Ligation of the bronchial artery in sheep attenuates early pulmonary changes following exposure to smoke

Smoke inhalation can produce acute pulmonary edema. Previous studies have shown that the bronchial arteries are important in acute pulmonary edema occurring after inhalation of a synthetic smoke containing acrolein, a common smoke toxin. We hypothesized that inhalation of smoke from burning cotton, known to contain acrolein, would produce in sheep acute pulmonary edema that was mediated by the bronchial circulation. We reasoned that occluding the bronchial arteries would eliminate smoke-induced pulmonary edema, whereas occlusion of the pulmonary artery would not. Smoke inhalation increased lung lymph flow from baseline from 2.4 +/- 0.7 to 5.6 +/- 1.2 ml/0.5 h at 30 min (P < 0.05) to 9.1 +/- 1 ml/0.5 h at 4 h (P < 0.05). Bronchial artery ligation diminished and delayed the rise in lymph flow with baseline at 2.8 +/- 0.7 ml/0.5 h rising to 3.1 +/- 0. 8 ml/0.5 h at 30 min to 6.5 +/- 1.5 ml/0.5 h at 240 min (P < 0.05). Wet-to-dry ratio was 4.1 +/- 0.2 in control, 5.1 +/- 0.3 in smoke inhalation (P < 0.05), and 4.4 +/- 0.4 in bronchial artery ligation plus smoke-inhalation group. Smoke inhalation after occlusion of the right pulmonary artery resulted in a wet-to-dry ratio after 4 h in the right lung of 5.5 +/- 0.8 (P < 0.05 vs. control) and in the left nonoccluded lung of 5.01 +/- 0.7 (P < 0.05). Thus the bronchial arteries may be major contributors to acute pulmonary and airway edema following smoke inhalation because the edema occurs in the lung with the pulmonary artery occluded but not in the lungs with bronchial arteries ligated.

Pulmonary artery thromboendarterectomy: a comparison of two different postoperative treatment strategies

Pulmonary artery thromboendarterectomy (PTE) is a potentially curative surgical procedure for chronic thromboembolic pulmonary hypertension. It is, nevertheless, associated with considerable mortality caused by postoperative complications, such as reperfusion pulmonary edema (RPE) (i.e., pulmonary infiltrates in regions distal to vessels subjected to endarterectomy) and right heart failure (RHF). However, there are no reports about the influence of different postoperative treatment strategies on complications and mortality. Therefore, we compared two different treatment strategies. In Group I (n = 33), positive inotropic catecholamines and vasodilators were avoided during termination of cardiopulmonary bypass (CPB) and thereafter, and mechanical ventilation was performed with low tidal volumes < 8 mL/kg, duration of inspiration:duration of expiration = 3:1, and peak inspiratory pressures < 18 cm H(2)O. In Group II (n = 14), positive inotropic catecholamines and vasodilators were regularly used for termination of CPB and thereafter, and ventilation was performed with high tidal volumes (10-15 mL/kg) and peak inspiratory pressures up to 50 cm H(2)O. Hemodynamics, the incidence of RPE and RHF, duration of ventilation, morbidity, and mortality were recorded. Cardiac index was comparable before surgery (2.11 +/- 0.09 vs 2.08 +/- 0.09 L. min(-1). m(-2)) and 20 min after CPB (2.26 +/- 0.09 vs 2.60 +/- 0.20 L. min(-1). m(-2)). RPE occurred in 6.1% (Group I) versus 14.3% (Group II), and RHF was observed in 9.1% (Group I) versus 21.4% (Group II). Mortality was 9.1% (Group I) versus 21.4% (Group II). Thus, the avoidance of positive inotropic catecholamines and vasodilators in combination with nonaggressive mechanical ventilation after PTE was associated with a low incidence of RPE, RHF, duration of ventilation, and mortality after PTE.

IMPLICATIONS

The avoidance of positive inotropic catecholamines and vasodilators in combination with nonaggressive mechanical ventilation was associated with a low incidence of reperfusion pulmonary edema and/or right heart failure after pulmonary artery thromboendarterectomy.

Differential time scale of fluid and solute permeability following hypothermic lung preservation

BACKGROUND

Assessment of the quality of lung graft preservation by simple functional measures in some laboratory models may fail to detect endothelial injury. The effects of hypothermic preservation in isolation were investigated by measuring the pulmonary capillary filtration coefficient (Kf) and the albumin surface area product (PS) at various cold ischemic intervals.

