Exercise promotes osteogenic differentiation by activating the long non-coding RNA H19/microRNA-149 axis

BACKGROUND

Regular physical activity during childhood and adolescence is beneficial to bone development, as evidenced by the ability to increase bone density and peak bone mass by promoting bone formation.

AIM

To investigate the effects of exercise on bone formation in growing mice and to investigate the underlying mechanisms.

METHODS

20 growing mice were randomly divided into two groups: Con group (control group, n = 10) and Ex group (treadmill exercise group, n = 10). Hematoxylin-eosin staining, immunohistochemistry, and micro-CT scanning were used to assess the bone formation-related indexes of the mouse femur. Bioinformatics analysis was used to find potential miRNAs targets of long non-coding RNA H19 (lncRNA H19). RT-qPCR and Western Blot were used to confirm potential miRNA target genes of lncRNA H19 and the role of lncRNA H19 in promoting osteogenic differentiation.

RESULTS

Compared with the Con group, the expression of bone morphogenetic protein 2 was also significantly increased. The micro-CT results showed that 8 wk moderate-intensity treadmill exercise significantly increased bone mineral density, bone volume fraction, and the number of trabeculae, and decreased trabecular segregation in the femur of mice. Inhibition of lncRNA H19 significantly upregulated the expression of miR-149 and suppressed the expression of markers of osteogenic differentiation. In addition, knockdown of lncRNA H19 significantly downregulated the expression of autophagy markers, which is consistent with the results of autophagy-related protein changes detected in mouse femurs by immunofluorescence.

CONCLUSION

Appropriate treadmill exercise can effectively stimulate bone formation and promote the increase of bone density and bone volume in growing mice, thus enhancing the peak bone mass of mice. The lncRNA H19/miR-149 axis plays an important regulatory role in osteogenic differentiation.

O-linked β-N-acetylglucosaminylation may be a key regulatory factor in promoting osteogenic differentiation of bone marrow mesenchymal stromal cells

Cumulative evidence suggests that O-linked β-N-acetylglucosaminylation (O-GlcNAcylation) plays an important regulatory role in pathophysiological processes. Although the regulatory mechanisms of O-GlcNAcylation in tumors have been gradually elucidated, the potential mechanisms of O-GlcNAcylation in bone metabolism, particularly, in the osteogenic differentiation of bone marrow mesenchymal stromal cells (BMSCs) remains unexplored. In this study, the literature related to O-GlcNAcylation and BMSC osteogenic differentiation was reviewed, assuming that it could trigger more scholars to focus on research related to O-GlcNAcylation and bone metabolism and provide insights into the development of novel therapeutic targets for bone metabolism disorders such as osteoporosis.

Nuclear magnetic resonance-based metabolomic study of rat serum after anterior cruciate ligament injury

Anterior cruciate ligament (ACL) injury, a common sports injury, is associated with a high risk of subsequent osteoarthritis (OA), which can cause serious pain and disability. Understanding the detailed mechanism underlying the predisposition of knee with ACL injury to secondary OA at an early stage is key to preventing future degradation and progression to a clinically significant disease. A total of 56 male Sprague Dawley rats (age, 8 weeks; weight, 180-220 g) were randomly divided into three experimental groups: control, ACL transection (ACLT; where surgical procedure was performed with ACLT), and sham (where surgical procedure was performed without ACLT). The ACLT and sham groups were further divided into three subgroups based on when the rats were sacrificed: 4, 8, and 12 weeks after the surgical procedure. The control group and the aforementioned subgroups contained 8 rats each. We used nuclear magnetic resonance (NMR)-based metabolomic analysis to analyze rat serum samples for the metabolic characteristics and the underlying mechanisms. In total, 28 metabolites were identified in the NMR spectra of the rat sera. At 4 and 8 weeks postoperatively, the sham group demonstrated metabolic profiles different from those of the ACLT group. However, this difference was not observed 12 weeks postoperatively. In total, five metabolites (acetate, succinate, sn-glycero-3-phosphocholine, glucose, and phenylalanine) and five metabolic pathways (phenylalanine, tyrosine, and tryptophan biosynthesis; phenylalanine metabolism; pyruvate metabolism; starch and sucrose metabolism; and histidine metabolism) demonstrated significant differences between the ACLT and sham groups. ACL injury was noted to considerably affect biochemical homeostasis and metabolism; however, these metabolic changes persisted briefly. Moreover, glucose was a characteristic metabolite, and several energy-related metabolic pathways were significantly disturbed. Therefore, an ACL injury may lead to considerable impairments in energy metabolism. Abnormal glucose levels facilitate chondrocyte function impairment and thereby lead to OA progression. Furthermore, lactate may aid in identifying metabolic changes specific to knee trauma not related to an ACL injury. Overall, the metabolic changes in rat serum after an ACL injury were closely related to disturbances in energy metabolism and amino acid metabolism. The current results may aid in understanding the pathogenesis of posttraumatic osteoarthritis.

Short-term efficacy of repetitive transcranial magnetic stimulation in SCA3: A prospective, randomized, double-blind, sham-controlled study

OBJECTIVE

Spinocerebellar ataxia type 3 (SCA3) is the most common autosomal dominant ataxia globally. No effective treatment is currently available for SCA3. Repetitive Transcranial Magnetic Stimulation (rTMS) is a non-invasive form of brain stimulation, demonstrated to improve symptoms in patients with neurodegenerative cerebellar ataxias. The present study investigated whether treatment with rTMS over the cerebellum for 15 consecutive days improved measures of ataxia in SCA3 patients.

METHODS

A double-blind, prospective, randomized, sham-controlled trial was carried out on 44 SCA3 patients. Participants were randomly assigned to two groups: real or sham stimulation. Each participant underwent 30 minutes of 1Hz rTMS stimulation (a total of 900 pulses) for 15 consecutive days. The primary outcome measure was the score on the International Cooperative Ataxia Rating Scale (ICARS), and secondary outcomes were from the Scale for the Assessment and Rating of Ataxia (SARA) and the Berg Balance Scale (BBS).

RESULTS

Nausea was the only adverse effect reported by 2 participants from the sham and real group. After 15 days of treatment, there was a significant improvement in all performance scores in both real and sham stimulation groups. However, compared to the sham group, the improvements were significantly larger in the real group for the ICARS (P = 0.002), SARA (P = 0.001), and BBS (P = 0.001).

INTERPRETATION

A 15 days treatment with rTMS over the cerebellum improves the symptoms of ataxia in SCA3 patients. Our results suggest that rTMS is a promising tool for future rehabilitative approaches in SCA3.

Advances in Stem Cell Therapies for Rotator Cuff Injuries

Rotator cuff injury is a common upper extremity musculoskeletal disease that may lead to persistent pain and functional impairment. Despite the clinical outcomes of the surgical procedures being satisfactory, the repair of the rotator cuff remains problematic, such as through failure of healing, adhesion formation, and fatty infiltration. Stem cells have high proliferation, strong paracrine action, and multiple differentiation potential, which promote tendon remodeling and fibrocartilage formation and increase biomechanical strength. Additionally, stem cell-derived extracellular vesicles (EVs) can increase collagen synthesis and inhibit inflammation and adhesion formation by carrying regulatory proteins and microRNAs. Therefore, stem cell-based therapy is a promising therapeutic strategy that has great potential for rotator cuff healing. In this review, we summarize the advances of stem cells and stem cell-derived EVs in rotator cuff repair and highlight the underlying mechanism of stem cells and stem cell-derived EVs and biomaterial delivery systems. Future studies need to explore stem cell therapy in combination with cellular factors, gene therapy, and novel biomaterial delivery systems.

