Target-Induced Conjunction of Split Aptamer Fragments and Assembly with a Water-Soluble Conjugated Polymer for Improved Protein Detection

Rapid and sensitive detection of proteins is crucial to biomedical research as well as clinical diagnosis. However, so far, most detection methods rely on antibody-based assays and are usually laborious and time-consuming, with poor sensitivity. Herein, we developed a simple and sensitive fluorescence-based strategy for protein detection by using split aptamer fragments and a water-soluble polycationic polymer (poly­{[9,9-bis­(6′-(<i>N</i>,<i>N</i>,<i>N</i>-diethylmethylammonium)­hexyl)-2,7-fluorenylene ethynylene]-alt-<i>co</i>-[2,5-bis­(3′-(<i>N</i>,<i>N</i>,<i>N</i>-diethylmethylammonium)-1′-oxapropyl)-1,4-phenylene] tetraiodide} (PFEP)). The thrombin-binding DNA aptamer was split into two fragments for target recognition. The PFEP with high fluorescence emission was used as energy donor to amplify the signal of dye-labeled DNA probe. In the absence of target, three DNA/PFEP complexes were formed via strong electrostatic interactions, resulting in efficient Föster resonance energy transfer (FRET) between two fluorophores. While the presence of target induces a conjunction of two split aptamer fragments to form G-quadruplex, and subsequent assemble with PFEP leading to the formation of G-quadruplex/thrombin/PFEP complex. The distance between the PFEP and dye increased due to protein’s large size, leading to a remarkable decrease of the FRET signal. Compared with the intact aptamer, the use of shorter split aptamer fragments increases the possibility of forming G-quadruplex upon target. Thus, the rate of change of FRET signal before and after the addition of target improved significantly and a higher sensitivity (limit of detection (LOD) = 2 nM) was obtained. This strategy is superior in that it is rapid, has low cost and homogeneous detection, and does not need heating to avoid an unfavorable secondary structure of DNA probe. With further efforts, this method could be extended to a universal way for simple and sensitive detection of a variety of biomolecules

Design, Synthesis, and Structure–Activity Relationship Studies of Highly Potent Novel Benzoxazinyl-Oxazolidinone Antibacterial Agents

A series of novel benzoxazinyl-oxazolidinones bearing nonaromatic heterocycle or aryl groups were designed and synthesized. Their in vitro and in vivo antibacterial activities were investigated. Most of the (<b>3</b><i><b>S</b></i>, <b>3a</b><i><b>S</b></i>) biaryl benzoxazinyl-oxazolidinones exhibited potent activity against Gram-positive pathogens. SAR trends were observed; a pyridyl C ring was preferable to other 5- or 6-member aryl C rings, while fluorine substitution on the B ring generated derivatives with reduced activity. Various substituent group positions on the pyridyl ring were also evaluated. The resulting compounds displayed excellent activity against linezolid-resistant strains. Compound <b>45</b> exhibited excellent in vitro activity, with a MIC value of 0.25–0.5 μg/mL against MRSA and an activity against linezolid-resistant strains of 8–16-fold higher potency than linezolid. In a MRSA systemic infection model, compound <b>45</b> displayed an ED₅₀ < 5.0 mg/kg, a potency that is nearly 3-fold better than that of linezolid. This compound also showed excellent pharmacokinetic profiles, with a half-life of more than 5 h as well as an oral bioavailability of 81% in rats

Solubility-Driven Optimization of (Pyridin-3-yl) Benzoxazinyl-oxazolidinones Leading to a Promising Antibacterial Agent

The solubility-driven structural modification of (pyridin-3-yl) benzoxazinyl-oxazolidinones is described, which resulted in the development of a new series of benzoxazinyl-oxazolidinone analogues with high antibacterial activity against Gram-positive pathogens, including that against linezolid-resistant strains and low hERG inhibition. With regard to structure–activity relationship (SAR) trends among the various substituents on the pyridyl ring, relatively small and nonbasic substituents were preferable to sterically demanding or basic substituents. Oxazolidinone ring substitution on the pyridyl ring generated analogues with antibacterial activity superior to imidazolidinone ring. Solubility was enhanced by the incorporation of polar groups, especially when compounds were converted to their prodrugs. Among the prodrugs, compound <b>85</b> exhibited excellent solubility and a good pharmacokinetic profile. In a MRSA systemic infection model, compound <b>85</b> displayed an ED₅₀ = 5.00 mg/kg, a potency that is 2-fold better than that of linezolid

Design, Synthesis, and Structure–Activity Relationship Studies of Novel Thioether Pleuromutilin Derivatives as Potent Antibacterial Agents

