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Biomedical subjects

G Poli

Publications and source records attributed to G Poli.

At least 289 records · Page 16Linked to original sources
PubMed1981

Effect of aldehydes on polyamine metabolism. II. Methylglyoxal-induced changes in S-adenosylmethionine decarboxylase (SAMD) activity and RNA synthesis and degradation in isolated hepatocytes.

In isolated rat liver cells methylglyoxal (MeG) inhibits S-adenosylmethionine decarboxylase activity and RNA and protein synthesis; MeG also stimulated RNA degradation. The changes induced by MeG in RNA metabolism are partially prevented (in the case of RNA synthesis inhibition) or totally abolished (in the case of RNA degradation stimulation) by exogenous spermidine addition. This suggests the effects of MeG on RNA metabolism are dependent, at least in part, on SAMD inhibition.

Adenosylmethionine Decarboxylase↗
PubMed1981

Effect of aldehydes on polyamine metabolism. III. Inhibition of S-adenosyl methionine decarboxylase (SAMD) by CCl4 and by aldehydes produced during lipid peroxidation.

In isolated rat liver cells in which lipid peroxidation is stimulated by CCl4, a strong inhibition of S-adenosylmethionine decarboxylase (SAMD) activity occurs. Some purified aldehydes, which are produced during lipid peroxidation, are able to inhibit SAMD activity in Yoshida hepatoma cells. The most active aldehyde is hydroxypentenal (HPE). It inhibits by 50% SAMD activity at 0.5 mM concentration in entire hepatoma cells, or in hepatoma cell sap, and at 0.1 mM concentration in partially purified hepatoma cell sap fractions.

Adenosylmethionine Decarboxylase↗
PubMed1981

Effect of aldehydes on polyamine metabolism. I. Method used to determine CO2 produced "in vitro" in enzymatic reactions: its application in evaluation of S-adenosylmethionine decarboxylase (SAMD) activity.

In this paper the Authors describe a new method they have adopted (in studies reported in accompanying papers II and III) for measuring S-adenosylmethionine decarboxylase activity in entire cells and cell fractions. The new method is a general one for recovering and measuring labelled carbon dioxide formed "in vitro" during enzymatic reactions. It presents several advantages when compared to traditional methods.

Adenosylmethionine Decarboxylase↗
PubMed1981

Influence of lipid peroxidation on lipoprotein secretion by isolated hepatocytes.

Isolated rat liver cells have been exposed to 3 different lipid peroxidation-inducing agents, CCl4, FeCl3 and cumene hydroperoxide, and the rates of malonaldehyde production and of lipoprotein secretion have been compared. Results indicate that it is possible to induce a high degree of lipid peroxidation without inducing strong changes in lipoprotein secretion. Only in CCl4-poisoned hepatocytes is lipoprotein secretion strongly impaired. In this experimental condition, the effect of free radical scavengers, or inhibitors of lipid peroxidation, as well as the behavior of both lipid peroxidation and lipoprotein secretion, have been evaluated. Promethazine and propyl gallate prevented malonaldehyde production, but neither agent reduced covalent binding nor improved secretion. Menadione, on the contrary, besides inhibiting malonaldehyde production, decreased covalent binding and protected against the impairment of secretion. These data lead to the conclusion that covalent binding of CCl4 metabolites, rather than lipid peroxidation products, accounts for the derangement of lipoprotein secretion in CCl4-poisoned liver cells.

Animals↗
PubMed1981

The role of lipid peroxidation in CCl4-induced damage to liver microsomal enzymes: comparative studies in vitro using microsomes and isolated liver cells.

The question as to whether CCl4 decreases the activities of glucose-6-phosphatase and cytochrome P-450 in liver endoplasmic reticulum mainly through its action in stimulating lipid peroxidation has been investigated using Promethazine to block lipid peroxidation. The investigation, moreover, has compared the effects of CCl4, with and without Promethazine, on isolated rat hepatocytes with corresponding effects on rat liver microsomal suspensions. Our data give no support for the view that products of lipid peroxidation are the main cause of the decrease in cytochrome P-450 observed in CCl4-intoxication. However, our present results are consistent with lipid peroxidation being a major contributory factor to the decrease in glucose-6-phosphatase activity observed in CCl4-induced liver injury.

Animals↗
PubMed1981

Microplate enzyme-linked immunosorbent assay for bovine leukemia virus antibody.

A microplate enzyme-linked immunosorbent assay method was developed for the measurement of bovine immunoglobulin G antibody specific to the envelope antigen (glycoprotein 60) of bovine leukemia virus. The test was then performed on 440 serum samples from dairy cows belonging to herds in which bovine leukemia was suspected or which were leukemia free, and the results were compared with those obtained with the gel-diffusion technique.