Effect of Exercise on the Cognitive Function of Older Patients With Type 2 Diabetes Mellitus: A Systematic Review and Meta-Analysis

Background

Aging and type 2 diabetes mellitus (T2DM) are important risk factors for the development of cognitive deterioration and dementia. The objective of this research was to investigate the effects of an exercise intervention on cognitive function in older T2DM patients.

Methods

Eight literature databases (PubMed, EBSCO, Scopus, Embase, The Cochrane Library, Web of Science, Ovid, and ProQuest) were searched from inception to 20 January 2022. The researchers examined randomized controlled trials (RCTs) that evaluated the impact of exercise on the cognitive performance of older T2DM patients. The Cochrane risk-of-bias tool (ROB 2) for RCTs was used to assess each study. The quality of evidence was assessed using the GRADE (grading of recommendations, assessment, development, and evaluations) approach. The mini-mental state examination (MMSE), Modified MMSE (3MSE), and Montreal cognitive assessment (MoCA) were used to evaluate the cognitive outcomes. We performed a subgroup analysis with stratification according to exercise intervention modality, duration, and cognitive impairment.

Results

Five trials were eligible, with a total of 738 T2DM patients. The combined findings revealed that exercise improved global cognitive function significantly (standardized mean difference: 1.34, 95% confidence interval: 0.23–2.44, p < 0.01). The effect of exercise on global cognitive performance was not significantly influenced by intervention modality, intervention duration, or cognitive impairment in the sub-group analysis (p > 0.05). In the studies that were included, no relevant adverse events were reported.

Conclusion

Exercise is beneficial in improving global cognitive function in older adults with T2DM. Studies with bigger sample sizes and higher quality are additionally expected to draw more definite conclusions.

Systematic Review Registration

[https://www.crd.york.ac.uk/PROSPERO/#recordDetails], identifier [CRD42022296049].

Effect of low-load resistance training with different degrees of blood flow restriction in patients with knee osteoarthritis: study protocol for a randomized trial

BACKGROUND

Knee osteoarthritis (KOA) is a common degenerative disease that causes pain, functional impairment, and reduced quality of life. Resistance training is considered as an effective approach to reduce the risk of muscle weakness in patients with KOA. Blood flow restriction (BFR) with low-load resistance training has better clinical outcomes than low-load resistance training alone. However, the degree of BFR which works more effectively with low-load resistance training has not been determined. The purpose of this study is to evaluate the effectiveness of different degrees of BFR with low-load resistance training in patients with KOA on pain, self-reported function, physical function performance, muscle strength, muscle thickness, and quality of life.

METHODS

This is a study protocol for a randomized, controlled trial with blinded participants. One hundred individuals will be indiscriminately assigned into the following groups: two training groups with a BFR at 40% and 80% limb occlusion pressure (LOP), a training group without BFR, and a health education group. The three intervention groups will perform strength training for the quadriceps muscles twice a week for 12 weeks, while the health education group will attend sessions once a week for 12 weeks. The primary outcome is pain. The secondary outcomes include self-reported function, physical function performance, muscle strength of the knee extensors, muscle mass of the quadriceps, quality of life, and adverse events. Intention-to-treat analysis will be conducted for individuals who withdraw during the trial.

DISCUSSION

Previous studies have shown that BFR with low-load resistance training is more effective than low-load resistance training alone; however, a high degree of BFR may cause discomfort during training. If a 40% LOP for BFR could produce similar clinical outcomes as an 80% LOP for BFR, resistance training with a low degree of BFR can be chosen for patients with KOA who are unbearable for a high degree of BFR.

TRIAL REGISTRATION

Chinese Clinical Trial Registry ChiCTR2000037859 ( http://www.chictr.org.cn/edit.aspx?pid=59956&htm=4 ). Registered on 2 September 2020.

Efficacy and Safety of Blood Flow Restriction Training in Patients With Knee Osteoarthritis: A Systematic Review and Meta-Analysis

OBJECTIVE

To evaluate the efficacy and safety of blood flow restriction training (BFRT) in the treatment of patients with knee osteoarthritis (OA).

METHOD

Seven electronic databases were searched to identify trials comparing BFRT and conventional resistance training in a population with knee OA. Studies were selected according to the inclusion and exclusion criteria. Standardized mean differences (SMDs) or risk ratios (RRs) with 95% confidence intervals (95% CIs) were calculated to compare outcome measures of the groups. The methodologic quality of selected studies and the quality of evidence were evaluated for included studies.

RESULTS

A total of 5 studies were included in this meta-analysis, with very low to moderate risk of bias. The pooled results showed no significant difference between BFRT and conventional resistance training for knee OA, including pain (SMD -0.04 [95% CI -0.31, 0.24], P = 0.79), physical function performance (SMD 0.12 [95% CI -0.55, 0.78], P = 0.73), self-reported function (SMD 0.14 [95% CI -0.24, 0.52], P = 0.48), and adverse events (RR 0.45 [95% CI 0.20, 1.01], P = 0.05). In subgroup analysis, BFRT had a lower incidence of adverse events when compared with high-load resistance training (HLRT).

CONCLUSION

Data from pooled studies showed that BFRT may not have greater efficacy for treating patients with knee OA, and it is less likely to have a higher risk of adverse events. However, limited evidence supports the idea that BFRT is likely safer than HLRT. More evidence with high quality is needed in further research on efficacy and safety.

Depression in Osteoarthritis: Current Understanding

Depression, one of the most common comorbidities with osteoarthritis (OA), affects patient prognosis and quality of life. It also increases the overall burden of disease. This subgroup of patients has not been effectively managed in clinical settings. The study aimed to direct physicians' attention to the co-occurrence of depression and OA. Therefore, this review summarizes the relevant literature published over the past 10 years. The focus is on the prevalence of and risk factors for depression in OA, the effects of depression on OA development and treatment response, comorbidity mechanisms, screening, and non-pharmacological treatment. The research on the etiology of depression has been driven largely by epidemiological studies. Recent studies have shown that high levels of pain, poor levels of function, high numbers of OA sites, and slow gait might be associated with depression. However, the pathophysiology of OA and depression comorbidities remains unclear. In addition to immune inflammation and structural changes in the brain, which have been documented in brain imaging studies, psychosocial factors may also play a role. The evidence indicates that depression can be treated with early intervention; however, adjustments may need to be made for individuals with comorbid depression in OA. It is recommended that health care providers pay more attention to depressive symptoms in patients with OA. Clinicians should develop and implement an individualized and comprehensive treatment plan for patients based on a mental health assessment and in teams with other professionals to optimize treatment outcomes.

