Alex L. Chang

Lysine 63-linked Polyubiquitination of TAK1 at Lysine 158 Is Required for Tumor Necrosis Factor α- and Interleukin-1β-induced IKK/NF-κB and JNK/AP-1 Activation

Transforming growth factor-β-activated kinase 1 (TAK1) plays an essential role in the tumor necrosis factor α (TNFα)- and interleukin-1β (IL-1β)-induced IκB kinase (IKK)/nuclear factor-κB (NF-κB) and c-Jun N-terminal kinase (JNK)/activator protein 1 (AP-1) activation. Here we report that TNFα and IL-1β induce Lys63-linked TAK1 polyubiquitination at the Lys158 residue within the kinase domain. Tumor necrosis factor receptor-associated factors 2 and 6 (TRAF2 and -6) act as the ubiquitin E3 ligases to mediate Lys63-linked TAK1 polyubiquitination at the Lys158 residue in vivo and in vitro. Lys63-linked TAK1 polyubiquitination at the Lys158 residue is required for TAK1-mediated IKK complex recruitment. Reconstitution of TAK1-deficient mouse embryo fibroblast cells with TAK1 wild type or a TAK1 mutant containing a K158R mutation revealed the importance of this site in TNFα and IL-1β-mediated IKK/NF-κB and JNK/AP-1 activation as well as IL-6 gene expression. Our findings demonstrate that Lys63-linked polyubiquitination of TAK1 at Lys158 is essential for its own kinase activation and its ability to mediate its downstream signal transduction pathways in response to TNFα and IL-1β stimulation.

TEG-guided resuscitation is superior to standardized MTP resuscitation in massively transfused penetrating trauma patients.

BACKGROUND For nearly a decade, our center performed thromboelastograms (TEGs) to analyze coagulation profiles, allowing rapid data-driven blood component therapy. After consensus recommendations for massive transfusion protocols (MTPs), we implemented an MTP in October 2009 with 1:1:1 ratio of blood (red blood cells [RBC]), plasma (fresh-frozen plasma [FFP]), and platelets. We hypothesized that TEG-directed resuscitation is equivalent to MTP resuscitation. METHODS All patients receiving 6 units (U) or more of RBC in the first 24 hours for 21 months before and after MTP initiation in an urban Level I trauma center were examined. Demographics, mechanism of injury (MOI), Injury Severity Score (ISS), 24-hour volume of RBC, FFP, platelets, crystalloid, and 30-day mortality were compared, excluding patients with traumatic brain injuries. Variables were analyzed using Student’s t-test and &khgr;2 or Fisher’s exact test. RESULTS For the preMTP group, there were 165 patients. In the MTP group, there were 124 patients. There were no significant differences in ISS, age, or sex. PreMTP patients with 6U or more RBC had significantly more penetrating MOI (p = 0.017), whereas preMTP patients with 10U or more RBC had similar MOIs. All patients received less crystalloid after MTP adoption (p < 0.001). There was no difference in volume of blood products or mortality in patients receiving 6U or more RBC. Blunt trauma MTP patients who received 10U or more RBC received more FFP (p = 0.02), with no change in mortality. Penetrating trauma patients who received 10U or more RBC received a similar volume of FFP; however, mortality increased from 54.1% for MTP versus 33.3% preMTP (p = 0.04). CONCLUSION TEG-directed resuscitation is equivalent to standardized MTP for patients receiving 6U or more RBC and for blunt MOI patients receiving 10U or more RBC. MTP therapy worsened mortality in penetrating MOI patients receiving 10U or more RBC, indicating a continued need for TEG-directed therapy. A 1:1:1 strategy may not be adequate in all patients. LEVEL OF EVIDENCE Therapeutic study, level IV.

Differential Regulation of Transforming Growth Factor β Signaling Pathways by Notch in Human Endothelial Cells

Notch and transforming growth factor β (TGFβ) play critical roles in endothelial-to-mesenchymal transition (EndMT), a process that is essential for heart development. Previously, we have shown that Notch and TGFβ signaling synergistically induce Snail expression in endothelial cells, which is required for EndMT in cardiac cushion morphogenesis. Here, we report that Notch activation modulates TGFβ signaling pathways in a receptor-activated Smad (R-Smad)-specific manner. Notch activation inhibits TGFβ/Smad1 and TGFβ/Smad2 signaling pathways by decreasing the expression of Smad1 and Smad2 and their target genes. In contrast, Notch increases SMAD3 mRNA expression and protein half-life and regulates the expression of TGFβ/Smad3 target genes in a gene-specific manner. Inhibition of Notch in the cardiac cushion of mouse embryonic hearts reduces Smad3 expression. Notch and TGFβ synergistically up-regulate a subset of genes by recruiting Smad3 to both Smad and CSL binding sites and cooperatively inducing histone H4 acetylation. This is the first evidence that Notch activation affects R-Smad expression and that cooperative induction of histone acetylation at specific promoters underlies the selective synergy between Notch and TGFβ signaling pathways.

Molecular mechanisms of erythrocyte aging.

