Sclareol Protects Staphylococcus aureus-Induced Lung Cell Injury via Inhibiting Alpha-Hemolysin Expression

( Ouyang Ping ),( Sun Mao ),( He Xuewen ),( Wang Kaiyu ),( Yin Zhongqiong ),( Fu Hualin ),( Li Yinglun ),( Geng Yi ),( Shu Gang ),( He Changliang ),( Liang Xiaoxia ),( Lai Weiming ),( Li Lixia ),( Zou 한국미생물 · 생명공학회 2017 Journal of microbiology and biotechnology Vol.27 No.1

Staphylococcus aureus (S. aureus) is a common gram-positive bacterium that causes serious infections in humans and animals. With the continuous emergence of methicillin-resistant S. aureus (MRSA) strains, antibiotics have limited efficacy in treating MRSA infections. Accordingly, novel agents that act on new targets are desperately needed to combat these infections. S. aureus alpha-hemolysin plays an indispensable role in its pathogenicity. In this study, we demonstrate that sclareol, a fragrant chemical compound found in clary sage, can prominently decrease alpha-hemolysin secretion in S. aureus strain USA300 at sub-inhibitory concentrations. Hemolysis assays, western-blotting, and RT-PCR were used to detect the production of alpha-hemolysin in the culture supernatant. When USA300 was co-cultured with A549 epithelial cells, sclareol could protect the A549 cells at a final concentration of 8 μg/ml. The protective capability of sclareol against the USA300-mediated injury of A549 cells was further shown by cytotoxicity assays and live/dead analysis. In conclusion, sclareol was shown to inhibit the production of S. aureus alpha-hemolysin. Sclareol has potential for development as a new agent to treat S. aureus infections.

Mechanism analysis on fluidelastic instability of tube bundles in considering of cross-flow effects

Jiang Lai,Lei Sun,Lixia Gao,Pengzhou Li 한국원자력학회 2019 Nuclear Engineering and Technology Vol.51 No.1

Fluidelastic instability is a key issue in steam generator tube bundles subjected in cross-flow. With a lowflow velocity, a large amplitude vibration of the tube observed by many researchers. However, themechanism of this vibration is seldom analyzed. In this paper, the mechanism of cross-flow effects onfluidelastic instability of tube bundles was investigated. Analysis reveals that when the system reachesthe critical state, there would be two forms, with two critical velocities, and thus two expressions for thecritical velocities were obtained. Fluidelastic instability experiment and numerical analysis were conductedto obtain the critical velocity. And, if system damping is small, with increases of the flow velocity,the stability behavior of tube array changes. At a certain flow velocity, the stability of tube array reachesthe first critical state, a dynamic bifurcation occurs. The tube array returns to a stable state with continuesto increase the flow velocity. At another certain flow velocity, the stability of tube array reachesthe second critical state, another dynamic bifurcation occurs. However, if system damping is big, there isonly one critical state with increases the flow velocity. Compared the results of experiments to numericalanalysis, it shows a good agreement.

Contact modeling and stiffness of a rough surface under mixed lubrication condition

Ling Li,Litai Sun,Jingjing Wang,Benshuai He,Chongqing Fan,Lixia Li,Miaoxia Xie 대한기계학회 2023 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.37 No.2

A method of using a quadratic function of rotary asperities to be equivalent to asperity is established based on a measurement experiment on rough surface topography. A micro-contact model of a rough surface that includes elastic, elastic-plastic, and pure plastic deformation states is re-derived using the theory of contact mechanics and the method of probability statistics. A rough surface contact stiffness model under mixed lubrication is proposed in accordance with the rough surface contact stiffness, which consists of solid surface and lubrication medium contact stiffness. The influence of the lubrication medium, solid material, and asperity size parameters on contact stiffness is analyzed. Results show that elastic modulus, acoustic impedance, and the size parameters of the asperities of the solid part are the main factors that affect the contact stiffness of the solid part. The acoustic impedance of the lubricating medium mainly affects the contact stiffness of the lubrication part. The contact stiffness of the rough surface under mixed lubrication is a superposition of the solid and lubrication parts, and it is greater than that without the lubrication medium. The model established in this study fully considers the deformation state in practical engineering, which includes asperities and the lubrication state of rough surfaces. It provides a reference for the performance prediction of mechanical surfaces.

Glia maturation factor beta deficiency protects against diabetic osteoporosis by suppressing osteoclast hyperactivity

Shi Si,Gu Huijie,Xu Jinyuan,Sun Wan,Liu Caiyin,Zhu Tong,Wang Juan,Gao Furong,Zhang Jieping,Ou Qingjian,Jin Caixia,Xu Jingying,Chen Hao,Li Jiao,Xu Guotong,Tian Haibin,Lu Lixia 생화학분자생물학회 2023 Experimental and molecular medicine Vol.55 No.-

