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Nowadays, high-phase-inversion in situ emulsification technology has shown great potential in enhancing oil recovery from high-water-cut thin-oil reservoirs. However, emulsification characteristics, interfacial properties, and the mechanism of high phase inversion have not been systematically described. In this study, an emulsification experiment was conducted to investigate the effects of shear time, shear rate, and temperature on the phase inversion of thin oil. Furthermore, the influence of resin and wax on the dispersion of asphaltene was studied through microscopic morphology analysis. Interfacial tension measurement and interfacial viscoelasticity analysis were carried out to determine the interaction characteristics of asphaltene, resin, and wax at the interface. The results showed that, at 50 °C, the phase-inversion point of thin oil reached as high as 75%, and even at 60 °C, it remained at 70%. The shear time and shear rate did not affect the phase-inversion point of thin oil, while an increase in temperature led to a decrease in the phase-inversion point. Moreover, compared to the 20% phase-inversion point of base oil, the phase-inversion point increased with different proportions of asphaltene, resin, and wax. Particularly, at the ratio of asphaltene/resin/wax = 1:5:9, the phase-inversion point reached as high as 80%, indicating the optimal state. In this proportion, asphaltene aggregates exhibited the smallest and most uniform size, best dispersion, lower interfacial tension, and higher interfacial modulus. These findings provide reference and guidance for further enhancing oil recovery in medium-to-high-water-cut thin-oil reservoirs.
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BACKGROUND: The emergence of plasmid-mediated mobile colistin resistance (mcr) gene poses a great challenge to the clinical application of polymyxins. To date, mcr-1 to mcr-10 have been found in animals, humans, and the environment. Among them, mcr-8 was first identified in Klebsiella pneumoniae (K. pneumoniae) of swine origin, and then mcr-8.1 to mcr-8.5 were successively identified. Notably, K. pneumoniae is the major host of the mcr-8 gene in both animals and humans. This study aims to explore the characteristics of K. pneumoniae strains carrying the mcr-8 gene and tmexCD1-toprJ1 gene cluster and investigate the correlation between these two antibiotic resistance genes. METHODS: The isolates from the poultry farms and the surrounding villages were identified by mass spectrometer, and the strains positive for mcr-1 to mcr-10 were screened by polymerase chain reaction (PCR). The size of the plasmid and the antimicrobial resistance genes carried were confirmed by S1-nuclease pulsed-field gel electrophoresis (S1-PFGE) and Southern hybridization, and the transferability of the plasmid was verified by conjugation experiments. Antimicrobial susceptibility testing (AST) and whole genome sequencing (WGS) were used to characterize the strains. RESULTS: Two K. pneumoniae isolates (KP26 and KP29) displaying polymyxin resistance were identified as mcr-8 gene carriers. Besides that, tigecycline-resistant gene cluster tmexCD1-toprJ1 was also found on the other plasmid which conferred strain resistance to tigecycline. Through epidemiological analysis, we found that the mcr-8 gene has dispersed globally, circulating in the human, animals, and the environment. Furthermore, our analysis suggests that the coexistence of mcr-8 and tmexCD1-toprJ1 on a single plasmid might evolved through plasmid recombination. CONCLUSIONS: Although the mcr-8 and tmexCD1-toprJ1 gene clusters in the two strains of K. pneumoniae in this study were on two different plasmids, they still pose a potential threat to public health, requiring close monitoring and further study.
Assuntos
Antibacterianos , Colistina , Farmacorresistência Bacteriana , Infecções por Klebsiella , Klebsiella pneumoniae , Testes de Sensibilidade Microbiana , Família Multigênica , Plasmídeos , Klebsiella pneumoniae/genética , Klebsiella pneumoniae/efeitos dos fármacos , Plasmídeos/genética , Colistina/farmacologia , Animais , Antibacterianos/farmacologia , Infecções por Klebsiella/microbiologia , Farmacorresistência Bacteriana/genética , Proteínas de Bactérias/genética , Humanos , Aves Domésticas/microbiologiaRESUMO
BACKGROUND: Patients with chronic lung diseases (CLDs), defined as progressive and life-limiting respiratory conditions, experience a heavy symptom burden as the conditions become more advanced, but palliative referral rates are low and late. Prognostic tools can help clinicians identify CLD patients at high risk of deterioration for needs assessments and referral to palliative care. As current prognostic tools may not generalize well across all CLD conditions, we aim to develop and validate a general model to predict one-year mortality in patients presenting with any CLD. METHODS: A retrospective cohort study of patients with a CLD diagnosis at a public hospital from July 2016 to October 2017 was conducted. The outcome of interest was all-cause mortality within one-year of diagnosis. Potential prognostic factors were identified from reviews of prognostic studies in CLD, and data was extracted from electronic medical records. Missing data was imputed using multiple imputation by chained equations. Logistic regression models were developed using variable selection methods and validated in patients seen from January 2018 to December 2019. Discriminative ability, calibration and clinical usefulness of the model was assessed. Model coefficients and performance were pooled across all imputed datasets and reported. RESULTS: Of the 1000 patients, 122 (12.2%) died within one year. Patients had chronic obstructive pulmonary disease or emphysema (55%), bronchiectasis (38%), interstitial lung diseases (12%), or multiple diagnoses (6%). The model selected through forward stepwise variable selection had the highest AUC (0.77 (0.72-0.82)) and consisted of ten prognostic factors. The model AUC for the validation cohort was 0.75 (0.70, 0.81), and the calibration intercept and slope were - 0.14 (-0.54, 0.26) and 0.74 (0.53, 0.95) respectively. Classifying patients with a predicted risk of death exceeding 0.30 as high risk, the model would correctly identify 3 out 10 decedents and 9 of 10 survivors. CONCLUSIONS: We developed and validated a prognostic model for one-year mortality in patients with CLD using routinely available administrative data. The model will support clinicians in identifying patients across various CLD etiologies who are at risk of deterioration for a basic palliative care assessment to identify unmet needs and trigger an early referral to palliative medicine. TRIAL REGISTRATION: Not applicable (retrospective study).
