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Predicting the interaction affinity between drugs and target proteins is crucial for rapid and accurate drug discovery and repositioning. Therefore, more accurate prediction of DTA has become a key area of research in the field of drug discovery and drug repositioning. However, traditional experimental methods have disadvantages such as long operation cycles, high manpower requirements, and high economic costs, making it difficult to predict specific interactions between drugs and target proteins quickly and accurately. Some methods mainly use the SMILES sequence of drugs and the primary structure of proteins as inputs, ignoring the graph information such as bond encoding, degree centrality encoding, spatial encoding of drug molecule graphs, and the structural information of proteins such as secondary structure and accessible surface area. Moreover, previous methods were based on protein sequences to learn feature representations, neglecting the completeness of information. To address the completeness of drug and protein structure information, we propose a Transformer graph-based early fusion research approach for drug-target affinity prediction (GEFormerDTA). Our method reduces prediction errors caused by insufficient feature learning. Experimental results on Davis and KIBA datasets showed a better prediction of drugtarget affinity than existing affinity prediction methods.
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Descubrimiento de Drogas , Reposicionamiento de Medicamentos , Secuencia de Aminoácidos , Suministros de Energía Eléctrica , AprendizajeRESUMEN
INTRODUCTION: Limited studies have explored the clinical features, treatment, and prognosis of neonatal tuberculosis (TB). Here, we attempted to delineate the clinical characteristics of neonatal TB, which may help clinicians further understand this disease. METHODS: A retrospective analysis of neonates diagnosed with congenital and/or neonatal TB disease from January 2010 to December 2020 was performed. Information on the demographic and epidemiological features, clinical symptoms, laboratory and imaging examinations, therapeutic regimens, and outcomes was collected. Kaplan-Meier analysis was used to present the time to disease onset, time to diagnosis, etc. Results: Forty-eight cases of neonatal TB were classified into congenital (n = 33) and postnatal (n = 15). The median time to disease onset in postnatal group was significantly longer than that in congenital group. Positive results for gastric fluid acid-fast bacilli, TB culture, Xpert MTB/RIF, interferon-γ release assay (IGRA), and tuberculin skin test were detected in 26/48 (54.2%), 14/34 (41.2%), 11/18 (61.1%), 19/29 (65.5%), and 8/24 (33.3%) patients, respectively. For lymphadenopathy, computed tomography (CT) scans showed a higher detection rate than did X-ray (80.0% vs. 0). Of the 48 infants, 44/48 (91.7%) received anti-TB therapy, and 33/44 (75%) were clinically improved or cured after 22.1 months (interquartile range: 12.4-27.7) of follow-up. Drug-induced liver injury occurred in 14/44 (31.8%) patients. DISCUSSION/CONCLUSION: IGRA and Xpert MTB/RIF showed good positive rate in neonatal TB infection/disease. In cases where TB is presumed but etiological evidence is lacking, low-dose CT could be considered. Prompt treatment under careful surveillance is important for preventing mortality and avoiding severe adverse effects.
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Mycobacterium tuberculosis , Tuberculosis , Lactante , Recién Nacido , Humanos , Rifampin/farmacología , Rifampin/uso terapéutico , Estudios Retrospectivos , Farmacorresistencia Bacteriana , Sensibilidad y Especificidad , Tuberculosis/diagnóstico , Tuberculosis/tratamiento farmacológico , Tuberculosis/epidemiologíaRESUMEN
Image sentiment recognition has attracted considerable attention from academia and industry due to the increasing tendency of expressing opinions via images and videos online. Previous studies focus on multilevel representation from global and local views to improve recognition performance. However, it is insufficient to research the importance and relationship of visual regions for image sentiment recognition. This paper proposes an attention-based sentiment region importance and relationship (ASRIR) analysis method, including important attention and relation attention for image sentiment recognition. First, we extract spatial region features using a multilevel pyramid network from the image. Second, we design important attention to exploring the sentiment semantic-related regions and relation attention to investigating the relationship between regions. In order to release the excessive concentration of attention, we employ a unimodal function as the objective function for regularization. Finally, the region features weighted by the attention mechanism are fused and input into a fully connected layer for classification. Extensive experiments on various commonly used image sentiment datasets demonstrate that our proposed method outperforms the state-of-the-art approaches.
