猪圆环病毒2型ORF2基因及片段的原核表达

目的表达猪圆环病毒2型ORF2抗原,为研制猪圆环病毒2型血清学诊断方法以及生物制品生物安全性检验,提供技术支持。方法根据猪圆环病毒2型(PCV2)LC株序列,设计合成5对引物,采用PCR方法从全序列重组质粒PCV2-LC中扩增出了ORF2基因和4个不同ORF2基因片段,分别将其克隆到原核表达载体PET-32a上,再分别将各个重组表达质粒转化到大肠杆菌BL21中,用终浓度1 mmol/LIPTG诱导。结果表达产物以包涵体的形式存在,经Western-blot检测表明,表达的重组蛋白ORF2b、ORF2c、ORF2d能够被PCV2阳性血清所识别,具有良好的抗原性。表达的重组蛋白为ELISA诊断试剂盒的研制奠定了基础。     

Science Letters： A synthetic Toll-like receptor 2 ligand decreases allergic immune responses in a mouse rhinitis model sensitized to mite allergen

It has been proposed that activation of Toll-like receptors （TLRs） plays crucial roles in the polarization of adaptive immune responses. A synthetic Toll-like receptor 2 （TLR2） ligand, Pam3CSK4, has been reported to modulate the balance of Th1/Th2 responses. We evaluated the modulation effect of Pam3CSK4 on allergic immune response in a mouse rhinitis model sensitized to house dust mite allergen （HDM）. Mice were sensitized and challenged with Dermatophagoidesfarinae allergen （Der f）, and then the allergic mice were treated by Pam3CSK4. Nasal allergic symptoms and eosinophils were scored. Der f-specific cytokine responses were examined in the splenocytes and bronchoalveolar lavage fluid （BALF）. Serum level of total IgE was also detected. After establishing a mouse allergic rhinitis model with HDM, we have showed that Pam3CSK4 treatment not only ameliorated the nasal allergic symptoms remarkably but also decreased the eosinophils and total inflammation cells in BALF significantly. Analysis of cytokine profile found that IFN-7 released from either BALF or stimulated splenocytes increased markedly in Pam3CSK4-treated mice, while IL-13 decreased significantly. Moreover, serum level of total IgE was significantly lower in Pam3CSK4-treated mice than in the untreated. Thus, in an allergic rhinitis mouse model developed with HDM, Pam3CSK4 was shown to exhibit an antiallergic effect, indicating its potential application in allergic diseases.     

Differential generation of hydrogen peroxide upon exposure to zinc and cadmium in the hyperaccumulating plant specie （Sedum alfredii Hance）

Sedum alfredii Hance has been identified as zinc （Zn） and cadmium （Cd） co-hyperaccumulator. In this paper the relationships of Zn or Cd hyperaccumulation to the generation and the role of H2O2 in Sedum alfredii H. were examined. The results show that Zn and Cd contents in the shoots of Sedum alfredii H. treated with 1000 μmol/L Zn^2＋ and/or 200 μmol/L Cd^2＋ increased linearly within 15 d. Contents of total S, glutathione （GSH） and H2O2 in shoots also increased within 15 d, and then decreased. Total S and GSH contents in shoots were higher under Cd^2＋ treatment than under Zn^2＋ treatment. However, reverse trends of H2O2 content in shoots were obtained, in which much higher H2O2 content was observed in Zn^2＋ -treated shoots than in Cd^2＋-treated shoots. Similarly, the microscopic imaging of H2O2 accumulation in leaves using H2O2 probe technique showed that much higher H2O2 accumulation was observed in the Zn^2＋-treated leaf than in the Cd^2＋ -treated one. These results suggest that there are different responses in the generation of H2O2 upon exposure to Zn^2＋ and Cd^2＋ for the hyperaccumulator Sedum alfredii H. And this is the first report that the generation of H2O2 may play an important role in Zn hyperaccumulation in the leaves. Our results also imply that GSH may play an important role in the detoxification of dissociated Zn/Cd and the generation of H2O2.     

New insights into the activation mechanism of store-operated calcium channels： roles of STIM and Orai

The activation of Ca^2＋ entry through store-operated channels by agonists that deplete Ca^2＋ from the endoplasmic reticulum （ER） is a ubiquitous signaling mechanism, the molecular basis of which has remained elusive for the past two decades. Store-operated Ca^2＋-release-activated Ca^2＋ （CRAC） channels constitute the sole pathway for Ca^2＋ entry following antigen-receptor engagement. In a set of breakthrough studies over the past two years, stromal interaction molecule 1 （STIM 1, the ER Ca^2＋ sensor） and Orai 1 （a pore-forming subunit of the CRAC channel） have been identified. Here we review these recent studies and the insights they provide into the mechanism of store-operated Ca^2＋ channels （SOCCs）.     

