The GGDEF-EAL protein CdgB from Azospirillum baldaniorum Sp245, is a dual function enzyme with potential polar localization.

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.

Utilidad de la interleucina-6 y de la proteína C reactiva ultrasensible como marcadores pronósticos en pacientes ambulatorios con insuficiencia cardíaca y fracción de eyección reducida / Usefulness of Interleukin-6 and High-sensitivity C-reactive Protein as Prognostic Markers in Outpatients with Heart Failure and Reduced Ejection Fraction

RESUMEN Objetivo: Evaluar si la interleucina-6 (IL-6) y la proteína C reactiva ultrasensible (PCRus) asociadas al péptido natriurético tipo B (BNP) son marcadores independientes de eventos en pacientes ambulatorios con insuficiencia cardíaca con fracción de eyección reducida (IC-FEr). Materiales y Métodos: Se incluyeron en forma prospectiva pacientes mayores de 65 años con IC-FEr controlados en forma ambulatoria. Se realizó la medición basal del BNP, la IL-6 y la PCRus. Se excluyeron los pacientes con IC posinfarto de miocardio reciente (<6 meses), con internación reciente (<3 meses) por un cuadro que pudiera aumentar los marcadores inflamatorios. Se consideró el punto final combinado de mortalidad de cualquier causa e internación por insuficiencia cardíaca descompensada (ICD). Resultados: Se incluyeron 130 pacientes de 75 ± 5 años, con FE de 33 ± 11%. Con un seguimiento de 450 ± 210 días, el punto final combinado se observó en el 31,5% (n = 41). En el análisis multivariado, el BNP elevado (>442 pg/ml) y la IL-6 elevada (>7,2 pg/ml) fueron predictores independientes del punto primario (HR 2,60 (IC95%: 1,14-5,9), p = 0,02 y HR 2,49 (IC95%: 1,08-5,7), p = 0,03, respectivamente), no así la PCRus (>6,9 mg/l), con p = 0,2. La IL-6 presentó un área bajo la curva (ABC) de 0,70, el BNP, de 0,73 y la PCRus de 0,63, sin diferencias significativas entre ellas. Conclusiones: El BNP y la IL-6 fueron marcadores independientes del punto final combinado, no así la PCRus. La capacidad de discriminación de la IL-6 y el BNP fue moderada.

ABSTRACT Purpose: The aim of this study was to assess whether interleukin-6 (IL-6) and high-sensitivity C-reactive protein (hsCRP) associated with B-type natriuretic peptide (BNP) are independent markers of adverse events in outpatients with heart failure and reduced ejection fraction (HFrEF). Methods: Patients older than 65 years of age with HFrEF who were followed-up on an outpatient basis were prospectively included. Baseline BNP, IL-6 and hsCRP levels were assessed. Patients with HF after recent myocardial infarction (<6 months), and recent hospitalization (<3 months) due to a condition that could increase inflammatory markers were excluded from the analysis. The composite endpoint was all-cause mortality and hospitalization for decompensated heart failure (DHF). Results: A total of 130 patients aged 75 ± 5 years and with EF of 33 ± 11% were included in the study. The composite endpoint was observed in 31.5% (n=41) of patients during a follow-up period of 450 ± 210 days. In the multivariate analysis, elevated BNP (>442 pg/ml) and elevated IL-6 (>7.2 pg/ml) were independent predictors of the primary endpoint [HR 2.60 (95% CI 1.14-5.9), p=0.02 and HR 2.49 (95% CI 1.08-5.7), p=0.03, respectively], but not hsCRP >6.9 mg/l, p=0.2. IL-6 presented an area under the ROC curve (AUC) of 0.70, BNP 0.73 and hsPCR 0.63, without significant differences between them. Conclusions: BNP and IL-6 were independent markers of the composite endpoint, but not CRP. The discrimination ability of IL-6 and BNP was moderate.

Home-based HIV testing: Using different strategies among transgender women in Argentina.

