bluuebunny/crossref_metadata_2025_split huggingface dataset:
Preparation and properties of water‐swellable elastomer
Authors: Zhang Yuhong , He Peixin , Zou Qichao , He Benqiao 
Published: June 2004

AbstractA series of water‐swellable elastomers were prepared by blending chlorinated polyethylene (CPE) with poly(acrylic acid–acrylic amide) [P(AA–AM)]. The effect of component on its water‐absorbent properties such as degree of swelling, swelling ratio, and weight loss ratio was discussed. Mechanical behavior of blends was also investigated. The results indicate that swelling rate of CPE/P(AA–AM) was very quick; the blend reached its equilibrium state in only 30 min. The equilibrium swelling ratio increased with increasing amounts of water‐absorbent resin, the greater the amount of P(AA–AM), the higher the swelling degree. The effect of temperature on swelling ratio was very interesting, below 30°C, with an increase of temperature, the swelling ratio of blend increased, but above 30°C, with an increase of temperature, the swelling ratio decreased, indicating that this is a temperature‐sensitive water‐swellable elastomer. The effect of pH of solutions on the swelling behavior showed that water absorption of blends was heavily influenced by pH. The effect of different metal ions on the swelling behavior were also studied and the results showed that the absorption of blends was decreased dramatically with increasing the charge number of the cation, but was not influenced by radius and valence state of the anion. Owing to the compatibility of the amphiphilic graft copolymer (CPE‐g‐PEG), the equilibrium swelling ratio of the blends increased and the weight loss ratio decreased. Adding CPE‐g‐PEG can improve the mechanical behavior of blends. But too much grafted copolymer can worsen the tensile strength of blends. Tensile strength of blends decreased with an increase in P(AA‐AM). After absorbing water, the material's strength is greater than in the dry state. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 93: 1719–1723, 2004
Ring‐opening copolymerization of maleic anhydride with propylene oxide by double‐metal cyanide
Authors: Hua Zhengjiang , Qi Guorong , Chen Shang 
Published: June 2004

AbstractRing‐opening copolymerization of maleic anhydride (MA) with propylene oxide (PO) was successfully carried out by using double‐metal cyanide (DMC) based on Zn3[Co(CN)6]2. The characteristics of the copolymerization are presented and discussed in this article. The structure of the copolymer was characterized with IR and 1H‐NMR. Number‐average molecular weight (Mn) and molecular weight distribution (MWD) of the copolymer were measured by GPC. The results showed that DMC was a highly active catalyst for copolymerization of MA and PO, giving high yield at a low catalyst level of 80 mg/kg. The catalytic efficiency reached 10 kg polymer/g catalyst. Almost alternating copolymer was obtained when monomer charge molar ratio reached MA/PO ≥ 1. The copolymerization can be also carried out in many organic solvents; it was more favorable to be carried in polar solvents such as THF and acetone than in low‐polarity solvents such as diethyl ether and cyclohexane. The proper reaction temperature carried in the solvents was between 90 and 100 °C. The Mn was in the range of 2000–3000, and it was linear with the molar ratio of conversion monomer and DMC catalyst. The reactivity ratio of MA and PO in this reaction system was given by the extended Kelen–Tudos equation: η=[r1+(r2/α)]ξ−(r2/α) at some high monomer conversion. The value of reactivity ratio r1(MA) = 0 for MA cannot be polymerized itself by DMC catalyst, and r2(PO) = 0.286. The kinetics of the copolymerization was studied. The results indicated that the copolymerization rate is first order with respect to monomer concentration. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 93: 1788–1792, 2004
Sequence analysis and fiber properties of a blend of poly(ethylene terephthalate) and poly(ethylene terephthalate‐co‐4,4′‐bibenzoate)
Authors: Min Byung , Kumar Satish , Hibbs Michael R. , Ma Hongming , Collard David M. , Schiraldi David A. 
Published: June 2004