Excessive mechanical stretch‑mediated osteoblasts promote the catabolism and apoptosis of chondrocytes via the Wnt/β‑catenin signaling pathway

Excessive biomechanical loading is considered an important cause of osteoarthritis. Although the mechanical responses of chondrocytes and osteoblasts have been investigated, their communication during mechanical loading and the underlying molecular mechanisms are not yet fully known. The present study investigated the effects of excessive mechanically stretched osteoblasts on the metabolism and apoptosis of chondrocytes, and also assessed the involvement of the Wnt/β‑catenin signaling pathway. In the present study, rat chondrocytes and osteoblasts were subjected to mechanical tensile strain, and an indirect chondrocyte‑osteoblast co‑culture model was established. Reverse transcription‑quantitative PCR and western blotting were performed to determine the expression levels of genes and proteins of interest. An ELISA was performed to investigate the levels of cytokines, including matrix metalloproteinase (MMP) 13, MMP 3, interleukin‑6 (IL‑6) and prostaglandin E2 (PG E2), released from osteoblasts. Flow cytometry was performed to detect the apoptosis of chondrocytes exposed to stretched osteoblast conditioned culture medium. The levels of MMP 13, IL‑6 and PG E2 increased significantly in the supernatants of stretched osteoblasts compared with the un‑stretched group. By contrast, the mRNA expression levels of Collagen 1a and alkaline phosphatase were significantly decreased in osteoblasts subjected to mechanical stretch compared with the un‑stretched group. The mRNA expression level of Collagen 2a was significantly decreased, whereas the expression levels of MMP 13 and a disintegrin and metalloproteinase with thrombospondin‑like motifs 5 were significantly increased in chondrocytes subjected to mechanical stretch compared with the un‑stretched group. In the co‑culture model, the results indicated that excessive mechanically stretched osteoblasts induced the catabolism and apoptosis of chondrocytes, which was partly inhibited by Wnt inhibitor XAV‑939. The results of the present study demonstrated that excessive mechanical stretch led to chondrocyte degradation and inhibited osteoblast osteogenic differentiation; furthermore, excessive mechanically stretched osteoblasts induced the catabolism and apoptosis of chondrocytes via the Wnt/β‑catenin signaling pathway.

Stem cell therapies in tendon-bone healing

Tendon-bone insertion injuries such as rotator cuff and anterior cruciate ligament injuries are currently highly common and severe. The key method of treating this kind of injury is the reconstruction operation. The success of this reconstructive process depends on the ability of the graft to incorporate into the bone. Recently, there has been substantial discussion about how to enhance the integration of tendon and bone through biological methods. Stem cells like bone marrow mesenchymal stem cells (MSCs), tendon stem/progenitor cells, synovium-derived MSCs, adipose-derived stem cells, or periosteum-derived periosteal stem cells can self-regenerate and potentially differentiate into different cell types, which have been widely used in tissue repair and regeneration. Thus, we concentrate in this review on the current circumstances of tendon-bone healing using stem cell therapy.

A review of applications of metabolomics in osteoarthritis

Osteoarthritis (OA) represents the most prevalent and disabling arthritis worldwide due to its heterogeneous and progressive articular degradation. However, effective and timely diagnosis and fundamental treatment for this disorder are lacking. Metabolomics, a growing field in life science research in recent years, has the potential to detect many metabolites and thus explains the underlying pathophysiological processes. Hence, new specific metabolic markers and related metabolic pathways can be identified for OA. In this review, we aimed to provide an overview of studies related to the metabolomics of OA in animal models and humans to describe the metabolic changes and related pathways for OA. The present metabolomics studies reveal that the pathogenesis of OA may be significantly related to perturbations of amino acid metabolism. These altered amino acids (e.g., branched-chain amino acids, arginine, and alanine), as well as phospholipids, were identified as potential biomarkers to distinguish patients with OA from healthy individuals.

Is it time to put traditional cold therapy in rehabilitation of soft-tissue injuries out to pasture?

Cold therapy has been used regularly as an immediate treatment to induce analgesia following acute soft-tissue injuries, however, a prolonged ice application has proved to delay the start of the healing and lengthen the recovery process. Hyperbaric gaseous cryotherapy, also known as neurocryostimulation, has shown the ability to overcome most of the limitations of traditional cold therapy, and meanwhile promotes the analgesic and anti-inflammatory effects well, but the current existing studies have shown conflicting results on its effects. Traditional cold therapy still has beneficial effect especially when injuries are severe and swelling is the limiting factor for recovery after soft-tissue injuries, and therefore no need to be entirely put out to pasture in the rehabilitation practice. Strong randomized controlled trials with good methodological quality are still needed in the future to evaluate the effects of different cryotherapy modalities.

Factors associated with public attitudes towards persons with disabilities: a systematic review

OBJECTIVE

The aim of this review is to identify and summarize factors that are associated with public attitudes towards people with various disabilities systematically.

METHODS

An electronic search of three databases was performed (Medline, EMBASE and Cochrane) covering the period from 1950 to present. A comprehensive search strategy was developed and the lists of citations were screened for potential eligible studies. Only quantitative studies using valid measurements were included, and the methodological quality of included studies was appraised based on three criteria (sample, measurement, analysis) by two independent reviewers.

RESULTS

The initial electronic search yielded 995 articles after duplicates removed, and 27 studies met the eligibility criteria were included in the study. Three categories of the factors were found to be associated with the public attitudes, which are related to the attitude provider, disabled people, and society respectively. Specifically, the more people know about disabilities, the more likely they were to have positive attitude; and the frequency and quality of the contact with the disabled are also proved to be influential to the attitudes. Meanwhile, the type of disability is also closely correlated to the public's attitude towards the disabilities.

CONCLUSION

People's knowledge of the disability and their contact with individuals with disabilities are the main influential factors in public attitudes towards persons with disabilities.

Treadmill running induces remodeling of the infrapatellar fat pad in an intensity-dependent manner

OBJECTIVE

To investigate the response of the infrapatellar fat pad (IFP) to running at different intensities and further explore the underlying mechanisms of these responses under different running-induced loadings.

METHODS

Animals were randomly assigned into the sedentary (SED), low-intensity running (LIR), medium-intensity running (MIR), and high-intensity running (HIR) groups. The rats in the LIR, MIR, and HIR groups were subjected to an 8-week treadmill running protocol. In each group, the IFP was examined at the baseline and at the 8th week to perform histomorphology, immunohistochemistry, and mRNA expression analyses.

RESULTS

Compared with LIR and MIR, HIR for 8 weeks led to a substantial increase in the surface cellularity (1.67 ± 1.15), fibrosis (1.29 ± 0.36), and vascularity (33.31 ± 8.43) of the IFP but did not increase IFP inflammation or M1 macrophage polarization. Low-to-medium-intensity running resulted in unchanged or decreased fibrosis, vascularity, and surface cellularity in the IFP compared to those of the SED group. Furthermore, serum leptin and visfatin levels were significantly lower in the LIR and MIR groups than in the SED group or the HIR group (P < 0.05).

CONCLUSION

The effect of running on IFP remodeling was intensity dependent. In contrast to LIR and MIR, HIR increased the fibrosis and vascularity of the IFP. HIR-induced IFP fibrosis was probably due to mechanical stress, rather than pathological proinflammatory M1/M2 polarization.

Efficacy and safety of sprifermin injection for knee osteoarthritis treatment: a meta-analysis

OBJECTIVE

To perform a meta-analysis comparing the structural progression and clinical symptom outcomes as well as adverse events experienced from intra-articular injections of sprifermin compared to a placebo treatment for patients with knee osteoarthritis (KOA).

METHOD

We systematically searched the literature for studies that compared long-term outcomes between sprifermin and placebo injections for KOA treatment. Meta-analysis was performed with RevMan5.3 using an inverse variance approach with fixed or random effects models. Odds ratios (ORs) and 95% confidence intervals (CIs) were estimated.

RESULTS

Eight studies were included. Overall, there was significantly less improvement of WOMAC total scores in patients receiving sprifermin, compared with the placebo (mean difference (MD) = 3.23, 95% CI 0.76-5.69; I² = 0%; P = 0.01). Further, sprifermin injection patients gained more, and lost less, cartilage thickness and volume in total femorotibial joint (cartilage thickness: standardized mean differences (SMD) = 0.55, 95% CI 0.26-0.84; I² = 78%; P = 0.0002; cartilage volume: SMD = 0.39, 95% CI 0.20-0.58; I² = 49%; P < 0.0001). Changes in the cartilage surface morphology of the medial tibio-femoral joint (MD = -0.30, 95% CI -0.44 to -0.16; I² = 0%; P < 0.0001) and patello-femoral joint (MD = -0.22; 95% CI -0.37 to -0.07; I² = 0%; P = 0.004) showed a significant difference between the sprifermin and placebo injections. Moreover, there were no significant differences between sprifermin and the placebo in the risk of treatment-emergent adverse events (OR = 1.05; 95% CI 0.52-2.14; I² = 48%; P = 0.89).

