PREVALENCE OF AVIAN CHLAMYDOPHILA PSITTACI IN CHINA

Abstract Examinations were carried out in 46 intensive farms in northern China to investigate avian Chlamydophila psittaci. Five hundred and twenty-five avian sera were selected for examining antibodies to C. psittaci by ELISA. One hundred and fifty-five clinical samples from throat swabs and oviduct tissues were tested for the presence of chlamydial antigen using IDEIA TM PCE chlamydia dual amplification immunoassay, and 60 samples were tested by ompA gene-based PCR. C. psittaci antibodies were detected in 387 (77.8%) out of 525 serum samples, with seroprevalences ranging from 50% to 100%. Among the tested samples, 98/150 (65.3%) in broilers, 173/210 (82.3%) in ducks, and 116/165 (70.3%) in laying hens were detected to be positive, respectively. Using PCE-ELISA test kits, in 91 out of 155 clinical samples the presence of antigen was confirmed, while 64 samples were negative. Forty-three PCR's were tested as positive out of 60 samples, while 17 samples were confirmed to be negative. Both higher positive antibodies and the presence of antigens were found in avian flocks associated with typical clinical signs suggestive of chlamydiosis. This study showed a severe prevalence of C. psittaci among different species of domestic birds in China

Kondo behavior and metamagnetic phase transition in a heavy fermion compound CeBi2

Heavy fermions represent an archetypal example of strongly correlated electron systems which, due to entanglement among different interactions, often exhibit exotic and fascinating physics involving Kondo screening, magnetism and unconventional superconductivity. Here we report a comprehensive study on the transport and thermodynamic properties of a cerium-based heavy fermion compound CeBi$_2$ which undergoes an anti-ferromagnetic transition at $T_N$ $\sim$ 3.3 K. Its high temperature paramagnetic state is characterized by an enhanced heat capacity with Sommerfeld coefficient $\gamma$ over 200 mJ/molK$^2$. The magnetization in the magnetically ordered state features a metamagnetic transition. Remarkably, a large negative magnetoresistance associated with the magnetism was observed in a wide temperature and field-angle range. Collectively, CeBi$_2$ may serve as an intriguing system to study the interplay between $f$ electrons and the itinerant Fermi sea.Comment: 7 pages, 6 figure

Momentum--dependent nuclear mean fields and collective flow in heavy ion collisions

We use the Boltzmann-Uehling-Uhlenbeck model to simulate the dynamical evolution of heavy ion collisions and to compare the effects of two parametrizations of the momentum--dependent nuclear mean field that have identical properties in cold nuclear matter. We compare with recent data on nuclear flow, as characterized by transverse momentum distributions and flow ($F$) variables for symmetric and asymmetric systems. We find that the precise functional dependence of the nuclear mean field on the particle momentum is important. With our approach, we also confirm that the difference between symmetric and asymmetric systems can be used to pin down the density and momentum dependence of the nuclear self consistent one--body potential, independently. All the data can be reproduced very well with a momentum--dependent interaction with compressibility K = 210 MeV.Comment: 15 pages in ReVTeX 3.0; 12 postscript figures uuencoded; McGill/94-1

Epidemiology of anti-tuberculosis drug resistance in a chinese population: current situation and challenges ahead

