Recent Submissions

  • PPAR-c Regulates Carnitine Homeostasis and Mitochondrial Function in a Lamb Model of Increased Pulmonary Blood Flow

    Sharma, Shruti; Sun, Xutong; Rafikov, Ruslan; Kumar, Sanjiv; Hou, Yali; Oishi, Peter E.; Datar, Sanjeev A.; Raff, Gary; Fineman, Jeffrey R.; Black, Stephen M.; Vascular Biology Center (2012-09-4)
    Objective: Carnitine homeostasis is disrupted in lambs with endothelial dysfunction secondary to increased pulmonary blood flow (Shunt). Our recent studies have also indicated that the disruption in carnitine homeostasis correlates with a decrease in PPAR-c expression in Shunt lambs. Thus, this study was carried out to determine if there is a causal link between loss of PPAR-c signaling and carnitine dysfunction, and whether the PPAR-c agonist, rosiglitazone preserves carnitine homeostasis in Shunt lambs.
  • Intracellular Kinases Mediate Increased Translation and Secretion of Netrin-1 from Renal Tubular Epithelial Cells

    Jayakumar, Calpurnia; Mohamed, Riyaz; Ranganathan, Punithavathi Vilapakkam; Ramesh, Ganesan; Vascular Biology Center (2011-10-26)
    Background: Netrin-1 is a laminin-related secreted protein, is highly induced after tissue injury, and may serve as a marker of injury. However, the regulation of netrin-1 production is not unknown. Current study was carried out in mouse and mouse kidney cell line (TKPTS) to determine the signaling pathways that regulate netrin-1 production in response to injury.
  • Inflammation and diabetic retinal microvascular complications

    Zhang, Wenbo; Liu, Hua; Al-Shabrawey, Mohamed; Caldwell, Robert William; Caldwell, Ruth B.; Vascular Biology Center; Vision Discovery Institute; Department of Pharmacology and Toxicology; Department of Oral Biology; Department of Cellular Biology and Anatomy; Department of Ophthalmology (2011-04)
    Diabetic retinopathy (DR) is one of the most common complications of diabetes and is a leading cause of blindness in people of the working age in Western countries. A major pathology of DR is microvascular complications such as non-perfused vessels, microaneurysms, dot/blot hemorrhages, cotton-wool spots, venous beading, vascular loops, vascular leakage and neovascularization. Multiple mechanisms are involved in these alternations. This review will focus on the role of inflammation in diabetic retinal microvascular complications and discuss the potential therapies by targeting inflammation.
  • Arginase 2 Deletion Reduces Neuro-Glial Injury and Improves Retinal Function in a Model of Retinopathy of Prematurity

    Narayanan, Subhadra P.; Suwanpradid, Jutamas; Saul, Alan; Xu, Zhimin; Still, Amber; Caldwell, Robert William; Caldwell, Ruth B.; Vascular Biology Center; Department of Cellular Biology and Anatomy; Department of Ophthalmology; Department of Pharmacology and Toxicology (2011-07-21)
    Background: Retinopathy of prematurity (ROP) is a major cause of vision impairment in low birth weight infants. While previous work has focused on defining the mechanisms of vascular injury leading to retinal neovascularization, recent studies show that neurons are also affected. This study was undertaken to determine the role of the mitochondrial arginine/ornithine regulating enzyme arginase 2 (A2) in retinal neuro-glial cell injury in the mouse model of ROP.
  • Oxygen Glucose Deprivation in Rat Hippocampal Slice Cultures Results in Alterations in Carnitine Homeostasis and Mitochondrial Dysfunction

