Animal Models Of Vascular Injury Research Articles

Automatic Hemorrhage Detection From Color Doppler Ultrasound Using a Generative Adversarial Network (GAN)-Based Anomaly Detection Method.

Hemorrhage control has been identified as a priority focus area both for civilian and military populations in the United States because exsanguination is the most common cause of preventable death in hemorrhagic injury. Non-compressible torso hemorrhage (NCTH) has high mortality rate and there are currently no broadly available therapies for NCTH outside of a surgical room environment. Novel therapies, which include High Intensity Focused Ultrasound (HIFU) have emerged as promising methods for hemorrhage control as they can non-invasively cauterize bleeding tissue deep within the body without injuring uninvolved regions. A major challenge in the application of HIFU with color Doppler US guidance is the interpretation and optimization of the blood flow images in real-time to identify the hemorrhagic focus. Today, this task requires an expert sonographer, limiting the utility of this therapy in non-clinical environments. In this work, we investigated the feasibility of an automated hemorrhage detection method using a Generative Adversarial Network (GAN) for anomaly detection that learns a manifold of normal blood flow variability and subsequently identifies anomalous flow patterns that fall outside the learned manifold. As an initial feasibility study, we collected ultrasound color Doppler images of femoral arteries in an animal model of vascular injury (N = 11 pigs). Velocity information of the blood flow were extracted from the color Doppler images that were used for training and testing the anomaly detection network. Normotensive images from 8 pigs were used for training, and testing was performed on normotensive, immediately after injury, 10 minutes post-injury and 30 minutes post-injury images from 3 other pigs. The residual images or the reconstructed error maps show promise in detecting hemorrhages with an AUC of 0.90, 0.87, 0.62 immediately, 10 minutes post-injury and 30 minutes post-injury respectively with an overall AUC of 0.83.

Aortic Oxidative Stress, Inflammation and DNA Damage Following Pulmonary Exposure to Cerium Oxide Nanoparticles in a Rat Model of Vascular Injury.

Pulmonary exposure to cerium oxide nanoparticles (CeO2 NPs) can occur either at the workplace, or due to their release in the environment. Inhaled CeO2 NPs are known to cross the alveolar–capillary barrier and reach various parts of the body, including the vasculature. The anticancer drug cisplatin (CP) causes vascular damage. However, the effects CeO2 NPs on vascular homeostasis in a rat model of CP-induced vascular injury remain unclear. Here, we assessed the impact and underlying mechanism of pulmonary exposure to CeO2 NPs on aorta in rats given a single intraperitoneal injection of cisplatin (CP, 6 mg/kg) to induce vascular damage. Six days later, the rats were intratracheally instilled with either CeO2 NPs (1 mg/kg) or saline (control), and various variables were studied 24 h thereafter in the aortic tissue. The concentration of reduced glutathione and the activity of catalase were significantly increased in the CP + CeO2 NPs group compared with both the CP + saline and the CeO2 NPs groups. The activity of superoxide dismutase was significantly decreased in the CP + CeO2 NPs group compared with both the CP + saline and CeO2 NPs groups. The expression of nuclear factor erythroid-derived 2-like 2 (Nrf2) by the nuclei of smooth muscles and endocardial cells assessed by immunohistochemistry was significantly augmented in CeO2 NPs versus saline, in CP + saline versus saline, and in CP + CeO2 NPs versus CeO2 NPs. Moreover, the concentrations of total nitric oxide, lipid peroxidation and 8-hydroxy-2-deoxyguanosine were significantly elevated in the CP + CeO2 NPs group compared with both the CP + saline and the CeO2 NPs groups. Similarly, compared with both the CP + saline and CeO2 NPs groups, the combination of CP and CeO2 NPs significantly elevated the concentrations of interleukin-6 and tumour necrosis factor-α. Additionally, aortic DNA damage assessed by Comet assay was significantly increased in CeO2 NPs compared with saline, and in CP + saline versus saline, and all these effects were significantly aggravated by the combination of CP and CeO2 NPs. We conclude that pulmonary exposure to CeO2 NPs aggravates vascular toxicity in animal model of vascular injury through mechanisms involving oxidative stress, Nrf2 expression, inflammation and DNA damage.

