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1.
Behav Neurosci ; 138(3): 164-177, 2024 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-38934920

RESUMO

A growing body of literature indicates that mediated learning techniques have specific utility for tapping into reality testing in animal models of neuropsychiatric illness. In particular, recent work has shown that animal models that recapitulate various endophenotypes of schizophrenia are particularly vulnerable to impairments in reality testing when undergoing mediated learning. Multiple studies have indicated that these effects are dopamine receptor 2-dependent and correlated with aberrant insular cortex (IC) activity. However, until now, the connection between dopamine and the IC had not been investigated. Here, we utilized a novel intersectional approach to label mesencephalic dopamine cells that specifically project to the insular cortex in both wild-type controls and transgenic mice expressing the dominant-negative form of the Disrupted-in-Schizophrenia-1 (DISC-1) gene. Using these techniques, we identified a population of cells that project from the ventral tegmental area (VTA) to the IC. Afterward, we conducted multiple studies to test the necessity of this circuit in behaviors ranging from gustatory detection to the maintenance of effort and, finally, mediated performance. Our results indicate that perturbations of the DISC-1 genetic locus lead to a reduction in the number of cells in the VTA → IC circuit. Behaviorally, VTA → IC circuitry does not influence gustatory detection or motivation to acquire sucrose reward; however, inactivation of this circuit differentially suppresses Pavlovian approach behavior in wild-type and DISC-1 transgenic mice during mediated performance testing. Moreover, under these testing conditions, inactivation of this circuit predisposes wild-type (but not DISC-1) mice to display impaired reality testing. (PsycInfo Database Record (c) 2024 APA, all rights reserved).


Assuntos
Neurônios Dopaminérgicos , Córtex Insular , Camundongos Transgênicos , Animais , Neurônios Dopaminérgicos/fisiologia , Neurônios Dopaminérgicos/metabolismo , Camundongos , Córtex Insular/fisiologia , Masculino , Área Tegmentar Ventral/fisiologia , Área Tegmentar Ventral/metabolismo , Camundongos Endogâmicos C57BL , Vias Neurais/fisiologia , Recompensa , Modelos Animais de Doenças , Dopamina/metabolismo , Proteínas do Tecido Nervoso/genética , Proteínas do Tecido Nervoso/metabolismo , Mesencéfalo/metabolismo , Mesencéfalo/fisiologia , Esquizofrenia/fisiopatologia
2.
ArXiv ; 2024 Feb 28.
Artigo em Inglês | MEDLINE | ID: mdl-38463508

RESUMO

Accurate blind docking has the potential to lead to new biological breakthroughs, but for this promise to be realized, docking methods must generalize well across the proteome. Existing benchmarks, however, fail to rigorously assess generalizability. Therefore, we develop DockGen, a new benchmark based on the ligand-binding domains of proteins, and we show that existing machine learning-based docking models have very weak generalization abilities. We carefully analyze the scaling laws of ML-based docking and show that, by scaling data and model size, as well as integrating synthetic data strategies, we are able to significantly increase the generalization capacity and set new state-of-the-art performance across benchmarks. Further, we propose Confidence Bootstrapping, a new training paradigm that solely relies on the interaction between diffusion and confidence models and exploits the multi-resolution generation process of diffusion models. We demonstrate that Confidence Bootstrapping significantly improves the ability of ML-based docking methods to dock to unseen protein classes, edging closer to accurate and generalizable blind docking methods.

3.
Psychol Med ; 52(14): 2937-2949, 2022 10.
Artigo em Inglês | MEDLINE | ID: mdl-36138518

RESUMO

Hallucinations occur in the absence of sensory stimulation and result in vivid perceptual experiences of nonexistent events that manifest across a range of sensory modalities. Approaches from the field of experimental and cognitive psychology have leveraged the idea that associative learning experiences can evoke conditioning-induced hallucinations in both animals and humans. In this review, we describe classical and contemporary findings and highlight the variables eliciting these experiences. We also provide an overview of the neurobiological mechanisms, along with the associative and computational factors that may explain hallucinations that are generated by representation-mediated conditioning phenomena. Through the integration of animal and human research, significant advances into the psychobiology of hallucinations are possible, which may ultimately translate to more effective clinical applications.


