A signal cascade amplification strategy based on RT-PCR triggering of a G-quadruplex DNAzyme for a novel electrochemical detection of viable Cronobacter sakazakii.

Cronobacter sakazakii is an important opportunistic food-borne pathogen, and it can cause severe diseases with main symptoms including neonatal meningitis, necrotizing enterocolitis, and sepsis. For the achievement of practical and convenient detection of viable C. sakazakii, a simple and robust strategy based on the cascade signal amplification of RT-PCR triggered G-quadruplex DNAzyme catalyzed reaction was firstly used to develop an effective and sensitive DNAzyme electrochemical assay. Without viable C. sakazakii in the samples there are no RT-PCR and DNAzyme products, which can cause a weak electrochemical response. Once viable C. sakazakii exists in the samples, an obvious enhancement of the electrochemical response can be achieved after the target signal is amplified by RT-PCR and the resulting DNAzyme, which catalyze the oxidation of 3,3',5,5'-tetramethylbenzidine (TMB) by H2O2 with the assistance of the cofactor hemin. Our novel assay can be performed in a range of 2.4 × 107 CFU mL-1 to 3.84 × 104 CFU mL-1 (R2 = 0.9863), with a detection limit of 5.01 × 102 CFU mL-1. Through the assay of 15 real samples, electrochemical detection assay provided the same results as conventional detection methods. Therefore, detection of viable C. sakazakii based on G-quadruplex DNAzyme electrochemical assay with RT-PCR demonstrates the significant advantages of high sensitivity, low cost and simple manipulation over existing approaches and offers an opportunity for potential application in pathogen detection.

Synthesis of Fluorophores that Target Small Molecules to the Endoplasmic Reticulum of Living Mammalian Cells.

The endoplasmic reticulum (ER) plays critical roles in the processing of secreted and transmembrane proteins. To deliver small molecules to this organelle, we synthesized fluorinated hydrophobic analogues of the fluorophore rhodol. These cell-permeable fluorophores are exceptionally bright, with quantum yields of around 0.8, and they were found to specifically accumulate in the ER of living HeLa cells, as imaged by confocal laser scanning microscopy. To target a biological pathway controlled by the ER, we linked a fluorinated hydrophobic rhodol to 5-nitrofuran-2-acrylaldehyde. In contrast to an untargeted nitrofuran warhead, delivery of this electrophilic nitrofuran to the ER by the rhodol resulted in cytotoxicity comparable to the ER-targeted cytotoxin eeyarestatin I, and specifically inhibited protein processing by the ubiquitin-proteasome system. Fluorinated hydrophobic rhodols are outstanding fluorophores that enable the delivery of small molecules for targeting ER-associated proteins and pathways.

[Retrospective Analysis of Blood Test Results of Volunteer Blood Donors].

OBJECTIVE: To analyze the results of unqualified blood screening among blood donors in Shaoxing region. METHODS: 257 145 blood samples from volunteer blood donors from 2017 to 2021 were tested for HBsAg, HCV, HIV, TP, ALT, HTLV, and NAT. All blood test results were analyzed retrospectively. RESULTS: Over the 5-year period, the average failure rate of the tests for volunteer blood donors was 1.22%. In the descending order from high to low, the positive rates of ALT, HBsAg, NAT, TP, HCV, HIV, HTLV were 0.32%, 0.25%, 0.20%, 0.19%, 0.17%, 0.07%, and 0.01% respecitively. Of these, HBsAg (χ2=65.23), ALT (χ2=47.32), and HCV (χ2=12.73) were significantly different between different years (P <0.05), but TP (χ2=4.19), HIV (χ2=7.58), NAT (χ2=7.62), and HTLV (χ2=6.75) were no significant differences (P >0.05). And the positivity rates of HBsAg and HCV was a trend of decreasing. By comparing nucleic acid and enzyme immunoassay positive tests, the two methods were found to complement each other. The age and gender distribution difference of the positive population could help to better ensure safe blood recruitment. CONCLUSION: It is necessary to strengthen blood testing efforts and continuously pay attention to the changing patterns of positive blood-borne diseases in order to improve blood quality and safety.

Discovery of Potent, Selective, and Orally Available IRE1α Inhibitors Demonstrating Comparable PD Modulation to IRE1 Knockdown in a Multiple Myeloma Model.

