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M Piacentini

Publications and source records attributed to M Piacentini.

124 records · Page 7Linked to original sources
PubMed1986

Ornithine decarboxylase, transglutaminase, diamine oxidase and total diamines and polyamines in maternal liver and kidney throughout rat pregnancy.

Ornithine decarboxylase (ODC; EC 4.1.1.17), transglutaminase (EC 2.3.2.13), diamine oxidase (DAO; EC 1.4.3.6) and total di- and poly-amines were studied in rat liver and kidney cortex throughout pregnancy. In liver, ODC activity exhibited two major peaks (4.5-5 times the control activities) on days 15 and 17. Also putrescine and spermidine increased biphasically (3-4-fold), but no variation in spermine content was observed. Transglutaminase activity showed slight variations only near the end of gestation. In kidney, ODC activity did not fluctuate significantly during pregnancy, whereas both transglutaminase activity and putrescine content showed three major increases, in very early, middle and late pregnancy. No significant variations in spermidine and spermine were observed. In both organs, DAO activity, very low or undetectable until day 10, dramatically increased (10- and 20-fold in kidney and liver respectively) in the second half of pregnancy, reaching maxima on days 16-17 and 19. The results obtained for transglutaminase, ODC and total di- and poly-amines are interpreted on the basis of hyperplastic and hypertrophic events in the liver and kidney respectively. The behaviour of DAO suggests that the enzyme plays an important role in the control of intracellular diamine concentration.

Amine Oxidase (Copper-Containing)↗
PubMed1985

Presence of di- and polyamines covalently bound to protein in rat liver.

Acid hydrolysis of trichloroacetic acid precipitate from rat tissue (liver, kidney and testis) homogenate released significant amounts of acid-insoluble putrescine, spermidine and spermine. Following incubation of liver homogenate with [1,4-14C]putrescine, 1.4% of total radioactivity and 1.0% of labelled diamine were recovered in the acid-insoluble fraction. Exhaustive digestion of acid-precipitable material with proteinases (Pronase, aminopeptidase M, carboxypeptidase A, B and Y) revealed the presence of di- and polyamines and of N1-(gamma-glutamyl)spermidine, N1-(gamma-glutamyl)spermine and N1,N12-bis(gamma-glutamyl)spermine. These derivatives were identified both by chromatographic analysis and by enzymatic digestion with purified gamma-glutamylamine cyclotransferase. The finding of di- and polyamine gamma-glutamyl derivatives in the proteinase-digested acid-insoluble fraction of homogenate may be considered as a proof of the in vivo transglutaminase-catalyzed binding of polyamines to proteins. This evidence suggests that di- and polyamines might have an important role in mammalian tissues through covalent binding to proteins by either one or both the primary amino groups.

Animals↗
PubMed1983

Mechanism of release of integral proteins from rat liver microsomal membranes.

The release of three integral enzymatic activities (NADH- and NADPH-cytochrome c reductase and 5'-nucleotidase) and total protein from washed rat liver microsomal membranes, upon simple incubation at 37 degrees C in aqueous media, was investigated. Release does not depend on contaminating proteases and is enhanced by alkaline pH. Total protein and enzyme release is consistent with a loss of phospholipids which are not recovered in the soluble phase. Following incubation at pH 9.0 large amounts of free fatty acids were recovered in the soluble phase, accounting for a ratio of 1/1 (w/w) with released protein. This evidence, together with the data available about densities (1.07-1.08 g/ml) and molecular weights (1 700 000-700 000) of the released enzymes, suggests that they are solubilized from microsomal membranes in the form of mixed micelles mostly formed by free fatty acids and integral proteins, probably owing to the activity of endogenous phospholipases on membrane lipids. Release of total protein and enzymatic activities is decreased by Ca2+, whose possible role in the phenomenon is discussed.

5'-Nucleotidase↗
PubMed1980

Urinary polyamine excretion in man. II. Influence of menstrual cycle.

24 hours urinary excretion of putrescine, spermidine and spermine was analysed at various phases of the menstrual cycle in 10 regularly menstruating women aged 20-40 years. After determining the ovulation time, by means of the basal temperature, the menstrual cycle was divided into five stages. The urinary excretion of putrescine and spermidine appears more marked during the follicular phase. During the luteal phase spermine excretion levels may be as much as 50 times higher than those found during the other stages of the cycle. Mean values show a wide fluctuation, which depends upon the individual. Moreover, the mean values of urinary excretion of di- and polyamines of 3 menstrual cycles in a 37 year old subject, showed little variation in this person. These results suggest that a relationship exists between the phases of the menstrual cycle and the variations in urinary levels of di- and polyamines.

