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Biomedical subjects

N Ferrara

Publications and source records attributed to N Ferrara.

At least 37 records · Page 2Linked to original sources
PubMed2000

Vascular endothelial growth factor and the regulation of angiogenesis.

The development of a vascular supply is essential not only for organ development and differentiation during embryogenesis but also for wound healing and reproductive functions in the adult Folkman, 1995). Angiogenesis is also implicated in the pathogenesis of a variety of disorders: proliferative retinopathies, age-related macular degeneration, tumors, rheumatoid arthritis, and psoriasis (Folkman, 1995; Garner, 1994). Several potential regulators of angiogenesis have been identified, including fibroblast growth factor-a (aFGF), bFGF, transforming growth factor-alpha (TGF-alpha), TGF-beta, hepatocyte growth factor/scatter factor (HGF/SF), tumor necrosis factor-alpha (TNF-alpha), angiogenin, and interleukin-8 (IL-8) (Folkman and Shing, 1992; Risau, 1997). More recently, the angiopoietins, the ligands of the Tie-2 receptor (Suri et al., 1996; Maisonpierre et al., 1997), have been identified. Vascular endothelial growth factor (VEGF) is an endothelial-cell-specific mitogen. The finding that VEGF was potent and specific for vascular endothelial cells and, unlike bFGF, freely diffusible, led to the hypothesis that this molecule plays a unique role in the regulation of physiological and pathological angiogenesis (Ferrara and Henzel, 1989: Leung et al., 1989). Over the last few years, several additional members of the VEGF gene family have been identified, including placenta growth factor (PIGF) (Maglione et al., 1991,1993), VEGF-B (Olofsson et al., 1996), VEGF-C (Joukov et al., 1996; Lee et al., 1996), and VEGF-D (Orlandini et al., 1996. Achen et al., 1998). There is compelling evidence that VEGF plays an essential role in the development and differentiation of the cardiovascular system (Ferrara and Davis-Smyth, 1997).

Adult↗
PubMed1999

Intracoronary serotonin release after high-pressure coronary stenting.

It is known that platelet-derived serotonin at the site of coronary angioplasty induces an increase in coronary tone and plays a role in vasoconstriction after balloon angioplasty. The goal of the present investigation was to compare local release of serotonin with changes in coronary tone after coronary stenting and coronary angioplasty. Twenty patients with significant stenosis (> or =50% diameter narrowing) of the left anterior descending coronary artery were referred to traditional coronary angioplasty (10 patients; group 1) or high-pressure coronary stenting (10 patients; group 2). An additional 16 patients with similar angiographic characteristics were referred to the coronary angioplasty group (8 patients; group 1a) or stenting group (8 patients; group 2a) after pretreatment with ketanserin. Serotonin plasma levels in coronary sinus and coronary cross-sectional area distal to the site of dilatation were measured before and after bath revascularization procedures. In groups 1 and 1a, plasma serotonin levels in coronary sinus increased from basal values of 3.2+/-0.8 and 3.2+/-0.5 ng/ml to 29.5+/-13 and 25.6+/-9 ng/ml after ballooning (p <0.001 vs baseline). In groups 2 and 2a, plasma serotonin levels in coronary sinus increased from basal values of 3.5+/-0.3 and 3.5+/-0.7 ng/ml to 114.6+/-34 and 113+/-29 ng/ml after stenting (p <0.001 vs baseline and vs postangioplasty values in groups 1 and 1a). Coronary cross-sectional area distal to the site of dilatation significantly decreased after angioplasty in group 1 (from 4.33+/-0.4 to 3.32+/-0.3 mm2; p <0.001), and after stenting in group 2 (from 4.27+/-0.3 to 2.86+/-0.2 mm2; p <0.001 vs baseline, and p <0.02 vs values after coronary angioplasty in group 1). Pretreatment with ketanserin significantly reduced distal coronary vasoconstriction after angioplasty and stenting. It is concluded that the higher local serotonin release after coronary stenting may explain the more marked coronary constriction observed after prosthesis deployment with respect to traditional coronary angioplasty. Ketanserin is able to significantly attenuate the increase in distal coronary tone induced by both revascularization procedures.

Angioplasty, Balloon, Coronary↗
PubMed1999

Oncogenic ras fails to restore an in vivo tumorigenic phenotype in embryonic stem cells lacking vascular endothelial growth factor (VEGF).

