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Biomedical subjects

N Ferrara

Publications and source records attributed to N Ferrara.

At least 109 records · Page 6Linked to original sources
PubMed1996

The role of aging on the control of contractile force by Na(+)-Ca2+ exchange in rat papillary muscle.

BACKGROUND: Sarcolemmal Na(+)-Ca2+ exchange system is believed to be fundamental to the control of cardiac contractility. However, the relation between Na(+)-Ca2+ exchange and the control of contractile force has not been studied in senescent myocardium. METHODS: The role of Na(+)-Ca2+ exchange in the regulation of the cardiac muscle's contractile force was studied in adult and senescent papillary muscles by simultaneously measuring intracellular sodium activity (aNai), action potential, and contractile force while varying extracellular concentration of sodium and/or calcium. RESULTS: Reduction of [Na+]o decreased aNai from 8.0 +/- 1.8 to 4.1 +/- 0.8 in adult (-3.9 mM) and from 8.7 +/- 1.9 to 4.7 +/- 0.9 in senescent (-4.0 mM) papillary muscles, while developed tension (DT) increased by 80.2% in adult and by 135.6% in senescent papillary muscles (p < .01 vs adult). During low [Ca2+]o and high [Na+]o, aNai and DT modifications were similar both in adult and senescent papillary muscles. During high [Ca2+]o, aNai decreased to a similar extent in both adult and senescent papillary muscles, while DT increased by 37.8% in adult and by 67.8% in senescent (p < .05 vs adult). Simultaneous reduction of [Na+]o and [Ca2+]o decreased aNai from 8.1 +/- 1.2 to 6.8 +/- 1.1 mM in adult (-1.3 mM), and from 8.4 +/- 1.0 to 7.2 +/- 1.0 mM in senescent (-1.2 mM) papillary muscles while DT decreased by 22.1% in adult and by only 12.0% in senescent (p < .01 vs adult) papillary muscles. Simultaneous increase of [Na+]o and [Ca2+]o similarly increased aNai in both adult senescent papillary muscles, but decreased DT by 28.5% in adult and by 11.7% in senescent (p < .01 vs adult). After [Na+]o modifications, the equilibration time for the ratio of external and internal sodium ion activities was slowed in senescent papillary muscles (i.e., in low [Na+]o solution the equilibration time was 4.6 +/- 0.9 min in adult and 6.3 +/- 1.2 min in senescent papillary muscles, p < .001). CONCLUSIONS: Similar changes of aNai during transmembrane Na+ and Ca2+ gradients modifications associated to changes in contractile force seem to demonstrate that Na(+)-Ca2+ exchange is probably not modified by the aging process. However, the slow equilibration time for the ratio of Na+ activities might reflect an age-related reduction of the Na(+)-K+ pump activity.

Action Potentials↗
PubMed1996

Vascular endothelial growth factor augments muscle blood flow and function in a rabbit model of chronic hindlimb ischemia.

Animal studies have shown that angiogenic factors can increase vascularity and improve blood pressure (BP) in an ischemic limb. Whether changes in these parameters are indicators of significant improvement in muscle function has not been demonstrated. In a rabbit model of hind limb ischemia, we measured blood flow in the extensor digitorum longus muscle (EDL) both at rest and during electrical stimulation. Ablation of the femoral artery caused significant reductions in resting and stimulated EDL blood flow. The chronic reduction in perfusion caused impairment of muscle function (p < 0.01). At 28 days after a single administration of vascular endothelial growth factor (VEGF), stimulated muscle blood flow (3 mg/kg intravenously, i.v.) and muscle function [1 mg intrarterially (i.a.) or 3 mg/kg i.v.] were significantly improved as compared with that of vehicle-treated controls. Simultaneous measurement of the hemodynamic responses in the contralateral limb and in the kidneys confirmed that the effects of VEGF were confined to the ischemic limb. The data agree with findings that angiogenic factors increase perfusion through angiogenesis. We hypothesized that neovascularization allows work-associated muscle hyperemia, resulting in a significant improvement in muscle function. Similar clinical improvements in muscle function would signify a substantial advance in the treatment of peripheral vascular disease.

