Stress fracture is a kind of weight-bearing lower extremity bone injury that usually occurs in athletes, recruits and other specific groups. It is one of the most important reasons that stop them from normal training and may affect athletes'career and military warfare capability. Many intrinsic and extrinsic factors may increase the risk of stress fracture, and preventive measures against these risk factors are the main direction of stress fracture prevention research. At the same time, the importance of more accurate diagnosis and treatment of stress fractures is heightened by the fact that the missed diagnosis or malpractice of stress fractures can have an adverse impact on the career of athletes or military recruits, placing an additional burden on the medical system. In this paper, the treatment and prevention of stress fractures are summarized, and the future prospects are prospected.

Objective To investigate the photodynamic effect of IR-820 and perfluoropentane (PFP) loaded phase-transition multifunctional molecular imaging probe (IR-820/PFP@PLGA NPs) on ultrasound/photoacoustic dual-mode imaging and fibroblast-like synoviocytes (FLSs) of rheumatoid arthritis (RA) in vitro. Methods The IR-820/PFP@PLGA nanoparticles were prepared by double emulsification method. The basic characteristics, thermal phase transition and photothermal effect of IR-820/PFP@PLGA nanoparticles were determined, the ultrasound/photoacoustic dual-mode imaging ability in vitro of the IR-820/PFP@PLGA nanoparticles were observed, and the generation of reactive oxygen species in vitro were evaluated. The photodynamic therapy effect of the nanoparticles on fibroblast-like synoviocytes was observed by CCK-8 method and flow cytometry. Results The prepared IR-820/PFP@PLGA nanoparticles were dark green, with a particle size of (261.8±3.2) nm and a potential of (–27.4±0.7) mV. The size of the IR-820/PFP@PLGA nanoparticles were uniform and the morphology were regular. The size of nanoparticles and the temperature of nanoparticle solution increased obviously by laser irradiation, it was positively correlated with the concentration of nanoparticles, and enhanced ultrasound imaging was observed. The photoacoustic imaging effect of nanoparticle was linearly correlated with the concentration of IR-820/PFP@PLGA nanoparticles; The singlet oxygen sensor green(SOSG) assay revealed that the nanoparticles produced a large amount of reactive oxygen species after laser irradiation with time-dependent manner; it was found by in vitro cell experiments that the nanoparticles had good biological safety, while the cytotoxicity increased along with the advanced nanoparticle concentration after laser irradiation, and also the apoptosis increased significantly. Conclusion IR-820/PFP@PLGA nanoparticles have a good dual-mode imaging and photodynamic effect on FLSs, which can provide a new idea for the integration of diagnosis and treatment for RA.

Objective To profile transcriptome dynamics in the entecavir resistant hepatitis B virus (ETV-r HBV) stably transfected cell line, and provide fundamental data for future studies to understand mechanisms of infection using this cell line. Methods ETV-r HBV stably transfected cell lines (HepG2.A64) and the corresponding isogenic cell lines (HepG2) were used to profile the transcriptome (n=3). We used DESeq2 software to analyze the sequencing results to identify differentially expressed genes with |log2 Fold Change|>2, padj<0.05. GO and KEGG functional enrichment analysis of differential genes were performed by clusterProfiler software, and then the transcriptional and protein levels of related genes in the DNA repair pathway were detected by RT-qPCR and Western blotting. Results A total of 613 differentially expressed genes were identified in the cell lines before and after stable ETV-r HBV transfection, of which 401 were up-regulated and 212 down-regulated (padj<0.05). GO and KEGG enrichment analysis showed that differentially expressed genes were mainly involved in the inflammatory response, PI3K/Akt signal pathway, PPAR signal pathway, NF-κB signal pathway and immune-related biological processes. Through the analysis of the relevant genes in the DNA repair pathway and the verification by RT-qPCR and Western blotting, it was found that after stable transfection of ETV-r HBV, the mRNA expression of RAD52 and XRCC2 genes in the DNA repair pathway decreased by 68.96%±7.59% and 69.58%±6.32%, respectively, and the protein expression decreased by 69.93%±3.88% and 26.47%±12.7%, respectively, and the differences were statistically significant (P<0.05). Conclusion Compared with the original background cell line HepG2, a lot of genes are differentially expressed at the transcription level in HBV stable cell line, and the DNA repair-related genes in the HepG2.A64 cell line had been decreased significantly.