METHODS

Rat lungs were flushed with University of Wisconsin solution at 4 degrees C. Following storage at 4 degrees C, lungs for Kf measurement were subjected to a change in pulmonary arterial pressure. Kf was calculated from the change in rate of weight gain as a function of hydrostatic stress. PS lungs were exposed to Tris buffered Ringer's solution containing 1125 albumin (20 microM) in an isogravimetric state. Following a vascular flush the lungs were homogenized and underwent scintillation counting. Using the Kedem-Katchalsky equation PS was calculated.

RESULTS

The Kf for the control, 4-hour, and 7-hour groups were 0.778, 1.816, 4.853 g/ cm H2O/min/100 g wet lung tissue, respectively. There was a significant increase in Kf with each time increment (P,0.01). The Kf for the 24-hour group was 5.587 g/cm H2O/min/100 g wet lung tissue; not an additional significant increase. PS for the control and 4-hour groups (0.0115 and 0.0101 cm3/g wet lung tissue/minute, respectively) were not significantly different. After 7 hours there was a significant increase to 0.171 cm3/g wet lung tissue/min. PS could not be measured after 24 hours.

CONCLUSIONS

Significant endothelial injury occurs after 4 hours of cold ischemic preservation. There is progressive injury with time. Increase in water permeability is not secondary to increase in albumin permeability.

Beneficial effects of novel nitric oxide donor (FK409) on pulmonary ischemia-reperfusion injury in rats

BACKGROUND

Nitric oxide (NO) seems to play an important role in tissue injury during reperfusion of the lung. FK409 is the first spontaneous NO donor that increases plasma guanosine 3':5'-cyclic monophosphate. It is reported that FK409 prevented myocardial infarction following occlusion and reperfusion in rat coronary arteries. In this study, we evaluated the effects of FK409 on pulmonary ischemia-reperfusion injury in an in situ warm ischemia model of rats.

METHODS

Animals were divided into 2 groups: the FK409 study group that was administered FK409 (0.4 mg/kg) before reperfusion and the control group, administered a saline vehicle only. Following a thoracotomy, the bronchus, pulmonary artery and vein were separately clamped for 1 hour. Arterial oxygen tension (PaO2), arterial oxygen saturation (SaO2), and endothelin-I (ET-I) were measured after 2 hours of reperfusion. Histologic and immunohistochemical studies were performed; polymorphonuclear neutrophils (PMNs) were counted after 2 hours of reperfusion.

RESULTS

PaO2, SaO2, ET-I after 2 hours of reperfusion and the 7-day survival rate were significantly (p < 0.05) better in the FK409 group than the control group. Histologic damage was reduced in the FK409 group compared with the control group. PMN infiltration was also significantly (p < 0.05) lower in the FK409 group than in the control group.

CONCLUSION

FK409 seems to protect against ischemia-reperfusion injury of the lung. This effect may be related to a homeostatic effect on pulmonary vascular beds and prevention of PMN sequestration.

Severe pre-eclampsia and eclampsia

The mainstay of the management of severe pre-eclampsia is early referral, stabilization of the mother with antihypertensive therapy and anticonvulsants if required, full assessment of the mother and the baby, and delivery on the best day in the best way. It is to be remembered that delivery is the long-term cure, but most women get worse after delivery and most maternal deaths occur postpartum. It is important that doctors have the training to be aware of the dangers of this condition, guidelines to follow and senior support. Lowering blood pressure has been associated with a reduction in the mortality from cerebrovascular accident and early use of antihypertensive agents is beneficial to both mother and baby. The main cause of death is now pulmonary oedema, with renal failure a rare complication. It is important that, after delivery, vigilance is maintained and fluid replacement is given with care. It is better to 'run them dry' than to give fluid replacement that may encourage pulmonary oedema. Followup is required with counselling about what has happened and the prospects of recurrence.

