Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts:   Target Concepts:
Query: UMLS:C0025202 (melanoma)
 69,561 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Fine needle aspiration biopsy cytology (ABC) has proven to be a valuable tool for diagnosis of metastatic and primary melanoma. The ABC of 28 cases was studied and the findings tabulated. Melanin can be verified by Fontana-Masson stain. Additional salient features include cell isolation, anisocytosis, multinucleation, eosinophilic nucleoli, and intranuclear inclusions. Use of all of these cytomorphologic findings will result in accurate diagnosis of melanoma by ABC.
 ...
PMID:Aspiration biopsy cytology and melanoma. 708 Nov 53

Schwann cell features were found on ultrastructural examination of a neurotropic melanoma (de novo type) of the lip. A neurotropic pattern of growth was retained in metastatic tumors in lymph nodes and lung. Melanin was not demonstrable in extra-epidermal tumor cells.
 ...
PMID:Schwann cell features in neurotropic melanoma. 730 33

Ultrastructural and histological investigations were performed on a case of generalized melanosis associated with superficial spreading melanoma. The hyperpigmentation of the general body surface, mucous membranes and nail beds was associated with deposition of melanin in macrophages in the dermis, together with some hyperactivity of epidermal melanocytes. Melanin granules were observed lying free in the stroma, suggesting pigment incontinence and phagocytosis by macrophages. Giant melanosomes were noted in melanocytes, keratinocytes and melanophages in the hyperpigmented skin. No evidence was found to suggest dissemination of individual malignant cells throughout the skin. Subcutaneous nodules of malignant melanoma were, however, present, as well as metastases to the iris, liver and to other organs.
 ...
PMID:Malignant melanoma with melanosis. Ultrastructural and histological studies. 744 Aug 12

Melanin content (percentage by weight) was determined in both pigmented and nonpigmented tissues of Syrian golden hamsters bearing Greene melanoma. Melanin content was also measured in various other melanoma models (B-16 in C57 mice, Harding-Passey in BALB/c mice, and KHDD in C3H mice) and in nine human melanomas, as well as in selected normal tissues. The purpose was to evaluate the possible efficacy of chlorpromazine, which is known to bind to melanin, as a vehicle for boron transport in neutron capture therapy. Successful therapy would depend upon selective uptake and absolute concentration of borated compounds in tumors; these parameters will in turn depend upon melanin concentration in melanomas and nonpigmented "background" tissues. Hamster whole eyes, hamster melanomas, and other well-pigmented animal melanomas were found to contain 0.3 to 0.8% melanin by weight, whereas human melanomas varied from 0.1 to 0.9% (average, 0.35%). Other tissues, with the exception of skin, were lower in content by a factor of greater than or equal to 30. Melanin pigment was extracted from tissues, and the melanin content was determined spectrophotometrically. Measurements were found to be sensitive to the presence of other proteins. Previous procedures for isolating and quantifying melanin often neglected the importance of removing proteins and other interfering nonmelanic substances.
 ...
PMID:Melanin content of hamster tissues, human tissues, and various melanomas. 744 93

Human vaginal malignant melanoma represents rare gynecological malignancies of poor prognosis. We have established a melanoma tumor line in nude mice, designated Mela-1, and have examined the histological and biological characteristics of this tumor. The Mela-1 tumor has preserved the histological, histochemical and biological characteristics of malignant melanoma even after 20 passages. Tumor cells are of epitheloid shape varying in size. An ultrastructural study revealed that the tumor cells were characterized by the presence of cells with deeply indented nuclei, and both types of melanosomes, eumelanosomes and pheomelanosomes, in various stages of maturation with vesiculo-globular bodies in the cytoplasm. Melanin analysis of the tumor indicated the Mela-1 tumor to be pheomelanic. Immunohistochemical examinations revealed that the Mela-1 cells were stained positively by melanoma-associated antibody (NKI/C3) and by antibodies for S-100 protein and vimentin, and negatively for keratin and CEA. The levels of AFP, CA125 and CEA in sera of tumor-bearing mice were within normal range. The 5-S-cysteinyldopa level in sera of tumor-bearing mice correlated well with the size of the tumor. Chromosomal analysis showed the human karyotype with great heterogeneity and a modal number of 102 chromosomes. Thus the Mela-1 tumor will be useful in establishing the biological characteristics in the search for an effective treatment of human malignant melanoma of the vagina.
 ...
PMID:Establishment and characterization of human vaginal malignant melanoma xenotransplants. 752 70

