Preparation of doxorubicin modified silver nanoparticle and its anti-tumor activity in vitro / 天津医药

Objective To design and synthesize a novel type of combined anti-tumor drug-doxorubicin modified silver nanoparticles(DOX-Ag NPs)with pH response,characterize its physical and chemical properties,and investigate its drug responsive release and anti-tumor activity in vitro.Methods DOX-Ag NPs were prepared by coupling silver nanoparticles (Ag NPs) with doxorubicin (DOX) via a LA-NHNH2linker. The structure of LA-NHN=DOX was confirmed by nuclear magnetic resonance(1H NMR)and high resolution mass spectrometry(HRMS).The particle size and micromorphology of the nanoparticles were detected by dynamic light scattering (DLS) and transmission electron microscopy (TEM), respectively. The optical properties of the nanoparticles were characterized by UV-vis absorption spectroscopy and fluorescence spectroscopy.The DOX release kinetics of DOX-Ag NPs under different pH conditions were examined by dialysis method combined with fluorescence spectroscopy. The in vitro anti-tumor effects of DOX-Ag NPs were evaluated by MTT assay. Results DOX-Ag NPs were spherical nanoparticles with a particle size of (40.4 ± 3.8) nm. DOX-Ag NPs could rapidly release DOX under weak acid condition.DOX-Ag NPs significantly inhibited the proliferation and cell viability of HepG2 cells in concentration dependent manner.When DOX concentration was 0.5-20 mg/L(Ag concentration was 0.45-18 mg/L), the cell survival rate was significantly lower in DOX-Ag NPs group than that of DOX group and Ag NPs group(P<0.05). Conclusion DOX-Ag NPs are a combined anti-tumor nano-drug with pH-responsive ability, which can release DOX rapidly in tumor tissues and play an anti-tumor effect through synergistic treatment with Ag NPs in vitro.

Protective effect of autophagy inhibition on ischemia-reperfusioninduced injury of N2a cells / 华中科技大学学报（医学）（英德文版）

Autophagy is a conserved and programmed catabolic process that degrades damaged proteins and organelles. But the underlying mechanism and functions of autophagy in the ischemiareperfusion (IR)-induced injury are unknown. In this study, we employed simulated IR of N2a cells as an in vitro model of IR injury to the neurons and monitored autophagic processes. It was found that the levels of Beclin-1 (a key molecule of autophay complex, Beclin-1/class III PI3K) and LC-3II (an autophagy marker) were remarkably increased with time during the process of ischemia and the process of reperfusion after 90 min of ischemia, while the protein kinases p70S6K and mTOR which are involved in autophagy regulation showed delayed inactivation after reperfusion. Administration of 3-methyladenine (3MA), an inhibitor of class III PI3K, abolished autophagy during reperfusion, while employment of rapamycin, an inhibitor of mTORC1 (normally inducing autophagy), surprisingly weakened the induction of autophagy during reperfusion. Analyses of mitochondria function by relative cell viability demonstrated that autophagy inhibition by 3-MA attenuated the decline of mitochondria function during reperfusion. Our data demonstrated that there were two distinct dynamic patterns of autophagy during IR-induced N2a injury, Beclin-1/class III PI3K complex-dependent and mTORC1-dependent. Inhibition of over-autophagy improved cell survival. These suggest that targeting autophagy therapy will be a novel strategy to control IR-induced neuronal damage.

Virulence genes and pathogenicity of Shigella flexneri Xv isolated in Beijing / 中华流行病学杂志

<p><b>OBJECTIVE</b>To understand the biochemical characteristics, virulence genes and pathogenicity of Shigella flexneri Xv isolated in Beijing.</p><p><b>METHODS</b>61 strains of S. flexneri Xv isolated from diarrhea patients in Beijing were systematically determined through biochemical reactions and serological tests. Application of PCR technique in detection of virulence genes on ipaH, sen, virF, ial and pulsed-field gel electrophoresis (PFGE) was used to identify the related characteristics and on rat lung slices to determine its pathogenicity.</p><p><b>RESULTS</b>All of the S. flexneri Xv could ferment glucose, mannitol, melibiose and arabinose. Using serum agglutination, we found that the antigen structure was (IV: 7, 8). IpaH, sen, virF and ial that carried rates of virulence genes appeared to be 100%, 81.97%, 75.41% and 80.30%, respectively. Among 61 strains of S. flexneri Xv, the PFGE typing of Shigella bacteria could be divided into 25 belt types while the results from rat lung slices showed inflammatory change of Xv.</p><p><b>CONCLUSION</b>S. flexneri Xv was found that it carried high rate of Shigella virulence genes, exhibiting genetic polymorphism and highly invasive.</p>

