Association of PM2.5 exposure in early pregnancy and maternal liver function: A retrospective cohort study in Shenzhen, China.

OBJECTIVE: Studies have shown that fine particulate matter (PM2.5) has adverse effects on the liver function, but epidemiological evidence is limited, especially regarding pregnant women. This study aims to investigate the association between PM2.5 exposure in early pregnancy and maternal liver function during pregnancy. METHODS: This retrospective cohort study included 13,342 pregnant participants. PM2.5 and Ozone (O3) exposure level, mean temperature, and relative humidity for each participant were assessed according to their residential address. The levels of serum aspartate aminotransferase (AST), alanine aminotransferase (ALT), and total bilirubin (TBIL) were measured during the second and third trimesters. Data on PM2.5 and O3 exposure level were sourced from Tracking Air Pollution in China (TAP), while the mean temperature and relative humidity were obtained from the ERA5 dataset. The Generalized Additive Model (GAM) was used to analyze the associations between PM2.5 exposure and maternal liver function during pregnancy, adjusting for potential confounding factors. RESULTS: According to the results, each 10 µg/m3 increase in PM2.5 was associated with an increase of 3.57% (95% CI: 0.29%, 6.96%) in ALT and 4.25% (95% CI: 2.33%, 6.21%) in TBIL during the second trimester and 4.51% (95% CI: 2.59%, 6.47%) in TBIL during the third trimester., respectively. After adjusting for O3, these associations remained significant, and the effect of PM2.5 on ALT during the second trimester was further strengthened. No significant association observed between PM2.5 and AST. CONCLUSIONS: PM2.5 exposure in early pregnancy is associated with increasement of maternal ALT and TBIL, suggesting that PM2.5 exposure may have an adverse effect on maternal liver function. Although this finding indicates an association between PM2.5 exposure and maternal liver function, more research is needed to confirm our findings and explore the underlying biological mechanisms.

Development of a novel bacterial surface display system using truncated OmpT as an anchoring motif.

OBJECTIVES: An efficient bacterial surface display system based on the anchoring motif derived from Escherichia coli (E. coli) outer membrane protease OmpT was developed in this study. RESULTS: Referring to the classical Lpp-OmpA (LOA) display system, the signal peptide and nine amino acids of mature Lpp were fused to the transmembrane domain comprising five ß-strands of truncated OmpT to generate a novel Lpp-OmpT (LOT) display system. The C-terminal fusion strategy was used to fuse a small peptide (His tag) and red fluorescent protein (mCherry) to the C-terminus of LOT. Cell surface exposure of His tag and mCherry were compared between the LOA and LOT display systems. E. coli expressing LOT-His tag adsorbed more Cu2+ than E. coli expressing LOA-His tag. E. coli expressing both LOT-mCherry-His tag and LOA-mCherry-His tag adhered to Cu2+ chelating sepharose beads, and adhered cells could be dissociated from the beads after excess Cu2+ treatment. More importantly, compared with the LOA system, a higher amount of LOT-mCherry-His tag hybrid protein was demonstrated to be localized at the outer membrane by both fluorescence spectrophotometric determination of cell fractions and cell-surface immunofluorescence assay. CONCLUSIONS: These results suggest that genetically modified OmpT can be used as a potential anchoring motif to efficiently and stably display polypeptides and proteins, and that the LOT system could be used in a variety of biotechnological and industrial processes.

A large meta-analysis of the global prevalence rates of S. aureus and MRSA contamination of milk.