Objective To investigate the effect of simulated high altitude and cold conditions on the model of severe abdominal infection in rabbits. Methods 60 New Zealand rabbits were randomly divided into plain group (altitude 100 m, temperature 5℃, n=20), sub-plateau group (altitude 1000 m, temperature –5℃, n=20) and plateau group (altitude 5000 m, temperature –25℃, n=20). Each group was kept in the corresponding animal feeding cabin for 14 days, then induced severe abdominal model by cecal ligation and puncture (CLP). The basic data were measured before operation, and the peripheral vein blood was extracted 24 and 72 hours after operation. The levels of C-reactive protein (CRP), procalcitonin (PCT), tumor necrosis factor-α (TNF-α), albumin (ALB), prealbumin (PAB) were measured by ELISA, and the white blood cell count (WBC) was performed. The rabbits were killed 72 hours after operation, the ascites were collected from the abdominal fluid, and collected liver, kidney and small intestine, and the pathological changes were observed by HE staining. Pearson correlation was used to analyze the correlation between the infection indexes and the high cold factors at high altitude. Results Seventy-two hours after operation, the survival rate of CLP model rabbits in plain group, sub-plateau group and plateau group was 65.0%(13/20), 35.0%(7/20), 10.0%(2/20), respectively. With the increase of altitude and the decrease of temperature, the survival rate of CLP model rabbits decreased gradually (P<0.01). All CLP rabbits began to show signs of less movement, curling, mental burnout, shortness of breath, coarse breath tone, diarrhea and eye corner exudates. In the plain group, the anal temperature increased continuously and then decreased slowly, with the highest value of 39.2℃ and the lowest value of 36.5℃; in the sub-plateau group, the anal temperature increased sharply and then decreased gradually, with the highest value of 40.6℃ and the lowest value of 34.9℃; in the plateau group, the anal temperature decreased rapidly, with the highest value of 41.2℃ and the lowest value of 34.0℃. At 24 and 72 hours after operation, the levels of PCT and TNF-α in venous blood of CLP model rabbits in plateau group and sub-plateau group were higher than those in plain group, and those in plateau group were higher than those in sub-plateau group (P<0.05); at 72 hours after operation, the levels of ALB and PAB in venous blood of CLP model rabbits in plateau group and sub-plateau group were lower than those in plain group, and those in plateau group were lower than those in sub-plateau group (P<0.05). Pearson correlation analysis showed that PCT, TNF-α were positively correlated with high altitude cold factors (r=0.288, r=0.368, P<0.05), WBC and CRP had no significant correlation with them (r=0.462, r=0.397, P>0.05). The results of ascite culture showed that 51, 69 and 107 pathogens were isolated from plain group, sub-plateau group and plateau group respectively, among which gram-negative bacteria accounted for 52.94%(27/51), 49.27%(34/69), 42.06%(45/107), and gram-positive bacteria accounted for 29.41%(15/51), 34.78%(24/69), 43.93%(47/107). Conclusion The high cold condition at high altitude is an important factor in the infection degree and death of CLP model rabbits. It can aggravate the infection of abdominal cavity and damage the important organ function, affect the nutrition absorption and metabolism of the body. The difference between the pathogenic bacteria and the plain area under this condition may affect the process and treatment of abdominal infection diseases, which is worth further study.

Objective To explore the analgesic effect of low-intensity exercise induced by interleukin (IL)-4 on chronic constriction injury of the sciatic nerve (CCI) mice. Methods A total of 48 male C57/BL6 mice were randomized into 6 groups(n=8): sham/sedentary group (SS group), sham/normal saline/exercise group (SNE group), sham/anti-IL-4/exercise group (SAE group), CCI/sedentary group (CS group), CCI/normal saline/exercise group (CNE group), CCI/anti-IL-4/exercise group (CAE group). After inducing CCI, mice were given low-intensity exercise from 1 to 15 days. For the SAE group and the CAE group, mice received 50 μg of IL-4 receptor blocker (IL-4Ra) 30 min before exercise through intraperitoneal injection. Behavioural tests were performed on the 3rd day (T₁), 7th day (T₂), 11th day (T₃) and 15th day (T₄) to analyze the difference of hyperalgesia. On the 15th day after CCI induction, the injured sciatic nerve and lumbar spinal cord (L₁-L₆) of all mice were collected. The levels of IL-4, IL-1Ra, IL-5, TNF-α, IL-1β, brain-derived neurotrophic factor (BDNF) and β-nerve growth factor (β-NGF) were detected by ELISA. Results The paw withdrawal mechanical threshold (PWMT) and paw withdrawal thermal latency (PWTL) values of the CNE group at T₃ and T₄ were higher than those of the CS group and CAE group (P<0.05); the IL-4 levels of the sciatic nerve and lumbar spinal cord in CNE group and CAE group were higher than those of CS group (P<0.05); the IL-1Ra and IL-5 levels of the sciatic nerve and lumbar spinal cord in CNE group were higher than those of CS group and CAE group (P<0.05); the TNF-α, IL-1β, BDNF and β-NGF levels of the sciatic nerve and lumbar spinal cord of CNE group were lower than those of CS group and CAE group (P<0.05). Conclusion Low-intensity exercise exerts the analgesic effect on mice with chronic constriction injury of sciatic nerve through IL-4.