The lack of selective and safe in vivo IRE1α tool molecules has limited the evaluation of IRE1α as a viable target to treat multiple myeloma. Focus on improving the physicochemical properties of a literature compound by decreasing lipophilicity, molecular weight, and basicity allowed the discovery of a novel series with a favorable in vitro safety profile and good oral exposure. These efforts culminated in the identification of a potent and selective in vivo tool compound, G-5758, that was well tolerated following multiday oral administration of doses up to 500 mg/kg. G-5758 demonstrated comparable pharmacodynamic effects to induced IRE1 knockdown as measured by XBP1s levels in a multiple myeloma model (KMS-11).

Synthesis of fluorinated benzophenones, xanthones, acridones, and thioxanthones by iterative nucleophilic aromatic substitution.

Fluorination of fluorophores can substantially enhance their photostability and improve spectroscopic properties. To facilitate access to fluorinated fluorophores, bis(2,4,5-trifluorophenyl)methanone was synthesized by treatment of 2,4,5-trifluorobenzaldehyde with a Grignard reagent derived from 1-bromo-2,4,5-trifluorobenzene, followed by oxidation of the resulting benzyl alcohol. This hexafluorobenzophenone was subjected to sequential nucleophilic aromatic substitution reactions, first at one or both of the more reactive 4,4'-fluorines, and second by cyclization through substitution of the less reactive 2,2'-fluorines, using a variety of oxygen, nitrogen, and sulfur nucleophiles, including hydroxide, methoxide, amines, and sulfide. This method yields symmetrical and asymmetrical fluorinated benzophenones, xanthones, acridones, and thioxanthones and provides scalable access to known and novel precursors to fluorinated analogues of fluorescein, rhodamine, and other derivatives. Spectroscopic studies revealed that several of these precursors are highly fluorescent, with tunable absorption and emission spectra, depending on the substituents. This approach should allow access to a wide variety of novel fluorinated fluorophores and related compounds.

Design, synthesis, and structure-activity relationship studies of conformationally restricted mutilin 14-carbamates.

We report herein the design, synthesis, and structure-activity relationship studies of conformationally restricted mutilin 14-carbamates based on the structure of SB-222734. The antibacterial activities of these newly synthesized compounds were also evaluated and compared with linezolid and retapamulin. Results showed that most of the target compounds exhibit good potency in inhibiting the growth of Gram-positive bacteria including Methicillin-susceptible Staphylococcus aureus MSSA (MIC: 0.0625-2µg/mL), Methicillin-resistant S. aureus MRSA (MIC: 0.0625-2µg/mL), Methicillin-susceptible Staphylococcus epidermidis MSSE (MIC: 0.0625-2µg/mL), Methicillin-resistant S. epidermidis MRSE (MIC: 0.0625-2µg/mL), and Streptococcus pneumonia (MIC: 0.0625-4µg/mL). In particular, three remarkable compounds of this series (12l, 12m, and 21l) exhibited comparable in vitro antibacterial profiles to that of retapamulin.

A visual on-site biosensor for low-cost detection of chloramphenicol based on aptamer and split DNAzyme.

Chloramphenicol (CAP) is a kind of broad-spectrum antibiotic, which has been forbidden in food by most countries because of its side effects. In this study, a simple and low-cost biosensor for CAP detection in food was developed. The biosensor consisted of an aptamer specific to CAP and a pair of split probes that could self-assemble as DNAzyme. The detection result could be identified by the naked eye and the visual limit was 10 nM CAP. The absorbance of final reaction products at 417 nm had a linear relationship with the logarithm of the CAP concentration in a range from 10 to 200 nM, and the limit of detection was 87.3 pM. The visual analysis by imageJ also showed a linear detection range between 25 and 200 nM. The entire detection procedure could be completed in about 1.5 h at a cost of about 0.16 dollars per reaction. We believe that the biosensor shows great potential in the rapid and sensitive detection of CAP in food.

Hepatic Arterial Infusion Chemotherapy with Oxaliplatin and 5-Fluorouracil for Advanced Gallbladder Cancer.

