Emanuela Balbis

Anti malondialdehyde-adduct immunological response as a possible marker of successful aging.

Contrasting results have been obtained by various researchers about oxidative markers of aging. In this study, a healthy over-90-year-old population was examined for various plasma oxidative biomarkers and compared with a healthy population of blood donors (age range 23-66). Plasma malondialdehyde (MDA), evaluated by means of the thiobarbituric acid test, was significantly higher in the over-90-year-old population, confirming the presence of increased lipoperoxidation in old age. The antibody titre against MDA-protein adducts, considered a marker of lipoperoxidative protein damage in vivo, was evaluated in an ELISA test, completely home made and calibrated versus a concentrated pool of human plasma; this antibody titre was significantly higher in the over-90-year-old population. Plasma vitamin E, evaluated in RP-HPLC, was not significantly different between the two groups. Plasma protein-bound carbonyls, a marker of oxidative protein damage, were measured with the 2,4-dinitrophenylhydrazine assay; their level in the over-90-year-old population was lower than in the blood donors. The higher antibody titre against MDA-adducts may result in protection against accumulation of oxidatively damaged proteins by enhancing their removal, and, together with the preserved plasma vitamin E level, it may endow over-90-year-olds with an especially efficient antioxidant profile. The low level of protein carbonyl might reflect the more efficient removal of damaged proteins.

Early effects of portal flow modulation after extended liver resection in rat

INTRODUCTION The incidence of small-for-size-liver-syndrome after liver transplantation and extended liver resection may be reduced by portal flow modulation. However, many aspects of the small-for-size-liver-syndrome pathogenesis are still unclear. In this experimental study we evaluated the early effects of portal flow modulation after 80% hepatic resection in rats. MATERIALS AND METHODS Rats were randomised in: sham operation (G1), conventional hepatic resection (G2), splenectomy and hepatic resection (G3), splenic transposition followed by hepatic resection after three weeks (G4). Six hours after operation, oxygen saturation of hepatic vein blood, glutathione, and standard liver markers were measured from hepatic venous blood. Glutathione measurement and histopatological examination were performed in the remnant liver. RESULTS Total bilirubin and liver glutathione did not show differences between groups. Aspartate aminotransferase and alanine aminotransferase significantly increased in G2-G4 groups. Blood glutathione and oxygen saturation of hepatic vein blood were lower in G2 than in other groups. A gradient of micro-vesicular degeneration was more severe in G2 compared with G3 and G4. Apoptosis, hemorrhagic necrosis, mitochondrial damage and leucocyte adhesion were evident in G2. CONCLUSION The portal flow modulation induced by splenectomy or splenic transposition was effective in limiting early damage after extended liver resection.

Biochemical and Morphologic Effects After Extended Liver Resection in Rats: Preliminary Results

After hepatic resection and transplantation with a partial graft, death and regeneration of the hepatocytes coexist in the liver. However, when the functional liver mass is inadequate to ensure a proper balance between regeneration vs functional and metabolic demands, small-for-size syndrome develops. We assessed the early effects of extended hepatic resection on liver function in a rat model. Six male Sprague-Dawley rats underwent 80% resection of the liver, and 6 rats served as a control group. At 6 hours after resection, blood samples were obtained from the hepatic vein for measurement of reduced glutathione (GSH), oxidized glutathione (GSSG), and hepatic venous oxygen saturation (Shvo(2)), and for standard liver function tests including determination of concentrations of alanine aminotransferase (ALT), aspartate aminotransferase (AST), gamma-glutamyl transpeptidase, and total bilirubin. The remnant lobe was removed for GSH assay and histopathologic analysis. In the resection group, values were significantly higher for ALT (P = .002), AST (P = .002), and Shvo(2) (P = .01), whereas a significant decrease was observed for blood GSH (P = .009) but not liver GSH. Also in the resection group, we observed characteristic hepatocyte vacuolization with a gradient from periportal acinar zone 1 to the centrolobular area, the presence of hemorrhagic necrosis, and several leukocyte adhesions. The Shvo(2) and GSH data suggest early alteration of oxygen metabolism, as demonstrated by the reduction in oxygen uptake and decreased liver GSH secretion, with preservation of hepatic GSH. Mitochondrial dysfunction and oxidative injury seem to have a crucial role in early onset of liver damage.

Human mesangial cells resist glycoxidative stress through an antioxidant response

The generation of advanced glycation end-products (AGE), the interaction with their receptors, the generation of reactive oxygen species, and the modulation of intracellular redox equilibrium are believed to be the main factors causing alterations of mesangial cell physiology leading to diabetic nephropathy. Normal human primary mesangial cells were exposed to glycoxidative stress by culture in high glucose (HG) or treatment with AGE for up to 6 days. In both cases only a moderate generation of reactive oxygen species and production of HNE-protein adducts were induced while protein nitrotyrosination was not affected. Moreover, HG and AGE caused a significant antioxidant response, confirmed by the induction of heme oxygenase 1 and the consumption of vitamin E. Glutathione was decreased only by HG. Mesangial cell proliferation and viability were slightly affected by HG and AGE. Furthermore, both treatments failed to influence TGF-ß1 and MCP-1 secretion and to modulate RAGE and collagen IV expression. We believe that normal human mesangial cells can resist glycoxidative stress by the observed antioxidant response. These results support the concept that mesangial cells are only partly responsible for the onset and progression of diabetic nephropathy and that the role of other cell types, such as podocytes and endothelial cells, should be taken into consideration.