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Biomedical subjects

M Trotta

Publications and source records attributed to M Trotta.

At least 19 recordsLinked to original sources
PubMed2001

Emulsions containing partially water-miscible solvents for the preparation of drug nanosuspensions.

The aim of this study was to investigate the feasibility of partially water-miscible solvents, such as benzyl alcohol, butyl lactate and triacetin, to prepare drug nanosuspensions by a solvent quenching technique. Mitotane, which possesses very poor water solubility and low bioavailability, was used as model drug. Preparation was by emulsifying an organic solution of the drug in an aqueous solution of a stabilising agent followed by rapid displacement of the solvent from the internal into the external phase, provoking solid particle formation. To verify the influence of emulsion droplet size on the drug particle size, 0.1 or 0.2% of different emulsifiers (Tween 80, caprylyl-capryl glucoside or lecithin) and different homogenisation conditions (Ultra Turrax or a high pressure homogenizer at 200 or 1000 bar for three cycles) were used. In general, emulsion droplet size decreased with high pressure homogenization and on increasing the number of cycles. The size of drug particles, obtained after adding water at a constant rate, was dependent on the droplet size in the emulsion. Drug particles of approximately 80 nm were obtained using butyl lactate, supporting the hypothesis that drug particle formation by the emulsification diffusion process involves generating regions of local supersaturation. Because of the increase in available surface area, the dissolution rate of diaultrafiltrated suspensions increased greatly compared to commercial product.

Emulsions↗
PubMed2001

Transfer of coenzyme Q0 from water to aqueous surfactant solutions: the case of Triton X-100.

The effect of UQ0 on the micellization equilibrium of Triton X-100 has been studied by the analysis of the UV absorption spectra of Triton X-100. In the range of the UQ0 concentration investigated, the critical micelle concentration (CMC) increases at increasing of the solute concentration. The dependence of the CMC on UQ0 concentration has been used to calculate the generalized Setchenov constant. Mixing and dilution enthalpies of aqueous solutions of UQ0 and Triton X-100 were measured and used to calculate the enthalpies of transfer of UQ0 from water to Triton X-100 aqueous solutions. From the dependence of the enthalpy of transfer on surfactant concentration, the distribution constant between aqueous and micellar phase and the standard enthalpy of transfer from water to Triton X-100 micelles were evaluated along with the standard transfer free energy and entropy. All measurements were carried out at 298 K.

Journal Article↗
PubMed2000

Large enhancement of the sub-barrier fusion probability for a halo nucleus

The fusion-fission cross sections of the 4He+238U and 6He+238U systems have been measured, at Louvain-la-Neuve, for energies around and below the Coulomb barrier, using an array of Si detectors surrounding a UF4 target. The data taken with 4He are in good agreement with previous data and with the coupled channel fusion calculation performed with ECIS. The 6He data show a regular trend with a large enhancement below the barrier which is attributed to the halo structure of the 6He nucleus.

Journal Article↗
PubMed1999

Investigation of the phase behaviour of systems containing lecithin and 2-acyl lysolecithin derivatives.

A series of modified phospholipids (m-PC) possessing different acyl chains in position 2, from butanoyl to hexadecanoyl, were prepared by partial synthesis from soybean lysolecithin. They were used with soybean lecithin to construct phase diagrams containing ethanol as cosolvent, water and medium chain triglycerides (MCT) or isopropyl myristate (IPM) as oils. The weight ratios lecithin:m-PC and surfactants:ethanol were kept constant at 1:1. The results indicate that the m-PCs have a strong effect on the microemulsion (L) and liquid crystalline (LC) domains in the water-rich/oil-poor part of the phase diagrams, although all diagrams correspond to a single lecithin:m-PC ratio. On decreasing the acyl chain length, and thus increasing the hydrophilicity of the surfactant, there was a corresponding increase in the L area, which moved towards the aqueous corner of the phase diagrams. The LC phase was detected only in the presence of the hexadecanoyl derivative for the systems containing MCT, and it was not detected only in the presence of the butanoyl derivative for the systems containing IPM. The use of a second hydrophilic surfactant to adjust the packing properties of the lecithin-alcohol systems, and/or to increase the fluidity of the surfactant film, increased the region of existence of the isotropic systems. This may be of importance in the formulation of drug delivery systems, especially those which are diluted by biological fluids upon administration.

Chemistry, Pharmaceutical↗
PubMed1999

On the stability of ascorbic acid in emulsified systems for topical and cosmetic use.