Dietary supplementation with Zyflamend poly-herbal extracts and fish oil inhibits intimal hyperplasia development following vascular intervention

The polyherbal blend Zyflamend™ has been shown to have anti-inflammatory properties and attenuate inflammatory-modulated pathologies. Fish oils have also been shown to have cardioprotective properties. However, the beneficial effects of their combination have not been investigated. Intimal hyperplasia (IH), a pathological remodeling response of a vessel to injury, is heavily regulated by an immune-mediated reaction. The objective of this study was to determine if dietary supplementation with Zyflamend and/or Wholemega could affect inflammatory-dependent vascular remodeling mechanisms when provided at human equivalent doses. Based on their anti-inflammatory properties and protective benefits demonstrated in previous pre-clinical studies, we hypothesized administration of these supplements would prevent IH in an animal model of vascular injury. The diets of aged male rats were supplemented with human equivalent doses of Zyflamend (Zyf) and/or Wholemega (WMega) or placebo (Plac) for 1wk prior to balloon angioplasty (BA)-induced injury of the left carotid artery. At 28d post-injury morphometric analysis of carotid tissue revealed IH was decreased in Zyf + WMega animals compared to placebo, while Zyf or WMega independently had no significant effect. Serum cytokine screening indicated injury-induced interleukin family isoforms, interferon-γ, and macrophage inflammatory proteins were downregulated by Zyf + WMega. Immunohistochemical staining for monocyte/macrophage phenotypic markers revealed that while overall monocyte/macrophage vessel infiltration was not affected, Zyf + WMega limited the alternative differentiation of M2 macrophages and reduced the presence of myofibroblasts in the injured vessel wall. In summary, dietary supplementation with Zyf + WMega attenuated the acute inflammatory response following vascular injury and inhibited IH development in vivo.

Ang‐II‐Induced Phosphorylation and Nuclear Export of Histone Deacetylase 5 is Mediated by an AKT‐Dependent Pathway in Vascular Smooth Muscle Cells

Augmented levels of angiotensin‐II (Ang‐II) are associated with the development of cardiovascular disorders such as atherosclerosis and hypertension. Exaggerated activation of Ang‐II‐induced signaling events and expression of genes linked to cell proliferation, hypertrophy and migration have been demonstrated to contribute to the development of these vascular pathologies. Ang‐II induces the phosphorylation of class II histone deacetylases (HDACs), particularly HDAC4 and HDAC5. HDACs regulate gene transcription by their ability to modify the acetylation status of the lysine residues in histone and non‐histone proteins. A heightened activation of HDACs, notably HDAC5, has been associated with vascular disorders such as atherosclerosis. We have shown earlier that Ang‐II induces the expression of early growth response factor‐1 (Egr‐1), a zinc finger transcription factor which is upregulated in atherosclerotic lesions and in animal models of vascular injury. We have also reported that the PI3Kinase/AKT pathway plays a key role in inducing the expression of Egr‐1 in vascular smooth muscle cells (VSMC). However, the role of the AKT pathway in HDAC5 phosphorylation and the contribution of HDAC5 in Egr‐1 expression in VSMC remains unexplored. Here, we show that Ang‐II induced the phosphorylation of HDAC5 in a time and dose‐dependent manner, and pharmacological blockade of the PI3K/AKT pathway by wortmannin or SC66 attenuated Ang‐II‐induced HDAC5 phosphorylation in A10 VSMC. In addition, Ang‐II treatment of VSMC resulted in the translocation of HDAC5 from the nucleus to the cytosol, and the inhibition of AKT by SC66 almost completely attenuated the nuclear export of HDAC5 induced by Ang‐II. In contrast, pharmacological blockade of the MAPK pathway by UO126 was ineffective in reducing Ang‐II‐induced HDAC5 phosphorylation. Furthermore, pharmacological inhibition of HDAC5 by MC1568 or siRNA‐induced silencing of HDAC5 suppressed Ang‐II‐induced Egr‐1 expression. In summary, our results suggest that Ang‐II induces the phosphorylation and nuclear export of HDAC5 via the PI3K/AKT‐dependent signaling pathway and that HDAC5 is an upstream modulator of Egr‐1 expression in VSMC.Support or Funding InformationSupported by Canadian Institutes of Health ResearchThis abstract is from the Experimental Biology 2019 Meeting. There is no full text article associated with this abstract published in The FASEB Journal.

