摘要:

50% faster than control cells. Furthermore, this growth advantage became more evident in the absence of serum growth factors, with an average increase in cell number of 118% over control cells after 6 days. Consistent with these in vitro data, we observed intense immunostaining for TSG-6 in proliferating SMCs in the rat neointima after injury, whereas only an occasional cell was positive for TSG-6 in the medial layer and in nonballooned arteries. We conclude that the expression of TSG-6 is tightly controlled by growth factors and cytokines via two distinct pathways in SMCs and that overexpression of TSG-6 confers a growth advantage to these cells. (Circ Res. 1997;81:289-296.)

ISSN:0009-7330    

出版商:OVID    

年代:1997

数据来源: OVID

摘要:

Epidermal fatty acid-binding protein (E-FABP), previously characterized in human keratinocytes, is a cytoplasmic protein of 15 kD that specifically binds fatty acids (FAs). Previous PAGE-immunoblotting studies indicated that several human tissues display an immunoreactive band with an electrophoretic mobility identical to that of E-FABP. The aim of this study was to determine in which cells, other than keratinocytes, E-FABP might be expressed. By immunohistochemistry, we show that E-FABP is expressed in endothelial cells of the microvasculature of the placenta, heart, skeletal muscle, small intestine, lung, and renal medulla. Interestingly, in lung, a tissue of endodermal origin, E-FABP staining was also localized to secretory cells, ie, Clara cells, goblet cells, and probably a subpopulation of pneumocytes. RNA isolated from cultured human umbilical vein and normal human dermal microvascular endothelial cells was analyzed by reverse-transcriptase polymerase chain reaction (RT-PCR). Southern blotting and sequencing of the cloned RT-PCR products demonstrate that endothelial E-FABP is identical to keratinocyte E-FABP. These data suggest that E-FABP-mediated FA transport occurs at the level of the microvasculature in several FA target organs. (Circ Res. 1997;81:297-303.)

ISSN:0009-7330    

出版商:OVID    

年代:1997

数据来源: OVID

摘要:

There is currently a stark therapeutic void in the treatment of evolving stroke. Although P-selectin is rapidly expressed by hypoxic endothelial cells in vitro, the functional significance of P-selectin expression in stroke remains unexplored. In order to identify the pathophysiological consequences of P-selectin expression and to identify P-selectin blockade as a potential new approach for the treatment of stroke, experiments were performed using a murine model of focal cerebral ischemia and reperfusion. Early P-selectin expression in the postischemic cerebral cortex was demonstrated by the specific accumulation of radiolabeled anti-murine P-selectin IgG, with the increased P-selectin expression localized to the ipsilateral cerebral microvascular endothelial cells by immunohistochemistry. In experiments designed to test the functional significance of increased P-selectin expression in stroke, neutrophil accumulation in the ischemic cortex of mice expressing the P-selectin gene (PS +/+) was demonstrated to be significantly greater than that in homozygous P-selectin-null mice (PS -/-). Reduced neutrophil influx was accompanied by greater postischemic cerebral reflow (measured by laser Doppler) in the PS -/- mice. In addition, PS -/- mice demonstrated smaller infarct volumes (5-fold reduction, P<.05) and improved survival compared with PS +/+ mice (88% versus 44%, P<.05). Functional blockade of P-selectin in PS +/+ mice using a monoclonal antibody directed against murine P-selectin also improved early reflow and stroke outcome compared with control mice, with reduced cerebral infarction volumes noted even when the blocking antibody was administered after occlusion of the middle cerebral artery. These data are the first to demonstrate a pathophysiological role for P-selectin in stroke and suggest that P-selectin blockade may represent a new therapeutic target in the treatment of stroke.(Circ Res. 1997;81:304-310.)

