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Background: Combat-related posttraumatic stress disorder (PTSD) can be a difficult condition to treat and has been associated with serious medical and economic issues among U.S. military veterans. Distinguishing between treatment responders vs. non-responders in this population has become an important public health priority. This study was conducted to identify pre-treatment characteristics of U.S. veterans with combat-related PTSD that might contribute to favorable and unfavorable responses to high value treatments for this condition., Method: This study focused on 805 patients who completed a VHA PTSD residential program between 2000 and 2007. These patients completed the PTSD Clinical Checklist at pre-treatment, post-treatment, and a four-month follow-up assessment. Latent growth curve analysis (LCGA) was incorporated to determine trajectories of changes in PTSD across these assessments and whether several key clinical concerns for this population were associated with their treatment responses., Study Findings: LCGA indicated three distinct trajectories in PTSD outcomes and identified several clinical factors that were prospectively linked with changes in veterans' posttraumatic symptomatology. When compared to a group with high PTSD symptom severity that decreased over the program but relapsed at follow-up (41%), the near half (48.8%) of the sample with an improving trajectory had less combat exposure and superior physical/mental health. However, when compared to a minority (10.2%) with relatively low symptomatology that also remained somewhat stable, patients in the improving group were younger and also reported greater combat exposure, poorer physical/mental health status, and more problems with substance abuse before the start of treatment., Conclusions: Findings suggest that veterans are most likely to benefit from residential treatment in an intermediate range of symptoms and risk factors, including PTSD symptom severity, history of combat exposure, and comorbid issues with physical/mental health. Addressing these factors in an integrative manner could help to optimize the effectiveness of treatments of combat-related PTSD in many cases.

The toxicity of Loxosceles spider venom has been attributed to a rare enzyme, sphingomyelinase D, which transforms sphingomyelin to ceramide-1-phosphate. The bases of its inflammatory and dermonecrotic activity, however, remain unclear. In this work the effects of ceramide-1-phosphate on model membranes were studied both by in situ generation of this lipid using a recombinant sphingomyelinase D from the spider Loxosceles laeta and by pre-mixing it with sphingomyelin and cholesterol. The systems of choice were large unilamellar vesicles for bulk studies (enzyme kinetics, fluorescence spectroscopy and dynamic light scattering) and giant unilamellar vesicles for fluorescence microscopy examination using a variety of fluorescent probes. The influence of membrane lateral structure on the kinetics of enzyme activity and the consequences of enzyme activity on the structure of target membranes containing sphingomyelin were examined. The findings indicate that: 1) ceramide-1-phosphate (particularly lauroyl ceramide-1-phosphate) can be incorporated into sphingomyelin bilayers in a concentration-dependent manner and generates coexistence of liquid disordered/solid ordered domains, 2) the activity of sphingomyelinase D is clearly influenced by the supramolecular organization of its substrate in membranes and, 3) in situ ceramide-1-phosphate generation by enzymatic activity profoundly alters the lateral structure and morphology of the target membranes.