Assuntos
Condicionamento Clássico , Alucinações , Animais , Humanos
4.
Cell Rep ; 38(5): 110318, 2022 02 01.
Artigo em Inglês | MEDLINE | ID: mdl-35090597

RESUMO

Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) vaccines may target epitopes that reduce durability or increase the potential for escape from vaccine-induced immunity. Using synthetic vaccinology, we have developed rationally immune-focused SARS-CoV-2 Spike-based vaccines. Glycans can be employed to alter antibody responses to infection and vaccines. Utilizing computational modeling and in vitro screening, we have incorporated glycans into the receptor-binding domain (RBD) and assessed antigenic profiles. We demonstrate that glycan-coated RBD immunogens elicit stronger neutralizing antibodies and have engineered seven multivalent configurations. Advanced DNA delivery of engineered nanoparticle vaccines rapidly elicits potent neutralizing antibodies in guinea pigs, hamsters, and multiple mouse models, including human ACE2 and human antibody repertoire transgenics. RBD nanoparticles induce high levels of cross-neutralizing antibodies against variants of concern with durable titers beyond 6 months. Single, low-dose immunization protects against a lethal SARS-CoV-2 challenge. Single-dose coronavirus vaccines via DNA-launched nanoparticles provide a platform for rapid clinical translation of potent and durable coronavirus vaccines.


Assuntos
Vacinas contra COVID-19/administração & dosagem , Vacinas contra COVID-19/imunologia , COVID-19/prevenção & controle , Nanopartículas/administração & dosagem , SARS-CoV-2/imunologia , Animais , Anticorpos Neutralizantes/imunologia , Sítios de Ligação , Vacinas contra COVID-19/química , Vacinas contra COVID-19/genética , Cricetinae , Epitopos , Cobaias , Imunogenicidade da Vacina , Camundongos , Nanopartículas/química , Vacinas Baseadas em Ácido Nucleico/administração & dosagem , Vacinas Baseadas em Ácido Nucleico/química , Vacinas Baseadas em Ácido Nucleico/genética , Vacinas Baseadas em Ácido Nucleico/imunologia , Polissacarídeos/química , Polissacarídeos/genética , Polissacarídeos/imunologia , SARS-CoV-2/química , SARS-CoV-2/genética , Glicoproteína da Espícula de Coronavírus/química , Glicoproteína da Espícula de Coronavírus/genética , Glicoproteína da Espícula de Coronavírus/imunologia , Potência de Vacina
5.
Environ Monit Assess ; 193(5): 307, 2021 Apr 28.
Artigo em Inglês | MEDLINE | ID: mdl-33909163

RESUMO

Metal and metalloid contamination in drinking water sources is a global concern, particularly in developing countries. This study used hollow membrane water filters and metal-capturing polyurethane foams to sample 71 drinking water sources in 22 different countries. Field sampling was performed with sampling kits prepared in the lab at Hope College in Holland, MI, USA. Filters and foams were sent back to the lab after sampling, and subsequent analysis of flushates and rinsates allowed the estimation of suspended solids and metal and other analayte concentrations in source waters. Estimated particulate concentrations were 0-92 mg/L, and consisted of quartz, feldspar, and clay, with some samples containing metal oxides or sulfide phases. As and Cu were the only analytes which occurred above the World Health Organization (WHO) guidelines of 10 µg/L and 2000 µg/L, respectively, with As exceeding the guideline in 45% of the sources and Cu in 3%. Except for one value of ~ 285 µg/L, As concentrations were 45-200 µg/L (river), 65-179 µg/L (well), and 112-178 µg/L (tap). Other metals (Ce, Fe, Mg, Mn, Zn) with no WHO guideline were also detected, with Mn the most common. This study demonstrated that filters and foams can be used for reconnaissance characterization of untreated drinking water. However, estimated metal and other analyte concentrations could only be reported as minimum values due to potential incomplete retrieval of foam-bound analytes. A qualitative reporting methodology was used to report analytes as "present" if the concentration was below the WHO guideline, and "present-recommend retesting" if the concentration was quantifiable and above the WHO guideline.


