Mechanism of action of Linggui Zhugan Decoction in treating non-alcoholic fatty liver disease using untargeted metabolomics approach

Background:Non-alcoholic fatty liver disease(NAFLD)is a liver disorder characterized by the accumulation and degeneration of fat in the liver cells,a condition that may further deteriorate and lead to cirrhosis and liver cancer.Numerous studies showed that metabolic dysfunction can promote NAFLD development.Linggui Zhugan Decoction(LGZGD)has therapeutic effects on NAFLD.The mechanism of LGZGD still remains unclear.This study was to examine the impact of LGZGD on the metabolic processes involved in the development of NAFLD.Methods:A mice model of NAFLD was treated with LGZGD.The therapeutic potential of LGZGD was evaluated by assessing the activity of transaminases,lipids levels of blood,and pathological changes in the liver of the mice model of NAFLD.Additionally,this study also evaluated the influence of LGZGD on liver inflammation and oxidative stress.Results:The results of untargeted metabolomics analysis showed that LGZGD reduced the disordered lipid metabolism in NAFLD mice.LGZGD improved the oxidative stress and also reduced the levels of pro-inflammatory cytokines in the liver.Untargeted metabolomics analysis of liver samples revealed that LGZGD treatment improved metabolic disorders,including alanine,aspartate,glutamate,glycerophospholipid metabolism,and citrate cycle.Further RT-qPCR and Western blot results showed that LGZGD could regulate the expression of key enzymes in the metabolic pathway of the citrate cycle,including ATP-citrate lyase(ACLY),alanine-glyoxylate aminotransferase-2(AGXT2),phosphatidylethanolamine N-methyltransferase(PEMT),and succinate dehydrogenase(SDH).Conclusion:We found that LGZGD can treat NAFLD by reducing inflammatory responses,inhibiting oxidative stress,regulating alanine,aspartate,glutamate,and glycerophospholipid metabolism,and citrate cycle pathways.

Mufangji tang ameliorates pulmonary arterial hypertension through improving vascular remodeling,inhibiting inflammatory response and oxidative stress,and inducing apoptosis

Background:Mufangji tang(MFJT)is composed of Ramulus Cinnamomi,Radix Ginseng,Cocculus orbiculatus(Linn.)DC.,and Gypsum.In clinical settings,MFJT has been effectively employed in addressing a range of respiratory disorders,notably including pulmonary arterial hypertension(PAH).However,the mechanism of action of MFJT on PAH remains unknown.Methods:In this study,a monocrotaline-induced PAH rat model was established and treated with MFJT.The therapeutic effects of MFJT on PAH rat model were evaluated.Network pharmacology was conducted to screen the possible targets for MFJT on PAH,and the molecular docking between the main active components and the core targets was carried out.The key targets identified from network pharmacology were tested.Results:Results showed significant therapeutic effects of MFJT on PAH rat model.Analysis of network pharmacology revealed several potential targets related to apoptosis,inflammation,oxidative stress,and vascular remodeling.Molecular docking showed that the key components were well docked with the core targets.Further experimental validation results that MFJT treatment induced apoptosis(downregulated Bcl-2 levels and upregulated Bax levels in lung tissue),inhibited inflammatory response and oxdative stress(decreased the levels of IL-1β,TNF-α,inducible NOS,and malondialdehyde,and increased the levels of endothelial nitric oxide synthase,nitric oxide,glutathione and superoxide dismutase),reduced the proliferation of pulmonary arterial smooth muscle cells(downregulated ET-1 andβ-catenin levels and ERK1/2 phosphorylation,increased GSK3βlevels).Conclusion:Our study revealed MFJT treatment could alleviate PAH in rats via induction of apoptosis,inhibition of inflammation and oxidative stress,and the prevention of vascular remodeling.

