Your browser doesn't support javascript.
loading
Mostrar: 20 | 50 | 100
Resultados 1 - 20 de 91
Filtrar
Mais filtros










Intervalo de ano de publicação
1.
Biotechnol Lett ; 41(10): 1105-1110, 2019 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-31407133

RESUMO

Atomic force microscopy (AFM) is a sophisticated imaging tool with nanoscale resolution that is widely used in structural biology, cell biology, and material science, among other fields. However, to date it has rarely been applied to the study of aquatic animals, especially on one of the main cultured species, shrimp. One reason for this is that no shrimp cell line established until now, primary cell is fragile and difficult to be studied under AFM. In this study, we used AFM to image three different types of biological material from shrimp (Litopenaeus vannamei) in air, including hemocytes and two associated pathogens. Without obvious deformations when the cells were imaged in air and in the case for the haemocytes and the cells were fixed as well. The result suggests hydrophobic glass coverslips are a suitable substrate for adhesion of these samples. The method described here can be applied to the preparation of other fragile biological samples from aquatic animals for high-resolution analyses of host-pathogen interactions and other basic physiological processes.


Assuntos
Células/ultraestrutura , Processamento de Imagem Assistida por Computador/métodos , Microscopia de Força Atômica/métodos , Penaeidae/ultraestrutura , Animais , Bactérias/ultraestrutura , Células/microbiologia , Células/virologia , Penaeidae/microbiologia , Penaeidae/virologia , Vírus/ultraestrutura
2.
J Microbiol Methods ; 153: 84-91, 2018 10.
Artigo em Inglês | MEDLINE | ID: mdl-30240810

RESUMO

We monitored Chlamydia trachomatis growth in HeLa cells cultured with either DMEM or RPMI medium containing 10% FCS under 2% or 21% O2 conditions for 2 days. Bacterial numbers, host cell numbers, and fibrosis-related gene expression in the host cells were estimated by an inclusion forming unit assay, a cell counting assay, and a PCR array, respectively. In contrast to RPMI, bacterial growth under low oxygen conditions in DMEM rapidly decreased with increasing host cell density. The addition of supplements (glucose, glutamine, vitamin B12, D-biotin, non-essential amino acids, glutathione) to the media had no effect. The growth of host cells in DMEM under low oxygen conditions rapidly decreased, although the cells remained healthy morphologically. Furthermore, the downregulation of 17 genes was observed under low oxygen in DMEM. Whereas no effect on bacterial growth was observed when culturing in RPMI medium at low oxygen, and the downregulation of three genes (CTGF, SERPINE1, JUN) was observed following bacterial infection compared with the uninfected control cells. Thus, our findings indicate the need for carefully selected culture conditions when performing experiments with C. trachomatis under low-oxygen environments, and RPMI (rather than DMEM) is recommended when a low host cell density is to be used, proposing the major modification of cell culturing method of C. trachomatis in a low-oxygen environment.


Assuntos
Técnicas de Cultura de Células/normas , Chlamydia trachomatis/crescimento & desenvolvimento , Citoplasma/microbiologia , Oxigênio/metabolismo , Contagem de Células/métodos , Contagem de Células/normas , Células/microbiologia , Meios de Cultura/química , Glucose/metabolismo , Células HeLa , Humanos , Hipóxia , Reação em Cadeia da Polimerase
3.
Gene ; 651: 134-142, 2018 Apr 20.
Artigo em Inglês | MEDLINE | ID: mdl-29391275

RESUMO

Bioinformatics and comparative genomics analysis methods were used to predict unknown pathogen genes based on homology with identified or functionally clustered genes. In this study, the genes of common pathogens were analyzed to screen and identify genes associated with intracellular survival through sequence similarity, phylogenetic tree analysis and the λ-Red recombination system test method. The total 38,952 protein-coding genes of common pathogens were divided into 19,775 clusters. As demonstrated through a COG analysis, information storage and processing genes might play an important role intracellular survival. Only 19 clusters were present in facultative intracellular pathogens, and not all were present in extracellular pathogens. Construction of a phylogenetic tree selected 18 of these 19 clusters. Comparisons with the DEG database and previous research revealed that seven other clusters are considered essential gene clusters and that seven other clusters are associated with intracellular survival. Moreover, this study confirmed that clusters screened by orthologs with similar function could be replaced with an approved uvrY gene and its orthologs, and the results revealed that the usg gene is associated with intracellular survival. The study improves the current understanding of intracellular pathogens characteristics and allows further exploration of the intracellular survival-related gene modules in these pathogens.