Role of interferon-gamma and nitric oxide in pulmonary edema and death induced by lipopolysaccharide

Mice given lipopolysaccharide (LPS) intravenously developed lung edema, which was maximum after 6 h. Tumor necrosis factor, interleukin 12 (IL-12), IL-6, and interferon-gamma (IFN-gamma) appeared in the serum, and levels of nitrogen oxide (NO) derivatives were increased in serum and bronchoalveolar fluid. Mice pretreated with neutralizing anti-IFN-gamma antibodies had lower serum levels of IFN-gamma, and fewer died. However, levels of other cytokines and NO derivatives as well as lung edema were unchanged. If IFN-gamma and LPS were given together, pulmonary edema was less, but levels of cytokines and NO derivatives in serum were raised, and the mortality was greater. IFN-gamma receptor knockout mice had more edema after LPS, but were less sensitive to the lethal effects. Treatment with anti-IL-12 antibody inhibited IFN-gamma induction and reduced mortality, but had no effect on the lung edema; exogenous IL-12 also failed to affect edema, but boosted serum cytokine levels and increased the mortality. Aminoguanidine, an inhibitor of NO synthase, protected against pulmonary edema, but did not modify the lethal effects of LPS. Clearly, in this model, early pulmonary edema and lethality are not directly related, and induced IFN-gamma has no role in causing early lung edema, but augments other events that result in death.

Sodium nitroprusside mitigates oleic acid-induced acute lung injury

BACKGROUND

Acute lung injury (ALI) is associated with pulmonary hypertension, intrapulmonary shunting, and increased microvascular permeability, leading to altered oxygenation capacity. Oleic acid (OA) creates a significant ALI that physiologically mimics human adult respiratory distress syndrome (ARDS). It has been hypothesized that pulmonary vasodilatation may improve ALI. Studies in our laboratory using this model and nitric oxide (NO) have shown that NO inhalation is detrimental and worsens the effects of OA. We studied the effect of pretreatment with a potent vasodilator, sodium nitroprusside (SNP), on ALI induced by OA in an isolated lung model. We hypothesized that pretreatment with SNP will worsen pulmonary hypertension and oxygenation in OA-induced ALI, similar to the effects seen with inhaled NO in this model.

METHODS

Rabbit heart lung blocks were isolated, flushed in vivo, harvested, immediately perfused with whole blood, and ventilated with 50% oxygen. Pulmonary artery pressure was determined every 15 seconds for 90 minutes of perfusion. Oxygenation was determined by blood gas analysis of pulmonary venous effluent at 0, 20, 40, 60, and 90 minutes after initiation of OA infusion. Four groups were studied: saline control (SC), oleic acid control (OAC; 20-minute infusion of 50% OA/ethanol into pulmonary circulation), SNP control (NPC; 10 microg/ kg/min SNP infused without subsequent OA infusion), and SNP treatment (NPRx); 10 microg/kg/min SNP infused before OA/ethanol. Pulmonary artery pressure (PAP), oxygenation (arterio-venous oxygen difference [AVO2], compliance (CPL), and wet/dry lung weight were determined.

RESULTS

No significant differences were found between the NPRx group and SC. Pretreatment with SNP eliminated the detrimental effects of OA infusion.

CONCLUSIONS

Contrary to our hypothesis, pretreatment with SNP eliminates the decrease in oxygenation and increase in lung weight, and ameliorates pulmonary hypertension in our isolated lung model of OA-induced ALI.

Pancreatitis-associated protein protects the lung from leukocyte-induced injury

BACKGROUND

Severe pancreatitis is often complicated by shock and acute lung failure. Little is known about the pathophysiologic impact of the 16.6-kD lectine, named pancreatitis-associated protein (PAP), which is expressed during pancreatitis and which reduces mortality in a rat model with severe pancreatitis. Therefore, the aim of this study was to investigate the effects of PAP on the pulmonary vasculature after leukocyte activation with N-formyl-Met-Leu-Phe (fMLP).

METHODS

The experiments were performed in buffer-perfused isolated rabbit lungs. Mean pulmonary artery pressure, weight gain, and thromboxane A2 synthesis of the lungs were monitored. PAP was obtained by affinity chromatography of pancreas juice from pancreatitic rats. The authors tested whether treatment with PAP (260 microg/l, n = 9; or 500 microg/l, n = 6) before fMLP injection (10(-6) M) influences mean pulmonary artery pressure and edema formation. Lungs that were treated only with fMLP (n = 6) served as controls. Additional experiments in which PAP was applied were performed to study whether PAP (260 microg/l, n = 3; 500 microg/l, n = 3; 1,000 microg/l, n = 3) itself effects lung vasculature.

