A Novel CCK Receptor GPR173 Mediates Potentiation of GABAergic Inhibition.

Cholecystokinin (CCK) enables excitatory circuit long-term potentiation (LTP). Here, we investigated its involvement in the enhancement of inhibitory synapses. Activation of GABA neurons suppressed neuronal responses in the neocortex to a forthcoming auditory stimulus in mice of both sexes. High-frequency laser stimulation (HFLS) of GABAergic neurons potentiated this suppression. HFLS of CCK interneurons could induce the LTP of their inhibition toward pyramidal neurons. This potentiation was abolished in CCK knock-out mice but intact in mice with both CCK1R and 2R knockout of both sexes. Next, we combined bioinformatics analysis, multiple unbiased cell-based assays, and histology examinations to identify a novel CCK receptor, GPR173. We propose GPR173 as CCK3R, which mediates the relationship between cortical CCK interneuron signaling and inhibitory LTP in the mice of either sex. Thus, GPR173 might represent a promising therapeutic target for brain disorders related to excitation and inhibition imbalance in the cortex.SIGNIFICANCE STATEMENT CCK, the most abundant and widely distributed neuropeptide in the CNS, colocalizes with many neurotransmitters and modulators. GABA is one of the important inhibitory neurotransmitters, and much evidence shows that CCK may be involved in modulating GABA signaling in many brain areas. However, the role of CCK-GABA neurons in the cortical microcircuits is still unclear. We identified a novel CCK receptor, GPR173, localized in the CCK-GABA synapses and mediated the enhancement of the GABA inhibition effect, which might represent a promising therapeutic target for brain disorders related to excitation and inhibition imbalance in the cortex.

Impact of LuxS on virulence and pathogenicity in Klebsiella pneumoniae exhibiting varied mucoid phenotypes.

How the LuxS/AI-2 quorum sensing (QS) system influences the pathogenicity of K. pneumoniae is complicated by the heterogeneity of the bacterial mucoid phenotypes. This study aims to explore the LuxS-mediated regulation of the pathogenicity of K. pneumoniae with diverse mucoid phenotypes, including hypermucoid, regular-mucoid, and nonmucoid. The wild-type, luxS knockout, and complemented strains of three K. pneumoniae clinical isolates with distinct mucoid phenotypes were constructed. The results revealed the downregulation of virulence genes of regular-mucoid, and nonmucoid but not hypermucoid strains. The deletion of luxS reduced the pathogenicity of the regular-mucoid, and nonmucoid strains in mice; while in hypermucoid strain, luxS knockout reduced virulence in late growth but enhanced virulence in the early growth phase. Furthermore, the absence of luxS led the regular-mucoid and nonmucoid strains to be more sensitive to the host cell defense, and less biofilm-productive than the wild-type at both the low and high-density growth state. Nevertheless, luxS knockout enhanced the resistances to adhesion and phagocytosis by macrophage as well as serum-killing, of hypermucoid K. pneumoniae at its early low-density growth state, while it was opposite to those in its late high-density growth phase. Collectively, our results suggested that LuxS plays a crucial role in the pathogenicity of K. pneumoniae, and it is highly relevant to the mucoid phenotypes and growth phases of the strains. LuxS probably depresses the capsule in the early low-density phase and promotes the capsule, biofilm, and pathogenicity during the late high-density phase, but inhibits lipopolysaccharide throughout the growth phase, in K. pneumoniae.IMPORTANCECharacterizing the regulation of physiological functions by the LuxS/AI-2 quorum sensing (QS) system in Klebsiella pneumoniae strains will improve our understanding of this important pathogen. The genetic heterogeneity of K. pneumoniae isolates complicates our understanding of its pathogenicity, and the association of LuxS with bacterial pathogenicity has remained poorly addressed in K. pneumoniae. Our results demonstrated strain and growth phase-dependent variation in the contributions of LuxS to the virulence and pathogenicity of K. pneumoniae. Our findings provide new insights into the important contribution of the LuxS/AI-2 QS system to the networks that regulate the pathogenicity of K. pneumoniae. Our study will facilitate our understanding of the regulatory mechanisms of LuxS/AI-2 QS on the pathogenicity of K. pneumoniae under the background of their genetic heterogeneity and help develop new strategies for diminished bacterial virulence within the clinical K. pneumoniae population.

