Despite hypercellular bone marrows (BM), peripheral cytopenias are the rule in patients with myelodysplastic syndromes (MDS). This study examined the roles played by cell birth and cell death rates in generating this paradox. Cell kinetics from BM biopsies of 35 MDS patients were measured using intravenous infusions of either iododeoxyuridine or bromodeoxyuridine, or both. Degree of apoptosis or programmed cell death (PCD) was estimated using in situ end-labeling of DNA directly from BM biopsies, which were simultaneously double-labeled from proliferation/PCD. MDS were found to be highly proliferative disorders with large numbers of myeloid, erythroid, and megakaryocytic cells synthesizing DNA. Median cycling time (Tc) of myeloblasts was more rapid than that of patients with acute myeloid leukemia (44.1 hr vs. 56.0 hr). Interestingly, most marrow cells of all three lineages in 32 of 34 evaluable cases were undergoing PCD. In 19 of 32 patients, greater than 75% cells were apoptotic. Surprisingly, large numbers of S-phase cells were found to be simultaneously undergoing PCD, as were stromal cells of the BM microenvironment. We conclude that the extensive apoptosis in hematopoietic cells effectively cancels the high birth rate resulting in ineffective hematopoiesis and accounting for deficient bone marrow function.
The reconstruction of full-thickness scalp defects remains a surgical challenge. Different types of reconstruction had varying success including the use of dermal regeneration template (DRT). We reviewed the surgical outcome of 30 patients who underwent application of DRT for resurfacing of full-thickness scalp defects when the pericranium was excised and the outer cortex of the calvarial bone was burred after the excision of scalp neoplasm. This was a retrospective review of 30 patients who had scalp reconstruction with DRT undertaken by the senior author between October 2004 and June 2007. The mean age of patients in our series was 63 years (37-91 years). There were 14 men and 16 women. The indications for re-excision and DRT reconstruction in 28 patients were close margins and aggressive tumor type, whereas 2 patients had a recurrence. The mean defect size was 95 cm2 (16-275 cm2). The second stage of the reconstruction occurred on postoperative day 42 (postoperative days 27-62). The mean follow-up period was 14 months. Two patients had minor complications. For both stages, the combined average operative time was 128 minutes. The use of DRT is a rung of the reconstructive ladder that deserves consideration. In our series of 30 patients who required secondary reconstruction of complex scalp defects, the use of DRT has been seen to provide safe and durable soft-tissue cover for full-thickness scalp defects. The reduced operative time and inpatient stay are desirable characteristics particularly in elderly patients with multiple comorbidities.
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