Heterochromatin mostly comprises repeated sequences prone to harmful ectopic recombination during double-strand break (DSB) repair. In Drosophila cells, ‘safe’ homologous recombination (HR) repair of heterochromatic breaks relies on a specialized pathway that relocalizes damaged sequences away from the heterochromatin domain before strand invasion. Here we show that heterochromatic DSBs move to the nuclear periphery to continue HR repair. Relocalization depends on nuclear pore and inner nuclear membrane proteins (INMPs) that anchor repair sites to the nuclear periphery via the Smc5/6-interacting proteins STUbL/RENi. Both the initial block to HR progression inside the heterochromatin domain, and the targeting of repair sites to the nuclear periphery, rely on SUMO and SUMO E3 ligases. This study reveals a critical role for SUMOylation in the spatial and temporal regulation of HR repair in heterochromatin, and identifies the nuclear periphery as a specialized site for heterochromatin repair in a multicellular eukaryote.

BACKGROUND Acute traumatic coagulopathy (ATC) afflicts 20–30% of trauma patients, but the extensive collinearity of the coagulation cascade complicates attempts to clarify global clotting factor dysfunction. This study aims to characterize phenotypes of clotting factor dysfunction and their contributions to mortality after major trauma. METHODS This prospective cohort study examines all adult trauma patients of the highest activation level presenting to San Francisco General Hospital between 2/2005 and 2/2015. Factors II, V, VII, VIII, IX, X, and protein C activity on admission and mortality status at 28 days were assessed. Predictors of 28-day mortality in univariate analysis were included in multiple logistic regression controlling for traumatic brain injury (TBI), acidosis, age, and mechanism of injury. Principal component analysis (PCA) was utilized to identify phenotypic coagulation. RESULTS Complete coagulation factor data was available for 876/1,429 (61%). In multiple logistic regression, factors V (OR: 0.86, CI95%: 0.76–0.97), VIII (OR: 0.97, CI95%: 0.95–0.99), X (OR: 0.79, CI95%: 0.68–0.92), and protein C (OR: 1.17, CI95%: 1.05–1.30) significantly predicted 28-day mortality after controlling for age, base deficit, mechanism of injury, and TBI. PCA identified 2 significant principal components (Phenotypes 1 and 2) that accounted for 66.3% of the total variance. Phenotype 1 (factors II, VII, IX, X, and protein C abnormalities) explained 49.3% and was associated with increased injury, coagulopathy, TBI, and mortality. Phenotype 2 (factors V and VIII abnormalities) explained 17.0% and was associated with increased coagulopathy, blunt injury, and mortality. Only Phenotype 2 remained significantly associated with 28-day mortality in multiple logistic regression. CONCLUSIONS PCA identified 2 distinct phenotypes within the entirety of global clotting factor abnormalities, and these findings substantiate the crucial association of factors V and VIII on mortality following trauma. This may be the first step toward identifying unique phenotypes after injury and personalizing hemostatic resuscitation. LEVEL OF EVIDENCE Prognostic study, Level III

Structured Abstract Background Though obese patients have high thrombosis rates following injury, the role of obesity in coagulation after trauma remains unknown. We hypothesized that BMI is independently associated with increased measures of hypercoagulability longitudinally after injury. Methods Data were prospectively collected for 377 consecutive highest-level trauma activation patients with a body mass index (BMI) ≥ 18.5 kg/m2. Standard coagulation measures, citrated kaolin and functional fibrinogen thromboelastography (TEG), and clotting factors were measured at 0-120h. BMI categories were defined as normal weight (18.5-24.99 kg/m2), overweight (25-29.99 kg/m2), and obese (≥ 30 kg/m2). Results The 377 patients were mostly male (81%) and bluntly injured (61%), with median BMI of 25.8 kg/m2. 42% were normal weight (median BMI 22.5 kg/m2). There were no differences in age, gender, ISS or base deficit between groups. There were no differences in admission INR/PTT or factors II, V, VII, VIII, X, ATIII, or protein C. However, obese patients had higher admission platelet counts (303 vs. 269 × 109/L, p=0.004), lower D-dimer (1.88 vs. 4.00 ug/mL, p=0.004), and a trend toward higher factor IX (134 vs. 119 % activity, p=0.042) than normal weight patients. Measured by TEG, clot strength (MA) and functional fibrinogen level (FLEV) were also higher on admission for obese patients (MA 65.7 vs. 63.4 mm, p=0.016; FLEV 407 vs. 351 mg/dL, p=0.008). In multiple linear regression, the relationship of BMI to clot strength, FLEV, and FIX persisted through 24h. Similarly, the relationship of BMI and platelet count persisted through 120h (all p<0.05). In multiple logistic regression, for every 5kg/m2 increase in BMI, there was an 85% increase in odds of thromboembolic complication (OR 1.85, CI 1.13-3.08, p=0.017). Conclusion Obese trauma patients are hypercoagulable compared to their similarly-injured normal weight counterparts, which persists longitudinally after injury. The significance of this hypercoagulability requires elucidation for guidance of anticoagulation in this at-risk group. Level of Evidence Level III; prognostic

