@article{ludwig_abraham_mckinney_freund_stewart_garman_barbas_sudan_gonzalez_2023, title={45: Comparison of the Effects of Normothermic Machine Perfusion and Cold Storage Preservation on Porcine Intestinal Allograft Regenerative Potential and Viability}, volume={107}, ISSN={0041-1337}, url={http://dx.doi.org/10.1097/01.tp.0000945636.34372.db}, DOI={10.1097/01.tp.0000945636.34372.db}, abstractNote={Historically, intestinal transplantation (IT) has been reserved as the last treatment option for patients with irreversible intestinal failure who are unable to tolerate total parenteral nutrition. Successful IT is reliant upon graft health at the time of donation, minimizing graft injury that may occur during procurement, storage, and IT, and the ability of the graft to heal following insult. Unfortunately, the intestine is easily damaged by ischemia-reperfusion injury (IRI). IRI induces intestinal epithelial cell apoptosis and damages the mucosal barrier, which can result in bacterial translocation and activation of the local and systemic immune and inflammatory response, ultimately contributing to graft failure, rejection, and decreased recipient survival. The current, preferred method of intestinal preservation prior to IT is static cold storage (CS), however the prolonged hypothermic ischemia of CS causes cell injury and intensifies the IRI that occurs during transplantation. Furthermore, IRI to the epithelial crypt region diminishes the intestine’s ability to heal by inducing loss of the highly proliferative intestinal stem cells (ISCs) that are responsible for maintenance, regeneration, and repair of the epithelium, critical to graft health. Thus, the investigation of alternative organ preservation techniques that reduce IRI, cellular damage, and graft injury are warranted to overall improve IT success. Normothermic machine perfusion (NMP) is a preservation method that reduces inflammation and promotes graft regeneration in other organs by preventing CS-associated IRI. However, NMP has not been described for intestine. We hypothesized that, compared to CS, intestinal NMP will induce less epithelial injury and better protect ISC regenerative potential and viability. 15 porcine intestines were flushed with UW solution, stored at 4°C (CS), or perfused with 34°C perfusate (NMP) for 6hr, and transplanted (n=9). Recipient pigs were recovered from anesthesia. Jejunal and ileal segments were collected immediately after flushing, serving as control tissue (CO), after 6hr of CS or NMP, and after 1hr of reperfusion post-IT. Histologic injury was assessed. Crypts isolated after flushing (CO), 6hr CS or NMP, and 1hr of reperfusion post-IT were cultured. Spheroid number, size, and EdU staining quantified ISC viability and proliferation. Expression of ISC and cellular proliferation genes and proteins were measured. Histologically, NMP tissue had mild epithelial erosion and increased columnar cell attenuation and expression of ISC and proliferation genes/proteins was observed. NMP spheroid areas and proliferating cell numbers were significantly larger than control and CS. Apoptotic cells were increased following CS. Post-graft reperfusion, CS had increased injury compared to uninjured control and NMP tissue. Compared to CS, NMP may improve graft regenerative potential, resulting in transplantation of healthier bowel and superior recipient survival.}, number={7S}, journal={Transplantation}, publisher={Ovid Technologies (Wolters Kluwer Health)}, author={Ludwig, Elsa and Abraham, Nader and McKinney, Caroline and Freund, John and Stewart, Amy and Garman, Katherine and Barbas, Andrew and Sudan, Debra and Gonzalez, Liara}, year={2023}, month={Jun}, pages={25–25} }
 @article{ludwig_hallowell_womble_o'neil_2023, title={Bilateral patellar aplasia in a foal}, ISSN={["2053-1095"]}, DOI={10.1002/vms3.1083}, abstractNote={Abstract A 2‐day‐old Cleveland Bay colt was referred to the Equine Emergency Service of the Farm Animal and Equine Veterinary Medical Center at North Carolina State University's College of Veterinary Medicine for evaluation of decreased nursing behaviour and right hindlimb lameness of 2 days’ duration. When assisted to stand, the foal was unable to extend either hindlimb or bear weight on the hindlimbs, the right patella was luxated laterally and unable to be reduced, and the foal assumed a crouched position. Stifle radiographs revealed minimal, heterogeneous, ill‐defined ossification of both patellae. Due to the severity of the musculoskeletal defects, humane euthanasia was elected. Post‐mortem examination identified a congenital malformation of both patella bones with failure of ossification and cardiac changes suggestive of right atrioventricular valve dysplasia. Histology of the patellae showed no evidence of osteoid deposition or ossification. To our knowledge, bilateral congenital patellar aplasia has not been previously described in foals.}, journal={VETERINARY MEDICINE AND SCIENCE}, author={Ludwig, Elsa K. and Hallowell, Kim and Womble, Mandy and O'Neil, Erin}, year={2023}, month={Feb} }
 @article{ludwig_hobbs_mckinney-aguirre_gonzalez_2023, title={Biomarkers of Intestinal Injury in Colic}, volume={13}, ISSN={2076-2615}, url={http://dx.doi.org/10.3390/ani13020227}, DOI={10.3390/ani13020227}, abstractNote={Simple Summary Biomarkers are measurable substances within body tissues or fluids that allow for the identification of ongoing injury or disease. Colic secondary to gastrointestinal disease is one of the most frequent causes of morbidity and mortality in horses. Specifically, colic associated with intestinal ischemia is the most life-threatening variety of this disease. Optimization of biomarkers for the diagnosis of colic and identification of intestinal ischemia may expedite the diagnosis and management of this disease and thus help to alleviate this burden on the equid population. Lactate, and specifically the L isomer, is a commonly employed biomarker in colic evaluations. A variety of other biomarkers, however, have been preliminarily evaluated for equine colic. This paper reviews currently explored biomarkers in equine medicine for colic. Ultimately, based on this review, L-lactate continues to be the most reliable marker for intestinal ischemia during colic. However, further exploration of the biomarkers included here may eventually provide the key to accelerated identification, intervention, and thus better outcomes for horses suffering from intestinal ischemia. Abstract Biomarkers are typically proteins, enzymes, or other molecular changes that are elevated or decreased in body fluids during the course of inflammation or disease. Biomarkers pose an extremely attractive tool for establishing diagnoses and prognoses of equine gastrointestinal colic, one of the most prevalent causes of morbidity and mortality in horses. This topic has received increasing attention because early diagnosis of some forms of severe colic, such as intestinal ischemia, would create opportunities for rapid interventions that would likely improve case outcomes. This review explores biomarkers currently used in equine medicine for colic, including acute phase proteins, proinflammatory cytokines, markers of endotoxemia, and tissue injury metabolites. To date, no single biomarker has been identified that is perfectly sensitive and specific for intestinal ischemia; however, L-lactate has been proven to be a very functional and highly utilized diagnostic tool. However, further exploration of other biomarkers discussed in this review may provide the key to accelerated identification, intervention, and better outcomes for horses suffering from severe colic.}, number={2}, journal={Animals}, publisher={MDPI AG}, author={Ludwig, Elsa K. and Hobbs, Kallie J. and McKinney-Aguirre, Caroline A. and Gonzalez, Liara M.}, year={2023}, month={Jan}, pages={227} }
 @article{veerasammy_gonzalez_báez‐ramos_schaaf_stewart_ludwig_mckinney‐aguirre_freund_robertson_gonzalez_2023, title={Changes in equine intestinal stem/progenitor cell number at resection margins in cases of small intestinal strangulation}, volume={55}, ISSN={0425-1644 2042-3306}, url={http://dx.doi.org/10.1111/evj.13927}, DOI={10.1111/evj.13927}, abstractNote={BACKGROUND
Intestinal epithelial stem cells (ISC) are responsible for epithelial regeneration and are critical to the intestine's ability to regain barrier function following injury. Evaluating ISC biomarker expression in cases of small intestinal strangulation (SIS) may provide insight into clinical progression.


