Dynamic Contrast-Enhanced Perfusion MR Imaging Measurements of Endothelial Permeability: Differentiation between Atypical and Typical Meningiomas

BACKGROUND: AND PURPOSE: The measurement of relative cerebral blood volume (rCBV) and the volume transfer constant (K(trans)) by means of dynamic contrast-enhanced (DCE) perfusion MR imaging (pMRI) can be useful in characterizing brain tumors. The purpose of our study was to evaluate the utility of these measurements in differentiating typical meningiomas and atypical meningiomas. METHODS: Fifteen patients with pathologically confirmed typical meningiomas and seven with atypical meningiomas underwent conventional imaging and DCE pMRI before resection.rCBV measurements were calculated by using standard intravascular

Changes in the permeability of blood brain barrier and endothelial cell damage after cerebral ischemia

OBJECTIVE： To investigate the effect of endothelial cells on the permeability of blood brain barrier （BBB） after brain injury and its effect mechanism. DATA SOURCES： We searched for the articles of permeability of BBB and endothelial cell injury after brain is- chemia, which were published between January 1982 and December 2005, with the key words of ＂cerebral ischemia damage,blood brain barrier （ BBB）,permeability,effect of endothelial cell （EC） and its variation mechanism＂in English. STUDY SELECTION： The materials were primarily selected. The articles related to the changes in the permeability of BBB and the effect of endothelial cells as well as the change mechanism after cerebral ischemia damage were chosen. Repetitive studies or review articles were excluded. DATA EXTRACTION： Totally 55 related articles were collected, and 35 were excluded due to repetitive or review articles, finally 20 articles were involved. DATA SYNTHESIS： The content or viewpoints of involved literatures were analyzed. Cerebral ischemia had damage for endothelial cells, such as the inflow of a lot of Ca2^＋, the production of nitrogen monoxide and oxygen free radical, and aggravated destruction of BBB. After acceptors of inflammatory mediators on cerebrovascular endothelial cell membrane, such as histamine, bradykinin , 5-hydroxytryptamine and so on are activated, endothelial cells shrink and the permeability of BBB increases. Its mechanism involves in the inflow of extracellular Ca^＋2and the release of intracellular Ca^2＋ in the cells. Glycocalyx molecule on the surface of endothelial cell, having structural polytropy, is the determinative factor of the permeability of BBB. VEGF, intensively increasing the vasopermeability and mainly effecting on postcapillary vein and veinlet, is the strongest known blood vessel permeation reagent. Its chronic overexpression in the brain can lead the destruction of BBB. CONCLUSION： The injury of endothelial cell participants in the pathological mechanism of BBB destruction after cerebral ischemla.

TNF-a induce the F-actin arrangement and permeability increase in endothelial cells by RhoA-ERK1/2 pathway

Background This study aimed to determine the effects of tumor necrosis factor(TNF-a) on endothelial cytoskeleton morphology and permeability,and to detect the underlying signaling mechanisms involved in these responses. Methods Cultured endothelial cells(ECs) were exposed to TNF-a,and EC cytoskeletal changes were evaluated by observing fluorescence of F-actin following ligation with labeled antibodies.Endothelial permeability was detected by measuring the flux of HRP-albumin across the EC monolayers.To explore the signaling pathways behind TNF-a-induced EC alteration, ECs were treated with either the RhoGTPase inhibitor Y27632 or the MAPK inhibitors PD98059 and SB203580 before TNF-a administration.To further elucidate possible involvement of the RhoA and ERK pathways in TNF-induced EC changes,retrovirus-carried recombinant dominant-negative forms and constitutive-activative forms of RhoA,namely T19NRhoA and Q63LRhoA,were pre-infect-ed into ECs prior to TNF-a exposure.Results TNF-a induced F-actin cytoskeleton rearrangement,as well as EC hyperpermeability in a dose and time-dependent manner.The effects were attenuated in cells pretreated with Y27632 or PD98059,respectively.EC pre-infection with T19NRhoA also alleviated the effects of TNF-a.Furthermore,retrovirus-mediated administration of activated forms of Q63LRhoA alone induced rearrangement of F-actin and hyperpermeability as well as induced the activation of pERK.Conclusions These results indicate that RhoA-ERK/MAPK signal pathway play important roles in the mediation of TNF-a induced EC barrier dysfunction associated with morphological changes of the Factin.