Vascular endothelial growth factor (VEGF) is a major regulator of angiogenesis. Previous studies have shown that the ability of murine embryonic stem (ES) cells to form teratocarcinomas in nude mice is substantially reduced following targeted inactivation of the VEGF gene. We sought to determine whether VEGF-/- ES cells' tumorigenic phenotype can be rescued by transfection with a mutant H-ras. VEGF-/- ES cells were transfected with expression vector which directs the constitutive synthesis of oncogenic Val-12 ras. Expression of ras protein was documented by Western blot analysis. We injected several clones with different levels of Val-12 ras expression in nude mice. In agreement with our earlier report, VEGF-/- ES cells formed much smaller tumors than control ES cells. However, none of the ras-expressing clones tested formed tumors larger than those derived from parental VEGF-/- cells. Thus, pluripotent cells such as ES cells are unable to compensate for the loss of VEGF even in the presence of a potent oncogenic stimulus such as mutant ras. These findings strengthen the hypothesis that VEGF-mediated angiogenesis is crucial for effective in vivo tumor growth.

Animals↗
PubMed1999

Age-related decrease in cardiac tolerance to oxidative stress.

Oxygen radical-mediated injury has been implicated in the process of cardiac aging. We investigated the tolerance to oxidative stress of hearts from rats of different age. Langendorff-perfused hearts from 3-12-month-old rats received a 30 min infusion of the reactive oxygen specie hydrogen peroxide (H2O2, 60 microM), followed by a 15 min wash-out. H2O2 infusion resulted in a significantly larger increase in end-diastolic pressure in hearts of 6- and 12-month-old rats than 3 months (P<0.01). In addition, developed pressure and rate-pressure product decreased more evidently in 12-month-old hearts (P<0.01 vs 3 and 6 months). Arrhythmia analysis showed higher score in hearts of 12- and 6-month-old rats with respect to 3-month-old animals (P<0.05). Cardiac release of oxidized glutathione (an index of the ability of the heart to inactivate oxygen metabolites) was significantly lower in hearts from rats of 6 and 12 months than in younger animals (P<0.001). Finally, cardiac concentrations of the scavenger enzymes glutathione peroxidase and Mn-superoxide dismutase also significantly decreased with age. In conclusion, in rat heart metabolic and functional tolerance toward oxidative stress decreases with age. This phenomenon may contribute to the development of cardiovascular alterations with increasing age.

Aging↗
PubMed1999

Molecular and biological properties of vascular endothelial growth factor.

Vascular endothelial growth factor (VEGF) is a fundamental regulator of normal and abnormal angiogenesis. Recent evidence indicates that VEGF is essential for embryonic vasculogenesis and angiogenesis. Furthermore, VEGF is required for the cyclical blood vessel proliferation in the female reproductive tract and for longitudinal bone growth and endochondral bone formation. Substantial experimental evidence also implicates VEGF in pathological angiogenesis. Anti-VEGF monoclonal antibodies or other VEGF inhibitors block the growth of many tumor cell lines in nude mice. Furthermore, the concentrations of VEGF are elevated in the aqueous and vitreous humors of patients with proliferative retinopathies such as the diabetic retinopathy. In addition, VEGF-induced angiogenesis results in a therapeutic benefit in several animal models of myocardial or limb ischemia. Currently, both therapeutic angiogenesis using recombinant VEGF or VEGF gene transfer and inhibition of VEGF-mediated pathological angiogenesis are being pursued.

Animals↗
PubMed1999

Ischemic threshold and myocardial stunning in the aging heart.

The aging heart appears to be more susceptible to ischemia-reperfusion injury than the adult heart. There is no evidence of an age-related difference in the threshold of myocardial ischemia and myocardial stunning. We studied the effects on mechanical, hemodynamic, and metabolic parameters of graded reduction of coronary perfusion pressure from 66 to 29 mmHg in isolated and perfused hearts from adult and senescent rats. Cardiac function was also assessed during recovery following ischemic period. In both adult and senescent hearts developed pressure and +dP/dt linearly decreased and end-diastolic pressure linearly increased with decreasing perfusion pressure. However, all mechanical parameters were more severely impaired in senescent than in adult hearts at 37 mmHg and 29 mmHg perfusion pressure, respectively (p < 0.01 vs. adult). At 29 mmHg, in both adult and senescent hearts lactate production similarly increased whereas creatine kinase leakage did not differ from controls. Developed pressure recovered more slowly in senescent than in adult hearts (p < 0.001) in the absence of cellular damage and in the presence of restoration of coronary flow. Lactate production observed at the same step of coronary perfusion pressure suggests that the ischemic threshold is similar in adult and senescent hearts. The slow recovery of myocardial contractility after the ischemic period observed in senescent hearts suggests an age-related increase in myocardial stunning.

