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Douglas B Cowan

Publications and source records attributed to Douglas B Cowan.

18 recordsLinked to original sources
PubMed2006

C6ORF32 is upregulated during muscle cell differentiation and induces the formation of cellular filopodia.

We have identified a gene by microarray analysis that is located on chromosome 6 (c6orf32), whose expression is increased during human fetal myoblast differentiation. The protein encoded by c6orf32 is expressed both in myogenic and non-myogenic primary cells isolated from 18-week old human fetal skeletal muscle. Immunofluorescent staining indicated that C6ORF32 localizes to the cellular cytoskeleton and filopodia, and often displays polarized expression within the cell. mRNA knockdown experiments in the C2C12 murine myoblast cell line demonstrated that cells lacking c6orf32 exhibit a myogenic differentiation defect, characterized by a decrease in the expression of myogenin and myosin heavy chain (MHC) proteins, whereas MyoD1 was unaltered. In contrast, overexpression of c6orf32 in C2C12 or HEK293 cells (a non-muscle cell line) promoted formation of long membrane protrusions (filopodia). Analysis of serial deletion mutants demonstrated that amino acids 55-113 of C6ORF32 are likely involved in filopodia formation. These results indicate that C6ORF32 is a novel protein likely to play multiple functions, including promoting myogenic cell differentiation, cytoskeletal rearrangement and filopodia formation.

Base Sequence↗
PubMed2006

Chemical modulation of receptor signaling inhibits regenerative angiogenesis in adult zebrafish.

We examined the role of angiogenesis and the need for receptor signaling using chemical inhibition of the vascular endothelial growth factor receptor in the adult zebrafish tail fin. Using a small-molecule inhibitor, we were able to exert precise control over blood vessel regeneration. An angiogenic limit to tissue regeneration was determined, as avascular tissue containing skin, pigment, neuronal axons and bone precursors could regenerate up to about 1 mm. This indicates that tissues can regenerate without direct interaction with endothelial cells and at a distance from blood supply. We also investigated whether the effects of chemical inhibition could be enhanced in zebrafish vascular mutants. We found that adult zebrafish, heterozygous for a mutation in the critical receptor effector phospholipase Cgamma1, show a greater sensitivity to chemical inhibition. This study illustrates the utility of the adult zebrafish as a new model system for receptor signaling and chemical biology.

Angiogenesis Inhibitors↗
PubMed2006

Reduction and redistribution of gap and adherens junction proteins after ischemia and reperfusion.

BACKGROUND: Previous studies have demonstrated that alterations in myocardial structure, consistent with tissue and sarcomere disruption as well as myofibril dissociation, occur after myocardial ischemia and reperfusion. In this study we determine the onset of these structural changes and their contribution to electrical conduction. METHODS: Langendorff perfused rabbit hearts (n = 47) were subjected to 0, 5, 10, 15, 20, 25, and 30 minutes global ischemia, followed by 120 minutes reperfusion. Hemodynamics were recorded and tissue samples were collected for histochemical and immunohistochemical studies. Orthogonal epicardial conduction velocities were measured, with temperature controlled, in a separate group of 10 hearts subjected to 0 or 30 minutes of global ischemia, followed by 120 minutes of reperfusion. RESULTS: Histochemical and quantitative light microscopy spatial analysis showed significantly increased longitudinal and transverse interfibrillar separation after 15 minutes or more of ischemia (p < 0.05 versus control). Confocal immunohistochemistry and Western blot analysis demonstrated significant reductions (p < .05 versus control) of the intercellular adherens junction protein, N-cadherin, and the active phosphorylated isoform of the principal gap junction protein, connexin 43 at more than 15 minutes of ischemia. Cellular redistribution of connexin 43 was also evidenced on immunohistochemistry. No change in integrin-beta1, an extracellular matrix attachment protein, or in epicardial conduction velocity anisotropy was observed. CONCLUSIONS: These data indicate that there are significant alterations in the structural integrity of the myocardium as well as gap and adherens junction protein expression with increasing global ischemia time. The changes occur coincident with previously observed significant decreases in postischemic functional recovery, but are not associated with altered expression of matrix binding proteins or electrical anisotropic conduction.

