Exploring m6A-linked aging genes in osteoarthritis and broad cancer spectrum: Prospects for diagnostic and therapeutic advancements.

Osteoarthritis (OA) is a prevalent degenerative joint disease that significantly impacts individuals and healthcare systems worldwide. However, the exploration of N6-methyladenosine (m6A)-related aging genes in OA pathogenesis remains largely underexplored. This study aimed to elucidate the role of m6A-related aging genes in OA and to develop a robust diagnostic model based on their expression profiles. Leveraging publicly available gene expression datasets, we conducted consensus clustering to categorize OA into distinct subtypes, guided by the expression patterns of m6A-related aging genes. Utilizing XGBoost, a cutting-edge machine learning approach, we identified key diagnostic genes and constructed a predictive model. Our investigation extended to the immune functions of these genes, shedding light on potential therapeutic targets and underlying regulatory mechanisms. Our analysis unveiled specific OA subtypes, each marked by unique expression profiles of m6A-related aging genes. We pinpointed a set of pivotal diagnostic genes, offering potential therapeutic avenues. The developed diagnostic model exhibited exceptional capability in distinguishing OA patients from healthy controls. To corroborate our computational findings, we performed quantitative real-time polymerase chain reaction analyses on two cell lines: HC-OA (representing adult osteoarthritis cells) and C-28/I2 (representative of normal human chondrocytes). The gene expression patterns observed were consistent with our bioinformatics predictions, further validating our initial results. In conclusion, this study underscores the significance of m6A-related aging genes as promising biomarkers for diagnosis and prognosis, as well as potential therapeutic targets in OA. Although these findings are encouraging, further validation and functional analyses are crucial for their clinical application.

Histological characteristics of exercise-induced skeletal muscle remodelling.

This study aims to analyse the pathological features of skeletal muscle injury repair by using rats to model responses to different exercise intensities. Eighty-four rats were randomly divided into five groups for treadmill exercise. The short-term control, low-intensity, medium-intensity and high-intensity groups underwent gastrocnemius muscle sampling after 6, 8 and 12 weeks of exercise. The long-term high-intensity group underwent optical coherence tomography angiography and sampling after 18 weeks of exercise. RNA sequencing was performed on the muscle samples, followed by the corresponding histological staining. Differentially expressed genes were generally elevated at 6 weeks in the early exercise stage, followed by a decreasing trend. Meanwhile, the study demonstrated a negative correlation between time and the gene modules involved in vascular regulation. The modules associated with muscle remodelling were positively correlated with exercise intensity. Although the expression of many genes associated with common angiogenesis was downregulated at 8, 12 and 18 weeks, we found that muscle tissue microvessels were still increased, which may be closely associated with elevated sFRP2 and YAP1. During muscle injury-remodelling, angiogenesis is characterized by significant exercise time and exercise intensity dependence. We find significant differences in the spatial distribution of angiogenesis during muscle injury-remodelling, which be helpful for the future achievement of spatially targeted treatments for exercise-induced muscle injuries.

NAMPT encapsulated by extracellular vesicles from young adipose-derived mesenchymal stem cells treated tendinopathy in a "One-Stone-Two-Birds" manner.

