Characteristics and Outcomes of Atrial Fibrillation in Chronic Heart Failure Patients: A Comprehensive Analysis of the Colombian Heart Failure Registry.

Background: Heart failure (HF) and atrial fibrillation (AF) represent conditions that commonly coexist. The impact of AF in HF has yet to be well studied in Latin America. This study aimed to characterize the sociodemographic and clinical features, along with patients' outcomes with AF and HF from the Colombian Heart Failure Registry (RECOLFACA). Methods: Patients with ambulatory HF and AF were included in RECOLFACA, mainly with persistent or permanent AF. A 6-month follow-up was performed. Primary outcome was all-cause mortality. To assess the impact of AF on mortality, we used a logistic regression model. A P value of < 0.05 was considered significant. All statistical tests were two-tailed. Results: Of 2,528 patients with HF in the registry, 2,514 records included information regarding AF diagnosis. Five hundred sixty (22.3%) were in AF (mean age 73 ± 11, 56% men), while 1,954 had no AF (mean age 66 ± 14 years, 58% men). Patients with AF were significantly older and had a different profile of comorbidities and implanted devices compared to non-AF patients. Moreover, AF diagnosis was associated with lower quality of life score (EuroQol-5D), mainly in mobility, personal care, and daily activity. AF was prevalent in patients with preserved ejection fraction (EF), while no significant differences in N-terminal prohormone of brain natriuretic peptide (NT-proBNP) levels were observed. Although higher mortality was observed in the AF group compared to individuals without AF (8.9% vs. 6.1%, respectively; P = 0.016), this association lost statistical significance after adjusting by age in a multivariate regression model (odds ratio (OR): 1.35; 95% confidence interval (CI): 0.95 - 1.92). Conclusions: AF is more prevalent in HF patients with higher EF, lower quality of life and different clinical profiles. Similar HF severity and non-independent association with mortality were observed in our cohort. These results emphasize the need for an improved understanding of the AF and HF coexistence phenomenon.

Prevalence, Clinical Characteristics, and Prognostic Impact of Kidney Disease on Heart Failure Patients: An Observational Study of the Colombian Heart Failure Registry.

INTRODUCTION: Chronic kidney disease (CKD) represents one of the most frequent comorbidities observed in heart failure (HF) patients and has been observed to increase this population's risk of adverse outcomes. Nevertheless, evidence analyzing kidney dysfunction in HF is scarce in Latin American populations. We aimed to analyze the prevalence of kidney dysfunction and assess its association with mortality in patients diagnosed with HF enrolled in the Colombian Heart Failure Registry (RECOLFACA). METHODS: RECOLFACA enrolled adult patients with HF diagnosis from 60 centers in Colombia during the period 2017-2019. The primary outcome was all-cause mortality. A Cox proportional-hazards regression model was used to assess the impact of the different categories of eGFR in mortality risk. A p value of <0.05 was considered significant. All statistical tests were two-tailed. RESULTS: From the total 2,514 evaluated patients, 1,501 (59.7%) patients had moderate kidney dysfunction (eGFR <60 mL/min/1.73 m2), while 221 (8.8%) patients were classified as having a severe kidney dysfunction (eGFR <30 mL/min/1.73 m2). Patients with lower kidney function were most commonly males, had higher median age, and reported a higher prevalence of cardiovascular comorbidities. Moreover, different patterns of medications prescription were observed when comparing CKD versus non-CKD patients. Finally, eGFR <30 mL/min/1.73 m2 was significantly associated with a higher mortality risk compared to eGFR >90 mL/min/1.73 m2 status (HR: 1.87; 95% CI, 1.10-3.18), even after an extensive adjustment by relevant covariates. CONCLUSION: CKD represents a prevalent condition in the setting of HF. Patients with CKD and HF present with multiple sociodemographic, clinical, and laboratory differences compared with those only diagnosed with HF and present a significantly higher risk of mortality. A timely diagnosis and optimal treatment and follow-up of CKD in the setting of HF may improve the prognosis of these patients and prevent adverse outcomes.