Host immunity involvement in the outcome of phage therapy against hypervirulent Klebsiella pneumoniae infections.

Highly encapsulated hypervirulent Klebsiella pneumoniae (hvKp) causes severe infections. Bacteriophage therapy, an antibiotic alternative, effectively treats bacterial infections. Phage φFK1979 encoding polysaccharide depolymerases can target and disarm the capsule of hvKp FK1979, showing promise against FK1979 infection. Resistant strains induced by φFK1979 are possibly eliminated by host immunity and new phage phiR3 targeting them. We constructed varied immunocompromised FK1979 infection mouse models to assess the therapy efficacy of φFK1979 alone or in combination with phiR3. Survival rates, bacterial loads, histopathology, inflammation, and immune cell distribution of mice were studied. Prompt and adequate administration of φFK1979, rather than phiR3, significantly improved survival rates in mice with different immune statuses. However, immunocompromised mice showed lower efficacy due to reduced tolerance to low-virulence φFK1979-resistant bacteria compared to immunocompetent mice. Adding phiR3 sequentially greatly enhanced therapy efficacy for them, leading to increased survival rates and notable improvements in pathology and inflammation. Immunocompetent mice exhibited the most favorable response to φFK1979 monotherapy, as their immune system cleared φFK1979-resistant bacteria while avoiding a robust response to phiR3 combating φFK1979-resistant bacteria. This study revealed host immunity involvement in the outcome of phage therapy against infections and introduced, for the first time, personalized phage therapy strategies for hvKp-infected mice with varying immune statuses.IMPORTANCEHypervirulent Klebsiella pneumoniae (hvKp), with high capsular polysaccharide production, can cause severe invasive infections. Capsule-targeting phage poses the potential to fight against hvKp. We previously elucidated that the capsule-targeting phage induces resistance in hvKp, while phage-resistant strains exhibit sensitivity to host innate immunity and new phages targeting them. This indicated that phage-resistant strains can be eliminated by the immune system in immunocompetent patients, whereas they may require treatment with phages targeting resistant bacteria in immunocompromised patients. HvKp can infect individuals with varying immune statuses, including both immunocompetent and immunocompromised/deficient patients. This study, for the first time, developed personalized phage therapy strategies for hvKp-infected mice with different immune statuses, optimizing phage therapy against hvKp infections. This research is expected to provide a theoretical foundation and novel insights for clinical phage therapy against hvKp infections, offering significant societal benefits and clinical value.

Preparation and anti-tumor activity of paclitaxel silk protein nanoparticles encapsulated by biofilm.

To address the disadvantages of poor water solubility, cardiotoxicity, and hypersensitivity reactions of paclitaxel (PTX). In this study, paclitaxel silk fibroin nanoparticles (PTX-SF-NPs) were prepared by self-assembly method, and then, the nanoparticles were encapsulated by using the outer membrane vesicles of Escherichia coli (E. coil), so that biofilm-encapsulated paclitaxel silk fibroin nanoparticles (OMV-PTX-SF-NPs) were constructed. Subsequently, the prepared nanoparticles were characterized in terms of particle size and zeta potential, and in vitro cytotoxicity studies were carried out, which showed that both PTX-SF-NPs and OMV-PTX-SF-NPs possessed good antitumor activity against tumor cells. In the in vivo biodistribution study and antitumor study, the results showed that OMV-PTX-SF-NPs could effectively increase the bioavailability of paclitaxel, prolong the action time of paclitaxel in vivo, reduce the absorption of paclitaxel in the stomach, increase the concentration of paclitaxel in tumor tissues, and significantly inhibit the growth of tumors. Overall, OMV-PTX-SF-NPs is a stable extended-release oral formulation of paclitaxel, which can effectively improve the bioavailability of paclitaxel, enhance the anti-tumor activity and reduce the adverse reactions.