<p>Abstract</p> <p>Background</p> <p>Drug resistance has been a cause of concern for tuberculosis (TB) control in both developed and developing countries. Careful monitoring of the patterns and trends of drug resistance should remain a priority.</p> <p>Methods</p> <p>Strains were collected from 1824 diagnosed sputum smear positive pulmonary TB patients in Jiangsu province of China and then tested for drug susceptibility against rifampicin, isoniazid, ethambutol and streptomycin. The prevalence and patterns of drug resistance in mycobacterium tuberculosis (MTB) isolates were investigated. Multiple logistic regression analysis was performed to identify the risk factors for multidrug resistant (MDR) bacterial infection. The strength of association was estimated by odds ratio (OR) and 95% confidence interval (95% CI).</p> <p>Results</p> <p>The drug susceptibility tests showed that 1077(59.05%) MTB strains were sensitive to all the four antibiotics and the other 747(40.95%) strains were resistant to at least one drug. The proportions of mono-drug resistance were 28.73% for isoniazid, 19.41% for rifampicin, 29.33% for streptomycin, and 13.98% for ethambutol, respectively. The prevalence of MDR-TB was 16.61%, which was significantly different between new cases (7.63%) and those with previous treatment history (33.07%). Geographical variation of drug resistance was observed, where the proportion of MDR-TB among new cases was higher in the central (9.50%) or north part (9.57%) than that in the south area (4.91%) of Jiangsu province. The age of patients was significantly associated with the risk of drug resistance (P < 0.001) and the adjusted OR (95% CI) was 1.88(1.26-2.81) for patients aged 35-44 years when compared with those 65 years or older. Patients with previous treatment history had a more than 5-fold increased risk of MDR-TB (adjusted OR: 6.14, 95% CI: 4.61-8.17), compared with those previously not having been treated.</p> <p>Conclusions</p> <p>The high prevalence of drug resistance has been a major challenge for TB control. Prevention and control of drug-resistant TB should be emphasized by the revised DOTS (direct observed therapy, short course) program through prompt case detection, routine and quality-assured drug susceptibility test for patients at high risk of resistance, programmatic treatment with both first and second-line medicines, and systematic treatment observation, with priority for high MDR-TB settings.</p

Diet folate, DNA methylation and genetic polymorphisms of MTHFR C677T in association with the prognosis of esophageal squamous cell carcinoma

<p>Abstract</p> <p>Background</p> <p>Folic acid may affect the development of human cancers. However, few studies have evaluated the consumption of diet folate in the prognosis of patients with esophageal squamous cell carcinoma (ESCC).</p> <p>Methods</p> <p>One hundred and twenty five ESCC patients underwent esophagectomy between January 2005 and March 2006 in the Yangzhong People's Hospital were recruited and followed up. The effects of diet folate, aberrant DNA methylation of selected genes and methylenetetrahydrofolate reductase (<it>MTHFR</it>) C677T genetic polymorphisms on the prognosis of ESCC were evaluated by using Cox proportional hazard regression models.</p> <p>Results</p> <p>Our analysis showed an inverse association between diet folate intake and the risk of death after esophagectomy. The median survival time was 3.06 years for low or moderate folate consumption and over 4.59 years for high folate consumption. After adjusting for potential confounders, the hazard ratios (95% confidence interval) [HRs (95% CI)] were 0.72 (0.36-1.46) for moderate and 0.39 (0.20-0.78) for high folate intake, respectively (<it>P </it>for trend = 0.007). This preventive effect was more evident in patients carrying <it>MTHFR </it>677CC genotype. No significant relation was observed between aberrant DNA methylation of <it>P16</it>, <it>MGMT </it>and <it>hMLH1 </it>gene, as well as <it>MTHFR </it>C677T genetic polymorphisms and the prognosis of ESCC.</p> <p>Conclusions</p> <p>Our research indicated that diet folate intake may have benefits on the prognosis of ESCC after esophagectomy. From a practical viewpoint, the findings of our study help to establish practical intervention and surveillance strategies for managements of ESCC patients and can finally decrease the disease burden.</p

Broad-Spectrum Antiviral Activity of RNA Interference against Four Genotypes of Japanese Encephalitis Virus Based on Single MicroRNA Polycistrons

