BACKGROUND: The yield of CD34-positive cells obtained from an apheresis procedure is determined, in part, by the efficiency of collection. Optimization of the efficiency of CD34-positive peripheral blood cell collection requires identification of predictive factors. STUDY DESIGN AND METHODS: Demographic, stem cell collection, mobilization, and disease-related measures from autologous and allogeneic donors undergoing 252 progenitor cell apheresis procedures were retrospectively reviewed. Statistical relationships between CD34 collection efficiency and the various measures were determined by correlation and multiple linear regression analysis. RESULTS: CD34 collection efficiency inversely correlated with the peripheral white cell count, hematocrit, and serum albumin concentration (R2 = 0.29). White cell count was the single best predictor of CD34 efficiency (R2 = 0.19). Donor groups with cytopenias (patients vs. normal donors; increased cycles of prior chemotherapy; bone marrow involvement; chemotherapy plus growth factor mobilization) had higher collection efficiencies. Only 29 percent of the variability in the data could be attributed to white cell count, hematocrit, and albumin concentration. The majority of the remaining variability was due to unexplained differences between donors. CONCLUSION: CD34 collection efficiencies show considerable variation. Higher peripheral white cell counts, hematocrits, and/or albumin concentrations result in decreased CD34 collection efficiency, but most of the variability in the data is not accounted for by these three factors.

Adolescent↗

PubMedDate not supplied

Selectively withholding treatment from newborn babies.

Whether to withhold life-prolonging treatment from a severely handicapped newborn baby is a topical moral dilemma. Some recent prominent court cases in the UK highlight the ethical issues that have to be faced when considering such a decision.

Euthanasia, Passive↗

PubMedDate not supplied

Bioelectric potentials associated with the growing deer antler.

Bioelectric potentials associated with the developing deer antler throughout its growth cycle can be correlated with the rate of longitudinal bone growth. Electrodes were connected to a high input impediance microvoltmeter, and potentials on the surface of antlers of mature deer were measured during the antler growth cycle. The reference electrode was placed at the base of the antler, while the recording electrode was placed at the antler tip or along the antler shaft. Antler length measurements were made during the growth cycle and longitudinal growth rates were determined. Growth rates and bioelectric potentials were compared for three specified periods during the antler growth cycle. The most negative potential was recorded from the antler tip. Furthermore, electronegativity increased as the rate of growth in length increased and decreased as the rate of growth in length decreased. The potentials reached isopolarity at the end of antler growth.

Action Potentials↗

PubMedDate not supplied

Changes in the tissue distribution of glucose radiocarbon at altitude.

Explore the source record for details and available documents.

Altitude↗