BACKGROUND: Tendinopathy is the leading sports-related injury and will cause severe weakness and tenderness. Effective therapy for tendinopathy remains limited, and extracellular vesicles (EVs) derived from adipose tissue-derived mesenchymal stem cells (ADMSCs) have demonstrated great potential in tendinopathy treatment; however, the influence of aging status on EV treatment has not been previously described. RESULTS: In this study, it was found that ADMSCs derived from old mice (ADMSCold) demonstrated remarkable cellular senescence and impaired NAD+ metabolism compared with ADMSCs derived from young mice (ADMSCyoung). Lower NAMPT contents were detected in both ADMSCold and its secreted EVs (ADMSCold-EVs). Advanced animal experiments demonstrated that ADMSCyoung-EVs, but not ADMSCold-EVs, alleviated the pathological structural, functional and biomechanical properties in tendinopathy mice. Mechanistic analyses demonstrated that ADMSCyoung-EVs improved cell viability and relieved cellular senescence of tenocytes through the NAMPT/SIRT1/PPARγ/PGC-1α pathway. ADMSCyoung-EVs, but not ADMSCold-EVs, promoted phagocytosis and M2 polarization in macrophages through the NAMPT/SIRT1/Nf-κb p65/NLRP3 pathway. The macrophage/tenocyte crosstalk in tendinopathy was influenced by ADMSCyoung-EV treatment and thus it demonstrated "One-Stone-Two-Birds" effects in tendinopathy treatment. CONCLUSIONS: This study demonstrates an effective novel therapy for tendinopathy and uncovers the influence of donor age on curative effects by clarifying the detailed biological mechanism.

Risk factors analysis and nomogram construction for postoperative pulmonary infection in elderly patients with hip fractures.

PURPOSE: The purpose of this study was to predict the probability of postoperative pulmonary infection in elderly patients with hip fractures by developing and validating a precise model. METHODS: The clinical data of 1008 elderly hip fracture patients undergoing surgical treatment in Shanghai Tenth Peoples' Hospital were retrospectively selected. A univariate analysis and multivariate regression were used to analyze the independent risk factors for postoperative pulmonary infection in elderly patients with hip fractures. A risk prediction model was established, and a nomogram was drawn. The area under the ROC curve and Hosmer‒Lemeshow test were used to evaluate the predictive effect of the model. RESULTS: The multivariate regression analysis indicated that age > 73, time from fracture to surgery (d) > 4 days, smoking, ASA ≥ III level, COPD, hypoproteinemia, red cell distribution width > 14.8%, mechanical ventilation time > 180 min, and stay in the ICU were independent risk factors for postoperative pulmonary infection in elderly patients. The AUCs of the model were 0.891 and 0.881, 0.843, respectively, in the two verification groups. For the Hosmer‒Lemeshow test, the P values were 0.726 in the modeling group and 0.497 and 0.231 in the verification group (P > 0.05). CONCLUSION: Overall, this study uncovered different independent risk factors for postoperative pulmonary infection in patients with hip fractures. The nomogram can effectively predict the occurrence of postoperative pulmonary infection.

A novel rat model of vertebral inflammation-induced intervertebral disc degeneration mediated by activating cGAS/STING molecular pathway.

In this study, we describe a new rat model of vertebral inflammation-induced caudal intervertebral disc degeneration (VI-IVDD), in which IVD structure was not damaged and controllable segment and speed degeneration was achieved. VI-IVDD model was obtained by placing lipopolysaccharide (LPS) in the caudal vertebral bodies of rats. Rat experimental groups were set as follows: normal control group, group with a hole drilled in the middle of vertebral body and not filled with LPS (Blank group), group with a hole drilled in the middle of vertebral body and filled with LPS (Mid group), and group with hole drilled in the vertebral body in proximity of IVD and filled with LPS (NIVD group). Radiological results of VI-IVDD rats showed a significant reduction in the intervertebral space height and decrease in MRI T2 signal intensity. Histological stainings also revealed that the more the nucleus pulposus and endplate degenerated, the more the annulus fibrosus structure appeared disorganized. Immunohistochemistry analysis demonstrated that the expression of Aggrecan and collagen-II decreased, whereas that of MMP-3 increased in Mid and NIVD groups. Abundant local production of pro-inflammatory cytokines was detected together with increased infiltration of M1 macrophages in Mid and NIVD groups. Apoptosis ratio remarkably enhanced in Mid and NIVD groups. Interestingly, we found a strong activation of the cyclic GMP-AMP synthase /stimulator of interferon gene signalling pathway, which is strictly related to inflammatory and degenerative diseases. In this study, we generated a new, reliable and reproducible IVDD rat model, in which controllable segment and speed degeneration was achieved.