A series of novel thioether pleuromutilin derivatives incorporating various heteroaromatic substituents into the C14 side chain have been reported. Structure–activity relationship (SAR) studies resulted in compounds <b>52</b> and <b>55</b> with the most potent in vitro antibacterial activity among the series (MIC = 0.031–0.063 μg/mL). Further optimization to overcome the poor water solubility of compound <b>55</b> resulted in compounds <b>87</b>, <b>91</b>, <b>109</b>, and <b>110</b> possessing good in vitro antibacterial activity with increased hydrophilicity. Compound <b>114</b>, the water-soluble phosphate prodrug of compound <b>52</b>, was also prepared and evaluated. Among the derivatives, compound <b>110</b> showed moderate pharmacokinetic profiles and good in vivo efficacy in both MSSA and MRSA systemic infection models. Compound <b>110</b> was further evaluated in CYP450 inhibition assay and displayed intermediate in vitro inhibition of CYP3A4

Additional file 1: of CLCA1 suppresses colorectal cancer aggressiveness via inhibition of the Wnt/beta-catenin signaling pathway

Patients’ clinical characteristics in IHC, western blotting analysis and ELISA. Table S1. listed patients’ clinical characteristics in IHC experiment and IHC staining results. Table S2. and S3. descripted patients’ clinical characteristics in western blotting analysis and ELISA, respectively. (DOC 62 kb

Additional file 2: of CLCA1 suppresses colorectal cancer aggressiveness via inhibition of the Wnt/beta-catenin signaling pathway

Western blotting images of markers of p53, Wnt, PI3K, NF-kappa B and Ras/MAPK signaling pathway. The results showed that beta-catenin, which is a marker of the Wnt pathway, was downregulated in the CLCA1-ACT transfectants but upregulated in the CLCA1-KO transfectants. (PNG 118 kb

Design, Synthesis, and Structure–Activity Relationship Studies of Highly Potent Novel Benzoxazinyl-Oxazolidinone Antibacterial Agents

A series of novel benzoxazinyl-oxazolidinones bearing nonaromatic heterocycle or aryl groups were designed and synthesized. Their in vitro and in vivo antibacterial activities were investigated. Most of the (<b>3</b><i><b>S</b></i>, <b>3a</b><i><b>S</b></i>) biaryl benzoxazinyl-oxazolidinones exhibited potent activity against Gram-positive pathogens. SAR trends were observed; a pyridyl C ring was preferable to other 5- or 6-member aryl C rings, while fluorine substitution on the B ring generated derivatives with reduced activity. Various substituent group positions on the pyridyl ring were also evaluated. The resulting compounds displayed excellent activity against linezolid-resistant strains. Compound <b>45</b> exhibited excellent in vitro activity, with a MIC value of 0.25–0.5 μg/mL against MRSA and an activity against linezolid-resistant strains of 8–16-fold higher potency than linezolid. In a MRSA systemic infection model, compound <b>45</b> displayed an ED₅₀ < 5.0 mg/kg, a potency that is nearly 3-fold better than that of linezolid. This compound also showed excellent pharmacokinetic profiles, with a half-life of more than 5 h as well as an oral bioavailability of 81% in rats

ICER decreases with rising specificity of FOBT or FOBT+HRFQ: One-way sensitivity analysis.

<p>ICER decreases with rising specificity of FOBT or FOBT+HRFQ: One-way sensitivity analysis.</p

Cost-Effectiveness of Colorectal Cancer Screening Protocols in Urban Chinese Populations

<div><p>Colorectal cancer (CRC) takes a second and fourth position in the incidence and mortality lists respectively among all malignant tumors in urban populations in China. This study was designed to evaluate the cost-effectiveness of two different CRC screening protocols: faecal occult blood test (FOBT) alone, and FOBT plus a high-risk factor questionnaire (HRFQ) as the respective initial screens, followed by colonoscopy. We developed a Markov model to simulate the progression of a cohort of 100,000 average risk asymptomatic individuals moving through a defined series of states between the ages of 40 to 74 years. The parameters used for the modeling came from the CESP (Comparison and Evaluation of Screening Programs for Colorectal Cancer in Urban Communities in China) study and published literature. Eight CRC screening scenarios were tested in the Markov model. The cost-effectiveness of CRC screening under each scenario was measured by an incremental cost-effectiveness ratio (ICER) compared with a scenario without CRC screening. The study revealed that a combined use of FOBT and HRFQ is preferable in CRC screening programs as an initial screening instrument. Annual FOBT+HRFQ screening is recommended for those who have a negative initial result and those who have a positive result but have failed to continue to colonoscopic examination. Repeated colonoscopy (for those with a positive result in initial screening but a negative colonoscopy result) should be performed at a ten-year interval instead of one-year. Such a protocol would cost 7732 Yuan per life year saved, which is the most cost-effective option. In conclusion, the current Chinese Trial Version for CRC Screening Strategy should be revised in line with the most cost-effective protocol identified in this study.</p></div

ICER increases with discount rate: One-way sensitivity analysis.

<p>ICER increases with discount rate: One-way sensitivity analysis.</p