Assuntos
Água Potável , Metaloides , Metais Pesados , Poluentes Químicos da Água , Monitoramento Ambiental , Humanos , Metaloides/análise , Metais Pesados/análise , Países Baixos , Poluentes Químicos da Água/análise
6.
Learn Mem ; 28(4): 104-108, 2021 04.
Artigo em Inglês | MEDLINE | ID: mdl-33723029

RESUMO

The dopamine system has been implicated in decision-making particularly when associated with effortful behavior. We examined acute optogenetic stimulation of dopamine cells in the ventral tegmental area (VTA) as mice engaged in an effort-based decision-making task. Tyrosine hydroxylase-Cre mice were injected with Cre-dependent ChR2 or eYFP control virus in the VTA. While eYFP control mice showed effortful discounting, stimulation of dopamine cells in ChR2 mice disrupted effort-based decision-making by reducing choice toward the lever associated with a preferred outcome and greater effort. Surprisingly, disruptions in effortful discounting were observed in subsequent test sessions conducted in the absence of optogenetic stimulation, however during these sessions ChR2 mice displayed enhanced high choice responding across trial blocks. These findings suggest increases in VTA dopamine cell activity can disrupt effort-based decision-making in distinct ways dependent on the timing of optogenetic stimulation.


Assuntos
Comportamento Animal/fisiologia , Tomada de Decisões/fisiologia , Neurônios Dopaminérgicos/fisiologia , Área Tegmentar Ventral/fisiologia , Animais , Condicionamento Operante/fisiologia , Camundongos , Optogenética , Desempenho Psicomotor/fisiologia , Tirosina 3-Mono-Oxigenase , Área Tegmentar Ventral/citologia
7.
Trop Med Health ; 49(1): 1, 2021 Jan 04.
Artigo em Inglês | MEDLINE | ID: mdl-33397511

RESUMO

BACKGROUND: Lack of sustainable access to clean drinking water continues to be an issue of paramount global importance, leading to millions of preventable deaths annually. Best practices for providing sustainable access to clean drinking water, however, remain unclear. Widespread installation of low-cost, in-home, point of use water filtration systems is a promising strategy. METHODS: We conducted a prospective, randomized, controlled trial whereby 16 villages were selected and randomly assigned to one of four treatment arms based on the installation location of Sawyer® PointONE™ filters (filter in both home and school; filter in home only; filter in school only; control group). Water samples and self-reported information on diarrhea were collected at multiple times throughout the study. RESULTS: Self-reported household prevalence of diarrhea decreased from 25.6 to 9.76% from installation to follow-up (at least 7 days, and up to 200 days post-filter installation). These declines were also observed in diarrhea with economic or educational consequences (diarrhea which led to medical treatment and/or missing school or work) with baseline prevalence of 9.64% declining to 1.57%. Decreases in diarrhea prevalence were observed across age groups. There was no evidence of a loss of efficacy of filters up to 200 days post-filter installation. Installation of filters in schools was not associated with decreases in diarrhea prevalence in school-aged children or family members. Unfiltered water samples both at schools and homes contained potential waterborne bacterial pathogens, dissolved heavy metals and metals associated with particulates. All dissolved metals were detected at levels below World Health Organization action guidelines. CONCLUSIONS: This controlled trial provides strong evidence of the effectiveness of point-of-use, hollow fiber membrane filters at reducing diarrhea from bacterial sources up to 200 days post-installation when installed in homes. No statistically significant reduction in diarrhea was found when filters were installed in schools. Further research is needed in order to explore filter efficacy and utilization after 200 days post-installation. TRIAL REGISTRATION: ClinicalTrials.gov, NCT03972618 . Registered 3 June 2019-retrospectively registered.