RESULTS

Application of fMLP resulted in an increase of mean pulmonary artery pressure (+/- SD) from 8 +/- 2 mmHg up to 26 +/-13 mmHg (P < 0.01) at a flow of 150 ml/min. Pretreatment with PAP reduced the peak pressure developed after fMLP to 15 +/- 7 mmHg (PAP 260 microg/l; P < 0.05) and to 9 +/- 4 mmHg (PAP 500 microg/l), respectively. In addition, the fMLP-induced lung weight gain of 9 +/- 7 g in the controls was prevented by pretreatment with PAP after 150 min in either concentration. In parallel to the attenuated pressure increase, thromboxane A2 release was significantly suppressed in the 260-microg/l (200 +/- 220 pmol x ml(-1) x min(-1); P < 0.01) and 500-microg/l (285 +/- 70 pmol x m(-1) x min(-1); P < 0.05) PAP groups compared with controls (1,138 +/- 800 pmol x ml(-1) x mi(-1)). Treatment with PAP alone in either concentration did not induce any changes in mean pulmonary artery pressure, weight gain, or thromboxane A2 release.

CONCLUSION

Clinically relevant concentrations of PAP prevented fMLP-induced vasoconstriction and edema formation in the lung. These findings point toward a protective effect of PAP on polymorphonuclear neutrophil leukocyte-mediated lung injury.

Anti-inflammatory activity of 2-acyl-5(3)-hydroxytetrahydro-1H-pyrazole derivatives

The anti-inflammatory effects of five pyrazolidine derivatives on white mice and laboratory rats were studied using models of thermal aseptic inflammation and inflammation induced by injection of carragenin and histamine, as well as models of "cotton-ball granuloma" and epinephrine (adrenaline)-induced pulmonary edema. These effects were compared with those of the most commonly used non-steroid anti-inflammatory drugs, such as phenylbutazone (CAS 50-33-9) and diclofenac (CAS 15307-79-6). It was found that the pyrazolidine compounds studied induced a pronounced anti-inflammatory effect by inhibiting both the proliferative and exudative phases of inflammation. At the same time, as compared to natural non-steroid anti-inflammatory drugs, these compounds had a lower toxicity and induced neither gastric ulcers nor suppression of hemopoiesis.

Alpha-adrenergic blockade in preventing posttransplant edema of lung allograft

Effect of alpha-adrenergic blockers on pulmonary edema in lung transplantation was studied with a rat model of syngeneic left lung transplantation. Prior to harvesting, 0.1 mg of Prazosin or 0.4 mg of Yohimbine was given to the donor. Pulmonary and systemic hemodynamics were measured under the right pulmonary arterial occlusion (RPAO) at different time points after grafting. Wet to dry weight ratio (W/D) of all transplants was also calculated. Same procedure was conducted in rats with normal and ischemic lung and in transplanted animals without any treatments. While RPAO did not increase W/D in normal lung with a significant elevation in pulmonary arterial pressure (PAP), both these values significantly increased in transplanted lung. Transplanted animals could not tolerate RPAO 24 hours after grafting, but were tolerable later than 48 hours with elevated W/D and PAP. On the contrary, animals given Prazosin or Yohimbine were all tolerable at 24 hours postsurgery. Yohimbine significantly improved W/D. Consequently, it was demonstrated that pulmonary edema of the graft reached its peak during first 24 to 48 hours after transplantation and was alleviated by the blockade of alpha-adrenergic receptor in the graft vessel.

Implantation of the undulation pump total artificial heart in the goat

The undulation pump total artificial heart (UPTAH) was developed by using small-size continuous-flow displacement-type blood pumps (undulation pump). To clarify and improve the problems accompanied by the implantation in the chest, 14 animal experiments were performed on goats weighing 41.3-79.2 kg. The UPTAH could be implanted in the chest of all goats and was driven with a modulation pulsatile mode. The first problem was the atrial suction effect. This problem could be prevented to some extent by developing the soft disk and by improving atrial cuffs. An automatic detection and releasing of the atrial suction effect was also tried. The next problem was acute lung edema accompanied by the postural change of the animal. Development of the automatic control of left atrial pressure could prevent this problem. Small blood leakage from a pinpoint hole in the seal membrane was the next problem. Improvement of the manufacturing procedure of the membrane prevented this. With these improvements, a 10 day survival could be obtained with this unique implantable total artificial heart.

[Transfusion-related lung injury edema]

INTRODUCTION

Transfusion-related acute lung injury (TRALI) is a relatively rare but potentially severe complication of blood transfusion that should be diagnosed.

EXEGESIS

The origin of this complication is most often an immunological leucocyte conflict due to transfused plasma HLA antibodies. Prevention (anti-HLA antibody screening in blood donors and elimination of blood products from immunized donors) is discussed.

CONCLUSION

Transfusion-related acute lung injury should be suspected in transfusion-related respiratory distress, after elimination of potential pulmonary edema due to overloading. An immunologic cause should always be searched for. Leukodepletion of blood products and harmonization in blood donor selection should prevent this rare complication.