Adherens Junctions↗
PubMed2006

Dopamine induces postischemic cardiomyocyte apoptosis in vivo: an effect ameliorated by propofol.

BACKGROUND: Dopamine is commonly used to improve postischemic myocardial contractile function. However, there is evidence that dopamine augments apoptosis after ischemia through increased intracellular calcium and opening of the mitochondrial permeability transition pore. Propofol (2,6-diisopropylphenol) is an anesthetic that has been shown to prevent mitochondrial permeability transition pore opening. We evaluated the effects of propofol given during reperfusion on dopamine-mediated apoptosis. METHODS: Hearts from 8-week-old inbred New Zealand White rabbit siblings were subjected to 2 hours of cold cardioplegic ischemia and 6 hours of reperfusion in a heterotopic transplant model. Controls consisted of the recipient rabbit's nonischemic heart. The ischemia-reperfusion (IR) group consisted of postischemic hearts reperfused with no drugs; the IR plus dopamine (IR+D) group received dopamine (20 microg x kg(-1) x min(-1)) continuously; the IR+D plus propofol (IR+D+P) group received dopamine (20 microg x kg(-1) x min(-1)) plus propofol (500 to 600 microg x kg(-1) x min(-1)); and the IR plus propofol (IR+P) group received propofol only (500 to 600 microg x kg(-1) x min(-1)) throughout reperfusion (n = 7 to 9 in each group). Myocardial function was measured using a left ventricular balloon; terminal nick-end labeling (TUNEL) staining, DNA electrophoresis, and immunoblotting for caspase-3 cleavage were performed at the end of reperfusion. RESULTS: Dopamine increased the number of TUNEL-positive nuclei significantly (14.0 +/- 2.0/1,000 for IR+D versus 6.7 +/- 2.0/1,000 for IR, p = 0.01). Propofol (IR+D+P) reduced the total number of apoptotic cells in hearts receiving dopamine (7.1 +/- 1.8/1,000, p = 0.01 versus IR+D) to the extent seen in IR alone. DNA laddering and caspase-3 cleavage were observed at greater frequency in the IR+D group compared with the IR and IR+D+P groups. Propofol had no effect on dopamine-mediated increased systolic function, but improved diastolic function after ischemia. CONCLUSIONS: Dopamine infusion has a positive inotropic effect on the postischemic heart at the expense of increased cardiomyocyte apoptosis. The addition of propofol prevents dopamine-induced apoptosis after ischemia while maintaining positive inotropy.

Anesthetics, Intravenous↗
PubMed2006

Cardiac conduction through engineered tissue.

In children, interruption of cardiac atrioventricular (AV) electrical conduction can result from congenital defects, surgical interventions, and maternal autoimmune diseases during pregnancy. Complete AV conduction block is typically treated by implanting an electronic pacemaker device, although long-term pacing therapy in pediatric patients has significant complications. As a first step toward developing a substitute treatment, we implanted engineered tissue constructs in rat hearts to create an alternative AV conduction pathway. We found that skeletal muscle-derived cells in the constructs exhibited sustained electrical coupling through persistent expression and function of gap junction proteins. Using fluorescence in situ hybridization and polymerase chain reaction analyses, myogenic cells in the constructs were shown to survive in the AV groove of implanted hearts for the duration of the animal's natural life. Perfusion of hearts with fluorescently labeled lec-tin demonstrated that implanted tissues became vascularized and immunostaining verified the presence of proteins important in electromechanical integration of myogenic cells with surrounding re-cipient rat cardiomyocytes. Finally, using optical mapping and electrophysiological analyses, we provide evidence of permanent AV conduction through the implant in one-third of recipient animals. Our experiments provide a proof-of-principle that engineered tissue constructs can function as an electrical conduit and, ultimately, may offer a substitute treatment to conventional pacing therapy.

Animals↗
PubMed2005

Cyclosporin A but not FK-506 protects against dopamine-induced apoptosis in the stunned heart.