ISSN:0009-7330    

出版商:OVID    

年代:1997

数据来源: OVID

摘要:

Vascular remodeling is regulated by a combination of hemodynamic, environmental, and genetic factors and may be influenced by age. To evaluate age-dependent remodeling in rats, we developed and used a quantitative highly reproducible model of carotid flow alteration. Fourteen juvenile (99 +/- 3 g) and 9 adult (199 +/- 5 g) male inbred Fischer rats underwent ligation of the left internal and external carotid arteries under anesthesia. Left common carotid blood flow immediately decreased by [nearly =]93%, whereas flow in the contralateral carotid increased by [nearly =]46%. After 4 weeks, the left carotid outer diameter (OD) significantly decreased in both juvenile and adult rats (as measured in vivo and by histological morphometry) compared with sham-operated rats. Changes in shear stress acutely mirrored the changes in blood flow. OD increased and shear stress returned to initial values after chronic exposure to increased flow in juvenile but not adult rats. To develop a simple quantitative index of remodeling that would not require killing the animals, we measured the OD in vivo and compared the ratio of right to left OD (OD ratio [ODR]) between groups. The initial ODR for all groups was [nearly =]1.0. After 4 weeks of altered flow, the ODR was significantly greater in juvenile than in adult rats (1.48 +/- 0.05 versus 1.29 +/- 0.04, respectively; P=.030), indicating that juvenile rats experienced more extensive remodeling than did the adult rats. We also found that unilateral carotid ligation caused a left versus right difference in endothelial NO synthase protein levels after 4 weeks that was not present in the sham-operated animals. Thus, the model described here shows that flow-induced vascular remodeling is dependent on age and supports the hypothesis that the driving force for remodeling involves shear stress and possibly NO. Because the model is quantitative, it allows dissection of the genetic factors that regulate remodeling in inbred rat strains. (Circ Res. 1997;81:311-319.)

ISSN:0009-7330    

出版商:OVID    

年代:1997

数据来源: OVID

摘要:

Blood flow and the tractive force shear stress are important determinants of artery caliber, and reduced shear predisposes arteries to intimal thickening and atherosclerosis. The molecular basis for shear-induced changes in artery wall structure is poorly defined. A number of factors associated with normal and pathological artery wall remodeling are induced by shear stress in endothelial cell cultures. These include platelet-derived growth factor (PDGF), a potent mitogen, chemoattractant, and vasoconstrictor. To determine whether similar changes occur in vivo, we examined the effects of reduced blood flow on endothelial cell PDGF expression and proliferation in the rat carotid artery. Branches of the right internal and external carotid arteries were ligated, reducing common carotid artery blood flow from 8.0 +/- 0.6 to 0.5 +/- 0.1 mL/min while increasing flow in the left carotid from 7.1 +/- 0.6 to 10.8 +/- 0.7 mL/min. Shear stress following the procedure was 1.4 +/- 0.2 and 33.4 +/- 1.1 dyne/cm2in carotids with reduced blood flow (RF) and increased blood flow (IF), respectively. Arteries were harvested 6, 24, 48, or 72 hours after ligation, perfusion-fixed, and opened longitudinally. Endothelial cell proliferation (bromodeoxyuridine [BrdU] labeling) was assessed en face at 24, 48, and 72 hours; expression of mRNA for PDGF-A and -B chains and PDGF alpha- and beta-receptors (in situ hybridization) was determined at 6, 48, and 72 hours after unilateral flow reduction. RF induced endothelial cell proliferation, which peaked at 48 hours (RF BrdU labeling: 24 hours, 0.4 +/- 0.2%; 48 hours, 7.2 +/- 2.0%; and 72 hours, 4.1 +/- 0.6%; n=5). PDGF-B expression increased in RF compared with IF endothelium within 48 hours and persisted at 72 hours (percent labeling [RF/IF x 100]: 6 hours, 76 +/- 20%; 48 hours, 395 +/- 179%; and 72 hours, 208 +/- 44%; n=3). PDGF-A expression was similarly increased in RF endothelium. In contrast, expression of PDGF alpha- and beta-receptors was undetectable in RF and IF endothelium at all times. We conclude that endothelial cell PDGF ligand expression is induced by reduced shear stress in vivo and may play an important role in flow-mediated remodeling and atherogenesis. (Circ Res. 1997;81:320-327.)

