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Biomedical subjects

M Pizzichini

Publications and source records attributed to M Pizzichini.

At least 19 recordsLinked to original sources
PubMed2002

Release of mercury from dental amalgam and its influence on salivary antioxidant activity.

Dental amalgam fillings are known to release significant amounts of mercury (Hg) in saliva which could represent a continuous source of oxidative damage to mouth tissues. The present investigation was aimed at verifying this hypothesis by determining a possible correlation between salivary Hg levels and salivary total antioxidant activity (TAA), which is used as an index of oxidative stress. Samples of saliva from 34 healthy donors were analyzed for Hg content, by vapor atomic absorption spectrometry, and for TAA, by determining the ferric reducing ability ('FRAP' method). A significant correlation between Hg and the number of amalgam restorations or total amalgam surface was evident in both the male and female subjects. A significant negative correlation between TAA and Hg levels or number of amalgam restorations or amalgam surface was evident in females, indicating that small increases in salivary Hg were sufficient to produce a decrease in salivary TAA. On the other hand, no significant correlation was found in the males. The present study provides, for the first time, evidence of a pro-oxidant role of the amalgam Hg chronically released in saliva.

Adolescent↗
PubMed2001

Purine nucleotide catabolism in rat liver: labelling of uric acid and allantoin after treatment with oxonic acid and allopurinol.

In our previous experiments on rat liver we found that 15' after intraperitoneal administration of 14C-formate the specific radioactivity of allantoin was always higher than that of uric acid. The present experiments have been carried out to interpret this unexpected result, which was only observed in liver and we studied: a) the incorporation of 14C-glycine into uric acid and allantoin; b) the effects of two competitive inhibitors of xanthine oxidase and uricase, oxonic acid and allopurinol respectively, on levels of uric acid and allantoin in liver and on their specific radioactivity after administration of labelled precursor. The results suggested: a) that under normal conditions, the formation of allantoin is so fast that it exceedes export from liver to serum, and thus the radioactivity of labelled precursors accumulates in allantoin; b) that when allopurinol or oxonic acid are administered, the rate of export exceeds that of allantoin formation and the incorporation of radioactivity into allantoin is lower; c) that not all the data, however, could be interpreted on this basis, but seems to require the existence of different pools of uric acid, which are transformed separately into allantoin.

Allantoin↗
PubMed1997

Purine nucleotide metabolism: specific aspects in chronic lymphocytic leukemia lymphocytes.

The metabolism of purine nucleotides was studied in human peripheral blood lymphocytes from healthy subjects and patients with B-cell chronic lymphocytic leukemia. Nucleotide content was determined by HPLC. The rate of de novo synthesis of purine nucleotides was measured kinetically by following the incorporation of 14C-formate into the nucleotides of a lymphocyte suspension. The patterns of the main enzymes involved in purine nucleotide metabolism (those of the salvage pathway and catabolism) were estimated by a radiochemical method. Although the data expressed in relation to cells and protein showed some discrepancies, several common differences were evident in both cases. The main differences were an increase in NAD and IMP, a sharp decrease in 5'-nucleotidase activities and in total guanylate content and synthesis, and an increase in the A/G ratio in lymphocytes of patients with respect to controls. The changes in these parameters in CLL indicate an imbalance in purine metabolism and may play a specific role in the biology of the leukemia cell. They are also potential biochemical markers of lymphoid malignancies and may be useful in chemotherapic applications.

5'-Nucleotidase↗
PubMed1997

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.

Animals↗
PubMed1997

Biological role of carbamoyl pyridoxal 5'-phosphate.

A new compound, carbamoyl-pyridoxal 5'-phosphate (C-PLP), was synthetized by condensation of pyridoxal 5'-phosphate (PLP) with KCNO. It may be obtained under certain physiological conditions of pH, temperature and concentration of reagents. Formation and degradation of C-PLP are readily reversible chemical reactions, not involving enzymes, at least in rat tissues. However, different considerations suggest that synthesis and breakdown of C-PLP play a biological role in the cell, providing 'protective synthesis' and a 'variable reservoir' of PLP and KCNO, which can be trapped by other proteins, apoenzymes and metabolites, to regulate many cell metabolic functions.

