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ABSTRACT: The binding of Tyr-D-Arg(2)-Phe-sarcosine(Sar)(4) (TAPS), a proposed mu-opioid receptor-selective tetrapeptide analog of dermorphin to opioid receptors, was studied using selective binding assays for subtypes of mu-, delta- and kappa-opioid receptors. Subtype specific mu-opioid receptor binding was further characterized in the presence of sodium and guanosine nucleotides and the activity of TAPS in isolated guinea pig ileum was compared to other mu-opioid receptor-selective ligands. Further, the antinociceptive properties of TAPS following intrathecal (i.t.) administration in rats, as a model of spinal antinociception, were evaluated. The K(i)-values for TAPS at the mu(1)- and mu(2)-opioid receptor sites were 0.4 and 1.3 nM, respectively, suggesting high affinity binding to mu-opioid receptor binding sites with an increased selectivity to mu(1)-opioid receptor sites. The attenuated reduction of TAPS binding at the mu(2)-opioid receptor subtype in the presence of the stable guanosintriphosphate analog 5'-guanylylimidodiphosphate and sodium suggests a potential partial antagonist mode of action at this site.
European Journal of Pharmacology 04/2001; 416(1-2):83-93. · 2.52 Impact Factor
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ABSTRACT: A humanized inhibitory anti-factor IX(a) antibody (SB 249417) has been compared to enoxaparin (Lovenox) in a rat model of arterial thrombosis. Pretreatment of rats with either SB 249417 (3.0 mg/kg, i. v.) or enoxaparin (30.0 mg/kg, i.v. or s.c.) resulted in comparable and significant reductions in thrombus formation. However, the efficacious dose of enoxaparin resulted in >30-fold increase in the aPTT over baseline, while the efficacious dose of SB 249417 prolonged the aPTT by only approximately 3-fold. Additionally, pretreatment with SB 249417 resulted in sustained blood flow and arterial patency throughout the experiment in >80% of rats treated. In contrast, <30% of rats pretreated with enoxaparin remained patent throughout the experiment. The data in this report indicate that the selective inhibition of factor IX(a) with the monoclonal antibody SB 249417 produces a superior antithrombotic profile to that of the low molecular weight heparin enoxaparin.
Thrombosis Research 11/2000; 100(1):73-9. · 2.44 Impact Factor
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ABSTRACT: Chemokines are potent proinflammatory and immune modulators. Increased expression of chemokines, eg, monocyte chemoattractant protein-1 (MCP-1), has recently been described in clinical and experimental heart failure. The present report is aimed at exploring the expression, localization, and binding site regulation of MCP-1, a member of the C-C chemokine family, in a rat model of volume-overload congestive heart failure (CHF).
An aortocaval fistula was surgically created between the abdominal aorta and inferior vena cava. Rats with CHF were further subdivided into compensated and decompensated subgroups. Northern blot analysis and real-time quantitative polymerase chain reaction demonstrated upregulation of MCP-1 mRNA expression correlating with the severity of CHF (288+/-22, 502+/-62, and 826+/-138 copies/ng total RNA for sham, compensated, and decompensated animals, respectively; n=5, P:<0.05). MCP-1 protein was localized by immunohistochemistry in cardiomyocytes, vascular endothelium and smooth muscle cells, infiltrating leukocytes, and interstitial fibroblasts, and its intensity increased with severity of CHF. In addition, rats with CHF displayed a significant decrease of (125)I-labeled MCP-1 binding sites to myocardium-derived membranes (384.3+/-57.0, 181.3+/-8.8, and 123.3+/-14.1 fmol/mg protein for sham, compensated, and decompensated animals, respectively).
Volume-overload CHF in rats is associated with alterations in the expression, immunohistochemical localization, and receptor binding of the MCP-1 chemokine in the myocardium. These changes were more pronounced in rats with decompensated CHF. The data suggest that activation of the MCP-1 system may contribute to the progressive cardiac decompensation and development of CHF in rats with aortocaval fistula.
