RESUMO
While acute myeloid leukemia (AML) comprises many disparate genetic subtypes, one shared hallmark is the arrest of leukemic myeloblasts at an immature and self-renewing stage of development. Therapies that overcome differentiation arrest represent a powerful treatment strategy. We leveraged the observation that the majority of AML, despite their genetically heterogeneity, share in the expression of HoxA9, a gene normally downregulated during myeloid differentiation. Using a conditional HoxA9 model system, we performed a high-throughput phenotypic screen and defined compounds that overcame differentiation blockade. Target identification led to the unanticipated discovery that inhibition of the enzyme dihydroorotate dehydrogenase (DHODH) enables myeloid differentiation in human and mouse AML models. In vivo, DHODH inhibitors reduced leukemic cell burden, decreased levels of leukemia-initiating cells, and improved survival. These data demonstrate the role of DHODH as a metabolic regulator of differentiation and point to its inhibition as a strategy for overcoming differentiation blockade in AML.
Assuntos
Antineoplásicos/uso terapêutico , Inibidores Enzimáticos/uso terapêutico , Leucemia Mieloide Aguda/tratamento farmacológico , Leucemia Mieloide Aguda/patologia , Terapia de Alvo Molecular , Oxirredutases atuantes sobre Doadores de Grupo CH-CH/antagonistas & inibidores , Animais , Antineoplásicos/química , Antineoplásicos/isolamento & purificação , Diferenciação Celular , Di-Hidro-Orotato Desidrogenase , Inibidores Enzimáticos/química , Inibidores Enzimáticos/isolamento & purificação , Ensaios de Triagem em Larga Escala , Proteínas de Homeodomínio/genética , Humanos , Leucemia Mieloide Aguda/genética , Camundongos , Células Mieloides/patologia , Oxirredutases atuantes sobre Doadores de Grupo CH-CH/metabolismo , Pirimidinas/metabolismo , Bibliotecas de Moléculas Pequenas/química , Bibliotecas de Moléculas Pequenas/isolamento & purificação , Bibliotecas de Moléculas Pequenas/uso terapêutico , Ensaios Antitumorais Modelo de XenoenxertoRESUMO
BACKGROUND: The main antibiotics used against Helicobacter pylori have been chosen empirically over time, with few preclinical studies to provide support. The rise in resistance to some of these antibiotics is prompting a reassessment of their use. This work aimed to evaluate the in vitro efficacy of 2 × 2 combinations of the most widely used antibiotics against H. pylori. MATERIALS AND METHODS: J99 reference strains and 19 clinical isolates of H. pylori with various antibiotic resistance phenotypes were used. Minimum inhibitory concentrations were carried out using the microdilution method in 96-well plates. The activity of 15 possible combinations of two antibiotics including amoxicillin, clarithromycin (CLA), levofloxacin, rifampicin, tetracycline, and metronidazole was determined for all strains by the checkerboard method. A mean fractional inhibitory concentration index (FICmean) was calculated for each combination and strain and the type of pharmacodynamic interaction was considered as synergic if FICmean ≤ 0.5, additive if 0.5 < FICmean ≤ 1, indifferent if 1 < FICmean < 4 or antagonistic if FICmean ≥ 4. RESULTS: Most of the 285 pharmacodynamic interactions tested with clinical strains were close to additivity (average FICmean = 0.89 [0.38-1.28]). No interaction was found to be antagonistic. When two antibiotics to which a strain was resistant were combined, the concentrations required to inhibit bacterial growth were higher than their respective breakpoints. CONCLUSION: The present results have shown that in vitro, the different antibiotics used in therapeutics have additive effects. The addition of the effects of two antibiotics to which a strain was resistant was not sufficient to inhibit bacterial growth. In probabilistic treatment, the choice of antibiotics to combine should therefore be based on the local epidemiology of resistance, and on susceptibility testing in the case of CLA therapy, so that at least one antibiotic to which the strain is susceptible is used.