CONCLUSION

The data from the included studies provide strong evidence to determine the effect of intra-articular sprifermin on joint structure in individuals with KOA and show no specific adverse effects. Nevertheless, intra-articular sprifermin did not likely have any positive effect on symptom alleviation.

Role of extracellular signal-regulated kinase 1/2 signaling underlying cardiac hypertrophy

Cardiac hypertrophy is the result of increased myocardial cell size responding to an increased workload and developmental signals. These extrinsic and intrinsic stimuli as key drivers of cardiac hypertrophy have spurred efforts to target their associated signaling pathways. The extracellular signal-regulated kinases 1/2 (ERK1/2), as an essential member of mitogen-activated protein kinases (MAPKs), has been widely recognized for promoting cardiac growth. Several modified transgenic mouse models have been generated through either affecting the upstream kinase to change ERK1/2 activity, manipulating the direct role of ERK1/2 in the heart, or targeting phosphatases or MAPK scaffold proteins to alter total ERK1/2 activity in response to an increased workload. Using these models, both regulation of the upstream events and modulation of each isoform and indirect effector could provide important insights into how ERK1/2 modulates cardiomyocyte biology. Furthermore, a plethora of compounds, inhibitors, and regulators have emerged in consideration of ERK, or its MAPK kinases, are possible therapeutic targets against cardiac hypertrophic diseases. Herein, is a review of the available evidence regarding the exact role of ERK1/2 in regulating cardiac hypertrophy and a discussion of pharmacological strategy for treatment of cardiac hypertrophy.

Infrapatellar Fat Pad and Knee Osteoarthritis

Osteoarthritis is the most prevalent arthritis typically characterized by degradation of cartilage. However, its pathogenesis is not fully understood. Currently, osteoarthritis is best considered a disease of the whole "joint organ". Infrapatellar fat pad (IFP), an adipose tissue near synovium, is now attaching importance to researchers for its inflammatory phenotype. In this narrative review, a large body of evidence has been gathered for the involvement of IFP in the development of knee osteoarthritis. Additionally, the underlying mechanisms of how IFP can be involved in this process have been proposed. However, further investigations are needed to better understand its precise role in this process and its underlying mechanism, and beyond that, to develop new strategies to slow down the degenerative process and explore an effective and timely diagnosis of the disease.

Mechanotransduction of stem cells for tendon repair

Tendon is a mechanosensitive tissue that transmits force from muscle to bone. Physiological loading contributes to maintaining the homeostasis and adaptation of tendon, but aberrant loading may lead to injury or failed repair. It is shown that stem cells respond to mechanical loading and play an essential role in both acute and chronic injuries, as well as in tendon repair. In the process of mechanotransduction, mechanical loading is detected by mechanosensors that regulate cell differentiation and proliferation via several signaling pathways. In order to better understand the stem-cell response to mechanical stimulation and the potential mechanism of the tendon repair process, in this review, we summarize the source and role of endogenous and exogenous stem cells active in tendon repair, describe the mechanical response of stem cells, and finally, highlight the mechanotransduction process and underlying signaling pathways.

Post-traumatic osteoarthritis following ACL injury

Post-traumatic osteoarthritis (PTOA) develops after joint injury. Specifically, patients with anterior cruciate ligament (ACL) injury have a high risk of developing PTOA. In this review, we outline the incidence of ACL injury that progresses to PTOA, analyze the role of ACL reconstruction in preventing PTOA, suggest possible mechanisms thought to be responsible for PTOA, evaluate current diagnostic methods for detecting early OA, and discuss potential interventions to combat PTOA. We also identify important directions for future research. Although much work has been done, the incidence of PTOA among patients with a history of ACL injury remains high due to the complexity of ACL injury progression to PTOA, the lack of sensitive and easily accessible diagnostic methods to detect OA development, and the limitations of current treatments. A number of factors are thought to be involved in the underlying mechanism, including structural factors, biological factors, mechanical factors, and neuromuscular factor. Since there is a clear "start point" for PTOA, early detection and intervention is of great importance. Currently, imaging modalities and specific biomarkers allow early detection of PTOA. However, none of them is both sensitive and easily accessible. After ACL injury, many patients undergo surgical reconstruction of ACL to restore joint stability and prevent excessive loading. However, convincing evidence is still lacking for the superiority of ACL-R to conservative management in term of the incidence of PTOA. As for non-surgical treatment such as anti-cytokine and chemokine interventions, most of them are investigated in animal studies and have not been applied to humans. A complete understanding of mechanisms to stratify the patients into different subgroups on the basis of risk factors is critical. And the improvement of standardized and quantitative assessment techniques is necessary to guide intervention. Moreover, treatments targeted toward different pathogenic pathways may be crucial to the management of PTOA in the future.

Transcranial direct current stimulation improves the swallowing function in patients with cricopharyngeal muscle dysfunction following a brainstem stroke

OBJECTIVE

This study investigated the effects of transcranial direct current stimulation (tDCS) combined with conventional swallowing training on the swallowing function in brainstem stroke patients with cricopharyngeal muscle dysfunction (CPD).

METHODS

Twenty-eight brainstem stroke patients with CPD were assigned randomly to an anodal tDCS group or a sham tDCS group. The patients received anodal tDCS or sham tDCS over the bilateral oesophageal cortical area combined with simultaneous catheter balloon dilatation and conventional swallowing therapy for 20 days. Swallowing function was assessed using the functional oral intake scale (FOIS) and the functional dysphagia scale (FDS) and by measuring the pharyngoesophageal Segment Opening (PESO) before and immediately after the intervention.

RESULTS

Both groups showed a significant improvement in the FDS, FOIS and PESO scores immediately after the intervention (all p < .005). However, compared with the sham stimulation group, the anodal tDCS group showed greater improvements in the FDS, FOIS and PESO scores immediately after the intervention (all p < .005).

CONCLUSION

The bihemispheric anodal tDCS combined with simultaneous catheter balloon dilatation and conventional swallowing therapy effectively improves the swallowing function in patients with CPD caused by a brainstem stroke. tDCS may be an effective adjuvant therapy in CPD rehabilitation.

An EZ-Diffusion Model Analysis of Attentional Ability in Patients With Retinal Pigmentosa

Retinitis pigmentosa (RP) is characterized by visual acuity decrease and visual field loss. However, the impact of visual field loss on the cognitive performance of RP patients remains unknown. In the present study, in order to understand whether and how RP affects spatial processing and attentional function, one spatial processing task and three attentional tasks were conducted on RP patients and healthy controls. In addition, an EZ-diffusion model was performed for further data analysis with four parameters, mean decision time, non-decision time, drift rate, and boundary separation. It was found that in the spatial processing task, compared with the control group, the RP group exhibited a slower response speed in large and medium visual eccentricities, and slower drift rate for the large stimulus, which is strongly verified by the significant linear correlation between the visual field eccentricity with both reaction time (p = 0.047) and non-decision time (p = 0.043) in RP patients. In the attentional orienting task and the attentional switching task, RP exerted a reduction of speed and an increase of non-decision time on every condition, with a decrease of drift rate in the orienting task and boundary separation in the switching task. In addition, the switching cost for large stimulus was observed in the control group but not in the RP group. The stop-signal task demonstrated similar inhibition function between the two groups. These findings implied that RP exerted the impairment of spatial cognition correlated with the visual field eccentricity, mainly in the peripheral visual field. Moreover, specific to the peripheral visual field, RP patients had deficits in the attentional orienting and flexibility but not in the attentional inhibition.

