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INTRODUCTION: The inflammatory state that accompanies adiposity and the metabolic syndrome (MetS) is called "low-grade" inflammation. White blood cell count (WBC) has been proposed as an emerging biomarker for predicting future cardiovascular events, MetS and mortality. Bariatric surgery (BS) improves comorbidities associated with obesity and the MetS and the surgically induced weight loss is known to improve inflammatory status. OBJECTIVES: To analyze the improvement of low-grade inflammation associated to obesity in patients with metabolically healthy severe obesity (MHSO) and patients with metabolically unhealthy obesity (MUSO) (severe obesity with MetS) after primary bariatric surgery as well as the protective effect of BS against the development of MetS in patients with MHSO by reducing the WBC. MATERIALS AND METHODS: Retrospective analysis of prospectively collected data of patients undergoing laparoscopic primary BS (gastric by-pass or sleeve gastrectomy) from January 2004-December 2015. Outcomes included changing of low-grade inflammation in terms of leukocytes, neutrophils, lymphocytes, and platelets. RESULTS: Twenty-one patients with MHSO and 167 patients with MUSO underwent laparoscopic primary BS. The preoperative values of leukocyte and platelet were statistically higher in the group of patients with MHSO. In both groups, there was significant postoperative decrease of inflammatory markers. The greatest drop in WBC occurred in the second postoperative year. No patient of the group of patients with MHSO developed MetS within five postoperative years. CONCLUSIONS: Surgically induced weight loss plays an important role for improvement in chronic inflammation associated to obesity because of reduction of visceral fat mass. MHSO associates a low-grade chronic inflammatory status comparable to MUSO. The improvement or decrease of low-grade inflammation in patients with metabolically healthy severe obesity after bariatric surgery could have a protective effect against the development of MetS and medical conditions associated with severe obesity.
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Cirugía Bariátrica , Síndrome Metabólico , Obesidad Metabólica Benigna , Obesidad Mórbida , Humanos , Obesidad Mórbida/cirugía , Estudios Retrospectivos , Obesidad/cirugía , Cirugía Bariátrica/efectos adversos , Síndrome Metabólico/complicaciones , Obesidad Metabólica Benigna/cirugía , Pérdida de Peso , Inflamación/complicaciones , Gastrectomía/efectos adversosRESUMEN
Azospirillum baldaniorum Sp245, a plant growth-promoting rhizobacterium, can form biofilms through a process controlled by the second messenger cyclic diguanylate monophosphate (c-di-GMP). A. baldaniorum has a variety of proteins potentially involved in controlling the turnover of c-di-GMP many of which are coupled to sensory domains that could be involved in establishing a mutualistic relationship with the host. Here, we present in silico analysis and experimental characterization of the function of CdgB (AZOBR_p410089), a predicted MHYT-PAS-GGDEF-EAL multidomain protein from A. baldaniorum Sp245. When overproduced, CdgB behaves predominantly as a c-di-GMP phosphodiesterase (PDE) in A. baldaniorum Sp245. It inhibits biofilm formation and extracellular polymeric substances production and promotes swimming motility. However, a CdgB variant with a degenerate PDE domain behaves as diguanylate cyclase (DGC). This strongly suggest that CdgB is capable of dual activity. Variants with alterations in the DGC domain and the MHYT domain negatively affects extracellular polymeric substances production and induction of swimming motility. Surprisingly, we observed that overproduction of CdgB results in increased c-di-GMP accumulation in the heterologous host Escherichia coli, suggesting under certain conditions, the WT CdgB variant can behave predominantly as a DGC. Furthermore, we also demonstrated that CdgB is anchored to the cell membrane and localizes potentially to the cell poles. This localization is dependent on the presence of the MHYT domain. In summary, our results suggest that CdgB can provide versatility to signaling modules that control motile and sessile lifestyles in response to key environmental signals in A. baldaniorum.
