Molecular and Genetic Mechanisms in Melanoma Gruber, Franjo; Kaštelan, Marija; Brajac, Ines ...
Collegium antropologicum,
10/2008, Letnik:
32 - Supplement 2, Številka:
2
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Recent studies have indicated an increasing incidence of melanoma worldwide. Although UV signature mutations
are found rarely in melanoma cells, there is some evidence that intense intermittent ...exposure to sunlight can induce
melanocyte tumorigenesis, and this is also observed after UV irradiation in some animals. The purpose of this paper is to
review some of the most important mechanisms involved in the pathogenesis of this tumor. Genetic studies showed the familiar
melanoma is linked to the mutation or deletion of the suppressor gene CDKN2A, and perhaps to CDK4. Studies
showed that BRAF mutation is frequent in primary and metastatic melanoma cells but also in naevocytic nevi. This mutation
activates the RAF/MEK pathway. Exposure to UV radiation induces immunosuppression. Recent investigations
showed that chemokines, angiogenesis, metalloproteinases can play a role in the mechanism of metastasis. In spite of
these advances the initiating events are still not completely understood. In conclusion, the pathogenesis of melanoma is
very complex because numerous genetic and epigenetic factors are implicated in its development and progression, but
some of the showed mechanisms can be targets for new therapies.
The competitive sorption of phosphates and marine fulvic acids on mineral particles (sand, calcite, bentonite and hematite) has been studied under simulated estuarine conditions. Afterwards, the ...release and desorption of bound phosphates by solutions containing dissolved fulvic acids was determined. It was found out that due to the favorable sorption of fulvic acids onto minerals studied binding of phosphate was significantly decreased. Desorption experiments showed that fulvic acids, present at high concentration level, similar to that in interstitial water of an oxygenated sediment, increase phosphate desorption by 10-20%.
The removal of humic substances from aqueous solution at pH=4.8 and 6.0 and 25 °C by pure culture of Aspergillus niger has been examined. The removal of humic substances from aqueous phase was ...monitored by following the decrease in absorbance at 370 nm. COD and fungal growth were also measured. The initial concentration of humic and fulvic acids, pH and diameter of fungal pellets were found to be the most important parameters. The results suggested that decolorization of batch culture was a consequence of several processes. In the first 5 hours for pellets with diameter 1-3 mm and 10 hours for pellets with diameter 2-5 mm adsorption of humic substances was dominant. Afterwards, desorption of slightly bound humic substances and their degradation, as well as degradation of remaining humic substances in the solution, continued simultaneously through the period of 10 days.