8.
Langmuir ; 36(5): 1147-1155, 2020 Feb 11.
Artigo em Inglês | MEDLINE | ID: mdl-31941274

RESUMO

Organic friction modifier additives (OFMs) are surfactant molecules added to engine oils to reduce friction in the boundary lubrication regime. They are thought to work by forming an absorbed layer, which provides low friction. This paper studied the relationship between the adsorption of OFMs and their friction and wear-reducing properties in a rubbing contact formed by a stationary glass ball and a rotating silicon disk under the boundary lubrication regime. The effect of molecular structure was investigated by using OFMs of various tail saturation and head group chemistry. OFMs tested were oleic acid, octadecylamine, oleylamine, and glycerol monooleate. The thickness of an OFM-adsorbed layer in hexadecane, examined in situ by spectroscopic ellipsometry and quartz crystal microbalance (QCM), depends on the molecular structure and the concentration of the OFM. As expected, the saturated, linear chain gives the thickest film. A critical OFM layer thickness of about 0.6 nm is necessary to achieve low initial and maximum friction. The thicker OFM layers are accompanied by narrower wear tracks, which are rougher than the wider, smoother wear tracks formed with thinner OFM layers. The interplay between the thickness of the OFM layer and wear track surface roughness results in all OFM layers having similar steady state friction. This shows that the apparent effect of OFM depends on the stage of the rubbing test: initially on friction, and then subsequently on surface damage. Despite OFMs and the base oil having similar refractive indices, ellipsometry was found to be a suitable technique for examining the adsorption of OFM additives from an oil-based solution and showed reasonable correlation with QCM results.

9.
Schizophr Bull ; 46(1): 54-67, 2020 01 04.
Artigo em Inglês | MEDLINE | ID: mdl-31150554

RESUMO

Impairments in reality testing are core features of numerous neuropsychiatric conditions. However, relatively few animal models have been developed to assess this critical facet of neuropsychiatric illness, thus impeding our understanding of the underlying central systems and circuits. Using mice in which dominant-negative Disrupted-in-Schizophrenia-1 is expressed throughout central nervous system circuitry (DN-DISC1-PrP), the capacity for an auditory conditioned stimulus (CS) to evoke perceptual processing of an absent sucrose solution was examined. At test, during CS presentations, DN-DISC1-PrP mice consumed more water and displayed a licking profile that is more typically revealed while ingesting a sweet-tasting solution. DN-DISC1-PrP mice also displayed greater c-fos expression in the insular (gustatory) cortex when consuming water in the presence of the CS. This capacity for the CS to more readily substitute for the taste features of the absent sucrose solution in DN-DISC1-PrP mice was attenuated following systemic treatment with the antipsychotic haloperidol. Conversely, social isolation during adolescence promoted the manifestation of these effects. These results provide strong validation for using associative learning procedures to examine dopamine-mediated reality testing associated with insular cortex activation.


Assuntos
Aprendizagem por Associação/fisiologia , Comportamento Animal/fisiologia , Córtex Cerebral/fisiopatologia , Delusões/fisiopatologia , Dopamina/fisiologia , Alucinações/fisiopatologia , Teste de Realidade , Recompensa , Percepção Gustatória/fisiologia , Animais , Antipsicóticos/farmacologia , Percepção Auditiva/fisiologia , Comportamento Animal/efeitos dos fármacos , Córtex Cerebral/efeitos dos fármacos , Condicionamento Clássico/fisiologia , Delusões/tratamento farmacológico , Modelos Animais de Doenças , Alucinações/tratamento farmacológico , Haloperidol/farmacologia , Camundongos , Camundongos Transgênicos , Proteínas do Tecido Nervoso , Isolamento Social , Percepção Gustatória/efeitos dos fármacos
10.
Pharmacol Biochem Behav ; 158: 14-21, 2017 07.
Artigo em Inglês | MEDLINE | ID: mdl-28529018

RESUMO

Previous research has implicated the positive modulation of anandamide, an endocannabinoid neurotransmitter, on feeding behavior. Anandamide is particularly noteworthy as it acts as an endogenous ligand of the CB1 receptor, the same receptor that is activated by tetrahydrocannabinol, the primary psychoactive component in Cannabis sativa. Cannabis legalization in North America has presented with a need to study endocannabinoid agonists and their effects on behavior. Much has yet to be determined in terms of the role of the endocannabinoid system in decision-making scenarios. The research presented here tested the hypothesis that anandamide would augment motivation and reward processing via appetitive and consummatory measures during an operant, foraging task. A three-box design was used in order to provide the animals with a free choice, exploratory foraging environment. Discrimination, preference, and incentive contrast were analyzed as discrete measures of decision-making in the three-box paradigm. Anandamide administration (1mg/kg) was found to significantly increase motivation for the optimal foraging outcome and alter basic processing of reward information involved in discrimination and relative valuation. The positive effects of anandamide on eating behavior and motivation have implications toward possible treatment modalities for patient populations presenting with disorders of motivation. These findings suggest the need for continued investigation of the endocannabinoid system as a central component of motivated behavior.


