Face motion form at learning influences the time course of face spatial frequency processing during test.

Studies that use static faces suggest that facial processing follows a coarse-to-fine sequence; i.e., holistic precedes featural processing, due to low and high spatial frequencies (LSF, HSF) transmitting holistic/global and featural/local information respectively. Although recent studies have focused on the role of facial movement in holistic facial processing, it is unclear whether moving faces have the same processing mechanism as static ones, especially in the time course of processing. The current study uses the event-related potential technique to investigate this issue by manipulating the facial format at study and face spatial frequency during the test. ERP results showed that the P1 amplitude was increased by LSF faces relative to HSF ones, using both moving and static study faces, with the former larger than the latter. The N170 amplitude was more sensitive to HSF than LSF faces when only static study faces were used, while the P2 amplitude was more sensitive to LSF faces regardless of the facial study format. The above results were not modulated by the race of the faces. These results favor the view that regardless of face race, moving study faces promote holistic processing during the earliest stage of face recognition. Furthermore, holistic processing is observed to be the same for both static and moving study faces at a later stage associated with more in-depth processing. It is evident that facial motion should be factored into further studies of face recognition, given the distinctions between holistic and featural processing for moving and static study faces.

Optimal Consensus Control for Continuous-Time Linear Multiagent Systems: A Dynamic Event-Triggered Approach.

This article investigates the optimal consensus problem for general linear multiagent systems (MASs) via a dynamic event-triggered approach. First, a modified interaction-related cost function is proposed. Second, a dynamic event-triggered approach is developed by constructing a new distributed dynamic triggering function and a new distributed event-triggered consensus protocol. Consequently, the modified interaction-related cost function can be minimized by applying the distributed control laws, which overcomes the difficulty in the optimal consensus problem that seeking the interaction-related cost function needs all agents' information. Then, some sufficient conditions are obtained to guarantee optimality. It is shown that the developed optimal consensus gain matrices are only related to the designed triggering parameters and the desirable modified interaction-related cost function, relaxing the constraint that the controller design requires the knowledge of system dynamics, initial states, and network scale. Meanwhile, the tradeoff between optimal consensus performance and event-triggered behavior is also considered. Finally, a simulation example is provided to verify the validity of the designed distributed event-triggered optimal controller.

STS1 and STS2 Phosphatase Inhibitor Baicalein Enhances the Expansion of Hematopoietic and Progenitor Stem Cells and Alleviates 5-Fluorouracil-Induced Myelosuppression.

STS1 and STS2, as the protein phosphatases that dephosphorylate FLT3 and cKIT, negatively regulate the self-renewal and differentiation of hematopoietic stem and progenitor cells (HSPCs). To obtain the small molecule inhibitors of STS1/STS2 phosphatase activity used to expand HSPCs both in vitro and in vivo, we establish an in vitro phosphatase assay using the recombinant proteins of the STS1/STS2 histidine phosphatase (HP) domain, by which we screened out baicalein (BC) as one of the effective inhibitors targeting STS1 and STS2. Then, we further demonstrate the direct binding of BC with STS1/STS2 using molecular docking and capillary electrophoresis and verify that BC can restore the phosphorylation of FLT3 and cKIT from STS1/STS2 inhibition. In a short-term in vitro culture, BC promotes profound expansion and enhances the colony-forming capacity of both human and mouse HSPCs along with the elevation of phospho-FLT3 and phospho-cKIT levels. Likewise, in vivo administration with BC significantly increases the proportions of short-term hematopoietic stem cells (ST-HSCs), multipotent progenitors (MPPs) and especially long-term HSCs (LT-HSCs) in healthy mouse bone marrow and increases the numbers of colony-forming units (CFU) formed by HSPCs as well. More importantly, pre-administration of BC significantly enhances the survival of mice with lethal 5-fluorouracil (5-FU) injection due to the alleviation of 5-FU-induced myelosuppression, as evidenced by the recovery of bone marrow histologic injury, the increased proportions of LT-HSCs, ST-HSCs and MPPs, and enhanced colony-forming capacity. Collectively, our study not only suggests BC as one of the small molecule candidates to stimulate HSPC expansion both in vitro and in vivo when needed in either physiologic or pathologic conditions, but also supports STS1/STS2 as potential therapeutic drug targets for HSPC expansion and hematopoietic injury recovery.