Aging↗
PubMed1999

Clinical applications of angiogenic growth factors and their inhibitors.

Promoting the formation of new collateral vessels in ischemic tissues using angiogenic growth factors (therapeutic angiogenesis) is a an exciting frontier of cardiovascular medicine. Conversely, inhibition of the action of key regulators of angiogenesis, such as VEGF, constitutes a promising approach for the treatment of solid tumors and intraocular neovascular syndromes. These concepts are being tested now in clinical trials.

Animals↗
PubMed1999

VEGF couples hypertrophic cartilage remodeling, ossification and angiogenesis during endochondral bone formation.

Hypertrophic chondrocytes in the epiphyseal growth plate express the angiogenic protein vascular endothelial growth factor (VEGF). To determine the role of VEGF in endochondral bone formation, we inactivated this factor through the systemic administration of a soluble receptor chimeric protein (Flt-(1-3)-IgG) to 24-day-old mice. Blood vessel invasion was almost completely suppressed, concomitant with impaired trabecular bone formation and expansion of hypertrophic chondrocyte zone. Recruitment and/or differentiation of chondroclasts, which express gelatinase B/matrix metalloproteinase-9, and resorption of terminal chondrocytes decreased. Although proliferation, differentiation and maturation of chondrocytes were apparently normal, resorption was inhibited. Cessation of the anti-VEGF treatment was followed by capillary invasion, restoration of bone growth, resorption of the hypertrophic cartilage and normalization of the growth plate architecture. These findings indicate that VEGF-mediated capillary invasion is an essential signal that regulates growth plate morphogenesis and triggers cartilage remodeling. Thus, VEGF is an essential coordinator of chondrocyte death, chondroclast function, extracellular matrix remodeling, angiogenesis and bone formation in the growth plate.

Animals↗
PubMed1999

Role of vascular endothelial growth factor in the regulation of angiogenesis.

Compelling evidence indicates that vascular endothelial growth factor (VEGF) is a fundamental regulator of normal and abnormal angiogenesis. The loss of a single VEGF allele results in defective vascularization and early embryonic lethality. VEGF plays also a critical role in kidney development, and its inactivation during early postnatal life results in the suppression of glomerular development and kidney failure. Recent evidence indicates that VEGF is also essential for angiogenesis in the female reproductive tract and for morphogenesis of the epiphyseal growth plate and endochondral bone formation. Substantial experimental evidence also implicates VEGF in pathological angiogenesis. Anti-VEGF monoclonal antibodies or other VEGF inhibitors block the growth of several human tumor cell lines in nude mice. Furthermore, the concentrations of VEGF are elevated in the aqueous and vitreous humors of patients with proliferative retinopathies such as the diabetic retinopathy. In addition, VEGF-induced angiogenesis results in a therapeutic benefit in several animal models of myocardial or limb ischemia. Currently, both therapeutic angiogenesis using recombinant VEGF or VEGF gene transfer and inhibition of VEGF-mediated pathological angiogenesis are being pursued clinically.

Animals↗
PubMed1999

Verapamil reduces dipyridamole-induced myocardial ischemia in patients with coronary artery disease.

