Observation of Chiral Channels in Helical Covalent Organic Frameworks.

Unraveling the mechanism of chirality transfer across length scales is crucial to the rational development of functional materials with hierarchical chirality. The key obstacle is the lack of structural information, especially at the mesoscopic level. We report herein the structural identification of helical covalent organic frameworks (heliCOFs) with hierarchical chirality, which integrate molecular chirality, channel chirality, and morphology chirality into one crystalline entity. Specifically, benefiting from the highly ordered structure of heliCOFs, the existence of chiral channels at the mesoscopic level has been confirmed by electron crystallography, and the handedness of these chiral channels has been directly determined through the stereopair imaging technique. Accordingly, the chirality transfer in heliCOFs from microscopic to macroscopic levels could be rationalized with a layer-rotating model that has been supported by both crystal structure analysis and theoretical calculations. Observation of chiral channels in heliCOFs not only provides unprecedented data for the understanding of the chirality transfer process but also sheds new light on the rational construction of highly ordered polymeric materials with hierarchical chirality.

Modulatory role of SmeQ in SmeYZ efflux pump-involved functions in Stenotrophomonas maltophilia.

BACKGROUND: SmeYZ is a constitutively expressed efflux pump in Stenotrophomonas maltophilia. Previous studies demonstrated that: (i) smeYZ inactivation causes compromised swimming, oxidative stress tolerance and aminoglycoside resistance; and (ii) the ΔsmeYZ-mediated pleiotropic defects, except aminoglycoside susceptibility, result from up-regulation of entSCEBB'FA and sbiAB operons, and decreased intracellular iron level. OBJECTIVES: To elucidate the modulatory role of SmeQ, a novel cytoplasmic protein, in ΔsmeYZ-mediated pleiotropic defects. METHODS: The presence of operons was verified using RT-PCR. The role of SmeQ in ΔsmeYZ-mediated pleiotropic defects was assessed using in-frame deletion mutants and functional assays. A bacterial adenylate cyclase two-hybrid assay was used to investigate the protein-protein interactions. Gene expression was quantified using quantitative RT-PCR (RT-qPCR). RESULTS: SmeYZ and the downstream smeQ formed an operon. SmeQ inactivation in the WT KJ decreased aminoglycoside resistance but did not affect swimming and tolerance to oxidative stress or iron depletion. However, smeQ inactivation in the smeYZ mutant rescued the ΔsmeYZ-mediated pleiotropic defects, except for aminoglycoside susceptibility. In the WT KJ, SmeQ positively modulated SmeYZ pump function by transcriptionally up-regulating the smeYZQ operon. Nevertheless, in the smeYZ mutant, SmeQ exerted its modulatory role by up-regulating entSCEBB'FA and sbiAB operons, decreasing intracellular iron levels, and causing ΔsmeYZ-mediated pleiotropic defects, except for aminoglycoside susceptibility. CONCLUSIONS: SmeQ is the first small protein identified to be involved in efflux pump function in S. maltophilia. It exerts modulatory effect by transcriptionally altering the expression of target genes, which are the smeYZQ operon in the WT KJ, and smeYZQ, entSCEBB'FA and sbiAB operons in smeYZ mutants.

Central and peripheral blood pressures in relation to the triglyceride-glucose index in a Chinese population.

BACKGROUND: The triglyceride-glucose (TyG) index has been proposed as a surrogate marker of insulin resistance. However, the relationship between the TyG index and central blood pressure (BP), has not been well studied in adults. METHODS: A total of 715 Chinese adult participants were enrolled in this study. Anthropometric and BP were assessed. The TyG index was calculated as ln[fasting triglycerides(mg/dL) × fasting glucose(mg/dL)/2]. Central BP was measured using SphygmoCor system. RESULTS: The participants were stratified into three groups based on the TyG index, and significant differences were observed in metabolic and cardiovascular parameters and the prevalence of hypertension among the groups. Both brachial (ß = 1.38, P = 0.0310; group highest vs. lowest, ß = 2.66, P = 0.0084) and aortic (ß = 2.38, P = 0.0002; group highest vs. lowest, ß = 3.96, P = 0.0001) diastolic BP were significantly and independently associated with the TyG index and increasing TyG index tertile. However, there was no independent association between the TyG index and systolic BP. A one-unit increase in the TyG index was associated with a 46% higher risk of hypertension (P = 0.0121), and compared with the lowest group, participants in the highest group had a 95% higher risk of hypertension (P = 0.0057). CONCLUSIONS: Our study demonstrates a significant and independent association between the TyG index and both brachial and aortic diastolic BP in Chinese adults. Furthermore, the TyG index was found to be an independent predictor of hypertension.

