The clopidogrel after surgery for coronary artery disease (CASCADE) randomized controlled trial: clopidogrel and aspirin versus aspirin alone after coronary bypass surgery [NCT00228423]

Background

Saphenous vein graft disease remains a major limitation of coronary artery bypass graft surgery. The process of saphenous vein intimal hyperplasia begins just days after surgical revascularization, setting the stage for graft atherosclerotic disease and its sequalae. Clopidogrel improves outcomes in patients with atherosclerotic disease, and is effective at reducing intimal hyperplasia in animal models of thrombosis. Therefore, the goal of this study will be to evaluate the efficacy of clopidogrel and aspirin therapy versus aspirin alone in the prevention of saphenous vein graft intimal hyperplasia following coronary artery bypass surgery.

Methods

Patients undergoing multi-vessel coronary artery bypass grafting and in whom at least two saphenous vein grafts will be used are eligible for the study. Patients will be randomized to receive daily clopidogrel 75 mg or placebo, in addition to daily aspirin 162 mg, for a one year duration starting on the day of surgery (as soon as postoperative bleeding has been excluded). At the end of one year, all patients will undergo coronary angiography and intravascular ultrasound assessment of one saphenous vein graft as selected by randomization. The trial will be powered to test the hypothesis that clopidogrel and aspirin will reduce vein graft intimal hyperplasia by 20% compared to aspirin alone at one year following bypass surgery.

Discussion

This trial is the first prospective human study that will address the question of whether clopidogrel therapy improves outcomes and reduces saphenous vein graft intimal hyperplasia following cardiac surgery. Should the combination of clopidogrel and aspirin reduce the process of vein graft intimal hyperplasia, the results of this study will help redefine modern antiplatelet management of coronary artery bypass patients.     

The non-human primate oocyte and embryo as a model for women, or is it vice versa?

The role of the non-human primate (NHP) oocyte and embryo in translational research is considered here including both in vitro activities directly involving oocytes or embryos as well as animal studies that impact reproductive function. Reasons to consider NHPs as animal research models along with their limitations are summarized. A case is made that in limited instances, such as in the development and application of the assisted reproductive technologies or in the study of embryonic stem cells, the human oocyte and embryo have acted as models for the monkey. The development of strategies for the preservation of fertility is used as an example of ongoing research in the non-human primate that cannot be conducted in women for ethical reasons. In animal studies, monitoring reproductive potential, responses to embryonic stem cell transplantation, along with translational research in the field of contraceptive development for women are considered as subjects that benefit from the availability of a NHP model.     

Egr-1的诱骗性寡脱氧核苷酸抑制大鼠颈总动脉损伤后MMP-2的表达

目的观察局部转染早期生长反应因子-1(early growth response factor-1,Egr-1)的特异诱骗寡脱氧核苷酸(decoy oligodeoxynucleotides,decoy ODNs)对球囊损伤颈总动脉后基质金属蛋白酶-2(MMP-2)蛋白表达的影响及内膜增生的情况,初步探讨Egr-1,decoy ODNs抑制球囊损伤后内膜增生的机制。方法 96只健康雄性Wistar大鼠,随机分为4组,分别为假手术组、对照组、杂码组和诱骗组,每组24只。除假手术组外均应用2F球囊导管行颈总动脉球囊损伤术,术中采用转染试剂FuGENE6介导的Egr-1decoy ODNs转染至损伤后大鼠血管中,与假手术组、对照组、杂码组相比较。术后3、7、14、21d每组处死6只动物。应用HE染色和免疫组织化学方法观察大鼠颈总动脉球囊损伤后内膜增生情况和MMP-2蛋白的表达及转染Egr-1decoy ODNs后对它们的影响。结果 (1)、内膜损伤后3d内膜增厚不明显,7d内膜开始增厚,14、21d时内膜明显增厚。(2)、在假手术组近腔面中膜可见MMP-2有少量散在阳性表达;在对照组及杂码组动脉损伤后3d,在近腔面中膜,有少量阳性表达,与假手术组相比,阳性表达指数上升。7d时在新生内膜和靠近新生内膜处中膜表达明显,14d后表达逐渐下降。(3)转染decoy ODNs治疗后,在各个时间点内膜增厚程度减轻,MMP-2蛋白表达减少,与对照组比较差异有显著性(P<0.01)。结论血管球囊损伤后,内膜7d开始增生,14d、21d增生更明显,而MMP-2在7d时表达明显,之后逐渐下降,Egr-1decoy ODNs能抑制MMP-2的表达,从而减轻血管损伤后内膜的增生。     