BACKGROUND: In Argentina, HIV prevalence among transgender women (TGW) has been reported at 34%. The stigma is one of the most important factors limiting their access to healthcare services. The aims of this study were to compare different HIV testing methodologies, to determine the factors associated with HIV diagnosis and to determine the feasibility of a home-based HIV testing service for TGW. METHODS: A multidisciplinary team performed home-based HIV testing interventions in four cities of Argentina. Participants self-identified as TGW, older than 14 years and with a negative or unknown HIV status. Blood samples were screened by two rapid tests (RT), one based on antibodies (Determine™ HIV-1/2) and the other on antigen and antibodies (Determine™ HIV-1/2 Combo), and the subsequent blood processing via 4th generation ELISA (VIDAS HIV DUO). All reactive samples were confirmed with a viral load (VL). We compared the results of both RT with the ELISA. Samples were pooled in groups of 6 and a VL (Abbott Real Time) performed to identify acute HIV infections. Factors associated with HIV infection were evaluated with multivariate logistic regression analysis. RESULTS: A total of 260 TGW were tested, 51 tested positive (HIV prevalence 19.6%). There were no discordant results between both RTs nor between RTs and 4th generation ELISA, therefore the correlation was 100%. The VL identified 2 additional positive samples. The final analytic sample for positive cases consisted of 53 TGW. In the multivariate analysis, factors associated with a positive HIV result were history of other sexually transmitted infections (STIs) and not being previously tested for HIV. TGW tested for the first time were at 4 times greater risk of being HIV positive compared to those that were tested previously. CONCLUSIONS: A multidisciplinary home-based HIV testing service among TGW is feasible and effective to detect cases of HIV infection. The testing algorithm should start with an RT followed by molecular diagnosis. The history of STIs and never having been tested for HIV were the factors associated with HIV-positive results and should determine efforts to reach this population. Home-based testing reaches individuals that were not tested before and who have more risk of acquiring HIV.

Características clínicas y epidemiológicas de pacientes con paracoccidioidomicosis diagnosticados en un hospital de Resistencia, Chaco / Clinical and epidemiological characteristics of patients with paracoccidioidomycosis diagnosed in a hospital of Resistencia, Chaco

Con el objetivo de describir las características clínico-epidemiológicas de la paracoccidioidomicosis, se realizó un estudio descriptivo de los casos diagnosticados por el Servicio de Microbiología Clínica del hospital de adultos Dr. Julio C. Perrando, de la ciudad de Resistencia (Chaco, Argentina). Entre 2011 y 2014 se detectaron 46 casos. En 2013 y 2014 se constató un incremento de la tasa de incidencia de alrededor de 4 veces con respecto a los anos anteriores. La forma crónica fue la predominante, con una media de edad de los pacientes de 53 anos. Del total de ellos, a 39 se les realizaron pruebas serológicas. En 15 de 39 casos, las pruebas serológicas fueron la única herramienta diagnóstica, mientras que en 4 de estos casos con diagnóstico microbiológico, la prueba resultó no reactiva. La inclusión de la paracoccidioidomicosis en el diagnóstico diferencial de pacientes de áreas endémicas que presentan un síndrome infeccioso inespecífico y la aplicación de las herramientas diagnósticas disponibles contribuyen al diagnóstico oportuno, así como a disminuir las secuelas de esta afección y su impacto socioeconómico.

In order to describe the clinical and epidemiological characteristics of paracoccidioidomycosis, a descriptive study of all the cases diagnosed by the Clinical Microbiology Service at Dr. Julio C. Perrando hospital in the city of Resistencia (Chaco Province, Argentina) was conducted. Between 2011 and 2014, 46 cases were detected. In the period 2013-2014, an almost 4-fold increase in the incidence rate was detected. The chronic form of the disease was predominant with an average age of 53 years. Serological tests in 39 out of 46 patients were performed. In 15 of 39 patients, serological tests were the only diagnostic tool while in 4 patients with a microbiological diagnosis serological tests were non-reactive. In patients from endemic areas with non-specific infectious syndrome it is important to include paracoccidioidomycosis in the differential diagnosis and to apply all available diagnostic tools to reach a timely diagnosis and to reduce the long-term sequelae and their socio-economic impact.

[Clinical and epidemiological characteristics of patients with paracoccidioidomycosis diagnosed in a hospital of Resistencia, Chaco]. / Características clínicas y epidemiológicas de pacientes con paracoccidioidomicosis diagnosticados en un hospital de Resistencia, Chaco.

