Biomedical subjects

Maria Rosa Festa

Publications and source records attributed to Maria Rosa Festa.

8 recordsLinked to original sources

PubMedDate not supplied

Penicillamine disulfide (PNS) and alkaline cations.

D-penicillamine disulfide (PNS) shows protolytic properties and is able to form complexes with cations, because it has two aminic groups and two carboxylic groups. The four protonation constants of its deprotonated species were determined by means of electromotive force (e.m.f.) measurements of a galvanic cell involving a glass electrode at 25 degrees C and in a constant ionic medium constituted by N(CH3)4Cl 3.00 or 1.00 mol dm-3. At 25 degrees C and in 3.00 mol dm-3 N(CH3)4Cl as ionic medium, equilibria taking place between PNS and lithium, sodium and potassium ions were investigated. Experimental data, again obtained from e.m.f. measurements, were explained by assuming the formation of species of the type MH2PNS ed M2H2PNS, where M indicates a cation. Stability constants for each proposed species were calculated. A comparison with cystine is discussed.

Cations↗

PubMedDate not supplied

The influence of the ionic medium on the behaviour of sodium glycocholate and cholate aqueous solutions.

In the framework of research on the sodium bile salts, solutions of sodium cholate and glycocholate had been studied only at three ionic medium concentrations. In this paper, experiments in two other concentrations of ionic medium are carried out both to verify the behaviour dependence on the ionic medium and to apply the results of this paper to a future investigation on solutions containing contemporary sodium cholate and glycocholate. To this aim, solubility, protonation constants, lead (II) salts solubility products at 25 degrees C and in 0.300 and 0.750 mol dm(-3) N(CH3)4Cl were determined. The formed species in solutions containing lead (II) together with the selected bile salts and the behaviour of the sodium salts in micellar and premicellar solutions were investigated, too. The obtained results were compared with those obtained at the other ionic medium concentrations.

Glycocholic Acid↗

PubMedDate not supplied

Composition of sodium cholate micellar solutions.

To study the composition of sodium cholate solutions, an investigation was carried out at 25 degrees C and in N(CH3)4Cl, as a constant ionic medium, at three different concentrations (W = 0.100; 0.500 and 0.800 mol dm(-3)). Electromotive force measurements of three different galvanic cells, the first involving a glass electrode for hydrogen ions, the second an electrode for sodium ions and the third a lead amalgam electrode, were performed. Independently, lead (II) cholate solubility measurements in the presence of sodium ions were performed, as well. The experimental results obtained from both approaches were explained by assuming the formation of aggregates in cholate and sodium of different composition depending on W and on the cholate concentration. The maximum aggregation found number for cholate was 24 and even aggregation numbers were markedly predominant. Only two species with odd aggregation number were found, but at a low percentage. The assumed species and the relative constants were compared with those found for the other sodium salt of cholanic acids.

Cholic Acids↗

PubMedDate not supplied

Ratios between content of fatty acids as markers for mixture of cow and goat milk.

The fat of mixture of goat and cow milk, extracted by di-ethylic ether, was gas chromatographically analysed in order to propose an analytical procedure suitable to reveal small additions of cow milk to goat milk. The obtained results show evident differences in the percentages of some fatty acids. An attempt to apply the peak area ratios, corresponding to the methyl esters of fatty acids, suggested by the literature for cow milk did not yield good results. Other ratios suitable to reveal even the presence of low percentages (up to 5 %) of cow milk in goat milk were found and proposed in this paper. Such ratios are sensitive and can be defined markers towards cow or goat milk and also towards extraneous fat like lard or colza seeds oil.

Animals↗

PubMedDate not supplied

Composition of aqueous solutions containing sodium glycocholate and glycodeoxycholate.

Composition and existence range of aggregates formed by sodium glycocholate and glycodeoxycholate contemporary present in aqueous micellar and premicellar solutions were investigated. Solubility measurements of lead (II) glycocholate and glycodeoxycholate give analytical concentration of lead (II) and glycocholate and glycodeoxycholate, respectively. Electromotive force measurements provide the free concentration of hydrogen, sodium and lead (II) ions. Experimental data obtained at 25 degrees C and at three different concentrations of N(CH3)4Cl, used as a constant ionic medium, can be explained by assuming the presence of aggregates of different composition depending on the reagent and ionic medium concentrations. Next to two species containing only glycocholate or glycodeoxycholate, the presence of aggregates formed with the contemporary participation of both bile anions in different ratios was assumed. Species with the hydrogen ion participation are not present in appreciable quantity in the investigated concentration range. As expected, the size of aggregates increases by increasing reagent and ionic medium concentration. Most of the species can be explained with a "core + link" mechanism, where all the glycocholate aggregation numbers are even, while those of glycodeoxycholate are always multiple of three. Analogy and difference with aggregates formed by the two bile anions separately are discussed.

Glycocholic Acid↗

PubMedDate not supplied

On lead(II) glycocholate solubility.

The solubility of lead(II) glycocholate was studied as a function of glycocholate ion concentration at 25 degrees C and in 0.100, 0.500 and 0.800 mol dm-3 N(CH3)4Cl as a constant ionic medium. For this purpose the total concentration of lead(II) was determined by means of atomic absorption spectrophotometry and polarography measurements in solution equilibrated with solid lead(II) glycocholate at known hydrogen ion concentration. The free concentration of lead(II) and hydrogen ions was determined by measuring the electromotive force(e.m.f.) of galvanic cells involving lead amalgam and glass electrode. The e.m.f. measurements were carried out both in clear solutions before precipitation and in the presence of the precipitate. The results of the solubility and e.m.f. measurements could be explained by assuming the presence of associated species between lead(II) and glycocholate. The solubility product and the association constants were determined for all the ionic medium concentrations.

Glycocholic Acid↗

PubMedDate not supplied

Number of eggs in egg-noodles.

The official method to determine the number of eggs present in egg-noodles is the digitonin method. By applying this method the total content of sterols is determined and expressed as total sterols. The official method is time consuming, not very accurate and its performance is very complicated. Its results are not very reliable either because the composition of the wheat is not considered. In this paper some markers are proposed to verify the correct ratio between eggs and triticum durum (TD) semolina used to prepare egg-noodles. Markers are selected ratios between sterols and FAME. The lipid extract is trans-esterified and injected into a gas chromatograph. The ratio between the areas of the selected components gives the markers. This method is proposed to substitute or alternate the official method because is more accurate and time saving.

Eggs↗

PubMedDate not supplied

Lead (II) cholate solubility.

In the framework of the research carried out on the behaviour of the salts of bile acids in aqueous solutions, the lead (II) cholate solubility was determined at 25 degrees C and in 0.100, 0.500 and 0.800 mol dm(-3) N(CH3)4Cl, as ionic medium. The change of its solubility was studied as a function of the cholate and hydrogen ion concentration. Solubility and electromotive force measurements of suitable galvanic cells were carried out and from the results lead (II) cholate solubility product could be calculated and the presence of associated species in solution in the ratio 1:3 and 1:4 between lead (II) and cholate was assumed. The relative constants were determined, as well. The results of this work allow us to obtain the free cholate concentration in equilibrium with solid lead (II) cholate.

Cholates↗