RESUMO
The generation of different cell types from stem cells containing identical genetic information and their organization into tissues and organs during development is a highly complex process that requires defined transcriptional programs. Maintenance of such programs is epigenetically regulated and the factors involved in these processes are often essential for development. The activities required for cell-fate decisions are frequently deregulated in human tumors, and the elucidation of the molecular mechanisms that regulate these processes is therefore important for understanding both developmental processes and tumorigenesis.
Assuntos
Diferenciação Celular/genética , Diferenciação Celular/fisiologia , Histona-Lisina N-Metiltransferase/metabolismo , Oxirredutases N-Desmetilantes/metabolismo , Células-Tronco/citologia , Células-Tronco/enzimologia , Animais , Metilação de DNA , Epigênese Genética , Regulação da Expressão Gênica no Desenvolvimento , Histona Metiltransferases , Histona-Lisina N-Metiltransferase/genética , Histonas/metabolismo , Humanos , Modelos Biológicos , Oxirredutases N-Desmetilantes/genética , Proteínas do Grupo Polycomb , Proteínas Repressoras/genética , Proteínas Repressoras/metabolismo , Transcrição GênicaRESUMO
BACKGROUND AND PURPOSE: Children with acute lymphoblastic leukemia are treated with intensive chemotherapy resulting in profound immuno suppression. Therefore treatment with trimethoprim-sulfamethoxazole (TMP-SMX) may be used for prophylaxis against infections both with bacteria and Pneumocystis carinii in some departments. The use of TMP-SMX for prophylaxis during the induction therapy is not uniform in the four departments of pediatric oncology in Denmark. This gave us the opportunity to describe the effect of TMP/SMX on bacterial infections in children with ALL during the induction therapy. MATERIAL AND METHODS: Between January 1st 1992 and December 31st 1997, 210 children were diagnosed with ALL in Denmark. Based on a retrospective review of the medical charts the number of children with fever (>38 degrees C), the number of febrile days, days of antibiotic treatment and the number of positive blood cultures were registered for every febrile episode. RESULTS: One hundred and fourteen children received TMP/SMX prophylaxis (10-30 mg/SMX/kg/day) and 76 did not. Children who received TMP/SMX prophylaxis had significantly fewer episodes of fever (66/114 (58%) v 60/76 (79%), p <0,01), and significantly fewer children who received TMP/SMX prophylaxis had positive blood cultures before start of antibiotic treatment compared with children who did not receive prophylaxis (23/114 (20%) vs 37/76 (49%), p<0.001)). Nineteen different species were isolated from the blood stream before start of antibiotic treatment. In the non-prophylaxis group there was a preponderance of isolates with Staph. aureus, Str. pneumoniae, E. coli and P. aeruginosa. There was no difference in the mortality between the two groups (p=0.44). There were no cases of P carinii pneumonia in the period of induction therapy. CONCLUSION: TMP/SMX prophylaxis during induction therapy for childhood ALL seems to reduce the risk of bacteremias and febrile illness.