RESUMO
Cancer cells exhibit higher proliferation rates than normal cells, and as a consequence, a higher nutritional demand for metabolites such as amino acids. Such cells demonstrate high expression of amino acid transporters and are significantly dependent on the external uptake of amino acids. Moreover, some types of cancer cells exhibit oncogenic mutations that render them auxotrophic to certain amino acids. This metabolic difference between tumor and normal cells has been explored for developing anticancer drugs. Enzymes capable of depleting certain amino acids in the bloodstream can be employed to inhibit the proliferation of cancer cells and promote cell death. Certain microbial enzymes, such as l-asparaginase and l-amino acid oxidases, have been studied for this purpose. In this paper, we discuss the role of l-asparaginase, the only enzyme currently used as a chemotherapeutic agent. We also review the studies on a new potential antineoplastic agent, l-lysine α-oxidase, an enzyme of l-amino acid oxidase family.
Assuntos
Aminoácido Oxirredutases , Antineoplásicos , Leucemia , Humanos , Aminoácidos/metabolismo , Antineoplásicos/uso terapêutico , Asparaginase , Leucemia/tratamento farmacológico , Leucemia/genética , Lisina , Aminoácido Oxirredutases/uso terapêuticoAssuntos
Fármacos Anti-HIV/administração & dosagem , Farmacorresistência Viral , Emtricitabina/administração & dosagem , Infecções por HIV/complicações , Vírus da Hepatite B/efeitos dos fármacos , Hepatite B Crônica/virologia , Tenofovir/administração & dosagem , Fármacos Anti-HIV/farmacologia , Coinfecção/virologia , Emtricitabina/farmacologia , Infecções por HIV/tratamento farmacológico , Vírus da Hepatite B/isolamento & purificação , Humanos , Masculino , Pessoa de Meia-Idade , Tenofovir/farmacologiaRESUMO
Diseases causing colonic ischemia may be mistaken with other causes of segmental colitis such as inflammatory bowel disease, especially in young patients. The authors present the case of a 47-year-old male with severe proctosigmoiditis. Assessment excluded infectious causes, thrombophilia and systemic vasculitis. The initial histological specimen was suggestive of inflammatory bowel disease and therapy was initiated with intravenous steroids and, at day 5, infliximab, with no response. The patient was proposed for surgery. Pathological examination of the surgical specimen revealed an idiopathic myointimal hyperplasia of mesenteric veins, a rare entity exhibiting necrotizing phlebitis with rapid progression to segmental necrosis in the rectosigmoid colon. In this paper the authors discuss the differential diagnosis of proctosigmoiditis in young ages and the approach to this exceptionally rare ischemic entity.