A visible-light-induced bromine radical initiates direct C-H alkylation of heteroaromatics.

Herein, a photoinduced direct C(sp2)-H alkylation of N-heteroaromatics by using commercially available tetrabutylammonium tribromide (TBATB) as a HAT reagent is described. The method uses O2 as the oxidant, and features metal-free, mild reaction conditions and good functional group compatibility.

The Lysine Acetylation Modification in the Porin Aha1 of Aeromonas hydrophila Regulates the Uptake of Multidrug Antibiotics.

Protein lysine acetylation (Kac) modification plays important roles in diverse physiological functions. However, there is little evidence on the role of Kac modification in bacterial antibiotic resistance. Here, we compared the differential expressions of whole-cell proteins and Kac peptides in oxytetracycline sensitive and oxytetracycline resistance (OXYR) strains of Aeromonas hydrophila using quantitative proteomics technologies. We observed a porin family protein Aha1 downregulated in the OXYR strain, which may have an important role in the OXY resistance. Interestingly, seven of eight Kac peptides of Aha1 decreased abundance in OXYR as well. Microbiologic assays showed that the K57R, K187R, and K197R Aha1 mutants significantly increased antibiotic resistance to OXY and reduced the intracellular OXY accumulation in OXY stress. Moreover, these Aha1 mutants displayed multidrug resistance features to tetracyclines and ß-lactam antibiotics. The 3D model prediction showed that the Kac states of K57, K187, and K197 sites located at the extracellular pore vestibule of Aha1 may be involved in the uptake of specific types of antibiotics. Overall, our results indicate a novel antibiotic resistance mechanism mediated by Kac modification, which may provide a clue for the development of antibiotic therapy strategies.

Quantitative Proteomics Reveal the Inherent Antibiotic Resistance Mechanism against Norfloxacin Resistance in Aeromonas hydrophila.

Recently, the prevalence of Aeromonas hydrophila antibiotic-resistant strains has been reported in aquaculture, but its intrinsic antibiotic resistance mechanisms are largely unknown. In the present study, a label-free proteomics technology was used to compare the differential protein abundances in response to norfloxacin (NOR) stress in A. hydrophila. The results showed that there were 186 proteins decreasing and 220 proteins increasing abundances in response to NOR stress. Bioinformatics analysis showed that the differentially expressed proteins were enriched in several biological processes, such as sulfur metabolism and homologous recombination. Furthermore, the antibiotic sensitivity assays showed that the deletion of AHA_0904, cirA, and cysI significantly decreased the resistance against NOR, whereas ΔAHA_1239, ΔcysA, ΔcysD, and ΔcysN significantly increased the resistance against NOR. Our results provide insights into NOR resistance mechanisms and indicate that AHA_0904, cirA, AHA_1239, and sulfur metabolism may play important roles in NOR resistance in A. hydrophila.

Proteomics analysis reveals that CirA in Aeromonas hydrophila is involved in nutrient uptake.

The colicin I receptor (CirA) is a well-studied outer membrane protein that has been reported to play important roles in antibiotic resistance, virulence, and iron homeostasis, although its exact physiological roles require further investigation. In this study, differentially expressed proteins between the ΔahcirA and wild-type (WT) strains of Aeromonas hydrophila were compared using quantitative proteomics. Bioinformatics analysis revealed that the expression of peptide, histidine, and arginine ATP-binding cassette (ABC) transporter system-related proteins was significantly higher in the ΔahcirA strain. Subsequent growth assays revealed that ΔahcirA grew slower than the WT strain in nutrient-limited medium when supplemented with dipeptide, histidine, and arginine as the carbon source. Far-western blot analysis further confirmed that AhCirA can directly bind to histidine/arginine and dipeptide small-molecule substrates in addition to their periplasmic-binding proteins, AhDppA and AhHisJ, respectively. These results indicate that AhCirA may play an important role in the uptake of amino acids and peptides as a channel-forming porin while also directly interacting with ABC transporters to transport nutrient substances into the plasma membrane. Overall, this study demonstrates that AhCirA is a multifunctional protein in A. hydrophila and extends our understanding of known nutrient transport mechanisms among bacteria.