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Algoritmos , Semántica , ActitudRESUMEN
Introduction: Menstrual discomfort affects women's quality of life, which is an important public health issue. Evidence confirming the link between passive smoking and menstrual discomfort is limited. Therefore, the aim of this study is to investigate the aforementioned topic on the basis of a cross-sectional study of 2,571 non-smoking Chinese nurses. Methods: Demographic information and passive smoking were assessed using a self-administered questionnaire. Menstrual discomfort was characterized as dysmenorrhea, illness or weakness, bed rest, and restlessness during menstruation, which was assessed using a modified version of the Cornell Medical Index-Health Questionnaire. Multivariate-adjusted odds ratio (OR) and 95% confidence intervals (CIs) were estimated using the logistic regression model. Results: A total of 1:195 nurses (46.48%) were exposed to passive smoking. Compared with non-passive smoking nurses, passive smoking nurses were more likely to have menstrual discomfort symptoms (72.38 vs. 64.39%), especially symptoms of dysmenorrhea (49.54 vs. 42.08%), illnesses or weakness (48.28 vs. 42.08%), and restlessness during menstruation (53.05 vs. 46.22%). Exposure to passive smoking was significantly associated with menstrual discomfort (OR = 1.41, 95%CI: 1.19-1.67), especially symptoms of dysmenorrhea (OR = 1.32, 95%CI: 1.13-1.56), illness or weakness (OR = 1.24, 95%CI: 1.06-1.46), and restlessness (OR = 1.26, 95%CI: 1.08-1.48) during menstruation. The subgroup analyses, stratified by age, children, and marital status, agreed with the main findings. Conclusions: Exposure to passive smoking was related to symptoms of dysmenorrhea and menstrual discomfort.
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Menstruación , Contaminación por Humo de Tabaco , Niño , China/epidemiología , Estudios Transversales , Dismenorrea/epidemiología , Dismenorrea/etiología , Femenino , Humanos , Agitación Psicomotora , Calidad de Vida , Contaminación por Humo de Tabaco/efectos adversosRESUMEN
This study aimed to investigate the association between passive smoking and physical and psychological health in Chinese nurses. Participants of this cross-sectional study comprised 2,484 non-smoking nurses. Passive smoking and demographic information were assessed using a self-administered questionnaire. Physical, psychological, and overall health status of nurses were measured using the Cornell Medical Index (CMI) health questionnaire. Multivariate-adjusted odds ratio (OR) and 95% confidence interval (CI) for nurses' health were estimated by exposure to passive smoking using unconditional logistic regression models. A total of 1,219 nurses (49.07%) were exposed to passive smoking. Of these, 609 (24.52%), 160 (6.44%), and 587 (23.63%) nurses had poorer physical, mental, and overall health, respectively. After adjusting for other confounding factors, compared with the non-passive smoking group, passive smoking was associated with poor physical (OR = 1.51, 95% CI: 1.25-1.83), mental (OR = 1.48, 95% CI: 1.07-2.07), and overall (OR = 1.58, 95% CI: 1.30-1.93) health of nurses, respectively. We also carried out subgroup analyses stratified by age, department, and professional title, which showed that most findings supported the main results. This study demonstrated that exposure to passive smoking was a risk factor for overall decreased physical and mental health status among Chinese nurses.