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Pneumopatias , Humanos , Feminino , Masculino , Prognóstico , Estudos Retrospectivos , Idoso , Pessoa de Meia-Idade , Pneumopatias/mortalidade , Pneumopatias/diagnóstico , Doença Crônica , Idoso de 80 Anos ou mais , Doença Pulmonar Obstrutiva Crônica/mortalidade , Doença Pulmonar Obstrutiva Crônica/diagnóstico , Cuidados Paliativos , Modelos Logísticos , Doenças Pulmonares Intersticiais/mortalidade , Doenças Pulmonares Intersticiais/diagnósticoRESUMO
BACKGROUND: Matrix metalloproteinase 10 (MMP-10) has a close relationship with carotid atherosclerosis (CAS) and cerebral infarction. The MMP-10 rs17435959 polymorphism causes a leucine to valine transition at codon 4 in exon 1 of the MMP-10 gene and may have functional effects. OBJECTIVES: To investigate the relationship between the MMP-10 rs17435959 polymorphism and the formation and stability of CAS plaques. MATERIALS AND METHODS: The present case-control study contains 738 visitors who came to our health examination center for the first time. According to the carotid ultrasound examinations, visitors were classified into the vulnerable plaque group (41-86 years old, 141 male, 105 female), the stable plaque group (41-86 years old, 141 male, 105 female) and the no plaque group (41-85 years old, 141 male, 105 female). All visitors in the three groups were sex- and- age-matched, and cardiovascular and cerebrovascular diseases were absent. The polymorphism was genotyped by real-time polymerase chain reaction- restriction. RESULTS: Compared to the GG genotype, the frequency of the CC and CG genotypes was significantly more common in the vulnerable plaque group than in the no plaque group (18.7% vs. 7.7%, unadjusted P = 0.002). Moreover, compared to the G allele, the frequency of the C allele was significantly more common in the vulnerable plaque group than in the no plaque group (10.4% vs. 3.9%, unadjusted P = 0.000) and in the vulnerable plaque group than in the stable plaque group (10.4% vs. 5.1%, unadjusted P = 0.008). Binary logistic regression showed that the CC and CG genotype was independent risk factor for the formation (P = 0.019, OR = 1.961, 95% CI [1.117, 3.444]) and vulnerability (P = 0.035, OR = 1.842, 95% CI [1.045, 3.247]) of CAS plaques. Moreover, individuals who have the C allele showed a higher level of fibrinogen, which was an independent risk factor for the formation of CAS plaques (P = 0.000, OR = 2.425, 95% CI [1.475, 3.985]). CONCLUSIONS: The rs17435959 polymorphism was associated with the formation and vulnerability of CAS plaques. Individuals who had variant-type MMP-10 showed higher levels of fibrinogen, which promoted the formation of CAS plaques.
Assuntos
Doenças das Artérias Carótidas/genética , Metaloproteinase 10 da Matriz/genética , Placa Aterosclerótica , Polimorfismo de Nucleotídeo Único , Adulto , Idoso , Idoso de 80 Anos ou mais , Doenças das Artérias Carótidas/diagnóstico por imagem , Doenças das Artérias Carótidas/enzimologia , Estudos de Casos e Controles , Feminino , Fibrinogênio/análise , Frequência do Gene , Estudos de Associação Genética , Predisposição Genética para Doença , Humanos , Masculino , Pessoa de Meia-Idade , Fenótipo , Prognóstico , Medição de Risco , Fatores de Risco , Ruptura EspontâneaRESUMO
In this study, the optimum synthetic process of the Pyracantha polysaccharide-iron (PPI) complex was studied via response surface methodology (RSM). Its antioxidant and anti-cancer activities were also investigated. It was demonstrated that the optimal conditions for the synthetic process of the complex were as follows: a pH of 8.9, a reaction temperature of 70 °C and a trisodium citrate:polysaccharide ratio of 1:2. PPI were analysis by UV, FTIR, SEM, CD, XRD, TGA and NMR. PPI was able to scavenge the metal ion, ABTS and free radicals of the superoxide anion, demonstrating its potential antioxidant activity. PPI was found to display cytotoxicity to Skov3 cells, as shown by its ability to induce apoptosis and alter gene expression in Skov3 cells. These findings show than PPI may represent a novel antioxidant and chemotherapeutic drug.