Assuntos
Bactérias/genética , Fenômenos Fisiológicos Bacterianos , Células/microbiologia , Genes Bacterianos , Animais , Proteínas de Bactérias/genética , Proteínas de Bactérias/fisiologia , Células Cultivadas , Genes Essenciais , Interações Hospedeiro-Patógeno , Camundongos , Família Multigênica , Filogenia
4.
Artigo em Inglês | MEDLINE | ID: mdl-29046870

RESUMO

Bacteria of the Salmonella genus cause diseases ranging from gastroenteritis to life-threatening typhoid fever and are among the most successful intracellular pathogens known. After the invasion of the eukaryotic cell, Salmonella exhibits contrasting lifestyles with different replication rates and subcellular locations. Although Salmonella hyper-replicates in the cytosol of certain host cell types, most invading bacteria remain within vacuoles in which the pathogen proliferates at moderate rates or persists in a dormant-like state. Remarkably, these cytosolic and intra-vacuolar intracellular lifestyles are not mutually exclusive and can co-exist in the same infected host cell. The mechanisms that direct the invading bacterium to follow the cytosolic or intra-vacuolar "pathway" remain poorly understood. In vitro studies show predominance of either the cytosolic or the intra-vacuolar population depending on the host cell type invaded by the pathogen. The host and pathogen factors controlling phagosomal membrane integrity and, as consequence, the egress into the cytosol, are intensively investigated. Other aspects of major interest are the host defenses that may affect differentially the cytosolic and intra-vacuolar populations and the strategies used by the pathogen to circumvent these attacks. Here, we summarize current knowledge about these Salmonella intracellular subpopulations and discuss how they emerge during the interaction of this pathogen with the eukaryotic cell.


Assuntos
Células/microbiologia , Interações Hospedeiro-Patógeno/fisiologia , Infecções por Salmonella/microbiologia , Salmonella/fisiologia , Animais , Citosol/microbiologia , Humanos , Camundongos , Vacúolos/microbiologia
5.
Annu Rev Cell Dev Biol ; 32: 373-397, 2016 10 06.
Artigo em Inglês | MEDLINE | ID: mdl-27146312

RESUMO

Bacterial pathogens encode a wide variety of effectors and toxins that hijack host cell structure and function. Of particular importance are virulence factors that target actin cytoskeleton dynamics critical for cell shape, stability, motility, phagocytosis, and division. In addition, many bacteria target organelles of the general secretory pathway (e.g., the endoplasmic reticulum and the Golgi complex) and recycling pathways (e.g., the endolysosomal system) to establish and maintain an intracellular replicative niche. Recent research on the biochemistry and structural biology of bacterial effector proteins and toxins has begun to shed light on the molecular underpinnings of these host-pathogen interactions. This exciting work is revealing how pathogens gain control of the complex and dynamic host cellular environments, which impacts our understanding of microbial infectious disease, immunology, and human cell biology.


Assuntos
Bactérias/metabolismo , Células/microbiologia , Citoesqueleto de Actina/metabolismo , Animais , Autofagia , Células/patologia , Interações Hospedeiro-Patógeno/imunologia , Humanos , Imunidade
8.
Cell Microbiol ; 16(11): 1619-26, 2014 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-25180443

RESUMO

Autophagy is an intracellular bulk degradation system in which double-membrane vesicles, called autophagosomes, engulf cytoplasmic components and later fuse with lysosomes to degrade the autophagosome content. Although autophagy was initially thought a non-selective process, recent studies have clarified that it can selectively target intracellular bacteria and function as an intracellular innate immune system that suppresses bacterial survival. A key mechanism for the recognition of cytosol-invading bacteria is ubiquitination, and the recognition of the ubiquitinated target by the autophagy machinery can be accomplished multiple ways. In this review, we discuss recent findings regarding the induction of autophagosome formation in response to intracellular bacterial invasion.