ISSN:0009-7330    

出版商:OVID    

年代:1997

数据来源: OVID

摘要:

75% with decreased blood flow. The inhibition of proliferation was unabated after 7 days of reduced flow. These findings indicate that the coordinated regulation of cell death and cell proliferation, in response to changes in arterial blood flow rates, contributes to arterial remodeling during development. (Circ Res. 1997;81:328-337.)

ISSN:0009-7330    

出版商:OVID    

年代:1997

数据来源: OVID

摘要:

descending thoracic aorta, with concentrations of total and nonesterified cholesterol 17% and 25% (both P<.05) greater, respectively, for the pulmonary artery than for the descending thoracic aorta. Rank order remained the same during 16 days of cholesterol feeding, but differences between arterial regions were exaggerated. After rabbits were fed cholesterol for 16 days, total and esterified cholesterol concentrations were 57% and 920% (both P<.01) greater, respectively, for the pulmonary artery than for the descending thoracic aorta, with much smaller differences between the aortic regions. In contrast, after rabbits were fed cholesterol for 17 weeks, concentrations of total, esterified, and nonesterified cholesterol were similar for the pulmonary artery and aortic arch, but these forms of cholesterol were increased 100%, 130%, and 53% (all P<.03), respectively, for the aortic arch compared with the descending thoracic aorta. Cholesterol concentrations for the pulmonary artery were positively associated with those for the aortic regions during the first 16 days of cholesterol feeding, but for rabbits fed cholesterol for 17 weeks the associations were either negative or absent. These results indicate that relative rates of cholesterol accumulation in the pulmonary artery and aorta differ at different stages of atherogenesis and suggest that the balance between processes that deliver cholesterol to, and remove cholesterol from, the artery may change in different ways in these arterial regions during atherogenesis. (Circ Res. 1997;81:338-345.)

ISSN:0009-7330    

出版商:OVID    

年代:1997

数据来源: OVID

摘要:

The pulmonary artery and the aorta are similarly susceptible to atherosclerosis in rabbits. However, the mechanism(s) that accounts for this is not yet known. This study investigated the hypothesis that one or more aspects of arterial low-density lipoprotein (LDL) transport and metabolism might explain the similar susceptibility of the aortic arch and pulmonary artery to atherosclerosis and the increased susceptibility of these arterial regions compared with the descending thoracic aorta. We determined permeability to LDL, rates of LDL degradation, and concentrations of undegraded LDL for the intima-media of normal rabbits and those fed cholesterol for [nearly =]8 days. Intima-media permeability did not differ between corresponding arterial regions of normal rabbits and rabbits fed cholesterol for 8 days and was similar for the aortic arch and pulmonary artery. Rates of LDL degradation and concentrations of undegraded LDL for the intima-media were influenced by cholesterol feeding. These measures were reduced in fractional terms but increased in absolute terms as a result of hypercholesterolemia, without differences between corresponding parameters for the pulmonary artery and aortic arch. However, permeability to LDL, rates of LDL degradation, and concentrations of undegraded LDL were increased for the intima-media of the aortic arch compared with the descending thoracic aorta. Similar, although not always significant, trends were evident for the comparison of the pulmonary artery and descending thoracic aorta. Differences in LDL transport and metabolism and changes after feeding cholesterol for 8 days parallel the relative susceptibility to atherosclerosis for the three arterial regions studied. These results support the role of arterial LDL transport and metabolism in atherogenesis and potentially provide a mechanistic explanation for the differences in susceptibility to atherosclerosis for these three arterial regions. (Circ Res. 1997;81:346-354.)

