@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{schaaf_polkoff_carter_stewart_sheahan_freund_ginzel_snyder_roper_piedrahita_et al._2023, title={A LGR5 reporter pig model closely resembles human intestine for improved study of stem cells in disease}, volume={37}, ISSN={["1530-6860"]}, DOI={10.1096/fj.202300223R}, abstractNote={Abstract}, number={6}, journal={FASEB JOURNAL}, author={Schaaf, Cecilia R. and Polkoff, Kathryn M. and Carter, Amber and Stewart, Amy S. and Sheahan, Breanna and Freund, John and Ginzel, Joshua and Snyder, Joshua C. and Roper, Jatin and Piedrahita, Jorge A. and et al.}, year={2023}, month={Jun} }
 @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={Abstract}, 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{ludwig_abraham_schaaf_mckinney_freund_stewart_veerasammy_thomas_cardona_garman_et al._2023, title={Comparison of the effects of normothermic machine perfusion and cold storage preservation on porcine intestinal allograft regenerative potential and viability}, volume={24}, ISSN={1600-6135}, url={http://dx.doi.org/10.1016/j.ajt.2023.10.026}, DOI={10.1016/j.ajt.2023.10.026}, abstractNote={<h2>Abstract</h2> Intestinal transplantation (IT) is the final treatment option for intestinal failure. Static cold storage (CS) is the standard preservation method used for intestinal allografts. However, CS and subsequent transplantation induce ischemia-reperfusion injury (IRI). Severe IRI impairs epithelial barrier function, including loss of intestinal stem cells (ISC), critical to epithelial regeneration. Normothermic machine perfusion (NMP) preservation of kidney and liver allografts minimizes CS-associated IRI; however, it has not been used clinically for IT. We hypothesized that intestine NMP would induce less epithelial injury and better protect the intestine's regenerative ability when compared with CS. Full-length porcine jejunum and ileum were procured, stored at 4 °C, or perfused at 34 °C for 6 hours (T6), and transplanted. Histology was assessed following procurement (T0), T6, and 1 hour after reperfusion. Real-time quantitative reverse transcription polymerase chain reaction, immunofluorescence, and crypt culture measured ISC viability and proliferative potential. A greater number of NMP-preserved intestine recipients survived posttransplant, which correlated with significantly decreased tissue injury following 1-hour reperfusion in NMP compared with CS samples. Additionally, ISC gene expression, spheroid area, and cellular proliferation were significantly increased in NMP-T6 compared with CS-T6 intestine. NMP appears to reduce IRI and improve graft regeneration with improved ISC viability and proliferation.}, number={4}, journal={American Journal of Transplantation}, publisher={Elsevier BV}, author={Ludwig, Elsa K. and Abraham, Nader and Schaaf, Cecilia R. and McKinney, Caroline A. and Freund, John and Stewart, Amy S. and Veerasammy, Brittany A. and Thomas, Mallory and Cardona, Diana M. and Garman, Katherine and et al.}, year={2023}, month={Oct}, pages={564–576} }
 @article{stewart_schaaf_veerasammy_freund_gonzalez_2022, title={Culture of equine intestinal epithelial stem cells after delayed tissue storage for future applications}, volume={18}, ISSN={["1746-6148"]}, DOI={10.1186/s12917-022-03552-6}, abstractNote={Abstract}, number={1}, journal={BMC VETERINARY RESEARCH}, author={Stewart, Amy Stieler and Schaaf, Cecilia R. and Veerasammy, Brittany and Freund, John M. and Gonzalez, Liara M.}, year={2022}, 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.
