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Biomedical subjects

G Omar

Publications and source records attributed to G Omar.

17 recordsLinked to original sources
PubMed2005

Treatment of psoriasis with topical sirolimus: preclinical development and a randomized, double-blind trial.

BACKGROUND: Systemically administered sirolimus has demonstrated efficacy in psoriasis in a multicentre European study. OBJECTIVES: To determine the efficacy and safety of topically applied sirolimus in treating psoriasis. METHODS: In vitro studies were followed by a pilot study designed to determine if sirolimus penetrates human skin, and by a randomized, double-blind, left-right comparative, dose-ranging study consisting of treatment with 2.2% sirolimus for 6 weeks and 8% sirolimus for an additional 6 weeks in 24 patients with stable, chronic plaque psoriasis. The primary outcome measure was clinical score. Secondary measures were ultrasound plaque thickness, plaque erythema, and computerized image analysis of immunohistochemical stains for immunocytes and proliferating cells. Pharmacokinetics and blood chemistry monitoring for safety were also performed. RESULTS: A significant reduction in the clinical score (P = 0.03) (mean score 9.1 following sirolimus vs. 11.2 in control) was achieved with topical sirolimus. Measurements of plaque thickness and erythema did not show significant improvement with treatment. Computerized image analysis of biopsies showed a significant reduction in CD4+ cells (P = 0.0054) and proliferating cells (stained by Ki-67) in the epidermis (P = 0.0153) with sirolimus treatment compared with control. CONCLUSIONS: Topically applied sirolimus penetrates normal skin and may have some antipsoriatic and immunosuppressive activity.

Administration, Topical↗
PubMed2001

Dielectronic recombination in plasmas. II. Initial excited states.

Ions in a plasma recombine with electrons by both direct and resonant modes. The latter, the dielectronic recombination, can be a dominant process at temperature near T approximately equal to Z2 Ry, for ions with charge Z. The rates are usually given for target ions in their ground states, and contributions from all doubly excited intermediate states and final singly excited states of the recombined ions are summed over. To facilitate applications of the rates in plasma modelling in terms of rate equations, simple rate formulas are often devised. However, at finite temperature, a sizable fraction of ions is initially in an excited state, and after recombination, ions are usually left in singly excited final states. Thus new empirical rate formulas are needed that exhibit an explicit dependence on final as well as initial states of the ions before and after the recombination. We have calculated properly adjusted rates where (a) the target ions are allowed to be in their ground and excited states, and (b) contributions to the individual final states are explicitly separated. Multiple cascades are important in such calculations. For Al3+ ions we show that rates for the initial excited states are much larger than that for the ground state.

Journal Article↗
PubMed2000

Dielectronic recombination in plasmas: the final state distribution

The dielectronic recombination rate is one of the important input parameters to rate equations for modeling plasmas, where the excited state population of the plasma ions is determined by taking into account the radiative and collisional effects of plasma particles. The rates are often conveniently summarized in the form of empirical formulas to facilitate their use; in particular, properly designed rate formulas are needed that describe the electron capture to the individual singly excited final recombined states. However, the currently available rate formulas fail to meet this requirement, although they are obtained from more detailed benchmark calculations that explicitly include all the important transitions. The modified rate formulas may be obtained by keeping separate the rates to the individual singly excited final states, but still summing the contributions from different intermediate resonance states, with proper account of the cascades. Ne-like Al3+ ions in their ground state are used as examples to show that the rates to the final ground state are reduced by as much as a factor of 5 from the total rates.

Journal Article↗
PubMed1997

Ketoconazole and fluconazole inhibition of the metabolism of cyclosporin A by human liver in vitro.