Multivariate analysis of the relationship between gluteal muscle contracture and coxa valga.

BACKGROUND: Gluteal muscle contracture (GMC) is a disease characterized by the limited function of the hip joint, knee pain, and abnormal gait. There is a lack of research on the effect of GMC on the hip joint structure to date. This study aims to analyze the association between GMC and the deformity of the hip and pelvis. METHODS: Standing anteroposterior pelvic radiographs of 214 patients (152 with gluteal muscle contracture and 62 without gluteal muscle contracture) were retrospectively collected. Neck-shaft angle, lateral center edge angle, Tönnis angle, femoral head coverage index, acetabular depth, Sacro-femoral-pubic angle, and obturator foramen ratio were respectively measured and included in the following statistical analysis. The collected data were analyzed using logistical regression and multiple linear regression to explore the factors influencing coxa valga and SFP angle. RESULTS: GMC was identified as a common factor significantly associated with coxa valga and increased SFP angle. There is a difference of risk factors in logistic regression for coxa valga between the left and right sides. CONCLUSION: GMC is a significant risk factor for coxa valga and increased SFP angle. Given that GMC can cause coxa valga and likely alter the pelvis's position, GMC should be paid attention to and treated early.

MicroRNA 148a-3p promotes Thrombospondin-4 expression and enhances angiogenesis during tendinopathy development by inhibiting Krüppel-like factor 6.

Tendinopathy is a common musculoskeletal disorder with characteristic hypervascularity. The mechanism of angiogenesis in tendinopathy remains unclear. The present study aimed to investigate the roles of miR-148a-3p in angiogenesis development of tendinopathy. In this study, we demonstrated that miR-148a-3p expression was increased in tendinopathy tissues and positively correlated with CD34 levels which is a specific marker for angiogenesis. We identified Krüppel-like factor 6 (KLF6) as a direct target gene of miR-148a-3p in tenocytes. Furthermore, reduced levels of KLF6 in tendinopathy tissues was showed using qRT-PCR and immunohistochemical analysis, compared with controls. A negative correlation between the levels of KLF6 mRNA and miR-148a-3p was observed. Then, we verified that miR-148a-3p could regulate Tsp-4 expression by targeting KLF6 in tenocyte and was positively correlated with Tsp-4 levels in tendinopathy tissues. In a coculture system of tenocytes with endothelial cells (ECs), we observed that transfection of Lv-miR-148a-3p markedly upregulated EC angiogenesis. In summary, our data establish a novel molecular mechanism by which miR-148a-3p upregulates Tsp-4 expression in tenocytes to promote EC angiogenesis by targeting KLF6, which could be helpful for the treatment of tendinopathy in the future.

Do Nonsteroidal Anti-Inflammatory Drugs Affect Tissue Healing After Arthroscopic Anterior Cruciate Ligament Reconstruction?

BACKGROUND Experimental studies have reported nonsteroidal anti-inflammatory drugs (NSAIDs) could impair tendon healing. The purpose of this study was to investigate whether NSAIDs could affect recovery of knee joint function in patients after anterior cruciate ligament (ACL) reconstruction. MATERIAL AND METHODS We enrolled 40 patients treated with celecoxib and 40 patients treated with tramadol, who underwent ACL reconstruction from January 2011 to December 2017. Visual analogue scale (VAS) and functional outcomes were collected and evaluated. The follow-up period was 12 months. RESULTS In both groups, all patients obtained pain release after surgery, compared with that before surgery. But no significant differences were observed between the 2 groups in VAS scores. We also did not find any differences between the 2 groups at 1 year of follow-up, in terms of anterior drawer test, Lachman test, side-to-side laxity assessed by KT-2000, IKDC score, Lysholm score, and Tegner scale. However, the celecoxib group showed a reduced incidence of nausea compared to the tramadol group (P=0.048). CONCLUSIONS The use of NSAIDs after ACL reconstruction is relatively safe and could decrease adverse side effects which were caused by opioid drugs.

