Management of acute-onset pancreatitis in dogs: a Narrative Review.

Acute-onset pancreatitis (AP) is common in dogs and presents diagnostic as well as management challenges. Until recently, the management of AP in dogs was based mainly on supportive and symptomatic care. Identification and management of a possible cause of the disease is important, but the majority of cases are considered to be idiopathic. Fluid therapy that is tailored to the patient's needs is crucial to provide adequate hydration while preventing overhydration. Antiemetics are required to control vomiting and fluid loss and aid in early nutritional support. Recognition and management of complications is also crucial. Furthermore, analgesics for abdominal pain are very important. More recently, pharmaceutical modification of the inflammatory cascade has gained interest and the first specific therapeutic agent for the treatment of AP, fuzapladib sodium, has been shown to have a reasonable expectation of effectiveness in a pilot study. This drug has been licensed for the treatment of clinical signs of AP in dogs in Japan and also has achieved FDA conditional approval in the US. Antibiotics should not be used indiscriminately but are indicated for patients with aspiration pneumonia, gastrointestinal bacterial translocation, or evidence of another bacterial infection. Proton pump inhibitors and plasma are not routinely prescribed in pancreatitis unless specifically indicated. Nonsteroidal anti-inflammatory drugs should be avoided. Corticosteroid therapy, once thought to be contraindicated, may have some beneficial effects, as shown in a single retrospective study. However, further studies are required before their routine use can be recommended. Finally, a surgical approach is rarely indicated.

Long-term outcome in patients with nodal-positive breast cancer treated with sentinel lymph node biopsy alone after neoadjuvant chemotherapy.

PURPOSE: Sentinel lymph node biopsy (SLNB) has yet to be accepted as the standard staging procedure in node positive (cN1) breast cancer patients who had clinical complete response in the axilla (cN0) following neoadjuvant chemotherapy (NAC), due to the presumed high false negative rate associated with SLNB in such scenario. This study aimed to determine whether there is a significant difference in the axillary recurrence rate (ARR) and long-term survival in this group of patients, receiving SLNB alone versus axillary lymph node dissection (ALND). METHODS: A retrospective cohort of cN1 patients who were rendered cN0 by NAC from January 2014 to December 2018 were identified from the Asan Medical Center database. Patients' characteristics and outcomes were collected and analyzed. RESULTS: 902 cN1 patients treated with NAC and turned cN0 were identified. 477 (52.9%) patients achieved complete pathological response in the axilla (ypN0). At a median follow up of 65 months, ARR was 3.2% in the SLNB only group and 1.8% in the ALND group (p = 0.398). DFS and OS were significantly worse in patients with ALND as compared to patients with SLNB only (p = 0.011 and 0.047, respectively). We noted more patients in the ALND group had T3-4 tumor. In the subgroup analysis, we showed that in the T1-2 subgroup (n = 377), there was no statistically significant difference in DFS and OS (p = 0.242 and 0.671, respectively) between SLNB only and ALND group. CONCLUSION: Our findings suggest that cN1 patients who were converted to ypN0 following NAC may be safely treated with SLNB only.

Integration of xeno-free single-cell cloning in CRISPR-mediated DNA editing of human iPSCs improves homogeneity and methodological efficiency of cellular disease modeling.

The capability to generate induced pluripotent stem cell (iPSC) lines, in tandem with CRISPR-Cas9 DNA editing, offers great promise to understand the underlying genetic mechanisms of human disease. The low efficiency of available methods for homogeneous expansion of singularized CRISPR-transfected iPSCs necessitates the coculture of transfected cells in mixed populations and/or on feeder layers. Consequently, edited cells must be purified using labor-intensive screening and selection, culminating in inefficient editing. Here, we provide a xeno-free method for single-cell cloning of CRISPRed iPSCs achieving a clonal survival of up to 70% within 7-10 days. This is accomplished through improved viability of the transfected cells, paralleled with provision of an enriched environment for the robust establishment and proliferation of singularized iPSC clones. Enhanced cell survival was accompanied by a high transfection efficiency exceeding 97%, and editing efficiencies of 50%-65% for NHEJ and 10% for HDR, indicative of the method's utility in stem cell disease modeling.

