Pattern of decrease in %[²H₂]-dA enrichment in CD34⁺ cells. Marrow aspirates were obtained at various times after 31 to 49.5 hours of continuous [²H₂]-glucose infusion was discontinued. CD34⁺ cells selected from low-density marrow cells were processed and analyzed for enrichment of [²H₂]-dA. Bars represent the means ± SEMs. %[²H₂]-dA enrichment in CD34⁺ cells obtained from 8 donors within 24 hours and again 2 weeks after [²H₂]-glucose infusion was discontinued. Cells from 4 of those donors also were obtained at week 4. The line represents a predicted rate for decrease in %[²H₂]-dA enrichment if cells represented populations with similar turnover kinetics and was calculated from fractional replacement constants determined from the donor marrows obtained at day 0.^20,28