BackgroundPrior mortality prediction models have incorporated severity of anatomic injury quantified by Abbreviated Injury Severity Score (AIS). Using a prospective cohort, a new score independent of AIS was developed using clinical and laboratory markers present on emergency department presentation to predict 28-day mortality.MethodsAll patients (n=1427) enrolled in an ongoing prospective cohort study were included. Demographic, laboratory, and clinical data were recorded on admission. True random number generator technique divided the cohort into derivation (n=707) and validation groups (n=720). Using Youden indices, threshold values were selected for each potential predictor in the derivation cohort. Logistic regression was used to identify independent predictors. Significant variables were equally weighted to create a new mortality prediction score, the Trauma Early Mortality Prediction Tool (TEMPT) score. Area under the curve (AUC) was tested in the validation group. Pairwise comparison of Trauma Injury Severity Score (TRISS), Revised Trauma Score, Glasgow Coma Scale, and Injury Severity Score were tested against the TEMPT score.ResultsThere was no difference between baseline characteristics between derivation and validation groups. In multiple logistic regression, a model with presence of traumatic brain injury, increased age, elevated systolic blood pressure, decreased base excess, prolonged partial thromboplastin time, increased international normalized ratio (INR), and decreased temperature accurately predicted mortality at 28 days (AUC 0.93, 95% CI 0.90 to 0.96, P<0.001). In the validation cohort, this score, termed TEMPT, predicted 28-day mortality with an AUC 0.94 (95% CI 0.92 to 0.97). The TEMPT score preformed similarly to the revised TRISS score for severely injured patients and was highly predictive in those having mild to moderate injury.DiscussionTEMPT is a simple AIS-independent mortality prediction tool applicable very early following injury. TEMPT provides an AIS-independent score that could be used for early identification of those at risk of doing poorly following even minor injury.Level of evidenceLevel II.

Background International normalized ratio (INR) and partial thromboplastin time (PTT) are used interchangeably to diagnose acute traumatic coagulopathy (ATC) but reflect disparate activation pathways. In this study we identified injury/patient characteristics and coagulation factors that drive contact pathway, tissue factor pathway (TF), and common pathway dysfunction by examining injured patients with discordant coagulopathies. We hypothesized that patients with INR/PTT discordance reflect differing phenotypes representing contact vs. tissue factor pathway perturbations, and that characterization will provide targets to guide individualized resuscitation. Methods Plasma samples were prospectively collected from 1262 critically-injured patients at a single Level-1 trauma center. Standard coagulation measures and an extensive panel of pro- and anti-coagulant factors were assayed and analyzed with demographic and outcome data. Results Fourteen percent of patients were coagulopathic on admission. Among these, 48% had abnormal INR and PTT (BOTH), 43% had isolated prolonged PTT (PTT-CONTACT), and 9% had isolated elevated INR (INR-TF). PTT-CONTACT and BOTH had lower GCS than INR-TF (p<0.001). INR-TF had decreased factor VII activity compared to PTT-CONTACT, while PTT-CONTACT had decreased factor VIII activity compared to INR-TF. All coagulopathic patients had factor V defecits but activity was lowest in BOTH suggesting an additive downstream effect of disordered activation pathways. Patients with PTT-CONTACT received half as much PRBC and FFP as other groups (p<0.001). Despite resuscitation, mortality was higher for coagulopathic patients; mortality was highest in BOTH and higher in PTT-CONTACT than INR-TF (71%, 60%, 41% p=0.04) Conclusions Discordant phenotypes demonstrate differential factor deficiencies consistent with dysfunction of contact vs. tissue factor pathways with additive effects from common pathway dysfunction. Recognition and treatment of pathway-specific factor deficiencies driving different coagulopathic phenotypes in injured patients may individualize resuscitation and improve outcomes. Level of Evidence Prognostic/therapeutic study, level III.

were incidence of deep venous thrombosis (DVT) and pulmonary embolism (PE), red-cell transfusions (used as surrogate marker for bleeding events), unplanned return to the operating room, and mortality after initiation of thromboprophylaxis. RESULTS: There were 39,876 patients who had isolated spine trauma; 9,585 underwent operative intervention and received anticoagulants, of which 3,556 patients (early: 1,772, late: 1,772) were matched. Matched groups were similar in age (p ¼ 0.74), sex (p ¼ 0.45), systolic blood pressure (p ¼ 0.30), heart rate (p ¼ 0.78), Injury Severity Score (p ¼ 0.96), spine-Abbreviated Injury Score (p ¼ 0.84), type of operative intervention (p ¼ 0.38), and type of anticoagulant (p ¼ 0.82). The DVT rate was higher in the late group without affecting PE or mortality rate (Table). CONCLUSIONS: Early VTE prophylaxis is associated with decreased rates of DVT in patients with operative spinal trauma without increasing the risk of bleeding and mortality. VTE prophylaxis should be initiated within 48 hours postoperatively to reduce the risk of DVT in this high-risk patient population.