PURPOSE: The aim of this study was to assess the safety and efficacy of hepatic arterial infusion chemotherapy (HAIC) with oxaliplatin and 5-fluorouracil for patients with advanced gallbladder cancer (GBC). MATERIALS AND METHODS: Twenty-six patients with advanced GBC, who underwent HAIC with oxaliplatin and 5-fluorouracil from January 2012 to July 2019, were enrolled in this retrospective study. The HAIC regimen consisted of infusions of oxaliplatin at 40 mg/m2 for 2 h, followed by 5-fluorouracil at 800 mg/m2 for 22 h on days 1-3 every 3-4 weeks. A maximum of six cycles of HAIC were applied for tumor control patients followed by maintenance with oral capecitabine or S-1. Overall survival (OS), progression-free survival (PFS), tumor response, and adverse events were investigated. RESULTS: Six of the 26 patients (23.1%) had failed systemic chemotherapy, 8/26 (30.8%) patients had failed various local therapies, and 9/26 (34.6%) patients had contraindications to systemic chemotherapy. The median OS was 13.5 months, and the median PFS was 10.0 months. The overall response rate was 69.2% (18/26), and disease control rate was 92.3% (24/26). Carcinoembryonic antigen (CEA) ≥ 10 U/ml (p = 0.003) and carbohydrate antigen 19-9 (CA19-9) ≥ 200 U/ml (p = 0.000) were independent risk factors for decreased survival. The most frequent Grade 3 or 4 treatment-related adverse event was liver dysfunction (4, 15.4%). CONCLUSION: HAIC with oxaliplatin and 5-fluorouracil is an acceptable and well-tolerated treatment for advanced gallbladder cancer even for patients in whom systemic chemotherapy had failed or is contraindicated. LEVEL OF EVIDENCE: Level 2, Observation Study with Dramatic Effect.

Discovery of Highly Potent and Selective IRAK1 Degraders to Probe Scaffolding Functions of IRAK1 in ABC DLBCL.

MyD88 gene mutation has been identified as one of the most prevalent driver mutations in the activated B-cell-like diffuse large B-cell lymphoma (ABC DLBCL). The published literature suggests that interleukin-1 receptor-associated kinase 1 (IRAK1) is an essential gene for ABC DLBCL harboring MyD88 mutation. Importantly, the scaffolding function of IRAK1, rather than its kinase activity, is required for tumor cell survival. Herein, we present our design, synthesis, and biological evaluation of a novel series of potent and selective IRAK1 degraders. One of the most potent compounds, Degrader-3 (JNJ-1013), effectively degraded cellular IRAK1 protein with a DC50 of 3 nM in HBL-1 cells. Furthermore, JNJ-1013 potently inhibited IRAK1 downstream signaling pathways and demonstrated strong anti-proliferative effects in ABC DLBCL cells with MyD88 mutation. This work suggests that IRAK1 degraders have the potential for treating cancers that are dependent on the IRAK1 scaffolding function.

Assessing IRAK4 Functions in ABC DLBCL by IRAK4 Kinase Inhibition and Protein Degradation.

The interleukin-1 receptor-activated kinase 4 (IRAK4) belongs to the IRAK family of serine/threonine kinases and plays a central role in the innate immune response. However, the function of IRAK4 in tumor growth and progression remains elusive. Here we sought to determine the enzymatic and scaffolding functions of IRAK4 in activated B-cell-like diffuse large B cell lymphoma (ABC DLBCL). We chose a highly selective IRAK4 kinase inhibitor to probe the biological effects of kinase inhibition and developed a series of IRAK4 degraders to evaluate the effects of protein degradation in ABC DLBCL cells. Interestingly, the results demonstrated that neither IRAK4 kinase inhibition nor protein degradation led to cell death or growth inhibition, suggesting a redundant role for IRAK4 in ABC DLBCL cell survival. IRAK4 degraders characterized in this study provide useful tools for understanding IRAK4 protein scaffolding function, which was previously unachievable using pharmacological perturbation.

Water-soluble phosphate prodrugs of pleuromutilin analogues with potent in vivo antibacterial activity against Gram-positive pathogens.

A phosphate prodrug strategy was investigated to address the problem of poor aqueous solubility of pleuromutilin analogues. Water-soluble phosphate prodrugs 6a, 6b and 6c of pleuromutilin analogues were designed and synthesized. Three compounds all exhibited excellent aqueous solubility (>50mg/mL) at near-neutral pH and sufficient stability in buffer solution. In particular, the phenol pleuromutilin prodrug 6c displayed favourable pharmacokinetic profiles and comparable potency with vancomycin against MSSA and MRSA strains in vivo.

Efficient and Scalable Synthesis of 4-Carboxy-Pennsylvania Green Methyl Ester: A Hydrophobic Building Block for Fluorescent Molecular Probes.

Fluorinated fluorophores are valuable tools for studies of biological systems. However, amine-reactive single-isomer derivatives of these compounds are often very expensive. To provide an inexpensive alternative, we report a practical synthesis of 4-carboxy-Pennsylvania Green methyl ester. Derivatives of this hydrophobic fluorinated fluorophore, a hybrid of the dyes Oregon Green and Tokyo Green, are often cell permeable, enabling labeling of intracellular targets and components. Moreover, the low pKa of Pennsylvania Green (4.8) confers bright fluorescence in acidic cellular compartments such as endosomes, enhancing its utility for chemical biology investigations. To improve access to the key intermediate 2,7-difluoro-3,6-dihydroxyxanthen-9-one, we subjected bis-(2,4,5-trifluorophenyl)methanone to iterative nucleophilic aromatic substitution by hydroxide on scales of > 40 g. This intermediate was used to prepare over 15 grams of pure 4-carboxy-Pennsylvania Green methyl ester in 28% overall yield without requiring chromatography. This compound can be converted into the amine reactive N-hydroxysuccinimidyl ester in essentially quantitative yield for the synthesis of a wide variety of fluorescent molecular probes.