Immune-stealth VP28-conjugated heparin nanoparticles for enhanced and reversible anticoagulation.

Heparins are a family of sulfated linear negatively charged polysaccharides that have been widely used for their anticoagulant, antithrombotic, antitumor, anti-inflammatory, and antiviral properties. Additionally, it has been used for acute cerebral infarction relief as well as other pharmacological actions. However, heparin's self-aggregated macrocomplex may reduce blood circulation time and induce life-threatening thrombocytopenia (HIT) complicating the use of heparins. Nonetheless, the conjugation of heparin to immuno-stealth biomolecules may overcome these obstacles. An immunostealth recombinant viral capsid protein (VP28) was expressed and conjugated with heparin to form a novel nanoparticle (VP28-heparin). VP28-heparin was characterized and tested to determine its immunogenicity, anticoagulation properties, effects on total platelet count, and risk of inducing HIT in animal models. The synthesized VP28-heparin trimeric nanoparticle was non-immunogenic, possessed an average hydrodynamic size (8.81 ± 0.58 nm) optimal for the evasion renal filtration and reticuloendothelial system uptake (hence prolonging circulating half-life). Additionally, VP28-heparin did not induce mouse death or reduce blood platelet count when administered at a high dosein vivo(hence reducing HIT risks). The VP28-heparin nanoparticle also exhibited superior anticoagulation properties (2.2× higher prothrombin time) and comparable activated partial thromboplastin time, but longer anticoagulation period when compared to unfractionated heparin. The anticoagulative effects of the VP28-heparin can also be reversed using protamine sulfate. Thus, VP28-heparin may be an effective and safe heparin derivative for therapeutic use.

Valorization of treated swine wastewater and generated biomass by microalgae: Their effects and salt tolerance mechanisms on wheat seedling growth.

The extensive use of mineral fertilizers has a negative impact on the environment, whereas wastewater and microalgal biomass can provide crops with nutrients such as nitrogen, phosphorus, and potassium, and have the potential to be used as a source of fertilizers in circular agriculture. In this study, a step-by-step resource utilization study of algae-containing wastewater generated from microalgae treatment of swine wastewater was carried out. When wheat seedlings were cultivated in the effluent after microalgae separation, the root fresh weight, seedling fresh weight, and total seedling length were increased by 3.44%, 14.45%, and 13.64%, respectively, compared with that of the algae-containing wastewater, and there was no significant difference in seedling fresh weight, total seedling length, maximum quantum yields of PSII photochemistry (Fv/Fm), and performance index (PIABS) from that of the Hogland solution group, which has the potential to be an alternative liquid fertilizer. Under salt stress, microalgae extract increased the contents of GA3, IAA, ABA, and SA in wheat seedlings, antioxidant enzymes maintained high activity, and the PIABS value increased. Low-dose microalgae extract (1 mL/L) increased the root fresh weight, seedling fresh weight, longest seedling length, and total seedling length by 30.73%, 31.28%, 16.43%, and 28.85%, respectively. Algae extract can act as a plant biostimulant to regulate phytohormone levels to attenuate the damage of salt stress and promote growth.

Analysis of abnormal expression of signaling pathways in PQ-induced acute lung injury in SD rats based on RNA-seq technology.