Ceftazidime-Decorated Gold Nanoparticles: a Promising Strategy against Clinical Ceftazidime-Avibactam-Resistant Enterobacteriaceae with Different Resistance Mechanisms.

Nanoparticle-based antibiotic delivery systems are essential in combating antibiotic-resistant bacterial infections arising from acquired resistance and/or biofilm formation. Here, we report that the ceftazidime-decorated gold nanoparticles (CAZ_Au NPs) can effectively kill clinical ceftazidime-avibactam-resistant Enterobacteriaceae with various resistance mechanisms. Further study of underlying antibacterial mechanisms suggests that CAZ_Au NPs can damage the bacterial cell membrane and increase the level of intracellular reactive oxygen species. Moreover, CAZ_Au NPs show great potential in inhibiting biofilm formation and eradicating mature biofilms via crystal violet and scanning electron microscope assays. In addition, CAZ_Au NPs demonstrate excellent performance in improving the survival rate in the mouse model of abdominal infection. In addition, CAZ_Au NPs show no significant toxicity at bactericidal concentrations in the cell viability assay. Thus, this strategy provides a simple way to drastically improve the potency of ceftazidime as an antibiotic and its use in further biomedical applications.

Study of Combined Effect of Bacteriophage vB3530 and Chlorhexidine on the Inactivation of Pseudomonas aeruginosa.

BACKGROUND: Chlorhexidine (CHG) is a disinfectant commonly used in hospitals. However, it has been reported that the excessive use of CHG can cause resistance in bacteria to this agent and even to other clinical antibiotics. Therefore, new methods are needed to alleviate the development of CHG tolerance and reduce its dosage. This study aimed to explore the synergistic effects of CHG in combination with bacteriophage against CHG-tolerant Pseudomonas aeruginosa (P. aeruginosa) and provide ideas for optimizing disinfection strategies in clinical environments as well as for the efficient use of disinfectants. METHODS: The CHG-tolerant P. aeruginosa strains were isolated from the First Affiliated Hospital of Wenzhou Medical University in China. The bacteriophage vB3530 was isolated from the sewage inlet of the hospital, and its genome was sequenced. Time-killing curve was used to determine the antibacterial effects of vB3530 and chlorohexidine gluconate (CHG). The phage sensitivity to 16 CHG-tolerant P. aeruginosa strains and PAO1 strain was detected using plaque assay. The emergence rate of resistant bacterial strains was detected to determine the development of phage-resistant and CHG-tolerant strains. Finally, the disinfection effects of the disinfectant and phage combination on the surface of the medical devices were preliminarily evaluated. RESULTS: The results showed that (1) CHG combined with bacteriophage vB3530 significantly inhibited the growth of CHG-resistant P. aeruginosa and reduced the bacterial colony forming units (CFUs) after 24 h. (2) The combination of CHG and bacteriophage inhibited the emergence of phage-resistant and CHG-tolerant strains. (3) The combination of CHG and bacteriophage significantly reduced the bacterial load on the surface of medical devices. CONCLUSIONS: In this study, the combination of bacteriophage vB3530 and CHG presented a combined inactivation effect to CHG-tolerant P. aeruginosa and reduced the emergence of strains resistant to CHG and phage. This study demonstrated the potential of bacteriophage as adjuvants to traditional disinfectants. The use of bacteriophage in combination with commercial disinfectants might be a promising method for controlling the spread of bacteria in hospitals.

A newly isolated bacteriophage vB8388 and its synergistic effect with aminoglycosides against multi-drug resistant Klebsiella oxytoca strain FK-8388.