    Rau, Thomas F.; Lu, Qing; Sharma, Shruti; Sun, Xutong; Leary, Gregory; Beckman, Matthew L.; Hou, Yali; Wainwright, Mark S.; Kavanaugh, Michael; Poulsen, David J.; Black, Stephen M.; Vascular Biology Center (2012-09-11)
    Mitochondrial dysfunction characterized by depolarization of mitochondrial membranes and the initiation of mitochondrial-mediated apoptosis are pathological responses to hypoxia-ischemia (HI) in the neonatal brain. Carnitine metabolism directly supports mitochondrial metabolism by shuttling long chain fatty acids across the inner mitochondrial membrane for beta-oxidation. Our previous studies have shown that HI disrupts carnitine homeostasis in neonatal rats and that L-carnitine can be neuroprotective. Thus, this study was undertaken to elucidate the molecular mechanisms by which HI alters carnitine metabolism and to begin to elucidate the mechanism underlying the neuroprotective effect of L-carnitine (LCAR) supplementation. Utilizing neonatal rat hippocampal slice cultures we found that oxygen glucose deprivation (OGD) decreased the levels of free carnitines (FC) and increased the acylcarnitine (AC): FC ratio. These changes in carnitine homeostasis correlated with decreases in the protein levels of carnitine palmitoyl transferase (CPT) 1 and 2. LCAR supplementation prevented the decrease in CPT1 and CPT2, enhanced both FC and the ACâ ¶FC ratio and increased slice culture metabolic viability, the mitochondrial membrane potential prior to OGD and prevented the subsequent loss of neurons during later stages of reperfusion through a reduction in apoptotic cell death. Finally, we found that LCAR supplementation preserved the structural integrity and synaptic transmission within the hippocampus after OGD. Thus, we conclude that LCAR supplementation preserves the key enzymes responsible for maintaining carnitine homeostasis and preserves both cell viability and synaptic transmission after OGD.
  • Notch2 and Notch3 Function Together to Regulate Vascular Smooth Muscle Development

    Wang, Qingqing; Zhao, Ning; Kennard, Simone; Lilly, Brenda; Vascular Biology Center (2012-05-17)
    Notch signaling has been implicated in the regulation of smooth muscle differentiation, but the precise role of Notch receptors is ill defined. Although Notch3 receptor expression is high in smooth muscle, Notch3 mutant mice are viable and display only mild defects in vascular patterning and smooth muscle differentiation. Notch2 is also expressed in smooth muscle and Notch2 mutant mice show cardiovascular abnormalities indicative of smooth muscle defects. Together, these findings infer that Notch2 and Notch3 act together to govern vascular development and smooth muscle differentiation. To address this hypothesis, we characterized the phenotype of mice with a combined deficiency in Notch2 and Notch3. Our results show that when Notch2 and Notch3 genes are simultaneously disrupted, mice die in utero at mid-gestation due to severe vascular abnormalities. Assembly of the vascular network occurs normally as assessed by Pecam1 expression, however smooth muscle cells surrounding the vessels are grossly deficient leading to vascular collapse. In vitro analysis show that both Notch2 and Notch3 robustly activate smooth muscle differentiation genes, and Notch3, but not Notch2 is a target of Notch signaling. These data highlight the combined actions of the Notch receptors in the regulation of vascular development, and suggest that while these receptors exhibit compensatory roles in smooth muscle, their functions are not entirely overlapping.
  • Regulation of soluble guanylyl cyclase by phosphorylation

    Zhou, Zongmin; Sayed, Nazish; Pyriochou, Anastasia; Fulton, David; Beuve, Annie; Papapetropoulos, Andreas; Vascular Biology Center (2009-08-11)
  • Regulation of soluble guanylyl cyclase by phosphorylation

    Zhou, Zongmin; Sayed, Nazish; Pyriochou, Anastasia; Fulton, David; Beuve, Annie; Papapetropoulos, Andreas; Vascular Biology Center (2009-08-11)
  • P2Y receptors as regulators of lung endothelial barrier integrity