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Azospirillum , Proteínas Bacterianas , Proteínas Bacterianas/genética , Proteínas Bacterianas/metabolismo , GMP Cíclico/metabolismo , Regulación Bacteriana de la Expresión Génica , Hidrolasas Diéster Fosfóricas/metabolismoRESUMEN
Azospirillum baldaniorum is a plant growth-promoting rhizobacterium (PGPR) capable of fixing nitrogen, the synthesis of several phytohormones including indole-acetic acid, and induction of plant defenses against phytopathogens. To establish a successful and prolonged bacteria-plant interaction, A. baldaniorum can form biofilms, bacterial communities embedded in a self-made matrix formed by extracellular polymeric substances which provide favorable conditions for survival. A key modulator of biofilm formation is the second messenger bis-(3'-5')-cyclic-dimeric-GMP (c-di-GMP), which is synthesized by diguanylate cyclases (DGC) and degraded by specific phosphodiesterases. In this study, we analyzed the contribution of a previously uncharacterized diguanylate cyclase designated CdgC, to biofilm formation and bacterial-plant interaction dynamics. We showed that CdgC is capable of altering c-di-GMP levels in a heterologous host, strongly supporting its function as a DGC. The deletion of cdgC resulted in alterations in the three-dimensional structure of biofilms in a nitrogen-source dependent manner. CdgC was required for optimal colonization of wheat roots. Since we also observed that CdgC played an important role in exopolysaccharide production, we propose that this signaling protein activates a physiological response that results in the strong attachment of bacteria to the roots, ultimately contributing to an optimal bacterium-plant interaction. Our results demonstrate that the ubiquitous second messenger c-di-GMP is a key factor in promoting plant colonization by the PGPR A. baldaniorum by allowing proficient internalization in wheat roots. Understanding the molecular basis of PGPR-plant interactions will enable the design of better biotechnological strategies of agro-industrial interest.
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The plant growth-promoting bacterium Azospirillum brasilense contains several genes encoding proteins involved in the biosynthesis and degradation of the second messenger cyclic-di-GMP, which may control key bacterial functions, such as biofilm formation and motility. Here, we analysed the function and expression of the cdgD gene, encoding a multidomain protein that includes GGDEF-EAL domains and CHASE and PAS domains. An insertional cdgD gene mutant was constructed, and analysis of biofilm and extracellular polymeric substance production, as well as the motility phenotype indicated that cdgD encoded a functional diguanylate protein. These results were correlated with a reduced overall cellular concentration of cyclic-di-GMP in the mutant over 48 h compared with that observed in the wild-type strain, which was recovered in the complemented strain. In addition, cdgD gene expression was measured in cells growing under planktonic or biofilm conditions, and differential expression was observed when KNO3 or NH4Cl was added to the minimal medium as a nitrogen source. The transcriptional fusion of the cdgD promoter with the gene encoding the autofluorescent mCherry protein indicated that the cdgD gene was expressed both under abiotic conditions and in association with wheat roots. Reduced colonization of wheat roots was observed for the mutant compared with the wild-type strain grown in the same soil conditions. The Azospirillum-plant association begins with the motility of the bacterium towards the plant rhizosphere followed by the adsorption and adherence of these bacteria to plant roots. Therefore, it is important to study the genes that contribute to this initial interaction of the bacterium with its host plant.
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Azospirillum brasilense/genética , GMP Cíclico/genética , GMP Cíclico/metabolismo , Regulación Bacteriana de la Expresión Génica/genética , Expresión Génica , Interacciones Microbiota-Huesped/genética , Dominios Proteicos/genética , Azospirillum brasilense/fisiología , Adhesión Bacteriana , Proteínas Bacterianas/genética , Proteínas Bacterianas/metabolismo , Mutación , Raíces de Plantas/microbiología , Sistemas de Mensajero Secundario , Triticum/microbiologíaRESUMEN
In this study, new polyurethanes (PUs) were prepared by using inulin and polycaprolactone as polyols. Their structure and morphology were determined by Fourier transform infrared spectroscopy (FTIR), Raman dispersive spectroscopy, Nuclear magnetic resonance spectroscopy (1H NMR and 13C NMR), and scanning electron microscopy (SEM), whereas their mechanical properties were evaluated by a universal testing machine. Additionally, their water uptake, swelling behavior, and degradation were evaluated to be used as drug delivery carriers. Therefore, an anti-cancer drug was loaded to these PUs with 25% of loading efficiency and its release behavior was studied using different theoretical models to unveil its mechanism. Finally, the ability of the new PUs to be used as a clip marker in breast biopsy was evaluated. The results clearly demonstrate that these PUs are safe and can be used as intelligent drug release matrices for targeted drug delivery and exhibits positive results to be used for clip marker and in general for breast cancer applications.
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Elucidation of biofilm structure formation in the plant growth-promoting rhizobacterium Azospirillum brasilense is necessary to gain a better understanding of the growth of cells within the extracellular matrix and its role in the colonization of plants of agronomic importance. We used immunofluorescence microscopy and confocal laser scanning microscopy to study spatio-temporal biofilm formation on an abiotic surface. Observations facilitated by fluorescence microscopy revealed the presence of polar flagellin, exopolysaccharides, outer major membrane protein (OmaA) and extracellular DNA in the Azospirillum biofilm matrix. In static culture conditions, the polar flagellum disaggregated after 3 days of biofilm growth, but exopolysaccharides were increasing. These findings suggest that the first step in biofilm formation may be attachment, in which the bacterium first makes contact with a surface through its polar flagellum. After attaching to the surface, the long flagella and OmaA intertwine the cells to form a network. These bacterial aggregates initiate biofilm development. The underlying mechanisms dictating how the biofilm matrix components of A. brasilense direct the overall morphology of the biofilm are not well known. The methods developed here might be useful in further studies that analyze the differential spatial regulation of genes encoding matrix components that drive biofilm construction.
