Xiuling Song

A Pharmacological Activator of AMP-Activated Protein Kinase Protects Hypoxic Neurons in a Concentration-Dependent Manner

Abstract5′adenosine monophosphate-dependent protein kinase (AMPK) is a member of metabolite-sensing kinase family which plays an important role in intracellular energy metabolism, particularly in the hypoxic neurons process. However, the effect of AMPK activation on hypoxic neurons remains controversial. In the present study, we report that the effect of AMPK activation induced by pretreatment with 5-aminoimidazole-4-carboxamide-1-b-4-ribofuranoside (AICAR) in neurons using the hypoxic model in vitro. The level of AMPK activation, the neuronal viability, and the levels of two important cytoskeleton proteins were analyzed during the oxygen deprivation. The AMPK activation was increased with the elevation of the AICAR concentration in hypoxic neurons. Moreover, the AMPK activation induced by AICAR protected neurons against death from hypoxic deprivation and that strongly depended on the extent of the AMPK activation. The AMPK activation at specific range protects hypoxic neurons, but the protective effect of AMPK activation disappeared when the AMPK was over-activated by AICAR. The result from an AMPK inhibitor, Compound C, in hypoxic neurons further proves the neuroprotective effect of AICAR.

Layer-by-layer assembly of polyoxometalate–pyrene-decorated fluorescent microspheres for the suspension immunoassay of Listeria monocytogenes

A fluorescence microsphere suspension array technique has been developed as a promising tool for the molecular detection of Listeria monocytogene (LM), which is a dangerous food borne pathogen that can cause severe food intoxication in both humans and animals. In such a technique, fluorescent microspheres as the key matrix for detection are often decorated with neutral organic dyes, which usually suffer from instability, easy photobleaching and loss from the matrix. Herein, we design and synthesize a new organic-inorganic hybrid POM-pyrene compound [N(C4H9)4]2[V6O13{(OCH2)3CNH-CH2-C16H9}2] (1), which is employed as a negatively-charged fluorescent material to prepare a new class of fluorescent microspheres by a layer-by-layer electrostatic self-assembly method. As a result, such POM-pyrene-decorated fluorescent microspheres possess obvious luminescence properties, superior photo-stability and long-term stability. Therefore, the POM-pyrene-decorated fluorescent microspheres are conjugated by monoclonal anti-LM antibodies, and introduced into the fluorescence microsphere-based suspension immunoassay system for the detection of LM in food, which exhibits a high sensitivity. The lowest limit of detection (LOD) of LM in artificially contaminated meat is down to 6 CFU g-1 without cross-reactivity with other pathogens. Furthermore, the suspension immunoassay based on PS@POM-pyrene microspheres shows excellent specificity to LM, good repeatability and high efficiency in contrast to the conventional culture-based method.

A novel recombinant multi-epitope protein against Brucella melitensis infection

Live, attenuated Brucella vaccines are considered effective but can induce abortions in pregnant animals and are potentially infectious to humans. There is a strong need to improve the immunoprotective effects and safety of vaccines against Brucella. Currently, subunit vaccines have been demonstrated to be safe and efficacious alternatives in both humans and animals. In this study, we employed bioinformatics tools to predict B and T cell epitopes to aid development of a novel recombinant multi-epitope antigen for brucellosis vaccination. To evaluate the protective capacity of the recombinant antigen, the antigens efficacy was studied in a mouse model of brucellosis. Our results indicated that BALB/c mice immunized with this recombinant multi-epitope antigen showed mixed Th1-Th2 immune responses with high levels of specific IgG and exhibited high degrees of IFN-γ and IL-6 and significantly higher CD3, CD4, and CD8 frequencies compared to the control group. The recombinant antigen and vaccine strain M5-90 also provided protection against Brucella melitensis 16 M infection. Using bioinformatics tools to develop candidate vaccines is a promising strategy for the development of Brucella vaccines.

Pharmacokinetics of Anti-HBV Polyoxometalate in Rats

Polyoxometalates are non-nucleoside analogs that have been proven to exhibit broad-spectrum antiviral activity. In particular, Cs2K4Na[SiW9Nb3O40].H2O 1 shows low toxicity and high activity against HBV. The preclinical pharmacokinetics of Compound 1 in rats were characterized by establishing and applying inductively coupled plasma-mass spectrometry method to determine the concentration of W in plasma, urine, feces, bile and organ samples. The quantitative ICP-MS method demonstrated good sensitivity and application in the pharmacokinetics study of polyoxometalates. The pharmacokinetic behavior of Compound 1 after intravenous or oral administration fit a two-compartment model. Tmax ranges from 0.1 h to 3 h and the T1/2 of Compound 1 is between 20 h and 30 h. The absolute bioavailability of Compound 1 at 45, 180 and 720 mg/kg groups were 23.68%, 14.67% and 11.93%, respectively. The rates of plasma protein binding of Compound 1 at 9, 18 and 36 mg/ml of Compound 1 are 62.13±9.41%, 71.20±24.98% and 49.00±25.59%, respectively. Compound 1 was widely distributed throughout the body, and high levels of compound 1 were found in the kidney and liver. The level of Compound 1 in excretion was lower: 30% for urine, 0.28% for feces and 0.42% for bile, respectively. For elaborate pharmacokinetic characteristics to be fully understood, the metabolism of Compound 1 needs to be studied further.