Amelioration of lung reperfusion injury by L- and E- selectin blockade

OBJECTIVE

Reperfusion injury is the main reason for early graft failure after lung transplantation. Inhibition of the adherence of polymorphonuclear leukocytes to activated endothelium by blocking L- and E-selectins (antibody EL-246) could potentially inhibit reperfusion injury.

METHODS

Reperfusion injury was induced in a left lung autotransplant model in sheep. After hilar stripping the left lung was flushed with Euro-Collins solution and preserved for 2 h in situ at 15 degrees C. After reperfusion right main bronchus and pulmonary artery were occluded leaving the animal dependent on the reperfused lung (control, n = 6). Pulmonary function was assessed by alveolo-arterial oxygen difference (AaDO2) and pulmonary vascular resistance (PVR), the chemiluminescence of isolated neutrophils, as well as the release of beta-N-acetyl-glucosaminidase (beta-NAG) served as indicator of neutrophilic activation. Extravascular lung water was an indicator for pulmonary edema formation. EL-246 group animals (n = 6) were treated additionally with 1 mg/kg BW of EL-246 given prior and during reperfusion.

RESULTS

After 3 h of reperfusion five control animals developed alveolar edema compared to one animal in the EL-246 group (P = 0.08). AaDO2 (mm Hg) was significantly higher in the control compared to the EL-246 group (510 +/- 148 vs. 214 +/- 86). PVR (dyn x s x cm(-5)) was significantly increased in the control compared to the EL-246 group (656 +/- 240 vs. 317 +/- 87). Neutrophilic activation was significantly lower in the EL-246 group. Extravascular lung water was significantly lower compared to control (6.88 +/- 1.0 vs. 13.4 +/- 2.8 g/g blood-free lung weight).

CONCLUSIONS

Treatment with EL-246 results in improved pulmonary function and less in vivo PMN activation in this experimental model. Further studies are necessary to evaluate the possible role of selectin blockade in amelioration of reperfusion injury in human lung transplantation.

Effects of exogenous surfactant on acute lung injury induced by intratracheal instillation of infant formula or human breast milk in rabbits

BACKGROUND

An animal experimental model of acute lung injury after intratracheal instillation of acidified milk products has been recently demonstrated. Exogenous administration of surfactant has proved to be successful treatment for acute lung injury induced by many causes including acid aspiration. The authors conducted this study to investigate whether exogenous surfactant can reduce the magnitude of lung damage induced in rabbits by acidified milk products.

METHODS

The lung injury was induced by intratracheal instillation of acidified human breast milk or acidified infant formula (0.8 ml/kg, pH 1.8). Thirty minutes after the insult, some animals were treated with intratracheal surfactant 100 or 200 mg/kg. Lung compliance and alveolar-to-arterial oxygen gradient were recorded during ventilation. After 4 or 12 h, the lungs were excised to determine physiologic and histologic lung damage. Albumin, interleukin-8, and eicosanoids in bronchoalveolar lavage fluid and superoxide production by neutrophils were measured.

RESULTS

The acidified milk products increased A-aD(O2)(550+/-52 and 156+/-28 mmHg; mean+/-SD at 4 h in saline solution and infant formula groups, respectively), lung wet-to-dry weight ratio (6.6+/-0.5 and 5.6 +/- 0.2), %neutrophils in bronchoalveolar lavage fluid (84+/-4% and 8+/-20%), and decreased compliance (0.76+/-0.09 and 1.90+/-0.11 ml/cm H2O). Surfactant improved these variables in a dose-dependent manner (A-aDO2 = 363+/-50 and 237+/-55 mmHg in 100-mg/kg and 200-mg/kg surfactant groups). Surfactant attenuated extensive histologic changes caused by the milk products. Superoxide production was less in rabbits receiving surfactant than in those not receiving it.

CONCLUSION

Exogenous surfactant improved physiologic, histologic, and biochemical lung injury induced by acidified milk products in a dose-dependent manner. The effectiveness of surfactant may be caused, in part, by inhibition of neutrophils' sequestration and activation. These data indicate that intratracheal instillation of surfactant may be a promising therapeutic modality in acute lung injury resulting from aspiration of acidified milk products.

