bluuebunny/crossref_metadata_2025_split huggingface dataset:
Synthesis, characterization, and swelling behavior of new pH‐sensitive hydrogels derived from copolymers of 2‐hydroxyethyl methacrylate and 2‐(diisopropylamino)ethylmethacrylate
Authors: Faccia Paula A. , Amalvy Javier I. 
Published: May 2012

AbstractThe aim of this work was to synthesize and to characterize new pH‐sensitive hydrogels that can be used in the controlled release of drugs, useful for dermal treatments or ophthalmology's therapies. Copolymers containing 2‐hydroxyethyl methacrylate (HEMA) with different amounts of 2‐(diisopropylamino)ethyl methacrylate (DPA) (10 and 30 wt %) and different amounts of crosslinker agent, ethylene glycol dimethacrylate (EGDMA) (1 and 3 wt %) were prepared by bulk photo‐polymerization. The copolymers were fully characterized by using Fourier‐transform infrared (FTIR) spectra, differential scanning calorimetry, thermogravimetric analysis, UV–visible spectroscopy, and measuring water content and dynamic swelling degree. The results show that modifications in the amount of DPA and/or crosslinker in the hydrogel produce variations in the thermal properties. When adding of DPA, we observed an increase in the thermal stability and decomposition temperature, as well as a change in the mechanism of decomposition. Also a decrease in the glass transition temperature was observed with regard to the value for pure pHEMA, by the addition of DPA. The water content of the hydrogels depends on the DPA content and it is inversely proportional to both the pH value and the crosslinking degree. Pure poly‐HEMA films did not show important changes over the pH range studied in this work. The dynamic swelling curves show the overshooting effect associated with the incorporation of DPA, the pH of the solution, and the crosslinking density. On the other hand, no important variations in the optical properties were observed. The synthesized hydrogels are useful as a drug delivery pH‐sensitive matrix. © 2012 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013
In situ crosslinkable sulfonated polyaromatic ionomers for the polyelectrolyte used in proton exchange membrane fuel cell
Authors: Wang S. J. , Chen Y. , Xiao M. , Meng Y. Z. 
Published: May 2012

AbstractTwo series of sulfonated poly(arylene ether nitrile ketone) ionomers containing potential crosslinkable nitrile groups were synthesized in high yield by direct aromatic nucleophilic polycondensation of 1,4‐bis‐(4‐hydroxyphenyl)‐2,3‐dicyano ‐naphthalene (3) with different molar ratio of disodium 5,5′‐carbonyl‐bis‐(2‐fluorobenzene‐sulfonate) (4) to 5,5′‐carbonyl‐bis‐(2‐fluorobenzene) (5) or 4,4‐biphenol (7). Subsequently, the sulfonated polymeric ionomers were in situ crosslinked when cast into membranes from solution at 180°C under nitrogen protection. The structure of the synthesized polymers was characterized by 1H‐nuclear magnetic resonance (NMR), Fourier‐transform infrared spectra, and elemental analysis. Comparing with the original polymeric membranes, the crosslinked membranes showed much better thermal and hydrolytic stabilities and superior mechanical properties as well as much lower swelling behavior, which were even better than Nafion 117 membrane. © 2012 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013
Copolymer‐induced silk‐based hydrogel with porous and nanofibrous structure
Authors: Zhong Tianyi , Xie Zonggang , Deng Chunmin , Chen Mei , Gao Yanfei , Zuo Baoqi 
Published: May 2012

AbstractA novel physical blend method was developed to accelerate the self‐assembly process of silk fibroin (SF) solution into porous and nanofibrous hydrogel by temperature‐sensitive copolymer. Silk‐based hydrogel was firstly achieved through blending SF solution with copolymer aqueous solution and then removed the copolymer from blend solution by heat treatment (50°C) after 24 h hydrogelation. Copolymer molecules would interact with SF molecules resulting in reduction of copolymer micelles, which further affect the hydrogelation of SF solutions. Copolymers could be separated from blend solution by heat treatment under an acceptable temperature (50°C), especially the copolymer2. Fourier transform infrared (FTIR) and X‐ray diffraction showed the blending of copolymer significantly accelerated the self‐assembly of SF into physically crosslinked β‐sheet crystals at room temperature which led to the sol‐gel transition. Results from DTA and X‐ray diffraction showed that the effect of copolymer on crystalline structure of SF in silk‐based hydrogel was very weak. SF molecules transformed from distributed globular nanoparticles to nanofilaments clustered during hydrogelation, resulting in the porous and nanofibrous structure of silk‐based hydrogel. Furthermore, silk‐based hydrogel was prepared in aqueous solution avoiding organic solvents and harsh processing conditions, suggesting that this silk‐based hydrogel could be a potential candidate scaffold for biomedical applications. © 2012 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013
Variation of lexan polycarbonate properties by electron beam
Authors: Hareesh K. , Ranganathaiah C. , Ramya P. , Bhargavi R. , Nair Geetha G. , Sangappa  , Sanjeev Ganesh 
Published: May 2012