          }, 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} }
 @article{stewart_schaaf_luff_freund_becker_tufts_robertson_gonzalez_2021, title={HOPX+ injury-resistant intestinal stem cells drive epithelial recovery after severe intestinal ischemia}, volume={321}, ISSN={["1522-1547"]}, url={https://doi.org/10.1152/ajpgi.00165.2021}, DOI={10.1152/ajpgi.00165.2021}, abstractNote={ This paper supports that rISCs are resistant to ischemic injury and likely an important source of cellular renewal following near-complete epithelial loss. Furthermore, we have evidence that HOPX controls ISC activity state and may be a critical signaling pathway during ISC-mediated repair. Finally, we use multiple novel methods to evaluate ISCs in a translationally relevant large animal model of severe intestinal injury and provide evidence for the potential role of rISCs as therapeutic targets. }, number={5}, journal={AMERICAN JOURNAL OF PHYSIOLOGY-GASTROINTESTINAL AND LIVER PHYSIOLOGY}, publisher={American Physiological Society}, author={Stewart, Amy Stieler and Schaaf, Cecilia Renee and Luff, Jennifer A. and Freund, John M. and Becker, Thomas C. and Tufts, Sara R. and Robertson, James B. and Gonzalez, Liara M.}, year={2021}, month={Oct}, pages={G588–G602} }
 @article{steward_hassel_martin_doddman_stewart_elzer_southwood_2020, title={Geographic Disparities in Clinical Characteristics of Duodenitis–Proximal Jejunitis in Horses in the United States}, volume={93}, url={https://doi.org/10.1016/j.jevs.2020.103192}, DOI={10.1016/j.jevs.2020.103192}, abstractNote={Duodenitis–proximal jejunitis (DPJ) is an idiopathic and potentially fatal disease of horses characterized by abdominal pain, proximal intestinal inflammation, and subsequent gastric and small intestinal fluid accumulation. Although this disease is known to be costly and life threatening in the equine industry, the severity of clinical signs can vary widely, and an exact etiology has yet to be elucidated. This study looked to identify differences in clinical parameters of horses with DPJ between geographic regions in an effort to corroborate anecdotal reports and support theories of differing etiologies. Case records were compared from veterinary academic referral hospitals in three different geographic locations in the United States to determine if significant differences in clinical, clinicopathologic, and prognostic characteristics exist among horses with DPJ. Clinical measurements on presentation that were significantly different between regions included heart rate, peritoneal total protein, albumin, anion gap, aspartate aminotransferase, gamma-glutamyl transferase, sodium, chloride, potassium, and creatinine. Duration of hospitalization and maximum body temperature while hospitalized were also different between regions. There were no significant differences in peritoneal cell count, total white blood cell count, neutrophil count, band neutrophils, calcium, total plasma protein, temperature on presentation, duration of reflux, total reflux volume, or age between hospitals. The mortality rates between hospitals were not significantly different. Increased severity of clinical signs and biochemical abnormalities were identified in the Southeastern United States hospital compared with the Northeastern and Western hospitals. A prospective, multicenter case–control study could identify risk factors contributing toward regional differences in this disease in the future.}, journal={Journal of Equine Veterinary Science}, publisher={Elsevier BV}, author={Steward, Sara K.T. and Hassel, Diana M. and Martin, Holly and Doddman, Courtney and Stewart, Amy and Elzer, Elizabeth J. and Southwood, Louise L.}, year={2020}, month={Oct}, pages={103192} }
 @article{gonzalez_stewart_freund_kucera_dekaney_magness_blikslager_2019, title={Preservation of reserve intestinal epithelial stem cells following severe ischemic injury}, volume={316}, ISSN={0193-1857 1522-1547}, url={http://dx.doi.org/10.1152/ajpgi.00262.2018}, DOI={10.1152/ajpgi.00262.2018}, abstractNote={ Intestinal ischemia is an abdominal emergency with a mortality rate >50%, leading to epithelial barrier loss and subsequent sepsis. Epithelial renewal and repair after injury depend on intestinal epithelial stem cells (ISC) that reside within the crypts of Lieberkühn. Two ISC populations critical to epithelial repair have been described: 1) active ISC (aISC; highly proliferative; leucine-rich-repeat-containing G protein-coupled receptor 5 positive, sex determining region Y-box 9 positive) and 2) reserve ISC [rISC; less proliferative; homeodomain only protein X (Hopx)+]. Yorkshire crossbred pigs (8–10 wk old) were subjected to 1–4 h of ischemia and 1 h of reperfusion or recovery by reversible mesenteric vascular