Neutrophil marrow release. A system analysis.

Neutrophil marrow egress is governed by several processes. The most important are cell maturation, functional behavior of marrow sinusoids and humoral or neuro-vascular factors. Neutrophil release cannot be observed directly but is reflected in the size, cellular composition and kinetics of the nonproliferating pool of granulocytopoiesis in bone marrow and of blood neutrophil pool. These experimentally determined parameters were used as the basis of a mathematical model study. The model describes two catenated compartments, the nonproliferating pool of granulocytopoiesis in marrow and the total blood granulocyte pool. Cell transit from one pool to the other was assumed to be age-dependent. It was expressed by a positive sloping sigmoidal function that defines the egress potential fo the cells that increases with cell maturation. During maturation granulocytopoietic cells develop intense motility which determines the morphology of the cells on smears. Relationship between cell motility and its morphology was defined by functions determining the age-dependent probabilities of cell fixation as metamyelocytes, band- and segmented forms, respectively. The parameters of this model could be so adjusted that all experimental data were matched within experimental errors. Thus, qualitative and quantitative information on neutrophil marrow egress was obtained for normal and pathological states of granulocytopoiesis.     

Extraction and quantification of ergosterol as a measure of fungal biomass in leaf litter

Homogenization in methanol, two hours of refluxing in methanol, and direct saponification in alcoholic KOH were equally efficient at extracting ergosterol from fungally colonized leaf litter. A 25-cm Li-Chrosphere RP18 HPLC column gave excellent resolution of ergosterol in leaf extracts. Recovery of ergosterol added to leaf powder and methylcellulose ranged between 88 and 97%, but differences among leaf species were not significant. Conditions for liquid-liquid extraction from saponified extracts are critical in ergosterol analysis. Dark storage of samples does not lead to dramatic losses of ergosterol. Extensive sample clean up before HPLC injection is nonessential.     

Combination of neutron activation analysis,tracer techniques,and biochemical methods in the investigation of selenium metabolism

Biological Trace Element Research - In several studies on rats, the metabolism of selenium was investigated. The quantitative determination of the element was carried out by instrumental neutron...