A universal dual-mode hydrogel array based on phage-DNA probe for simultaneous rapid screening and precisely quantitative detection of Escherichia coli O157:H7 in foods by the fluorescent/microfluidic chip electrophoresis methods.

Rapid and specific detection of virulent bacterial strains is a great challenge for food safety regarding large amounts of contaminated samples. Herein, a dual-mode hydrogel array biosensor was constructed to simultaneously rapidly screen and precisely quantitatively detect virulent Escherichia coli O157:H7 (E. coli O157:H7) based on a novel DNA-modified phage probe. First, E. coli O157:H7 was incubated with alginate to form the E. coli O157:H7/hydrogel premix complex. Subsequently, hydrogel formation by cross-linking upon the addition of calcium ions and phages for E. coli O157:H7 modified with a DNA primer (phage-DNA) was added to the alginate hydrogel. The DNA on the complex could trigger rolling circle amplification (RCA) to form a phage probe containing a long-chain DNA skeleton (phage@RCA-DNA). The RCA-DNA was then hybridized with the complementary DNA (cDNA) to form double-stranded DNA fragments (phage@RCA-dsDNA), which could be stained by the SYBR Green dye to emit visual green fluorescence (FL) and determined by a smartphone for rapid screening. Meanwhile, the unreacted cDNA in the supernatant could be quantitatively detected by microfluidic chip electrophoresis (MCE). The signal decrement was also proportional to the bacterial concentration. The detection limit values of E. coli O157:H7 were 50 CFU mL-1 by the FL signal and 6 CFU mL-1 by the MCE signal. The two results could be mutually corrected to decrease the false-positive results. This assay was also employed to detect virulent Salmonella Typhimurium (S. Typhimurium) using the corresponding S. Typhimurium phage@RCA-DNA probe. All these results demonstrated that the universal bioassay was suitable for simultaneous rapid screening and precisely quantitative detection of virulent bacterial strains.

[Sorafenib as salvage therapy in refractory relapsed acute myeloid leukemia with positive FLT3 mutation].

OBJECTIVE: To analyze the effect of sorafenib as salvage therapy used before and/or after allogeneic hematopoietic stem cell transplantation (allo-HSCT) in refractory relapsed FLT3-positive acute myeloid leukemia (AML). METHODS: A total of 16 patients with refractory relapsed FLT3-positive AML, including 10 refractory relapsed pre-transplantation and 6 relapsed after allo-HSCT, were enrolled in this retrospective study. Sorafenib treatment protocols included sorafenib in combination with chemotherapy inducing remission, and sorafenib monotherapy as mauntenance treatment after complete remission (CR). RESULTS: Thirteen of the 16 patients achieved CR after one or two courses of induction therapy, including 7 refractory relapsed pre-transplantation and 6 relapsed after allo-HSCT. With a median follow up of 472 (range, 59-1569) days post-transplantation, 12 patients survived and 4 died. Causes of death included leukemia relapse (n=3) and acute graft-versus-host disease (n=1). The 2-year overall and disease-free survival post-transplantation of the 16 patients were (75.0±10.8) % and (50.5±13.7) % respectively. The main side effect of sorafenib was the skin rash. The incidence of rash was lower in the patients used sorafenib pre-transplantation than those post-transplantation (30.0% vs 75.0%, P=0.043). CONCLUSION: Sorafenib used as salvage therapy befor and/or after transplantation for refractory relapsed FLT3-positive AML could reduce the relapse rate and improve the survival.

A novel "dual-potential" electrochemiluminescence aptasensor array using CdS quantum dots and luminol-gold nanoparticles as labels for simultaneous detection of malachite green and chloramphenicol.

A novel type of "dual-potential" electrochemiluminescence (ECL) aptasensor array was fabricated on a homemade screen-printed carbon electrode (SPCE) for simultaneous detection of malachite green (MG) and chloramphenicol (CAP) in one single assay. The SPCE substrate consisted of a common Ag/AgCl reference electrode, carbon counter electrode and two carbon working electrodes (WE1 and WE2). In the system, CdS quantum dots (QDs) were modified on WE1 as cathode ECL emitters and luminol-gold nanoparticles (L-Au NPs) were modified on WE2 as anode ECL emitters. Then the MG aptamer complementary strand (MG cDNA) and CAP aptamer complementary strand (CAP cDNA) were attached on CdS QDs and L-Au NPs, respectively. The cDNA would hybridize with corresponding aptamer that was respectively tagged with cyanine dye (Cy5) (as quenchers of CdS QDs) and chlorogenic acid (CA) (as quenchers of l-Au NPs) using poly(ethylenimine) (PEI) as a bridging agent. PEI could lead to a large number of quenchers on the aptamer, which increased the quenching efficiency. Upon MG and CAP adding, the targets could induce strand release due to the highly affinity of analytes toward aptamers. Meanwhile, it could release the Cy5 and CA, which recovered cathode ECL of CdS QDs and anode ECL of L-Au NPs simultaneously. This "dual-potential" ECL strategy could be used to detect MG and CAP with the linear ranges of 0.1-100 nM and 0.2-150 nM, with detection limits of 0.03 nM and 0.07 nM (at 3sB), respectively. More importantly, this designed method was successfully applied to determine MG and CAP in real fish samples and held great potential in the food analysis.

[Anti-apoptotic effect of Astragalus Polysaccharide on myeloid cells].

This study was aimed to assess the effect of Astragalus Polysaccharide (ASPS) on in-vitro hematopoiesis. CFU-GM assays were used to determine the effect of ASPS and thrombopoietin (TPO) on granulocytic-monocyte progenitor cells. The CFU assays were also used to investigate the effect of ASPS on the proliferation of HL-60 cells.HL-60 cells were cultured with serum-free RPMI 1640 medium and treated with or without of different concentrations of ASPS. After 72 h incubation, the number of cells were counted.In addition, the caspase-3 and JC-1 expression was determined by flow cytometry with Annexin V/PI double staining. The results showed that ASPS (100, 200 µg/ml) and TPO (100 ng/ml) significantly promoted CFU-GM formation in vitro. Various concentrations of ASPS and TPO also promoted the colony formation of HL-60 cells, the largest effect of ASPS was observed at a concentration of 100 µg/ml. There were no synergistic effects between TPO and ASPS on cellular proliferation. The results also showed that ASPS significantly protected HL-60 cells from apoptosis in condition of serum-free medium culture, suppressed caspase 3 activation, and reduced the cell apoptosis. It is concluded that ASPS can significantly promote the formation of bone marrow CFU-GM and the proliferation of HL-60 cells, the optimal concentration of ASPS is at 100 µg/ml. In the absence of serum inducing apoptosis, ASPS also significantly reduced the apoptosis of HL-60 cells via suppressing the activation of caspase-3.