AbstractBlends of poly(ethylene terephthalate) (PET) and poly(ethylene terephthalate‐co‐4,4′‐ bibenzoate) (PETBB) are prepared by coextrusion. Analysis by 13C‐NMR spectroscopy shows that little transesterification occurs during the blending process. Additional heat treatment of the blend leads to more transesterification and a corresponding increase in the degree of randomness, R. Analysis by differential scanning calorimetry shows that the as‐extruded blend is semicrystalline, unlike PETBB15, a random copolymer with the same composition as the non‐ random blend. Additional heat treatment of the blend leads to a decrease in the melting point, Tm, and an increase in glass transition temperature, Tg. The Tm and Tg of the blend reach minimum and maximum values, respectively, after 15 min at 270°C, at which point the blend has not been fully randomized. The blend has a lower crystallization rate than PET and PETBB55 (a copolymer containing 55 mol % bibenzoate). The PET/PETBB55 (70/30 w/w) blend shows a secondary endothermic peak at 15°C above an isothermal crystallization temperature. The secondary peak was confirmed to be the melting of small and/or imperfect crystals resulting from secondary crystallization. The blend exhibits the crystal structure of PET. Tensile properties of the fibers prepared from the blend are comparable to those of PET fiber, whereas PETBB55 fibers display higher performance. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 93: 1793–1803, 2004
Differential versican isoforms and aggrecan expression in the chicken embryo aorta
Authors: Arciniegas Enrique , Neves Carmen Yudith , Candelle Daniel , Parada David 
Published: June 2004

AbstractMembers of the family of large chondroitin sulfate proteoglycans (CSPGs), such as versican and aggrecan, are involved in early heart development, and in the development and progression of atherosclerosis and restenosis. Given the important roles played by versican and aggrecan in such processes, we sought to determine whether these molecules are present in the aortic wall during the advanced stages of chicken embryo development and the endothelial–mesenchymal transformation (EMT). Immunolabeling of serial cryosections revealed versican immunoreactivity around the cells within the intimal thickening, and the cells organized in lamellar and interlamellar cell layers. In contrast, a weak aggrecan immunoreactivity was limited to the cells arranged into lamellar and interlamellar cell layers. Immunolabeling also demonstrated that V2 is the main versican isoform present at the intimal thickening. According to immunoblotting analysis, the aggrecan content was very low in all stages examined, and two versican isoforms (V0 and V2) were present at day 14 of development. We also investigated whether versican isoforms were present during EMT in vitro. Versican immunoreactivity was detected in patches of endothelial cells; in the detaching and migrating cells, and the extracellular matrix (ECM) deposited by them; and in cells that had acquired mesenchymal characteristics. These data indicate that versican and aggrecan have different spatial and temporal patterns of expression, and they have different functions during remodeling of the aortic wall. Also, the different immunoreactivity and immunolocalization patterns observed for versican both in vivo and in vitro, in addition to being associated with the presence of different versican isoforms, may be related to the predominance of the V2 isoform during intimal thickening formation and EMT. © 2004 Wiley‐Liss, Inc.
Polymorphisms in the interferon‐γ/interleukin‐26 gene region contribute to sex bias in susceptibility to rheumatoid arthritis
Authors: Vandenbroeck K. , Cunningham S. , Goris A. , Alloza I. , Heggarty S. , Graham C. , Bell A. , Rooney M. 
Published: June 2004

AbstractObjectiveTo determine whether polymorphisms in the interferon‐γ (IFNγ)/interleukin‐26 (IL‐26; formerly, AK155) gene cluster contribute to sex‐based differential susceptibility to rheumatoid arthritis (RA).MethodsFour microsatellite markers, located in a 118‐kb interval that contains both the IFNγ and IL‐26 genes on chromosome 12q15, were typed in 251 patients with RA and 198 unrelated healthy controls (all of whom lived in Northern Ireland) by means of polymerase chain reaction–based fragment analysis.ResultsMarker D12S2510, which is located 3 kb 3′ from the IL‐26 gene, was significantly associated with RA in women (corrected P [Pcorr] = 0.008, 2 degrees of freedom [2 df]) but not in men (P = 0.99, 2 df). A 3‐marker haplotype, IFNGCA*13;D12S2510*8;D12S2511*9, was inferred that showed significant underrepresentation in women with RA (odds ratio 0.50, 95% confidence interval 0.32–0.78; P = 0.002, Pcorr = 0.03) but not in men with RA.ConclusionOur results demonstrate that common polymorphisms in the IFNγ/IL‐26 gene region may contribute to sex bias in susceptibility to RA, by distorting the propensity of female carriers versus male carriers to contract this disease. These results conform to our recent observations of a role for this gene cluster in sex‐based differential susceptibility to another Th1‐type inflammatory disease, multiple sclerosis.
Endothelin 1 promotes osteoarthritic cartilage degradation via matrix metalloprotease 1 and matrix metalloprotease 13 induction
Authors: Roy‐Beaudry Marjolaine , Martel‐Pelletier Johanne , Pelletier Jean‐Pierre , M'Barek Khatija Nait , Christgau Stephan , Shipkolye Fazool , Moldovan Florina 
Published: June 2004