Assuntos
Autofagia , Bactérias/crescimento & desenvolvimento , Células/imunologia , Células/microbiologia , Citoplasma/microbiologia , Fagossomos/metabolismo , Animais , Células/metabolismo , Humanos , Imunidade Inata
9.
Annu Rev Cell Dev Biol ; 30: 79-109, 2014.
Artigo em Inglês | MEDLINE | ID: mdl-25103867

RESUMO

Pathogens use a vast number of strategies to alter host membrane dynamics. Targeting the host membrane machinery is important for the survival and pathogenesis of several extracellular, vacuolar, and cytosolic bacteria. Membrane manipulation promotes bacterial replication while suppressing host responses, allowing the bacterium to thrive in a hostile environment. This review provides a comprehensive summary of various strategies used by both extracellular and intracellular bacteria to hijack host membrane trafficking machinery. We start with mechanisms used by bacteria to alter the plasma membrane, delve into the hijacking of various vesicle trafficking pathways, and conclude by summarizing bacterial adaptation to host immune responses. Understanding bacterial manipulation of host membrane trafficking provides insights into bacterial pathogenesis and uncovers the molecular mechanisms behind various processes within a eukaryotic cell.


Assuntos
Fenômenos Fisiológicos Bacterianos , Membrana Celular/metabolismo , Células/microbiologia , Interações Hospedeiro-Patógeno/fisiologia , Animais , Autofagia/fisiologia , Proteínas de Bactérias/fisiologia , Toxinas Bacterianas/farmacologia , Transporte Biológico , Permeabilidade da Membrana Celular , Células/ultraestrutura , Citosol/microbiologia , Endocitose/fisiologia , Humanos , Lisossomos/fisiologia , Lipídeos de Membrana/metabolismo , Proteínas de Membrana/metabolismo , Fagossomos/fisiologia , Transporte Proteico , Vacúolos/microbiologia , Vacúolos/fisiologia
10.
Kiru ; 10(2): 91-95, jul.-dic. 2013. graf
Artigo em Espanhol | LILACS, LIPECS | ID: lil-753384

RESUMO

Objetivo. Evaluar la tasa de sobrevivencia y la capacidad preventiva de los sellantes de ion¢mero de vidrio de alta viscosidad colocadosde acuerdo al protocolo propuesto por el tratamiento restaurador atraumatico (TRA), en primeros molares permanentes en ni¤os de 6a 12 a¤os de edad, en una comunidad de alto riesgo. Material y m‚todos. Se trataron 75 primeras molares permanentes de 34 ni¤osde la Instituci¢n Educativa “Jos‚ Olaya Balandra” en el balneario de Bujama, distrito de Mala, Ca¤ete, Per£. Los sellantes se colocaronutilizando ion¢mero de vidrio de alta viscosidad siguiendo el protocolo del TRA y fueron evaluados luego de 12 meses utilizando loscriterios de la Organizaci¢n Mundial de la Salud (OMS). Resultados. Las piezas evaluadas mostraron que 56,4% present¢ sellantescompletos (c¢digo 0); el 23,6% sellantes parcialmente presentes sin caries (c¢digo 1); el 1,8% sellantes parcialmente presentes consignos de caries (c¢digo 2), y el 18,2% present¢ ausencia de sellantes sin presencia de caries (c¢digo 3). Empleando el criterio deefectividad biol¢gica se establece que 98,18% de las piezas inicialmente tratadas permanecieron libres de caries. Existi¢ una diferenciasignificativa (p<0,05) en relaci¢n a la ubicaci¢n de la pieza, observ ndose mayores tasas de retenci¢n en las primeras molares inferiores(67,9%) al compararlas con las superiores (44,4%). Conclusiones. Los sellantes TRA demostraron tener un gran potencial para prevenirlesiones de caries oclusales en primeras molares permanentes a los de 12 meses de seguimiento.