The bacteriophage vB8388 can lyse multi-drug resistant Klebsiella oxytoca strain FK-8388 and maintain stability in a wide range of temperatures (from 4 °C to 80 °C) and pHs (3-11). Bioinformatics analysis showed that vB8388 is a linear double-stranded DNA virus that is 39,750 long with 50.65% G + C content and 44 putative open reading frames (ORFs). Phage vB8388 belongs to the family Autographviridae and possesses a non-contractile tail. The latency period of vB8388 was approximately 20 min. The combination of phage vB8388 and gentamicin, amikacin, or tobramycin could effectively inhibit the growth of K. oxytoca strain FK-8388, with a decrease of more than 4 log units within 12 h in vitro. Phage vB8388 showed a strong synergistic effect with gentamicin that could enhance the anti-biofilm effect of vB8388. The phage + gentamicin combination also showed synergy in vivo in the larval infection model of Galleria mellonella. In conclusion, the findings of this study suggest the potential of phage + antibiotic combination therapy to be used as an alternative therapeutic approach for treating infectious diseases caused by multidrug-resistant bacteria.

Bacterial outer membrane vesicles-cloaked modified zein nanoparticles for oral delivery of paclitaxel.

To improve the aqueous solubility and oral bioavailability of paclitaxel (PTX), a biomimetic system for oral administration of PTX was efficiently developed as an outer membrane vesicle (OMVs) of sodium caseinate (CAS) modified zein nanoparticles (OMVs-Zein-CAS-PTX-NPs) by Escherichia coli. To verify their structure and properties, the designed nanostructures were thoroughly characterized using various characterization techniques. The results indicated that hydrogen bonds and van der Waals forces mainly drove the interaction between PTX and Zein, but the complex is unstable. The physicochemical stability of PTX-loaded zein nanoparticles was improved by the addition of CAS. The biological characteristics of biofilms are reproduced by nanoparticles cloaked with outer membrane vesicles. OMVs-Zein-CAS-PTX-NPs delayed the release of PTX under simulated gastric and intestinal fluids due to OMVs protection. OMVs-Zein-CAS-PTX-NPs exhibited remarkable antitumor ability in vitro and improved the bioavailability of oral administration of PTX in vivo. Therefore, OMVs cloaked in nanoparticles may be a suitable delivery vehicle to provide an efficient application prospect for the oral administration of PTX.

Rapid ResaCeftazidime-Avibactam Enterobacterales NP Test: Rapid Detection of Ceftazidime-Avibactam Susceptibility in Enterobacterales.

Ceftazidime-avibactam (CZA), a novel ß-lactam/ß-lactamase inhibitor combination, has good antibacterial activity against carbapenem-resistant Enterobacterales (CRE) producing class A and C and some class D carbapenemases, but in recent years, the emergence of CZA-resistant Enterobacterales bacteria is growing. Therefore, rapid, accurate, and timely detection of CZA is necessary for clinical anti-infection treatment. In this study, the rapid ResaCeftazidime-avibactam Enterobacterales NP test was developed; its principle is that metabolically active bacteria (CZA-resistant strains) can change resazurin-PrestoBlue, a viability colorant, from blue to purple or pink in the presence of CZA, whereas CZA-susceptible strains cannot. We used 178 Enterobacterales isolates to evaluate the performance of this test. This test allowed the susceptibility of Enterobacterales to CZA to be detected within 4.5 h with an overall performance of 96% category agreement (CA), 7% major errors (MEs), and 0% very major errors (VMEs). Performance for Escherichia coli included 100% CA and 0% MEs and VMEs. Performance for Klebsiella pneumoniae included 99% CA and 2% MEs and 0% VMEs. Performance for Enterobacter cloacae included 87% CA, 25% MEs, and 0% VMEs. Moreover, this test is both economical ($1.0106 per isolate) and convenient, as it only requires basic laboratory equipment. In a word, the rapid ResaCeftazidime-avibactam Enterobacterales NP test is rapid and feasible, which may provide certain backing for the rapid screening and timely treatment of CZA-resistant strains in the clinic.

Evaluation of the antibacterial, antibiofilm, and anti-virulence effects of acetic acid and the related mechanisms on colistin-resistant Pseudomonas aeruginosa.

