Yucatan Miniature Pigs Research Articles

Genome analysis of Yucatan miniature pigs to assess their potential as biomedical model animals.

ObjectivePigs share many physiological, anatomical and genomic similarities with humans, which make them suitable models for biomedical researches. Understanding the genetic status of Yucatan miniature pigs (YMPs) and their association with human diseases will help to assess their potential as biomedical model animals. This study was performed to identify non-synonymous single nucleotide polymorphisms (nsSNPs) in selective sweep regions of the genome of YMPs and present the genetic nsSNP distributions that are potentially associated with disease occurrence in humans.MethodsnsSNPs in whole genome resequencing data from 12 YMPs were identified and annotated to predict their possible effects on protein function. Sorting intolerant from tolerant (SIFT) and polymorphism phenotyping v2 analyses were used, and gene ontology (GO) network and Kyoto encyclopedia of genes and genomes (KEGG) pathway analyses were performed.ResultsThe results showed that 8,462 genes, encompassing 72,067 nsSNPs were identified, and 118 nsSNPs in 46 genes were predicted as deleterious. GO network analysis classified 13 genes into 5 GO terms (p<0.05) that were associated with kidney development and metabolic processes. Seven genes encompassing nsSNPs were classified into the term associated with Alzheimer’s disease by referencing the genetic association database. The KEGG pathway analysis identified only one significantly enriched pathway (p<0.05), hsa04080: Neuroactive ligand-receptor interaction, among the transcripts.ConclusionThe number of deleterious nsSNPs in YMPs was identified and then these variants-containing genes in YMPs data were adopted as the putative human diseases-related genes. The results revealed that many genes encompassing nsSNPs in YMPs were related to the various human genes which are potentially associated with kidney development and metabolic processes as well as human disease occurrence.

Fracture Healing and Bone Remodeling With Human Standard-Sized Magnesium Versus Polylactide–Co-Glycolide Plate and Screw Systems Using a Mini-Swine Craniomaxillofacial Osteotomy Fixation Model

This study compared the degradation profile, safety, and efficacy of bioresorbable magnesium alloy and polylactide-co-glycolide (PLGA) polymer osteosynthesis systems for the treatment of fractures in a load-sharing maxillofacial environment using a new mini-swine fracture fixation model. Two types of clinically relevant situations were evaluated in 5 Yucatan miniature pigs. Defined porcine midface osteotomies of the supraorbital rim and zygoma were created and fixed with either a coated magnesium (test animals) or PLGA plate and screw osteosynthesis system (control animals). After surgery, the mini-pigs were able to recover for either 1 or 9months with continuous invivo post-implantation monitoring. Standardized computed tomography (CT) imaging was taken immediately postoperatively and at termination for all animals. The 9-month cohort also underwent CT at 2, 4, and 6months after surgery. At necropsy, osteotomy sites and bone-implant units were harvested, and healing was evaluated by micro-CT, histopathology, and histomorphometry. After clinical and radiologic follow-up examination, all fracture sites healed well for both the magnesium and polymer groups regardless of time point. Complete bone union and gradually disappearing osteotomy lines were observed across all implantation sites, with no major consistency change in periprosthetic soft tissue or in soft tissue calcification. Macroscopic and microscopic examination showed no negative influence of gas formation observed with magnesium during the healing process. Histopathologic analysis showed similar fracture healing outcomes for both plating systems with good biocompatibility as evidenced by a minimal or mild tissue reaction. This study confirms that WE43 magnesium alloy exhibited excellent fracture healing properties before its full degradation without causing any substantial inflammatory reactions in a long-term porcine model.Compared with PLGA implants, magnesium represents a promising new biomaterial with reduced implant sizes and improved mechanical properties to support fracture healing in a load-sharing environment.

Bempedoic Acid Lowers Low-Density Lipoprotein Cholesterol and Attenuates Atherosclerosis in Low-Density Lipoprotein Receptor-Deficient (LDLR+/- and LDLR-/-) Yucatan Miniature Pigs.