Autophagy Prevents Oxidative Stress-Induced Loss of Self-Renewal Capacity and Stemness in Human Tendon Stem Cells by Reducing ROS Accumulation.

BACKGROUND/AIMS: Tendon stem cells (TSCs) exhibit a high self-renewal capacity, multi-differentiation potential, and low immunogenicity; thus, these cells might provide a new cell source for tendon repair and regeneration. TSCs are exposed to increased oxidative stress at tendon injury sites; however, how TSCs maintain their stemness under oxidative stress is not clear. METHODS AND RESULTS: In this study, we found that H2O2 treatment increased ROS accumulation in human TSCs (hTSCs) and resulted in loss of self-renewal capacity and stemness, as reflected in reduced colony formation and proliferation, decreased expression of the stemness markers Nanog, Oct-4, NS, and SSEA-4, and impaired differentiation capability. These H2O2-induced damages were prevented by pretreatment with starvation or rapamycin. Pretreatment with starvation or rapamycin prior to H2O2 exposure also led to decreased intracellular and mitochondrial ROS accumulation along with increased autophagic activity, as manifested in increased LC3 cleavage, Beclin-1 expression, and GFP-LC3-labeled autophagosome formation. Autophagy inhibition by 3-MA or CQ, or by shRNA silencing of Agt-7 or Beclin-1 reduced the protective effects of starvation and rapamycin on H2O2-treated hTSCs. CONCLUSION: Thus, the findings of this study suggest that autophagy prevents oxidative stress-induced loss of self-renewal capacity and stemness in hTSCs through suppression of ROS accumulation.

Microarray profiling analysis of long non-coding RNAs expression in tendinopathy: identification for potential biomarkers and mechanisms.

The role of lncRNAs in pathologies of tendinopathy has not been researched so far, this study aims to identify the role and potent mechanism of lncRNAs in tendinopathy with a bioinformatic analysis. The gene profile of GSE26051 based on the platform of Affymetrix Human Genome U133B Array condensed was downloaded from Gene Expression Omnibus. A total of 46 specimens (including 23 normal samples and 23 tendinopathy specimens) were available. Compared with the control samples, differentially expressed genes (DEGs) of tendinopathy was identified the by packages in R. The selected DEGs were further analysed using bioinformatics methods including co-expression and enrichment analysis to detect the potential role of lncRNAs. A total of 40 different expressed lncRNAs were identified. However, most of the identified lncRNAs have not been researched before. And this study only annotate one of the identified lncRNAs successfully, the LOC100507027 (myoregulin), with the potential role in regulating skeletal muscle tissue development and skeletal muscle organ development.

Tenotomy or tenodesis for long head biceps lesions in shoulders with reparable rotator cuff tears: a prospective randomised trial.

PURPOSE: Tenotomy and tenodesis are both effective for the treatment of long head biceps lesions. The aim of this study was to compare the clinical outcomes of the two procedures in patients older than 55 years of age affected by reparable rotator cuff tears with concomitant long head biceps pathologies. METHODS: Patients older than 55 years of age with long head biceps lesions and reparable rotator cuff tears were selected for this study. A total of 151 patients were randomly assigned to the tenotomy group (77 patients) or the tenodesis group (74 patients). Arthroscopic rotator cuff repair was performed in all the patients. Before surgery, physical and radiological examinations were performed; the constant score was measured as well. After the operation, the surgical time, cost, pain (VAS scores), Popeye sign, cramping pain, constant scores, satisfaction level and the elbow flexion and forearm supination strength indices were recorded. RESULTS: Patients were followed for an average of 24 months. No significant differences in the clinical results for the constant scores, the forearm supination and elbow flexion strength indices, Popeye sign, cramping pain and satisfaction level were found between the groups. However, tenotomy required a shorter surgical time (40.4 ± 4.0 vs. 50.4 ± 5.9 min, P < 0.001) and resulted in faster pain relief (3.1 ± 1.8 vs. 4.8 ± 1.9, P < 0.001). CONCLUSION: Both tenotomy and tenodesis are effective and equal for the treatment of long head biceps lesions. However, because tenotomy requires a shorter surgical time and results in faster pain relief, tenotomy may be more suitable for the treatment of long head biceps lesions in patients older than 55 years of age with reparable rotator cuff tears. LEVEL OF EVIDENCE: Therapeutic studies, Level I.