Assuntos
Ácidos Araquidônicos/farmacologia , Comportamento Animal/efeitos dos fármacos , Comportamento de Escolha , Endocanabinoides/farmacologia , Alcamidas Poli-Insaturadas/farmacologia , Recompensa , Animais , Apetite/efeitos dos fármacos , Ratos , Ratos Sprague-Dawley
11.
J Rural Health ; 28(3): 221-6, 2012.
Artigo em Inglês | MEDLINE | ID: mdl-22757945

RESUMO

CONTEXT: The 2008 financial crisis had a far-reaching impact on nearly every sector of the economy. As unemployment increased so did the uninsured. Already operating on a slim margin and poor payer mix, many critical access hospitals are facing a tough road ahead. PURPOSE: We seek to examine the increasing impact of uncompensated care on the revenues earned by Washington's critical access hospitals; to forecast uncompensated care to the year 2014; and to forecast the financial impact on rural hospital uncompensated care of HR 3590, the Affordable Care Act (ACA). FINDINGS: For critical access hospitals in the state of Washington, total uncompensated care increased by almost $16 million, a 22% increase from 2008 to 2009. By 2014, total uncompensated care is forecast to more than double from 2009, totaling $174 million annually without health reforms. Using the Urban Institute's Health Insurance Policy Simulation Model, uncompensated care is forecast to fall by $106 million in 2014, thereby reducing the uncompensated care percentage from 5.31% to 2.07%. CONCLUSIONS: Policy makers and health care managers should note that a substantial portion of the newly insured from the ACA will most likely be Medicaid participants. Given this source of lower revenue per case, critical access hospital administrators should seek additional public and private sources of revenue. Most importantly, rural hospital managers must maintain or improve their cost efficiency, while serving the needs of their rural population as we move closer toward the implementation of health reforms.


Assuntos
Cuidados Críticos/economia , Economia Hospitalar , Reforma dos Serviços de Saúde/legislação & jurisprudência , Patient Protection and Affordable Care Act/legislação & jurisprudência , Cuidados de Saúde não Remunerados/economia , Cuidados Críticos/estatística & dados numéricos , Previsões , Hospitais Rurais/economia , Humanos , Cuidados de Saúde não Remunerados/estatística & dados numéricos , Cuidados de Saúde não Remunerados/tendências , Washington
12.
Microb Pathog ; 52(6): 344-52, 2012 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-22445818

RESUMO

Campylobacter jejuni is a major bacterial cause of gastroenteritis world-wide. C. jejuni produces a range of glycans including lipooligosaccharide (LOS), an important virulence factor. The genetic content of the LOS synthesis locus varies between C. jejuni strains and 19 classes have been described. Three LOS synthesis genes of C. jejuni strain 81116 (NCTC 11828), wlaRG, wlaTB and wlaTC were the focus of this study. WlaRG and the remaining two proteins of interest share sequence similarity to aminotransferases and glycosyltransferases, respectively. These genes were insertionally inactivated and phenotypically characterised. Each mutant produced truncated LOS. Mutants lacking WlaRG, WlaTB and WlaTC produced LOS with reduced immunogenicity. Both the wlaRG and wlaTC mutants were non-motile and aflagellate. In vitro invasion and adhesion assays revealed that the wlaRG, wlaTB and wlaTC mutants displayed reduced adherence to chicken embryo fibroblasts. All mutants were less invasive of human cells than 81116 confirming the role of intact LOS during invasion of human cells in vitro. Here we propose the general composition for the 81116 LOS core backbone based on capillary electrophoresis-mass spectrometry.