Background: Paraquat (PQ) plays an important role in agricultural production due to its highly effective herbicidal effect. However, it has led to multiple organ failure in those who have been poisoned, with damage most notable in the lungs and ultimately leading to death. Because of little research has been performed at the genetic level, and therefore, the specific genetic changes caused by PQ exposure are unclear.Methods: Paraquat poisoning model was constructed in Sprague Dawley (SD) rats, and SD rats were randomly divided into Control group, paraquat (PQ) poisoning group and Anthrahydroquinone-2,6-disulfonate (AH2QDS) treatment group. Then, the data was screened and quality controlled, compared with reference genes, optimized gene structure, enriched at the gene expression level, and finally, signal pathways with significantly different gene enrichment were screened.Results: This review reports on lung tissues from paraquat-intoxicated Sprague Dawley (SD) rats that were subjected to RNA-seq, the differentially expressed genes were mainly enriched in PI3K-AKT, cGMP-PKG, MAPK, Focal adhesion and other signaling pathways.Conclusion: The signaling pathways enriched with these differentially expressed genes are summarized, and the important mechanisms mediated through these pathways in acute lung injury during paraquat poisoning are outlined to identify important targets for AH2QDS treatment of acute lung injury due to paraquat exposure, information that will be used to support a subsequent in-depth study on the mechanism of PQ action.

Structural Insights into the Stability and Recognition Mechanism of the Antiquinalphos Nanobody for the Detection of Quinalphos in Foods.

Nanobodies (Nbs) have great potential in immunoassays due to their exceptional physicochemical properties. With the immortal nature of Nbs and the ability to manipulate their structures using protein engineering, it will become increasingly valuable to understand what structural features of Nbs drive high stability, affinity, and selectivity. Here, we employed an anti-quinalphos Nb as a model to illustrate the structural basis of Nbs' distinctive physicochemical properties and the recognition mechanism. The results indicated that the Nb-11A-ligand complexes exhibit a "tunnel" binding mode formed by CDR1, CDR2, and FR3. The orientation and hydrophobicity of small ligands are the primary determinants of their diverse affinities to Nb-11A. In addition, the primary factors contributing to Nb-11A's limited stability at high temperatures and in organic solvents are the rearrangement of the hydrogen bonding network and the enlargement of the binding cavity. Importantly, Ala 97 and Ala 34 at the active cavity's bottom and Arg 29 and Leu 73 at its entrance play vital roles in hapten recognition, which were further confirmed by mutant Nb-F3. Thus, our findings contribute to a deeper understanding of the recognition and stability mechanisms of anti-hapten Nbs and shed new light on the rational design of novel haptens and directed evolution to produce high-performance antibodies.

Role of yceA-cybB-yceB operon in oxidative stress tolerance, swimming motility and antibiotic susceptibility of Stenotrophomonas maltophilia.

BACKGROUND: Stenotrophomonas maltophilia is ubiquitous in the environment and is an important MDR opportunistic pathogen. Oxidative stress is an inevitable challenge to an aerobic bacterium. Accordingly, S. maltophilia has many capabilities to face variable oxidative stress. Some of the oxidative stress alleviation systems cross-protect bacteria from antibiotics. In our recent RNA-sequencing transcriptome analysis, we documented the increased expression of a three-gene cluster, yceA-cybB-yceB, in the presence of hydrogen peroxide (H2O2). The YceI-like, cytochrome b561 and YceI-like proteins encoded by yceA, cybB and yceB are located in the cytoplasm, inner membrane and periplasm, respectively. OBJECTIVES: To characterize the role of the yceA-cybB-yceB operon of S. maltophilia in oxidative stress tolerance, swimming motility and antibiotic susceptibility. METHODS: The presence of the yceA-cybB-yceB operon was verified by RT-PCR. The functions of this operon were revealed by in-frame deletion mutant construction and complementation assay. Expression of the yceA-cybB-yceB operon was assessed by quantitative RT-PCR. RESULTS: The yceA, cybB and yceB genes form an operon. Loss of function of the yceA-cybB-yceB operon compromised menadione tolerance, enhanced swimming motility and increased susceptibility to fluoroquinolone and ß-lactam antibiotics. The expression of the yceA-cybB-yceB operon was up-regulated by oxidative stress, such as H2O2 and superoxide, and not impacted by antibiotics, such as fluoroquinolone and ß-lactams. CONCLUSIONS: The evidence strongly supports the view that the physiological function of the yceA-cybB-yceB operon is to alleviate oxidative stress. The operon provides an additional example that oxidative stress alleviation systems can cross-protect S. maltophilia from antibiotics.

Touch print smear of testicular tissue with thionine stain for intraoperative diagnosis in azoospermic men.

