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Journal ArticleDOI

Influence of the pituitary on the melanin formation in psoralene treated toad (Bufo melanostictus)

01 Jan 1965-Naturwissenschaften (Springer-Verlag)-Vol. 52, Iss: 22, pp 622-622
About: This article is published in Naturwissenschaften.The article was published on 1965-01-01. It has received 3 citations till now. The article focuses on the topics: Bufo melanostictus & Toad.
Citations
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Journal ArticleDOI
TL;DR: Tryptophan was found to participate in the pathway of melanogenesis, as a precursor as well as a positive regulator of tyrosinase, and its behavior is much more similar to the conventional substrates tyrosine and dopa.
Abstract: Since the etiology of vitiligo is still unknown, we searched for some abnormal biochemical parameters, if any, in subjects with vitiligo. Higher urinary excretion of indole metabolites in vitiliginous patients have been noted, in association with higher dioxygenase, superoxide dismutase, and tyrosine aminotransferase activity in their serum. Similar results have also been found in an animal model, Bufo melanostictus, during induced tyrosinase inhibition. Treatment with psoralen can reverse the parameters, except tyrosine aminotransferase, to a normal level. Although psoralens are not the magic bullet for the therapy of vitiligo, they are still being used as a chemotherapeutic agent against vitiligo on a major scale to date. Tryptophan was found to participate in the pathway of melanogenesis, as a precursor as well as a positive regulator of tyrosinase. Its behavior in this regard is much more similar to the conventional substrates tyrosine and dopa (dihydroxyphenylalanine). In consideration of combined participation of tyrosine and tryptophan in the synthesis of melanin and its breakdown, the possible influence of different enzymatic reactions, like mono-oxygenase, dioxygenase, and deamination, has been suggested.

49 citations

Book ChapterDOI
TL;DR: The fascinating colors in the feathers of birds, skins of reptiles and fishes and the blue eyes in animals are optical phenomena due to diffraction, light absorption and scattering, interference, that are produced by melanin granules either in combination or not, with other pigmentary colors.
Abstract: Melanins, pigments of diverse origin and chemical function, have been subjects of interest for a long time (Aristotle, in “Historia Animalia”, 315 B.C.). These natural cosmetics of skin, hair, and feathers usually occur in the form of insoluble fine granules in certain dendritic cells of the epidermis. The term melanin (μɛλαζ = black) is, however, misleading and confusing since not all biogenetically related pigments are black. The melanogenic enzyme, tyrosinase, is known to catalyze the biosynthesis of not only black but also red to brown, or even yellow pigments, e.g. pheomelanins (208, 266). On the other hand, the fascinating colors in the feathers of birds, skins of reptiles and fishes and the blue eyes in animals are optical phenomena due to diffraction, light absorption and scattering, interference, that are produced by melanin granules either in combination or not, with other pigmentary colors (94, 156) and by complex formation of the granules with heavy metals (21, 156).

7 citations

Journal ArticleDOI
TL;DR: The first experimental vitiligo responding to treatment with psoralene has been developed using Bufo melanostictus, and it is shown that the depigmentation produced by the tyrosinase inhibitors hydroquinone and catechol is counteracted by psoralenes.

5 citations

References
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Journal ArticleDOI
TL;DR: It will be shown that the pituitary gland elaborates a melanocyte-stimulating hormone (MSH) which affects melanin pigmentation in man which depends in large part upon the activity of MSH.
Abstract: IN RECENT years the relationship between hormones and the mechanism of pigmentation has come to the fore. In this report it will be shown that the pituitary gland elaborates a melanocyte-stimulating hormone (MSH) which affects melanin pigmentation in man. The “peculiar change” in skin color described by Addison in patients with adrenocortical insufficiency, the decreased pigmentation of panhypopituitarism, and the melasma of pregnancy seem to depend in large part upon the activity of MSH. Because the developments leading to this conclusion have involved many people and many aspects of research, it is worthwhile to review the historical background of this problem. In 1916 Smith and Allen, two biologists working independently, almost simultaneously reported that removal of the pituitary gland of tadpoles was followed by loss of skin color (1–4). Three years later Atwell showed that when tadpoles were immersed in pituitary extracts their skin became darker (5). Atwell, Smith, Swingle, and later Zondek found ...

139 citations

Journal ArticleDOI
23 Aug 1958-JAMA
TL;DR: Clinical studies confirmed the native lore by demonstrating that both internal administration and external application of the plant extractives, when combined with exposure to sunlight, did indeed bring about repigmentation in certain patches of vitiligo.
Abstract: It was known from the ancient folk-medicine practiced by the natives of Egypt that derivatives of the plant Ammi majus Linn could restore pigment in vitiliginous skin areas. In 1947 Fahmy and Abu-Shady 1 isolated the most active agents from extracts of this plant. They initiated clinical studies which confirmed the native lore by demonstrating that both internal administration and external application of the plant extractives, when combined with exposure to sunlight, did indeed bring about repigmentation in certain patches of vitiligo. 2 Further confirmation of these facts was soon forthcoming in Egyptian publications and in the European and American literature. 3 The most active pigmentstimulating ingredients of the plant were found to be in the group of natural furocoumarins, compounds long known to possess photosensitizing properties. Among these compounds are the oxypsoralens. A good deal of the recent work in the United States has been done with methoxsalen (Meloxine,

6 citations