Examining the exposure-reception-retention link in realistic communication environments via VR and eye-tracking: The VR billboard paradigm.

Exposure is key to message effects. No effects can ensue if a health, political, or commercial message is not noticed. Yet, existing research in communication, advertising, and related disciplines often measures 'opportunities for exposure' at an aggregate level, whereas knowing whether recipients were 'actually exposed' to a message requires a micro-level approach. Micro-level research, on the other hand, focuses on message processing and retention, takes place under highly controlled laboratory conditions with forced message exposure, and largely ignores how recipients attend selectively to messages under more natural conditions. Eye-tracking enables us to assess actual exposure, but its previous applications were restricted to screen-based reading paradigms lacking ecological validity or field studies that suffer from limited experimental control. Our solution is to measure eye-tracking within an immersive VR environment that creates the message delivery and reception context. Specifically, we simulate a car ride down a highway alongside which billboards are placed. The VR headset (HP Omnicept Pro) provides an interactive 3D view of the environment and holds a seamlessly integrated binocular eye tracker that records the drivers' gaze and detects all fixations on the billboards. This allows us to quantify the nexus between exposure and reception rigorously, and to link our measures to subsequent memory, i.e., whether messages were remembered, forgotten, or not even encoded. An empirical study shows that incidental memory for messages differs based on participants' gaze behavior while passing the billboards. The study further shows how an experimental manipulation of attentional demands directly impacts drivers' gaze behavior and memory. We discuss the large potential of this paradigm to quantify exposure and message reception in realistic communication environments and the equally promising applications in new media contexts (e.g., the Metaverse).

Role of Pellino-1 in Inflammation and Cardioprotection following Severe Sepsis: A Novel Mechanism in a Murine Severe Sepsis Model †.

OBJECTIVES: Intra-abdominal sepsis is commonly diagnosed in the surgical population and remains the second most common cause of sepsis overall. Sepsis-related mortality remains a significant burden in the intensive care unit despite advances in critical care. Nearly a quarter of the deaths in people with heart failure are caused by sepsis. We have observed that overexpression of mammalian Pellino-1 (Peli1), an E3 ubiquitin ligase, causes inhibition of apoptosis, oxidative stress, and preservation of cardiac function in a myocardial infarction model. Given these manifold applications, we investigated the role of Peli1 in sepsis using transgenic and knockout mouse models specific to this protein. Therefore, we aimed to explore further the myocardial dysfunction seen in sepsis through its relation to the Peli 1 protein by using the loss of function and gain-of-function strategy. METHODS: A series of genetic animals were created to understand the role of Peli1 in sepsis and the preservation of heart function. Wild-type, global Peli1 knock out (Peli1-/-), cardiomyocyte-specific Peli1 deletion (CP1KO), and cardiomyocyte-specific Peli1 overexpressing (alpha MHC (αMHC) Peli1; AMPEL1Tg/+) animals were divided into sham and cecal ligation and puncture (CLP) surgical procedure groups. Cardiac function was determined by two-dimensional echocardiography pre-surgery and at 6- and 24-h post-surgery. Serum IL-6 and TNF-alpha levels (ELISA) (6 h), cardiac apoptosis (TUNEL assay), and Bax expression (24 h) post-surgery were measured. Results are expressed as mean ± S.E.M. RESULTS: AMPEL1Tg/+ prevents sepsis-induced cardiac dysfunction assessed by echocardiographic analysis, whereas global and cardiomyocyte-specific deletion of Peli1 shows significant deterioration of cardiac functions. Cardiac function was similar across the sham groups in all three genetically modified mice. ELISA assay displayed how Peli 1 overexpression decreased cardo-suppressive circulating inflammatory cytokines (TNF-alpha, IL-6) compared to both the knockout groups. The proportion of TUNEL-positive cells varied according to Peli1 expression, with overexpression (AMPEL1Tg/+) leading to a significant reduction and Peli1 gene knockout (Peli1-/- and CP1KO) leading to a significant increase in their presence. A similar trend was also observed with Bax protein expression. The improved cellular survival associated with Peli1 overexpression was again shown with the reduction of oxidative stress marker 4-Hydroxy-2-Nonenal (4-HNE). CONCLUSION: Our results indicate that overexpression of Peli1 is a novel approach that not only preserved cardiac function but reduced inflammatory markers and apoptosis following severe sepsis in a murine genetic model.