Past reports have indicated a high prevalence of milk contaminated with Staphylococcus aureus (S. aureus) and methicillin-resistant Staphylococcus aureus (MRSA), but the pooled prevalence rates of S. aureus and MRSA in pasteurized and boiled cow's milk, raw cow's milk, and raw Caprinae milk (raw sheep's milk and raw goat's milk) and across different periods, continents, economic conditions and purchase locations remain inconsistent. We searched relevant articles published in PubMed, EMBASE, and Web of Science before July 2016. The Strengthening the Reporting of Observational Studies in Epidemiology (STROBE) Statement was used to evaluate the quality of 93 included studies. We observed that the pooled prevalence rates of S. aureus contamination in pasteurized and boiled cow's milk, raw cow's milk, and raw Caprinae milk were 15.4% (95% CI, 6.1-27.5%), 33.5% (95% CI, 29.5-37.7%) and 25.8% (95% CI, 17.5-35.0%), respectively. The pooled prevalence rates of MRSA contamination were 4.9% (95% CI, 0.0-15.7%), 2.3% (95% CI, 1.3-3.6%), and 1.1% (95% CI, 0.5-1.8%), respectively. The prevalence of S. aureus contamination in raw cow's milk increased over time. However, the pooled prevalence of raw cow's milk contaminated with S. aureus was lowest in European studies. These findings give an indication of the consequence of better milk regulation in Europe. High S. aureus prevalence rates in raw milk collected from farms and processing companies pose a potential threat to consumers. The implementation of good hygiene practices, appropriate health knowledge, and food safety principles at the farm level, as well as the prudent use of antibiotics in veterinary medicine and heat treatment before drinking, are necessary to reduce the potential risk of S. aureus and MRSA contamination.

Prevalence, Influencing Factors, Antibiotic Resistance, Toxin and Molecular Characteristics of Staphylococcus aureus and MRSA Nasal Carriage among Diabetic Population in the United States, 2001-2004.

Diabetic population were reported more likely to suffer carriage and infection with Staphylococcus aureus (S. aureus) and methicillin-resistant Staphylococcus aureus (MRSA) than non-diabetic population. We aim to elucidate the prevalence and characteristics of S. aureus and MRSA nasal carriage among diabetic population in the United States National Health and Nutrition Examination Survey, 2001-2004. Univariate analyses were conducted using Chi-square test, Fisher's exact probability test or student t test, as appropriate. Multivariate analy¬sis using logistic regression was conducted to assess the association between influencing factors and S. aureus and MRSA nasal carriage. 1010 diabetic participants were included in the study. The prevalence of S. aureus and MRSA nasal carriage were 28.32% and 1.09%, respec¬tively. After the logistic regression, ever had a painful sensation or tingling in hands or feet past three months (Odds Ratio [OR] = 0.359, 95% Confidence Interval [CI], 0.146-0.882) was significant among S. aureus nasal carriage and gender (OR = 3.410, 95% CI, 1.091-10.653) was significant among MRSA nasal carriage. The proportions of staphylococcal enterotoxin (SE) A, SEB, SEC, SED, Toxic-shock syn¬drome toxin-1, and Panton Valentine Leukocidin toxin among S. aureus strains were 18.75%, 3.13%, 12.50%, 15.63%, 28.13%, and 9.38%, respectively. 63.63% of MRSA strains were community-acquired, 27.27% were hospital-acquired, and 9.09% were non-typeable. Diabetic patients might be more likely to carry S. aureus and MRSA in the United States. Improving hand hygiene compliance, reducing antibiotic overuse, screening for carriers, and decolonization are recommended to reduce the spread of S. aureus and MRSA, especially in community.

Construction of a RFP-lacZα bicistronic reporter system and its application in lead biosensing.

The combination of a fluorescent reporter and enzymatic reporter provides a flexible and versatile way for the study of diverse biological processes, such as the detection of transcription and translation. Thus, there is an urgent need to develop this novel bifunctional reporter system. This study reports the design, construction, and validation of a new dicistronic mCherry-lacZα reporter system by artificial lac operon and pbr operon models in lacZM15-producing E. coli. It allows two reporter genes to be co-transcribed into a dicistronic mRNA strand, followed by coupled expression of mCherry and lacZα. In artificial lac operons, expression of the downstream lacZα was demonstrated to be positively related to expression of the upstream ORF. In artificial pbr operons, compared with the insertion of downstream full-length lacZ, the insertion of downstream lacZα exerted a slight effect on the response from the upstream mCherry. Furthermore, the downstream lacZα reporter showed stronger response to Pb(II) than the downstream full-length lacZ. Importantly, the response sensitivity of downstream lacZα was still higher than that of upstream mCherry in a dual RFP-lacZα reporter construct. The highly efficient expression profile of the reporter lacZα peptide makes it a preferred downstream reporter in polycistronic constructs. This novel bifunctional reporter system offers a robust tool for biological studies.

