Citations

Abstract Obesity is a risk factor for Pancreatic Ductal Adenocarcinoma (PDAC), but the molecular mechanisms involved are unclear. Oncogenic mutation of K-Ras occurs early and nearly universally in patients with this disease. However, recent evidence indicates that oncogenic Ras is not fully active and for activity to surpass the threshold required to engage a Ras-inflammation feed-forward loop, it requires a stimulus. We hypothesized that high-fat intake acts as an inflammatory stimulus, increasing K-Ras activity and that cyclooxygenase -2 (COX2) expression is required in the inflammatory loop. LSL-K-Ras mice were crossed with elastase-CreER (acinar cell-specific) or Pdx1-Cre (pancreatic cell-specific) to “knock-in” expression of oncogenic K-Ras. Additionally, acinar cell-specific -Ras mice were crossed with COX2 conditional knockout mice. All mice were fed isocaloric diets with different amounts of fat and a COX2 inhibitor was administered to some acinar cell-specific -Ras mice. Pancreata were analyzed for Ras activity, Phospho-ERK levels, inflammation, fibrosis, PanIN and PDAC development. We observed that consumption of a high fat diet (HFD) led to increased K-Ras activity, PanIN formation, fibrotic stroma and PDAC development compared to a control diet. Additionally, we observed a significant reduction in the survival of mice fed a HFD. Genetic deletion of COX2 in acinar cells and COX2 systemic inhibition prevented the HFD-induced effects in acinar cell-specific -Ras mice. These findings indicated that a HFD stimulates activation of oncogenic K-Ras and initiates an inflammatory feed-forward loop requiring the expression of COX2 leading to pancreatic inflammation, fibrosis, PanINs and PDAC. This mechanism may explain the PDAC risks associated with consumption of a HFD. Citation Format: Bincy Philip, Christina L. Roland, Jarek Daniluk, Yan Liu, Deyali Chatterjee, Sobeyda Berenice Gomez, Baoan Ji, Huang Haojie, Huamin Wang, Jason B. Fleming, Craig D. Logsdon, Zobeida Cruz-Monserrate. High fat triggers oncogenic K-Ras activity and a COX2 dependent feed-forward loop to induce pancreatic ductal adenocarcinoma development. [abstract]. In: Proceedings of the Twelfth Annual AACR International Conference on Frontiers in Cancer Prevention Research; 2013 Oct 27-30; National Harbor, MD. Philadelphia (PA): AACR; Can Prev Res 2013;6(11 Suppl): Abstract nr C61.

ABSTRACTThe mechanism underlying non‐contact anterior cruciate ligament (ACL) injury is multi‐factorial and still an object of debate. Computational models, in combination with in vivo and cadaveric studies, can provide valuable insight into the contribution of the different factors involved. The goal of this study was to validate four knee finite element models (two males and two females) to kinematic and strain data collected in vitro with an impact‐driven simulator and use them to assess how secondary external knee loads (knee abduction moment [KAM], anterior shear force, and internal rotation torque [ITR]) affect tibiofemoral contact forces and ACL force during impact. Four subject‐specific knee models were developed from specimen computed tomography and magnetic resonance imaging. Patellofemoral and tibiofemoral ligament properties were calibrated to match experimentally measured kinematics and ligament strain. Average root mean square errors and correlations between experimental and model‐predicted knee kinematics were below 1.5 mm and 2°, and above 0.75, respectively. Similar errors and correlations were obtained for ACL strain (< 2% and > 0.9). Model‐predicted ACL forces were highly correlated with the anterior component of the tibiofemoral contact force on the lateral plateau occurring during impact (r = 0.99), which was increased by larger KAM and ITR through the posterior tibial slope and a larger contact force on the lateral side. This study provides a better understanding of the mechanism through which secondary external knee loads increase ACL injury risk during landing. © 2019 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 37:1730–1742, 2019

Background: Achilles tendon tears are potentially career-ending injuries for professional athletes. For players in the National Football League (NFL), return requires not only surgery and extensive rehabilitation but also the ability to compete in a market with limited positions that annually introduces new recruits. Purpose/Hypothesis: We authors sought to evaluate factors related to return to play (RTP) and changes in performance following a primary Achilles tear. Our hypothesis was that “skilled” position players and those drafted in later rounds would return at a lower rate as compared with “unskilled” position players and higher draft-round players. Study Design: Case-control study; Level of evidence, 3. Methods: From a previously established database, 80 NFL players were identified as having primary Achilles tendon tears between the 2009 and 2014 seasons. RTP was defined as playing in a regular season or postseason game following injury. Probability of RTP was modeled as a function of time after injury in Kaplan-Meier analysis with demographic variables assessed via generalized linear models. Twelve players (15%) experienced a subsequent Achilles tendon tear during or after the study period and were included in the overall RTP rate but were excluded from performance analyses owing to the confounding effects of an ipsilateral retear or contralateral tear. Results: The overall RTP rate was 61.3%. Age, number of prior seasons, position type, or draft round status did not significantly affect RTP when evaluated with Kaplan-Meier analysis. In the season before their injury, players who did RTP played in a significantly greater number of regular season games (13.7) compared with players who did not RTP (8.71) ( P = .011). Players who did not RTP exhibited a significant decrease in performance in the season preceding injury (12.7 regular season games played 2 seasons preinjury vs 8.71 regular season games played 1 season prior preinjury;, P = .019). Players who returned did not display a significant change in the number of games played or started in seasons following injury when >1 season after return was evaluated. Conclusion: Rate of RTP following primary Achilles tendon tears may be lower than previously published. However, for those able to return, performance only in the season immediately following injury appears to be affected; players return to preinjury levels if given the opportunity to play >1 season after injury.