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 52 and 55 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 55 resulted in compounds 87, 91, 109, and 110 possessing good in vitro antibacterial activity with increased hydrophilicity. Compound 114, the water-soluble phosphate prodrug of compound 52, was also prepared and evaluated. Among the derivatives, compound 110 showed moderate pharmacokinetic profiles and good in vivo efficacy in both MSSA and MRSA systemic infection models. Compound 110 was further evaluated in CYP450 inhibition assay and displayed intermediate in vitro inhibition of CYP3A4.

Novel acid-activated fluorophores reveal a dynamic wave of protons in the intestine of Caenorhabditis elegans.

Unlike the digestive systems of vertebrate animals, the lumen of the alimentary canal of Caenorhabditis elegans is unsegmented and weakly acidic (pH ~4.4), with ultradian fluctuations to pH > 6 every 45-50 s. To probe the dynamics of this acidity, we synthesized novel acid-activated fluorophores termed Kansas Reds. These dicationic derivatives of rhodamine B become concentrated in the lumen of the intestine of living C. elegans and exhibit tunable pKa values (2.3-5.4), controlled by the extent of fluorination of an alkylamine substituent, that allow imaging of a range of acidic fluids in vivo. Fluorescence video microscopy of animals freely feeding on these fluorophores revealed that acidity in the C. elegans intestine is discontinuous; the posterior intestine contains a large acidic segment flanked by a smaller region of higher pH at the posterior-most end. Remarkably, during the defecation motor program, this hot spot of acidity rapidly moves from the posterior intestine to the anterior-most intestine where it becomes localized for up to 7 s every 45-50 s. Studies of pH-insensitive and base-activated fluorophores as well as mutant and transgenic animals revealed that this dynamic wave of acidity requires the proton exchanger PBO-4, does not involve substantial movement of fluid, and likely involves the sequential activation of proton transporters on the apical surface of intestinal cells. Lacking a specific organ that sequesters low pH, C. elegans compartmentalizes acidity by producing of a dynamic hot spot of protons that rhythmically migrates from the posterior to anterior intestine.

[Genotyping and mutational analysis of occult hepatitis B virus infection in blood donors of Shaoxing].

OBJECTIVE: To assess the molecular biological characteristics of occult hepatitis B virus (HBV) infected blood donors in Shaoxing. METHODS: 8692 blood donors were screened using ELISA. The occult HBV infection was determined by DNA analysis among the HBsAg negative subjects. DNA sequencing and mutational analysis were further performed in the HBV DNA positive samples. The overall situation of occult HBV infection was hereby evaluated and the possible underlying mechanisms discussed. RESULTS: Among the 8644 HBsAg negative subjects out of 8692 blood donors, 8 were HBV DNA positive. The occult HBV infection rate was 0.92 per thousand (8/8692). Among the 8 samples, 6 were genotype C (75%) and 2 genotype B (25%). In addition, a specific mutation in "a" epitope was observed in 7 OBI virus strains by amino acid analysis. CONCLUSION: There were occult HBV infected among blood donors in Shaoxing, which is probably associated with the gene mutation of HBV virus.

[Hepatitis E virus infection in population of non-remunerate blood donors in Shaoxing].

OBJECTIVE: To investigate the incidence of HEV infection in population of non-remunerate blood donors in Shaoxing. METHODS: Blood specimens from 3701 non-remunerate blood donors were collected, ELISA were used to study anti-HEV IgG and IgM antibodies, RT-PCR were further used to study HEV RNA in samples from donors whose anti-HEV IgM was positive. RESULTS: Anti-HEV IgG positive rate was 29.19% (1107/3701), anti-HEV IgM positive rate was 1.35% (50/3701) among non-remunerate blood donors in Shaoxin. Six cases were positive for HEV RNA. The positive rate was 0.16% (6/3701), and all the 6 cases belonged to HEV genotype 1. Different seasons showed no interference on the positive rate of IgG and IgM. CONCLUSION: The detecting and studying of HEV infection among donors was important to ensure the safety of blood products and blood transfusion.