Assuntos
Antineoplásicos/farmacologia , Produtos Biológicos/farmacologia , Compostos Férricos/farmacologia , Sequestradores de Radicais Livres/farmacologia , Polissacarídeos/farmacologia , Pyracantha/química , Linhagem Celular Tumoral , HumanosRESUMO
OBJECTIVES: Children are vulnerable to Salmonella infection due to their immature immune system. Cases of infection with mcr-1-harbouring Salmonella in child inpatients have not been reported in China before. METHODS: Salmonella isolates from gastroenteritis and bacteraemia were screened using primers targeting mcr-1. Complete genome sequences of mcr-1-harbouring isolates were determined using the PacBio RS II platform. The transferability of mcr-1-harbouring plasmids was verified by conjugation. RESULTS: We investigated two mcr-1-carrying polymyxin-resistant Salmonella enterica serovar Typhimurium ST34 isolates, S61394 and S44712, from bloodstream and intestinal Salmonella infection of two child inpatients, respectively. Both isolates were non-susceptible to commonly used antibiotics for children that compromised the success of clinical treatment and infection control. The mcr-1-harbouring plasmids pLS61394-MCR and pLS44712-MCR (from S61394 and S44712, respectively) were both conjugative pHNSHP45-2-like IncHI2-type epidemic plasmids carrying multiple resistance genes. Compared with pHNSHP45-2, a â¼33 kb insertion region encoding Tn7 transposition protein and heavy metal resistance proteins was identified in pLS61394-MCR, which might enhance adaptation of bacteria carrying this plasmid to various ecological niches. The phylogenetic tree of worldwide mcr-harbouring Salmonella indicated a host preference of mcr and a worldwide and cross-sectoral prevalence of the mcr-positive Salmonella ST34 clone. CONCLUSIONS: To our knowledge, for the first time we report completed whole genomes of mcr-1-positive MDR Salmonella Typhimurium ST34 isolated from infected children in China, suggesting that improved surveillance is imperative for tackling the dissemination of mcr-harbouring MDR Salmonella Typhimurium ST34.
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Antibacterianos/farmacologia , Farmacorresistência Bacteriana Múltipla/genética , Gastroenterite/microbiologia , Infecções por Salmonella/sangue , Salmonella typhimurium/efeitos dos fármacos , Salmonella typhimurium/genética , Criança , China/epidemiologia , Genes Bacterianos , Genoma Bacteriano , Humanos , Masculino , Testes de Sensibilidade Microbiana , Filogenia , Infecções por Salmonella/epidemiologia , Infecções por Salmonella/microbiologia , Sorogrupo , Sequenciamento Completo do GenomaRESUMO
BACKGROUND: Understanding the genetic diversity of candidate genes for malaria vaccines such as circumsporozoite protein (csp) may enhance the development of vaccines for treating Plasmodium knowlesi. Hence, the aim of this study is to investigate the genetic diversity of non-repeat regions of csp in P. knowlesi from Malaysian Borneo and Peninsular Malaysia. METHODS: A total of 46 csp genes were subjected to polymerase chain reaction amplification. The genes were obtained from P. knowlesi isolates collected from different divisions of Sabah, Malaysian Borneo, and Peninsular Malaysia. The targeted gene fragments were cloned into a commercial vector and sequenced, and a phylogenetic tree was constructed while incorporating 168 csp sequences retrieved from the GenBank database. The genetic diversity and natural evolution of the csp sequences were analysed using MEGA6 and DnaSP ver. 5.10.01. A genealogical network of the csp haplotypes was generated using NETWORK ver. 4.6.1.3. RESULTS: The phylogenetic analysis revealed indistinguishable clusters of P. knowlesi isolates across different geographic regions, including Malaysian Borneo and Peninsular Malaysia. Nucleotide analysis showed that the csp non-repeat regions of zoonotic P. knowlesi isolates obtained in this study underwent purifying selection with population expansion, which was supported by extensive haplotype sharing observed between humans and macaques. Novel variations were observed in the C-terminal non-repeat region of csp. CONCLUSIONS: The csp non-repeat regions are relatively conserved and there is no distinct cluster of P. knowlesi isolates from Malaysian Borneo and Peninsular Malaysia. Distinctive variation data obtained in the C-terminal non-repeat region of csp could be beneficial for the design and development of vaccines to treat P. knowlesi.