Encapsulated papillary carcinoma of the breast: An institutional case series and literature review.

BACKGROUND: Encapsulated papillary carcinoma of the breast is rare, making difficult diagnosis and resulting in patients undergoing excision biopsy before definitive surgery. Evidence-based guidelines are sparse. We would like to further elucidate the clinicopathological, treatment and survival outcomes. MATERIALS AND METHODS: 54 patients identified, with a median follow up duration of 48 months. Patients' demographics, radiological and clinicopathological characteristics, treatment, adjuvant therapies as well as survival data were analysed. RESULTS: 18 (33.3%) cases were pure EPC, 12 (22.2%) were EPC associated with ductal carcinoma in situ (DCIS) and 24 (44.4%) cases had concurrent invasive ductal carcinoma. EPCs were more likely to present as a solid-cystic mass on sonography (63.8%), regular-shaped (oval or round) (97.9%), lack spiculations (95.7%) and lack suspicious microcalcifications (95.6%). Median tumour size was largest in the EPC with IDC group (18.5 mm). 2 patients developed loco-regional recurrence. Overall survival is good for EPCs of all subtypes. CONCLUSION: EPC is a rare tumour with excellent prognosis.

First Analysis of Nationwide Trends in the Use of the SNAP-Ed Evaluation Framework.

OBJECTIVE: To understand Supplemental Nutrition Assistance Program-Education (SNAP-Ed) Implementing Agencies'(SIAs) use of the SNAP-Ed Evaluation Framework (Framework), which is a tool that includes 51 indicators that SNAP-Ed programs can use to measure the success of their programs in the first 5 years after its release. METHODS: A repeated cross-sectional study design was utilized to administer electronic surveys to between 124 and 154 SIAs who received SNAP-Ed funding in fiscal years 2017, 2019, and 2021. Analyses included descriptive statistics and tests of proportions. RESULTS: Most SIAs indicated that they used the Framework to inform both data collection instruments and program planning decisions and the rates remained relatively constant over the 3 time points (> 80%). The most common specific use of the Framework across all 3 time points was to define, count, or measure the work accomplished, but this statistically decreased from 2017 (76%) to 2021 (57%) (z-score = 3.31; P < 0.001). CONCLUSIONS AND IMPLICATIONS: The results of this analysis confirmed that 5 years after its introduction, uptake and use of the Framework was high and that, as a whole, SIAs focused on priority indicators set by the US Department of Agriculture, with no notable increases in addressing and measuring longer-term, multisector, and population-wide outcomes. The systematic study of the Framework's usability over time has a broader application to other national health promotion initiatives with shared frameworks.

Retrotransposon instability dominates the acquired mutation landscape of mouse induced pluripotent stem cells.

Induced pluripotent stem cells (iPSCs) can in principle differentiate into any cell of the body, and have revolutionized biomedical research and regenerative medicine. Unlike their human counterparts, mouse iPSCs (miPSCs) are reported to silence transposable elements and prevent transposable element-mediated mutagenesis. Here we apply short-read or Oxford Nanopore Technologies long-read genome sequencing to 38 bulk miPSC lines reprogrammed from 10 parental cell types, and 18 single-cell miPSC clones. While single nucleotide variants and structural variants restricted to miPSCs are rare, we find 83 de novo transposable element insertions, including examples intronic to Brca1 and Dmd. LINE-1 retrotransposons are profoundly hypomethylated in miPSCs, beyond other transposable elements and the genome overall, and harbor alternative protein-coding gene promoters. We show that treatment with the LINE-1 inhibitor lamivudine does not hinder reprogramming and efficiently blocks endogenous retrotransposition, as detected by long-read genome sequencing. These experiments reveal the complete spectrum and potential significance of mutations acquired by miPSCs.