Reduction of post-ischemic lung reperfusion injury by fibrinolytic activity suppression

BACKGROUND

Although extensive studies on the detailed mechanisms of ischemia-reperfusion injury have been conducted, the implication of the fibrinolytic system has not been known. To determine the role of the fibrinolytic system in ischemia-reperfusion injury, we used tranexamic acid, a synthetic specific plasmin and tissue-type plasminogen activator inhibitor, to suppress fibrinolytic activity in a rabbit lung ischemia-reperfusion model.

METHODS

New Zealand White rabbits were randomly divided into two groups: a simple ischemia group and a group injected with tranexamic acid before left hilar occlusion. After 2 hours of warm ischemia, plasma was collected from pulmonary vessels. Fibrin zymography was used to ascertain fibrinolytic activity, and enzyme-linked immunosorbent assay was used to determine soluble thrombomodulin levels as a marker for endothelial cells damage. Changes in left pulmonary function including arterial oxygen tension, peak airway pressure, and pulmonary vascular resistance were recorded during reperfusion after the 2 hours of warm ischemia.

RESULTS

Fibrinolytic activity and soluble thrombomodulin levels increased in the vessels of the ischemic lung, indicating endothelial cell injury. The increased fibrinolytic activity and the rise in soluble thrombomodulin were suppressed by the preadministration of tranexamic acid, resulting in remarkably improved pulmonary function during reperfusion. After 2 hours of reperfusion, the wet-to-dry weight ratios and histological studies showed reduced pulmonary edema in the group that had received tranexamic acid.

CONCLUSION

These findings suggest that the fibrinolytic system is involved in the onset mechanism of ischemia-reperfusion injury through induced endothelial cell damage and increased vascular permeability.

A leukocyte elastase inhibitor reduces thrombin-induced pulmonary oedema in the rat: mechanisms of action

The effect of a selective leukocyte elastase inhibitor, ICI 200,355, on thrombin-induced pulmonary oedema was studied in rats. Thrombin administration produced an increase in lung weight (P < 0.05), wet weight/ dry weight ratio (P < 0.05), and relative lung water content (P < 0.05). The lung weight increase was reduced by the elastase inhibitor in doses of 2000, 200 and 20 micrograms/kg per h (P < 0.05), but not by 2 micrograms/kg per h. A dose of 20 micrograms/ kg per h seems to be optimal, since 10-fold and 100-fold increases in dose did not further improve the effect. Free elastase activity in lung tissue was higher after thrombin infusion than in controls, but was not depleted by the elastase inhibitor in vivo (P < 0.05). This elastase activity in the lung was, however, inhibited by the elastase inhibitor in vitro, indicating that the inhibitor can block extracellular, but not intracellular elastase activity. Thrombin infusion resulted in a significant decrease in plasma elastase inhibitory capacity (P < 0.05), which was depleted by the elastase inhibitor (20 micrograms/kg per h) (P < 0.05). Myeloperoxidase activity was significantly increased in lung tissue after thrombin infusion (P < 0.05). Lung myeloperoxidase activity 5 min after thrombin infusion was not affected by the elastase inhibitor, but the inhibitor induced a further increase in myeloperoxidase as seen 90 min after thrombin infusion, indicating that the effect of this inhibitor on pulmonary oedema is not due to reduction of leukocyte infiltration in the lungs, but may partly be exerted by prevention of neutrophil destruction.

Donor and recipient treatment with the Lazaroid U-74006F do not improve post-transplant lung function in swine

OBJECTIVE

U-74006F is the only Lazaroid which is currently in clinical use. A number of experimental studies demonstrate that Lazaroids reduce ischemia/reperfusion injury in various organ systems. We evaluated the effect of U-74006F on reperfusion injury in a large animal model of lung allo-transplantation.

METHODS

Two different treatment modalities were evaluated and compared with corresponding control groups. Unilateral left lung transplantation was performed in 21 weight-matched pigs (24-31 kg). Donor lungs were flushed with 1.51 cold (1 degrees C) LPD solution and preserved for 20 h. In group I (n = 5), donor animals were pretreated with U-74006F (10 mg/ kg i.v.) 20 min before harvest. In addition U-74006F was added to the flush solution (10 mg/l). In group III (n = 6), the Lazaroid was given to the donor before flush and to the recipient before reperfusion (3 mg/kg i.v.). Group II and IV (n = 5) served as control. One hour after reperfusion, the recipient contralateral right pulmonary artery and bronchus were ligated to assess graft function only. Extravascular lung water index (EVLWI), mean pulmonary artery pressure, cardiac output, and gas exchange were assessed during a 5 h observation period. Lipid peroxidation (TBARS) and neutrophil migration (MPO activity) were measured at the end of the assessment in lung allograft tissue.