Circulation 10/2000; 102(11):1315-22. · 14.74 Impact Factor
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ABSTRACT: We have established a focal preconditioning (PC) paradigm that produces significant and prolonged ischemic tolerance (IT) of the brain to subsequent permanent middle cerebral artery occlusion (MCAO). PC using 10 min of MCAO induces brain tolerance at 1-7 days of reperfusion that requires active protein synthesis. The protective protein(s) involved are unknown. In these studies the increased transcription and translation of the inducible 70-kDa heat shock protein (Hsp70) and the 27-kDa heat shock protein (Hsp27), and astrogliosis/glial fibrillary acidic protein (GFAP) were determined by Northern analysis and immunohistochemistry following PC. Cellular localization of proteins was determined by double labeling. PC produced no brain injury but did increase Hsp70 mRNA transiently at 6 h and increased Hsp27 mRNA later at 24 h for at least 5 days. Protein expression induced by PC exhibited a similar profile. Hsp70 protein was primarily expressed in neurons from 1 to 5 days post-PC throughout the PC cortex. Hsp27 protein expression was initiated later for a much longer period of time. A remarkable astroglyosis was verified with increased astrocytic Hsp27 from 1 to 7 days after PC. Gliosis with increased Hsp27 in the PC cortex was still present but reduced 4 weeks after PC. Therefore, PC that results in brain tolerance/neuroprotection increases neuronal Hsp70 in the PC cortex and activated astrocytic Hsp27 in the PC cortex in a temporal fashion associated with developing IT. The short duration of benign ischemia (PC) that produces IT produces a robust, long-lived cellular and protein synthetic response that extends throughout the entire cortex (i.e. well beyond the MCA perfusion territory). The resulting IT is associated with changes in astrocyte-activation that might provide increased support and protection from injury. Although both Hsp70 and Hsp27 may participate in the neuroprotection/brain tolerance induced by PC, the temporal expression patterns of these proteins indicate that they are not solely responsible for the tolerance to brain injury.
Brain Research 05/2000; 863(1-2):169-81. · 2.73 Impact Factor
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ABSTRACT: Interleukin-1beta (IL-1beta) is a pleiotropic cytokine capable of inducing smooth muscle activation and leukocyte recruitment in restenosis and atherosclerosis. Our present study investigated the expression of IL-1beta, IL-1 receptor antagonist (IL-1ra), and IL-1 receptor (IL-1RI and IL-1RII) mRNA in carotid artery after balloon angioplasty using semiquantitative reverse transcription/polymerase chain reaction (RT/PCR) and Northern analysis. Time course studies revealed that IL-1beta mRNA was rapidly induced at 6 h (30-fold increase over control, P < 0.001) post balloon injury and diminished to basal levels at 24 h. The increased expression of IL-1ra mRNA was delayed, reaching a peak at 24 h (400-fold increase, P < 0.001) and sustained up to 14 days. The expression of IL-1RII mRNA was remarkably similar to that of IL-1beta, whereas the IL-1RI (the signaling receptor) mRNA expression was delayed (significantly induced at day 1; 14.2-fold increase, P < 0.01) post balloon injury. Immunohistochemical studies revealed a strong induction of IL-1beta in the area with actively proliferating and migrating smooth muscle cells (i.e., in the inner medial layer at day 1 and in neointima at day 14 after balloon injury). The differential but concomitant expression of IL-1beta, IL-1ra, IL-1RI, and IL-1RII mRNAs after balloon angioplasty suggests that each of these IL-1 system components may play a distinct role in neointima formation.