Use of Combination of Oral Levothyroxine and Liothyronine in Severe Hypothyroidism With Massive Pericardial Effusion.

Thyroid hormone plays an important role in cardiovascular function. Pericardial effusions are commonly seen in cases of severe hypothyroidism. However, large to massive pericardial effusions with cardiac tamponade are exceptionally rare. Herein, we present two cases of severe hypothyroidism with massive pericardial effusion. Our first case demonstrates that a patient with large pericardial effusion can be managed conservatively with aggressive thyroid hormone replacement therapy. In our second case, pericardiocentesis was performed in addition to thyroid hormone replacement therapy as the underlying aetiology of effusion could not be reasonably limited to hypothyroidism. These two cases served to highlight and demonstrate rapid normalisation of thyroid function test by using aggressive oral thyroid hormone replacement therapy using liothyronine, in combination with levothyroxine, which led to resolution of pericardial effusion and prevent its re-accumulation.

Understanding lipase assays in the diagnosis of pancreatitis in veterinary medicine.

Pancreatitis commonly occurs in humans, dogs, and cats. For both veterinary and human health-care professionals, measurement of serum pancreatic lipase concentration or activity provides useful support for a diagnosis of pancreatitis. In this Currents in One Health manuscript, we will discuss commonly used lipase assays in veterinary medicine, namely catalytic colorimetric and immunological lipase assays. We highlight potential diagnostic pitfalls associated with analytical specificity, assay validation, and sample condition interferences. Catalytic lipase assays may detect extrapancreatic lipases. In addition, we propose a decision tree for interpretation of lipase assays in the context of a clinical patient.

A Clinical Risk Assessment of a 3D-Printed Patient-Specific Scaffold by Failure Modes and Effects Analysis.

This study aims to carry out a risk assessment to identify and rectify potential clinical risks of a 3D-printed patient-specific scaffold for large-volume alveolar bone regeneration. A survey was used to assess clinicians' perceptions regarding the use of scaffolds in the treatment of alveolar defects and conduct a clinical risk assessment of the developed scaffold using the Failure Modes and Effects Analysis (FMEA) framework. The response rate was 69.4% with a total of 41 responses received. Two particular failure modes were identified as a high priority through the clinical risk assessment conducted. The highest mean Risk Priority Number was obtained by "failure of healing due to patient risk factors" (45.7 ± 27.7), followed by "insufficient soft tissue area" (37.8 ± 24.1). Despite the rapid developments, finding a scaffold that is both biodegradable and tailored to the patient's specific defect in cases of large-volume bone regeneration is still challenging for clinicians. Our results indicate a positive perception of clinicians towards this novel scaffold. The FMEA clinical risk assessment has revealed two failure modes that should be prioritized for risk mitigation (safe clinical translation). These findings are important for the safe transition to in-human trials and subsequent clinical use.

Lipases: it's not just pancreatic lipase!

Lipases are water-soluble enzymes that hydrolyze water-insoluble lipid molecules, such as triglycerides, phospholipids, and galactolipids. They are ubiquitous in nature and are present in humans, animals, insects, plants, fungi, and microorganisms. While we commonly consider pancreatic lipase, this review provides an overview of several lipases that are important for the digestion and metabolism of lipids in veterinary species. All of these enzymes have specific functions but share a common α/ß-hydrolase fold and a catalytic triad where substrate hydrolysis occurs. The pancreatic lipase gene family is one of the best characterized lipase gene families and consists of 7 mammalian subfamilies: pancreatic lipase, pancreatic lipase related proteins 1 and 2, hepatic lipase, lipoprotein lipase, endothelial lipase, and phosphatidylserine phospholipase A1. Other mammalian lipases that play integral roles in lipid digestion include carboxyl ester lipase and gastric lipase. Although most enzymes have preferred substrate specificity, much overlap occurs across the plethora of lipases because of the similarities in their structures. This has major implications for the development and clinical utilization of diagnostic assays. These implications are further explored in our companion Currents in One Health article by Lim et al in the August 2022 issue of the Journal of American Veterinary Medical Association, which focuses on pancreatic lipase assays for the diagnosis of pancreatitis.

