The dynamic character of phospholipid aggregates limits conventional structural studies to the determination of average molecular features. In order to develop more detailed descriptions of phospholipid structure for comparison with experiment, the molecular dynamics of a hydrated lysophosphatidylethanolamine (LPE) micelle, incorporating 85 LPE and 1591 water molecules, have been simulated. Comparison of the initial and equilibrated micelles shows substantial differences both in LPE hydrocarbon chain conformation and polar head-group-solvent interactions. Although these changes produce only subtle effects on the averaged structural properties of the system, the alterations in hydrocarbon chain packing and head-group solvation appear to mimic a polymorphic pretransition from a spherical toward a cylindrical micelle structure.

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Clinical symptoms are sudden chest pain, dyspnea, and, less commonly, dysphagia and hoarseness. Physically, subcutaneous air and a typical crunching sound are present.When chest pain and dyspnea are present, anxiety and panic attack are frequent. Panic disorders are often observed in anorexic patients: when chest pain and/or dyspnea or dysphagia appear, spontaneous PM should be considered. 1 At present, 20 cases of spontaneous PM have been described in the literature. [2][3][4] PM in anorexic patients is sometimes produced by selfinduced vomiting. 3 Our patient had no history of vomiting, and the thorough diagnostic procedures (thoracic computed tomographic scan, esophageal radiologic evaluation, and laryngopharyngoscopy) showed no signs of esophageal or upper airway laceration.The pathophysiologic mechanism of PM in our patient can be explained by an alveolar wall rupture, with consequent air leak into the mediastinum. The air was interestingly confined to the mediastinum only: no signs of pneumothorax were evident.PM is sometimes observed in AN: self-induced vomiting causing an esophageal laceration is frequently the cause of PM in these patients.Anorexic patients with severe malnutrition are at high risk for PM or pneumothorax. 4

ABSTRACT:It is critical to identify at-risk patients and minimize the deleterious effects of cardiopulmonary bypass (CPB) procedures in pediatric populations. The present study screened the plasma proteome of pediatric patients undergoing CPB procedures to identify potential clinical biomarkers related to tissue damage, inflammation, or other pathologies. Blood samples were collected at five different time points from 10 children undergoing a CPB procedure. Plasma was isolated and analyzed using two-dimensional differential in-gel electrophoresis and matrix-assisted laser desorption ionization time of flight mass spectrometry. Levels of differentially regulated proteins identified by two-dimensional differential in-gel electrophoresis, and related proteins were then measured in all time points and patients. As well, associated small molecules and ions were measured. The present study identified 13 proteins and protein isoforms altered in expression, including hemopexin, ceruloplasmin, inter-alpha inhibitor H4, and alpha-2-macroglobulin. Immunoblot analysis revealed significant decreases in each of these proteins during the CPB procedure. Significant changes in the levels of copper, iron, Hb, epinephrine, norepinephrine, and serotonin were observed. The potential markers of pathology (inflammation, oxidative stress) identified during this preliminary study may illuminate opportunities for preventative measures and/or treatments during and following CPB procedures in pediatric patients. (Pediatr Res 63: 638-644, 2008)A lthough cardiopulmonary bypass (CPB) methods are well optimized and mortality rates from pediatric CPB continue to decrease (1,2), surgery-related pathologies are still a major concern. In fact, changes have been observed in levels of cytokines (3), and CD antigens (4) in the blood following CPB procedures. Changes in such molecules may reflect tissue damage, inflammation, and other pathologies that could affect both the long-and short-term patient outcome. These markers of pathology are risk factors for in-hospital or post-discharge morbidity and mortality in pediatric CPB patients (5,6). A more complete catalog of the circulating changes accompanying pediatric CPB surgeries may enable better prevention and treatment of complications.Although survival with good acute outcomes after surgery is increasingly likely with pediatric CPB procedures, neurodevelopmental complications such as lower intelligence, motor deficits, and impaired language skills remain a concern (7). In addition, a higher incidence of behavioral and attention problems have been reported in these patients (8,9). Although the cause of such deficits has not been shown to result from the CPB procedure itself, it is important to identify the potential long-term effects of pediatric cardiac surgery on development.Previous studies by our laboratory have used proteomic techniques-specifically two-dimensional differential in-gel electrophoresis (2-DIGE)-to examine the proteomic profile of various tissues and body fluids (10 -12). We have p...