PURPOSE: To compare the diagnostic value of testicular tissue touch print smear (TPS) conducted on azoospermic patients with results obtained from histopathology and in vitro fertility (IVF) lab findings. METHODS: Microdissection testicular sperm extraction was performed on a group of 148 azoospermic patients and testicular samples obtained intraoperatively. Using TPS, the samples were smeared onto a sterile slide, followed with staining using thionine. The testis tissue bulk samples were also transferred to the IVF lab, and determinations of sperm presence or absence obtained from IVF lab tests were compared with the TPS sample results. Needle testis biopsy was separately performed on a group of 360 azoospermic patients, and results of pathohistology review on the biopsies were further compared with determinations of spermatogenesis stage obtained from TPS for those patients. RESULTS: When compared with IVF lab results, TPS was found to have 100% (126/126) positive predictive value and 95.5% (25/26) negative predictive value for predicting sperm presence or absence, respectively. Furthermore, TPS was further found to have a 93.6% correlation (337 of 360 biopsies) with results of histological diagnoses performed by needle biopsy. Results from histology and TPS for the detection of sperm presence were concordant in 96.1% (346/360) of biopsies. Diagnosis of SCO by TPS shows the highest correlation with histopathology (98.6%), followed by complete spermatogenesis (97.5%), early maturation arrest (78.9%), and late maturation arrest (27.3%). CONCLUSIONS: The results support the continued use of TPS in testicular tissue analysis for more rapid assessment of spermatogenesis and for detection of spermatozoa in azoospermic subjects.

Prediction of microdissection testicular sperm extraction outcomes of azoospermic patients post-chemotherapy using cyclophosphamide equivalent dose.

PURPOSE: We determined the sperm retrieval rate in men with persistent azoospermia post-chemotherapy in relation to cyclophosphamide equivalent dose (CED), a unit for quantifying alkylating agent exposure. METHODS: Medical records were retrospectively reviewed of 1098 patients diagnosed with non-obstructive azoospermia who had undergone microdissection testicular sperm extraction (mTESE) between January 2010 and 2021 at our institution. Twenty-three patients with a prior history of chemotherapy were included in the study. Oncological data, chemotherapy regime, and dosage were reviewed. The pretreatment hormone profile, CED, and mTESE outcomes were analyzed. RESULTS: Testicular spermatozoa were successfully retrieved from 11 patients (47%). The mean patient age was 37.3 years (range, 27-41 years), and mean time interval from chemotherapy to mTESE, 11.8 years (range, 1-45 years). Patients exposed to alkylating agents had significantly lower sperm retrieval rates than those not exposed to alkylating agents (1/9, 11% vs. 10/14, 71%, p = 0.009). No men with CED > 4000 mg/m2 (n = 6) had viable sperm in the testes during mTESE. Moreover, patients diagnosed with testicular non-seminomatous germ cell tumors had a favorable sperm retrieval rate (67%) compared to patients with lymphoma (20%) or leukemia (33%). CONCLUSION: Patients with permanent azoospermia post-chemotherapy have a lower testicular sperm retrieval rate when the chemotherapy regimen included alkylating agents. In cases where patients have undergone more intensive gonadotoxic treatments, such as higher CED, the likelihood of successful sperm retrieval is low. It is advisable to counsel such patients using the CED model prior to considering surgical sperm retrieval.

FadACB and smeU1VWU2X Contribute to Oxidative Stress-Mediated Fluoroquinolone Resistance in Stenotrophomonas maltophilia.

Pathogenic bacteria experience diverse stresses induced by host cells during infection and have developed intricate systems to trigger appropriate responses. Bacterial stress responses have been reported to defend against these stresses and cross-protect bacteria from antibiotic attack. In this study, we aimed to assess whether oxidative stress affects bacterial susceptibility to fluoroquinolone (FQ) and the underlying mechanism. Stenotrophomonas maltophilia, a species with high genetic diversity, is distributed ubiquitously and is an emerging multidrug-resistant opportunistic pathogen. FQs are among the limited antibiotic treatment options for S. maltophilia infection. The minimum inhibitory concentrations (MICs) of 103 S. maltophilia clinical isolates against ciprofloxacin (CIP) and levofloxacin (LVX) were determined using the agar dilution method in Mueller-Hinton plates with or without menadione (MD), a superoxide generator. The resistance rates for ciprofloxacin and levofloxacin were 40% and 18% in the MD-null group and increased to 91% and 23%, respectively, in the MD-treated group. Of the 103 isolates tested, 54% and 27% had elevated MICs against ciprofloxacin and levofloxacin, respectively, in the presence of MD. The involvement of oxidative stress responses in the MD-mediated FQ resistance was further assessed by mutants construction and viability assay. Among the 16 oxidative stress alleviation systems evaluated, fadACB and smeU1VWU2X contributed to MD-mediated FQ resistance. The antibiotic susceptibility test is an accredited clinical method to evaluate bacterial susceptibility to antibiotics in clinical practice. However, oxidative stress-mediated antibiotic resistance was not detected using this test, which may lead to treatment failure.