Assuntos
Proteínas de Bactérias/metabolismo , Campylobacter jejuni/enzimologia , Campylobacter jejuni/metabolismo , Glicosiltransferases/metabolismo , Lipopolissacarídeos/biossíntese , Transaminases/metabolismo , Animais , Aderência Bacteriana , Proteínas de Bactérias/genética , Campylobacter jejuni/genética , Campylobacter jejuni/fisiologia , Células Cultivadas , Embrião de Galinha , Fibroblastos/microbiologia , Flagelos/fisiologia , Glicosiltransferases/genética , Humanos , Lipopolissacarídeos/imunologia , Locomoção , Mutagênese Insercional , Homologia de Sequência de Aminoácidos , Transaminases/genética , Fatores de Virulência/biossíntese , Fatores de Virulência/imunologia
13.
FEMS Immunol Med Microbiol ; 54(2): 224-35, 2008 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-18754784

RESUMO

Campylobacter concisus is an opportunistic pathogen commonly found in the human oral cavity. It has also been isolated from clinical sources including gastroenteritis cases. Both secreted and cell-associated hemolytic activities were detected in C. concisus strains isolated from children with gastroenteritis. The secreted hemolytic activity of C. concisus strains was labile and was detected in variable levels from fresh-culture filtrates only. In addition, another secreted hemolysin/cytotoxin with a molecular weight < 10 kDa was detected in a single C. concisus strain (RCH 12). A C. concisus genomic library, constructed from strain RCH 3 in Escherichia coli XL1-Blue, was screened for hemolytic clones. Subcloning and sequence analysis of selected hemolytic clones identified ORFs for genes that enhance hemolytic activity but do not appear to be related to any known hemolysin genes found in Gram-negative bacteria. In a previous study, a stable cell-associated hemolysin was identified as an outer-membrane phospholipase A (OMPLA) encoded by the pldA gene. In this study, we report cloning of the pldA gene of the clinical strain C. concisus RCH 3 and the complementation of phospholipase A activity in an E. coli pldA mutant.


Assuntos
Campylobacter/genética , Proteínas Hemolisinas/genética , Hemólise , Fosfolipases A/genética , Sequência de Aminoácidos , Proteínas da Membrana Bacteriana Externa/química , Proteínas da Membrana Bacteriana Externa/genética , Proteínas da Membrana Bacteriana Externa/metabolismo , Sequência de Bases , Campylobacter/isolamento & purificação , Campylobacter/patogenicidade , Infecções por Campylobacter/microbiologia , Criança , Clonagem Molecular , Gastroenterite/microbiologia , Teste de Complementação Genética , Biblioteca Genômica , Proteínas Hemolisinas/química , Proteínas Hemolisinas/metabolismo , Humanos , Ferro/metabolismo , Dados de Sequência Molecular , Fosfolipases A/química , Fosfolipases A/metabolismo , Fosfolipases A1/genética , Fosfolipases A1/metabolismo , Proteínas Recombinantes/metabolismo
14.
Int J Med Microbiol ; 297(6): 431-41, 2007 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-17631048

RESUMO

The lipooligosaccharide (LOS) molecules of Campylobacter jejuni are involved in virulence and induction of the Guillain-Barré syndrome (GBS). This study analysed the transcription of the LOS synthesis genes from the GBS-inducing C. jejuni strain HB 93-13 under microaerobic conditions. Fourteen consecutive genes Cj1132c, waaC, htrB, wlaNC, wlaND, cgtA, cgtB, cstII, neuB, neuC, neuA, wlaVA, wlaQA, and waaF were included. The results of rapid amplification of cDNA ends and single-stranded ligation of complementary ends showed initiation sites with potential promoter regions on both DNA strands in the Cj1132c/waaC, cgtB/cstII, and wlaQA/waaF strand-switch regions. Other termini without recognisable promoter region were also found throughout the LOS gene cluster, suggesting a low specificity of the polymerase during transcription. In addition, all gene junction regions were cloned into the shuttle vector pMW10 carrying the promoterless lacZ gene to identify functional promoter sites. Bidirectional active promoters were found in the strand-switch regions. The results of RT-PCR and cDNA blotting indicated that transcriptional linkage occurred between different operons, indicating a lack of transcription termination within the LOS gene cluster. Moreover, the results of semi-quantitative RT-PCR and real-time RT-PCR showed that both DNA strands were transcribed but transcription of the coding strand was at a higher rate. The results presented here provide an insight into transcription of the LOS synthesis gene cluster of C. jejuni.