Correlación entre el neumoperitoneo y los hallazgos quirúrgicos y morbimortalidad en recién nacidos con enterocolitis necrosante / Correlation between pneumoperitoneum and surgical findings and morbidity and mortality in newborns with necrotising enterocolitis

INTRODUCCIÓN: La intervención quirúrgica en las enterocolitis necrosantes (EN) es precisa cuando existe gangrena intestinal, hecho evidente cuando produce perforación y neumoperitoneo, siendo este la única indicación radiológica aceptada universalmente para la intervención quirúrgica. OBJETIVO: Analizar a los pacientes intervenidos de EN, saber por qué se les intervino, cómo evolucionan y si los pacientes perforados presentan neumoperitoneo. MÉTODO: Estudio retrospectivo de una cohorte de recién nacidos con EN intervenidos durante un periodo de 10 años (2006-2015). Se analizan los hallazgos radiológicos preoperatorios y se correlacionan con los quirúrgicos y con la morbimortalidad, dependiendo de la presencia de neumoperitoneo (N+) o no (N-). Se evaluó la concordancia interobservador con radiólogo pediátrico enmascarado a la clínica mediante el índice de acuerdo kappa. RESULTADOS: Se analizó a 53 pacientes. El 36% se intervino tras la visualización de neumoperitoneo; en el resto, la indicación fue deterioro clínico y metabólico, junto con hallazgos radiológicos asociados. En el 39% del grupo N- se objetivó perforación. No se encontraron diferencias significativas en ambos grupos con respecto a longitud intestinal resecada, días de intubación, día de inicio de nutrición enteral y mortalidad. La comparación entre duración de síntomas y estancia hospitalaria total en ambos grupos (N-/N+) fue significativa (7 vs. 2 días, p = 0,008; 127 vs. 79 días, p = 0,003 respectivamente), siendo más favorable en el grupo N+. Estas diferencias se mantuvieron al ajustar por peso. CONCLUSIONES: La indicación quirúrgica ha de basarse en un conjunto de datos clínicos y radiológicos, ya que el 39% de los pacientes sin neumoperitoneo presentaron perforación. En nuestro estudio la presencia de neumoperitoneo no se correlaciona con peor pronóstico

INTRODUCTION: Surgical intervention in necrotising enterocolitis (NEC) is correct when there is intestinal gangrene. This is evident when gangrene produces perforation and pneumoperitoneum, with this being the only universally accepted radiological indication for the surgical intervention of NEC. OBJECTIVE: To perform an analysis on patients with surgically managed NEC, including determining how the decision to intervene is reached, the outcomes, and if patients with perforation had a pneumoperitoneum. METHODS: Retrospective review of neonates with surgical NEC over a period of 10years (2006-2015). An analysis was made of pre-surgical x-ray findings, which were compared with surgical ones, in addition to the morbidity and mortality, depending on the presence (N+) or absence (N-) of pneumoperitoneum. An evaluation was also made of the interobserver concordance with a paediatric radiologist blinded to the clinical reason using the kappa agreement index. RESULTS: A total of 53 neonates were included in the study. Surgical treatment was indicated after observing pneumoperitoneum in 36%. In the remaining neonates, the surgical decision was made after noting a clinical and metabolic deterioration with classical x-ray findings. Intestinal perforation was observed in 39% of the N- neonates. There were no statistical differences between either group on analysing the excised intestinal length, days of intubation, starting of enteral nutrition, and the mortality rate. Comparisons in terms of duration of symptoms and total hospital stay were statistically significant (7 vs. 2 days, P = .008; 127 vs. 79 days, P = .003, respectively), with both being more favourable in the N+ group. These differences remained when the groups were adjusted by birthweight. CONCLUSIONS: Surgical indication has to be done on an ensemble of clinical and radiological evidence, as 39% of the neonates in the N- groups were perforated. In our study, the presence of a pneumoperitoneum did not correlate with a worse prognosis

[Correlation between pneumoperitoneum and surgical findings and morbidity and mortality in newborns with necrotising enterocolitis]. / Correlación entre el neumoperitoneo y los hallazgos quirúrgicos y morbimortalidad en recién nacidos con enterocolitis necrosante.