AbstractThe modifications in microstructural, optical, and photoluminescence properties of the Lexan polycarbonate (bisphenol‐A‐polycarbonate) films exposed to different electron doses have been studied using UV–vis spectroscopy, Fourier transform infrared spectroscopy (FTIR), positron annihilation lifetime spectroscopy, photoluminescence spectroscopy, and scanning electron microscopy (SEM). The obtained UV–vis spectroscopy results showed decrease in optical energy gap, optical activation energy, and increase in number of carbon atoms per cluster with increase in electron dose. The chemical changes in electron irradiated polymers due to chain scission and reconstruction have been observed from FTIR spectroscopy. The correlation of positron lifetime study with optical measurement is obtained, and electron irradiation‐induced microstructural modifications within the polymer is understood. SEM result shows the degradation of Lexan polymer after electron irradiation. The mechanical properties and average molecular weight of Lexan decrease after irradiation, whereas average number of chain scissions per original polymer molecule increases. © 2012 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013
Solid‐state hydrolysis of postconsumer polyethylene terephthalate after plasma treatment
Authors: Mancini Sandro Donnini , Nogueira Alex Rodrigues , Rangel Elidiane Cipriano , da Cruz Nilson Cristino 
Published: May 2012

AbstractPlasma treatments were applied on the surface of postconsumer polyethylene terephthalate (PET) bottles to increase their wettability and hasten the subsequent hydrolysis process. Sixty‐four treatments were tested by varying plasma composition (oxygen and air), power (25–130 W), pressure (50–200 mTorr), and time (1 and 5 min). The best treatment was the one applied in air plasma at 130 W and 50 mTorr for 5 min, as it provided the lowest contact angle, 9.4°. Samples of PET before and after the optimized plasma condition were subjected to hydrolysis at 205°C. Although the treatment changed only a thin surface layer, its influence was evident up to relatively high conversion rates, as the treated samples presented more than 40% higher conversion rates than the untreated ones after 2 h of reaction. Infrared spectroscopy showed that the terephthalic acid obtained from 99% of depolymerization was similar to the commercial product used in PET synthesis. © 2012 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013
Synthesis of epoxy resin–silica nanocomposites provided from perhydropolysilazane as a curing reagent and the precursor of silica domain
Authors: Saito Reiko , Fujii Yosuke , Kumagai Tohru 
Published: May 2012

AbstractEpoxy resin–silica nanocomposites with spherical silica domains with 29.0 nm in diameter in an epoxy resin matrix were synthesized from Bisphenol‐A type epoxide monomer, 2,2‐bis(4‐glycidyloxyphenyl)propane (DGEBA), and perhydropolysilazane (PHPS, [Si2NH]n). The volume fraction of silica domain in the composite varied from 5.4 to 37.8 vol % by varying the feed ratio of PHPS to the epoxide monomer. The reaction mechanism of epoxy group and PHPS was investigated by using glycidyl methacrylate as a model compound of the epoxy monomer by 1H‐nucular magnetic resonance and Fourier transform infrared spectrometry. Ammonia gas provided by the decomposition of PHPS with moisture converted PHPS to silica and cured the epoxy monomer. The curing of epoxy monomer preferably proceeded than the conversion of silica. The addition of 1,4‐diaminobutane drastically accelerated the rate of curing; white and hard epoxy resin–silica nanocomposites were obtained. The good thermal stability of the composite prepared with DGEBA/PHPS/1,4‐diaminobutane was observed by thermogravimetric analysis. © 2012 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013
A clinical and serologic comparison of African American and Caucasian patients with systemic sclerosis
Authors: Steen Virginia , Domsic Robyn T. , Lucas Mary , Fertig Noreen , Medsger Thomas A. 
Published: May 2012