BACKGROUND: Dopamine given at moderate doses for inotropy to postischemic hearts has been shown to augment myocyte apoptosis in association with elevated cytosolic calcium. We hypothesize that dopamine-mediated apoptosis occurs through calcium-induced opening of the mitochondrial permeability transition (mPT) pore. We also hypothesize that cyclosporin A (CSA), a calcineurin inhibitor known to block mPT pore opening, would prevent dopamine-induced apoptosis primarily by inhibiting pore opening (cyclophilin D binding). METHODS: Isolated perfused rabbit hearts (n = 6/group) were subjected to 30 minutes of 37 degrees C cardioplegic arrest followed by 120 minutes reperfusion (ischemic injury that produces < 3% infarct by triphenyl-tetrazolium chloride [TTC] staining). Four groups were studied: (1) control; (2) dopamine (10 micromol/L) postischemia (dopa); (3) dopamine+CSA (0.2 micromol/L) (CSA+D) group; (4) dopamine+FK-506 (0.2 micromol/L) (FK+D) group. Left ventricular developed pressure and oxygen consumption were measured preischemia and postischemia. Bax, caspase-3 and caspase-9, and poly-ADP-ribose polymerase (PARP) activation were measured by Western blotting. Apoptotic nuclei were quantified by terminal deoxynucleotidyl transferase-mediated dUTP nick-end labeling (TUNEL) staining. RESULTS: Dopamine postischemia improved contractile function and heart rate and this was not affected by CSA or FK. However, TUNEL positive nuclei, Bax, caspase-3 and caspase-9 activation, and PARP cleavage were all increased in dopa and FK+D groups, but not in CSA+D. CONCLUSIONS: Cyclosporin is effective in preventing dopamine-induced apoptosis in the postischemic heart. The mechanism is likely due to inhibition of mPT pore opening since FK-506, a potent calcineurin inhibitor that does not bind to cyclophilin, did not prevent this. Low dose cyclosporin may prove useful to prevent dopamine-induced apoptosis resulting in long-term preservation of cardiac function.

Animals↗
PubMed2004

Promoting angiogenesis protects severely hypertrophied hearts from ischemic injury.

BACKGROUND: Myocardial hypertrophy is associated with progressive contractile dysfunction, increased vulnerability to ischemia-reperfusion injury, and is, therefore, a risk factor in cardiac surgery. During the progression of hypertrophy, a mismatch develops between the number of capillaries and cardiomyocytes per unit area, suggesting an increase in diffusion distance and the potential for limited supply of oxygen and nutrients. We hypothesized that promoting angiogenesis in hypertrophied hearts increases microvascular density, thereby improves tissue perfusion and substrate availability, maintains myocardial function, and improves postischemic recovery. METHODS: Left ventricular hypertrophy was created in 10-day-old rabbits by aortic banding and progression was monitored by echocardiography. At 4 weeks (compensated hypertrophy), 2 microg of vascular endothelial growth factor (VEGF) or placebo was administered intrapericardially. After 2 weeks, microvascular density, coronary flow (CF), and glucose uptake (GU) were measured. Tolerance to ischemia was determined by cardiac function measurements before and after ischemia-reperfusion using an isolated heart preparation. RESULTS: Microvascular density increased significantly following VEGF treatment (1.43 +/- 0.08/nuclei/field vs 1.04 +/- 0.06/nuclei/field untreated hypertrophy). Concomitantly, there was an increase in CF (7 +/- 0.5 vs 5 +/- 0.4 mL/min/g) and GU (1.24 +/- 0.2 vs 0.69 +/- 0.2 micromoles/g/30 minutes; p <or= 0.05). In vivo contractile function (-0.08 +/- 0.48 vs -1.39 +/- 0.35 untreated hypertrophy; p <or= 0.05) and postischemic myocardial recovery (% recovery: 93 +/- 2.0 vs 73 +/- 6.8 untreated hypertrophy; p <or= 0.05) were significantly improved in VEGF-treated hearts compared to untreated hypertrophied hearts. CONCLUSIONS: Treatment of hypertrophied hearts with VEGF resulted in an increase of microvascular density, improved tissue perfusion, and glucose delivery. Promoting angiogenesis proved useful in preserving myocardial function in late hypertrophy and improving postischemic recovery of contractile function.