Ferric Chloride-induced Canine Carotid Artery Thrombosis: A Large Animal Model of Vascular Injury

Ferric Chloride-induced Canine Carotid Artery Thrombosis: A Large Animal Model of Vascular Injury

Ferric Chloride-induced Canine Carotid Artery Thrombosis: A Large Animal Model of Vascular Injury.

Occlusive arterial thrombosis leading to cerebral ischemic stroke and myocardial infarction contributes to ~13 million deaths every year globally. Here, we have translated a vascular injury model from a small animal into a large animal (canine), with slight modifications that can be used for pre-clinical screening of prophylactic and thrombolytic agents. In addition to the surgical methods, the modified protocol describes the step-by-step methods to assess carotid artery canalization by angiography, detailed instructions to process both the brain and carotid artery for histological analysis to verify carotid canalization and cerebral hemorrhage, and specific parameters to complete an assessment of downstream thromboembolic events by utilizing magnetic resonance imaging (MRI). In addition, specific procedural changes from the previously well-established small animal model necessary to translate into a large animal (canine) vascular injury are discussed.

New insights into the non-hemostatic role of von Willebrand factor in endothelial protection

During exposure to ischemia-reperfusion (I/R) insult, angiotensin II (AngII)-induced endothelin-1 (ET-1) upregulation in endothelial cells progressively impairs nitric oxide (NO) bioavailability while increasing levels of superoxide anion (O2-) and leading to the onset of endothelial dysfunction. Moreover, the overexpression of ET-1 increases the endothelial and circulating levels of von Willebrand factor (vWF), a glycoprotein with a crucial role in arterial thrombus formation. Nowadays, the non-hemostatic role of endothelial vWF is emerging, although we do not yet know whether its increased expression is cause or consequence of endothelial dysfunction. Notably, the vWF blockade or depletion leads to endothelial protection in cultured cells, animal models of vascular injury, and patients as well. Despite the recent efforts to develop an effective pharmacological strategy, the onset of endothelial dysfunction is still difficult to prevent and remains closely related to adverse clinical outcome. Unraveling the non-hemostatic role of endothelial vWF in the onset of endothelial dysfunction could provide new avenues for protection against vascular injury mediated by AngII.

Testosterone replacement attenuates intimal hyperplasia development in an androgen deficient model of vascular injury