Bempedoic acid (BemA; ETC-1002) is a novel drug that targets hepatic ATP-citrate lyase to reduce cholesterol biosynthesis. In phase 2 studies, BemA lowers elevated low-density lipoprotein cholesterol (LDL-C) in hypercholesterolemic patients. In the present study, we tested the ability of BemA to decrease plasma cholesterol and LDL-C and attenuate atherosclerosis in a large animal model of familial hypercholesterolemia. Gene targeting has been used to generate Yucatan miniature pigs heterozygous (LDLR+/-) or homozygous (LDLR-/-) for LDL receptor deficiency (ExeGen). LDLR+/- and LDLR-/- pigs were fed a high-fat, cholesterol-containing diet (34% kcal fat; 0.2% cholesterol) and orally administered placebo or BemA for 160 days. In LDLR+/- pigs, compared with placebo, BemA decreased plasma cholesterol and LDL-C up to 40% and 61%, respectively. In LDLR-/- pigs, in which plasma cholesterol and LDL-C were 5-fold higher than in LDLR+/- pigs, BemA decreased plasma cholesterol and LDL-C up to 27% and 29%, respectively. Plasma levels of triglycerides and high-density lipoprotein cholesterol, fasting glucose and insulin, and liver lipids were unaffected by treatment in either genotype. In the aorta of LDLR+/- pigs, BemA robustly attenuated en face raised lesion area (-58%) and left anterior descending coronary artery cross-sectional lesion area (-40%). In LDLR-/- pigs, in which lesions were substantially more advanced, BemA decreased aortic lesion area (-47%) and left anterior descending coronary artery lesion area (-48%). In a large animal model of LDLR deficiency and atherosclerosis, long-term treatment with BemA reduces LDL-C and attenuates the development of aortic and coronary atherosclerosis in both LDLR+/- and LDLR-/- miniature pigs.

Intrauterine growth-restricted Yucatan miniature pigs experience early catch-up growth, leading to greater adiposity and impaired lipid metabolism as young adults.

Early nutrition has critical influences on cardiovascular disease risk in adulthood. The study objectives were to evaluate the impact of low birth weight on fasting and postprandial lipid metabolism and endothelium function in Yucatan miniature pigs. Intrauterine growth-restricted (IUGR) piglets (n = 6; 3 days old, 0.73 ± 0.04 kg) were paired with normal-weight (NW) same-sex littermates (n = 6; 1.11 ± 0.05 kg) and fed milk replacer ad libitum for 4 weeks. Thereafter, all pigs were fed a standard diet ad libitum for 5 h/day with growth, intakes, and blood samples collected for 8 months. At 9 months old, pigs were surgically fitted with venous catheters and an oral fat tolerance test was performed. At 10 months old, pigs were killed and endothelium-dependent and -independent vasodilations of isolated coronary arteries were measured using wire-myographs. IUGR pigs demonstrated catch-up growth (P < 0.05) in body weight and abdominal circumference prior to sexual maturity (<7 months old) and had more (P < 0.05) subcutaneous fat at 10 months old compared with NW pigs. IUGR pigs had consistently higher fasting plasma triglyceride concentrations from 5 to 10 months old and higher liver triglyceride and total cholesterol concentrations at 10 months old (P < 0.05). The fat tolerance test revealed delayed postprandial triglyceride clearance in IUGR pigs, but no differences in plaque formation or vascular reactivity. To conclude, IUGR and early postnatal catch-up growth are associated with increased overall body fat deposition and altered triglyceride metabolism in adult Yucatan miniature swine.

