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Biomedical subjects

A R Verhagen

Publications and source records attributed to A R Verhagen.

At least 19 recordsLinked to original sources
PubMed1986

A new approach to the measurement of phospholipase A2 in tissue homogenates and its application to human skin.

We describe a new approach to the quantification of tissue phospholipase A2 based on the observation that the Vmax is increased by several orders of magnitude in the presence of high concentrations of dimethyl sulphoxide. The enzyme from human skin showed optimal activity at 30% dimethyl sulphoxide and pH 6-7.5, and had an absolute dependence on Ca2+ (apparent Km = 1.4 mmol/l). The relationship between reaction velocity and substrate concentration did not follow Michaelis-Menten kinetics. The enzyme was inhibited by p-bromophenacyl bromide, half-maximal inhibition occurring at 2.4 mumol/l. Surprisingly, assay of specimens of various human tissues indicated that, with the exception of pancreas, skin contained higher levels of phospholipase A2 activity than any other tissue investigated. Equally surprising was that primate skin (in particular human) seems considerably more active than that of other mammals. Speculatively, these findings may be related to the high levels of free fatty acids occurring on the skin surface.

Animals↗
PubMed1984

Atypical psoriasis of the face and hands after PUVA treatment.

In sixty patients with psoriasis, two types of lesions developed after repeated and prolonged courses of PUVA radiation. In sixteen patients, new lesions on the face resembled seborrhoeic dermatitis; in thirteen patients thick plaques on the dorsum of the hands developed insidiously over the years. There was no significant association between the two types of lesions and only the latter were dose-related. The appearance of recalcitrant psoriasis on the face and hands appears to be a complication of PUVA treatment.

Adult↗
PubMed1983

Effects of PUVA on human blood monocytes in vitro.

Adherent monolayer cultures of monocytes at two stages of maturation were exposed to long-wave ultra-violet radiation in the presence and absence of 8-methoxypsoralen. A remarkably predictable, dose-related lethal effect was seen, suggesting that mesenchymal cells in general may be sensitive to photochemotherapy (PUVA). Both monocytes and macrophages were lethally damaged with doses that may reach the dermis in the course of normal clinical therapy.

Dose-Response Relationship, Drug↗
PubMed1979

Lichenoid melanodermatitis. A clinicopathological study of fifty-one Kenyan patients with so-called tropical lichen planus.

Fifty-one Kenyan patients with variable round plaques on the exposed parts, predominantly on the face, and characterized by central hyperpigmentation with annular hypopigmented borders, are described. The clinical and histological picture showed transitions, which ranged from lichen planus and lichenoid poikilodermatous syndromes to dermatitis. This syndrome corresponds largely with (sub-)tropical or actinic lichen planus as reported from the Middle East, where emphasis has been given mainly to a part of the described spectrum of transitions. We suggest that this syndrome should be considered as one of Pinkus' regional lichenoid syndromes which represent hybrids between lichen planus and other conditions rather than as a mere variant of lichen planus.

Adolescent↗
PubMed1975

Post-inflammatory elastolysis and cutis laxa.

Post-inflammatory elastolysis and cutis laxa (Marshall, Heyl & Weber, 1966) is a skin disease in African infants which appears to be comparatively common in at least two countries. Destruction of elastic tissue and atrophy are preceded by urticarial or by annular erythematous-popular lesions and result in severe disfigurement. The clinical features are intermediate between anetoderma (macular atrophy) and acquired cutis laxa, but sufficiently typical and characteristic to constitute a distinctive syndrome, which might represent an abnormal reaction to the bite of an arthropod.

Arthropods↗