Topical diclofenac in the treatment of actinic keratoses.
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Administration, Topical↗
Biomedical subjects
Hans F Merk
Publications and source records attributed to Hans F Merk.
A skin-like cytochrome P450 cocktail activates prohaptens to contact allergenic metabolites.
Allergic contact dermatitis is a complex syndrome representing immunological responses to cutaneous exposure to protein-reactive chemicals. Although many contact sensitizers directly can elicit this disorder, others (prohaptens) require activation. Knowledge regarding the activating mechanisms remains limited, but one possibility is metabolic activation by cytochrome P450 (CYP) enzymes in the skin. We have, after quantitative reverse transcriptase-PCR studies of the CYP content in 18 human skin samples, developed an enriched skin-like recombinant human (rh) CYP cocktail using CYP1A1, 1B1, 2B6, 2E1, and 3A5. To validate the rhCYP cocktail, a prohaptenic conjugated diene ((5R)-5-isopropenyl-2-methyl-1-methylene-2-cyclohexene) was investigated using: the skin-like rhCYP cocktail, a liver-like rhCYP cocktail, single rhCYP enzymes, liver microsomes, keratinocytes, and a dendritic cell (DC) assay. The diene was activated to sensitizing epoxides in all non-cell-based incubations including the skin-like rhCYP cocktail. An exocyclic epoxide metabolite ((7R)-7-isopropenyl-4-methyl-1-oxaspiro[2.5]oct-4-ene) was found to be mainly responsible for the allergenic activity of the diene. This epoxide also induced pronounced DC activation indicated by upregulation of IL-8. The skin-like rhCYP cocktail provides a simplified alternative to using skin tissue preparations in mechanistic studies of CYP-mediated skin metabolism of prohaptens and offers the future possibility of designing in vitro predictive assays for assessment of allergenic activity of prohaptens.
Allergens↗
Enhanced expression levels of IL-31 correlate with IL-4 and IL-13 in atopic and allergic contact dermatitis.
BACKGROUND: IL-31 is produced by activated T lymphocytes, preferentially by TH2 cells. Transgenic mice overexpressing IL-31 have a phenotype resembling allergic dermatitis in human subjects. OBJECTIVE: We sought to evaluate the potential importance of IL-31 in the pathogenesis of human T cell-mediated skin diseases. METHODS: We analyzed total RNA taken from 149 skin biopsy specimens from patients with atopic dermatitis (AD), allergic contact dermatitis (ACD), or psoriasis in comparison with specimens taken from patients with healthy skin (n = 13) by using quantitative real-time PCR for the expression of TH1/TH2 cytokines. RESULTS: We found statistically increased mRNA levels of IL-31 in biopsy specimens taken from patients with AD, irrespective of the severity of the disease and serum IgE levels. Moreover, IL-31 mRNA levels were strongly increased in many biopsy specimens taken from patients with ACD. However, no increased transcription of IL-31 could be detected in biopsy specimens taken from psoriatic plaques. A comparison of mRNA levels of IL-31 with TH1 or TH2 cytokines demonstrates a correlation of the expression of IL-31 with IL-4 and IL-13 but not with IFN-gamma. No significant increase of IL-31 receptor mRNA could be detected in any disease, whereas the second receptor subunit of IL-31, the oncostatin M receptor, seems to be enhanced transcribed in patients with psoriasis. CONCLUSION: IL-31 expression is not only increased in patients with AD but also in those with ACD, 2 pruritic skin disorders. In both types of eczema, expression of IL-31 is associated with the expression of the TH2 cytokines IL-4 and IL-13. CLINICAL IMPLICATIONS: IL-31 might contribute not only to the development of AD but also to ACD-provoked skin inflammation.
Dermatitis, Allergic Contact↗
Skin retinoid concentrations are modulated by CYP26AI expression restricted to basal keratinocytes in normal human skin and differentiated 3D skin models.