Mechanical Stretch Promotes Neurite Outgrowth of Primary Cultured Dorsal Root Ganglion Neurons via Suppression of Semaphorin 3A-Neuropilin-1/Plexin-A1 Signaling.

Significant attempts have been made to promote neuronal extension and migration in nerve development and regeneration. Although mechanical stretch induces persistent elongation of the axon, the underlying molecular mechanisms are not yet clear. Some axonal guidance cues secreted in the growth cone that affect the axonal growth could attract or repel axons in neurite connection. As semaphorin 3A (Sema3A) is an important repulsion guidance molecule, inhibition of Sema3A has been postulated to promote neuronal development. In this study, the effects of mechanical stretch on dorsal root ganglion neuronal growth and the underlying mechanisms were investigated by assessing the extension direction, neurite length, cell body size, mitochondrial membrane potential, and the expression of Sema3A and its receptors. Our results showed that cell viability significantly increased at tensile strains of 2.5, 5, and 10% for 4 h, with the most prominent effect at 5% tensile strain. Moreover, neurons migrated closer to the stretching direction at 5% tensile strain (0-12 h), while the neurons of the control group moved in a disorderly manner. Furthermore, Sema3A-Neuropilin-1/Plexin-A1 signaling pathway was found to be suppressed after mechanical stretch at 5% tensile strain for 4 h by immunofluorescence staining, immunoprecipitation, and western blot assay. Finally, a Sema3A-SiRNA (SiRNA = small interfering RNA) treatment led to remarkable guidance growth in the stretch-grown neurons. Importantly, there was significant decrease of repulsive cue Sema3A expression and remarkable increase of attractive molecule Netrin-1 expression after mechanical stretching treatment, which jointly promoted neurite outgrowth. This study provides a promising new approach for the development of mechanical stretching therapy or guidance factor-related drugs in injured neuronal regeneration.

Data-driven model-free resilient speed control of an autonomous surface vehicle in the presence of actuator anomalies.

This paper is concerned with the resilient speed control of an autonomous surface vehicle (ASV) in the presence of actuator anomalies. A data-driven model-free resilient speed control method is presented based on available input and output data only with pulse-width-modulation inputs. Specifically, a data-driven neural predictor is designed to learn the unknown system dynamics of the speed control system of the ASV. Then, a resilient speed control law is designed based on the learned dynamics obtained from the neural network predictor, where a cost function is designed for selecting the optimal duty cycle for the motor. The stability of the data-driven neural predictor is analyzed by using input-state stability (ISS) theory. The advantage of the developed data-driven model-free resilient control method is that the optimal speed control performance can be achieved in the presence of actuator anomalies without any modeling process. Simulation results show the learning ability of the data-driven neural predictor and the effectiveness of the proposed data-driven model-free resilient speed control method for the ASV subject to actuator anomalies.

The Time Sequence of Face Spatial Frequency Differs During Working Memory Encoding and Retrieval Stages.

Previous studies have found that P1 and P2 components were more sensitive to configural and featural face processing, respectively, when attentional resources were sufficient, suggesting that face processing follows a coarse-to-fine sequence. However, the role of working memory (WM) load in the time course of configural and featural face processing is poorly understood, especially whether it differs during encoding and retrieval stages. This study employed a delayed recognition task with varying WM load and face spatial frequency (SF). Our behavioral and ERP results showed that WM load modulated face SF processing. Specifically, for the encoding stage, P1 and P2 were more sensitive to broadband SF (BSF) faces, while N170 was more sensitive to low SF (LSF) and BSF faces. For the retrieval stage, P1 on the right hemisphere was more sensitive to BSF faces relative to HSF faces, N170 was more sensitive to LSF faces than HSF faces, especially under the load 1 condition, while P2 was more sensitive to high SF (HSF) faces than HSF faces, especially under load 3 condition. These results indicate that faces are perceived less finely during the encoding stage, whereas face perception follows a coarse-to-fine sequence during the retrieval stage, which is influenced by WM load. The coarse and fine information were processed especially under the low and high load conditions, respectively.

Leader-Following Consensus of Multiple Uncertain Euler-Lagrange Systems via Fully Distributed Event-Triggered Adaptive Fuzzy Control.