Objective. To evaluate the survival rate and preventive capacity of high viscosity glass ionomer sealants placed according to theprotocol proposed by ART, in first permanent molars in children aged 6 to 12 years old, in a high risk Peruvian community. Materialand methods. 75 first permanent molars were treated from 34 children of the school “Jose Olaya Balandra” in Bujama, district of Malain Ca¤ete, Peru. Sealants were placed using high viscosity glass ionomer following the ART protocol and they were evaluated after 12months using the World Health Organiation (WHO) criteria. Results. Evaluated pieces showed that 56, 4% had completed sealant (Code0), 23, 6% partially sealants present without caries (code 1), 1,8% partially sealants present with signs of decay (Code 2) and 18,2% hadno sealant without the presence of caries (code 3). Using the biological effectiveness criterion states that 98, 18% of the parts treatedinitially remained free of decay. There was a statistically significant difference (p <0,05) relative to the location of the piece, showinghigher retention rates in the first molars (67, 9%) when compared to higher (44,4%). Conclusions. The ART sealants showed a greatpotential to prevent oclusal caries lesions in first permanent molars after 12 months of follow up.


Assuntos
Humanos , Masculino , Feminino , Armazenamento de Substâncias, Produtos e Materiais , Células/microbiologia , Ligamento Periodontal , Sobrevivência Celular , Grupos Controle
11.
Kiru ; 10(2): 91-95, jul.-dic. 2013. graf
Artigo em Espanhol | Peru nacional | ID: pnc-17553

RESUMO

Objetivo. Evaluar la tasa de sobrevivencia y la capacidad preventiva de los sellantes de ionómero de vidrio de alta viscosidad colocadosde acuerdo al protocolo propuesto por el tratamiento restaurador atraumatico (TRA), en primeros molares permanentes en niños de 6a 12 años de edad, en una comunidad de alto riesgo. Material y métodos. Se trataron 75 primeras molares permanentes de 34 niñosde la Institución Educativa “José Olaya Balandra” en el balneario de Bujama, distrito de Mala, Cañete, Perú. Los sellantes se colocaronutilizando ionómero de vidrio de alta viscosidad siguiendo el protocolo del TRA y fueron evaluados luego de 12 meses utilizando loscriterios de la Organización Mundial de la Salud (OMS). Resultados. Las piezas evaluadas mostraron que 56,4% presentó sellantescompletos (código 0); el 23,6% sellantes parcialmente presentes sin caries (código 1); el 1,8% sellantes parcialmente presentes consignos de caries (código 2), y el 18,2% presentó ausencia de sellantes sin presencia de caries (código 3). Empleando el criterio deefectividad biológica se establece que 98,18% de las piezas inicialmente tratadas permanecieron libres de caries. Existió una diferenciasignificativa (p<0,05) en relación a la ubicación de la pieza, observándose mayores tasas de retención en las primeras molares inferiores(67,9%) al compararlas con las superiores (44,4%). Conclusiones. Los sellantes TRA demostraron tener un gran potencial para prevenirlesiones de caries oclusales en primeras molares permanentes a los de 12 meses de seguimiento. (AU)


Objective. To evaluate the survival rate and preventive capacity of high viscosity glass ionomer sealants placed according to theprotocol proposed by ART, in first permanent molars in children aged 6 to 12 years old, in a high risk Peruvian community. Materialand methods. 75 first permanent molars were treated from 34 children of the school “Jose Olaya Balandra” in Bujama, district of Malain Cañete, Peru. Sealants were placed using high viscosity glass ionomer following the ART protocol and they were evaluated after 12months using the World Health Organiation (WHO) criteria. Results. Evaluated pieces showed that 56, 4% had completed sealant (Code0), 23, 6% partially sealants present without caries (code 1), 1,8% partially sealants present with signs of decay (Code 2) and 18,2% hadno sealant without the presence of caries (code 3). Using the biological effectiveness criterion states that 98, 18% of the parts treatedinitially remained free of decay. There was a statistically significant difference (p <0,05) relative to the location of the piece, showinghigher retention rates in the first molars (67, 9%) when compared to higher (44,4%). Conclusions. The ART sealants showed a greatpotential to prevent oclusal caries lesions in first permanent molars after 12 months of follow up. (AU)