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Azospirillum brasilense/fisiología , Biopelículas/crecimiento & desarrollo , Matriz Extracelular de Sustancias Poliméricas/metabolismo , Azospirillum brasilense/crecimiento & desarrollo , Proteínas de la Membrana Bacteriana Externa/metabolismo , ADN Bacteriano/metabolismo , Flagelina/metabolismo , Cinética , Microscopía Confocal , Microscopía Fluorescente , Polisacáridos Bacterianos/metabolismoRESUMEN
Azospirillum brasilense is one of the most studied species of diverse agronomic plants worldwide. The benefits conferred to plants inoculated with Azospirillum have been primarily attributed to its capacity to fix atmospheric nitrogen and synthesize phytohormones, especially indole-3-acetic acid (IAA). The principal pathway for IAA synthesis involves the intermediate metabolite indole pyruvic acid. Successful colonization of plants by Azospirillum species is fundamental to the ability of these bacteria to promote the beneficial effects observed in plants. Biofilm formation is an essential step in this process and involves interactions with the host plant. In this study, the tyrR gene was cloned, and the translated product was observed to exhibit homology to TyrR protein, a NtrC/NifA-type activator. Structural studies of TyrR identified three putative domains, including a domain containing binding sites for aromatic amino acids in the N-terminus, a central AAA+ ATPase domain, and a helix-turn-helix DNA binding motif domain in the C-terminus, which binds DNA sequences in promoter-operator regions. In addition, a bioinformatic analysis of promoter sequences in A. brasilense Sp7 genome revealed that putative promoters encompass one to three TyrR boxes in genes predicted to be regulated by TyrR. To gain insight into the phenotypes regulated by TyrR, a tyrR-deficient strain derived from A. brasilense Sp7, named A. brasilense 2116 and a complemented 2116 strain harboring a plasmid carrying the tyrR gene were constructed. The observed phenotypes indicated that the putative transcriptional regulator TyrR is involved in biofilm production and is responsible for regulating the utilization of D-alanine as carbon source. In addition, TyrR was observed to be absolutely required for transcriptional regulation of the gene dadA encoding a D-amino acid dehydrogenase. The data suggested that TyrR may play a major role in the regulation of genes encoding a glucosyl transferase, essential signaling proteins, and amino acids transporters.
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Aspergillus , Biopelículas/crecimiento & desarrollo , Proteínas Fúngicas , Factores de Transcripción , Aspergillus/química , Aspergillus/fisiología , D-Aminoácido Oxidasa/biosíntesis , D-Aminoácido Oxidasa/genética , Proteínas Fúngicas/química , Proteínas Fúngicas/genética , Secuencias Hélice-Giro-Hélice , Dominios Proteicos , Elementos de Respuesta , Factores de Transcripción/química , Factores de Transcripción/genética , Factores de Transcripción/metabolismo , Transcripción Genética/fisiologíaRESUMEN
This study reports the introduction of egfp or mCherry markers to the Sp245, Sp7, and M40 wild-type strains of Azospirillum brasilense and the hhkB (encoding for a putative hybrid histidine kinase) minus mutant an isogenic strain of A. brasilense Sp245 to monitor colonization of wheat (Triticum aestivum). Two plasmids were constructed: (1) the pJMS-2 suicide plasmid derived from pSUP202 and harboring the mCherry gene expressed under the constitutive kanamycin resistance promoter to create a cis tag and (2) the broad-range plasmid pMP2449-5 that carries the mCherry gene under the lac promoter, which is derived from the plasmid pMP2444; to create the in trans tag. The stability of the plasmids encoding egfp and mCherry were confirmed in vitro for seven days of bacterial growth, and then, the A. brasilense strains harboring the plasmids were studied under nonselective conditions for adherence to seeds and, at seven or 14 days post-inoculation, for wheat root colonization. The utility of the labeled strains was proven by observation, using fluorescence microscopy and confocal laser scanning microscopy (CLSM) in wheat plants inoculated with the labeled strains and compared with the CFU g-1 for seed and wheat root. The method was suitable for observation of the in situ formation of mini-colonies, enabled visualization of bacterial colonization sites on large root fragments, and showed adherence to germinated seeds and root colonization of all strains by cell counts and direct microscopic examination. Thus, we are able to quantify the structures of the biofilms formed by each strain.