This article deals with the leader-following consensus problem of multiple uncertain Euler-Lagrange systems with unknown nonlinear dynamics. By introducing a dynamic compensator for each agent, a fully distributed control strategy is developed based on the fuzzy approximation approach, which is independent of any priori global information associated with the communication topology. Meanwhile, a distributed event-triggering mechanism (ETM) is designed such that each agent broadcasts its states only when an event occurs. It is shown that with the proposed ETM, the leader-following consensus is achieved with aperiodic intermittent communication and Zeno behavior is excluded by contradiction. Moreover, the consensus tracking errors converge to small sets around the origin. Finally, an example is provided to illustrate the effectiveness of the obtained theoretical results.

Search for Cosmic-Ray Boosted Sub-GeV Dark Matter at the PandaX-II Experiment.

We report a novel search for the cosmic-ray boosted dark matter using the 100 tonne·day full dataset of the PandaX-II detector located at the China Jinping Underground Laboratory. With the extra energy gained from the cosmic rays, sub-GeV dark matter particles can produce visible recoil signals in the detector. The diurnal modulations in rate and energy spectrum are utilized to further enhance the signal sensitivity. Our result excludes the dark matter-nucleon elastic scattering cross section between 10^{-31} and 10^{-28} cm^{2} for dark matter masses from 0.1 MeV/c^{2} to 0.1 GeV/c^{2}, with a large parameter space previously unexplored by experimental collaborations.

Event-Triggered Adaptive Fuzzy Output-Feedback Control for Nonstrict-Feedback Nonlinear Systems With Asymmetric Output Constraint.

This article addresses the event-triggered adaptive fuzzy output-feedback control problem for a class of nonstrict-feedback nonlinear systems with asymmetric and time-varying output constraints, as well as unknown nonlinear functions. By designing a linear observer to estimate the unmeasurable states, a novel event-triggered adaptive fuzzy output-feedback control scheme is proposed. The barrier Lyapunov function (BLF) and the error transformation technique are used to handle the output constraint under a completely unknown initial tracking condition. It is shown that with the proposed control scheme, all the solutions of the closed-loop system are semiglobally bounded, and the tracking error converges to a small set near zero, while the output constraint is satisfied within a predetermined finite time, even when the constraint condition is violated initially. Moreover, with the proposed event-triggering mechanism (ETM), the Zeno behavior can be strictly ruled out. An example is finally provided to demonstrate the effectiveness of the proposed control method.

Search for Light Dark Matter-Electron Scattering in the PandaX-II Experiment.

We report constraints on light dark matter through its interactions with shell electrons in the PandaX-II liquid xenon detector with a total 46.9 tonnes/day exposure. To effectively search for these very low energy electron recoils, ionization-only signals are selected from the data. 1821 candidates are identified within an ionization signal range between 50 and 75 photoelectrons, corresponding to a mean electronic recoil energy from 0.08 to 0.15 keV. The 90% C.L. exclusion limit on the scattering cross section between the dark matter and electron is calculated with systematic uncertainties properly taken into account. Under the assumption of point interaction, we provide the world's most stringent limit within the dark matter mass range from 15 to 30 MeV/c^{2}, with the corresponding cross section from 2.5×10^{-37} to 3.1×10^{-38} cm^{2}.

Dark Matter Search Results from the PandaX-4T Commissioning Run.

We report the first dark matter search results using the commissioning data from PandaX-4T. Using a time projection chamber with 3.7 tonne of liquid xenon target and an exposure of 0.63 tonne·year, 1058 candidate events are identified within an approximate nuclear recoil energy window between 5 and 100 keV. No significant excess over background is observed. Our data set a stringent limit to the dark matter-nucleon spin-independent interactions, with a lowest excluded cross section (90% C.L.) of 3.8×10^{-47} cm^{2} at a dark matter mass of 40 GeV/c^{2}.

KIAA1217 Promotes Epithelial-Mesenchymal Transition and Hepatocellular Carcinoma Metastasis by Interacting with and Activating STAT3.