Efficacy Analysis of Arthroscopic Surgery Combined with Intra-articular Chitosan Injection for Stage II-III Knee Osteoarthritis in Patients with Abnormal Body Weight.

OBJECTIVE: Weight is an influential factor in knee osteoarthritis (KOA). However, the effect of abnormal body weight on chitosan's efficacy in treating KOA is unclear. This study aimed to explore the differences in the effectiveness of arthroscopic surgery combined with intra-articular chitosan injection for KOA in patients with abnormal body weight. METHODS: Patients with stage II-III KOA (Kellgren-Lawrence rating, K-L) undergoing arthroscopic surgery were recruited for this clinical study from January 2020 to September 2021. Based on body mass index (BMI) and intra-articular chitosan injection, patients with KOA undergoing arthroscopic surgery (138 patients) were divided into four groups: low-weight-non-injection (Lw-N, BMI <18.5); low-weight-chitosan injection (Lw-CS, BMI <18.5); overweight-non-injection (Ow-N, BMI ≥25); overweight-chitosan injection (Ow-CS, BMI ≥25). A 2-year follow-up was conducted to evaluate various indicators, including the visual analogue scale (VAS) and the Western Ontario and McMaster Universities osteoarthritis index score (WOMAC). Statistical analyses were performed using relevant parametric or non-parametric tests. RESULTS: In total, 138 patients with KOA were included in this study. There were no significant differences in gender, age, and incidence of chronic residual pain after arthroscopy among the four groups (p > 0.05). The proportion of patients undergoing subsequent knee arthroplasty during the 2-year follow-up period was significantly higher in the Ow-CS group (20/35) than in the Lw-CS group (12/39) (p < 0.05). The K-L rating showed an overall increasing trend over time, with the K-L rating in the Ow-N and Ow-CS groups significantly higher than that in the Lw-CS group at the final follow-up (p < 0.05). VAS and WOMAC scores significantly decreased at 1 and 3 months post-arthroscopy and then increased. One month after arthroscopy, VAS was significantly lower (p < 0.05) in the intra-articular chitosan injection groups (Lw-CS and Ow-CS) compared with the non-injection groups (Lw-N and Ow-N). VAS was lower in the Ow-CS group than in the Lw-CS group (p < 0.05). There was no significant difference in WOMAC between the intra-articular chitosan injection and non-injection groups at each time point (Lw-N vs. Lw-CS, Ow-N vs. Ow-CS, p > 0.05). CONCLUSION: Arthroscopic surgery combined with intra-articular chitosan injection shows short-term positive effects in treating KOA. Intra-articular chitosan injection appears to have a greater short-term pain relief effect in obese patients.

Course-based intra-articular injection of medical chitosan mitigates excessive deposition of triacylglycerides in the synovial tissue of the knee osteoarthritis.

BACKGROUND: This study aimed to investigate the clinical efficacy of intra-articular injections of medical chitosan for treating knee osteoarthritis (KOA) and measure the lipid metabolism profiles of the synovial tissue. METHODS: 60 patients with KOA undergoing conservative treatment were recruited and randomized into two groups: one without pharmacological intervention (OA group) and the other receiving course-based intra-articular medical chitosan injections (CSI group). Quantitative lipidomic profile of synovial tissue was analyzed. Functional scores, including Kellgren-Lawrence rating (K-L), VAS, WOMAC scoring, and AKS scoring were conducted. RESULTS: Survival from the initial conservative treatment to final knee arthroplasty was significantly longer in the CSI group compared to the OA group. Except for the pre-surgery VAS score, no statistically significant differences were observed in the other scores, including K-L, initial VAS, WOMAC, and AKS. However, the CSI group experienced a slightly more pronounced decline in AKS-Knee subscores compared to the OA group. Compared to the CSI group, the OA group exhibited a significant upregulation in most differential lipids, particularly triacylglycerides (TAGs, 77%). The OA group had notably higher levels of long-chain unsaturated fatty acids. CONCLUSION: Intra-articular injection of medical chitosan significantly prolongs the survival period before knee arthroplasty and reduces the deposition of TAGs metabolites.