BACKGROUND: Pseudomonas aeruginosa (P. aeruginosa) has been majorly implicated in the infection of burns, wounds, skin, and respiratory tract. Colistin is considered the last line of defense against P. aeruginosa infections. However, colistin is becoming increasingly invalid in treating patients infected with colistin-resistant (COL-R) P. aeruginosa. As one of the disinfectants used for wound infections, acetic acid (AA) offers good antibacterial and antibiofilm activities against P. aeruginosa. This study investigated the effects of AA on COL-R P. aeruginosa in terms of its antibacterial, antibiofilm, and anti-virulence properties and the corresponding underlying mechanisms. RESULTS: The antimicrobial susceptibility and growth curve data revealed that 0.078% (v/v) AA exhibited good antibacterial activity against COL-R P. aeruginosa. Subinhibitory concentrations of AA were ineffective in inhibiting biofilm formation, but 4 × and 8 × of the minimum inhibitory concentration (MIC) was effective in removing the preformed biofilms in biofilm-eradication assays. The virulence results illustrated that AA inhibited COL-R P. aeruginosa swimming, swarming, twitching, and pyocyanin and elastase production. The analysis of the potential antibacterial mechanisms of AA on COL-R P. aeruginosa revealed that AA acted by increasing the outer and inner membrane permeability, polarizing the membrane potential, and decreasing the reduction potential in a concentration-dependent manner. The qRT-PCR results revealed that AA may inhibit the virulence of COL-R P. aeruginosa by inhibiting the expression of T3SS-related and QS-related genes. CONCLUSIONS: AA possesses antibacterial, antibiofilm, and anti-virulence properties that ultimately lead to the alteration of the bacterial membrane permeability, membrane potential, and reduction potential. Our findings indicated that AA is presently one of the effective treatment options for infections. A high concentration of AA (> 0.156% v/v) can be used to sterilize biofilm-prone surgical instruments, for hospital disinfection, and for treating the external wound, whereas a low concentration of AA (0.00975-0.039% v/v) may be used as an anti-virulence agent for adjuvant treatment of COL-R P. aeruginosa, thereby further improving the application value of AA in the treatment of infections.

The identification of phage vB_1086 of multidrug-resistant Klebsiella pneumoniae and its synergistic effects with ceftriaxone.

BACKGROUND: The continued rise of Klebsiella pneumoniae resistance to antibiotics is precipitating a medical crisis. Bacteriophages have been hailed as one possible therapeutic option to enhance the efficacy of antibiotics. This study describes the genomic characterization and biological property of a new bacteriophage vB_1086 and its potential for phage therapy application against Klebsiella pneumoniae. METHODS: In our study, the double-layer agar plate method isolated a lytic bacteriophage named vB_1086. Besides, we analyzed its biological characteristics and genetic background. Then the antibacterial ability of the bacteriophage vB_1086 combined with antibiotics were analyzed by the combined checkerboard method. The impact on the formation of biofilms was analyzed by crystal violet staining method. RESULTS: vB_1086 is a lytic bacteriophage with stable biological characteristics and clear genetic background, showing good antibacterial activity in combination with ceftriaxone, and the combination of phage and meropenem can effectively inhibit the formation of biofilm. Besides, the combination of bacteriophage and antimicrobials can effectively alleviate the generation of bacterial resistance and reduce the dosage of antimicrobials. CONCLUSION: vB_1086 is a novel phage. To some extent, these results provide valuable information that phage vB_1086 can be combined with antibiotics to reduce the dosage of antimicrobials and alleviate the generation of bacterial resistance.

Membrane-cloaked polydopamine modified mesoporous silica nanoparticles for cancer therapy.