Angiogenesis Inducing Agents↗
PubMed1996

Effects of vascular endothelial growth factor on hemodynamics and cardiac performance.

Vascular endothelial growth factor (VEGF), a major regulator of angiogenesis, has therapeutic benefit in animal models of coronary or limb ischemia. However, the hemodynamic effects of VEGF have not been investigated. We examined the effects of VEGF on hemodynamics and cardiac performance. Mean arterial pressure (MAP), heart rate (HR), cardiac output, stroke volume, left ventricular (LV) dP/dt, and hematocrit were measured before and after intravenous injection of VEGF in conscious, instrumented rats. VEGF caused a dose-dependent reduction in MAP and an associated increase in HR. VEGF (250 micrograms/kg) significantly decreased cardiac output and stroke volume without affecting the inotropic state of the left ventricle, as determined by dP/dt. VEGF significantly increased hematocrit. Furthermore, VEGF did not affect contractility or HR in the isolated rat heart in vitro. The data suggest that the VEGF-induced decrease in cardiac output is due to reduced stroke volume, which may be caused by a decrease in venous return rather than a direct effect on myocardial contractility. In addition, pretreatment with N omega-nitro-L-arginine methyl-ester (L-NAME), a nitric oxide (NO) synthase inhibitor, significantly attenuated the depressor and tachycardic responses to VEGF, suggesting that VEGF-induced hypotension may be mediated by NO.

Animals↗
PubMed1996

Vascular endothelial growth factor, a specific regulator of angiogenesis.

Vascular endothelial growth factor is a diffusible endothelial cell-specific mitogen and angiogenic factor that can also increase vascular permeability. The vascular endothelial growth factor receptors are specifically expressed on the cell surface of vascular endothelial cells. Recent studies point to vascular endothelial growth factor as a major regulator of physiological angiogenesis, such as developmental and reproductive angiogenesis. In addition vascular endothelial growth factor appears to be a crucial mediator of blood vessel growth associated with tumors and proliferative retinopathies. Antivascular endothelial growth factor antibodies have the ability to suppress the growth of a variety of tumor cell lines in nude mice and can also inhibit angiogenesis in animal models of intra-ocular neovascularization. Furthermore vascular endothelial growth factor administration promotes collateral vessel growth and results in functional improvement in animal models of coronary or limb ischemia.

Animals↗
PubMed1996

Ovarian steroid regulation of vascular endothelial growth factor in the human endometrium: implications for angiogenesis during the menstrual cycle and in the pathogenesis of endometriosis.

The human endometrium undergoes a complex process of vascular and glandular proliferation, differentiation, and regeneration with each menstrual cycle in preparation for implantation. Vascular endothelial growth factor (VEGF) is an endothelial cell-specific angiogenic protein that appears to play an important role in both physiological and pathological neovascularization. To investigate whether VEGF may regulate human endometrial angiogenesis, we examined VEGF messenger ribonucleic acid (mRNA) and protein throughout the menstrual cycle and studied the regulation of VEGF by reproductive steroids in isolated human endometrial cells. By ribonuclease protection analysis, VEGF mRNA increased relative to early proliferative phase expression by 1.6-,2.0-, and 3.6-fold in midproliferative, late proliferative, and secretory endometrium, respectively. In histological sections, VEGF mRNA and protein were localized focally in glandular epithelial cells and more diffusely in surrounding stroma, with greatest VEGF expression in secretory endometrium. Consistent with these in vivo results, the treatment of isolated human endometrial cells with estradiol (E2), medroxyprogesterone acetate (MPA), or E2 plus MPA significantly increased VEGF mRNA expression over the control value by 3.1-, 2.8-, and 4.7-fold, respectively. The VEGF response to E2 was rapid, with steady state levels of VEGF mRNA reaching 85% maximum 1 h after the addition of steroid. E2 also caused a 46% increase in secreted VEGF protein, and the combination of E2 and MPA caused an 18% increase. VEGF expression in endometriosis, an angiogenesis-dependent, estrogen-sensitive disease was similar to that seen in eutopic endometrium. Peritoneal fluid concentrations of VEGF were significantly higher in women with moderate to severe endometriosis than in women with minimal to mild endometriosis or no disease. VEGF, therefore, may be important in both physiological and pathological angiogenesis of human endometrium, as it is an estrogen-responsive angiogenic factor that varies throughout the menstrual cycle and is elevated in women with endometriosis.