Cellular levels of all-trans retinoic acid (RA) are meticulously regulated utilizing an array of systems to balance uptake, biosynthesis, catabolism, and efflux transport. Metabolic transformation of all-trans RA to 4-hydroxylated RA appears to be primarily catalyzed by the cytochrome P450 (CYP) 26AI. Analysis of monolayer cultures of normal human epidermal keratinocytes (NHEKs) and dermal fibroblasts by quantitative real-time PCR and reverse transcription-PCR revealed no basal levels of CYP26AI mRNA expression, whereas specific transcripts were detectable following addition of 10(-6) M all-trans RA. Immunofluorescence and Western blot analysis showed a weak expression of CYP26AI in NHEK, which was increased by stimulation with all-trans RA. Using a newly developed peptide antibody, we further examined the localization of CYP26AI expression in normal skin and three-dimensional (3D) skin models. In contrast to cell culture monolayers where CYP26AI was only weakly detectable, strong constitutive expression of CYP26AI in vivo and in organotypic culture was found to be restricted to basal epidermal keratinocytes, as well as eccrine sweat glands and sebaceous glands. These studies verify the capacity of human skin to metabolize RA, although substantial differences exist in CYP expression between normal skin and 3D skin models compared to monolayer cultures. Complex metabolic processes that maintain retinoid homeostasis may therefore be better studied in model systems more closely resembling in vivo skin. In light of our prior studies documenting the functional activity of RA metabolites, expression of CYP26 in the sebaceous gland epithelium supports the suggestion that altered RA metabolism may be involved in the pathogenesis of acne.
Blotting, Western↗
Onychomycosis in a diabetic patient due to Trichophyton gallinae.
A 67-year-old female suffering from diabetes mellitus type I revealed brownish-yellow discolouration, subungual hyperkeratosis, and onychodystrophy of several finger nails. Upon culturing of nail specimens, Trichophyton gallinae could be repeatedly identified on Sabouraud glucose agar. To our knowledge, this is the first report of a human infection caused by this species in Germany. T. gallinae is a zoophilic dermatophyte that primarily infects higher animals, but can also be transmitted to humans sporadically. Herein, clinical, diagnostic, and epidemiological aspects of this zoophilic dermatophyte are briefly reviewed.
Aged↗
Dual porphyrias revisited.
The porphyrias are clinically and genetically heterogeneous metabolic diseases, which predominantly result from a hereditary dysfunction in the pathway of haeme biosynthesis. Currently, at least eight different forms of porphyrias can be differentiated, all of them characterized by a specific enzyme deficiency that is either inherited in an autosomal-dominant fashion, autosomal recessively or, in the case of porphyria cutanea tarda, might also be acquired. All genes encoding these enzymes have been cloned and several mutations underlying the different types of porphyrias have been reported. Traditionally, the diagnosis of porphyria is made on the basis of clinical symptoms, characteristic biochemical findings and enzyme assays. In some porphyria patients and families, however, these diagnostic tools can reveal simultaneous findings compatible with two different forms of porphyria, a phenomenon referred to as dual porphyria. Here, we give an overview on what is currently known about these peculiar variants of porphyria and suggest that, whenever feasible, molecular genetic analysis should complement the analytical techniques used to characterize patients and families in which a double enzymatic deficiency within the haeme biosynthetic pathway is assumed.
DNA Mutational Analysis↗
Concepts in molecular dermatotoxicology.
In the recent years, molecular research has successfully elucidated some of the major mechanisms through which environmental noxae damage human skin. From this knowledge, novel concepts for skin protection have been developed. Here, we provide a brief overview of some of the most exciting and intriguing concepts in molecular dermatotoxicology.
Cell Membrane↗
Fluoroquinolone-associated anaphylaxis in spontaneous adverse drug reaction reports in Germany: differences in reporting rates between individual fluoroquinolones and occurrence after first-ever use.
BACKGROUND: The frequency of fluoroquinolone-associated anaphylaxis has been estimated to be 1.8-23 per 10 million days of treatment based on spontaneous reports. It is unknown whether there are differences between the reporting rates of anaphylaxis with individual fluoroquinolones. According to pathophysiology, anaphylaxis may be immune mediated (anaphylactic) or not (anaphylactoid). The latter may occur after first-ever intake since no sensitisation phase is necessary. OBJECTIVE: To analyse spontaneous reports of fluoroquinolone-associated anaphylaxis contained in the spontaneous adverse drug reaction database of the Federal Institute for Drugs and Medical Devices in Germany with regard to differences in reporting rates between various fluoroquinolones, the previous intake and the time to onset of the reaction. METHODS: All fluoroquinolone-associated cases of anaphylaxis, anaphylactic shock, and anaphylactic/anaphylactoid reaction spontaneously reported to the Federal Institute for Drugs and Medical Devices between 1 January 1993 and 31 December 2004 were identified and assessed with regard to the correctness of the diagnosis of anaphylaxis, the causal relationship with the drug, the previous intake of fluoroquinolones and the time to onset of the reaction. RESULTS: In 166 of 204 cases identified, the diagnosis of anaphylaxis and a causal relationship with the drug were considered at least possible. Moxifloxacin, levofloxacin, ciprofloxacin and ofloxacin accounted for 90 (54%), 25 (15%), 21 (13%) and 16 (10%) of the 166 cases, respectively. The corresponding reporting rates per 1 million defined daily doses based on crude estimates of exposure were 3.3, 0.6, 0.2 and 0.2 for moxifloxacin, levofloxacin, ciprofloxacin and ofloxacin, respectively. The occurrence of anaphylaxis after the first dose or within the first three days was reported in 71 of 166 (43%) cases, but no information on prior exposure with this or any other fluoroquinolone was provided with these reports. In 21 of 166 (13%) cases, the reaction occurred within the first 3 days and it was stated that the particular fluoroquinolone had never been taken before. CONCLUSIONS: Anaphylaxis appears to be associated with the fluoroquinolone class of antibacterials. Observed differences in reporting rates should be further investigated. Fluoroquinolone-associated anaphylaxis may occur after first-ever intake of the agent.
