Stress using incident models

The majority of individuals exposed to trauma are resilient and do not develop PTSD. As in humans, lower mammals also have individual differences and heterogeneity of stress responses. Recent animal models of PTSD attempt to take into account this heterogeneity. Cohen et al., 2006 review two measures—performance on the elevated plus maze and acoustic startle response, used to mimic symptoms of PTSD. In their model, they differentiate animals that display stress-induced extreme behavioral responses (EBR) on both of these tests from those that display minimal behavioral responses (MBR). Different types of stress paradigms caused different proportions of EBR and MBR, similar to the suggestion in clinical literature that more severe stress increases incidence of PTSD. In Cohen s study, although stress led to an EBR immediately after the stressor in 100% of the animals, only 25% of the animals continued to show EBR 30 days following stress. 

In P. microphyllus model, callus were also subjected to conditions and elicitors in an MS-liquid medium supplemented with 2,4-D as growth regulator [54]. Different nutrient concentration, pH value, type/concentration of elicitors (histidine, threonine and methyl jasmonic acid), and osmotic and salt stress (PEG and NaCl) were evaluated. Light incidence influence was also analyzed. Pilocarpine was released in the liquid medium from callus kept in the dark. Detection was carried out using HPLC-MS/MS techniques, and pilocarpine quantification was performed by HPLC. Elicitors induced highest accumulation of the alkaloid in a time/concentration relationship. Light incidence and methyl jasmonic acid inhibited pilocarpine release to the medium. 

The systems approach seeks to identify situations or factors likely to contribute to human error. James Reason s analysis of industrial accidents revealed that catastrophic safety failures almost never result from isolated errors conunitted by individuals. Most incidents result from smaller and multiple errors in components and environments with underlying system flaws. Reason s Swiss Cheese Model describes this phenomenon. Errors made by individuals can result in disastrous consequences due to flawed systans that are represented by the holes in the cheese. Reason believed human error would happen in complex systems. Striving for perfection or punishing individuals who make errors does not appreciably improve safety. A systems approach stresses efforts to catch or anticipate human errors before they occur. Reason used the terms active errors and latent errors to distinguish individual errors from system errors. Active errors almost always involve frontline personnel. They occur at the point of contact between a human and some element of a larger system. Latent errors occur due to failures of the organization or designs that allow inevitable active errors to cause harm. The terms sharp end and blunt end correspond to active error and latent error. The systems approach provides a framework for analysis of errors and efforts to improve safety. 

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