Background: Gene expression data often contain missing expression values. Therefore, several imputation methods have been applied to solve the missing values, which include k-nearest neighbour (kNN), local least squares (LLS), and Bayesian principal component analysis (BPCA). However, the effects of these imputation methods on the modelling of gene regulatory networks from gene expression data have rarely been investigated and analysed using a dynamic Bayesian network (DBN). Methods: In the present study, we separately imputed datasets of the Escherichia coli S.O.S. DNA repair pathway and the Saccharomyces cerevisiae cell cycle pathway with kNN, LLS, and BPCA, and subsequently used these to generate gene regulatory networks (GRNs) using a discrete DBN. We made comparisons on the basis of previous studies in order to select the gene network with the least error. Results: We found that BPCA and LLS performed better on larger networks (based on the S. cerevisiae dataset), whereas kNN performed better on smaller networks (based on the E. coli dataset). Conclusion: The results suggest that the performance of each imputation method is dependent on the size of the dataset, and this subsequently affects the modelling of the resultant GRNs using a DBN. In addition, on the basis of these results, a DBN has the capacity to discover potential edges, as well as display interactions, between genes.

OBJECTIVETo examine vibrio cholera (V.C) in aquatic products of littoral area, Zhejiang Province and to provide scientific evidence for administration of aquatic products and cholera epidemic control.

METHODSAll 990 samples of aquatic products collected from local markets, eateries and aquafarms in three chosen areas. Samples were proliferated in alkaline liquid medium, and purified in NO: 4 medium, the isolations were identified biochemically, and phenotype of strains were defined by phagocyte and coagulation with V.C. diagnostic serum. Three virulence genes (ctx, ace, zct) of the isolated strains were detected by polymerase chain reaction (PCR).

RESULTSThere were 1.41% samples caught by V.C., having a carrying rate highest in turtles of 8.9%. 14 strains were defined as three serogroups, and the numbers of Inaba, Ogawa, and Hikojima types were 2, 2, 10 respectively. Virulence genes had detected in 9 of 12 stains. All genes were detected in 5 strains, only ZOT genes in 3 strains, and both CTX and ACE genes in 1 strain.

CONCLUSIONSAquatic products from inshore in Zhejiang Province caught with V.C. strains might be divided into three serogroups. Most of them should be virulence genes. Cholera epidemic outbreak might be caused by those contaminated products.

China ; Food Microbiology ; Genes, Bacterial ; Seafood ; microbiology ; Vibrio cholerae ; genetics ; isolation & purification ; Virulence Factors ; genetics

OBJECTIVETo investigate the lymph node metastasis and its risk factors in T1-2 staging invasive rectal carcinoma.

METHODSThe data of 1116 patients with rectal cancer treated with total mesorectal excision (TME) technique from January 2000 to April 2009 was analyzed retrospectively. The clinicopathological factors analyzed included gender, age, primary symptom type, number of symptoms, duration of symptom, synchronous polyps, preoperative serum carcino-embryonic antigen level, preoperative serum CA19-9 level, the distance of tumor from the anal verge, tumor size, tumor morphological type, tumor circumferential extent, tumor differentiation and tumor T staging. Statistical analysis was performed by using Logistic regression analysis and Chi-square test.

RESULTSA total of 1116 patients were enrolled, and 358 cases (32.1%) were classified as with T1-2 staging tumor. Two cases (5.6%, 2/36) in patients with a T1 staging tumor were found with lymph node metastasis, and 75 cases (23.3%, 75/322) in patients with a T2 staging tumor, respectively. Compared with patients with T3-4 staging tumor, lymph node metastasis rate of the patients with T1-2 staging tumor was significantly lower [21.5% (77/358) vs. 51.6% (391/758), P < 0.05]. Only the tumor T staging was found as the independent risk factor for the lymph node metastasis in patients with T1-2 staging tumor on multivariate Logistic regression analysis (odds ratio: 5.162; 95%CI: 1.212 to 21.991; P = 0.026).

CONCLUSIONSA substantial proportion of T1-2 staging rectal cancers harbor metastatic lymph nodes and the clinicopathological features except for T staging fail to predict the lymph node metastasis. Further research is warranted to identify the risk factors and guide the clinical practice in patient with T1-2 staging tumor.

Female ; Humans ; Lymph Nodes ; pathology ; Lymphatic Metastasis ; pathology ; Male ; Middle Aged ; Neoplasm Staging ; Rectal Neoplasms ; pathology ; Retrospective Studies ; Risk Factors