Biochemical and Biophysical Research Communications 04/2000; 271(1):138-43. · 2.48 Impact Factor
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ABSTRACT: Three major mammalian mitogen-activated protein kinases, extracellular signal-regulated kinase (ERK), p38, and c-Jun NH(2)-terminal protein kinase (JNK), have been identified in the cardiomyocyte, but their respective roles in the heart are not well understood. The present study explored their functions and cross talk in ischemia/reoxygenation (I/R)-induced cardiac apoptosis. Exposing rat neonatal cardiomyocytes to ischemia resulted in a rapid and transient activation of ERK, p38, and JNK. On reoxygenation, further activation of all 3 mitogen-activated protein kinases was noted; peak activities increased (fold) by 5.5, 5.2, and 6.2, respectively. Visual inspection of myocytes exposed to I/R identified 18.6% of the cells as showing morphological features of apoptosis, which was further confirmed by DNA ladder and terminal deoxyribonucleotide transferase-mediated dUTP nick end labeling (TUNEL). Myocytes treated with PD98059, a MAPK/ERK kinase (MEK1/MEK2) inhibitor, displayed a suppression of I/R-induced ERK activation, whereas p38 and JNK activities were increased by 70.3% and 55.0%, respectively. In addition, the number of apoptotic cells was increased to 33.4%. With pretreatment of cells with SB242719, a selective p38 inhibitor, or SB203580, a p38 and JNK2 inhibitor, I/R+PD98059-induced apoptotic cells were reduced by 42.8% and 63.3%, respectively. Hearts isolated from rats treated with PD98059 and subjected to global ischemia (30 minutes)/reoxygenation (1 hour) showed a diminished functional recovery compared with the vehicle group. Coadministration of SB203580 attenuated the detrimental effects of PD98059 and significantly improved cardiac functional recovery. The data taken together suggest that ERK plays a protective role, whereas p38 and JNK mediate apoptosis in cardiomyocytes subjected to I/R, and the dynamic balance of their activities is critical in determining cardiomyocyte fate subsequent to reperfusional injury.
Circulation Research 04/2000; 86(6):692-9. · 9.49 Impact Factor
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ABSTRACT: A short duration of ischemia (i.e., ischemic preconditioning) was shown to result in significant tolerance to subsequent ischemic injury. Since previous reports suggest that interleukin-1beta (IL-1beta) may be involved in both ischemic damage and neuroprotection, the present work examined the expression of IL-1beta mRNA in cortical brain tissue after an established preconditioning (PC) stimulus known to produce significant brain tolerance to focal stroke after 1-7 days. Significant induction of IL-1beta mRNA was observed in the ipsilateral cortex at 6 hr (87+/-9 copies of the mRNA per microgram of brain tissue compared to 16+/-5 copies in sham-operated samples, P < 0.001, n = 4) and 8 hr (46+/-4 copies, P < 0.01, n = 4) after PC by means of real-time Taqman polymerase chain reaction (PCR). The peak expression of IL-1beta mRNA after PC was significantly (P < 0.01) lower than that after permanent occlusion of the middle cerebral artery (MCAO), i.e., 87+/-9 and 546+/-92 copies of RNA per microgram tissue at peak levels for PC and focal stroke, respectively. Immunohistochemistry studies revealed a parallel induction of IL-1beta in the ipsilateral cortex after PC. The maximal expression of IL-1beta was observed during the first week post-PC, showing marked parallelism with the duration of ischemic tolerance. These data suggest that the significant but low levels of IL-1beta induction after PC may contribute to ischemic brain tolerance.
Journal of Neuroscience Research 02/2000; 59(2):238-46. · 2.74 Impact Factor
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ABSTRACT: A short duration of ischemia (i.e., ischemic preconditioning) results in significant brain protection to subsequent severe ischemic insult. Because previous studies suggest that tumor necrosis factor-alpha (TNF-alpha) plays a role in both promoting ischemic damage and neuroprotection, the present work aimed to evaluate the expression of TNF-alpha mRNA in an established model of ischemic preconditioning using a transient 10-minute occlusion of the middle cerebral artery. Because the level of TNF-alpha mRNA expression in the brain was too low to be consistently detected by Northern technique, a real-time polymerase chain reaction method was applied to quantitate the absolute copy number of TNF-alpha transcript in rat brain after the preconditioning procedure. TNF-alpha mRNA was induced in the ipsilateral cortex as early as 1 hour (27 +/- 1 copies of mRNA per microgram of tissue compared to 11 +/- 3 copies in sham-operated samples) after preconditioning, reached a peak level at 6 hours (49 +/- 10 copies of transcript, n = 4, P < 0.01), and persisted up to 2 days. These data not only demonstrate the utility of real-time polymerase chain reaction for sensitive and accurate measurement of mRNA expression in normal and injured tissues but also suggest a potential role of TNF-alpha in the phenomenon of ischemic preconditioning.