Abstract 394: Ldl-cholesterol, ApoB100 Kinetics and Atherosclerosis in Ldlr-deficient Yucatan Minipigs: A New Model for Familial Hypercholesterolemia

Lack of animal models with human-like lipoprotein metabolism and pathology has hampered translational research in atherosclerosis. Recently, a model of familial hypercholesterolemia was developed in Yucatan miniature pigs, in which the LDL receptor (LDLR) was deleted through gene targeting of exon 4. The objective of the present study was to determine the plasma lipoprotein response to a high fat diet and the kinetics of apolipoprotein (apo) B metabolism in LDLR-deficient miniature pigs. LDLR+/+ (n=5), LDLR+/- pigs (n=6) and LDLR-/- pigs (n=5) were fed a diet containing 34% kcal from fat and 0.2% cholesterol (C). At 6 weeks, the kinetics of plasma apoB100 (fasting) were measured using stable isotopic techniques and multi-compartmental modeling. In chow-fed pigs, LDL-C was 0.8mM, 1.3mM and 14mM in LDLR+/+, LDLR+/- and LDLR-/- pigs, respectively. On diet for 6 weeks, LDL-C increased 1.3-fold (to 1.09mM), 1.7-fold (to 2.3mM) and 1.2-fold (to 15.8mM) in LDLR+/+, LDLR+/- and LDLR-/- pigs, respectively. The effect of genotype or diet on plasma TG and HDL-C was modest. Compared to LDLR+/+ pigs, VLDL apoB100 pool sizes increased 1.4-fold in LDLR+/- and 1.7-fold in LDLR-/- pigs, due primarily to a decrease in fractional catabolic rates (FCR) of 18% and 63%, respectively. Compared to LDL+/+ pigs, LDL apoB100 pool sizes increased 2.2-fold and 14-fold in LDLR+/- and LDLR-/-, respectively, which was due to both 1.5-fold and 2-fold increases in production rates and 24% and 85% decreases in FCR, respectively. At 23 weeks, raised lesion area in the abdominal aorta was 3.3% in LDLR+/- pigs and 48.5% in LDLR-/- pigs. In the left anterior descending coronary artery, lesion area was 14.7x10 3 μm 2 in LDLR+/- pigs and 656x10 3 μm 2 in LDLR-/- pigs. This model should prove useful for translational research in lipoprotein metabolism and atherosclerosis.

Percutaneous Treatment of Herniated Lumbar Discs with Ozone: Investigation of the Mechanisms of Action

PurposeTo elucidate the mechanism of action of intradiscal oxygen-ozone therapy for herniated intervertebral disc therapy. MethodsOzone’s mechanism of action was investigated using 3 approaches: mathematical models of intervertebral disc space to explore the relationship between disc pressure and volume; ozonolysis experiments using glycosaminoglycans (GAGs) from a Chinese hamster ovary cell line that were similar in composition to GAGs found in human nucleus pulposus; and experiments in which live Yucatan miniature pigs received various concentrations of percutaneous, image-guided intradiscal oxygen-ozone treatment and were examined (after sacrifice) with histology and semiquantitative analysis of disc cytokine concentrations. ResultsEngineering calculations support observations that a small (6%) disc volume reduction can result in considerable (9.84%) intradiscal pressure reduction. Porcine disc histology and Chinese hamster ovary GAG ozonolysis results showed that administered ozone reacted with and fragmented disc proteoglycans, reducing disc volume through disc dehydration. Cytokine analysis of porcine discs found that each of 4 cytokines measured (interleukin [IL]-1β, IL-6, IL-8, and tumor necrosis factor α) increased in concentration after 2 wt% ozone treatment. ConclusionsOxygen-ozone therapy breaks down proteoglycan GAGs that maintain disc osmotic pressure, dehydrating the nucleus pulposus and reducing intervertebral disc volume. This is likely a primary mechanism by which ozone relieves nerve root compression and alleviates herniated disc–related pain. Additionally, 2 wt% ozone appears to interact with intradiscal cytokines, generating an antiinflammatory response that may contribute to symptom improvement.

