"Sticki-ER": Functions of the Platelet Endoplasmic Reticulum.

Significance: The primary role of platelets is to generate a thrombus by platelet activation. Platelet activation relies on calcium mobilization from the endoplasmic reticulum (ER). ER resident proteins, which are externalized upon platelet activation, are essential for the function of platelet surface receptors and intercellular interactions. Recent Advances: The platelet ER is a conduit for changes in cellular function in response to the extracellular milieu. ER homeostasis is maintained by an appropriate redox balance, regulated calcium stores and normal protein folding. Alterations in ER function and ER stress results in ER proteins externalizing to the cell surface, including members of the protein disulfide isomerase family (PDIs) and chaperones. Critical Issues: The platelet ER is central to platelet function, but our understanding of its regulation is incomplete. Previous studies have focused on the function of PDIs in the extracellular space, and much less on their intracellular role. How platelets maintain ER homeostasis and how they direct ER chaperone proteins to facilitate intercellular signalling is unknown. Future Directions: An understanding of ER functions in the platelet is essential as these may determine critical platelet activities such as secretion and adhesion. Studies are necessary to understand the redox reactions of PDIs in the intracellular versus extracellular space, as these differentially affect platelet function. An unresolved question is how platelet ER proteins control calcium release. Regulation of protein folding in the platelet and downstream pathways of ER stress require further evaluation. Targeting the platelet ER may have therapeutic application in metabolic and neoplastic disease.

Sclerosing peritonitis post liver transplantation: a rare condition where surgery is an important treatment option.

BACKGROUND: Sclerosing peritonitis (SP) is a rare but potentially fatal complication following orthotopic liver transplantation (OLT). The definitive surgical management is via a laparotomy peritonectomy and enterolysis procedure, but this carries risks particularly in the immunosuppressed transplant patient population. The natural history of SP is known from a handful of case reports and series, which mostly report de novo cases arising early on following OLT. The aim of this study was to identify all cases of de novo SP following OLT and the outcomes of management. METHODS: Cases of SP post OLT were identified from the Australian National Liver Transplantation Unit (New South Wales) database of all 1393 adult patients. RESULTS: Three cases of SP were diagnosed between 2 and over 9 years post-transplantation. Two patients proceeded to laparotomy and a peritonectomy and enterolysis procedure of the cocooned bowel. The third was managed conservatively due to a relatively indolent course and their medical co-morbidities. CONCLUSION: SP should be considered in the differential diagnosis in patients post OLT presenting with symptoms of bowel obstruction, even years following transplantation. Surgery may be required in order to achieve a satisfactory outcome in some cases.