Protective effect of autophagy inhibition on ischemia-reperfusion-induced injury of N2a cells / 华中科技大学学报（医学）（英德文版）

Autophagy is a conserved and programmed catabolic process that degrades damaged proteins and organelles. But the underlying mechanism and functions of autophagy in the ischemia-reperfusion (IR)-induced injury are unknown. In this study, we employed simulated IR of N2a cells as an in vitro model of IR injury to the neurons and monitored autophagic processes. It was found that the levels of Beclin-1 (a key molecule of autophay complex, Beclin-1/class III PI3K) and LC-3II (an autophagy marker) were remarkably increased with time during the process of ischemia and the process of reperfusion after 90 min of ischemia, while the protein kinases p70S6K and mTOR which are involved in autophagy regulation showed delayed inactivation after reperfusion. Administration of 3-methyladenine (3MA), an inhibitor of class III PI3K, abolished autophagy during reperfusion, while employment of rapamycin, an inhibitor of mTORC1 (normally inducing autophagy), surprisingly weakened the induction of autophagy during reperfusion. Analyses of mitochondria function by relative cell viability demonstrated that autophagy inhibition by 3-MA attenuated the decline of mitochondria function during reperfusion. Our data demonstrated that there were two distinct dynamic patterns of autophagy during IR-induced N2a injury, Beclin-1/class III PI3K complex-dependent and mTORC1-dependent. Inhibition of over-autophagy improved cell survival. These suggest that targeting autophagy therapy will be a novel strategy to control IR-induced neuronal damage.

Effect of UC-MSCs on inflammation and thrombosis of the rats with collagen type II induced arthritis / 中华血液学杂志

<p><b>OBJECTIVE</b>To investigate the immunoregulation effects of umbilical cord mesenchymal stem cells (UC-MSCs) on the rats with collagen II induced arthritis (CIA).</p><p><b>METHODS</b>The rats were first immunized by intradermal injection of chicken collagen type II emulsified with complete Freund's adjuvant (CFA) to monitor their swelling of foot, hair color and action state. After injected UC-MSC by caudal vein, the rats were scored with the arthritis index (AI) once a week. Then, the concentration of interleukin (IL-6), tumor necrosis factor-α (TNF-α) in serum and D-dimer (D-D), antithrombin-III (AT-III), thrombomodulin (TM) in plasma were detected by ELISA.</p><p><b>RESULTS</b>Obvious swellings of the feet were found in the experiment group compared with normal one. ELISA analysis showed that the concentrations of IL-6, TNF-α, D-D and TM in plasma of the experiment group as of (200.48 ± 15.04) ng/L, (450.25 ± 45.39) ng/L, (274.26 ± 67.93) ng/L and (9.18 ± 0.84) µg/L, respectively were higher than of(167.62 ± 0.97) ng/L, (371.44 ± 21.26) ng/L, (193.95 ± 8.22) ng/L and (6.30 ± 0.32) µg/L respectively in normal group (P < 0.05), but the concentration of AT-III \[(89.57 ± 6.40) ng/L\] was lower than normal group \[(112.82 ± 1.74) ng/L\] (P < 0.05). The levels of cytokines through the UC-MSCs treatment were significantly different from the model group (P < 0.05). After 9 weeks, these cytokines in the UC-MSCs group were mostly the same as the normal group.</p><p><b>CONCLUSION</b>The thrombophilia status of the CIA rats was caused by immune injury. The UC-MSCs reduced the production of inflammatory cytokines and regulated and repaired the balance of coagulation and anticoagulation system of the body to cure the immune-related thrombophilia.</p>

Progress in research on multilocus sequence typing technique / 军事医学科学院院刊

Multilocus sequence typing (MLST) is a molecular genotyping method based on nucleotide sequencing. The procedure of this method characterizes isolates of bacterial species using the DNA sequencing of multiple housekeeping genes(usually seven). For each housekeeping gene, the different sequences present within a bacterial species are assigned as distinct alleles.For each isolate, the alleles at each of the loci define the allelic profile or sequence type (ST). MLST has the advantages of being robust (based on genetic data) and electronically portable to generate data that allow rapid and global comparisons between different laboratories. In this paper, the principle, method, data analysis, application, advantages and flaws of MLST are introduced.