Global current research status and future hotspots in osteoporotic fracture based on bibliometric assessment and visualization techniques

BACKGROUND In the past decade,the evolution of themes in the field of osteoporotic fractures has changed from epidemiology and prediction of long-term morbidity,risk assessment of osteoporotic fractures,and zoledronic acid and denosumab in the treatment of osteoporosis to treatment guidelines for osteoporosis and the side effects caused by anti-osteoporotic drugs.AIM To understand the trends and hotspots in osteoporotic fracture research.METHODS Original articles were retrieved between January 1,2010,and December 31,2019,from the Web of Science Core Collection database.CiteSpace software facilitated the analysis and visualization of scientific productivity and emerging trends.RESULTS Nine studies were identified using bibliometric indices,including citation,centrality,and sigma value,which might indicate a growing trend.Through clustering,we identified six major hot subtopics.Using burst analysis,top-5 references with the strongest bursting strength after 2017 were identified,indicating a future hotspot in this field.CONCLUSION Current hot subtopics in osteoporotic fracture research include atypical femoral fractures,androgen deprivation therapy,denosumab discontinuation,hip fractures,trabecular bone score(TBS),and bone phenotype.Management and prevention of secondary fractures in patients with osteoporotic fractures,TBSs,and long-term administration strategy for zoledronic acid are expected to become research hotspots.

The mechanistic study on Wa medicine Niang-Mu-Liang medicinal liquor mitigating diabetes mellitus erectile dysfunction in rats by inhibiting ferroptosis

Background:This study aims to investigate the therapeutic effect of Wa medicine Niang-Mu-Liang medicinal liquor(NML)on rats with diabetes mellitus erectile dysfunction(DMED)and its impact on the ferroptosis signaling pathway.Methods:Thirty Sprague-Dawley rats were randomly divided into three groups:Control,DMED,and NML.After establishing the DMED model,treatments were administered for 8 weeks.After the administration,apomorphine hydrochloride tests were conducted to measure the mass and organ index of testes and epididymides,sperm concentration and viability in each group.Penile corpus cavernosum tissues were stained with hematoxylin and eosin.Nitric oxide and cyclic guanosine monophosphate levels in the penile corpus cavernosum tissues were determined using biochemical kits and enzyme-linked immunosorbent assay,while the expression of proteins related to the ferroptosis signaling pathway was measured by Western blot.Results:Compared to the DMED group,the DMED rats treated with NML showed significantly increased erection frequency,testicular and epididymal mass and index,sperm count and viability,along with noticeable improvement in the pathological morphology of penile corpus cavernosum.The content of nitric oxide and cyclic guanosine monophosphate,and the expression of ferritin heavy chain,ferritin light chain,and glutathione peroxidase 4 proteins in penile corpus cavernosum tissue were elevated,while the expression of transferrin and STEAP3 proteins was reduced.Conclusion:NML can improve erectile function in DMED rats by inhibiting the ferroptosis signaling pathway.

The role and research progress of MDSC in immune aging-related diseases

Myeloid-derived suppressor cells(MDSCs)are a group of heterogeneous immature cells with a strong immunosuppressive function in myeloid cells,which are impeded in the differentiation of myeloid cells under the pathological conditions of hypoxia,inflammation,infection,and cancer.As individuals age,there is a significant increase in myeloid-derived suppressor cells(MDSCs),which subsequently enhance the immunosuppressive functions of Tregs(regulatory T cells)and Bregs(regulatory B cells).Therefore,MDSC may be related to immune system remodeling,thereby preventing excessive lesions caused by aging.This indicates that MDSC could serve as a potent inducer of immune senescence.Immune senescence,characterized by immune dysfunction with aging,is closely linked to the onset of diseases like infections,pulmonary fibrosis,and tumors.To achieve the purpose of anti-aging by intervening in immune aging and slow down the occurrence and development of related diseases.Therefore,understanding the biological characteristics of MDSC and its role in immune aging is crucial for immunotherapy targeting MDSC.This article reviews the different roles of MDSC in immune aging and its relationship with pulmonary fibrosis,tumor and other related diseases to provide theoretical basis for more comprehensive targeted MDSC immunotherapy.