The fciTABC and feoABI systems contribute to ferric citrate acquisition in Stenotrophomonas maltophilia.

BACKGROUND: Stenotrophomonas maltophilia, a member of γ-proteobacteria, is a ubiquitous environmental bacterium that is recognized as an opportunistic nosocomial pathogen. FecABCD system contributes to ferric citrate acquisition in Escherichia coli. FeoABC system, consisting of an inner membrane transporter (FeoB) and two cytoplasmic proteins (FeoA and FeoC), is a well-known ferrous iron transporter system in γ-proteobacteria. As revealed by the sequenced genome, S. maltophilia appears to be equipped with several iron acquisition systems; however, the understanding of these systems is limited. In this study, we aimed to elucidate the ferric citrate acquisition system of S. maltophilia. METHODS: Candidate genes searching and function validation are the strategy for elucidating the genes involved in ferric citrate acquisition. The candidate genes responsible for ferric citrate acquisition were firstly selected using FecABCD of E. coli as a reference, and then revealed by transcriptome analysis of S. maltophilia KJ with and without 2,2'-dipyridyl (DIP) treatment. Function validation was carried out by deletion mutant construction and ferric citrate utilization assay. The bacterial adenylate cyclase two-hybrid system was used to verify intra-membrane protein-protein interaction. RESULTS: Smlt2858 and Smlt2356, the homologues of FecA and FecC/D of E. coli, were first considered; however, deletion mutant construction and functional validation ruled out their involvement in ferric citrate acquisition. FciA (Smlt1148), revealed by its upregulation in DIP-treated KJ cells, was the outer membrane receptor for ferric citrate uptake. The fciA gene is a member of the fciTABC operon, in which fciT, fciA, and fciC participated in ferric citrate acquisition. Uniquely, the Feo system of S. maltophilia is composed of a cytoplasmic protein FeoA, an inner membrane transporter FeoB, and a predicted inner membrane protein FeoI. The intra-membrane protein-protein interaction between FeoB and FeoI may extend the substrate profile of FeoB to ferric citrate. FeoABI system functioned as an inner membrane transporter of ferric citrate. CONCLUSIONS: The FciTABC and FeoABI systems contribute to ferric citrate acquisition in S. maltophilia.

The predictive factors of successful sperm retrieval for men with Y chromosome AZFc microdeletion.

PURPOSE: To identify key predictors for successful sperm retrieval in men with AZFc microdeletion. METHODS: Totally, 71 infertile men with confirmed AZFc microdeletion were studied. For each patient, the endocrine profile including serum follicle stimulating hormone (FSH), luteinizing hormone, total testosterone, prolactin, and estradiol was recorded, along with intratesticular testosterone levels (ITT), age, and testicular size. The factors were further analyzed to determine the key predictors for successful sperm retrieval. RESULTS: Of the 71 men with AZFc microdeletion, 52 (73.2%) were classified as having non-obstructive azoospermia (NOA), 7 (9.9%) as having cryptozoospermia, and 12 (15.8%) as having severe oligoasthenoteratozoospermia. Of the 52 men with azoospermia, 47 received microdissection testicular sperm retrieval, and sperm retrieval was successful in 35 of those cases (74.5%). A significantly lower serum FSH (p = 0.03) was found in those patients from whom sperm could be successfully retrieved. The area under the receiving operating characteristic curve for FSH was determined to be 0.721. Using an FSH cutoff point of 12.95 mIU/mL, the model for predicting successful sperm retrieval was found to have 51.4% sensitivity, 83.3% specificity, 90.0% positive predictive value, and 37.0% negative predictive value. ITT levels were obtained from 7 NOA patients, the mean ITT and the mean ITT/serum testosterone ratio was 1932.8 ng/ml and 567.2 in 6 men with successful sperm retrieval, whereas, in a patient with fail sperm retrieval, the levels were 2370 ng/ml and 393.0. CONCLUSION: Men exhibiting AZFc microdeletion with discernible spermatogenesis from whom sperm was successfully retrieved by mTESE generally presented with relatively lower FSH levels.