Effective regeneration of rat sciatic nerve using nanofibrous scaffolds containing rat ADSCs with controlled release of rhNGF and melatonin molecules for the treatment of peripheral injury model.

Different therapeutic strategies have been designed and developed for the repair and regeneration of peripheral nerve injury (PNI) tissue as a result of advancements in tissue engineering and regenerative medicine. Due to its versatility, controlled delivery and administration of multifunctional therapeutic agents can be regarded of as an effective strategy in treating nerve injury. In this study, melatonin (Mel) molecules and recombinant human nerve growth factor (rhNGF) were loaded on the surface and in the core of polycaprolactone/chitosan (PCL/CS) blended nanofibrous scaffold. To simulate the in vivo microenvironment, a dual-delivery three-dimensional (3-D) nanofibrous matrix was developed and the in vitro neural development of stem cell differentiation process was systematically examined. The microscopic technique with acridine orange and ethidium bromide (AO/EB) fluorescence staining method was used to establish the adipose-derived stem cells (ADSCs) differentiation and cell-cell communications, which demonstrated that the effective differentiation of the ADSCs with nanofibrous matrix. As investigated observations, ADSCs differentiation was further evident through cell migration assay and gene expression analysis. According to the biocompatibility analysis, the nanofibrous matrix did not trigger any adverse immunological reactions. Based on these characteristics, a 5-week in vivo investigation examined the potential of the developed nanofibrous matrix in the regeneration of sciatic nerve of rats. Additionally, compared to the negative control group, the electrophysiological and walking track analyses demonstrated improved sciatic nerve regeneration. This study demonstrates the nanofibrous matrix's ability to regenerate peripheral nerves.

Multivariate Analysis of Associations between Patellofemoral Instability and Gluteal Muscle Contracture: A Radiological Analysis.

The purpose of this study was to investigate the associations between gluteal muscle contracture (GMC) severity and patellofemoral instability and evaluate the reliability of novel indicators by multivariate analysis. Clinical and imaging data from 115 patients with GMC were collected for retrospective analysis. Two novel indicators were used to evaluate GMC severity (knee flexion angle and hip flexion angle, feet distance), and two additional novel parameters were used to reflect patellofemoral instability [patellar displacement vector (L, α), patella-femoral trochlear (P-FT) area, and femoral-trochlear-patella (FT-P) area]. In this study, patients with moderate contracture were dominant, and 35.65% also experienced anterior knee pain after physical activity. Ordered logistic regression analysis indicated that a more serious GMC represented a higher risk of lateral tilt and lateral displacement of the patella. Multivariate analysis showed that feet distance was a reliable indicator for evaluating the severity of GMC. The results showed that the more serious the GMC, the more significant the difference between the P-FT area and the FT-P area of the patellofemoral joint space. L, patellar tilt angle, patellar congruency angle, and lateral patellofemoral angle were independent risk factors for this difference. A more serious GMC represents a higher risk of patellar subluxation.

The duration of postoperative analgesic use after total knee arthroplasty and nomogram for predicting prolonged analgesic use.