Shao Yao Decoction exerts a protective effect on ulcerative colitis by inhibiting inflammation mediated by hypercoagulability

Background:Shaoyao decoction(SYD)has been found widespread clinical use in treating ulcerative colitis(UC).However,the mechanism underlying SYD impact on UC remains elusive.Materials and methods:We preliminarily evaluated the therapeutic effect of SYD intervention in a dextran sulfate sodium-induced UC mouse model by analyzing the body weight change,disease activity index score,colon length,and HE staining results of colon tissue in each group of mice.Subsequently,we determined pro-inflammatory cytokines level and blood coagulation markers in the colon tissues of mice in each group to evaluate the effect of SYD intervention on colonic inflammatory response and coagulation function in UC mice.Results:Our findings emphasize the significant therapeutic effect of SYD on UC,including slowed down body weight loss,reduced disease activity index score,increased colon length,and reduced inflammatory infiltration in colon tissue.Moreover,SYD intervention significantly downregulated the levels of pro-inflammatory cytokines IL-1β,IL-6,and IL-17A in the colon.Furthermore,SYD intervention reversed the coagulation-related indicators such as prothrombin time,fibrinogen,P-selectin,D-dimer,and platelet glycomembrane protein IIb/IIIa.Conclusion:Our results elucidate the substantial therapeutic impact of SYD on UC mice.Importantly,the therapeutic mechanism of SYD in addressing UC potentially involves the inhibiting of inflammatory response mediated by hypercoagulability.

Investigating the mechanism of action of Bu-Yang-Huan-Wu decoction in treating bleomycin-Induced pulmonary fibrosis through the epithelial-mesenchymal transition pathway

Background:To explore the effects and mechanisms of Bu-Yang-Huan-Wu Decoction on pulmonary fibrosis in mice.Methods:Forty-five C57BL/6J mice were randomly divided into three groups:Control,Model,and Bu-Yang-Huan-Wu Decoction.Pulmonary fibrosis was elicited in mice through a solitary intratracheal administration of 2.5 mg/kg bleomycin.For the control group,mice were given a solitary intratracheal administration of a comparable volume of PBS.Treatment began on the first day after the successful model establishment and lasted for 21 days.The survival rate and body weight of the mice were recorded daily,and on the 22nd day,bronchoalveolar lavage fluid was collected to determine total cells and total protein.The wet/dry weight ratio of lung tissue and hydroxyproline were measured.Lung tissue pathology was observed using hematoxylin and eosin staining and Masson staining.The mRNA expression of epithelial-mesenchymal transition-related proteins(E-cadherin and vimentin)was detected by RT-qPCR,and their protein expression was analyzed by western blot.Results:Compared to the model group,the Bu-Yang-Huan-Wu Decoction treatment notably enhanced both the survival rate and body weight in pulmonary fibrosis mice,significantly reduced lung tissue wet/dry weight ratio,total cells,and protein in bronchoalveolar lavage fluid,and hydroxyproline content.The pathological morphology of lung tissue was significantly improved,with increased expression of the epithelial cell marker E-cadherin mRNA and protein,and decreased expression of the mesenchymal cell marker vimentin mRNA and protein.Conclusion:Bu-Yang-Huan-Wu Decoction can improve the degree of bleomycin-induced pulmonary fibrosis in mice by inhibiting epithelial-mesenchymal transition.

肠道菌群与脂肪性肝病研究新进展

目前,肠道菌群已成为一个当今研究的热点问题之一.脂肪性肝病是指由于各种原因引起的肝细胞内脂肪堆积过多的病变,引起肝的正常结构、生理及生化功能受损,最终出现临床症状的一类疾病总称,一般包括非酒精性脂肪性肝病和酒精性肝病两大类.肠道菌群和肠道通透性的变化可以通过肠-肝轴进一步影响脂肪性肝病的发展.同样,在脂肪性肝病的发生发展过程中,肠道菌群的也发生不同程度的改变.本文主要介绍肠-肝轴与脂肪性肝病的关系、脂肪性肝病进展过程中肠道菌群的变化及益生菌在脂肪性肝病治疗中的应用新进展.

