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Biomedical subjects

C Costa

Publications and source records attributed to C Costa.

At least 145 records · Page 8Linked to original sources
PubMed1990

Fast atom bombardment mass spectrometry in the study of dopamine melanogenesis intermediates.

Fast atom bombardment was applied to the study of the intermediates of the reaction dopamine-tyrosinase after treatment with diazomethane. The identification of trimethoxyindoline, dopamine-o-quinone and dimethoxyindole was easily achieved by this ionization method, together with accurate mass measurements and collision experiments. The structures of these compounds are in agreement with those already hypothesized in studies on melanogenesis.

Dopamine↗
PubMed1990

[Electropherotypes of rotavirus in children with and without gastroenteritis].

It was defined the electropherotypes of rotavirus identified in stools of a groups (named "case") of 500 children with diarrhea, ranging in age from 0 to 12 months. A group (named "control") of 500 children of the same age group, without diarrhea or respiratory infections, were evaluated. Human rotavirus was detected in 14.8% of the children with diarrhea. Of the positive samples 5 had the "short" and 11 the "long" electropherotype. In the control group rotavirus was detected in 0.8% of children and all the three positive samples had "long" electropherotype.

Electrophoresis, Polyacrylamide Gel↗
PubMed1989

[Aneurysms of the abdominal aorta. Clinical evaluation and therapeutic criteria].

On the basis of their own experience and of the most recent acquisitions published in the literature, the authors report on aneurysms of the abdominal aorta which are observed with increasing frequency. After discussing the etiopathogenesis, they dwell on the principal clinical problems of the disease, especially those concerning early diagnosis. Thanks to new acquisitions in vascular surgery, early detection may in fact allow of highly satisfactory therapeutic results.

Adult↗
PubMed1989

[Etiopathogenetic, clinical and therapeutic findings on infectious endocarditis in drug addicts].

Within the sphere of the infectious pathology one usually finds among drug addicts using intravenous methods, a prominent place is occupied by Endocarditis, a serious complication which is one of the more common causes of death among drug addicts. On the basis of the recent literature and their personal experience, the Authors report on several aspects of this illness in addicts, describing the etiological profile and the clinical manifestations in particular, which show clear dissimilarities when compared with infectious endocarditis in patients who are not addicts.

Adult↗
PubMed1989

Guidelines for the dosage of neuroleptics. I: Chlorpromazine equivalents of orally administered neuroleptics.

Chlorpromazine (CPZ) equivalents are often used as a relative measure of the antipsychotic potency of neuroleptics. We review the CPZ equivalents of 33 neuroleptics and illustrate why imprecisions or discrepancies will be difficult to eliminate from these values. We nevertheless underline that CPZ equivalents can be clinically useful, since they facilitate the choice of doses of different neuroleptics that should induce comparable antipsychotic effects.

Antipsychotic Agents↗
PubMed1989

Scoring atopic dermatitis: the simpler the better?

Two scoring methods evaluating the severity of atopic dermatitis have been compared. One was simple, quick and compatible with a busy outpatients clinic. The other was more complicated and time consuming; it took into account most of the evaluable clinical signs of disease activity in each involved site. There was a highly significant correlation between the two methods of scoring, thus validating the simplest one; furthermore, the more complicated method was less reproducible than the simplest when used by two physicians on the same patient. This suggests that a simple and feasible scoring method is meaningful in keeping records at each visit in any patient with atopic dermatitis. Such records may then be used in retrospect for the evaluation of any new therapy.

Adolescent↗
PubMed1988

Spectroscopic characterization of a high-potential monohaem cytochrome from Wolinella succinogenes, a nitrate-respiring organism. Redox and spin equilibria studies.

