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Biomedical subjects

E Donati

Publications and source records attributed to E Donati.

At least 19 recordsLinked to original sources
PubMed2005

The role of higher polythionates in the reduction of chromium(VI) by Acidithiobacillus and Thiobacillus cultures.

In this paper, we report the chromium(VI) reduction by filtrates of Acidithiobacillus and Thiobacillus cultures. Chromium(VI) reduction by filtrates of A. ferrooxidans cultures under acidic conditions was higher than that observed for A. thiooxidans. However, at pH close to 7, chromium(VI) reduction by filtrates of T. thioparus cultures was as high as that by filtrates of A. thiooxidans cultures and much higher than that observed for A. ferrooxidans cultures at the same pH. The capability of these cultures to reduce chromium(VI) was associated specifically with the fraction of cultures (cells, sulphur and associated sulphur compounds) retained by filtration through a 0.45mum filter. In the fraction that comes from A. thiooxidans culture, polythionates (S(x)O(6)(2-)) with 3-7 sulphur atoms were detected and identified (by HPLC with MS as detector). The model of vesicles containing polythionates, sulphur and water agrees with our results.

Acidithiobacillus↗
PubMed2005

Direct determination by capillary electrophoresis of cardiovascular drugs, previously included in liposomes.

The lipophilicity of some cardiovascular drugs was determined by capillary electrophoresis (CE). Mexiletine, amlodipine and indapamide, the drugs considered, were in contact with liposomial vescicles for 2, 4 or 6 h. After the contact time the drugs, penetrated into liposomial vesicles, were determined by CE using phosphate buffer (pH 6.3 or 7.4) or borate buffer (pH 9). The lipophilicity of three drugs was determined considering the drug percentage penetrated into liposomial vesicles. The found lipohilicity order was amlodipine > mexiletine > indapamide.

Cardiovascular Agents↗
PubMed2005

Analysis of diltiazem and its related substances by HPLC and HPLC/MS.

Diltiazem (DTZ) is an optically active calcium channel blocker having a benzodiazepine structure. The drug used in therapy is (+)-cis-diltiazem with configuration (2S,3S). To describe the analytical profile of DTZ different stationary phases (RP-18, RP-8, monolithic support) were tested. The best separation of DTZ from A, B, E and F was obtained using as stationary phase a RP-8 or a monolithic RP-18. The characterization of impurities was carried out using two analytical systems, HPLC and HPLC/MS.

Calcium Channel Blockers↗
PubMed2004

Micellar electrokinetic chromatography for determination of drug partition in phospholipids.

The lipophilicity of pipemidic, nalidixic and oxolinic acids was determined by forming phospholipidic micelles directly in an electrophoretic capillary. Phosphatidylcholine derivatives, namely L-alpha-dilauroyl phosphatidylcholine (DLPC) or L-alpha-dimiristoyl phosphatidylcholine (DMPC), were added in the run buffer (50 mM phosphate buffer at pH 7.4). To obtain a mixed micelle, phospholipidic derivatives and sodium cholate were together added in the run buffer. Considering the increasing of migration time when phosphatidylcholine derivative is added in the run buffer, Ks can be determined and then quinolones lipophilicity.

Anti-Infective Agents↗
PubMed2004

Chiral investigation of midodrine, a long-acting alpha-adrenergic stimulating agent.

Midodrine hydrochloride is a peripheral alpha(1)-adrenoreceptor agonist that induces venous and arterial vasoconstriction. Midodrine, after oral or intravenous administration, undergoes enzymatic hydrolysis and releases deglymidodrine, a pharmacologically active metabolite. Midodrine and deglymidodrine have a chiral carbon in the 2-position. To investigate the bioactivity of racemates and enantiomers of the drug and metabolite, three chromatographic chiral stationary phases, Chiralcel OD-H, Chiralcel OD-R, and alpha(1)-AGP, were evaluated for enantiomeric resolution. Good enantioseparation of midodrine racemate was obtained using the Chiralcel OD-H column. This stationary phase was then used to collect separately the midodrine enantiomers. By alkaline hydrolysis of rac-midodrine and each separated enantiomer, rac-deglymidodrine and its enantiomers were prepared. The control of the enantiomeric purity was carried out by alpha(1)-AGP stationary phase, while the hydrolysis of rac-midodrine and its enantiomers was controlled by capillary electrophoresis using trimethyl-beta-cyclodextrin as chiral selector. The pharmacological activity of the two racemates and the two enantiomeric pairs was tested in vitro on a strip of rabbit descending thoracic aorta. The tests continued that the activity of the drug and metabolite is due only to the (-)-enantiomer because neither of the (+)-enantiomers is active.

Adrenergic alpha-Agonists↗
PubMed2003

Determination of MPTP, a toxic impurity of pethidine.