Journal of Cerebral Blood Flow & Metabolism 01/2000; 20(1):15-20. · 5.01 Impact Factor
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ABSTRACT: An inhibitory anti-factor IX/IXa antibody (BC2) has been investigated as an anti-thrombotic agent in a rat venous thrombosis model. The treatment of rats post-injury with a single bolus dose of BC2 (3 mg/kg, i.v.) resulted in an approximately 4 fold reduction in venous thrombus mass (P = 0.043). This efficacy was matched by a minimal (<2.5 fold) prolongation of the aPTT and had no effect on the prothrombin time (PT). Heparin by comparison, given as a bolus followed by continuous infusion, at doses comparable in efficacy at reducing thrombus formation, prolonged the aPTT >50 fold. These results demonstrate that the anti-factor IX/IXa antibody (BC2), when compared to heparin, can effectively reduce venous thrombosis with less disruptive consequences on blood clotting.
Thrombosis and Haemostasis 11/1999; 82(5):1443-5. · 5.04 Impact Factor
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ABSTRACT: A murine antihuman factor IX monoclonal antibody (BC2) has been generated and evaluated for its capacity to prolong the activated partial thromboplastin time (aPTT) in vitro and ex vivo and to prevent arterial thrombosis in a rat model in vivo. BC2 extended aPTT to a maximum of 60 to 80 seconds at 100 to 1000 nmol/L in vitro (rat and human plasma, respectively) and ex vivo (rat) after dosing of rats up to 6 mg/kg in vivo. BC2, administered as bolus (1 to 6 mg/kg) followed by infusion (0.3 to 2 mg x kg(-1) x h(-1)), dose-dependently prevented thrombosis of an injured rat carotid artery (FeCl(3)-patch model), increased time to artery occlusion, and reduced incidence of vessel occlusion. BC2 efficacy in preventing arterial thrombosis exceeded that of heparin (bolus 15 to 120 U/kg followed by infusion 0.5 to 4.0 U x kg(-1) x min(-1)), whereas the latter rendered the blood incoagulable (aPTT>1000 seconds). BC2 demonstrated complete antithrombotic efficacy also as a single bolus given either as prevessel or postvessel injury as evidenced by reduction of thrombus mass (from 4.18+/-0.49 to 1.80 +/-0.3 mg, P<0.001), increasing vessel patency time (from 14.9+/-0.9 minutes to 58.3+/-1.7 minutes, P<0.001) and decreasing incidence of vessel occlusion from 100% to 0% in vehicle- versus BC2-treated rats, respectively. BC2 (3 mg/kg, IV) administered in a single bolus resulted in 50% reduction in thrombus mass (P<0.01), extended vessel patency time (P<0.001), extended aPTT only 4-fold, and had no effect on blood loss via a tail surgical wound; heparin, at doses that reduced thrombus mass to a similar extent, extended aPTT beyond 1000 seconds (over 500-fold) and increased blood loss from 1.8+/-0.7 to 3.3 +/-0.6 mL (P<0.001). These data suggest that BC2 may provide enhanced therapeutic efficacy in humans at lesser interference with blood hemostasis than heparin.