BackgroundAndrogen deficiency (AD) is associated with increased risk of vascular disease. Dysfunctional remodeling of the vessel wall and atypical proliferative potential of vascular smooth muscle cells (VSMCs) are fundamental processes in the development of intimal hyperplasia (IH). We have demonstrated an inverse relationship between dihydrotestosterone (DHT) levels, matrix metalloproteinase activity, and VSMC migration and proliferation in vitro. Here, we investigated the role of AD and testosterone (TST) replacement in IH development in an animal model of vascular injury to elucidate mechanisms modulated by AD that could be playing a role in the development of vascular pathogenesis. MethodsAged orchiectomized male rats underwent TST supplementation via controlled release pellet (0.5-35 mg). Young adult and middle-age adult intact (MI) and orchiectomized placebo (Plac) groups served as controls. All groups underwent balloon angioplasty of the left common carotid at a 14-d post-TST. Carotid tissue was collected at a 14-d post-balloon angioplasty and subjected to morphologic and immunohistochemical analyses. Human male VSMCs were treated with DHT (0-3000 nM) for 24 h then subjected to quantitative PCR for gene expression analyses and costained for F-actin and G-actin for visualization of cytoskeletal organization. ResultsI:M ratio was increased in Plac, subphysiological, low-physiological, and high pharmacologic level TST animals compared with MI controls but was decreased with high-physiological TST supplementation. Injury-induced expression of previously defined matrix metalloproteinase remodeling enzymes was not significantly affected by TST status. Urotensin (UTS) receptor (UTSR) staining was low in injured vessels of all young adult intact, MI, and Plac controls but was significantly upregulated in all groups receiving exogenous TST supplementation, irrespective of dose. In vitro DHT exposure increased the expression of UTSR in VSMCs in a dose-dependent manner. However, this did not correlate with any change in proliferative markers. F:G actin staining revealed that DHT-induced cytoskeletal organization in a dose-dependent manner. ConclusionsAD increased IH development in response to vascular injury, whereas physiological TST replacement attenuated this effect. AD-induced IH occurs independent of matrix remodeling mechanisms known to be heavily involved in vascular dysfunction, and AD alone does not affect the UTS and/or UTSR mechanism. Exogenous TST and/or DHT increases UTSR pathway signaling in vitro and in vivo. This modulation correlates to a shift in cytoskeletal organization and may exacerbate vasoconstrictive pathogenesis. While physiological TST replacement attenuates AD-modulated IH development, its UTS-mediated effect on vasotone may prove deleterious to overall vascular function.

The complement receptor 3 (CD11b/CD18) agonist Leukadherin-1 suppresses human innate inflammatory signalling.

SummaryComplement receptor 3 (CR3, CD11b/CD18) is a multi‐functional receptor expressed predominantly on myeloid and natural killer (NK) cells. The R77H variant of CD11b, encoded by the ITGAM rs1143679 polymorphism, is associated robustly with development of the autoimmune disease systemic lupus erythematosus (SLE) and impairs CR3 function, including its regulatory role on monocyte immune signalling. The role of CR3 in NK cell function is unknown. Leukadherin‐1 is a specific small‐molecule CR3 agonist that has shown therapeutic promise in animal models of vascular injury and inflammation. We show that Leukadherin‐1 pretreatment reduces secretion of interferon (IFN)‐γ, tumour necrosis factor (TNF) and macrophage inflammatory protein (MIP)‐1β by monokine‐stimulated NK cells. It was associated with a reduction in phosphorylated signal transducer and activator of transcription (pSTAT)‐5 following interleukin (IL)‐12 + IL‐15 stimulation (P < 0·02) and increased IL‐10 secretion following IL‐12 + IL‐18 stimulation (P < 0·001). Leukadherin‐1 pretreatment also reduces secretion of IL‐1β, IL‐6 and TNF by Toll‐like receptor (TLR)‐2 and TLR‐7/8‐stimulated monocytes (P < 0·01 for all). The R77H variant did not affect NK cell response to Leukadherin‐1 using ex‐vivo cells from homozygous donors; nor did the variant influence CR3 expression by these cell types, in contrast to a recent report. These data extend our understanding of CR3 biology by demonstrating that activation potently modifies innate immune inflammatory signalling, including a previously undocumented role in NK cell function. We discuss the potential relevance of this to the pathogenesis of SLE. Leukadherin‐1 appears to mediate its anti‐inflammatory effect irrespective of the SLE‐risk genotype of CR3, providing further evidence to support its evaluation of Leukadherin‐1 as a potential therapeutic for autoimmune disease.

Expression of V3 Versican by Rat Arterial Smooth Muscle Cells Promotes Differentiated and Anti-inflammatory Phenotypes

