Hydrolyzed milk-serum peptides reduce body weight and fat content of dietary obese rats ameliorating their antioxidant status and liver functions.

AIM: Recent studies suggested that weight reduction under energy restriction required protein supplementation. Moreover, a significant decrease in serum cholesterol and triglycerides was observed when milk-serum proteins and, in particular, their hydrolyzed peptides were compared to milk casein. METHODS: Six Sprague-Dawley rats were fed with the standard diet for 8 weeks. Eighteen rats were fed with the obesity- producing diet for 4 weeks. After this period and for the remaining 4 weeks, these rats were divided into 3 groups, the 1st was fed with the obesity-diet, the 2nd and the 3rd were fed with the casein--and with the hydrolyzed milk-serum peptides--restricted diet, respectively. RESULTS: Treatment with the obesity-diet, compared to standard-diet, induced an increase in the body weight and fat content, with a decrease in protein mass and dehydration state. There was also an increase in blood levels of cholesterol, triglycerides and glucose. The lipoperoxides content in the plasma, heart, brain and liver had also increased, while the content of glutathione and ATP and the membrane fluidity in the liver had significantly decreased. The administration of the restricted caloric diet, in particular the one containing the hydrolyzed peptides were capable of an improvement of all these parameters. CONCLUSIONS: The metabolic modifications induced by the hydrolyzed peptides-restricted diet contribute to control better the over-weight thus reducing the risk of the onset of the dismetabolic pathologies correlated to it.

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 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.

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.

Fusion of sulfatide-containing vesicles of phosphatidylcholine.

Positively charged albumin is described as a 'useful tool' to induce both aggregation and fusion of phosphatidylcholine vesicles containing sulfatide. Techniques that include light-scattering, Sepharose chromatography, centrifugation, electron microscopy, trapped volume determination and scanning calorimetry demonstrate that extensive fusion occurs during aggregation when sulfatide concentrations are above 4-5 mol%. The rate of fusion increases with time for 1-2 h, then reaches a plateau. Fusion occurs extensively above the transition temperature of the phospholipid and is strongly inhibited by increasing concentration of vesicle cholesterol. The significance of both membrane fluidity and sulfatide-phospholipid organization in the fusion mechanism are discussed.

Prolactin response to the dopamine antagonists sulpiride and domperidone. Further evidence for pituitary dopamine deficiency in hyperprolactinemic disorders of different etiology.

The PRL response to the dopamine antagonists sulpiride (100 mg i.m.) or domperidone (2 or 8 mg i.v.) was evaluated in healthy controls and in 148 patients with different hyperprolactinemic disorders (50 with idiopathic hyperprolactinemia, 58 with microprolactinoma, 19 with macroprolactinoma, 2 with empty sella, 8 with acromegaly, 7 with organic lesions of the hypothalamus, and 4 with idiopathic hypopituitarism of presumed hypothalamic origin). Mean PRL response to both drugs was significantly lower in all groups of patients than in controls, and significantly higher in subjects with idiopathic hyperprolactinemia than in those with pituitary adenomas or hypothalamic disease. Absent or impaired PRL responses were found in 38% of idiopathic patients, in 91.5% of microprolactinomas and in all of the patients with either macroprolactinoma, acromegaly, or hypothalamic disorders. Since the PRL response to dopamine antagonists depends on the presence of an endogenous dopaminergic tone, it is suggested that these figures reflect the incidence of major dopamine deficiency at pituitary lactotrophs in different hyperprolactinemic states. These data suggest that the pathophysiology of hyperprolactinemia in many patients with idiopathic disease is different from that of microprolactinoma. However, the finding of a normal PRL response to sulpiride in some subjects with radiologically or surgically proven microprolactinoma indicates that this test has no diagnostic value in the individual case.

Preparation of asymmetric, cerebroside sulfate-containing phospholipid vesicles.

A procedure is described which inserts asymmetrically cerebroside sulfate ('sulfatide') into the outer leaflet of bilayered phospholipid vesicles. Cerebroside sulfate is adsorbed onto a cellulose, filter-paper support and, when incubated with phosphatidylcholine vesicles is transferred to and inserted into the outer leaflet of these vesicles. This transfer occurs at, or above the transition temperature of the phospholipid and follows a similar pattern with small or larger ('fused') unilamellar vesicles. The transfer is linear with time for 1-2 h and is maximal after about 6 h, when the sulfatide content reaches about 6 mol% of the total quantity of phospholipid, corresponding to about 10 mol% of the phospholipids present in the outer layer. Initial rates of sulfatide transfer were somewhat increased when the vesicles contained a positively charged lipid (e.g. stearylamine) and decreased when this lipid was negatively charged (e.g. dicetyl phosphate) or hydrophobic (e.g. cholesterol). Divalent ions markedly inhibited sulfatide transfer and monovalent ions did so to a lesser degree. Once incorporated into the outer leaflet of the vesicle, the sulfatide could not be removed by washing with buffer, 1 M NaCl or 1 M urea.