Angiogenesis Inducing Agents↗
PubMed2003

Hypoxia and stretch regulate intercellular communication in vascular smooth muscle cells through reactive oxygen species formation.

OBJECTIVE: We hypothesized that the alterations in vasomotor tone and adaptive remodeling responses that occur in the circulation because of hypoxia were dependent on changes in cell to cell communication through regulation of gap junction protein expression and function. Consequently, we studied the amount, distribution, and permeability of the principal vascular smooth muscle cell (VSMC) gap junction protein, connexin43, in rat aortic cultures exposed to oxygen partial pressures of 150 or 15 mm Hg. METHODS AND RESULTS: Immunohistochemical staining, immunoblot assays, and Northern blot analyses demonstrated that connexin43 expression was reversibly increased in hypoxic cultures. As a result, hypoxic cells exhibited greater intercellular communication as determined by fluorescence recovery after photobleaching experiments. Using a fluorogenic substrate, hypoxic VSMCs showed increased reactive oxygen species generation, which could be prevented by the glutathione peroxidase mimic ebselen and the mitochondrial complex I inhibitor rotenone but not with the redox-sensitive thiol pyrrolidine dithiocarbamate. The rise in connexin43 expression attributable to hypoxia could be attenuated by ebselen and rotenone treatment. Interestingly, the previously reported induction of connexin43 expression by tensile stretch was also contingent on oxidative activity. CONCLUSIONS: Hypoxia and stretch increased gap junctional intercellular communication in VSMCs attributable to enhanced connexin43 expression initiated by reactive oxygen species formation.

Animals↗
PubMed2003

Postnatal increase in insulin-sensitive glucose transporter expression is associated with improved recovery of postischemic myocardial function.

OBJECTIVE: Glucose is an important substrate for energy production in the developing heart. Increased glucose uptake rate and metabolism during ischemia and reperfusion are closely linked to postischemic myocardial recovery. The initial rate-limiting step for glycolysis is the transport of glucose across the plasma membrane by glucose transporters (GLUT-1 and GLUT-4). We hypothesized that changes in GLUT-1 and GLUT-4 expression in developing hearts lead to age-dependent adaptive changes in glucose uptake capacity and influence tolerance to ischemia. METHODS: Western-immunoblotting was performed to determine GLUT-1 and GLUT-4 expression in myocardial tissue from 1, 2, and 3-week-old and adult rabbits. Glucose uptake rate was measured with (31)P-nuclear magnetic resonance spectroscopy using 2-deoxyglucose as substrate in isolated perfused hearts. Hearts from same age rabbits were perfused in the Langendorff mode with crystalloid buffer or buffer plus a GLUT-4 specific antibody in order to determine GLUT-4 mediated effects on myocardial protection. The hearts were subjected to 30 minutes of normothermic ischemia followed by reperfusion. Cardiac contractile function measurements were obtained pre- and postischemia. Tissue lactate accumulation was measured in all groups at end-ischemia CONCLUSIONS: Insulin-regulated glucose transporter (GLUT-4) expression in the heart increased gradually after birth reaching nearly adult levels by 3 weeks of age. Corresponding with the higher amount of GLUT-4 protein, improved recovery of postischemic contractile function was seen in older hearts in association with increased anaerobic glycolytic capacity. Interventions to accelerate postnatal GLUT-4 expression may improve ischemic tolerance in the neonatal heart.

Age Factors↗
PubMed2002

Differential effects of amrinone and milrinone upon myocardial inflammatory signaling.

