Giuliano Cinci

Comparative determination of purine compounds in carotid plaque by capillary zone electrophoresis and high-performance liquid chromatography

Allantoin, uric acid (UA), hypoxanthine (Hx) and xanthine (X) were determined on carotid plaque by capillary zone electrophoresis (CZE) and high-performance liquid chromatography (HPLC). Comparison of the results showed that capillary zone electrophoresis may have similar or even superior analytical performance to HPLC, especially for the determination of allantoin in biological samples.

Effects of testosterone on cholesterol levels and fatty acid composition in the rat.

The effects of testosterone treatment on cholesterol levels and its fatty acid components were studied in adult rats. Cholesterol levels increased both in the liver and in the serum of castrated rats. Androgen administration restored the normal values only in the serum. A general decrease in unsaturated and essential fatty acids in cholesterol esters was evident after testosterone administration. In the liver, only the C16:O/C16:1 ratio clearly increased after testosterone administration, which inhibited the delta 9 unsaturation of palmitic acid, but not of stearic acid. In the serum the C16:O/C16:1, C18:O/C18:1, and C18:2/C2O:4 ratios decreased after castration and were restored by testosterone. The results indicate a clear inhibition of delta 9 unsaturation of palmitic and stearic acids, of delta 5 unsaturation and elongation in organs other than the liver. No effect was evident on delta 6 unsaturation. This suggests that fatty acid unsaturations are regulated differently by testosterone in different tissues. For delta 9 unsaturation in the liver, the effect also seems to be substrate-dependent.

Fatty acid composition of phospholipids, triglycerides and cholesterol in serum of castrated and estradiol treated rats.

We have studied the levels of phospholipids, triglycerides, cholesterol esters, and their fatty acid composition in serum for normal, castrated and estradiol treated rats. The sex hormones did not greatly affect the levels of the various lipid fractions which did not undergo great significant variations, under the different treatments. More evident variations occurred in the percent composition of fatty acid and in the content of the various saturated (SAT), unsaturated (UNSAT), essential (EFA) and non essential fatty acids (NEFA). We studied the most important ratios: EFA/NEFA; UNS/SAT; 16:0/16:1; 18:0/18:1, 18:2/18:3; 18:2/20:4. 16:0/16:1; 18:0/18:1 represent the delta9 desaturase, one specific for palmitic, the other for stearic acid. 18:2/18:3 ratio is an index of the delta6 desaturase activity: 18:2/20:4 ratio of delta5 desaturase-elongase. Most changes were evident in triglycerides. We observed a different behaviour of the UNS/SAT and EFA/NEFA ratios in phospholipids and cholesterol esters, which may reflect either an effect of the sex hormones on the exchange of fatty acids between the same lipid fractions, or a redistribution of lipids among different tissues. Great variations were observed of the ratios 16:0/16:1; 18:0/18:1; 18:2/18:3; 18:2/20:4, which are ascribed a different effect of the sex hormones of delta9, delta6, delta5 desaturases.

Perinatal exposure to xenoestrogens affects pain in adult female rats.

Estrogens have a variety of effects in addition to their action on reproductive structures, including permanent effects on the Central Nervous System (CNS). Therefore environmental chemicals with estrogenic activity (xenoestrogens) can potentially affect a number of CNS functions. In the present experiment, female rats receiving ethynylestradiol (EE) or methoxychlor (MXC) via the mothers during pregnancy (pre) or lactation (post) were tested in comparison with females born from mothers treated with OIL. The Object Recognition, Plantar and Formalin tests were carried out to evaluate the effects of these compounds on integrated functions such as memory and pain. Testosterone and estradiol plasma levels were determined by RIA. The results of the Object Recognition and Plantar tests did not differ among groups. However the groups differed in the Formalin test since flexing duration was higher in the EE- and MXC-pre groups than in the EE- and MXC-post and OIL groups. Estradiol plasma levels were higher in EE-pre than in the other groups. These results confirm the possibility that estrogen-like compounds (EE and MXC) can affect complex neural processes like pain when taken during critical stages of CNS development.