Photoredox Catalysis-Enabled C-H Difluoromethylation of Heteroarenes with Pentacoordinate Phosphorane as the Reagent.

Difluoromethylated heterocyclic compounds have found broad applications in numerous bioactive molecules. Herein, we report photoredox catalysis-induced direct C-H difluoromethylation of heterocycles by using bis(difluoromethyl) pentacoordinate phosphorane (PPh3(CF2H)2, 1) as the reagent. A variety of heterocycles, such as quinoxalin-2(1H)-one, thiophene, indole, and coumarin, are readily tailored with a difluoromethyl group. The method is featured as transition-metal-free by using an organic compound Erythrosin B as the catalyst and O2 as the oxidant.

Quantitative Proteomics Reveals That the Protein Components of Outer Membrane Vesicles (OMVs) in Aeromonas hydrophila Play Protective Roles in Antibiotic Resistance.

In recent years, the intracellular mechanisms that contribute to antibiotic resistance have received increasing attention, and outer membrane vesicles (OMVs) have been reported to be related to antibiotic resistance in several Gram-negative bacterial species. However, the intrinsic molecular mechanisms and the form of such antibiotic resistance are still largely unknown. In this study, OMVs from an oxytetracycline (OXY) sensitive aquatic pathogen, Aeromonas hydrophila (OXY-S), were found with significantly increased OXY resistance. Interestingly, the OXY-resistant strain (OXY-R) had a more protective role in OXY resistance. Therefore, a DIA-based quantitative proteomics analysis was performed to compare the differential expression of OMV proteins between OXY-R (OMVsR) and OXY-S (OMVsS). The results showed that seven proteins increased and five proteins decreased in OMVsR vs OMVsS. A subsequent antibiotics susceptibility assay showed that the deletion of icd, rpsF, and iscS significantly increased OXY sensitivity. Moreover, the exogenous addition of the crude OMV fractions of overexpressed recombinant proteins in E. coli with rRpsF, rIcd, rIscS, rOmpA, rPepA, rFrdA, and rRplQ demonstrated that these proteins promoted the OXY resistance of A. hydrophila. Overall, our results indicate the important protective role of OMVs in antibiotic resistance in A. hydrophila and provide novel insights on bacterial antibiotic resistance mechanisms.

Targeting entry into mitochondria for increased anticancer efficacy of BCL-XL-selective inhibitors in lung cancer.

The BCL-XL-selective inhibitors exhibit potential clinical application value when combined with chemotherapeutic drugs for the treatment of solid tumors. However, their efficacy in these settings is still low when treated with BCL-XL inhibitors alone in solid tumors. The mechanism responsible for the poor efficacy remains unclear. We show here that unable to interact with target of BCL-XL-selective inhibitors caused by invalid entry into mitochondria is essential for their inefficacy in solid tumors. We demonstrated in non-small-cell lung cancer (NSCLC) cells that the instability of A-1155463 in cells as well as invalid entry into mitochondria of A-1331852, two BCL-XL-selective inhibitors, accounted for their off-target problems. Furthermore, we found that a mitochondria-targeted, non-toxic small molecule NA-2a improved the on-target effect of A-1331852 to enhance its apoptotic regulatory activity, thereby increasing its anticancer activity in NSCLC. Our results indicated that NA-2a was selectively enriched in mitochondria transported by organic-anion-transporting polypeptide (OATP) transporters, which altered the permeability of the mitochondrial membrane, thereby promoting the entrance of A-1331852 to mitochondria and enhancing its disruption of the BIM-BCL-XL complex, which finally led to the increased anticancer activity in vitro and in vivo. Collectively, our data provided overwhelming evidence that the combination of NA-2a and A-1331852 could be used as a promising synergistic therapeutic agent in NSCLC therapy.

Preparation of Yellow Fluorescent N,O-CDs and its Application in Detection of ClO.