Assuntos
Antibacterianos , Infecções por Helicobacter , Helicobacter pylori , Testes de Sensibilidade Microbiana , Helicobacter pylori/efeitos dos fármacos , Antibacterianos/farmacologia , Antibacterianos/uso terapêutico , Humanos , Infecções por Helicobacter/tratamento farmacológico , Infecções por Helicobacter/microbiologia , Farmacorresistência Bacteriana , Quimioterapia Combinada , Sinergismo FarmacológicoRESUMO
BACKGROUND: Meyerozyma guilliermondii is a yeast species responsible for invasive fungal infections. It has high minimum inhibitory concentrations (MICs) to echinocandins, the first-line treatment of candidemia. In this context, azole antifungal agents are frequently used. However, in recent years, a number of azole-resistant strains have been described. Their mechanisms of resistance are currently poorly studied. OBJECTIVE: The aim of this study was consequently to understand the mechanisms of azole resistance in several clinical isolates of M. guilliermondii. METHODS: Ten isolates of M. guilliermondii and the ATCC 6260 reference strain were studied. MICs of azoles were determined first. Whole genome sequencing of the isolates was then carried out and the mutations identified in ERG11 were expressed in a CTG clade yeast model (C. lusitaniae). RNA expression of ERG11, MDR1 and CDR1 was evaluated by quantitative PCR. A phylogenic analysis was developed and performed on M. guilliermondii isolates. Lastly, in vitro experiments on fitness cost and virulence were carried out. RESULTS: Of the ten isolates tested, three showed pan-azole resistance. A combination of F126L and L505F mutations in Erg11 was highlighted in these three isolates. Interestingly, a combination of these two mutations was necessary to confer azole resistance. An overexpression of the Cdr1 efflux pump was also evidenced in one strain. Moreover, the three pan-azole-resistant isolates were shown to be genetically related and not associated with a fitness cost or a lower virulence, suggesting a possible clonal transmission. CONCLUSION: In conclusion, this study identified an original combination of ERG11 mutations responsible for pan-azole-resistance in M. guilliermondii. Moreover, we proposed a new MLST analysis for M. guilliermondii that identified possible clonal transmission of pan-azole-resistant strains. Future studies are needed to investigate the distribution of this clone in hospital environment and should lead to the reconsideration of the treatment for this species.
Assuntos
Azóis , Farmacorresistência Fúngica , Saccharomycetales , Humanos , Azóis/farmacologia , Tipagem de Sequências Multilocus , Farmacorresistência Fúngica/genética , Antifúngicos/farmacologia , Mutação , Testes de Sensibilidade Microbiana , Fluconazol/farmacologiaRESUMO
Gram-negative bacterial pathogens have an outer membrane that restricts entry of molecules into the cell. Water-filled protein channels in the outer membrane, so-called porins, facilitate nutrient uptake and are thought to enable antibiotic entry. Here, we determined the role of porins in a major pathogen, Pseudomonas aeruginosa, by constructing a strain lacking all 40 identifiable porins and 15 strains carrying only a single unique type of porin and characterizing these strains with NMR metabolomics and antimicrobial susceptibility assays. In contrast to common assumptions, all porins were dispensable for Pseudomonas growth in rich medium and consumption of diverse hydrophilic nutrients. However, preferred nutrients with two or more carboxylate groups such as succinate and citrate permeated poorly in the absence of porins. Porins provided efficient translocation pathways for these nutrients with broad and overlapping substrate selectivity while efficiently excluding all tested antibiotics except carbapenems, which partially entered through OprD. Porin-independent permeation of antibiotics through the outer-membrane lipid bilayer was hampered by carboxylate groups, consistent with our nutrient data. Together, these results challenge common assumptions about the role of porins by demonstrating porin-independent permeation of the outer-membrane lipid bilayer as a major pathway for nutrient and drug entry into the bacterial cell.
Assuntos
Antibacterianos/metabolismo , Membrana Celular/fisiologia , Nutrientes/metabolismo , Porinas/metabolismo , Pseudomonas aeruginosa/fisiologia , Proteínas da Membrana Bacteriana Externa/metabolismo , Transporte Biológico/fisiologia , Permeabilidade da Membrana CelularRESUMO
Lab managers and users of scanning electron microscope or electron probe microanalyzer facilities aiming for qualitative or quantitative X-ray analyses require comprehensive, yet flexible documentation structures for their daily work and available reference material, with a complete X-ray data library, a repository of energy- and wavelength-dispersive spectra, and an instrument scheduling mechanism. An online multilaboratory database system available at https://de-ma.ch is presented with the primary goals of providing information on microanalytical reference materials, analytical setups, characteristic X-ray data, and for managing reservation and training requests. This website is designed for multiuser facilities, where experience ranges from beginners to expert users. Registered users will find these tools useful in developing and maintaining high-quality, reproducible, and efficient analyses, whereas lab managers will keep records of their microanalytical reference material database and analytical protocols. The database also serves an educational purpose by (a) providing information on reference materials, (b) encouraging students to select appropriate X-ray lines to analyze, (c) providing analytical setups for point analysis or mapping, (d) identifying unknown X-ray lines, (e) displaying energy- or wavelength-dispersive spectra, and (f) recalculating mineral formula from quantitative wt% analysis results, based on a number of oxygen atoms or cations.
