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Small Animal Models (small + animal_models)
Selected AbstractsHuman islet cell transplantation , future prospectsDIABETIC MEDICINE, Issue 2 2001S. A. White Summary Background Islet transplantation has the potential to cure diabetes mellitus. Nevertheless despite successful reversal of diabetes in many small animal models, the clinical situation has been far more challenging. The aim of this review is to discuss why insulin-independence after islet allotransplantation has been so difficult to achieve. Methods A literature review was undertaken using Medline from 1975 to July 2000. Results reported to the International Islet Transplant Registry (ITR) up to December 1998 were also analysed. Results Up to December 1998, 405 islet allotransplants have been reported the ITR. Of those accurately documented between 1990 and 1998 (n = 267) only 12% have achieved insulin-independence (greater than 7 days). However with refined peri-transplant protocols insulin indepedence at 1 year can reach 20%. Conclusions There are many factors which can explain the failure of achieving insulin-independence after islet allotransplantation. These include the use of diabetogenic immunosuppressive agents to abrogate both islet allo-immunity and auto-immunity, the critical islet mass to achieve insulin-independence and the detrimental effects of transplanting islets in an ectopic site. However recent evidence most notably from the Edmonton group demonstrates that islet allotransplantation still has great potential to become an established treatment option for diabetic patients. [source] Fetal Mouse Imaging Using Echocardiography: A Review of Current TechnologyECHOCARDIOGRAPHY, Issue 10 2006Christopher F. Spurney M.D. Advances in genetic research have led to the need for phenotypic analysis of small animal models. However, often these genetic alterations, especially when affecting the cardiovascular system, can result in fetal or perinatal death. Noninvasive ultrasound imaging is an ideal method for detecting and studying such congenital malformations, as it allows early recognition of abnormalities in the living fetus and the progression of disease can be followed in utero with longitudinal studies. Two platforms for fetal mouse echocardiography exist, the clinical systems with 15-MHz phased array transducers and research systems with 20,55-MHz mechanical transducers. The clinical ultrasound system has limited two-dimensional (2D) resolution (axial resolution of 440 ,m), but the availability of color and spectral Doppler allows quick interrogations of blood flows, facilitating the detection of structural abnormalities. M-mode imaging further provides important functional data, although, the proper imaging planes are often difficult to obtain. In comparison, the research biomicroscope system has significantly improved 2D resolution (axial resolution of 28 ,m). Spectral Doppler imaging is also available, but in the absence of color Doppler, imaging times are increased and the detection of flow abnormalities is more difficult. M-mode imaging is available and equivalent to the clinical ultrasound system. Overall, the research system, given its higher 2D resolution, is best suited for in-depth analysis of mouse fetal cardiovascular structure and function, while the clinical ultrasound systems, equipped with phase array transducers and color Doppler imaging, are ideal for high-throughput fetal cardiovascular screens. [source] Age-Related Increase in Atrial Fibrillation Induced by Transvenous Catheter-Based Atrial Burst Pacing: An In Vivo Rat Model of Inducible Atrial FibrillationJOURNAL OF CARDIOVASCULAR ELECTROPHYSIOLOGY, Issue 1 2010DONGZHU XU M.D. AF Rat Model Induced by Transvenous Catheter Pacing.,Introduction: Large animal models of atrial fibrillation (AF) are well established, but limited experimental reports exist on small animal models. We sought to develop an in vivo rat model of AF using a transvenous catheter and to evaluate the model's underlying characteristics. Methods and Results: Echocardiogram, surface electrocardiogram (ECG), and atrial effective refractory period (AERP) were recorded at baseline in young (3 months) and middle-aged (9 months) Wistar rats. AF inducibility and duration were measured through transvenous electrode catheter in young (n = 11) and middle-aged rats (n = 11) and middle-aged rats treated with either pilsicainide (1 mg/kg iv, n = 7) or amiodarone (10 mg/kg iv, n = 9). Degrees of interstitial fibrosis and cellular hypertrophy in the atria were assessed histologically. The P-wave duration and AERP were significantly longer and echocardiographic left atrial dimension significantly larger in middle-aged versus young rats. AF was inducible in >90% of all procedures in both untreated rat groups, whereas AF inducibility was reduced by the antiarrhythmic drugs. The AF duration was significantly longer in middle-aged than in young rats and was significantly shortened by treatment with either pilsicainide or amiodarone. Histologic analysis revealed significant increases in atrial interstitial fibrosis and cellular diameter in middle-aged versus young rats. Conclusions: Transvenous catheter-based AF is significantly longer in middle-aged than in young rats and is markedly reduced by treatment with antiarrhythmic drugs. This rat model of AF is simple, reproducible, and reliable for examining pharmacologic effects on AF and studying the process of atrial remodeling.(J Cardiovasc Electrophysiol, Vol. 21, pp. 88,93, January 2010) [source] Blood velocity assessment using 3D bright-blood time-resolved magnetic resonance angiographyMAGNETIC RESONANCE IN MEDICINE, Issue 3 2006Sylvain Miraux Abstract Blood velocity is a functional parameter that is not easily assessed noninvasively, especially in small animals. A new noninvasive method that uses magnetic resonance angiography (MRA) to measure blood flows is proposed. This method is based on the time-of-flight (TOF) phenomenon. By initially suppressing the signal from the stationary spins in the area of interest, it is possible to sequentially visualize only the signal from the moving spins entering a given volume. With this method, 3D cine images of the blood flow can be generated by positive contrast, with unparalleled spatial (<200 ,m) and temporal resolutions (<10 ms/image). As a result, it is possible to measure flow in sinuous paths. The present method was applied in vivo to measure the blood velocity in mouse carotid arteries. Because of its robustness and simplicity of implementation, this method has numerous potential applications for fundamental studies in small animal models. Magn Reson Med, 2006. © 2006 Wiley-Liss, Inc. [source] Antibody-Mediated Rejection: Emergence of Animal Models to Answer Clinical QuestionsAMERICAN JOURNAL OF TRANSPLANTATION, Issue 5 2010William M. Baldwin III Decades of experiments in small animals had tipped the balance of opinion away from antibodies as a cause of transplant rejection. However, clinical experience, especially with sensitized patients, has convinced basic immunologists of the need to develop models to investigate mechanisms underlying antibody-mediated rejection (AMR). This resurgent interest has resulted in several new rodent models to investigate antibody-mediated mechanisms of heart and renal allograft injury, but satisfactory models of chronic AMR remain more elusive. Nevertheless, these new studies have begun to reveal many insights into the molecular and pathological sequelae of antibody binding to the allograft endothelium. In addition, complement-independent and complement-dependent effects of antibodies on endothelial cells have been identified in vitro. As small animal models become better defined, it is anticipated that they will be more widely used to answer further questions concerning mechanisms of antibody-mediated tissue injury as well as to design therapeutic interventions. [source] | ||||||||||