Several O/W microemulsions, O/W and W/O emulsions and a W/O/W multiple emulsion were prepared using non-ionic, non-ethoxylated, skin compatible emulsifiers. Ascorbic acid (vitamin C) was added to the emulsified systems and its stability against oxidation was studied at 45.0 degrees C in aerobic conditions and compared with that in aqueous solutions at different pH values. All emulsified systems provided protection to ascorbic acid, as its degradation rate, which increased with increasing pH, was slower in emulsified systems than in aqueous solutions. The highest protection of ascorbic acid was when it was dissolved in the inner aqueous phase of the W/O/W multiple emulsion, both at 45 and at 20 degrees C for long storage. A pseudo first-order mechanism was hypothesised for ascorbic acid degradation in the experimental conditions for as long as abundant dissolved oxygen was present.

Administration, Topical↗
PubMed1999

Influence of phase transformation on indomethacin release from microemulsions.

The release rates of indomethacin from microemulsions containing water, isopropyl myristate, lecithin, lysolecithin and alcohol are reported. Depending on the composition, the microemulsions transformed on contact with the release medium into emulsions, liquid crystals, or remained as microemulsions. The release rates, measured by monitoring the change in pH of an acceptor phase as the release system was diluted into it, were consistent with an interfacial barrier being the rate-limiting step for solute release. The release rates were found to be dependent on the size of the disperse phase after dilution with the release medium, and on the alcohol used in the formulation. Microemulsions that remained transparent after dilution produced rate constants lower than those that transformed into emulsions. The rate constant for the microemulsion that transforms into liquid crystals was not calculated because of the broad dispersion, but the percentage of drug released was much lower than those from the others systems. The release rates were too rapid to allow sustained drug release, while the release observed for the microemulsion that transformed into liquid crystals was consistent with the slow release required for drug delivery applications.

Anti-Inflammatory Agents, Non-Steroidal↗
PubMed1999

Investigation on the detergent role in the function of secondary quinone in bacterial reaction centers.

In this paper are reported studies on the detergent role in isolated reaction centers (RC) from Rhodobacter sphaeroides, over a large range of lauryldimethylamino-N-oxide (LDAO) concentrations, in influencing the thermodynamics of the quinone exchange reaction as well as the protein aggregation. The occurrence of the quinone exchange reaction between the QB-binding site (where QB is the second quinone molecule of two in the RC) and the ubiquinone 0 dissolved in the different environments (water, LDAO micelles and detergent phase of the protein-detergent complex) has also been analyzed. Measurements carried out in QB-depleted RC to which exogenous quinone has been added show that the relative amplitudes of the slow and fast phase of the recombination reaction depend on this parameter. The overall amount of the restored QB-functionality is affected by the concentration of the LDAO in solution. Interpolation of the titration curves with a quadratic function obtained by simple considerations allowed the binding constant of UQ0 to the QB-binding site to be calculated. From the fitting procedure, the distribution of the quinone in the different environments present in solution was evaluated, indicating that the exchange reaction can take place only between the QB-site and the detergent phase. The dependence of the quinone pool size upon the volume of the phase in which the interacting quinone is solubilized is also discussed. The increasing difficulty in saturating the QB-pocket above the LDAO critical micellar concentration is finally related to the association of protein-detergent complexes to form large protein clusters.

Detergents↗
PubMed1999

Primary tuberculosis of the penis.

We present a case of primary tuberculosis of the inner lining of the prepuce in a 63-year-old man. The condition resembled carcinoma. The diagnosis was based on histopathology and on M. tuberculosis culture. Successful treatment was by a combined medical and surgical approach. The rarity of the case is emphasized.

Antitubercular Agents↗
PubMed1998

Chronic cryptosporidiosis in patients with AIDS: stable remission and possible eradication after long-term, low dose azithromycin.

AIMS: To investigate the effectiveness of long term, low dose azithromycin treatment for chronic cryptosporidiosis in patients with AIDS. METHODS: Azithromycin was administered as initial daily treatment to 13 patients with AIDS: 6 patients received 500 mg for 30 to 40 days (mean 35); 3 patients received 1000 mg for 21 to 50 days (mean 37); and 4 patients received 1500 mg for 20 days. Nine of the 13 patients were also given low dose maintenance treatment with different schedules of azithromycin for 30 to 360 days (mean 129). Patients were monitored, during and after treatment, for parasite shedding in stool and for daily stool frequency and body weight. All but one patient had severe immunodeficiency. RESULTS: Long term, low dose maintenance treatment was associated with major clinical and parasitological benefits: there was probable eradication of infection in 2 patients, and 7 patients showed a complete response with persistent high decrease (5 patients) or clearance (2 patients) of parasite in stool. The drug was well tolerated, and there was no relapse either during treatment or during follow up (up to 21 months). These results were more impressive than those observed after the short term initial course of azithromycin, which was unable at any tested dose to achieve parasite clearance in stool (except in the patient with less advanced immunodeficiency) or to prevent relapse in 3 patients who discontinued treatment. Reversible side effects occurred with the 1500 mg daily dose. CONCLUSIONS: Long term, low dose azithromycin is well tolerated and may induce stable remission of chronic cryptosporidiosis in patients with AIDS. It may lead to probable eradication of the infection in some patients, even those with severe immunodeficiency.

