Molecular epidemiology of Listeria monocytogenes isolated from ready-to-eat food in 2017 in China / 中华预防医学杂志

To analyze the molecular characteristics of strains from ready-to eat food in China. A total of 239 strains isolated from ready-to-eat food in 2017, all strains underwent whole-genome sequencing (WGS) , and comparisons uncovered population structure derived from lineages, clonal complex, serogroups, antimicrobial susceptibility and virulence, which were inferred in silico from the WGS data. Core genome multilocus sequence typing was used to subtype isolates. All strains were categorized into three different lineages, lineage Ⅱ was the predominant types in food, and IIa was the main serogroups. CC8, CC101 and CC87 were the first three prevalent CCs among 23 detected CCs, accounting for 49.4%. Only 4.6% (11 isolates) of tested strains harbored antibiotic resistance genes, which were mostly trimethoprim genes (7 isolates, 2.9%). All strains were positive for LIPI-1, and only a part of strains harbored LIPI-3 and LIPI-4, accounting for 13.8% (33 isolates) and 14.2% (34 isolates), respectively. ST619 carried both LIPI-3 and LIPI-4. 51.5% (123 isolates) of strains carried SSI-1, and all CC121 strains harbored SSI-2. Different lineages, serogroups and CCs can be separated obviously through cgMLST analysis, and 24 sublineages were highly concordant with CCs. Ⅱa was the main serogroups in ready-to-eat food isolates in China; CC8, CC101 and CC87 were the prevalent CCs, and CC87 isolates was hypervirulent isolates, cgMLST method can be adopted for prospective foodborne disease surveillance and outbreaks detection.

Association between IL-6 C-572G and susceptibility to spontaneous preterm birth / 中国当代儿科杂志

<p><b>OBJECTIVE</b>To investigate the association between the genetic polymorphism of IL-6 C-572G and susceptibility to spontaneous preterm birth (SPTB).</p><p><b>METHODS</b>The subjects were from Beijing and the surrounding areas of Beijing. This case-control study enrolled 569 SPTB infants, including 56 extremely preterm (<28 weeks of gestation), 166 very preterm (28-31weeks of gestation) and 347 moderate to late preterm infants (32 to 36weeks of gestation). A total of 673 term infants were enrolled as the control group. The latest Sequenom MassARRAY®SNP detection technique was used for the typing of single nucleotide polymorphism of IL-6 C-572G.</p><p><b>RESULTS</b>Compared with the CC genotypes, the IL-6 C-572G G-positive genotype (CG+GG genotype) was significantly associated with an increased susceptibility to moderate to late SPTB (OR=1.35, 95%CI: 1.01-1.80, P=0.04).</p><p><b>CONCLUSIONS</b>Among the Chinese population, IL-6 C-572G polymorphism is associated with susceptibility to moderate to late SPTB.</p>

Association between interleukin-1β C+3953T and genetic susceptibility to spontaneous preterm birth: a case-control study / 中国当代儿科杂志

<p><b>OBJECTIVE</b>To study the association between interleukin-1β (IL-1β) C+3953T and genetic susceptibility to spontaneous preterm birth (SPTB).</p><p><b>METHODS</b>In this case-control study, 753 SPTB neonates were enrolled in the case group and 681 full-term neonates were enrolled in the control group. The latest Sequenom MassARRAY®SNP detection technique was used for the typing of single nucleotide polymorphisms (SNP) of IL-1β C+3953T.</p><p><b>RESULTS</b>Compared with those carrying CC genotype of IL-1β C+3953T, the neonates who carried at least one T allele (CT+TT genotype) had significantly increased risks of SPTB, SPTB complicated by premature rupture of membranes, and mild preterm birth.</p><p><b>CONCLUSIONS</b>In the Chinese population, IL-1β C+3953T has significant genetic association with an increased risk of SPTB. The identification of this SNP helps to prevent SPTB and clarify the causes and pathogenesis of SPTB.</p>

Association between tumor necrosis factor-α G-308A polymorphisms and genetic susceptibility to spontaneous preterm birth / 中国当代儿科杂志

<p><b>OBJECTIVE</b>To study the association between tumor necrosis factor-α (TNF-α) G-308A polymorphisms and genetic susceptibility to spontaneous preterm birth (SPTB).</p><p><b>METHODS</b>The case group enrolled 753 SPTB infants and the control group included 681 term infants. TNF-α G-308A polymorphisms were genotyped using Sequenom MassARRAY®SNP.</p><p><b>RESULTS</b>The frequencies of the allele (G and A) in the case and control groups were not significantly different (P=0.35). The frequencies of the genotypes (GG, GA and AA) in the case and control groups were not significantly different (P=0.64). The logistic regression analysis found that TNF-α G-308A was not associated with genetic susceptibility to SPTB (OR=0.85; 95%CI: 0.61-1.19; P=0.35).</p><p><b>CONCLUSIONS</b>There is no association between the polymorphisms of TNF-α G-308A and the genetic susceptibility to SPTB.</p>

A case-control study on association between OAS1 polymorphism and susceptibility to spontaneous preterm birth and preterm premature rupture of membranes / 中国当代儿科杂志