Assuntos
Variação Genética , Plasmodium knowlesi/genética , Proteínas de Protozoários/genética , Bornéu , MalásiaRESUMO
The structure of amphiphilic spherical brushes, consisting of the nano-SiO2 core, the hyperbranched polyamidoamine subshell, and a grafted layer of long hydrophobically modified polyacrylamide (HMPAM) chains, in aqueous solution was analyzed and described in the framework of the original mean-field approach. The scaling estimations of the hydrodynamic radius of such polymer brushes as a function of the number of grafted macromolecules allow concluding that the HMPAM shells are in a globular state and that the region of the stretched chains adjacent to the grafting surface is a minor part of the grafted macromolecules and does not have a significant impact on the self-assembly of the HMPAM shell caused by the complex hydrophobic-hydrophilic composition of their monomer units. In mean-field theory, the amphiphilic nature of HMPAM was taken into account by attaching the hydrophobic side group H to some fraction of monomer units of the hydrophilic P backbone. The strong attraction of H groups causes the aggregation of macromolecules, whereas the affinity of hydrophilic P groups to solvent forces the aggregates to increase their surface. Due to such effective surface activity, in poor solvent, the grafted amphiphilic macromolecules could form a spherical compacted structure around the nanoparticle or self-assemble into a "hedgehog" structure with several "spines" having hydrophobic core and hydrophilic shell. State diagrams, obtained theoretically, reveal that the "hedgehog" structure is preferable for a wide range of energetic parameters.
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It is well-established that OxyR functions as a transcriptional activator of the peroxide stress response in bacteria, primarily based on studies on Escherichia coli Recent investigations have revealed that OxyRs of some other bacteria can regulate gene expression through both repression and activation or repression only; however, the underlying mechanisms remain largely unknown. Here, we demonstrated in γ-proteobacteriumShewanella oneidensis regulation of OxyR on expression of major catalase gene katB in a dual-control manner through interaction with a single site in the promoter region. Under non-stress conditions, katB expression was repressed by reduced OxyR (OxyRred), whereas when oxidized, OxyR (OxyRoxi) outcompeted OxyRred for the site because of substantially enhanced affinity, resulting in a graded response to oxidative stress, from repression to derepression to activation. The OxyR-binding motif is characterized as a combination of the E. coli motif (tetranucleotides spaced by heptanucleotide) and palindromic structure. We provided evidence to suggest that the S. oneidensis OxyR regulon is significantly contracted compared with those reported, probably containing only five members that are exclusively involved in oxygen reactive species scavenging and iron sequestering. These characteristics probably reflect the adapting strategy of the bacteria that S. oneidensis represents to thrive in redox-stratified microaerobic and anaerobic environments.
Assuntos
Proteínas de Bactérias/metabolismo , Catalase/metabolismo , Regulon , Proteínas Repressoras/metabolismo , Shewanella/genética , Shewanella/metabolismo , Fatores de Transcrição/metabolismo , Adaptação Fisiológica , Proteínas de Bactérias/genética , Regulação Bacteriana da Expressão Gênica , Oxirredução , Estresse Oxidativo , Regiões Promotoras Genéticas , Proteínas Repressoras/genética , Shewanella/crescimento & desenvolvimento , Fatores de Transcrição/genéticaRESUMO
Methamphetamine (METH) is a highly addictive stimulant and METH exposure can induce a series of neuroinflammatory effects. Peli1 is a novel and important E3 ubiquitin-protein ligase contributing to neuroinflammation; targeting Peli1 may thus provide promising therapeutic strategies for neuroinflammation. In addition to the classic MyD88-dependent or MyD88-independent pathways, miRNAs may also be involved in Peli1 modulation. In the present study, two novel miRNAs, miR-142a-3p and miR-155-5p, that were predicted to target Peli1 using bioinformatics were chosen, and their unique roles in METH-induced neuroinflammation via regulating Peli1 expression were identified. Our results showed that miR-142a-3p was significantly reduced in METH-induced neuroinflammation and was negatively associated with Peli1 expression both in BV2 cells and in the brain of mouse. MiR-155-5p was significantly reduced by METH in vitro but increased in vivo. A luciferase reporter assay was performed to reveal that miR-142a-3p and miR-155-5p bound specifically to Peli1, an effect that was completely abolished by the Peli1 binding site mutation. Reciprocally, the overexpression of miR-142a-3p and miR-155-5p could directly suppress Peli1 expression and could protect against the inflammatory effects of METH treatment partially through activating p38 MAPK and NF-κB inflammatory pathways. In conclusion, the present study reveals a novel signaling pathway, the miR-142a-3p/miR-155-5p/Peli1 axis in METH-mediated neuroinflammation, and this pathway could be a potential therapeutic target for METH-mediated neurotoxicity.