Validation of a Preclinical Model of Diethylnitrosamine-Induced Hepatic Neoplasia in Yucatan Miniature Pigs

Objective: The purpose of this study was to reduce the time to tumor onset in a diethylnitrosamine (DEN)-induced hepatocellular carcinoma (HCC) swine model via partial liver embolization (PLE) and to characterize the model for use in translational research. Methods: Eight Yucatan miniature pigs were injected intraperitoneally with either saline (n = 2) or DEN (n = 6) solution weekly for 12 weeks. Three of the DEN-treated pigs underwent PLE. The animals underwent periodic radiological evaluation, liver biopsy, and blood sampling, and full necropsy was performed at study termination (∼29 months). Results: All DEN-treated pigs developed hepatic adenoma and HCC. PLE accelerated the time to adenoma development but not to HCC development. Biomarker analysis results showed that IGF1 levels decreased in all DEN-treated pigs as functional liver capacity decreased with progression of HCC. VEGF and IL-6 levels were positively correlated with disease progression. Immunohistochemical probing of HCC tissues demonstrated the expression of several important survival-promoting proteins. Conclusion: To our knowledge, we are the first to demonstrate an accelerated development of hepatic neoplasia in Yucatan miniature pigs. Our HCC swine model closely mimics the human condition (i.e., progressive disease stages and expression of relevant molecular markers) and is a viable translational model.

Abstract 18: Bempedoic Acid Lowers Low Density Lipoprotein-Cholesterol and Attenuates Aortic Atherosclerosis in LDL Receptor-Deficient ( LDLR +/- and LDLR -/- ) Yucatan Miniature Pigs

Bempedoic acid (ETC-1002) is an oral investigational drug that targets hepatic adenosine triphosphate-citrate lyase to reduce cholesterol biosynthesis. In Phase 2 studies (up to 12 weeks in duration), bempedoic acid lowers elevated LDL-cholesterol (C) in patients with hypercholesterolemia. The objective of the present study was to test the ability of bempedoic acid to decrease plasma-C and LDL-C, and attenuate the development of atherosclerosis in a large animal model of familial hypercholesterolemia. Gene targeting has been used to generate Yucatan miniature pigs heterozygous ( LDLR +/- ) or homozygous ( LDLR -/- ) for LDL-receptor (R) deficiency (ExeGen). LDLR +/- pigs (n=12) and LDLR -/- pigs (n=12) were fed a high fat, cholesterol-containing diet (34% kcal fat; 0.2% cholesterol) and orally administered placebo or bempedoic acid at 120 mg/d and at 240 mg/d for 160 days. Bempedoic acid was well tolerated; weight gain, caloric intake, liver enzymes and clinical chemistry analyses were unaffected by treatment. In LDLR +/- pigs at 160 days, compared to placebo, bempedoic acid significantly decreased plasma-C and LDL-C up to 43% ( P &lt;0.01) and 63% ( P &lt;0.002), respectively. Compared to LDLR-/- placebo pigs, in which plasma-C and LDL-C were 5-fold higher than in LDLR +/- placebo pigs, bempedoic acid significantly decreased plasma-C and LDL-C up to 26% ( P &lt;0.04) and 29% ( P &lt;0.03), respectively. Plasma levels of triglycerides and HDL-C, fasting glucose and insulin, and liver lipids were not affected by treatment in either genotype. In the aorta of LDLR +/- pigs, bempedoic acid treatment robustly attenuated total Sudan IV-stained lesion area (-58%, P &lt;0.02) and area of raised lesions in the abdominal aorta (-58%, P &lt;0.03). In LDLR -/- pigs, in which total aortic lesion area (6-fold) and area of raised abdominal lesions (12-fold) were substantially larger compared to LDLR +/- pigs, bempedoic acid significantly decreased total aortic lesion area (-47%, P &lt;0.01) and area of raised abdominal lesions (-50%, P &lt;0.03). The present experiments demonstrate that in a large animal model of LDLR-deficiency and atherosclerosis, long term treatment with bempedoic acid reduces LDL-C and attenuates the progression of aortic atherosclerosis in both LDLR +/- and LDLR -/- miniature pigs.

Analysis of Swine Leukocyte Antigen Haplotypes in Yucatan Miniature Pigs Used as Biomedical Model Animal.

