children with acute myeloid leukaemia (AML) were treated in the MRC AML 10 trial. Three risk groups were identified based on cytogenetics and response to treatment. One hundred and twenty-five children relapsed -103 in the bone marrow only, 12 in the bone marrow combined with other sites, and six had isolated extramedullary relapses (site was not known in four cases). Eighty-seven children received further combination chemotherapy, one all-trans retinoic acid for acute promyelocytic leukaemia, and one a matched unrelated donor allograft in relapse, and 61 achieved a second remission. One patient with no details on reinduction therapy also achieved second remission. Treatment in second remission varied -44 children received a BMT (22 autografts, 12 matched unrelated donor allografts, 10 family donor allografts), and 17 were treated with chemotherapy alone. The overall survival rate for all children (treated and untreated) was 24% at 3 years, with a disease-free survival of 44% for those achieving a second remission. Length of first remission was the most important factor affecting response rates -children with a first remission of less than 1 year fared poorly (second remission rate 36%, 3 year survival 11%), whereas those with longer first remissions had a higher response rate (second remission rate 75%, 3 year survival 49%, P Ͻ 0.0001).

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Dual-energy X-ray absorptiometry (DEXA) is a rapid and precise technique for the assessment of bone mineralization in children. Interpretation of the results in growing children is complex as results are influenced by age, body size (height and weight) and puberty. Conventionally, bone mineral data derived from DEXA have been presented as an areal density [BMD; bone mineral content (BMC, g)/projected bone area (BA, cm2)], yet this fails to account for changes in BMC that result from changes in age, body size or pubertal development. Measurement of BMC and BA of the whole body, lumbar spine and left hip were made in 58 healthy boys and girls using DEXA. The relationship between BMC and BA was curvilinear, with the best fit being that of a power model (BMD = BMC/BAlambda, where lambda is the exponent to which BA is raised in order to remove its influence on BMC). The value of lambda changed when measures of body size and puberty were taken into account (e.g. for lumbar spine from 1.66 to 1.49). Predictive formulae for BMC were produced using regression analysis and based on the variables of age, body size and pubertal development. This provides a method for interpreting the measured BMC which is independent of such variables and a constant reference range for children aged 6-18 y.

B cell reconstitution after bone marrow transplantation is slow in patients with chronic graft-vs.-host disease (cGVHD). Could this be secondary to decreased production of B cells in the bone marrow? We determined the relative amount of B cell precursors in the marrow of 26 patients at approximately 1 year after marrow transplant (10 patients with and 16 patients without clinical cGVHD) and 8 normal adult controls. In the controls (median), 3.1% of all marrow mononuclear cells were B cell precursors. The patients without cGVHD tended to have higher than normal percents of B cell precursors (median 6.5%; the difference from normal adults was not significant). In contrast, the patients with cGVHD had barely detectable B cell precursors (median 0.2%; the difference from normal adults was significant, P = 0.004). Therefore, delayed reconstitution of B cells in patients with cGVHD appears to be due at least in part to decreased B cell production by the marrow.