Assuntos
Humanos , Masculino , Feminino , Sobrevivência Celular , Ligamento Periodontal , Células/microbiologia , Armazenamento de Substâncias, Produtos e Materiais , Grupos Controle
12.
Immunobiology ; 218(3): 325-37, 2013 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-22795971

RESUMO

Classically labeled facultative intracellular pathogens are characterized by the ability to have an intracellular phase in the host, which is required for pathogenicity, while capable of extracellular growth in vitro. The ability of these bacteria to replicate in cell-free conditions is usually assessed by culture in artificial bacteriological media. However, the extracellular growth ability of these pathogens may also be expressed by a phase of extracellular infection in the natural setting of the host with pathologic consequences, an ability that adds to the pathogenic potential of the infectious agent. This infective capability to grow in the extracellular sites of the host represents an additional virulence attribute of those pathogens which may lead to severe outcomes. Here we discuss examples of infectious diseases where the in vivo infective extracellular life is well documented, including infections by Francisella tularensis, Yersinia pestis, Burkholderia pseudomallei, Burkholderia cenocepacia, Salmonella enterica serovar Typhimurium and Edwardsiella tarda. The occurrence of a phase of systemic dissemination with extracellular multiplication during progressive infections by facultative intracellular bacterial pathogens has been underappreciated, with most studies exclusively centered on the intracellular phase of the infections. The investigation of the occurrence of a dual lifestyle in the host among bacterial pathogens in general should be extended and likely will reveal more cases of infectious diseases with a dual infective intracellular/extracellular pattern.


Assuntos
Células/microbiologia , Infecções por Bactérias Gram-Negativas/microbiologia , Bacilos Gram-Negativos Anaeróbios Facultativos/fisiologia , Animais , Espaço Extracelular , Infecções por Bactérias Gram-Negativas/imunologia , Bacilos Gram-Negativos Anaeróbios Facultativos/patogenicidade , Interações Hospedeiro-Patógeno , Humanos , Espaço Intracelular , Virulência
13.
IEEE Trans Biomed Eng ; 59(8): 2362-71, 2012 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-22711766

RESUMO

Quantitative modeling of the phenotypic changes in the host cell during the bacterial infection makes it possible to explore an empirical relation between the infection stages and the quantifiable host-cell phenotype. A statistically reliable model of this relation can facilitate therapeutic defense against threats due to natural and genetically engineered bacterium. In the preliminary experiment, we have collected several thousand cell images over a period of 72 h of infection with a 2-h sampling frequency that covers various stages of infection by Francisella tularenesis (Ft). Segmentation of macrophages in images was accomplished using a fully automatic, parallel region growing technique. Over two thousand feature descriptors for the host cell were calculated. Multidimensional scaling, followed by hierarchical clustering, was used to group the cells. Preliminary results show that the host-cell phenotype, as defined by the set of measureable features, groups into different classes that can be mapped to the stages of infection.


Assuntos
Células/microbiologia , Técnicas Citológicas/métodos , Infecções/patologia , Carga Bacteriana/métodos , Células/classificação , Células Cultivadas , Progressão da Doença , Interações Hospedeiro-Patógeno , Humanos , Infecções/microbiologia , Fenótipo
14.
Nat Rev Immunol ; 12(5): 367-82, 2012 Apr 25.
Artigo em Inglês | MEDLINE | ID: mdl-22531325

RESUMO

Interferons (IFNs) induce the expression of hundreds of genes as part of an elaborate antimicrobial programme designed to combat infection in all nucleated cells - a process termed cell-autonomous immunity. As described in this Review, recent genomic and subgenomic analyses have begun to assign functional properties to novel IFN-inducible effector proteins that restrict bacteria, protozoa and viruses in different subcellular compartments and at different stages of the pathogen life cycle. Several newly described host defence factors also participate in canonical oxidative and autophagic pathways by spatially coordinating their activities to enhance microbial killing. Together, these IFN-induced effector networks help to confer vertebrate host resistance to a vast and complex microbial world.