BACKGROUND: Mounting evidence links systemic and local inflammatory cytokine production to myocardial dysfunction and injury occurring during ischemia-reperfusion, cardiopulmonary bypass, and heart failure. Phosphodiesterase inhibitors (PDEIs), used frequently in these states, can modulate inflammatory signaling. The mechanisms for these effects are unclear. We therefore examined the effects of 2 commonly used PDEIs, amrinone and milrinone, on cardiac cell inflammatory responses. METHODS AND RESULTS: Primary rat cardiomyocyte cultures were treated with endotoxin (LPS) or tumor necrosis factor-alpha (TNF-alpha), alone or in the presence of clinically relevant concentrations of amrinone or milrinone. Regulation of nuclear factor-kappa B (NFkappaB), nitric oxide synthase and cyclooxygenase isoforms, and cytokine production were assessed by electrophoretic mobility shift assays, Western immunoblotting, and enzyme-linked immunoassays, respectively. Both LPS and TNF-alpha induced significant NFkappaB activation, cyclooxygenase-2 (COX-2) expression, and inducible NO synthase (iNOS) and cytokine production; with the exception of COX-2 expression, all were significantly reduced by amrinone, beginning at concentrations of 10 to 50 micro mol/L. In contrast, milrinone increased nuclear NFkappaB translocation, iNOS and COX-2 expression, and cardiomyocyte production of interleukin-1beta. Cell-permeable cAMP increased inflammatory gene expression, whereas cell-permeable cGMP had no effect, indicating that the effects of amrinone were not due to phosphodiesterase inhibition. Similar results were seen in macrophages and coronary vascular endothelial cells. CONCLUSIONS: Both amrinone and milrinone have significant effects on cardiac inflammatory signaling. Overall, amrinone reduces activation of the key transcription factor NFkappaB and limits the production of pro-inflammatory cytokines, whereas milrinone does not.

Amrinone↗
PubMed2002

Dopamine treatment of postischemic contractile dysfunction rapidly induces calcium-dependent pro-apoptotic signaling.

BACKGROUND: Ischemia and adrenergic stimulation of cardiomyocyte cultures have been shown to induce apoptotic cell death. We hypothesized that in a model of contractile dysfunction following ischemia, a commonly used catecholamine such as dopamine augments cardiomyocyte apoptosis via activation of calcium-dependent signaling cascades. METHODS AND RESULTS: Isolated perfused rabbit hearts were subjected to 45 minutes of normothermic ischemia with cardioplegic arrest. Hearts were reperfused for 120 minutes with unmodified perfusate (control), perfusate containing 20 nM dopamine, dopamine+2,3-butanedione monoxime (BDM), a MgATPase-inhibitor, or the calcium-sensitizing inotrope ORG 30029. Ischemia-reperfusion alone caused contractile dysfunction without significant myocardial necrosis (left ventricular pressure-volume curves; 1% triphenyltetrazolium chloride staining; creatine kinase release) or apoptosis (terminal deoxynucleotidyl transferase-mediated nick end labeling [TUNEL] analysis; immunoblotting for poly(ADP-ribose) polymerase [PARP] cleavage; activation of caspases-3, -8, and -9; expression of Bax/Bcl-2). Intracellular calcium [Ca2+]i measured by rhod-2 spectrofluorometry was increased in dopamine-reperfused hearts. Although postischemic dopamine treatment improved contractility, the number of apoptotic cardiomyocytes was significantly higher than in untreated postischemic hearts (32.5+/-9 versus 5.5+/-1.6/1000 nuclei, P<0.01). Further evidence of dopamine-stimulated apoptosis included PARP cleavage, activation of mitochondrial-derived caspase-9, and the terminal effector caspase-3. Dopamine also increased cellular content of pro-apoptotic Bax while decreasing anti-apoptotic Bcl-2. Simultaneous treatment with BDM suppressed contractility without affecting [Ca2+]i and did not reduce dopamine-stimulated apoptotic markers. When contractility was increased without elevating [Ca2+]i using ORG 30029, no activation of pro-apoptotic signaling cascades was found. Dopamine infusion in nonischemic hearts did not result in cardiomyocyte apoptosis. CONCLUSIONS: Postischemic dopamine treatment of contractile dysfunction activates pro-apoptotic signal cascades, most likely via a calcium-dependent process and mitochondrial damage.

Animals↗
PubMed2002

Protective effects of protein kinase C during myocardial ischemia require activation of phosphatidyl-inositol specific phospholipase C.