In order to describe the clinical and epidemiological characteristics of paracoccidioidomycosis, a descriptive study of all the cases diagnosed by the Clinical Microbiology Service at Dr. Julio C. Perrando hospital in the city of Resistencia (Chaco Province, Argentina) was conducted. Between 2011 and 2014, 46 cases were detected. In the period 2013-2014, an almost 4-fold increase in the incidence rate was detected. The chronic form of the disease was predominant with an average age of 53 years. Serological tests in 39 out of 46 patients were performed. In 15 of 39 patients, serological tests were the only diagnostic tool while in 4 patients with a microbiological diagnosis serological tests were non-reactive. In patients from endemic areas with non-specific infectious syndrome it is important to include paracoccidioidomycosis in the differential diagnosis and to apply all available diagnostic tools to reach a timely diagnosis and to reduce the long-term sequelae and their socio-economic impact.

Effectiveness of a Hand Hygiene Program at Child Care Centers: A Cluster Randomized Trial.

OBJECTIVES: Respiratory infections (RIs) are an important cause of morbidity and excessive antibiotic prescriptions in children attending day care centers (DCCs). We aimed to assess the effectiveness of an educational and hand hygiene program in DCCs and homes in reducing RI incidence and antibiotic prescriptions in children. METHODS: A cluster, randomized, controlled, and open study of 911 children aged 0 to 3 years attending 24 DCCs in Almería (Spain) with an 8-month follow-up. Two intervention groups of DCC families performed educational and hand hygiene measures, 1 with soap and water (SWG; n = 274), another with hand sanitizer (HSG; n = 339), and the control group (CG; n = 298) followed usual hand-washing procedures. RI episode rates were compared through multilevel Poisson regression models. The percentage of days missed were compared with Poisson exact tests. RESULTS: There were 5211 RI episodes registered. Children in the HSG had less risk of RI episodes (incidence rate ratio [IRR]: 0.77; 95% confidence interval [CI]: 0.68-0.88) and antibiotic prescriptions (IRR: 0.69; 95% CI: 0.57-0.84) compared with the those in the CG. Children in the SWG had a higher risk of RI episodes (IRR: 1.21; 95% CI: 1.06-1.39) and antibiotic prescriptions (IRR: 1.31; 95% CI: 1.08-1.56) than those in the HSG. Pupils missed 5186 DCC days because of RIs, and the percentage of days absent was significantly lower in the HSG compared with the CG (P < .001) and the SWG (P < .001). CONCLUSIONS: Hand hygiene programs that include hand sanitizer and educational measures for DCC staff, children, and parents, reduce absent days, RIs, and antibiotic prescriptions for these infections in children at DCCs.

Prevalencia de bacterias enteropatógenas en niños que asisten a un hospital pediátrico en Resistencia, Chaco, Argentina / Prevalence of enteropathogenic bacteria in children attending a pediatric hospital in Resistencia, Chaco, Argentina

La enfermedad diarreica aguda continúa siendo uno de los problemas de salud pública más serios en los países en desarrollo, en los que constituye una de las causas principales de enfermedad y muerte en los niños menores de 5 años. Su epidemiología es totalmente dependiente de la región geográfica, nivel socio económico, costumbres y hábitos de la población.El objetivo del presente trabajo fue determinar la prevalencia de agentes etiológicos bacterianos causantes de diarrea aguda, en niños atendidos en un Hospital Pediátrico de Resistencia, Chaco, en el año 2013.Se investigó la presencia de Shigella spp., Salmonella spp., Campylobacte rspp., Escherichia coli O157:H7 en muestras de materia fecal de niños con enfermedad diarreica aguda. Sobre 823 muestras de materia fecal analizadas en el período mencionado, 93 resultaron positivas para alguno de los enteropatógenos estudiados (Tasa de recuperación del 11,3%).Las frecuencias de aislamiento de los enteropatógenos fueron: Shigella spp (82,8%), Salmonella spp (9,7%), Campylobacter spp (6,5%), y E. coli O157:H7 (1%).Con respecto a las especies, dentro del género Shigella predominó S. flexneri (60/77) seguida de S. sonnei (13/77) y S. boydii (4/77). Con excepción de E. coli O157, en el presente trabajo no se estudiaron los diferentes tipos patogénicos.Como en el resto del país, S. flexneri continúa siendo el agente etiológico más frecuentemente aislado. Este es el primer informe sobre la presencia de Campylobacter en coprocultivos en la provincia del Chaco.

