ObjectiveTo make clear exercise combined with Shenghui Tang interferes in acetylcholine receptor （M1AChR） to improve mitochondrial autophagy and enhance cognition of Alzheimer's disease （AD） model rats through the adenylate activated protein kinase （AMPK）/mammalian target of rapamycin （mTOR） signaling pathway. MethodsForty-eight male SD rats of SPF grade were randomly divided into a blank group， a model group， a Shenghui Tang group （9.3 g·kg^-1）， an exercise group， an exercise + Shenghui Tang group （9.3 g·kg^-1）， and a rapamycin group （1.5 mg·kg^-1）. Except for the blank group， the rat model of AD was constructed by injecting amyloid beta （Aβ_1-42） into hippocampus stereotaxically. The exercise group received treadmill exercise for 4 weeks， while the Shenghui Tang group received intragastric administration for 4 weeks， and the exercise + Shenghui Tang group received treadmill exercise and intragastric administration of Shenghui Tang for 4 weeks simultaneously. After the intervention， the Morris water maze test was used to detect the learning and memory ability. Spontaneous behavior was observed in the open field test. The pathological structure of hippocampal neurons was observed by NISSl staining. The expression level of M1AChR in hippocampus was detected by immunohistochemistry （IHC）. The autophagy ultrastructure of hippocampal neurons was observed by transmission electron microscopy. The apoptosis rate was evaluated by terminal deoxynucleotidyl transferase dUTP nick end labeling （TUNEL）. The expression of Beclin1 and microtubule-associated protein light chain 3β （LC3β） was detected by immunofluorescence （IF）. The protein expression of M1AChR， AMPK， p-AMPK， mTOR， Beclin1， LC3β， and chelate 1 （SQSTM1/p62） in hippocampus was detected by Western blot. ResultsCompared with the blank group， the model group exhibited significantly increased platform escape latency on the fifth day （P<0.01） and significantly decreased activity distance in the target quadrant and times of crossing the platform （P<0.01）. The total movement distance in the open field， the time of movement in the central area， and the average speed obviously decreased （P<0.05）. The arrangement of nerve cells in hippocampus CA1 region was dispersed， and the numbers of Nissl bodies and M1AChR positive cells significantly decreased （P<0.01）. The expression of TUNEL positive cells was significantly increased （P<0.01）. The typical autophagic lysosomal structure decreased. The protein expression of M1AChR， p-AMPK/AMPK， p-mTOR/mTOR， Beclin1， LC3Ⅱ/Ⅰ in hippocampus was significantly decreased （P<0.01）， and the protein expression of p62 was significantly increased （P<0.01）. Compared with the model group， the exercise + Shenghui Tang group exhibited obviously improved space exploration and positioning navigation ability （P<0.05， P<0.01）. The total movement distance in the open field， the time of movement in the central area， and the average speed of movement significantly increased （P<0.01）. The number of Nissl bodies significantly increased （P<0.01）. The number of M1AChR positive cells in hippocampus was significantly increased （P<0.01）. The expression of TUNEL positive cells was significantly decreased （P<0.01）. The protein expression of M1AChR， p-AMPK/AMPK， p-mTOR/mTOR， Beclin1， LC3Ⅱ/Ⅰ in hippocampus was significantly increased （P<0.01）， while the protein expression of p62 was significantly decreased （P<0.01）. Compared with the exercise + Shenghui Tang group， the Shenghui Tang group and the exercise group showed significantly increased platform escape latency on the fifth day （P<0.01） and obviously decreased activity distance in the target quadrant and times of crossing the platform （P<0.05， P<0.01）. The total movement distance in the open field， the time of movement in the central area， and the average speed of movement significantly decreased （P<0.01）. The number of Nissl bodies and the number of M1AChR positive cells significantly decreased （P<0.01）. The expression of TUNEL positive cells was obviously increased （P<0.05）. Ultrastructure of the hippocampal region showed decreased autophagy level. The protein expression of M1AChR， p-AMPK/AMPK， p-mTOR/mTOR， LC3Ⅱ/Ⅰ in the hippocampus was obviously decreased in the Shenghui Tang group （P<0.05， P<0.01）， while the protein expression of p62 was significantly increased （P<0.01）. In the exercise group， the protein expression of M1AChR， p-AMPK/AMPK， Beclin1， and LC3Ⅱ/Ⅰ was obviously decreased （P<0.05， P<0.01）， while the protein expression of p-mTOR/mTOR and p62 was significantly increased （P<0.01）. ConclusionExercise combined with traditional Chinese medicine can enhance the expression of M1AChR in the hippocampus of AD model rats， induce autophagy through the AMPK/mTOR signaling pathway， and improve the learning and memory ability of AD rats.

