Search results for "Urea"
showing 10 items of 888 documents
Vitamin A Deficiency Increases Protein Catabolism and Induces Urea Cycle Enzymes in Rats
2010
Chronic vitamin A deficiency induces a substantial delay in the rates of weight and height gain in both humans and experimental animals. This effect has been associated with an impaired nutrient metabolism and loss of body protein. Therefore, we analyzed the effect of vitamin A deficiency on endogenous proteolysis and nitrogen metabolism and its reversibility with all-trans retinoic acid (RA). Male weanling rats, housed in pairs, were pair-fed a vitamin A-deficient (VAD) or control diet until they were 60 d old. A group of deficient rats were further treated with daily intraperitoneal injections of all-trans RA for 10 d. Final body and tissue (i.e. liver and heart) weights were significantl…
Dietary Arginine Slightly and Variably Affects Tissue Polyamine Levels in Male Swiss Albino Mice
2002
Many key metabolic and physiologic functions involve arginine and arginine-derived metabolites. Requirements for arginine, a "conditionally essential" amino acid for most mammalian species, are met in variable proportions by dietary intake and endogenous synthesis, the latter being sufficient to fulfill arginine needs in adult humans and mice under nonpathologic conditions. However, dietary arginine restriction causes orotic aciduria and abnormal function of the urea cycle. Furthermore, the importance of dietary arginine in the maintenance of homeostasis of arginine-derived metabolites in the body has not yet been analyzed in detail. We therefore examined whether the deprivation or suppleme…
Mushroom bodies enhance initial motor activity in Drosophila.
2009
The central body (or central complex, CCX) and the mushroom bodies (MBs) are brain structures in most insect phyla that have been shown to influence aspects of locomotion. The CCX regulates motor coordination and enhances activity while MBs have, thus far, been shown to suppress motor activity levels measured over time intervals ranging from hours to weeks. In this report, we investigate MB involvement in motor behavior during the initial stages (15 minutes) of walking in Buridan's paradigm. We measured aspects of walking in flies that had MB lesions induced by mutations in six different genes and by chemical ablation. All tested flies were later examined histologically to assess MB neuroan…
Paraoxonase-1 deficiency is associated with severe liver steatosis in mice fed a high-fat high-cholesterol diet: a metabolomic approach.
2013
Oxidative stress is a determinant of liver steatosis and the progression to more severe forms of disease. The present study investigated the effect of paraoxonase-1 (PON1) deficiency on histological alterations and hepatic metabolism in mice fed a high-fat high-cholesterol diet. We performed nontargeted metabolomics on liver tissues from 8 male PON1-deficient mice and 8 wild-type animals fed a high-fat, high-cholesterol diet for 22 weeks. We also measured 8-oxo-20-deoxyguanosine, reduced and oxidized glutathione, malondialdehyde, 8-isoprostanes and protein carbonyl concentrations. Results indicated lipid droplets in 14.5% of the hepatocytes of wild-type mice and in 83.3% of the PON1-deficie…
Regulation of argininosuccinate synthetase level by corticosteroid and pancreatic hormones during perinatal period.
1995
The urea cycle takes place in the hepatocyte of ureothelic animals. The conversion of ammonia into urea involves five reactions. The first 2 take place in the matrix of the mitochondria, the last 2 occur in the cytosol. Argininosuccinate synthetase (AS) is the third reaction of the urea cycle. It catalyses the condensation of citrulline and aspartate into arginonosuccinate. We have previously reported that rat AS activity was present in the cytosol and the outer membrane of the mitochondria. We have shown that, at the activity level, the colocation of AS was changing during fetal and neonatal development and was under the control of corticosteroid and pancreatic hormones. However, an unreso…
Evaluation of the therapeutic potential of PPARalpha agonists for X-linked adrenoleukodystrophy.
2003
Adrenoleukodystrophy protein (ABCD1), a peroxisomal membrane protein, is mutated in patients affected by X-linked adrenoleukodystrophy (X-ALD). Adrenoleukodystrophy-related protein (ABCD2) is the closest relative of ABCD1. Pharmacological induction of ABCD2 gene expression has been proposed as a novel therapy strategy for X-ALD. Fibrates induce peroxisome proliferation and Abcd2 expression in rodent liver. Here we evaluate the possibility of using peroxisome proliferator-activated receptor alpha (PPARalpha) agonists for pharmacological induction of ABCD2 expression. In the liver of PPARalpha-deficient mice, both the constitutive and the fenofibrate-inducible Abcd2 gene expression was found …
Liver intracellular L-cysteine concentration is maintained after inhibition of the trans-sulfuration pathway by propargylglycine in rats.
1997
To study the fate ofl-cysteine and amino acid homeostasis in liver after the inhibition of the trans-sulfuration pathway, rats were treated with propargylglycine (PPG). At 4 h after the administration of PPG, liver cystathionase (EC4.4.1.1) activity was undetectable,l-cystathionine levels were significantly higher,l-cysteine was unchanged and GSH concentration was significantly lower than values found in livers from control rats injected intraperitoneally with 0.15 M-NaCl. The hepatic levels of amino acids that are intermediates of the urea cycle,l-ornithine,l-citrulline andl-arginine and blood urea were significantly greater. Urea excretion was also higher in PPG-treated rats when compared…
Responses to histamine and selective H2-receptor agonists in lung parenchymal strips from normal and sensitized guinea-pigs.
1989
Histamine produces concentration-dependent contractions of lung parenchyma strips obtained from normal and sensitized guinea-pigs. The responsiveness of the sensitized lung strips to histamine was significantly increased compared to normal tissues. Clemizole (0.1 microM) was equally effective as an H1-antagonist in normal (dose-ratio 9.12) and sensitized (dose-ratio 9.77) tissues. The concentration-response curves to histamine were displaced to the left by cimetidine (0.1 microM to 0.1 mM) with similar dose-ratios in normal and sensitized tissues. Cimetidine enhanced maximal responses to histamine only in normal lung strips. The effects of submaximal equieffective concentrations of histamin…
Correlation between leukocytosis and thrombosis in Philadelphia-negative chronic myeloproliferative neoplasms
2009
The evidence that leukocytes may contribute to the pathogenesis of thrombosis in Chronic Myeloproliferative Neoplasms is increasing but not definitive. To further enforces whether an increased leukocyte count is associated with thrombosis and whether this effect can be modulated by cytoreductive therapy, we analyzed the clinical course of 187 patients with Polycythemia Vera (PV) and Essential Thrombocythemia (ET) followed at two Italian Institutions over a period of 7 years. The association was measured at diagnosis or before thrombotic events: a multivariable analysis was carried out using data at baseline and time-dependent covariates. We found that white blood cells (WBC) count above 9.5…
Long-term expression of differentiated functions in hepatocytes cultured in three-dimensional collagen matrix.
1998
Hepatocytes entrapped in collagen gel and cultured in serum-free conditions survived longer than cells cultured on plastic (5 days vs. 3 weeks), showed fewer signs of early cell senescence (no increase in c-fos oncoprotein expression), and maintained the expression of differentiated hepatic metabolic functions over a longer period of time. Cells cultured in collagen gels retained their ability to respond to hormones. The insulin-stimulated glycogen synthesis rate remained fairly constant during 18 days in culture (between 5.4 +/- 0.37 and 9 +/- 2.7 nmol glucose/h/microg DNA). Collagen-cultured hepatocytes recovered glycogen stores to levels similar to those found in liver, or in hepatocytes…