The bile salt glycocholate induces global changes in gene and protein expression and activates virulence in enterotoxigenic Escherichia coli

Pathogenic bacteria use specific host factors to modulate virulence and stress responses during infection. We found previously that the host factor bile and the bile component glyco-conjugated cholate (NaGCH, sodium glycocholate) upregulate the colonization factor CS5 in enterotoxigenic Escherichia coli (ETEC). To further understand the global regulatory effects of bile and NaGCH, we performed Illumina RNA-Seq and found that crude bile and NaGCH altered the expression of 61 genes in CS5 + CS6 ETEC isolates. The most striking finding was high induction of the CS5 operon (csfA-F), its putative transcription factor csvR, and the putative ETEC virulence factor cexE. iTRAQ-coupled LC-MS/MS proteomic analyses verified induction of the plasmid-borne virulence proteins CS5 and CexE and also showed that NaGCH affected the expression of bacterial membrane proteins. Furthermore, NaGCH induced bacteria to aggregate, increased their adherence to epithelial cells, and reduced their motility. Our results indicate that CS5 + CS6 ETEC use NaGCH present in the small intestine as a signal to initiate colonization of the epithelium

The Chaperone IpgC Copurifies with the Virulence Regulator MxiE▿

The expression of a subset of Shigella flexneri virulence genes is dependent upon a cytoplasmic chaperone, IpgC, and an activator from the AraC/XylS family, MxiE. In this paper, we report that the chaperone forms a specific and stable heteromer with MxiE

CfaD-Dependent Expression of a Novel Extracytoplasmic Protein from Enterotoxigenic Escherichia coli

H10407 is a strain of enterotoxigenic Escherichia coli (ETEC) that utilizes CFA/I pili to adhere to surfaces of the small intestine, where it elaborates toxins that cause profuse watery diarrhea in humans. Expression of the CFA/I pilus is positively regulated at the level of transcription by CfaD, a member of the AraC/XylS family. DNase I footprinting revealed that the activator has two binding sites upstream of the pilus promoter cfaAp . One site extends from positions −23 to −56, and the other extends from positions −73 to −103 (numbering relative to the transcription start site of cfaAp ). Additional CfaD binding sites were predicted within the genome of H10407 by computational analysis. Two of these sites lie upstream of a previously uncharacterized gene, cexE . In vitro DNase I footprinting confirmed that both sites are genuine binding sites, and cexEp :: lacZ reporters demonstrated that CfaD is required for the expression of cexE in vivo. The amino terminus of CexE contains a secretory signal peptide that is removed during translocation across the cytoplasmic membrane through the general secretory pathway. These studies suggest that CexE may be a novel ETEC virulence factor because its expression is controlled by the virulence regulator CfaD, and its distribution is restricted to ETEC

Repression of the Inner Membrane Lipoprotein NlpA by Rns in Enterotoxigenic Escherichia coli

The expression of the inner membrane protein NlpA is repressed by the enterotoxigenic Escherichia coli (ETEC) virulence regulator Rns, a member of the AraC/XylS family. The Rns homologs CfaD from ETEC and AggR from enteroaggregative E. coli also repress expression of nlpA. In vitro DNase I and potassium permanganate footprinting revealed that Rns binds to a site overlapping the start codon of nlpA, preventing RNA polymerase from forming an open complex at nlpAp. A second Rns binding site between positions −152 and −195 relative to the nlpA transcription start site is not required for repression. NlpA is not essential for growth of E. coli under laboratory conditions, but it does contribute to the biogenesis of outer membrane vesicles. As outer membrane vesicles have been shown to contain ETEC heat-labile toxin, the repression of nlpA may be an indirect mechanism through which the virulence regulators Rns and CfaD limit the release of toxin

Experimental comparison for the calculation of rock wettability using the amott-harvey method and a new visual method

This article provides the results of the implementation of the Amott-Harvey method (quantitative) and the visual method (qualitative) to determine the wettability of the rock in core samples from the Mugrosa Formation of the Colorado Field, in order to learn about the distribution of fluids in the reservoir, as this property affects various aspects of the production performance thereof. Wettability is determined first by restoring the wettability of the samples, for 200 hours and 1000 hours at reservoir conditions (T = 144°F and P = 1350 psi). After that, rock wettability is calculated using the Amott-Harvey method, obtaining results of neutral wettability. It is then determined by the visual method for comparison purposes, in order to conclude that rock wettability is neutral. It is important to emphasize that the visual method is of great relevance, because it provides a real view of how the fluids are distributed within the rock to obtain representative results, in order to make decisions that optimizes the production of the field under study.Este artigo apresenta os resultados da implantação do método Amott-Harvey (quantitativo) e do método visual (qualitativo) para a determinação da molhabilidade da rocha em amostras de corações da formação Mugrosa do campo Colorado, e desta forma conhecer como é a distribuição de fluídos dentro da jazida; já que dita propriedade incide em numerosos aspectos do desempenho de produção da jazida. Inicialmente, a determinação da molhabilidade é realizada restaurando a molhabilidade das amostras; umas a 200 horas e outras a 1000 horas com relação às condições da jazida (T = 144°F e P = 1350 psi). Posteriormente, a molhabilidade da rocha é calculada com o método Amott-Harvey, obtendo resultados de uma molhabilidade neutra. Logo, é realizada a determinação da molhabilidade pelo método visual para gerar uma comparação e desta forma poder concluir que a molhabilidade da rocha é de tipo neutra. É importante ressaltar que o método visual é de grande aplicabilidade, pois permite visualizar de forma real como são distribuídos os fluídos dentro da rocha e obter resultados representativos, para assim poder tomar decisões na hora de aperfeiçoar a produção do campo em estudo.Este artículo presenta los resultados de la implementación del método Amott-Harvey (cuantitativo) y el método visual (cualitativo) para la determinación de la mojabilidad de la roca en muestras de corazones de la formación Mugrosa del campo Colorado, y de esta forma conocer como es la distribución de fluidos dentro del yacimiento; ya que dicha propiedad incide en numerosos aspectos del desempeño de producción del yacimiento. La determinación de la mojabilidad se realiza en primera medida restaurando la mojabilidad de las muestras; unas a 200 horas y otras a 1000 horas con respecto a las condiciones de yacimiento (T = 144°F y P = 1350 psi). Posteriormente se calcula la mojabilidad de la roca con el método Amott-Harvey, obteniendo resultados de una mojabilidad neutra. Luego se realiza la determinación de la mojabilidad por el método visual para generar una comparación y de esta forma poder concluir que la mojabilidad de la roca es de tipo neutra. Es importante resaltar que el método visual es de gran aplicabilidad, pues nos permite visualizar de forma real como se distribuyen los fluidos dentro de la roca y obtener resultados representativos, para así poder tomar decisiones a la hora de optimizar la producción del campo en estudio

