Biomedical subjects
Publications and source records attributed to F Petrelli.
The peptide isolated by us from calf pineal gland causes a reduction of RNA synthesis in vitro in L1210 and HL60 tumoral cells. This peptide also causes inhibition of cell proliferation; the cell viability is not modified. The effects are dose-dependent and reversible.
Biotin-deficient rats show a slower growth rate and thymus involution. The amount of the thymic peptides controlling DNA template, based on thymus weight, is higher in deficient than control rats. No significant difference was noticed in the content of active peptides when evaluated for the rat. This observation suggests that involution of the thymus does not involve those cells which produce active peptides. Inhibition of RNA synthesis is the same for peptides extracted from normal and from biotin-deficient rat thymus. The amount of plasma peptides controlling DNA template per milliliter of plasma is higher and inhibition of activity on RNA synthesis is lower in deficient as compared to control rats. These effects are reversible following biotin administration.
Biotin clearance, its distribution in liver and liver fractions after intravenous administration of 5 muCi/100 g body weight (21.55 microgram) of biotin-14COOH in normal and biotin-deficient rats are reported. In the biotin deficient animal there is a more rapid disappearance of the labeled biotin from the blood stream. Biotin-14COOH incorporation in the liver of the deficient rat is more rapid and larger than the incorporation in normal rat liver. Almost all the biotin recovered from liver homogenate is found in the mitochondria and in the pH 5.2 cytosol fraction; whereas in the microsomes only a very small amount is present. The intracellular distribution of biotin is in agreement with its known metabolic roles.
In biotin-deficient rats, a decrease of total proteins, attributable to a decrease of albumin and alpha1-globulin fractions, a decrease of the pre-beta-lipoproteins and an increase of the alpha-lipoproteins, was observed, together with a rise of total amino acids. Such a situation may be related to the influence of biotin on the synthesis of RNA and proteins.
Biotin deficient rat liver histones showed decreased phosphorylation and methylation, and increased acetylation rates as compared to normal rat liver histones: these alterations may be related to the observed lower stability of the interactions between histones and DNA. The modifications of the metabolic process might be the consequence of an alteration of the synthesis of the enzymes involved in histone phosphorylation, acetylation and methylation mechanisms and are presumably related to a biotin effect upon the synthesis of RNA and proteins.
Biotin administration to old rats (28 months) causes in the blood an increase of ATP, glucose, triglycerides, alkaline phosphatase and a decrease of cholesterol and acid phosphatase; in the liver DNA and electrostatic interactions between DNA and histones are increased. Such parameters come within the values shown by adult rats.
In biotin-deficient rats, a decreased intestinal transport of Na+, H2O and L-phenylalanine, and no transport differences of 3-O-methyl-D-glucose were observed. The lower Na+ and L-phenylalanine transport appears to be referable to a decreased energy availability and probably not to the lack of a carrier.
On the basis of an hypothesis according to which suitable nucleophilic agents may convert adenosine diphosphate (ADP) into adenosine monophosphate (AMP) and adenosine, well known inhibitors of ADP-induced platelet aggregation, some N-heterocyclic aldoxime methiodides were tested as inhibitors of ADP-induced rabbit platelet aggregation. Several 1-aryl-2-hydroxyiminomethly-3-methylimidazolium iodides significantly inhibit in vitro and in vivo-in vitro ADP-induced rabbit platelet aggregation.
Several 5-monosubstituted and 5,5-disubstituted 5,6-dihydroimidazo[1,2-c]quinazolines were synthesized in high yields by the condensation of 2-(o-aminophenyl)imidazole with the required aliphatic or aromatic aldehydes or ketones. Some of these compounds caused inhibition of ADP-induced platelet aggregation in vitro at concentration of 10(-5) to 10(-4) M. The structure-activity relationships of these inhibitors are discussed.
A low molecular factor showing high specific activity in the control DNA of transcription in vitro was isolated from aqueous ultrafiltered calf pineal gland extracts. The active factor was purified by means of Gel filtration on Sephadex G-25 and G-10, thin layer chromatography on aluminum sheet cellulose and high performance liquid chromatography using a Supelcosil LC 318 reverse phase column. The purified pineal factor was characterized as a peptide of low molecular weight (of about 1200 Dalton) containing glutamic acid, leucine, glycine, threonine and alanine in their approximate molar ratio, referred to glycine taken as 1: glycine 1, threonine 1, leucine 1, alanine 6, glutamic acid 2. Studies of the aminoacid sequence by N-terminal analysis using the automated Edman degradation procedure, were unsuccessful, suggesting the presence of a blocked NH2 group. The purified peptide appears to be different from peptide factors till now isolated from pineal gland.
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