AbstractObjectiveEpidemiology studies suggest that systemic sclerosis (SSc) is more common, occurs at a younger age, and is more severe in African Americans than Caucasians. However, the scleroderma autoantibody profile is very different between these 2 ethnic groups. This study was undertaken to examine the demographic and disease features, frequency and severity of internal organ system involvement, and survival in African American patients compared to Caucasian patients with SSc, giving particular attention to their serum autoantibody profiles.MethodsDemographic features, clinical characteristics, autoantibody profile, organ involvement, and survival were studied in consecutive African American and Caucasian patients with SSc whose visits were recorded between 1972 and 2007 as part of the Pittsburgh Scleroderma Database. The Medsger Severity Score for SSc was used to determine the severity of disease.ResultsAfrican American patients were more likely to have anti–topoisomerase I (anti–topo I), anti–U1 RNP, and anti–U3 RNP autoantibodies. In comparing African American and Caucasian patients with these antibodies, pulmonary fibrosis was found to be more frequent and more severe, and the rate of survival was decreased, in African American patients with anti–topo I antibodies compared to Caucasian patients with anti–topo I. Pulmonary fibrosis was also more severe in the anti–U1 RNP–positive patients, but this was not associated with a difference in survival between African Americans and Caucasians. Anti–U3 RNP was associated with more severe gastrointestinal involvement in African Americans compared to Caucasians.ConclusionAfrican Americans with SSc have more severe disease complications compared to Caucasians with SSc, and this is associated with both the type of autoantibody present and the severity of interstitial lung disease. Thus, it is hoped that early aggressive intervention in African Americans with interstitial lung disease will improve outcomes.
Effect of intensive lipid‐lowering therapy on cardiovascular outcome in patients with and those without inflammatory joint disease
Authors: Semb Anne Grete , Kvien Tore K. , DeMicco David A. , Fayyad Rana , Wun Chuan‐Chuan , LaRosa John C. , Betteridge John , Pedersen Terje R. , Holme Ingar 
Published: May 2012

AbstractObjectiveTo examine the effect of intensive lipid‐lowering therapy on a composite cardiovascular outcome (cardiovascular disease [CVD]), consisting of mortality and morbidity end points, in patients with inflammatory joint disease (rheumatoid arthritis [RA], ankylosing spondylitis [AS], or psoriatic arthritis [PsA]) by post hoc analysis of 2 prospective trials of statins with a secondary end point of CVD outcome (the Treating to New Targets [TNT] and Incremental Decrease in End Points Through Aggressive Lipid Lowering [IDEAL] studies).MethodsOf the 18,889 patients participating in the 2 trials, 199 had RA, 46 had AS, and 35 had PsA. Lipid‐lowering therapy consisted of an intensive regimen of atorvastatin 80 mg or a conventional/low‐dose regimen of atorvastatin 10 mg or simvastatin 20–40 mg. The median duration of followup was nearly 5 years. Changes in lipid levels were examined by analyses of covariance. The effect on CVD was examined by Cox regression analyses, and heterogeneity tests were performed.ResultsPatients with RA and those with AS had lower baseline cholesterol levels than patients without inflammatory joint disease (least squares mean ± SEM 180.7 ± 2.3 mg/dl and 176.5 ± 4.7 mg/dl, respectively, versus 185.6 ± 0.2 mg/dl; P = 0.03 and P = 0.05, respectively). Statin treatment led to a comparable decrease in lipid levels and a 20% reduction in overall risk of CVD in both patients with and those without inflammatory joint disease.ConclusionOur findings indicate that patients with and those without inflammatory joint disease experience comparable lipid‐lowering effects and CVD risk reduction after intensive treatment with statins.
Enhanced suppressor of cytokine signaling 3 in arthritic cartilage dysregulates human chondrocyte function
Authors: van de Loo Fons A. J. , Veenbergen Sharon , van den Brand Ben , Bennink Miranda B. , Blaney‐Davidson Esmeralda , Arntz Onno J. , van Beuningen Henk M. , van der Kraan Peter M. , van den Berg Wim B. 
Published: May 2012