occlusion. This study was designed to evaluate whether ISC-expressing biomarkers of aISCs or rISCs show differential resistance to ischemic injury and different contributions to the subsequent repair and regenerative responses. Our data demonstrate that, following 3–4 h ischemic injury, aISC undergo apoptosis, whereas rISC are preserved. Furthermore, these rISC are retained ex vivo in spheroids in which cell populations are enriched in the rISC biomarker Hopx. These cells appear to go on to provide a proliferative pool of cells during the recovery period. Taken together, these data indicate that Hopx+ cells are resistant to injury and are the likely source of epithelial renewal following prolonged ischemic injury. It is therefore possible that targeting reserve stem cells will lead to new therapies for patients with severe intestinal injury. }, number={4}, journal={American Journal of Physiology-Gastrointestinal and Liver Physiology}, publisher={American Physiological Society}, author={Gonzalez, Liara M. and Stewart, Amy Stieler and Freund, John and Kucera, Cecilia Renee and Dekaney, Christopher M. and Magness, Scott T. and Blikslager, Anthony T.}, year={2019}, month={Apr}, pages={G482–G494} }
 @article{stieler stewart_freund_blikslager_gonzalez_2018, title={Intestinal Stem Cell Isolation and Culture in a Porcine Model of Segmental Small Intestinal Ischemia}, volume={5}, ISSN={1940-087X}, url={http://dx.doi.org/10.3791/57647}, DOI={10.3791/57647}, abstractNote={Intestinal ischemia remains a major cause of morbidity and mortality in human and veterinary patients. Many disease processes result in intestinal ischemia, when the blood supply and therefore oxygen is decreased to the intestine. This leads to intestinal barrier loss and damage to the underlying tissue. Intestinal stem cells reside at the base of the crypts of Lieberkühn and are responsible for intestinal renewal during homeostasis and following injury. Ex vivo cell culture techniques have allowed for the successful study of epithelial stem cell interactions by establishing culture conditions that support the growth of three-dimensional epithelial organ-like systems (termed "enteroids" and "colonoids" from the small and large intestine, respectively). These enteroids are composed of crypt and villus-like domains and mature to contain all of the cell types found within the epithelium. Historically, murine models have been utilized to study intestinal injury. However, a porcine model offers several advantages including similarity of size as well as gastrointestinal anatomy and physiology to that of humans. By utilizing a porcine model, we establish a protocol in which segmental loops of intestinal ischemia can be created within a single animal, enabling the study of differing time points of ischemic injury and repair in vivo. Additionally, we describe a method to isolate and culture the intestinal stem cells from the ischemic loops of intestine, allowing for the continued study of epithelial repair, modulated by stem cells, ex vivo.}, number={135}, journal={Journal of Visualized Experiments}, publisher={MyJove Corporation}, author={Stieler Stewart, Amy and Freund, John M and Blikslager, Anthony T and Gonzalez, Liara M}, year={2018}, month={May} }
 @article{stewart_freund_gonzalez_2017, title={Advanced three-dimensional culture of equine intestinal epithelial stem cells}, volume={50}, ISSN={0425-1644}, url={http://dx.doi.org/10.1111/evj.12734}, DOI={10.1111/evj.12734}, abstractNote={Summary}, number={2}, journal={Equine Veterinary Journal}, publisher={Wiley}, author={Stewart, A. Stieler and Freund, J. M. and Gonzalez, L. M.}, year={2017}, month={Sep}, pages={241–248} }
 @misc{stewart_pratt-phillips_gonzalez_2017, title={Alterations in Intestinal Permeability: The Role of the "Leaky Gut" in Health and Disease}, volume={52}, ISSN={["1542-7412"]}, url={https://doi.org/10.1016/j.jevs.2017.02.009}, DOI={10.1016/j.jevs.2017.02.009}, abstractNote={All species, including horses, suffer from alterations that increase intestinal permeability. These alterations, also known as "leaky gut," may lead to severe disease as the normal intestinal barrier becomes compromised and can no longer protect against harmful luminal contents including microbial toxins and pathogens. Leaky gut results from a variety of conditions including physical stressors, decreased blood flow to the intestine, inflammatory disease, and pathogenic infections, among others. Several testing methods exist to diagnose these alterations in both a clinical and research setting. To date, most research has focused on regulation of the host immune response due to the wide variety of factors that can potentially influence the intestinal barrier. This article serves to review the normal intestinal barrier, measurement of barrier permeability, pathogenesis and main causes of altered permeability, and highlight potential alternative therapies of leaky gut in horses while relating what has been studied in other species. Conditions resulting in barrier dysfunction and leaky gut can be a major cause of decreased performance and also death in horses. A better understanding of the intestinal barrier in disease and ways to optimize the function of this barrier is vital to the long-term health and maintenance of these animals.