BACKGROUND:The most common complication of traumatic femoral neck fractures after internal fixation is femoral head necrosis.Currently,many studies have reported on the risk factors that affect the occurrence and development of postoperative femoral head necrosis,but there is still a lack of tools to predict the risk of femoral head necrosis after internal fixation of femoral neck fractures.OBJECTIVE:To develop a predictive model that estimates the risk of femoral head necrosis shortly after patients with femoral neck fractures receive cannulated screw internal fixation.METHODS:A retrospective analysis reviewed clinical records of 172 patients who underwent cannulated screw internal fixation for femoral neck fractures at Department of Orthopedics of Mianyang Central Hospital from January 2013 to June 2023.Patients were categorized into two groups based on the presence or absence of femoral head necrosis within one year post-operation:the necrosis group and the non-necrosis group.Univariate analysis,Lasso regression,and multivariate Logistic regression techniques were employed to identify the determinants of femoral head necrosis.A nomogram prediction model was constructed using R language's"rms"package,version 4.0.The receiver operating characteristic curve was used to evaluate the discriminatory ability of the model.The Hosmer-Lemeshow test was used to evaluate the goodness of fit of the model,and the decision curve analysis was used to determine its clinical application benefits.Internal validation of the study was conducted using the Bootstrap method,involving 1 000 repeated samplings.To delve deeper into the primary factors influencing femoral head necrosis post-internal fixation of the femoral neck,this paper employed the SHAP method for data set analysis.RESULTS AND CONCLUSION:(1)The risk factors leading to femoral head necrosis in the short term after cannulated screw fixation of femoral neck fractures include:smoking,diabetes,Garden classification,fracture line location,reduction quality,age,and operation time.(2)The prediction model demonstrated robust performance,evidenced by an area under the curve of 0.940(95％Confidence Interval:0.903 to 0.977),indicating a high level of prediction accuracy.The model achieved a sensitivity of 90.2％and a specificity of 87.6％,indicating that its diagnostic performance was stable.The Hosmer-Lemeshow goodness-of-fit test yielded a chi-square value of 6.593 with a P-value of 0.581,confirming that the model's predictions closely align with the observed outcomes.(3)The calibration curve of the model also performed well,and its overall trend was very close to the ideal curve,further proving the high accuracy of the model.(4)The internal validation was carried out by the Bootstrap method with 1 000 repeated samplings,and the area under the curve of the model internal validation was still as high as 0.939,proving that the model had good stability.(5)Through the decision curve,it is found that within the probability threshold range of 1％to 92％,the model can obtain the maximum net benefit value.(6)The SHAP analysis results show that among the risk factors analyzed in this study,the location of the fracture line serves as the most significant predictor of femoral head necrosis following internal fixation with cannulated screws in femoral neck fractures,and subcapital fractures are extremely prone to femoral head necrosis after surgery.(7)It is concluded that the validated prediction model demonstrates strong discriminative power and reliability,offering practical clinical utility.It serves as a useful reference tool for short-term risk assessment of femoral head necrosis following internal fixation of femoral neck fractures.

