PTH 1-34 is an effective but expensive anabolic treatment for osteoporosis. WBV has been found to stimulate muscle and bone growth. Animal studies have shown a beneficial effect on bone when combining PTH 1-34 with mechanical loading. A combined treatment with PTH 1-34 and WBV may potentially have beneficial effects on bone and muscles, and reduce fracture risk...
March 16, 2018: Trials
H Hatami-Marbini
Networks of semiflexible filaments are building blocks of different biological and structural materials such as cytoskeleton and extracellular matrix. The mechanical response of these systems when subjected to an applied strain at zero temperature is often investigated numerically using networks composed of filaments, which are either rigidly welded or pinned together at their crosslinks. In the latter, filaments during deformation are free to rotate about their crosslinks while the relative angles between filaments remain constant in the former...
February 2018: Physical Review. E
Tales Rocha de Moura, Sina Mozaffari-Jovin, Csaba Zoltán Kibédi Szabó, Jana Schmitzová, Olexandr Dybkov, Constantin Cretu, Michael Kachala, Dmitri Svergun, Henning Urlaub, Reinhard Lührmann, Vladimir Pena
Human nineteen complex (NTC) acts as a multimeric E3 ubiquitin ligase in DNA repair and splicing. The transfer of ubiquitin is mediated by Prp19-a homotetrameric component of NTC whose elongated coiled coils serve as an assembly axis for two other proteins called SPF27 and CDC5L. We find that Prp19 is inactive on its own and have elucidated the structural basis of its autoinhibition by crystallography and mutational analysis. Formation of the NTC core by stepwise assembly of SPF27, CDC5L, and PLRG1 onto the Prp19 tetramer enables ubiquitin ligation...
March 15, 2018: Molecular Cell
Julia K Nussbacher, Gene W Yeo
RNA binding proteins (RBPs) interact with primary, precursor, and mature microRNAs (miRs) to influence mature miR levels, which in turn affect critical aspects of human development and disease. To understand how RBPs contribute to miR biogenesis, we analyzed human enhanced UV crosslinking followed by immunoprecipitation (eCLIP) datasets for 126 RBPs to discover miR-encoding genomic loci that are statistically enriched for RBP binding. We find that 92% of RBPs interact directly with at least one miR locus, and that some interactions are cell line specific despite expression of the miR locus in both cell lines evaluated...
March 15, 2018: Molecular Cell
N De Neve, B Vlaeminck, F Gadeyne, E Claeys, P Van der Meeren, V Fievez
Previously, polyunsaturated fatty acids (PUFA) from linseed oil were effectively protected (>80%) against biohydrogenation through polyphenol-oxidase-mediated protein crosslinking of an emulsion, prepared with polyphenol oxidase (PPO) extract from potato tuber peelings. However, until now, emulsions of only 2 wt% oil have been successfully protected, which implies serious limitations both from a research perspective (e.g. in vivo trials) as well as for further upscaling toward practical applications. Therefore, the aim of this study was to increase the oil/PPO ratio...
March 16, 2018: Animal: An International Journal of Animal Bioscience
Babloo Sharma, Susanne Striegler
In an effort to develop biomimetic glycosyl transfer catalysts, a polymerization protocol was developed that is applicable to the synthesis of crosslinked microgels via UV-initiated free radical polymerization of miniemulsions at ambient temperature and below. The catalytic activity of the microgels derived from butyl acrylate, EGDMA and a catalyst-precursor ligand was established using the hydrolysis of 4-methylumbelliferyl -D-galactopyranoside as a model reaction. The microgel-catalyzed hydrolysis was up to 3 × 105-fold accelerated over the background reaction and notably 38-fold faster than the hydrolysis catalyzed by its low molecular weight analog...