Bidirectional association between metabolic syndrome and osteoarthritis: a meta-analysis of observational studies

BACKGROUND

Emerging observational studies suggest an association between metabolic syndrome (MetS) and osteoarthritis (OA). This meta-analysis was conducted to examine whether or not there is a bidirectional relationship between MetS and OA.

METHODS

The PubMed and Embase databases were searched from their inception to October 2019. We selected studies according to predefined criteria. Random effects were selected to calculate two sets of pooled risk estimates: MetS predicting OA and OA predicting MetS.

RESULTS

A total of seven cross-sectional studies and four cohort studies met the criteria for MetS predicting the onset of OA. Another six cross-sectional studies and one cohort study met the criteria for OA predicting the onset of MetS. The pooled odds risk (OR) for OA incidences associated with baseline MetS was 1.45 (95% CI 1.27-1.66). The OR for MetS incidences associated with baseline OA was 1.90 (95% CI 1.11-3.27). In an overall analysis, we found that MetS was associated with prevalent OA in both cross-sectional studies (OR = 1.32, 95% CI 1.21-1.44) and cohort studies (OR = 1.76, 95% CI 1.29-2.42). No indication of heterogeneity was found in the cross-sectional studies (p = 0.395, I² = 4.8%), whereas substantial heterogeneity was detected in the cohort studies (p = 0.000, I² = 79.3%).

CONCLUSION

Meta-analysis indicated a bidirectional association between MetS and OA. We advise that patients with MetS should monitor their OA status early and carefully, and vice versa.

Photonic crystal for graphene plasmons

Photonic crystals are commonly implemented in media with periodically varying optical properties. Photonic crystals enable exquisite control of light propagation in integrated optical circuits, and also emulate advanced physical concepts. However, common photonic crystals are unfit for in-operando on/off controls. We overcome this limitation and demonstrate a broadly tunable two-dimensional photonic crystal for surface plasmon polaritons. Our platform consists of a continuous graphene monolayer integrated in a back-gated platform with nano-structured gate insulators. Infrared nano-imaging reveals the formation of a photonic bandgap and strong modulation of the local plasmonic density of states that can be turned on/off or gradually tuned by the applied gate voltage. We also implement an artificial domain wall which supports highly confined one-dimensional plasmonic modes. Our electrostatically-tunable photonic crystals are derived from standard metal oxide semiconductor field effect transistor technology and pave a way for practical on-chip light manipulation.

Traditional photonic crystals consist of periodic media with a pre-defined optical response. Here, the authors combine nanostructured back-gate insulators with a continuous layer of graphene to demonstrate an electrically tunable two-dimensional photonic crystal suitable for controlling the propagation of surface plasmon polaritons.

Soliton superlattices in twisted hexagonal boron nitride

Properties of atomic van der Waals heterostructures are profoundly influenced by interlayer coupling, which critically depends on stacking of the proximal layers. Rotational misalignment or lattice mismatch of the layers gives rise to a periodic modulation of the stacking, the moiré superlattice. Provided the superlattice period extends over many unit cells, the coupled layers undergo lattice relaxation, leading to the concentration of strain at line defects - solitons - separating large area commensurate domains. We visualize such long-range periodic superstructures in thin crystals of hexagonal boron nitride using atomic-force microscopy and nano-infrared spectroscopy. The solitons form sub-surface hexagonal networks with periods of a few hundred nanometers. We analyze the topography and infrared contrast of these networks to obtain spatial distribution of local strain and its effect on the infrared-active phonons of hBN.

Effect of an indwelling nasogastric tube on swallowing function in elderly post-stroke dysphagia patients with long-term nasal feeding

BACKGROUND

In clinical practice, a large number of post-stroke survivors require nasogastric tube (NGT) placement and nasal feeding for a relatively long period. However, its impact on the swallowing function remains largely unknown. This study examines the impact of prolonged placement of an NGT on the swallowing function of elderly post-stroke patients.

METHODS

The participants of this study were 30 elderly post-stroke patients who had been using an NGT for more than 2 months. A videofluoroscopic swallowing study (VFSS) was performed before and 5 h after removal of the NGT. The following parameters were analyzed and compared, the functional dysphagia scale (FDS), residue in the valleculae, residue in the pyriform sinuses, and the penetration-aspiration scale (PAS). In addition, prior to the VFSS, the pharynx and larynx were examined using a fiberoptic laryngoscope.

RESULTS

Significant differences were observed between the total scores of the FDS, pharyngeal transit times (PTTs), the residue in the valleculae, and the residue in the pyriform sinuses before and after the NGT removal, suggesting an improved swallowing function following the removal of the NGT. A significantly lower penetration-aspiration degree was found after removing the NGT compared with that before its removal. In addition, examinations using the fiberoptic laryngoscope showed that laryngopharyngeal edema was present in three quarters of the patients.

CONCLUSIONS

Our results demonstrate that prolonged placement of the NGT had a negative impact on the swallowing function of elderly post-stroke dysphagia patients, mainly on the pharyngeal phase.

Photonic crystals for nano-light in moiré graphene superlattices

Graphene is an atomically thin plasmonic medium that supports highly confined plasmon polaritons, or nano-light, with very low loss. Electronic properties of graphene can be drastically altered when it is laid upon another graphene layer, resulting in a moiré superlattice. The relative twist angle between the two layers is a key tuning parameter of the interlayer coupling in thus-obtained twisted bilayer graphene (TBG). We studied the propagation of plasmon polaritons in TBG by infrared nano-imaging. We discovered that the atomic reconstruction occurring at small twist angles transforms the TBG into a natural plasmon photonic crystal for propagating nano-light. This discovery points to a pathway for controlling nano-light by exploiting quantum properties of graphene and other atomically layered van der Waals materials, eliminating the need for arduous top-down nanofabrication.

Mechanical Stretch Promotes the Osteogenic Differentiation of Bone Mesenchymal Stem Cells Induced by Erythropoietin

INTRODUCTION

The effects of erythropoietin (EPO) on the behaviors of bone marrow mesenchymal stem cells (BMSCs) subjected to mechanical stretch remain unclear. This study was therefore aimed at establishing the dose-response effect of EPO stimulation on rat BMSCs and investigating the effects of mechanical stretch combined with EPO on the proliferation and osteogenic differentiation of BMSCs.

MATERIAL AND METHODS

The proliferation and osteogenic differentiation of rat BMSCs were examined and compared using EPO with different concentrations. Thereafter, BMSCs were subjected to 10% elongation using a Flexcell strain unit, combined with 20 IU/ml EPO. The proliferation of BMSCs was detected by Cell Counting Kit-8, colony formation assay, and cell cycle assay; meanwhile, the mRNA expression levels of Ets-1, C-myc, Ccnd1, and C-fos were detected by reverse transcription and real-time quantitative PCR (qPCR). The osteogenic differentiation of BMSCs was detected by alkaline phosphatase (ALP) staining, and the mRNA expression levels of ALP, OCN, COL, and Runx2 were detected by qPCR. The role of the extracellular signal-regulated kinases 1/2 (ERK1/2) in the osteogenesis of BMSCs stimulated by mechanical stretch combined with 20 IU/ml EPO was examined by Western blot.

