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Query: UMLS:C0025202 (melanoma)
 69,561 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Four cases of primary malignant melanoma of the vagina are described and discussed with respect to vaginal smears. Two cases treated with radiotherapy began to increase the amount of the melanin pigment during the course of irradiation. Characteristic cytologic features found in the four cases are summarized as follows: a) Distribution of cell 1) Scattering, no tendency of grouping 2) Moderate anisocytosis and anisokaryosis b) Cytoplasm 1) Cyanophilic wispy cytoplasm 2) Indistinct cytoplasmic rim 3) Relatively clear cytoplasm 4) Relatively low N/C ratio c) Melanin pigment 1) In melanoma cells-finely granular and diffusely packed in cytoplasm 2) In histiocytes-coarsely granular and densely packed in cytoplasm d) Nucleus 1) Extremely eccentric nucleus 2) Thin and irregular nuclear membrane 3) Relatively regular chromatin distribution 4) Finely or moderately granular chromatin pattern 5) Prominent nucleolus 6) Giant malignant cells (3-4 nuclei) 7) Intranuclear vacuole (punched out).
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PMID:Cytologic studies of malignant melanoma of the vagina. 5 32

Four cases of primary malignant melanoma of the vagina in women aged 23, 44, 51 and 65 years are presented. In these 4 cases, thorough clinical and postmortem examinations ruled out the possibility of a primary melanoma elsewhere. The primary tumors showed exophytic growth with superficial ulceration. Three of the melanomas arose from the middle third of the vagina and one from the upper third. Melanin was visible in sections stained with hematoxylin and eosin in 3 of the tumors. In the other one, the first biopsy failed to reveal melanin. However, the second biopsy performed following irradiation showed abundant melanin pigment. Electron microscopic examination of 3 tumors revealed premelanosomes and melanosomes in the tumor cells, thus confirming the diagnosis. Two neoplasms showed atypical histologic features, and only the presence of melanin enabled us to make diagnosis of malignant melanoma. One melanoma was associated with an adjacent widespread intraepithelial component of superficial spreading type indicating its probable mode of origin. All 4 patients died of widespread metastases within 13 months after initial treatment. These 4 cases, in which clinical diagnosis was confirmed by thorough autopsy, strongly indicate that malignant melanoma can arise directly from the vagina.
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PMID:Primary malignant melanoma of the vagina: study of four autopsy cases with ultrastructural findings. 36 16

A 53 year old male patient presented with a dark-brown linear pigmentation of the thumb nail due to a subungual melanoma mainly of the superficial spreading melanoma-type. Melanin-induced nail pigmentations are recommended to be treated by a resection in local anaemia of the dorsal two thirds of the terminal phalanx. This procedure combines sufficient radical surgery with a good functional and acceptable cosmetic result.
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PMID:[Subungual melanoma with linear nail pigmentation]. 68 Nov 77

Extracts of healthy and diseased skin in vitiligo, naevi and malignant melanoma were electrophoresed on polyacrylamide gel. Melanin bands were visualized on the gel by Dopa reaction. The tyrosinases found in malignant melanoma were also present in naevocellular naevi. Additional dopa melanin bands were observed. Some bands which were not related to the presence of melanocytes varied with the level of the melanogenetic activity in the individual patients.
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PMID:The tyrosinases of normal and diseased human skin (naevi, malignant melanoma, vitiligo). 81 59

Melanin granules were isolated from the Cloudman S91 mouse melanoma and from Amphiuma liver in highly purified form, as judged by electron microscopy and the lack of a mitochondrial enzyme marker. The granules from both tissues contained small amounts of DNA (less than or equal to 1% of the cell content) that was distinguished from nuclear DNA by the broadness of its buoyant density band in cesium chloride, by its sedimentation rate, and by a two-phased melting curve. The melanosome DNA could not be distinguished from nuclear and mitochondrial DNA by the amount of tritiated thymidine incorporated. The results are discussed and the suggestion made that the melanin DNA may provide the information that led to the production of the granules.
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PMID:Association of DNA with melanin granules. 115 43

The activities of mushroom and melanoma tyrosinases towards the estrogens were compared. While the fungal enzyme is capable of hydroxylating estradiol to the 2-hydroxy compound and to oxidize the latter to the quinone, the mammalian enzyme does not have this ability. With dopa as substrate and an estrogen present in the reaction mixture, both enzyme reactions yield melanin with the steroid firmly incorporated into the pigment, although with the mammalian enzyme the incorporation is small. The steroid appears to be incorporated by covalent linkage. It is suggested that the incorporation of estrogens into melanin produced by mammalian tyrosinase is via their oxidation by oxidized intermediates of the dopa to melanin transformation. Melanin itself may function as oxidant for the estrogens. Whole melanoma cells are capable of binding estrogens and incorporating small amounts into melanosomes. Similarly, fresh melanosomes in isolation can incorporate estrogens into their structure, presumably by covalent bonding to their melanin.
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PMID:Incorporation and binding of estrogens into melanin: comparison of mushroom and mammalian tyrosinases. 131 67