Protective Effect of Cardiomyocyte-Specific Prolyl-4-Hydroxylase 2 Inhibition on Ischemic Injury in a Mouse MI Model.

BACKGROUND: Our earlier studies showed that inhibiting prolyl-4-hydroxylase enzymes (PHD-1 and PHD-3) improves angiogenesis, heart function, and limb perfusion in mouse models via stabilizing hypoxia-inducible transcription factor-alpha (HIF-1α). The present study explored the effects of the prolyl-4-hydroxylase enzyme, PHD-2, on ischemic heart failure using cardiac-specific PHD-2 gene knockout (KO) mice (PHD2 -/- ). STUDY DESIGN: Adult wild-type (WT) and PHD2 -/- mice, 8-12 weeks old, were subjected to myocardial infarction (MI) by irreversibly ligating the left anterior descending (LAD) coronary artery. All sham group mice underwent surgery without LAD ligation. Animals were divided into 4 groups: (1) wild-type sham (WTS); (2) wild-type myocardial infarction (WTMI); (3) PHD2KO sham (PHD2 -/- S); (4) PHD2KO myocardial infarction (PHD2 -/- MI). Left ventricular tissue samples collected at various time points after surgery were used for microRNA expression profiling, Western blotting, and immunohistochemical analysis. RESULTS: Volcano plot analysis revealed 19 differentially-expressed miRNAs in the PHD2 -/- MI group compared with the WTMI group. Target analysis using Ingenuity Pathway Analysis showed several differentially regulated miRNAs targeting key signaling pathways such as Akt, VEGF, Ang-1, PTEN, apoptosis, and hypoxia pathways. Western blot analysis showed increased HIF-1α, VEGF, phospho-AKT, ß-catenin expression and reduced Bax expression for the PHD2 -/- MI group compared with the WTMI group. Echocardiographic analysis showed preserved heart functions, and picrosirius red staining revealed decreased fibrosis in PHD2 -/- MI compared with the WTMI group. CONCLUSIONS: PHD2 inhibition showed preserved heart function, enhanced angiogenic factor expression, and decreased apoptotic markers after MI. Overall, cardiac PHD2 gene inhibition is a promising candidate for managing cardiovascular diseases.

New insights into the etiology, risk factors, and pathogenesis of pancreatitis in dogs: Potential impacts on clinical practice.

While most cases of pancreatitis in dogs are thought to be idiopathic, potential risk factors are identified. In this article we provide a state-of-the-art overview of suspected risk factors for pancreatitis in dogs, allowing for improved awareness and detection of potential dog-specific risk factors, which might guide the development of disease prevention strategies. Additionally, we review important advances in our understanding of the pathophysiology of pancreatitis and potential areas for therapeutic manipulation based thereof. The outcome of pathophysiologic mechanisms and the development of clinical disease is dependent on the balance between stressors and protective mechanisms, which can be evaluated using the critical threshold theory.

The Impact of Statin Use and Breast Cancer Recurrence - A Retrospective Study in Singapore.