Assuntos
Campylobacter jejuni/genética , Genes Bacterianos , Lipopolissacarídeos/biossíntese , Redes e Vias Metabólicas/genética , Transcrição Gênica , Campylobacter jejuni/metabolismo , DNA Bacteriano/genética , DNA Complementar/genética , Genes Reporter , Vetores Genéticos , Família Multigênica , Regiões Promotoras Genéticas , Reação em Cadeia da Polimerase Via Transcriptase Reversa , beta-Galactosidase/biossíntese , beta-Galactosidase/genética
15.
FEMS Immunol Med Microbiol ; 50(1): 27-36, 2007 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-17374131

RESUMO

Campylobacter jejuni is recognized as the most common identifiable pathogen associated with the development of Guillain-Barré syndrome (GBS), an acute autoimmune-mediated disease affecting the peripheral nervous system. The immune response to ganglioside-like structures in lipo-oligosaccharides (LOSs) of certain C. jejuni strains is thought to cross-react with human nerve gangliosides and induce GBS. To study the involvement of LOSs in the pathogenesis of Campylobacter-induced GBS, we created truncated LOS molecules by inactivating the waaF gene in a GBS-associated isolate of C. jejuni. Gas Chromatography-MS analysis of the waaF mutant LOSs revealed a marked reduction in sugar content, including sialic acid and galactose. GM1 and GD1a-like mimicry was not detected in the waaF mutant by Western blot analysis with cholera toxin B and anti-GD1a antibodies. Mice immunized with the waaF mutant failed to develop anti-GM1 or anti-GD1a antibodies. The waaF mutant also showed reduced adherence to and invasion of INT-407 cells. The results indicate that the LOS of C. jejuni HB93-13 is essential for adherence and invasion as well as for anti-ganglioside antibody induction.


Assuntos
Anticorpos Antibacterianos/imunologia , Infecções por Campylobacter/imunologia , Campylobacter jejuni/imunologia , Gangliosídeos/imunologia , Glucosiltransferases/genética , Mimetismo Molecular/imunologia , Oligossacarídeos/imunologia , Sequência de Aminoácidos , Animais , Antígenos de Bactérias/imunologia , Infecções por Campylobacter/metabolismo , Campylobacter jejuni/genética , Clonagem Molecular , Cromatografia Gasosa-Espectrometria de Massas/métodos , Glucosiltransferases/deficiência , Glucosiltransferases/metabolismo , Imunização/métodos , Camundongos , Camundongos Endogâmicos C3H , Dados de Sequência Molecular , Oligossacarídeos/farmacologia , Reação em Cadeia da Polimerase , Fatores de Virulência
16.
FEMS Immunol Med Microbiol ; 49(1): 133-40, 2007 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-17266719

RESUMO

Cytotoxin fractions were isolated from Campylobacter jejuni 81116 and semi-purified by size-exclusion liquid chromatography. The fraction showing the strongest toxicity was injected into mice to produce antiserum. The antiserum was used to screen a C. jejuni 81116 cosmid library. Nine genes were identified in overlapping cosmid inserts that induced reactivity with the antiserum. One of these genes showed high similarity to a periplasmic protein of unknown function and its isogenic mutant showed decreased toxicity compared to the C. jejuni 81116 wild type. This gene contains a Gram-negative bacterial RTX toxin-activating protein C signature, which suggests it may play a role in C. jejuni 81116 cytotoxin activation.


Assuntos
Campylobacter jejuni/genética , Cosmídeos/genética , Citotoxinas/imunologia , Animais , Sequência de Bases , Western Blotting/métodos , Células CHO , Infecções por Campylobacter/microbiologia , Campylobacter jejuni/imunologia , Cricetinae , Cricetulus , Citotoxinas/genética , Citotoxinas/isolamento & purificação , DNA Bacteriano/genética , Feminino , Células HeLa , Humanos , Camundongos , Camundongos Endogâmicos BALB C , Dados de Sequência Molecular , Testes de Neutralização/métodos , Fases de Leitura Aberta , Reação em Cadeia da Polimerase/métodos , Mapeamento por Restrição
17.
FEMS Immunol Med Microbiol ; 49(1): 149-54, 2007 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-17266722

RESUMO

Campylobacter jejuni is a common cause of bacterial enteritis. The surface capsular polysaccharides are important for this bacterium to survive in the environment, but little is known about their involvement in bacterium-host interactions. This study showed that the C. jejuni capsular polysaccharides play an important role in adherence to and invasion of human embryonic epithelial cells. However, no significant role of capsular polysaccharides was shown in colonization of the chicken gut.