AbstractObjectiveTo determine the expression of suppressor of cytokine signaling 3 (SOCS‐3) in human articular chondrocytes and its functional consequences.MethodsChondrocytes were isolated from the cartilage of patients with osteoarthritis (OA), patients with rheumatoid arthritis (RA), and trauma patients and from the healthy cartilage of patients with a femoral neck fracture. The human chondrocyte cell line G6 and primary bovine chondrocytes were used in validation experiments. SOCS‐3 messenger RNA (mRNA) expression was measured by quantitative polymerase chain reaction, and SOCS‐3 protein levels were determined by Western blotting and immunohistochemical analysis. To ascertain the role of SOCS‐3 in the chondrocyte response to interleukin‐1β (IL‐1β) or lipopolysaccharide (LPS), the expression of SOCS3 was either reduced by small interfering RNA or enhanced by viral transduction.ResultsThe expression of SOCS‐3 mRNA (but not that of SOCS‐1 mRNA) was significantly enhanced in chondrocytes obtained from OA cartilage (mean ± SD ΔCt 3.4 ± 1.0) and RA cartilage (ΔCt 3.4 ± 1.4) compared with cartilage obtained from patients with femoral neck fracture (ΔCt 5.3 ± 1.2). The expression of SOCS3 correlated significantly with that of other genes known to be expressed in arthritic chondrocytes, such as MMP13 (r = 0.743), ADAMTS4 (r = 0.779), and ADAMTS5 (r = 0.647), and an inverse relationship was observed with COL2A1 (r = −0.561). Up‐regulation of SOCS‐3 by IL‐1 in G6 chondrocytes and its spontaneous expression in OA chondrocytes were reduced by mithramycin, a specific inhibitor of transcription factor Sp‐1. Overexpression of SOCS‐3 in bovine chondrocytes reduced IL‐1– and LPS‐induced nitric oxide production and insulin‐like growth factor 1–induced proteoglycan synthesis. Interestingly, a similar impairment of function was observed in OA chondrocytes, which was partially restored by SOCS‐3 gene knockdown.ConclusionThis study demonstrated that both SOCS‐3 mRNA and SOCS‐3 protein are expressed in human arthritic chondrocytes and affect cellular responses involved in cartilage pathology.
Gremlin 1, Frizzled‐related protein, and Dkk‐1 are key regulators of human articular cartilage homeostasis
Authors: Leijten J. C. H. , Emons J. , Sticht C. , van Gool S. , Decker E. , Uitterlinden A. , Rappold G. , Hofman A. , Rivadeneira F. , Scherjon S. , Wit J. M. , van Meurs J. , van Blitterswijk C. A. , Karperien M. 
Published: May 2012

AbstractObjectiveThe development of osteoarthritis (OA) may be caused by activation of hypertrophic differentiation of articular chondrocytes. Healthy articular cartilage is highly resistant to hypertrophic differentiation, in contrast to other hyaline cartilage subtypes, such as growth plate cartilage. The purpose of this study was to elucidate the molecular mechanism responsible for the difference in the propensity of human articular cartilage and growth plate cartilage to undergo hypertrophic differentiation.MethodsWhole‐genome gene‐expression microarray analysis of healthy human growth plate and articular cartilage derived from the same adolescent donors was performed. Candidate genes, which were enriched in the articular cartilage, were validated at the messenger RNA (mRNA) and protein levels and examined for their potential to inhibit hypertrophic differentiation in two models. In addition, we studied a possible genetic association with OA.ResultsPathway analysis demonstrated decreased Wnt signaling in articular cartilage as compared to growth plate cartilage. This was at least partly due to increased expression of the bone morphogenetic protein and Wnt antagonists Gremlin 1, Frizzled‐related protein (FRP), and Dkk‐1 at the mRNA and protein levels in articular cartilage. Supplementation of these proteins diminished terminal hypertrophic differentiation without affecting chondrogenesis in long‐bone explant cultures and chondrogenically differentiating human mesenchymal stem cells. Additionally, we found that single‐nucleotide polymorphism rs12593365, which is located in a genomic control region of GREM1, was significantly associated with a 20% reduced risk of radiographic hip OA in 2 population‐based cohorts.ConclusionTaken together, our study identified Gremlin 1, FRP, and Dkk‐1 as natural brakes on hypertrophic differentiation in articular cartilage. As hypertrophic differentiation of articular cartilage may contribute to the development of OA, our findings may open new avenues for therapeutic intervention.
Natural antibody to apoptotic cell membranes inhibits the proinflammatory properties of lupus autoantibody immune complexes
Authors: Vas Jaya , Grönwall Caroline , Marshak‐Rothstein Ann , Silverman Gregg J. 
Published: May 2012

