Postpneumonectomy pulmonary oedema (PPO) develops in approximately 5% of patients undergoing pneumonectomy or lobectomy, and has a high associated mortality (>50%). In its extreme form, PPO follows a clinical and histopathological course indistinguishable from acute respiratory distress syndrome. Perioperative fluid overload, impaired lymphatic drainage following node dissection and trauma caused by surgical manipulation have been implicated in the pathogenesis of PPO. However, PPO more probably represents the pulmonary manifestation of a panendothelial injury consequent upon inflammatory processes induced by the surgical procedure, which involves collapse and re-expansion of the operative lung to permit hilar dissection and pulmonary resection. High inspired oxygen concentrations are required to overcome the effects of shunt. Animal studies have shown that pulmonary ischaemia/reperfusion can result in oedema formation, possibly due to the generation of pro-oxidant forces. Moreover, plasma taken from patients undergoing lobectomy or pneumonectomy (but not lesser resections) shows evidence of oxidative damage. Such evidence suggests either that the high inspired oxygen concentrations associated with one-lung ventilation, or ischaemia/reperfusion injury, may modulate post-pneumonectomy pulmonary oedema. Mechanisms by which redox imbalance may result in tissue damage and postpneumonectomy pulmonary oedema are discussed.

Reactive oxygen (ROS) and reactive nitrogen species (RNS) produced in vivo at levels that cannot be dealt with adequately by endogenous antioxidant systems can lead to the damage of lipids, proteins, carbohydrates and nucleic acids. Oxidative modification of these molecules by toxic levels of ROS and RNS represents an extreme event that can lead to deleterious consequences such as loss of function. More recently, however, interest has focused on the formation of these species at sub-toxic levels and their potential to act as biological signal molecules. Subtoxic ROS and RNS production can lead to alterations in cellular and extracellular redox state, and it is such alterations that have been shown to signal changes in cell functions. By the use of a variety of cell types it has been shown that numerous cellular processes including gene expression can be regulated by subtle changes in redox balance Examples of this include the activation of certain nuclear transcription factors, and the determination of cellular fate by apoptosis or necrosis. Cellular redox balance is, under normal circumstances, probably under genetic control and maintained by an array of enzymatic systems that ensure that overall reducing conditions prevail. Thiols, by virtue of their ability to be reversibly oxidised, are recognised as key components involved in the maintenance of redox balance. Additionally, increasing evidence suggests that thiol groups located on various molecules act as redox sensitive switches thereby providing a common trigger for a variety of ROS and RNS mediated signalling events. In this review we discuss a number of cellular processes in which ROS and RNS have been implicated in redox signalling mechanisms. Particular attention has been paid to the importance of thiols and thiol-containing molecules in these processes.

To ascertain the influence of albumin on antioxidant status in patients with acute lung injury. Prospective, randomized, placebo-controlled study. Intensive care units, teaching hospitals. Twenty patients meeting the American European Consensus criteria for acute lung injury. Ten patients received albumin (25 g of a 25% solution every 8 hrs for a total of nine doses) and ten received placebo (normal saline administered in identical fashion and volume). All received supportive therapy appropriate for patients with acute lung injury. Plasma samples were obtained sequentially from all patients before, 30 mins after, and 4 hrs after albumin/placebo administration. Serum albumin and total protein, total antioxidant status, iron-binding antioxidant protection, iron-oxidizing antioxidant protection, lipid hydroperoxides, protein carbonyls, and plasma thiols were measured. Albumin administration increased plasma albumin concentrations (p < .05 compared with placebo) and decreased concentrations of protein carbonyls (p < .05 compared with placebo). By contrast, plasma lipid hydroperoxide concentrations were similar in both groups, both in absolute terms and relative to albumin content. For all other variables, no significant differences were apparent. For all patients, there was a positive correlation between albumin and plasma thiol concentrations (r = .983, p < .01) and albumin and antioxidant capacity (r = .885, p = .01). In the albumin treatment group, there was a strong correlation between thiols and antioxidant capacity (r = .876, p = .01). No such correlation was apparent in the placebo group. Plasma iron-binding antioxidant protection was negatively correlated (r = −.741, p < .05) with albumin content in the treatment group but not the placebo group. In patients with acute lung injury, albumin administration favorably influences plasma thiol-dependent antioxidant status as well as levels of protein oxidative damage.