Assuntos
Inflamação/prevenção & controle , Metanfetamina/toxicidade , MicroRNAs/metabolismo , Proteínas Nucleares/fisiologia , Ubiquitina-Proteína Ligases/fisiologia , Animais , Encéfalo/efeitos dos fármacos , Encéfalo/metabolismo , Linhagem Celular , Expressão Gênica/genética , Inflamação/induzido quimicamente , Masculino , Camundongos , Camundongos Endogâmicos C57BL , MicroRNAs/genética , Microglia/efeitos dos fármacos , Fármacos Neuroprotetores , Proteínas Nucleares/genética , Transdução de Sinais/efeitos dos fármacos , Transfecção , Ubiquitina-Proteína Ligases/genéticaRESUMO
Accumulating evidence suggests that microglial cells have altered morphology and proliferation in different brain regions of methamphetamine (Meth) abusers and Meth-abusing animal models. However, the possible mechanisms underlying Meth-induced microglial activation remain poorly understood. Meanwhile, Toll-like receptor4 (TLR4) is closely associated with inflammation. Therefore the aim of the present study was to assess whether Meth treatment affects TLR4 expression; in addition, we evaluated the effects of ginkgolide B (GB), a diterpene lactone extracted from Ginkgo biloba, on Meth-mediated inflammation. BV2 cells were treated with Meth. Interestingly, Meth treatment significantly increased TLR4 expression, activated the NF-κB signaling pathway, and promoted TNF-α, IL-6 and IL-1ß excretion. These effects, however, were partially attenuated by GB pre-treatment. To further confirm the role of TLR4 in Meth-mediated inflammation, the siRNA technology was applied to knock down TLR4, which resulted in hampered Meth-mediated inflammatory responses, confirming the important role of TLR4 in this process. Taken together, our findings suggested that Meth exposure results in BV2 cell activation, in association with TLR4 upregulation. GB could attenuate Meth-induced inflammation, at least partially through TLR4-NF-κB signaling pathway, therefore, targeting TLR4 may constitute a potential intervention strategy for Meth mediated neuroinflammation.
Assuntos
Ginkgolídeos/farmacologia , Lactonas/farmacologia , Metanfetamina/farmacologia , Microglia/efeitos dos fármacos , Transdução de Sinais/efeitos dos fármacos , Receptor 4 Toll-Like/efeitos dos fármacos , Animais , Células Cultivadas , Mediadores da Inflamação/metabolismo , Mediadores da Inflamação/farmacologia , Lipopolissacarídeos/farmacologia , NF-kappa B/metabolismo , Receptor 4 Toll-Like/metabolismoRESUMO
Class II fructose-1,6-bisphosphate aldolases (FBA-II) are attractive new targets for the discovery of drugs to combat invasive fungal infection, because they are absent in animals and higher plants. Although several FBA-II inhibitors have been reported, none of these inhibitors exhibit antifungal effect so far. In this study, several novel inhibitors of FBA-II from C. albicans (Ca-FBA-II) with potent antifungal effects were rationally designed by jointly using a specific protocols of molecular docking-based virtual screening, accurate binding-conformation evaluation strategy, synthesis and enzymatic assays. The enzymatic assays reveal that the compounds 3c, 3e-g, 3j and 3k exhibit high inhibitory activity against Ca-FBA-II (IC50 < 10 µM), and the most potential inhibitor is 3g, with IC50 value of 2.7 µM. Importantly, the compounds 3f, 3g, and 3l possess not only high inhibitions against Ca-FBA-II, but also moderate antifungal activities against C. glabrata (MIC80 = 4-64 µg/mL). The compounds 3g, 3l, and 3k in combination with fluconazole (8 µg/mL) displayed significantly synergistic antifungal activities (MIC80 < 0.0625 µg/mL) against resistant Candida strains, which are resistant to azoles drugs. The probable binding modes between 3g and the active site of Ca-FBA-II have been proposed by using the DOX (docking, ONIOM, and XO) strategy. To our knowledge, no FBA-II inhibitors with antifungal activities against wild type and resistant strains from Candida were reported previously. The positive results suggest that the strategy adopted in this study are a promising method for the discovery of novel drugs against azole-resistant fungal pathogens in the future.