Melanin is specifically produced in melanocytes. The pathway for melanin biosynthesis is regulated by a number of melanocyte-specific proteins, including tyrosinase and tyrosinase-related protein-1 (TRP-1, b locus protein). To understand the regulation of melanogenesis, we examined tyrosinase activities, mRNA levels of tyrosinase and TRP-1, and eumelanin and pheomelanin contents in mouse B16-F1 melanoma cells after they had been treated with some melanotropic reagents. Cholera toxin, alpha-melanocyte-stimulating hormone, and dibutyryl cyclic AMP increased tyrosinase activity and stimulated eumelanin biosynthesis. These reagents elevated intracellular cAMP levels. In contrast, 12-O-tetradecanoylphorbol 13-acetate reduced tyrosinase activity and eumelanin synthesis. In all cases, the mRNA levels of tyrosinase and TRP-1 changed in parallel with tyrosinase activity and eumelanin content. TRP-1 was induced simultaneously with tyrosinase, although its inducibility was lower than that of tyrosinase. These results suggest that the expressions of tyrosinase and TRP-1 genes are coordinately regulated by melanotropic reagents through cAMP-dependent protein kinase and protein kinase C in mouse B16-F1 cells, and that their coordinate expression causes eumelanin biosynthesis.
 ...
PMID:Eumelanin biosynthesis is regulated by coordinate expression of tyrosinase and tyrosinase-related protein-1 genes. 768 98

The diversity of melanoma patterns greatly impairs the interpretation of malignant cells in effusion samples. The presence of melanin pigments greatly helps determine the histogenetic origin of the tumor, but unfortunately many cases do not exhibit this feature. We reviewed cases with a definitive diagnosis of melanoma in order to identify some useful characteristics of the morphologic examination of effusions. We also subjected the effusions to the HMB45 immunoreaction to determine the diagnostic usefulness of this monoclonal antibody. The study was performed on 21 effusion samples containing malignant cells, and the main cytologic findings were similar to those on other neoplasms except for the presence of melanin pigment. The HMB45 immunoreaction was very sensitive, confirming the diagnosis in 14 of 18 cases (77.8%). Melanin pigments seem to be useful markers for melanoma in effusions, and HMB45 can be used as an ancillary method in the differential diagnosis.
 ...
PMID:Cytologic diagnosis of melanoma in serous effusions. A morphologic and immunocytochemical study. 776 36

This report illustrates the case of a patient with a pigmented lesion on the dorsal skin of his left foot associated with a bulky homolateral inguinal mass. A metastatic melanoma was clinically suspected; therefore, the pigmented foot lesion was excised and grafted, and the groin mass was dissected. The histological examination of the foot lesion revealed a well-preserved epidermal layer, beneath which spindle cells endowed with regular nuclei yet without any atypia or mitotic figures, were present. Melanin-rich histiocytes surrounded the nerve fibers and the vessels that intermingled with such spindle cells. Under light microscopy, the sections of the inguinal lymph nodes revealed clusters of pigmented cells that looked very much like those found in the foot skin lesion. These spindle-shaped cells infiltrated the nodes' capsule and peripheral sinuses and left the inner parenchyma unaltered. The inguinal mass revealed a thick, fibrous capsule surrounding a heavily pigmented tissue rich with blue nevus cells with islands of melanophages. In the case presented here, the differential diagnosis between cellular blue nevus and nodular melanoma was mandatory. In this case report, we provide the differential diagnosis and review the criteria used for it. Further support for the diagnosis was obtained from immunohistochemical findings that were positive for S-100 protein and not for HMB-45. Wide but conservative surgery appears to be the treatment of choice for cellular blue nevus. In fact, the patient described here is still alive 5 years postoperatively. Hence, the clinical evolution of the patient's lesions can be considered benign.
 ...
PMID:Benign "metastatic" cellular blue nevus. 781 Sep 62

