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Capillary Endothelial Cells (capillary + endothelial_cell)
Kinds of Capillary Endothelial Cells 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] High transcytosis of melanotransferrin (P97) across the blood,brain barrierJOURNAL OF NEUROCHEMISTRY, Issue 4 2002Michel Demeule Abstract The blood,brain barrier (BBB) performs a neuroprotective function by tightly controlling access to the brain; consequently it also impedes access of proteins as well as pharmacological agents to cerebral tissues. We demonstrate here that recombinant human melanotransferrin (P97) is highly accumulated into the mouse brain following intravenous injection and in situ brain perfusion. Moreover, P97 transcytosis across bovine brain capillary endothelial cell (BBCEC) monolayers is at least 14-fold higher than that of holo-transferrin, with no apparent intra-endothelial degradation. This high transcytosis of P97 was not related to changes in the BBCEC monolayer integrity. In addition, the transendothelial transport of P97 was sensitive to temperature and was both concentration- and conformation-dependent, suggesting that the transport of P97 is due to receptor-mediated endocytosis. In spite of the high degree of sequence identity between P97 and transferrin, a different receptor than the one for transferrin is involved in P97 transendothelial transport. A member of the low-density lipoprotein receptor protein family, likely LRP, seems to be involved in P97 transendothelial transport. The brain accumulation, high rate of P97 transcytosis and its very low level in the blood suggest that P97 could be advantageously employed as a new delivery system to target drugs directly to the brain. [source] Symmetry-breaking in mammalian cell cohort migration during tissue pattern formation: Role of random-walk persistenceCYTOSKELETON, Issue 4 2005S. Huang Abstract Coordinated, cohort cell migration plays an important role in the morphogenesis of tissue patterns in metazoa. However, individual cells intrinsically move in a random walk-like fashion when studied in vitro. Hence, in the absence of an external orchestrating influence or template, the emergence of cohort cell migration must involve a symmetry-breaking event. To study this process, we used a novel experimental system in which multiple capillary endothelial cells exhibit spontaneous and robust cohort migration in the absence of chemical gradients when cultured on micrometer-scale extracellular matrix islands fabricated using microcontact printing. A computational model suggested that directional persistence of random-walk and dynamic mechanical coupling of adjacent cells are the critical control parameters for this symmetry-breaking behavior that is induced in spatially-constrained cell ensembles. The model predicted our finding that fibroblasts, which exhibit a much shorter motility persistence time than endothelial cells, failed to undergo symmetry breaking or produce cohort migration on the matrix islands. These findings suggest that cells have intrinsic motility characteristics that are tuned to match their role in tissue patterning. Our results underscore the importance of studying cell motility in the context of cell populations, and the need to address emergent features in multicellular organisms that arise not only from cell-cell and cell-matrix interactions, but also from properties that are intrinsic to individual cells. Cell Motil. Cytoskeleton 61:201,213, 2005. © 2005 Wiley-Liss, Inc. [source] Upregulation of Brain Expression of P-Glycoprotein in MRP2-deficient TR - Rats Resembles Seizure-induced Up-regulation of This Drug Efflux Transporter in Normal RatsEPILEPSIA, Issue 4 2007Katrin Hoffmann Summary:,Purpose: The multidrug resistance protein 2 (MRP2) is a drug efflux transporter that is expressed predominantly at the apical domain of hepatocytes but seems also to be expressed at the apical membrane of brain capillary endothelial cells that form the blood,brain barrier (BBB). MRP2 is absent in the transport-deficient (TR,) Wistar rat mutant, so that this rat strain was very helpful in defining substrates of MRP2 by comparing tissue concentrations or functional activities of compounds in MRP2-deficient rats with those in transport-competent Wistar rats. By using this strategy to study the involvement of MRP2 in