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Biomedical subjects

G Fazio

Publications and source records attributed to G Fazio.

At least 19 recordsLinked to original sources
PubMed2001

Halo structure of (14)Be.

The two-neutron halo nucleus (14)Be has been investigated in a kinematically complete measurement of the fragments ((12)Be and neutrons) produced in dissociation at 35 MeV/nucleon on C and Pb targets. Two-neutron removal cross sections, neutron angular distributions, and invariant mass spectra were measured, and the contributions from electromagnetic dissociation (EMD) were deduced. Comparison with three-body model calculations suggests that the halo wave function contains a large nu(2s(1/2))(2) admixture. The EMD invariant mass spectrum exhibited enhanced strength near threshold consistent with a nonresonant soft-dipole excitation.

Journal Article↗
PubMed2001

Interaction between indomethacin and heavy metal ions in aqueous solution.

The interaction between indomethacin anions and heavy metal ions, such as cadmium, zinc and copper(II) ions, was studied in aqueous solution by polarographic techniques. Indomethacin anions form complexes with these heavy metal ions: the complex formed with cadmium ions is sparingly soluble, while more soluble and also stronger complexes are formed with zinc and copper(II). At high concentrations, where indomethacin anions undergo self-aggregation, these last compounds are solubilised. This property is briefly discussed and compared to that of bile salts. In the presence of calcium ions, indomethacin forms a poorly soluble salt and no evidence was detected for the formation of complex species.

Anti-Inflammatory Agents, Non-Steroidal↗
PubMed1999

Formation of ion-pairs in aqueous solutions of diclofenac salts.

In this work we studied the ability of the diclofenac anion to form ion-pairs in aqueous solution in the presence of organic and inorganic cations: ion-pairs have a polarity and hydrophobicity more suitable to the partition than each ion considered separately and can be extracted by a lipid phase. The cations considered were those of the organic bases diethylamine, diethanolamine, pyrrolidine, N-(2-hydroxyethyl) pyrrolidine and N-(2-hydroxyethyl) piperidine; the inorganic cations studied were Li(+), Na(+), K(+), Rb(+), Cs(+). Related to each cation we determined the equilibrium constant (K(XD)) for the ion-pair formation with the diclofenac anion in aqueous solution and the water/n-octanol partition coefficient (P(XD)) for each type of ion-pair formed. Among the alkali metal cations, only Li(+) shows some interaction with the diclofenac anion, in agreement with its physiological behaviour of increasing clearance during the administration of diclofenac. The influence of the ionic radius and desolvation enthalpy of the alkali metal cations on the ion-pair formation and partition was briefly discussed. Organic cations promote the formation of ion-pairs with the diclofenac anion better than the inorganic ones, and improve the partition of the ion-pair according to their hydrophobicity. The values of the equilibrium parameters for the formation and partition of ion-pairs are not high enough to allow the direct detection of their presence in the aqueous solution. Their formation can be appreciated in the presence of a lipid phase that continuously extracts the ion-pair. Extraction constants (E(XD)=P(XD) times K(XD)) increase passing from inorga to organic cations. This study could help to clarify the mechanism of the percutaneous absorption of diclofenac in the form of a salt, a route where the formation of ion-pairs appears to play an important role.

Anti-Inflammatory Agents, Non-Steroidal↗
PubMed1999

Dehydration and rehydration of a hydrate diclofenac salt at room temperature.

The salt diclofenac/N-(2-hydroxyethyl) pyrrolidine crystallizes from water as a dihydrate, while it precipitates from organic solvents anhydrously: the two salts have different crystal structures. Dehydration of the dihydrate salt was carried out in a desiccator over silica gel at room temperature: the process occurs with the retention of the crystal structure. Slight changes observed in the diffractograms suggest, that soon after dehydration, a phase transition starts, slowly due to the low temperature of the process. The reaction was followed determining the loss of weight as a function of time and by thermal analysis, since the dihydrate and the dehydrate forms have different thermograms, but similar diffractograms. The reaction was complete after 24 h. The analysis of the experimental data suggests a kinetic process related to a one-dimensional diffusion of the crystallization water molecules outwards the solid particles. At room temperature, the dehydrate material rapidly back-absorbs the two molecules of crystallization water from the atmosphere moisture. The interaction with water of the different forms of the salt was discussed as a function of their solid structures as well as of the complex equilibria present in aqueous solution: these can explain previous apparently anomalous results.

Anti-Inflammatory Agents, Non-Steroidal↗
PubMed1999

Effect of the temperature on a hydrate diclofenac salt.

The salt Diclofenac/N-(2-hydroxyethyl) pyrrolidine when crystallizes from water forms a di-hydrate, which looses the crystallization water molecules on heating or in the presence of silica gel, undergoing a phase transition. The two processes were followed at room temperature, at 40 and 50 degrees C by thermal analysis and analyzing the dimensional parameters obtained by scanning electron microscopy as a function of the changes occurring in the solid state. The fractal dimension of the particle surface (DS) was determined for the di-hydrate, the anhydrate and the anhydrous forms: DS values are close together suggesting that the processes modify only slightly the external morphology of the particles. The reactive dimension (DR) to dissolution suggests that the salt after the thermal treatment has a dissolution behaviour identical to that observed for the salt obtained from organic solvents. The two processes de-hydration and phase transition can be carried out at relatively low temperature, suggesting an important pathway to obtain the anhydrous form starting from the di-hydrate one.

