[Bronchial asthma and inflammatory dermatoses. Topical glucocorticoid treatment].
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Administration, Topical↗
Biomedical subjects
Monika Schäfer-Korting
Publications and source records attributed to Monika Schäfer-Korting.
[A silver lining on the horizon: new antimycotics].
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Anti-Bacterial Agents↗
Glucocorticoid receptor interactions with glucocorticoids: evaluation by molecular modeling and functional analysis of glucocorticoid receptor mutants.
In the treatment of inflammatory skin diseases, there are some glucocorticoid (GC) double esters combining pronounced antiinflammatory activity and minor atrophogenic side effects. The reason, however, is only poorly understood. To investigate interactions of GCs with the ligand-binding domain of the glucocorticoid receptor (GR), we measured receptor-binding potency of a series of GC esters including their metabolites and performed a molecular modeling study using progesterone receptor crystal structure data. Ligand docking to the GR-binding pocket showed good fitting of GC 17-esters corresponding to their high receptor-binding affinity, and unfavorable sterical interactions for GC 21-esters with substituents larger than propionate. Molecular dynamics simulations served to visualize induced fit procedures. Ligand docked GC conformations after dynamics simulations were used for generation of a 3D quantitative structure-activity relationship model. Using a set of 11 steroids, this model showed a correlation coefficient (r(2)) of 0.98, a leave-one-out cross validation (q(2)) of 0.79 and was able to predict binding affinity of further six ligands with a standard error of prediction of 0.33. Moreover, interactions of Asn-564 and Met-639 with the steroids were investigated by studying GR mutants of these amino acids. Met-639 participates in hydrophobic interactions mainly with GC side chains, while Asn-564 forms a hydrogen bond to the C11-OH group of the steroid. Asn-564 is shown to be very important for ligand binding and even more for target gene activation and transcription factor repression.
Amino Acid Substitution↗
Sphingosine-1-phosphate and its potentially paradoxical effects on critical parameters of cutaneous wound healing.
The sphingolipid metabolite sphingosine-1-phosphate has emerged as a new bioactive molecule involved in the regulation of cell growth, differentiation, survival, and chemotaxis as well as angiogenesis and embryogenesis. These effects are mediated either via G-protein-coupled receptors or through intracellular actions. The most prominent sources of sphingosine-1-phosphate are human platelets suggesting its potential role in wound healing. In agreement with a positive function on reconstruction of wounded skin, we identified sphingosine-1-phosphate as a potent chemoattractant for keratinocytes as well as an activator of extracellular matrix production by fibroblasts. An unexpected finding is a strong cell growth arrest of keratinocytes after exposure to sphingosine-1-phosphate, as keratinocyte proliferation is critical for re-epithelialization of the wound. Most interestingly, the anti-proliferative effect of sphingosine-1-phosphate is not a result of cytotoxicity or apoptosis as sphingosine-1-phosphate even protects these cells from programmed cell death. Moreover, sphingosine-1-phosphate enhances differentiation of keratinocytes. To investigate further by which signaling pathway cell growth inhibition is mediated expression of the mRNA of all sphingosine-1-phosphate receptors (S1P1-5) was identified. 1 (Edg 1), 2 (Edg 5), 3 (Edg 3), 4 (Edg 6), and 5 (Edg 8) mRNA in keratinocytes was identified. As demonstrated in guanosine 5-[gamma-35S] triphosphate-gammaS binding assays, these G-protein-coupled receptors are functional at nanomolar concentrations. As the anti-proliferative effect of sphingosine-1-phosphate is only partially inhibited in the presence of pertussis toxin, it was investigated if intracellular actions are also involved. Microinjections of sphingosine-1-phosphate in keratinocytes also reduce proliferation suggesting that both sphingosine-1-phosphate receptors as well as intracellular actions mediate sphingosine-1-phosphate- induced cell growth arrest.
Cell Differentiation↗
Albumin effects on drug absorption and metabolism in reconstructed epidermis and excised pig skin.
To replace animal experiments for the risk assessment in cutaneous absorption European and Non-European regulatory authorities urge to develop in vitro test systems. A variety of methods have been established which, however, vary in several respects, such as the nature of the barrier and used media. Since both affect drug uptake we have compared the influence of albumin (BSA) in the acceptor medium on the permeation and metabolism of highly lipophilic steroidal drugs, testosterone and prednicarbate (PC). Surprisingly, the addition of BSA to the acceptor medium slightly reduced the steroid permeation, especially when formulations of poor PC uptake were tested. Moreover, with slow drug permeation the metabolite pattern changed as compared to PC metabolites to be found in albumin-free acceptor medium. This was clearly less the case with PC incorporated into newly developed solid lipid nanoparticles accelerating PC uptake about fourfold. The penetration of testosterone was not influenced by BSA in the acceptor medium. Summarising, these results contribute essentially to the development of appropriate in vitro methods for testing of the cutaneous absorption of drugs, ingredients of cosmetics and for the risk assessment of xenobiotics, pesticides and biozides.
Administration, Cutaneous↗
[Pharmacology at the Free University of Berlin. The presentation of a chair in pharmacology and toxicology at the Free University of Berlin].
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Berlin↗
[New systemic antifungal drugs: mechanisms of action, drug interactions and side effects].
New antifungal agents are needed to match the currently increasing rate of systemic fungal infections and the development of resistant fungal strains. This appears possible by the introduction of second generation azole antifungals which potently inhibit ergosterol synthesis, but also by a partial synthetic echinocandin analogue which acts by the suppression of the enzyme glucan synthase. Voriconazole and caspofungin have been approved for the treatment of invasive aspergillosis. Both drugs are well tolerated if contraindications and--with voriconazole--also possible drug interactions are respected. Possibly these drugs are also suitable for other severe fungal infections including systemic and oropharyngeal candidosis in the immunocompromised host.
Anti-Bacterial Agents↗
Different skin thinning potential of equipotent medium-strength glucocorticoids.
In this study, we investigated the effect of prednicarbate, mometasone furoate and betamethasone 17-valerate on total skin thickness over a treatment period of 6 weeks. The study was conducted as a double-blind, placebo-controlled randomized clinical trial with a confirmatory approach. The influence of these drugs on healthy human skin under non-occlusive conditions was assessed by measuring total skin thickness and epidermal thickness using 20 and 50 MHz sonography, respectively. Epidermal surface structure was evaluated using profilometry. Visual assessment addressed signs of atrophy and formation of telangiectasia. The reduction of total skin thickness induced by prednicarbate was clearly less than that caused by betamethasone 17-valerate and mometasone furoate. Prednicarbate led to a higher degree of skin thinning than vehicle. For technical reasons, epidermal thickness could not be reliably evaluated with 50 MHz sonography. Profilometry did not demonstrate any differences between treatments. Visible signs of atrophy or telangiectasia were detected in two subjects each upon betamethasone 17-valerate and mometasone furoate, but not upon prednicarbate or its vehicle. Prednicarbate is a topical glucocorticoid with an improved benefit/risk ratio, as it causes less skin atrophy than the equipotent betamethasone 17-valerate.
Administration, Topical↗