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Azospirillum brasilense/genética , Biopelículas/crecimiento & desarrollo , Proteínas Fluorescentes Verdes/genética , Proteínas Luminiscentes/genética , Raíces de Plantas/microbiología , Triticum/microbiología , Azospirillum brasilense/fisiología , Proteínas Bacterianas/genética , Proteínas Bacterianas/metabolismo , ADN Bacteriano/genética , ADN Bacteriano/aislamiento & purificación , Regulación Bacteriana de la Expresión Génica , Genes Bacterianos/genética , Vectores Genéticos , Plásmidos , Regiones Promotoras Genéticas , Semillas/crecimiento & desarrollo , Proteína Fluorescente RojaRESUMEN
BACKGROUND: The cyclic-di-GMP (c-di-GMP) second messenger exemplifies a signaling system that regulates many bacterial behaviors of key importance; among them, c-di-GMP controls the transition between motile and sessile life-styles in bacteria. Cellular c-di-GMP levels in bacteria are regulated by the opposite enzymatic activities of diguanylate cyclases and phosphodiesterases, which are proteins that have GGDEF and EAL domains, respectively. Azospirillum is a genus of plant-growth-promoting bacteria, and members of this genus have beneficial effects in many agronomically and ecologically essential plants. These bacteria also inhabit aquatic ecosystems, and have been isolated from humus-reducing habitats. Bioinformatic and structural approaches were used to identify genes predicted to encode GG[D/E]EF, EAL and GG[D/E]EF-EAL domain proteins from nine genome sequences. RESULTS: The analyzed sequences revealed that the genomes of A. humicireducens SgZ-5T, A. lipoferum 4B, Azospirillum sp. B510, A. thiophilum BV-ST, A. halopraeferens DSM3675, A. oryzae A2P, and A. brasilense Sp7, Sp245 and Az39 encode for 29 to 41 of these predicted proteins. Notably, only 15 proteins were conserved in all nine genomes: eight GGDEF, three EAL and four GGDEF-EAL hybrid domain proteins, all of which corresponded to core genes in the genomes. The predicted proteins exhibited variable lengths, architectures and sensor domains. In addition, the predicted cellular localizations showed that some of the proteins to contain transmembrane domains, suggesting that these proteins are anchored to the membrane. Therefore, as reported in other soil bacteria, the Azospirillum genomes encode a large number of proteins that are likely involved in c-di-GMP metabolism. In addition, the data obtained here strongly suggest host specificity and environment specific adaptation. CONCLUSIONS: Bacteria of the Azospirillum genus cope with diverse environmental conditions to survive in soil and aquatic habitats and, in certain cases, to colonize and benefit their host plant. Gaining information on the structures of proteins involved in c-di-GMP metabolism in Azospirillum appears to be an important step in determining the c-di-GMP signaling pathways, involved in the transition of a motile cell towards a biofilm life-style, as an example of microbial genome plasticity under diverse in situ environments.
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Azospirillum/genética , Azospirillum/metabolismo , Proteínas Bacterianas/genética , Proteínas Bacterianas/metabolismo , GMP Cíclico/análogos & derivados , Dominios Proteicos , Transducción de Señal , Adaptación Biológica , Azospirillum/enzimología , Biopelículas/crecimiento & desarrollo , Biología Computacional , GMP Cíclico/metabolismo , Proteínas de Escherichia coli/metabolismo , Regulación Bacteriana de la Expresión Génica , Modelos Moleculares , Hidrolasas Diéster Fosfóricas/metabolismo , Liasas de Fósforo-Oxígeno/metabolismo , Conformación Proteica , Sistemas de Mensajero Secundario/genéticaRESUMEN
In bacteria, proteins containing GGDEF domains are involved in production of the second messenger c-di-GMP. Here we report that the cdgA gene encoding diguanylate cyclase A (CdgA) is involved in biofilm formation and exopolysaccharide (EPS) production in Azospirillum brasilense Sp7. Biofilm quantification using crystal violet staining revealed that inactivation of cdgA decreased biofilm formation. In addition, confocal laser scanning microscopy analysis of green-fluorescent protein-labeled bacteria showed that, during static growth, the biofilms had differential levels of development: bacteria harboring a cdgA mutation exhibited biofilms with considerably reduced thickness compared with those of the wild-type Sp7 strain. Moreover, DNA-specific staining and treatment with DNase I, and epifluorescence studies demonstrated that extracellular DNA and EPS are components of the biofilm matrix in Azospirillum. After expression and purification of the CdgA protein, diguanylate cyclase activity was detected. The enzymatic activity of CdgA-producing cyclic c-di-GMP was determined using GTP as a substrate and flavin adenine dinucleotide (FAD(+)) and Mg(2)(+) as cofactors. Together, our results revealed that A. brasilense possesses a functional c-di-GMP biosynthesis pathway.
