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S Giuffrida

Publications and source records attributed to S Giuffrida.

48 records · Page 3Linked to original sources
PubMed1994

Molecular mechanism of drug photosensitization. 5. Photohemolysis sensitized by Suprofen.

Red blood cell lysis photosensitized by Suprofen (SPF) and the photolysis of the drug were investigated. The photohemolysis process occurs at a higher rate in anaerobic than aerobic conditions. The effect of additives demonstrates the involvement of free radicals and, to a lesser extent, singlet oxygen and hydroxyl radicals in the process. Photolysis of the drug at 310-390 nm in deaerated buffered solutions (pH 7.4) leads to a decarboxylation process with the formation of p-ethylphenyl 2-thienyl ketone (I), whereas in aerated solutions formation of photoproduct I and of the photoproducts p-acetylphenyl 2-thienyl ketone (II) and p-(1-hydroxyethyl)phenyl-2-thienyl ketone (III) occurs. The photodegradation products, which were separated and characterized, show a moderate lytic and photolytic activity. The rate of SPF photodegradation decreases in the presence of oxygen and increases in the presence of hydrogen donors. The overall results lead us to propose a mechanism of SPF photodegradation and a hemolysis scheme in which cell damage is provoked principally by the direct attack of drug radicals and secondarily by singlet oxygen and hydroxyl radicals.

Aerobiosis↗
PubMed1993

Determination of superoxide dismutase-like activity of copper(II) complexes. Relevance of the speciation for the correct interpretation of in vitro O2- scavenger activity.

The superoxide dismutase activity of several copper(II) complexes of linear and cyclic dipeptides has been measured. The results of a classic indirect method (xanthine-xanthine oxidase) have been compared with those obtained by generation of the superoxide radical through 2-(3-benzoylphenyl)propionic acid (ketoprofen) photolysis. A simulation approach, based on the knowledge of the stability constants of the different complex species existing in experimental conditions, has allowed us to obtain the correct speciation and to use these data to calculate the pertinent catalytic constants.

Catalysis↗
PubMed1993

Molecular mechanism of drug photosensitization. 4. Photohemolysis sensitized by carprofen.

Red blood cell lysis photosensitized by carprofen (CPF) was investigated. The photohemolysis process was observed in both aerobic and anaerobic conditions. Irradiation (310-390 nm) of buffered CPF solutions at pH 7.4 in deaerated conditions leads to a dehalogenation process via intermediate radicals with formation of the compound 2-(2-carbazolyl)propanoic acid (I) in the presence of hydrogen donors. Irradiation of I produces decarboxylation via free radicals and the formation of a stable decarboxylated compound, 2-ethylcarbazole (II). The photodegradation products I and II do not show lytic activity. The dechlorinated product I shows photosensitizing ability which was studied in the presence of the red blood cells in both aerated and deaerated solution. When carried out in the presence of additives, the observed photohemolysis suggests the involvement of free radicals and singlet oxygen in the membrane damage induced by both CPF and photoproduct I irradiation, whereas there is no evidence of any role for hydroxyl radicals. Superoxide anion is involved only in the photosensitization process induced by photoproduct I.

Aerobiosis↗
PubMed1993

Magnetic resonance imaging in cervical spinal cord compression.

In patients with cervical spondylotic myelopathy MRI sometimes shows increased signal intensity zones on the T2-weighted images. It has been suggested that these findings carry prognostic significance. We studied 56 subjects with cervical spinal cord compression. Twelve patients showed an increased signal intensity (21.4%) and a prevalence of narrowing of the AP-diameter (62% vs 24%). Furthermore, in this group, there was evidence of a longer mean duration of the symptoms and, in most of the patients, of more serious clinical conditions. The importance of these predisposing factors remains, however, to be clarified since they are also present in some patients without the increased signal intensity.

Adult↗
PubMed1991

Molecular mechanism of drug photosensitization. Part 3. Photohemolysis sensitized by diflunisal.

The lysis of red blood cells photosensitized by diflunisal (DFN) was investigated. Photohemolysis is inhibited by butylated hydroxyanisole and reduced glutathione, but is unaffected by mannitol and enhanced by sodium azide; the presence of oxygen markedly reduces the lysis which is accelerated in anaerobic conditions. These results contrast with those expected for a photodynamic mechanism. High lytic activity is observed for pre-irradiated solutions, mainly under anaerobic conditions. Direct irradiation of DFN in buffer solution at pH 7.4 leads to the formation, under anaerobic conditions, of compound 2'-(2''',4'''-difluoro-3''-carboxy-[1'',1'''-biphenyl]-4''-oxy)-4'- fluoro-4-hydroxy-[1,1'-biphenyl]-3-carboxylic acid (PhP), whereas under aerobic conditions formation of PhP is accompanied by unidentified photo-oxidation products; only compound PhP displays strong lytic activity. The overall results for DFN-photosensitized hemolysis suggest a mechanism involving a concerted action of free radicals, superoxide anion, singlet oxygen and sensitizer photoproducts.

Aerobiosis↗
PubMed1986

Cystic meningiomas. Report of seven cases.

Seven patients with cystic meningioma are reported. The computerized tomography appearance of these meningiomas may mimic that of a glial or metastatic tumor with cystic or necrotic changes, and lead to an incorrect presumptive diagnosis. Radiological evaluation and recognition are important for the surgical removal of these potentially curable neoplasms.

Adolescent↗
PubMedDate not supplied

The nerves of the upper and lower extremities which are at a greater risk of compressive pathology. Anatomical topographical correlations. Our experience.

The experience of numerous cases of surgical operations carried out over the ten years from 1990-2000, has meant we have been able to reflect on the fact that the median, ulnar, radial (upper extremity), tibial and external popliteal sciatic (lower extremity) nerves are more greatly exposed to compressive pathology. This is due to certain anatomical topographical relationships with canals, semi-canals, tunnels in well-defined and unchanging sites. From this point of view, a pathology with an etiopathogenic topographical tendency is emerging.

Arm↗
PubMedDate not supplied

Leukoaraiosis and lacunar infarcts in ischemic stroke: role of age and vascular risk factors.

To assess the role that age and some vascular risk factors play in the pathogenesis of leukoaraiosis and lacunar infarcts in patients with ischemic stroke, we examined 71 consecutive patients who had undergone magnetic resonance imaging because of clinical suspicion of stroke. We collected data regarding hypertension, diabetes mellitus, cardiac diseases, hypercholesterolemia, and hematocrit, and compared patients with lacunar infarcts to those with cortical or subcortical nonlacunar lesions. Patients were then assigned to one of two age groups, Group A (< or = 66 years), or Group B (> 66 years). We found a significant correlation between the presence and severity of leukoaraiosis and the presence of lacunar infarcts in both groups. In Group A, however, lacunar infarcts were correlated to hematocrit, while in Group B they were correlated to a trend to hypertension. Leukoaraiosis was correlated to hypertension only in Group A. Although we noted a strong correlation between leukoaraiosis and lacunar infarcts suggesting a common small-vessel disease, our data indicate that different pathogenetic mechanisms are involved. We suggest that patients be grouped according to age in future studies on the role that risk factors play in the pathogenesis of leukoaraiosis and lacunar infarcts.

Age Factors↗