Agmatine induces gastric protection against ischemic injury by reducing vascular permeability in rats

AIM:To investigate the effect of administration of agmatine(AGM) on gastric protection against ischemia reperfusion(I/R) injury.METHODS:Three groups of rats(6/group);sham,gastric I/R injury,and gastric I/R + AGM(100 mg/kg,i.p.given 15 min prior to gastric ischemia) were recruited.Gastric injury was conducted by ligating celiac artery for 30 min and reperfusion for another 30 min.Gastric tissues were histologically studied and immunostained with angiopoietin 1(Ang-1) and Ang-2.Vascular endothelial growth factor(VEGF) and monocyte chemoattractant protein-1(MCP-1) were measured in gastric tissue homogenate.To assess whether AKt/phosphatidyl inositol-3-kinase(PI3K) mediated the effect of AGM,an additional group was pretreated with Wortmannin(WM)(inhibitor of Akt/PI3K,15 μg/kg,i.p.),prior to ischemic injury and AGM treatment,and examined histologically and immunostained.Another set of experiments was run to study vascular permeability of the stomach using Evan's blue dye.RESULTS:AGM markedly reduced Evan's blue dye extravasation(3.58 ± 0.975 μg/stomach vs 1.175 ± 0.374 μg/stomach,P < 0.05),VEGF(36.87 ± 2.71 pg/100 mg protein vs 48.4 ± 6.53 pg/100 mg protein,P < 0.05) and MCP-1 tissue level(29.5 ± 7 pg/100 mg protein vs 41.17 ± 10.4 pg/100 mg protein,P < 0.01).It preserved gastric histology and reduced congestion.Ang-1 and Ang-2 immunostaining were reduced in stomach sections of AGM-treated animals.The administration of WM abolished the protective effects of AGM and extensive hemorrhage and ulcerations were seen.CONCLUSION:AGM protects the stomach against I/R injury by reducing vascular permeability and inflammation.This protection is possibly mediated by Akt/PI3K.

Low-power Helium-Neon laser irradiation enhances the expression of VEGF in murine myocardium

Background Low-power helium-neon (He-Ne) lasers have been increasingly widely applied in the treatment of cardiovascular diseases, and its vasodilation effect has been proven. The aim of this study was to determine the effects of low-power He-Ne laser irradiation directed at the precardial region of Wistar rats on capillary permeability in the myocardium and the expression of myocardial vascular endothelial growth factor (VEGF). Methods Sixteen rats were divided randomly into control and irradiated groups (n=8, each). A He-Ne laser (632.8 nm) was applied to the irradiated group with a dose of 60.5 J/cm2. Ferritin was perfused into the left femoral vein and capillary permeability was examined under an electron microscope. VEGF expression in the myocardium was investigated by immunohistochemical methods, RT-PCR, and image analysis. Results The ultrastructures of the myocardial capillaries were examined. Compared to the control group, more high-density granules (ferritin), which were present within the capillary endothelium and the mitochondrions of myocardial cells in the internal layer of the myocardium, were observed in the irradiated group. VEGF staining of the myocardium was stronger in the irradiated group than that in the control group. The optic density of the irradiated group (0.246±0.015) was significantly higher than that of the control group (0.218±0.012, P<0.05). Finally, the levels of RT-PCR products of VEGF165 mRNA were 2.79 times higher in irradiated rats than in the control rats.Conclusions Our study demonstrates that He-Ne laser irradiation (in doses of 60.5 J/cm2) increases myocardial capillary permeability and the production of VEGF in myocardial microvessels and in myocardium. Our study provides experimental morphological evidence that myocardial microcirculation can be improved using He-Ne laser irradiation.