The porcine major histocompatibility complex (MHC) is called swine leukocyte antigen (SLA), which controls immune responses and transplantation reactions. The SLA is mapped on pig chromosome 7 (SSC7) near the centromere. In this study, 3 class I (SLA-1, SLA-3, and SLA-2) and 3 class II (DRB1, DQB1, and DQA) genes were used for investigation of SLA haplotypes in Yucatan miniature pigs in Korea. This pig breed is a well-known model organism for biomedical research worldwide. The current study indicated that Korean Yucatan pig population had 3 Class I haplotypes (Lr-4.0, Lr-6.0, and Lr-25.0) and 3 class II haplotypes (Lr-0.5, Lr-0.7, and Lr-0.25). The combinations of SLA class I and II haplotype together, 2 homozygous (Lr-4.5/4.5 and Lr-6.7/6.7) and 3 heterozygous (Lr-4.5/6.7, Lr-4.5/25.25, and Lr-6.7/25.25) haplotypes were identified, including previously unidentified new heterozygous haplotypes (Lr-4.5/4.7). In addition, a new SLA allele typing method using Agilent 2100 bioanalyzer was developed that permitted more rapid identification of SLA haplotypes. These results will facilitate the breeding of SLA homozygous Yucatan pigs and will expedite the possible use of these pigs for the biomedical research, especially xenotransplantation research.

Computed Tomography and Magnetic Resonance Imaging for Longitudinal Characterization of Lung Structure Changes in a Yucatan Miniature Pig Silicosis Model

Medical imaging is a rapidly advancing field enabling the repeated, noninvasive assessment of physiological structure and function. These beneficial characteristics can supplement studies in swine by mirroring the clinical functions of detection, diagnosis, and monitoring in humans. In addition, swine may serve as a human surrogate, facilitating the development and comparison of new imaging protocols for translation to humans. This study presents methods for pulmonary imaging developed for monitoring pulmonary disease initiation and progression in a pig exposure model with computed tomography and magnetic resonance imaging. In particular, a focus was placed on systematic processes, including positioning, image acquisition, and structured reporting to monitor longitudinal change. The image-based monitoring procedure was applied to 6 Yucatan miniature pigs. A subset of animals (n= 3) were injected with crystalline silica into the apical bronchial tree to induce silicosis. The methodology provided longitudinal monitoring and evidence of progressive lung disease while simultaneously allowing for a cross-modality comparative study highlighting the practical application of medical image data collection in swine. The integration of multimodality imaging with structured reporting allows for cross comparison of modalities, refinement of CT and MRI protocols, and consistently monitors potential areas of interest for guided biopsy and/or necropsy.

Comparison of magnesium versus polylactide-co-glycolide resorbable plates and screws using a new porcine maxillofacial fracture fixation model, a pilot study

Comparison of magnesium versus polylactide-co-glycolide resorbable plates and screws using a new porcine maxillofacial fracture fixation model, a pilot study

Guanidinoacetate is more effective than creatine at enhancing tissue creatine stores while consequently limiting methionine availability in Yucatan miniature pigs.

Creatine (Cr) is an important high-energy phosphate buffer in tissues with a high energy demand such as muscle and brain and is consequently a highly consumed nutritional supplement. Creatine is synthesized via the S-adenosylmethionine (SAM) dependent methylation of guanidinoacetate (GAA) which is not regulated by a feedback mechanism. The first objective of this study was to determine the effectiveness of GAA at increasing tissue Cr stores. Because SAM is required for other methylation reactions, we also wanted to determine whether an increased creatine synthesis would lead to a lower availability of methyl groups for other methylated products. Three month-old pigs (n = 18) were fed control, GAA- or Cr-supplemented diets twice daily. On day 18 or 19, anesthesia was induced 1–3 hours post feeding and a bolus of [methyl-3H]methionine was intravenously infused. After 30 minutes, the liver was analyzed for methyl-3H incorporation into protein, Cr, phosphatidylcholine (PC) and DNA. Although both Cr and GAA led to higher hepatic Cr concentration, only supplementation with GAA led to higher levels of muscle Cr (P < 0.05). Only GAA supplementation resulted in lower methyl-3H incorporation into PC and protein as well as lower hepatic SAM concentration compared to the controls, suggesting that Cr synthesis resulted in a limited methyl supply for PC and protein synthesis (P < 0.05). Although GAA is more effective than Cr at supporting muscle Cr accretion, further research should be conducted into the long term consequences of a limited methyl supply and its effects on protein and PC homeostasis.

