44 research outputs found
Malignant melanoma arising from a perianal fistula and harbouring a BRAF gene mutation: a case report
<p>Abstract</p> <p>Background</p> <p>Melanoma of the anal region is a very uncommon disease, accounting for only 0.2-0.3% of all melanoma cases. Mutations of the <it>BRAF </it>gene are usually absent in melanomas occurring in this region as well as in other sun-protected regions. The development of a tumour in a longstanding perianal fistula is also extremely rare. More frequent is the case of a tumour presenting as a fistula, that is, the fistula being a consequence of the cancerous process, although we have found only two cases of fistula-generating melanomas reported in the literature.</p> <p>Case Presentation</p> <p>Here we report the case of a 38-year-old male who presented with a perianal fistula of four years of evolution. Histopathological examination of the fistulous tract confirmed the presence of malignant melanoma. Due to the small size and the central location of the melanoma inside the fistulous tract, we believe the melanoma reported here developed in the epithelium of the fistula once the latter was already formed. Resected sentinel lymph nodes were negative and the patient, after going through a wide local excision, remains disease-free nine years after diagnosis. DNA obtained from melanoma tissue was analysed by automated direct sequencing and the <it>V600E </it>(<it>T1799A</it>) mutation was detected in exon 15 of the <it>BRAF </it>gene.</p> <p>Conclusion</p> <p>Since fistulae experience persistent inflammation, the fact that this melanoma harbours a <it>BRAF </it>mutation strengthens the view that oxidative stress caused by inflammatory processes plays an important role in the genesis of <it>BRAF </it>gene mutations.</p
Biochar: pyrogenic carbon for agricultural use: a critical review.
O biocarvĂŁo (biomassa carbonizada para uso agrĂcola) tem sido usado como condicionador do solo em todo o mundo, e essa tecnologia Ă© de especial interesse para o Brasil, uma vez que tanto a ?inspiração?, que veio das Terras Pretas de ĂŤndios da AmazĂ´nia, como o fato de o Brasil ser o maior produtor mundial de carvĂŁo vegetal, com a geração de importante quantidade de resĂduos na forma de finos de carvĂŁo e diversas biomassas residuais, principalmente da agroindĂşstria, como bagaço de cana, resĂduos das indĂşstrias de madeira, papel e celulose, biocombustĂveis, lodo de esgoto etc. Na Ăşltima dĂ©cada, diversos estudos com biocarvĂŁo tĂŞm sido realizados e atualmente uma vasta literatura e excelentes revisões estĂŁo disponĂveis. Objetivou-se aqui nĂŁo fazer uma revisĂŁo bibliográfica exaustiva, mas sim uma revisĂŁo crĂtica para apontar alguns destaques na pesquisa sobre biochar. Para isso, foram selecionados alguns temaschave considerados crĂticos e relevantes e fez-se um ?condensado? da literatura pertinente, mais para orientar as pesquisas e tendĂŞncias do que um mero olhar para o passad