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Azospirillum brasilense/enzimología , Azospirillum brasilense/fisiología , Biopelículas/crecimiento & desarrollo , GMP Cíclico/análogos & derivados , Proteínas de Escherichia coli/metabolismo , Liasas de Fósforo-Oxígeno/metabolismo , Polisacáridos Bacterianos/biosíntesis , Azospirillum brasilense/genética , Técnicas Bacteriológicas , Coenzimas/metabolismo , GMP Cíclico/metabolismo , Proteínas de Escherichia coli/aislamiento & purificación , Flavina-Adenina Dinucleótido/metabolismo , Guanosina Trifosfato/metabolismo , Magnesio/metabolismo , Microscopía Confocal , Liasas de Fósforo-Oxígeno/aislamiento & purificación , Coloración y EtiquetadoRESUMEN
Plant growth-promoting bacteria of the genus Azospirillum are present in the rhizosphere and as endophytes of many crops. In this research we studied 40 Azospirillum strains isolated from different plants and geographic regions. They were first characterized by 16S rDNA restriction analysis, and their phylogenetic position was established by sequencing the genes 16S rDNA, ipdC, hisC1, and hisC2. The latter three genes are involved in the indole-3-pyruvic acid (IPyA) biosynthesis pathway of indole-3-acetic acid (IAA). Furthermore, the suitability of the 16S-23S rDNA intergenic spacer sequence (IGS) for the differentiation of closely related Azospirillum taxa and development of PCR protocols allows for specific detection of strains. The IGS-RFLP analysis enabled intraspecies differentiation, particularly of Azospirillum brasilense and Azospirillum lipoferum strains. Results demonstrated that the ipdC, hisC1, and hisC2 genes are highly conserved in all the assessed A. brasilense isolates, suggesting that these genes can be used as an alternative phylogenetic marker. In addition, IAA production determined by HPLC ranged from 0.17 to 98.2 µg mg(-1) protein. Southern hybridization with the A. brasilense ipdC gene probe did not show, a hybridization signal with A. lipoferum, Azospirillum amazonense, Azospirillum halopreferans and Azospirillum irakense genomic DNA. This suggests that these species produce IAA by other pathways. Because IAA is mainly synthesized via the IPyA pathway in A. brasilense strains, a species that is used worldwide in agriculture, the identification of ipdC, hisC1, and hisC2 genes by PCR may be suitable for selecting exploitable strains.
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Azospirillum brasilense/clasificación , Azospirillum brasilense/genética , Vías Biosintéticas/genética , Genes Bacterianos , Ácidos Indolacéticos/metabolismo , Azospirillum brasilense/metabolismo , Southern Blotting , Cromatografía Líquida de Alta Presión , Análisis por Conglomerados , ADN Bacteriano/química , ADN Bacteriano/genética , ADN Ribosómico/química , ADN Ribosómico/genética , ADN Espaciador Ribosómico , Datos de Secuencia Molecular , Filogenia , Plantas/microbiología , Polimorfismo de Longitud del Fragmento de Restricción , ARN Ribosómico 16S/genética , ARN Ribosómico 23S/genética , Análisis de Secuencia de ADNRESUMEN
Bacterial biofilms are ubiquitous in nature, and their flexibility is derived in part from a complex extracellular matrix that can be made-to-order to cope with environmental demand. Although common developmental stages leading to biofilm formation have been described, an in-depth knowledge of genetic and signaling is required to understand biofilm formation. Bacteria detect changes in population density by quorum sensing and particular environmental conditions, using signals such as cyclic di-GMP or nitric oxide. The significance of understanding these signaling pathways lies in that they control a broad variety of functions such as biofilm formation, and motility, providing benefits to bacteria as regards host colonization, defense against competitors, and adaptation to changing environments. Due to the importance of these features, we here review the signaling network and regulatory connections among quorum sensing, c-di-GMP and nitric oxide involving biofilm formation.