Arterial smooth muscle cells (ASMCs) undergo phenotypic changes during development and pathological processes in vivo and during cell culture in vitro. Our previous studies demonstrated that retrovirally mediated expression of the versican V3 splice variant (V3) by ASMCs retards cell proliferation and migration in vitro and reduces neointimal thickening and macrophage and lipid accumulation in animal models of vascular injury and atherosclerosis. However, the molecular pathways induced by V3 expression that are responsible for these changes are not yet clear. In this study, we employed a microarray approach to examine how expression of V3 induced changes in gene expression and the molecular pathways in rat ASMCs. We found that forced expression of V3 by ASMCs affected expression of 521 genes by more than 1.5-fold. Gene ontology analysis showed that components of the extracellular matrix were the most significantly affected by V3 expression. In addition, genes regulating the formation of the cytoskeleton, which also serve as markers of contractile smooth muscle cells (SMCs), were significantly up-regulated. In contrast, components of the complement system, chemokines, chemokine receptors, and transcription factors crucial for regulating inflammatory processes were among the genes most down-regulated. Consistently, we found that the level of myocardin, a key transcription factor promoting contractile SMC phenotype, was greatly increased, and the proinflammatory transcription factors NFκB1 and CCAAT/enhancer-binding protein β were significantly attenuated in V3-expressing SMCs. Overall, these findings demonstrate that V3 expression reprograms ASMCs promoting differentiated and anti-inflammatory phenotypes.

Abstract 515: Effects of the Glucagon-Like Peptide-1 Analog Exendin-4 on Reendothelialization and Intimal Hyperplasia Formation in an Animal Model of Vascular Injury

Background and aims: Diabetic patients have an increased risk of late stent thrombosis formation and restenosis, after angioplasty. It is hypothesized that delayed re-endothelization is a major underlying problem for late-stent thrombosis and also that rapid re-endothelization is essential for preventing restenosis. Exendin-4 is a stable GLP-1 receptor agonist, which is applied in clinical treatment of diabetes. Beside its insulinotropic action, it may also exert direct beneficial effects on endothelial function. We previously reported that exendin-4 is able to activate the GLP-1 receptor on human coronary artery endothelial cells, leading to increased cell proliferation and decreased apoptosis. Therefore, our aim was to study if exendin-4 can influence endothelialization and decrease neointima formation after vascular injury. Materials and Methods: Balloon injury of the left common carotid artery (LCCA) was performed on Sprague-Dawley rats. Rats were randomized into two groups and treated for four weeks with exendin-4 (1 nmol/day) or saline. Intimal hyperplasia and endothelialization was monitored non-invasively by high frequency ultrasound and upon sacrifice with Evans blue, respectively. The LCCA was then sectioned for subsequent morphometric and immunohistochemical analyses. To further investigate if and how smooth muscle cells (SMCs) are directly affected by exendin-4 treatment, we studied proliferation and apoptosis of SMCs in vitro . Results and conclusions: Our findings show that exendin-4 selectively reduces SMC proliferation and intimal hyperplasia through activation of cAMP signaling and endothelial nitric oxide synthase without influencing re-endothelialization. Treatment with exendin-4 did however improve arterial wall elasticity. Together, these effects of exendin-4 are highly desirable and may lead to improved outcome for patients undergoing vascular interventions

Bindarit inhibits human coronary artery smooth muscle cell proliferation, migration and phenotypic switching.

Bindarit, a selective inhibitor of monocyte chemotactic proteins (MCPs) synthesis, reduces neointimal formation in animal models of vascular injury and recently has been shown to inhibit in-stent late loss in a placebo-controlled phase II clinical trial. However, the mechanisms underlying the efficacy of bindarit in controlling neointimal formation/restenosis have not been fully elucidated. Therefore, we investigated the effect of bindarit on human coronary smooth muscle cells activation, drawing attention to the phenotypic modulation process, focusing on contractile proteins expression as well as proliferation and migration. The expression of contractile proteins was evaluated by western blot analysis on cultured human coronary smooth muscle cells stimulated with TNF-α (30 ng/mL) or fetal bovine serum (5%). Bindarit (100–300 µM) reduced the embryonic form of smooth muscle myosin heavy chain while increased smooth muscle α-actin and calponin in both TNF-α- and fetal bovine serum-stimulated cells. These effects were associated with the inhibition of human coronary smooth muscle cell proliferation/migration and both MCP-1 and MCP-3 production. The effect of bindarit on smooth muscle cells phenotypic switching was confirmed in vivo in the rat balloon angioplasty model. Bindarit (200 mg/Kg/day) significantly reduced the expression of the embryonic form of smooth muscle myosin heavy chain, and increased smooth muscle α-actin and calponin in the rat carodid arteries subjected to endothelial denudation. Our results demonstrate that bindarit induces the differentiated state of human coronary smooth muscle cells, suggesting a novel underlying mechanisms by which this drug inhibits neointimal formation.