Improved Monitoring of Low-Level Transcription in Escherichia coli by a ß-Galactosidase α-Complementation System.

Genetically encoded reporter proteins are important and widely used tools for the identification and capture of a promoter, tracking the dynamic behavior of transcription, and the quantification of promoter activity. The sensitivity of the reporter gene is a critical factor for an ideal reporter system because weak transcriptional signal has usually failed to be detected using classical reporters. In this study, we present a novel reporter system for improved monitoring of transcription in E. coli based on ß-galactosidase α-complementation. In this reporter system, the ß-galactosidase activity resulting from the assembly of a reporter lacZα and an existing α-acceptor in advance serves as a measure of transcriptional activity in vivo. To validate the potential of the lacZα-derived reporter system, a series of artificial operons were constructed, and the moderately strong lac promoter, ara promoter, and weak pbr promoter were chosen as the detection promoters. The response profiles of lacZα was similar to that of wild type lacZ in artificial lac operons. Due to its small size and efficient expression profile, the detection sensitivity of a lacZα-derived reporter system was significantly higher than that of the traditional full-length ß-galactosidase and the fluorescent protein mCherry reporter system in artificial ara operons. As expected, the response sensitivity of the lacZα-derived reporter system was also demonstrated to be significantly higher than that of the ß-galactosidase and mCherry reporter systems in lead-sensitive artificial pbr operons. The lacZα-derived reporter system may prove to be a valuable tool for detecting promoter activity, especially low-level transcription in vivo.

Nasal colonization of Staphylococcus aureus colonal complex 5: Prevalence, influencing factors, and phenotypic and molecular characteristics in pregnant Chinese women.

BACKGROUND: Colonal complex 5 (CC5) has been referred to as the most pandemic community-associated Staphylococcus aureus in most Asian countries. However, few studies have focused on CC5 isolates in pregnant women. The aim of this study was to determine the prevalence and phenotypic and molecular characteristics of S aureus and methicillin-resistant S aureus (MRSA) CC5 nasal colonization in pregnant Chinese women. METHODS: We performed a cross-sectional study between August and November 2015 in 2 hospitals in Shenzhen, China. Pregnant women were asked to complete questionnaires, and nasal swabs were collected. Log-binomial regression models were used to explore factors influencing S aureus and MRSA nasal colonization between the CC5 and non-CC5 or non-S aureus groups. Polymerase chain reaction assays were used to detect the molecular characteristics of isolates. RESULTS: Overall, 2,172 pregnant women were included in this study. The prevalence of S aureus and MRSA was 25.60% (n = 556) and 5.62% (n = 122), respectively. The multilocus sequence typing of S aureus isolates was diversified. A lower frequency of daily handwashing (<7) and weekly bathing (<7) were risk factors for the prevalence of S aureus (adjusted prevalence ratio [aPR], 1.13; 95% confidence interval [CI], 1.03-1.41 and aPR, 1.22; 95% CI, 1.03-1.45) and MRSA (aPR, 1.96; 95% CI, 1.23-3.14 and aPR, 1.47; 95% CI, 1.21-2.44) nasal colonization in the CC5 groups of pregnant women. CONCLUSIONS: The prevalence of S aureus and MRSA nasal colonization was moderate. The molecular characteristics of S aureus and MRSA isolates indicated possible cross-transmission among multiple resources. A higher frequency of daily handwashing and weekly bathing significantly decreased the prevalence of S aureus and MRSA CC5 nasal colonization in the pregnant women.