BACKGROUND: Protein kinase C (PKC) activation during myocardial ischemia is thought to be cardioprotective. However, the mechanism of ischemia-induced PKC activation remains unclear. We hypothesized that ischemic PKC activation occurs through activation of phosphatidyl-inositol specific phospholipase C (PI-PLC) and protects the heart from ischemic injury. METHODS: Isolated rabbit hearts were subjected to 20 minutes of normothermic ischemia and reperfusion. The PI-PLC inhibitor U73122 (0.5 micromol/L), its inactive analogue U73343 (0.5 micromol/L), or the PKC inhibitor chelerythrine (2 micromol/L) were given just before ischemia. Another group received U73122 plus the direct PKC activator phorbol 12-myristate-13-acetate (PMA, 10 pmol/L). Measurements included contractile function, intracellular calcium, PI-PLC activity, and translocation of PKC isoforms. RESULTS: PI-PLC activity increased during myocardial ischemia and was inhibited by U73122. PI-PLC inhibition prevented the ischemic translocation of PKC-alpha, PKC-epsilon, and PKC-eta, and impaired cardiac recovery and cytosolic calcium regulation without significant changes in energy metabolism. PMA restored both contractile function and PKC translocation pattern in U73122-treated hearts. Direct PKC inhibition with chelerythrine mimicked the effects of U73122. CONCLUSIONS: PI-PLC mediates PKC translocation during myocardial ischemia. Inhibition of PI-PLC or PKC activation, or both, during ischemia significantly impairs postischemic myocardial recovery.

Adenosine Triphosphate↗
PubMed2002

Diazoxide amelioration of myocardial injury and mitochondrial damage during cardiac surgery.

BACKGROUND: Recently, we have shown that the selective opening of mitochondrial ATP-sensitive potassium channels with diazoxide significantly decreases myocardial injury. The purpose of this study was to determine the effects of diazoxide on apoptosis and the mechanisms modulating apoptosis and myocardial injury in a blood-perfused model of acute myocardial infarction. METHODS: Pigs (32 to 42 kg) undergoing total cardiopulmonary bypass underwent left anterior descending coronary artery occlusion for 30 minutes. The aorta was cross-clamped and magnesium-supplemented potassium cold-blood cardioplegia (DSA; n = 6) or magnesium-supplemented potassium cardioplegia containing 50 micromol/L diazoxide (DZX; n = 6) was administered, followed by 30 minutes of global ischemia and 120 minutes of reperfusion. Left ventricular tissue samples from DSA and DZX hearts were obtained after reperfusion. Apoptosis was determined by TUNEL, caspase-3 and PARP cleavage, and caspase-3 activity. Bax and bcl-2 levels were determined and tissue morphology was examined by light and transmission electron microscopy. RESULTS: Apoptosis, as estimated by TUNEL-positive nuclei/3,000 myocardial cells, was 120.3 +/- 48.8 in DSA hearts and was significantly decreased to 21.4 +/- 5.3 in DZX hearts (p < 0.05 vs control). Caspase-3 and poly-ADP-ribose polymerase cleavage and pro-apoptotic bax protein levels were significantly decreased with diazoxide (p < 0.05 vs DSA). Light and transmission electron microscopy indicated severe disruption of tissue with capillary dilatation, mitochondrial cristae damage, and evidence of increased presence of mitochondrial granules in DSA as compared with DZX hearts. CONCLUSIONS: The addition of diazoxide (50 micromol/L) to cardioplegia significantly decreases regional myocardial apoptosis and mitochondrial damage, and provides an additional modality for achieving myocardial protection.

Animals↗
PubMed2002

Selective opening of mitochondrial ATP-sensitive potassium channels during surgically induced myocardial ischemia decreases necrosis and apoptosis.

