Effect of Prostaglandin E<Superscript>1</Superscript> on Leukocyte Migration

THE acute inflammatory response following many types of tissue injury involves principally an increase in vascular permeability and the migration of leukocytes towards the inflammatory focus¹. Although the complement system is known to be involved in the acute inflammatory response to allergic causes^2,3, the nature of non-immunologically induced inflammation, however, is still rather obscure. We recently reported that prostaglandin E₁ (PGE₁) increased vascular permeability in rat skin and rat cremasteric muscle to a degree and in a pattern, not unlike that produced by histamine or serotonin⁴.     

Lysosomal Fragility induced by Prostaglandin F2α

PROSTAGLANDINS have been suggested as mediators of inflammatory reactions because they increase vascular permeability^1,2, are found in inflammatory exudates³, are released during antigen-antibody reactions⁴ and have leucotactic properties⁵. For this reason and because lysosomes have been assigned an important role in the pathogenesis of diverse tissue injury reactions⁶, we have studied the effect of prostaglandins on lysosomal fragility.     

The Effect of Source—Sink Manipulations on Nitrogen Fixation in Peas

The effect on nitrogen fixation of excising leaves or pods in pea (Pisum sativum L. cv. Alaska) was determined over a 60-day period. Flower buds or their subtending leaves were removed, and C₂H₂ reduction, H₂ evolution and N accumulation were measured at weekly intervals. Highest percentage nitrogen content in all treatments coincided with time of maximal C₂H₂-reduction rates. Nitrogen fixation, calculated from C₂H₂ reduction and H₂- evolution data, was significantly lower in the partially defoliated and generally higher in the depodded plants than in the controls. Total N accumulation was greatest in the depodded plants and least in the defoliated ones. Percentage nitrogen content and N₂-fixation rates in the depodded plants were maximized approximately 10 days later than in the defoliated or control plants. The absolute rates of C₂H₂ reduction and H₂ evolution were significantly altered by plant organ removal, but the relative rates were proportional. As a result the ratios of H₂/C₂H₄ production and the related relative efficiency of N₂ fixation in the treatments were not significantly different from the controls.