鼠李糖乳杆菌治疗肠易激综合征机制新进展

肠易激综合征(irritable bowel syndrome,IBS)是临床上常见的功能性胃肠病,其会影响患者的生活质量.因此探寻IBS的有效治疗方法具有重要意义.益生菌可改善IBS患者的症状并提高其生活质量,其中备受关注的是鼠李糖乳杆菌(Lactobacillus rhamnosus GG,LGG).LGG是目前被研究最多的益生菌之一.LGG已经在临床上被用来治疗IBS,且近年来LGG治疗IBS机制不断有新的进展.LGG可通过调节肠道菌群失调、保护肠道屏障功能、抗炎、调节肠道免疫、改善内脏高敏感和抑菌来发挥作用从而改善IBS症状.本文就LGG治疗IBS的可能机制作一综述.

Prevalence of fatty liver disease and the economy in China: A systematic review

AIM: To investigate the relationship between the economy and the adult prevalence of fatty liver disease(FLD) in China's Mainland. METHODS: Literature searches on the Pub Med and Chinese National Knowledge Infrastructure databases were performed to identify eligible studies published before July 2014. Records were limited to crosssectional surveys or baseline surveys of longitudinal studies that reported the adult prevalence of FLD and recruited subjects from the general population or community. The gross domestic product(GDP) per capita was chosen to assess the economic status. Multiple linear regression and Loess regression were chosen to fit the data and calculate the 95%CIs. Fitting and overfitting of the models were considered in choosing the appropriate models. RESULTS: There were 27 population-based surveys from 26 articles included in this study. The pooled mean prevalence of FLD in China was 16.73%(95%CI: 13.92%-19.53%). The prevalence of FLD was correlated with the GDP per capita and survey years in the country(adjusted R2 = 0.8736, P GDP per capita = 0.00426, P years = 0.0000394), as well as in coastal areas(R2 = 0.9196, P GDP per capita = 0.00241, P years = 0.00281). Furthermore, males [19.28%(95%CI: 15.68%-22.88%)] presented a higher prevalence than females [14.1%(95%CI: 11.42%-16.61%), P = 0.0071], especially in coastal areas [21.82(95%CI: 17.94%-25.71%) vs 17.01%(95%CI: 14.30%-19.89%), P = 0.0157]. Finally, the prevalence was predicted to reach 20.21% in 2020, increasing at a rate of 0.594% per year. CONCLUSION: This study reveals a correlation between the economy and the prevalence of FLD in China's Mainland.

HMGB1 gene polymorphisms in patients with chronic hepatitis B virus infection

AIM: To characterize high mobility group box chromosomal protein 1(HMGB1) polymorphisms in patients infected with hepatitis B virus(HBV) and determine the different patterns in patient subgroups.METHODS: A total of 1495 unrelated Han Chinese HBV carriers were recruited in this hospital-based casecontrol study.The HMGB1 1176 G/C polymorphism was genotyped by polymerase chain reaction-restriction fragment length polymorphism assay.RESULTS: A significant association was observed between HMGB1 1176 G/C polymorphism and outcome of HBV infection.The subjects bearing 1176G/G genotype had an increased risk of susceptibility to chronic hepatitis B,liver cirrhosis and severe hepatitis B when compared with those bearing at least one 1176C allele.CONCLUSION: Patients with 1176G/G genotype of HMGB1 gene are more likely to have a progressive status in HBV infection.

Plasma exchange-centered artificial liver support system in hepatitis B virus-related acute-onchronic liver failure:a nationwide prospective multicenter study in China

BACKGROUND： Plasma exchange （PE）-centered artificial liver support system reduced the high mortality rate of hepa titis B virus （HBV）-related acute-on-chronic liver failure （ACLF）. But the data were diverse in different medical centers. The present prospective nationwide study was to evaluate the effects of PE on patients with HBV-ACLF at different stages.