March 16, 2018: Biomacromolecules
Marlena Whinton, Timothy C Hughes, Shuhua Peng, Michael A Brook
Bicontinuous microemulsions exhibit domain structures on the nanoscale (<20 nm). Normally, such fine details are lost during the conversion from a fluid microemulsion to solid elastomeric materials, as a consequence of interfacial destabilization via polymerization of either the oil phase, or of monomers in the aqueous phase. Very little is known about the polymerization of silicone microemulsions and the morphological changes that occur upon transition from a nanostructured liquid to a solid ma-trix. Silicone microemulsions polymerized by free radical (aqueous phase) and condensation (silicone phase) processes, respective-ly, were characterized by small angle X-ray scattering (SAXS) and transmission electron microscopy (TEM)...
March 16, 2018: Langmuir: the ACS Journal of Surfaces and Colloids
Makoto Ashiuchi, Yuichi Hakumai, Sawami Nakayama, Haruna Higashiuchi, Kosuke Shimada
We are now entering a new age of intelligent material development using fine, sustainable polymers from extremophiles. Herein we present an innovative (but simple) means of transforming archaeal poly-γ-glutamate (PGA) into extremely durable polyionic complexes with potent antimicrobial performance. This new supra-polymer material (called PGA/DEQ) was subjected to nuclear magnetic resonance and X-ray diffraction spectroscopies to characterize in structural chemistry. Calorimetric measurements revealed its peculiar thermal properties; to the best of our knowledge, it is one of the most heat-resistant biopolymer-based polyionic complexes developed to date...
March 15, 2018: Scientific Reports
Jasmin L Whittaker, Rajkamal Balu, Robert Knott, Liliana de Campo, Jitendra P Mata, Christine Rehm, Anita J Hill, Naba K Dutta, Namita Roy Choudhury
Regenerated Bombyx mori silk fibroin (RSF) is a widely recognized protein for biomedical applications; however, their hierarchical gel structures are poorly understood. In this paper, the hierarchical structure of photocrosslinked RSF and RSF-based hybrid hydrogel systems: (i) RSF/Rec1-resilin and (ii) RSF/poly(N-vinylcaprolactam (PVCL) is reported for the first time using small-angle scattering (SAS) techniques. The structure of RSF in dilute to concentrated solution to fabricated hydrogels were characterized using small angle X-ray scattering (SAXS), small angle neutron scattering (SANS) and ultra-small angle neutron scattering (USANS) techniques...
March 12, 2018: International Journal of Biological Macromolecules
Felix A Blyakhman, Nikita A Buznikov, Tatyana F Sklyar, Alexander P Safronov, Elizaveta V Golubeva, Andrey V Svalov, Sergey Yu Sokolov, Grigory Yu Melnikov, Iñaki Orue, Galina V Kurlyandskaya
Hydrogels are biomimetic materials widely used in the area of biomedical engineering and biosensing. Ferrogels (FG) are magnetic composites capable of functioning as magnetic field sensitive transformers and field assisted drug deliverers. FG can be prepared by incorporating magnetic nanoparticles (MNPs) into chemically crosslinked hydrogels. The properties of biomimetic ferrogels for multifunctional biosensor applications can be set up by synthesis. The properties of these biomimetic ferrogels can be thoroughly controlled in a physical experiment environment which is much less demanding than biotests...
March 15, 2018: Sensors
Musammir Khan, Janne T Koivisto, Terttu I Hukka, Mikko Hokka, Minna Kellomäki
Biopolymers are attractive candidates to fabricate biocompatible hydrogels, but the low water solubility of most of them at physiological pH, has hindered their applications. To prepare a water-soluble derivative of chitosan (WSC) biopolymer, it was grafted with a small anionic amino acid, L-glutamic acid, using a single step 1-Ethyl-3-[3-dimethylaminopropyl] carbodiimide coupling reaction. This resulted in a zwitterion-tethered structure onto the polymer backbone. The degree of substitution ranged between 13-16 ± 1...
March 15, 2018: ACS Applied Materials & Interfaces
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