AIDS-Related Opportunistic Infections↗
PubMed1997

Chronic intestinal infection due to subgenus F type 40 adenovirus in a patient with AIDS.

A case of chronic intestinal infection due to adenovirus type 40 lasting for 13 months in a patient with AIDS is described. Adenovirus particles were detected by electron microscopy in biopsy samples taken from the duodenum 3 months after the onset of diarrhoea. The virus was identified as adenovirus type 40 in stool samples by ELISA monoclonal antibodies to adenovirus group antigen (MAd-g2) and types 40 and 41 (MA 40-1 and MA 41-1). No other enteropathogens were found. These data support a causal relationship between adenovirus 40 and the gastrointestinal symptoms of the patient. This is the first reported case of intestinal infection caused by adenovirus type 40 in a patient with AIDS.

AIDS-Related Opportunistic Infections↗
PubMed1997

Effect of oil phase composition on the skin permeation of felodipine from o/w microemulsions.

Oil/water microemulsions containing benzyl alcohol or different ratios of benzyl alcohol and isopropyl myristate as oil phase were prepared and used as vehicles for the transdermal absorption of felodipine. Skin permeation from the microemulsions was compared with that from a drug suspension in an apparent external phase of a microemulsion and with an aqueous drug suspension. The highest flux was from the microemulsion with the highest solubility of felodipine, while the permeation rate decreased over time from the suspension in the apparent external phase. The flux from the aqueous suspension was 10-50 times lower than that from the microemulsions. These results indicate that microemulsions containing benzyl alcohol may be interesting vehicles for transdermal administration of felodipine.

Administration, Cutaneous↗
PubMed1997

[Azithromycin combined with pyrimethamine in the treatment of neurotoxoplasmosis, in an AIDS patient].

We report one case of successful treatment of cerebral toxoplasmosis in acquired immunodeficiency syndrome (AIDS) with azithromycin combined with pyrimethamine. Toxoplasmic encephalitis had been diagnosed on the basis of multiple lesions exhibiting ring like contrast enhancement on double contrast Computed Tomographic (CT) scan of the brain. Thereby our patient had been treated with pyrimethamine 25 mg/die, after an attack dose of 100 mg in the first day, and clindamycin 2400 mg/die, because of sulfa-drug allergy, but clindamycin had to be discontinued because of rash development. At this point azithromycin, at a dose of 1000 mg/die for 21 days and 1500 mg a week for the following 50 days of follow-up, was added to pyrimethamine. Follow-up CT scan after 20 days of treatment (10 with clindamycin+pyrimethamine and 10 with azithromycin+pyrimethamine) revealed partial resolution of the brain lesions and subsequently (after 50 and 80 days of treatment) complete resolution.

AIDS-Related Opportunistic Infections↗
PubMed1996

Role of palmitic acid on the isolation and properties of halorhodopsin.

Purified halorhodopsin was isolated from Halobacterium halobium as previously described (Duschl, A. et al. (1988) J. Biol. Chem. 263, 17016-17022). Two purple bands were eluted from phenyl-Sepharose column, indicating the presence of differently retained halorhodopsin forms; the absorption spectra of the two halorhodopsin bands in the dark were not different. By gas chromatography/mass spectrometry we could identify palmitate (which is only a minor lipid component of archaeal cells) among lipids associated with purple fractions. Typically the palmitate content of the first eluted band was higher than that of the second, indicating a correlation between the palmitate content and the retention time; from one to two fatty acid molecules per halorhodopsin molecule were present depending on the fraction analysed. Very little or no palmitate was released from denatured halorhodopsin. By adding palmitate to buffers used in the phenyl-Sepharose chromatography, only one sharp purple band was collected, corresponding to the less retained halorhodopsin fraction. Pentadecanoic fatty acid could also affect the halorhodopsin chromatography. Chromatography of halorhodopsin in the presence of beta-mercaptoethanol showed only one band, corresponding to the more retrained halorhodopsin form. The two halorhodopsin fractions had different photoreactivity; the less retained halorhodopsin fraction (at higher palmitate content) showed an higher rate of decay of the absorbance at 570 nm upon illumination. By following the decay of the absorbance at 570 nm upon addition of alkali in the dark, we found that the two halorhodopsin fractions had different pKa values of deprotonation.