INTRODUCTION: Surgical intervention in necrotising enterocolitis (NEC) is correct when there is intestinal gangrene. This is evident when gangrene produces perforation and pneumoperitoneum, with this being the only universally accepted radiological indication for the surgical intervention of NEC. OBJECTIVE: To perform an analysis on patients with surgically managed NEC, including determining how the decision to intervene is reached, the outcomes, and if patients with perforation had a pneumoperitoneum. METHODS: Retrospective review of neonates with surgical NEC over a period of 10years (2006-2015). An analysis was made of pre-surgical x-ray findings, which were compared with surgical ones, in addition to the morbidity and mortality, depending on the presence (N+) or absence (N-) of pneumoperitoneum. An evaluation was also made of the interobserver concordance with a paediatric radiologist blinded to the clinical reason using the kappa agreement index. RESULTS: A total of 53 neonates were included in the study. Surgical treatment was indicated after observing pneumoperitoneum in 36%. In the remaining neonates, the surgical decision was made after noting a clinical and metabolic deterioration with classical x-ray findings. Intestinal perforation was observed in 39% of the N- neonates. There were no statistical differences between either group on analysing the excised intestinal length, days of intubation, starting of enteral nutrition, and the mortality rate. Comparisons in terms of duration of symptoms and total hospital stay were statistically significant (7 vs. 2 days, P=.008; 127 vs. 79 days, P=.003, respectively), with both being more favourable in the N+ group. These differences remained when the groups were adjusted by birthweight. CONCLUSIONS: Surgical indication has to be done on an ensemble of clinical and radiological evidence, as 39% of the neonates in the N- groups were perforated. In our study, the presence of a pneumoperitoneum did not correlate with a worse prognosis.

Deterioro funcional asociado al deterioro cognitivo en el anciano hospitalizado / Functional impairment associated with cognitive impairment in hospitalised elderly

Introducción. Nuestro objetivo fue analizar el efecto del deterioro cognitivo sobre el deterioro funcional en pacientes hospitalizados≥60 años. Métodos. Las medidas a la admisión incluyeron datos demográficos, índice de comorbilidad de Charlson y deterioro cognitivo (de acuerdo al nivel educativo). También se midieron estancia hospitalaria, depresión y delirium desarrollado durante la hospitalización. La variable resultado, el Índice de Barthel (IB) se midió al ingreso, al alta y al mes después. Para realizar análisis de regresión logística multivariante y predecir el deterioro funcional (un IB≤75) desde el ingreso hasta el alta y al mes después. Se excluyeron los pacientes con IB≤75 (n=54) al ingreso o con valor perdido de IB (n=1). Resultados. De 133 pacientes incluidos el 24,8% tenían IB≤75 al alta y el 19,6% tenían IB≤75 al mes después. Comparado con los hombres, las mujeres tenían más del doble de riesgo para deterioro funcional al alta y al mes (p<0,05). Comparados con aquellos sin delirium y sin deterioro cognitivo, aquellos con delirium y deterioro cognitivo tuvieron un riesgo aumentado de deterioro funcional (IB≤75) al alta (OR 5,15; IC del 95%: 1,94-13,67) y al mes (OR 6,26; IC del 95%: 2,30-17,03). En forma similar, aquellos con comorbilidad (≥2) tuvieron un riesgo aumentado de deterioro funcional al alta (OR 2,36 IC del 95% 1,14-4,87) y al mes (OR 2,71 IC del 95% 1,25-5,89). Conclusión. El delirium durante la hospitalización superpuesto en el deterioro cognitivo al momento del ingreso fue un predictor mayor del deterioro funcional (AU)

Introduction. The aim of this study was to analyse the effect of cognitive impairment on functional decline in hospitalised patients aged ≥60 years. Methods. Measurements at admission included demographic data, Charlson's comorbidity index, and cognitive impairment (according to education level). Data were also collected on hospital length of stay, depression, and delirium developed during hospitalisation. The outcome, Barthel Index (BI), was measured at admission, discharge, and 1-month post-discharge. Patients with BI≤75 at admission (n=54) or with a missing BI value were excluded (n=1). Multivariate logistic regression analyses were conducted to explore predictive factors with functional decline (BI≤75) from admission to discharge, and 1-month later. Results. Of the 133 patients included, 24.8% and 19.6% had a BI≤75 at discharge and at 1-month, respectively. Compared with men, women had more than double risk for functional decline at discharge and 1-month (P<.05). Compared with those without delirium and without cognitive impairment, those with delirium and cognitive impairment had an increased risk for functional decline (BI≤75) at discharge (OR 5.15, 95% CI; 1.94-13.67), and at 1-month (OR 6.26, 95% CI; 2.30-17.03). Similarly, those with comorbidity (≥2) had increased functional decline at discharge (OR 2.36, 95% CI; 1.14-4.87), and at 1-month after discharge (OR 2.71, 95% CI; 1.25-5.89). Conclusion. Delirium during hospitalisation, together with cognitive impairment on admission, was a strong predictor of functional decline (AU)

[Functional impairment associated with cognitive impairment in hospitalised elderly]. / Deterioro funcional asociado al deterioro cognitivo en el anciano hospitalizado.