Accurate and efficient detection of ClO- was extremely important due to the harm of ROS in the environment and organism. In this paper, yellow fluorescent N,O-CDs were successfully prepared by the solvothermal method. The microscopic size of the N,O-CDs was approximately spherical with an average particle size of 4.8 ± 0.8 nm. The fluorescence quantum yield in ethanol solution was calculated as 10.5 % using fluorescein as the standard reference. The as-fabricated N,O-CDs had high sensitivity and low detection limit (7.5 µM) for quantitatively detecting ClO- with a linear range from 0.07 mM to 0.16 mM. The probe not only shows good selectivity and anti-interference to metal ions, anions and amino acids but also has excellent light stability and thermal stability. Also, a wide selection range for pH was demonstrated.

Combined fenestrated/chimney thoracic endovascular repair for the treatment of blunt traumatic aortic injury: A case report.

Blunt traumatic thoracic aortic injury (BTAI) is an extremely serious medical condition with a high rate of associated mortality. Recent advances in techniques such as thoracic endovascular repair offer new opportunities to manage the critical BTAI patients in an efficacious yet less invasive manner. A 65 year-old-male suffered from multiple injuries after a fall, including BTAI in the aortic arch, which resulted in dissection of the descending thoracic-abdominal aorta and iliac artery, development of an intimal flap in the left common carotid artery, and dissection of the left subclavian artery. Based on the imaging information of this patient and our clinical experience, the combined treatment of fenestrated thoracic endovascular repair and a chimney technique was immediately planned to fully repair these dissections and moreover prevent further dissection of the branching vessels, additionally to ensure sufficient blood flow in the left subclavian artery and left common carotid artery. The intervention yielded satisfactory early outcomes. Follow-up assessment at six months reported no symptoms or complications associated with the stent-graft. Computed tomography angiography further confirmed adequate stent-graft coverage of the aortic injury.

Tanshinone IIA alleviates brain damage in a mouse model of neuromyelitis optica spectrum disorder by inducing neutrophil apoptosis.

BACKGROUND: Neuromyelitis optica spectrum disorder (NMOSD), an autoimmune astrocytopathic disease associated with the anti-aquaporin-4 (AQP4) antibody, is characterized by extensive necrotic lesions primarily located on the optic nerves and spinal cord. Tanshinone IIA (TSA), an active natural compound extracted from Salvia miltiorrhiza Bunge, has profound immunosuppressive effects on neutrophils. OBJECTIVE: The present study aimed to evaluate the effect of TSA on NMOSD mice and explore the underlying mechanisms. Mice were initially administered TSA (pre-TSA group, n = 20) or vehicle (vehicle group, n = 20) every 8 h for 3 days, and then NMOSD model was induced by intracerebral injection of NMOSD-immunoglobulin G (NMO-IgG) and human complement (hC). In addition, post-TSA mice (n = 10) were administered equal dose of TSA at 8 h and 16 h after model induction. At 24 h after intracerebral injection, histological analysis was performed to assess the inhibitory effects of TSA on astrocyte damage, demyelination, and neuroinflammation in NMOSD mice, and western blotting was conducted to clarify the effect of TSA on the NF-κB and MAPK signaling pathways. Furthermore, flow cytometry and western blotting were conducted to verify the proapoptotic effects of TSA on neutrophils in vitro. RESULTS: There was a profound reduction in astrocyte damage and demyelination in the pre-TSA group and post-TSA group. However, prophylactic administration of TSA induced a better effect than therapeutic treatment. The number of infiltrated neutrophils was also decreased in the lesions of NMOSD mice that were pretreated with TSA. We confirmed that prophylactic administration of TSA significantly promoted neutrophil apoptosis in NMOSD lesions in vivo, and this proapoptotic effect was mediated by modulating the caspase pathway in the presence of inflammatory stimuli in vitro. In addition, TSA restricted activation of the NF-κB signaling pathway in vivo. CONCLUSION: Our data provide evidence that TSA can act as a prophylactic agent that reduces NMO-IgG-induced damage in the mouse brain by enhancing the resolution of inflammation by inducing neutrophil apoptosis, and TSA may serve as a promising therapeutic agent for neutrophil-associated inflammatory disorders, such as NMOSD.