brain access of antiepileptic drugs (AEDs), we recently reported that phenytoin is a substrate for MRP2 in the BBB. However, one drawback of such studies in genetically deficient rats is the fact that compensatory changes with upregulation of other transporters can occur. This prompted us to study the brain expression of P-glycoprotein (Pgp), a major drug efflux transporter in many tissues, including the BBB, in TR, rats compared with nonmutant (wild-type) Wistar rats. Methods: The expression of MRP2 and Pgp in brain and liver sections of TR, rats and normal Wistar rats was determined with immunohistochemistry, by using a novel, highly selective monoclonal MRP2 antibody and the monoclonal Pgp antibody C219, respectively. Results: Immunofluorescence staining with the MRP2 antibody was found to label a high number of microvessels throughout the brain in normal Wistar rats, whereas such labeling was absent in TR, rats. TR, rats exhibited a significant up-regulation of Pgp in brain capillary endothelial cells compared with wild-type controls. No such obvious upregulation of Pgp was observed in liver sections. A comparable overexpression of Pgp in the BBB was obtained after pilocarpine-induced seizures in wild-type Wistar rats. Experiments with systemic administration of the Pgp substrate phenobarbital and the selective Pgp inhibitor tariquidar in TR, rats substantiated that Pgp is functional and compensates for the lack of MRP2 in the BBB. Conclusions: The data on TR, rats indicate that Pgp plays an important role in the compensation of MRP2 deficiency in the BBB. Because such a compensatory mechanism most likely occurs to reduce injury to the brain from cytotoxic compounds, the present data substantiate the concept that MRP2 performs a protective role in the BBB. Furthermore, our data suggest that TR, rats are an interesting tool to study consequences of overexpression of Pgp in the BBB on access of drugs in the brain, without the need of inducing seizures or other Pgp-enhancing events for this purpose. [source] Expression 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] Induction of blood-brain barrier properties in cultured brain capillary endothelial cells: Comparison between primary glial cells and C6 cell lineGLIA, Issue 3 2005Monica Boveri Abstract The communication between glial cells and brain capillary endothelial cells is crucial for a well-differentiated blood-brain barrier (BBB). It has been suggested that in vitro primary glial cells (GCs) be replaced by the glial C6 cell line to standardise the model further. This study compares directly the structural and functional differentiation of bovine brain capillary endothelial cells (BBCECs) induced by co-culture with rat primary GCs or C6 cells, for the first time. Trans-endothelial electrical resistance (TEER) measurements showed that under no condition were C6 cells able to reproduce TEER values as high as in the presence of GCs. At the same time, permeability of the BBCECs to both radioactive sucrose and FITC-inulin was 2.5-fold higher when cells were co-cultured with C6 than with GCs. Furthermore, immunocytochemistry studies showed different cell morphology and less developed tight junction pattern of BBCECs co-cultured with C6 toward GCs. Additionally, studies on P-glycoprotein (P-gp) showed much lower P-gp presence and activity in BBCECs co-cultured with C6 than GCs. Both VEGF mRNA expression and protein content were dramatically increased when compared with GCs, suggesting that VEGF could be one of the factors responsible for higher permeability of BBB. Our results clearly indicate that, in the presence of the glial C6 cell line, BBCECs did not differentiate as well as in the co-culture with primary GCs at both structural and functional levels. © 2005 Wiley-Liss, Inc. [source] The Complementary Membranes Forming the Blood-Brain BarrierIUBMB LIFE, Issue 3 2002Richard A. Hawkins Abstract Brain capillary endothelial cells form the blood-brain barrier. They are connected by extensive tight junctions, and are polarized into luminal (blood-facing) and abluminal (brain-facing) plasma membrane domains. The polar distribution of transport proteins allows for active regulation of brain extracellular fluid. Experiments on isolated membrane vesicles from capillary endothelial cells of bovine brain demonstrated the polar arrangement of amino