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Estado de Salud , Enfermeras y Enfermeros , Contaminación por Humo de Tabaco , China/epidemiología , Estudios Transversales , Humanos , Encuestas y CuestionariosRESUMEN
BACKGROUND: Colorectal cancer (CRC) is a common malignant tumor with unsatisfactory overall prognosis. CircRNAs could be promising prognostic biomarkers in cancers, and play important role in the process of tumorigenesis and progression. Here, we explored the role of hsa_circ_0004831 in blood extracellular vesicles and its prognostic value in CRC. METHODS: The circRNA and mRNA expression level matrix in extracellular vesicles of CRC and normal samples were obtained from the exoRBase database. The corresponding miRNA expression level matrix in extracellular vesicles was downloaded from the BBCancer database. Differentially expressed circRNAs, miRNAs and mRNAs were identified using the limma package of R software at the cut-off criteria of fold change (FC) > 2 and adj. p < 0.05. RT-qPCR assay was conducted to measure hsa_circ_0004831 expression level in CRC blood samples. A circRNA-miRNA-mRNA regulatory network of hsa_circ_0004831 was constructed based on competitive endogenous RNA mechanism and differentially expressed genes. The mRNAs co-expressed with hsa_circ_0004831 were screened at the cut-off criteria of pearson |r| > 0.3 and p < 0.05. Gene set enrichment analysis (GSEA) based on co-expressed mRNAs was used to explore the potential molecular function of hsa_circ_0004831. RESULTS: Differentially expressed circRNAs, miRNAs and mRNAs were identified and hsa_circ_0004831 had a FC value of 3.92 in CRC blood extracellular vesicles. The RT-qPCR assay showed that the hsa_circ_0004831 was up-regulated in CRC blood samples. The overall survival analysis found that high expression of hsa_circ_0004831 was linked with poorer prognosis. Finally, a circRNA-miRNA-mRNA regulatory network of hsa_circ_0004831 was constructed based on down-regulated miR-4326 and 12 up-regulated mRNAs. GSEA indicated that mRNAs co-expressed with hsa_circ_0004831 were involved in EMT, WNT and p53 signaling pathways. CONCLUSIONS: The study confirmed the up-regulation of hsa_circ_0004831 in CRC, and it may act as a vital prognostic biomarker. The circRNA-miRNA-mRNA regulatory network of hsa_circ_0004831 could be used to uncover the tumorigenesis and progression of CRC.
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A facile method employing styrene-type carboxylic esters or amides in the presence of PhICl2 in CH3CN was developed to achieve the synthesis of 6-endo products 3,4-dihydroisocoumarins or 3,4-dihydroisocoumarin-1-imines in good to high yields. This metal-free regioselective intramolecular chlorolactonization process was proposed to involve a PhICl2-mediated oxidative C-O bond formation followed by C-Cl bond formation.
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Iron- and/or manganese-supported catalysts on granular activated carbons (Fe and/or Mn/GACs) were prepared, and their catalytic activities were evaluated by using them to treat phenol and secondary petrochemical effluent via ozonation. The presence of Fe and/or Mn/GACs significantly improved the degradation and degree of phenol mineralization. Changes in dissolved ozone concentrations and the effects of carbonate and tert-butyl alcohol (TBA) indicated that the prepared catalyst enhanced the decomposition of ozone into hydroxyl radicals (·OH), which was determined to be a key factor in catalyzing the ozonation of phenol. Typical intermediate products were identified by GC-MS and HPLC analysis, and a possible degradation pathway of phenol via catalytic ozonation was proposed. The results of XPS, CV, and other experimental data indicated that introducing Fe and/or Mn increased the rate of ozone decomposition into ·OH, and also enhanced the interfacial electron transfer by Fe2+-Fe3+ and Mn2+-Mn3+-Mn4+ redox cycles, resulting in higher catalytic activity. However, the Fe-Mn/GAC surface was shown to undergo galvanic corrosion between Fe3O4 and MnO2, decreasing the catalytic activity. In addition, catalytic ozonation was used to treat secondary petrochemical effluent. The results demonstrated that the Mn/GAC/O3 system significantly improved the quality of phenol-containing wastewater in terms of its COD, TOC, NH4+-N, water color, and ecotoxicity. This study gives a better understanding of the phenol treatment by catalytic ozonation using Fe and/or Mn/GAC.