Adult↗
MnSOD polymorphisms in sensitized patients with delayed-type hypersensitivity reactions to the chemical allergen para-phenylene diamine: a case-control study.
Dyes such as para-phenylene diamine (PPD) or related para-compounds are very common contact sensitizers in man. The corresponding contact dermatitis in sensitized individuals is a complex and common illness associated with considerable morbidity and social cost. It has been found that oxidative stress from reactive oxygen species (ROS) may play an important role in the pre-immunological phase of allergic contact dermatitis to PPD. Manganese superoxide dismutase (MnSOD) is one of the primary enzymes that directly scavenge potential harmful oxidizing species. A valine (Val) to alanine (Ala) substitution at amino acid -9, occurring in the MnSOD gene, has been associated with various disease risk. The aim of our study was to investigate possible associations of the MnSOD 47 T>C genotype in exon 2 (Ala-9Val) and the 339 T>C genotype in exon 3 (Ile58Thr) with contact sensitization to PPD in humans in a case-control study. The study was performed in 157 unrelated cases and 201 age- and gender-matched controls. The MnSOD genotypes were determined using LightCycler allele discrimination assays. No heterozygous (CT) or homozygous carriers (TT) for the Ile58Thr polymorphism were found. The frequency for the C allele of the Ala-9Val polymorphism was 51% (79/157) in cases and 49% (107/201) in controls. Homozygous CC carriers (Ala/Ala) were 27% (43/157) in cases and 23% (46/201) in controls (odds ratio [OR], 1.3; 95% confidence interval [CI], 0.8-2.1). Stratification into subgroups based on gender and age limited the association to females. Increased risk among homozygous CC carriers (Ala/Ala) was only found in the group of older females (over 45 years, 25% versus 18%; OR, 1.5; 95% CI, 0.7-2.34). These data suggest that the C (Ala) allele of MnSOD modifies contact dermatitis risk among older females, but is not an independent susceptibility factor for contact sensitization to PPD.
Adolescent↗
Diagnosis of drug hypersensitivity: lymphocyte transformation test and cytokines.
For all types of allergic reactions including immediate type of reactions, types II and III reactions as well as delayed-type reactions the recognition of the antigen by specifically sensitized T-lymphocytes is a prerequisite. Evidences for the key role of T-lymphocytes in the pathophysiology of allergic drug reactions are positive patch test reactions and the LTT. The proliferative response that can be measured by means of the incorporation of 3H-thymidine during DNA synthesis can be expressed as stimulation index (SI) which is the relation between the cell proliferation with antigen compared without antigen. In addition drug-specific activation of PBMC consistently resulted in IL-5 expression and secretion. The sensitivity of the LTT for the detection of drug sensitization could be improved up to 92% by the measurement of released interleukin-5. The expression and secretion of other cytokines such as IFN-gamma and IL-10 was less consistently and had a diagnostic sensitivity of 36 and 50%, respectively. Microarrays are a promising new technical platform to look for better markers which can be used as a read out in the LTT and other similar assays and to study pharmacological interactions between drugs including cytokines such as interferons and the immune system.
Animals↗
Polysorbate 80 in medical products and nonimmunologic anaphylactoid reactions.