Design and implementation of ethernet passive electronic network over coax

To increase the limit of ethernet over coax （EoC） technology in the bidirectional reform of the hybrid fiber coaxial （HFC） network, an ethernet passive electronic network （EPEN） system based on Coax is proposed and experimentally demonstrated in this paper. The proposed EPEN exploits the existing capabilities of the MAC layer in the ethernet passive optical network （EPON） for reduction of cost of the HFC network. As the MPCP （multi-point control protocol） is introduced in the EPEN, bandwidth control and higher efficiency can be achieved. The experimental results exhibit the throughput of system up to 100Mbps, which meet the requirements of HFC network. To improve the performance of EPEN, frequency division multiplexing （FDM） can be used for further increase of the throughput and more hardware processing modules in the future. can be implemented to enhance the capacity     

Metabonomic analysis of hepatitis B virus-induced liver failure： identification of potential diagnostic biomarkers by fuzzy support vector machine

Hepatitis B virus （HBV）-induced liver failure is an emergent liver disease leading to high mortality. The severity of liver failure may be reflected by the profile of some metabolites. This study assessed the potential of using metabolites as biomarkers for liver failure by identifying metabolites with good discriminative performance for its phenotype. The serum samples from 24 HBV-indueed liver failure patients and 23 healthy volunteers were collected and analyzed by gas chromatography-mass spectrometry （GC-MS） to generate metabolite profiles. The 24 patients were further grouped into two classes according to the severity of liver failure. Twenty-five eommensal peaks in all metabolite profiles were extracted, and the relative area values of these peaks were used as features for each sample. Three algorithms, F-test, k-nearest neighbor （KNN） and fuzzy support vector machine （FSVM） combined with exhaustive search （ES）, were employed to identify a subset of metabolites （biomarkers） that best predict liver failure. Based on the achieved experimental dataset, 93.62% predictive accuracy by 6 features was selected with FSVM-ES and three key metabolites, glyeerie acid, cis-aeonitie acid and citric acid, are identified as potential diagnostic biomarkers.     

Degradation of 2,4-dichlorophenol catalyzed by the immobilized laccase with the carrier of FeaO4@MSS-NH2

With the Fe304@MSS （magnetic mesoporous silica spheres）-NH2 as the carrier and the glutaraldehyde as crosslinking agent, the immobilized laccase has been pre- pared and characterized by XRD, IR, SEM and BET etc. Under the optimal conditions, the removal efficiency of 2,4-DCP reached 88 % and the removal efficiency still remained 61.5 % after five cycles of operations. In virtue of GC-MS analysis, 2,5-dimethoxyl-l,4-quinone, 2-chlo- rine-l,4-dimethoxyl benzene, 3,3＇-dichlorine-4,4＇-dimeth- oxyl biphenyl, maleic acid phenol ester, and three kinds of maleic acid, alcohol ester, and para-hydroxyl phenol ester compounds have been identified as intermediate and final degradation products of 2,4-DCP, respectively. Besides, the degradation products of 2,4-DCP have been confirmed by performing the 1H-NMR and 13C-NMR experiments, further demonstrating the degradation mechanism of 2,4- DCP by the immobilized laccase.     

Accumulation and distribution of arsenic and cadmium by tea plants

It is important to research the rules about accumulation and distribution of arsenic and cadmium by tea plants, which will give us some scientific ideas about how to control the contents of arsenic and cadmium in tea. In this study, by field investigation and pot trial, we found that mobility of arsenic and cadmium in tea plants was low. Most arsenic and cadmium absorbed were fixed in feeding roots and only small amount was transported to the above-ground parts. Distribution of arsenic and cadmium, based on their concentrations of unit dry matter, in tea plants grown on un-contaminated soil was in the order： feeding roots〉stems=main roots〉old leaves〉young leaves. When tea plants were grown on polluted soils simulated by adding salts of these two metals, feeding roots possibly acted as a buffer and defense, and arsenic and cadmium were transported less to the aboveground parts. The concentration of cadmium in soil significantly and negatively correlated with chlorophyll content, photosynthetic rate, transpiration rate and biomass production of tea plants.     