acid and glucose transporters, and the utility of such arrangements have been proposed. For instance, passive carriers for glutamine and glutamate have been found only in the luminal membrane of blood-brain barrier cells, while Na-dependent secondary active transporters are at the abluminal membrane. This organization could promote the net removal of nitrogen-rich amino acids from brain, and account for the low level of glutamate penetration into the central nervous system. Furthermore, the presence of a ,-glutamyl cycle at the luminal membrane and Na-dependent amino acid transporters at the abluminal membrane may serve to modulate movement of amino acids from blood-to-brain. Passive carriers facilitate amino acid transport into brain. However, activation of the ,-glutamyl cycle by increased plasma amino acids is expected to generate oxoproline within the blood-brain barrier. Oxoproline stimulates secondary active amino acid transporters (Systems A and B o,+ ) at the abluminal membrane, thereby reducing net influx of amino acids to brain. Finally, passive glucose transporters are present in both the luminal and abluminal membranes of the blood-brain barrier. Interestingly, a high affinity Na-dependent glucose carrier has been described only in the abluminal membrane. This raises the question whether glucose entry may be regulated to some extent. Immunoblotting studies suggest more than one type of passive glucose transporter exist in the blood-brain barrier, each with an asymmetrical distribution. In conclusion, it is now clear that the blood-brain barrier participates in the active regulation of brain extracellular fluid, and that the diverse functions of each plasma membrane domain contributes to these regulatory functions. [source] On the vascularization and structure of the skin of a Korean bullhead Pseudobagrus brevicorpus (Bagridae, Teleostei) based on its entire body and appendagesJOURNAL OF APPLIED ICHTHYOLOGY, Issue 1 2010J. Y. Park Summary To investigate the vascularization and structure of the skin and its relationship to cutaneous respiration in Pseudobagrus brevicorpus, a histological study by light microscopy was carried out on 15 regions of the skin, including eight body regions, six fins and the barbel. The skin consisted of the epidermis, dermis and subcutis in all regions, except for the barbel that had a relatively thin dermis and subcutis. The epidermis was composed of the outermost layer, the middle layer and the stratum germinativum. There were two kinds of gland cells: the unicellular mucus cells and large club cells. The middle layer had a small number of fine blood capillaries accompanied by dermal collagen in all regions; the mean number of blood capillaries ranged from 0.9 to 5.9. The mean diffusion distance between the capillary endothelial cells and the surface of the epidermis ranged from 50.6 to 126.8 ,m. Based on these intra-epithelial blood capillaries, the relative surface area of the respiratory epithelium ranged from 0.1 to a maximum value of 1.2%. The dermis lacking scales had collagen bundles arranged parallel to each other, but vertical fiber bundles around the dorso-lateral regions were seen at intervals. Sensory organs such as taste buds, pit organs and lateral canals were found whereby the taste buds in particular were more abundant in the epidermis of the barbel. The vascularization of the skin may be closely related to an additional respiratory system used to deal with an extreme hypoxic condition during dry seasons. [source] Ex vivo organ culture of adipose tissue for in situ mobilization of adipose-derived stem cells and defining the stem cell nicheJOURNAL OF CELLULAR PHYSIOLOGY, Issue 3 2010Young-Il Yang In spite of the advances in the knowledge of adipose-derived stem cells (ASCs), in situ location of ASCs and the niche component of adipose tissue (AT) remain controversial due to the lack of an appropriate culture system. Here we describe a fibrin matrix-supported three-dimensional (3D) organ culture system for AT which sustains the ASC niche and allows for in situ mobilization and expansion of ASCs in vitro. AT fragments were completely encapsulated within the fibrin matrix and cultured under dynamic condition. The use of organ culture of AT resulted in a robust outgrowth and proliferation in the fibrin matrix. The outgrown cells were successfully