Proliferating Stem Cells are Acutely Affected by DNA Damage Induced by Sulfur Mustard.

Sulfur mustard (SM), a chemical warfare agent, can form adducts with DNA, RNA, and proteins. Reactions with DNA lead to the formation of both DNA monoadducts and interstrand cross-links, resulting in DNA damage, and is an important component of SM toxicity. Our previous in vivo studies indicated that dividing cells such as hematopoietic stem cells and intestinal villi stem cells seemed to have increased sensitivity to SM. Therefore, to compare the sensitivity of somatic and stem cells to SM and to investigate the mechanism of SM cytotoxicity, we isolated human foreskin fibroblasts, reprogrammed them into pluripotent stem cells, and then compared the DNA damage repair pathways involved upon SM treatment. Our results indicated that proliferating stem cells were more sensitive to SM-induced DNA damage, and the damage mainly comprised single-stranded breaks. Furthermore, the pathways involved in DNA repair in stem cells and somatic cells were different.

Therapeutic Effects of Human Umbilical Cord Mesenchymal Stromal Cells in Sprague-Dawley Rats with Percutaneous Exposure to Sulfur Mustard.

Sulfur mustard (SM) exposure, whose symptoms are similar to radiation exposure, can lead to acute injury. Because mesenchymal stromal cells (MSCs) have been used to experimentally and clinically treat acute radiation syndrome, in this study, MSCs were intravenously injected into rats after percutaneous SM exposure. Then, we examined sternum and spleen samples by histopathological and immunohistochemical methods to observe pathological changes. Furthermore, blood samples were taken to test the white blood cell (WBC) count, blood platelet count (BPC), red blood cell count, and the levels of cytokines in the serum. The number of bone marrow karyocytes and the WBC in the MSC + SM group were higher than those in the SM group, and the levels of granulocyte colony-stimulating factor, granulocyte-macrophage colony stimulating factor, monocyte chemoattractant protein-1, interleukin (IL)-1α, IL-5, and interferon-γ in the MSC + SM group remained high at different time points after SM exposure. In addition, the BPC, the level of erythropoietin and the relative weight of the spleen in the MSC + SM group were significantly higher than those in the SM group. Meanwhile, spleens in the MSC + SM group were more hyperplastic and hematopoietic, and had fewer apoptotic cells than in the SM group. Furthermore, rat body weight and locomotion ability in the MSC + SM group were higher than in the SM group. This evidence supports the potential ability of MSCs in immunoregulation and functional improvements to the hemopoietic microenvironment. Intravenous injection of MSCs exerted significant therapeutic effects in rats with percutaneous exposure to SM.

Prolonged exposure to carbon nanoparticles induced methylome remodeling and gene expression in zebrafish heart.

Growing black carbon (BC) emission has become one of the major urgent environmental issues facing human beings. Usually, BC or BC-containing carbon nanoparticles (CNPs) were recognized as non-directly toxic components of atmospheric particulate matter. However, epidemiology studies have provided much evidence of the associations of exposure of particulate-containing carbon particles with cardiovascular diseases. There are still no related studies to support the epidemiological conclusions. Hence, in this article we exposed adult zebrafish to CNPs for 60 days, and then explored the heart location and potential adverse effects on cardiac tissues of these nanosized carbon particles. Our results first showed direct visualization of cardiac endothelial uptake and heart deposition of CNPs in zebrafish. In addition, CNPs caused significant ultrastructural alterations in myocardial tissue and induced the expression of inflammatory cytokines in a dose-dependent manner, resulting in sub-endocardial inflammation and cell apoptosis. Moreover, our data demonstrated the perturbations caused by CNPs on DNA methylation, suggesting that DNA methylome remodeling might play a critical role in CNP-induced cardiotoxicity in zebrafish heart. Therefore, this study not only proved a laboratory link between CNP exposure and cardiotoxicity in vivo, but also indicated a possible toxicity mechanism involved.

Characterization of phiCFP-1, a virulent bacteriophage specific for Citrobacter freundii.

Citrobacter freundii, a Gram-negative bacterium, causes many opportunistic infections. Bacteriophage phiCFP-1 was isolated and characterized by its ability to lyse the multidrug-resistant clinical C. freundii strain P10159. Transmission electron microscopy showed that the phage has an icosahedral head and a short tail, making it a Podoviridae family member. In a single-step growth experiment, phiCFP-1 exhibited an eclipse period of 20 min and a burst size of 100 particles per cell. Its genome assembled as a circular molecule when genomic sequencing was completed. However, based on genome content and organization, it was categorized as a classic T7-related phage, and such phages are known to have linear genomes with direct terminal repeats. With the quick and simple method established herein, the 38,625-bp linear double-stranded DNA with 229-bp direct terminal repeats was accurately identified. The genome contained 43 putative open reading frames and no tRNA genes. Using a proteomics-based approach, seven viral and two host proteins from purified phiCFP-1 particles were identified. Comparative genomics and recombination analyzes revealed close genetic relatedness among phiCFP-1, phiYeO3-12/vB_YenP_AP5 (from Yersinia enterocolitica O3), and phiSG-JL2 (from Salmonella enterica).

