Previous studies have demonstrated that a number of membrane-active agents are capable of binding to the surface of polymorphonuclear leukocytes (PMN) resulting in an augmentation of superoxide anion and hydrogen peroxide (H2O2) production in response to soluble stimuli. It is now demonstrated that these same membrane-active agents can bind to the surface of endothelial cells and enhance their susceptibility to killing by H2O2. Membrane-active agents which are capable of synergizing with H2O2 include cationic proteins, cationic poly-amino acids, lysophosphatides and enzymes which are capable of degrading membrane phospholipids (e.g., phospholipase C, phospholipase A2 and streptolysin S). In each case, treatment of the target cells with the membrane-active agent and H2O2 produces greater damage than the sum of the damage produced by either agent separately. Since inflammatory lesions, particularly sites of bacterial infection, may contain a rich mixture of cationic substances, phospholipases and phospholipid breakdown products, these substances may contribute to the tissue damage observed at sites of inflammation by enhancing endothelial cell sensitivity to PMN-generated H2O2 as well as by augmenting the generation of H2O2 by PMNs.

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235 most resistant to atresia (5-10 g) had been developing at an intermediate and slowly declining rate which shows no sharp demarca-. tion from the growth rate of follicles in adjoining weight classes.Summary. Ovarian follicles in the laying hen were found to exhibit a differential rate of atresia following hypophysectomy which is dependent on follicle size. Atresia appeared first in the smallest of the rapidly developing follicles at 6 hours post-operatively and spread to include all mature or nearly mature follicles by 18 hours. Foll.icles weighing 5 to 10 g remained intact for as long as 24 hours.

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