Animals↗
PubMed1980

Studies on lipid peroxidation using isolated rat liver cells: the role of singlet oxygen in the propagation of lipid peroxidation ADP-Fe3+ or CCl4 induced.

The separation of lipid peroxidation reactions in two sequential parts, initiation and propagation, has been proposed. Furthermore, it has been shown that some of the propagation reactions following the peroxidative breakdown of membrane lipids may produce singlet oxygen, a highly excited, energetic species of molecular oxygen. To investigate whether singlet oxygen is involved in the propagation of ADP-Fe3+ or CCl4-induced lipid peroxidation, hepatocytes in single cell suspension were treated with the two mentioned drugs in the presence or in the absence of 1,4-diazabicyclo-[2,2,2]octane (DABCO), a known scavenger of singlet oxygen. Only the stimulation of malonaldehyde production due to ADP-Fe3+ was partially prevented by high concentrations of the scavenger, while the CCl4-induced increase of malonaldehyde was not influenced. The results reported here suggest that ADP-iron complex stimulates lipid peroxidation in a way that is somehow different from that occurring in the case of CCl4 poisoning.

Adenosine Diphosphate↗
PubMed1980

ELISA for toxoplasma antibody detection: a comparison with other serodiagnostic tests.

An ELISA method was developed for the measurement of toxoplasma IgG antibodies in human serum using antigen-coated polystyrene beads as a solid phase and anti human IgG-horse radish peroxidase conjugate as an enzymatic tracer. In order to assess ELISA sensitivity and specificity, a between methods comparison was made using 'conventional' serological tests as reference (dye-test, crossover-linked immunoassay, passive haemagglutination, indirect immunofluorescence). From an analysis of the group classifications obtained some considerations emerged: the ELISA specificity looks comparable with that of the 'reference' tests, as no sample classified as negative by all these tests was ELISA-positive, and vice versa; ELISA appears to correlate better with haemagglutination and immunofluorescence, on the basis of the respective class frequencies; in particular, the number of positives, which is much lower for the dye-test and crossover-linked immunoassay, suggests that a higher sensitivity is reached in the former cases.

Antibodies↗
PubMed1980

Tuberculosis in marine tropical fishes in an aquarium.

Skin, gill and visceral tubercle lesions were detected in marine tropical fish in an aquarium. Ninety-seven fish of 17 different genera were affected. The tubercles consisted of a wall of densely packed epithelioid cells and necrotic center packed with acid-fast bacilli identified as Mycobacterium marinum.

Animals↗
PubMed1979

Effect of methyl glyoxal on enzyme release and on protein synthesis and secretion by isolated hepatocytes.

The experiments reported in this paper were designed to study some aspects of protein metabolism in isolated rat liver cells treated with methyl glyoxal. Concentrations of this drug not inducing cell damage were able to decrease hepatocyte protein synthesis and secretion. The results obtained using liver cells whose protein was prelabelled suggest that the alpha-ketoaldehyde acts not only through an impairment of protein synthesis but also affecting the secretion pathway itself.

Alanine Transaminase↗
PubMed1979

Effects of carbon tetrachloride on isolated rat hepatocytes. Inhibition of protein and lipoprotein secretion.

The effects of carbon tetrachloride on protein and lipoprotein secretion, and on lipid peroxidation, have been investigated in isolated rat hepatocytes. It was found that although the free-radical scavenger promethazine completely suppressed the increased peroxidation produced by carbon tetrachloride, it had no effect on the inhibitory action of carbon tetrachloride on lipoprotein secretion. In consequence, the latter effect of carbon tetrachloride does not appear to be mediated through a peroxidative stage.

Animals↗
PubMed1979

A study of bovid herpesvirus 2 infection in calves inoculated intradermally or intranasally.

Bovid herpesvirus 2 infection was studied in calves exposed to the virus by intradermal inoculation of the skin of the left cheek or by nasal spray. In either case a localised infection developed and virus replication was shown to occur mostly in the tissues of its primary localisation, i.e. the skin of the left cheek or the nasal mucosa. There were neither secondary lesions, except at the site of virus injection, nor any serious systemic involvement on the part of the animals. The virus was also recovered from some areas of the skin (right cheek, perineum and scrotum) that were free of macroscopic lesions; moreover, intranuclear inclusions were found in several tissues of the nervous system (brain, superior cervical, stellate and Gasserian ganglia) which did not show any signs of inflammatory or degenerative changes. These findings suggest that the skin and the nervous system play an important role in the naturally-occurring disease since they could be the sites where the virus is maintained latently in the host.

Administration, Intranasal↗