Japanese encephalitis virus (JEV), a neurotropic mosquito-borne flavivirus, causes acute viral encephalitis and neurologic disease with a high fatality rate in humans and a range of animals. Small interfering RNA (siRNA) is a powerful antiviral agent able to inhibit JEV replication. However, the high rate of genetic variability between JEV strains (of four confirmed genotypes, genotypes I, II, III and IV) hampers the broad-spectrum application of siRNAs, and mutations within the targeted sequences could facilitate JEV escape from RNA interference (RNAi)-mediated antiviral therapy. To improve the broad-spectrum application of siRNAs and prevent the generation of escape mutants, multiple siRNAs targeting conserved viral sequences need to be combined. In this study, using a siRNA expression vector based on the miR-155 backbone and promoted by RNA polymerase II, we initially identified nine siRNAs targeting highly conserved regions of seven JEV genes among strains of the four genotypes of JEV to effectively block the replication of the JEV vaccine strain SA14-14-2. Then, we constructed single microRNA-like polycistrons to simultaneously express these effective siRNAs under a single RNA polymerase II promoter. Finally, these single siRNAs or multiple siRNAs from the microRNA-like polycistrons showed effective anti-virus activity in genotype I and genotype III JEV wild type strains, which are the predominant genotypes of JEV in mainland China. The anti-JEV effect of these microRNA-like polycistrons was also predicted in other genotypes of JEV (genotypes II and IV), The inhibitory efficacy indicated that siRNAs×9 could theoretically inhibit the replication of JEV genotypes II and IV

Intra- and Inter-Subunit Disulfide Bond Formation Is Nonessential in Adeno-Associated Viral Capsids

The capsid proteins of adeno-associated viruses (AAV) have five conserved cysteine residues. Structural analysis of AAV serotype 2 reveals that Cys289 and Cys361 are located adjacent to each other within each monomer, while Cys230 and Cys394 are located on opposite edges of each subunit and juxtaposed at the pentamer interface. The Cys482 residue is located at the base of a surface loop within the trimer region. Although plausible based on molecular dynamics simulations, intra- or inter-subunit disulfides have not been observed in structural studies. In the current study, we generated a panel of Cys-to-Ser mutants to interrogate the potential for disulfide bond formation in AAV capsids. The C289S, C361S and C482S mutants were similar to wild type AAV with regard to titer and transduction efficiency. However, AAV capsid protein subunits with C230S or C394S mutations were prone to proteasomal degradation within the host cells. Proteasomal inhibition partially blocked degradation of mutant capsid proteins, but failed to rescue infectious virions. While these results suggest that the Cys230/394 pair is critical, a C394V mutant was found viable, but not the corresponding C230V mutant. Although the exact nature of the structural contribution(s) of Cys230 and Cys394 residues to AAV capsid formation remains to be determined, these results support the notion that disulfide bond formation within the Cys289/361 or Cys230/394 pair appears to be nonessential. These studies represent an important step towards understanding the role of inter-subunit interactions that drive AAV capsid assembly

Kaposi's Sarcoma Herpesvirus Upregulates Aurora A Expression to Promote p53 Phosphorylation and Ubiquitylation

Aberrant expression of Aurora A kinase has been frequently implicated in many cancers and contributes to chromosome instability and phosphorylation-mediated ubiquitylation and degradation of p53 for tumorigenesis. Previous studies showed that p53 is degraded by Kaposi's sarcoma herpesvirus (KSHV) encoded latency-associated nuclear antigen (LANA) through its SOCS-box (suppressor of cytokine signaling, LANASOCS) motif-mediated recruitment of the EC5S ubiquitin complex. Here we demonstrate that Aurora A transcriptional expression is upregulated by LANA and markedly elevated in both Kaposi's sarcoma tissue and human primary cells infected with KSHV. Moreover, reintroduction of Aurora A dramatically enhances the binding affinity of p53 with LANA and LANASOCS-mediated ubiquitylation of p53 which requires phosphorylation on Ser215 and Ser315. Small hairpin RNA or a dominant negative mutant of Aurora A kinase efficiently disrupts LANA-induced p53 ubiquitylation and degradation, and leads to induction of p53 transcriptional and apoptotic activities. These studies provide new insights into the mechanisms by which LANA can upregulate expression of a cellular oncogene and simultaneously destabilize the activities of the p53 tumor suppressor in KSHV-associated human cancers