recovered from fibrin by urokinase treatment. These outgrown cells fulfilled the criteria of mesenchymal stem cells, adherence to plastic, multilineage differentiation, and cell surface molecule expression. In vitro label retaining assay revealed that newly divided cells during the culture resided in interstitium between adipocytes and capillary endothelial cells. These interstitial stromal cells proliferated and outgrew into the fibrin matrix. Both in situ mobilized and outgrown cells expressed CD146 and ,-smooth muscle actin (SMA), but no endothelial cell markers (CD31 and CD34). The structural integrity and spatial approximation of CD31,/CD34,/CD146+/SMA+ interstitial stromal cells, adipocytes, and capillary endothelial cells were well preserved during in vitro culture. Our results suggest that ASCs are natively associated with the capillary wall and more specifically, belong to a subset of pericytes. Furthermore, organ culture of AT within a fibrin matrix-supported 3D environment can recapitulate the ASC niche in vitro. J. Cell. Physiol. 224: 807,816, 2010. © 2010 Wiley-Liss, Inc. [source] Thioredoxin interacting protein (TXNIP) induces inflammation through chromatin modification in retinal capillary endothelial cells under diabetic conditionsJOURNAL OF CELLULAR PHYSIOLOGY, Issue 1 2009Lorena Perrone Chronic hyperglycemia and activation of receptor for advanced glycation end products (RAGE) are known risk factors for microvascular disease development in diabetic retinopathy. Thioredoxin-interacting protein (TXNIP), an endogenous inhibitor of antioxidant thioredoxin (TRX), plays a causative role in diabetes and its vascular complications. Herein we investigate whether HG and RAGE induce inflammation in rat retinal endothelial cells (EC) under diabetic conditions in culture through TXNIP activation and whether epigenetic mechanisms play a role in inflammatory gene expression. We show that RAGE activation by its ligand S100B or HG treatment of retinal EC induces the expression of TXNIP and inflammatory genes such as Cox2, VEGF-A, and ICAM1. TXNIP silencing by siRNA impedes RAGE and HG effects while stable over-expression of a cDNA for human TXNIP in EC elevates inflammation. p38 MAPK-NF-,B signaling pathway and histone H3 lysine (K) nine modifications are involved in TXNIP-induced inflammation. Chromatin immunoprecipitation (ChIP) assays reveal that TXNIP over-expression in EC abolishes H3K9 tri-methylation, a marker for gene inactivation, and increases H3K9 acetylation, an indicator of gene induction, at proximal Cox2 promoter bearing the NF-,B-binding site. These findings have important implications toward understanding the molecular mechanisms of ocular inflammation and endothelial dysfunction in diabetic retinopathy. J. Cell. Physiol. 221: 262,272, 2009. © 2009 Wiley-Liss, Inc [source] Risk factors and mechanism of transplacental transmission of hepatitis B virus: A case-control studyJOURNAL OF MEDICAL VIROLOGY, Issue 1 2002De-Zhong Xu Abstract Intrauterine hepatitis B virus (HBV) infection has been suggested to be caused by transplacental transmission that cannot be blocked by hepatitis B vaccine. This would decrease the effectiveness of hepatitis B vaccine. This study examined the risk factors and mechanism of transplacental HBV transmission. A case-control study included 402 newborn infants from 402 HBsAg-positive pregnant women. Among these, 15 newborn infants infected with HBV by intrauterine transmission were selected as cases, and the rest as controls. A pathology study included 101 full-term placentas from the HBsAg-positive pregnant women above and 14 from HBsAg-negative pregnant women. Immunohistochemistry staining and HBV DNA in situ hybridization were used to estimate the association of intrauterine HBV infection and HBV infection in the placentas. HBeAg positivity in mothers' sera (OR,=,17.07, 95%CI 3.39,86.01) and threatened preterm labor (OR,=,5.44, 95%CI 1.15,25.67) were found to be associated with transplacental HBV transmission. The intrauterine infection rate increased linearly and significantly with maternal serum HBsAg titers (trend test P,=,0.0117) and HBV DNA concentration (trend test P,<,0.01). Results of the pathology study showed that HBV infection rates decreased gradually from the maternal side to the fetal side (trend test P,=,0.0009) in the placental cell