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Carbón Orgánico/química , Hierro/química , Manganeso/química , Fenol/aislamiento & purificación , Purificación del Agua/métodos , Catálisis , Radical Hidroxilo/química , Oxidación-Reducción , Ozono/química , Fenol/química , Contaminantes Químicos del Agua/química , Contaminantes Químicos del Agua/aislamiento & purificaciónRESUMEN
The reaction of diorganyl disulfides or diselenides with PhICl2 in acetonitrile was found for the first time to lead to the in situ formation of organosulfenyl chloride or selenenyl chloride, which enables the regioselective intramolecular chalcogenylacyloxylation of alkynes resulting in the formation of 4-chalcogenylisocumarins/pyrones in good to excellent yields under metal-free conditions.
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A series of 4-chloroisocoumarins were conveniently synthesized from o-alkynylbenzoates via PhICl2-mediated intramolecular cyclization under metal-free conditions. PhICl2 plays the role of both the oxidant and the chlorine source to enable oxidative C-O bond formation and introduction of the chlorine atom. The utility and practicability of this protocol have been exemplified by virtue of mild reaction conditions, high-yielding products, simplified purification, and gram-scale synthesis.
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The explosion of genomic data provides new opportunities to improve the task of gene regulatory network reconstruction. Because of its inherent probability character, the Bayesian network is one of the most promising methods. However, excessive computation time and the requirements of a large number of biological samples reduce its effectiveness and application to gene regulatory network reconstruction. In this paper, Flooding-Pruning Hill-Climbing algorithm (FPHC) is proposed as a novel hybrid method based on Bayesian networks for gene regulatory networks reconstruction. On the basis of our previous work, we propose the concept of DPI Level based on data processing inequality (DPI) to better identify neighbors of each gene on the lack of enough biological samples. Then, we use the search-and-score approach to learn the final network structure in the restricted search space. We first analyze and validate the effectiveness of FPHC in theory. Then, extensive comparison experiments are carried out on known Bayesian networks and biological networks from the DREAM (Dialogue on Reverse Engineering Assessment and Methods) challenge. The results show that the FPHC algorithm, under recommended parameters, outperforms, on average, the original hill climbing and Max-Min Hill-Climbing (MMHC) methods with respect to the network structure and running time. In addition, our results show that FPHC is more suitable for gene regulatory network reconstruction with limited data.
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BACKGROUND: The reconstruction of gene regulatory network (GRN) from gene expression data can discover regulatory relationships among genes and gain deep insights into the complicated regulation mechanism of life. However, it is still a great challenge in systems biology and bioinformatics. During the past years, numerous computational approaches have been developed for this goal, and Bayesian network (BN) methods draw most of attention among these methods because of its inherent probability characteristics. However, Bayesian network methods are time consuming and cannot handle large-scale networks due to their high computational complexity, while the mutual information-based methods are highly effective but directionless and have a high false-positive rate. RESULTS: To solve these problems, we propose a Candidate Auto Selection algorithm (CAS) based on mutual information and breakpoint detection to restrict the search space in order to accelerate the learning process of Bayesian network. First, the proposed CAS algorithm automatically selects the neighbor candidates of each node before searching the best structure of GRN. Then based on CAS algorithm, we propose a globally optimal greedy search method (CAS + G), which focuses on finding the highest rated network structure, and a local learning method (CAS + L), which focuses on faster learning the structure with little loss of quality. CONCLUSION: Results show that the proposed CAS algorithm can effectively reduce the search space of Bayesian networks through identifying the neighbor candidates of each node. In our experiments, the CAS + G method outperforms the state-of-the-art method on simulation data for inferring GRNs, and the CAS + L method is significantly faster than the state-of-the-art method with little loss of accuracy. Hence, the CAS based methods effectively decrease the computational complexity of Bayesian network and are more suitable for GRN inference.