RESUMO
Polycythemia vera (PV) and essential thrombocythemia (ET) are myeloproliferative neoplasms (MPN) characterized by clonal erythrocytosis and thrombocytosis, respectively. The main goal of therapy in PV and ET is to prevent thrombohemorrhagic complications. Despite a debated notion that red blood cells (RBCs) play a passive and minor role in thrombosis, there has been increasing evidence over the past decades that RBCs may play a biological and clinical role in PV and ET pathophysiology. This review summarizes the main mechanisms that suggest the involvement of PV and ET RBCs in thrombosis, including quantitative and qualitative RBC abnormalities reported in these pathologies. Among these abnormalities, we discuss increased RBC counts and hematocrit, that modulate blood rheology by increasing viscosity, as well as qualitative changes, such as deformability, aggregation, expression of adhesion proteins and phosphatidylserine and release of extracellular microvesicles. While the direct relationship between a high red cell count and thrombosis is well-known, the intrinsic defects of RBCs from PV and ET patients are new contributors that need to be investigated in depth in order to elucidate their role and pave the way for new therapeutical strategies.
Assuntos
Policitemia Vera , Trombocitemia Essencial , Trombocitose , Trombose , Humanos , Trombocitemia Essencial/complicações , Trombose/complicações , Trombocitose/patologia , Eritrócitos/patologiaRESUMO
A double ampC (AmpCG183D) and ampD (AmpDH157Y) genes mutations have been identified by whole genome sequencing in a Pseudomonas aeruginosa (PaS) that became resistant (PaR) in a patient treated by ceftolozane/tazobactam (C/T). To precisely characterize the respective contributions of these mutations on the decreased susceptibility to C/T and on the parallel increased susceptibility to imipenem (IMI), mutants were generated by homologous recombination in PAO1 reference strain (PAO1- AmpCG183D, PAO1-AmpDH157Y, PAO1-AmpCG183D/AmpDH157Y) and in PaR (PaR-AmpCPaS/AmpDPaS). Sequential time-kill curve experiments were conducted on all strains and analyzed by semi-mechanistic PKPD modeling. A PKPD model with adaptation successfully described the data, allowing discrimination between initial and time-related (adaptive resistance) effects of mutations. With PAO1 and mutant-derived strains, initial EC50 values increased by 1.4, 4.1, and 29-fold after AmpCG183D , AmpDH157Y and AmpCG183D/AmpDH157Y mutations, respectively. EC50 values were increased by 320, 12.4, and 55-fold at the end of the 2 nd experiment. EC50 of PAO1-AmpCG183D/AmpDH157Y was higher than that of single mutants at any time of the experiments. Within the PaR clinical background, reversal of AmpCG183D, and AmpDH157Y mutations led to an important decrease of EC50 value, from 80.5 mg/L to 6.77 mg/L for PaR and PaR-AmpCPaS/AmpDPaS, respectively. The effect of mutations on IMI susceptibility mainly showed that the AmpCG183D mutation prevented the emergence of adaptive resistance. The model successfully described the separate and combined effect of AmpCG183D and AmpDH157Y mutations against C/T and IMI, allowing discrimination and quantification of the initial and time-related effects of mutations. This method could be reproduced in clinical strains to decipher complex resistance mechanisms.