Anti-Inflammatory Agents, Non-Steroidal↗
PubMed1997

Interaction of iron(II) with bile salts.

Iron(II) ions react with small aggregates of cholate, glycocholate, chenodeoxycholate, and deoxycholate to form soluble and colloidal compounds. Taurocholate under conditions used does not react with the Fe2+ ion. Small aggregates of dihydroxy bile salts (predominating in the premicellar region, at concentrations of the bile salt above 1 mmol dm-3) have a larger affinity for Fe2+ compared to those formed from cholate anions. In their interactions with small aggregates of cholate anions, the Fe2+ ion shows an affinity comparable to that of Cu2+ and Cd2+ and somewhat larger than that of Zn2+. Small aggregates of cholate show a higher ability to mask Fe2+ than those of taurocholate and glycocholate. Interaction of glycocholic acid anions with Fe2+ ions is sufficient to prevent iron(II) precipitation.

Anions↗
PubMed1996

Earth-Based Observations of the Galileo Probe Entry Site

Earth-based observations of Jupiter indicate that the Galileo probe probably entered Jupiter's atmosphere just inside a region that has less cloud cover and drier conditions than more than 99 percent of the rest of the planet. The visual appearance of the clouds at the site was generally dark at longer wavelengths. The tropospheric and stratospheric temperature fields have a strong longitudinal wave structure that is expected to manifest itself in the vertical temperature profile.

Journal Article↗
PubMed1996

Fractal analysis of sodium cholate particles.

A fractal analysis was carried out on the powder particles of two samples of sodium cholate. A commercial sample had very irregular particles agglomerated, and accordingly the fractal dimension of the surface was 2.98, suggesting a noteworthy roughness of the particle surface; scanning electron microscopy showed that this was due to irregularities caused by a disordered agglomeration of very small particles, resulting in larger particles showing polygonal and smooth but limited facets. A second sample was obtained by recrystallization from ethanol of the commercial sodium cholate and contained large and regular particles, with very smooth surfaces. The fractal dimension therefore was accordingly low. Despite these differences, the two samples had similar, high reactive dimension values to dissolution (2.96 and 2.76, respectively), suggesting that the surfactant behavior of sodium cholate is an important parameter in driving the dissolution of the solid particles and leveling the surface defects.

Cholic Acid↗
PubMed1995

Interaction between Cu2+ ions and cholic acid derivatives followed by polarography.

Interaction of bile salts with Cu2+ ions in unbuffered systems containing 0.15 M NaNO3 was followed by measuring polarographic limiting currents and half-wave potentials. Whereas taurocholate forms neither soluble complexes nor compounds of limited solubility, cholate, glycocholate, and dehydrocholate from both soluble complexes and slightly soluble salts of copper(II) with small aggregates of bile salts. The stability of soluble complexes is comparable for cholates, dehydrocholates, acetates, and acetylglycinates, but smaller for glycocholates. The solubility of the copper(II) salts with small aggregates decreases in the sequence: glycocholate > cholate >> dehydrocholate. It is proposed that these salts are formed by interaction of a copper(II) ion with two carboxylic groups located on the small aggregate in a sufficiently small distance. In the presence of excess cholate the precipitated copper(II) salts are dissolved. It is assumed that at high bile salt concentrations, where precipitates are not observed, larger aggregates are formed that have free carboxylate groups, which increase their solubility in aqueous solutions. For glycocholate, within the accessible concentration range and within the time-frame used (24 h for the establishment of the equilibrium), the formation of such larger aggregates was not observed, even when its "cmc" is comparable with that of cholate. The absence of formation of larger aggregates for dehydrocholate parallels its tendency not to form "micelles".

Carboxylic Acids↗
PubMed1993

Diclofenac/N-(2-hydroxyethyl)pyrrolidine: a new salt for an old drug.

Twenty-four diclofenac salts were prepared using inorganic and organic, linear and cyclic, hydrophilic and hydrophobic bases and their behaviour in polar and poorly polar solvents was examined. Most salts were found more soluble in 1-octanol than in water, suggesting a fair hydrophobicity of these compounds and their existence as ion pairs in non-polar solvents. The salt diclofenac/N-(2-hydroxyethyl)pyrrolidine (DHEP) is the most soluble of this group in 1-octanol (8.39% w/w) and in water (1.89% w/w), where it displays a surfactant behaviour above 1.44% w/w, which can be considered as a critical micellar concentration. It was possible to study the surface activity of diclofenac only using DHEP, since all other salts of this group are not soluble enough to overcome the critical concentration. The mild detergent properties of DHEP were confirmed by the solubilization of lecithin and the formation of mixed micelles with bile salts: these properties appear very interesting in developing new pharmaceutical forms containing DHEP, as a chemical form for the delivery of the active principle diclofenac.