Default Mode Network,Motor Network,Dorsal and Ventral Basal Ganglia Networks in the Rat Brain: Comparison to Human Networks Using Resting State-fMRI

Rodent models are developed to enhance understanding of the underlying biology of different brain disorders. However, before interpreting findings from animal models in a translational aspect to understand human disease, a fundamental step is to first have knowledge of similarities and differences of the biological systems studied. In this study, we analyzed and verified four known networks termed: default mode network, motor network, dorsal basal ganglia network, and ventral basal ganglia network using resting state functional MRI (rsfMRI) in humans and rats. Our work supports the notion that humans and rats have common robust resting state brain networks and that rsfMRI can be used as a translational tool when validating animal models of brain disorders. In the future, rsfMRI may be used, in addition to short-term interventions, to characterize longitudinal effects on functional brain networks after long-term intervention in humans and rats.     

Somatostatin receptor subtype expression and function in human vascular tissue

In animal models the somatostatin analog angiopeptin inhibits intimal hyperplasia by acting primarily through somatostatin receptor 2 (SSTR-2). However, the results of clinical trials using angiopeptin have been disappointing. In this study we showed that human blood vessels express high levels of SSTR-1 with significantly lower levels of SSTR-2 and -4. Samples of normal veins and arteries, as well as atherosclerotic arteries, expressed predominantly SSTR-1. In addition, the levels of SSTR-1 varied between individuals, indicating that the vascular disease process may have affected SSTR gene expression. Immunocytochemical studies demonstrated that SSTR-1 was present in endothelial but not vascular smooth muscle cells. No evidence of SSTR-3 or -5 expression was detected in normal or diseased blood vessels. Two endothelial cell preparations, ECV304 and human umbilical vein endothelial cells, were investigated and shown to express only SSTR-1 and -4. Exposure of these cells to 10 nM somatostatin or 10 nM SSTR-1-specific agonist resulted in alterations to the actin cytoskeleton, as characterized by a loss of actin stress fibers coupled with an increase in lamellipodia formation at the plasma membrane. These results suggest that the lack of effectiveness of angiopeptin in humans may be due to the differential expression of SSTR-1 by human endothelial cells.     

Statins for the prevention of vein graft stenosis: a role for inhibition of matrix metalloproteinase-9

Saphenous vein (SV) grafts are commonly used to bypass coronary arteries that are diseased due to atherosclerosis. However, the development of intimal hyperplasia in such grafts can lead to patency-threatening stenosis and re-occlusion of the vessel. The proliferation and migration of smooth muscle cells (SMC) play key roles in the development of intimal hyperplasia, and an agent that inhibits both of these processes therefore has therapeutic potential. A prerequisite for SMC proliferation and migration in vivo is degradation of the basement membrane, achieved by secretion of the matrix-degrading gelatinases matrix metalloproteinase-2 (MMP-2) and MMP-9. Statins are cholesterol-lowering drugs that also have direct effects on SMC function. Here we report that neointima formation in organ-cultured human SV segments is inhibited by simvastatin, an effect that is associated with reduced MMP-9 activity. Additionally, our work shows that simvastatin not only inhibits proliferation, but importantly also inhibits invasion (migration through a matrix barrier), of cultured human SV SMC. Thus simvastatin treatment appears to inhibit neointima formation as a result of combined inhibition of SMC proliferation and invasion. The potential intracellular mechanisms by which statins affect SMC proliferation and migration, and thus attenuate intimal hyperplasia, are discussed, with particular emphasis on the role of MMP-9.     