<p><b>OBJECTIVE</b>To investigate the association between the genetic polymorphism of 2',5'-oligoadenylate synthetase 1 (OAS1) and susceptibility to spontaneous preterm birth (SPTB) and preterm premature rupture of membranes (PPROM).</p><p><b>METHODS</b>The case-control study consisted of 599 preterm infants including 171 cases of PPROM, and 673 full-term infants without maternal histories of SPTB and PPROM as controls. The single nucleotide polymorphism (SNP) at OAS1 intron 5, rs10774671, was analyzed by polymerase chain reaction-restriction fragment length polymorphism.</p><p><b>RESULTS</b>No significant differences were observed between the case and control groups in the frequencies of genotypes (AA, GA, and GG) and alleles (A and G) of OAS1 rs10774671. When the case group was divided into two subgroups with or without PPROM, no significant differences in the genotype and allele frequencies were found between each subgroup and the control group. When the case group was divided into three subgroups with different gestational ages at SPTB, no significant differences in the genotype and allele frequencies were detected between each subgroup and the control group.</p><p><b>CONCLUSIONS</b>No association is identified between OAS1 SNP and susceptibility to SPTB and PPROM.</p>

Establishment and comparison of pulsed-field gel electrophoresis, multiple-locus variable number tandem repeat analysis and automated ribotyping methods for subtyping of Citrobacter strains / 生物医学与环境科学（英文）

<p><b>OBJECTIVE</b>To establish and compare the pulsed-field gel electrophoresis (PFGE), multiple-locus variable number tandem repeat analysis (MLVA) and automated ribotyping for subtyping of Citrobacter strains.</p><p><b>METHODS</b>PFGE protocol was optimized in terms of plug preparation procedure, restriction enzymes and configuration of electrophoretic parameters. MLVA method was evaluated by finding variable number tandem repeats in two genomes of Citrobacter strains. The ribotyping was performed by using the automated RiboPrinter system.</p><p><b>RESULTS</b>We optimized the plug preparation procedure, focused on the cell suspension concentration (turbidity of 2.5 to 3.5), SDS addition (no SDS needed) and lysis time (1 h), and selected the appropriate restriction enzyme (XbaI) and the electrophoretic parameters (1.0 s-20.0 s for 19 h) of PFGE. There was nearly no discriminatory power of MLVA between Citrobacter strains. For 51 Citrobacter strains, automated ribotyping gave a D-value of 0.9945, while PFGE gave a D-value of 0.9969. Both PFGE and automated ribotyping clustered strains from the same sources (with the same species from the same place at the same time identified as the same source) and divided strains from different sources (from different years, places and hosts) into different subtypes.</p><p><b>CONCLUSION</b>PFGE protocol established in this paper and automated ribotyping are suitable for application in Citrobacter subtyping.</p>

Secretion expression of cholera toxin B subunit in food-grading Lactococcus lactis expression system / 中华流行病学杂志

<p><b>OBJECTIVE</b>To clone and secretion express cholera toxin B subunit (CTB) in food-grading Lactococcus lactis expression systems.</p><p><b>METHODS</b>ctB fragment that encoding CTB was amplified by polymerase chain reaction (PCR) using the genomic DNA of Vibrio cholera strain 569B as template and was inserted into two secretion expression vector pSQZ and pSQ to construct food-grading expression system L.lactis MBP71/pSQZ-ctB and L.lactis MBP71/pSQ-ctB. The expressed CTB was detected by Western-blot assay.</p><p><b>RESULTS</b>The ctB fragment was successfully amplified from Vibrio cholera strain 569B and inserted into two secretion expression vectors pSQZ and pSQ to construct food-grading expression system L. lactis MBP71/pSQZ-ctB and L. lactis MBP71/pSQ-ctB. Western-blot assay demonstrated that CTB was secretion and expressed from L.lactis MBP71 harboring vectors pSQZ-ctB and pSQ-ctB, and the quantity of CTB secreted by L. lactis MBP71/pSQ-ctB was about 2 microg/ml, higher than that of L. lactis MBP71/pSQZ-ctB.</p><p><b>CONCLUSION</b>CTB was successfully secreted and expressed by food-grading L. lactis expression systems.</p>

Mitochondrial DNA mutation analysis in patients with mitochondrial myopathy / 中华医学遗传学杂志

<p><b>OBJECTIVE</b>To examine mitochondrial DNA mutations in mitochondrial myopathy.</p><p><b>METHODS</b>Three suspected cases of mitochondrial myopathy were examined by HE staining, histochemical staining methods and electron microscopy. The mutations in all 22 tRNA genes of mitochondrial genome were screened by polymerase chain reaction-single strand conformation polymorphism and DNA sequencing.</p><p><b>RESULTS</b>The three cases were diagnosed as mitochondrial myopathy. The examinations revealed that patient 1 had a homoplasmic A1627G mutation in tRNA-Val gene, and patient 2 had a heteroplasmic A1627G/A mutation in tRNA-Val gene, and patient 3 had two mutationsuone was homoplasmic T5554C mutation in tRNA-Trp gene, the other was heteroplasmic A10412C/A mutation in tRNA-Arg gene.</p><p><b>CONCLUSION</b>tRNA genes mutations of mtDNA might be one of the etiologies of mitochondrial myopathy.</p>