Assuntos
Farmacorresistência Bacteriana , Pseudomonas aeruginosa , Humanos , Antibacterianos/farmacologia , Proteínas de Bactérias/genética , beta-Lactamases/farmacologia , Cefalosporinas/farmacologia , Imipenem/farmacologia , Testes de Sensibilidade Microbiana , Mutação , Pseudomonas aeruginosa/efeitos dos fármacos , Pseudomonas aeruginosa/genética , Infecções por Pseudomonas/tratamento farmacológico , Tazobactam/farmacologia , Farmacorresistência Bacteriana/genéticaRESUMO
The inoculum effect (i.e., reduction in antimicrobial activity at large starting inoculum) is a phenomenon described for various pathogens. Given that limited data exist regarding inoculum effect of Acinetobacter baumannii, we evaluated killing of A. baumannii by polymyxin B, a last-resort antibiotic, at several starting inocula and developed a pharmacokinetic-pharmacodynamic (PKPD) model to capture this phenomenon. In vitro static time-kill experiments were performed using polymyxin B at concentrations ranging from 0.125 to 128 mg/L against a clinical A. baumannii isolate at four starting inocula from 105 to 108 CFU/mL. Samples were collected up to 30 h to quantify the viable bacterial burden and were simultaneously modeled in the NONMEM software program. The expression of polymyxin B resistance genes (lpxACD, pmrCAB, and wzc), and genetic modifications were studied by RT-qPCR and DNA sequencing experiments, respectively. The PKPD model included a single homogeneous bacterial population with adaptive resistance. Polymyxin B effect was modeled as a sigmoidal Emax model and the inoculum effect as an increase of polymyxin B EC50 with increasing starting inoculum using a power function. Polymyxin B displayed a reduced activity as the starting inoculum increased: a 20-fold increase of polymyxin B EC50 was observed between the lowest and the highest inoculum. No effects of polymyxin B and inoculum size were observed on the studied genes. The proposed PKPD model successfully described and predicted the pronounced in vitro inoculum effect of A. baumannii on polymyxin B activity. These results should be further validated using other bacteria/antibiotic combinations and in vivo models.
Assuntos
Acinetobacter baumannii , Polimixina B , Acinetobacter baumannii/genética , Antibacterianos/farmacologia , Farmacorresistência Bacteriana Múltipla , Sinergismo Farmacológico , Testes de Sensibilidade Microbiana , Polimixina B/farmacologiaRESUMO
Sperm develop from puberty in the seminiferous tubules, inside the blood-testis barrier to prevent their recognition as "non-self" by the immune system, and it is widely assumed that human sperm-specific proteins cannot access the circulatory or immune systems. Sperm-specific proteins aberrantly expressed in cancer, known as cancer-testis antigens (CTAs), are often pursued as cancer biomarkers and therapeutic targets based on the assumption they are neoantigens absent from the circulation in healthy men. Here, we identify a wide range of germ cell-derived and sperm-specific proteins, including multiple CTAs, that are selectively deposited by the Sertoli cells of the adult mouse and human seminiferous tubules into testicular interstitial fluid (TIF) that is "outside" the blood-testis barrier. From TIF, the proteins can access the circulatory- and immune systems. Disruption of spermatogenesis decreases the abundance of these proteins in mouse TIF, and a sperm-specific CTA is significantly decreased in TIF from infertile men, suggesting that exposure of certain CTAs to the immune system could depend on fertility status. The results provide a rationale for the development of blood-based tests useful in the management of male infertility and indicate CTA candidates for cancer immunotherapy and biomarker development that could show sex-specific and male-fertility-related responses.
Assuntos
Antígenos de Neoplasias/análise , Proteínas/análise , Túbulos Seminíferos/metabolismo , Espermatozoides/química , Animais , Barreira Hematotesticular , Líquido Extracelular/química , Humanos , Imunoterapia , Infertilidade Masculina/metabolismo , Masculino , Camundongos , Neoplasias/terapia , Proteoma , Células de Sertoli/fisiologia , Espermatogênese , Testículo/metabolismoRESUMO
Grasp55 is a ubiquitous Golgi stacking protein involved in autophagy, protein trafficking, and glucose deprivation sensing. The function of Grasp55 in protein trafficking has been attributed to its PDZ-mediated interaction with the C-terminal PDZ-binding motifs of protein cargos. We have recently shown that such an interaction occurs between Grasp55 and the adhesion molecule Jam-C, which plays a central role in stemness maintenance of hematopoietic and spermatogenic cells. Accordingly, we have found that Grasp55-deficient mice suffer from spermatogenesis defects similar to Jam-C knockout mice. However, whether Grasp55 is involved in the maintenance of immunohematopoietic homeostasis through regulation of protein transport and Jam-C expression remains unknown. In this study, we show that Grasp55 deficiency does not affect hematopoietic stem cell differentiation, engraftment, or mobilization, which are known to depend on expression of Grasp55-dependent protein cargos. In contrast, using an Myc-dependent leukemic model addicted to autophagy, we show that knockdown of Grasp55 in leukemic cells reduces spleen and bone marrow tumor burden upon i.v. leukemic engraftment. This is not due to reduced homing of Grasp55-deficient cells to these organs but to increased spontaneous apoptosis of Grasp55-deficient leukemic cells correlated with increased sensitivity of the cells to glucose deprivation. These results show that Grasp55 plays a role in Myc-transformed hematopoietic cells but not in normal hematopoietic cells in vivo.