The survival and prognosis of hepatocellular carcinoma (HCC) are poor, mainly due to metastasis. Therefore, insights into the molecular mechanisms underlying HCC invasion and metastasis are urgently needed to develop a more effective antimetastatic therapy. Here, we report that KIAA1217, a functionally unknown macromolecular protein, plays a crucial role in HCC metastasis. KIAA1217 expression was frequently upregulated in HCC cell lines and tissues, and high KIAA1217 expression was closely associated with shorter survival of patients with HCC. Overexpression and knockdown experiments revealed that KIAA1217 significantly promoted cell migration and invasion by inducing epithelial-mesenchymal transition (EMT) in vitro. Consistently, HCC cells overexpressing KIAA1217 exhibited markedly enhanced lung metastasis in vivo. Mechanistically, KIAA1217 enhanced EMT and accordingly promoted HCC metastasis by interacting with and activating JAK1/2 and STAT3. Interestingly, KIAA1217-activated p-STAT3 was retained in the cytoplasm instead of translocating into the nucleus, where p-STAT3 subsequently activated the Notch and Wnt/ß-catenin pathways to facilitate EMT induction and HCC metastasis. Collectively, KIAA1217 may function as an adaptor protein or scaffold protein in the cytoplasm and coordinate multiple pathways to promote EMT-induced HCC metastasis, indicating its potential as a therapeutic target for curbing HCC metastasis.

Ameliorative effects of Qingganjiuwei powder, a traditional Mongolian medicine, against CCl4-induced liver fibrosis in rats.

ETHNOPHARMACOLOGICAL RELEVANCE: Qingganjiuwei powder (QGJWS) is a well-known traditional drug containing nine kinds of medicinal materials. This drug is commonly used in the Inner Mongolia region and exerts remarkable clinical effects on hepatic protection. AIM OF THE STUDY: To investigate whether QGJWS inhibits liver fibrosis in rats and to reveal its potential mechanisms. METHODS: Liver fibrosis model was induced by CCl4 for 8 weeks in SD rats. Next, rats were intragastrically administered quantum satis doses of QGJWS (0.525, 1.575, 4.725 g/kg per day) or Silymarin (SIL; 120 mg/kg per day) for 8 weeks. Afterwards, the rats were sacrificed, and serum aminotransferase (ALT and AST) levels, histopathological changes as well as the mRNA and protein expression of matrix metalloproteinase 2 (MMP2), MMP9, tissue inhibitor of metalloproteinase1 (TIMP1), collagen type Ⅰ(COL1), α-smooth muscle actin (α-SMA), combined with phosphorylation levels of extracellular signal-regulated kinase (ERK), C-Jun amino-terminal kinases (JNKs) and stress-activated protein kinase-2 (p38) protein in liver tissues were measured in each groups, respectively. RESULTS: The symptoms and signs of the model rats were consistent with the diagnostic criteria of liver fibrosis. By contrast, treatment with QGJWS clearly improved the general condition of rats. Also, the morphology and structure of liver can be ameliorated, there are fewer hepatocyte necrosis and lymphocytic infiltration and pseudolobuli in QGJWS treatment groups as demonstrated by histopathological analysis, thus helping bring about lower METAVIR scores. QGJWS administration also dramatically decreased serum ALT and AST levels. Further immunohistochemistry, western blotting and Real-Time PCR analysis revealed that QGJWS significantly enhanced the mRNA and protein expression of MMP2, MMP9, and downregulated the expression levels of COL1, TIMP1 and α-SMA. Furthermore, QGJWS reduced the activities of mitogen-activated protein kinases (MAPKs) pathway in liver by inhibited the phosphorylation of ERK, JNKs and p38 proteins. CONCLUSIONS: QGJWS offers notable protection against CCl4-induced liver fibrosis in rats, which may be due to its ability to inhibited the MAPKs signaling pathway.

Fabrication of poly-sulfosalicylic acid film decorated pure carbon fiber as electrochemical sensing platform for detection of theophylline.

In this work, we integrated the superiority of good conductivity, large surface area of carbon fibers and the catalytic property, good biocompatibility of polymer sulfosalicylic acid to construct a novel electrochemical sensor to detect theophylline in drug analysis. The morphology of nanocomposite was characterized by scanning electron microscopy (SEM). The polymerization between monomers was observed by Fourier transform infrared spectroscopy (FTIR). The composite between carbon material and polymer was verified by Raman spectrum. Under the optimal experimental conditions, the concentration of theophylline (0.6∼137 µM) and the peak current value revealed a good linear relationship and the limit of detection as low as 0.2 µM. In addition, the proposed sensor exhibits repeatability, stability and ease of selectivity.

Aligned graphene/silk fibroin conductive fibrous scaffolds for guiding neurite outgrowth in rat spinal cord neurons.

