AIM To establish the expermental model in vitro for the study of mechanism of antitumor drug resistance and the screening of antitumor drug. METHODS By continuously exposing cells to gradually increasing concentration of drug and agar cell colony forming technique, using dye exclusive method for determing cytotoxic effect, a murine leukemia L1210 cell subline were established,which exhibited 40 fold resistance to Cis diamminedichloro platinum(DDP). RESULTS The doubling times, plate efficiency, cell cycle, DNA index and cell morphology of DDP resistant L1210 subline were similarto those of its parant cell line. When the cell subline was stored with DDP at -196℃ for 6 months and then was recovered, its characterization of antitumor drug resistance was still maintained to a period of 5 months without DDP. DDP resistant L1210 subline was characterized with cross resistance to Carboplatin, Mitomycin, Thio Tepa, Methotrexate, Vincristin and Mustine Hydrochloride, but with no cross resistance to Harringtonine and Adriamycin. It was seemed more sensitive to Cytarabine and Fluorouracil. CONCLUSION DDP resistant L1210 subline is a good experimental model in vitro for the study of mechanism of antitumor drug resistance and the screening of antitumor drug.

Objective To explore the clinical effects of pedicled omentum in preventing anastomotic leakage after resection of colorcctal cancer complicated with intestinal obstruction.Methods The clinicopathologic data and anastomotic leakage rate of 102 patients with colorectal cancer undergoing resection from Dec.2012 to Dec.2015 were analyzed.Results Seven patients in the control group developed anastomotic leakage.Only 1 patient in the experimental group developed anastomotic leakage.The incidence of anastomotic leakage in the control group was 12％,while that in the experimental group was 2％ (x2 =4.250,P =0.039).Of the 7 patients complicating anastomotic leakage in control group,1 died of multiple organ failure,1 was cured with conservative treatment,and 5 were done with diverting stoma.The one leakage in experimental group was cured by conservative treatment.Conclusion Pedicled omentum is useful in the prevention of anastomotic leakage after resection of colorectal cancer in settings of intestinal obstruction.

Abstract: Objective　To investigate the antimicrobial activity of omadacycline (OMC) against clinical Streptococcus agalactiae (GBS) isolates, as well as its relationship with biofilm formation, resistance genes and virulence genes. Methods　A total of 136 strains of Streptococcus agalactiae isolated from Shenzhen Nanshan People's Hospital between 2015 to 2020. The minimum inhibitory concentration (MIC) of OMC against Streptococcus agalactiae was determined by broth microdilution. Crystal violet staining was used to detect the biofilm formation ability of GBS. Resistance genes (tetM, tetO, tetK, ermB, OptrA) and virulence genes (cpsⅢ, bca, fbsA, cpsA, scpB) were investigated by polymerase chain reaction (PCR). Results　Among the 136 clinical isolates of GBS, 20 strains (14.7%) were resistant to OMC, 64 (47.1%) were intermediate, and 52 (38.2%) were sensitive. Fifty-seven strains (41.9%) were biofilm-positive, 20 of which (35.1%) were sensitive to OMC. Seventy-nine strains (58.1%) were biofilm-negative, 32 of which (40.5%) were susceptible to OMC. There was a statistically significant difference in the sensitivity rates between the two groups of strains (χ2=63.062, P<0.001), but there was no significant difference in the sensitivity of OMC among the biofilm-positive strains (Fisher's exact test, P=0.824). The resistance rates of tetM, tetO, ermB and OptrA positive strains were higher than those of negative strains, while tetK was opposite. The presence of tetM (Z=0.815, P=0.415), tetO (Z=0.151, P=0.88), tetK (Z=0.567, P=0.571), ermB (Z=1.198, P=0.231) resistance genes in Streptococcus agalactiae had no significant impact on the sensitivity of OMC. However, the presence of the OptrA resistance gene showed a statistically significant effect on the sensitivity of OMC (Z=2.913, P=0.004). The virulence factors cpsⅢ, bca, fbsA, cpsA and scpB were all detected at a rate higher than 50%. The presence of the virulence genes cpsⅢ (Z=0.222, P=0.824), bca (Z=0.141, P=0.888), fbsA (Z=0.813, P=0.416), and cpsA (Z=1.615, P=0.106) in Streptococcus agalactiae had no significant impact on the sensitivity of OMC. However, there was a significant inter-group difference in the scpB virulence gene (Z=2.844, P=0.004), but the rank mean values and resistance rates of scpB-positive strains were lower than those of the negative strains. Conclusions　The formation of biofilm in Streptococcus agalactiae reduces its sensitivity to OMC, but there was no significant difference in the sensitivity to OMC among the biofilm-positive strains. The presence of resistance genes tetM, tetO, tetK, ermB, and virulence genes cpsⅢ, bca, fbsA, cpsA, scpB in Streptococcus agalactiae is not associated with OMC resistance, but the presence of the resistance gene OptrA is correlated with OMC resistance..