Effect of Lactobacillus rhamnosus GG supernatant on serotonin transporter expression in rats with post-infectious irritable bowel syndrome

AIM To evaluate the effect of Lactobacillus rhamnosus GG supernatant(LGG-s) on the expression of serotonin transporter(SERT) in rats with post-infectious irritable bowel syndrome(PI-IBS).METHODS Campylobacter jejuni 81-176(1010 CFU/m L) was used to induce intestinal infection to develop a PI-IBS model. After evaluation of the post-infectious phase by biochemical tests, Dn A agarose gel electrophoresis, abdominal withdrawal reflex(AWR) test, and the intestinal motility test, four PI-IBS groups received different concentrations of LGG-s for 4 wk. The treatments were maintained for 1.0, 2.0, 3.0 or 4.0 wk during the experiment, and the colons and brains were removed for later use each week. SERT m Rn A and protein levels were detected by real-time PCR and Western blot, respectively.RESULTS The levels of SERT m Rn A and protein in intestinal tissue were higher in rats treated with LGG-s than in control rats and PI-IBS rats gavaged with PBS during the whole study. Undiluted LGG-s up-regulated SERT m Rn A level by 2.67 times compared with the control group by week 2, and SERT m Rn A expression kept increasing later. Double-diluted LGG-s was similar to undiluted-LGG-s, resulting in high levels of SERT m Rn A. Triple-diluted LGG-s up-regulated SERT m Rn A expression level by 6.9-times compared with the control group, but SERT m Rn A expression decreased rapidly at the end of the second week. At the first week, SERT protein levels were basically comparable in rats treated with undiluted LGG-s, double-diluted LGG-s, and triplediluted LGG-s, which were higher than those in the control group and PBS-treated PI-IBS group. SERT protein levels in the intestine were also comparable in rats treated with undiluted LGG-s, double-diluted LGG-s, and triple-diluted LGG-s by the second and third weeks. SERT m Rn A and protein levels in the brain had no statistical difference in the groups during the experiment.CONCLUSION LGG-s can up-regulate SERT m Rn A and protein levels in intestinal tissue but has no influence in brain tissue in rats with PI-IBS.

Regulation of the serotonin transporter in the pathogenesis of irritable bowel syndrome

Serotonin(5-HT) and the serotonin transporter(SERT) have earned a tremendous amount of attention regarding the pathogenesis of irritable bowel syndrome(IBS). Considering that enteric 5-HT is responsible for the secretion, motility and perception of the bowel, the involvement of altered enteric 5-HT metabolism in the pathogenesis of IBS has been elucidated. Higher 5-HT availability is commonly associated with depressed SERT mR NA in patients with IBS compared with healthy controls. The expression difference of SERT between IBS patients and healthy controls might suggest that SERT plays an essential role in IBS pathogenesis, and SERT was expected to be a novel therapeutic target for IBS. Progress in this area has begun to illuminate the complex regulatory mechanisms of SERT in the etiology of IBS. In this article, current insights regarding the regulation of SERT in IBS are provided, including aspects of SERT gene polymorphisms, microR NAs, immunity and inflammation, gut microbiota, growth factors, among others. Potential SERT-directed therapies for IBS are also described. The potential regulators of SERT are of clinical importance and are important for better understanding IBS pathophysiology and therapeutic strategies.

Detection of PERV by polymerase chain reaction and its safety in bioartificial liver support system

AIM： To establish a method detecting porcine endogenous retrovirus （PERV） in China experimental minipigs and to evaluate the safety of PERV in three individuals treated with bioartificial liver support systems based on porcine hepatocytes. METHODS： Porcine hepatocytes were isolated with two-stage perfusion method, then cultured in the bioreactor, which is separated by a semipermeable membrane （0.2μm） from the lumen through which the patients＇ blood plasma was circulated. After posthemoperfusion, patients＇ blood was obtained for screening. Additionally, samples of medium collected from both intraluminal and extraluminal compartments of the laboratory bioreactor and culture supernate in vitro was analyzed. The presence of viral sequences was estimated by polymerase chain reaction （PCR） and reverse transcriptase-polymerase chain reaction （RTPCR）. Finally, the infection of virus in the supernate of common culture was ascertained by exposure to the fetal liver cells. RESULTS： PERV-specific gag sequences were found in the porcine hepatocytes using RT-PCR. and were detected in all samples from the intraluminal, extraluminal samples and culture supernate. However, culture supernatant from primary porcine hepatocytes （cleared of cellular debris） failed to infect human fetal liver cells. Finally, RT-PCR detected no PERV infection was found in the blood samples obtained from three patients at various times post-hemoperfusion. CONCLUSION： The assays used are specific and sensitive, identified by second PCR. PERVs could be released from hepatocytes cultured in bioreactor without the stimulation of mitogen and could not be prevented by the hollow fiber semipermeable membrane, indicating the existence of PERV safety in extracorporeal bioartificial liver support system （EBLSS）.