RESULTS

Our results showed that effects of EPO on BMSCs included a dose-response relationship, with the 20 IU/ml EPO yielding the largest. Mechanical stretch combined with 20 IU/ml EPO promoted proliferation and osteogenic differentiation of BMSCs. The increase in ALP, mineral deposition, and osteoblastic genes induced by the mechanical stretch-EPO combination was inhibited by U0126, an ERK1/2 inhibitor.

CONCLUSION

EPO was able to promote the proliferation and osteogenic differentiation of BMSCs, and these effects were enhanced when combined with mechanical stretch. The underlying mechanism may be related to the activation of the ERK1/2 signaling pathway.

Response of decorin to different intensity treadmill running

Decorin is widely understood to affect collagen fibrillogenesis. However, little is understood about its response to various mechanical loading conditions. In the present study, 36 Wistar rats were randomly divided into control (CON), moderate treadmill running (MTR) and strenuous treadmill running (STR) groups. Animals in the MTR and STR groups were subjected to a 4‑ or 8‑week treadmill running protocol. Subsequently, all Achilles tendons were harvested to perform histological and biochemical analyses. Decorin expression was markedly increased in the MTR group compared with the CON group at 4 and 8 weeks. Conversely, decorin expression was markedly decreased in the STR group compared with the CON and MTR group at 4 and 8 weeks. Furthermore, between the two time points, decorin expression levels were significantly increased in the MTR group, whereas they were markedly decreased in the STR group. These results suggested that MTR exercise may induce increased decorin expression via a balance of MMP‑2 and TIMP‑2, improving tendon structure and function. However, STR exercise may result in degradation of decorin due to an imbalance of MMP‑2 and TIMP‑2, with a bias to MMP‑2, resulting in a predisposition to tendinopathy.

Intensity‑dependent effect of treadmill running on differentiation of rat bone marrow stromal cells

The effect of running on bone mass depends on its intensity. However, the underlying molecular mechanism that associates running intensity with bone mass is unclear. The current study examined the effects of treadmill running at different intensities on bone mass and osteogenic differentiation of bone marrow stromal cells (BMSCs) in a rat model. A total of 24 male Wistar rats were randomly divided into groups and subjected to no running (Con group), low‑intensity running (LIR group), moderate‑intensity running (MIR group), and high‑intensity running (HIR group). Histological, immunohistochemistry and micro‑CT examinations were performed on the femora harvested after 8 weeks of treadmill running. The study demonstrated that treadmill running affected trabecular bone mass in an intensity‑dependent manner. In addition, such an intensity‑dependent effect was also demonstrated on the osteogenic and adipogenic differentiation and proliferation of BMSCs. Furthermore, the Wnt/β‑catenin signaling pathway may be involved in the running‑induced increase in bone mass in rats in the MIR group. There appears to be a biomechanical 'window', in which running‑induced strain signals can increase the number of BMSCs and progenitor cells (specific to the osteoblast lineage) causing upregulation of osteogenesis and downregulation of adipogenesis of BMSCs. This finding may provide insight into the molecular and cellular mechanisms responsible for bone homeostasis.

Intensity-dependent effect of treadmill running on rat Achilles tendon

It is understood that mechanical loading may affect tendon properties. However, how different mechanical loading conditions may affect tendons remains unknown. The present study aimed to investigate the effect of treadmill running at various intensities on rat Achilles tendon. A total of 18 male Wistar rats were randomly assigned to one of three groups: Control (CON), medium-intensity running (MIR), and high-intensity running (HIR). Following 8 weeks of treadmill running protocols, all Achilles tendons were harvested for histological observation and gene expression analysis. Significant morphological changes were observed with regular and large diameter collagen fibrils in the MIR group, whereas irregular and small diameter collagen fibrils were observed in the HIR group. Collagen type I was significantly upregulated in the MIR group compared with the CON group, and downregulated in the HIR group compared with the CON or MIR groups (P<0.05). However, collagen type III was significantly upregulated in the HIR group in comparison with the CON or MIR groups (P<0.05). Furthermore, the expression of matrix metallopeptidase-13 was significantly increased in the MIR and HIR groups compared with the CON group (P<0.05). The expression of tissue inhibitor of metalloproteinases-1 was increased in the MIR group compared with the CON group, but decreased in the HIR group compared with the CON and MIR groups (P<0.05). Additionally, decorin expression was significantly higher in the MIR group compared with the CON group, and significantly decreased in the HIR group compared with the CON or MIR groups (P<0.05). A converse pattern of changes in biglycan expression was identified among the three groups. Aggrecan expression was significantly higher in the HIR group compared with the CON or MIR groups (P<0.05). These findings indicated that moderate exercise may induce increased collagen synthesis and organize regular and large collagen fibers, thus benefiting the Achilles tendon. However, overuse during exercise may result in collagen degradation and disturbance, which predisposes individuals to injury.

Effects of methamphetamine abuse on spatial cognitive function

Methamphetamine (MA) abuse has been rising rapidly over the past decade, however, its impact in spatial cognitive function remains unknown. To understand its effect on visuospatial ability and spatial orientation ability, 40 MA users and 40 non-MA users conducted the Simple Reaction Task (Task 1), the Spatial Orientation Task (Task 2), and the Mental Rotation Task (Task 3), respectively. There was no significant difference in either accuracy or reaction time (RT) between 2 groups in Task 1. During Task 2, in comparison with non-MA users, MA users performed poorer on RT, but not in accuracy for foot and hand stimuli. In addition, both non-MA and MA users responded much more quickly to upward stimuli than downward stimuli on vertical surface, however, only non-MA users exhibited leftward visual field advantage in horizontal orientation processing. As for Task 3, MA users exhibited poorer performance and more errors than their healthy counterparts. For each group, linear relationship was revealed between RT and orientation angle, whereas MA abuse led to longer intercept for all stimuli involved. Our findings suggested that MA abuse may lead to a general deficit in the visuospatial ability and the spatial orientation ability with more serious impact in the former.

Exercise affects biological characteristics of mesenchymal stromal cells derived from bone marrow and adipose tissue

Both bone marrow mesenchymal stromal cells (BMSCs) and adipose-derived mesenchymal stromal cells (ADSCs) are good sources for tissue engineering. To maximize therapeutic efficacy of MSCs, an appropriate source of MSCs should be selected according to their own inherent characteristics for future clinical application. Hence, this study was conducted to compare proliferative, differential and antiapoptosis abilities of both MSCs derived from exercised and sedentary rats under normal and hypoxia/serum deprivation conditions (H/SD). Our results showed that exercise may enhance proliferative ability and decrease adipogenic ability of BMSCs and ADSCs. However, positive effect of exercise on osteogenesis was only observed for BMSCs in either environment. Little effect was observed on the antiapoptotic ability of both MSC types. It was also suggested that biological characteristics of both types were partly changed. It is therefore believed that BMSCs derived from exercised rat on early passage may be a good cell source for bone tissue engineering.

Effects of treadmill running with different intensity on rat subchondral bone

Subchondral bone (SB) is recognized as a key factor in normal joint protection, not only does it provide a shock absorbing and supportive function for the cartilage, but it may also be important for cartilage metabolism. Mechanical loading is considered to be a critical regulator of skeletal homeostasis, including bone and cartilage. It is suggested that both cartilage and bone may respond to mechanical loading in an intensity-dependent manner. In this report, we have discovered that the subchondral plate became thicker with higher bone mineral density (BMD) and lower porosity, while trabecular bone became more plate-like and denser with higher BMD in high-intensity running (HIR) group. Further, HIR led to highly remodeled, less mineralized, and stiffer subchondral plate and trabecular bone. On the contrary, low-intensity running and moderate-intensity running failed to result in considerable changes in microstructure, composition and hardness. Our findings suggested that running affects SB in an intensity-dependent manner. In addition, HIR may induce change in organization and composition of SB, and consequently alter its mechanical properties. HIR-induced "brittle and stiff" SB may adversely affect the overlying articular cartilage.