ISSN:0009-7330    

出版商:OVID    

年代:1997

数据来源: OVID

摘要:

NO, produced by endothelial NO synthase (eNOS), is a key mediator of pulmonary vasodilation during cardiopulmonary transition at birth. The capacity for NO production is maximal at term because pulmonary eNOS expression increases during late gestation. Since fetal estrogen levels rise markedly during late gestation and there is indirect evidence that the hormone enhances nonpulmonary NO production in adults, estrogen may upregulate eNOS in fetal pulmonary artery endothelium. Therefore, we studied the direct effects of estrogen on eNOS expression in ovine fetal pulmonary artery endothelial cells (PAECs). Estradiol-17 beta caused a 2.5-fold increase in NOS enzymatic activity in PAEC lysates. This effect was evident after 48 hours, and it occurred in response to physiological concentrations of the hormone (10 sup -10 to 10 sup -6 mol/L). The increase in NOS activity was related to an upregulation in eNOS protein expression, and eNOS mRNA abundance was also enhanced. Estrogen receptor antagonism with ICI 182,780 completely inhibited estrogen-mediated eNOS upregulation, indicating that estrogen receptor activation is necessary for this response. In addition, immunocytochemistry revealed that fetal PAECs express estrogen receptor protein. Furthermore, transient transfection assays with a specific estrogen-responsive reporter system have demonstrated that the endothelial estrogen receptor is capable of estrogen-induced transcriptional transactivation. Thus, estrogen upregulates eNOS gene expression in fetal PAECs through the activation of PAEC estrogen receptors. This mechanism may be responsible for pulmonary eNOS upregulation during late gestation, thereby optimizing the capacity for NO-mediated pulmonary vasodilation at birth. (Circ Res. 1997;81:355-362.)

ISSN:0009-7330    

出版商:OVID    

年代:1997

数据来源: OVID

摘要:

Endothelial cell permeability is impaired in diabetes mellitus and may be increased by high extracellular glucose concentrations. High glucose activates protein kinase C (PKC), a family of kinases vital to intracellular signaling. We tested the hypothesis that high glucose concentration activates PKC in endothelial cells and leads to an increase in endothelial cell permeability via distinct PKC isoforms. Porcine aortic endothelial cells were used, and the PKC isoforms alpha, delta, epsilon, zeta, and theta were identified in these cells. Glucose caused a rapid dose-dependent increase in endothelial cell permeability, with an EC50of 17.5 mmol/L. Phorbol 12-myristate 13-acetate (TPA) induced an increase in permeability very similar to that elicited by glucose. The effect of glucose and TPA was totally reversed by preincubating the cells with the PKC inhibitors staurosporine (10 sup -8 mol/L) and Goe 6976 (10 sup -8 mol/L). Downregulation of PKC by preincubation with TPA for 24 hours also abolished the effect of glucose and TPA on endothelial cell permeability. High glucose (20 mmol/L) caused an increase in PKC activity at 2, 10, and 30 minutes. Cell fractionation and Western blot analysis showed a glucose-induced translocation of PKC alpha and PKC epsilon. Confocal microscopy confirmed the translocation and showed an association of PKC alpha and PKC epsilon with nuclear structures and the cell membrane. Specific antisense oligodesoxynucleotides (ODNs) against PKC alpha reduced the expression of the isoform, abolished the effects of glucose on endothelial cell permeability completely, and reduced the TPA effect significantly. In contrast, specific antisense ODNs against PKC epsilon had no effect on glucose-induced permeability and only a minor effect on the TPA-induced increase in permeability. We conclude that an increase in extracellular glucose leads to a rapid dose-dependent increase in endothelial cell permeability via the activiation of PKC and that this effect is mediated by the PKC isoform alpha. (Circ Res. 1997;81:363-371.)

ISSN:0009-7330    

出版商:OVID    

年代:1997

数据来源: OVID