BACKGROUND:The most common complication of traumatic femoral neck fractures after internal fixation is femoral head necrosis.Currently,many studies have reported on the risk factors that affect the occurrence and development of postoperative femoral head necrosis,but there is still a lack of tools to predict the risk of femoral head necrosis after internal fixation of femoral neck fractures.OBJECTIVE:To develop a predictive model that estimates the risk of femoral head necrosis shortly after patients with femoral neck fractures receive cannulated screw internal fixation.METHODS:A retrospective analysis reviewed clinical records of 172 patients who underwent cannulated screw internal fixation for femoral neck fractures at Department of Orthopedics of Mianyang Central Hospital from January 2013 to June 2023.Patients were categorized into two groups based on the presence or absence of femoral head necrosis within one year post-operation:the necrosis group and the non-necrosis group.Univariate analysis,Lasso regression,and multivariate Logistic regression techniques were employed to identify the determinants of femoral head necrosis.A nomogram prediction model was constructed using R language's"rms"package,version 4.0.The receiver operating characteristic curve was used to evaluate the discriminatory ability of the model.The Hosmer-Lemeshow test was used to evaluate the goodness of fit of the model,and the decision curve analysis was used to determine its clinical application benefits.Internal validation of the study was conducted using the Bootstrap method,involving 1 000 repeated samplings.To delve deeper into the primary factors influencing femoral head necrosis post-internal fixation of the femoral neck,this paper employed the SHAP method for data set analysis.RESULTS AND CONCLUSION:(1)The risk factors leading to femoral head necrosis in the short term after cannulated screw fixation of femoral neck fractures include:smoking,diabetes,Garden classification,fracture line location,reduction quality,age,and operation time.(2)The prediction model demonstrated robust performance,evidenced by an area under the curve of 0.940(95％Confidence Interval:0.903 to 0.977),indicating a high level of prediction accuracy.The model achieved a sensitivity of 90.2％and a specificity of 87.6％,indicating that its diagnostic performance was stable.The Hosmer-Lemeshow goodness-of-fit test yielded a chi-square value of 6.593 with a P-value of 0.581,confirming that the model's predictions closely align with the observed outcomes.(3)The calibration curve of the model also performed well,and its overall trend was very close to the ideal curve,further proving the high accuracy of the model.(4)The internal validation was carried out by the Bootstrap method with 1 000 repeated samplings,and the area under the curve of the model internal validation was still as high as 0.939,proving that the model had good stability.(5)Through the decision curve,it is found that within the probability threshold range of 1％to 92％,the model can obtain the maximum net benefit value.(6)The SHAP analysis results show that among the risk factors analyzed in this study,the location of the fracture line serves as the most significant predictor of femoral head necrosis following internal fixation with cannulated screws in femoral neck fractures,and subcapital fractures are extremely prone to femoral head necrosis after surgery.(7)It is concluded that the validated prediction model demonstrates strong discriminative power and reliability,offering practical clinical utility.It serves as a useful reference tool for short-term risk assessment of femoral head necrosis following internal fixation of femoral neck fractures.

Background/Aims: Regorafenib is recommended by guidelines and trials as a sequential second-line therapy following progression on first-line sorafenib or lenvatinib in hepatocellular carcinoma (HCC). However, efficacy is limited, highlighting the urgent need to screen suitable patients and develop sensitization strategies. Methods: Acquired sorafenib- or lenvatinib-resistant (SR or LR) HCC cell lines and organoids were established. Genome-wide CRISPR library screen was performed in SR or LR cell strains to identify synthetic lethal targets of regorafenib. RNA-seq and FITC-regorafenib efflux assay were used to elucidate ERBB3-driven downstream signaling. Preclinical mouse models of cell line- and patient-derived xenografts and clinical cohorts of HCC patients were employed to validate the efficacy of ERBB3-guided patient stratification. Results: Screening with CRISPR library, we showed that inhibition of ERBB3 was synthetic lethal with regorafenib in SR or LR cell strains and organoids. Mechanistically, SR or LR triggered feedback activation of ERBB3 signaling and mediated regorafenib efflux via ERBB3-HIF1A-ABCB1 cascade pathway, limiting sensitivity to regorafenib. Moreover, ERBB3-low tumors following SR or LR exhibited significant sensitivity to regorafenib, suggesting its potential as a predictive biomarker to screen optimal candidates for sequential therapy. Seribantumab, an ERBB3-targeting monoclonal antibody, inhibited ERBB3-HIF1A-ABCB1 cascade, and its combination with regorafenib exerted marked synergistic anti-tumor effects on ERBB3-high tumors resistant to sorafenib or lenvatinib both in vitro and in vivo. Conclusions This study revealed that ERBB3 was a key resistance factor driving limited efficacy to sequential regorafenib, but also an effective therapeutic target whose inhibition enhanced regorafenib sensitivity after SR or LR.