INTRODUCTION: The aim of this study was to analyse the effect of cognitive impairment on functional decline in hospitalised patients aged ≥60 years. METHODS: Measurements at admission included demographic data, Charlson's comorbidity index, and cognitive impairment (according to education level). Data were also collected on hospital length of stay, depression, and delirium developed during hospitalisation. The outcome, Barthel Index (BI), was measured at admission, discharge, and 1-month post-discharge. Patients with BI≤75 at admission (n=54) or with a missing BI value were excluded (n=1). Multivariate logistic regression analyses were conducted to explore predictive factors with functional decline (BI≤75) from admission to discharge, and 1-month later. RESULTS: Of the 133 patients included, 24.8% and 19.6% had a BI≤75 at discharge and at 1-month, respectively. Compared with men, women had more than double risk for functional decline at discharge and 1-month (P<.05). Compared with those without delirium and without cognitive impairment, those with delirium and cognitive impairment had an increased risk for functional decline (BI≤75) at discharge (OR 5.15, 95% CI; 1.94-13.67), and at 1-month (OR 6.26, 95% CI; 2.30-17.03). Similarly, those with comorbidity (≥2) had increased functional decline at discharge (OR 2.36, 95% CI; 1.14-4.87), and at 1-month after discharge (OR 2.71, 95% CI; 1.25-5.89). CONCLUSION: Delirium during hospitalisation, together with cognitive impairment on admission, was a strong predictor of functional decline.

Properties of alternative microbial hosts used in synthetic biology: towards the design of a modular chassis.

The chassis is the cellular host used as a recipient of engineered biological systems in synthetic biology. They are required to propagate the genetic information and to express the genes encoded in it. Despite being an essential element for the appropriate function of genetic circuits, the chassis is rarely considered in their design phase. Consequently, the circuits are transferred to model organisms commonly used in the laboratory, such as Escherichia coli, that may be suboptimal for a required function. In this review, we discuss some of the properties desirable in a versatile chassis and summarize some examples of alternative hosts for synthetic biology amenable for engineering. These properties include a suitable life style, a robust cell wall, good knowledge of its regulatory network as well as of the interplay of the host components with the exogenous circuits, and the possibility of developing whole-cell models and tuneable metabolic fluxes that could allow a better distribution of cellular resources (metabolites, ATP, nucleotides, amino acids, transcriptional and translational machinery). We highlight Pseudomonas putida, widely used in many different biotechnological applications as a prominent organism for synthetic biology due to its metabolic diversity, robustness and ease of manipulation.

Piocele como complicación de peritonitis en un preescolar / Pyocele as a complication peritonitis in an preschooler

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Radiation-free monitoring in the long-term follow-up of pyeloplasty: Are ultrasound new parameters good enough to evaluate a successful procedure?