    Zemskov, Evgeny A.; Lucas, Rudolf; Verin, Alexander D.; Umapathy, Nagavedi S.; Vascular Biology Center; Department of Pulmonary and Critical Care (2011-01)
    Endothelial cells (ECs), forming a semi-permeable barrier between the interior space of blood vessels and underlying tissues, control such diverse processes as vascular tone, homeostasis, adhesion of platelets, and leukocytes to the vascular wall and permeability of vascular wall for cells and fluids. Mechanisms which govern the highly clinically relevant process of increased EC permeability are under intense investigation. It is well known that loss of this barrier (permeability increase) results in tissue inflammation, the hall mark of inflammatory diseases such as acute lung injury and its severe form, acute respiratory distress syndrome. Little is known about processes which determine the endothelial barrier enhancement or protection against permeability increase. It is now well accepted that extracellular purines and pyrimidines are promising and physiologically relevant barrier-protective agents and their effects are mediated by interaction with cell surface P2Y receptors which belong to the superfamily of G-protein-coupled receptors. The therapeutic potential of P2Y receptors is rapidly expanding field in pharmacology and some selective agonists became recently available. Here, we present an overview of recently identified P2Y receptor agonists that enhance the pulmonary endothelial barrier and inhibit and/or reverse endothelial barrier disruption.
  • CXCL9 induces chemotaxis, chemorepulsion and endothelial barrier disruption through CXCR3-mediated activation of melanoma cells

    Amatschek, S; Lucas, Rudolf; Eger, Andreas; Pflueger, M; Hundsberger, Harald; Knoll, C; Grosse-Kracht, S; Schuett, W; Koszik, F; Maurer, D; Wiesner, C; Vascular Biology Center (2011-02-01)
  • Allele Polymorphism and Haplotype Diversity of HLA-A, -B and -DRB1 Loci in Sequence-Based Typing for Chinese Uyghur Ethnic Group

    Deng, Ya-jun; Ye, Shi-hui; Yan, Jiang-wei; Yang, Guang; Wang, Hong-dan; Qin, Hai-xia; Huang, Qi-zhao; Zhang, Jing-Jing; Shen, Chun-mei; Zhu, Bo-feng; Vascular Biology Center; Institute of Molecular Medicine and Genetics (2010-11-04)
    Background: Previous studies indicate that the frequency distributions of HLA alleles and haplotypes vary from one ethnic group to another or between the members of the same ethnic group living in different geographic areas. It is necessary and meaningful to study the high-resolution allelic and haplotypic distributions of HLA loci in different groups.
  • Novel mechanisms of endothelial dysfunction in diabetes

    Yang, Guang; Lucas, Rudolf; Caldwell, Ruth B.; Yao, Lin; Romero, Maritza J.; Caldwell, Robert William; Vascular Biology Center; Department of Pharmacology and Toxicology (2010-04)
    Diabetes mellitus is a major risk factor for cardiovascular morbidity and mortality. This condition increases the risk of developing coronary, cerebrovascular, and peripheral arterial disease fourfold. Endothelial dysfunction is a major contributor to the pathogenesis of vascular disease in diabetes mellitus patients and has recently received increased attention. In this review article, some recent developments that could improve the knowledge of diabetes-induced endothelial dysfunction are discussed.
  • Type-2 diabetes-induced changes in vascular extracellular matrix gene expression: relation to vessel size.