Graphene, as a highly conducting material, incorporated into silk fibroin (SF) substrates is promising to fabricate an electroactive flexible scaffold toward neural tissue engineering. It is well known that aligned morphology could promote cell adhesion and directional growth. The purpose of this study was to develop aligned conductive scaffolds made of graphene and SF (G/SF) by electrospinning technique for neural tissue engineering applications. The physicochemical characterization of scaffolds revealed that the mechanical and electrochemical property of aligned G/SF scaffolds continually raised with the increasing contents of graphene (A0% G/SF, A1% G/SF, A2% G/SF, and A3% G/SF), but the mechanical property descended when the graphene concentration reached to 4% (the A4% G/SF group). The results of the cell experiment in vitro indicated that all the aligned G/SF scaffolds were no neurotoxic to primary cultured spinal cord neurons. In addition, the neurite elongation in all aligned groups was significantly enhanced by the upregulation of Netrin-1 expression compared to them in the control group. Thus, A3% G/SF scaffolds not only possessed the optimal property based on the mechanical and electrochemical performances but also displayed the beneficial capability to neurite outgrowth, which might perform a suitable candidate to successfully scaffold electrically active tissues during neural regeneration or engineering.

SIRT1 Inhibits High Shear Stress-Induced Apoptosis in Rat Cortical Neurons.

INTRODUCTION: Sirtuin1 (SIRT1), one of NAD+-dependent protein deacetylases, is proved to be neuroprotective in aging diseases, but its effect on neuronal apoptosis has not been clarified. To investigate the role of SIRT1 in inhibiting neuronal apoptosis, SIRT1 was interfered or overexpressed in cortical neurons. METHODS: We exerted overloading laminar shear stress with 10 dyn/cm2 for 4, 8, and 12 h on neurons to cause cortical neuronal apoptosis, and the apoptosis percentage was tested by TUNEL assay. The adenovirus plasmids containing SIRT1 RNA interference or SIRT1 wild type gene were transfected into neurons before shear stress loading. SIRT1 mRNA and protein level were tested by Real-time PCR, immunofluorescence and western blots assay. RESULTS: SIRT1 was primarily expressed in nucleus of cortical neurons, and its mRNA level was significantly increased after 4 h stimulation. SIRT1 RNAi cortical neurons had higher TUNEL positive cells, while SIRT1 overexpression significantly decreased the percentage of died cells induced by shear stress compared to control group. CONCLUSIONS: SIRT1 plays a neuroprotective role in shear stress induced apoptosis and could be as potential pharmacological targets against neuronal degeneration in future.

Promotion of Neuronal Guidance Growth by Aminated Graphene Oxide via Netrin-1/Deleted in Colorectal Cancer Signaling.

Promotion of neurite outgrowth and synapse formation is a key step for nervous tissue regeneration. It is important for finding a new biomaterial to guide neuron growth to target neurons. Aminated graphene oxide (NH2-GO) displays electrical properties and dispersibility, which may change the surface charge of neurons and further activate neuronal excitement. However, the molecular guidance mechanism of NH2-GO on neurite outgrowth is seldom reported. In this study, we compared the role of NH2-GO on the spinal cord neurons and cortical neurons. Results indicated that the proper concentrations were at 2 and 4 µg/mL as determined by the CCK-8 assay. Notably, NH2-GO (2 and 4 µg/mL) improved the dispersibility and strengthened the effect of the composite material. In addition, it enables biocompatibility and efficient guidance of growth performance, which is not neurotoxic for neuronal outgrowth under these two concentrations. More interestingly, NH2-GO at 2 µg/mL induced both marked neurite elongation and increased branches in cortical neurons, but there is no significant change of neurite length and branches in spinal cord neurons. Further, the fluorescence intensity and mRNA level of Netrin-1 and DCC (Deleted in Colorectal Cancer) were both enhanced by NH2-GO at 2 µg/mL. Moreover, the function of Netrin-1 and DCC were activated more significantly by NH2-GO at 2 µg/mL in cortical neurons than that of spinal cord neurons. When RhoA was inhibited by the C3 exoenzyme, phosphorylated Rac1 and Cdc42 expression decreased significantly. Thus, NH2-GO at 2 µg/mL could influence Netrin-1/DCC signaling and the downstream RhoGTPase pathway, which may be preferred to guide the neurite growth in cortical neurons. It will provide a promising approach for the development of novel therapeutic methods of nerve regeneration.