INTRODUCTION: Long-term evolution of residual hydronephrosis after successful pyeloplasty is not common. In this report, we have studied new ultrasound parameters, and have investigated the frequency of residual hydronephrosis. We highlight alternative radiation-free monitoring of pediatric pyeloplasties with ultrasound alone. PATIENTS AND METHODS: Children who had undergone successful open Anderson-Hynes pyeloplasties in the period 2001-2010 were followed up. Exclusion criteria included non-clearly obstructed renography scans (tracer clearance half-time < 20 min), crossing vessels, failed pyeloplasty, bilateral disease, other renal concomitant anomaly, absence of ultrasound measurements, and loss to follow up (<1 year). Postoperative (postoperative) ultrasound parameters were anteroposterior (AP) diameter, pelvis-cortex (P/C) ratio, a proportion that takes in account these two values, enhancing sensitivity to evaluate minimal evolutive changes), and percentage of improvement (PI) in AP diameter (which reflects in relative means the evolution of each AP diameter, being 0% no change, and 100% absence of hydronephrosis) (Figure). Echographic checks were made at 3 and 6 months postoperatively and then yearly afterwards. SPSS software (v. 17.0 IBM, College Station, TX, USA) was used. RESULTS: Out of 80 pyeloplasties performed in the above-mentioned period, 44 patients (i.e., 44 renal units) fulfilled the inclusion criteria for the main study. The median age at time of operation was 15 months (range 2 months-10.3 years). The median follow-up was 4.5 years (range 1-12 years). The mean preoperative anteroposterior diameter was 26 mm (range 16-54 mm). At the third postoperative check, the mean the PI was 29%, and rose to 53% at 6 months (p=0.027). Posterior controls showed a stable yearly PI during follow-up, without statistically significant variations (40-59% in subsequent years, p>0.5). The P/C ratio had already downgraded significantly at the third postoperative check (4.6 preoperative vs. 1.8 postoperative; p=0.03). A subgroup analysis of failed pyeloplasty (4 renal units) showed all PI < 15% at the third postoperative month (sensitivity 100%, specificity 86%). Complete resolution of hydronephrosis occurred in nine patients (20%). DISCUSSION: The P/C ratio and PI are new feasible ultrasound parameters in pyeloplasty follow-up. Early improvement in the P/C ratio can be expected and might avoid repeated ionizing scans. A PI>15% in subsequent postoperative checks might be enough for safe monitoring with ultrasound alone. Thus, renograms may be solicited only in these cases where ultrasound parameters do not improve in the first 6 postoperative months. Afterwards, ultrasound parameters often remain stable in the long term. Absence of hydronephrosis could only be documented in the long term in one out of every five patients.

Homeopatía, una realidad social y asistencial / Homeopathy, social welfare and reality

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[Vesicovaginal Reflux and Urocolpos]. / Reflujo Vaginal y Urocolpos.

OBJECTIVE: Vesico-vaginal reflux (VVR) is defined as the reflux of urine into the vaginal vault during voiding, occasionally seen in pre- adolescent girls. The typical history consists in post voiding leaks in the daytime, that correspond to the progressive urine discharge from the vagina, after it has been filled up during micturition. We intend to show two cases presenting with significant urocolpos. METHODS: Description of two clinical cases observed in the pediatric urology office. RESULTS: Clinical case 1.- A 10-year-old girl presented with the complaint of diurnal incontinence (in the immediate post-voiding minutes). The early voiding phase in the cystourethrogram (VCUG) demonstrated progressive gross distension of the vagina (urocolpos) due to retrograde filling as the bladder emptied. The girl was managed with behavioural modifications, and was dry afterwards. Clinical case 2.- A 9-year-old girl presented with history of incomplete voiding. In infancy, she had right-sided vesicoureteral reflux (VUR) and was endoscopically treated at the age of 2. VCUG showed VVR, and no VUR. She was then successfully treated with behavioural modifications. Clinical case 3.- A 10-year-old girl complained of diurnal urinary incontinence, described as post voiding leaks. Again, a VCUG showed VVR and a small urocolpos. After re-education of voiding habits, leaks disappeared, but recurred 6 months afterwards, when she acknowledged no adherence to the therapy. DISCUSSION: Between 12 to 15% of girls referred to Urological clinics because of urine incontinence present VVR. In the absence of a clear anatomical obstruction, reflux happens as the urine flow encounters a natural obstacle in the labia majora usually in girls that close their legs as they void. Instructions on proper voiding form a key element in the management of VVR, and if not enough, the behavioural modification consists on a reverse position during voiding.

Reflujo Vaginal y Urocolpos / Vesicovaginal Reflux and Urocolpos

OBJETIVOS: El reflujo vaginal (RV) o micción intravaginal es una causa de incontinencia urinaria diurna, con goteo postmiccional. El llenado retrógrado de la vagina durante la micción obedece a causas anatómicas predisponentes o funcionales. MÉTODOS: Exposición de casos clínicos. RESULTADO: Caso clínico 1.- Niña de 10 años, con infecciones de orina acompañadas de incontinencia postmicional a diario. En CUMS se aprecia, en las placas miccionales, la aparición progresiva de urocolpos, que desaparece parcialmente al finalizar la micción. Se inicia tratamiento con re-educación miccional con resolución de síntomas. Caso clínico 2.- Niña de 9 años, con antecedentes de Reflujo Vesicoureteral (RVU) corregido en la infancia que desde hace un año presenta incontinencia de escasa cuantía, postmiccional, con sensación de vaciado incompleto. Aporta ecografia pre y postmiccional normal, pero en la CUMS se aprecia RV, por lo que se inicia tratamiento específico con mejoría de los síntomas. Caso clínico 3.- Niña de 10 años con sobrepeso que consulta por incontinencia diurna, sin síntomas nocturnos. En CUMS se aprecia RV por lo que se establecen medidas conductuales. A los seis meses, las fugas han recurrido, al incumplir la paciente dichas medidas. Concluisones: Hasta un 12-15% de las niñas prepúberes que consultan por escapes de orina pueden presentar RV. El tratamiento consiste en la re-educación del hábito miccional, insistiendo en micciones frecuentes y programadas con un hábito postural correcto consistente en apertura de piernas e inclinación hacia delante, o bien, a horcajadas sobre el inodoro en posición contraria a la habitual

