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H F Merk

Publications and source records attributed to H F Merk.

At least 19 recordsLinked to original sources

[Array technology in skin pharmacology and allergology].

Because of their variable application, microarrays are currently used in different areas of research and development, such as skin pharmacology and allergology. Microarrays are plane carriers, on whose surface a variety of known DNA-molecules and proteins were immobilised. Transcripts can be detected by cDNA- and oligonucleotid-arrays and proteins of activated genes can be discovered using antibody microarrays. Detection of allergen-specific IgE from human serum can be performed using allergen chips. Since many details of the molecular mechanism and pathogenesis of skin cancer and inflammatory skin diseases and the effect of xenobiotics on cells of the human skin are still not known, array-technologies are a powerful tool to identify novel marker genes and offer the possibility of develop new therapeutic strategies as well as prognosis- and diagnosis-systems.

Allergens↗

CD63 expression on basophils as a tool for the diagnosis of pollen-associated food allergy: sensitivity and specificity.

BACKGROUND: Basophil activation is associated with the expression of CD63. Because allergens can induce basophil activation by cross-linking specific IgE, increased CD63 expression has been proposed as a novel in vitro test for immediate type allergy. OBJECTIVE: We compared the CD63-based basophil activation test (BAT) in the diagnosis of allergy to carrot, celery and hazelnut with skin prick tests (SPT) and measurement of allergen-specific IgE. METHODS: Twenty-nine patients with a history of an oral allergy syndrome induced by carrot, celery or hazelnut (n = 20 for each allergen) and 20 controls were studied. SPT were performed with standardized and native carrot, celery and hazelnut extracts. Allergen-specific IgE was determined by the CAP FEIA method and basophil activation was determined by flow cytometry upon double staining with anti-IgE/anti-CD63 mAb. RESULTS: SPT with native carrot, celery and hazelnut showed sensitivities of 100%, 100% and 90%, and specificities of 80%, 80% and 90%. SPT with commercial extracts of the same allergens gave sensitivities of 85%, 80% and 85%, and specificities of 80%, 80% and 90%. Sensitivity of allergen-specific IgE and the BAT for carrot, celery and hazelnut was 80% vs. 85%, 70% vs. 85%, and 80% vs. 90%, with corresponding specificities of 80% vs. 85%, 80% vs. 80%, and 95% vs. 90%. The cut-off for a positive BAT was 10% CD63+ basophils. Moreover, there was a positive correlation between IgE reactivity and the number of CD63+ basophils for all food allergens (carrot: r = 0.69, celery: r = 0.67, hazelnut: r = 0.66). CONCLUSIONS: Quantification of basophil activation by CD63 expression is a valuable new in vitro method for diagnosis of immediate type food sensitization. Although double-blind placebo-controlled food challenges remain the gold standard, the CD63-based BAT may supplement routine diagnostic tests such as SPT or allergen-specific IgE in the future.

Antigens, CD↗

Amoxicillin-induced exanthema in young adults with infectious mononucleosis: demonstration of drug-specific lymphocyte reactivity.

BACKGROUND: Teenagers and young adults frequently develop maculopapular exanthema following amoxicillin intake within infectious mononucleosis. The underlying pathomechanisms are still largely unknown. OBJECTIVES: To investigate whether amoxicillin-induced exanthema in florid infectious mononucleosis is a disease-associated phenomenon or results from specific sensitization to the drug. METHODS: Four patients with amoxicillin-induced exanthema within infectious mononucleosis were analysed in vivo by prick, intradermal and patch tests and in vitro by means of the lymphocyte transformation test (LTT) employing amoxicillin, ampicillin, benzylpenicillin and phenoxymethylpenicillin. RESULTS: Drug-specific sensitization to amoxicillin in the LTT was observed in three patients, two of whom showed a side-chain-specific sensitization to amoxicillin and ampicillin. The in vitro results were confirmed in vivo by skin tests. CONCLUSIONS: These data suggest that real sensitization to amoxicillin and ampicillin may occur within infectious mononucleosis and may be detected in vivo and in vitro by means of skin tests and the LTT.

Adult↗

Determination of interleukin-5 secretion from drug-specific activated ex vivo peripheral blood mononuclear cells as a test system for the in vitro detection of drug sensitization.