Animals↗
PubMed1997

Effect of estradiol on serum triglyceride lipoprotein levels and fatty acid composition in castrated rats.

Triglyceride content and fatty acid composition of rat serum lipoproteins showed specific variations after castration and estradiol treatment. Triglyceride levels decreased in VLDL after castration and in LDL and HDL after low doses of estradiol. High doses of estradiol enhanced triglyceride levels in VLDL and decreased them in LDL. Fatty acid composition showed a complex pattern: after castration, monoenoic acids decreased and essential fatty acids increased in all lipoprotein classes, enhancing the EFA/NEFA and EFA/ME ratios. Both doses of estrogen lowered these ratios in VLDL and LDL, but decreased them in HDL with high doses and enhanced them in HDL with low doses.

Animals↗
PubMed1996

Effect of testosterone on purine metabolism and morphometric parameters in the rat liver.

The effect of testosterone on the morphology and biochemistry of adult castrated rat liver is described. Castration decreases mean weight and volume of hepatocytes, volume and surface area of sinusoidal lumen, and apparently increases cell number per g of tissue. These variations indicate cell distress. Testosterone administration restored sinusoidal volume and surface area, indicating a true hyperplastic response and improved trophic conditions. Acid soluble nucleotides, RNA and DNA content were lower after castration, being partially restored after testosterone treatment. This restoration, however, was only statistically significant for total guanylate. We concluded that testosterone deficiency and administration exerts a specific effect on the liver in terms of morphological and biochemical changes. Purine nucleotide metabolism is probably the first target of hormonal action, since its changes are the most significant and useful to explain all the other observations.

Animals↗
PubMed1996

Labelling of uric acid and allantoin in different purine organs and urine of the rat.

We studied the incorporation of 14C-formate into uric acid and allantoin in different organs (liver, lung, kidney, spleen), isolated hepatocytes, perfused liver and urine of the rat. Allantoin had a higher specific radioactivity than uric acid after 14C-formate load in the liver in vivo. This was found to be a strictly hepatic phenomenon and not due to the influence of other tissues.

Allantoin↗
PubMed1996

Purine ribonucleotide content in infected HIV-RT+ and HIV-RT- lymphoblastoid cell lines.

We have studied the purine nucleotide metabolism in the following cell lines: a), H9 (continuous human T-cell line) and H9/HTLV-III (H9 cell line, infected with RT+ HIV-I virus); b), A3.01 (human lymphoblastoid cell line CD4+) and 8E51 (line A3.01 permanently transfected with RT-HIV-I virus). Purine metabolism was studied by evaluating the content of the most important ribonucleotides (AMP-GMP-IMP-NAD-ADP-GDP-ATP-GTP) and their ratios. We determined several differences between the cell lines before and after viral infection. All nucleotides except triphosphates were reduced in H9/HTLV-III with respect to H9 cells; in 8E51, however, triphosphates were markedly reduced, while monophosphates increased with respect to A3.01 uninfected cells. Also the ratios exhibited different behaviors, for example the total adenine nucleotides total guanine nucleotides ratio (sigma A/sigma G) was enhanced in H9/HTLV-III cells with respect to H9 and unaltered in 8E51 with respect to A3.01 cells. We may conclude that the HIV-I virus strongly influences the purine nucleotide metabolism of the host cells and that the changes are different when induced either by RT+ or RT- virus.

Analysis of Variance↗
PubMed1996

Purine metabolism in HIV-1 virus-infected T lymphocyte population.

Purine nucleotide metabolism has been studied in T-lymphocyte population in healthy subjects and in AIDS bearing patients. Nucleotide content was determined by HPLC. The overall rate of purine nucleotide synthesis was measured following the incorporation of 14C-formate into the nucleotides of a T cell suspension. The authors discuss the results, which indicate interesting variations in nucleotide content and a lower nucleotide synthesis, determined by kinetic studies.

Acquired Immunodeficiency Syndrome↗