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Query: UMLS:C0022116 (ischemia)
 91,303 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Increased vascular permeability is an early event characteristic of tissue ischemia and angiogenesis. Although VEGF family members are potent promoters of endothelial permeability the role of placental growth factor (PlGF) is hotly debated. Here we investigated PlGF isoforms 1 and 2 and present in vitro and in vivo evidence that PlGF-1, but not PlGF-2, can inhibit VEGF-induced permeability but only during a critical window post-VEGF exposure. PlGF-1 promotes VE-cadherin expression via the trans-activating Sp1 and Sp3 interaction with the VE-cadherin promoter and subsequently stabilizes transendothelial junctions, but only after activation of endothelial cells by VEGF. PlGF-1 regulates vascular permeability associated with the rapid localization of VE-cadherin to the plasma membrane and dephosphorylation of tyrosine residues that precedes changes observed in claudin 5 tyrosine phosphorylation and membrane localization. The critical window during which PlGF-1 exerts its effect on VEGF-induced permeability highlights the importance of the translational significance of this work in that PLGF-1 likely serves as an endogenous anti-permeability factor whose effectiveness is limited to a precise time point following vascular injury. Clinical approaches that would pattern nature's approach would thus limit treatments to precise intervals following injury and bring attention to use of agents only during therapeutic windows.
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PMID:Placenta growth factor-1 exerts time-dependent stabilization of adherens junctions following VEGF-induced vascular permeability. 3065 Jan 41

Great uncertainty exists as to whether aging enhances the detrimental effects of tissue plasminogen activator (tPA) on vascular integrity of the ischemic brain. We hypothesized that tPA treatment would augment ischemic injury by causing increased blood-brain barrier (BBB) breakdown as determined by quantitative serial T(1) and T(2) magnetic resonance imaging (MRI), and the transfer constant for gadolinium-diethylenetriamine penta-acetic acid (Gd-DTPA) from blood to brain in aged (18 to 20 months) compared with young (3 to 4 months) Wistar rats after middle cerebral artery occlusion, mediated through the acute disassembly of claudin 5 and occludin. Increased T(2) values over the first hour of postreperfusion were independently augmented following treatment with tPA (P<0.001) and aging (P<0.01), supporting a synergistic effect of tPA on the aged ischemic brain. Blood-brain barrier permeability for Gd-DTPA (K(Gd)) was substantial following reperfusion in all animal groups and was exacerbated by tPA treatment in the elderly rat (P<0.001). The frequency of hematoma formation was proportionately increased in the elderly ischemic brain (P<0.05). Both tPA and age independently increased claudin 5 and occludin phosphorylation during ischemia. Early BBB permeability detected by quantitative MRI following ischemic stroke is enhanced by increased age and tPA and is related to claudin 5 and occludin phosphorylation.
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PMID:Quantitative MRI reveals the elderly ischemic brain is susceptible to increased early blood-brain barrier permeability following tissue plasminogen activator related to claudin 5 and occludin disassembly. 2161 Jul 23

Glucocorticoid stress hormones (GCs) are well known for being anti-inflammatory, but some reports suggest that GCs can also augment aspects of inflammation during acute brain injury. Because the GC receptor (GR) is ubiquitously expressed throughout the brain, it is difficult to know which cell types might mediate these unusual "proinflammatory" GC actions. We examined this with cell type-specific deletion or overexpression of GR in mice experiencing seizure or ischemia. Counter to their classical anti-inflammatory actions, GR signaling in myeloid cells increased Iba-1 and CD68 staining as well as nuclear p65 levels in the injured tissue. GCs also reduced levels of occludin, claudin 5, and caveolin 1, proteins central to blood-brain-barrier integrity; these effects required GR in endothelial cells. Finally, GCs compromised neuron survival, an effect mediated by GR in myeloid and endothelial cells to a greater extent than by neuronal GR.
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PMID:Glucocorticoid signaling in myeloid cells worsens acute CNS injury and inflammation. 2363 79