Embolization of the first diagonal branch of the left anterior descending coronary artery as a porcine model of chronic trans-mural myocardial infarction

BackgroundAlthough the incidence of acute death related to coronary artery disease has decreased with the advent of new interventional therapies, myocardial infarction remains one of the leading causes of death in the US. Current animal models developed to replicate this phenomenon have been associated with unacceptably high morbidity and mortality. A new model utilizing the first diagonal branch of the left anterior descending artery (D1-LAD) was developed to provide a clinically relevant lesion, while attempting to minimize the incidence of adverse complications associated with infarct creation.MethodsEight Yucatan miniature pigs underwent percutaneous embolization of the D1-LAD via injection of 90 µm polystyrene micro-spheres. Cardiac structure and function were monitored at baseline, immediately post-operatively, and at 8-weeks post-infarct using transthoracic echocardiography. Post-mortem histopathology and biochemical analyses were performed to evaluate for changes in myocardial structure and extracellular matrix (ECM) composition respectively. Echocardiographic data were evaluated using a repeated measures analysis of variance followed by Tukey’s HSD post hoc test. Biochemical analyses of infarcted to non-infarcted myocardium were compared using analysis of variance.ResultsAll eight pigs successfully underwent echocardiography prior to catheterization. Overall procedural survival rate was 83% (5/6) with one pig excluded due to failure of infarction and another due to deviation from protocol. Ejection fraction significantly decreased from 69.7 ± 7.8% prior to infarction to 50.6 ± 14.7% immediately post-infarction, and progressed to 48.7 ± 8.9% after 8-weeks (p = 0.011). Left ventricular diameter in systole significantly increased from 22.6 ± 3.8 mm pre-operatively to 30.9 ± 5.0 mm at 8 weeks (p = 0.016). Histopathology showed the presence of disorganized fibrosis on hematoxylin and eosin and Picro Sirius red stains. Collagen I and sulfated glycosaminoglycan content were significantly greater in the infarcted region than in normal myocardium (p = 0.007 and p = 0.018, respectively); however, pyridinoline crosslink content per collagen I content in the infarcted region was significantly less than normal myocardium (p = 0.048).ConclusionSystolic dysfunction and changes in ECM composition induced via embolization of the D1-LAD closely mimic those found in individuals with chronic myocardial infarction (MI), and represents a location visible without the need for anesthesia. As a result, this method represents a useful model for studying chronic MI.Electronic supplementary materialThe online version of this article (doi:10.1186/s12967-015-0547-4) contains supplementary material, which is available to authorized users.

Cryopreserved human amniotic membrane and a bioinspired underwater adhesive to seal and promote healing of iatrogenic fetal membrane defect sites

IntroductionWe investigated the ability of cryopreserved human amniotic membrane (hAM) scaffold sealed with an underwater adhesive, bio-inspired by marine sandcastle worms to promote healing of iatrogenic fetal membrane defects in a pregnant swine model. MethodsTwelve Yucatan miniature pigs underwent laparotomy under general anesthesia at 70 days gestation (term = 114 days). The gestational sacs were assigned to uninstrumented (n = 24) and instrumented with 12 Fr trocar, which was further randomized into four different arms-no hAM patch, (n = 22), hAM patch secured with suture (n = 16), hAM patch with no suture (n = 14), and hAM patch secured with adhesive (n = 9). The animals were euthanized 20 days after the procedure. Gross and histological examination of the entry site was performed for fetal membrane healing. ResultsThere were no differences in fetal survival, amniotic fluid levels, or dye-leakage from the amniotic cavity between the groups. The fetal membranes spontaneously healed in instrumented sacs without hAM patches. In sacs with hAM patches secured with sutures, the patch was incorporated into the swine fetal membranes. In sacs with hAM patches without sutures, 100% of the patches were displaced from the defect site, whereas in sacs with hAM patches secured with adhesive 55% of the patches remained in place and showed complete healing (p = 0.04). DiscussionIn contrast to humans, swine fetal membranes heal spontaneously after an iatrogenic injury and thus not an adequate model. hAM patches became incorporated into the defect site by cellular ingrowth from the fetal membranes. The bioinspired adhesive adhered the hAM patches within the defect site.

