Elvira Pistolesi

Behaviour of several enzymes of lysosomal origin in human plasma during pregnancy

The following enzymes of lysosomal origin were fluorimetrically determined in maternal plasma from the second to the ninth month of pregnancy at 1-mth intervals: beta-D-N-acetylglucosaminidase (EC 3.2.1.30), beta-D-glucuronidase (EC 3.2.1.31), beta-D-glucosidase (EC 3.2.1.21), beta-D-galactosidase (EC 3.2.1.22), alpha-D-galactosidase (EC 3.2.1.23), alpha-L-fucosidase (EC 3.2.1.51) and alpha-D-mannosidase (EC 3.2.1.24) (pH 4.0). As reference microsomal alpha-D-mannosidase (pH 5.7) was also studied. Thirty-eight healthy women, aged 18-37 yr, who had a normal pregnancy followed by normal parturition, were studied. All enzymes, with the only exception of beta-D-galactosidase, showed a progressive and statistically significant increase of activity throughout pregnancy. At the end of pregnancy, the increase ranged from a maximum of 5.6-fold for beta-D-N-acetylglucosaminidase to a minimum of 0.55-fold for alpha-D-mannosidase, pH 5.7. In the case of beta-D-N-acetylglucosaminidase, the level at the fifth month of pregnancy was significantly higher than that at the third month, and from the sixth to the ninth month each level significantly differed from that of the month immediately preceding.

Electron spin resonance studies on the dynamics of phosphatidylcholine — sulfatide model membranes

The effects of sulfatide on the fluidity and surface dynamics of bilayered and micellar model membranes of egg phosphatidylcholine containing sulfatide were studied by electron spin resonance (ESR). 5-Nitroxystearic acid and 15-nitroxystearic acid were employed as spin-label probes for the region close to the surface and that close to the hydrophobic core of lipid structures. In the vesicular structures, the signals generated by 5-nitroxystearic acid showed that the presence of sulfatide reduced the mobility of the hydrocarbon chains around the probe. The effect increased with increasing glycolipid concentration. The decrease in membrane fluidity was also monitored with the 15-nitroxystearic acid probe, although to a lesser extent. We think that sulfatide causes strong side-to-side head-group interactions on the bilayer surface, causing the lipid chains to assemble in a more rigid fashion, though this effect may be balanced in part by the disordered mechanical coupling of glycolipid acyl chains in the apposite faces of the hydrophobic core of the bilayer. Reduction of this mechanical coupling between apposite lipids when there was transition from a bilayered to a micellar structure resulted in a further increase in the order of the system.

Study of the effect of lactobacillus GG supplementation in combination with and without arginine aspartate on lipoproteins and liver peroxidation in cholesterol-fed rats

The effect of diet integration with lactobacillus GG and arginine aspartate administered singly or together to rats submitted to a cholesterol-enriched diet have been evaluated by measuring both the changes in the levels of cholesterol and tryglycerides and the variations of the most indicative parameters of peroxidation in plasma lipoproteins and livers. The administration of lactobacillus GG alone is able to induce a significant hypocholesterolaemic effect while the arginine aspartate singly or together with the lactobacillus does not seem to promote any significant hypocholesterolaemic effect. The cholesterol levels (expressed as mg × dL -1) are in fact: 45.5 for the control diet; 185.4 for the cholesterol-enriched diet; 131.1 for the cholesterol-enriched diet + lactobacillus; 178.2 for the cholesterol enriched diet + arginine aspartate and 122.4 for the cholestorol-enriched diet + lactobacillus + arginine aspartate. On the contrary, the co-administration of lactobacillus and arginine aspartate gives rise to a very high preventive activity against the cholesterol-induced peroxidation damages both in the plasma lipoproteins and in the liver. Such preventive activity is higher by far than that obtainable when lactobacillus or arginine aspartate are administered singly to the rats.The effect of diet integration with lactobacillus GG and arginine aspartate administered singly or together to rats submitted to a cholesterol-enriched diet have been evaluated by measuring both the changes in the levels of cholesterol and triglycerides and the variations of the most indicative parameters of peroxidation in plasma lipoproteins and livers. The administration of lactobacillus GG alone is able to induce a significant hypocholesterolaemic effect while the arginine aspartate singly or together with the lactobacillus does not seem to promote any significant hypocholesterolaemic effect. The cholesterol levels (expressed as mg x dL-1) are in fact: 45.5 for the control diet; 185.4 for the cholesterol-enriched diet; 131.1 for the cholesterol-enriched diet + lactobacillus; 178.2 for the cholesterol enriched diet + arginine aspartate and 122.4 for the cholesterol-enriched diet + lactobacillus + arginine aspartate. On the contrary, the co-administration of lactobacillus and arginine aspartate gives rise to a very high preventive activity against the cholesterol-induced peroxidation damages both in the plasma lipoproteins and in the liver. Such preventive activity is higher by far than that obtainable when lactobacillus or arginine aspartate are administered singly to the rats.