Carbon-dot-based ratiometric fluorescent probe of intracellular zinc ion and persulfate ion with low dark toxicity.

Metal ions and anions play significant roles in biological systems and industrial processes, therefore it is important to develop good fluorescent probes to detect metal ions and anions. Here, N,O-co-doped carbon quantum dots (CDs) that could detect Zn2+ via a ratiometric fluorescence method were fabricated. The reaction between the as-prepared CDs and zinc acetate gave the composite CDs-Zn, in which fluorescence changed ratiometrically upon addition of S2 O8 2- . With change in excitation light, the emission peaks of the CDs and CDs-Zn were kept fixed while intensity changed. CDs and CDs-Zn exhibited good photostability, thermal stability, selectivity, and strong anti-interference ability. In addition, CDs and CDs-Zn displayed low dark toxicity under physiological temperatures. Ratiometric fluorescence imaging of intracellular Zn2+ and S2 O8 2- was carried out in living HeLa cells for both of these probes. Compared with reported ratiometric fluorescent hybrid nanosensors based on organic dyes and inorganic nanomaterials, the as-prepared CDs and CDs-Zn had low toxicity, and were easy to synthesize.

Association between work-family conflict and overall well-being among Chinese nurse leaders.

AIM: To explore the association between work-family conflict and overall well-being among Chinese nurse leaders. BACKGROUND: Nurse leaders are constantly busy at the clinical frontline, mostly experience high stress levels at work and have little time to spend with the family. There is little evidence to know about the association between work-family conflict and overall well-being, which is essential for high-quality medical care. METHODS: A cluster sampling method was used to recruit 42 nurse leaders. Data were collected using the Chinese versions of the Multidimensional Work-Family Conflict Scale and the General Well-Being Schedule. Descriptive analyses, independent t tests, ANOVAs and Pearson's correlation were used for the statistical analysis. RESULTS: The mean scores (SD) of work-family conflict and well-being were 2.17 (0.57) and 4.51 (0.61), respectively. Negative correlations were observed with strain-based and behaviour-based work-family conflict and overall well-being. CONCLUSION: Stress from work-family conflict is positively correlated with the overall well-being of Chinese nurse leaders. IMPLICATIONS FOR NURSING MANAGEMENT: Hospital administrators should be aware of specific risk factors and implement accordingly the interventional strategies to decrease the stress levels and improve the overall well-being of nurse leaders.

Mitochondrion-Targeting Identification of a Fluorescent Apoptosis-Triggering Molecule by Mass Spectrometry Elucidates Drug Tracking.

The real-time tracking of localization and dynamics of small molecules in organelles helps to understand their function and identification of their potential targets at subcellular resolution. To identify the mitochondrion-targeting effects of small molecules (NA-17 and NA-2a) in cancer cells, we used mass spectrometry to study their distribution and accumulation in mitochondria and in the surrounding cytoplasm thus enabling tracing of action processes of therapeutic compounds. Colocalization analysis with the aid of imaging agents suggests that both NA-17 and NA-2a display mitochondrion-targeting effects. However, MS analysis reveals that only NA-2a displays both a mitochondrion-targeting effect and an accumulation effect, whereas NA-17 only distributes in the surrounding cytoplasm. A combination of mitochondrion imaging, immunoblotting, and MS analysis in mitochondria indicated that NA-17 neither has the ability to enter mitochondria directly nor displays any mitochondrion-targeting effect. Further studies revealed that NA-17 could not enter into mitochondria even when the mitochondrial permeability in cells changed after NA-17 treatment, as was evident from reactive oxygen species (ROS) generation and cytochrome c release. In the process of cellular metabolism, NA-17 itself is firmly restricted to the cytoplasm during the metabolic process, but its metabolites containing fluorophores could accumulate in mitochondria for cell imaging. Our studies have furnished new insights into the drug metabolism processes.

Characterization, expression profiling and functional characterization of cathepsin Z (CTSZ) in turbot (Scophthalmus maximus L.).