layers. There was a significant association between intrauterine HBV transmission and HBV infection in villous capillary endothelial cells (VCEC) in the placenta (OR,=,18.46, P,=,0.0002). The main risk factors for intrauterine HBV infection are maternal serum HBeAg positivity, history of threatened preterm labor, and HBV in the placenta especially the villous capillary endothelial cells. Previous reports of transplacental leakage of maternal blood causing intrauterine infection are confirmed. In addition, there appears to be a "cellular transfer" of HBV from cell to cell in the placenta causing intrauterine infection. This latter hypothesis needs to be confirmed. J. Med. Virol. 67:20,26, 2002. © 2002 Wiley-Liss, Inc. [source] Localization of organic cation/carnitine transporter (OCTN2) in cells forming the blood,brain barrierJOURNAL OF NEUROCHEMISTRY, Issue 1 2008Dorota Miecz Abstract Carnitine ,-hydroxy-,-(trimethylammonio)butyrate , a compound necessary in the peripheral tissues for a transfer of fatty acids for their oxidation within the cell, accumulates in the brain despite low ,-oxidation in this organ. In order to enter the brain, carnitine has to cross the blood,brain barrier formed by capillary endothelial cells which are in close interaction with astrocytes. Previous studies, demonstrating expression of mRNA coding two carnitine transporters , organic cation/carnitine transporter 2 (OCTN2) and B0,+ in endothelial cells, did not give any information on carnitine transporters polarity in endothelium. Therefore more detailed experiments were performed on expression and localization of a high affinity carnitine transporter OCTN2 in an in vitro model of the blood,brain barrier by real-time PCR, western blot analysis, and immunocytochemistry. The amount of mRNA was comparable in endothelial cells and kidney, when referred to house-keeping genes, it was, however, significantly lower in astrocytes. Polarity of OCTN2 localization was further studied in an in vitro model of the blood,brain barrier with use of anti-OCTN2 antibodies. Z -axis analysis of the confocal microscope pictures of endothelial cells, with anti-P-glycoprotein antibodies as the marker of apical membrane, showed OCTN2 localization at the basolateral membrane and in the cytoplasmic region in the vicinity of nuclei. Localization of OCTN2 suggest that carnitine can be also transported from the brain, playing an important role in removal of certain acyl esters. [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] Scavenger receptor class B, type I is expressed in porcine brain capillary endothelial cells and contributes to selective uptake of HDL-associated vitamin EJOURNAL OF NEUROCHEMISTRY, Issue 2 2001Daniel Goti It is clearly established that an efficient supply to the brain of ,-tocopherol (,TocH), the most biologically active member of the vitamin E family, is of the utmost importance for proper neurological functioning. Although the mechanism of uptake of ,TocH into cells constituting the blood,brain barrier (BBB) is obscure, we previously demonstrated that high-density lipoprotein (HDL) plays a major role in the supply of ,TocH to porcine brain capillary endothelial cells (pBCECs). Here we studied whether a porcine analogue of human and rodent scavenger receptor class B, type I mediates selective (without concomitant lipoprotein particle internalization) uptake of HDL-associated ,TocH in a similar manner to that described for HDL-associated cholesteryl esters (CEs). In agreement with this hypothesis we observed that a major proportion of ,TocH uptake by pBCECs occurred by selective uptake, exceeding HDL3 holoparticle uptake by up to 13-fold. The observation that selective uptake of HDL-associated CE exceeded HDL3 holoparticle up to fourfold suggested that a porcine analogue of SR-BI (pSR-BI) may be involved in lipid uptake at the BBB. In line with the observation of selective lipid uptake, RT-PCR and northern and western blot analyses revealed the presence of pSR-BI in cells constituting the BBB. Adenovirus-mediated overexpression of the human analogue of SR-BI (hSR-BI) in pBCECs resulted in a fourfold increase in selective HDL-associated ,TocH uptake. In accordance with the proposed function of SR-BI, selective HDL,CE uptake was increased sixfold in Chinese hamster ovary cells stably transfected with murine SR-BI (mSR-BI). Most