Molecular Characterization of Three Tandemly Located Flagellin Genes of Stenotrophomonas maltophilia.

Stenotrophomonas maltophilia is a motile, opportunistic pathogen. The flagellum, which is involved in swimming, swarming, adhesion, and biofilm formation, is considered a virulence factor for motile pathogens. Three flagellin genes, fliC1, fliC2, and fliC3, were identified from the sequenced S. maltophilia genome. FliC1, fliC2, and fliC3 formed an operon, and their encoding proteins shared 67-82% identity. Members of the fliC1C2C3 operon were deleted individually or in combination to generate single mutants, double mutants, and a triple mutant. The contributions of the three flagellins to swimming, swarming, flagellum morphology, adhesion, and biofilm formation were assessed. The single mutants generally had a compromise in swimming and no significant defects in swarming, adhesion on biotic surfaces, and biofilm formation on abiotic surfaces. The double mutants displayed obvious defects in swimming and adhesion on abiotic and biotic surfaces. The flagellin-null mutant lost swimming ability and was compromised in adhesion and biofilm formation. All tested mutants demonstrated substantial but different flagellar morphologies, supporting that flagellin composition affects filament morphology. Bacterial swimming motility was significantly compromised under an oxidative stress condition, irrespective of flagellin composition. Collectively, the utilization of these three flagellins for filament assembly equips S. maltophilia with flagella adapted to provide better ability in swimming, adhesion, and biofilm formation for its pathogenesis.

Role of AzoR, a LysR-type transcriptional regulator, in SmeVWX pump-mediated antibiotic resistance in Stenotrophomonas maltophilia.

BACKGROUND: The SmeVWX efflux pump of Stenotrophomonas maltophilia contributes to menadione (MD) tolerance and resistance to chloramphenicol, quinolones and tetracycline. The components of the SmeVWX efflux pump are encoded by a five-gene operon, smeU1VWU2X. We have previously demonstrated that the smeU1VWU2X operon is intrinsically unexpressed and inducibly expressed by MD via a SoxR- and SmeRv-involved regulatory circuit in S. maltophilia KJ. We also inferred that there should be other regulator(s) involved in MD-mediated smeU1VWU2X expression in addition to SoxR and SmeRv. OBJECTIVES: To identify novel regulator(s) involved in the regulation of MD-mediated smeU1VWU2X expression and elucidate the regulatory circuit. METHODS: A possible regulator candidate involved in the regulation of MD-mediated smeU1VWU2X expression was identified by a homologue search using the helix-turn-helix domain of SmeRv as a query. Gene expression was assessed using the promoter-xylE transcriptional fusion assay and quantitative RT-PCR. The impact of the regulator on SmeVWX pump-mediated functions was investigated via mutant construction and functional tests (antibiotic susceptibility and MD tolerance). RESULTS: AzoR (Smlt3089), a LysR-type transcriptional regulator, was investigated. In unstressed logarithmically grown cells, AzoR was abundantly expressed and functioned as a repressor, inhibiting the expression of the smeU1VWU2X operon. MD challenge attenuated azoR expression, thus derepressing the expression of the smeU1VWU2X operon in S. maltophilia KJ. AzoR down-regulation-mediated smeU1VWU2X expression was observed in quinolone-resistant and SmeVWX-overexpressing S. maltophilia clinical isolates. CONCLUSIONS: AzoR negatively regulates the expression of the smeU1VWU2X operon and SmeVWX pump-mediated antibiotic resistance in S. maltophilia.

Role of the PhoPQ two-component regulatory system in the ß-lactam resistance of Stenotrophomonas maltophilia.