High Concentrations of Thrombospondin-1 Suppress Shear Stress Induced Cleavage of Von Willebrand Factor by ADAMTS13.

Abstract 3063Poster Board II-1039ADAMTS13 is a circulating metalloprotease that cleaves and down regulates the activity of von Willebrand factor (VWF) in the circulation. Deficiency of ADAMTS13 causes thrombotic thrombocytopenic purpura (TTP). VWF is critical for supporting platelet adhesion and aggregation at sites of microvascular injury. Nevertheless, the factors that protect VWF from cleavage by ADAMTS13 remain unknown. Thrombospondin-1 (Thbs-1), an adhesive protein that exhibit binding to multiple proteins such as collagen, fibronectin and fibrin, promotes thrombus adherence in animal models of vascular injury. To investigate the role of Thbs-1 in the regulation of VWF cleavage by ADAMTS13, we analyzed the cleavage of VWF flowing through a capillary tube. In the presence of physiological concentrations of ADAMTS13, VWF fragments were generated in a shear stress dependent manner. The cleavage of VWF in the capillary tube device was inhibited by Thbs-1 in a concentration dependent manner. At physiological concentrations (30 ng/mL) of Thbs-1, the cleavage of VWF was decreased insignificantly to 85% of control. The cleavage was decreased to 50% at 100 ng/mL Thbs-1, and to less than 10% at 1000 ng/mL Thbs-1 (P<0.0001). The suppressive effect of Thbs-1 was also observed with a truncated variant of ADAMTS13 that lacks the distal six thrombospondin type 1 repeats and the CUB domains, suggesting that the C-terminal part of ADAMTS13 is not necessary for the suppressive effect of Thbs-1. Furthermore, the presence of platelets did not negate the suppressive effect of Thbs-1 on VWF cleavage. Thbs-1 did not suppress the cleavage of FRET-VWF73 or guanidine hydrochloride treated VWF. It also did not affect the cleavage of VWF multimers induced by vortexing in the presence of ADAMTS13 and platelets. In summary, the suppressive effect of Thbs-1 on VWF cleavage is shear stress dependent. Thbs-1 is not expected to play a major role in regulating the size of circulating VWF multimers. Nevertheless, high concentrations of Thbs-1 released from platelets may protect sheared VWF from cleavage by ADAMTS13. This protective effect of Thbs-1 on VWF proteolysis may help stabilize the hemostatic plugs at sites of microvascular injury. DisclosuresNo relevant conflicts of interest to declare.

The anti-inflammatory agent bindarit inhibits neointima formation in both rats and hyperlipidaemic mice.

AimsBindarit is an original compound with peculiar anti-inflammatory activity due to a selective inhibition of a subfamily of inflammatory chemokines, including the monocyte chemotactic proteins MCP-1/CCL2, MCP-3/CCL7, and MCP-2/CCL8. In this study, we investigated the effect of bindarit on neointima formation using two animal models of arterial injury: rat carotid artery balloon angioplasty and wire-induced carotid injury in apolipoprotein E-deficient (apoE−/−) mice.Methods and resultsTreatment of rats with bindarit (200 mg/kg/day) significantly reduced balloon injury-induced neointima formation by 39% at day 14 without affecting re-endothelialization and reduced the number of medial and neointimal proliferating cells at day 7 by 54 and 30%, respectively. These effects were associated with a significant reduction of MCP-1 levels both in sera and in injured carotid arteries of rats treated with bindarit. In addition, in vitro data showed that bindarit (10–300 µM) reduced rat vascular smooth muscle cell (VSMC) proliferation, migration, and invasion, processes contributing to the injury-induced neointima formation in vivo. Similar results were observed in hypercholesterolaemic apoE−/− mice in which bindarit administration resulted in a 42% reduction of the number of proliferating cells at day 7 after carotid injury and in a 47% inhibition of neointima formation at day 28. Analysis of the cellular composition in neointimal lesions of apoE−/− mice treated with bindarit showed that the relative content of macrophages and the number of VSMCs were reduced by 66 and 30%, respectively, compared with the control group.ConclusionThis study demonstrates that bindarit is effective in reducing neointima formation in both non-hyperlipidaemic and hyperlipidaemic animal models of vascular injury by a direct effect on VSMC proliferation and migration and by reducing neointimal macrophage content. All of these data were associated with the inhibition of MCP-1 production.