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Biopelículas/crecimiento & desarrollo , GMP Cíclico/análogos & derivados , Óxido Nítrico/fisiología , Percepción de Quorum/fisiología , Transducción de Señal/fisiología , Adhesión Bacteriana/fisiología , Proteínas Bacterianas/fisiología , GMP Cíclico/fisiología , Regulación Bacteriana de la Expresión Génica , Modelos Biológicos , Sistemas de Mensajero Secundario/fisiología , Virulencia/fisiologíaRESUMEN
Las bacterias forman biopelículas de manera ubicua, y esta característica les otorga una flexibilidad que es resultado, en parte, de una matriz compleja construida según las exigencias de las condiciones ambientales. Aunque los estadios de la formación de las biopelículas bacterianas se conocen con detalle, para entender con profundidad la formación de las biopelículas es deseable un conocimiento mayor de los mecanismos de señalización. Las bacterias detectan cambios en la densidad de población por regulación del quórum y condiciones específicas, empleando señales como el di-GMPc y el óxido nítrico. La importancia del conocimiento de estas vías de señalización radica en que controlan una variedad de funciones, como la formación de biopelículas y la movilidad, y proporcionan a las bacterias beneficios en la colonización del hospedador, la defensa contra competidores y los cambios adversos del entorno. Por la trascendencia que revisten estos aspectos, revisamos aquí las redes de regulación y la conexión de la señalización entre quorum sensing, di-GMPc y óxido nítrico
Bacterial biofilms are ubiquitous in nature, and their flexibility is derived in part from a complex extracellular matrix that can be made-to-order to cope with environmental demand. Although common developmental stages leading to biofilm formation have been described, an in-depth knowledge of genetic and signaling is required to understand biofilm formation. Bacteria detect changes in population density by quorum sensing and particular environmental conditions, using signals such as cyclic di-GMP or nitric oxide. The significance of understanding these signaling pathways lies in that they control a broad variety of functions such as biofilm formation, and motility, providing benefits to bacteria as regards host colonization, defense against competitors, and adaptation to changing environments. Due to the importance of these features, we here review the signaling network and regulatory connections among quorum sensing, c-di-GMP and nitric oxide involving biofilm formation
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Biopelículas/crecimiento & desarrollo , GMP Cíclico/biosíntesis , Percepción de Quorum/fisiología , Óxido Nítrico/biosíntesisRESUMEN
Fundamento: se necesita que los docentes de la educación médica utilicen los medios de enseñanza de una manera correcta y eficaz, para potenciar el proceso enseñanza aprendizaje. Métodos: se realizó una investigación descriptiva, en la Filial de Ciencias Médicas de Sagua la Grande, desde enero 2008 a marzo 2009, con el objetivo de elaborar una estrategia metodológica para el uso de los medios de enseñanza, dirigida a los docentes de las carreras de Tecnologías de la Salud. La muestra se seleccionó obedeciendo a un muestreo no probabilístico, quedó conformada por 53 profesores. Para el desarrollo de las tareas científicas se combinaron diferentes métodos: del nivel teórico: analítico-sintético, histórico-lógico, inductivo-deductivo y modelación: para el estudio del material recopilado los que aportaron los fundamentos teóricos sobre los medios de enseñanza y las tendencias sobre estrategias de capacitación de profesores en el tema; del empírico: análisis documental, observaciones a clases, encuestas a docentes y expertos para la recogida de la información; y del matemático para el procesamiento a través de la estadística descriptiva con distribución de frecuencias absoluta y en porcientos. Resultados: se identificaron dificultades en el uso de los medios de enseñanza por parte de los docentes, por lo cual se elaboró una estrategia que contiene acciones vinculadas al trabajo metodológico y a la superación profesional, concebidas con un enfoque sistémico, y orientadas a solucionar las dificultades. Conclusiones: los especialistas consultados expresaron que sus acciones son asequibles, factibles, pertinentes y posibles de aplicar desde el puesto de trabajo.
Background: it is needed that medical education teachers make use of the teaching aids in a correct and effective way to enhance the teaching-learning process. Methods: a descriptive study was conducted at the Medical University Branch in Sagua la Grande, from January 2008 to March 2009, with the objective of developing a methodological strategy for the use of teaching aids by the teachers of Health Technology courses. The sample was selected through a non-probability sampling. It consisted of 53 teachers. Different methods were combined for carrying out the scientific tasks. From the theoretical level: analytic-synthetic method, historical and logical method, deductive-inductive method and modeling; for the study of the collected material, which provided the theoretical foundations about the teaching aids and the trends about teacher training strategies in the subject. Empirical methods were used, such as documentary analysis, observation of classes, surveys of teachers and experts for collecting information. Mathematical methods were used for processing by means of descriptive statistics with absolute frequency distribution and percentages. Results: difficulties were found in the use of teaching aids by the teachers; therefore, a strategy that contains actions related to methodological and professional development was developed. These actions are designed with a systemic approach, and aimed at solving the problems. Conclusions: the experts who were consulted expressed that the actions are affordable, achievable and relevant, and it is possible to apply them at the workplace.