Vocal Learning in Songbirds and Humans: A Retrospective in Honor of Peter Marler

Peter Marler made a number of significant contributions to the field of ethology, particularly in the area of animal communication. His research on birdsong learning gave rise to a thriving subfield. An important tenet of this growing subfield is that parallels between birdsong and human speech make songbirds valuable as models in comparative and translational research, particularly in the case of vocal learning and development. Decades ago, Marler pointed out several phenomena common to the processes of vocal development in songbirds and humans—including a dependence on early acoustic experience, sensitive periods, predispositions, auditory feedback, intrinsic reinforcement, and a progression through distinct developmental stages—and he advocated for the value of comparative study in this domain. We review Marler's original comparisons between birdsong and speech ontogeny and summarize subsequent progress in research into these and other parallels. We also revisit Marler's arguments in support of the comparative study of vocal development in the context of its widely recognized value today.     

Animal models of NAFLD from a hepatologist's point of view

Non-alcoholic fatty liver disease (NAFLD) is a chronic liver disorder closely linked to obesity, hyperlipidemia and type 2 diabetes and is increasingly recognized as a major health problem in many parts of the world. While early stages of NAFLD are characterized by a bland accumulation of fat (steatosis) in hepatocytes, the disease can progress to non-alcoholic steatohepatitis (NASH) which involves chronic liver inflammation, tissue damage and fibrosis and can ultimately lead to end-stage liver disease including cirrhosis and cancer. As no approved pharmacological treatment for NAFLD exists today, there is an urgent need to identify promising pharmacological targets and develop future therapies. For this purpose, basic and translational research in NAFLD animal models is indispensable. While a large number of diverse animal models are currently used in the field, there is an ongoing challenge to identify those models that mirror human pathology the closest to allow good translation of obtained results into further clinical development. This review is meant to provide a concise overview of the most relevant NAFLD animal models currently available and will discuss the strengths and weaknesses of these models with regard to their comparability to human disease conditions.     

Genetically engineered pig models for diabetes research

Diabetes mellitus (DM) has emerged into a steadily increasing health problem and the predicted future dimension of the global DM epidemic is alarming: an increase from currently 346 million to over 400 million affected people worldwide by the year 2030 was extrapolated. Thus concerted research efforts are imperative to gain insight into disease mechanisms and to expand the basis for development of preventive and therapeutic strategies. Diabetic rodent models have traditionally been used to follow these goals, but have limitations for translational research. The pig is another classical animal model for diabetes research. Genetic engineering now facilitates tailoring pig models which mimic human disease mechanisms at the molecular level. This article reviews the existing genetically engineered pig models for diabetes research and their current and future applications. Further, the potential role of the pig as donor of pancreatic islets for xenotransplantation or as host for growing human pancreas is outlined.     

Impact of genetic background and aging on mesenteric collateral growth capacity in Fischer 344, Brown Norway, and Fischer 344 x Brown Norway hybrid rats

Available studies indicate that both genetic background and aging influence collateral growth capacity, but it is not known how their combination affects collateral growth. We evaluated collateral growth induced by ileal artery ligation in Fischer 344 (F344), Brown Norway (BN), and the first generation hybrid of F344 x BN (F1) rats available for aging research from the National Institute on Aging. Collateral growth was determined by paired diameter measurements in anesthetized rats immediately and 7 days postligation. In 3-mo-old rats, significant collateral growth occurred only in BN (35% +/- 11%, P < 0.001). The endothelial cell number in arterial cross sections was also determined, since this precedes shear-mediated luminal expansion. When compared with the same animal controls, the intimal cell number was increased only in BN rats (92% +/- 21%, P < 0.001). The increase in intimal cell number and the degree of collateral luminal expansion in BN rats was not affected by age from 3 to 24 mo. Immunohistochemical studies demonstrated that intimal cell proliferation was much greater in the collaterals of BN than of F1 rats. The remarkable difference between these three strains of rats used in aging research and the lack of an age-related impairment in the BN rats are novel observations. These rat strains mimic clinical observations of interindividual variation in collateral growth capacity and the impact of age on arteriogenesis and should be useful models to investigate the molecular mechanisms responsible for such differences.     

Optical imaging and tumor angiogenesis

Tumor angiogenesis is essential for tumor growth and progression. Therefore, targeting tumor blood vessels is a promising approach for cancer therapy. Angiogenesis, the formation of blood vessels, is a multistep process, and strongly influenced by the microenvironment. There are no in vitro assays that can resemble this dynamic process in vivo. For this reason, animal models and imaging technologies are critical for studying tumor angiogenesis, identifying therapeutic targets as well as validating the targets. Non-invasive molecular imaging in animal models presents an unprecedented opportunity and ability for us to perform repetitive observations and analysis of the biological processes underlying tumor angiogenesis and tumor progression in living animals in real time. As we gain a better understanding of the fundamental molecular nature of cancer, these techniques will be an important adjunct in translating the knowledge into clinical practice. This important information may elucidate how the tumor blood vessels behave and respond to certain treatments and therapies.     