}, journal={JOURNAL OF EQUINE VETERINARY SCIENCE}, publisher={Elsevier BV}, author={Stewart, Amy Stieler and Pratt-Phillips, Shannon and Gonzalez, Liara M.}, year={2017}, month={May}, pages={10–22} }
 @article{stewart_sanchez_mallicote_muniz_westerterp_burrow_mackay_2017, title={Effects of clarithromycin, azithromycin and rifampicin on terbutaline-induced sweating in foals}, volume={3}, DOI={10.1111/evj.12677}, abstractNote={Summary}, journal={Equine Veterinary Journal}, publisher={Wiley-Blackwell}, author={Stewart, A. L. Stieler and Sanchez, L. C. and Mallicote, M. F. and Muniz, A. L. and Westerterp, M. S. and Burrow, J. A. and MacKAY, R. J.}, year={2017}, month={Mar} }
 @article{taylor_mackay_nelson_stieler_roberts_castleman_2016, title={Spinal Cord Hamartomatous Myelodysplasia in 2 Horses With Clinical Neurologic Deficits}, volume={53}, DOI={10.1177/0300985815622971}, abstractNote={ Two horses euthanized for neurologic deficits were diagnosed with hamartomatous myelodysplasia of the spinal cord. One was a 5-week-old Holsteiner colt exhibiting spasms of muscle rigidity in the extensor muscles of the limbs and epaxial muscles, and the other was a 3-year-old Thoroughbred colt exhibiting progressive ataxia and hypermetria in the pelvic limbs. Each had focal disorganization of the white and gray matter of the spinal cord forming a mass interspersed with neurons, glial cells, and disoriented axon bundles. In the Holsteiner colt, the mass was at the level of C5 and included islands of meningeal tissue contiguous with the leptomeninges. The mass occluded the central canal forming hydromyelia cranial to the occlusion. In the Thoroughbred colt, the mass was at the level of L1 on the dorsal periphery of the spinal cord and did not involve the central canal. }, number={4}, journal={Veterinary Pathology}, publisher={SAGE Publications}, author={Taylor, K. R. and MacKay, R. J. and Nelson, E. A. and Stieler, A. L. and Roberts, J. F. and Castleman, W. L.}, year={2016}, month={Jul}, pages={844–846} }
 @article{stieler_sanchez_mallicote_martabano_burrow_mackay_2015, title={Macrolide-induced hyperthermia in foals: Role of impaired sweat responses}, volume={48}, DOI={10.1111/evj.12481}, abstractNote={Summary}, number={5}, journal={Equine Veterinary Journal}, publisher={Wiley-Blackwell}, author={Stieler, A. L. and Sanchez, L. C. and Mallicote, M. F. and Martabano, B. B. and Burrow, J. A. and MacKay, R. J.}, year={2015}, month={Sep}, pages={590–594} }
 @article{mcnaughten_pozor_mallicote_stieler_kelleman_macpherson_2014, title={Non-Surgical management of vaginal prolapse in a late gestation alpaca (Lamos pacos)}, volume={6}, number={4}, journal={Clinical Theriogenology}, author={McNaughten, J.W. and Pozor, M.A. and Mallicote, M.F. and Stieler, A.L. and Kelleman, A.A. and MacPherson, M.L.}, year={2014}, pages={489–493} }
 @article{stieler_reuss_werpy_mackay_2013, title={What Is Your Neurologic Diagnosis?}, volume={243}, DOI={10.2460/javma.243.6.779}, abstractNote={A 2-year-old Thoroughbred filly in race training was found in its stall with signs of lethargy and periorbital swelling and a corneal ulcer in the left eye; there appeared to be no vision in that eye. These signs were attributed to unobserved head trauma. Over a 3-day period, medical management of the ulcer with topical administration of antimicrobials and atropine was unsuccessful, and the horse was referred for further evaluation. The horse had been treated with acupuncture 2 months earlier for suspected pelvic limb weakness. At the referral examination, the upper eyelid of the left eye was swollen with chemosis}, number={6}, journal={Journal of the American Veterinary Medical Association}, publisher={American Veterinary Medical Association (AVMA)}, author={Stieler, Amy L. and Reuss, Sarah M. and Werpy, Natasha M. and MacKay, Robert J.}, year={2013}, month={Sep}, pages={779–781} }
 @article{stieler_bernardo_donovan_2012, title={Neutrophil and monocyte function in neonatal dairy calves fed fresh or frozen colostrum}, volume={10}, number={4}, journal={International Journal of Applied Research in Veterinary Medicine}, author={Stieler, A.L. and Bernardo, B.S. and Donovan, G.A.}, year={2012}, pages={328–334} }