Assuntos
Antifúngicos/química , Antifúngicos/farmacologia , Candida albicans/enzimologia , Desenho de Fármacos , Inibidores Enzimáticos/química , Inibidores Enzimáticos/farmacologia , Frutose-Bifosfato Aldolase/antagonistas & inibidores , Candida albicans/efeitos dos fármacos , Frutose-Bifosfato Aldolase/química , Frutose-Bifosfato Aldolase/metabolismo , Frutosedifosfatos/metabolismo , Testes de Sensibilidade Microbiana , Simulação de Dinâmica MolecularRESUMO
Shewanella oneidensis is renowned for its respiratory versatility, which is largely due to abundant c-type cytochromes. Maturation of these proteins depends on a Ccm system encoded by genes in an unusual chromosomal arrangement, but the detailed mechanism is not understood. In this study, we identify SO0265 as CcmI, an apocytochrome c chaperone that is important and essential for maturation of c-type cytochromes with the canonical heme binding motif(s) (HBM; CX(2)CH) and nitrite reductase NrfA carrying a non-canonical CX(2)CK motif respectively. We show that the N-terminal transmembrane segment of CcmI, CcmI-1, is sufficient for maturation of the former but the entire protein is required for maturation of the latter. Although S. oneidensis possesses a heme lyase, SirEFG, dedicated for non-canonical HBMs, it is specific for SirA, a sulfite reductase with a CX(15)CH motif. By presenting evidence that the periplasmic portion of CcmI, CcmI-2, interacts with NrfA, we suggest that CcmI also takes the role of Escherichia coliâ NrfG for chaperoning apo-NrfA for maturation at CX(2)CK. Moreover, intact CcmI is required for maturation of NrfA, presumably by ensuring that heme attachment at canonical HBMs occurs before apoprotein degradation.
Assuntos
Citocromos c/metabolismo , Heme/metabolismo , Nitrito Redutases/metabolismo , Shewanella/metabolismo , Motivos de Aminoácidos , Grupo dos Citocromos c/metabolismo , Escherichia coli/genética , Escherichia coli/metabolismo , Proteínas de Escherichia coli/metabolismo , Liases/metabolismo , Chaperonas Moleculares/metabolismo , Nitrito Redutases/química , Oxirredutases atuantes sobre Doadores de Grupo Enxofre/metabolismo , Periplasma/metabolismo , Estrutura Terciária de Proteína , Shewanella/genéticaRESUMO
UNLABELLED: Hydrogen sulfide (H2S), well known for its toxic properties, has recently become a research focus in bacteria, in part because it has been found to prevent oxidative stress caused by treatment with some antibiotics. H2S has the ability to scavenge reactive oxygen species (ROS), thus preventing oxidative stress, but it is also toxic, leading to conflicting reports of its effects in different organisms. Here, with Shewanella oneidensis as a model, we report that the effects of H2S on the response to oxidative stress are time dependent. When added simultaneously with H2O2, H2S promoted H2O2 toxicity by inactivating catalase, KatB, a heme-containing enzyme involved in H2O2 degradation. Such an inhibitory effect may apply to other heme-containing proteins, such as cytochrome cbb3 oxidase. When H2O2 was supplied 20 min or later after the addition of H2S, the oxidative-stress-responding regulator OxyR was activated, resulting in increased resistance to H2O2. The activation of OxyR was likely triggered by the influx of iron, a response to lowered intracellular iron due to the iron-sequestering property of H2S. Given that Shewanella bacteria thrive in redox-stratified environments that have abundant sulfur and iron species, our results imply that H2S is more important for bacterial survival in such environmental niches than previously believed. IMPORTANCE: Previous studies have demonstrated that H2S is either detrimental or beneficial to bacterial cells. While it can act as a growth-inhibiting molecule by damaging DNA and denaturing proteins, it helps cells to combat oxidative stress. Here we report that H2S indeed has these contrasting biological functions and that its effects are time dependent. Immediately after H2S treatment, there is growth inhibition due to damage of heme-containing proteins, at least to catalase and cytochrome c oxidase. In contrast, when added a certain time later, H2S confers an enhanced ability to combat oxidative stress by activating the H2O2-responding regulator OxyR. Our data reconcile conflicting observations about the functions of H2S.