Arteriosclerosis Thrombosis and Vascular Biology 11/1999; 19(10):2554-62. · 6.37 Impact Factor
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ABSTRACT: Contrary to previous dogmas, it is now well established that brain cells can produce cytokines and chemokines, and can express adhesion molecules that enable an in situ inflammatory reaction. The accumulation of neutrophils early after brain injury is believed to contribute to the degree of brain tissue loss. Support for this hypothesis has been drawn from many studies where neutrophil-depletion blockade of endothelial-leukocyte interactions has been achieved by various techniques. The inflammation reaction is an attractive pharmacologic opportunity, considering its rapid initiation and progression over many hours after stroke and its contribution to evolution of tissue injury. While the expression of inflammatory cytokines that may contribute to ischemic injury has been repeatedly demonstrated, cytokines may also provide "neuroprotection" in certain conditions by promoting growth, repair, and ultimately, enhanced functional recovery. Significant additional basic work is required to understand the dynamic, complex, and time-dependent destructive and protective processes associated with inflammation mediators produced after brain injury. The realization that brain ischemia and trauma elicit robust inflammation in the brain provides fertile ground for discovery of novel therapeutic agents for stroke and neurotrauma. Inhibition of the mitogen-activated protein kinase (MAPK) cascade via cytokine suppressive anti-inflammatory drugs, which block p38 MAPK and hence the production of interleukin-1 and tumor necrosis factor-alpha, are most promising new opportunities. However, spatial and temporal considerations need to be exercised to elucidate the best opportunities for selective inhibitors for specific inflammatory mediators.
Journal of Cerebral Blood Flow & Metabolism 09/1999; 19(8):819-34. · 5.01 Impact Factor
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ABSTRACT: A number of studies have provided evidence that neuronal cell loss after stroke involves programmed cell death or apoptosis. In particular, recent biochemical and immunohistochemical studies have demonstrated the expression and activation of intracellular proteases, notably caspase-3, which act as both initiators and executors of the apoptotic process. To further elucidate the involvement of caspases in neuronal cell death induced by focal stroke we developed a panel of antibodies and investigated the spatial and temporal pattern of both caspase-8 and caspase-3 expression. Our efforts focused on caspase-8 because its "apical" position within the enzymatic cascade of caspases makes it a potentially important therapeutic target. Constitutive expression of procaspase-8 was detectable in most cortical neurons, and proteolytic processing yielding the active form of caspase-8 was found as early as 6 hr after focal stroke induced in rats by permanent middle cerebral artery occlusion. This active form of caspase-8 was predominantly seen in the large pyramidal neurons of lamina V. Active caspase-3 was evident only in neurons located within lamina II/III starting at 24 hr after injury and in microglia throughout the core infarct at all times examined. Terminal deoxynucleotidyl transferase-mediated biotinylated UTP nick end labeling, gel electrophoresis of DNA, and neuronal cell quantitation indicated that there was an early nonapoptotic loss of cortical neurons followed by a progressive elimination of neurons with features of apoptosis. These data indicate that the pattern of caspase expression occurring during delayed neuronal cell death after focal stroke will vary depending on the neuronal phenotype.
Journal of Neuroscience 08/1999; 19(14):5932-41. · 7.11 Impact Factor
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ABSTRACT: The neuroprotective effects of isradipine, a 2,4-dihydropyridine calcium channel blocker, has been well studied in the rat model of focal ischemia (induced by middle cerebral artery occlusion, MCAO). The present study was designed to evaluate whether isradipine pretreatment caused early (0-3 h after stroke) ischemic changes in diffusion- weighted magnetic resonance imaging (DWI) and if such changes were predictive of previously documented protection in brain infarction. An initial dose-response study using neurological deficit scores and estimates of protection from brain infarction (by histology) showed that isradipine reduced cortical infarctions compared to vehicle-treated animals at most doses (between 1.25 and 5 mg/kg/day s.c. for 6 days) with the best results obtained at 5 mg/kg/day, where a 78.5% reduction was observed. This dose was utilized to perform the DWI study. Early quantitative estimates of infarct size, as measured by DWI at 1, 2 and 3 h after MCAO, were similar to those obtained with late histology at 24 h. These data indicate that in pretreatment protocols, DWI can be used to quantitatively predict areas at risk of permanent damage. This work also demonstrates that neurological deficits, developing from the damaged forebrain following focal stroke, may provide an index of isradipine's neuroprotective activity.