Hyaluronan Accumulation Is Elevated in Cultures of Low Density Lipoprotein Receptor-deficient Cells and Is Altered by Manipulation of Cell Cholesterol Content

The extracellular matrix molecule hyaluronan (HA) accumulates in human atherosclerotic lesions. Yet the reasons for this accumulation have not been adequately addressed. Because abnormalities in lipid metabolism promote atherosclerosis, we have asked whether disrupted cholesterol homeostasis alters HA accumulation in low density lipoprotein receptor-deficient cell cultures. Cultured aortic smooth muscle cells (ASMC) from Watanabe heritable hyperlipidemic (WHHL) rabbits and skin fibroblasts from homozygous patients with familial hypercholesterolemia accumulated 2-4-fold more HA than corresponding cells from age- and sex-matched normolipidemic rabbits and individuals. This occurred in both cell-associated and secreted HA fractions and was independent of cell density or medium serum concentration. WHHL ASMC cultures synthesized twice the proportion of high molecular mass HA (>2x10(6) Da) as normal rabbit ASMC but showed a lower capacity to degrade exogenous [3H]HA. Most importantly, cholesterol depletion or blocking cholesterol synthesis markedly reduced HA accumulation in WHHL ASMC cultures, whereas cholesterol replenishment or stimulation of cholesterol synthesis restored elevated HA levels. We conclude the following: 1) maintaining normal HA levels in cell cultures requires normal cell cholesterol homeostasis; 2) HA degradation may contribute to but is not the predominant mechanism to increase high molecular mass HA accumulation in low density lipoprotein receptor-deficient WHHL ASMC cultures; and 3) elevated accumulation of HA depends on cellular or membrane cholesterol content and, potentially, intact cholesterol-rich microdomains.

This Month in Anesthesiology

The characteristics of diabetic cardiomyopathy and its consequences on anesthetic management are reviewed.Better understanding of methadone metabolism is likely to improve the safety and outcomes of methadone use in patients.Hyperglycemia that occurred during renal ischemia–reperfusion resulted in severe functional injury.To study the relation between body mass index (BMI) and perioperative outcomes in children, Tait et al. prospectively collected data from 2,025 children presenting for surgery during a 20-month period. Using BMI classifications developed specifically for children, the team identified 17.3% of the children as obese. Incidence and severity of respiratory adverse events were recorded at five points throughout the perioperative period. Obese children had a higher incidence of difficult mask ventilation, airway obstruction, and oxygen desaturation. Although events were managed without serious sequelae, it is important to identify risk factors associated with obesity to optimize anesthetic care of these children.Kodali et al. undertook two studies to evaluate airway changes associated with labor and delivery. In the first study of 61 parturients, the team used conventional Samsoon’s modification of Mallampati airway class to classify airways at the onset and end of labor. In the second study, the team used acoustic reflectometry to measure upper airway volumes at the same junctures. During Study 1, there was a significant increase in airway class from pre- to postlabor, with 33% of patients increasing one grade higher. Study 2 revealed significant decreases in oral volume, pharyngeal area, and pharyngeal volume during labor and delivery. Due to these observed changes, it is essential to carefully evaluate a woman’s airway just before administering anesthesia during labor rather than relying on prelabor data. See the accompanying Editorial View on page 347 The regenerative potential of endothelial progenitor cells (EPCs) has been investigated in a variety of animal models of vascular injury and ischemia. In this issue, Lam et al. report on the effects of EPCs in a rabbit model of acute lung injury/acute respiratory distress syndrome (ALI/ARDS) that produced pulmonary endothelial dysfunction. Endothelial dysfunction was attenuated in rabbits treated with autologous EPCs, and infiltration and activity of leucocytes in the lung parenchyma was also significantly reduced. Transplanted EPCs might have the potential for becoming a cell-based, endothelium-targeted therapeutic strategy for the prevention and treatment of ALI/ARDS. See the accompanying Editorial View on page 354 Pain from bone injury is poorly understood. Freeman et al. induced closed mid-diaphyseal fracture of the left femur 21 days after pin placements in male and female rats. The animals’ pain behaviors were assessed at day 0 (before fracture) and at several days up to three weeks after fracture. There were no gender differences in degree of after-fracture guarding, flinching, and weight-bearing, or required morphine. Histologic analysis of bone and nerve tissues allowed characterization of the fracture pain and bone healing trajectories. Use of this fracture model could lead to discovery of analgesics to effectively treat fracture pain without inhibiting fracture healing. See the accompanying Editorial View on page 349 This article has been selected for the Anesthesiology CME Program.

