Encoding DNA Frameworks for Amplified Multiplexed Imaging of Intracellular microRNAs.

Real-time imaging of multiple low-abundance microRNAs (miRNAs) simultaneously in living cells with high sensitivity is of vital importance for accurate cancer clinical diagnosis and prognosis studies. Maintaining stability of nanoprobes resistant to enzyme degradation and enabling effective signal amplification is highly needed for in vivo imaging studies. Herein, a rationally designed one-pot assembled multicolor tetrahedral DNA frameworks (TDFs) by encoding multicomponent nucleic acid enzymes (MNAzymes) was developed for signal-amplified multiple miRNAs imaging in living cells with high sensitivity and selectivity. TDFs could enter cells via self-delivery with good biocompatibility and stability. Two kinds of MNAzymes specific for miRNA-21 and miRNA-155 with fluorescein labeling were encoded in the structure of TDFs respectively through one-step thermal annealing. In the intracellular environment, the TDFs could be specifically bound with its specific miRNA target and form an active DNAzyme structure. The cleavage of the active site would trigger the release of target miRNA and circular fluorescence signal amplification, which enabled accurate diagnosis on miRNA identifications of different cell lines with high sensitivity. Meanwhile, with the specific AS1411 aptamer targeting for nucleolin overexpressed on the surface of the carcinoma cells, this well-designed TDFs nanoprobe exhibited good discrimination between cancer cells and normal cells. The strategy provides an efficient tool for understanding the biological function of miRNAs in cancer pathogenesis and therapeutic applications.

Antiviral activity of Lactobacillus reuteri Protectis against Coxsackievirus A and Enterovirus 71 infection in human skeletal muscle and colon cell lines.

BACKGROUND: Recurrence of hand, foot and mouth disease (HFMD) pandemics continues to threaten public health. Despite increasing awareness and efforts, effective vaccine and drug treatment have yet to be available. Probiotics have gained recognition in the field of healthcare worldwide, and have been extensively prescribed to babies and young children to relieve gastrointestinal (GI) disturbances and diseases, associated or not with microbial infections. Since the faecal-oral axis represents the major route of HFMD transmission, transient persistence of probiotic bacteria in the GI tract may confer some protection against HFMD and limit transmission among children. METHODS: In this work, the antiviral activity of two commercially available probiotics, namely Lactobacillus reuteri Protectis (L. reuteri Protectis) and Lactobacillus casei Shirota (L. casei Shirota), was assayed against Coxsackieviruses and Enterovirus 71 (EV71), the main agents responsible for HFMD. In vitro infection set-ups using human skeletal muscle and colon cell lines were designed to assess the antiviral effect of the probiotic bacteria during entry and post-entry steps of the infection cycle. RESULTS: Our findings indicate that L. reuteri Protectis displays a significant dose-dependent antiviral activity against Coxsackievirus type A (CA) strain 6 (CA6), CA16 and EV71, but not against Coxsackievirus type B strain 2. Our data support that the antiviral effect is likely achieved through direct physical interaction between bacteria and virus particles, which impairs virus entry into its mammalian host cell. In contrast, no significant antiviral effect was observed with L. casei Shirota. CONCLUSIONS: Should the antiviral activity of L. reuteri Protectis observed in vitro be translated in vivo, such probiotics-based therapeutic approach may have the potential to address the urgent need for a safe and effective means to protect against HFMD and limit its transmission among children.

Bacterial imaging with photostable upconversion fluorescent nanoparticles.

Autofluorescence, photodamage and photobleaching are often encountered when using downconverting fluorophores and fluorescent proteins for bacteria labeling. These caveats represent a serious limitation when trying to map bacteria dissemination for prolonged periods. Upconversion nanoparticles (UCNs), which are able to convert low energy near-infrared (NIR) excitation light into higher energy visible or NIR light, can address these limitations. These particles' unique optical properties translate into attractive advantages of minimal autofluorescence, reduced photodamage, deeper tissue penetration and prolonged photostability. Here, we report a UCN-based bacteria labeling strategy using Escherichia coli as prototypic bacteria. A comparative analysis highlighted the superior photostability of UCN-labeled bacteria over green fluorescent protein-expressing bacteria. Infection study of UCN-labeled bacteria in dendritic cells indicated co-localization of the UCN signal with bacterial position for up to 6 h post-infection. Furthermore, long-term monitoring of the same infected cells demonstrated the potential to utilize photostable UCN-based imaging for bacterial trafficking purposes.