The aim of this study was to evaluate the effects of verapamil administration on dipyridamole-induced transient wall-motion abnormalities as detected by two-dimensional echocardiographic monitoring in patients with coronary artery disease. Twenty-eight patients (16 men and 12 women; mean age, 60+/-7 years) with angiographic evidence of significant coronary artery disease, positive dipyridamole echocardiography test results at basal condition on two consecutive days, were prospectively studied. Patients were randomized to verapamil (360 mg/day) or placebo treatments, given in three divided doses daily for 7 days; at the end of this time, each patient crossed over to the alternate regimen. Dipyridamole echocardiographic testing was repeated at the end of each treatment period. Our data demonstrate that verapamil significantly reduces the dipyridamole-induced wall-motion score index, a quantitative marker of acute myocardial ischemia (1.7+/-0.4 vs. 1.3+/-0.2; p<0.001). Hemodynamic data show that the drug reduces heart rate and rate-pressure product at basal condition (heart rate from 75+/-8 to 67+/-9 beats/min; p<0.001; rate-pressure product from 99+/-13 to 86+/-13 U x 10(-2); p<0.001) and at peak dipyridamole infusion (heart rate from 96+/-8 to 89+/-6 beats/min; p<0.001; rate pressure product from 127+/-21 to 118+/-13 U x 10(-2); p<0.05) with respect to placebo treatment. We conclude that verapamil is able to reduce dipyridamole-induced ischemia, as detected by two-dimensional echocardiographic monitoring, in patients with coronary artery disease by reducing, at least partially, myocardial oxygen consumption. Moreover, its beneficial action could be related to the effects of the drug on coronary collateral circulation and on sympathetic modulation.

Aged↗
PubMed1999

VEGF antagonism reduces edema formation and tissue damage after ischemia/reperfusion injury in the mouse brain.

VEGF is mitogenic, angiogenic, and a potent mediator of vascular permeability. VEGF causes extravasation of plasma protein in skin bioassays and increases hydraulic conductivity in isolated perfused microvessels. Reduced tissue oxygen tension triggers VEGF expression, and increased protein and mRNA levels for VEGF and its receptors (Flt-1, Flk-1/KDR) occur in the ischemic rat brain. Brain edema, provoked in part by enhanced cerebrovascular permeability, is a major complication in central nervous system pathologies, including head trauma and stroke. The role of VEGF in this pathology has remained elusive because of the lack of a suitable experimental antagonist. We used a novel fusion protein, mFlt(1-3)-IgG, which sequesters murine VEGF, to treat mice exposed to transient cortical ischemia followed by reperfusion. Using high-resolution magnetic resonance imaging, we found a significant reduction in volume of the edematous tissue 1 day after onset of ischemia in mice that received mFlt(1-3)-IgG. 8-12 weeks after treatment, measurements of the resultant infarct size revealed a significant sparing of cortical tissue. Regional cerebral blood flow was unaffected by the administration of mFlt(1-3)-IgG. These results demonstrate that antagonism of VEGF reduces ischemia/reperfusion-related brain edema and injury, implicating VEGF in the pathogenesis of stroke and related disorders.

Animals↗
PubMed1999

VEGF is required for growth and survival in neonatal mice.

We employed two independent approaches to inactivate the angiogenic protein VEGF in newborn mice: inducible, Cre-loxP- mediated gene targeting, or administration of mFlt(1-3)-IgG, a soluble VEGF receptor chimeric protein. Partial inhibition of VEGF achieved by inducible gene targeting resulted in increased mortality, stunted body growth and impaired organ development, most notably of the liver. Administration of mFlt(1-3)-IgG, which achieves a higher degree of VEGF inhibition, resulted in nearly complete growth arrest and lethality. Ultrastructural analysis documented alterations in endothelial and other cell types. Histological and biochemical changes consistent with liver and renal failure were observed. Endothelial cells isolated from the liver of mFlt(1-3)-IgG-treated neonates demonstrated an increased apoptotic index, indicating that VEGF is required not only for proliferation but also for survival of endothelial cells. However, such treatment resulted in less significant alterations as the animal matured, and the dependence on VEGF was eventually lost some time after the fourth postnatal week. Administration of mFlt(1-3)-IgG to juvenile mice failed to induce apoptosis in liver endothelial cells. Thus, VEGF is essential for growth and survival in early postnatal life. However, in the fully developed animal, VEGF is likely to be involved primarily in active angiogenesis processes such as corpus luteum development.

Age Factors↗
PubMed1999

Evidence of exercise-induced myocardial ischemia in patients with primary aldosteronism: the Cross-sectional Primary Aldosteronism and Heart Italian Multicenter Study.