Bacteriorhodopsins↗
PubMed1996

Influence of counter ions on the skin permeation of methotrexate from water--oil microemulsions.

The influence on the permeation of methotrexate across intact hairless mouse skin of different counter ions added to water--oil (w/o) microemulsions containing lecithin, as surfactant, and water--propylene glycol at different pH values, as internal phase, was studied. As counter ions, monooctyl phosphate, monodecyl phosphate, monodecyl glycerophosphate, taurodeoxycholate, dodecyl sulfate and dioctyl sulfosuccinate were used. At pH 4.0, the transport of methotrexate was enhanced by the counter ions and a marked increase in the flux of the drug was measured when dodecyl sulfate and dioctyl sulfosuccinate were used. At pH 5.0 only a slight increase of the flux was observed. The increased permeation was attributed to the lipophilization of methotrexate as a consequence of ion pair formation.

Animals↗
PubMed1996

Human parvovirus B19 infection within a family and risk for pregnant women.

During an outbreak of parvovirus B19 infection among four related families at least 70% of the household contacts, including a woman at the 33rd week of pregnancy, became infected. Twins were born at the 39th week of pregnancy, both with B19 infection. B19 DNA was detected in their sera by a nested PCR, anti-B19 IgM was detectable only by an immunofluorescence assay, and low levels of maternal anti-B19 IgG were demonstrable by an immunoenzymatic test in the serum of both children. All the haematological parameters were normal at birth and 6 months later, when B19 DNA and anti-B19 antibody were no longer detectable in serum samples. This observation emphasizes the high risk of B19 infection among household contacts and the possibility of a favourable outcome of the foetal infection, possibly related to infection late in the pregnancy.

Adult↗
PubMed1996

[Progressive paralysis. A case report].

STUDY OBJECTIVE: A fairly uncommon case of neurosyphilis is reported in a not immunocompromised patient. CASE REPORT: A case of general paresis in a 40 year-old male with the recent onset of mania is described. Psychiatric anamnesis was negative. Neurologic examination was negative. Laboratory tests were performed and serologic tests for syphilis were positive. Cerebrospinal fluid (CSF) examination showed 80 leukocytes/mm3, a reactive Venereal Disease Research Laboratory (VDRL) and normal protein concentration. CSF gamma globulin with an oligoclonal pattern and abnormal IgG index were found. A test for antibodies to Human Immunodeficiency Virus (HIV) was negative. The patient underwent a high dose intravenous penicillin G regimen for two weeks. A follow-up six months later showed a normal CSF even though the IgG index was still abnormal and the mental status was unchanged. CONCLUDING REMARKS: The authors suggest that patients with neurologic and/or psychiatric symptoms with a recent onset and a reactive VDRL should undergo a CSF examination to exclude a possible neurosyphilis.

Adult↗
PubMed1995

Pseudo-ternary phase diagrams of lecithin-based microemulsions: influence of monoalkylphosphates.

The formation of macroscopically homogeneous, stable, fluid, optically transparent, isotropic solutions (microemulsions) was delineated, at 25 degrees C, for systems containing water, soybean lecithin, sodium monoalkylphosphate (hexyl or ocytl), alcohol and isopropyl myristate. Six straight or branched alcohols (1-butanol, 2-butanol, isobutanol, 1-pentanol, 2-pentanol, 3-pentanol) were investigated as co-surfactants. A constant lecithin/alcohol mixing ratio was used, while the aqueous phase consisted of a solution of alkylphosphates at different concentrations. An increase of the microemulsion domain was seen by increasing the concentration of the alkylphosphate. With 0.2m hexylphosphate, as aqueous phase, the microemulsion domain consisted of a single, region, that, in the presence of butylic alcohols, spanded the greater portion of the phase diagram. In the presence of amyl alcohols the area of this region was much smaller. With 0.2 m octylphosphate the realm of existence of the microemulsions, except for 1-pentanol, consisted of two regions separated by a liquid-crystal region. With all the alcohols examined, the liquid-crystal phase solubilized a larger amount of oil in the presence of octylphosphate than in the presence of hexylphosphate. The stability ranges of microemulsions in systems containing soybean, lecithin, alcohol, water, and isopropyl myristate can be greatly increased by using a second hydrophobic amphiphile, such as hexylphosphate, to adjust the hydrophilic-lipophilic balance or the spontaneous peaking properties of lecithin-alcohol systems.

Chemistry, Pharmaceutical↗