BACKGROUND: In vitro detection of drug sensitization is still limited. The lymphocyte transformation test, which determines drug-specific proliferation, is the only in vitro test for detecting drug sensitization at the cellular level irrespective of the reaction's clinical phenotype. Accumulation of eosinophils following IL-5 secretion from drug-specific stimulated T cells is a characteristic histological feature of drug-induced skin eruptions. OBJECTIVE: We determined whether in vitro drug-specific activation of ex vivo peripheral blood mononuclear cells from 10 patients with drug-induced maculopapular exanthems and three patients with severe skin reactions results in secretion of IL-5, IL-10 or IFN-gamma and assessed the sensitivity and specificity of drug-specific IL-5 secretion as a test system compared with the lymphocyte transformation test and patch tests. Furthermore, the subsets of CD4+ and CD8+ T cells involved in drug-specific proliferation, IL-5 secretion and mRNA expression were examined in three patients. METHODS: Drug-specific proliferation of peripheral blood mononuclear cells in the lymphocyte transformation test was investigated by 3H-thymidine uptake, and culture supernatants taken after 5 days were analysed for IL-5, IL-10 and IFN-gamma concentrations by ELISA technique. IL-5 mRNA expression was determined by RT-PCR. RESULTS: Drug-specific activation of peripheral blood mononuclear cells consistently resulted in IL-5 and to a lesser extent in IL-10 and IFN-gamma secretion. The sensitivities of the patch test, lymphocyte transformation test and assessment of drug-specific IL-5 secretion for the detection of drug sensitization were 55%, 75% and 92%, respectively. CONCLUSION: These data suggest a role for the determination of drug-specific IL-5 secretion by ex vivo peripheral blood mononuclear cells for the in vitro detection of drug-sensitization in drug-induced maculopapular exanthems.

Adult↗

Preferential usage of TCR-Vbeta17 by peripheral and cutaneous T cells in nickel-induced contact dermatitis.

Nickel (Ni) is one of the most common contact sensitizers in man, and Ni-induced contact dermatitis is considered as a model of hapten-induced delayed type hypersensitivity. Previous studies indicated that Ni-reactive T cells derived from Ni-allergic individuals preferentially express distinct TCR-Vbeta chains. However, data on the TCR-Vbeta repertoire of Ni-responsive T cells are not consistent. Therefore, the aim of this study was to identify the TCR-Vbeta receptors of Ni-responsive peripheral and cutaneous T cells in a cohort of 17 donors with Ni-induced contact dermatitis in comparison with those of 6 healthy controls. Peripheral NiSO(4)-responsive T lymphocytes showed a significant overexpression of TCR-Vbeta17 and the frequency of TCR-Vbeta17(+) T cells correlated significantly with the in vitro reactivity of PBMC to NiSO(4). In addition, the cutaneous infiltrate of Ni-induced patch test reactions consisted primarily of Vbeta17(+) T cells. The majority of patch test-derived NiSO(4)-responsive T cells of three allergic donors were TCR-Vbeta17(+), whereas patch test-derived NiSO(4) unresponsive T cells of four additional donors did not express TCR-Vbeta17. Skin-derived Ni-responsive T cell lines from three donors uniformly secreted the Th2 cytokine, IL-5, but no IFN-gamma or IL-10. These in vitro and in vivo findings strongly suggest that T cells with a restricted TCR-Vbeta repertoire, i.e., Vbeta17, predominate in NiSO(4)-induced contact dermatitis and may be crucial in the effector phase of Ni hypersensitivity.

Cells, Cultured↗

Characterization of T cell responses to fragrances.

Fragrances are worldwide a major cause of allergic contact dermatitis (ACD), a delayed-type hypersensitivity reaction mediated by T lymphocytes. We investigated T cell responses to fragrances using peripheral blood mononuclear cells (PBMC) and T cells from skin lesions of fragrance-allergic patients. The components of a fragrance mixture (eugenol, isoeugenol, geraniol, oak moss, alpha-amyl cinnamic aldehyde, cinnamic aldehyde, cinnamic alcohol, and hydroxycitronellal) that is commonly used in the patch test were studied in vitro in the lymphocyte transformation test (LTT). PBMC from fragrance-allergic patients (n = 32) showed significant stimulations to all eight fragrances. The calculated stimulation indices (SI) varied between 2.1 and 21.8. The influence of metabolic enzymes on T cell stimulation was studied for two fragrances. Interestingly, stimulation of eugenol and isoeugenol was increased in the presence of antigen-modified human liver microsomes (CYP450) or recombinant CYP1A1 in five of seven cases. Furthermore, we established 18 T cell clones (TCC) from a skin lesion reacting specifically to eugenol. FACS analysis revealed that the majority (n = 15, 83%) of TCC were CD3(+), CD4(+), and HLA-DR(+). Seventeen percent (n = 3) of the clones were CD8(+). TCC (n = 4) released significant amounts of IL-2 and IFN-gamma but no IL-4 and IL-5. In addition, CD4(+) TCC (n = 3) showed antigen-induced cytotoxic activities against autologous B cells. In summary, we demonstrated for the first time that fragrance-specific CD4(+) and CD8(+) T lymphocytes are present in fragrance-allergic individuals. In addition, our results suggest that CYPs can be involved in the formation of the nominative antigen.