To improve the shortcomings of narrow therapeutic range and low bioavailability of traditional preparations, a composite drug carrier that combines the advantages of biological carriers and synthetic carriers was prepared in this project. The biomimetic nano-delivery system outer membrane vesicles-polydopamine-mesoporous silica nanoparticle (OMVs-PDA-MSN-DOX) for oral administration is composed of OMVs ofEscherichia colias shell and doxorubicin-loaded MSN modified by PDA as core. Several characterization techniques thoroughly examined the nano-drug delivery system to confirm its surface morphology and chemical property. OMVs-PDA-MSN-DOX with a particle size of 150 nm showed significant cell selectivity and safety. We demonstrated that OMVs are capable of protecting pH-sensitive nanostructure from the oral route of administration in the short term. Importantly, OMVs-PDA-MSN-DOX could facilitate intestinal adhesion and improve DOX bioavailability. Overall, the OMVs-cloaked nanocarrier provides an efficient delivery platform for the oral targeting treatment of cancer with pH-sensitive nano-formulations.

Characterization of resistance mechanisms of Enterobacter cloacae Complex co-resistant to carbapenem and colistin.

BACKGROUND: The emergence of carbapenem-resistant and colistin-resistant ECC pose a huge challenge to infection control. The purpose of this study was to clarify the mechanism of the carbapenems and colistin co-resistance in Enterobacter cloacae Complex (ECC) strains. RESULTS: This study showed that the mechanisms of carbapenem resistance in this study are: 1. Generating carbapenemase (7 of 19); 2. The production of AmpC or ESBLs combined with decreased expression of out membrane protein (12 of 19). hsp60 sequence analysis suggested 10 of 19 the strains belong to colistin hetero-resistant clusters and the mechanism of colistin resistance is increasing expression of acrA in the efflux pump AcrAB-TolC alone (18 of 19) or accompanied by a decrease of affinity between colistin and outer membrane caused by the modification of lipid A (14 of 19). Moreover, an ECC strain co-harboring plasmid-mediated mcr-4.3 and blaNDM-1 has been found. CONCLUSIONS: This study suggested that there is no overlap between the resistance mechanism of co-resistant ECC strains to carbapenem and colistin. However, the emergence of strain co-harboring plasmid-mediated resistance genes indicated that ECC is a potential carrier for the horizontal spread of carbapenems and colistin resistance.

Evaluation of resazurin-based assay for rapid detection of polymyxin-resistant gram-negative bacteria.

BACKGROUND: Colistin resistance is considered a serious problem due to a lack of alternative antibiotics. The Rapid ResaPolymyxin Acinetobacter/Pseudomonas NP test is a resazurin reduction-based technique that relies on the visual detection of bacterial growth in the presence of a defined concentration of colistin. The aim of this study was to evaluate the performance of the Rapid ResaPolymyxin Acinetobacter/Pseudomonas NP test in the detection of colistin susceptibility in common clinical Gram-negative bacteria. RESULTS: A total of 253 clinical isolates from a teaching hospital, including Acinetobacter baumanii (n = 58, 8 colistin-resistant), Pseudomonas aeruginosa (n = 61, 11 colistin-resistant), Klebsiella pneumoniae (n = 70, 20 colistin-resistant) and Escherichia coli (n = 64, 14 colistin-resistant) were tested in this study. The sensitivity and specificity of the Rapid ResaPolymyxin Acinetobacter/Pseudomonas NP test compared to Broth microdilution method was 100 and 99%, respectively. CONCLUSIONS: Our results suggest that Rapid ResaPolymyxin Acinetobacter/Pseudomonas NP test could be used as an accurate detection method for colistin resistance.

Biofilm-encapsulated nano drug delivery system for the treatment of colon cancer.

AIM: In this study, 5-fluorouracil (5-FU) is delivered to target colon without the interference of mononuclear phagocyte system (MPS). METHODS: Outer membrane vesicles (OMVs) were used as the biological shield to disguise mesoporous silica (MSN) and 5-FU. OMVs-MSN-5-FU were prepared by high pressure co-extrusion, and characterised on the basis of size, drug loading, transmission electron microscope, infra-red spectroscopy, differential scanning calorimetry, thermal gravity analysis, % in vitro release, MTT assay, cell uptake and in vivo imaging. RESULTS: OMVs-MSN-5-FU with -18.22 ± 0.17 mV zeta potential and 90.4 ± 9.1 nm size were used for oral treatment of colon cancer. Drug loading of the drug was 50.22%±0.17 (w/w). The cumulative release of OMVs-MSN-5-FU reached 75.07%±0.94 in tumour microenvironment. The percentage of cell viability of OMVs-MSN-5-FU was 33.75%±2.73. In vivo experiments results confirmed that OMVs-MSN-5-FU could be taken up by colon cancer cells. CONCLUSIONS: The study provided a promising nano platform for the targeting treatment of colon cancer.