importantly stable mSR-BI overexpression mediated a twofold increase in HDL-associated [14C],TocH selective uptake in comparison with control cells. In line with tracer experiments, mass transfer studies with unlabelled lipoproteins revealed that mSR-BI overexpression resulted in a twofold increase in endogenous HDL3 -associated ,TocH uptake. The results of this study indicate that SR-BI promotes the uptake of HDL-associated ,TocH into cells constituting the BBB and plays an important role during the supply of the CNS with this indispensable micronutrient. [source] Therapeutic implications of the MDR-1 geneJOURNAL OF VETERINARY PHARMACOLOGY & THERAPEUTICS, Issue 5 2004K. L. Mealey Drug transporters significantly influence drug pharmacokinetics and pharmacodynamics. P-glycoprotein (P-gp), the product of the MDR1 (ABCB1) gene, is among the most well-characterized drug transporters, particularly in veterinary medicine. A number of clinically relevant, structurally and functionally unrelated drugs are substrates for P-gp. P-gp is expressed by a variety of normal tissues including the intestines, renal tubular cells, brain capillary endothelial cells, biliary canalicular cells, and others, where it functions to actively extrude substrate drugs. In this capacity, P-gp limits oral absorption and central nervous system entry of many substrate drugs. A number of MDR1 polymorphisms have been described in human patients, some of which result in altered drug pharmacokinetics and susceptibility to diseases such as Parkinson's disease, inflammatory bowel disease, refractory seizures, and others. An MDR1 polymorphism in herding breed dogs, including collies and Australian shepherds, has been demonstrated to be the cause of ivermectin sensitivity in these breeds. Recent evidence suggests that this polymorphism, a 4-bp deletion mutation, results in increased susceptibility to the toxicity of several drugs in addition to ivermectin. Furthermore, data in rodent models suggest that P-gp may play an important role in regulating the hypothalamic,pituitary,adrenal axis. [source] Leukocyte Adhesion in Capillary-Sized, P-Selectin-Coated MicropipettesMICROCIRCULATION, Issue 2 2008Prithu Sundd ABSTRACT Objective: Leukocyte retention in lung capillaries is observed in normal physiology and following a bacterial infection. It has been hypothesized that cells either become mechanically trapped or adhere to capillary endothelial cells via adhesion molecules. We propose that retention involves both mechanical and adhesive forces and that the biochemical adhesive force is modulated by mechanical forces that alter the area of contact between leukocytes and endothelium. Methods: To probe this hypothesis, an adhesion assay has been developed in which individual HL-60 cells were aspirated into micropipettes pre-coated with P-selectin. Following aspiration, cells were exposed to physiological pressure differences. Results: Little adhesion was seen in micropipettes coated with BSA, whereas significant adhesion was observed in micropipettes coated with P-selectin. The frequency of cell arrest on P-selectin in the micropipette was much greater than on P-selectin in a parallel plate flow chamber even though the disruptive force in the micropipette assay exceeds that in the parallel plate flow chamber. These results demonstrate that receptor,ligand interactions can enhance adhesion in a capillary geometry and that differences in capillary geometry vs. venule geometry can significantly influence the adhesive phenotype. Conclusions: Taken together, these observations support the hypothesis that an interplay between mechanical and biochemical adhesive forces can play a major role in retention. [source] Role of adrenocorticotropic hormone in the development and maintenance of the adrenal cortical vasculatureMICROSCOPY RESEARCH AND TECHNIQUE, Issue 3 2003Michaël Thomas Abstract The adrenal cortex is a highly vascularized endocrine tissue. A dense network of blood capillaries centripetally irrigates the adrenal gland, allowing every endocrine cell to be in contact with an endothelial cell. The pituitary hormone ACTH controls the coordinated development of the vasculature and the endocrine tissue mass. This suggests that paracrine secretions between steroidogenic adrenocytes and capillary endothelial cells participate in the control of