Assuntos
Complexo de Golgi/patologia , Proteínas da Matriz do Complexo de Golgi/metabolismo , Leucemia/metabolismo , Animais , Apoptose/genética , Autofagia , Carcinogênese , Sobrevivência Celular , Proteínas da Matriz do Complexo de Golgi/genética , Hematopoese/genética , Leucemia/patologia , Camundongos , Camundongos Endogâmicos C57BL , Camundongos Knockout , Transporte Proteico , Proteínas Proto-Oncogênicas c-myc/metabolismo , Carga TumoralRESUMO
Male fertility is dependent on spermatogonial stem cells (SSCs) that self-renew and produce differentiating germ cells. Growth factors produced within the testis are essential for SSC maintenance but intrinsic factors that dictate the SSC response to these stimuli are poorly characterised. Here, we have studied the role of GILZ, a TSC22D family protein and spermatogenesis regulator, in spermatogonial function and signalling. Although broadly expressed in the germline, GILZ was prominent in undifferentiated spermatogonia and Gilz deletion in adults resulted in exhaustion of the GFRα1+ SSC-containing population and germline degeneration. GILZ loss was associated with mTORC1 activation, suggesting enhanced growth factor signalling. Expression of deubiquitylase USP9X, an mTORC1 modulator required for spermatogenesis, was disrupted in Gilz mutants. Treatment with an mTOR inhibitor rescued GFRα1+ spermatogonial failure, indicating that GILZ-dependent mTORC1 inhibition is crucial for SSC maintenance. Analysis of cultured undifferentiated spermatogonia lacking GILZ confirmed aberrant activation of ERK MAPK upstream mTORC1 plus USP9X downregulation and interaction of GILZ with TSC22D proteins. Our data indicate an essential role for GILZ-TSC22D complexes in ensuring the appropriate response of undifferentiated spermatogonia to growth factors via distinct inputs to mTORC1.
Assuntos
Alvo Mecanístico do Complexo 1 de Rapamicina/metabolismo , Espermatogênese/fisiologia , Espermatogônias/citologia , Fatores de Transcrição/metabolismo , Animais , Células Cultivadas , Proteínas de Ligação a DNA , Endopeptidases/biossíntese , Regulação da Expressão Gênica no Desenvolvimento/genética , Receptores de Fator Neurotrófico Derivado de Linhagem de Célula Glial/metabolismo , Infertilidade Masculina/genética , Masculino , Alvo Mecanístico do Complexo 1 de Rapamicina/antagonistas & inibidores , Camundongos , Camundongos Endogâmicos C57BL , Camundongos Knockout , Espermatogênese/genética , Células-Tronco/citologia , Ubiquitina TiolesteraseRESUMO
Mammalian spermatogenesis is a tightly coordinated process that gives rise to mature spermatozoa capable of fertilising an ovum during sexual reproduction. A population of stem and progenitor cells known as undifferentiated spermatogonia enables continual spermatogenesis throughout life. A complex transcriptional network that balances self-renewal of spermatogonia with their timely differentiation in order to maintain constant fertility regulates this process. Importantly, post-transcriptional regulation of gene expression plays a critical role in spermatogenesis, necessitated by the profound genetic and morphological changes that occur during meiosis and sperm maturation. Pre-mRNA splicing, mRNA export, maintenance of transcript stability and translation are key RNA processing steps that are regulated in the male germline to maintain coordinated gene expression. In this review, we examine these processes in the context of mammalian spermatogenesis and provide an overview of key mediators at each step.
