Estrés oxidativo, nitrosativo y daño cardiovascular en pacientes pediátricos obesos.

La obesidad predispone fuertemente al riesgo cardiovascular y se relaciona con alteraciones en diferentes marcadores de funcionalidad del tejido adiposo, inflamación y daño a biomoléculas. Establecer la presencia de alteraciones precoces en la obesidad infantil es el objetivo de este estudio realizado en pacientes pediátricos (7-14 años) obesos (N=60) y controles (N=42). En él hemos evaluado como marcadores de estrés oxidativo y nitrosativo los niveles de malondialdehído, 8-isoprostanos, productos avanzados de oxidación proteica, mieloperoxidasa y nitrotirosina. Las alteraciones del metabolismo de la arginina se valoraron por la producción de óxido nítrico (NO; nitrito y/o nitrato) y niveles de poliaminas. Otros indicadores fueron la proteína C-reactiva, IL-6 y TNF α como marcadores de inflamación; sICAM-1, sVCAM-1, sE-selectina y VEGF como moléculas de adhesión y funcionalidad endotelial; adipoquinas leptina y resistina, y Vitamina D, PTH, y calcio y fósforo séricos. Según nuestros resultados, la obesidad pediátrica se asocia a estrés oxidativo y nitrosativo, elevación de poliaminas circulantes, incremento de los marcadores de inflamación, adipoquinas y moléculas de adhesión, y descenso de Vitamina D. Las correlaciones entre estas alteraciones son evidentes, y se extienden a los parámetros indicadores del grado de obesidad. La confluencia de otros factores de riesgo metabólico y, particularmente, el nivel de Vitamina D, parecen ser determinantes en la extensión del daño oxidativo y nitrosativo, inflamación y disfunción endotelial valorados. Estos parámetros podrían servir como marcadores tempranos del deterioro vascular asociado a la obesidad pediátrica, y ser utilizados en el seguimiento de estos pacientes y en la prevención de sus complicaciones en la edad adulta

An antihypertensive lactoferrin hydrolysate inhibits angiotensin I-converting enzyme, modifies expression of hypertension-related genes and enhances nitric oxide production in cultured human endothelial cells

This study was aimed to explore whether an antihypertensive lactoferrin hydrolysate (LFH) can inhibit angiotensin I-converting enzyme (ACE) activity and modify the expression of genes related to hypertension in human umbilical vein endothelial cells (HUVEC). LFH induced significant inhibition of ACE activity but it did not affect ACE mRNA levels after 24 h of exposure. LFH treatment significantly affected the expression of genes encoding for proteins involved in nitric oxide pathway such as soluble guanylate cyclase 1 α3 subunit (GUCY1A3; 4.42-fold increase) and nitric oxide synthase trafficking (NOSTRIN; 2.45-fold decrease). Furthermore, expression of the PTGS2/COX-2 gene encoding prostaglandin-endoperoxide synthase 2 a key component of prostaglandin synthesis was significantly increased (2.23-fold). Moreover, NOSTRIN mRNA downregulation was consistent with reduced NOSTRIN protein expression and increased NO production observed in HUVEC. The present study reveals the complexity of the effects exerted by LFH opening avenues for the better understanding of its antihypertensive effects.This work was supported by grant AGL2010-21009 from ‘Ministerio de Educación y Ciencia – FEDER’, Consolider Ingenio 2010, Fun-C-Food, CSD2007-00063 and RETICS INVICTUS RD12/0014/0004 from ‘Instituto de Salud Carlos III’. A. García-Tejedor is recipient of a predoctoral fellowship from ‘Ministerio de Educación y Ciencia’ (BES-2011-044424).Peer reviewe

The Gene Cluster for Agmatine Catabolism of Enterococcus faecalis: Study of Recombinant Putrescine Transcarbamylase and Agmatine Deiminase and a Snapshot of Agmatine Deiminase Catalyzing Its Reaction

Enterococcus faecalis makes ATP from agmatine in three steps catalyzed by agmatine deiminase (AgDI), putrescine transcarbamylase (PTC), and carbamate kinase (CK). An antiporter exchanges putrescine for agmatine. We have cloned the E. faecalis ef0732 and ef0734 genes of the reported gene cluster for agmatine catabolism, overexpressed them in Escherichia coli, purified the products, characterized them functionally as PTC and AgDI, and crystallized and X-ray diffracted them. The 1.65-Å-resolution structure of AgDI forming a covalent adduct with an agmatine-derived amidine reactional intermediate is described. We provide definitive identification of the gene cluster for agmatine catabolism and confirm that ornithine is a genuine but poor PTC substrate, suggesting that PTC (found here to be trimeric) evolved from ornithine transcarbamylase. N-(Phosphonoacetyl)-putrescine was prepared and shown to strongly (K(i) = 10 nM) and selectively inhibit PTC and to improve PTC crystallization. We find that E. faecalis AgDI, which is committed to ATP generation, closely resembles the AgDIs involved in making polyamines, suggesting the recruitment of a polyamine-synthesizing AgDI into the AgDI pathway. The arginine deiminase (ADI) pathway of arginine catabolism probably supplied the genes for PTC and CK but not those for the agmatine/putrescine antiporter, and thus the AgDI and ADI pathways are not related by a single “en bloc” duplication event. The AgDI crystal structure reveals a tetramer with a five-blade propeller subunit fold, proves that AgDI closely resembles ADI despite a lack of sequence identity, and explains substrate affinity, selectivity, and Cys357-mediated-covalent catalysis. A three-tongued agmatine-triggered gating opens or blocks access to the active center