AbstractObjectiveNaturally arising IgM antibodies (NAb) to apoptotic cell (AC) determinants are present from birth and can be further induced by AC challenge. In systemic lupus erythematosus, lower anti‐AC NAb levels have been associated with higher disease activity. We have recently shown that a prototypical AC‐specific IgM NAb can suppress proinflammatory responses to purified agonists of Toll‐like receptors and block the in vivo induction of IgG immune complex (IC)–induced arthritis. Nuclear antigens, which activate dendritic cells (DCs), form complexes with IgG autoantibody, and these have been implicated in the pathogenesis of autoimmune disease. In this study, we sought to investigate potential roles of such NAb for regulating IC‐mediated activation of DCs, which is believed to be involved in disease initiation and perpetuation.MethodsBone marrow–derived myeloid DCs were stimulated with ICs composed of IgG autoantibody and chromatin or IgG autoantibody and RNA. Outcome was evaluated according to the production of inflammatory cytokines, as determined by enzyme‐linked immunosorbent assay, and the expression of costimulatory molecules (markers of DC activation), as determined by flow cytometry. MAPK activation was evaluated by phospho‐flow analysis and immunofluorescence microscopy.ResultsIgM anti‐AC NAb dose‐dependently suppressed the production of DNA IC– and RNA IC–induced interleukin‐6 and DNA IC–induced tumor necrosis factor α, as well as the RNA IC–induced up‐regulation of CD86 and CD40 on DCs. IgM NAb–mediated inhibition was associated with suppression of IC‐mediated p38 MAPK activation and nuclear localization.ConclusionWe demonstrated a direct in vitro inhibitory effect of IgM NAb on inflammatory responses induced by IgG–nucleic acid ICs. These findings contribute to emerging evidence that regulatory NAb to AC determinants may oppose the influence of pathogenic lupus autoantibody ICs and thereby play roles in the maintenance of immune homeostasis.
Inhibiting HLA–B27 homodimer–driven immune cell inflammation in spondylarthritis
Authors: Payeli Sravan K. , Kollnberger Simon , Marroquin Belaunzaran Osiris , Thiel Markus , McHugh Kirsty , Giles Joanna , Shaw Jacqueline , Kleber Sascha , Ridley Anna , Wong‐Baeza Isabel , Keidel Sarah , Kuroki Kimiko , Maenaka Katsumi , Wadle Andreas , Renner Christoph , Bowness Paul 
Published: May 2012

AbstractObjectiveSpondylarthritides (SpA), including ankylosing spondylitis (AS), are common inflammatory rheumatic diseases that are strongly associated with positivity for the HLA class I allotype B27. HLA–B27 normally forms complexes with β2‐microglobulin (β2m) and peptide to form heterotrimers. However, an unusual characteristic of HLA–B27 is its ability to form β2m‐free heavy chain homodimers (HLA–B272), which, unlike classic HLA–B27, bind to killer cell immunoglobulin‐like receptor 3DL2 (KIR‐3DL2). Binding of HLA–B272 to KIR‐3DL2–positive CD4+ T and natural killer (NK) cells stimulates cell survival and modulates cytokine production. This study was undertaken to produce an antibody to HLA–B272 in order to confirm its expression in SpA and to inhibit its proinflammatory properties.MethodsWe generated monoclonal antibodies by screening a human phage display library positively against B272 and negatively against B27 heterotrimers. Specificity was tested by enzyme‐linked immunosorbent assay (ELISA), surface plasmon resonance (SPR) assay, and fluorescence‐activated cell sorting (FACS) analysis of B272‐expressing cell lines and peripheral blood mononuclear cells (PBMCs) and synovial fluid mononuclear cells (SFMCs) from patients with SpA. Functional inhibition of KIR‐3DL2–B272 interactions was tested using cell lines and PBMCs from patients with SpA.ResultsMonoclonal antibody HD6 specifically recognized recombinant HLA–B272 by ELISA and by SPR assay. HD6 bound to cell lines expressing B272. FACS revealed binding of HD6 to PBMCs and SFMCs from patients with AS but not from controls. HD6 inhibited both the binding of HLA–B272 to KIR‐3DL2 and the survival and proliferation of KIR‐3DL2–positive NK cells. Finally, HD6 inhibited production of the proinflammatory disease–associated cytokine interleukin‐17 by PBMCs from patients with AS.ConclusionThese results demonstrate that antibody HD6 has potential for use in both the investigation and the treatment of AS and other B27‐associated spondylarthritides.