When purified, a high-potential c-type monohaem cytochrome from the nitrate-respiring organism, Wollinella succinogenes (VPI 10659), displayed a minimum molecular mass of 8.2 kDa and 0.9 mol iron and 0.95 mol haem groups/mol protein. Visible light spectroscopy suggested the presence of an equilibrium between two ligand arrangements around the haem, i.e. an absorption band at 695 nm characteristic of haem-methionine coordination (low-spin form) coexisting with a high-spin form revealed by a band at 619 nm and a shoulder at 498 nm. The mid-point redox potential measured by visible redox titration of the low-spin form was approximately +100 mV. Binding cyanide (Ka = 5 x 10(5) M-1) resulted in the displacement of the methionyl axial residue, and full conversion to a low-spin, cyanide-bound form. Structural features were studied by 300-MHz 1H-NMR spectroscopy. In the oxidized state, the pH dependence of the haem methyl resonances (pH range 5-10) and the magnetic susceptibility measurements (using an NMR method) were consistent with the visible light spectroscopic data for the presence of a high-spin/low-spin equilibrium with a transition pKa of 7.3. The spin equilibrium was fast on the NMR time scale. The haem methyl resonances presented large downfield chemical shifts. An unusually broad methyl resonance at around 35 ppm (pH = 7.5, 25 degrees C) was extremely temperature-dependent [delta(323 K) - delta(273 K) = 7.2 ppm] and was assigned to the S-CH3 group of the axial methionine. In the ferrous state only a low-spin form is present. The haem meso protons, the methyl group and the methylene protons from the axial methionine were identified in the reduced form. The resonances from the aromatic residues (three tyrosines and one phenylalanine) were also assigned. Detailed monitoring of the NMR-redox pattern of the monohaem cytochrome from the fully reduced up to the fully oxidized state revealed that the rate of the intermolecular electronic exchange process was approximately 6 x 10(6) M-1 s-1 at 303 K and pH = 6.31. A dihaem cytochrome also present in the crude cell extract and purified to a homogeneous state, exhibited a molecular mass of 11 kDa and contained 2.43 mol iron and 1.89 mol haem c moieties/mol cytochrome. The absorption spectrum in the visible region exhibited no band at 695 nm, suggesting that methione is not a ligand for either of the two haems. Recovery of only small amounts of this protein prevented more detailed structural analyzes.

Bacteroidaceae↗
PubMed1988

Cytochrome components of nitrate- and sulfate-respiring Desulfovibrio desulfuricans ATCC 27774.

Three multiheme c-type cytochromes--the tetraheme cytochrome c3 (molecular weight [MW] 13,500), a dodecaheme cytochrome c (MW 40,800), and a "split-Soret" cytochrome c (MW 51,540), which is a dimer with 2 hemes per subunit (MW 26,300)--were isolated from the soluble fraction of Desulfovibrio desulfuricans (ATCC 27774) grown under nitrate- or sulfate-respiring conditions. Two of them, the dodecaheme and the split-Soret cytochromes, showed no similarities to any of the c-type cytochromes isolated from other sulfate-reducing bacteria, while the tetraheme cytochrome c3 appeared to be analogous to the cytochrome c3 found in other sulfate-reducing bacteria. For all three multiheme c-type cytochromes isolated, the homologous proteins from nitrate- and sulfate-grown cells were indistinguishable in amino acid composition, physical properties, and spectroscopic characteristics. It therefore appears that the same c-type cytochrome components are present when D. desulfuricans ATCC 27774 cells are grown under either condition. This is in contrast to the considerable difference found in Pseudomonas perfectomarina (Liu et al., J. Bacteriol. 154:278-286, 1983), a marine denitrifier, when the cells are grown on nitrate or oxygen as the terminal electron acceptor. In addition, two spectroscopy methods capable of revealing minute structural variations in proteins provided identical information about the tetraheme cytochrome c3 from nitrate-grown and sulfate-grown cells.

Amino Acids↗
PubMed1988

No effect of ketoconazole on thyroid function of normals and thyrotoxic patients.

To investigate a putative inhibitory effect of the antifungal agent ketoconazole on thyroid function, five patients with thyrotoxicosis and ten normal subjects were treated with ketoconazole at high doses (600 mg daily in three 200 mg oral doses) for four weeks. TSH, TT3, TT4FT3 and FT4 were measured before and after the end of treatment. In all of the normal subjects no significant modifications of circulating thyroid hormones and TSH were detected. In patients with thyrotoxicosis an increase of the levels of circulating thyroid hormones and a worsening of clinical signs were observed. However, this behaviour could not be related to an action of the drug since it not differ from the normal evolution of untreated hyperfunctional thyroid disease. These findings confirm the lack of any inhibitory effect of ketoconazole on the synthesis of thyroid hormones and thyroid function.

Humans↗