    Song, WeiWei; Ergul, Adviye; Vascular Biology Center (2006-04-10)
    BACKGROUND: Hyperglycemia-induced changes in vascular wall structure contribute to the pathogenesis of diabetic microvascular and macrovascular complications. Matrix metalloproteinases (MMP), a family of proteolytic enzymes that degrade extracellular matrix (ECM) proteins, are essential for vascular remodeling. We have shown that endothelin-1 (ET-1) mediates increased MMP activity and associated vascular remodeling in Type 2 diabetes. However, the effect of Type 2 diabetes and/or ET-1 on the regulation of ECM and MMP gene expression in different vascular beds remains unknown. METHODS: Aorta and mesenteric artery samples were isolated from control, Type 2 diabetic Goto-Kakizaki (GK) rats and GK rats treated with ETA antagonist ABT-627. Gene expression profile of MMP-2, MMP-9, MT1-MMP, fibronectin, procollagen type 1, c-fos and c-jun, were determined by quantitative real-time (qRT) PCR. In addition, aortic gene expression profile was evaluated by an ECM & Adhesion Molecules pathway specific microarray approach. RESULTS: Analysis of the qRT-PCR data demonstrated a significant increase in mRNA levels of MMPs and ECM proteins as compared to control animals after 6 weeks of mild diabetes. Furthermore, these changes were comparable in aorta and mesentery samples. In contrast, treatment with ETA antagonist prevented diabetes-induced changes in expression of MMPs and procollagen type 1 in mesenteric arteries but not in aorta. Microarray analysis provided evidence that 27 extracellular matrix genes were differentially regulated in diabetes. Further qRT-PCR with selected 7 genes confirmed the microarray data. CONCLUSION: These results suggest that the expression of both matrix scaffold protein and matrix degrading MMP genes are altered in macro and microvascular beds in Type 2 diabetes. ETA antagonism restores the changes in gene expression in the mesenteric bed but not in aorta suggesting that ET-1 differentially regulates microvascular gene expression in Type 2 diabetes.
  • Increased hemorrhagic transformation and altered infarct size and localization after experimental stroke in a rat model type 2 diabetes.

    Ergul, Adviye; Elgebaly, Mostafa M; Middlemore, Mary-Louise; Li, Weiguo; Elewa, Hazem; Switzer, Jeffrey A; Hall, Christiana; Kozak, Anna; Fagan, Susan C.; Vascular Biology Center; Department of Neurology (2007-11-29)
    BACKGROUND: Interruption of flow through of cerebral blood vessels results in acute ischemic stroke. Subsequent breakdown of the blood brain barrier increases cerebral injury by the development of vasogenic edema and secondary hemorrhage known as hemorrhagic transformation (HT). Diabetes is a risk factor for stroke as well as poor outcome of stroke. The current study tested the hypothesis that diabetes-induced changes in the cerebral vasculature increase the risk of HT and augment ischemic injury. METHODS: Diabetic Goto-Kakizaki (GK) or control rats underwent 3 hours of middle cerebral artery occlusion and 21 h reperfusion followed by evaluation of infarct size, hemorrhage and neurological outcome. RESULTS: Infarct size was significantly smaller in GK rats (10 +/- 2 vs 30 +/- 4%, p < 0.001). There was significantly more frequent hematoma formation in the ischemic hemisphere in GK rats as opposed to controls. Cerebrovascular tortuosity index was increased in the GK model (1.13 +/- 0.01 vs 1.34 +/- 0.06, P < 0.001) indicative of changes in vessel architecture. CONCLUSION: These findings provide evidence that there is cerebrovascular remodeling in diabetes. While diabetes-induced remodeling appears to prevent infarct expansion, these changes in blood vessels increase the risk for HT possibly exacerbating neurovascular damage due to cerebral ischemia/reperfusion in diabetes.
  • Effect of neutrophil depletion on gelatinase expression, edema formation and hemorrhagic transformation after focal ischemic stroke.

    Harris, Alex K; Ergul, Adviye; Kozak, Anna; Machado, Livia S; Johnson, Maribeth H.; Fagan, Susan C.; Vascular Biology Center; Department of Biostatistics and Epidemiology; Department of Neurology (2005-08-25)
    BACKGROUND: While gelatinase (MMP-2 and -9) activity is increased after focal ischemia/reperfusion injury in the brain, the relative contribution of neutrophils to the MMP activity and to the development of hemorrhagic transformation remains unknown. RESULTS: Anti-PMN treatment caused successful depletion of neutrophils in treated animals. There was no difference in either infarct volume or hemorrhage between control and PMN depleted animals. While there were significant increases in gelatinase (MMP-2 and MMP-9) expression and activity and edema formation associated with ischemia, neutrophil depletion failed to cause any change. CONCLUSION: The main finding of this study is that, in the absence of circulating neutrophils, MMP-2 and MMP-9 expression and activity are still up-regulated following focal cerebral ischemia. Additionally, neutrophil depletion had no influence on indicators of ischemic brain damage including edema, hemorrhage, and infarct size. These findings indicate that, at least acutely, neutrophils are not a significant contributor of gelatinase activity associated with acute neurovascular damage after stroke.
  • Microtubules growth rate alteration in human endothelial cells.