Objective To understand mosquito density, species composition, and seasonal variations around the Beijing Capital International Airport(BCIA)and provide scientific evidence for mosquito-borne disease prevention and control. Methods Meteorological data were collected from 2016 to 2022, and mosquito density was monitored at seven surveillance sites around the BCIA from May to October each year using CO2-baited mosquito traps to analyze the relationship between mosquito density and meteorological factors. Results In total,68 518 female mosquitoes were captured, with a mosquito density of 10.20 per light · hour. The dominant species was Culex pipiens pallens(73.90%), followed by Aedes albopictus(9.71%)and Ae. vexans(9.29%);the mosquito density was highest in 2016(14.8 per light·hour)and lowest in 2022(4.46 per light·hour). Significant statistical differences were observed in mosquito density among different species(F=18.118, P<0.05). The density of Cx. pipiens pallens and other mosquito species showed a mutually exclusive trend; the peak of mosquito density varied based on years and habitats, with significant statistical differences in mosquito density among different habitats(F=8.504, P<0.05). The highest mosquito density was observed near the Wenyu River(21.50 per light·hour), whereas the lowest was recorded at the BCIA construction site(2.44 per light· hour). The monthly average temperature(r=0.595), monthly average highest temperature(r=0.575), and monthly average lowest temperature(r=0.624)showed moderate positive correlations, whereas the monthly average air pressure(r=-0.484)showed a moderate negative correlation. The monthly average minimum temperature was included in the regression model(F=25.575, P<0.000), and the equation Y=1.029X4-8.181 was used. The monthly average air pressure 2 months prior(b=-2.418, β=-1.619, P<0.05)and the monthly average relative humidity(b=-0.739, β=-1.201, P<0.05)significantly negatively predicted the mosquito density. Notably, the regression equation used was y=2526.170+(-2.418)X9+(-0.739)X13. The exposure-response analysis revealed that the density of mosquitoes was not linearly related to the average monthly air pressure, rainfall, and duration of sunshine. Conclusions The dominant mosquito species around the BCIA was Cx. pipiens pallens, Ae. albopictus, and Ae. vexans. During the control of Cx. pipiens pallens, the impact on other mosquito species must also be considered. Environmental management, breeding sites, and scientific use of pesticides should be prioritized based on the activity periods of mosquitoes. Further studies on mosquitoes and meteorological factors should be conducted to provide references and novel avenues for mosquito control.

Objective To investigate the capacity of municipal and county-level Centers for Disease Control (CDC) in Shandong Province for γ radionuclides in food as well as gross α and gross β in drinking water, and to provide evidence for strengthening radiological laboratories. Method Data regarding radioactive detection capacity were collected from 16 prefecture-level cities and 136 county-level CDCs. Chi-square test and Fisher's exact tests were used to compare capacity differences across regions and between cities with and without nuclear power plants. Correlation analysis was used to evaluate the spatial equity of gross α and gross β detection capacity for drinking water. Result The detection capacity of gross α and gross β in drinking water varied significantly among counties (χ²=81.026, P<0.001），no significant difference was found between coastal and inland cities (χ²=2.021，P>0.155); Cities with nuclear power plants showed better detection capacity (χ²=20.253，P<0.01). The detection capacity for γ radionuclides in food was primarily concentrated in the prefecture-level cities that host nuclear power plants. Conclusion The overall detection capacity for radioactivity in drinking water was acceptable but spatially uneven. The capacity for monitoring radioactive contamination in food was generally weak. It is necessary to strengthen capacity building at the grassroots level.