To optimize skin pigmentation in order to help body prevention against UV radiation, the mechanism of melanin pigment transfer from melanocytes to keratinocytes must be elucidated. Melanin transfer to keratinocytes requires specific recognition between keratinocytes and melanocytes or melanosomes. Cell surface sugar-specific receptor (membrane lectin) expression was studied in human C32 melanoma cells, an amelanotic melanoma, by flow cytometry analysis of neoglycoprotein binding as an approach to the molecular specificity. Sugar receptors on melanocytes are mainly specific for alpha-L-fucose. Their expression is enhanced upon treatment by the diacylglycerol analogue 1-oleoyl-2-acetylglycerol, which can induce melanin synthesis in amelanotic human melanoma cells in a dose-dependent manner. Flow cytometry analyses showed a small-sized population of vesicles distinguishable from large cells by their fluorescence properties upon neoglycoprotein binding. Sorting indicated that the small-sized subpopulation is composed of vesicles produced by melanocytic cells. Upon vesicle formation, a selective concentration of sugar receptors specific for 6-phospho-beta-D-galactosides appears in the resulting melanocytic vesicles. Vesicles are recognized and taken up by cultured keratinocytes and a partial inhibitory effect was obtained upon cell incubation in the presence of neoglycoproteins, indicating a possible participation of sugar receptors in this recognition. The validity for such a model to help in understanding the natural melanin transfer by melanosomes is confirmed by electron microscopy, which demonstrates the presence of melanin inside keratinocytic cells upon incubation with melanocytic vesicles.
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PMID:C32 human melanoma cell endogenous lectins: characterization and implication in vesicle-mediated melanin transfer to keratinocytes. 142 39

Clinical and experimental observations suggest that tumor-induced endothelial cell injury may be one of several initial events in the establishment of tumor metastases. To test this hypothesis, the authors have analyzed the interaction of malignant melanoma (ST-ML-12) multicenter tumor spheroids with endothelial cell monolayers in a three-dimensional coculture system. After 1.5 hours of interaction, the authors observed a toxic effect on endothelial cells in the perispheroid region. The latter was demonstrated by testing membrane integrity with the fluorescent probes acridine orange/ethidium bromide and resulted in sensitivity to shear stress of the damaged cells. The endothelium then underwent a regenerative cycle to replace the denuded halo. Addition of the oxygen radical-scavenging enzyme superoxide dismutase to the culture medium prevented this endothelial cell damage in a dose-dependent manner for up to 12 hours. By contrast, catalase, deferoxamine mesylate, allopurinol, and the proteinase inhibitors soybean trypsin inhibitor and aprotinin were not protective under the same conditions. The endothelial damage was dependent on the attachment of the spheroids. Medium conditioned by ST-ML-12-spheroids proved to be ineffective. A similar, but less prominent, deleterious effect was seen when human peritoneal mesothelial cells were used in place of the human umbilical vein endothelial cells. Spheroids of the uroepithelial cell line HU-609 were used as control. No toxicity was observed in these cocultures. Melanin biosynthesis is associated with the production of oxygen-derived free radicals. The results suggest a possible implication of these free radicals in metastasis formation of malignant melanoma.
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PMID:Interaction of human malignant melanoma (ST-ML-12) tumor spheroids with endothelial cell monolayers. Damage to endothelium by oxygen-derived free radicals. 151 67

Cultured murine B16 melanoma cells normally grow as spindle-shaped cells firmly attached to tissue culture flasks. Pellets obtained from harvested B16 melanoma cells are white to grey in color. When the same cells were grown in synthetic, serum-free AIM V medium, cellular morphology and pigmentation were radically altered. Within 3 days of subculture in AIM V, cells rounded up and grew in clusters in suspension. Melanin content increased to greater than 30 times and tyrosinase activity was found to be 10-50 times higher in cells grown in AIM V medium compared to those cultured in normal medium. A concomitant increase in the level of immunoreactive tyrosinase was also induced. The individual growth factors and hormones present in AIM V medium were examined to determine which component(s) stimulates melanogenesis. Only those cells grown in the presence of 2.5% human albumin were stimulated to synthesize melanin. These findings suggest that albumin, or a component associated with albumin, has a major effect upon the regulation of melanogenesis in these cells.
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PMID:Induction of B16 melanoma melanogenesis by a serum-free synthetic medium. 161 31

Melanin, the natural pigment found in human skin, absorbs and protects against the ultraviolet (UV) components of sunlight. Melanin production (melanogenesis) is increased by exposure to sunlight, causing a darker skin colour which is regarded as aesthetically pleasing by many humans, who therefore expose themselves to large amounts of potentially damaging sunlight. We have found that topically applied all-trans retinoic acid, a metabolic derivative of vitamin A, greatly enhances UV light-induced melanogenesis: the same preparation on its own had no effect on skin pigmentation. An orally administered retinoid, temarotene, did not have this effect. These observations were made using a lightly pigmented mouse strain, HRA: Skh-2, and confirmed in 2 human volunteers. This is the first time that metabolic derivatives of vitamin A have been shown to augment UV light-induced melanogenesis, suggesting a role for vitamin A in this process.
Melanoma Res 1992 May
PMID:Topical retinoic acid augments ultraviolet light-induced melanogenesis. 164 23


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