OBJECTIVES
Intestinal resection margins from cases of SIS were evaluated to determine if (1) evidence of injury could be identified using histomorphometry, (2) ISC biomarker expression was decreased in the proximal resection margin compared to control and distal resection margin, and (3) the ISC biomarker expression was associated with the number of preoperative risk factors negatively related to outcome, postoperative complications, or case outcome.


STUDY DESIGN
Retrospective cohort study.


METHODS
Intestinal samples were obtained intraoperatively from resection margins of adult horses with SIS and horses euthanised for reasons unrelated to colic. Preoperative risk factors negatively related to outcome, postoperative complications, and case outcome were obtained from medical records. Horses were grouped as euthanised intraoperatively, postoperatively, or survived to discharge. Histomorphometry and immunofluorescence were performed to evaluate tissue architecture and ISC and progenitor cell number. Groups were compared using one-way ANOVA. Associations between biomarker expression and the number of preoperative risk factors and postoperative complications negatively related to outcome were determined using linear regression modeling.


RESULTS
Thirty-six cases of SIS were evaluated. Ki67+ cell counts were decreased in the proximal (mean= 15.45 cells; 95% CI; 10.27-20.63, SD=4.17; p=0.02) and distal resection margins (mean=15.05; 95% CI= 8.46-21.64; SD=4.141; p=0.03) in horses euthanised postoperatively compared to control (mean=23.62 cells; 95% CI= 19.42-27.83; SD=5.883). In the distal resection margin, an increase in SOX9+ Ki67+ cells were associated with a decrease in the total number of preoperative risk factors negatively related to outcome (95% CI; 0.236-1.123; p=0.008, SE=0.1393).


MAIN LIMITATIONS
Small population size.