Mouse models in neurological disorders: Applications of non-invasive imaging

Neuroimaging techniques represent powerful tools to assess disease-specific cellular, biochemical and molecular processes non-invasively in vivo. Besides providing precise anatomical localisation and quantification, the most exciting advantage of non-invasive imaging techniques is the opportunity to investigate the spatial and temporal dynamics of disease-specific functional and molecular events longitudinally in intact living organisms, so called molecular imaging (MI). Combining neuroimaging technologies with in vivo models of neurological disorders provides unique opportunities to understand the aetiology and pathophysiology of human neurological disorders. In this way, neuroimaging in mouse models of neurological disorders not only can be used for phenotyping specific diseases and monitoring disease progression but also plays an essential role in the development and evaluation of disease-specific treatment approaches. In this way MI is a key technology in translational research, helping to design improved disease models as well as experimental treatment protocols that may afterwards be implemented into clinical routine. The most widely used imaging modalities in animal models to assess in vivo anatomical, functional and molecular events are positron emission tomography (PET), magnetic resonance imaging (MRI) and optical imaging (OI). Here, we review the application of neuroimaging in mouse models of neurodegeneration (Parkinson's disease, PD, and Alzheimer's disease, AD) and brain cancer (glioma).     

Fucoidan is a non-anticoagulant inhibitor of intimal hyperplasia.

We previously reported that heparin inhibits the proliferation of fibroblasts and vascular smooth muscle cells (SMC), in part, by binding to and increasing the antiproliferative activity of transforming growth factor-beta 1 (TGF-beta 1). We now report that certain other polyanions which are structurally distinct from heparin, such as fucoidan and polyinosinic acid, are more avid ligands for TGF-beta 1 and more potent antiproliferative agents than heparin. Fucoidan possessed more potent antiproliferative activity than heparin against rat and bovine aortic SMC in vitro, though possessing much lower anticoagulant activity than heparin. Furthermore, fucoidan suppressed in vivo intimal hyperplasia when continuously infused into rats subjected to balloon-catheter injury. Unlike heparin, which also suppressed intimal hyperplasia, fucoidan did not cause systemic anticoagulation. Thus, fucoidan may be useful as a non-anticoagulant inhibitor of post-angioplasty intimal hyperplasia.     

Lack of intimal hyperplasia response in an experimental model of non-endothelial vascular wall damage.

The endothelial and medial layers are generally presumed to play an important role in the appearance and development of intimal hyperplasia. We have carried out a short-, media- and long-term study of the morphological changes taking place in the common iliac artery of rats after surgical removal of the adventitial layer. Our aim has been to assess the likely role played by this layer in the development of intimal hyperplasia. Our results show recurrent periods of cellular desquamation and almost complete absence of hyperplastic response during the first two months. After three months three is a slow process of endothelialization which is completed by the 6th month and persists one year after adventitial resection. Thus, adventitial resection seems to cause instability at the subendothelial bed level, not allowing the junction and embedding of endothelial cells nor the development of intimal hyperplasia. This lack of hyperplasia might also result from the fact that the endothelial desquamation process does not involve cellular rupture, which would prevent mitogenic-factor release. After morphological repair of the endothelium, a slow morphofunctional recovery of the artery takes place.     

FDG-PET imaging, EEG and sleep phenotypes as translational biomarkers for research in Alzheimer's disease

The lack of reliable translational procedures applicable to both patients and experimental models are a major obstacle for the advancement of basic research as well as for the development of therapeutics. This is particularly relevant to neurodegenerative disorders such as AD (Alzheimer's disease), where the predictive validity of animal models and procedures applied preclinically have met with little success. Two approaches available for human diagnostics are currently experiencing major advancements in preclinical research: in vivo imaging using MRI (magnetic resonance imaging) or PET (positron-emission tomography) and recordings of brain electrical activity via surface EEG (electroencephalogram). The present paper reviews the results obtained so far in rodent AD models, and summarizes advantages and disadvantages of such procedures.     

