Objective. Long noncoding RNAs (lncRNAs) play crucial regulatory roles in diverse biologic processes, but knowledge of lncRNAs in osteoarthritis (OA) is limited. The aim of this study was to identify lncRNA expression in articular cartilage and to explore the function of cartilage injury-related lncRNAs (lncRNA-CIR) in OA.Methods. To identify lncRNAs specifically expressed in OA cartilage, we compared the expression of lncRNAs in OA cartilage with that in normal cartilage using microarray and quantitative polymerase chain reaction (qPCR) analyses. In OA cartilage, lncRNA-CIR was specifically, differentially, and highly expressed. The function of lncRNA-CIR was determined by silencing and overexpression in vitro. Extracellular matrix (ECM)-related molecules were detected by qPCR, Western blot, and immunofluorescence analyses.Results. Up to 152 lncRNAs were found to be differentially expressed (>8-fold) in OA and normal cartilage (82 lncRNAs more highly expressed and 70 less highly expressed in OA cartilage than in normal cartilage). A specific differentially expressed lncRNA-CIR was selected according to the results of the higher expression in OA cartilage and OA chondrocytes. The expression of lncRNA-CIR increased in chondrocytes with in vitro treatment with interleukin-1␤ and tumor necrosis factor ␣. Silencing of lncRNA-CIR by small interfering RNA promoted the formation of collagen and aggrecan and reduced the expression of matrixdegrading enzymes, such as MMP13 and ADAMTS5. The expression of collagen and aggrecan was reduced, whereas the expression of matrix-degrading enzymes was increased, after overexpression of lncRNA-CIR.Conclusion. The results indicate that lncRNA-CIR contributes to ECM degradation and plays a key role in the pathogenesis of OA. We propose that lncRNA-CIR could be used as a potential target in OA therapy.Osteoarthritis (OA) is a degenerative joint disease characterized by degradation of articular cartilage, thickening of subchondral bone, and formation of osteophytes (1). OA is associated with age-related loss of homeostatic balance. Cartilage cellularity in OA is reduced by chondrocyte death, and chondrocytes are stimulated by cytokines and growth factors to a catabolic and abnormal differentiation that leads to degradation of the extracellular matrix (ECM) (2-5). Degradation of the ECM is complicated, for it involves genetic, developmental, biochemical, and biomechanical factors. The molecular mechanisms involved in the maintenance of articular cartilage have been characterized in order to develop new therapeutic interventions (6,7).The human transcriptome comprises not only protein-coding messenger RNAs (mRNAs), but also a large amount of non-protein-coding transcripts that have structural, regulatory, or unknown functions (8). Although studies of small noncoding RNAs (microRNAs, consisting of 18-200 nucleotides) have dominated the field of RNA biology in recent years (9-11), multiple studies have indicated that promising new molecules, namely, long noncoding RNAs (lncRNAs),

Anisotropic tough hydrogels are of great importance in biomedical fields. Tough poly(vinyl alcohol) (PVA) hydrogels with anisotropic porous structure and mechanical properties are obtained with a facile directional freezing-thawing (DFT) technique. The PVA gels have an aligned porous structure, with long aligned channels in the direction parallel to the freezing direction and pores with similar sizes in the perpendicular direction. The degree of crystallinity of the freeze-dried PVA hydrogels increases with number of DFT cycles, and it can reach 55.8%. The PVA hydrogels have excellent mechanical properties, as exhibited by the high tensile strengths (0.3-1.2 MPa), medium moduli (0.03-0.10 MPa) and high fracture energies (160-420 J m À2 ) of the gels with solid contents of 10-12%. More importantly, the gels exhibit significant anisotropy in the mechanical properties, and their tensile strengths, moduli and fracture energies are higher in the perpendicular direction than those in the parallel direction. Anisotropic mechanical behaviors can also be found in the cyclic tensile tests of the PVA hydrogels. The anisotropic mechanical properties of the DFT PVA hydrogels could be attributed to the oriented arrangement of crystalline regions along the direction perpendicular to the direction of freezing.