CONCLUSIONS
Proliferating cell and ISC numbers may be associated with case outcome. This article is protected by copyright. All rights reserved.}, number={6}, journal={Equine Veterinary Journal}, publisher={Wiley}, author={Veerasammy, Brittany and Gonzalez, Gabriel and Báez‐Ramos, Patricia and Schaaf, Cecilia R. and Stewart, Amy Stieler and Ludwig, Elsa K. and McKinney‐Aguirre, Caroline and Freund, John and Robertson, James and Gonzalez, Liara M.}, year={2023}, month={Feb}, pages={995–1002} }
 @article{hobbs_young_nannarone_luethy_hopster-iversen_mckenzie_ludwig_2023, title={Intravenous loss of over-the-wire catheter guidewires in 13 horses}, volume={12}, ISSN={["1939-1676"]}, url={https://doi.org/10.1111/jvim.16960}, DOI={10.1111/jvim.16960}, abstractNote={Abstract Background Over‐the‐wire (OTW) catheter placement is performed frequently in horses. Intravascular loss of a guidewire has been anecdotally reported, but there is limited information regarding the treatment and outcome of horses that have experienced this complication of OTW catheter placement. Objectives Describe the clinical and diagnostic features, treatment, and outcome of horses experiencing IV guidewire loss at the time of OTW catheter placement. Animals Thirteen horses. Methods Multicenter retrospective study to identify horses with IV guidewire loss. Horses of all ages were considered for inclusion. Horses were excluded from the study if complete medical records of signalment, indication, and outcome were not available. Intravenous guidewire loss was defined as the guidewire being lost IV at the time of OTW catheter placement. Results No horses in this study experienced adverse clinical signs associated with the loss of a guidewire. Eight horses had the guidewire removed and the guidewire was left in situ in 5 horses. None of the horses with the guidewire in situ had experienced long‐term effects. Conclusions and Clinical Importance Intravenous guidewire loss seems to have a good long‐term prognosis even in horses in which removal of the guidewire was not possible. Thus, in horses where guidewire removal is not feasible, guidewires that remain in situ may have limited to no adverse effects.}, journal={JOURNAL OF VETERINARY INTERNAL MEDICINE}, author={Hobbs, Kallie J. and Young, Kimberly A. S. and Nannarone, Sara and Luethy, Daniela and Hopster-Iversen, Charlotte and Mckenzie, Harold C. and Ludwig, Elsa K.}, year={2023}, month={Dec} }
 @article{abraham_ludwig_schaaf_veerasammy_stewart_mckinney_freund_brassil_samy_gao_et al._2022, title={Orthotopic Transplantation of the Full-length Porcine Intestine After Normothermic Machine Perfusion}, volume={8}, ISSN={2373-8731}, url={http://dx.doi.org/10.1097/TXD.0000000000001390}, DOI={10.1097/TXD.0000000000001390}, abstractNote={Background. Successful intestinal transplantation is currently hindered by graft injury that occurs during procurement and storage, which contributes to postoperative sepsis and allograft rejection. Improved graft preservation may expand transplantable graft numbers and enhance posttransplant outcomes. Superior transplant outcomes have recently been demonstrated in clinical trials using machine perfusion to preserve the liver. We hypothesized that machine perfusion preservation of intestinal allografts could be achieved and allow for transplantation in a porcine model. Methods. Using a translational porcine model, we developed a device for intestinal perfusion. Intestinal samples were collected at the time of organ procurement, and after 6 h of machine perfusion for gross and histologic evaluation, hourly chemistry panels were performed on the perfusate and were used for protocol optimization. Following transplantation, porcine recipient physical activity, systemic blood parameters, and vital signs were monitored for 2 d before sacrifice. Results. In initial protocol development (generation 1, n = 8 grafts), multiple metabolic, electrolyte, and acid-base derangements were measured. These factors coincided with graft and mesenteric edema and luminal hemorrhage and were addressed with the addition of dialysis. In the subsequent protocol (generation 2, n = 9 grafts), differential jejunum and ileum perfusion were observed resulting in gross evidence of ileal ischemia. Modifications in vasodilating medications enhanced ileal perfusion (generation 3, n = 4 grafts). We report successful transplantation of 2 porcine intestinal allografts after machine perfusion with postoperative clinical and gross evidence of normal gut function. Conclusions. This study reports development and optimization of machine perfusion preservation of small intestine and successful transplantation of intestinal allografts in a porcine model.}, number={11}, journal={Transplantation Direct}, publisher={Ovid Technologies (Wolters Kluwer Health)}, author={Abraham, Nader and Ludwig, Elsa K. and Schaaf, Cecilia R. and Veerasammy, Brittany and Stewart, Amy S. and McKinney, Caroline and Freund, John and Brassil, John and Samy, Kannan P. and Gao, Qimeng and et al.}, year={2022}, month={Oct}, pages={e1390} }