Contribution of inducible and neuronal nitric oxide synthases to mitochondrial damage and melatonin rescue in LPS-treated mice

NOS isoform activation is related to liver failure during sepsis, but the mechanisms driving mitochondrial impairment remain unclear. We induced sepsis by LPS administration to inducible nitric oxide synthase (iNOS-/-) and neuronal nitric oxide synthase (nNOS-/-) mice and their respective wild-type controls to examine the contribution of iNOS to mitochondrial failure in the absence of nNOS. To achieve this goal, the determination of messenger RNA (mRNA) expression and protein content of iNOS in cytosol and mitochondria, the mitochondrial respiratory complex content, and the levels of nitrosative and oxidative stress (by measuring 3-nitrotyrosine residues and carbonyl groups, respectively) were examined in the liver of control and septic mice. We detected strongly elevated iNOS mRNA expression and protein levels in liver cytosol and mitochondria of septic mice, which were related to enhanced oxidative and nitrosative stress, and with fewer changes in respiratory complexes. The absence of the iNOS, but not nNOS, gene absolutely prevented mitochondrial impairment during sepsis. Moreover, the nNOS gene did not modify the expression and the effects of iNOS here shown. Melatonin administration counteracted iNOS activation and mitochondrial damage and enhanced the expression of the respiratory complexes above the control values. These effects were unrelated to the presence or absence of nNOS. iNOS is a main target to prevent liver mitochondrial impairment during sepsis, and melatonin represents an efficient antagonist of these iNOS-dependent effects whereas it may boost mitochondrial respiration to enhance liver survival (AU)

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Reactive oxygen species derived from NAD(P)H oxidase play a role on ethanol-induced hypertension and endothelial dysfunction in rat resistance arteries

Chronic ethanol consumption is a risk factor for cardiovascular diseases. We studied whether NAD(P)H oxidase-derived reactive oxygen species (ROS) play a role in ethanol-induced hypertension, vascular dysfunction, and protein expression in resistance arteries. Male Wistar rats were treated with ethanol (20 % v/v) for 6 weeks. Ethanol treatment increased blood pressure and decreased acetylcholine-induced relaxation in the rat mesenteric arterial bed (MAB). These responses were attenuated by apocynin (30 mg/kg/day; p.o. gavage). Ethanol consumption increased superoxide anion (O2−) generation and decreased nitrate/nitrite (NOx) concentration in the rat MAB and apocynin prevented these responses. Conversely, ethanol did not affect the concentration of hydrogen peroxide (H2O2) and reduced glutathione (GSH) or the activity of superoxide dismutase (SOD) and catalase (CAT) in the rat MAB. Ethanol increased interleukin (IL)-10 levels in the rat MAB but did not affect the levels of tumor necrosis factor (TNF)-α, IL-6, or IL-1β. Ethanol increased the expression of Nox2 and the phosphorylation of SAPK/JNK, but reduced eNOS expression in the rat MAB. Apocynin prevented these responses. However, ethanol treatment did not affect the expression of Nox1, Nox4, p38MAPK, ERK1/2, or SAPK/JNK in the rat MAB. Ethanol increased plasma levels of TBARS, TNF-α, IL-6, IL-1β, and IL-10, whereas it decreased NOx levels. The major finding of our study is that NAD(P)H oxidase-derived ROS play a role on ethanol-induced hypertension and endothelial dysfunction in resistance arteries. Moreover, ethanol consumption affects the expression and phosphorylation of proteins that regulate vascular function and NAD(P)H oxidase-derived ROS play a role in such responses (AU)

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Cyclooxygenase-2 (COX-2): a molecular target in prostate cancer

Epidemiological studies provided the first evidence that COX may be involved in the pathogenesis of cancer. In the process of carcinogenesis and in the route of intracellular signalling during carcinogenesis, COX-2 expression may be a universal phenomenon. In general, COX-2 is up-regulated throughout the tumorigenic process, from early hyperplasia to metastatic disease. COX-2 has been reported to be constitutively overexpressed in a variety of malignancies and is frequently constitutively elevated in prostate carcinoma. COX-2 was consistently overexpressed in premalignant lesions such as prostatic intraepithelial neoplasia, and carcinoma. Cases are described with evolution of proliferative inflammatory atrophy of the prostate and prostate carcinoma. The increase of evidence implicating COX-2 in cancer has stimulated clinical trials to investigate the efficacy of selective COX-2 inhibitors in individuals at risk for human cancer. Regarding prostate carcinoma there is much direct or indirect evidence to support the use of COX-2 inhibitors in this disease. Trials using these drugs in familial adenomatous polyposis (FAP) and other patients with a high risk of colorectal carcinoma are ongoing (AU)

Protein processing in Plasmodium falciparum?

Los genomas de los organismos del género Plasmodium, agente causante de la malaria humana y animal, se caracterizan por un alto contenido en A+T e inserciones de baja complejidad en sus proteínas. La enzima glucosa-6-fosfato deshidrogenasa- 6-fosfogluconolactonasa (G6PD-6PGL) de las especies de Plasmodium posee unas características estructurales y bifuncionales únicas. En el presente trabajo analizamos la expresión de la G6PD-6PGL de P. faciparum a lo largo del ciclo intraeritrocítico mediante análisis inmunológico con anticuerpos frente a sus dominios N- y C- terminal. La modificación del tamaño del patrón de bandas en los diferentes estadios del desarrollo del parásito sugiere un procesamiento intracelular de la proteína que implicaría que la forma nativa bifuncional genera dos fragmentos principales. El silenciamiento in vitro del gen PfG6PD-6PGL, mediante ARN de interferencia, durante el desarrollo a corto plazo del parásito, también reveló la aparente modificación intracelular de la proteína dependiente del estadio de su ciclo vital. El tamaño de los fragmentos fue consistente con la separación de las dos funciones catalíticas de la enzima. Aunque en P. falciparum no se ha identificado la maquinaria proteolítica de este procesamiento específico de PfG6PD- 6PGL, nuestros resultados sugieren la existencia de mecanismos especializados para el procesamiento intracelular de este tipo de proteínas de estructura única y de función esencial, y que han podido aparecer como consecuencia de la particular evolución de su genoma

The genomes from the organisms of the Plasmodium genus, the causative agents of human and animal malaria, are characterized by an extreme high A+T content and an associated abundant low complexity inserts within their proteins. The enzyme glucose-6-phosphate dehydrogenase-6-phosphogluconolactonase (G6PD- 6PGL) found in Plasmodium species has unique structural and bifunctional characteristics. Here, we report the expression analysis of P. faciparum G6PD- 6PGL along the intraerythrocytic cycle by immunological analysis with antibodies raised against its N- and C- terminal domains. The pattern modification of band sizes at the different stages of parasite development suggest intracellular protein processing involving the cleavage of the native bifunctional form to produce two main fragments. In vitro RNA-mediated PfG6PD-6PGL gene silencing, studied along short-term parasite development also revealed the apparent intracellular protein modification dependent on the parasite stage. Fragment sizes were consistent with separating both catalytic functions of the enzyme. The proteolytic machinery underlying this specific PfG6PD-6PGL proccesing is still unknown in P. falciparum but suggests the existence of distinctive mechanisms in the parasite to deal with unique protein structures of essential function resulting from its genome evolution

Litiasis purínicas infrecuentes: déficit de adenina fosforribosiltransferasa y xantinuria hereditaria / Uncommon purinic lithiasis adenine phosphoribosyltransferase (APRT) deficiency and hereditary xanthinuria

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Las enfermedades tropicales en el mundo occidental / Tropical diseases in the western world

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