MiR-451 suppresses proliferation, migration and promotes apoptosis of the human osteosarcoma by targeting macrophage migration inhibitory factor

Previous studies have shown that MiR-451 plays an important role in human osteosarcoma carcinogenesis, but the underlying mechanism by which MiR-451 affects the osteosarcoma has not been fully understood. This study intends to uncover the mechanism by which MiR-451 functions as a tumor suppressor. The expression of MiR-451 in osteosarcoma tissues and osteosarcoma cell lines was monitored by real-time PCR. The proliferation ability was examined by MTT and cell cycle assay. The migration and apoptosis of cells were monitored by migration assay and flow cytometry, respectively. Moreover, the angiogenesis of HUVEC cells transfected with MiR-451 mimics was examined by tube formation assay. The effect of MiR-451 on MIF was determined by luciferase assays and Western blot assay. The results showed that MiR-451 expression level was significantly reduced in the osteosarcoma compared with normal bone tissues. Overexpression of MiR-451 significantly attenuated the proliferation and migration, and induced the apoptosis of osteosarcoma cells. Furthermore, the angiogenesis of HUVEC cells transfected with MiR-451 mimics was assayed and the decreased angiogenic ability was detected compared to the controls. Finally, we demonstrated that MiR-451 overexpression inhibited the malignant behavior of osteosarcoma by downregulating MIF. These findings suggest that MiR-451 may act as a tumor suppressor in osteosarcoma. MiR-451 inhibited cell proliferation, migration and angiogenesis and promoted apoptosis of human osteosarcoma cells, at least partially, by inhibiting the expression of MIF. MiR-451/MIF may be a novel therapeutic target in treatment of osteosarcoma.

miR-451 inhibits cell growth, migration and angiogenesis in human osteosarcoma via down-regulating IL 6R

Osteosarcoma (OS) has become one of the most common primary malignant tumors in the children and adolescents with a poor prognosis owing to its high malignant and metastatic potential. Although increasing evidence indicates that miR-451 could inhibit the growth and metastasis of OS, its effect on angiogenesis in OS is still very poor. What is more, the mechanism by which miR-451 affects the OS has not been fully elucidated. In the present study, miR-451 was reduced in human osteosarcoma tissues compared with the adjacent bone tissues, and the introduction of miR-451 dramatically inhibited the growth, migration and angiogenesis in OS. Additionally, it was suggested that IL 6R is a direct target gene of miR-451. Silencing of IL 6R suppressed the growth, migration and angiogenesis of OS, which was consistent with the effect of overexpression of miR-451. In conclusion, our data demonstrate that miR-451 may function as a potential suppressor of tumor growth, migration and angiogenesis in OS via down-regulating IL 6R, suggesting a promising therapeutic avenue for managing OS.

Delivery of curcumin by directed self-assembled micelles enhances therapeutic treatment of non-small-cell lung cancer

BACKGROUND

It has been widely reported that curcumin (CUR) exhibits anticancer activity and triggers the apoptosis of human A549 non-small-cell lung cancer (NSCLC) cells. However, its application is limited owing to its poor solubility and bioavailability. Therefore, there is an urgent need to develop a new CUR formulation with higher water solubility and better biocompatibility for clinical application in the future.

MATERIALS AND METHODS

In this study, CUR-loaded methoxy polyethylene glycol-polylactide (CUR/mPEG-PLA) polymeric micelles were prepared by a thin-film hydration method. Their characteristics and antitumor effects were evaluated subsequently.

RESULTS

The average size of CUR/mPEG-PLA micelles was 34.9±2.1 nm with its polydispersity index (PDI) in the range of 0.067-0.168. The encapsulation efficiency and drug loading were 90.2%±0.78% and 9.1%±0.07%, respectively. CUR was constantly released from the CUR/mPEG-PLA micelles, and its cellular uptake in A549 cells was significantly increased. It was also found that CUR/mPEG-PLA micelles inhibited A549 cell proliferation, increased the cell cytotoxicity, induced G2/M stage arrest and promoted cell apoptosis. Moreover, the CUR/mPEG-PLA micelles suppressed the migration and invasion of A549 cells more obviously than free CUR. Additionally, CUR/mPEG-PLA micelles inhibited human umbilical vein endothelial cells migration, invasion and corresponding tube formation, implying the antiangiogenesis ability. Its enhanced antitumor mechanism may be related to the reduced expression of vascular endothelial growth factor, matrix metalloproteinase (MMP)-2, MMP-9 and Bcl-2 as well as the increased expression of Bax.

CONCLUSION

The mPEG-PLA copolymer micelles can serve as an efficient carrier for CUR. The CUR/mPEG-PLA micelles have promising clinical potential in treating NSCLC.

Ultraconfined Plasmonic Hotspots Inside Graphene Nanobubbles

We report on a nanoinfrared (IR) imaging study of ultraconfined plasmonic hotspots inside graphene nanobubbles formed in graphene/hexagonal boron nitride (hBN) heterostructures. The volume of these plasmonic hotspots is more than one-million-times smaller than what could be achieved by free-space IR photons, and their real-space distributions are controlled by the sizes and shapes of the nanobubbles. Theoretical analysis indicates that the observed plasmonic hotspots are formed due to a significant increase of the local plasmon wavelength in the nanobubble regions. Such an increase is attributed to the high sensitivity of graphene plasmons to its dielectric environment. Our work presents a novel scheme for plasmonic hotspot formation and sheds light on future applications of graphene nanobubbles for plasmon-enhanced IR spectroscopy.

Thoracic spinal epidural abscess caused by fishbone perforation: A case report and review of literature

RATIONALE

Ingestion of a fishbone is a common cause of esophageal injury, but spinal epidural abscess (SEA) is a rare condition due to the esophageal penetration by a swallowed fishbone. Prompt diagnosis can be seldom made owing to incomplete patient history taking and difficulties in imaging evidence identification.

PATIENT CONCERNS

We describe the case of a 62-year-old woman who was stuck in her throat by a fishbone, and complained of back pain, paresis of the lower limbs and fever, successively. To our knowledge, this is the first case report that we know of thoracic SEA caused by fishbone perforation.

DIAGNOSES

About 20 days after the onset of severe back pain, she was diagnosed with SEA based on the clinical presentation and imaging findings.

INTERVENTIONS

Antibiotic therapy and rehabilitation therapy were carried out afterwards. However, due to exacerbation of her condition, surgical intervention had to be taken eventually.

OUTCOMES

It is quite unfortunate for this patient to have a poor prognosis due to a delayed diagnosis and an improper management.

LESSONS

A number of lessons can be learnt from this case.

Strenuous Treadmill Running Induces a Chondrocyte Phenotype in Rat Achilles Tendons

BACKGROUND Although tendinopathy is common, its underlying pathogenesis is poorly understood. This study aimed to investigate the possible pathogenesis of tendinopathy. MATERIAL AND METHODS In this study, a total of 24 rats were randomly and evenly divided into a control (CON) group and a strenuous treadmill running (STR) group. Animals in the STR group were subjected to a 12-week treadmill running protocol. Subsequently, all Achilles tendons were harvested to perform histological observation or biochemical analyses. RESULTS Histologically, hypercellularity and round cells, as well as disorganized collagen fibrils, were presented in rat Achilles tendon sections from the STR group. Furthermore, our results showed that the expression of aggrecan, collagen type II (Col II), and Sex-Determining Region Y Box 9 (Sox 9) were markedly increased in the STR group compared with that in the CON group. Additionally, the mRNA expression of bone morphogenetic protein-2 (BMP-2) and biglycan was significantly up-regulated in the STR group in contrast to that in CON group. CONCLUSIONS These results suggest that a 12-week strenuous treadmill running regimen can induce chondrocyte phenotype in rat Achilles tendons through chondrogenic differentiation of tendon stem cells (TSCs) by BMP-2 signaling.

