144 Inflammation

15.21 DOES DEXAMETHASONE BLUNT THE SECONDARY f" JFLAMMATORY RESPONSE ASSOCIATED WITH OXIDATIVE-INDUCED LUNG INJURY? Frank Kelly, Marie Landreau, Gary Phillips, and lan Town Departments of Nutrition and Medicine 1, University of Southampton, Southampton, SO2 3DD England.

In the preterm infant with developing or established chronic lung disease (CLD), dexamethasone (dex) is widely used and has been shown to improve short term outcome. One proposed mechanism for the Improved pulmonary function with dex is decreased migration of inflammatory cells to the lung. We have investigated this hypothesis in the preterm guinea pig model of oxygen-induced lung injury.

Three day preterm guinea pig pups were delivered by Caesarian section and exposed to either 95% 02 or 21% 02 for 72 h, then maintained in room air for up to a further 96 h which we have previously shown to result in a marked inflammatory response in the lung. Subgroups of animals were given a daily sc injection of either dex (10 mg/kg) or an equivalent volume of 0.9% NaCI. Bronchoalveolar lavage (BAL) was performed at 3, 5 or 7 days after delivery. May Grunwald-Geisma stained cytospin preparations were evaluated for total and differential cell counts. BAL protein and a l - P I concentrations and elastase activity were also determined. Dex treatment significantly reduced both the total inflammatory cell and neutrophil influx to the lung at 3 and 5 days. However, neither elastase activity, protein or a l - P I concentrations were reduced at these times. These data confirm that dex can reduce the inflammatory response that follows oxygen-induced lung injury but that this may not be the mechanism by which it improves lung function in neonates with CLD.

EOSINOPHIL PEROXIDASE MEDIATED MYOCARDIAL DAMAGE John R. Mahoney, Jr. and Arne Slungaard Departments of Surgery and Medicine, University of Minnesota, Minneapolis, MN 55455 U.S.A.

Chronic blood eosinophilia occurring in parasitic infestations is often complicated by a potentially lethal cardiomyopathy characterized histologically by dense endocardial deposition of eosinophil proteins. These include eosinophil peroxidase (EPO), which unlike myeloperoxidase, preferentially oxidizes Br- rather than CI- at physiological concentrations. We hypothesized that endocardial EPO might play a role in hypereosinophilic cardiomyopathy by diverting H20 2 leaking from myocytes of this highly aerobic organ to fuel progressive oxidative destruction of the heart. To model this we used isolated working rat hearts and purified human EPO. Hypothermic cardioplegia with or without EPO (3.5 ug) was infused via the aorta, left for 3 min and flushed with warm Krebs-Henseleit perfusate. Baseline values were established for 15 min before a 20 min infusion of 1 uM H202 (cardiac output ~ 60 ml/min). RPP = rate x pressure, MVO2 = 02 consumption.

Average values after 20 rain H202 infusion. Group(n=3) Work MVO2 RPP

(kgx m/rain x g) (umol O21 g ) (ram Hgx I04 ) -EPO +Br- fl00 uM) 23+6 9.8_+ 2 2.4 +.2 +EPO +Br- 23 + 3 9.9 + .3 2.4 +.I

-EPO +H202 +Br- 25 _+11 10 + 3 2.6 _+.4 +EPO +H202 -Br- 19 +7 8.6 + 1 2.7 +.2 +EPO +H202 + Br- 0 3.2 _+ .3 0.7 +.02 There was no significant change in mechanical function in the control groups over the course of the experiment. These results show cell-adherent EPO in the presence of Br- and H202 can generate a highly cardiotoxic oxidant; this may help explain the cardiomyopathy seen with blood eosinophilia.

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15,23 OXlDATIVELY-FRAGMENTED PHOSPHATIDYLCHOLINE ACTI- VATES HUMAN NEUTROPHILS: The role of the receptor for Platelet-Activating Factor (PAF). T.M. Mclntyre, P.L. Smiley, K.E. Stremler, S.M. Prescott, and G. A. Zimmerman. CVRTI Univ of Utah, Salt Lake City UT 84112

PAF, 1-O-alkyl-2-acetyl-sn-glycero-3-phosphocholine (GPC), is a potent phospholipid mediator that activates neutrophils (PMN)

and other inflammatory cells via a receptor specific for phosphati-

dylcholines with a short sn-2 residue: neither 1-C16:0-2-C20:4-

GPC ([PA]PC) nor its phospholipid peroxide derivative signifi- cantly activated PMN. However, after air oxidation, lipid material in

the peroxide preparation activated human PMN: activation was blocked by phospholipase A 2 treatment or by a PAF receptor an- tagonist. Reversed phase HPLC showed many phospholipids more polar than [PA]PC; these activated PMN at submioromolar concentrations. This was blocked by 3 structurally unrelated PAF

receptor antagonists. GC/mass spectrometry identified 1-C16:0-

2-C3-GPC in this mixture. Synthetic 1-C16:0-2-C3-GPC activated PMN: this was blocked by PAF receptor antagonists. [PA]PC was

fragmented by ozonolysis and the resulting 1-C16:0-2-(5-oxo- valeroyl)-GPC purified by HPLC. It (or lipid products derived from it) activated PMN and this also was inhibited by PAF receptor an- tagonists. Thus, free redical-catalyzed oxidation of phosphatidyl-

choline fragmented the sn-2 polyunsaturated fatty acyl residue to yield phospholipids with residues as short as propionoyl. This, and its hornologs, activate PMN via their PAF receptor. Inflamma- tion and other sources of oxidative stress may non-enzymatically generate material that mimics the biological activities of PAF.

THERAPEUTIC EFFECT OF SUPEROXlDE DISMUTASE IN COM- BINATION WITH AN ANTIMICROBIAL AGENT ON PERITONITIS IN RATS

M.Muramoto, H.Takeyama, M.Taniguchi, T.Hayakawa, K.Katoh, S.Ishikawa, N.Shinagawa, J.Yura and R.Sinohara

First Department of Surgery, Nagoya City University Medical School, Nagoya, Japan

It is suspected that multiple organ failure due to severe infection is related to oxidative damage. To study this possi-

bility, experimental peritonitis was induced in Sprague-Dawley rats (weighing 190-240 g) with Escherichia coil NIHJ JC-2 through an intraperitoneal injection consisting of bacterial cells, BaSO4 and gastric mucin solution. Retaining one group as control (n = 206), recombinant human superoxide dismutase (SOD) and ceftizoxime (CZX) were administered simultaneously to the combination group (n = 28), while another group received only CZX (n =54). Judging survival rates by the Kaplan-Meier

curve, a significant improvement was seen between the control and CZX groups(p < 0.001) and between the CZX and combination group(p<0.05). SOD activity and lipid peroxide (LPO) levels in liver, lung and serum were assayed with the nitrite and TBA and Fe3 + TBA methods respectively, but data in each group had no significant difference. Six hours after inducing

peritonitis, ascites was sampled for measuring LPO content and prognosis was observed. LPO levels were significantly higher(p<0.01) in the dead rats than in those that survived. LPO levels affect prognosis, and the combination of SOD and CZX is effective.

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