BACKGROUND: Primary aldosteronism (PA) is a disease associated with hypersecretion of aldosterone caused by an aldosterone-producing adrenal adenoma, bilateral adrenal hyperplasia, and, although rarely, by adrenal carcinoma. Arterial hypertension induces several cardiovascular alterations that yield a high cardiovascular risk. It has been shown that reduced myocardial perfusion at rest, assessed by thallium-201 myocardial scintigraphy, was greater in PA than in essential hypertension (EH). However, it is still unknown whether reduced myocardial perfusion at rest and/or regional function abnormalities are present during exercise-induced myocardial stress. PURPOSE: We addressed the impact of PA on myocardial ischemia and sought to identify signs of exercise-induced myocardial ischemia (assessed by MIBI-SPECT and echocardiography) in patients with PA compared to patients with EH. Patients with consistent signs of myocardial ischemia on all of the tests were studied by coronary arteriography. PATIENTS: We studied 72 patients with PA and an age/sex-matched group of 72 patients with EH enrolled in the cross-sectional Primary Aldosteronism and Heart Italian Multicenter Study (PAHIMS). METHODS: Regional function was detected from echocardiographic measurement of wall motion done at baseline and immediately after exercise. Myocardial perfusion was evaluated by SPECT imaging after injecting 99mTc-MIBI with the same-day protocol using the rest-stress sequence. RESULTS: Although the conditions of arterial pressure, duration of hypertension, and target organ damage were equivalent, the patients with PA had greater incidence of both reversible perfusion defects and abnormalities of regional function. Moreover, multiple regression analysis showed that the high plasma aldosterone level was highly predictive for SPECT ischemic score and wall motion index, suggesting that PA contributes to cardiovascular risk over and above that associated with ventricular hypertrophy. Exercise-induced myocardial ischemia in PA was not segmental but widely distributed suggesting that this phenomenon was not related to abnormal coronary perfusion. Accordingly, of the 38 patients with PA who underwent coronarography, there was no presence of significant coronary atherosclerotic lesions in 30 (78.9%) of the patients. CONCLUSIONS: The PAHIMS observed more exercise-induced moderate myocardial ischemic defects (co-detected by SPECT and echocardiograms and not segmental but widely allocated) in patients with PA than in patients with EH. This phenomenon occurred in a greater percentage of patients with PA without significant coronary lesions (78.95%, n = 38), which supports the possible presence of small-vessel intramyocardial disease.

Adult↗
PubMed1998

Vascular endothelial growth factor regulates endothelial cell survival through the phosphatidylinositol 3'-kinase/Akt signal transduction pathway. Requirement for Flk-1/KDR activation.

Vascular endothelial growth factor (VEGF) has been found to have various functions on endothelial cells, the most prominent of which is the induction of proliferation and differentiation. In this report we demonstrate that VEGF or a mutant, selectively binding to the Flk-1/KDR receptor, displayed high levels of survival activity, whereas Flt-1-specific ligands failed to promote survival of serum-starved primary human endothelial cells. This activity was blocked by the phosphatidylinositol 3'-kinase (PI3-kinase)-specific inhibitors wortmannin and LY294002. Endothelial cells cultured in the presence of VEGF and the Flk-1/KDR-selective VEGF mutant induced phosphorylation of the serine-threonine kinase Akt in a PI3-kinase-dependent manner. Akt activation was not detected in response to stimulation with placenta growth factor or an Flt-1-selective VEGF mutant. Furthermore, a constitutively active Akt was sufficient to promote survival of serum-starved endothelial cells in transient transfection experiments. In contrast, overexpression of a dominant-negative form of Akt blocked the survival effect of VEGF. These findings identify the Flk-1/KDR receptor and the PI3-kinase/Akt signal transduction pathway as crucial elements in the processes leading to endothelial cell survival induced by VEGF. Inhibition of apoptosis may represent a major aspect of the regulatory activity of VEGF on the vascular endothelium.

Amino Acid Chloromethyl Ketones↗
PubMed1998

Homologous up-regulation of KDR/Flk-1 receptor expression by vascular endothelial growth factor in vitro.