Pethidine, predominantly a mu-receptor agonist, is a phenyl-piperidinic synthetic drug. It is used in the management of moderate to several pain. A possible hydrolytic degradation of an ester group can generate a very toxic compound, the N-methyl-4-phenyl-1,2,3,6 tetrahydropyridine (MPTP) which contaminates the drug. Because of the toxicity of MPTP a suitable method for its determination must be selective and sensitive. Afterwards we propose simple methods to determine pethidine and MPTP by capillary electrophoresis (CE), MECK and RP-high performance liquid chromatography (HPLC) looking at the limit of detection obtained using these three techniques. CE was carried out using as running buffer ammonium acetate (pH 8.3). MECK was performed with a borate buffer (pH 8.3) containing sodium dodecylsulphate and trimethyl-beta-cyclodextrins. RP-HPLC was carried out on a RP18 stationary phase, using as mobile phase a mixture of phosphate buffer (pH 7) containing acetonitrile and 1% of diethylamine.

1-Methyl-4-phenyl-1,2,3,6-tetrahydropyridine↗
PubMed2003

Ibuprofen quality control by electrochromatography.

The quality control of drugs is generally made by HPLC. This control could be made also by capillary electrochromatography (CEC). In this paper we report the analysis by CEC of ibuprofen, a well-known anti-inflammatory non steroidic drug, and some of its impurities. The analyses were performed in a 100-microm inner diameter (I.D.) fused silica capillary, packed with RP-18 stationary phase. The mobile phase was a mixture of 100 mM formic acid solution (pH 2.5), water and acetonitrile (ACN). The ACN percentage in the mobile phase and the applied voltage were carefully studied to well resolve the drug from each impurity. The results, obtained determining ibuprofen and related compounds by CEC, showed the selectivity and efficiency of the method.

Anti-Inflammatory Agents, Non-Steroidal↗
PubMed2003

Prevalence and chemosusceptibility of Neisseria meningitidis and Haemophilus influenzae in a population of central Italy.

The purpose of this study was to determine the prevalence of nasopharyngeal carriers of Neisseria meningitidis and Haemophilus influenzae, and to evaluate their chemoresistance. N. meningitidis was more frequently isolated in adolescents (10-15 years). All of meningococci were susceptible to ceftriaxone and rifampin, only one isolate showed reduced susceptibility to chloramphenicol and four strains showed reduced penicillin susceptibility. The results show that these drugs are still effective for prophylaxis and treatment in our area. All strains of H. influenzae were susceptible to penicillin, ceftriaxone, chloramphenicol, rifampin, azithromicin and gentamicin. 6 nontypeable strains were resistant to sulfamethoxazole-trimethoprim, 7 strains of type a and c-f, and 3 non-typeable strains showed reduced susceptibility to tetracycline. In contrast with the current trend in the world, in our area the susceptibility of H. influenzae to betalactams was 100%, therefore these antibiotics are still the drugs of choice for treatment of invasive diseases.

Adolescent↗
PubMed2002

Determination of losartan and hydrochlorothiazide in tablets by CE and CEC.

Capillary Electrophoresis (CE) and Capillary Electrochromatography (CEC) have been used to determine losartan and hydrochlorothiazide. The CE separation was carried out in an uncoated capillary filled with a 100 mM sodium borate pH 9 solution containing trimethyl-beta-cyclodextrins. CEC was performed using a capillary packed with a RP-18 stationary phase. The mobile phase was a mixture of 50 mM ammonium acetate pH 7, water, acetonitrile (1/1.5/7.5). By CE and CEC suitable methods to determine simultaneously losartan and hydrochlorothiazide in working standard mixture or pharmaceutical form were obtained. The proposed methods are very simple and both gave accurate and precise results.

Antihypertensive Agents↗
PubMed2002

Chiral discrimination by HPLC and CE and antifungal activity of racemic fenticonazole and its enantiomers.

Fenticonazole is a chiral antifungal agent, used in therapy as the racemic mixture. The investigation on the chirality of fenticonazole is reported in this study. rac-Fenticonazole was resolved by HPLC and by capillary electrophoresis (CE). The chiral stationary phase (CSP), used in HPLC, was Daicel OD-H, a commercial phase, which allowed the separate collection of the two enantiomers. The chiral selectors used for CE were some cyclodextrin derivatives. The analysis time required from CE was about the half the HPLC enantioseparation time. The biological activity of the rac-mixture and each individual enantiomer was tested against Cryptococcus neoformans and two Aspergillus nidulans strains. The minimum inhibitory concentration (MIC) evaluation showed that the eutomer was the enantiomer chromatographically more retained and had a longer migration time in the electrophoretic enantioseparation. The CD spectrum of the eutomer showed a positive Cotton effect.