Pharmacology 07/1999; 58(6):292-9. · 1.79 Impact Factor
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ABSTRACT: Activation of p38 mitogen-activated protein kinase (MAPK) plays an important role in apoptotic cell death. The role of p38 MAPK in myocardial injury caused by ischemia/reperfusion, an extreme stress to the heart, is unknown.
Studies were performed with isolated, Langendorff-perfused rabbit hearts. Ischemia alone caused a moderate but transient increase in p38 MAPK activity (3.5-fold increase, P<0.05 versus basal). Ischemia followed by reperfusion further activated p38 MAPK, and the maximal level of activation (6.3-fold, P<0.01) was reached 10 minutes after reperfusion. Administration of SB 203580, a p38 MAPK inhibitor, decreased myocardial apoptosis (14.7+/-3.2% versus 30.6+/-3.5% in vehicle, P<0.01) and improved postischemic cardiac function. The cardioprotective effects of SB 203580 were closely related to its inhibition of p38 MAPK. Administering SB 203580 before ischemia and during reperfusion completely inhibited p38 MAPK activation and exerted the most cardioprotective effects. In contrast, administering SB 203580 10 minutes after reperfusion (a time point when maximal MAPK activation had already been achieved) failed to convey significant cardioprotection. Moreover, inhibition of p38 MAPK attenuated myocardial necrosis after a prolonged reperfusion.
These results demonstrate that p38 MAPK plays a pivotal role in the signal transduction pathway mediating postischemic myocardial apoptosis and that inhibiting p38 MAPK may attenuate reperfusion injury.
Circulation 04/1999; 99(13):1685-91. · 14.74 Impact Factor
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ABSTRACT: Following an ischemic insult to the central nervous system a reorganization of cells and tissue takes place as the surrounding cells attempt to limit the injury, repair the damage, and restore normal architecture of the brain. This tissue remodeling requires de novo synthesis of genes and proteins which enables cells to actively change their relationship with the existing extracellular matrix and with other cells to reorganize the damaged tissue. We have identified two key molecular components of the matrix remodeling process after focal ischemia: osteopontin (OPN) and its integrin receptor alpha v beta 3 (alpha v beta 3). OPN is initially expressed by activated macrophages and microglia in the periinfarct region (24-48 hr) and at later times (5-15 days) in the core infarct. After focal stroke the alpha v beta 3 was upregulated by astrocytes in the periinfarct region. Spatial and temporal analyses demonstrated that at 5 days after injury the alpha v beta 3-positive astrocytes were at a distance from the osteopontin-expressing macrophages; by 15 days the alpha v beta 3-expressing astrocytes were localized within an osteopontin-rich matrix. In vitro OPN was shown to induce migration of astrocytes in a Boyden chamber system. These data suggest that OPN derived from microglia at the infarct border zone (and possible macrophages in the infarct core) may serve as an "astrokine" (suggested term for astrocyte chemoattractant) to organize the astrocyte scar after focal stroke. Our data demonstrate profound changes in brain matrix remodeling after focal ischemic stroke, including the synthesis and release of matrix proteins alien to the normal brain, the expression of integrin receptors that ligate these proteins, and possibly a novel function for microglial-derived OPN in astrocyte migration after focal ischemia that may drive glial activation, organization, and repair functions.