Peripheral nerve injury (PNI) severs peripheral connections and induces profound reorganization of primary somatosensory (S1) and motor (M1) cortical maps, a dynamic process that critically shapes the extent and quality of functional recovery. Brain-derived neurotrophic factor (BDNF) has emerged as a central molecular hub linking the initial peripheral insult to subsequent central plastic changes. This review systematically examines BDNF-mediated cortical remodeling following PNI, with a particular emphasis on its spatiotemporally specific regulatory mechanisms and the therapeutic opportunities they present. Immediately after PNI, deafferented cortical territories undergo rapid functional silencing and, over time, become progressively encroached upon by adjacent intact representations. This maladaptive reorganization—characterized by sensory map fusion and motor compensatory invasion—actively impedes successful reinnervation and optimal recovery. Such phenomena have been consistently documented in both non-human primate models and human fMRI studies, spanning sensory and motor modalities. Motor remapping is also prominently observed in facial nerve injury and chronic nerve compression models, underscoring the universality of these plastic changes. Notably, a range of interventions including regional local anesthesia, auditory-tactile substitution, and guided tactile imagery can effectively mitigate this aberrant remodeling, revealing promising avenues for the therapeutic modulation of cortical plasticity during critical post-injury windows. BDNF coordinates post-PNI cortical remodeling through three mechanistically interconnected pathways. First, BDNF drives dendritic and axonal growth via TrkB receptor signaling: retrogradely transported axonal signaling endosomes integrate CREB-dependent transcriptional programs with mTOR-mediated local protein synthesis to bolster dendritic arborization and axonal elongation, while BDNF-induced Limk1 translation precisely fine-tunes actin cytoskeletal dynamics, thereby stabilizing dendritic spine morphology. Second, BDNF governs GABAergic interneuron maturation and perineuronal net formation through the JNK signaling cascade, thereby acting as a “plasticity brake” that preserves the delicate excitatory/inhibitory balance and constrains indiscriminate, maladaptive rewiring. Third, BDNF robustly potentiates NMDAR-dependent long-term potentiation (LTP) by elevating NMDA channel open probability and increasing synaptic receptor density, thus tightly coupling structural remodeling with functional synaptic strengthening. Concurrently, long-term depression pathways are subject to modulation, with NMDAR antagonism exerting time-dependent, bidirectional effects that vary with the post-injury phase. Superimposed on these mechanisms, the functionally antagonistic actions of proBDNF/p75NTR (favoring pruning and growth cone collapse) and mature BDNF/TrkB (promoting survival and stabilization) add further layers of regulatory complexity, highlighting the absolute necessity for precise spatiotemporal control in any therapeutic strategy. Extending our previous experimental findings, we introduce a “cortical reclamation threshold” model. In this framework, early upregulation of BDNF-TrkB signaling enhances inhibitory tone to restrict cortical encroachment by neighboring intact regions, whereas delayed but precisely timed BDNF delivery following surgical nerve repair actively facilitates the reclamation of the original, deafferented cortical maps by regenerating afferent fibers. Importantly, the common BDNF Val66Met polymorphism may significantly modulate individual thresholds, providing a biologically grounded rationale for patient stratification and personalized timing of intervention. Despite this mechanistic promise, clinical translation faces considerable hurdles. These include inherently poor pharmacokinetics of BDNF, severely limited penetration across the blood-brain barrier, dose-dependent neurotoxicity mediated through the p75NTR receptor, and the overarching dual-edged nature of BDNF signaling, which can simultaneously promote both adaptive and maladaptive plasticity. Emerging delivery platforms——including engineered exosomes, polymeric nanoparticles, cryogel microcarriers, and adeno-associated virus (AAV)-based gene therapy——offer potential solutions, but all require rigorous pharmacokinetic, toxicological, and functional validation. Future research priorities should encompass: (1) comprehensive single-cell and spatial transcriptomic mapping to resolve BDNF cellular sources and real-time signaling dynamics across distinct cortical layers and cell types; (2) genotype-stratified dose-response studies to establish safe, effective, and personalized delivery protocols; and (3) large-scale multicenter clinical trials that seamlessly integrate BDNF-targeted interventions with multimodal rehabilitation strategies, such as repetitive transcranial magnetic stimulation and mirror therapy, with longitudinal neuroimaging serving as a biomarker for cortical reclamation. By systematically addressing these priorities, we aim to transform BDNF from a critical endogenous regulator into a precisely controllable and titratable therapeutic target, ultimately enabling a paradigm shift from mere structural repair to true functional neural reconstruction following PNI.

