Faculty Bibliography

Apoptosis is the primary mechanism through which most chemotherapeutic agents induce tumor cell death. The purpose of this study was to determine the extent to which blasts from children with leukemia undergo a uniform apoptotic death pathway in vivo. The expression of pro- and anti-apoptotic proteins p53, p21, MDM-2, BCL-2, BCL-X(L), BCL-X(S), and BAX, and caspase-3 activity was determined in circulating blasts collected from the peripheral blood of children with leukemia prior to, and at serial time points following chemotherapy. Culturing blasts ex vivo for 12 h assessed spontaneous apoptosis and the increment induced by chemotherapy. Baseline apoptosis varied between 3% and 29%. Twenty-four hours following chemotherapy the increase in the percentage of cells undergoing apoptosis ranged from <1% to 38%. Eleven of 20 patients who received initial treatment with a p53-dependent drug showed an increase in p53 expression. In these patients, the levels of p53 target genes were also increased. A uniform pattern of BCL-2 family protein expression was not observed and only a minority of samples showed a change that would favor apoptosis. We conclude that that the initial apoptotic response to chemotherapy in children with leukemia is variable involving both p53-dependent and p53-independent pathways

Severe congenital neutropenia (Kostmann syndrome) is a disorder that presents in the neonatal period, but predisposes to leukemia later in life. This report describes a 4-y-old female with a history of severe congenital neutropenia, who developed a clonal abnormality associated with the translocation (7;21;8) (q32;q22;q22) (AML-1/ETO). She had circulating peripheral blasts and bone marrow blast counts as high as 64% when she received recombinant granulocyte colony-stimulating factor (rG-CSF). Her marrow blasts decreased to 4-20% when rG-CSF was discontinued. Fluorescence in situ hybridization analysis was performed on bone marrow cell populations sorted by flow cytometry to determine which cell populations had the AML-1/ETO translocation. The translocation was found in mature neutrophils and blasts, but not in monocytes, lymphocytes or stem cells. CONCLUSION: These findings suggest that the translocation occurred in a neutrophil progenitor, past the point in ontogeny where monocytes and neutrophils separate. The techniques described may be useful in understanding lineage relationships and leukemogenesis in other clonal abnormalities associated with myelodysplasia and leukemia.

The advent of microarray technology undoubtedly will have great impact on the medical field during the next decade. This article discusses different genomic technologies, statistical methods for data analysis, and clinical applications of microarrays. Emphasis is devoted to integration of microarrays into the field of pediatric oncology

Initial functional closure of the ductus arteriosus normally occurs within hours after birth, with permanent closure taking several weeks. The mechanism for ductal closure has been well studied and has not been shown to include thrombus formation. We describe a normal infant found to have a thrombus originating in the ductus arteriosus that occluded the ductus and subsequently extended into the left pulmonary artery, threatening to occlude it as well. This case illustrates the importance of echocardiography in making this rare diagnosis. It also emphasizes the role of echocardiography as an effective means of following the progression or regression of such a thrombus.

Immunosuppressive therapy is commonly used in the management of autoimmune disorders. As marrow-derived lymphocytes appear to play a key role in these diseases, lymphoid ablation followed by replacement with autologous or allogeneic stem cells may be a therapeutic option. We report a 5-year-old boy with severe Evans syndrome which consists of immune thrombocytopenia and Coombs-positive hemolytic anemia. He was rendered into complete remission with marrow ablation followed by rescue with an HLA-identical sibling cord blood transplant. He unexpectedly died 9 months following transplant from acute hepatic failure of unknown etiology.