Acute diarrheal disease remains one of the most serious problems of public health in developing countries, which is one of the leading causes of illness and death in children under 5 years. Its epidemiology is totally dependent on the geographic region, socioeconomic status, customs and habits of the population.The aim of this study was to determine the prevalence of bacterial etiologic agents causing acute diarrhea in children attending a Pediatric Hospital in the city of Resistencia, Chaco, during 2013.In this work Shigella spp, Salmonella sp, Campylobacter spp, Escherichia coli O157:H7 were investigatedAmong 823 stool samples analyzed, 93 were positive for any of the enteropathogens studied (recovery rate 11.3%).The frequency of isolation of enteric pathogens were: Shigella spp (82.8%), Salmonella spp (9.7%), Campylobacter spp (6.5%), and E. coli O157: H7 (1%).Respect to genus Shigella, Shigella flexneri was the prevalent (60/77) followed by S. sonnei (13/77) and S. boydii (4/77). With the exception of E. coli O157 in the present work the other pathogenic types were not studied.As in the rest of the country, S. flexneri remains the most frequently isolated etiologic agent. This is the first report about the presence of Campylobacter in stool cultures in the province of Chaco

Presence of Thrombus and spontaneous Contrast in the left atrium of Patients with atrial Fibrillation anticoagulated with dabigatran and acenocoumarol / Presencia de trombo y contraste espontáneo en la aurícula izquierda en pacientes con fibrilación auricular, anticoagulados con dabigatrán y acenocumarol

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Volumen plaquetario medio como marcador pronóstico en pacientes con síndrome coronario agudo / Mean Platelet Volume as Prognostic Marker in Patients with Acute Coronary Syndrome

El volumen plaquetario medio (VPM) se ha descripto como un predictor de eventos cardiovasculares en pacientes con síndrome coronario agudo. No obstante, la evidencia de su rol como marcador pronóstico en pacientes añosos es escasa. Objetivo: Evaluar si el VPM es un predictor independiente de eventos en el seguimiento en pacientes con síndrome coronario agudo mayores de 65 años. Material y métodos: Estudio prospectivo que incluyó pacientes mayores de 65 años con síndrome coronario agudo con y sin elevación del segmento ST. Se dividieron en dos grupos: VPM alto (≥ 10,9 fL - tercil 3) y VPM bajo (< 10,9 fL - terciles 1 y 2). Se analizaron diferentes variables clínicas y se calcularon los puntajes TIMI y GRACE. Se consideró el punto final combinado de mortalidad global y reinternación cardiovascular (por síndrome coronario agudo, insuficiencia cardíaca y accidente cerebrovascular) en el seguimiento. Resultados: Se incluyeron 250 pacientes con una edad promedio de 74 ± 7 años, el 44% eran mujeres. Presentaron VPM alto 85 pacientes y VPM bajo 165. La mediana de seguimiento fue de 302 días (rango intercuartil 130-558) y el punto final primario se observó en el 17,6% (44 pacientes). En el análisis multivariado por regresión de Cox, el VPM alto fue predictor independiente del punto final primario [HR 7,23 (IC 95% 2,47-11,6); p = 0,001], al igual que el TIMI riesgo alto [3,10 (IC 95% 1,46-6,59); p = 0,03] y el puntaje GRACE [1,02 (IC 95% 1,01-1,07); p = 0,002]. El VPM presentó un área bajo la curva de 0,71 (IC 95% 0,59-0,82); p = 0,001. Conclusiones: En nuestra población, el VPM se comportó como un predictor independiente del punto final combinado, ajustado por otras variables como los puntajes TIMI y GRACE.