RESULTS

A significant change of TBARS concentration was shown in group III (group III 78.7+/-4.6 pmol/g vs. group IV 120.8+/-7.2 pmol/g (P = 0.0065) normal lung tissue 41.3+/-4.2 pmol/g). MPO activity was reduced in group III 3.74+/-0.25 deltaOD/mg per min vs. group IV 4.97+/-0.26 deltaOD/mg per min (P = 0.027), normal lung tissue 1.04+/-0.27 deltaOD/mg per min). Pulmonary hemodynamics and gas exchange after reperfusion did not differ between groups. In group I and III, a tendency towards a reduced EVLWI was noted.

CONCLUSION

We conclude that combined treatment of donor and recipient with U-74006F reduces free radical mediated injury in the allograft. However, this intervention did not result in a significant reduction of post-transplant lung edema or improvement of pulmonary hemodynamics. Donor pretreatment alone did not improve lung allograft reperfusion injury. These results indicate that the benefit of U-74006F is too small to consider clinical application in lung transplantation.

Radiation induced endothelial cell retraction in vitro: correlation with acute pulmonary edema

We determined the effects of low dose radiation (<200 cGy) on the cell-cell integrity of confluent monolayers of pulmonary microvascular endothelial cells (PMEC). We observed dose- and time-dependent reversible radiation induced injuries to PMEC monolayers characterized by retraction (loss of cell-cell contact) mediated by cytoskeletal F-actin reorganization. Radiation induced reorganization of F-actin microfilament stress fibers was observed > or =30 minutes post irradiation and correlated positively with loss of cell-cell integrity. Cells of irradiated monolayers recovered to form contact inhibited monolayers > or =24 hours post irradiation; concomitantly, the depolymerized microfilaments organized to their pre-irradiated state as microfilament stress fibers arrayed parallel to the boundaries of adjacent contact-inhibited cells. Previous studies by other investigators have measured slight but significant increases in mouse lung wet weight >1 day post thoracic or whole body radiation (> or =500 cGy). Little or no data is available concerning time intervals <1 day post irradiation, possibly because of the presumption that edema is mediated, at least in part, by endothelial cell death or irreversible loss of barrier permeability functions which may only arise 1 day post irradiation. However, our in vitro data suggest that loss of endothelial barrier function may occur rapidly and at low dose levels (< or =200 cGy). Therefore, we determined radiation effects on lung wet weight and observed significant increases in wet weight (standardized per dry weight or per mouse weight) in < or =5 hours post thoracic exposure to 50 200 cGy x-radiation. We suggest that a single fraction of radiation even at low dose levels used in radiotherapy, may induce pulmonary edema by a reversible loss of endothelial cell-cell integrity and permeability barrier function.

Transalveolar fluid absorption ability in rat lungs preserved with Euro-Collins solution and EP4 solution

BACKGROUND

Pulmonary reimplantation response, presenting lung edema, is a major obstacle of lung transplantation. Transalveolar fluid absorption mechanism, regulated by active transalveolar Na+ transport via Na+ channel and Na+-K+-ATPase, is considered to be essential for resolution of lung edema. We investigated the effect of lung preservation on this fluid transport mechanism.

METHODS

The rat lungs were flushed and preserved with either EP4 solution (EP4) or Euro-Collins solution (EC). First, we determined the basal transalveolar fluid movement by calculating alveolar fluid clearance (AFC) after pulmonary flushing, 24- and 72-hr preservation. Then, we assessed the effects of Na+ channel blocker, amiloride, and Na+-K+-ATPase inhibitor, ouabain, on AFC after 24-hr preservation. We further measured lung ATP content and Na+-K+-ATPase activity after 24-hr preservation to evaluate cellular metabolism and enzymatic activity during preservation.

RESULTS

We found that the lungs preserved with EC showed significantly lower AFC and less inhibitory effects of both blockers than with EP4 after 24-hr preservation. Na+-K+-ATPase activity was significantly lower with EC than with EP4, even though lung ATP content was not affected by preservation solution.

CONCLUSIONS

EP4 preservation provides a better environment for maintaining transalveolar fluid absorption mechanism than EC preservation. Therefore, lung preservation with EP4 may ensure more reliable ability in resolving pulmonary edema.