Detection of Streptococcus pyogenes using rapid visual molecular assay.

Streptococcus pyogenes is an increasingly important pathogen in many parts of the world. Rapid and accurate detection of S. pyogenes aids in the control of the infection. In this study, a loop-mediated isothermal amplification (LAMP) assay was developed and validated for the specific detection of S. pyogenes. The assay incorporates two methods: a chromogenic analysis using a calcein/Mn(2+) complex and real-time turbidity monitoring to assess the reaction. Both methods detected the target DNA within 60 min under 64°C isothermal conditions. The assay used specifically designed primers to target spy1258, and correctly identified 111 strains of S. pyogenes and 32 non-S. pyogenes strains, including other species of the genus Streptococcus. Tests using reference strains showed that the LAMP assay was highly specific. The sensitivity of the assay, with a detection limit of 1.49 pg DNA, was 10-fold greater than that of PCR. The LAMP assay established in this study is simple, fast and sensitive, and does not rely upon any special equipment; thus, it could be employed in clinical diagnosis.

A novel New Delhi metallo-ß-lactamase variant, NDM-14, isolated in a Chinese Hospital possesses increased enzymatic activity against carbapenems.

A novel New Delhi metallo-ß-lactamase (NDM) variant, NDM-14, was identified in clinical isolate Acinetobacter lwoffii JN49-1, which was recovered from an intensive care unit patient at a local hospital in China. NDM-14, which differs from other existing enzymes by an amino acid substitution at position 130 (Asp130Gly), possesses enzymatic activity toward carbapenems that is greater than that of NDM-1. Kinetic data indicate that NDM-14 has a higher affinity for imipenem and meropenem.

Proteomic analysis of the interaction of Bifidobacterium longum NCC2705 with the intestine cells Caco-2 and identification of plasminogen receptors.

To identify proteins with a potential role in the interaction of Bifidobacterium longum with intestinal epithelial cells, we profiled the protein response of B. longum NCC2705 following interaction with Caco-2 cells. Thirty-one protein spots, belonging to a total of 23 proteins, which exhibited a change in abundance of at least 3-fold were identified in B. longum NCC2705 following co-culture with Caco-2 cells, and were subsequently identified. Changes in expression were confirmed at the transcriptional level for a selection of these proteins. Enolase (Eno) and elongation factor Tu (EF-Tu) were amongst the proteins that showed the most prominent increase in abundance. Interaction of these proteins with plasminogen (Plg) was analyzed by Plg overlay assays, glutathione S-transferase (GST)-pull down, and western blot analysis. The results suggested that EF-Tu and Eno serve as surface receptors for B. longum NCC2705 binding to human plasminogen. Purified GST-EF-Tu and GST-Eno inhibited adhesion of B. longum NCC2705 to Caco-2 cells. Collectively, our data suggest that Eno and EF-Tu moonlight as adhesions, and are possibly involved in the protective role played by B. longum NCC2705 in defense against enteric pathogens. Biological significance The interaction of bifidobacteria with the human host plasminogen/plasmin system confirms the existence of a new component in the molecular cross-talk between bacteria and the host. Our study analyzed proteins EF-Tu and Eno with Plg binding activity, and they can inhibit adhesion of B. longum NCC2705 to Caco-2 cells, suggesting their role in the bacterial adherent to the enterocyte surface.

Abnormal fecal microbiota community and functions in patients with hepatitis B liver cirrhosis as revealed by a metagenomic approach.

BACKGROUND: Assessment and characterization of human colon microbiota is now a major research area in human diseases, including in patients with hepatitis B liver cirrhosis (HBLC). METHODS: We recruited 120 patients with HBLC and 120 healthy controls. The fecal microbial community and functions in the two groups were analyzed using high-throughput Solexa sequencing of the complete metagenomic DNA and bioinformatics methods. RESULTS: Community and metabolism-wide changes of the fecal microbiota in 20 HBLC patients and 20 healthy controls were observed and compared. A negative correlation was observed between the Child-Turcotte-Pugh scores and Bacteroidetes (P < 0.01), whereas a positive correlation was observed between the scores and Enterobacteriaceae and Veillonella (P < 0.01). Analysis of the additional 200 fecal microbiota samples demonstrated that these intestinal microbial markers might be useful for distinguishing liver cirrhosis microbiota samples from normal ones. The functional diversity was significantly reduced in the fecal microbiota of cirrhotic patients compared with in the controls. At the module or pathway levels, the fecal microbiota of the HBLC patients showed enrichment in the metabolism of glutathione, gluconeogenesis, branched-chain amino acid, nitrogen, and lipid (P < 0.05), whereas there was a decrease in the level of aromatic amino acid, bile acid and cell cycle related metabolism (P < 0.05). CONCLUSIONS: Extensive differences in the microbiota community and metabolic potential were detected in the fecal microbiota of cirrhotic patients. The intestinal microbial community may act as an independent organ to regulate the body's metabolic balance, which may affect the prognosis for HBLC patients.