Background: Mean platelet volume (MPV) has been described as a predictor of cardiovascular events in patients with acute coronary syndrome. However, there is limited evidence of its role as prognostic marker in elderly patients. Objective: The aim of this study was to evaluate whether MPV is an independent predictor of events during follow-up of patients over 65 years of age with acute coronary syndrome. Methods: This prospective study included patients over 65 years with ST segment elevation or non ST segment elevation acute coronary syndrome. They were divided into two groups: high MPV (≥10.9 fL - 3rd tertile) and low MPV (<10.9 fL - 1st and 2nd tertile). Different clinical variables were analyzed and the TIMI and GRACE scores were calculated. The primary endpoint was the composite of all-cause mortality and cardiovascular readmission (for acute coronary syndrome, heart failure and stroke) over the follow up period. Results: A total of 250 patients were included in the study. Mean age was 74±7 years and 44% were women. Eighty-five patients presented with high and 165 with low MPV. Median follow-up was 302 days (interquartile range 130-558) and the primary endpoint was observed in 17.6% of cases (44 patients). In the multivariate Cox regression analysis, high MPV [HR 7.23 (95% CI 2.47-11.6); p=0.001], and TIMI [HR 3.10 (95% CI 1.46-6.59); p=0.03] and GRACE [HR 1.02 (95% CI 1.01-1.07); p=0.002] high risk scores were independent predictors of the primary endpoint. The area under the curve for MPV was 0.71 (95% CI 0.59-0.82), p=0.001. Conclusions: In our population, MPV emerged as an independent predictor of the composite endpoint, adjusted for other variables as the TIMI and GRACE scores.

[Detection of virulence genes of the enteroaggregative pathotype in Escherichia coli strains isolated from groundwater sources in the province of Chaco, Argentina]. / Detección de genes de virulencia del patotipo enteroagregativo en cepas de Escherichia coli aisladas de fuentes de agua subterránea de la provincia del Chaco, Argentina.

Groundwater is an important source of drinking water for many communities in Northern Argentina; particularly, in the province of Chaco, where about 14% of households use this natural resource. Enteroaggregative Escherichia coli is an emerging pathogen whose global importance in public health has increased in recent years. Despite the significant risk of disease linked to contaminated water exposure, the prevalence of E. coli pathotypes in aquatic environments is still not so well defined. The aim of the present study was to detect the presence of typical enteroaggregative E. coli through the recognition of its virulence factors aap, AA probe and aggR by molecular techniques. A total of 93 water samples from different small communities of Chaco were analyzed. E. coli was identified in 36 (38.7%) of the tested samples. Six strains isolated from different samples harbored the studied genes. Of these 6 isolates, 3 carried the aap gene, 2 the AA probe and the last one the combination of aap/aggR genes. The prevalence of E. coli isolates harboring enteroaggregative virulence genes in groundwater sources was 6.4%. This work represents the first contribution to the study of the presence and distribution of virulence genes of EAEC in groundwater sources in this region of Argentina.

Detección de genes de virulencia del patotipo enteroagregativo en cepas de Escherichia coli aisladas de fuentes de agua subterránea de la provincia del Chaco, Argentina / Detection of virulence genes of the enteroaggregative pathotype in Escherichia coli strains isolated from groundwater sources in the province of Chaco, Argentina

En la provincia del Chaco, el agua subterránea representa una fuente alternativa, y muchas veces única, para el consumo humano; esta es utilizada en el 14 % de los hogares. A pesar de que se reconoce el riesgo de la exposición al agua contaminada, la prevalencia de los diferentes patotipos de Escherichia coli en ambientes acuáticos no ha sido bien caracterizada. E. coli enteroagregativo (ECEA) es un patógeno emergente cuya importancia en la salud pública mundial se incrementó y quedó claramente establecida en los últimos años. El objetivo del presente trabajo fue detectar la presencia de ECEA típico mediante el reconocimiento de los factores de virulencia aap, AA probe y aggR por reacción en cadena de la polimerasa, en fuentes de agua subterráneas de la provincia del Chaco. Se identificó E. coli en 36 (38,7 %) de las 93 muestras estudiadas, provenientes de diferentes localidades. De esos 36 aislamientos, se identificaron 6 (16,7 %) portadores de los genes de ECEA, lo que representa una prevalencia del 6,4 % considerando las 93 fuentes de agua subterránea estudiadas. De esos 6 aislamientos, 3 eran portadores del gen aap, 2 del gen AA probe y uno de la combinación aggR/aap. El presente trabajo representa el primer aporte en el estudio de la presencia y distribución de genes de virulencia de ECEA en fuentes de agua subterránea de la región.