AbstractObjectiveDegradation of the collagenous extracellular matrix by metalloproteases (MMPs) plays an important role in the pathogenesis of osteoarthritis (OA). Recently, it was suggested that endothelin 1 (ET‐1), a potent vasoconstrictor, may be involved in MMP regulation. This study investigated the role of ET‐1 in OA cartilage degradation.MethodsWe explored ET‐1 expression and synthesis in normal and OA cartilage and synovial membrane by reverse transcription–polymerase chain reaction and immunohistochemistry. MMP‐1 and MMP‐13 gene expression and protein synthesis were investigated using Northern blotting and enzyme‐linked immunosorbent assays. Additionally, ET‐1–induced collagenase activity, type II collagen metabolites, and tissue inhibitor of metalloproteases 1 (TIMP‐1) protein were evaluated.ResultsWe found expression and synthesis of ET‐1, in situ, in both normal and OA cartilage and synovial membrane. We demonstrated that ET‐1 induced gene expression and protein synthesis of both MMP‐1 and MMP‐13. These enzymes were produced in OA chondrocyte cultures, and the production increased in a dose‐dependent manner in the presence of ET‐1. In OA cartilage, ET‐1 also induced type II collagen–derived neoepitopes concomitantly with an increase in collagenase activity and a decrease in TIMP‐1 protein.ConclusionOur results provide strong evidence of the catabolic role of ET‐1 in OA cartilage via MMP‐1 and MMP‐13 up‐regulation. As well, ET‐1 increased the net MMP/TIMP balance and secondarily increased collagen degradation. Hence, ET‐1 becomes an attractive factor to target in the conception of new therapeutic approaches for OA and other diseases in which MMP‐13 and MMP‐1 actions are crucial in tissue alteration.
Hydrostatic pressure modulates proteoglycan metabolism in chondrocytes seeded in agarose
Authors: Toyoda Takashi , Seedhom Bahaa B. , Yao Jian Q. , Kirkham Jennifer , Brookes Steven , Bonass William A. 
Published: June 2004

AbstractObjectiveTo investigate the effect of isolated hydrostatic pressure on proteoglycan metabolism in chondrocytes.MethodsBovine articular chondrocytes cultured in agarose gels were subjected to 5 MPa hydrostatic pressure for 4 hours in either a static or a pulsatile (1 Hz) mode, and changes in glycosaminoglycan (GAG) synthesis, hydrodynamic size, and aggregation properties of proteoglycans and aggrecan messenger RNA (mRNA) levels were determined.ResultsThe application of 5 MPa static pressure caused a significant increase in GAG synthesis of 11% (P < 0.05). Column chromatography showed that this increase in GAG synthesis was associated with large proteoglycans. In addition, semiquantitative reverse transcriptase–polymerase chain reaction showed a 4‐fold increase in levels of aggrecan mRNA (P < 0.01).ConclusionHydrostatic pressure in isolation, which does not cause cell deformation, can affect proteoglycan metabolism in chondrocytes cultured in agarose gels, indicating an important role of hydrostatic pressure in the regulation of extracellular matrix turnover in articular cartilage.
Differential expression of HLA class II genes associated with disease susceptibility and progression in rheumatoid arthritis
Authors: Heldt Christian , Listing Joachim , Sözeri Osman , Bläsing Franca , Frischbutter Stefan , Müller Brigitte 
Published: June 2004

AbstractObjectiveRheumatoid arthritis (RA)–associated HLA class II genes are assumed to promote susceptibility to and/or progression of the disease. Among the various modes of action proposed so far is the effect of the differential expression of HLA class II genes in different types of antigen‐presenting cells on the Th1/Th2 balance. The aim of this study was to investigate the differential expression of genes encoded within the RA–associated HLA–DR4 superhaplotype and within the neutral DR7 and DR9 superhaplotypes.MethodsThe promoters encoded within these 3 haplotypes were first analyzed for sequence polymorphisms. To test for functional consequences, we assumed that the binding of nuclear factors to the promoter elements was correlated with the transcription activity, and we used surface plasmon resonance technology. To that end, oligonucleotides representing the polymorphic regulatory sequences and nuclear extracts from a monocyte cell line and a B cell line were used.ResultsWhile the promoters of the highly polymorphic HLA–DRB1*04, *07, and *09 alleles showed comparable binding of nuclear factors, differential binding was observed for the 2 promoters that drive the relatively nonpolymorphic DRB4 alleles in linkage disequilibrium with DRB1. Interestingly, analysis of RA patients positive for DR4, DR7, and DR9 revealed the segregation of radiographic progression with the stronger of the 2 DRB4 promoters, independent of the DRB1 allele. Moreover, DRB1*04 alleles in RA patients showed a reduced association with the DRB4 splice variant, completely preventing DRB4 expression.ConclusionOur findings represent the first evidence of a correlation between the differential expression of HLA class II genes and both the susceptibility and the progression of RA.
Synovial fluid neutrophils transcribe and express class II major histocompatibility complex molecules in rheumatoid arthritis
Authors: Cross Andrew , Bucknall Roger C. , Cassatella Marco A. , Edwards Steven W. , Moots Robert J. 
Published: June 2004