Assuntos
Células/imunologia , Infecções/imunologia , Interferons/imunologia , Animais , Células/microbiologia , Células/parasitologia , Células/virologia , Humanos , Infecções/patologia
16.
Med Sci (Paris) ; 27(1): 41-7, 2011 Jan.
Artigo em Francês | MEDLINE | ID: mdl-21299961

RESUMO

Autophagy is a highly conserved, self-degradative pathway for clearance and recycling of cytoplasmic contents. This ubiquitous cell intrinsic process can be used as a defence mechanism against intracellular pathogens. Indeed autophagy is increased upon pathogen detection, and experimental extinction in vitro and in vivo of this cellular process has been demonstrated as a crucial role to control intracellular pathogens. Co-evolution between host-cells and pathogens has selected numerous micoorganisms able to avoid or usurp autophagy to their own benefit. Understanding mechanisms underlying the anti-microbial properties of autophagy as well as those used by certain pathogens to escape this cellular process might be crucial to manipulate this cellular function in order to prevent or treat infectious diseases.


Assuntos
Autofagia , Interações Hospedeiro-Patógeno/fisiologia , Animais , Fenômenos Fisiológicos Bacterianos , Células/microbiologia , Células/parasitologia , Células/virologia , Células Eucarióticas/fisiologia , HIV/fisiologia , Humanos , Interferon Tipo I/fisiologia , Fusão de Membrana , Modelos Biológicos , Fagossomos/fisiologia , Complexo de Endopeptidases do Proteassoma/fisiologia , Receptores de Reconhecimento de Padrão/fisiologia , Seleção Genética , Proteínas Modificadoras Pequenas Relacionadas à Ubiquitina/fisiologia , Resposta a Proteínas não Dobradas/fisiologia
17.
Sci Transl Med ; 2(51): 51ps48, 2010 Sep 29.
Artigo em Inglês | MEDLINE | ID: mdl-20881278

RESUMO

As a way of enhancing infections, bacterial pathogens often alter host cell signaling pathways. Here, we describe recent work that highlights a new phosphatase from an intestinal and wound-invading pathogen that manipulates host cell phosphoinositide circuits. Despite the active-site homology between bacterial inositol phosphatases and mammalian phosphatases, sequence differences between them suggest that the development of specific inhibitors may be feasible.


Assuntos
Bactérias/metabolismo , Células/metabolismo , Células/microbiologia , Interações Hospedeiro-Patógeno , Transdução de Sinais , Animais , Humanos
19.
Lett Appl Microbiol ; 50(6): 633-8, 2010 Jun 01.
Artigo em Inglês | MEDLINE | ID: mdl-20438617

RESUMO

AIM: Contamination by Mollicutes is a significant challenge for research laboratories and biopharmaceutical industry. It leads to alteration of results or production quality as well as loss of time, materials and revenue. These organisms can czoriginate from mammalian, avian, insect, plant or fish cells. Culture-based methods may require 28 days to detect Mollicutes. Traditional microbiology could advantageously be replaced by nucleic acid testing for earlier detection. METHODS AND RESULTS: A membrane filtration-based concentration of the Mollicutes has been coupled to real-time transcription-mediated amplification (real-time TMA) to demonstrate these advantages. The eight species required by European Pharmacopoeia have been tested and were detected with sensitivity below 100 CFU per 20-ml sample. Co-culture experiments, in which Mollicutes are grown with CHO-S (suspension) or HEK 293 (adherent) cells, were also performed to respectively mimic a bioreactor or flask contamination. Despite the fact that Mollicutes can attach to or invade mammalian cells, they were consistently detected over multiple days. CONCLUSIONS: the sample preparation and amplification method used in this study increases sensitivity and reduces time-to-result for detection of Mollicutes. SIGNIFICANCE AND IMPACT OF THE STUDY: the described system allows real-time monitoring for microbial contamination of cell-based processes and products for the biopharmaceutical industry.


Assuntos
Reatores Biológicos/microbiologia , Reação em Cadeia da Polimerase/métodos , Tenericutes/isolamento & purificação , Animais , Células CHO , Linhagem Celular , Células/microbiologia , Cricetinae , Cricetulus , Humanos , Tenericutes/genética , Transcrição Genética
SELEÇÃO DE REFERÊNCIAS
DETALHE DA PESQUISA