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Algoritmos , Teorema de Bayes , Perfilación de la Expresión Génica/métodos , Redes Reguladoras de Genes , Estudios de Asociación Genética/métodos , Biología Computacional/métodos , Regulación de la Expresión Génica , Humanos , Biología de SistemasRESUMEN
BACKGROUND: Discovering novel genes that are involved human diseases is a challenging task in biomedical research. In recent years, several computational approaches have been proposed to prioritize candidate disease genes. Most of these methods are mainly based on protein-protein interaction (PPI) networks. However, since these PPI networks contain false positives and only cover less half of known human genes, their reliability and coverage are very low. Therefore, it is highly necessary to fuse multiple genomic data to construct a credible gene similarity network and then infer disease genes on the whole genomic scale. RESULTS: We proposed a novel method, named RWRB, to infer causal genes of interested diseases. First, we construct five individual gene (protein) similarity networks based on multiple genomic data of human genes. Then, an integrated gene similarity network (IGSN) is reconstructed based on similarity network fusion (SNF) method. Finally, we employee the random walk with restart algorithm on the phenotype-gene bilayer network, which combines phenotype similarity network, IGSN as well as phenotype-gene association network, to prioritize candidate disease genes. We investigate the effectiveness of RWRB through leave-one-out cross-validation methods in inferring phenotype-gene relationships. Results show that RWRB is more accurate than state-of-the-art methods on most evaluation metrics. Further analysis shows that the success of RWRB is benefited from IGSN which has a wider coverage and higher reliability comparing with current PPI networks. Moreover, we conduct a comprehensive case study for Alzheimer's disease and predict some novel disease genes that supported by literature. CONCLUSIONS: RWRB is an effective and reliable algorithm in prioritizing candidate disease genes on the genomic scale. Software and supplementary information are available at http://nclab.hit.edu.cn/~tianzhen/RWRB/ .
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Algoritmos , Biología Computacional/métodos , Enfermedad/genética , Redes Reguladoras de Genes , Ontología de Genes , Humanos , Anotación de Secuencia MolecularRESUMEN
One obstacle for practical glycosylations is the high cost of promoters and low-temperature equipment. This problem has been at least partially solved by using MeSCH2Cl/KI as a low-cost promoter system. MeSCH2Cl has an estimated cost of <$1/mol compared with $1741/mol for AgOTf and $633/mol for TMSOTf. This new promoter system is capable of activating various leaving groups including anomeric Cl, F, trichloroacetimidate, and acyloxy groups. Stable and easy-to-prepare anomeric benzoloxy carbohydrate donors were investigated in the glycosylations of carbohydrates, aliphatic alcohols, amino acids, steroids, and nucleoside acceptors. Most of these glycosylations were operationally simple with fast reaction rates and moderate yields of 35-79%. In addition, direct glycosylations of nucleosides using less than 2 equiv of anomeric benzoloxy donors and high stereoselective mannosylation have been achieved. From an economic point of view, this glycosylation method should be highly applicable to industrial processes.
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Riemerella anatipestifer infection is a severe disease confronting the duck industry worldwide. However, little is known about the molecular basis of R. anatipestifer pathogenesis. In this study, we screened 3580 transposon Tn4351 insertion mutagenesis mutants of the highly virulent strain YZb1 in a duckling infection experiment and found 29 of them to be attenuated and 28 potential virulence-associated genes were identified. Molecular characterization of transposon insertion sites showed that of the 28 screened genes, two were predicted to encode TonB-dependent outer membrane receptor (plugs), sixteen encoded enzymes, and seven encoded hypothetical proteins. In addition, of the 28 affected genes, 19 were only found in bacteria belonging to the phylum Bacteroidetes and 10 were only found in the family Flavobacteriaceae. The median lethal dose of the mutants M11 and M29, which was affected in Riean_0060 and Riean_1537 respectively, were about 1700-fold and 210-fold higher than that of the wild-type strain YZb1, and those of the complemented strains M11(pRES-Riean_0060) and M29(pRES-Riean_1537) were decreased by 25- and 3-fold respectively compared to those of the mutants M11 and M29. Additional analysis indicated that the blood bacterial loading of ducklings infected with M11 or M29 was decreased significantly, as compared with that in ducklings infected with the wild-type strain YZb1. Thus, our results indicate that Riean_0060 and Riean_1537 were involved in R. anatipestifer pathogenesis.