BACKGROUND: Polyoxyethylene-sorbitan-20-monooleate (also known as polysorbate 80 and Tween 80) is a solubilizing agent ubiquitously used in nutritives, creams, ointments, lotions, and multiple medical preparations (e.g., vitamin oils, vaccines, and anticancer agents) and as an additive in tablets. Whereas its relevance as a contact allergen has declined during the past decades, it is of current relevance as a "hidden" inductor of anaphylactoid reactions. OBJECTIVE: To identify polysorbate 80 (generally believed to be an inert vehicle) as an inductor of a severe anaphylactoid reaction. METHODS: Skin prick testing, enzyme-linked immunosorbent assay, IgE immunoblotting, and flow cytometric detection of basophil activation were performed in controls and in a patient with a medical history of anaphylactic shock due to intravenous administration of a multivitamin product during pregnancy. RESULTS: Polysorbate 80 was identified as the causative agent for the anaphylactoid reaction of nonimmunologic origin in the patient. Polysorbate specific IgE antibodies were not identified in enzyme-linked immunosorbent assay and immunoblot examinations, confirming the nonimmunologic nature of the anaphylactoid reaction. CONCLUSIONS: Polysorbate 80 is a ubiquitously used solubilizing agent that can cause severe nonimmunologic anaphylactoid reactions.
Anaphylaxis↗
Interleukin-6-type cytokines upregulate expression of multidrug resistance-associated proteins in NHEK and dermal fibroblasts.
Normal human epidermal keratinocytes (NHEK) and dermal fibroblasts express a cell-specific pattern of efflux transport proteins. Since regulatory mechanisms for these transporters in cells of the human skin were unknown, we analyzed the influence of inflammatory cytokines on the expression of multidrug resistance-associated proteins (MRP1, 3, 4, 5). Using real-time PCR, RT-PCR, cDNA microarray, immunostaining and efflux assays we demonstrated that stimulation of NHEK and primary human dermal fibroblasts with interleukin-6 (IL-6), in combination with its soluble alpha-receptor, or oncostatin M (OSM) for 24-72 h resulted in an upregulation of MRP expression and activity. Both cytokines induced a strong activation of signal transducer and activator of transcription (STAT)1 and STAT3 as well as the mitogen-activated protein kinase (MAPK) Erk1/2. OSM additionally activated proteinkinase B strongly. Using the MAPK/extracellular signal-regulated kinase kinase 1-specific inhibitor U0126 we could exclude a stimulatory effect of MAPK on MRP gene expression. Inhibition of the phosphatidylinositol 3-kinase, however, indicated that this pathway might be involved of OSM-mediated upregulation of MRP4 in dermal fibroblasts. Several inflammatory skin diseases show an enhanced expression of IL-6-type cytokines. Correspondingly, upregulation of MRP expression was found in lesional skin taken from patients with psoriasis and lichen planus.
ATP Binding Cassette Transporter, Subfamily B↗
Retinoic acid and its 4-oxo metabolites are functionally active in human skin cells in vitro.
Retinoic acid exerts a variety of effects on gene transcription that regulate growth, differentiation, and inflammation in normal and neoplastic skin cells. Because there is a lack of information regarding the influence of metabolic transformation of retinoids on their pharmacologic effects in skin, we have analyzed the functional activity of all-trans-, 9-cis-, and 13-cis-retinoic acid and their 4-oxo-metabolites in normal human epidermal keratinocytes (NHEKs) and dermal fibroblasts using gene and protein expression profiling techniques, including cDNA microarrays, two-dimensional gel electrophoresis, and MALDI-MS. It was previously thought that the 4-oxo-metabolites of RA are inert catabolic end-products but our results indicate instead that they display strong and isomer-specific transcriptional regulatory activity in both NHEKs and dermal fibroblasts. Microarray and proteomic analyses identified a number of novel genes/gene products that are influenced by RA treatment of NHEKs or fibroblasts, including genes for enzymes catalyzing biotransformation of retinoids, corticosteroids, and antioxidants and structural and transport proteins known to be essential for homeostasis. Our results expand current knowledge regarding retinoic acid action within skin cells and the target tissue/cell regulatory systems that are important for modulating the physiological and pharmacological effects of this important class of dermatological drugs.
Alitretinoin↗
Lymphocyte transformation test as a diagnostic test in allergic contact dermatitis.
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Allergens↗
The "strip" patch test: results of a multicentre study towards a standardization.