Exploring the genetic signature of body size in Yucatan miniature pig.

Since being domesticated about 10,000–12,000 years ago, domestic pigs (Sus scrofa domesticus) have been selected for traits of economic importance, in particular large body size. However, Yucatan miniature pigs have been selected for small body size to withstand high temperature environment and for laboratory use. This renders the Yucatan miniature pig a valuable model for understanding the evolution of body size. We investigate the genetic signature for selection of body size in the Yucatan miniature pig. Phylogenetic distance of Yucatan miniature pig was compared to other large swine breeds (Yorkshire, Landrace, Duroc and wild boar). By estimating the XP-EHH statistic using re-sequencing data derived from 70 pigs, we were able to unravel the signatures of selection of body size. We found that both selections at the level of organism, and at the cellular level have occurred. Selection at the higher levels include feed intake, regulation of body weight and increase in mass while selection at the molecular level includes cell cycle and cell proliferation. Positively selected genes probed by XP-EHH may provide insight into the docile character and innate immunity as well as body size of Yucatan miniature pig.

Lower esophageal sphincter augmentation by endoscopic injection of dextranomer hyaluronic acid copolymer in a porcine gastroesophageal reflux disease model

BackgroundWe previously demonstrated feasibility, safety, and a reproducible histologic bulking effect after injection of dextranomer hyaluronic acid copolymer (DxHA) into the gastroesophageal junction of rabbits. In the current study, we investigated the potential for DxHA to augment the lower esophageal sphincter (LES) in a porcine model of gastroesophageal reflux disease (GERD). MethodsTwelve Yucatan miniature pigs underwent LES manometry and 24-hour ambulatory pH monitoring at baseline, after cardiomyectomy, and 6weeks after randomization to endoscopic injection of either DxHA or saline at the LES. After necropsy, the foregut, including injection sites, was histologically examined. ResultsPigs in both groups had similar weight progression. Cardiomyectomy induced GERD in all animals, as measured by a rise in the median % of time pH <5 from 0.6 to 11.6 (p=0.02). Endoscopic injection of DxHA resulted in a higher median difference in LES length (1.8cm vs. 0.4cm, p=0.03). In comparison with saline injection, DxHA resulted in 120% increase in LES pressure, and 76% decrease in the mean duration of reflux episodes, but these results were not statistically significant. Injection of DxHA induced a foreign body reaction with fibroblasts and giant cells. ConclusionsPorcine cardiomyectomy is a reproducible animal GERD model. Injection of DxHA may augment the LES, offering a potential therapeutic effect in GERD.

Targeted Disruption of LDLR Causes Hypercholesterolemia and Atherosclerosis in Yucatan Miniature Pigs

Recent progress in engineering the genomes of large animals has spurred increased interest in developing better animal models for diseases where current options are inadequate. Here, we report the creation of Yucatan miniature pigs with targeted disruptions of the low-density lipoprotein receptor (LDLR) gene in an effort to provide an improved large animal model of familial hypercholesterolemia and atherosclerosis. Yucatan miniature pigs are well established as translational research models because of similarities to humans in physiology, anatomy, genetics, and size. Using recombinant adeno-associated virus-mediated gene targeting and somatic cell nuclear transfer, male and female LDLR+/− pigs were generated. Subsequent breeding of heterozygotes produced LDLR−/− pigs. When fed a standard swine diet (low fat, no cholesterol), LDLR+/− pigs exhibited a moderate, but consistent increase in total and LDL cholesterol, while LDLR−/− pigs had considerably elevated levels. This severe hypercholesterolemia in homozygote animals resulted in atherosclerotic lesions in the coronary arteries and abdominal aorta that resemble human atherosclerosis. These phenotypes were more severe and developed over a shorter time when fed a diet containing natural sources of fat and cholesterol. LDLR-targeted Yucatan miniature pigs offer several advantages over existing large animal models including size, consistency, availability, and versatility. This new model of cardiovascular disease could be an important resource for developing and testing novel detection and treatment strategies for coronary and aortic atherosclerosis and its complications.

