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To date there is compelling in vitro and in vivo evidence for epidermal H2O2 accumulation in vitiligo. This paper reviews the literature and presents new data on oxidative stress in the epidermal compartment of this disorder. Elevated H2O2 levels can be demonstrated in vivo in patients compared with healthy controls by utilizing Fourier-Transform Raman(More)
The lytic peptides, cecropins, were originally isolated from the haemolymph of the giant silk moth, Hyalophora cecropia and possess antibacterial and anticancer activity in vitro. This study investigated the antimicrobial activity of these peptides against human pathogens using standardised assay techniques, and the activity of cecropin B on outer and inner(More)
Patients with vitiligo accumulate millimolar levels of H(2)O(2) in their epidermis. The recycling process of (6R)-l-erythro-5,6,7,8-tetrahydrobiopterin in these patients is disrupted due to deactivation of 4a-OH-BH(4) dehydratase by H(2)O(2). The H(2)O(2) oxidation products 6- and 7-biopterin lead to the characteristic fluorescence of the affected skin upon(More)
In the human epidermis both keratinocytes and melanocytes express POMC m-RNA. Immunohistochemical studies of both cell types demonstrate significantly higher levels of alpha-MSH in melanocytes than in keratinocytes. Both cell types also hold the full capacity for de novo synthesis/recycling of the essential cofactor(More)
In Hermansky-Pudlak Syndrome (HPS) a mutation in a 79.3 kDa transmembrane protein has been shown. The function of this protein has escaped definition so far. This study unveils a defective (6R)-L-erythro-5,6,7,8-tetrahydrobiopterin (6BH4) de novo synthesis/recycling for this cofactor in HPS, where activities of the key enzyme GTP-cyclohydrolase I are in the(More)
It has been shown in vivo that patients with the depigmentation disorder vitiligo accumulate hydrogen peroxide (H(2)O(2)) accompanied by low catalase levels and high concentrations of 6- and 7-biopterin in their epidermis. Earlier it was demonstrated that epidermal 4a-OH-tetrahydrobiopterin dehydratase, an important enzyme in the recycling process of(More)
The influence of UVB irradiation on the metabolic pathway for the production of L-tyrosine from L-phenylalanine in the human epidermis has been examined in 12 healthy volunteers with photo skin types I-VI (Fitzpatrick classification). This metabolic pathway involves the induction of GTP-cyclohydrolase 1 (GTP-CH-1), the rate-limiting enzyme for de novo(More)
It has recently been shown that patients with vitiligo can accumulate epidermal hydrogen peroxide (H2O2) in association with low catalase levels. This study examined serum selenium levels and blood glutathione peroxidase activities in 61 patients and controls. The results showed high serum selenium levels in 56% of the patients. As at least one isoform of(More)
Patients with vitiligo accumulate up to 10(-3) mol/L concentrations of H(2)O(2) in their epidermis, which in turn affects many metabolic pathways in this compartment, including the synthesis and recycling of the cofactor (6R)-L-erythro-5,6,7,8-tetrahydrobiopterin (6BH(4)). De novo synthesis of 6BH(4) is dependent on the rate-limiting enzyme GTP(More)
Patients with atopic eczema have significantly higher norepinephrine levels in plasma than healthy controls. In addition, significantly higher levels of the essential cofactor (6R)-L-erythro-5,6,7,8-tetrahydrobiopterin (6BH4) were found in this patient group. Cell extracts from epidermal suction blister roofs revealed only half the normal activity of(More)