EFFECT OF ESTRADIOL ON PHOSPHOLIPID LIPOPROTEIN LEVELS AND FATTY ACID COMPOSITION IN THE RAT

Phospholipid content and fatty acid composition in the different serum lipoproteins showed specific variations after castration and estradiol administration. Only the levels of phospholipids in HDL, the principal lipoprotein carrying phospholipids, increased after castration and were further enhanced by estradiol treatment, especially at low doses. Fatty acid composition showed many variations and an irregular pattern. The EFA/NEFA, EFA/ME and SAT/ME ratios were calculated. EFA/ME increased in VLDL after both doses of estradiol, while EFA/NEFA and EFA/ME of LDL enhanced at the low dose and decreased at the high one in a dose-dependent manner. HDL showed higher EFA/ME and SAT/ME ratios after castration and lower values of all ratios after both doses of estradiol. The correlation with diseases more frequent in men is discussed.

INFLUENCE OF ESTROGEN ON CHOLESTEROL ESTERIFICATION AND FATTY ACID COMPOSITION IN SERUM LIPOPROTEINS OF CASTRATED RATS

Total, free and esterified cholesterol and its fatty acid composition were measured in the serum lipoproteins of castrated rats after estradiol administration. In general, castration and treatment with estradiol led to a decrease in total esterified cholesterol content. However, estradiol induced an effect opposite to that of castration on the fatty acid composition in VLDL. The effects were variable in HDL and insignificant in LDL. Similarly, the ratios of essential fatty acid to non-essential fatty acid (EFA/NEFA) and that to monoenoic acid (EFA/ME) were affected differently in castration and estradiol treatment in VLDL, but not in HDL or LDL. The pattern of lipid metabolism in castrated and estradiol-treated rats thus appears opposite to that described in human pathology.

Purine nucleotide catabolism in rat liver.

The higher specific radioactivity of ALL in comparison to UA, which are observed after administration of labelled precursors, changed when, oxonic acid and allopurinol, inhibitors of UA and ALL formation were administrated. To interpret these results, it is worth while to recall that nucleotide metabolism can be represented as a complex sequence including de novo synthesis of nucleotides and their degradation to UA and ALL. UA is both partially exported to the blood and partially transformed into ALL, which is totally exported to the blood. Under normal conditions, the radioactivity of UA and ALL is similar, in the case of14 C-glycine, while in the other cases (after 14C-formate and other precursors), the formation of ALL is so fast, that it exceedes export from liver to serum, and the radioactivity of the precursors accumulates in ALL. When we treated with the oxonic acid and allopurinol, formation of ALL was reduced, became slower than its export, leading to a higher labelling into UA.

Serum Folate and Vitamin B12 Levels in Children from Mozambique

In order to investigate the behaviour of biochemical parameters in children from Mozambique, we have determined the serum levels of folic acid and vitamin B12, two well known markers of nutritional anemia.

Determination of Methylated Purine Bases in Urine from Healthy Subjects

This fast and high sensitive method, optimised in our laboratory, was used to determine the basal levels of the excretion of atypical purine compounds; it will interesting to compare the normal values with those from subjects affected by disorders of purine metabolism such as gout or rheumatoid arthritis.

Extraction and purification of ecto-5'-nucleotidase from human lymphocytes.

Ecto-5’ -nucleotidase is an extracellular enzyme which is anchored to the plasma membrane of various cells, including human lymphocytes through a glycosylphosphatidylinositol (GPI) linkage. The enzyme dephosphorylates purine and pyrimidine nucleoside monophosphates to the corresponding nucleosides and generates adenosine from extracellular AMP. In addition to its function as an enzyme, the ecto-5’ -nucleotidase mediates costimulatory signals in T cells, lymphocyte adhesion to endhotelium, and has a role in controlling B cell-follicular dendritic cell interactions. Ecto-5’ -nucleotidase is recognized as a maturation marker for both T and B lymphocytes. Abnormally low ecto-5’-nucleotidase activity has been found on lymphocytes of pat ients suffering with a variety of immunodeficiency diseases characterized by a block in lymphocyte maturation 1. In previous studies we found a strong reduction of ecto-5’-nucleotidase activity in lymphocytes from patients affected by B-cell chronic lymphocytic