The effects of the important antifungal agents, ketoconazole (Ket) and fluconazole (Flu), on the microsomal metabolism of cyclosporin A (CsA) by seven human livers was measured in vitro. A total of eight CsA metabolites were identified by high-performance liquid chromatography, with metabolites AM9 and AM1 predominating. Ket was a stronger inhibitor than Flu for the formation of each of the 8 metabolites; the mean IC50 for the inhibition of total CsA metabolism was 0.26 +/- 0.08 microM and 85.7 +/- 23.9 microM for Ket and Flu, respectively. Inhibition by Ket and Flu was noncompetitive, with Ki = 0.13 microM and 25.1 microM, respectively. There was considerable interindividual variation in the sensitivity of CsA metabolism to inhibition by Ket or Flu and the degree of inhibition was not uniform across the range of individual CsA metabolites. In six of the seven livers tested, Ket and Flu inhibited the aggregate formation of secondary metabolites (AM19, AM49, AM4N9, and AM1c) more than the aggregate formation of primary metabolites (AM9, AM1, and AM4N) and inhibited the formation of AM9 more than AM1. Although the degree of inhibition of total CsA metabolism by Flu correlated directly with the control (uninhibited) rate of total CsA metabolism (r = 0.95), no similar correlation for inhibition by Ket was noted, nor was the magnitude of inhibition by Ket and Flu related. The results are discussed in relation to the inhibition of CsA metabolism by Ket and Flu in patients in vivo and to the possibility of changes in the efficacy and toxicity of CsA as a result of alterations in its metabolite profile.

Adult↗
PubMed1993

The effects of retinoids and terbinafine on the human hepatic microsomal metabolism of cyclosporin.

Following the observation of increased trough whole blood cyclosporin A (CyA) concentrations and reduced renal function in a patient with recalcitrant generalized pustular psoriasis treated with a combination of CyA and etretinate, the effect of vitamin A analogues on human microsomal cytochrome P450-dependent CyA metabolism was investigated in vitro. In addition, the effect of terbinafine, a new allylamine antifungal agent, was also tested. Etretinate, its major metabolite acitretin, and isotretinoin, each at a single concentration of 100 microM, inhibited total hepatic microsomal CyA metabolism to a similar extent (33-45%, compared with control values). The generation of total primary and total secondary CyA metabolites was also inhibited to a similar extent by each of the retinoids. Conversely, terbinafine was without significant effect on CyA metabolism in vitro. The results, which suggest that inhibition of hepatic CyA metabolism by retinoids may contribute to increased circulating CyA concentrations, are discussed in relation to other potential drug interactions, and to the use of etretinate in reducing the CyA administered dose.

Acitretin↗
PubMed1989

Purification and characterization of an anticonvulsant-induced human cytochrome P-450 catalysing cyclosporin metabolism.

A form of human hepatic microsomal cytochrome P-450 (P450hA7) with subunit Mr 50,400 has been purified from an epileptic who had been receiving long-term treatment with anticonvulsant drugs. P450hA7 metabolized the immunosuppressant drug cyclosporin A and the dihydropyridine calcium channel antagonist nifedipine, but did not metabolize a similar dihydropyridine drug, nicardipine, nor a series of alkoxyresorufin model substrates. The hepatic microsomal concentration of P450hA7 was higher in five individuals who had been receiving long-term anticonvulsant treatment than in any of 21 individuals who had not been similarly treated. The mean P450hA7 concentration in the treated individuals was 5-fold higher than the mean concentration in the untreated individuals. It is concluded that P450hA7 is a member of the cytochrome P450III family which is induced by anticonvulsant drugs in man.

Adult↗
PubMed1984

False aneurysm of the internal iliac artery with involvement of the reproductive tract. A case report.

A case of rupture of a false internal iliac artery aneurysm is discussed and the known urological and neurological presenting symptoms are reviewed. Therapy is also briefly reviewed. In addition, the first documented case of involvement of the reproductive tract is recorded. The rarity of the condition often leads to misdiagnosis. The most probable cause of the rupture in this patient was syphilis.

Adult↗
PubMed1984

Computed tomography of intraabdominal abscesses.

A total of 78 patients were subjected to computed tomography (CT) over a period of 18 months. CT proved extremely accurate in the diagnosis of intraabdominal abscesses and in estimating the extent of spread. The series included many examples of amoebic and hydatid abscesses with unusual presentations and appearances. The commonest appearance of abscesses on CT was a low-density mass with peripheral rims after the administration of intravenous contrast media, followed by gas-containing low-density lesions which were regarded as showing characteristic features of abscess formation. Pitfalls in the CT appearance of abdominal abscesses were many and correlation with the clinical presentation was essential for diagnosis. The greatest value of CT lay in the rapidity of diagnosis.

Abdominal Muscles↗