Acyclic Monoterpenes↗

Molecular features determining lymphocyte reactivity in allergic contact dermatitis to chloramphenicol and azidamphenicol.

BACKGROUND: We report on two cases of allergic contact dermatitis to chloramphenicol and azidamphenicol respectively, with in vivo and in vitro lymphocyte reactivity to both compounds. The molecular features determining lymphocyte reactivity were explored because chloramphenicol, azidamphenicol, and thiamphenicol exhibit almost identical chemical structures. METHODS: With chloramphenicol, azidamphenicol, and the chemically related thiamphenicol, we performed patch tests and lymphocyte transformation tests with both patients. Furthermore, the interleukin-5 and interferon-gamma concentrations in the cultures of peripheral blood mononuclear cells of one patient were determined. RESULTS: Patch tests showed delayed hypersensitivity reactions to chloramphenicol and azidamphenicol, but not to thiamphenicol. These results were confirmed by lymphocyte transformation tests with peripheral blood mononuclear cells of the patients, showing a proliferative T-cell response to azidamphenicol and chloramphenicol. Moreover, lymphocytes from one patient secreted large amounts of interleukin-5, but not of interferon-gamma upon coculture with azidamphenicol. CONCLUSIONS: Since lymphocyte reactivity was observed to chloramphenicol and azidamphenicol, but not to thiamphenicol, the epitope(s) recognized by the allergen-reactive T cells may be formed by the nitro-group of the benzene ring shared by chloramphenicol and azidamphenicol.

Aged↗

An improved and rapid method to construct skin equivalents from human hair follicles and fibroblasts.

To produce sufficient amounts of high quality skin equivalents (SE), either allogenic for dermatopharmacological and dermatotoxicological studies or autologous for transplantation purposes, we established a rapid, easy and cost effective three-dimensional SE model on the basis of human dermal fibroblasts, collagen and freshly plucked hair follicles. Acidic liquid collagen was polymerized with sodium hydroxide in the presence of fibroblasts to form a dermal equivalent (DE) resembling normal human dermis. At 24 h later, freshly plucked hair follicles were implanted into the surface of these DEs after cutting their bulbs off. Another 48 h later, the surface of the SEs was lifted to the air-liquid interface. Fourteen days after implantation, outgrowing keratinocytes from the outer root sheath of the hair follicles completely covered the surface of the SE and built a fully developed, multi-layered and cornified epidermis. Histology and immunofluorescence studies with specific antibodies directed against components of keratinocytes, fibroblasts, cell-adhesion molecules, different extracellular matrix and basement membrane proteins revealed the similarity of our three-dimensional SEs to the in vivo situation in normal human skin. Using autologous cell sources and cell culture media enriched with serum from the respective cell donor, it will be possible to use these SEs for autologous transplantation, thereby reducing the risk of transplant rejection.

Cell Division↗

Standard treatment: the role of antihistamines.

Histamine-1 (H1) antihistamines are the first-line drug for the treatment of urticaria. Major progress has been achieved in recent years both in the understanding of their ligands, the H1-histamine receptors, and therefore in the mechanisms of their pharmacologic effects, as well as in the development of safer antihistamines with low or no sedating effects and no interactions on the level of potassium channels leading to QT-prolongations and interactions on the level of cytochrome P450 isoenzymes. This development has brought antihistamines very close to the ideal antihistamines that are desired by clinicians to treat most types of urticaria in patients who have to take these drugs for a long time.

Cyclizine↗

In vitro drug allergy detection system incorporating human liver microsomes in chlorazepate-induced skin rash: drug-specific proliferation associated with interleukin-5 secretion.

BACKGROUND: Chlorazepate is a benzodiazepine often used for pre-operative anxiolysis. The central metabolite responsible for the pharmacological and probably for the adverse effects of most benzodiazepines, including chlorazepate, is N-desmethyldiazepam. We report a woman who developed a generalized exanthem 1 day after receiving chlorazepate and four other drugs related to anaesthesia for surgery of the larynx. Patch tests pointed to chlorazepate as the culprit drug for the skin rash. OBJECTIVES: The purpose of this study was to detect drug allergy to chlorazepate or a metabolite in vitro by means of the lymphocyte transformation test (LTT), and to determine the concentrations of the T-helper (Th) 2-type cytokine interleukin (IL)-5 and the Th1-type cytokine interferon (IFN) -gamma in the culture supernatants. METHODS: We performed an LTT with peripheral blood mononuclear cells from the patient and a control, employing human liver microsomes containing cytochrome P450 enzymes as a metabolizing system, in parallel cultures. IL-5 and IFN-gamma concentrations in the culture supernatants were assessed by enzyme-linked immunosorbent assay. RESULTS: In the LTT, no T-cell reactivity was observed to the parent compound chlorazepate, whereas coincubation of the drug with human liver microsomes yielded proliferative T-cell reactivity, which was associated with secretion of IL-5 but not of IFN-gamma. CONCLUSIONS: We conclude that addition of a metabolizing system may be advantageous for in vitro detection of T-cell reactivity to drug metabolites in the LTT.