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Patos , Infecciones por Flavobacteriaceae/veterinaria , Mutagénesis Insercional , Riemerella/genética , Riemerella/patogenicidad , Virulencia/genética , Animales , Carga Bacteriana , Proteínas Bacterianas/genética , Sangre/microbiología , Infecciones por Flavobacteriaceae/microbiología , Enfermedades de las Aves de Corral/microbiologíaRESUMEN
To gain insight into the epidemiology of childhood drug resistant tuberculosis (DR-TB) in China that has the second largest burden of TB and the largest number of multidrug resistant (MDR) TB cases in the world, we performed the cross-sectional study to investigate drug resistance of four first-line anti-TB drugs (isoniazid, rifampicin, streptomycin and ethambutol) using Mycobacterium tuberculosis isolates from 196 culture-confirmed pediatric TB cases diagnosed in the Children's Hospital of Chongqing Medical University, China during 2008-2013. Univariate and multivariate logistic regression analyses were performed to assess the associations between patient demographic and clinical characteristics and DR-and MDR-TB, respectively. Twenty-eight percent (56/196) of the study patients exhibited resistance to at least one of the four first-line anti-TB drugs tested. MDR was found in 4.6% (9/196) of the study patients. More than half (5/9, 55.6%) of the MDR cases were from a single county of Chongqing. A significant association was found between being acid-fast bacilli-smear negative and DR-TB (adjusted OR, 2.33; 95% CI, 1.13-4.80) and between having concurrent thoracic-extrathoracic involvement and MDR-TB (adjusted OR, 9.49; 95% CI, 1.05-85.92), respectively. The findings of this study indicate that the rate of DR is high among pediatric TB patients in Chongqing and suggest an urgent need for studies to identify MDR transmission hotspots in Chongqing, thereby contributing to the control DR- and MDR-TB epidemics in China. The study also generates new insight into the pathogenesis of DR and MDR M. tuberculosis strains and highlights the importance of studying childhood TB to the goal of global TB control.
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Antituberculosos/uso terapéutico , Tuberculosis Resistente a Múltiples Medicamentos/epidemiología , Adolescente , Niño , Preescolar , China/epidemiología , Estudios Transversales , Etambutol/uso terapéutico , Femenino , Humanos , Lactante , Isoniazida/uso terapéutico , Modelos Logísticos , Masculino , Rifampin/uso terapéutico , Tuberculosis Resistente a Múltiples Medicamentos/tratamiento farmacológico , Tuberculosis Resistente a Múltiples Medicamentos/patologíaRESUMEN
The direct chlorination and bromination of (E)-enamines and (Z)-enamides to the corresponding (Z)-configurated α-chloroenamines, α-bromoenamines, and α-chloroenamides have been realized using NiCl2·6H2O or tetrabutyl ammonium bromide as a halide source and (1,1-diacetoxyiodo)benzene as an oxidant. The high stereoselective reactions which produce products with only (Z)-configurations can be attributed to the structure of the intermediates, the conformations of which are controlled by the electrostatic attractions between the positively charged nitrogen atoms and the oxygen atoms of the carbonyl group. This type of electrostatic effect has never been reported in olefin halogenations. For this reason, the three-membered bromonium ion is only a minor intermediate in the enamine bromination pathway. These methods open pathways to prepare α-chloroenamines and α-chloroenamides, which are not accessible via the currently used methods.
