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B Tadolini

Publications and source records attributed to B Tadolini.

10 recordsLinked to original sources
PubMed1992

The influence of phospholipid polar head on the lipid hydroperoxide dependent initiation of lipid peroxidation.

In a buffer (Mes) and at a pH (6.5) where Fe2+ is very stable, we have studied the peroxidation of liposomes catalyzed by FeCl2. The liposomes studied, prepared by sonolysis, contained either phosphatidylcholine or 1:1 molar ratio of phosphatidylcholine and phosphatidic acid. The presence of the negatively charged phospholipid causes: 1) rapid Fe2+ oxidation and oxygen consumption; 2) increased generation of lipid hydroperoxides; 3) decreased generation of thiobarbituric acid-reactive materials; 4) very low inhibition of Fe2+ oxidation and lipid hydroperoxide generation by BHT; 5) inhibition of the termination phase of lipid peroxidation at high FeCl2 concentrations. A hypothesis is proposed to explain the results obtained.

Ferrous Compounds↗
PubMed1992

Phospholipid polar heads affect the generation of oxygen active species by Fe2+ autoxidation.

The possibility that phospholipid polar heads may influence Fe2+ reaction with molecular oxygen and, thus, the generation of oxygen active species was investigated. Dipalmitoyl phosphatidylcholine (DPPC) and DPPC/dipalmitoyl phosphatidic acid (DPPA) were utilized as model liposomes. Fe2+ oxidation, oxygen consumption, nitro blue tetrazolium reduction and 2-deoxyribose degradation were the parameters evaluated. Comparison of the results obtained clearly shows that the two types of polar heads differently affect iron chemistry. DPPC liposomes are ineffective. By contrast, Fe2+ oxidation by oxygen occurs in the presence of DPPC/DPPA liposomes. During this reaction, species able to reduce nitro blue tetrazolium and to degrade 2-deoxyribose are generated. The results obtained indicate that the polar heads of phospholipids, by influencing Fe2+ autoxidation, generate dangerous oxygen species which may exert an active role in the oxidation of the associated hydrophobic components of the phospholipids.

1,2-Dipalmitoylphosphatidylcholine↗
PubMed1975

Modification of the template capacity of liver chromatin for form-B ribonucleic acid polymerase by food intake in rats under controlled feeding schedules.

Nuclei from liver of rats accustomed to eating during the first 8h of a daily 12h dark period demonstrate an increased capacity to synthesize RNA 6H after the beginning of the feeding period. 2. This increase is accompanied by a higher yield of extractable form-B DNA-dependent RNA polymerase activity. 3. The endogenous RNA polymerase activity associated with nuclear chromatin is also stimulated by food intake. Both purified and chromatin-associated form-B enzyme activities exhibit different ionic strength requirements after food intake. 4. The sensitivity of exogenous (added) form-B-enzyme to changes in ionic strength changes after feeding when chromatin is used as template. 5. Chromatin extracted from the liver of fed rats is a better template for form-B-enzyme than chromatin extracted from starved rats.

Ammonium Sulfate↗
PubMed1975

The effect of spermine on transcription of mammalian chromatin by mammalian deoxyribonucleic acid-dependent ribonucleic acid polymerase.

Isolated rat liver nuclei demonstrate an increased ability to synthesize RNA in the presence of either spermine or spermidine. Spermidine has more effect on the low-salt alpha-amanitin-insensitive reaction, and spermine has more effect on the high-salt alpha-amanitin-sensitive reaction. Spermine is effective at concentrations of 0.1 mM and 1 muM, showing a biphasic effect. The RNA polymerase activity associated with nuclear chromatin is increased in the presence of spermine only at a concentration of 0.1 mM. Aso the transcription of deproteinized liver DNA by liver form-B polymerase or Escherichia coli enzyme is more efficient in the presence of 0.1 mM-spermine. Only when liver chromatin is transcribed by its homologous enzyme (and not by E. coli enzyme) is spermine active at both 0.1mM and 1 muM as in purified nuclei. The lower concentration of spermine (1 muM) is able to affect chromatin transcription by increasing the affinity of chromatin for the enzyme. Our findings suggest a regulatory role of spermine at the level of genome transcription.

Amanitins↗
PubMedDate not supplied

Glycoprotein glycosyltransferases in male reproductive organs and their hormonal regulation.

The prostate glands of rats, mice, guinea pigs and hamsters were found to be a rich source of enzymes catalyzing the Mn2+-dependent transfer of galactose from UDP-galactose to glycoprotein acceptors such as ovomucoid and ovalbumin. The ventral prostate was also very active in promoting transfer of fucose from GDP-fucose to ovomucoid. The prostatic enzymes promoting both galactosyl and fucosyl transfers to glycoproteins were very largely membrane-bound, and were markedly activated by the non-ionic detergent Triton X-100. Castration of adult male resulted in a many-fold and roughly parallel decline in both glycosyltransferase activities over a period of two weeks, which was reversed by subsequent daily treatment with testosterone for 8 days. The very low galactosyltransferase of the ventral prostate of hypophysectomized rats was markedly enhanced by testosterone administration, whereas prolactin alone or in combination with androgen had no significant effect.

Animals↗