Diclofenac↗
PubMed1992

Basic cholane derivatives. XI: Comparison between acid and basic derivatives.

A series of hydroxycholan-24-amines was synthesized; the carboxyl group of starting unconjugated bile acids was transformed into a basic moiety [-NH2, -NHCH3, -N(CH3)2, or -NHCH2C6H5] at C-24. Solubilities, acidities, partition coefficients, and critical micellar concentrations were measured and compared with those of the corresponding bile acids. Because the steroid nucleus in the amines is the same as that in the bile acids, most of the physical-chemical properties of the two compound classes were similar. The amines were more soluble than the corresponding acids; solubilities depended mainly on the number of steroid hydroxyls and, to a lesser extent, on the side chain. Amines are strong bases in water, whereas unconjugated bile acids can be classified as weak acids. N-Benzylamino derivatives have higher log P (P is partition coefficient) values, as a consequence of the bulky hydrophobic substituent; the log P values were almost the same for the amines and the bile acids and depended on the steroid hydroxyls. Amines can self-aggregate at an acidic pH and form cationic micelles; the critical micellar concentrations of amines were of the same order of magnitude as those of bile acids. The introduction of a basic function in the side chain of the cholane moiety increased the antimicrobial activity toward most gram-positive strains.

Bile Acids and Salts↗
PubMed1992

Chemical properties of bile acids. V. Interaction with concentrated sulfuric acid.

The reaction between concentrated sulfuric acid and steroid hydroxy compounds, previously studied for a series of sterols, was used to develop an analytical method for bile acids. The reaction generates species absorbing in the wavelength ranges 300-320 and 370-390 nm, corresponding to isomeric allylic and dienylic carbocations. Eleven bile acids were examined and influence of time, temperature and sulfuric acid concentration on the chromogenic reaction was studied. The linear dependence of absorbance on concentration of individual bile acids demonstrates that the method can be used to measure spectrophotometrically micromolar concentrations of bile acids.

Adsorption↗
PubMed1991

Long-term follow-up of patients with nonischemic dilated cardiomyopathy and ventricular tachyarrhythmias treated with implantable cardioverter defibrillators.

We analyzed our 10-year cumulative experience of 40 consecutive patients with idiopathic dilated cardiomyopathy and associated ventricular tachyarrhythmias, treated with implantable cardioverter defibrillators. Dilated cardiomyopathy was defined as left ventricular ejection fraction (EF) less than or equal to 50% with no defineable etiology. Patient characteristics included: 24 male, mean age 52 years, mean EF = 33%, New York Heart Association Class I-III, presenting syndrome--cardiac arrest (n = 28), syncope/near syncope (n = 12). At 2.5 years mean follow-up, there were 16 deaths: one operative, three sudden, two incessant ventricular tachycardia/ventricular fibrillation (VT/VF), six heart failure, and four noncardiac. The actuarial mortality at 1 and 4 years was 0% and 14% for sudden death, 11% and 34% for cardiac death. The projected mortality was 52% and 78% for same time intervals (P less than 0.01). No useful baseline variable predicted who would or would not receive an ICD shock in follow-up. ICD therapy appears effective in reducing sudden death mortality in this high risk population.

Cardiomyopathy, Dilated↗
PubMed1991

Chemical properties-dissolution relationship. IV. Behaviour in solution of the diclofenac/N-(2-hydroxyethyl) pyrrolidine salt (DHEP).

The behaviour in solution of the salt formed between diclofenac and N-(2-hydroxyethyl) pyrrolidine (DHEP) was examined. This salt is more soluble and dissolves more rapidly than sodium diclofenac and tends to give rise to supersaturated solutions, that only slowly evolve to equilibrium. Above 35 mM of DHEP, the solutions show unexpected solubilization ability towards sparingly soluble materials. The faster plasma level found, when DHEP is administered per os, can be associated to this weak detergency. These properties make DHEP a suitable pharmaceutical form to prepare extemporary solutions for short term analgesic therapy.

Diclofenac↗
PubMed1990

Seizures in patients with trisomy 21.

We report on the incidence of seizures in 113 patients with Down Syndrome (DS), 43 coming from the OASI Institute for Research on Mental Retardation and Brain Aging, Troina, and 70 from the outpatient clinic of the Department of Pediatrics, University of Catania. We obtained the following results: 15 (13.2%) patients had seizures; 6 (5.3%) febrile seizures (FS) and 9 (7.9%) afebrile seizures (aFS). Among the latter group 2 patients had generalized tonic-clonic seizures, 3 partial complex seizures, and 4 infantile spasms. The seizures appeared early in life. Only 2 adult patients had seizures. These results suggest that patients with DS show a higher incidence of FS and of aFS than non-DS individuals. Seizures in DS may be an epiphenomenon of the neurological abnormalities, both anatomical and functional, usually observed in these patients.

Adult↗