A novel dual sensitive polymer-gambogic acid conjugate: synthesis, characterization, and in vitro evaluation.

Currently, bio-simulate drug delivery systems are highly considered for efficient targeting of tumors. Nevertheless, there are some potential problems such as intelligent release efficiency, subsequently, influence cell toxicity and blood circulation stability. A novel type of stimuli-responsive nanoparticle was developed in accordance with the specific tumor microenvironment to deliver gambogic acid (GA). Herein, we successfully connected GA with mPEG via two different sensitive linkages, valine-citrulline (VC) and cystamine. The structure was characterized by ESI-MS, 1H NMR, FT-IR or MALDI-TOF-MS. The mPEG-VC-SS-GA-NPs (PVSG-NPs) were rapidly prepared. The properties of nanoparticles, including solubility, particle size, morphology, and sensitive drug release performance, were investigated. Compared to single sensitive conjugate (mPEG-SS-GA-NPs, PSG-NPs), PVSG-NPs demonstrated greater solubility and higher sensitive release profile. Cytotoxicity test indicated that PVSG-NPs had apparent cytotoxicity on HepG2 cells and reduced cytotoxicity on normal cells. Additionally, PVSG-NPs mainly kill HepG2 cells by inducing early and late apoptosis and restraining the G0/G1 phase proliferation. Albumin adsorption test revealed that the PVSG-NPs had little albumin combination, consequently, enhancing their circulation constancy. In summary, our findings suggested the novel PVSG-NPs capable of being used for tumor targeting and further practical applications.

Oral Delivery of Pingyangmycin by Layer-by-Layer (LbL) Self-Assembly Polyelectrolyte-Grafted Nano Graphene Oxide.

With the increasing development in scientific technology, building a nanocarrier system for cancer drugs has become a bliss for cancer patients. To allow for the oral administration of hydrophilic drugs, a nanocarrier that was based on negatively charged graphene oxide (GO) and prepared through the Layer-by-Layer (LbL) self-assembly of poly(acrylic acid)-cysteine (PAA-cys) and poly(allylamine hydrochloride) (PAH) was established. In the present study, we demonstrated the excellent biological properties of GO, the biological adhesiveness of PAA-cys, and the protection and controlled release profiles of polyelectrolyte. Pingyangmycin (PYM) was loaded onto the nanocarrier through non-covalent interactions. In vitro drug release studies of the prepared PAA-cys-PAH-GO-PYM were pH-sensitive and showed sustained release effects for over 8 h, before they were completely expelled by gastrointestinal peristalsis. Furthermore, cell viability experiments using A549 lung adenocarcinoma cells revealed that the IC50 of PAA-cys-PAH-GO-PYM, free drug, and GO-PYM were 159.241 µM, 134.960 µM, and 129.815 µM respectively, indicating the higher retention and cytotoxicity of PYM in vitro. When comparing the oral bioavailability of PYM with free drug, in vivo pharmacokinetics studies showed a 1.03-fold and 1.74-fold increase after GO loading and double-layer polyelectrolyte coating, respectively. Thus, PAA-cys-PAH-GO was successfully developed for oral delivery of PYM as anti-cancer therapy, and may provide further insight for oral administration of GO-based nanomaterials.

Sensor array based on single carbon quantum dot for fluorometric differentiation of all natural amino acids.

