Many investigators have studied this problem with numerous, and often conflicting, hypotheses proposed. We have reviewed the field and discussed the pros and cons of each (1). We favor the hypothesis that "RBC senescence" and clearance from the circulation involve the unmasking of ␤-galactosyl residues due to desialylation of glycoconjugates on the RBC cell surface. This hypothesis was based on classical biochemical studies on young and old RBCs (2) and was validated at the cellular level by the use of flow cytometric procedures (3,4). Following these studies, we demonstrated with flow cytometric techniques that the densest (5) and oldest RBCs were the most

A striking relation has been shown between the increase of glutathione levels during dormancy breakage of barley seeds and the induction of germination by exogenous glutathione. These findings suggested that glutathione may play a crucial role in dormancy breakage.

The procoagulant activity (PCA) of disrupted monocytes was examined in 32 diabetic patients (26 with insulin-dependent and 6 with non-insulin-dependent diabetes) versus 30 control subjects. Diabetes monocytes exhibited a weak PCA before any incubation, associated in 10 cases with a significant amount of factor VII activity. Incubation led to a significant rise in PCA in diabetes cells, when stimulated with lipopolysaccharide or not, and in control cells only after stimulation. In incubated diabetes cells, PCA was prothrombinase-like when factor VII was associated with the freshly isolated cells, and tissue factor-like (as in the controls) when no factor VII was associated with the cells. The characteristics of PCA were not correlated with clinical features or with the type of diabetes. Our study suggests that diabetes monocytes exhibit a higher level of PCA than control ones, possibly corresponding to an in vivo stimulation, or at least a higher responsiveness to stimuli occurring in vitro.

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