    Alieva, Irina B; Zemskov, Evgeny A.; Kireev, Igor I; Gorshkov, Boris A; Wiseman, Dean A; Black, Stephen M.; Verin, Alexander D.; Vascular Biology Center (2010-05-06)
    To understand how microtubules contribute to the dynamic reorganization of the endothelial cell (EC) cytoskeleton, we established an EC model expressing EB3-GFP, a protein that marks microtubule plus-ends. Using this model, we were able to measure microtubule growth rate at the centrosome region and near the cell periphery of a single human EC and in the EC monolayer. We demonstrate that the majority of microtubules in EC are dynamic, the growth rate of their plus-ends is highest in the internal cytoplasm, in the region of the centrosome. Growth rate of microtubule plus-ends decreases from the cell center toward the periphery. Our data suggest the existing mechanism(s) of local regulation of microtubule plus-ends growth in EC. Microtubule growth rate in the internal cytoplasm of EC in the monolayer is lower than that of single EC suggesting the regulatory effect of cell-cell contacts. Centrosomal microtubule growth rate distribution in single EC indicated the presence of two subpopulations of microtubules with "normal" (similar to those in monolayer EC) and "fast" (three times as much) growth rates. Our results indicate functional interactions between cell-cell contacts and microtubules.
  • Delayed minocycline inhibits ischemia-activated matrix metalloproteinases 2 and 9 after experimental stroke.

    Machado, Livia S; Kozak, Anna; Ergul, Adviye; Hess, David C.; Borlongan, Cesar V; Fagan, Susan C.; Vascular Biology Center; Department of Neurology (2006-08-15)
    BACKGROUND: Matrix metalloproteinases 2 and 9 (MMP-2 and MMP-9) are increased in the brain after experimental ischemic stroke in rats. These two proteases are involved with the degradation of the basal lamina and loss of stability of the blood brain barrier that occurs after ischemia and that is associated with thrombolytic therapy in ischemic stroke. Minocycline is a lipophilic tetracycline and is neuroprotective in several models of brain injury. Minocycline inhibits inflammation, apoptosis and extracellular matrix degradation. In this study we investigated whether delayed minocycline inhibits brain MMPs activated by ischemia in a model of temporary occlusion in Wistar rats. RESULTS: Both MMP-2 and MMP-9 were elevated in the ischemic tissue as compared to the contra-lateral hemisphere after 3 hours occlusion and 21 hours survival (p < 0.0001 for MMP-9). Intraperitoneal minocycline at 45 mg/kg concentration twice a day (first dose immediately after the onset of reperfusion) significantly reduced gelatinolytic activity of ischemia-elevated MMP-2 and MMP-9 (p < 0.0003). Treatment also reduced protein concentration of both enzymes (p < 0.038 for MMP-9 and p < 0.018 for MMP-2). In vitro incubation of minocycline in concentrations as low as 0.1 mug/ml with recombinant MMP-2 and MMP-9 impaired enzymatic activity and MMP-9 was more sensitive at lower minocycline concentrations (p < 0.05). CONCLUSION: Minocycline inhibits enzymatic activity of gelatin proteases activated by ischemia after experimental stroke and is likely to be selective for MMP-9 at low doses. Minocycline is a potential new therapeutic agent to acute treatment of ischemic stroke.