A Practical Guide to Rodent Islet Isolation and Assessment Revisited.

Insufficient insulin secretion is a key component of both type 1 and type 2 diabetes. Since insulin is released by the islets of Langerhans, obtaining viable and functional islets is critical for research and transplantation. The effective and efficient isolation of these small islands of endocrine cells from the sea of exocrine tissue that is the rest of the pancreas is not necessarily simple or quick. Choosing and administering the digestive enzyme, separation of the islets from acinar tissue, and culture of islets are all things that must be considered. The purpose of this review is to provide a history of the development of islet isolation procedures and to serve as a practical guide to rodent islet research for newcomers to islet biology. We discuss key elements of mouse islet isolation including choosing collagenase, the digestion process, purification of islets using a density gradient, and islet culture conditions. In addition, this paper reviews techniques for assessing islet viability and function such as visual assessment, glucose-stimulated insulin secretion and intracellular calcium measurements. A detailed protocol is provided that describes a common method our laboratory uses to obtain viable and functional mouse islets for in vitro study. This review thus provides a strong foundation for successful procurement and purification of high-quality mouse islets for research purposes.

Isolation and Assessment of Pancreatic Islets Versus Dispersed Beta Cells: A Straightforward Approach to Examine Cell-Cell Communication.

Islets of Langerhans, found in the pancreas, are microorgans essential for glucose homeostasis within the body. Many cells are found with an islet, such as beta cells (~70%), alpha cells (~20%), delta cells (~5%), F cells (~4%), and epsilon cells (1%), each with its own unique function. To better understand the roles of these cells and how cell communication alters their function, several techniques have been established such as islet isolation and beta cell dispersion. Here we describe how to isolate primary rodent islets, disperse pancreatic islets, measure intracellular calcium, and use immunofluorescent staining to distinguish beta cells and alpha cells.

Empirical limits for the forensic assessment of PTSD litigants.

This paper discusses the limits of expert opinion on posttraumatic stress disorder (PTSD) in personal injury claims. The construct of PTSD is hampered by several empirical limitations. Multiple reliable measures of PTSD exist, but have not been evaluated sufficiently within litigating samples and are infrequently used by forensic assessors. Common methods for trauma screening appear insensitive. Opinions about causation of PTSD and disability are complicated by retrospective memory biases, as well as the failure of most anxiety disorders to be detected within primary medical care. PTSD appears to have a steep spontaneous remission curve during the first year, but at least 10% of trauma-exposed people suffer chronic distress. Little is known about the course beyond 1 year. Efficacious psychological treatments have been developed for PTSD, but are not in common use limiting claimants' access to rehabilitative treatments. Research on functional disability associated with PTSD is in its infancy, but it seems likely that PTSD will account for only a part of the variance in work disability. We provide suggestions for improving forensic practice, advising the courts about the limitations of forensic opinions, and necessary research.