The AraC/XylS protein MxiE and its co-regulator IpgC control a negative feedback loop in the transcriptional cascade that regulates type III secretion in Shigella flexneri

Members of the AraC Family of Transcriptional Regulators (AFTRs) control the expression of many genes important to cellular processes, including virulence. In Shigella species, the type III secretion system (T3SS), a key determinant for host cell invasion, is regulated by the three-tiered VirF/VirB/MxiE transcription cascade. Both VirF and MxiE belong to the AFTRs and are characterized as positive transcriptional regulators. Here, we identify a novel regulatory activity for MxiE and its co-regulator IpgC, which manifests as a negative feedback loop in the VirF/VirB/MxiE transcription cascade. Our findings show that MxiE and IpgC down-regulate the virB promoter and hence VirB protein production, thus, decreasing VirB-dependent promoter activity at ospD1, one of the nearly 50 VirB-dependent genes. At the virB promoter, regions required for negative MxiE- and IpgC-dependent regulation were mapped and found to be coincident with regions required for positive VirF-dependent regulation. In tandem, negative MxiE- and IpgC-dependent regulation of the virB promoter only occurred in the presence of VirF suggesting that MxiE and IpgC can function to counter VirF activation of the virB promoter. Lastly, MxiE and IpgC do not down-regulate another VirF-activated promoter, icsA, demonstrating that this negative feedback loop targets the virB promoter. Our study provides insight into a mechanism that may reprogram Shigella virulence gene expression following type III secretion and provides the impetus to examine if MxiE and IpgC homologs in other important bacterial pathogens such as Burkholderia pseudomallei and Salmonella enterica serovars Typhimurium and Typhi coordinate similar negative feedback loops

Theory of inpatient circadian care (TICC): A proposal for a middle-range theory

The circadian system controls the daily rhythms of a variety of physiological processes. Most organisms show physiological, metabolic and behavioral rhythms that are coupled to environmental signals. In humans, the main synchronizer is the light/dark cycle, although non-photic cues such as food availability, noise, and work schedules are also involved. In a continuously operating hospital, the lack of rhythmicity in these elements can alter the patient’s biological rhythms and resilience. This paper presents a Theory of Inpatient Circadian Care (TICC) grounded in circadian principles. We conducted a literature search on biological rhythms, chronobiology, nursing care, and middle-range theories in the databases PubMed, SciELO Public Health, and Google Scholar. The search was performed considering a period of 6 decades from 1950 to 2013. Information was analyzed to look for links between chronobiology concepts and characteristics of inpatient care. TICC aims to integrate multidisciplinary knowledge of biomedical sciences and apply it to clinical practice in a formal way. The conceptual points of this theory are supported by abundant literature related to disease and altered biological rhythms. Our theory will be able to enrich current and future professional practice.Fil: Camargo Sanchez, Andrés. Universidad de Ciencias Aplicadas y Ambientales; ColombiaFil: Niño, Carmen L.. Universidad de Ciencias Aplicadas y Ambientales; ColombiaFil: Sánchez, Leonardo. Universidad de Ciencias Aplicadas y Ambientales; ColombiaFil: Echeverri, Sonia. Fundacion Santa Fe de Bogota; ColombiaFil: Gutiérrez, Diana P.. Fundacion Santa Fe de Bogota; ColombiaFil: Duque, Andrés F.. Marly Clinic; ColombiaFil: Pianeta, Oscar. Universidad de Ciencias Aplicadas y Ambientales; ColombiaFil: Jaramillo Gómez, Jenny A.. Universidad Nacional de Colombia; ColombiaFil: Pilonieta, Martin A.. Universidad Nacional de Colombia; ColombiaFil: Cataño, Nhora. Universidad Nacional de Colombia; ColombiaFil: Arboleda, Humberto. Universidad Nacional de Colombia; ColombiaFil: Agostino, Patricia. Universidad Nacional de Quilmes. Departamento de Ciencia y Tecnología. Laboratorio de Cronobiología; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Alvarez Baron, Claudia P.. University of Wisconsin; Estados UnidosFil: Vargas, Rafael. Pontificia Universidad Javeriana; Colombi