Failure of single-dose lecithin to alter aspects of central cholinergic activity in Alzheimer's disease

The effect of a single dose (15 g/70 kg) of lecithin (95% phosphatidylcholine) on several measures of central cholinergic activity (memory, cortisol, prolactin, pulse, blood pressure) was assessed in individuals with Alzheimer's disease. In contrast to the reported effects of physostigmine, a cholinesterase inhibitor, lecithin had no effect on these parameters, despite significant increases in plasma and erythrocyte choline.

Competition for mixed substrates by microbial populations

A model for the growth of an organism on multiple substrates was developed, assuming that each substrate has a competitive inhibition effect on the uptake of other substrates. The model was extended to examine mixed substrates, showing that the coexistence of several species at steady state in continuous cultures is possible, even when all the organisms all strongly prefer the one substrate. The diversity of nutrient sources in a real system may be a key factor in supporting a heterogeneous microbial population.