OBJECTIVE: Mitochondrial ATP-sensitive potassium channels have been proposed to be myoprotective. The relevance and specificity of this mechanism in cardiac surgery was unknown. The purpose of this study was to examine the effects of the mitochondrial potassium ATP-sensitive channel opener diazoxide on regional and global myocardial protection using a model of acute myocardial infarction. METHODS: Pigs (n=19) were placed on total cardiopulmonary bypass and then subjected to 30 min normothermic regional ischemia by snaring the left anterior descending coronary artery (LAD). The aorta was then crossclamped and cold blood Deaconess Surgical Associates cardioplegia (DSA; n=6) or DSA containing 50 microM diazoxide (DZX; n=6) was delivered via the aortic root and the hearts subjected to 30 min hypothermic global ischemia. The crossclamp and snare were removed and the hearts reperfused for 120 min. RESULTS: No significant differences in preload recruitable stroke work relationship, Tau, proximal, distal or proximal/distal coronary flow, regional or global segmental shortening, systolic bulging or post-systolic shortening were observed within or between DSA and DZX hearts during reperfusion. Infarct was present only in the region of LAD occlusion in both DSA and DZX hearts. Infarct size (% of area at risk) was 33.6+/-2.9% in DSA and was 16.8+/-2.4% in DZX hearts (P<0.01 versus DSA). Apoptosis as estimated by TUNEL positive nuclei was 120.3+/-48.8 in DSA and was significantly decreased to 21.4+/-5.3 in DZX hearts. Myocardial infarct was located centrally within the area at risk in both DSA and DZX hearts but was significantly increased at borderline zones within the area at risk in DSA hearts. CONCLUSIONS: The addition of diazoxide to cardioplegia significantly decreases regional myocardial cell necrosis and apoptosis in a model of acute myocardial infarction and represents an additional modality for achieving myocardial protection.

Animals↗
PubMed2002

The characterization and purification of a human transcription factor modulating the glutathione peroxidase gene in response to oxygen tension.

An oxygen responsive transcription factor regulating human glutathione peroxidase gene (GPx) through two oxygen responsive elements (ORE I and ORE2) has been purified and characterized by sequence-specific DNA affinity chromatography. The DNA binding activity, termed Oxygen Responsive Element Binding Protein (OREBP), was partially represented by a 77 kD polypeptide (p70) possessing a blocked N-terminus. The p70 subunit co-eluted with an 86 kD subunit (p80) from affinity columns. N-terminal sequencing analysis of the 86 kD component revealed that this protein represented the larger member of the Ku antigen complex. The identity of the purified 77 kD subunit was determined by Western blot analysis using an antibody directed against the p70 protein. In addition to binding the GPx-ORE, the OREBP was itself regulated by oxygen tension. It was found that the abundance of the ORE binding activity was decreased in cells maintained at low oxygen tension (40 mm Hg). Anti-Ku-antibodies specifically supershifted the OREBP-ORE DNA complex. These observations further add to the numerous nuclear roles of the Ku-transcription factor.

Antibodies↗
PubMed2002

Levels of soluble adhesion molecules are elevated in the cerebrospinal fluid of children with moyamoya syndrome.

OBJECTIVE: The pathogenesis of moyamoya syndrome is unknown; however, previous studies suggested an inflammatory component. Because adhesion molecules mediate inflammation during cerebral ischemia, we measured the levels of soluble isoforms of the endothelial adhesion molecules vascular cell adhesion molecule Type 1, intercellular adhesion molecule Type 1, and E-selectin in serum and cerebrospinal fluid (CSF) samples from children with moyamoya syndrome. METHODS: Serum and CSF samples were obtained from children with moyamoya syndrome (n = 20) and patients with congenital spinal deformities (n = 20). Soluble vascular cell adhesion molecule Type 1, intercellular adhesion molecule Type 1, and E-selectin levels were measured in enzyme-linked immunoassays. The correlation between the levels of soluble adhesion molecules and the Suzuki angiographic classification was analyzed. CSF/serum albumin index values were also measured, to determine the integrity of the blood-brain barrier. RESULTS: Compared with the control group, children with moyamoya syndrome exhibited significantly elevated CSF levels of soluble vascular cell adhesion molecule Type 1, intercellular adhesion molecule Type 1, and E-selectin. The albumin index for the moyamoya group was 9, which was significantly higher than that for the control group. However, there were no differences in the serum levels of the three soluble adhesion molecules and no correlations between age, Suzuki classification, and serum and CSF levels of adhesion molecules. CONCLUSION: Our study demonstrates increased CSF levels of soluble endothelial adhesion molecules, suggesting that children with moyamoya syndrome have ongoing central nervous system inflammation, with slight impairment of the blood-brain barrier. These soluble adhesion molecules may be clinically useful as indicators of this inflammatory process and may provide some insight into this enigmatic disease process.

Arnold-Chiari Malformation↗