Home About us Contact
|
Home About us Contact | ||
|
|
||
Microvessel Endothelial Cells (microvessel + endothelial_cell)
Selected AbstractsExpression of the Multidrug Transporter P-glycoprotein in Brain Capillary Endothelial Cells and Brain Parenchyma of Amygdala-kindled RatsEPILEPSIA, Issue 7 2002Ulrike Seegers Summary: ,Purpose: Based on data from brain biopsy samples of patients with pharmacoresistant partial epilepsy, overexpression of the multidrug transporter P-glycoprotein (PGP) in brain capillary endothelium has recently been proposed as a potential mechanism of resistance to antiepileptic drugs (AEDs). We examined whether PGP is overexpressed in brain regions of amygdala-kindled rats, a widely used model of temporal lobe epilepsy (TLE), which is often resistant to AEDs. Methods: Rats were kindled by stimulation of the basolateral amygdala (BLA); electrode-implanted but nonkindled rats and naive (not implanted) rats served as controls. PGP was determined by immunohistochemistry either 1 or 2 weeks after the last kindled seizure, by using a monoclonal anti-PGP antibody. Six brain regions were examined ipsi- and contralateral to the BLA electrode: the BLA, the hippocampal formation, the piriform cortex, the substantia nigra, the frontal and parietal cortex, and the cerebellum. Results: In both kindled rats and controls, PGP staining was observed mainly in microvessel endothelial cells and, to a much lesser extent, in parenchymal cells. The distribution of PGP expression across brain regions was not homogeneous, but significant differences were found in both the endothelial and parenchymal expression of this protein. In kindled rats, ipsilateral PGP expression tended to be higher than contralateral expression in several brain regions, which was statistically significant in the piriform cortex and parietal cortex. However, compared with controls, no significant overexpression of PGP in capillary endothelial cells or brain parenchyma of kindled rats was seen in any ipsilateral brain region, including the BLA. For comparison with kindled rats, kainate-treated rats were used as positive controls. As reported previously, kainate-induced seizures significantly increased PGP expression in the hippocampus and other limbic brain regions. Conclusions: Amygdala-kindling does not induce any lasting overexpression of PGP in several brain regions previously involved in the kindling process. In view of the many pathophysiologic and pharmacologic similarities between the kindling model and TLE, these data may indicate that PGP overexpression in pharmacoresistant patients with TLE is a result of uncontrolled seizures but not of the processes underlying epilepsy. It remains to be determined whether transient PGP overexpression is present in kindled rats shortly after a seizure, and whether pharmacoresistant subgroups of kindled rats exhibit an increased expression of PGP. Furthermore, other multidrug transporters, such as multidrug resistance,associated protein, might be involved in the resistance of kindled rats to AEDs. [source] Homocysteine induces metalloproteinase and shedding of ,-1 integrin in microvessel endothelial cells,JOURNAL OF CELLULAR BIOCHEMISTRY, Issue 1 2004Suresh Shastry Abstract Although studies have suggested microvessel endothelial cells (MVEC) activation and induction of matrix metalloproteinases (MMPs) by homocysteine (Hcy), the transduction mechanism leading to endothelial activation was unclear. We hypothesized that Hcy induced metalloproteinase and altered the levels of integrin in MVEC. MVEC from mouse brain were isolated and characterized by CD-31 (PECAM-1) FITC labeling. The MVEC were activated with different doses (6,40 ,M) of Hcy. The cultured-conditioned-medium was analyzed for MMP activity by gelatin gel-zymography. TIMP-1, -4, ,-1 integrin, and a disintegrin and metalloproteinase-12 (ADAM-12) were quantified by Western blot analysis. We used MVEC in cell culture to study the effect of increasing concentrations of Hcy upon the secretion of various proteins into the culture medium. MMP-9, ,-1 integrin, ADAM-12, and TIMP-1 were found in increased concentrations in the culture medium of Hcy-treated cells whereas TIMP-4 was decreased. We have shown that purified TIMP-4 blocked the increase of ,-1 integrin shedding in Hcy-treated cells. Interestingly, our results suggest that TIMP-1 and TIMP-4 function antagonistically in Hcy-induced signaling pathways. © 2004 Wiley-Liss, Inc. [source] Intracerebral accumulation of glutaric and 3-hydroxyglutaric acids secondary to limited flux across the blood,brain barrier constitute a biochemical risk factor for neurodegeneration in glutaryl-CoA dehydrogenase deficiencyJOURNAL OF NEUROCHEMISTRY, Issue 3 2006Sven W. Sauer Abstract Glutaric acid (GA) and 3-hydroxyglutaric acids (3-OH-GA) are key metabolites in glutaryl co-enzyme A dehydrogenase (GCDH) deficiency and are both considered to be potential neurotoxins. As cerebral concentrations of GA and 3-OH-GA have not yet been studied systematically, we investigated the tissue-specific distribution of these organic acids and glutarylcarnitine in brain, liver, skeletal and heart muscle of Gcdh -deficient mice as well as in hepatic Gcdh,/, mice and in C57Bl/6 mice following intraperitoneal loading. Furthermore, we determined the flux of GA and 3-OH-GA across the blood,brain barrier (BBB) using porcine brain microvessel endothelial cells. Concentrations of GA, 3-OH-GA and glutarylcarnitine were significantly elevated in all tissues of Gcdh,/, mice. Strikingly, cerebral concentrations of GA and 3-OH-GA were unexpectedly high, reaching similar concentrations as those found in liver. In contrast, cerebral concentrations of these organic acids remained low in hepatic Gcdh,/, mice and after intraperitoneal injection of GA and 3-OH-GA. These results suggest limited flux of GA and 3-OH-GA across the BBB, which was supported in cultured porcine brain capillary endothelial cells. In conclusion, we propose that an intracerebral de novo synthesis and subsequent trapping of GA and 3-OH-GA should be considered as a biochemical risk factor for neurodegeneration in GCDH deficiency. [source] Cytoskeletal response of microvessel endothelial cells to an applied stress force at the submicrometer scale studied by atomic force microscopyMICROSCOPY RESEARCH AND TECHNIQUE, Issue 10 2006Wanyun Ma Abstract Cytoskeleton fibers form an intricate three-dimensional network to provide structure and function to microvessel endothelial cells. During accommodation to blood flowing, stress fiber bundles become more prominent and align with the direction of blood flow. This network either mechanically resists the applied shear stress (lateral force) or, if deformed, is dynamically remodeled back to a preferred architecture. However, the detailed response of these stress fiber bundles to applied lateral force at submicrometer scales are as yet poorly understood. In our in vitro study, the tip, topography probe in lateral force microscopy of atomic force microscopy, acted as a tool for exerting quantitative vertical and lateral force on the filaments of the cytoskeleton. Moreover, the authors developed a formula to calculate the value of lateral force exerted on every point of the filaments. The results show that cytoskeleton fibers of healthy tight junctions in rat cerebral microvessel endothelial cells formed a cross-type network, and were reinforced and elongated in the direction of scanning under lateral force of 15,42 nN. Under peroxidation (H2O2 of 300 ,mol/L), the cytoskeleton remodeled at intercellular junctions, and changed over the meshwork structures into a dense bundle, that redistributed the stress. Once mechanical forces were exerted on an area, the cells shrank and lost morphologic tight junctions. It would be useful in our understanding of certain pathological processes, such as cerebral ischemia/reperfusion injury, which maybe caused by biomechanical forces and which are overlooked in current disease models. Microsc. Res. Tech., 2006. © 2006 Wiley-Liss, Inc. [source] | |||||||||||||