Cells, Cultured↗
PubMed1996

Effects of age on the role of atrial natriuretic factor in renal adaptation to physiologic variations of dietary salt intake.

The effects of normal, low, and high dietary salt intake on basal atrial natriuretic factor plasma levels, plasma renin activity, and aldosterone were evaluated in seven young (Group 1), seven middle-aged (Group 2), and seven elderly healthy volunteers (Group 3). In all subjects, progressively higher doses of human alpha-atrial natriuretic factor were infused at low-sodium diet conditions to obtain hormone plasma values during infusion similar to those obtained in the same subjects at high-sodium diet conditions. Atrial natriuretic factor plasma values were significantly higher in Group 3 than in the other two groups at both normal- and high-salt diet conditions, and at all steps of the infusion study. At low-sodium diet conditions, peptide concentrations averaged 23.2 +/- 6.2 in Group 3, 26.2 +/- 1.9 in Group 2, and 19.1 +/- 3.9 pg/mL in Group 1 (P = not significant between groups). Hormone plasma values at high-salt diet conditions averaged 47 +/- 6.9 pg/mL in Group 1, 60 +/- 6.5 pg/mL in Group 2, and 136.3 +/- 14.6 pg/mL in Group 3. Each value was not significantly different from the corresponding value gained at an infusion step of 2 ng/min per kg in Group 1 and 2 (57.1 +/- 11.9 and 62.7 +/- 6.5 pg/mL, respectively), and of 1 ng/min per kg (139.1 +/- 22.2 pg/mL) in Group 3. At these infusion steps and at high-salt diet conditions, the urinary sodium excretion rate was, respectively, 0.185 +/- 0.02 and 0.311 +/- 0.02 mEq/min in Group 1, 0.168 +/- 0.01 and 0.300 +/- 0.02 mEq/min in Group 2, and 0.110 +/- 0.01 and 0.256 +/- 0.01 mEq/min in Group 3. Hormone infusion induced a progressive fall of plasma renin activity and aldosterone level in all groups. By experimentally increasing plasma concentrations of atrial natriuretic factor in a low-salt diet condition to the levels occurring physiologically in a high-salt diet condition, a significant rise in urinary sodium excretion rate is evoked, which accounts for 52% in young, 47% in middle-aged, and 30% in older subjects of the rise that is necessary to balance the increased salt intake.

Adaptation, Physiological↗
PubMed1996

Hypoxia regulates vascular endothelial growth factor receptor KDR/Flk gene expression through adenosine A2 receptors in retinal capillary endothelial cells.