Simulation of flow through a Miller cuff bypass graft

Unnatural temporal and spatial distributions of wall shear stress in the anastomosis of distal bypass grafts have been identified as possible factors in the development of anastomotic intimal hyperplasia in these grafts. Distal bypass graft anastomoses with an autologus vein cuff (a Miller cuff) interposed between the graft and artery have been shown to alleviate the effects of intimal hyperplasia. In this study, pulsatile flow through models of a standard end-to-side anastomosis and a Miller cuff anastomosis are computed and the resulting wall shear stress and pressure distributions analysed. The results are inconclusive, and could be taken to suggest that the unnatural distributions of shear stress that do occur along the anastomosis floor may not be particularly important in the development of intimal hyperplasia. However, it seems more likely that the positive effects of the biological and material properties of the vein cuff, which are not considered in this study, somehow outweigh the negative effects of the shear stress distributions predicted to occur on the floor of the Miller-cuff graft.     

Impaired collateral development in mature rats

The effect of maturation on collateral development of resistance arteries was investigated. Three to four sequential mesenteric arteries were ligated to create collateral pathways in anesthetized young (approximately 200 g) and mature (approximately 600 g) rats. Blood flow was similarly elevated in collaterals of young and mature animals. In vivo inner arterial diameter was increased only within young collaterals (33 +/- 7%, P < 0.001). Increases in number of intimal nuclei (57 +/- 10% vs. 52 +/- 14%) and cross-sectional medial area (33 +/- 13% vs. 38 +/- 5%) were similar between young and mature collaterals. Relative to the same animal controls, collateral endothelial nitric oxide synthase mRNA was increased as much in mature as in young rats. Proteomic analysis revealed significant differences in protein expression with maturation between control arteries as well as flow-loaded collateral vessels. The results indicate that, whereas intimal and medial remodeling events were similar in collaterals of young and mature rats, luminal expansion occurred only in young rats. Alteration in arterial protein expression with maturation and altered responses to stimuli for collateral development may contribute to this impairment.     

CRISPR/Cas9-mediated genome editing: From basic research to translational medicine

The recent development of the CRISPR/Cas9 system as an efficient and accessible programmable genome-editing tool has revolutionized basic science research. CRISPR/Cas9 system-based technologies have armed researchers with new powerful tools to unveil the impact of genetics on disease development by enabling the creation of precise cellular and animal models of human diseases. The therapeutic potential of these technologies is tremendous, particularly in gene therapy, in which a patient-specific mutation is genetically corrected in order to treat human diseases that are untreatable with conventional therapies. However, the translation of CRISPR/Cas9 into the clinics will be challenging, since we still need to improve the efficiency, specificity and delivery of this technology. In this review, we focus on several in vitro, in vivo and ex vivo applications of the CRISPR/Cas9 system in human disease-focused research, explore the potential of this technology in translational medicine and discuss some of the major challenges for its future use in patients.     

RECK基因在兔颈动脉壁损伤后再狭窄过程中的表达

目的:通过建立动物损伤模型,分析RECK基因在兔子颈动脉球囊损伤术后的表达与动脉内膜变化和官腔狭窄的相关性。方法:兔子手术损伤侧的动脉血管设置为实验组,未进行手术操作的一侧动脉作为对照组。建立动脉模型的四个时间点7、14、21、28 d,在麻醉状态下处死模型动物。取得所需长度的损伤动脉血管及对照组动脉血管。将取得的标本进行HE病理染色,通过计算机图像计算软件观察标本动脉内膜随时间的变化;同时通过western-blot方法测定RECK蛋白表达水平、real-time PCR测量RECK基因表达量。结果:血管手术损伤后,血管内膜面积在随着术后日期的增长呈逐渐增厚变化,血管内膜与中层比值逐渐增大,同对照实验组比较,有统计学意义(P0.05)。实验组及对照组的中膜无显著增生。结论:RECK基因在组织中表达变化影响MMPs基因表达。实验论证了在动脉损伤后RECK基因参与了血管再狭窄,为血管再狭窄研究寻得新的研究方向。