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Informática Médica , Relaciones Comunidad-Institución , Metodología como un TemaRESUMEN
Fundamento: se necesita que los docentes de la educación médica utilicen los medios de enseñanza de una manera correcta y eficaz, para potenciar el proceso enseñanza aprendizaje. Métodos: se realizó una investigación descriptiva, en la Filial de Ciencias Médicas de Sagua la Grande, desde enero 2008 a marzo 2009, con el objetivo de elaborar una estrategia metodológica para el uso de los medios de enseñanza, dirigida a los docentes de las carreras de Tecnologías de la Salud. La muestra se seleccionó obedeciendo a un muestreo no probabilístico, quedó conformada por 53 profesores. Para el desarrollo de las tareas científicas se combinaron diferentes métodos: del nivel teórico: analítico-sintético, histórico-lógico, inductivo-deductivo y modelación: para el estudio del material recopilado los que aportaron los fundamentos teóricos sobre los medios de enseñanza y las tendencias sobre estrategias de capacitación de profesores en el tema; del empírico: análisis documental, observaciones a clases, encuestas a docentes y expertos para la recogida de la información; y del matemático para el procesamiento a través de la estadística descriptiva con distribución de frecuencias absoluta y en porcientos.Resultados: se identificaron dificultades en el uso de los medios de enseñanza por parte de los docentes, por lo cual se elaboró una estrategia que contiene acciones vinculadas al trabajo metodológico y a la superación profesional, concebidas con un enfoque sistémico, y orientadas a solucionar las dificultades. Conclusiones: los especialistas consultados expresaron que sus acciones son asequibles, factibles, pertinentes y posibles de aplicar desde el puesto de trabajo(AU)
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Humanos , Materiales de Enseñanza , Estrategias de SaludRESUMEN
Bacterial biofilms are ubiquitous in nature, and their flexibility is derived in part from a complex extracellular matrix that can be made-to-order to cope with environmental demand. Although common developmental stages leading to biofilm formation have been described, an in-depth knowledge of genetic and signaling is required to understand biofilm formation. Bacteria detect changes in population density by quorum sensing and particular environmental conditions, using signals such as cyclic di-GMP or nitric oxide. The significance of understanding these signaling pathways lies in that they control a broad variety of functions such as biofilm formation, and motility, providing benefits to bacteria as regards host colonization, defense against competitors, and adaptation to changing environments. Due to the importance of these features, we here review the signaling network and regulatory connections among quorum sensing, c-di-GMP and nitric oxide involving biofilm formation.
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Biopelículas/crecimiento & desarrollo , GMP Cíclico/análogos & derivados , Óxido Nítrico/fisiología , Percepción de Quorum/fisiología , Transducción de Señal/fisiología , Adhesión Bacteriana/fisiología , Proteínas Bacterianas/fisiología , GMP Cíclico/fisiología , Regulación Bacteriana de la Expresión Génica , Modelos Biológicos , Sistemas de Mensajero Secundario/fisiología , Virulencia/fisiologíaRESUMEN
Endocytosis and transport of bovine liver ß-glucuronidase to lysosomes in human fibroblasts are mediated by two receptors: the well-characterized cation-independent mannose 6-phosphate receptor (IGF-II/Man6PR) and an IGF-II/Man6PR-independent receptor, which recognizes a Ser-Trp*-Ser sequence present on the ligand. The latter receptor was detergent extracted from bovine liver membranes and purified. LC/ESI-MS/MS analysis revealed that this endocytic receptor was annexin VI (AnxA6). Several approaches were used to confirm this finding. First, the binding of bovine ß-glucuronidase to the purified receptor from bovine liver membranes and His-tagged recombinant human AnxA6 protein was confirmed using ligand-blotting assays. Second, western blot analysis using antibodies raised against IGF-II/Man6PR-independent receptor as well as commercial antibodies against AnxA6 confirmed that the receptor and AnxA6 were indeed the same protein. Third, double immunofluorescence experiments in human fibroblasts confirmed a complete colocalization of the bovine ß-glucuronidase and the AnxA6 receptor on the plasma membrane. Lastly, two cell lines were stably transfected with a plasmid containing the cDNA for human AnxA6. In both transfected cell lines, an increase in cell surface AnxA6 and in mannose 6-phosphate-independent endocytosis of bovine ß-glucuronidase was detected. These results indicate that AnxA6 is a novel receptor that mediates the endocytosis of the bovine ß-glucuronidase.