Adult↗

Expression of multiple cytochrome p450 enzymes and multidrug resistance-associated transport proteins in human skin keratinocytes.

Cytochrome P450 enzymes metabolize various endogenous and exogenous small molecular weight compounds. Transport-associated proteins, such as P-glycoprotein, multidrug resistance-associated protein and lung resistance protein are overexpressed in drug-resistant cell lines, as well as in human tumors from various histologic origins, including malignant melanoma. Little is known about the expression and function of cytochrome enzymes and multidrug resistance-associated transport proteins in human skin; therefore, the aim of this study was to analyze the expression pattern of cytochrome enzymes and multidrug resistance-associated transport proteins in proliferating human epidermal keratinocytes under constitutive conditions and after induction with various inducers. Reverse transcription-polymerase chain reaction revealed constitutive expression of cytochromes 1A1, 1B1, 2B6, 2E1, and 3A5 in keratinocytes and showed expression of cytochrome 3A4 after incubation with dexamethasone. The expression of cytochrome 1A1 was enhanced on the mRNA level after induction with benzanthracene. Reverse transcription-polymerase chain reaction analysis of the multidrug resistance-associated transport proteins revealed constitutive expression of multidrug resistance-associated proteins 1 and 3-6, and lung resistance protein in human epithelial keratinocytes and was negative for multidrug resistance 1 and 2. Expression of 1 was seen after induction with dexamethasone. Reverse transcription-polymerase chain reaction results were confirmed by immunoblots which showed expression of cytochromes 1A1, 2B6, 2E1, and 3A, multidrug resistance-associated proteins 1, 3, and 5 as well as multidrug resistance 1 after induction with dexamethasone. Immunohistology showed positive immunofluorescence in skin specimens for cytochromes 1A1, 2B6, 2E1, and 3A and multidrug resistance-associated protein 1 and multidrug resistance 1. Constitutive activity of cytochrome 1A1, 2B, 2E1, and 3A enzymes was measured by catalytic assays. These results show that keratinocytes of the human skin express various transport-associated enzymes and detoxifying metabolic enzymes. Previous studies have revealed that cytochrome enzymes and transport-associated proteins play complementary parts in drug disposition by biotransformation (phase I) and anti-transport (phase III) and act synergistically as a drug bioavailability barrier.

ATP-Binding Cassette Transporters↗

Comparison of patch test results with a standard series among white and black racial groups.

BACKGROUND: Environmental, cultural, occupational, genetic, individual, and racial differences are important factors in the study of contact dermatitis. Some epidemiologic studies have compared overall sensitization rates among different racial groups, but similar data are lacking on individual allergens. OBJECTIVE: Determine differences in sensitization rates between 2 racial groups in North America undergoing patch testing over a period of 4 years at the Cleveland Clinic Foundation (CCF), Ohio. METHODS: Retrospective computer review of the standard screening tray results of 991 patients with an average age of 45.9 years consisting of 877 (88.5%) whites and 114 (11.5%) blacks. RESULTS: Nickel sulfate and thiomersal (both 8.0%) and nickel sulfate and p-phenylenediamine (both 10.6%) were the 2 most common sensitizers among whites and blacks respectively. There was a statistically significant difference (P =.00599) in the sensitization rate for p-phenylenediamine in blacks (10.6%) compared with whites (4.5%). There were also statistically significant differences in sensitization rates for p-phenylenediamine (21.2%; P =.00005) and imidazolidinyl urea in petrolatum (pet.) (9.1%; P =.04103) in black men compared with white men (p-phenylenediamine [4.2%] and imidazolidinyl urea [2.6% pet.]). CONCLUSION: The differences in sensitization rates, especially for p-phenylenediamine, may reflect variations in allergen exposure among racial groups or interindividual variations in the N-acetylation (N-acetyltransferase 1 [NAT1] and 2 [NAT2]) capacities of human skin for p-phenylenediamine.

Allergens↗