Assuntos
Sulfeto de Hidrogênio/farmacologia , Estresse Oxidativo/efeitos dos fármacos , Shewanella/efeitos dos fármacos , Shewanella/fisiologia , Proteínas de Bactérias/genética , Proteínas de Bactérias/metabolismo , Regulação Bacteriana da Expressão Gênica/efeitos dos fármacos , Peróxido de Hidrogênio/farmacologia , Ferro/metabolismoRESUMO
UNLABELLED: Oxidative stresses triggered by reactive oxygen species (ROS) that damage various cellular components are unavoidable for virtually all living organisms. In defense, microorganisms have evolved sophisticated mechanisms to sense, respond to, and battle against ROS. Shewanella oneidensis, an important research model for applied and environmental microbes, employs OxyR to mediate the response to H2O2 by derepressing the production of the major H2O2 scavenger KatB as a major means toward these goals. Surprisingly, despite enhanced H2O2 degradation, the oxyR mutant carries a viability deficiency phenotype (plating defect), which can be suppressed by the addition of exogenous iron species. Experiments showed that the defect was not due to iron starvation. Rather, multiple lines of evidence suggested that H2O2 generated abiotically in lysogeny broth (LB) is responsible for the defect by quickly killing mutant cells. We then showed that the iron species suppressed the plating defect by two distinct mechanisms, either as an H2O2 scavenger without involving living cells or as an environmental cue to stimulate an OxyR-independent response to help cells cope with oxidative stress. Based on the suppression of the plating defect by overproduction of H2O2 scavengers in vivo, we propose that cellular components that are vulnerable to H2O2 and responsible for the defect may reside outside the cytoplasm. IMPORTANCE: In bacteria, OxyR is the major regulator controlling the cellular response to H2O2. The loss of OxyR results in reduced viability in many species, but the underlying mechanism is unknown. We showed in S. oneidensis that this defect was due to H2O2 generated abiotically in LB. We then showed that this defect could be corrected by the addition of Fe(2+) or catalase to the LB or increased intracellular production of catalase. Further analyses revealed that Fe(2+) was able not only to decompose H2O2 directly but also to stimulate the activity of OxyR-independent H2O2-scavenging enzymes. Our data indicate that iron species play a previously underappreciated role in protecting cells from H2O2 in environments.
Assuntos
Proteínas de Bactérias/metabolismo , Regulação Bacteriana da Expressão Gênica/fisiologia , Proteínas Repressoras/metabolismo , Shewanella/metabolismo , Proteínas de Bactérias/genética , Catalase/metabolismo , Deleção de Genes , Peróxido de Hidrogênio/metabolismo , Ferro , Estresse Oxidativo , Espécies Reativas de Oxigênio/metabolismo , Proteínas Repressoras/genética , Shewanella/genéticaRESUMO
Recent studies have failed to demonstrate a causal cardioprotective effect of HDL cholesterol levels, shifting focus to the functional aspects of HDL. Phospholipid transfer protein (PLTP) is an HDL-associated protein involved in reverse cholesterol transport. This study sought to determine the genetic and nongenetic predictors of plasma PLTP activity (PLTPa), and separately, to determine whether PLTPa predicted carotid artery disease (CAAD). PLTPa was measured in 1,115 European ancestry participants from a case-control study of CAAD. A multivariate logistic regression model was used to elucidate the relationship between PLTPa and CAAD. Separately, a stepwise linear regression determined the nongenetic clinical and laboratory characteristics that best predicted PLTPa. A final stepwise regression considering both nongenetic and genetic variables identified the combination of covariates that explained maximal PLTPa variance. PLTPa was significantly associated with CAAD (7.90 × 10(-9)), with a 9% decrease in odds of CAAD per 1 unit increase in PLTPa (odds ratio = 0.91). Triglyceride levels (P = 0.0042), diabetes (P = 7.28 × 10(-5)), paraoxonase 1 (PON1) activity (P = 0.019), statin use (P = 0.026), PLTP SNP rs4810479 (P = 6.38 × 10(-7)), and PCIF1 SNP rs181914932 (P = 0.041) were all significantly associated with PLTPa. PLTPa is significantly inversely correlated with CAAD. Furthermore, we report a novel association between PLTPa and PON1 activity, a known predictor of CAAD.
Assuntos
Arildialquilfosfatase/metabolismo , Doenças das Artérias Carótidas/genética , Doenças das Artérias Carótidas/metabolismo , Proteínas de Transferência de Fosfolipídeos/genética , Proteínas de Transferência de Fosfolipídeos/metabolismo , Polimorfismo de Nucleotídeo Único , Idoso , Doenças das Artérias Carótidas/sangue , Doenças das Artérias Carótidas/enzimologia , Estudos de Casos e Controles , Feminino , Humanos , Lipídeos/sangue , Masculino , Análise MultivariadaRESUMO
BACKGROUND: MMP 14 is expressed in atherosclerotic plaques and potentially plays an important role in the development of vulnerable carotid plaques. MMP 14 gene polymorphisms can influence the bioactivity or expression of MMP 14. OBJECTIVE: The aim of this study was to investigate the association between MMP 14 position + 7096 T > C (NM_004995.2:c.855T> C, rs2236307) polymorphism and vulnerable carotid plaque formation. METHODS: 1370 patients with ischemic cerebral infarctions were enrolled and divided into three groups according to their carotid ultrasound examination: No plaque group (n = 346), stable plaque group (n = 695) and vulnerable plaque group (n = 329). The traditional atherosclerosis risk factors were recorded, and the MMP 14 polymorphism were genotyped by Applied Biosystems 7300 Real-Time PCR System using the TaqMan assay. RESULTS: In the multiple logistic regression analysis done among the sub-groups, compared to no carotid plaque group, individuals with the MMP 14 position + 7096 TC+ CC genotype showed a significantly (p = 0.009) lower risk for vulnerable plaque (AOR = 0.675; 95% CI, 0.568-0.922) formation compared with subjects of the TT genotype; however, no relation between TC+ CC genotype and stable carotid plaque was observed (p > 0.125). Age was a risk factor for both stable plaque (p = 0.000; AOR = 3.732; 95% CI: 2.496-5.58) and vulnerable plaque formation (p = 0.001; AOR = 2.234; 95% CI: 1.387-3.597). Meanwhile, fibrinogen (> 4.0 g/L) was a risk factor for stable plaque (p = 0.004; AOR = 2.313; 95% CI: 1.308-4.091). CONCLUSIONS: The MMP 14 position + 7096 TC+ CC genotype might lower the risk of vulnerable carotid plaque formation. Fibrinogen (> 4.0 g/L) was a risk factor for stable plaque.