PURPOSE: Vascular endothelial growth factor (VEGF) is an endothelial cell-specific angiogenic factor that serves an important role in numerous ischemic retinopathies. The authors studied the hypoxic gene regulation of two known VEGF receptors (KDR and Flt) and its mechanism in cultured bovine retinal endothelial cells (BREC). METHODS: Confluent monolayers of BREC were exposed to various oxygen concentrations using a computer-controlled, infrared, water-jacked CO2 incubator with reduced oxygen control. Northern blot analysis and 125I-VEGF binding analysis were used to identify hypoxia-induced alterations of VEGF receptor at mRNA and protein levels. RESULTS: KDR was detectable by Northern blot analysis in BREC, whereas Flt was not. Hypoxia decreased KDR gene expression in a dose-and time-dependent manner with maximal inhibition to 0.5 +/- 0.2% (P = 0.019) of normoxic control observed after 24 hours exposure to 0% oxygen and with significant inhibition at oxygen concentrations below 5%. Blockade of oxygen respiration decreased KDR mRNA expression to 58% +/- 7.1% of control (P = 0.001) after 3 hours. CPA, a stable adenosine A1 receptor (A1R) agonist, did not affect KDR mRNA expression at A1R stimulatory concentrations, but it decreased KDR mRNA levels to 30% +/- 4.9% (P = 0.002) of control at higher concentrations that react with A2R. DPMA, an adenosine A2 receptor (A2R) agonist, decreased KDR mRNA in a dose-dependent manner with an EC50 of 5 to 10 nM. A1R antagonists, 8-cyclolentyl-1,3-dipropylxanthine and 8-phenyltheophylline, did not inhibit the hypoxic response of KDR mRNA at A1R inhibitory concentrations but did inhibit the response at A2R effective doses (P = 0.001). The A2R antagonist, CSC, inhibited the KDR hypoxic response by 42% +/- 7.8% (P = 0.008) at 10 microM. Specific VEGF binding to BREC was decreased from 15.1% +/- 0.3% to 12.7% +/- 0.4% per milligram protein (P < 0.001) after exposure to 1% oxygen for 24 hours. In contrast, long-term exposure to 1% oxygen (72 hours) resulted in an increase of VEGF binding from 13.5% +/- 1.1% to 18.3% +/- 0.8% per milligram protein (P < 0.001). Scatchard analysis detected a decrease of receptor binding sites without change in binding affinity after 30 hours of exposure to hypoxia but demonstrated an increase in specific binding sites (4.2 +/- 0.6 x 10(4) sites/cell to 6.7 +/- 1.0 x 10(4) sites/cell, P = 0.049) with unaltered receptor affinity after 72 hours of hypoxic exposure. CONCLUSIONS: These data suggest that hypoxia induces an initial decline in KDR mRNA levels and VEGF binding sites as mediated through adenosine binding to the A2R. Exposure to prolonged periods of hypoxia, however, results in an increase in VEGF binding sites by an as yet unidentified mechanism.

Adenosine↗
PubMed1996

The in vivo bioactivity of vascular endothelial growth factor/vascular permeability factor is independent of N-linked glycosylation.

The carbohydrate moieties of glycoprotein hormones or growth factor molecules may have a variety of effects that impact biological potency. Vascular endothelial growth factor (VEGF), also known as vascular permeability factor (VPF), is a 45 kD heparin-binding, endothelial cell (EC) specific mitogen with a putative N-linked glycosylation site. Recent studies have shown that VEGF/VPF may successfully augment collateral development in animal models of myocardial and hindlimb ischemia. The extent to which glycosylation of the 75 asparagine site affects the angiogenic properties of VEGF/VPF has not been studied in vivo. Specifically unaddressed to date is the concern that nonglycosylated VEGF/VPF may be less stable, and therefore characterized by a shorter half-life, reducing its utility for therapeutic angiogenesis. Accordingly, the purpose of this study was to investigate the extent to which posttranslational modification, specifically glycosylation, mofies the angiogenic properties of VEGF/VPF in vivo. Glycosylated (g+) recombinant human VEGF165 was purified from media conditioned by Chinese hamster ovary (CHO) cells. Nonglycosylated (g-) VEGF165 was expressed, purified and refolded from E. coli. The purity of both materials was assessed by silver-stained SDS/PAGE and characterized by the presence of a single amino terminal sequence as indicated by Edman degradation. Tryptic mapping by reverse-phase HPLC confirmed that the potential glycosylation site at 75 asparagine was occupied by N-linked carbohydrate for the Chinese hamster ovary-derived VEGF/VPF, but not for E. coli-derived VEGF/VPF. The mitogenic effects of Chinese hamster ovary-derived (g+) VEGF165 and E. coli-derived (g-) VEGF165 wre studied in vitro using microvascular EC. At concentrations of VEGF/VPF ranging from 10(-4) to 10(2) nM, both produced similar concentration-dependent effects on EC proliferation. For in vivo studies, (g-) (n = 8) and (g+) (n = 8) formulations of VEGF/VPF were administered to New Zealand white rabbits with unilateral hindlimb ischemia. For (g-) versus (g+) VEGF/VPF-treated groups, respectively, calf blood pressure ratio was 0.40 +/- 0.04 versus 0.37 +/- 0.04; angiographic score (of collateral vessels) was 0.37 +/- 0.04 versus 0.35 +/- 0.04; capillary density (capillaries/mm2) at necropsy was 246.9 +/- 21.5 versus 253.9 +/- 18.8; and tissue perfusion (colored microspheres) was 92.8 +/- 5.5 versus 90.30 +/- 13.47 (all p = ns). Moreover, intravascular Doppler-based analyses of resting, maximum, and endothelium-dependent flow was similar for (g-) and (g+) VEGF/VPF. These in vitro and in vivo findings establish that the potential for VEGF/VPF to stimulate therapeutic angiogenesis persists unaltered in the nonglycosylated state.