The ligand/RAGE axis: Lighting the fuse and igniting vascular stress

Vascular inflammation contributes critically to the initiation and progression of atherosclerosis. These processes are accelerated in hyperglycemia and play key roles in the increased incidence and severity of myocardial infarction and stroke observed in diabetes. Evidence suggests that the ligands of the receptor for advanced glycation endproducts (RAGE), a multiligand member of the immunoglobulin superfamily, interact with this receptor to play important roles in both early development and progression of atherosclerosis and vascular inflammation. Studies in animal models of vascular injury underscored the potent impact of RAGE blockade; administration of ligand-binding decoys of RAGE or antibodies to the receptor reduced the consequences of diabetes, hyperlipidemia, and physical injury to the vessel wall. This review focuses on the ligand repertoire of RAGE, the impact of ligand-RAGE interaction, and the potent effect of RAGE blockade in rodent models of vascular injury.

Potential role of Chinese medicinal herbs in the prevention of coronary artery restenosis

Potential role of Chinese medicinal herbs in the prevention of coronary artery restenosis

Prevention of Restenosis by Systemic Drug Therapy

In this issue of Circulation , 2 studies report a positive outcome in patients who received oral pharmacotherapy for the prevention of restenosis after stent placement. In the randomized, double-blind, placebo-controlled Cilostazol for Restenosis Trial (CREST) trial,1 patients were given cilostazol, a phosphodiesterase 3 inhibitor with antithrombotic2 and antiproliferative3 properties, for 6 months starting immediately after implantation of a bare-metal stent in a de novo target lesion. Minimal lumen diameter, the primary end point of this study, which comprised 705 patients, was larger among patients treated with cilostazol than among those who received placebo. Other angiographic but not clinical outcomes were also more favorable among patients assigned to the active treatment arm. Articles pp 2792 and 2826 The second study investigated the effect of a 6-month treatment with the thiazolidinedione pioglitazone on neointima formation measured by intravascular ultrasound 6 months after bare-metal stent implantation for de novo coronary artery lesions.4 In this small study, which comprised a total of 50 nondiabetic patients, neointima formation was significantly reduced among patients treated with pioglitazone compared with those who received placebo. Similarly, angiographic and clinical measures of restenosis were better among patients assigned to pioglitazone treatment. Although potential beneficial effects of thiazolidinedione regarding the prevention of neointima formation include antiinflammatory5 and antiproliferative effects,6 the exact mechanism by which pioglitazone led to a reduction of neointima formation among patients included in this study remains elusive. The findings of these studies add to the existing evidence on the use of systemic pharmacological approaches to prevent restenosis. For most of these approaches, initial positive results in animal models of vascular injury and/or small pilot studies have been followed by disappointing results in large clinical trials. Basically, …

Does the AT2-receptor mediate anti-atherosclerotic actions?

Does the AT2-receptor mediate anti-atherosclerotic actions?