OBJECTIVE: Vesico-vaginal reflux (VVR) is defined as the reflux of urine into the vaginal vault during voiding, occasionally seen in pre- adolescent girls. The typical history consists in post voiding leaks in the daytime, that correspond to the progressive urine discharge from the vagina, after it has been filled up during micturition. We intend to show two cases presenting with significant urocolpos. METHODS: Description of two clinical cases observed in the pediatric urology office. RESULTS: Clinical case 1.- A 10-year-old girl presented with the complaint of diurnal incontinence (in the immediate post-voiding minutes). The early voiding phase in the cystourethrogram (VCUG) demonstrated progressive gross distension of the vagina (urocolpos) due to retrograde filling as the bladder emptied. The girl was managed with behavioural modifications, and was dry afterwards. Clinical case 2.- A 9-year-old girl presented with history of incomplete voiding. In infancy, she had right-sided vesicoureteral reflux (VUR) and was endoscopically treated at the age of 2. VCUG showed VVR, and no VUR. She was then successfully treated with behavioural modifications. Clinical case 3.- A 10-year-old girl complained of diurnal urinary incontinence, described as post voiding leaks. Again, a VCUG showed VVR and a small urocolpos. After re-education of voiding habits, leaks disappeared, but recurred 6 months afterwards, when she acknowledged no adherence to the therapy. DISCUSSION: Between 12 to 15% of girls referred to Urological clinics because of urine incontinence present VVR. In the absence of a clear anatomical obstruction, reflux happens as the urine flow encounters a natural obstacle in the labia majora usually in girls that close their legs as they void. Instructions on proper voiding form a key element in the management of VVR, and if not enough, the behavioural modification consists on a reverse position during voiding

Patient with disorganization syndrome: surgical procedures, pathology, and potential causes.

BACKGROUND: The human disorganization syndrome (HDS) is an extremely rare malformation syndrome that presents with a severe pattern of defects affecting different structures. METHODS: We describe a newborn girl presenting with HDS. Her clinical features included a large appendage arising from the right buttock as the only alteration, with size and shape of a lower member-like structure, and a pedicle of the extra limb structure. The surgical observations, the pathological results, evolution up to 6 months of age, and their potential causes are described, as well as a review of the literature. RESULTS: The MRI procedure also detected a multicystic mass located at the presacral region of the pelvis and perineum, without any dysraphism or other medullary anomalies. The X-ray showed that the member-like structure had an iliac wing, femur, tibia, fibula, and aberrant metatarsals. The review of the literature shows disparate defects of the published cases with HDS, which include some features pathogenically not related with this syndrome. CONCLUSION: We highlight the need to maintain restricted the clinical diagnosis for HDS to those concordant with a great disorganization of morphogenetic inductions affecting the three germ layers, which occur during the first four weeks of development. This is crucial to: (a) perform a correct diagnosis, which is essential to establish the prognosis and surgery procedures, (b) identify which is/are the cause/s, and (c) the adequate genetic counseling.

Aerobic degradation of aromatic compounds.

Our view on the bacterial responses to the aerobic degradation of aromatic compounds has been enriched considerably by the current omic methodologies and systems biology approaches, revealing the participation of intricate metabolic and regulatory networks. New enzymes, transporters, and specific/global regulatory systems have been recently characterized, and reveal that the widespread biodegradation capabilities extend to unexpected substrates such as lignin. A completely different biochemical strategy based on the formation of aryl-CoA epoxide intermediates has been unraveled for aerobic hybrid pathways, such as those involved in benzoate and phenylacetate degradation. Aromatic degradation pathways are also an important source of metabolic exchange factors and, therefore, they play a previously unrecognized biological role in cell-to-cell communication. Beyond the native bacterial biodegradation capabilities, pathway evolution as well as computational and synthetic biology approaches are emerging as powerful tools to design novel strain-specific pathways for degradation of xenobiotic compounds.