Atherosclerotic cardiovascular disease (ASCVD) is a kind of disease including acute coronary syndrome(ACS), history of myocardial infarction (MI), stable or unstable angina pectoris (SAP, UAP), coronary artery or other blood vessel revascularization (PCI), ischemic stroke (IS), transient ischemic attack (TIA), peripheral vascular disease (PAD) and so on. It has a high morbidity rate, high disability rate, and high mortality rate in elderly patients, which puts a heavy burden on patients'families and society. But the early warning markers of ASCVD were still in the exploratory stage. Sarcopenia is a common disease in elderly individuals. A large number of studies showed that sarcopenia may be an independent risk factor for the onset and severity of ASCVD. As a comorbidity, at the same time, it may also be an independent predictor of poor prognosis of ASACVD. In addition, sarcopenia and ASCVD in elderly individuals have some common pathogenesis, such as inflammation, oxidative stress and insulin resistance. The role of sarcopenia in the pathogenesis of ASCVD in the elderly is reviewed in present paper.

Objective To investigate the effects of advanced pregnancy on DNA methylation level of hippocampus in the offspring rats. Methods 12- and 3-month-old female SD rats were mated with 3-month-old male SD rats. The offspring(s)from older mother were marked as AMA group, and those from younger mother were marked as control group. The brain and hippocampus samples of the offsprings were taken at the 7th, 14th and 28th day after birth. The mRNA levels of DNA methyltransferase (Dnmt)1, Dnmt3A and Dnmt3B were detected by real-time fluorescent quantitative PCR (RT-PCR). The protein expression levels of Dnmt1, Dnmt3A and Dnmt3B were measured by Western blotting. Immunofluorescence and ELISA were used to detect the localization and expression level of 5-methylcytosine (5-mC) in hippocampus. Results RT-PCR showed the Dnmt1 mRNA level was markedly lower in hippocampus of AMA group than that in control group on day 28 after birth (P<0.05); Western blotting analysis showed the expression level of Dnmt3A protein was obviously higher in hippocampus of the AMA group than that in control group on day 7 after birth (P<0.05), while the expression levels of Dnmt1 and Dnmt3A were lower in AMA group than those in control group on day 28 after birth (P<0.05). Immunofluorescence test showed that the 5-mC level in hippocampus was significantly higher in AMA group than that in control group on day 7 and 14 after birth (P<0.05). ELISA showed that the 5-mC level in hippocampus increased slightly but without statistical significance in AMA group than that in control group on day 7, 14 and 28 after birth (P>0.05). Conclusion Advanced pregnancy may lead to the expression disorder of Dnmts and the increased DNA methylation level in offspring's hippocampus, which may be one of the potential mechanisms of offspring's brain dysfunction.

Heatstroke is a disease with high morbidity and mortality that causes a patient's core body temperature to be higher than 40.5℃ and combined with organ dysfunction when human body exposed to high temperature, high humidity and slow air circulation environment or after strenuous exercise. Early diagnosis and early cooling can significantly improve patient prognosis, increase patient survival rate and reduce complications. The cooling measures include extravascular cooling which mainly refers to physical cooling of body surface and intravascular cooling is mainly for patients who are not suitable for physical cooling or whose diagnosis and treatment are delayed due to lack of resources, especially for patients with heatstroke, which has a better cooling effect and can improve the prognosis of patients. Currently, the commonly used intravascular cooling measures in clinical practice mainly include intravascular infusion cooling, intravascular temperature management devices cooling and continuous blood purification.This article reviews the classification, mechanism, clinical application, advantages and disadvantages of intravascular cooling.