Cathepsin Z (CTSZ) is a lysosomal cysteine protease of the papain superfamily. It participates in the host immune defense via phagocytosis, signal transduction, cell-cell communication, proliferation, and migration of immune cells such as monocytes, macrophages, and dendritic cells. In this study, we reported the identification of SmCTSZ, a CTSZ homolog from turbot (Scophthalmus maximus L.). SmCTSZ was 317 residues in length and contains a Pept-C1 domain. In multiple species comparison, SmCTSZ shared 65-93% overall sequence identities with the CTSZ counterparts from human, rat, and several fish species. In the phylogenetic analysis, SmCTSZ showed the closest relationship to Cynoglossus semilaevis. The syntenic analysis revealed the similar neighboring genes of CTSZ across all the selected species, which suggested the synteny encompassing CTSZ region during vertebrate evolution. Subsequently, SmCTSZ was constitutively expressed in various tissues, with the lowest and highest levels in brain and intestine respectively. In addition, SmCTSZ was significantly up-regulated in intestine following both Gram-negative bacteria Vibrio anguillarum, and Gram-positive bacteria Streptococcus iniae immersion challenge. Finally, the rSmCTSZ showed strong binding ability to all the examined microbial ligands, and the agglutination effect to different bacteria. Taken together, these results indicated SmCTSZ could play important roles in mucosal immune response in the event of bacterial infection in teleost. However, the knowledge of CTSZ are still limited in teleost species, further studies should be carried out to better characterize its detailed roles in teleost mucosal immunity.

Radio Frequency Fingerprint-Based Intelligent Mobile Edge Computing for Internet of Things Authentication.

In this paper, a light-weight radio frequency fingerprinting identification (RFFID) scheme that combines with a two-layer model is proposed to realize authentications for a large number of resource-constrained terminals under the mobile edge computing (MEC) scenario without relying on encryption-based methods. In the first layer, signal collection, extraction of RF fingerprint features, dynamic feature database storage, and access authentication decision are carried out by the MEC devices. In the second layer, learning features, generating decision models, and implementing machine learning algorithms for recognition are performed by the remote cloud. By this means, the authentication rate can be improved by taking advantage of the machine-learning training methods and computing resource support of the cloud. Extensive simulations are performed under the IoT application scenario. The results show that the novel method can achieve higher recognition rate than that of traditional RFFID method by using wavelet feature effectively, which demonstrates the efficiency of our proposed method.

Clustering Based Physical-Layer Authentication in Edge Computing Systems with Asymmetric Resources.

In this paper, we propose a clustering based physical-layer authentication scheme (CPAS) to overcome the drawback of traditional cipher-based authentication schemes that suffer from heavy costs and are limited by energy-constrained intelligent devices. CPAS is a novel cross-layer secure authentication approach for edge computing system with asymmetric resources. The CPAS scheme combines clustering and lightweight symmetric cipher with physical-layer channel state information to provide two-way authentication between terminals and edge devices. By taking advantage of temporal and spatial uniqueness in physical layer channel responses, the non-cryptographic physical layer authentication techniques can achieve fast authentication. The lightweight symmetric cipher initiates user authentication at the start of a session to establish the trust connection. Based on theoretical analysis, the CPAS scheme is secure and simple, but there is no trusted party, while it can also resist small integer attacks, replay attacks, and spoofing attacks. Besides, experimental results show that the proposed scheme can boost the total success rate of access authentication and decrease the data frame loss rate, without notable increase in authentication latencies.

Multifloroside Suppressing Proliferation and Colony Formation, Inducing S Cell Cycle Arrest, ROS Production, and Increasing MMP in Human Epidermoid Carcinoma Cell Lines A431.

