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Biomedical subjects

P Perocco

Publications and source records attributed to P Perocco.

At least 55 records · Page 3Linked to original sources
PubMed1980

Damage by dichlorvos of human lymphocyte DNA.

The action of dichlorvos (2,2-dichlorovinyldimethyl phosphate) was studied with a short-term in vitro system which utilizes lymphocytes. The parameters studied were the action exerted by the pesticide on scheduled (semiconservative) and unscheduled (reparative) DNA synthesis measured as tritiated thymidine uptake. The results obtained show that dischlovos affects semiconservative DNA synthesis, damages human lymphocyte DNA inducing low reparative synthesis, and interferes with DNA repair processes after damage exerted by ultraviolet rays.

Cells, Cultured↗
PubMed1980

[Increase in DNA repair after treatment of mice with N-methyl-N-nitrosourea].

Inbred Balb/C mice were treated in vivo for three days with ip injections of the carcinogen N-Methyl-N-nitrosourea (25 mg/kg body weight). Reported data show that the spleens from treated animals are strongly reduced, functionally impaired and that they present a higher capacity of repairing their DNA after damage exerted in vitro by the same carcinogen or by ultraviolet rays (900 ergs/mm2).

Animals↗
PubMed1980

Effect of pesticides on scheduled and unscheduled DNA synthesis of rat thymocytes and human lymphocytes.

The action of seventeen pesticides (insecticides, fungicides and herbicides) has been studied with short-term in vitro system using rat thymocytes and/or human lymphocytes. The parameters studied were: a)the action of chemicals tested in scalar doses on DNA synthesis of rat thymocytes; b)damage exerted by pesticides on human lymphocyte DNA measured as unscheduled DNA sythesis; c)the interference of chemicals tested with human lymphocyte repair capability after damage exerted on cells by ultraviolet rays. The results obtained suggest that some of tested pesticides don't induce damages to human lymphocyte DNA, some others elicit low DNA repair if compared to the repair following a standard ultraviolet irradiation and some of them (6/17) exert a marked inhibition of cell repair processes after ultraviolet irradiation. Data are discussed on the basis of a possible role played by these substances as carcinogenic agents in the environment.

Animals↗
PubMed1977

Compared effects of N-hydroxyurethan, urethan and hydroxyurea on DNA synthesis. In vivo and in vitro studies.

The effect of N-hydroxyurethan (HUR) on DNA synthesis has been tested both in vivo on various tissues and in vitro on concanavalin A (ConA)-stimulated rat thymocytes and compared with the action of urethan and hydroxyurea. HUR suppresses scheduled DNA synthesis, except that of non-stimulated spleen cells in vitro. The inhibition is efficient and rapid and takes place immediately if the drug is administered at the peak of the S-phase. UR inhibits DNA synthesis in vitro only at much higher doses and with different time course. It is effective or slightly effective if it is administered at the peak of the S-phase. A conversion of urethan into HUR the latter depressing DNA synthesis could partly explain the differences observed. No toxicity was found after treatment with drugs at the concentration employed. Finally, the relationships between drug doses and cell responses have been particularly observed in vivo.

Animals↗
PubMed1976

Selective effect on T and B cell subpopulations in rat lymphoid organs after urethan treatment.

In vitro phytohemagglutinin (PHA) and concanavalin A (Con A) responsiveness of thymus and bone marrow cells, and E, EA, and EAC rosette-forming cells (E, EA, EAC) of these organs and spleen were studied in Fisher rats at various time intervals following a carcinogenic treatment with urethan (UR). Immediately after treatment, organ cellularities were drastically reduced with a progressive recovery as time passed. 1 day after treatment, the response of thymocytes to PHA showed a fourfold increase while organ cellularity dropped to 1%. This response fell below normal values after 7 days with an overshoot after days 14 and 21. UR-treated bone marrow cells showed a response to PHA below normal values after 1 and 7 days, a twofold increase after 3 days and an overshoot after 14 and 21 days. The responsiveness to Con A of both organs was affected by UR treatment to a much lesser extent, although following a pattern similar to that of PHA. E were never found, whether in normal nor in UR-treated animals. As far as the B-cell compartment is concerned, UR causes a progressive diminution of EAC, while the number of EA remains unaffected. The data are discussed in terms of selective effect on T- and B-cell subpopulations.

Animals↗
PubMedDate not supplied

Purification, characterization and biological activity of tulipin, a novel inhibitor of DNA synthesis of plant origin.

A DNA synthesis-inhibiting protein (for which the term tulipin is proposed) was isolated from the bulbs of Tulipa sp. The yield ranged from 3.4 to 4.1 per cent of total protein content of the crude extract. Mr, isoelectric point, neutral and amino sugar and amino acid composition were determined. Inhibition of DNA synthesis varied in intact cells according to the cellular types studied, with a minimum ID 50% (concentration giving 50% inhibition) of 400 ng/ml in neuroblastoma cells. The effect was reversible. No effect was obtained in cell-lysate. RNA and protein synthesis were unaffected. The acute toxicity, evaluated in Swiss mice, gave an LD of 6.1 mg/kg body wt. Results of electron microscopy are also given. A second protein, called tulipin 2, has been isolated and partially characterized.

Amino Acids↗
PubMedDate not supplied

Inhibition and potentiation of T lymphocyte response to mitogens. Studies using two mitogenic stimuli simultaneously.

Rat thymocytes were stimulated with phytohaemagglutinin (PHA), Concanavalin A (Con A), pokeweed mitogen (PWM) and lipopolysaccharide (LPS) or with mixtures of two of these mitogens, added simultaneously to in vitro cultures. Four-five concentrations of first mitogen were matched with four-five concentrations of second mitogen, in all possible combinations. Synergistic effects were observed with LPS plus PHA and LPS plus PWM and inhibitory effects with PHA plus Con A and LPS plus Con A. The hypothesis is discussed that an inhibitory effects occurs when two mitogens react with identical or very similar receptors on the lymphocyte surface, while a synergistic effect is produced by two mitogens reacting with different receptors.

Animals↗
PubMedDate not supplied

DNA repair after UV and gamma irradiation. I. Rat spleen cells.

An in vitro microculture was set up to standardize DNA enzymatic repair in rat spleen lymphocytes after exposure to ultraviolet or gamma rays by measuring the tritiated thymidine uptake. A relation between irradiation dose and DNA repair is always observable when cell viability and scheduled DNA synthesis are taken into account. This micromethod utilizing rat spleen cells appears to be a suitable system for such a study since it permits a satisfactory evaluation of DNA repair.

Animals↗