Assuntos
Precursores de RNA/genética , Processamento Pós-Transcricional do RNA , Espermatogênese/genética , Espermatogônias/metabolismo , Animais , Diferenciação Celular/genética , Fertilidade/genética , Humanos , Masculino , Espermatogônias/citologia , Células-Tronco/citologia , Células-Tronco/metabolismoRESUMO
In neuroblastoma (NB), genetic alterations in chromatin remodeling (CRGs) and epigenetic modifier genes (EMGs) have been described. We sought to determine their frequency and clinical impact. Whole exome (WES)/whole genome sequencing (WGS) data and targeted sequencing (TSCA®) of exonic regions of 33 CRGs/EMGs were analyzed in tumor samples from 283 NB patients, with constitutional material available for 55 patients. The frequency of CRG/EMG variations in NB cases was then compared to the Genome Aggregation Database (gnomAD). The sequencing revealed SNVs/small InDels or focal CNAs of CRGs/EMGs in 20% (56/283) of all cases, occurring at a somatic level in 4 (7.2%), at a germline level in 12 (22%) cases, whereas for the remaining cases, only tumor material could be analyzed. The most frequently altered genes were ATRX (5%), SMARCA4 (2.5%), MLL3 (2.5%) and ARID1B (2.5%). Double events (SNVs/small InDels/CNAs associated with LOH) were observed in SMARCA4 (n = 3), ATRX (n = 1) and PBRM1 (n = 1). Among the 60 variations, 24 (8.4%) targeted domains of functional importance for chromatin remodeling or highly conserved domains but of unknown function. Variations in SMARCA4 and ATRX occurred more frequently in the NB as compared to the gnomAD control cohort (OR = 4.49, 95%CI: 1.63-9.97, p = 0.038; OR 3.44, 95%CI: 1.46-6.91, p = 0.043, respectively). Cases with CRG/EMG variations showed a poorer overall survival compared to cases without variations. Genetic variations of CRGs/EMGs with likely functional impact were observed in 8.4% (24/283) of NB. Our case-control approach suggests a role of SMARCA4 as a player of NB oncogenesis.
Assuntos
Carcinogênese/genética , Montagem e Desmontagem da Cromatina/genética , DNA Helicases/genética , Neuroblastoma/genética , Proteínas Nucleares/genética , Fatores de Transcrição/genética , Adolescente , Estudos de Casos e Controles , Criança , Pré-Escolar , Variações do Número de Cópias de DNA , Éxons/genética , Feminino , Mutação em Linhagem Germinativa , Humanos , Mutação INDEL , Lactente , Recém-Nascido , Estimativa de Kaplan-Meier , Masculino , Neuroblastoma/mortalidade , Neuroblastoma/patologia , Polimorfismo de Nucleotídeo Único , Intervalo Livre de Progressão , Sequenciamento do Exoma , Proteína Nuclear Ligada ao X/genéticaRESUMO
Mycobacterium abscessus is responsible for difficult-to-treat chronic pulmonary infections in humans. Current regimens, including parenteral administrations of cefoxitin (FOX) in combination with amikacin and clarithromycin, raise compliance problems and are frequently associated with high failure and development of resistance. Aerosol delivery of FOX could be an interesting alternative. FOX was administered to healthy rats by intravenous bolus or intratracheal nebulization, and concentrations were determined in plasma and epithelial lining fluid (ELF) by liquid chromatography-tandem mass spectrometry. After intrapulmonary administration, the FOX area under the curve within ELF was 1,147 times higher than that in plasma, indicating that this route of administration offers a biopharmaceutical advantage over intravenous administration. FOX antimicrobial activity was investigated using time-kill curves combined with a pharmacokinetic/pharmacodynamic (PK/PD) type modeling approach in order to account for its in vitro instability that precludes precise determination of MIC. Time-kill data were adequately described by a model including in vitro degradation, a sensitive (S) and a resistant (R) bacteria subpopulation, logistic growth, and a maximal inhibition-type growth inhibition effect of FOX. Median inhibitory concentrations were estimated at 16.2 and 252 mg/liter for the S and R subpopulations, respectively. These findings suggest that parenteral FOX dosing regimens used in patients for the treatment of M. abscessus are not sufficient to reduce the bacterial burden and that FOX nebulization offers a potential advantage that needs to be further investigated.