Spatial distribution of Cd and Cu in soils in Shenyang Zhangshi Irrigation Area （SZIA）, China

Heavy metal contamination of soils, derived from sewage irrigation, mining and inappropriate utilization of various agrochemicals and pesticides, and so on, has been of wide concern in the last several decades. The Shenyang Zhangshi Irrigation Area （SZIA） in China is a representative area of heavy metal contamination of soils resulting from sewage irrigation for about 30 years. This study investigated the spatial distribution and temporal variation of soil cadmium （Cd） and copper （Cu） contamination in the SZIA. The soil samples were collected from the SZIA in 1990 and 2004; Cd and Cu in soils was analyzed and then the spatial distribution and temporal variation of Cd and Cu in soils were modeled using Kriging methods. The results show that long-term sewage irrigation had caused serious Cd and Cu contamination in soils. The mean and the maximum of soil Cd are markedly higher than the levels in second grade standard soil （LSGSS） in China, and the maximum of soil Cu is close to the LSGSS in China in 2004 and is more than the LSGSS in China in 1990. The contamination magnitude of soil Cd and the soil extent of Cd con- tamination had evidently increased since sewage irrigation ceased in 1992. The contamination magnitude of soil Cu and the soil extent of Cu contamination had evidently increased in topsoil, but obviously decresed in subsoil. The soil contamination of Cd and Cu was mainly related to Cd and Cu reactivation of contaminated sediments in Shenyang Xi River and the import of Cd and Cu during irrigation. The eluviation of Cd and Cu in contaminated topsoil with rainfall and irrigation water was another factor of temporal-spatial variability of Cd and Cu contamination in soils.     

Sensing Escherichia coli O157：H7 via frequency shift through a self-assembled monolayer based QCM immunosensor

By means of the specific immuno-recognition and ultra-sensitive mass detection, a quartz crystal microbalance （QCM） biosensor for Escherichia coli O157：H7 detection was developed in this work. As a suitable surfactant, 16-mercaptohexadecanoic acid （MHDA） was introduced onto the Au surface of QCM, and then self-assembled with N-hydroxysuccinimide （NHS） raster as a reactive intermediate to provide an active interface for the specific antibody immobilization. The binding of target bacteria with the immobilized antibodies decreased the sensor＇s resonant frequency, and the frequency shift was correlated to the bacterial concentration. The stepwise assembly of the immunosensor was characterized by means of the electrochemical techniques. Using the immersion-dry-immersion procedure, this QCM biosensor could detect 2.0×10^2 colony forming units （CFU）/ml E. coli O157：H7. In order to reduce the fabrication time, a polyelectrolyte layer-by-layer self-assembly （LBL-SA） method was adopted for fast construction. Finally, the reproducibility of this biosensor was discussed.     

Comparison of an SMS text messaging and phone reminder to improve attendance at a health promotion center： A randomized controlled trial

Objective： To compare the efficacy of a short messaging service （SMS） text messaging and phone reminder to improve attendance rates at a health promotion center. Methods： A total of 1 859 participants who had scheduled appointments in the health promotion center of our hospital from April 2007 to May 2007 were enrolled in the study and randomly assigned into 3 groups： control （no reminder） group, SMS text messaging reminder group and telephone reminder group. Attendance rates and costs of interventions were collected. Results： A total of 1848 participants were eligible for analysis. Attendance rates of control, SMS and telephone groups were 80.5%, 87.5% and 88.3%, respectively. The attendance rates were significantly higher in SMS and telephone groups than that in the control group, with odds ratio 1.698, 95% confidence interval 1.224 to 2.316, P=0.001 in the SMS group, and odds ratio 1.829, 95% confidence interval 1.333 to 2.509, P〈0.001 in the telephone group. However, there was no difference between the SMS group and the telephone group （P=0.670）. The cost effectiveness analysis showed that the cost per attendance for the SMS group （0.31 Yuan） was significantly lower than that for the telephone group （0.48 Yuan）. Conclusion： SMS and telephone are effective reminders for improving attendance rate at a health promotion center. SMS reminder may be more cost-effective compared with the telephone reminder.     

Effect of serum concentration on adhesion of monocytic THP-1 cells onto cultured EC monolayer and EC-SMC co-culture

Background： The adhesion of monocytes to the endothelium following accumulation of low-density lipoprotein （LDL） in subendothelial spaces is an important step in the development of intimal hyperplasia in arterially implanted vein grafts and atherosclerosis in both animals and humans. However, it is not well known how serum factors affect the adhesion of monocytes. Methods： We have studied the effect of fetal calf serum （FCS）, which we considered a source of LDL, on the adhesion of monocytes to endothelial cells （ECs） by using human monocytic THP-1 cells and both a monolayer of cultured bovine aortic endothelial cells （EC monoculture） and a co-culture with bovine aortic smooth muscle cells （EC-SMC co-culture）. Results： It was found that the addition of FCS to the medium greatly affected the adhesion of THP-1 cells, and the higher the concentration of FCS in the medium, the greater the adhesion of THP-1 cells to endothelial cells. Adhesion of THP- 1 cells to an EC-SMC co-culture was approximately twofold greater than that to an EC monoculture, and after adhering to endothelial cells, many THP-1 cells transmigrated into the layer of smooth muscle cells. Conclusion： The results suggest that the elevation of the LDL （cholesterol） level in blood provides a favorable condition for the development of intimal hyperplasia and atherosclerosis by promoting the adhesion of monocytes to the endothelium and their subsequent migration into subendothelial spaces.     