Assuntos
Aterosclerose/genética , Infarto Cerebral/genética , Metaloproteinase 14 da Matriz/genética , Placa Aterosclerótica/genética , Polimorfismo Genético , Fatores Etários , Idoso , Povo Asiático , Aterosclerose/sangue , Aterosclerose/diagnóstico , Aterosclerose/etnologia , Biomarcadores/sangue , Artérias Carótidas/metabolismo , Artérias Carótidas/patologia , Infarto Cerebral/sangue , Infarto Cerebral/diagnóstico , Infarto Cerebral/etnologia , Feminino , Fibrinogênio/metabolismo , Expressão Gênica , Predisposição Genética para Doença , Humanos , Masculino , Pessoa de Meia-Idade , Placa Aterosclerótica/sangue , Placa Aterosclerótica/diagnóstico , Placa Aterosclerótica/etnologia , Fatores de RiscoRESUMO
Fractional exhaled nitric oxide (FENO) measurement is a useful diagnostic test of airway inflammation. However, there have been few studies of FENO in workers exposed to nanomaterials. The purpose of this study was to examine the effect of nanoparticle (NP) exposure on FENO and to assess whether the FENO is increased in workers exposed to nanomaterials (NM). In this study, both exposed workers and non-exposed controls were recruited from NM handling plants in Taiwan. A total of 437 subjects (exposed group = 241, non-exposed group = 196) completed the FENO and spirometric measurements from 2009-2011. The authors used a control-banding (CB) matrix to categorize the risk level of each participant. In a multivariate linear regression analysis, this study found a significant association between risk level 2 of NP exposure and FENO. Furthermore, asthma, allergic rhinitis, peak expiratory flow rate (PEFR), and NF-κB were also significantly associated with FENO. When the multivariate logistic regression model was adjusted for confounders, nano-TiO2 in all of the NM exposed categories had a significantly increased risk in FENO > 35 ppb. This study found associations between the risk level of NP exposure and FENO (particularly noteworthy for Nano-TiO2). Monitoring FENO in the lung could open up a window into the role nitric oxide (NO) may play in pathogenesis.
Assuntos
Exposição por Inalação , Nanopartículas/toxicidade , Óxido Nítrico/análise , Exposição Ocupacional , Adulto , Asma/epidemiologia , Testes Respiratórios , Expiração , Feminino , Humanos , Masculino , NF-kappa B/análise , Rinite Alérgica , Rinite Alérgica Perene/epidemiologiaRESUMO
Exosomes have been identified as optimal biomarkers to screen for multiple diseases. However, few studies focus on the abundant exosome population isolated from plasma of migraine. This study investigated whether proteins in abundant exosomes can aid in the diagnosis of chronic migraine (CM). Plasma exosomes were collected by centrifugation, from which protein samples were extracted. A pilot study (CM, 18; episodic migraine (EM), 26) followed by a second dataset (CM, 26; EM, 16; tension-type headache (TTH), 20; control, 22) was applied to establish a diagnostic model of CM. We employed proteomics based on liquid chromatography-tandem mass spectrometry (LC-MS/MS) to search for potential candidate biomarkers in plasma exosomes from CM patients. In total, 530 proteins in plasma exosomes were co-detected. Among them, 13 proteins were found significantly dysregulated between the plasma exosomes of CM patients and other groups. The receiver operating characteristic curve analysis revealed a combination of six proteins (upregulated: RAP2B, AK1, BID, DAG1, PICALM, PSMB2) could distinguish CM patients with high accuracy. Linear correlation analysis showed that the combination was significantly correlated with Headache Impact Test (HIT-6) scores (assessing the negative impact of headaches on normal daily activity). The RT-qPCR results showed the same trends in CM models with nitroglycerin as the exosomal protein sequencing results. These data revealed dysregulated proteins in plasma exosomes of CM, and the combination of plasma exosomal proteins RAP2B, AK1, BID, DAG1, PICALM, and PSMB2 could serve as a novel candidate biomarker for CM diagnosis.