Excessive osteoclast activation, which depends on dramatic changes in actin dynamics, causes osteoporosis (OP). The molecular mechanism of osteoclast activation in OP related to type 1 diabetes (T1D) remains unclear. Glia maturation factor beta (GMFB) is considered a growth and differentiation factor for both glia and neurons. Here, we demonstrated that Gmfb deficiency effectively ameliorated the phenotype of T1D-OP in rats by inhibiting osteoclast hyperactivity. In vitro assays showed that GMFB participated in osteoclast activation rather than proliferation. Gmfb deficiency did not affect osteoclast sealing zone (SZ) formation but effectively decreased the SZ area by decreasing actin depolymerization. When GMFB was overexpressed in Gmfb-deficient osteoclasts, the size of the SZ area was enlarged in a dose-dependent manner. Moreover, decreased actin depolymerization led to a decrease in nuclear G-actin, which activated MKL1/SRF-dependent gene transcription. We found that pro-osteoclastogenic factors (Mmp9 and Mmp14) were downregulated, while anti-osteoclastogenic factors (Cftr and Fhl2) were upregulated in Gmfb KO osteoclasts. A GMFB inhibitor, DS-30, targeting the binding site of GMFB and Arp2/3, was obtained. Biocore analysis revealed a high affinity between DS-30 and GMFB in a dose-dependent manner. As expected, DS-30 strongly suppressed osteoclast hyperactivity in vivo and in vitro. In conclusion, our work identified a new therapeutic strategy for T1D-OP treatment. The discovery of GMFB inhibitors will contribute to translational research on T1D-OP.

Fluidelastic instability of a tube array in two-phase cross-flow considering the effect of tube material

Huantong Liu,Jiang Lai,Lei Sun,Pengzhou Li,Lixia Gao,Danping Yu 한국원자력학회 2019 Nuclear Engineering and Technology Vol.51 No.8

Fluidelastic instability of a tube array is a key factor of the security of a nuclear power plant. An unsteady model of the fluidelastic instability of a tube array subjected to two-phase flow was developed to analyze the fluidelastic instability of tube bundles in two-phase flow. Based on this model, a computational program was written to calculate the eigenvalue and the critical velocity of the fluidelastic instability. The unsteady model and the program were verified by comparing with the experimental results reported previously. The influences of void fraction and the tube's material properties on the critical velocity were investigated. Numerical results showed that, with increasing the void fraction of the two-phase flow, the tube array becomes more stable. The results indicate that the critical velocities of the tube array made of stainless are much higher than those of the other two tube arrays within void fraction ranging from 20%to 80%.

Effect of the worn status of wheel/rail profiles on wheel wear over curved tracks

Jie Kou,Jimin Zhang,Hechao Zhou,Chengping Wang,Lixia Sun 대한기계학회 2021 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.35 No.3

The worn status of wheel/rail profiles could change the wheel-rail contact and influence the wear rates of the wheel and rail. Worn wheel profiles of a Chinese intercity train and the worn rail profile of curved tracks were taken into account in this work. According to the dynamics model of the vehicle, teh wheel-rail three-dimensional steady-state rolling contact model, and the Archard wear model, a new fast calculation method of wheel wear rate was proposed. Simulation results show that obviously severe wear would distribute in the flange when the wheel and rail were worn. The side wear of rail gauge corner will seriously aggravate the wear of new wheel flange. The wear of the wheel is serious for teh worn wheel in the initial phase of service. Therefore, the re-profiling of wheels and rails should be scheduled cooperatively, and the wear of flange in the initial phase of service should addressed.

Study on Anomalous Codeposition Phenomenon of CoNi Magnetic Films

Yundan Yu,Guoying Wei,Hongliang Ge,Li Jiang,Lixia Sun 한국자기학회 2017 Journal of Magnetics Vol.22 No.2

CoNi alloy films prepared from electrolytes with various concentrations of cobalt ions were studied in the paper. Influences of different cobalt ions concentrations on electrochemistry processes, components, microstructures, surface morphologies and magnetic properties of CoNi films were investigated. It was found that CoNi film plating was a kind of anomalous codeposition process. The percentage of cobalt content in CoNi films was higher than that of in the electrolyte. Moreover, with the rise of cobalt ions concentrations, the percentage of cobalt content in the samples increased gradually. CoNi films possessed crystal structures with four stronger diffraction peaks. However, CoNi films prepared from bath with higher cobalt ions possessed hcp structures which contributed to dendrite structures resulting in the increase of coercivity.

Testicular Characteristics and the Block to Spermatogenesis in Mature Hinny

Han, Hongmei,Wang, Aihong,Liu, Liming,Zhao, Gaoping,Su, Jie,Wang, Biao,Li, Yunxia,Zhang, Jindun,Wu, Baojiang,Sun, Wei,Hu, Shuxiang,Li, Shuyu,Zhao, Lixia,Li, Xihe Asian Australasian Association of Animal Productio 2016 Animal Bioscience Vol.29 No.6

Most hinnies (female donkey${\times}$male horse) and mules (female horse${\times}$male donkey) are sterile with few reports of equine fertile hybrids. The main cause of this sterility is thought to be a meiotic block to spermatogenesis and oogenesis. This study compared the developmental features of the testes and a histological analyses of spermatogenesis in a male hinny with those of a normal, fertile stallion and Jack donkey. Hinny testes showed a thicker tunica albuginea, fewer blood vessels and more connective tissue in the testis parenchyma than those of the stallion and Jack donkey. Although the mean number of seminiferous tubules was significantly higher in stallion and hinny than Jack donkey (p<0.01), the mean proportion of seminiferous tubules was lower in the hinny (p<0.01) which resulted in a smaller diameter of seminiferous tubules. The mean number of spermatogonia and spermatocytes per unit area were significantly lower in hinny testis (p<0.01) and no spermatids or mature spermatozoa cells were found during immunofluorescent analyses. These results indicated that defects in seminiferous tubule development and structure occur in the testis of hinnies. Furthermore, most spermatogonia and spermatocytes cease development in synapsis during mid-meiosis of spermatocytes, which results in a block to spermatogenesis that prevents the formation of spermatids and matured spermatozoa during meiosis in male hinnies.