A sandwich immunoassay for brucellosis diagnosis based on immune magnetic beads and quantum dots

&NA; Brucellosis is a serious zoonosis with a rapid increase in incidence across epidemic regions. Currently, there are numerous methods for diagnosing brucellosis. However, these studies often have a few defects, such as low sensitivity, poor specificity, time consuming, laborious, and even potential biological risk. To overcome these shortcomings, we have developed a rapid, sensitive and accurate diagnosis procedure for brucellosis based on the immune magnetic beads (IMB) probe and quantum dots (QDs) – staphylococcal protein A (SPA) probe. With the presence of Brucella antibody in the tested serum, the QDs‐SPA probe links to the IMB probe and an immune‐sandwich complex is formed. As a result, the fluorescence intensity from QDs increased significantly and was correlated with the amount of Brucella antibody. Under the optimized conditions, 248 blood samples were detected and the diagnosis effect was evaluated. The area under the receiver‐operating characteristic (ROC) curve was 0.970 (95% confidence interval (CI), 0.9479–0.9920). The diagnostic sensitivity was 96.15% (95% CI, 91.82–98.58%), the diagnostic specificity was 94.12% (95% CI, 87.64–97.81%) with a fluorescence intensity cutoff value of 150.4 and the detection time was only 100 min. This diagnostic procedure can be satisfactorily applied to the diagnosis of brucellosis. Graphical abstract Figure. No caption available. HighlightsWe design a rapid, sensitive and accurate diagnosis procedure for brucellosis.IMB probe was utilized to enrich and separate the Brucella antibodies in serum.QDs‐SPA probe could be bind to antibodies strongly and be employed to generate the detectable fluorescent signal.This sandwich immunoassay was satisfactorily applied to the diagnosis of brucellosis.

Rapid and Quantitative Detection of Vibrio parahemolyticus by the Mixed-Dye-Based Loop-Mediated Isothermal Amplification Assay on a Self-Priming Compartmentalization Microfluidic Chip

Vibrio parahemolyticus (VP) mostly isolated from aquatic products is one of the major causes of bacterial food-poisoning events worldwide, which could be reduced using a promising on-site detection method. Herein, a rapid and quantitative method for VP detection was developed by applying a mixed-dye-loaded loop-mediated isothermal amplification (LAMP) assay on a self-priming compartmentalization (SPC) microfluidic chip, termed on-chip mixed-dye-based LAMP (CMD-LAMP). In comparison to conventional approaches, CMD-LAMP was advantageous on the limit of detection, which reached down to 1 × 103 CFU/mL in food-contaminated samples without the pre-enrichment of bacteria. Additionally, as a result of the use of a mixed dye and SPC chip, the quantitative result could be easily acquired, avoiding the requirement of sophisticated instruments and tedious operation. Also, CMD-LAMP was rapid and cost-effective. Conclusively, CMD-LAMP has great potential in realizing the on-site quantitative analysis of VP for food safety.

Colorimetric immunoassay for rapid detection of Vibrio parahaemolyticus based on Mn2+-mediate the assembly of gold nanoparticles

Vibrio parahemolyticus ( V. parahemolyticus) is an important food-borne pathogen that causes food poisoning and acute gastroenteritis in humans. Herein, a novel colorimetric immunoassay was presented for rapid detection of V. parahemolyticus using gold nanoparticles (18.1 nm diameter) as chromogenic substrate, whose combination of a magnetic bead-based sandwich immunoassay and an optical sensing system via Mn2+ ions mediated aggregation of gold nanoparticles. MnO2 nanoparticles coated with polyclonal IgG antibodies (7.8 nm diameter) are used to recognize the target and can be etched to generate manganese ions by ascorbic acid. A color change ranging from red to purple to blue can be easily discerned by bare eye, corresponding to V. parahemolyticus concentration in the range between 10 and 106 cfu·mL-1. The proposed method possesses high specificity with a limit of detection of 10 cfu·mL-1 and was successfully applied to determination of V. parahemolyticus in oyster samples without pre-enrichment. In our perception, it shows promise in rapid instrumental and on-site visual detection of V. parahemolyticus.

Development of a self-priming PDMS/paper hybrid microfluidic chip using mixed-dye-loaded loop-mediated isothermal amplification assay for multiplex foodborne pathogens detection

Foodborne pathogen is the primary cause of foodborne disease outbreak. Given its great damage, a sensitive, simple and rapid detection method is demanded. Herein, we described a self-priming polydimethylsiloxane (PDMS)/paper hybrid microfluidic chip, termed SPH chip, with mixed-dye-loaded loop-mediated isothermal amplification (LAMP) for multiplex foodborne pathogens detection. Staphylococcus aureus (SA) and Vibrio parahaemolyticus (VP) were chosen to verify the novel method. Compared to other similar detection devices, the SPH chip required easier fabrication process, less operation steps and lower cost. Additionally, the reaction result, especially for the weak-positive reaction, could be judged more accurately and conveniently due to the use of mixed-dye. Without pre-enrichment of bacteria in the food contaminated sample, the limit of detection (LOD) reached down to 1000 CFU mL-1 with high specific. Additionally, for fully exploiting the potential of SPH chip, a conceptual eight-channel detection chip was also developed. Overall, the reliable and excellent result demonstrated that the novel method had great potential to be applied in the wider range of pathogens detection or disease diagnose, especially in some resource-limited area.