BACKGROUND: Stenotrophomonas maltophilia, an opportunistic pathogen, is intrinsically resistant to most ß-lactams except ceftazidime and ticarcillin/clavulanate, due to the inducibly expressed L1 and L2 ß-lactamases. A two-component regulatory system (TCS) allows organisms to sense and respond to changes in different environmental conditions. The PhoPQ TCS of S. maltophilia plays regulatory roles in antibiotic susceptibility, physiology, stress adaption and virulence. Inactivation of S. maltophilia phoPQ increases ß-lactam susceptibility. OBJECTIVES: To elucidate the PhoPQ-regulating mechanism for ß-lactam resistance. METHODS: The candidate genes responsible for the ΔphoPQ-mediated ß-lactam resistance compromise were identified by transcriptome analysis and verified by quantitative RT-PCR and complementation assay. Etest was used to assess ß-lactam susceptibility. The phosphorylation level of the PhoP protein was determined by Phos-tag SDS-PAGE and western blotting. A ß-lactam influx assay was used to investigate the influx efficiency of a ß-lactam. RESULTS: PhoPQ deletion down-regulated the expression of mltD1 and slt, attenuated the induced ß-lactamase activity and then compromised the ß-lactam resistance. Complementation of mutant phoPQ with mltD1 or slt genes partially reverted the induced ß-lactamase activity and ß-lactam resistance. The PhoPQ TCS was activated in logarithmically grown KJ cells and was further activated by low magnesium, but not by a ß-lactam. However, low-magnesium-mediated PhoPQ activation hardly made an impact on ß-lactam resistance enhancement. Furthermore, PhoPQ inactivation altered the outer membrane permeability and increased the influx of a ß-lactam. CONCLUSIONS: The PhoPQ TCS is activated to some extent in physiologically grown S. maltophilia. Inactivation of phoPQ attenuates the expression of mltD1 and slt, and increases ß-lactam influx, both synergically contributing to ß-lactam resistance compromise.

Clinical and molecular characterization of Acinetobacter seifertii in Taiwan.

OBJECTIVES: Acinetobacter seifertii, a new member of the Acinetobacter baumannii group, has emerged as a cause of severe infections in humans. We investigated the clinical and molecular characteristics of A. seifertii. PATIENTS AND METHODS: This retrospective study enrolled 80 adults with A. seifertii bloodstream infection (BSI) at four medical centres over an 8 year period. Species identification was confirmed by MALDI-TOF MS, rpoB sequencing and WGS. Molecular typing was performed by MLST. Clinical information, antimicrobial susceptibility and the mechanisms of carbapenem and colistin resistance were analysed. Transmissibility of the carbapenem-resistance determinants was examined by conjugation experiments. RESULTS: The main source of A. seifertii BSI was the respiratory tract (46.3%). The 28 day and in-hospital mortality rates of A. seifertii BSI were 18.8% and 30.0%, respectively. High APACHE II scores and immunosuppressant therapy were independent risk factors for 28 day mortality. The most common MLST type was ST553 (58.8%). Most A. seifertii isolates were susceptible to levofloxacin (86.2%), and only 37.5% were susceptible to colistin. Carbapenem resistance was observed in 16.3% of isolates, mostly caused by the plasmid-borne ISAba1-blaOXA-51-like genetic structure. A. seifertii could transfer various carbapenem-resistance determinants to A. baumannii, Acinetobacter nosocomialis and other A. seifertii isolates. Variations of pmrCAB and lpxCAD genes were not associated with colistin resistance of A. seifertii. CONCLUSIONS: Levofloxacin and carbapenems, but not colistin, have the potential to be the drug of choice for A. seifertii infections. A. seifertii can transfer carbapenem-resistance determinants to other species of the A. baumannii group and warrants close monitoring.

Expression of ABC transporter and scavenger receptor mRNAs in PBMCs in 100-km ultramarathon runners.