Development and Prevention of Running-Related Osteoarthritis

Studies investigating the effect of running on risk for developing osteoarthritis at weight-bearing joints have reported with conflicting results. Generally, moderate-level running is not likely detrimental to joint health. However, many factors may be associated with the increased risk of developing osteoarthritis in runners. Factors often implicated in the development of osteoarthritis comprise those that increase joint vulnerability and those which increase joint loading. It is therefore suggested that running has different effects on different people. Efforts should be made to identify those with joint vulnerability and joint loading, and measures should be taken to have those factors and/or their running programs modified to run safely. Further investigations are needed to examine the effect of running on joint health under different conditions to confirm the association between exposure to risk factors and development of osteoarthritis, as well as to validate the effectiveness of measures for preventing running-related osteoarthritis.

Tunable Plasmonic Reflection by Bound 1D Electron States in a 2D Dirac Metal

We show that the surface plasmons of a two-dimensional Dirac metal such as graphene can be reflected by linelike perturbations hosting one-dimensional electron states. The reflection originates from a strong enhancement of the local optical conductivity caused by optical transitions involving these bound states. We propose that the bound states can be systematically created, controlled, and liquidated by an ultranarrow electrostatic gate. Using infrared nanoimaging, we obtain experimental evidence for the locally enhanced conductivity of graphene induced by a carbon nanotube gate, which supports this theoretical concept.

Spatial and temporal changes of subchondral bone proceed to articular cartilage degeneration in rats subjected to knee immobilization

This study was aimed to investigate the spatial and temporal changes of subchondral bone and its overlying articular cartilage in rats following knee immobilization. A total of 36 male Wistar rats (11-13 months old) were assigned randomly and evenly into 3 groups. For each group, knee joints in 6 rats were immobilized unilaterally for 1, 4, or 8 weeks, respectively, while the remaining rats were allowed free activity and served as external control groups. For each animal, femurs at both sides were dissected after sacrificed. The distal part of femur was examined by micro-CT. Subsequently, femoral condyles were collected for further histological observation and analysis. For articular cartilage, significant changes were observed only at 4 and 8 weeks of immobilization. The thickness of articular cartilage and chondrocytes numbers decreased with time. However, significant changes in subchondral bone were defined by micro-CT following immobilization in a time-dependent manner. Immobilization led to a thinner and more porous subchondral bone plate, as well as a reduction in trabecular thickness and separation with a more rod-like architecture. Changes in subchondral bone occurred earlier than in articular cartilage. More importantly, immobilization-induced changes in subchondral bone may contribute, at least partially, to changes in its overlying articular cartilage.

Different responses of articular cartilage to strenuous running and joint immobilization

OBJECTIVE

To compare the pathological changes in cartilage derived from rats that developed osteoarthritis either by joint immobilization or by strenuous treadmill running in order to better understand their respective pathomechanism.

METHOD

A total of 24 male Wistar rats were randomly assigned to three groups: sedentary control (CON), immobilization (IM), and strenuous running (SR). For rats in the IM group, unilateral knee joint was immobilized in flexion. Rats in the SR group underwent treadmill running with high intensity. Eight weeks later, all animals were sacrificed. Femoral condyles were collected to take histological observation for cartilage characteristic and immunohistochemistry for collagen type II. In addition, cartilage samples were obtained to assess gene expression of aggrecan, collagen type II, biglycan, and fibromodulin by quantitative RT-PCR.

RESULTS

Gross and histological observation showed osteoarthritic changes in groups SR and IM; however, more severe cartilage degradation was revealed in the latter. Proteoglycan and collagen II content decreased in groups SR and IM in comparison to group CON, with more loss in group IM. In group SR, mRNA levels in femoral cartilage were found to be unaltered for all the molecules measured. On the contrary, these molecules were significantly downregulated in group IM.

CONCLUSION

Differences in gross observation, histological characteristics, and gene expression of proteoglycans and collagen II suggest that both knee immobilization and strenuous running would lead to degenerative change of cartilage, but at different stages of the degenerative process.

Plasmons in graphene moiré superlattices

Moiré patterns are periodic superlattice structures that appear when two crystals with a minor lattice mismatch are superimposed. A prominent recent example is that of monolayer graphene placed on a crystal of hexagonal boron nitride. As a result of the moiré pattern superlattice created by this stacking, the electronic band structure of graphene is radically altered, acquiring satellite sub-Dirac cones at the superlattice zone boundaries. To probe the dynamical response of the moiré graphene, we use infrared (IR) nano-imaging to explore propagation of surface plasmons, collective oscillations of electrons coupled to IR light. We show that interband transitions associated with the superlattice mini-bands in concert with free electrons in the Dirac bands produce two additive contributions to composite IR plasmons in graphene moiré superstructures. This novel form of collective modes is likely to be generic to other forms of moiré-forming superlattices, including van der Waals heterostructures.

Tunneling Plasmonics in Bilayer Graphene

We report experimental signatures of plasmonic effects due to electron tunneling between adjacent graphene layers. At subnanometer separation, such layers can form either a strongly coupled bilayer graphene with a Bernal stacking or a weakly coupled double-layer graphene with a random stacking order. Effects due to interlayer tunneling dominate in the former case but are negligible in the latter. We found through infrared nanoimaging that bilayer graphene supports plasmons with a higher degree of confinement compared to single- and double-layer graphene, a direct consequence of interlayer tunneling. Moreover, we were able to shut off plasmons in bilayer graphene through gating within a wide voltage range. Theoretical modeling indicates that such a plasmon-off region is directly linked to a gapped insulating state of bilayer graphene, yet another implication of interlayer tunneling. Our work uncovers essential plasmonic properties in bilayer graphene and suggests a possibility to achieve novel plasmonic functionalities in graphene few-layers.

Angular velocity affects trunk muscle strength and EMG activation during isokinetic axial rotation

OBJECTIVE

To evaluate trunk muscle strength and EMG activation during isokinetic axial rotation at different angular velocities.

METHOD

Twenty-four healthy young men performed isokinetic axial rotation in right and left directions at 30, 60, and 120 degrees per second angular velocity. Simultaneously, surface EMG was recorded on external oblique (EO), internal oblique (IO), and latissimus dorsi (LD) bilaterally.

RESULTS

In each direction, with the increase of angular velocity, peak torque decreased, whereas peak power increased. During isokinetic axial rotation, contralateral EO as well as ipsilateral IO and LD acted as primary agonists, whereas, ipsilateral EO as well as contralateral IO and LD acted as primary antagonistic muscles. For each primary agonist, the root mean square values decreased with the increase of angular velocity. Antagonist coactiviation was observed at each velocity; however, it appears to be higher with the increase of angular velocity.

CONCLUSION

Our results suggest that velocity of rotation has great impact on the axial rotation torque and EMG activity. An inverse relationship of angular velocity was suggested with the axial rotation torque as well as root mean square value of individual trunk muscle. In addition, higher velocity is associated with higher coactivation of antagonist, leading to a decrease in torque with the increase of velocity.