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Most chemiluminescence (CL) reactions usually generate only one-step CL, which is rarely dependent on the highly reactive and biologically/environmentally important hydroxyl radicals ( • OH). Here, we show that an unprecedented two-step CL can be produced by the carcinogenic tetrachloro-1,4-benzoquinone (also known as p -chloranil) and H 2 O 2 , which was found to be well-correlated to and directly dependent on its two-step metal-independent production of • OH. We proposed that • OH-dependent formation of quinone-dioxetane and electronically excited carbonyl species might be responsible for this unusual two-step CL production by tetrachloro-1,4-benzoquinone/H 2 O 2 . This is a unique report of a previously undefined two-step CL-producing system that is dependent on intrinsically formed • OH. These findings may have potential applications in detecting and quantifying • OH and the ubiquitous polyhalogenated aromatic carcinogens, which may have broad biological and environmental implications for future research on these types of important species.

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Ergothioneine (2-mercaptohistidine trimethylbetaine) is a naturally occurring amino acid analogue found in up to millimolar concentrations in several tissues and biological fluids. However, the biological functions of ergothioneine remain incompletely understood. In this study, we investigated the role of ergothioneine in copper-induced oxidative damage to DNA and protein, using two copper-containing systems: Cu(II) with ascorbate and Cu(II) with H(2)O(2) [0.1 mM Cu(II), 1 mM ascorbate, and 1 mM H(2)O(2)]. Oxidative damage to DNA and bovine serum albumin was measured as strand breakage and protein carbonyl formation, respectively. Ergothioneine (0.1-1.0 mM) provided strong, dose-dependent protection against oxidation of DNA and protein in both copper-containing systems. In contrast, only limited protection was observed with the purported hydroxyl radical scavengers, dimethyl sulfoxide and mannitol, even at concentrations as high as 100 mM. Ergothioneine also significantly inhibited copper-catalyzed oxidation of ascorbate and competed effectively with histidine and 1,10-phenanthroline for binding of cuprous copper, but not cupric copper, as demonstrated by UV-visible and low-temperature electron spin resonance techniques. We conclude that ergothioneine is a potent, natural sulfur-containing antioxidant that prevents copper-dependent oxidative damage to biological macromolecules by forming a redox-inactive ergothioneine-copper complex.

Osteoarthritis (OA) of the temporomandibular joint (TMJ) is associated with dental biomechanics. A major change during OA progression is the ossification of the osteochondral interface. This study investigated the formation, radiological detectability, and mechanical property of the osteochondral interface at an early stage, the pathogenesis significance of which in OA progression is of clinical interest and remains elusive for the TMJ. Unilateral anterior crossbite (UAC) was performed on 6-wk-old rats as we previously reported. TMJs were harvested at 4, 12, and 20 wk. The progression of TMJ OA was evaluated using a modified Osteoarthritis Research Society International (OARSI) score system. Osteochondral interface was investigated by quantifying the thickness via von Kossa staining of histological slices and in vivo calcium deposition by calcein injection. Tissue ossification was imaged by micro-computed tomography (CT). Mechanical properties were measured at nanoscale using dynamic indentation. Time-dependent TMJ cartilage lesions were elicited by UAC treatment. Geometric change of the condyle head and increased value of the OARSI score were evident in UAC TMJs. At the osteochondral interface, there was not only enhanced deep-zone cartilage calcification but also calcium deposition at the osseous boundary. The thickness, density, and stiffness of the osteochondral interface were all significantly increased. The enhanced ossification of the osteochondral interface is a joint outcome of the aberrant deeper cartilage calcification at the superior region and promoted formation of subchondral cortical bone at the inferior region. The micro-CT detectable ossification from an early stage thus is of diagnostic significance. Although the environment of the cartilage and subchondral bone could be changed due to the stiffness of the interface, whether or not the stiffened interface would accelerate OA progress remains to be confirmed. With that evidence, the osteochondral interface could be a new diagnostic and therapeutic target of the mechanically initiated OA in the TMJ.