A novel electrochemical enzyme biosensor for detection of 17ß-estradiol by mediated electron-transfer system.

An extremely sensitive enzyme sensor for detection of 17ß-estradiol based on electropolymerized L-lysine molecules on a glassy carbon electrode (GCE) modified with critic acid@graphene (CA-GR) and cross-linked with laccase enzyme has been developed in this work. As the laccase immobilization, glutaraldehyde was chosen as cross-linker through the groups reactions. The novel enzyme sensor could recognize and determinate 17ß-estradiol effectively. The morphology of the enzyme modified electrode was characterized by transmission electron microscopy (TEM) and electron microscopy (SEM). The amino interaction between cross-linker and enzyme was characterized by Fourier transform infrared spectroscopy (FTIR). Under the optimal experimental conditions, good linear relationships were achieved in the range of 4 × 10-13 - 5.7 × 10-11 M and a limit of detection as low as 1.3 × 10-13 M. Moreover, the enzyme sensor exhibited good reproducibility, stability and high selectivity to 17ß-estradiol. Excellent performance was showed in the human urine samples analysis, thus confirming great prospect for further application in clinic diagnosis and biological research.

Potential diagnostic role of diffusion tensor imaging in early-stage osteonecrosis of the femoral head.

The present study aimed to explore the potential diagnostic role of diffusion tensor magnetic resonance imaging (DTI) in the early stage of modified corticosteroid-induced osteonecrosis of the femoral head (ONFH). A total of 20 beagles were randomly classified (1:1) into either an experimental group (LM), which were intramuscularly injected with lipopolysaccharide (LPS) and methylprednisolone (MPS) on three consecutive days, or control (CON) group, which were injected with saline. Magnetic resonance imaging (MRI) and DTI were performed at pre-induction and 8 and 12 weeks post-induction. Apparent diffusion coefficient (ADC) values in the range of interest in the femoral head were quantified using DTI. Proximal femora were examined for ONFH at 8 and 12 weeks. The results demonstrated that ONFH developed in four beagles at 8 weeks and in six beagles at 12 weeks, whereas no ONFH was detected in the CON group. No abnormalities were detected by MRI and DTI, and no mortality occurred. In beagles with ONFH in the LM group, the ADC values were 4.7±0.2×10-4 and 4.8±0.3×10-4 mm2/sec at 8 and 12 weeks, respectively, which were significantly increased compared with the CON group (2.5±0.3×10-4 and 2.4±0.3×10-4 mm2, respectively) and the LM group without ONFH (2.6±0.4×10-4 and 2.4±0.3×10-4 mm2, respectively) (P<0.05). The results of the present study indicated that intramuscular injection of LPS and MPS may lead to early-stage ONFH in beagles. As such, the detection of locally elevated ADC values in the femoral head may aid in the early diagnosis of ONFH.

Correlation between sialic acid levels in the synovial fluid and the radiographic severity of knee osteoarthritis.

Osteoarthritis (OA) is associated with the presence of inflammation. Sialic acid (SA), an acetylated derivative of neuraminic acid, is reported to be a useful biomarker of inflammation. The aim of the present study was to investigate the correlation between SA levels in the serum and synovial fluid (SF) and radiographic severity in patients with knee OA. A total of 234 patients with knee OA were recruited for the study, as well as 20 patients that had suffered a knee injury or fracture (without knee OA) and 160 healthy controls. Radiological grading of OA in the knee was conducted according to the Kellgren-Lawrence (KL) grading system. SA levels in the serum and SF were measured using Warren's thiobarbituric acid assay. The results demonstrated that knee OA patients exhibited significantly elevated levels of serum SA when compared with the healthy controls, and also significantly elevated levels of SF SA when compared with the knee fracture patients. Higher SA levels in the SF were identified in knee OA patients with KL grade 4 as compared with patients with KL grade 2 or 3. In addition, OA patients of KL grade 3 had significantly higher SA levels in the SF as compared with patients with KL grade 2 (P<0.01). The SA levels in the SF of the knee OA patients positively correlated with the KL grades (r=0.353; P<0.01). However, there was no significant correlation identified between serum SA levels and KL grade. Therefore, SA levels in the SF positively correlated with the radiographic severity of OA, thus, SA levels in the SF may serve as a biomarker for the progression of OA.