AbstractObjectiveTo investigate a potential interaction between neutrophils and T cells in rheumatoid arthritis (RA), by defining the optimal conditions for induction of class II major histocompatibility complex (MHC) expression on peripheral blood neutrophils in vitro and investigating the capacity for neutrophils to express class II MHC molecules in RA.MethodsSurface expression of class II MHC and costimulatory molecules by peripheral blood and synovial fluid (SF) neutrophils obtained from healthy controls and patients with RA was measured by flow cytometry and fluorescence microscopy. Intracellular class II MHC protein and messenger RNA (mRNA) were detected by Western blotting and Northern blotting, respectively.ResultsFreshly isolated peripheral blood neutrophils from controls did not express surface class II MHC; expression was induced by culture with appropriate cytokines. Freshly isolated peripheral blood neutrophils from patients with RA expressed mRNA, but there was no surface expression of class II MHC. Freshly isolated SF neutrophils from patients with RA contained high levels of class II MHC mRNA, did not express surface class II MHC, but did have large intracellular amounts of this protein as detected by Western blotting. After culture for 20 hours in vitro, SF neutrophils from RA patients expressed large amounts of surface class II MHC but very low levels of costimulatory molecules CD80 and CD86. Fluorescence microscopy localized surface class II MHC to discrete areas on the neutrophil. Class II MHC–expressing neutrophils stimulated T cell proliferation.ConclusionPeripheral blood neutrophils from patients with RA but not healthy controls express class II MHC mRNA. SF neutrophils in RA synthesize and express large amounts of class II MHC but not costimulatory molecules. This might underlie a novel interaction with T cells that is important in terms of disease pathology.
Investigation of the role of ANKH in ankylosing spondylitis
Authors: Timms A. E. , Zhang Y. , Bradbury L. , Wordsworth B. P. , Brown M. A. 
Published: June 2004

AbstractObjectiveThe ank/ank mouse develops a phenotype similar to ankylosing spondylitis (AS) in humans. ANKH, the human homolog of the mutated gene in the ank/ank mouse, has been implicated in familial autosomal‐dominant chondrocalcinosis and autosomal‐dominant craniometaphyseal dysplasia. This study was undertaken to investigate the role of ANKH in susceptibility to and clinical manifestations of AS.MethodsSequence variants were identified by genomic sequencing of the 12 ANKH exons and their flanking splice sites in 48 AS patients; variants were then screened in 233 patients and 478 controls. Linkage to the ANKH locus was assessed in 185 affected‐sibling‐pair families.ResultsFive single‐nucleotide polymorphisms were identified within the coding region and flanking splice sites. No association between either susceptibility to AS or its clinical manifestations and these novel polymorphisms, or between disease susceptibility and 3 known promoter variants, was seen. No linkage between the ANKH locus and AS was observed. Multipoint exclusion mapping rejected the hypothesis of a locus of a magnitude λ≥1.4 (logarithm of odds score <−2) (equivalent to a genetic contribution of >10% to the AS sibling recurrence risk ratio) within this area contributing to AS.ConclusionThese findings indicate that ANKH is not significantly involved in susceptibility to or clinical manifestations of AS.
Prostaglandin E2 is an enhancer of interleukin‐1β–induced expression of membrane‐associated prostaglandin E synthase in rheumatoid synovial fibroblasts
Authors: Kojima Fumiaki , Naraba Hiroaki , Sasaki Yasuharu , Beppu Moroe , Aoki Haruhito , Kawai Shinichi 
Published: June 2004