A novel thioredoxin reductase inhibitor inhibits cell growth and induces apoptosis in HL-60 and K562 cells

Human thioredoxin reductase （TrxR） system is associated with cancer cell growth and anti-apoptosis process. Effects of 1,2-[bis（1,2-benzisoselenazolone-3（2H）-ketone）]ethane （BBSKE）, a novel TrxR inhibitor, were investigated on human leukemia cell lines HL-60 and K562. BBSKE treatment induced cell growth inhibition and apoptosis in both cell lines. Apoptosis induced by BBSKE is through Bcl-2/Bax and caspase-3 pathways. Ehrlich＇s ascites carcinoma-bearing mice were used to investigate the anti-tumor effect of BBSKE in vivo. Tumor-bearing mice treated with BBSKE showed an increase of life span with a comparable effect to cyclophosphamide （CTX）. These results suggest a potential usage of BBSKE as a therapeutic agent against non-solid tumors.     

Relationship between alanine aminotransferase levels and metabolic syndrome in nonalcoholic fatty liver disease

Objective： To investigate the relationship between alanine aminotransferase （ALT） levels and metabolic syndrome （MS） in nonalcoholic fatty liver disease （NAFLD）. Methods： A total of 26527 subjects who received medical health checkup in our hospital from January 2005 to July 2007 were enrolled in the study. The diagnosis of fatty liver was based on ultrasound imaging. MS was defined according to the criteria of the Adult Treatment Panel III. ALT, triglyceride （TG）, high density lipoprotein cholesterol （HDL-c）, fasting plasma glucose （FPG）, height, weight, waist circumference （WC）, systolic blood pressure （SBP） and diastolic blood pressure （DBP） were measured in each subject to analyze the relationship between MS and ALT activity Results： （1） The prevalence of NAFLD in men （30.94%） was significantly higher than that in women （15.65%）; （2） The incidence of MS in NAFLD （33.83%） was significantly greater than that in non-NAFLD （10.62%）; （3） Of the 6470 subjects with NAFLD, in the age-adjusted partial correlation analysis, there were statistically significant correlations between the ALT levels and most metabolic risk factors in each sex （P〈0.01）, except that ALT levels multiple stepwise regression analysis, SBP lost its significance, and had no correlation with HDL-c in women. Moreover, in the WC, body mass index （BMI）, age, DBP, TG and FPG were independently associated with ALT levels in both sexes （P〈0.05）. HDL-c remained significant and was independently related to ALT levels in men; （4） ALT levels were significantly higher in subjects with MS compared to those without MS （P〈0.001）. Mean ALT levels increased with the number of MS components in each sex （P〈0.05 for trend）. Conclusion： We found a strong relationship between ALT levels and MS in NAFLD and revealed that the cluster of MS components might be the predictor for ALT elevations.     

Optimal time for mesenchymal stem cell transplantation in rats with myocardial infarction

Background： Bone marrow mesenchymal stem cell （MSC） transplantation is a promising strategy in the treatment of myocardial infarction （MI）. However, the time for transplanting cells remains controversial. The aim of this study was to find an optimal time point for cell transplantation. Methods： MSCs were isolated and cultured from Sprague-Dawley （SD） rats. MI model was set up in SD rats by permanent ligation of left anterior descending coronary artery. MSCs were directly injected into the infarct border zone at 1 h, 1 week and 2 weeks after MI, respectively. Sham-operated and MI control groups received equal volume of phosphate buffered saline （PBS）. At 4 weeks after MI, cardiac function was assessed by echocardiography; vessel density was analyzed on hematoxylin-eosin stained slides by light microscopy; the apoptosis of cardiomyocytes was evaluated by terminal deoxynucleotidyl transferase-mediated dUTP nick end-labeling （TUNEL） assay; the expressions of proteins were analyzed by Western blot. Results： MSC transplantation improved cardiac function, reduced the apoptosis of cardiomyocytes and increased vessel density. These benefits were more obvious in 1-week group than in 1-h and 2-week groups. There are more obvious increases in the ratio of bcl-2/bax and the expression of vascular endothelial growth factor （VEGF） and more obvious decreases in the expression of cleaved-caspase-3 in 1-week group than those in other two groups. Conclusion： MSC transplantation was beneficial for the recovery of cardiac function. MSC transplantation at 1 week post-MI exerted the best effects on increases of cardiac function, anti-apoptosis and angiogenesis.