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Biomedical subjects

P Valenti

Publications and source records attributed to P Valenti.

At least 127 records · Page 7Linked to original sources
PubMed1987

The effect of saturation with Zn2+ and other metal ions on the antibacterial activity of ovotransferrin.

The antibacterial activity of metal complexes of ovotransferrin was tested "in vitro" against different bacterial species and the Zn2+ saturated ovotransferrin appeared to be the most active by comparison with the apo-protein and other metal complexes. Appropriate controls showed that such an effect was neither due to Zn2+ ions, nor to iron deprivation, but to a specific activity of the Zn-ovotransferrin complex. This antibacterial activity required a direct contact of Zn-ovotransferrin with the bacterial surface. In vivo experiments confirmed the higher antibacterial activity of Zn-ovotransferrin as compared with the apo-form.

Animals↗
PubMed1985

Antifungal activity of ovotransferrin towards genus Candida.

The inhibiting activity of ovotransferrin was tested towards different species belonging to genus Candida. Of one hundred strains tested, only C. krusei showed a noticeable resistance, while the other species appeared to be more sensitive than bacteria to the action of ovotransferrin. The influence of anions, such as bicarbonate and citrate, on the inhibiting activity of ovotransferrin was also investigated. Moreover it was observed that iron saturated ovotransferrin retained its activity, thus suggesting an interaction between the protein and Candida cells.

Antifungal Agents↗
PubMed1985

Composite IS1 elements encoding hydroxamate-mediated iron uptake in FIme plasmids from epidemic Salmonella spp.

Eleven FIme plasmids representative of those identified in epidemic strains of Salmonella wien and Salmonella typhimurium isolated in North Africa, Europe, and the Middle East have been examined for the presence of determinants of toxigenicity, adherence, and iron-sequestering mechanisms. Chemical and genetic data indicated that all plasmids code for a hydroxamate-mediated iron assimilation system. Detailed analysis of derivative plasmids and cloned fragments of FIme plasmid pZM61 demonstrated that the general genetic and structural organization of the DNA region containing the genes for hydroxamate biosynthesis and cloacin DF13 receptor was virtually identical to that described for the aerobactin-mediated iron uptake system of pColV-K30. This DNA region is part of a composite element that is 16.7 kilobases long and carries its IS1 modules as inverted repeats. A very similar element is present in either orientation in all nine FIme plasmids analyzed.

Base Sequence↗
PubMed1985

Antilipolytic activity of tiadenol-nicotinate in isolated fat cells: a comparison with its parent drugs.

Tiadenol-nicotinate is an ester in which two molecules of nicotinic acid are linked to one molecule of tiadenol. In the present study the antilipolytic activity of tiadenol-nicotinate was evaluated in isolated rat fat cells and a direct comparison was made with the parent drugs. Basal lipolysis was not affected by tiadenol-nicotinate or by nicotinic acid, but it was reduced by a high concentration of tiadenol (10(-3) M) alone or associated with a double concentration of nicotinic acid. Tiadenol-nicotinate (10(-5)-10(-3) M) was very effective in antagonizing the lipolytic action of epinephrine (10(-6) M) and of theophylline (3 X 10(-4) M). The latter drugs were equally sensitive to the inhibitory effect of tiadenol, while nicotinic acid reduced the action of theophylline more than the effect of the catecholamine. Neither of the parent drugs was as effective as tiadenol-nicotinate at this level. However, nicotinic acid potentiated the antilipolytic effect of tiadenol, thus making it possible to reach an inhibitory effect quantitatively similar to or even higher than the effect of tiadenol-nicotinate. These results show that tiadenol-nicotinate is a potent antilipolytic agent in vitro and that its effect may be due to hydrolysis of the ester and release of the parent drugs. The possible therapeutic value of tiadenol-nicotinate is discussed.

Adipose Tissue↗
PubMed1983

Studies of the antimicrobial activity of ovotransferrin.

The antibacterial activity of ovotransferrin (conalbumin) against different bacterial species was studied in vitro. The most sensitive species were Pseudomonas sp., E. coli, S. mutans; and the most resistant ones S. aureus, Proteus sp., Klebsiella. The bacteriostatic activity of conalbumin in various conditions was also tested. The presence of bicarbonate ions always increased the activity of conalbumin, while an antagonistic effect of citrate was observed in bacteria with a receptor for the iron-citrate complex. Experiments with conalbumin covalently linked to Sepharose 4B indicated that its antibacterial activity may not be due simply to the removal of iron from the medium, but probably involves other metals and an interaction with the bacterial surface. The in vitro studies carried out with conalbumin and lactoferrin demonstrated that the two proteins produced a similar inhibition of growth of E. coli and S. mutans. The in vivo studies showed that the protective effect of conalbumin in newborn guinea pigs with E. coli by gastrointestinal route was similar to that naturally provided by the lactoferrin present in milk.

Animals↗
PubMed1982

Antibacterial activity of matrix-bound ovotransferrin.

Ovotransferrin immobilized by covalent linkage to Sepharose 4B showed a bacteriostatic effect towards Escherichia coli similar to that of free ovotransferrin. The growth of the bacteria, after exposure to the gel-bound ovotransferrin and its removal, depended on the length of exposure. The results suggest that the antibacterial activity of transferrin is not due simply to the removal of iron from the medium.

Anti-Bacterial Agents↗