Melanogenesis in melanoma cells can be enhanced by psoralens in the absence of UV light. Melanin biosynthesis is regulated by a number of melanocyte-specific proteins, including tyrosinase, DOPAchrome tautomerase (DCT), and tyrosinase-related protein-1 (TRP-1, gp75). To get more insight on the molecular mechanisms involved in psoralens-induced melanogenesis, we determined tyrosinase and DCT activities as well as mRNA and protein levels of tyrosinase, DCT, and TRP-1 in S91 mouse melanoma cells treated by 5-MOP. High concentration of 5-MOP (5 x 10(-5) M) induced a time-dependent increase of tyrosinase activity and melanin content, which was correlated to an increase of both mRNA and protein levels of tyrosinase. These results demonstrate that the 5-MOP stimulation of melanogenesis is related to increased tyrosinase synthesis. In addition, 5-MOP stimulated TRP-1 synthesis and induced a dose-dependent decrease of DCT activity without any modification in the expression of the protein. We explored then the signalling pathways involved in 5-MOP-induced melanogenesis and, particularly, the role of cyclic AMP and protein kinase C (PKC). A small stimulation of cyclic AMP production was observed in presence of 5-MOP. Furthermore, 1-oleoyl-2-acetylglycerol (OAG), a PKC activator, potentiated the 5-MOP stimulation of tyrosinase activity, while calphostin, a specific PKC inhibitor, inhibited the 5-MOP induction of tyrosinase activity. Phorbol-myristate acetate (PMA), described as a strong activator of PKC, inhibited also the effect of 5-MOP when used at long term. Taken together, these results demonstrate that in murine melanoma cells 5-MOP stimulates melanogenesis by increasing activity and synthesis of tyrosinase. Tyrosinase and TRP-1 expression are coordinately regulated by 5-MOP. Furthermore, a negative correlation between melanogenesis and DCT activity was observed under 5-MOP stimulation. At least, PKA and PKC systems appear to play an important role in the melanogenic effect of 5-MOP.
 ...
PMID:Regulation of melanogenesis induced by 5-methoxypsoralen without ultraviolet light in murine melanoma cells. 785 73

Melanin synthesis is a biologic property unique to the melanocyte. It is highly elevated in malignant melanoma with the production of both eumelanin (brown/black pigment) and pheomelanin (yellow/red pigment), dihydroxyindole (DHI) and cysteinyldopa (CD), respectively, being major precursors. Melanin metabolites are often released in the urine of patients with disseminated melanoma metastasis (melanuria). To establish a better method for the detection of occult melanoma this study compares the plasma levels of a pheomelanin metabolite, 5-S-CD, and a eumelanin metabolite, 6-hydroxy-5-methoxyindole-2-carboxylic acid (6H5MI2C), in melanoma and non-melanoma patients and correlates them with tumor thickness and melanoma metastasis. We found a) that the normal plasma levels of 5-S-CD and 6H5M12C are less than 2.22 ng/ml and 1.04 ng/ml, respectively; b) that the group with the normal 6H5MI2C plasma level does not have any metastasis, whereas a normal 5-S-CD level is seen in both non-melanoma and melanoma patients with and without metastasis; c) that a high plasma 6H5MI2C level is seen in all melanoma patients with tumor thickness more than 3.0 mm regardless of the presence or absence of metastasis, whereas in thinner melanoma patients this is seen only in positive metastasis group; and d) that all melanoma patients with positive metastases showed a high plasma 6H5MI2C level (more than 1.75 ng/ml). We conclude that the measurement of plasma levels of melanin metabolites provides a method for detecting occult melanoma metastasis and estimating the prognosis of melanoma patients, plasma 6H5MI2C level being more sensitive and reliable than that of 5-S-CD, and its increased level being a high risk factor.
 ...
PMID:High plasma level of a eumelanin precursor, 6-hydroxy-5-methoxyindole-2-carboxylic acid as a prognostic marker for malignant melanoma. 815 Nov 28


<< Previous 1 2 3 4 5 6 7 8 9 10 Next >>