Angiography↗
PubMed1996

Adenosine mediates hypoxic induction of vascular endothelial growth factor in retinal pericytes and endothelial cells.

PURPOSE: To determine the mechanistic role for adenosine and adenosine receptors in the hypoxic induction of vascular endothelial growth factor (VEGF) in retinal microvascular cells. METHODS: Bovine retinal capillary endothelial cells and microvascular pericytes were studied under normoxic (95% air, 5% CO2) or hypoxic conditions (0% to 2% O2, 5% CO2, 93% to 95% N2) using a variety of well-characterized adenosine and adenosine receptor agonists and antagonists. Vascular endothelial growth factor mRNA expression was evaluated by Northern blot analysis, VEGF protein levels were determined by Western blot analysis, and cyclic adenosine monophosphate (cAMP) accumulation was measured by radioimmunoassay. RESULTS: Inhibitors of oxidative respiration increased VEGF mRNA 5 +/- 3 times (P < 0.001) after 3 hours. Adenosine A1 receptor (A1R) agonist N6-cyclopentyl-adenosine did not increase VEGF mRNA at A1R stimulatory concentrations; however, adenosine A2 receptor (A2R) agonists DPMA, NECA, and CGS21680 increased VEGF mRNA in a dose-dependent manner with elevations of 2 +/- 0.3 (P < 0.001), 2.3 +/- 0.5 (P = 0.016), and 2 +/- 0.2 (P = 0.002) times, respectively. A2R antagonist CSC and adenosine degradation by adenosine deaminase reduced hypoxic stimulation of VEGF mRNA 68% +/- 18% (P = 0.038) and 37% +/- 6% (P = 0.025), respectively, in a dose-dependent manner. A1R antagonists DPCPX and 8-PT had no significant effect. Hypoxia and NECA increased VEGF protein secretion 4.7 times, whereas CSC inhibited hypoxia-induced VEGF protein secretion by 96%. NECA and CGS21680 increased cAMP production within 10 minutes, and cAMP stimulation increased VEGF mRNA 4.8 +/- 2.6 times (P = 0.034). CSC suppressed the hypoxic elevation of cAMP (P < 0.05). Inhibition of protein kinase A using H-89 reduced hypoxia-induced VEGF expression 61% +/- 6.3% (P = 0.043) in a dose-dependent manner. CONCLUSIONS: These data suggest that the hypoxia-induced accumulation of adenosine stimulates VEGF gene expression through stimulation of adenosine A2a receptor and subsequent activation of the cAMP-dependent protein kinase A pathway in retinal vascular cells.

Adenosine↗
PubMed1996

Beta-adrenoceptor function changes with age of subject in myocytes from non-failing human ventricle.