OBJECTIVE To identify the active components of Desmodium styracifolium （Osb.） Merr. extract （DME） against cholestatic liver injury （CLI）， and to verify its target and molecular mechanism， so as to provide scientific evidence for the clinical application of D.styracifolium （Osb.） Merr. and the development of new hepatoprotective agents.METHODS High-performance liquid chromatography was applied to establish fingerprints of 19 batches of DME， followed by similarity evaluation and identification of common peaks. An in vitro CLI model was constructed by lithocholic acid （LCA）-induced injury in HepG2 cells to evaluate the in vitro protective effect of DME against CLI. Spearman correlation analysis， grey relational analysis and partial least-squares regression analysis were adopted to investigate the spectrum-effect relationship of DME against CLI and preliminarily screen the core active components. Molecular docking and surface plasmon resonance technology were used to predict and verify the binding capacity between core active components and farnesoid X receptor （FXR）. qRT-PCR， Western blot and immunofluorescence staining tests were performed to validate the influences of core active components on the expression of molecules related to FXR/bile salt export pump （BSEP） pathway in CLI model cells.RESULTS A total of 12 common peaks were calibrated in the fingerprints of 19 batches of DME， and the similarity values were all above 0.990. Four common peaks were identified， namely peak 6 （schaftoside）， peak 7 （isoorientin）， peak 11 （isoschaftoside） and peak 12 （isovitexin）. DME at 80 μg/mL exerted the optimal protective effect on CLI-model cells， and the cell viability reached （75.66±4.60）% after 24 h of treatment. Spectrum-effect analysis revealed that schaftoside possessed the strongest correlation with the anti-CLI activity of DME and served as the core active component. Target prediction and validation results showed that the binding energy between schaftoside and FXR was －8.1 kcal/mol， and the equilibrium dissociation constant was 27.3 μmol/L. Mechanistic experiments demonstrated that 100 μmol/L schaftoside significantly elevated the expression levels of FXR and BSEP， and mRNA of their encoded genes Nr1h4 ， Abcb11 in CLI-model cells （ P ＜0.05）.CONCLUSIONS Schaftoside may be the core active component of DME against CLI， and its mechanism may be related to the activation of FXR/BSEP pathway.

BACKGROUND:Flap transplantation technique is a commonly used surgical procedure for the treatment of severe tissue defects,but postoperative flap necrosis is easily triggered by ischemia-reperfusion injury.Therefore,it is still an important research topic to improve the survival rate of transplanted flaps. OBJECTIVE:To review the pathogenesis and latest treatment progress of flap ischemia-reperfusion injury. METHODS:CNKI,WanFang Database and PubMed database were searched for relevant literature published from 2014 to 2024.The search terms used were"flap,ischemia-reperfusion injury,inflammatory response,oxidative stress,Ca2+overload,apoptosis,mesenchymal stem cells,platelet-rich plasma,signaling pathways,shock wave,pretreatment"in Chinese and English.After elimination of irrelevant literature,poor quality and obsolete literature,77 documents were finally included for review. RESULTS AND CONCLUSION:Flap ischemia/reperfusion injury may be related to pathological factors such as inflammatory response,oxidative stress response,Ca2+overload,and apoptosis,which can cause apoptosis of vascular endothelial cells,vascular damage and microcirculation disorders in the flap,and eventually lead to flap necrosis.Studies have found that mesenchymal stem cell transplantation,platelet-rich plasma,signaling pathway modulators,shock waves,and pretreatment can alleviate flap ischemia/reperfusion injuries from different aspects and to varying degrees,and reduce the necrosis rate and necrosis area of the grafted flap.Although there are many therapeutic methods for skin flap ischemia/reperfusion injury,a unified and effective therapeutic method has not yet been developed in the clinic,and the advantages and disadvantages of various therapeutic methods have not yet been compared.Most of the studies remain in the stage of animal experiments,rarely involving clinical observations.Therefore,a lot of research is required in the future to gradually move from animal experiments to the clinic in order to better serve the clinic.

With the deepening understanding of the pathogenesis of osteoarthritis (OA), therapeutic strategies targeting oxidative stress in chondrocytes have gradually become a research hotspot. This article summarizes the important role of oxidative stress in the development of OA, pointing out that it is closely related to chondrocyte senescence, inflammatory cascade reaction, and cartilage matrix degradation. Given the central role of oxidative stress in the pathological process of OA, inhibiting oxidative stress and the generation of reactive oxygen species (ROS) is considered the key to alleviating chondrocyte damage and senescence, and preventing the progression of OA. Although some progress has been made in current OA research, there are still many challenges, such as the in-depth understanding of the etiology of OA and the limited selection of therapeutic drugs. Future research will focus on a more comprehensive understanding of the mechanism of oxidative stress in OA, exploring new biomarkers and therapeutic targets, and developing new drugs or treatment methods targeting oxidative stress pathways. These efforts are expected to bring more effective treatment options to OA patients, thereby improving their quality of life and prognosis.
Humans ; Oxidative Stress ; Osteoarthritis/pathology* ; Chondrocytes/pathology* ; Animals ; Reactive Oxygen Species/metabolism*