Ciprofloxacin-resistant Salmonella enterica serovar Kentucky in Canada.

We report emergence of ciprofloxacin-resistant Salmonella enterica serovar Kentucky in Canada during 2003-2009. All isolates had similar macrorestriction patterns and were multilocus sequence type ST198, which has been observed in Europe and Africa. Ciprofloxacin-resistant S. enterica serovar Kentucky represents 66% of all ciprofloxacin-resistant nontyphoidal Salmonella sp. isolates observed in Canada since 2003.

Emergence of multidrug-resistant Salmonella enterica serotype 4,[5],12:i:- involving human cases in Canada: results from the Canadian Integrated Program on Antimicrobial Resistance Surveillance (CIPARS), 2003-10.

OBJECTIVES: Over the last decade, a marked increase in Salmonella enterica serotype 4,[5],12:i:- with a core resistance to ampicillin, streptomycin, sulphonamides and tetracycline (ASSuT) has been observed in Europe. This study describes the emergence and characterization of isolates of multidrug-resistant Salmonella 4,[5],12:i:- in Canada. METHODS: Human clinical isolates of Salmonella 4,[5],12:i:- were identified by provincial laboratories from 2003 to 2010. Serotyping and phage typing were performed by standardized methodologies. MIC values were determined using broth microdilution. PCR was used to determine the presence of resistance genes. Multilocus sequence typing was performed on a selected number of isolates. RESULTS: A total of 26 251 Salmonella were submitted as part of the Canadian Integrated Program on Antibiotic Resistance Surveillance (CIPARS). Of these, Salmonella 4,[5],12:i:- accounted for a total of 766 isolates (2.9%), and the number increased significantly from 42 (1.4%) in 2003 to 164 (4.8%) in 2010. The ASSuT+ phenotype was observed in 11.9% (n = 91) of Salmonella 4,[5],12:i:- isolates and increased from two isolates in 2003 to 35 isolates in 2010. Two sequence types (STs) were observed. ST34 was mainly associated with the ASSuT isolates (n = 24; 38%), which contained blaTEM, strA-strB, tet(B) and sul2. ST19 was more likely to be associated with the ACSSuT phenotype and contained blaTEM, floR, strA-strB, sul2 and tet(A) or blaPSE-1, floR, aadA2, sul1 and tet(G). CONCLUSIONS: The prevalence of Salmonella 4,[5],12:i:- has significantly increased from 2003 to 2010 and it is now the fifth most common serotype reported in Canada causing human disease. Similar antimicrobial resistance patterns, phage types and STs have been observed in Europe.

Applications of upconversion nanoparticles in imaging, detection and therapy.

Upconversion nanoparticles (UCNs) are an emerging class of luminescent nanomaterials, exhibiting many advantages over conventional fluorophores, such as high signal-to-noise ratio and superior photostability. The near-infrared excitation wavelengths of these particles offer additional advantages such as deep tissue penetration and low photodamage to biological samples. In the last 5 years, with the advances in nanoparticles synthesis and modification technology, much research has been performed to exploit UCNs' advantages and integrate them into various biological applications. This review focuses on the recent developments of UCNs as imaging, detection and therapeutic tools, highlighting the respective strategies adopted.

Identification of prolyliminopeptidase-negative Neisseria gonorrhoeae strains in Canada.

Neisseria gonorrhoeae strains that fail to produce the enzyme prolyliminopeptidase have been identified in Canada. Commercial test panels use prolyliminopeptidase activity for identification and to avoid the misdiagnosis of gonorrhea, at least 2 distinct methods for the confirmatory identification of N. gonorrhoeae is imperative.

Corynebacterium accolens isolated from breast abscess: possible association with granulomatous mastitis.

Corynebacterium accolens is rarely isolated as a human pathogen. We describe here a case of C. accolens isolated from a breast abscess in a patient previously diagnosed with granulomatous mastitis. The possible association of Corynebacterium accolens and granulomatous mastitis in this patient is discussed.