Relationship between HLA-DR gene polymorphisms and outcomes of hepatitis B viral infections:A meta-analysis

AIM:To assess the rigorous relationship between human leukocyte antigens(HLA)-DR alleles and outcomes of hepatitis B virus(HBV) infections by means of metaanalysis.METHODS:Medline/PubMed,EMBASE,CNKI and VIP were searched to identify relevant studies.Study quality was evaluated using the Newcastle-Ottawa Scale.Odds ratios(OR) and 95% confidence interval(95% CI) were pooled using Stata 11.0.Subgroup analyses were performed by ethnicity.Heterogeneity and publication bias analyses were performed to validate the credibility.RESULTS:A total of 2609 patients with chronic hepatitis B and 2606 controls spontaneously recovering from prior HBV infection were included.Meta-analysis showed that HLA-DR*04(OR = 0.72,95% CI:0.60-0.85) and DR*13(OR = 0.27,95% CI:0.19-0.37) alleles were significantly associated with HBV clearance while patients carrying HLA-DR*03(OR = 1.47,95% CI:1.16-1.87) or DR*07(OR = 1.59,95% CI:1.24-2.03) alleles had a significantly increased risk of chronic HBV persistence.For the HLA-DR*01 polymorphism,a significantly association with HBV clearance was found in Chinese Han group(OR = 0.48,95% CI:0.26-0.86),but not found in other ethnic groups(P = 0.191).For other polymorphisms,no association with the HBV infection outcome was found.CONCLUSION:HLA-DR*04 and DR*13 alleles may be the protective factors for HBV clearance and HLADR*03,and DR*07 alleles may be the risk factors for HBV persistence.

Effects of fluid balance on prognosis of acute respiratory distress syndrome patients secondary to sepsis

BACKGROUND:Fluid management is crucial to acute respiratory distress syndrome(ARDS)secondary to sepsis.However,choices of fluid resuscitation strategies and fluid input volumes remain a thorny problem.Our study aimed to elucidate the relationship between fluid balance and prognosis of ARDS patients secondary to sepsis.METHODS:Our study included 322 sepsis patients from Ruijin Hospital between 2014 and 2018,and 84 patients were diagnosed as ARDS within 72 hours after onset of sepsis according to Berlin ARDS Defi nition.RESULTS:Among the 322 sepsis patients,84(26.1%)were complicated with ARDS within 72 hours.ARDS patients had a lower oxygenation index(PaO2/FiO2166.4±71.0 vs.255.0±91.2,P<0.05),longer duration of mechanical ventilation(11[6-24]days vs.0[0-0]days,P<0.05)than those without ARDS.Sepsis patients with ARDS showed daily positive net fl uid balance during seven days compared with those without ARDS who showed daily negative net fluid balance since the second day with signifi cant statistical differences.Among the 84 sepsis patients with ARDS,58(69.0%)died.Mean daily fl uid input volumes were much lower in survivors than in non-survivors(43.2±16.7 mL/kg vs.51.0±25.2 mL/kg,P<0.05)while output volumes were much higher in survivors(45.2±19.8 mL/kg vs.40.2±22.7 mL/kg,P<0.05).Using binary logistic regression analysis,we found that the mean daily fl uid balance was independently associated with mortality of sepsis patients complicating with ARDS(P<0.05).CONCLUSIONS:Early negative fluid balance is independently associated with a better prognosis of sepsis patients complicated with ARDS.