Groundwater is an important source of drinking water for many communities in Northern Argentina; particularly, in the province of Chaco, where about 14 % of households use this natural resource. Enteroaggregative Escherichia coli is an emerging pathogen whose global importance in public health has increased in recent years. Despite the significant risk of disease linked to contaminated water exposure, the prevalence of E. coli pathotypes in aquatic environments is still not so well defined. The aim of the present study was to detect the presence of typical enteroaggregative E. coli through the recognition of its virulence factors aap, AA probe and aggR by molecular techniques. A total of 93 water samples from different small communities of Chaco were analyzed. E. coli was identified in 36 (38.7 %) of the tested samples. Six strains isolated from different samples harbored the studied genes. Of these 6 isolates, 3 carried the aap gene, 2 the AA probe and the last one the combination of aap/aggR genes. The prevalence of E. coli isolates harboring enteroaggregative virulence genes in groundwater sources was 6.4 %. This work represents the first contribution to the study of the presence and distribution of virulence genes of EAEC in groundwater sources in this region of Argentina.

[Networks involving quorum sensing, cyclic-di-GMP and nitric oxide on biofilm production in bacteria]. / Redes de señalización en la producción de biopelículas en bacterias: 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.

Redes de señalización en la producción de biopelículas en bacterias: quorum sensing, di-GMPc y óxido nítrico / Networks involving quorum sensing, cyclic-di-GMP and nitric oxide on biofilm production in bacteria

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

Denitrification-derived nitric oxide modulates biofilm formation in Azospirillum brasilense.

Azospirillum brasilense is a rhizobacterium that provides beneficial effects on plants when they colonize roots. The formation of complex bacterial communities known as biofilms begins with the interaction of planktonic cells with surfaces in response to appropriate signals. Nitric oxide (NO) is a signaling molecule implicated in numerous processes in bacteria, including biofilm formation or dispersion, depending on genera and lifestyle. Azospirillum brasilense Sp245 produces NO by denitrification having a role in root growth promotion. We analyzed the role of endogenously produced NO on biofilm formation in A. brasilense Sp245 and in a periplasmic nitrate reductase mutant (napA::Tn5; Faj164) affected in NO production. Cells were statically grown in media with nitrate or ammonium as nitrogen sources and examined for biofilm formation using crystal violet and by confocal laser microscopy. Both strains formed biofilms, but the mutant produced less than half compared with the wild type in nitrate medium showing impaired nitrite production in this condition. NO measurements in biofilm confirmed lower values in the mutant strain. The addition of a NO donor showed that NO influences biofilm formation in a dose-dependent manner and reverses the mutant phenotype, indicating that Nap positively regulates the formation of biofilm in A. brasilense Sp245.

Distance correction in the electrocardiographic estimation of left ventricular mass.

Assessment of the left ventricular mass (LVM) from electrocardiograms may be improved by the addition of clinical variables into a multivariate equation. As the heart-thorax distance may affect the results, its relationships with electrocardiographic and clinical data have been evaluated in a group of 220 subjects (53 +/- 15 years, 126 female, 175 without demonstrated heart disease) who were assessed for echocardiographic LVM and heart-thorax distance. Sokolow, Cornell, and total QRS voltage indexes were obtained. Multiple regression equations with LVM as the dependent variable were fit, with an ECG index, body mass index (BMI), age, and gender as the independent predictors. Each of the 3 ECG indexes, BMI, age, and sex was shown to be independent predictors of LVM, with the ECG and BMI contributing with most of the explanatory power. When added to the model, the distance from the interventricular septum to the precordium (septal-LVD) was not a predictor of LVM, but when BMI was withdrawn, septal-LVD became an independent predictor of LVM (P < .001). This was not observed when septal-LVD was substituted for any other clinical or ECG variable, thus suggesting that septal-LVD accounts for information contained in BMI but not in the remaining variables. In addition, the distance from the center of LV to the precordium (mid-LVD) achieved significance as an independent LVM predictor, although the coefficient of multiple determination (R) practically did not change. Almost identical results are obtained when LVM is indexed for body surface area. Body mass index supplies virtually all the information contained in the heart-thorax distance.