Prevention of recurrent pulmonary edema in patients with bilateral renovascular disease through renal artery stent placement

Pulmonary edema and congestive heart failure (both referred to here as PE) have been reported to be complications of bilateral renal artery stenosis or unilateral stenosis in a solitary functioning kidney (both referred to as BRAS). The goals of this study were to determine whether a history of PE was more common in patients with BRAS than in those with unilateral stenosis and a normal contralateral kidney (URAS), and whether recurrent PE could be prevented by renal artery stent placement. We evaluated 90 consecutive patients with renovascular disease who were treated with percutaneous renal artery stent placement. History and clinical follow-up were obtained through chart review and phone contact with referring physicians. Mean follow-up was 18.4 months after stent placement. Twenty-three of 56 (41%) subjects with BRAS had a history of PE before revascularization, compared with four of 34 (12%) subjects with URAS (P = .05). Twenty-five of the 27 patients with history of PE had adequate clinical follow-up. Seventeen of the 22 (77%) subjects with BRAS and history of PE had no further PE after stent placement in one or both renal arteries. The five BRAS subjects with recurrent PE after stent placement had evidence of stent thrombosis or restenosis. In contrast, only one of three (33%) URAS subjects with a history of PE remained free of PE after stent placement. We conclude that PE is a common complication of BRAS, but not of URAS. In patients with BRAS, recurrent PE can be prevented by successful stent placement in one or both renal arteries.

Prevention of rapid reperfusion-induced lung injury with prostaglandin E1 during the initial period of reperfusion

We have found that the instantaneous restoration of blood flow causes acute dysfunction and massive edema in rat lungs after 4 hours of room temperature ischemia. This is associated with an early increase in pulmonary artery pressure (Ppa) and can be prevented by a stepwise increase in flow rate during the first 10 minutes of reperfusion. The objectives of this study were to determine whether rapid reperfusion causes lung injury after hypothermic preservation, and whether this injury can be attenuated by a short-course of prostaglandin E1 (PGE1). Rat lungs were flushed preserved with low-potassium dextran solution for 12 hours at 4 degrees C and randomly divided into three groups: (1) control (no PGE1); (2) PGE1 only in the flush solution; and (3) PGE1 in both flush solution and blood perfusate during the first 10 minutes of reperfusion. Postpreservation pulmonary function was assessed in an isolated rat lung reperfusion model developed previously. We found that rapid initiation of reperfusion led to significant pulmonary dysfunction, which was attenuated by a short-course of PGE1 in the blood perfusate. The addition of PGE1 to the flush solution alone did not have such an effect. Administration of PGE1 to the blood perfusate during the first 10 minutes resulted in significant lower Ppa and airway pressure and better gas exchange. There was a positive correlation between the peak Ppa during the first 10 minutes of reperfusion and the final shunt fraction. The physical forces generated by the rapid initiation of blood reperfusion appear to induce severe injury. The first 10 minutes of reperfusion seem to be a transition phase in which mechanical factors play an important role relating to ultimate post reperfusion lung function. A short course of PGE1 may be a useful maneuver to prevent rapid reperfusion-induced lung injury.

[Effects of long-term preoperative administration of low-dose erythromycin on warm ischemia-reperfusion pulmonary injury]

The effects of long-term preoperative administration of low-dose erythromycin (EM) were experimentally examined in relation to the treatment of reperfusion disorders following pulmonary thermal ischemia. EM was administered at a dose of 100 mg/day for 1 month to adult mongrel dogs with an average weight of about 12 kg (EM group). A control group that did not receive EM was also enrolled. Using a pulmonary autograft model, collapse-thermal ischemia of the lungs was performed on each animal for 60 minutes. In the early stage of reperfusion, the following measurements were assessed: gas-exchange potency in the left lung, hemodynamics, water content, adhesion of neutrophils to vascular endothelium, and concentration of blood eicosanoids. The results for the 2 groups were then compared. In the control group, the blood level of leukotriene B4 (LTB4) increased shortly after reperfusion, neutrophils migrated toward the vascular endothelium and adhered to it, and pulmonary edema developed after 1 hour. However in the EM group, the blood level of thromboxane B2 was significantly suppressed before and after hilar stripping, and the increase in the blood LTB4 level and the migration of neutrophils shortly after reperfusion in thermal ischemia were suppressed. Eventually alleviation of pulmonary edema was indicated and significantly improved gas exchange was maintained. In conclusion, pulmonary injury during detachment of the hilum of the lung, as well as warm ischemia-reperfusion pulmonary injury, may be alleviated by preoperative administration of low-dose EM on a long-term basis.