Assuntos
Proteínas de Bactérias/genética , Campylobacter jejuni/genética , Intestinos/microbiologia , Proteínas de Membrana Transportadoras/genética , Animais , Aderência Bacteriana , Cápsulas Bacterianas/biossíntese , Cápsulas Bacterianas/genética , Proteínas de Bactérias/metabolismo , Infecções por Campylobacter/microbiologia , Campylobacter jejuni/metabolismo , Campylobacter jejuni/patogenicidade , Galinhas , Inativação Gênica , Humanos , Proteínas de Membrana Transportadoras/metabolismo , Mutagênese Sítio-Dirigida , Polissacarídeos Bacterianos/biossíntese , Polissacarídeos Bacterianos/genética
18.
Microbiology (Reading) ; 153(Pt 1): 254-62, 2007 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-17185554

RESUMO

In Campylobacter jejuni, an htrB homologous gene is located in the lipo-oligosaccharide synthesis gene cluster. This study examined the effects of htrB expression on the responsiveness of Salmonella typhimurium and C. jejuni to harsh environments. Complementation experiments showed that the C. jejuni htrB gene could restore the normal morphology of the Salmonella htrB mutant, and its ability to grow without inhibition under heat, acid and osmotic stresses, but not bile stress. This indicated that the htrB genes in C. jejuni and S. typhimurium exhibit similar pleiotropic effects. Moreover, quantitative real-time RT-PCR showed that expression of the C. jejuni htrB gene was upregulated under acid, heat, oxidative and osmotic stresses, but did not change under bile stress. This indicated that the C. jejuni htrB gene plays a role in regulating cell responses to various environmental changes. Furthermore, deletion mutation of the htrB gene in C. jejuni was lethal, indicating that the htrB gene is essential for C. jejuni survival. Therefore, these results showed that expression of the htrB gene is essential for the response of S. typhimurium and C. jejuni to environmental stresses.


Assuntos
Aciltransferases/fisiologia , Proteínas de Bactérias/fisiologia , Campylobacter jejuni/fisiologia , Salmonella typhimurium/fisiologia , Ácidos , Expressão Gênica , Teste de Complementação Genética , Temperatura Alta , Mutação , Pressão Osmótica
19.
J Microbiol Methods ; 68(2): 427-9, 2007 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-17084472

RESUMO

DNA-free RNA samples are essential to investigate gene regulation using real-time RT-PCR. This study evaluated eight RNA isolation methods in combination with TURBO DNase treatment and acid phenol extractions for their ability to produce DNA-free RNA from Campylobacter jejuni strains.


Assuntos
Campylobacter jejuni/genética , RNA Bacteriano/isolamento & purificação , Desoxirribonucleases/química , RNA Bacteriano/química , RNA Bacteriano/genética , Reação em Cadeia da Polimerase Via Transcriptase Reversa , Espectrofotometria Ultravioleta
20.
Infect Immun ; 74(2): 1368-72, 2006 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-16428786

RESUMO

Human ganglioside-like structures, such as GM1, found on some Campylobacter jejuni strains have been linked to inducing the Guillain-Barré Syndrome (GBS). This study shows that a C. jejuni strain without GM1-like molecules acquired large DNA fragments, including lipooligosaccharide synthesis genes, from a strain expressing GM1-like molecules and consequently transformed into a number of potential GBS-inducible transformants, which exhibited a high degree of genetic and phenotypic diversity.


Assuntos
Proteínas de Bactérias/genética , Campylobacter jejuni/genética , Transferência Genética Horizontal , Síndrome de Guillain-Barré/microbiologia , Lipopolissacarídeos/biossíntese , Transformação Bacteriana , Campylobacter jejuni/classificação , Campylobacter jejuni/metabolismo , DNA Bacteriano/análise , DNA Bacteriano/genética , Eletroforese em Gel de Campo Pulsado , Gangliosídeo G(M1)/metabolismo , Síndrome de Guillain-Barré/etiologia , Humanos , Mimetismo Molecular , Família Multigênica , Reação em Cadeia da Polimerase , Polimorfismo de Fragmento de Restrição , Recombinação Genética
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