AbstractObjectiveMembrane‐associated prostaglandin E synthase (mPGES) is a recently identified terminal enzyme of the arachidonic acid cascade, which converts PGH2 to PGE2 in rheumatoid arthritis synovial fibroblasts (RASFs). This study was undertaken to investigate factors regulating the expression of mPGES.MethodsRASFs were treated with interleukin‐1β (IL‐1β), indomethacin, NS‐398, rofecoxib, or meloxicam. The effects of PGE2 and selective agonists for PGE2 receptor subtypes (EP1, EP2, EP3, and EP4) were also studied. Expression of mPGES messenger RNA (mRNA) and protein was measured by Northern and Western blot analysis, respectively. EP receptor mRNA expression in RASFs was determined by reverse transcriptase–polymerase chain reaction. Production of PGE2 and cAMP was measured by enzyme‐linked immunosorbent assay.ResultsThe enhanced expression of mPGES mRNA and protein in IL‐1β–stimulated RASFs was attenuated by the addition of indomethacin, NS‐398, rofecoxib, or meloxicam. This reduction of expression was reversed by PGE2. IL‐1β–induced PGES activity, measured by conversion of PGH2 to PGE2, was decreased by rofecoxib. EP2 and EP4 receptor mRNA was detected in RASFs. EP2 and EP4 agonists, as well as PGE2, restored the inhibitory effect of rofecoxib on mPGES expression. The effect of PGE2 was mimicked by forskolin, a direct activator of adenylate cyclase. Intracellular cAMP was increased by IL‐1β and was inhibited by rofecoxib.ConclusionEnhancement of mPGES expression by PGE2 via the EP2/EP4 receptors with an increase in cAMP may play an important role in articular inflammation in patients with RA. It also seems that cyclooxygenase 2 (COX‐2) inhibitors decrease PGE2 production not only by direct inhibition of COX‐2, but also by reducing mPGES expression in activated RASFs.
Subgrouping of fibromyalgia patients on the basis of pressure‐pain thresholds and psychological factors
Authors: Giesecke Thorsten , Williams David A. , Harris Richard E. , Cupps Thomas R. , Tian Xiaoming , Tian Thomas X. , Gracely Richard H. , Clauw Daniel J. 
Published: June 2004

AbstractObjectiveAlthough the American College of Rheumatology (ACR) criteria for fibromyalgia are used to identify individuals with both widespread pain and tenderness, individuals who meet these criteria are not a homogeneous group. Patients differ in their accompanying clinical symptoms, as well as in the relative contributions of biologic, psychological, and cognitive factors to their symptom expression. Therefore, it seems useful to identify subsets of fibromyalgia patients on the basis of which of these factors are present. Previous attempts at identifying subsets have been based solely on psychological and cognitive features. In this study, we attempt to identify patient subsets by incorporating these features as well as the degree of hyperalgesia/tenderness, which is a key neurobiologic feature of this illness.MethodsNinety‐seven individuals meeting the ACR criteria for fibromyalgia finished the same battery of self‐report and evoked‐pain testing. Analyzed variables were obtained from several domains, consisting of 1) mood (evaluated by the Center for Epidemiologic Studies Depression Scale [for depression] and the State‐Trait Personality Inventory [for symptoms of trait‐related anxiety]), 2) cognition (by the catastrophizing and control of pain subscales of the Coping Strategies Questionnaire), and 3) hyperalgesia/tenderness (by dolorimetry and random pressure‐pain applied at suprathreshold values). Cluster analytic procedures were used to distinguish subgroups of fibromyalgia patients based on these domains.ResultsThree clusters best fit the data. Multivariate analysis of variance (ANOVA) confirmed that each variable was differentiated by the cluster solution (Wilks' λ [degrees of freedom 6,89] = 0.123, P < 0.0001), with univariate ANOVAs also indicating significant differences (all P < 0.05). One subgroup of patients (n = 50) was characterized by moderate mood ratings, moderate levels of catastrophizing and perceived control over pain, and low levels of tenderness. A second subgroup (n = 31) displayed significantly elevated values on the mood assessments, the highest values on the catastrophizing subscale, the lowest values for perceived control over pain, and high levels of tenderness. The third group (n = 16) had normal mood ratings, very low levels of catastrophizing, and the highest level of perceived control over pain, but these subjects showed extreme tenderness on evoked‐pain testing.ConclusionThese data help support the clinical impression that there are distinct subgroups of patients with fibromyalgia. There appears to be a group of fibromyalgia patients who exhibit extreme tenderness but lack any associated psychological/cognitive factors, an intermediate group who display moderate tenderness and have normal mood, and a group in whom mood and cognitive factors may be significantly influencing the symptom report.