Objective To understand genetic mutation sites in linezolid (LZD)-sensitive and inducible resistant strains of methicillin-resistant Staphylococcus aureus (MRSA) using whole-genome sequencing,and realize mutation sites of LZD-resistant gene.Methods MRSA-MS4 with explicit genotype and whole-genome sequences was induced by LZD of different concentration gradients,LZD-resistant strain MRSA-MS4-LZD100 was obtained,minimum inhibitory concentration(MIC) was detected,domain V of 23S rRNA and ribosomal proteins L3/L4 gene in MRSAMS4-LZD100 were amplified by polymerase chain reaction (PCR),the sequenced products obtained the corresponding mutation site in contrast with the wild-type strain;Illumina PE library was constructed through paired-end sequencing by Illumina HiSeq 2000 technique,and whole genome sequencing was completed based on bioinformatics.Results MRAS-MS4-LZD100 strain was induced after 32 passages,MIC of LZD was 96 μg/mL.Sequencing of PCR products indicated the genetic variations were G2447T mutation in multiple copies of domain V of 23S rRNA gene,and Gly113Val mutation in L3 protein respectively;the whole genome of MRSA-MS4-LZD100 contained 2 744 315 bp,annotation of the whole genome found a total of 2 509 genes,11 tRNA-encoding genes and 2 entire rRNA-encoding operons.The data were submitted to the PubMed,and the GeneBank accession number JXMJ00000000 was assigned;a total of 101 SNPs and 6 Small indels were found,16 of 101SNP mutations occurred in exon,of which the variant proteins with anmino acid sequence alterations included IstB ATP binding domain-containing protein,clumping factor A,IS1272 transposase and so on;3 of 6 Small indel mutations occurred in exon,of which the variant proteins with anmino acid sequence alterations included hypothetical protein,30S ribosomal protein S1,and clumping factor A.Conclusion LZD-resistant strain MRSA-MS4-LZD100 was successfully induced by LZD;beside 23S rRNA V domain and ribosomal L3 protein,the other mutant site exist in this resistant strain,which provide some direction for subsequent study of recessive LZD resistance mechanism.

OBJECTIVETo compare the efficacy of proximal gastrectomy(PG) and total gastrectomy(TG) for adenocarcinoma of esophagogastric junction.

METHODSClinical trials comparing PG with TG for adenocarcinoma of esophagogastric junction published from 1990 to 2012 were searched in Cochrane library, Medline, Embase and China National Knowledge Infrastructure (CNKI), Wanfang Data. Review manager 5.0 was used for meta-analysis and outcome measures included mortality and complication morbidity, as well as nutritional state.

RESULTSA total of 10 studies including 2481 patients were identified and analyzed. The results showed no significant differences in the mortality(OR=1.00, P=0.99) and complication morbidity(OR=2.14, P=0.12) between PG and TG. However, anastomotic stenosis(OR=5.40, P<0.01) and reflux esophagitis(OR=7.12, P=0.01) were more frequently observed in PG group. The nutritional state in TG group was comparable with PG group(WMD=2.09, P=0.57).

CONCLUSIONTG is superior to PG in reducing the morbidity of anastomotic stenosis and reflux esophagitis.

Adenocarcinoma ; surgery ; China ; Clinical Trials as Topic ; Esophagogastric Junction ; surgery ; Gastrectomy ; methods ; Humans ; Stomach Neoplasms ; surgery

Objective: To explore the surgical results and clinicopathological features of gastric cancer patients with liver metastases. Methods: The clinicopathological data and post-operative survival of 37 patients who underwent resection of liver metastasis from gastric cancer at our department from Dec. 2007 to Dec. 2014 were analyzed. Results: The 1-, 3-, and 5-year overall survival rates after resection were 91.4%, 57.9%, and 22.0%, respectively, with a median survival of 37 months. Univariate analysis revealed that lymph node metastasis, multiple hepatic metastases and no preoperative chemotherapy are unfavorable prognostic factors for overall survival. Multivariate analysis identified that lymph node metastasis and number of liver metastasis are independent prognostic factors. Conclusions Gastric cancer patients with a solitary liver metastasis may be good candidates for gastric D2 resection combined with liver R0 resection.