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Anexina A6/fisiología , Endocitosis/fisiología , Glucuronidasa/metabolismo , Receptor IGF Tipo 2/fisiología , Receptores de Superficie Celular/fisiología , Animales , Anexina A6/análisis , Anexina A6/aislamiento & purificación , Anticuerpos/inmunología , Anticuerpos/farmacología , Bovinos , Línea Celular Tumoral , Endocitosis/efectos de los fármacos , Células Epiteliales/fisiología , Fibroblastos/efectos de los fármacos , Fibroblastos/fisiología , Humanos , Células L , Hígado/química , Hígado/enzimología , Manosafosfatos/farmacología , Espectrometría de Masas , Ratones , Unión Proteica/fisiología , Receptores de Superficie Celular/análisis , Receptores de Superficie Celular/aislamiento & purificación , Proteínas Recombinantes/genética , Proteínas Recombinantes/inmunología , Proteínas Recombinantes/metabolismo , Transfección , Vesículas Transportadoras/metabolismoRESUMEN
BACKGROUND: Interferon (IFN)-α receptor 1 (ifnar1) and suppressor of cytokine signaling 1 (socs1) transcription levels were quantified in peripheral blood mononuclear cells (PBMC) of 59 patients infected with hepatitis C virus (HCV) and 17 non-infected individuals. Samples were obtained from patients infected with HCV that were either untreated or treated with IFN-α2 plus ribavirin for 1 year and divided into responders and non-responders based on viral load reduction 6 months after treatment. Ifnar1 and socs1 transcription was quantified by real-time RT-PCR, and the fold difference (2(â»ΔΔCT)) with respect to hprt housekeeping gene was calculated. RESULTS: Ifnar1 transcription increased significantly in HCV-infected patients either untreated (3.26 ± 0.31), responders (3.1 ± 0.23) and non-responders (2.18 ± 0.23) with respect to non-infected individuals (1 ± 0.34; P = 0.005). Ifnar1 transcription increased significantly (P = 0.003) in patients infected with HCV genotypes 1a (4.74 ± 0.25) and 1b (2.81 ± 0.25) but not in 1a1b (1.58 ± 0.21). No association was found of Ifnar1 transcription with disease progress, initial viral load or other clinical factors. With respect to socs1 transcription, values were similar for non-infected individuals (1 ± 0.28) and untreated patients (0.99 ± 0.41) but increased in responders (2.81 ± 0.17) and non-responder patients (1.67 ± 0.41). Difference between responder and non-responder patients was not statistically significant. Socs1 transcription increased in patients infected with HCV genotypes 1a and 1b (2.87 ± 0.45 and 2.22 ± 0.17, respectively) but not in 1a1b (1.28 ± 0.40). Socs1 transcript was absent in three patients infected with HCV genotype 1b. A weak correlation between ifnar1 and socs1 transcription was found, when Spearman's correlation coefficient was calculated. CONCLUSION: Our results suggest that HCV infection may up-regulate ifnar1 transcription. HCV genotypes differ in their capacity to affect ifnar1 and socs1 transcription, as well as in the ability to evade the antiviral response.
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Hepatitis C Crónica/patología , Leucocitos Mononucleares/inmunología , Leucocitos Mononucleares/virología , Receptor de Interferón alfa y beta/biosíntesis , Proteínas Supresoras de la Señalización de Citocinas/biosíntesis , Transcripción Genética , Adulto , Anciano , Antivirales/uso terapéutico , Femenino , Hepatitis C Crónica/tratamiento farmacológico , Hepatitis C Crónica/inmunología , Humanos , Interferón alfa-2 , Interferón-alfa/uso terapéutico , Masculino , Persona de Mediana Edad , Proteínas Recombinantes , Ribavirina/uso terapéutico , Proteína 1 Supresora de la Señalización de CitocinasRESUMEN
In this work, we report the detection of aromatic amino acid aminotransferase (AAT) activity from cell-free crude extracts of nine strains of N(2)-fixing bacteria from three genera. Using tyrosine as substrate, AAT activity ranged in specific activity from 0.084 to 0.404 micromol min(-1)mg(-1). When analyzed under non-denaturating PAGE conditions; and using tryptophan, phenylalanine, tyrosine, and histidine as substrates Pseudomonas stutzeri A15 showed three isoforms with molecular mass of 46, 68 and 86 kDa, respectively; Azospirillum strains displayed two isoforms which molecular mass ranged from 44 to 66 kDa and Gluconacetobacter strains revealed one enzyme, which molecular mass was estimated to be much more higher than those of Azospirillum and P. stutzeri strains. After SDS-PAGE, some AAT activity was lost, indicating a differential stability of proteins. All the strains tested produced IAA, especially with tryptophan as precursor. Azospirillum strains produced the highest concentrations of IAA (16.5-38 microg IAA/mg protein), whereas Gluconacetobacter and P. stutzeri strains produced lower concentrations of IAA ranging from 1 to 2.9 microg/mg protein in culture medium supplemented with tryptophan. The IAA production may enable bacteria promote a growth-promoting effect in plants, in addition to their nitrogen fixing ability.