adrenocortical homeostasis. Besides its effect on the vascular tone of arteries, ACTH induces the expression of the angiogenic cytokine VEGF-A (vascular endothelial growth factor-A) in primary cultures of adrenocortical cells. This growth factor is a specific mitogen for endothelial cells and is likely to mediate the hormonal control of adrenocortical vascularization through a paracrine mechanism. The newly discovered angiogenic factor EG-VEGF (endocrine-gland-derived vascular endothelial growth factor), the expression of which is restricted to endocrine glands and which is preferentially mitogenic for endocrine tissue-derived endothelial cells, is another candidate mediator of great potential interest. Microsc. Res. Tech. 61:247,251, 2003. © 2003 Wiley-Liss, Inc. [source] Organ-specific endoglin (CD105) expression in the angiogenesis of human cancersPATHOLOGY INTERNATIONAL, Issue 12 2006Rahmawati Minhajat Some markers of angiogenic endothelial cells are emerging as targets for cancer therapy. The present study compared the expression of CD105 with that of other endothelial markers in cancers from various organs. Surgically resected cancer tissues from 188 patients comprising brain (n = 17), lung (n = 38), breast (n = 30), stomach (n = 30), colon (n = 31), liver (n = 32), and kidney (n = 10) cancers were immunohistochemically analyzed on tissue microarrays using a panel of eight endothelial markers. CD31 was expressed in vascular endothelial cells in cancer lesions as well as in non-cancerous areas (30,100%) in all core tissue samples. CD105 expression was intense and restricted to capillary endothelial cells in cancer lesions (>73%). In contrast, positive expression of CD105 was seen in <20% of non-cancerous areas in the same organs. However, no significant difference in CD105 expression in vascular endothelial cells between cancer lesions and non-cancerous areas from liver and renal cancer samples was found. Vascular endothelial growth factor (VEGF), Flt1, and Flk1 were also expressed, but only sporadically and in few samples (<30%), and transforming growth factor (TGF)-,1 and TGF-,RII were negative in vascular endothelial cells but generally positive in cancer cells. CD44 was strongly expressed in sinusoidal endothelial cells of the liver (90,100%). These results show that CD105 is expressed specifically in the tumor angiogenesis of brain, lung, breast, stomach, and colon cancers. [source] 2125: High glucose sensitizes human retinal endothelial cells for IFN-g-mediated apoptosisACTA OPHTHALMOLOGICA, Issue 2010R NAGARAJ Purpose The biochemical mechanisms by which inflammatory cytokines cause damage in the diabetic retina are poorly understood. Indoelamine 2, 3-dioxygenase (IDO) is an inducible by IFN-, enzyme and is the first enzyme of the kynurenine pathway, which produces cytotoxic kynurenines. In this study we have investigated the role of IDO in apoptosis of human retinal capillary endothelial cells (HREC) under hyperglycemic conditions. Methods HREC were cultured in medium containing high glucose (25 mM) or low glucose (7.5 mM) and incubated with 1-100 U/ml of IFN-,. IDO activity was measured by an HPLC assay. Expression of IFN-, receptor 1, and activation of the JAK-STAT signaling pathway along with activation of PKC-, was assessed by Western blotting. HREC apoptosis was measured by Hoechst staining. The role of IDO in HREC apoptosis was evaluated in the presence specific chemical inhibitors of the kynurenine pathway. Results IFN-, dose-dependently activated JAK-STAT signaling and PKC-,, and upregulated IDO. The IDO-mediated tryptophan oxidation led to formation of kynurenines, which was followed by chemical modification of proteins by kynurenines in HREC. These changes were accompanied by production of reactive oxygen species (ROS) and depletion of protein-free thiols. IFN-, inhibited cell cycle at low concentrations and caused caspase-3-mediated apoptosis and at higher concentrations, and those effects were amplified in the presence of high glucose in HREC. We found that IFN-, mediated cytotoxicity in HREC was primarily due to ROS generated by 3-hydroxykynurenine. Conclusion Our results suggest that high glucose sensitizes HREC to deleterious effects IFN-, and provide a novel mechanistic pathway for retinal capillary endothelial cell death in diabetes. [source] | |||||||||||||||||||||||||