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BACKGROUND: Childhood tuberculosis (TB) is a major infectious disease causing morbidity and mortality in children and yet has been largely ignored until recently. This study is the first study to characterize childhood TB in China incorporating both Mycobacterium tuberculosis genetic characteristics and patient data. METHODS: We analyzed a total of 331 culture-confirmed childhood TB cases and 158 M. tuberculosis isolates from a subset of the study sample. Univariate and multivariate logistic regression analyses were performed to identify host and microbial predictors for having extrathoracic TB alone, concurrent thoracic and extrathoracic TB and TB meningitis (TBM), respectively. RESULTS: Fifty-eight percent (192/331) of the study subjects had extrathoracic TB, and 139 (42.0%) cases had TBM. Both age of less than 5 years [adjusted odds ratio (OR): 4.52; 95% confidence interval (CI): 1.27-16.16] and female sex (adjusted OR: 2.72; 95% CI: 1.03-7.18) were significantly associated with extrathoracic TB alone, whereas living in rural area (adjusted OR: 2.35; 95% CI: 1.06-5.18) was significantly associated with thoracic-extrathoracic TB. Age of less than 5 years was also strongly associated with TBM (adjusted OR: 3.63; 95% CI: 1.64-8.05). Sixty-four percent (101/158) of the study isolates were Beijing lineage strains. Infection with Beijing lineage strains was significantly associated with thoracic-extrathoracic TB (adjusted OR: 2.39; 95% CI: 1.11-5.15) and TBM (adjusted OR: 2.25; 95% CI: 1.10-4.60). CONCLUSIONS: Both microbial and host factors can affect the outcome of M. tuberculosis infection in children. Future studies incorporating host and pathogen data from different populations are warranted to develop new strategies for childhood TB control.
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Tuberculosis Meníngea/epidemiología , Tuberculosis Meníngea/microbiología , Niño , Preescolar , China/epidemiología , Estudios de Cohortes , Femenino , Humanos , Masculino , Mycobacterium tuberculosis/genética , Mycobacterium tuberculosis/aislamiento & purificación , Factores de RiesgoRESUMEN
Two TonB systems in Riemerella anatipestifer were found and characterized as ExbB1-ExbD1-TonB1 and ExbB2-ExbD2-ExbD2'-TonB2, but the significance of two sets of TonB complexes in R. anatipestifer is not clear. In this study, by deleting the tonB1 or tonB2 gene of R. anatipestifer strain CH3, we investigated the roles of the TonB1 and TonB2 proteins in iron acquisition and virulence. The results showed that strain CH3 could utilize haemin as the sole iron source in the presence of l-cysteine, but haemin iron acquisition was defective in the CH3ΔtonB1 mutant, and the deletion of either tonB1 or tonB2 significantly reduced adhesion to and invasion of Vero cells. Animal experiments indicated that the LD50 of the CH3ΔtonB1 and CH3ΔtonB2 mutants in ducklings was â¼224- and â¼87-fold, respectively, higher than that of the WT CH3 strain. Additional analysis indicated that blood bacterial loading of ducklings infected with CH3ΔtonB1 or CH3ΔtonB2 decreased significantly compared with that found for WT CH3-infected ducklings. Thus, our results indicated that the TonB1, but not TonB2 protein, is involved in haemin iron acquisition and that both TonB proteins are necessary for optimal bacterial virulence.
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Proteínas Bacterianas/metabolismo , Infecciones por Flavobacteriaceae/veterinaria , Hemina/metabolismo , Proteínas de la Membrana/metabolismo , Enfermedades de las Aves de Corral/microbiología , Riemerella/metabolismo , Riemerella/patogenicidad , Animales , Proteínas Bacterianas/genética , Transporte Biológico , Chlorocebus aethiops , Patos , Infecciones por Flavobacteriaceae/microbiología , Hierro/metabolismo , Proteínas de la Membrana/genética , Riemerella/genética , Células Vero , VirulenciaRESUMEN
To investigate the genetic basis of erythromycin resistance in Riemerella anatipestifer, the MIC to erythromycin of 79 R. anatipestifer isolates from China and one typed strain, ATCC11845, were evaluated. The results showed that 43 of 80 (53.8%) of the tested R. anatipestifer strains showed resistance to erythromycin, and 30 of 43 erythromycin-resistant R. anatipestifer strains carried ermF or ermFU with an MIC in the range of 32-2048 µg/ml, while the other 13 strains carrying the ereD gene exhibited an MIC of 4-16 µg/ml. Of 30 ermF + R. anatipestifer strains, 27 (90.0%) carried the ermFU gene which may have been derived from the CTnDOT-like element, while three other strains carried ermF from transposon Tn4351. Moreover, sequence analysis revealed that ermF, ermFU, and ereD were located within the multiresistance region of the R. anatipestifer genome.