Introduction: Statins, HMG-CoA reductase inhibitors, are commonly used cholesterol-lowering medications which are also increasingly recognized to have anti-cancer properties for various cancers, including breast cancer. Most clinical evidence supports a protective effect of statin on reducing breast cancer recurrence, particularly in hormone-receptor positive breast cancers.This study seeks to study the impact of statin use on breast cancer recurrence in an Asian population. Methods: This is a retrospective study of patients diagnosed with breast cancer at the National Cancer Centre and Singapore General Hospital from 2005-2015. Statin use was defined as use after surgery. Associations between statin use, breast cancer recurrence and overall survival were estimated using Cox proportional hazards regression with adjustment for age, TNM stage, grade, ER/HER2 status, and co-morbidities. Associations between statin-use and disease-specific survival were estimated using competing risks regression. Results: A total of 7858 females with breast cancer were studied, 1353(17.2%) were statin users, 6505(82.8%) were non-statin users, with a median follow-up of 8.67 years. Distribution of cancer stage, histology, molecular subtypes and grades were similar in both groups. Estrogen receptor(ER) positive (HR 0.57,95%CI 0.43-0.76,p<0.001) and HER2 negative (HR 0.74,95%CI 0.57-0.96,p=0.026) invasive cancers had a lower risk of recurrence in statin users. Statin users trended towards a long term recurrence-risk reduction (all subtypes,HR 0.48,p=0.002; ER-, HR 0.34,p=0.036; HER2+,HR 0.10,p=0.002). The risk-reduction benefit is not appreciated in statin users with DCIS, possibly due to small recurrence event numbers. Disease-specific survival benefit was seen in statin users with ER+ cancers (adjusted SHR 0.71,95%CI 0.53-0.96,p=0.027), especially ER+ invasive cancers (adjusted SHR 0.72, 95%CI 0.53-0.97,p=0.028), but with no statistically significant benefit in overall survival for statin users (all subtypes). Conclusion: This is the first known retrospective study on the effect of statin use and breast cancer recurrence in an Asian population. Similar to previous international studies, statin use is associated with a risk reduction in breast cancer recurrence. This is especially beneficial in patients who have ER+ and HER2- invasive breast cancer. Statin use is also associated with a reduced risk of breast cancer recurrence in all subtypes of breast cancer in the long term (>6 years post diagnosis).

Male breast cancer: a Singapore perspective.

INTRODUCTION: Male breast cancer (MBC) is rare, representing <1% of all breast cancers. Treatment recommendations have been extrapolated from trial data of female breast cancer patients. This study aims to report our institutional experience of MBC across a 20 year period, analyse the survival outcome and prognosis of this group against female breast cancer patients treated at the same centre. METHODS: Clinical, histopathological, treatment and survival data of male and female breast cancer patients treated between Jan 1999 and July 2019 at Singapore General Hospital and National Cancer Centre Singapore were identified and analysed. RESULTS: Fifty-seven male patients were identified. The median age at diagnosis was 63 years. Majority had invasive ductal carcinoma (86%) and presented at an early disease stage: 70.2% presented as Tis/T1/T2 and 49.1% had no axillary nodal involvement. 84.2% had a simple mastectomy with either a sentinel lymph node biopsy or axillary clearance. The median follow up was 5.69 years for males and 5.83 years for females. The median survival was 11.86 years for males and 16.3 years for females. At 5 years, overall survival (OS) was 69.9% (52.3-82.1%) and disease free survival (DFS) was 62.9% (44.9-76.5%) for males compared with OS 83.8% (83.21-84.39%) and DFS 74.5% (73.91-75.09%) for females. CONCLUSION: MBC remains understudied. Our institutional data indicates that good long term survival in South-East Asian patients can be achieved with treatment protocols that are similar to female breast cancer. More prospective studies are required.

Atypical Ductal Hyperplasia of the Breast on Core Needle Biopsy: Risk of Malignant Upgrade on Surgical Excision.

