Alternative splicing of human NT5E generates CD73S, an endoplasmic reticulum–associated and dimerization-deficient glycoprotein that lacks enzymatic activity. CD73S functions as a negative regulator of canonical CD73 by promoting its proteasomal degradation, which may have significance in chronic liver disease and liver cancer.

Objective Mountaineers face a variety of health risks at altitude including pulmonary edema; portable ultrasound may be used to diagnose high altitude pulmonary edema. This report tests the functionality of electronic equipment in a hypobaric test environment and the ability of remotely guided nonexperts to use ultrasound to evaluate respiratory status on Mt Everest. Methods Two ultrasound devices and associated video equipment were tested in a cooled (4°C–5°C) hypobaric chamber to 27 000 feet (8230 m) before travel to Mt Everest. The ultrasound system was connected via satellite phone to a video streaming device and portable computer to stream video through the Internet for remote guidance of a novice user by an expert. Pulmonary interstitial fluid was quantified by the presence of “comet tail” artifacts. Results There was no notable degradation in equipment performance in cold, hypobaric conditions; ultrasound confirmation of increased comet tails was noted in the chamber despite oxygen supplementation and the very brief exposure. Two pulmonary surveys of asymptomatic participants were completed by novice operators within 25 minutes on Mt Everest. The remote expert was able to guide and identify comet tails suggestive of intermediate pulmonary interstitial fluid. Image quality was excellent. Conclusions The tested ultrasound devices functioned nominally in cold, hypobaric conditions; acute changes in lung fluid content were noted in these conditions despite normoxia. We successfully used a satellite telemedical connection with a remote expert to guide thoracic ultrasound examinations at Advanced Base Camp on Mt Everest. Coupling portable ultrasound with remote expert guidance telemedicine provides a robust diagnostic capability in austere locations.

Fas ligand (FasL)‐mediated hepatocyte apoptosis occurs in the context of acute liver injury that can be accompanied by intravascular coagulation (IC). We tested the hypothesis that analysis of selected protein fractions from livers undergoing apoptosis will shed light on mechanisms that are involved in liver injury that might be amenable to intervention. Proteomic analysis of the major insoluble liver proteins after FasL exposure for 4‐5 hours identified fibrinogen‐γ (FIB‐γ) dimers and FIB‐γ–containing high molecular mass complexes among the major insoluble proteins visible via Coomassie blue staining. Presence of the FIB‐γ–containing products was confirmed using FIB‐γ–specific antibodies. The FIB‐γ–containing products partition selectively and quantitatively into the liver parenchyma after inducing apoptosis. Similar formation of FIB‐γ products occurs after acetaminophen administration. The observed intrahepatic IC raised the possibility that heparin therapy may ameliorate FasL‐mediated liver injury. Notably, heparin administration in mice 4 hours before or up to 2 hours after FasL injection resulted in a dramatic reduction of liver injury—including liver hemorrhage, serum alanine aminotransferase, caspase activation, and liver apoptosis—compared with heparin‐untreated mice. Heparin did not directly interfere with FasL‐induced apoptosis in isolated hepatocytes, and heparin‐treated mice survived the FasL‐induced liver injury longer compared with heparin‐untreated animals. There was a sharp, near‐simultaneous rise in FasL‐induced intrahepatic apoptosis and coagulation, with IC remaining stable while apoptosis continued to increase. Conclusion: Formation of FIB‐γ dimers and their high molecular mass products are readily detectable within the liver during mouse apoptotic liver injury. Heparin provides a potential therapeutic modality, because it not only prevents extensive FasL‐related liver injury but also limits the extent of injury if given at early stages of injury exposure. (HEPATOLOGY 2011;)

Keratin 18 (K18 or KRT18) undergoes caspase-mediated cleavage during apoptosis, the significance of which is poorly understood. Here, we mutated the two caspase-cleavage sites (D238E and D397E) in K18 (K18-DE), followed by transgenic overexpression of the resulting mutant. We found that K18-DE mice develop extensive Fas-mediated liver damage compared to wild-type mice overexpressing K18 (K18-WT). Fas-stimulation of K18-WT mice or isolated hepatocytes caused K18 degradation. By contrast, K18-DE livers or hepatocytes maintained intact keratins following Fasstimulation, but showed hypo-phosphorylation at a major stresskinase-related keratin 8 (K8) phosphorylation site. Although K18-WT and K18-DE hepatocytes showed similar Fas-mediated caspase activation, K18-DE hepatocytes were more 'leaky' after a mild hypoosmotic challenge and were more susceptible to necrosis after Fas-stimulation or severe hypoosmotic stress. K8 hypophosphorylation was not due to the inhibition of kinase binding to the keratin but was due to mutation-induced inaccessibility to the kinase that phosphorylates K8. A stress-modulated keratin phospho-mutant expressed in hepatocytes phenocopied the hepatocyte susceptibility to necrosis but was found to undergo keratin filament reorganization during apoptosis. Therefore, the caspase cleavage of keratins might promote keratin filament reorganization during apoptosis. Interference with keratin caspase cleavage shunts hepatocytes towards necrosis and increases liver injury through the inhibition of keratin phosphorylation. These findings might extend to other intermediate filament proteins that undergo proteolysis during apoptosis.

Nucleoside diphosphate kinase (NDPK) proteins comprise a family of ten human isoforms that participate in the regulation of multiple cellular processes via enzymatic and non-enzymatic functions. The major enzymatic function of NDPKs is the generation of nucleoside triphosphates, such as GTP. Mechanisms behind the non-enzymatic NDPK functions are not clear, but likely involve context-dependent signaling roles of NDPK within multi-protein complexes. This is most evident for NDPK-A, which is encoded by the human NME1 gene, the first tumor metastasis suppressor gene to be identified. Understanding which protein interactions are most relevant for the biological and metastasis-related functions of NDPK will be important in the potential utilization of NDPK as a disease target. Accumulating evidence suggests that NDPK interacts with and affects various components and regulators of the cytoskeleton, including actin-binding proteins, intermediate filaments, and cytoskeletal attachment structures (adherens junctions, desmosomes and focal adhesions). We review the existing literature on this topic and highlight outstanding questions and potential future directions that should clarify the impact of NDPK on the different cytoskeletal systems.