Apolipoprotein E acts to increase nitric oxide production in macrophages by stimulating arginine transport

AbstractPrevious studies have shown that apolipoprotein E (apoE) plays a role in immune function by modulating tissue redox balance. Using a mouse macrophage cell line (RAW 264.7), we have examined the mechanism by which apoE regulates nitric oxide (NO) production in macrophages. ApoE potentiates NO production in immune activated RAW cells in combination with lipopolysaccharide or polyinosinic:polycytidylic acid (PIC), agents known to induce expression of inducible nitric oxide synthase mRNA and protein. The effect is not observed with apolipoprotein B or heat-inactivated apoE. The combination of PIC plus apoE produced more NO than the level expected from an additive effect of PIC and apoE alone. Furthermore, this increase was observed at submaximal extracellular arginine concentrations, suggesting that apoE altered arginine (substrate) availability. Examination of [3H]arginine uptake across the cell membrane demonstrated that arginine uptake was increased by PIC but further increased by PIC plus apoE. Treatment of RAW cells with apoE was associated with an increased apparent Vmax and decreased affinity for arginine as well as a switch in the induction of mRNA for subtypes of cationic amino acid transporters (CAT). Treatment of RAW cells with PIC plus apoE resulted in the loss of detectable CAT1 mRNA and expression of CAT2 mRNA. Regulation of arginine availability is a novel action of apoE on the regulation of macrophage function and the immune response

On the generalized stacking energy, core structure and Peierls stress of the 12⟨110⟩{110}\frac{1} {2}\left\langle {110} \right\rangle \left\{ {110} \right\} dislocations in alkali halide

Using the improved P-N theory in which the lattice discrete effect is taken into account, the core width and Peierls stress of the $\frac{1}{2}$ ⟨110⟩{110} dislocations in NaCl structure alkali halide have been investigated with the generalized stacking fault energy calculated by the ab initio calculation. The anisotropic of elasticity are taken into account while calculation the lattice discrete correction coefficient and the energy coefficient for dislocations. The discrete effect leads to a wider dislocation core in the improved P-N theory than that in the P-N theory. The obtained Peierls stress are in agreement with the existing experimental results. The predicted Peierls stress for edge dislocations in LiF and NaCl are 0.13 × 10-3μ and 0.46 × 10-3μ, respectively. The corresponding experimental values are 0.16 × 10-3μ and 0.50 × 10-3μ. It is also found that the Peierls stress and the anisotropic factor decrease with the increasing radius of the positive ion for the same negative ion in alkali halide