A finely tuned regulatory circuit of the nicotinic acid degradation pathway in Pseudomonas putida.

The biochemistry of nicotinic acid (NA) degradation is known but the transcriptional control of the genes involved is still poorly studied. We report here the transcriptional regulatory circuit of the nic genes responsible for the aerobic degradation of NA in Pseudomonas putida KT2440. The three NA-inducible catabolic operons, i.e. nicAB, encoding the upper pathway that converts NA into 6-hydroxynicotinic acid (6HNA), and the nicCDEFTP and nicXR operons, responsible for channelling 6HNA to the central metabolism, are driven by the Pa, Pc and Px promoters respectively. The nicR regulatory gene encodes a MarR-like protein that represses the activity of the divergent Pc and Px promoters being 6HNA the inducer molecule. A new gene, nicS, that is associated to the nicAB genes in the genomes of different γ- and ß-Proteobacteria, encodes a TetR-like regulator that represses the activity of Pa in the absence of the NA/6HNA inducers. The NA regulatory circuit in P. putida has evolved an additional repression loop based on the NicR-dependent cross regulation of the nicS gene, thus assuring a tight transcriptional control of the catabolic genes that may prevent depletion of this vitamin B3 when needed for the synthesis of essential cofactors.

A preliminary crystallographic study of recombinant NicX, an Fe(2+)-dependent 2,5-dihydroxypyridine dioxygenase from Pseudomonas putida KT2440.

NicX from Pseudomonas putida KT2440 is an Fe(2+)-dependent dioxygenase that is involved in the aerobic degradation of nicotinic acid. The enzyme converts 2,5-dihydroxypyridine to N-formylmaleamic acid when overexpressed in Escherichia coli. Biophysical characterization of NicX by analytical gel-filtration chromatography revealed that it behaves as an oligomeric assembly in solution, with an apparent molecular weight that is consistent with a hexameric species. NicX was crystallized by the hanging-drop vapour-diffusion method at 291 K. Diffraction data were collected to a resolution of 2.0 A at the ESRF. The crystals most probably belong to the orthorhombic space group C222 or C222(1). The estimated Matthews coefficient was 2.4 A(3) Da(-1), corresponding to 50% solvent content, which is consistent with the presence of three protein molecules in the asymmetric unit. Analysis of the crystal data together with chromatographic results supports NicX being a hexameric assembly composed of two cyclic trimers. Currently, crystallization of recombinant selenomethionine-containing NicX is in progress.

Growth phase-dependent expression of the Pseudomonas putida KT2440 transcriptional machinery analysed with a genome-wide DNA microarray.

Bacterial transcriptional networks are built on a hierarchy of regulators, on top of which lie the components of the RNA polymerase (in particular the sigma factors) and the global control elements, which play a pivotal role. We have designed a genome-wide oligonucleotide-based DNA microarray for Pseudomonas putida KT2440. In combination with real-time reverse transcription polymerase chain reaction (RT-PCR), we have used it to analyse the expression pattern of the genes encoding the RNA polymerase subunits (the core enzyme and the 24 sigma factors), and various proteins involved in global regulation (Crc, Lrp, Fur, Anr, Fis, CsrA, IHF, HupA, HupB, HupN, BipA and several MvaT-like proteins), during the shift from exponential growth in rich medium into starvation and stress brought about by the entry into stationary phase. Expression of the genes encoding the RNA polymerase core and the vegetative sigma factor decreased in stationary phase, while that of sigma(S) increased. Data obtained for sigma(N), sigma(H), FliA and for the 19 extracytoplasmic function (ECF)-like sigma factors suggested that their mRNA levels change little upon entry into stationary phase. Expression of Crc, BipA, Fis, HupB, HupN and the MvaT-like protein PP3693 decreased in stationary phase, while that of HupA and the MvaT-like protein PP3765 increased significantly. Expression of IHF was indicative of post-transcriptional control. These results provide the first global study of the expression of the transcriptional machinery through the exponential stationary-phase shift in P. putida.