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Matrix metalloproteinases (MMPs) such as MMP-9, 3, and 2 degrade the cellular matrix and are believed to play a crucial role in ischemic stroke. We examined how the duration of ischemia (up to 4 h) and treatment with recombinant tissue plasminogen activator altered the comparative expression of these MMPs in experimental ischemic stroke with reperfusion. Both prolonged ischemia and r-tPA treatment markedly increased MMP-9 expression in the ischemic hemisphere (all p < 0.0001). The duration of ischemia and r-tPA treatment also significantly increased MMP-2 expression (p < 0.01–0.001) in the ischemic hemisphere (p < 0.01) but to a lesser degree than MMP-9. In contrast, MMP-3 expression significantly decreased in the ischemic hemisphere (p < 0.001) with increasing duration of ischemia and r-tPA treatment (p < 0.05–0001). MMP-9 expression was prominent in the vascular compartment and leukocytes. MMP-2 expression was evident in the vascular compartment and MMP-3 in NeuN+ neurons. Prolonging the duration of ischemia (up to 4 h) before reperfusion increased brain hemorrhage, infarction, swelling, and neurologic disability in both saline-treated (control) and r-tPA-treated mice. MMP-9 and MMP-2 expression were significantly positively correlated with, and MMP-3 was significantly negatively correlated with, infarct volume, swelling, and brain hemorrhage. We conclude that in experimental ischemic stroke with reperfusion, the duration of ischemia and r-tPA treatment significantly altered MMP-9, 3, and 2 expression, ischemic brain injury, and neurological disability. Each MMP showed unique patterns of expression that are strongly correlated with the severity of brain infarction, swelling, and hemorrhage. In summary, in experimental ischemic stroke in male mice with reperfusion, the duration of ischemia, and r-tPA treatment significantly altered the immunofluorescent expression of MMP-9, 3, and 2, ischemic brain injury, and neurological disability. In this model, each MMP showed unique patterns of expression that were strongly correlated with the severity of brain infarction, swelling, and hemorrhage. [ABSTRACT FROM AUTHOR]

Acute coronary artery occlusion triggers the release of atrial natriuretic peptide (ANP) from the heart. ANP affects vasodilation, natriuresis, and inflammation, but the integrated biological effects of ANP on myocardial infarction are unknown. To elucidate these effects, the left anterior coronary artery was ligated in anesthetized, ANP-deficient ([ANP.sup.-/-]) and congenic wild-type ([ANP.sup.+/+]) mice. The survival of [ANP.sup.-/-] mice was markedly better (56%) at 30 days postinfarction than the survival of [ANP.sup.+/+] mice (20%, P < 0.01). Surviving mice were comparable initially, but [ANP.sup.-/-] mice developed more cardiac hypertrophy (P < 0.001) and had lower contractility indexes 30 days after infarction (P < 0.05). An analysis 24 h after coronary occlusion showed that [ANP.sup.-/-] mice had smaller infarcts than [ANP.sup.+/+] mice (62.6 [+ or -] 12.1 vs. 100.8 [+ or -] 3.8%, P < 0.001) adjusted for comparable areas at risk for ischemia. The administration of ANP to [ANP.sup.-/-] mice via osmotic minipumps significantly enlarged infarct size to levels comparable with those observed in [ANP.sup.+/+] mice (P < 0.05). There was no difference in neutrophil migration into the noninfarcted myocardium of [ANP.sup.-/-] mice undergoing actual versus sham-operated coronary occlusion. By comparison, after coronary occlusion, the neutrophil infiltration into the myocardium was enhanced in [ANP.sup.+/+] (P < 0.0005) and [ANP.sup.-/-] mice administered ANP (P < 0.0005). The expression of P-selectin, a molecule that mediates neutrophil adhesion, was significantly greater after coronary occlusion in the vasculature of [ANP.sup.+/+] or [ANP.sup.-/-] mice treated with ANP than in [ANP.sup.-/-] mice (P < 0.002). Taken together, these results indicate that ANP increases P-selectin, neutrophil infiltration, infarct size, and mortality following experimental coronary occlusion. myocardial infarction; neutrophil; P-selectin

Signaling through cAMP plays an important role in heart failure. Phosphorylation of cAMP response element binding protein (CREB) at serine-133 regulates gene expression in the heart. We examined the functional significance of CREBS133 phosphorylation by comparing transgenic models in which a phosphorylation resistant CREB-S 133A mutant containing either an intact or a mutated leucine zipper domain (CREB-S 133A-LZ) was expressed in the heart. In vitro, CREB-S133A retained the ability to interact with wild-type CREB, whereas CREB-S133A-LZ did not. In vivo, CREB-S133A and CREB-S133A-LZ were expressed at comparable levels in the heart; however, CREB-S133A markedly suppressed the phosphorylation of endogenous CREB, whereas CREB-S 133A-LZ had no effect. The one-year survival of mice from two CREB-S133A-LZ transgenic lines was equivalent to nontransgenic littermate control mice (NTG), whereas transgenic CREBS133A mice died with heart failure at a median 30 wk of age (P < 0.0001). CREB-S133A mice had an altered gene expression characteristic of the failing heart, whereas CREB-S 133A-LZ mice did not. Left ventricular contractile function was substantially reduced in CREB-S133A mice versus NTG mice and only modestly reduced in CREB-S 133A-LZ mice (P < 0.02). When considered in light of other studies, these findings indicate that overexpression of the CREB leucine zipper is required for both inhibition of endogenous CREB phosphorylation and cardiomyopathy in this routine model of heart failure. adenosine 3',5'-cyclic monophosphate responsive element binding protein

The study observation shows that explosive generation of plasmin in blood or plasma which diminishes streptokinase's therapeutic effects is attributated to the formation of SK-Pg* that is governed by kringle domains.

Author(s): George L. Dale (corresponding author) [1]; Paul Friese [1]; Peter Batar [1]; Stephen F. Hamilton [2]; Guy L. Reed [3]; Kenneth W. Jackson [1]; Kenneth J. Clemetson [4]; Lorenzo [...]

Research has been conducted on the plasminogen that regulates fibrinolysis process. Conformational changes in plasminogen induced by lysine side chains have been explored.

A study on the fibrinolytic pathway and plasminogen activators involved in this pathway was conducted to test the molecular sexuality hypothesis by deleting Ile1 from streptokinase. This mutation abolishes the activation of plasminogen by streptokinase under certain conditions. The study demonstrates the significance of the N-terminus of streptokinase in plasminogen activation and provides compelling data for the molecular sexuality hypothesis.

Ten different lysine residues in the plasminogen binding region of streptokinase (SK) were modified to produce 8 recombinant (r) SK mutants to evaluate the hypothesis that SK is involved in the binding and function of the activator complex. Results identified lysine residues in a plasminogen binding region of SK which appear to be essential for normal high-affinity binding to plasminogen and for the efficient catalytic processing of substrate plasminogen molecules by the activator complex.

Streptokinase (SK), a plasminogen activator used to treat patients with myocardial infarction binds to plasminogen with high affinity, and the primary binding region for plasminogen is located within amino acids 244-352. The binding via this region is necessary for the generation of a functional activator complex. Recombinant SK fragments attached to amino acids 1-127 and 1-253 does not bind to Glu-plasminogen, whereas fragments attached to 1-352, 120-352 and 244-414 binds tightly to plasminogen and each fragment inhibits the binding of full-length SK to plasminogen.