Annals of the New York Academy of Sciences 02/1999; 890:204-22. · 3.15 Impact Factor
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T L Yue,
J Ni,
A M Romanic,
J L Gu,
P Keller,
C Wang,
S Kumar,
G L Yu,
T K Hart,
X Wang,
Z Xia,
W E DeWolf, G Z Feuerstein
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ABSTRACT: TL1 is a recently discovered novel member of the tumor necrosis factor (TNF) cytokine family. TL1 is abundantly expressed in endothelial cells, but its function is not known. The present study was undertaken to explore whether TL1 induces apoptosis in endothelial cells and, if so, to explore its mechanism of action. Cultured bovine pulmonary artery endothelial cells (BPAEC) exposed to TL1 showed morphological (including ultrastructural) and biochemical features characteristic of apoptosis. TL1-induced apoptosis in BPAEC was a time- and concentration-dependent process (EC50 = 72 ng/ml). The effect of TL1 was not inhibited by soluble TNF receptors 1 or 2. TL1 up-regulated Fas expression in BPAEC at 8 and 24 h after treatment, and significantly activated stress-activated protein kinase (SAPK) and p38 mitogen-activated protein kinase (p38 MAPK). The peak activities of SAPK and p38 MAPK in TL1-treated BPAEC were increased by 9- and 4-fold, respectively. TL1-induced apoptosis in the BPAEC was reduced by expression of a dominant-interfering mutant of c-Jun (62.8%, p < 0.05) or by a specific p38 inhibitor, SB203580 (1-10 microM) dose-dependently. TL1 also activated caspases in BPAEC, and TL1-induced apoptosis in BPAEC was significantly attenuated by the caspase inhibitor, ZVAD-fluromethyl-ketone. The major component activated by TL1 in BPAEC was caspase-3, which was based on substrate specificity and immunocytochemical analysis. These findings suggest that TL1 may act as an autocrine factor to induce apoptosis in endothelial cells via activation of multiple signaling pathways, including stress protein kinases as well as certain caspases.
Journal of Biological Chemistry 01/1999; 274(3):1479-86. · 4.77 Impact Factor
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ABSTRACT: Brief occlusion of the middle cerebral artery (i.e., ischemic preconditioning; PC) induces significant brain protection to subsequent severe ischemic events. In an effort to discover genes responsible for ischemic tolerance, we have applied a new technique, suppression subtractive hybridization (SSH), to identify genes that are upregulated by PC. Using this SSH approach, a cDNA that encodes tissue inhibitor of matrix metalloproteinase- (TIMP-1) was identified. Time course studies using Northern analysis revealed that TIMP-1 mRNA was significantly elevated at 24 hours (3.3-fold over controls, P < 0.05, n = 5) and 2 days (4.3-fold increase, P < 0.01) after PC, corresponding to the onset of significant ischemic tolerance. Our data not only demonstrate the utility of this new polymerase chain reaction-based SSH strategy for discovery of genes differentially expressed in PC, but also suggest a potential role of TIMP-1 in PC-induced ischemic tolerance.
Journal of Cerebral Blood Flow & Metabolism 11/1998; 18(11):1173-7. · 5.01 Impact Factor
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ABSTRACT: Activation of the renin-angiotensin system may contribute to the derangement in renal and cardiac function in congestive heart failure. The present study evaluated the effects of eprosartan, a selective angiotensin II receptor antagonist, on renal hemodynamic and excretory parameters and on the development of cardiac hypertrophy in rats with aortocaval fistula, an experimental model of congestive heart failure. Infusion of eprosartan (1.0 mg/kg) in rats with aortocaval fistula produced a significant increase (+34%) in total renal blood flow and a sustained decrease (-33%) in the calculated renal vascular resistance. These effects on renal hemodynamics were more pronounced than those observed in sham-operated control rats and occurred despite a significant fall (-12%) in mean arterial blood pressure. Moreover, eprosartan caused a preferential increase in renal cortical blood perfusion and significantly increased glomerular filtration in rats with congestive heart failure. Chronic administration of eprosartan (5.0 mg/kg per day for 7 days through osmotic minipumps inserted intraperitoneally on the day of operation) resulted in a significant enhancement of urinary sodium excretion compared with nontreated rats with heart failure. Moreover, administration of eprosartan to salt-retaining rats with congestive heart failure resulted in a progressive increase and ultimate recovery in urinary sodium excretion. Finally, early treatment with eprosartan blocked the development of cardiac hypertrophy in rats with aortocaval fistula to a larger extent than the angiotensin-converting enzyme inhibitor enalapril. These findings emphasize the importance of angiotensin II in mediating the impairment in renal function and induction of cardiac hypertrophy in heart failure and further suggest that angiotensin II receptor blockade may be a useful treatment of these consequences in severe cardiac failure.