Multifloroside (4), together with 10-hydroxyoleoside 11-methyl ester (1), 10-hydroxyoleoside dimethyl ester (2), and 10-hydroxyligustroside (3), are all secoiridoids, which are naturally occurring compounds that possess a wide range of biological and pharmacological activities. However, the anti-cancer activity of 1-4 has not been evaluated yet. The objective of this work was to study the anti-cancer activities of 1-4 in the human epidermoid carcinoma cell lines A431 and the human non-small cell lung cancer (NSCLC) cell lines A549. The results indicate that 1-4 differ in potency in their ability to inhibit the proliferation of human A431 and A549 cells, and multifloroside (4) display the highest inhibitory activity against A431 cells. The structure-activity relationships suggest that the o-hydroxy-p-hydroxy-phenylethyl group may contribute to the anti-cancer activity against A431 cells. Multifloroside treatment can also inhibit cell colony formation, arrest the cell cycle in the S-phase, increase the levels of reactive-oxygen-species (ROS), and mitochondrial membrane potential (MMP), but it did not significantly induce cell apoptosis at low concentrations. The findings indicated that multifloroside (4) has the tendency to show selective anti-cancer effects in A431 cells, along with suppressing the colony formation, inducing S cell cycle arrest, ROS production, and increasing MMP.

Establishment and application of an indirect ELISA for porcine circovirus 3.

Porcine circovirus type 3 (PCV3) was initially reported in 2016 in the United States of America. Since then, the virus has been detected on swine farms in Poland, South Korea, and China using PCR. However, a serological survey of PCV3 in pig populations has never been conducted. In this study, for the first time, we established an indirect enzyme-linked immunosorbent (ELISA) assay and performed a national retrospective serological survey for PCV3. Our results showed that the PCV3-postive rate increased from 22.35% to 51.88% between 2015 and 2017. The above results suggest PCV3 has spread widely in China with increased positive rates since 2015.

Characterization and expression analysis of chitinase genes (CHIT1, CHIT2 and CHIT3) in turbot (Scophthalmus maximus L.) following bacterial challenge.

Chitinases are hydrolytic enzymes which have been employed to breakdown chitin coats of pathogenic microorganisms, thereby weaken the defense system of several pathogens and insects. In this regard, we identified the chitinase genes of turbot and characterized their expression patterns in mucosal tissues following Vibrio anguillarum and Streptococcus iniae challenge. In present study, transcripts of three chitinase genes (CHIT1, CHIT2 and CHIT3) were captured, as well as their protein structures and expression patterns following different bacterial infection were also characterized. The chitinases were widely expressed in all tested tissues with the highest expression levels of CHIT1 and CHIT2 in intestine, and CHIT3 in skin. Finally, these three genes showed different expression patterns following bacterial challenge. The significant quick induction of chitinases in mucosal surfaces against infection indicated their key roles to prevent pathogen attachment and entry in mucosal immunity. Functional studies should further characterize the chitinases and avail utilization of their function to increase the disease resistance in maintaining the integrity of the mucosal barriers against infection and facilitating the disease resistant family/strain selection in turbot.

The involvement of cathepsin F gene (CTSF) in turbot (Scophthalmus maximus L.) mucosal immunity.

Cathepsin F (CTSF) is a recently described papain-like cysteine protease and unique among cathepsins due to an elongated N-terminal pro-region, which contains a cystatin domain. CTSF likely plays a regulatory role in processing the invariant chain which is associated with the major histocompatibility complex (MHC) class II. In this regard, we identified the CTSF gene of turbot as well as its protein structure, phylogenetic relationships, and expression patterns in mucosal tissues following Vibrio anguillarum and Streptococcus iniae challenge. We also determined the expression patterns of CTSF in mucosal tissues after vaccinated with the formalin-inactivated V. vulnificus whole-cell vaccine. Briefly, turbot CTSF gene showed the closest relationship with that of Paralichthys olivaceus in phylogenetic analysis. And CTSF was ubiquitously expressed in all tested tissues with the highest expression level in gill. In addition, CTSF gene showed different expression patterns following different bacterial challenge. The significant quick regulation of CTSF in mucosal surfaces against infection indicated its roles in mucosal immunity. Functional studies should further characterize avail utilization of CTSF function to increase the disease resistance of turbot in maintaining the integrity of the mucosal barriers against infection and to facilitate selection of the disease resistant family/strain in turbot.