Adult↗
PubMedDate not supplied

Macrophages: a crucial reservoir for human immunodeficiency virus in the body.

The replication of Human Immunodeficiency Virus (HIV) in cells of macrophage lineage represents a key pathogenetic event of the neurological damages typically found during the course of this disease. Macrophages are persistently infected cells and thus not susceptible to the cytophatic effect typical of infected activated CD4-lymphocytes. The resistance of macrophages to HIV infection is at least in part mediated by the autocrine production of the nerve growth factor (NGF), a neurokine able to sustain the survival of some cells of bone marrow origin, including monocyte-derived macrophages. This anti-apoptotic effect of NGF in HIV-infected macrophages can be even more relevant at the central nervous system level, where many cells are able to physiologically produce NGF, thus further increasing the survival of macrophages infected by HIV, and enhancing the damages that these cells may induce upon bystander neurons. The proapoptotic effect of soluble factors released by HIV-infected macrophages may heavily affect the survival and functions also of astrocytes, that in turn become unable to sustain neuronal homeostasis. Taken together, this information supports the importance of therapeutic attempts aimed at attacking virus replication in infected macrophages and/or to selectively eliminate these chronically infected and persistently virus-producing cells.

AIDS Dementia Complex↗
PubMedDate not supplied

CD1d expression by hepatocytes is a main restriction element for intrahepatic T-cell recognition.

The liver has specific mechanisms to protect itself from infectious agents and to avoid autoimmunity, indicating an important role of the hepatic tissues in antigen presentation and tolerance induction. Since intrahepatic lymphocytes may contribute to the innate immunity and to the liver pathology, it is of interest to analyze the expression of antigen presenting molecules and of the related T cell recognition in liver, and how these change in relation to different diseases. We analyzed the expression of MHC class I, and of CD1-a, -b, -c, and -d proteins on liver tissues from patients with different hepatic diseases. Moreover, in the same patients we studied the intrahepatic and peripheral NKT cell recognition of alpha-galactosyl ceramide antigen in the context of CD1d. Unlike in other tissues, classical MHC class I molecules were poorly expressed in the hepatic compartment, suggesting that inflamed hepatocytes may trigger weak MHC-restricted T cell responses. Nevertheless, we observed a prevalent expression of HLA class I-like CD1d isoform on the hepatocyte surface, indicating that CD1d is the main restriction element in the liver. In patients with viral hepatitis, the intrahepatic CD1d expression parallels the recruitment of CD56+Valpha24Vbeta11+ NKT cells in the liver which recognize CD1d presenting glycolipids such as alpha-galactosyl ceramide, suggesting that the intrahepatic T cell immunity may focus on glycolipid antigens.

Adult↗
PubMedDate not supplied

Release of rat liver endoplasmic reticulum membrane proteins into the cytosol.

A membrane-free supernatant is prepared from rat liver cell homogenate by centrifugation at 230,000 x g. AMPase, NADH- and NADPH-cytochrome c reductase activities are demonstrated in the supernatant. These enzymes can be released from rough microsomal membranes by incubation in 0.25 M sucrose at 37 degrees C for 30 minutes. This release is time and temperature dependent and decreases in presence of phospholipase inhibitors. These results indicate that transfer of membrane enzymes from membranes to the cytosol may take place also in vivo. The process seems to be due to an enzymatic digestion of membranes and may be a mechanism for membrane turnover in addition to autophagocytosis.

Adenosine Monophosphate↗
PubMedDate not supplied

A gas chromatographic method for the determination of di- and polyamines in human urine.

A gas chromatographic method for the determination of di- and polyamines in human urine has been developed. The di- and polyamines have been extracted from standard solutions or from urine by a butanolic method modified to improve its sensitivity in relation to the low concentration of the amines in human normal urine. The quantitation is controlled by using two internal standards: 1,6-diaminohexane for Putrescine and Cadaverine, l-ephedrine for Spermidine and Spermine. Distilled water was the final solvent injected into the GLC column and the detector response was linear between 5 and 100 ng.

Cadaverine↗
PubMedDate not supplied

Urinary polyamine excretion in man: I. Influence of sex and age.

Urinary di- and polyamines were analysed by gas-liquid chromatography in 63 normal volunteers. Subjects were divided into two age groups for each sex (males: from 18 to 40 years, and 40 to 70; females from 15 to 35 and 35 to 50), in order to establish age and sex dependent variations in the normal excretion of polyamines. Age appears to have some influence only in the excretion of spermine in male subjects. Sex on the contrary, has a considerable influence on urinary polyamines. Mean values of excretion for putrescine and spermine in female subjects are higher than those in males and show a wide variation in standard deviations.

Adolescent↗