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

Tyrosine hydroxylase, dopa oxidase, and peroxidase activities were studied in soluble fractions of B16 melanoma tumor homogenates by polyacrylamide gel disc electrophoresis. Stained gels were scanned photometrically and gel slices were assayed radiometrically. In these preparations, the two bands of tyrosine hydroxylating activity were completely separated from the peroxidase activity but coincided with two major bands of dopa oxidase activity. The third dopa oxidase band coincided with the single band of peroxidase activity. The soluble fraction of cultured cell homogenates had no peroxidase activity, but the two tyrosine hydroxylase bands coincided exactly with the two dopa oxidase bands. Therefore, in the soluble fraction of the murine melanoma bifunctional tyrosinase does exist as two electrophoretically separable forms which are independent of peroxidase.
J Invest Dermatol 1977 May
PMID:Characteristics of tyrosinase in B16 melanoma. 1 62

L-Tyrosine aminotransferase is present in a high speed supernatant fraction of skin homogenate of AKR/J albino and C57BL/6J black mice. The conversion of tyrosine to p-hydroxyphenylpyruvate was shown to be catalyzed by an aminotransferase by the following observations: the reaction was partially dependent on the presence of low concentrations of alpha-ketoglutarate; catalase was ineffective in increasing the yield of p-hydroxyphenylpyruvate; there was potent inhibition by typical inhibitors of pyridoxal phosphate enzymes and of rat liver tyrosine aminotransferase; there was no inhibition by inhibitors of L-amino acid oxidase; and there was no oxidation of L-leucine, the best substrate for rat kidney L-amino acid oxidase. The aminotransferase was stimulated by mercaptoethanol and was inhibited by high concentrations of alpha-ketoglutarate. The apparent Km for tyrosine was 5 X 10(-3) M and the molecular weight, determined by sucrose density gradient centrifugation, was 150-200,000. Dopa was also transaminated by the crude enzyme. No tyrosine aminotransferase could be detected in extracts of hamster melanoma.
J Invest Dermatol 1978 May
PMID:Tyrosine aminotransferase in AKR/J albino and C57BL/6J black mouse skin. 2 9

Quantitative differences in the tyrosinase activity are found at the three types of malignant melanoma of Clark and Mihm by the combined 3,4-dihydroxyphenylalanine-premelanin-reaction. Only a very small activity is present in the junction nevus. In the superficial spreading melanoma the tyrosinase activity is clear, but limited. The lentigo maligna melanoma shows an increased pigmentation. The topmost activity after incubation however is present in the nodular melanoma.
Arch Dermatol Forsch 1975
PMID:Tyrosinase activity in three types of the malignant melanoma: superficial spreading melanoma, lentigo maligna melanoma and nodular melanoma. 5 Jul 62

In split epidermal sheets with clinically normal appearance a quantitative study was carried out on dopa-positive cells in the vicinity of malignant melanomas. These data were then compared with the number of melanocytes found in the skin of the contralateral body side of the same patient. In the epidermis around superficial spreading melanoma and lentigo maligna melanoma, the number of dopa-positive cells was usually significantly higher than in the contralateral body side. On the other hand, no difference was generally found around nodular melanoma.
Arch Dermatol Forsch 1975 Jul 18
PMID:Increase of melanocytes around malignant melanoma. 5 8

The mouse melanoma B16 contains particles encapsulating high molecular weight RNA of 60--70S size associated with a reverse transcriptase. The [3H]DNA synthesized by these particles possesses homology with RNA isolated from a hamster melanoma and from three human malignant melanomas.
Arch Dermatol Res 1978 Jul 28
PMID:Particles from mouse melanoma B16 containing reverse transcriptase and 70S RNA related to human melanoma cytoplasmic RNA. 8 Jan 58

Validity of the tritiated water assay technique for tyrosine hydroxylase activity as a qualitative method was demonstrated with mushroom tyrosinase. Using this method, isolated murine melanoma "tyrosinase" (L-dopa oxidase) showed no tyrosine hydroxylase activity. This finding supports previous studies in our laboratory which used a variety of histochemical and biochemical methods. The nonenzymatic production of tritiated water caused by tritium exchange with hydrogen peroxide complicates the use of the tritiated water assay technique with crude systems, since hydrogen peroxide is generated by a variety of oxidase reactions. For this reason, previous studies using the tritiated water assay technique with crude systems are ambiguous.
J Invest Dermatol 1979 Apr
PMID:Inability to demonstrate hydroxylation of tyrosine by murine melanoma "tyrosinase" (L-DOPA oxidase), using the tritiated water assay technique. 10 47

A diffusion method is described for quantitative determination of precipitating antibodies against polysaccharide antigen from Candida albicans. It is a reversed single radial immunodiffusion method with the antigen in the gel layer. As one parameter within an immunological testing programme antibody levels were estimated in serum samples from a patient suffering from malignant melanoma.
Dermatol Monatsschr 1979 Jan
PMID:[The quantitative immunochemical determination of Candida albicans-specific antibodies (author's transl)]. 10 42

Although neurofibromatosis and cutaneous melanoma are both diseases of neuroectodermal origin, reports of their association are rare. The case history of a patient with histologically documented neurofibromatosis and a nodular melanoma unrelated to a cafe-au-lait spot or congenital nevus is reported, and the literature reviewed. The appearance of only one patient with neurofibromatosis in a series of 900 patients with melanoma suggests that these diseases are probably not associated with greater frequency than that predicted by chance alone.
Arch Dermatol 1979 Jul
PMID:Cutaneous melanoma in a patient with neurofibromatosis. 11 Feb 69

A marked cutaneous axonal dystrophy has been observed electronmicroscopically for the first time in the skin of three patients: (a) lesion of pityriasis lichenoides chronica in a patient with bronchogenic carcinoma, (b) non involved skin of a patient with malignant melanoma and (c) non involved skin of a patient with gout and retinal damage after prolonged use of chloroquine. The affected myelinated and non myelinated axons showed distinct alterations of mitochondria and multiple osmiophilic lamellated bodies (LK). These changes were interpreted as a (poly-)neuropathy, due to the influence of toxic systemic agents, such as malignant tumor and abuse of drugs. Chloroquine is known to induce neural damage. Moreover, some other compounds (ergotamine, ethaverine, analgetic preparations) may also be responsible for the drug-induced axonal dystrophy described in this study.
Arch Dermatol Res 1975 Nov 14
PMID:[Tumor- and drug-induced cutaneous axonal dystrophy. An electronmicrocopy proof of multiple lamellated bodies]. 17 47

Growth and melanization are intimately related in melanoma cells. MSH, by promoting elevated cyclic AMP levels, causes increases in melanization, cessation of growth, and gross morphologic changes in Cloudman S-91 melanoma cells. Growth inhibition results from high levels of cyclic AMP while growth stimulation occurs with lower levels. During melanization, oxidation products of tyrosine are generated which are toxic to the cells. Genetic studies have revealed that some of these processes are related through common biochemical pathways. This article reviews work of recent years on such regulatory mechanisms in melanoma.
J Invest Dermatol 1976 Apr
PMID:Factors regulating growth and pigmentation of melanoma cells. 17 4


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