BACKGROUND: Cholesterol metabolism is tightly regulated at the cellular level. This study was to measure the expression levels of ATP-binding cassette transporter A1 (ABCA1) and G1 (ABCG1), scavenger receptor class B type I (SR-BI) and class A (SRA), and CD36 mRNAs in peripheral blood mononuclear cells (PBMCs) in response to 100-km ultramarathon event and determine any correlation between these ABC transporters/scavenger receptor expression levels and plasma cholesterol homeostasis. MATERIALS AND METHODS: Twenty-six participants were enrolled. Blood was drawn from each individual 1 week prior, immediately after, and 24 hours after the race. The expression levels of ABCA1, ABCG1, SR-BI, SRA and CD36 in PBMCs were measured by using real-time quantitative reverse transcription polymerase chain reaction. RESULTS: Plasma triglyceride levels were significantly increased immediately after the race and dropped at 24-hour post-race compared with pre-race values. The 100-km ultramarathon boosted high-density lipoprotein cholesterol (HDL-C) levels and decreased low-density lipoprotein cholesterol (LDL-C) levels 24-hour post-race. The expression levels of ABCA1, ABCG1 and SR-BI were markedly decreased, whereas that of CD36 was slightly but significantly upregulated in runners' PBMCs immediately after the race. Ultramarathon resulted in immediate large-scale stimulation of inflammatory cytokines with increased plasma interleukin-6 and tumour necrosis factor-alpha levels. Moreover, by using in vitro models with human monocytic cell lines, incubation of runners' plasma immediately after the race significantly downregulated ABCA1 and ABCG1, and upregulated CD36 expression in these cells. CONCLUSIONS: ABCA1, ABCG1 and CD36 gene expressions in PBMCS might be associated with endurance exercise-induced plasma cholesterol homeostasis and systemic inflammatory response.

Electrical Cardiometry and Cardiac Biomarkers in 24-h and 48-h Ultramarathoners.

Our study aimed to (i) utilize novel electrical cardiometry and observe acute changes in cardiac biomarkers among 24-h and 48-h ultra-marathoners, and (ii) examine whether alterations in cardiac responses were associated with the average running speed of these participants. Twenty-four 24-h and sixteen 48-h ultra-marathoners were recruited. Electrical cardiometry in the 2 groups showed significant post-race drops in systolic pressure (24-h: p=0.001; 48-h: p=0.016) and rapid increases in heart rate (24-h, p=0.004; 48-h, p=0.001). Cardiac output increased in 48-h runners (p=0.012) and stroke volume decreased in 24-h runners (p=0.009) at post-test. Six of 20 (30%) 24-h and 4 of 16 (25%) 48-h runners had high-sensitivity troponin T values above the reference interval after the races. N-terminal proB-type natriuretic peptide levels showed a 15-fold increase in 24-h runners and a 10-fold increase in 48-h runners at post-race. There was a positive correlation between delta N-terminal proB-type natriuretic peptide and running mileage (rs=0.629, p=0.003) in 24-h ultra-marathoners. In conclusion, stroke volume and cardiac output showed inconsistent changes between the 2 groups. Average running speed has a significant effect on post-exercise elevation in cardiac biomarkers.

Effects of 100-km ultramarathon on erythropoietin variation in runners with hepatitis B virus carrier.

Completing an ultramarathon leads to an immediate postrace surge of erythropoietin (EPO). Patients with chronic liver disease may have high plasma EPO concentrations. This study aims to explore whether plasma EPO concentrations vary between hepatitis B virus carrier (HBVc) and non-HBVc runners during long distance running. Blood samples were collected from 8 HBVc and 18 non-HBVc runners at 3 different time points: 1 week before, immediately following, and then 24 h after the 100-km ultramarathon race. Samples were analyzed for plasma EPO levels. EPO concentration had a statistically significant rise immediately after the race (8.7 [7.1-11.9] mU·mL-1 to 23.7 [14.8-37.2] mU·mL-1, P < 0.001) and maintained the high levels 24 h after the race finished (16.7 [11.5-21.0] mU·mL-1, P < 0.001) in all participants. The mean of EPO concentration was 8.9 (5.7-13.2) mU·mL-1 in HBVc runners and was 8.7 (7.7-11.2) mU·mL-1 in non-HBVc runners in the prerace. In HBVc runners, plasma EPO levels were no different at baseline (P = 0.657) and increased in the same fashion in response to ultramarathon compared with non-HBVc runners. Plasma EPO levels between the two groups were not statistically different at any time point. Prolonged endurance exercise led to a significant increase in EPO. A comparable increase in EPO levels was observed in HBVc and non-HBVc runners during and 24 h after 100-km ultramarathon. However, a small sample size might have affected the ability to detect a difference if it does exist.