Deleterious effects of xanthine oxidase on rat liver endothelial cells after ischemia/reperfusion

AbstractPrevious studies have demonstrated that reactive oxygen species are involved in ischemic injury. The present work was undertaken to determine in vivo the role of xanthine oxidase in the oxygen free radical production during rat liver ischemia and to examine the activity of antioxidant enzymes (superoxide dismutase, catalase and glutathione peroxidase) during the same period. Our results indicate a 4-fold increase in xanthine oxidase activity between 2 and 3 hours of normothermic ischemia, in parallel with a decrease in cell viability. Moderate hypothermia delays both events. Under the same conditions, the activity of oxygen radical scavenging enzymes remains unchanged. Moreover, we have compared in vitro the susceptibility of isolated liver cells to an oxidative stress induced by O2·−, H2O2 and OH. Our results reveal that endothelial cells are much more susceptible to reactive oxygen species than hepatocytes, probably because they lack H2O2-detoxifying enzymes. These findings suggest that xanthine oxidase might play a major role in the ischemic injury mainly at the level of the sinusoidal space where most endothelial cells are located

Biological functions of lysosomal membrane-associated glycoproteins

Lysosomes are the final repository of degradation products from the extracellular and intracellular spaces. The lysosomal membrane forms a unique vacuole participating in both endocytosis and autophagocytosis. It is extremely resistant to degradation by lysosomal hydrolases, maintains an acidic intralysosomal environment, transports amino acids and oligosaccharides produced by lysosomal hydrolases, interacts and fuses with other membrane organelles, such as endosomes and phagosomes, and with the plasma membrane.Biomedical Reviews 1997; 8: 119-125

The liver is a common non-exocrine target in primary Sjögren's syndrome: A retrospective review

BACKGROUND: The autoimmune destruction of exocrine glands that defines primary Sjögren's syndrome (1°SS) often extends to non-exocrine organs including the liver. We aimed to determine the prevalence of liver disease in patients with 1°SS and to evaluate the association of this complication with other non-exocrine features and serologic markers of autoimmunity and systemic inflammation. METHODS: We reviewed 115 charts of patients with 1°SS and further analyzed the 73 cases that fulfilled the European Epidemiology Center Criteria, seeking evidence for clinical and subclinical liver disease. RESULTS: Liver function tests had been determined in 59 of the 73 patients. Of those, 29 patients (49.1%) had abnormal liver function tests including 20.3% with clinically overt hepatic disease. Liver disease was the most common non-exocrine feature in this cohort. Risk factors for abnormal liver function tests were distributed similarly between the patients with and without liver disease. In 60% of patients with abnormal liver function tests no explanation for this complication was found except for 1°SS. Liver involvement was significantly more common in 1°SS patients who also had evidence of lung, kidney and hematological abnormalities. Patients with abnormal liver function tests were also more likely to have an elevated sedimentation rate and a positive anti-ENA during the course of their disease. CONCLUSION: Liver involvement is a common complication in 1°SS. Its presence correlates with systemic disease. We consider that this complication should be routinely sought in patients with 1°SS, especially when a positive anti-ENA or evidence of systemic inflammation is found

Nutritional and environmental effects on ammonia emissions from dairy cattle housing: A meta-analysis

Nitrogen (N) excreted in urine by dairy cows can be potentially transformed to ammonia (NH3) and emitted to the atmosphere. Dairy production contributes to NH3 emission, which can create human respiratory problems and odor issues, reduces manure quality, and is an indirect source of nitrous oxide (N2O). The objective of this study was to (i) investigate environmental factors and measurement method that influence NH3 from dairy housing, and (ii) identify key explanatory variables in the prediction of NH3 emissions from dairy barns using a meta-analytical approach. Data from 25 studies were used for the preliminary analysis and data from 10 studies reporting 87 treatment means were used for the meta-analysis. Season, flooring type, manure handling and housing type and system significantly affected NH3 emission rates as well as the measurement method used to quantify the NH3 emission. Ammonia emissions rates from open-lot and scrape systems were considerably greater and those from deep pit systems lower compared to U.S. Environmental Protection Agency (USEPA) estimates used in national inventory calculations. For nutritional effect analysis, the between-study variability (heterogeneity) of the mean emission was estimated using random-effect models and had a significant effect (P < 0.01). Therefore, random-effect models were extended to mixed-effect models to explain heterogeneity. Available dietary and animal variables were included as fixed effects in the mixed-effect models. The final mixed-effect model included dietary crude protein, milk yield and dry matter intake, explaining 45.5% of the heterogeneity in NH3 emissions. A unit increase in milk yield (kg/d) resulted in 4.9 g cow/d reduction in NH3 emissions, and a unit increase in diet crude protein content (%) and dry matter intake (kg/d) resulted in 10.2 and 16.3 g cow/d increase in NH3 emissions, respectively. Ammonia emissions from dairy barns are driven by several factors including housing system, season and diet. Crude protein content of the diet, dry matter intake and milk production are important animal related factors that significantly affect ammonia emission from dairy facilities

Etude expérimentale de la surcharge des lysosomes

Thèse d'agrégation de l'enseignement supérieur (Faculté de médecine) -- UCL, 196

Effects of wine on cellular and endocellular membranes <em>in vitro</em>

Several observations suggest that wine consumption could have beneficial effects on health by preventing cardiovascular diseases. Apparently, ethanol is not the only component responsible for these effects, phenolic substances: tanins, flavonoids may have an important role. As these compounds are able to affect biological membranes, we investigated the effect of wine in vitro on two model membranes: the lysosomal membrane and the red cell membrane. The integrity of rat liver lysosomal membrane was assessed by measuring the latency of Nacetylglucosaminidase, a lysosomal enzyme, when the organelles are subjected to free radicals of oxygen in the presence of different concentrations of wine. The state of red cell membrane was followed by determining hemolysis caused by phospholipase C. Our results show that low concentrations of red wine prevent the deterioration of the membrane of lysosomes induced by oxygen free radicals generated by the xanthine-xanthine oxidase system and oppose hemolysis induced by treating red cells with Clostridium welchii phospholipase C. White wine is considerably less efficient. As similar effects can be obtained with some phenolic compounds, it is probable that the membrane protective effects of red wine that we describe, originate from its content in these substances