PubMed Health⌕ Search

Biomedical subjects

Z Mohamed

Publications and source records attributed to Z Mohamed.

7 recordsLinked to original sources
PubMed1992

Caffeine as a probe for human cytochromes P450: validation using cDNA-expression, immunoinhibition and microsomal kinetic and inhibitor techniques.

The molecular basis for the use of caffeine (CA; 1,3,7-trimethylxanthine) as a probe for specific human cytochromes P450 has been investigated. The CA 1-, 3- and 7-demethylations (to form theobromine, paraxanthine and theophylline, respectively) all followed biphasic kinetics in human liver microsomes. Mean apparent Km values for the high- and low-affinity components of the demethylations ranged from 0.13-0.31 nM and 19.2-30.0 mM, respectively. cDNA-expressed CYP1A2 catalysed all three CA demethylations, and the apparent Km for CA 3-demethylation (the major metabolic pathway in humans) by the expressed enzyme was similar to the Km for the high-affinity liver microsomal CA 3-demethylase. IC50 values for inhibition of the CA demethylations by alpha-naphthoflavone were similar for both expressed CYP1A2 and the high-affinity microsomal demethylases. Moreover, CA was a competitive inhibitor of expressed CYP1A2 catalysed phenacetin O-deethylation, with the apparent Ki (0.080 mM) closely matching the apparent Km (0.082 mM) for CA 3-demethylation by the expressed enzyme. Expressed CYP1A1 was additionally shown to catalyse the 3-demethylation of CA, although activity was lower than that observed for CYP1A2. While these data indicate that CYP1A2 is responsible for the high-affinity component of human liver CA 3-demethylation, two limitations associated with the use of CA as an in vitro probe for CYP1A2 activity have been identified: (i) CA 3-demethylation reflects hepatic CYP1A2 activity only at appropriately low substrate concentrations; and (ii) CA is a non-specific CYP1A substrate and CYP1A1 may therefore contribute to CA 3-demethylase activity in tissues in which it is expressed. An anti-CYP3A antibody essentially abolished the 8-hydroxylation of CA to form trimethyluric acid, suggesting formation of this metabolite may potentially serve as a marker of CYP3A isozyme(s) activity.

Benzoflavones↗
PubMed1992

[Adrenal myelolipoma: a new case. Review].

We report a case of symptomatic myelolipoma with a good evolution at three and a half years' follow up. The clinical features and the diagnosis of this tumor type are discussed. In this case, as in most cases, CT proved to be the most useful in making the diagnosis. Like most of the cases, the patient was middle aged, obese and hypertensive. The etiology, pathogenesis, clinical features and diagnosis of this disease entity are reviewed. The treatment modalities utilized according to the specific features of each case are discussed.

Adrenal Gland Neoplasms↗
PubMed1991

[Current status of transcatheter arterial embolization in urology].

We report our experience of 155 transcatheter arterial embolization (TAE) procedures performed over a period spanning 12 months. The changes relative to the therapeutic approach in renal tumors are discussed. Palliative TAE has increased in comparison to presurgical TAE and the range of possibilities in benign renal pathological conditions has been extended (trauma, hemorrhage, hypertension, etc.). The morbidity ascribable to this technique continues to be low. New embolization materials (ethanol, fine particles, etc.) that are more effective and produce less side effects have become available. To date, TAE continues to be a highly effective therapeutic modality with specific indications and scant morbidity.

Catheterization↗
PubMed1990

Localization of endogenous galactoside-binding lectin during morphogenesis of Xenopus laevis.

A monoclonal antibody has been produced against Xenopus laevis galactoside-binding neural-crest-stage lectin. This antibody inhibits lectin-mediated hemagglutination. Using this antibody in conjunction with immunohistochemical techniques, lectin deposition has been studied in embryos and tadpoles at different stages of morphogenesis, from initial neural crest migration, up to the formation of a swimming tadpole. Lectin levels change during development in different regions of the embryo and tadpole, decreasing in migratory cells, and increasing in sites where cells become more adhesive to one another. The results suggest that galactoside-binding lectins may be an important class of cellular adhesion molecules during these stages of development.

Animals↗
PubMedDate not supplied

[New permanent expandable prosthesis for the treatment of urethral stenosis].

The paper presents our initial experience in the treatment of urethral stenosis through implantation of a "Wallstent" self expanding resident prosthesis. A total of eleven prosthesis were placed in 10 patients with excellent results, from a clinical, urodynamic, radiological and endoscopic point of view, in 9 of them after 5 months. We believe that this kind of prosthesis can be a valid alternative to other established therapeutic options in the management of urethral stenosis. Long-term monitoring, however, will be necessary in order to corroborate the excellent results obtained in this short/medium-term observation.

Adult↗