Abstract Anemia and hemorrhagic shock are leading causes of morbidity and mortality worldwide, and transfusion of human blood products is the ideal treatment for these conditions. As human erythrocytes age during storage in blood banks they undergo many biochemical and structural changes, termed the red blood cell ‘storage lesion’. Specifically, ATP and pH levels decrease as metabolic end products, oxidative stress, cytokines, and cell-free hemoglobin increase. Also, membrane proteins and lipids undergo conformational and organizational changes that result in membrane loss, viscoelastic changes and microparticle formation. As a result, transfusion of aged blood is associated with a host of adverse consequences such as decreased tissue perfusion, increased risk of infection, and increased mortality. This review summarizes current research detailing the known parts of the erythrocyte storage lesion and their physiologic consequences.

Acid Sphingomyelinase Inhibition in Stored Erythrocytes Reduces Transfusion-Associated Lung Inflammation.

OBJECTIVE We aimed to identify the role of the enzyme acid sphingomyelinase in the aging of stored units of packed red blood cells (pRBCs) and subsequent lung inflammation after transfusion. SUMMARY BACKGROUND DATA Large volume pRBC transfusions are associated with multiple adverse clinical sequelae, including lung inflammation. Microparticles are formed in stored pRBCs over time and have been shown to contribute to lung inflammation after transfusion. METHODS Human and murine pRBCs were stored with or without amitriptyline, a functional inhibitor of acid sphingomyelinase, or obtained from acid sphingomyelinase-deficient mice, and lung inflammation was studied in mice receiving transfusions of pRBCs and microparticles isolated from these units. RESULTS Acid sphingomyelinase activity in pRBCs was associated with the formation of ceramide and the release of microparticles. Treatment of pRBCs with amitriptyline inhibited acid sphingomyelinase activity, ceramide accumulation, and microparticle production during pRBC storage. Transfusion of aged pRBCs or microparticles isolated from aged blood into mice caused lung inflammation. This was attenuated after transfusion of pRBCs treated with amitriptyline or from acid sphingomyelinase-deficient mice. CONCLUSIONS Acid sphingomyelinase inhibition in stored pRBCs offers a novel mechanism for improving the quality of stored blood.Objective: We aimed to identify the role of the enzyme acid sphingomyelinase in the aging of stored units of packed red blood cells (pRBCs) and subsequent lung inflammation after transfusion. Summary Background Data: Large volume pRBC transfusions are associated with multiple adverse clinical sequelae, including lung inflammation. Microparticles are formed in stored pRBCs over time and have been shown to contribute to lung inflammation after transfusion. Methods: Human and murine pRBCs were stored with or without amitriptyline, a functional inhibitor of acid sphingomyelinase, or obtained from acid sphingomyelinase-deficient mice, and lung inflammation was studied in mice receiving transfusions of pRBCs and microparticles isolated from these units. Results: Acid sphingomyelinase activity in pRBCs was associated with the formation of ceramide and the release of microparticles. Treatment of pRBCs with amitriptyline inhibited acid sphingomyelinase activity, ceramide accumulation, and microparticle production during pRBC storage. Transfusion of aged pRBCs or microparticles isolated from aged blood into mice caused lung inflammation. This was attenuated after transfusion of pRBCs treated with amitriptyline or from acid sphingomyelinase-deficient mice. Conclusions: Acid sphingomyelinase inhibition in stored pRBCs offers a novel mechanism for improving the quality of stored blood.

Addressing the High Costs of Pancreaticoduodenectomy at Safety-Net Hospitals

Importance Safety-net hospitals care for vulnerable patients, providing complex surgery at increased costs. These hospitals are at risk due to changing health care reimbursement policies and demand for better value in surgical care. Objective To model different techniques for reducing the cost of complex surgery performed at safety-net hospitals. Design, Setting, and Participants Hospitals performing pancreaticoduodenectomy (PD) were queried from the University HealthSystem Consortium database (January 1, 2009, to December 31, 2013) and grouped according to safety-net burden. A decision analytic model was constructed and populated with clinical and cost data. Sensitivity analyses were then conducted to determine how changes in the management or redistribution of patients between hospital groups affected cost. Main Outcomes and Measures Overall cost per patient after PD. Results During the 5 years of the study, 15 090 patients underwent PD. Among safety-net hospitals, low-burden hospitals (LBHs), medium-burden hospitals (MBHs), and high-burden hospitals (HBHs) treated 4220 (28.0%), 9505 (63.0%), and 1365 (9.0%) patients, respectively. High-burden hospitals had higher rates of complications or comorbidities and more patients with increased severity of illness. Perioperative mortality was twice as high at HBHs (3.7%) than at LBHs (1.6%) and MBHs (1.7%) (P < .001). In the base case, when all clinical and cost data were considered, PD at HBHs cost

Previous Cryopreservation Alters the Natural History of the Red Blood Cell Storage Lesion.

35 303 per patient, 30.1% and 36.2% higher than at MBHs (

Prophylactic pasireotide administration following pancreatic resection reduces cost while improving outcomes.

27 130) and LBHs (

Acid Sphingomyelinase Inhibition Prevents Hemolysis During Erythrocyte Storage.

25 916), respectively. Reducing perioperative complications or comorbidities by 50% resulted in a cost reduction of up to

Case mix–adjusted cost of colectomy at low-, middle-, and high-volume academic centers

4607 for HBH patients, while reducing mortality rates had a negligible effect. However, redistribution of HBH patients to LBHs and MBHs resulted in significantly more cost savings of