BACKGROUND: The "strip" patch test (SPT) is a variant of patch testing which is used for substances with a poor percutaneous penetration. Penetration of the substances is enhanced by repeated applications of adhesive tape prior to their application to the skin. However, no guidelines exist for standardized performance of the SPT. OBJECTIVES: The aim of this multicentre study was to obtain a first practical approach towards a standardized SPT procedure. METHODS: Intact noninflamed skin of the upper back of 83 healthy volunteers was tape-stripped. For sequential strips, a 25-mm diameter 3M Blenderm surgical tape was vertically applied and gently pressed downward using the fingertips for about 2 s. The tape was removed in one quick movement at an angle of 45 degrees in the direction of adherence. Each strip was performed with a new piece of tape on exactly the same skin area. RESULTS. In each subject, we first determined the number of strips (A) until the skin surface started to glisten and calculated the median number of strips (A) in the sample (A=26 strips). We then ascertained the median number of strips (a) in the sample that was necessary to achieve a statistically significant and twofold increase in TEWL (a=11 strips), revealing a "critical" stratum corneum strip depth. The unknown number of strips (a) for each subject was finally calculated from the formula a/A=a/A, i.e. the individual number of strips (A) until the skin surface started to glisten was multiplied by a derived tape-specific correction factor (cf=a/A=11/26=0.4). The increase in percutaneous penetration in strip patch testing by performing "a" strips versus conventional patch testing was shown by scoring of clinical and subjective SLS irritant reactions. CONCLUSIONS: The present multicentre study outlines an experimentally derived approach for a uniform SPT procedure, which does not require the use of complex technical equipment. This first approach now requires validation by a study involving the application of allergens to obtain evidence of enhancement in the sensitivity of patch testing.
Adhesives↗
The molecular basis of porphyria cutanea tarda in Chile: identification and functional characterization of mutations in the uroporphyrinogen decarboxylase gene.
The porphyrias are heterogeneous disorders arising from predominantly inherited catalytic deficiencies of specific enzymes in heme biosynthesis. Porphyria cutanea tarda (PCT) results from a decreased activity of uroporphyrinogen decarboxylase, the fifth enzyme in heme biosynthesis. The disorder represents the only porphyria that is not exclusively inherited monogenetically. In PCT, at least two different types can be distinguished: acquired/sporadic (type I) PCT, in which the enzymatic deficiency is limited to the liver and inherited/familial (type II) PCT, which is inherited as an autosomal dominant trait with a decrease of enzymatic activity in all tissues. In an effort to characterize the molecular basis of PCT in Chile, we identified eight mutations in 18 previously unclassified PCT families by polymerase chain reaction, heteroduplex analysis, and automated sequencing. To study the role of these mutations in disease causality, in vitro expression of all novel missense mutations was studied. Our results indicate that the frequency of familial PCT in Chile is approximately 50%, thus, to our knowledge, representing the highest incidence of familial PCT reported to date. The data further emphasize the molecular heterogeneity in type II PCT and demonstrate the advantages of molecular genetic techniques as a diagnostic tool and in the detection of clinically asymptomatic mutation carriers.
Chile↗
Allelic loss underlies type 2 segmental Hailey-Hailey disease, providing molecular confirmation of a novel genetic concept.
Hailey-Hailey disease (HHD) is an autosomal dominant trait characterized by erythematous and oozing skin lesions preponderantly involving the body folds. In the present unusual case, however, unilateral segmental areas along the lines of Blaschko showing a rather severe involvement were superimposed on the ordinary symmetrical phenotype. Based on this observation and similar forms of mosaicism as reported in other autosomal dominant skin disorders, we postulated that in such cases, 2 different types of segmental involvement can be distinguished. Accordingly, the linear lesions as noted in the present case would exemplify type 2 segmental HHD. In the heterozygous embryo, loss of heterozygosity occurring at an early developmental stage would have given rise to pronounced linear lesions reflecting homozygosity or hemizygosity for the mutation. By analyzing DNA and RNA derived from blood and skin samples as well as keratinocytes of the index patient with various molecular techniques including RT-PCR, real-time PCR, and microsatellite analysis, we found a consistent loss of the paternal wild-type allele in more severely affected segmental skin regions, confirming this hypothesis for the first time, to our knowledge, at the molecular and cellular level.
Alleles↗
Radical resection of giant congenital melanocytic nevus and reconstruction with meek-graft covered integra dermal template.
BACKGROUND: Giant congenital melanocytic nevi represent a surgical challenge, particularly in cases in which the size of the nevus exceeds certain extend and malignant transformations have to be considered. OBJECTIVE: To discuss through case report considerable surgical options when extensive giant congenital melanocytic nevi with malignant transformation are encountered. METHODS: We present an unusual case of a giant congenital melanocytic nevi of the entire back of a 44-year-old patient. To achieve radical resection with direct appropriate wound closure and acceptable outcome, the integument of the entire back was excised and covered with Integra, followed by split-thickness skin grafting after stable integration of the matrix. RESULTS: The approach resulted in a complete excision of the tumor and acceptable cosmetic and excellent biomechanical outcome. CONCLUSION: The introduced practice demonstrates a useful alternative to established methods, particularly if tumor excision in large areas and subsequent wound closure might be achieved in one procedure.
Adult↗