PURPOSE: This study identified factors predicting malignant upgrade for atypical ductal hyperplasia (ADH) diagnosed on core-needle biopsy (CNB) and developed a nomogram to facilitate evidence-based decision making. METHODS: This retrospective analysis included women diagnosed with ADH at the National Cancer Centre Singapore (NCCS) in 2010-2015. Cox proportional hazards regression was used to identify clinical, radiological, and histological factors associated with malignant upgrade. A nomogram was constructed using variables with the strongest associations in multivariate analysis. Multivariable logistic regression coefficients were used to estimate the predicted probability of upgrade for each factor combination. RESULTS: Between 2010 and 2015, 238,122 women underwent mammographic screening under the National Breast Cancer Screening Program. Among 29,564 women recalled, 5,971 CNBs were performed. Of these, 2,876 underwent CNBs at NCCS, with 88 patients (90 lesions) diagnosed with ADH and 26 lesions upgraded to breast malignancy on excision biopsy. In univariate analysis, factors associated with malignant upgrade were the presence of a mass on ultrasound (p = 0.018) or mammography (p = 0.026), microcalcifications (p = 0.047), diffuse microcalcification distribution (p = 0.034), mammographic parenchymal density (p = 0.008). and ≥ 3 separate ADH foci found on biopsy (p = 0.024). Mammographic parenchymal density (hazard ratio [HR], 0.04; 95% confidence interval [CI], 0.005-0.35; p = 0.014), presence of a mass on ultrasound (HR, 10.50; 95% CI, 9.21-25.2; p = 0.010), and number of ADH foci (HR, 1.877; 95% CI, 1.831-1.920; p = 0.002) remained significant in multivariate analysis and were included in the nomogram. CONCLUSION: Our model provided good discrimination of breast cancer risk prediction (C-statistic of 0.81; 95% CI, 0.74-0.88) and selected for a subset of women at low risk (2.1%) of malignant upgrade, who may avoid surgical excision following a CNB diagnosis of ADH.

Gene therapy with Pellino-1 improves perfusion and decreases tissue loss in Flk-1 heterozygous mice but fails in MAPKAP Kinase-2 knockout murine hind limb ischemia model.

OBJECTIVES: In the United States, over 8.5 million people suffer from peripheral arterial disease (PAD). Previously we reported that Pellino-1(Peli1) gene therapy reduces ischemic damage in the myocardium and skin flaps in Flk-1 [Fetal Liver kinase receptor-1 (Flk-1)/ Vascular endothelial growth factor receptor-2/VEGFR2] heterozygous (Flk-1+/--) mice. The present study compares the angiogenic response and perfusion efficiency following hind limb ischemia (HLI) in, Flk-1+/- and, MAPKAPKINASE2 (MK2-/-) knockout (KO) mice to their control wild type (WT). We also demonstrated the use of Peli1 gene therapy to improve loss of function following HLI. STUDY DESIGN AND METHODS: Femoral artery ligation (HLI) was performed in both Flk-1+/- and MK2-/- mice along with their corresponding WT. Another set of Flk-1+/- and MK2-/- were injected with either Adeno-LacZ (Ad.LacZ) or Adeno-Peli1 (Ad.Peli1) after HLI. Hind limb perfusion was assessed by laser doppler imaging at specific time points. A standardized scoring scale is used to quantify the extent of ischemia. Histology analysis performed includes capillary density, fibrosis, pro-angiogenic and anti-apoptotic proteins. RESULTS: Flk-1+/- and MK2-/- had a slower recovery of perfusion efficiency in the ischemic limbs than controls. Both Flk-1+/- and MK2-/- KO mice showed decreased capillary density and capillary myocyte ratios with increased fibrosis than their corresponding wild types. Ad.Peli1 injected ischemic Flk-1+/- limb showed improved perfusion, increased capillary density, and pro-angiogenic molecules with reduced fibrosis compared to Ad.LacZ group. No significant improvement in perfusion was observed in MK2-/- ischemic limb after Ad. Peli1 injection. CONCLUSION: Deletion of Flk-1 and MK2 impairs neovascularization and perfusion following HLI. Treatment with Ad. Peli1 results in increased angiogenesis and improved perfusion in Flk-1+/- mice but fails to rectify perfusion in MK2 KO mice. Overall, Peli1 gene therapy is a promising candidate for the treatment of PAD.