A sensor array is described that consists of a carbon quantum dot (CQD) and metal ions, including Hg2+, Cu2+, Fe3+, Ag+, Cd2+, and Pb2+. The CQDs display blue fluorescence with excitation/emission maxima at 370/440 nm. It is shown that the array can be applied to the determination of all natural amino acids (NAAs). Metal ions can quench the fluorescence of the CQDs, while NAAs can take metal ions away or co-bind to the CQD@metal-ion complex, which enhances or depresses the fluorescence of the CQDs. Based on the differential fluorescence variation, the CQD@metal-ion@NAA array exhibits a unique pattern for NAAs. Principal component analysis (PCA) and hierarchical cluster analysis (HCA) were carried out to generate visualized datagrams for NAA discrimination. The design and construction of the sensor array is convenient and economical. The sensor array can distinguish NAAs at a concentration of as low as 30 µM, and can distinguish NAAs into acidic, neutral and basic NAAs. Semi-quantitative assay of alanine and threonine was also realized. Based on the low limit of detection and multi-NAA detection capability, the array can differentiate healthy cases from acute leukemia, chronic leukemia and lymphoma by analyzing the NAA status of serum samples. Graphical abstractSchematic representation of a fluorometric (FL) sensor array based on single CQD (carbon quantum dot) interacting with metal ions for differentiating all NAAs (natural amino acids) into acidic, neutral and basic NAAs (ANs, NNs and BNs) through PCA (principle component analysis).

A high incidence and coexistence of multiresistance genes cfr and optrA among linezolid-resistant enterococci isolated from a teaching hospital in Wenzhou, China.

Linezolid is considered as a last-resort antimicrobial agent, the resistance of which is of great concern. The aim of this study was to investigate the mechanisms and transferability of linezolid resistance and molecular epidemiology of linezolid-resistant enterococcal isolates in Wenzhou, China. A collection of 1623 enterococcal strains, including 789 Enterococcus faecalis and 834 Enterococcus faecium, were isolated from our hospital during 2011-2016. Antimicrobial susceptibility testing and clinical data analysis were performed. Molecular mechanisms of linezolid resistance, including the existence of resistance genes cfr and optrA, as well as the mutations in 23S rRNA and ribosomal proteins L3, L4, and L22, were investigated by PCR and sequencing. Conjugation experiments were conducted, and epidemiological characteristics were analyzed by PFGE and MLST. In our study, 31 (3.93%) E. faecalis and 2 (0.24%) E. faecium exhibited resistance to linezolid. Risk factors correlated with linezolid-resistant enterococcal infections included gastrointestinal surgery hospitalization, urogenital disorders, tumor, diabetes, and polymicrobial infections. Among these isolates, 6 (18.18%) harbored cfr, 9 (27.27%) harbored optrA, and 18 (54.55%) co-harbored cfr and optrA. However, mutational mechanisms were not found in this study. Conjugation experiments demonstrated the transferability of cfr and optrA between Gram-positive and Gram-negative bacteria. The clone of these isolates was diverse and scattered. It is noteworthy that cfr and optrA were the main mechanisms of linezolid resistance in this study, posing a potential risk of spread of linezolid resistance. Strikingly, it reported firstly that the two transferable resistance genes cfr and optrA coexisted in the same E. faecalis isolates.

Synthesis, screening and nanocrystals preparation of rhein amide derivatives.

Rhein (RH) has many bioactivities, but the application was limited of its poor solubility. The present study aimed to establish an efficient method for the synthesis of rhein amide derivatives (RAD) to increase the solubility and anti-tumour activity. RAD exhibited stronger anti-tumour activity than RH in MTT assay. The solubility and oil/water partition coefficient results indicated that rhein-phenylalanine and rhein-isoleucine have better absorption effect, which was consolidated in pharmacokinetic study. Then, rhein-phenylalanine and rhein-isoleucine were prepared into nanocrystals via the precipitation high-pressure homogenisation method. Additionally, the nanocrystals both displayed much higher dissolution profiles than the bulk drugs. Pharmacokinetics study indicated that the AUC0-∞ and Cmax of nanocrystals increased markedly (p < 0.01). However, the concentration of RH-Phe-NC was far less than RH-Ile-NC in plasma. Consequently, RH-Ile-NC was validated to be an applicable way to improve the bioavailability of RH, which owns a promising future in clinical application.