Background: Total knee arthroplasty is currently a reliable treatment for end-stage knee osteoarthritis. However, chronic postsurgical pain (CPSP) is substantially thought to reduce patient satisfaction. NSAID-based oral analgesics were used to manage CPSP, but research on the duration of postoperative analgesic use (DAU) and prolonged analgesic use (PAU) are presently scarce. Methods: Preoperative, perioperative, and one-year or above postoperative follow-up data were collected from 162 patients who underwent total knee arthroplasty between 1 June 2018 and 1 March 2019, and the DAU and the discontinuation time of each patient after discharge were recorded. Observational statistical analysis, diagnostic test, and predictive nomogram construction were performed on the collected data. Results: The 3-month DAU has good diagnostic utility for poor outcome of postoperative months twelve (POM12). The constructed nomogram shows that gender, preoperative Numeric Rating Scale (NRS) movement pain scores, duration of surgery, postoperative days three (POD3) moderate to severe movement pain, and POD3 pain rescue medication were significant prognostic predictors of PAU after discharge. The area under the curve (AUC) of the 3-month, 6-month, and 12-month nomogram receiver operating characteristic (ROC) curves were calculated to be 0.741, 0.736, and 0.781. Conclusion: PAU was defined as more than three months of NSAID-based oral analgesic use after TKA. Prognostic predictors of PAU after TKA were identified, and visualized nomogram was plotted and evaluated. The evaluation indicated that the prediction model had the good predictive ability and was a valuable tool for predicting PAU after discharge.

Rapid and Severe Idiopathic Aseptic Necrosis of the Contralateral Femoral Head after Unilateral Total Hip Arthroplasty.

BACKGROUND: Osteonecrosis of the femoral head (ONFH) is a multifactorial disease, and agnogenic ONFH, otherwise known as idiopathic ONFH, is rare in clinic. Idiopathic ONFH that exhibits severe necrosis and progresses extremely rapidly is called rapidly destructive hip disease (RDHD). RDHD greatly affects patients but is rarely reported in clinical practice and literature. CASE PRESENTATION: In this study, a 64-year-old male patient with complete collapse and necrosis of the right femoral head complicated with severe bone destruction at 10 months after left total hip arthroplasty (THA) was reported. The period from the intact structure of the right femoral head to the first discovery of its complete collapse, according to imaging results, was 7 months. The duration from the occurrence of symptoms in the right hip joint to the first discovery of complete collapse and necrosis of the femoral head was only 5 months. At present, the cause has not been determined based on medical history, symptoms, signs, imaging evaluation results, laboratory examination results, and pathological examination results, though it has been identified as severe idiopathic aseptic necrosis of the femoral head with rapid progression, or RDHD. Finally, right THA was performed, and a good outcome was observed in the patient at present. CONCLUSIONS: As a rare hip joint disease, RDHD greatly influences the normal life of patients. RDHD of the contralateral side after unilateral THA is even scarcer. Left THA may be one of the important factors accelerating the necrosis of the right femoral head. Hopefully, with this case report, more attention will be paid to the contralateral hip joint in patients undergoing unilateral THA by clinicians and rehabilitation physicians, and a clinical reference will be provided for the research on RDHD.

Association and histological characteristics of endplate injury and intervertebral disc degeneration in a rat model.

INTRODUCTION: The purpose of this study was to construct a rat caudal vertebral body fracture model and to analyze the association and histological characteristics of vertebral body fracture with endplate injury and adjacent intervertebral disc degeneration. MATERIALS AND METHODS: This study included 144 clean-grade male Sprague-Dawley rats, which were randomly divided into a control, middle vertebral body injury (MI), and endplate injury (EI) groups. A vertebral body fracture with or without endplate injury was developed by either drilling a hole in the middle of a rat caudal vertebral body to create a fracture with an intact endplate or drilling a hole in the vertebral body near the intervertebral disc to create a vertebral body fracture with endplate injury. The histological differences in the adjacent intervertebral discs of vertebral body fractures with or without endplate injury were detected using imaging, non-specific histological staining, immunohistochemistry and TUNEL assay. RESULTS: Imaging results revealed that the EI group showed a significant decrease in intervertebral space height and intervertebral disc T2 signal over time. Non-specific histological staining revealed that in the EI group, the intervertebral disc was degenerative. Immunohistochemistry indicated that Aggrecan and Collagen-II were decreased and inflammatory factors were increased in the EI group. The TUNEL detection found that apoptosis was significantly increased in the EI group as compared with the MI and control groups. CONCLUSION: In rat caudal vertebral body fractures, a fracture with endplate injury is more likely to induce or accelerate degeneration of adjacent intervertebral discs.