We investigated the possibility that vascular endothelial growth factor (VEGF) treatment could regulate KDR/Flk-1 receptor expression in endothelial cells. Bovine adrenal cortex endothelial cells were incubated with 200 pM rhVEGF165 for 0-7 days. Western blot analysis showed a 3-5-fold increase in total KDR protein following 4-day VEGF treatment. Scatchard analysis revealed that VEGF induced a 2-3-fold increase in high affinity receptor number (5.0 x 10(4)/cell versus 2. 4 x 10(4)/cell) without significantly affecting receptor binding affinity (Kd 76 pM versus 72 pM). Quantitative polymerase chain reaction analysis demonstrated a 3-fold increase in KDR mRNA levels following VEGF exposure. VEGF-induced KDR expression primarily occurred at the transcriptional level as demonstrated by a luciferase reporter assay system. Receptor selective mutants with wild-type KDR binding and decreased Flt-1 binding also induced KDR up-regulation; in contrast, mutants with decreased KDR binding and wild-type Flt-1 binding did not, suggesting that KDR receptor signaling mediated the increase in KDR expression. Inhibition of tyrosine kinase, Src tyrosine kinase, protein kinase C, and mitogen-activated protein kinase activities all blocked VEGF-induced KDR up-regulation. Finally, co-incubation of nitric-oxide synthase inhibitors with VEGF had no significant effect on KDR expression, but 100 microM sodium nitroprusside, a NO donor, significantly inhibited VEGF-induced KDR up-regulation, indicating that NO negatively regulates KDR expression. In conclusion, our data demonstrate that VEGF binding to the KDR receptor tyrosine kinase results in an increase in KDR receptor gene transcription and protein expression. Thus, KDR up-regulation induced by VEGF may represent an important positive feedback mechanism for VEGF action in tumor and ischemia-induced angiogenesis.

Animals↗
PubMed1998

Tumor necrosis factor-alpha regulates expression of vascular endothelial growth factor receptor-2 and of its co-receptor neuropilin-1 in human vascular endothelial cells.

Tumor necrosis factor-alpha (TNF-alpha) modulates gene expression in endothelial cells and is angiogenic in vivo. TNF-alpha does not activate in vitro migration and proliferation of endothelium, and its angiogenic activity is elicited by synthesis of direct angiogenic inducers or of proteases. Here, we show that TNF-alpha up-regulates in a dose- and time-dependent manner the expression and the function of vascular endothelial growth factor receptor-2 (VEGFR-2) as well as the expression of its co-receptor neuropilin-1 in human endothelium. As inferred by nuclear run-on assay and transient expression of VEGFR-2 promoter-based reporter gene construct, the cytokine increased the transcription of the VEGFR-2 gene. Mithramycin, an inhibitor of binding of nuclear transcription factor Sp1 to the promoter consensus sequence, blocked activation of VEGFR-2, suggesting that the up-regulation of the receptor required Sp1 binding sites. TNF-alpha increased the cellular amounts of VEGFR-2 protein and tripled the high affinity 125I-VEGF-A165 capacity without affecting the Kd of ligand-receptor interaction. As a consequence, TNF-alpha enhanced the migration and the wound healing triggered by VEGF-A165. Since VEGFR-2 mediates angiogenic signals in endothelium, our data indicate that its up-regulation is another mechanism by which TNF-alpha is angiogenic and may provide insight into the mechanism of neovascularization as occurs in TNF-alpha-mediated pathological settings.

Antigens, Surface↗
PubMed1998

Vascular endothelial growth factor induces expression of the antiapoptotic proteins Bcl-2 and A1 in vascular endothelial cells.

We examined the role of vascular endothelial growth factor (VEGF) in preventing apoptosis in primary human umbilical vein endothelial (HUVE) cells. VEGF was capable of preventing serum starvation-induced apoptosis at concentrations between 10 and 100 ng/ml. The addition of VEGF to serum-starved HUVE cells led to a 5. 2-fold induction of Bcl-2 after 36 h and to a transient, 2.4-fold induction of A1 after a 7-h incubation, as quantitated by real time reverse transcriptase-polymerase chain reaction analysis. Western blot analysis demonstrated a 2-3-fold induction of Bcl-2 protein after 18-36 h of exposure to VEGF and a transient induction of A1 after 7 h of VEGF stimulation. Moreover, overexpression of Bcl-2 by means of transient biolistic transfection experiments of HUVE cells was sufficient to prevent endothelial cells from apoptotic cell death in the absence of VEGF. These findings indicate that Bcl-2 plays an important role in mediating the survival activity of VEGF on endothelial cells.

Apoptosis↗