Genome-wide microarray-based analysis of miRNAs expression in patients with acute-onchronic liver failure

BACKGROUND: Acute-on-chronic liver failure(ACLF) is a severe clinical syndrome that may cause a high mortality. However, the mechanism is still not clear. Characterization of the microRNA(miRNA) profiles in ACLF patients may provide new clues to the pathogenesis and management of this syndrome. METHODS: Genome-wide microarray was performed to compare the different miRNA expression profiles in peripheral blood mononuclear cells of a pair of monozygotic twins, an ACLF patient and an HBV asymptomatic carrier(AsC). The case-control miRNA profiles were compared and confirmed by quantitative reverse transcription-polymerase chain reaction in 104 ACLF patients and 96 AsCs. A combined computational prediction algorithm was used to predict the potential target genes. RESULTS: Forty-five miRNAs were increased and eight miRNAs were decreased in the ACLF group. The expressions of hsa-let-7a and hsa-miR-16 were increased by 8.58- and 8.63-fold in ACLF patients compared with that in AsCs, respectively(P【0.001). CARD8, BCL2, IL1RAPL1, LTB, FZD10 and EDA were identified as the target genes of hsa-miR-16; MAP4K3, OPRM1, IGF2BP1 and CERCAM were verified as the target genes of hsa-let-7a. CONCLUSIONS: Our results showed that there is a close relationship between specific miRNAs of peripheral blood mononuclear cells and ACLF. hsa-miR-16 and hsa-let-7a may contribute to the development of ACLF.

Application of Fractal Contact Model in Dynamic Performance Analysis of Gas Face Seals

Fractal theory provides scale?independent asperity contact loads and assumes variable curvature radii in the contact analyses of rough surfaces, the current research for which mainly focuses on the mechanism study. The present study introduces the fractal theory into the dynamic research of gas face seals under face?contacting conditions. Structure?Function method is adopted to handle the surface profiles of typical carbon?graphite rings, proving the fractal con?tact model can be used in the field of gas face seals. Using a numerical model established for the dynamic analyses of a spiral groove gas face seal with a flexibly mounted stator, a comparison of dynamic performance between the Majumdar?Bhushan(MB) fractal model and the Chang?Etsion?Bogy(CEB) statistical model is performed. The result shows that the two approaches induce differences in terms of the occurrence and the level of face contact. Although the approach distinctions in film thickness and leakage rate can be tiny, the distinctions in contact mechanism and end face damage are obvious. An investigation of fractal parameters D and G shows that a proper D(nearly 1.5) and a small G are helpful in raising the proportion of elastic deformation to weaken the adhesive wear in the sealing dynamic performance. The proposed research provides a fractal approach to design gas face seals.

Nerve bundle formation during the promotion of peripheral nerve regeneration:collagenⅥ-neural cell adhesion molecule 1 interaction

The formation of nerve bundles,which is partially regulated by neural cell adhesion molecule 1(NCAM1),is important for neural network organization during peripheral nerve regeneration.However,little is known about how the extracellular matrix(ECM)microenvironment affects this process.Here,we seeded dorsal root ganglion tissue blocks on different ECM substrates of peripheral nerve ECM-derived matrixgel,Matrigel,laminin 521,collagen I,and collagen IV,and observed well-aligned axon bundles growing in the peripheral nerve ECM-derived environment.We confirmed that NCAM1 is necessary but not sufficient to trigger this phenomenon.A protein interaction assay identified collagen VI as an extracellular partner of NCAM1 in the regulation of axonal fasciculation.Collagen VI interacted with NCAM1 by directly binding to the FNIII domain,thereby increasing the stability of NCAM1 at the axolemma.Our in vivo experiments on a rat sciatic nerve defect model also demonstrated orderly nerve bundle regeneration with improved projection accuracy and functional recovery after treatment with 10 mg/m L Matrigel and 20μg/m L collagen VI.These findings suggest that the collagen VI-NCAM1 pathway plays a regulatory role in nerve bundle formation.This study was approved by the Animal Ethics Committee of Guangzhou Medical University(approval No.GY2019048)on April 30,2019.