Role of the Alarmin S100A9 protein in inducing Achilles tendinopathy in rats.

BACKGROUND: This study aimed to investigate the correlation between the Alarmin S100A9 protein and Achilles tendinopathy (AT), and to reveal the role of this protein in inducing AT. METHODS: In this study, 40 male Sprague-Dawley rats were randomly divided into four groups: Control group (received no treatment), Injury group (Achilles tendon tissues were cut intraoperatively), S100A9 group (received a subcutaneous injection of rhS100A9 solution), and S100A9 + Paquinimod group [received a subcutaneous injection of rhS100A9 and Paquinimod (1:1 ratio) into the Achilles tendon]. At 1 week postoperatively, the four groups of rats were euthanized, and the Achilles tendon tissues were isolated for histological staining, immunohistochemistry (IHC), immunofluorescence, Sirius Red (SR) staining, and terminal deoxynucleotidyl transferase-mediated dUTP-biotin nick end labeling assay. RESULTS: Compared with both the Control and S100A9 + Paquinimod groups, the Injury and S100A9 groups exhibited higher expression levels of S100A9 protein, matrix metalloproteinase-3 (MMP-3), and inflammatory factors. Regarding histomorphology [hematoxylin-eosin (HE) staining and Safranin O/fast green (SOFG; fast green and Safranin) training], the Achilles tendon tissues in the Injury and S100A9 groups showed AT-like changes, and the fibers were extremely disorderly, non-bundled, and ruptured, and some nuclei were spindles. As for collagen (Col) remodeling, a large number of fresh collagen fibers had formed, the amounts of Col-I and Col-II were lower, and a large quantity of Col-III was present. Additionally, a large number of tendon cells had died in both the Injury and S100A9 groups. CONCLUSIONS: This study showed that Alarmin S100A9 can induce AT-like morphological changes and local inflammatory reactions, trigger collagen fiber remodeling and tendon cell apoptosis, and ultimately induce AT.

FGF6 enhances muscle regeneration after nerve injury by relying on ERK1/2 mechanism.

BACKGROUND: Severe peripheral nerve injury leads to skeletal muscle atrophy and impaired limb function that is not sufficiently improved by existing treatments. Fibroblast growth factor 6 (FGF6) is involved in tissue regeneration and is dysregulated in denervated rat muscles. However, the way that FGF6 affects skeletal muscle repair after peripheral nerve injury has not been fully elucidated. METHODS: In this study, we investigated the role of FGF6 in the regeneration of denervated muscles using myoblast cells and an in vivo model of peripheral nerve injury. RESULTS: FGF6 promoted the viability and migration of C2C12 and primary myoblasts in a dose-dependent manner through FGFR1-mediated upregulation of cyclin D1. Low concentrations of FGF6 promoted myoblast differentiation through FGFR4-mediated activation of ERK1/2, which upregulated expression of MyHC, MyoD, and myogenin. FGFR-1, FGFR4, MyoD, and myogenin were not upregulated when FGF6 expression was inhibited in myoblasts by shRNA-mediated knockdown. Injection of FGF6 into denervated rat muscles enhanced the MyHC-IIb muscle fiber phenotype and prevented muscular atrophy. CONCLUSION: These findings indicate that FGF6 reduces skeletal muscle atrophy by relying on the ERK1/2 mechanism and enhances the conversion of slow muscle to fast muscle fibers, thereby promoting functional recovery of regenerated skeletal muscle after innervation.