Assuntos
Antibacterianos/farmacologia , Cefoxitina/farmacocinética , Cefoxitina/uso terapêutico , Infecções por Mycobacterium não Tuberculosas/tratamento farmacológico , Mycobacterium abscessus/efeitos dos fármacos , Administração Intravenosa/métodos , Animais , Antibacterianos/farmacocinética , Claritromicina/farmacocinética , Claritromicina/uso terapêutico , Masculino , Testes de Sensibilidade Microbiana/métodos , Infecções por Mycobacterium não Tuberculosas/microbiologia , Ratos , Ratos Sprague-Dawley , Infecções Respiratórias/tratamento farmacológico , Infecções Respiratórias/microbiologiaRESUMO
We study quantum metrology for unitary dynamics. Analytic solutions are given for both the optimal unitary state preparation starting from an arbitrary mixed state and the corresponding optimal measurement precision. This represents a rigorous generalization of known results for optimal initial states and upper bounds on measurement precision which can only be saturated if pure states are available. In particular, we provide a generalization to mixed states of an upper bound on measurement precision for time-dependent Hamiltonians that can be saturated with optimal Hamiltonian control. These results make precise and reveal the full potential of mixed states for quantum metrology.
RESUMO
Electron microprobe trace element analysis is a significant challenge. Due to the low net intensity of peak measurements, the accuracy and precision of such analyses relies critically on background measurements, and on the accuracy of any pertinent peak interference corrections. A linear regression between two points selected at appropriate background positions is a classical approach for electron probe microanalysis (EPMA). However, this approach neglects the accurate assessment of background curvature (exponential or polynomial), and the presence of background interferences, a hole in the background, or an absorption edge can dramatically affect the results if underestimated or ignored. The acquisition of a quantitative wavelength-dispersive spectrometry (WDS) scan over the spectral region of interest remains a reasonable option to determine the background intensity and curvature from a fitted regression of background portions of the scan, but this technique can be time consuming and retains an element of subjectivity, as the analyst has to select areas in the scan which appear to represent background. This paper presents a new multi-point background (MPB) method whereby the background intensity is determined from up to 24 background measurements from wavelength positions on either side of analytical lines. This method improves the accuracy and precision of trace element analysis in a complex matrix through careful regression of the background shape, and can be used to characterize the background over a large spectral region covering several elements to be analyzed. The overall efficiency improves as systematic WDS scanning is not required to assess background interferences. The method is less subjective compared to methods that rely on WDS scanning, including selection of two interpolation points based on WDS scans, because "true" backgrounds are selected through an exclusion method of possible erroneous backgrounds. The first validation of the MPB method involves blank testing to ensure the method can accurately measure the absence of an element. The second validation involves the analysis of U-Th-Pb in several monazite reference materials of known isotopic age. The impetus for the MPB method came from efforts to refine EPMA monazite U-Th-Pb dating, where it was recognized that background errors resulting from interference or strong background curvature could result in errors of several tens of millions of years on the calculated date. Results obtained on monazite reference materials using two different microprobes, a Cameca SX-100 Ultrachron and a JEOL JXA-8230, yield excellent agreement with ages obtained by isotopic methods (Thermal Ionization Mass Spectrometry [TIMS], Sensitive High-Resolution Ion MicroProbe [SHRIMP], or Secondary Ion Mass Spectrometry [SIMS]). Finally, the MPB method can be used to model the background over a large spectrometer range to improve the accuracy of background measurement of minor and trace elements acquired on a same spectrometer, a method called the shared background measurement. This latter significantly improves the accuracy of minor and trace element analysis in complex matrices, as demonstrated by the analysis of Rare Earth Elements (REE) in REE-silicates and phosphates and of trace elements in scheelite.
RESUMO
We present a detailed study of the temperature (T) and magnetic field (H) dependence of the electronic density of states (DOS) at the Fermi level, as deduced from specific heat and Knight shift measurements in underdoped YBa_{2}Cu_{3}O_{y}. We find that the DOS becomes field independent above a characteristic field H_{DOS}, and that the H_{DOS}(T) line displays an unusual inflection near the onset of the long-range 3D charge-density wave order. The unusual S shape of H_{DOS}(T) is suggestive of two mutually exclusive orders that eventually establish a form of cooperation in order to coexist at low T. On theoretical grounds, such a collaboration could result from the stabilization of a pair-density wave state, which calls for further investigation in this region of the phase diagram.