The American Pancreatic Association/Hirshberg Foundation Symposium Celebrating the 10th Anniversary of the Seed Grant Program

The Hirshberg Foundation for Pancreatic Cancer Research was founded by Agi Hirshberg in 1997, following her husband Ronald Hirshberg’s 8-month, 7-day battle with the disease. (http://www.pancreatic.org/). At the time, the Hirshberg family viewed pancreatic cancer as the ‘‘unknown enemy’’ (http:// www.pancreatic.org/site/c.htJYJ8MPIwE/b.8276835/k.66CB/ Agi_Hirshbergs_Story.htm). In the years since Ronald Hirshberg’s death, Agi Hirshberg has made it her mission to unmask the unknown for others facing the same enemy. When patients present with a new diagnosis of pancreatic cancer, most are already in an advanced stage of the disease. Pancreatic cancer is resistant to most chemotherapeutic agents and radiotherapy. These factors combine to make pancreatic cancer a highly lethal disease, and according to the National Cancer Institute (NCI) 2013 estimates, pancreatic cancer was diagnosed in approximately 45,220 US citizens, and some 38,460 died of the disease. 1 The Annual Report to the Nation on the Status of Cancer, 1975Y2009, shows that overall cancer death rates continued to decline in the United States among both men and women, among all major racial and ethnic groups, and for all of the many common cancer sites, including lung, colon and rectum, female breast, and prostate. However, this trend does not hold true for pancreatic cancer. The report demonstrates that death rates continued to increase during the latest time period (2000 through 2009) for pancreatic cancer. 2 Only about 23% of patients with cancer of the pancreas will still be living 1 year after diagnosis, and only about 4% will survive 5 years. Even for those diagnosed with pancreatic cancer that has not spread to other organs or systems, the overall 5-year survival rate approaches only 15%. The Hirshberg Foundation’s vision is to advance pancreatic cancer research and provide information, resources, and support to pancreatic cancer patients and their families. The mission of the Foundation is as follows: & To find a cure for pancreatic cancer in honor of Ron Hirshberg and the thousands of people who are diagnosed with this disease each year. & To create a premier Pancreatic Cancer Center where all needs of pancreatic cancer patients can be met in one location with the most advanced treatment options. & To be recognized as a patient support reference source for

Targeted Disruption of LDLR Causes Hypercholesterolemia and Atherosclerosis in Yucatan Miniature Pigs

Targeted Disruption of LDLR Causes Hypercholesterolemia and Atherosclerosis in Yucatan Miniature Pigs

Infrared skin damage thresholds from 1319-nm continuous-wave laser exposures

A series of experiments were conducted in vivo using Yucatan miniature pigs (Sus scrofa domestica) to determine thermal damage thresholds to the skin from 1319-nm continuous-wave Nd:YAG laser irradiation. Experiments employed exposure durations of 0.25, 1.0, 2.5, and 10 s and beam diameters of ∼0.6 and 1 cm. Thermal imagery data provided a time-dependent surface temperature response from the laser. A damage endpoint of fifty percent probability of a minimally visible effect was used to determine threshold for damage at 1 and 24 h postexposure. Predicted thermal response and damage thresholds are compared with a numerical model of optical-thermal interaction. Resultant trends with respect to exposure duration and beam diameter are compared with current standardized exposure limits for laser safety. Mathematical modeling agreed well with experimental data, predicting that though laser safety standards are sufficient for exposures <10 s, they may become less safe for very long exposures.