Objective To explore the predictive value of red volume distribution width (RDW) for the clinical outcome of sepsis in the elderly. Methods Two hundred and ten elderly patients with sepsis admitted to the General Hospital of Eastern Theater Command of PLA from January 2018 to December 2019 were included. The highest Acute Physiology and Chronic Health Evaluation (APACHE Ⅱ)score and sequential organ failure (SOFA) score were calculated during sepsis. According to clinical outcome, 210 patients were divided into septic shock (n=93) /non-shock (n=117) groups; severe (n=79)/mild organ dysfunction (n=131) groups and death (n=60)/survival groups (n=150). The differences in age, sex, smoking and drinking history, medical history, APACHE Ⅱ score, SOFA score, RDW were compared between the different groups. Spearman's correlation analysis was used to analyze the correlation between RDW and APACHE Ⅱscore, SOFA score, total hospital days and ICU hospital days. Unconditional logistic regression was used to analyze the risk factors for septic shock, severe organ dysfunction and death in elderly patients with sepsis. Receiver operating characteristic (ROC) curves were adopted to analyze the predictive value of RDW, SOFA score, and APACHE Ⅱ score for septic shock and severe organ dysfunction in elderly patients with sepsis. Results The RDW, APACHE Ⅱ score, SOFA score, the incidence of severe organ dysfunction and death in the septic shock group were higher than those of the non-sepsis group; RDW, APACHE Ⅱscore, SOFA score, the incidences of septic shock and mortality in the severe organ dysfunction group were higher than those in the mild organ dysfunction group; RDW, APACHE Ⅱ score, SOFA score, the incidence of septic shock and severe organ dysfunction in the death group were higher than those in the survival group, there was a significant difference between each group (P<0.05); RDW was positively correlated with APACHE Ⅱ score, SOFA score, total hospital days and ICU hospital days (P<0.001); Elevated RDW was an independent risk factor for septic shock and severe organ dysfunction (P<0.05); the risk of septic shock and severe organ dysfunction was significantly increased when RDW>20% (P<0.05); The ROC AUC of SOFA score was 0.958, sensitivity was 0.817, specificity was 0.940, ROC AUC of RDW combined with SOFA score was 0.959, sensitivity was 0.968, specificity was 0.676 in predicting septic shock; The ROC AUC of APACHE Ⅱ score was 0.973, sensitivity was 0.911, specificity was 0.931, the ROC AUC of the RDW combined with APACHE Ⅱ score was 0.978, sensitivity was 0.972, and specificity was 0.668 in predicting severe organ dysfunction. Conclusions RDW is an independent risk factor to predict septic shock and severe organ dysfunction in elderly patients with sepsis; RDW combined with SOFA score and RDW combined with APACHE Ⅱ score have better sensitivity to predict septic shock and severe organ dysfunction than any single factor.

Objective To investigate the effect of oleanolic acid (OA) in the maturation of human induced pluripotent stem cell-derived cardiomyocytes (hiPSC-CMs) through switching pyruvate kinase type M isoforms. Methods HiPSC-CMs were derived from human induced pluripotent stem cells (hiPSCs), through sequential activation and inhibition of the Wnt signaling pathway. On day 19 hiPSC-CMs were divided into control group (RPMI 1640+B27), DMSO group (RPMI 1640+B27+2 μl DMSO), and 10 μmol/L OA group (RPMI 1640+B27+2 μl 5 mmol/L OA) and treated for 7 days, and the medium was changed every 2 days. Immunofluorescence or RT-qPCR were used to detect the expression of stem factor in hiPSCs and cardiac specific markers in hiPSC-CMs. Western blotting was used to detect the expression of PK and mitofusin 2 (MFN2). Mito-Tracker staining showed the morphology of mitochondria, and transmission electron microscope (TEM) showed the ultrastructure of mitochondria. EDU staining was used to detect cell proliferation, and flow cytometry was used to detect cell cycle. Results Immunofluorescence showed that hiPSCs expressed Nanog and Sox2, and hiPSC-CMs expressed myocardial specific markers cTnT, Cx43 and α-actinin.RT-qPCR showed that, compared with hiPSCs, significant differences (P<0.05 or P<0.01) existed in hiPSC-CMs expressed troponin I3 (TNNI3), myosin heavy chain 6 (MYH6), and myosin heavy chain 7 (MYH7). Immunofluorescence showed that, compared with control group and DMSO group, the cell area increased, sarcomere length increased, and the cell circularity decreased in hiPSC-CMs cultured with OA, and the differences were statistically significant (P<0.05); Western blotting showed that, compared with control group and DMSO group, the ratio of PKM1/PKM2 and the expression of MFN2 increased obviously, and the differences were statistically significant (P<0.05 or P<0.01), the fusion lengthening of mitochondria was observed under electron microscope, and Mito-Tracker staining showed that mitochondria formed more mature structure; EDU staining showed a decreased cell proliferation in hiPSC-CMs cultured with OA group compared with control group and DMSO group, all differences were statistically significant(P<0.05). The flow cytometry results indicated that the number of coenocytes increased in hiPSC-CMs cultured with OA group compared with control group and DMSO group. Conclusion OA can promote the maturation of cell structure, mitochondrial structure and morphology, and also can promote cell multinucleation. OA can promote hiPSC-CMs' maturation by switching pyruvate kinase type M isoforms.