Hypertension 11/1998; 32(4):746-52. · 6.21 Impact Factor
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ABSTRACT: Focal cerebral ischemia elicits local inflammatory reaction as demonstrated by the accumulation of inflammatory cells and mediators in the ischemic brain. Interferon-inducible protein-10 (IP-10) is a member of the C-X-C chemokine family that possesses potent chemoattractant actions for monocytes, T cells, and smooth muscle cells. To investigate a potential role of IP-10 in focal stroke, we studied the temporal expression of IP-10 mRNA after occlusion of the middle cerebral artery in rat by means of northern analysis. IP-10 mRNA expression after focal stroke demonstrated a unique biphasic profile, with a marked increase early at 3 h (4.9-fold over control; p < 0.01), a peak level at 6 h (14.5-fold; p < 0.001) after occlusion of the middle cerebral artery, and a second wave induction 10-15 days after ischemic injury (7.2- and 9.3-fold increase for 10 and 15 days, respectively; p < 0.001). In situ hybridization confirmed the induced expression of IP-10 mRNA and revealed its spatial distribution after focal stroke. Immunohistochemical studies demonstrated the expression of IP-10 peptide in neurons (3-12 h) and astroglial cells (6 h to 15 days) of the ischemic zone. To explore further the potential role of IP-10 in focal stroke, we demonstrated a dose-dependent chemotactic action of IP-10 on C6 glial cells and enhanced attachment of rat cerebellar granule neurons. Taken together, the data suggest that ischemia induces IP-10, which may play a pleiotropic role in prolonged leukocyte recruitment, astrocyte migration/activation, and neuron attachment/sprouting after focal stroke.
Journal of Neurochemistry 10/1998; 71(3):1194-204. · 4.06 Impact Factor
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ABSTRACT: Microglia and astrocytes in the peri-infarct region are activated in response to focal stroke. A critical function of activated glia is formation of a protective barrier that ultimately forms a new glial-limiting membrane. Osteopontin, a provisional matrix protein expressed during wound healing, is induced after focal stroke. The present study was performed to determine the spatial and temporal expression of osteopontin and its integrin receptor alpha(v)beta3 during formation of the peri-infarct gliotic barrier and subsequent formation of a new glial-limiting membrane.
Spontaneously hypertensive rats (n = 19) were subjected to permanent occlusion of the middle cerebral artery and killed 3, 6, and 24 hours and 2, 5, and 15 days after occlusion. The spatial and temporal expression of osteopontin mRNA was determined by in situ hybridization, and that of osteopontin ligand and its integrin receptor alpha(v)beta3 was determined by immunohistochemistry.
Osteopontin mRNA was expressed de novo in the peri-infarct region from 3 to 48 hours; by 5 days osteopontin mRNA expression was restricted to the infarct. Osteopontin protein was expressed by peri-infarct microglia beginning at 24 hours and by microglia/macrophages at 48 hours in the infarct. Integrin receptor alpha(v)beta3 was expressed in peri-infarct astrocytes at 5 and 15 days.
Early microglial/macrophage expression of osteopontin mRNA defines the borders and final infarct area at 24 hours. At 5 days osteopontin ligand is at a distance from the peri-infarct astrocytes expressing integrin receptor alpha(v)beta3. By 15 days astrocytes expressing integrin receptor alpha(v)beta3 are localized in an osteopontin-rich region concomitant with formation of the new glial-limiting membrane. The de novo expression and interaction of osteopontin ligand with its receptor integrin alpha(v)beta3 suggest a role in wound healing after focal stroke.
Stroke 09/1998; 29(8):1698-706; discussion 1707. · 5.73 Impact Factor