RESUMO
Type 3 secretion systems (T3SSs) are major virulence factors in Gram-negative bacteria. Pseudomonas aeruginosa expresses two T3SSs, namely, an injectisome (iT3SS) translocating effector proteins in the host cell cytosol and a flagellum (fT3SS) ensuring bacterial motility. Inhibiting these systems is an appealing therapeutic strategy for acute infections. This study examines the protective effects of the salicylidene acylhydrazide INP0341 and of the hydroxyquinoline INP1750 (previously described as T3SS inhibitors in other species) toward cytotoxic effects of P. aeruginosain vitro Both compounds reduced cell necrosis and inflammasome activation induced by reference strains or clinical isolates expressing T3SS toxins or only the translocation apparatus. INP0341 inhibited iT3SS transcriptional activation, including in strains with constitutive iT3SS expression, and reduced the total expression of toxins, suggesting it targets iT3SS gene transcription. INP1750 inhibited toxin secretion and flagellar motility and impaired the activity of the YscN ATPase from Yersinia pseudotuberculosis (homologous to the ATPase present in the basal body of P. aeruginosa iT3SS and fT3SS), suggesting that it rather targets a T3SS core constituent with high homology among iT3SS and fT3SS. This mode of action is similar to that previously described for INP1855, another hydroxyquinoline, against P. aeruginosa Thus, although acting by different mechanisms, INP0341 and INP1750 appear as useful inhibitors of the virulence of P. aeruginosa Hydroxyquinolines may have a broader spectrum of activity by the fact they act upon two virulence factors (iT3SS and fT3SS).
Assuntos
Antibacterianos/farmacologia , Hidroxiquinolinas/farmacologia , Pseudomonas aeruginosa/efeitos dos fármacos , Sistemas de Secreção Tipo III/efeitos dos fármacos , Proteínas de Bactérias/metabolismo , Linhagem Celular , Humanos , Hidrazinas/farmacologia , Inflamassomos/efeitos dos fármacos , Inflamassomos/metabolismo , Sistemas de Secreção Tipo III/metabolismo , Virulência/efeitos dos fármacosRESUMO
We report the NMR observation of a skewed distribution of ^{17}O Knight shifts when a magnetic field quenches superconductivity and induces long-range charge-density-wave (CDW) order in YBa_{2}Cu_{3}O_{y}. This distribution is explained by an inhomogeneous pattern of the local density of states N(E_{F}) arising from quasiparticle scattering off, yet unidentified, defects in the CDW state. We argue that the effect is most likely related to the formation of quasiparticle bound states, as is known to occur, under specific circumstances, in some metals and superconductors (but not in the CDW state, in general, except for very few cases in 1D materials). These observations should provide insight into the microscopic nature of the CDW, especially regarding the reconstructed band structure and the sensitivity to disorder.
RESUMO
BACKGROUND: The Democratic Republic of the Congo (DRC) is characterized by a high prevalence of hypertension (HTN) and a high proportion of uncontrolled HTN, which is indicative of poor HTN management. Effective management of HTN in the African region is challenging due to limited resources, particularly human resources for health. To address the shortage of health workers, the World Health Organization (WHO) recommends task shifting for better disease management and treatment. Although task shifting from doctors to nurses is being implemented in the DRC, there are no studies, to the best of our knowledge, that document the association between task shifting and HTN control. The aim of this study was to investigate the association between task shifting and HTN control in Kinshasa, DRC. METHODS: We conducted a cross-sectional study in Kinshasa from December 2015 to January 2016 in five general referral hospitals (GRHs) and nine health centers (HCs). A total of 260 hypertensive patients participated in the study. Sociodemographic, clinical, health care costs and perceived health care quality assessment data were collected using a structured questionnaire. To examine the association between task shifting and HTN control, we assessed differences between GRH and HC patients using bivariate and multivariate analyses. RESULTS: Almost half the patients were female (53.1%), patients' mean age was 59.5 ± 11.4 years. Over three-fourths of patients had uncontrolled HTN. There was no significant difference in the proportion of GRH and HC patients with uncontrolled HTN (76.2% vs 77.7%, p = 0.771). Uncontrolled HTN was associated with co-morbidity (OR = 10.3; 95% CI: 3.8-28.3) and the type of antihypertensive drug used (OR = 4.6; 95% CI: 1.3-16.1). The mean healthcare costs in the GRHs were significantly higher than costs in the HCs (US$ 34.2 ± US$3.34 versus US$ 7.7 ± US$ 0.6, respectively). CONCLUSION: Uncontrolled HTN was not associated with the type of health facility. This finding suggests that the management of HTN at primary healthcare level might be just as effective as at secondary level. However, the high proportion of patients with uncontrolled HTN underscores the need for HTN management guidelines at all healthcare levels.