The Journal of investigative dermatology
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Psychophysical experiments were done to test the possibility that a single receptor population signals both itch and pain by generating different patterns of activity for each type of stimulus. Electrical stimulation of hairy skin evoked pruritus in 92% of the subjects tested, and for the majority the pruritus elicited by electrical stimulation felt the same as that provoked by cowhage. ⋯ Electrical stimulation of human skin with response patterns obtained from individual cat polymodal nociceptive neurons to pain- and itch-producing stimuli caused no differences in the quality of the evoked pruritic sensations. These results do not support the idea that the same population of primary sensory neurons can produce both itch and pain by changing their pattern of discharge.
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In vitro lipogenesis was studied on the xanthoma tissue from 6 patients with normal plasma lipids and 4 patients with hyperlipidemia. Xanthoma tissue was incubated at 37 degrees C for 6 hr in Krebs-Ringer phosphate buffer containing sodium [14C]acetate. The radioactivity of each lipid class was determined after extraction and separation of lipids. ⋯ The data exemplify considerable in situ lipid synthesis of xanthoma tissue. Although the lipids in xanthomas of hyperlipidemic persons may be derived from plasma, the plasma origin of xanthoma lipids in normolipidemic persons remains to be confirmed, and the contribution of local lipogenesis cannot be ignored. The lipids in cutaneous xanthomas are most likely derived from a multiple input system.
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The distribution of basement membrane glycoproteins, fibronectin, laminin, and type IV collagen was studied in experimentally induced skin blisters in which the epidermis is separated from the dermis through the lamina lucida part of basal lamina. Fibronectin was found surrounding the blister cavity and in a primary covering formed on the bottom of the blister. ⋯ No interstitial collagens were found in the separated epidermis in accordance with previous ultrastructural evidence. These studies support the proposed role of laminin in the adhesion of epidermal cells to basement membrane collagen.
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J. Invest. Dermatol. · Sep 1981
Experimental infections in rabbits and humans with Pityrosporum orbiculare and P. ovale.
The purpose of this investigation was to produce experimental tinea versicolor in rabbits and humans with Pityrosporum orbiculare and P. ovale. P. orbiculare and P. ovale were inoculated, with and without occlusion, on the inside of the ear in 10 male rabbits and on the upper arm in 10 patients with a history of tinea versicolor, and in 3 healthy volunteers. After 1 week tinea versicolor-like lesions were produced with both P. orbiculare and P. ovale in 8 of 10 rabbits. ⋯ Microscopically short hyphae and transformation between round and oval forms were seen in both P. orbiculare and P. ovale. This investigation adds to the identity of P. orbiculare and P. ovale and also to the identity of these 2 fungi and the fungus seen in tinea versicolor. Spontaneous healing and the fact that experimental infections were produced only under occlusion illustrates the importance of predisposing factors in tinea versicolor.
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J. Invest. Dermatol. · Aug 1981
Detection of basement membrane zone antigens during epidermal wound healing in pigs.
Bullous pemphigoid (BP) antigen, laminin, and type IV collagen, 3 distinct antigens of basement membrane, were studied by indirect immunofluorescence in the epidermal-dermal junction of re-epithelializing wounds. Partial thickness wounds were made with a dermatome in the skin of white Yorkshire pigs. ⋯ In contrast, BP antigen extended from the basement membrane zone of normal skin throughout the entire epidermal-dermal junction of dermis. These results suggest that in the re-epithelization of superficial wounds laminin and type IV collagen are not present in the initial epidermal-dermal interaction of the migrating epithelium but that BP antigen may be important in this early interaction.