Antifungal Agents↗
PubMed2001

Spinal dysraphism in an elderly patient.

Spinal dysraphisms are diagnosed more frequently at birth or in infancy. We report a spinal malformation compatible with lipomyeloschisis in an elderly patient presenting with symptoms and signs of myelopathy. Magnetic resonance imaging revealed an intraspinal mass continuous with a subcutaneous lipoma. Three-dimensional computed tomography reconstructions better showed the spinal dysraphism; dermal sinus was also evident. Neuroimaging can define the precise diagnosis also in elderly patients presenting with myelopathy and can provide valuable structural details.

Aged↗
PubMed2001

A rapid PCR method for the detection of slime-producing strains of Staphylococcus epidermidis and S. aureus in periprosthesis infections.

In periprosthesis tissues, Staphylococcus epidermidis produces extracellular polysaccharide slime. Recently it has been shown that S. aureus also produces slime and that both S. epidermidis and S. aureus contain the ica operon responsible for slime production. In the operon, icaA encodes for N-acetylglutaminyltransferase, the enzyme for polysaccharide synthesis. However, co-expression of icaA and icaD is required for full slime synthesis. The slime-producing strains of both S. epidermidis and S. aureus are more virulent and are responsible for severe postsurgical or periprosthesis infections. The authors describe a simple, rapid, and reliable polymerase chain reaction method to detect icaA and icaD. The method was applied to the detection of ica genes on two reference strains, 15 strains each of S. epidermidis and S. aureus from periprosthesis infections and 10 strains from the skin and mucosa of healthy volunteers. icaA and icaD were detectable only in slime-producing strains (tested for slime production on Congo Red agar), and never in nonslime-producing ones. This method is a straightforward way of detecting the slime-producing ability by S. epidermidis and S. aureus. In clinical specimens this polymerase chain reaction method enables rapid diagnosis of virulent slime-producing strains with respect to the traditional culture method on Congo Red agar, which requires much more time. Rapid identification of the virulent properties of the bacterial strain responsible for a staphylococcal infection is crucial for deciding treatment.

Base Sequence↗
PubMed2001

Evaluation of PCR methods for 5S-rDNA and p30 genes to detect Toxoplasma gondii in blood and other clinical samples.

During the last few years the direct diagnosis of Toxoplasma gondii infection has taken advantage of PCR. The present work tested the sensitivity and specificity of PCR for rDNA and p30 genes. Using ascitic fluid from infected mice rDNA PCR detected 0.5 tachyzoite/ml, while nested p30 PCR 1 tachyzoite/ml. The rDNA amplification was positive in all clinical samples from a single immuno compromised patient (blood, urine and bronchoalveolar fluid). In the same patient nested p30 PCR was positive only in urine and bronchoalveolar lavage (BAL) fluid. The rDNA and p30 amplicons were never found in any amniotic fluids tested. These results could prove the usefulness of rDNA amplification to detect T. gondii in blood.

Amniotic Fluid↗
PubMed2000

Iron-oxidizing and leaching activities of sulphur-grown Thiobacillus ferrooxidans cells on other substrates: effect of culture pH.

The rate of iron (II) oxidation by sulphur-grown Thiobacillus ferrooxidans cells decreased when the pH of the original growth medium was lowered. This behaviour was observed even after shifting from the original growth pH to a higher pH. After being suspended in medium at a pH higher than the growth pH, sulphur-grown cells could leach covellite at a similar initial rate to iron-grown cells. Sulphur-grown cells exhibited a long lag phase when the original growth pH was low. These results were correlated with the number of protons associated with the cell surface, rather than with cell hydrophobicity or cell capacity to attach to solid particles. Sulphur-grown cells grown in very acidic media (without pH control) were not able to oxidize iron (II) or leach covellite even after shifting to a high pH.

Journal Article↗
PubMed1999

Human handedness and asymmetry of the motor cortical silent period.

We performed transcranial magnetic stimulation of the motor cortex in 22 left-handed and 25 right-handed subjects during active contraction of a small hand muscle. Motor evoked potentials had the same latency, amplitude and threshold on both sides of the body, whilst the silent period duration was shorter in the dominant hand. Silent periods elicited by nerve and brainstem stimulation were the same in both hands. Since the latter part of the cortical silent period is due mainly to withdrawal of corticospinal input to spinal motoneurones, we speculate that the results are compatible with the suggestion that tonic contractions of the non-dominant hand are associated with a greater involvement of the corticospinal tract than those of the dominant hand. It also seems likely that there is an asymmetry in the excitability of cortical inhibitory mechanisms with those responsible for the cortical silent period being less excitable in the dominant motor cortex.

Adult↗