The contractile response to beta-adrenoceptor stimulation has been found to be reduced in single myocytes from failing human ventricle. A portion of that reduction was statistically related to the age of the patient. We have developed a method for obtaining viable contracting myocytes from small biopsies of human ventricle, enabling experiments to be performed on non-failing left ventricle from patients undergoing coronary artery surgery. These subjects are generally in an older age range than those we have previously obtained from donor hearts. The present study compares responses to isoproterenol and high Ca2+ between myocytes from older (> 50 years, n = 8) and younger (< 40 years, n = 5) subjects. Myocytes from older patients did not differ in their contraction amplitude (10.7 +/- 1.0 cf. 10.8 +/- 1.1% cell shortening), or contraction and relaxation velocities in high Ca2+ at a driving frequency of 0.2 Hz (32 degrees C). The sensitivity to isoproterenol, as determined from the EC50 value (concentration for half-maximal effect), was also similar between age groups (1.16 +/- 0.64 nM young, cf. 2.76 +/- 2.0 nM old), although higher than in myocytes from failing hearts (22.3 +/- 7.5 nM, n = 11). However, for the older group there was a significant depression in maximum contraction amplitude with isoproterenol (8.5 +/- 0.6 cf. 11.5 +/- 1.0% cell shortening, P < 0.05) and in the ratio between this and the maximum Ca2+ response (isoproterenol/Ca2+ ratio, 0.79 +/- 0.05 cf. 1.16 +/- 0.12, P < 0.05). Concomitantly, the maximum contraction and relaxation velocities achieved in the presence of isoproterenol were also depressed in older subjects (P < 0.02 for both). We conclude that age and/or coronary disease with unimpaired left ventricular function selectively reduces the maximum effect of isoproterenol but not the concentration at which this occurs.

Adrenergic beta-Agonists↗
PubMed1996

Gene transfer of naked DNA encoding for three isoforms of vascular endothelial growth factor stimulates collateral development in vivo.

Vascular endothelial growth factor (VEGF) is a naturally secreted endothelial cell-specific mitogen. We investigated the hypothesis that naked DNA encoding for VEGF could be used in a strategy of arterial gene therapy to stimulate collateral artery development. Plasmid DNA encoding each of the three principal human VEGF isoforms (phVEGF121, phVEGF165, or phVEGF189) was applied to the hydrogel polymer coating of an angioplasty balloon and delivered percutaneously to one iliac artery of rabbits with operatively induced hindlimb ischemia. Compared with control animals transfected with LacZ, site-specific transfection of phVEGF resulted in augmented collateral vessel development documented by serial angiography, and improvement in calf blood pressure ratio (ischemic to normal limb), resting and maximum blood flow, and capillary to myocyte ratio. Similar results were obtained with phVEGF121, phVEGF165, and phVEGF189, which suggests that these isoforms are biologically equivalent with respect to in vivo angiogenesis. The fact that viral or other adjunctive vectors were not required further suggests that secreted gene products may have potential therapeutic utility even when the number of successfully transfected cells remains low. Arterial gene transfer of naked DNA encoding for a secreted angiogenic cytokine, thus, represents a potential alternative to recombinant protein administration for stimulating collateral vessel development.

Animals↗
PubMed1996

Non-insulin-dependent diabetes mellitus is associated with a greater prevalence of depression in the elderly. The Osservatorio Geriatrico of Campania Region Group.

We investigated the association of non-insulin-dependent (Type 2) diabetes mellitus and depression symptoms in a representative community-dwelling elderly population independently of other conditions such as gender, age, status, disability, cognitive impairment and a number of chronic medical conditions such as chronic obstructive lung disease, degenerative joint disease, heart disease, cirrhosis of the liver, cholelithiasis, peptic ulcer and kidney stones. A total of 1339 elderly subjects living in southern Italy were randomly selected from electoral rolls and evaluated. All subjects were tested by the Geriatric Depression Scale to detect depression, the Mini-Mental State Examination to study cognitive function and the Activity Daily Living Index to evaluate disability. Non-insulin-dependent diabetes mellitus affected 14.7% of our sample. Depression was more prevalent in women over 75 years of age than in younger women (15.9 vs 8.1%, p < 0.001). In multiple linear regression analysis, diabetes mellitus was found to be significantly associated with depression independently of age, gender, loneliness, cognitive impairment, chronic obstructive lung disease, degenerative joint disease, heart diseases, cancer, kidney disease, cirrhosis of the liver and cholelithiasis. It is concluded that non-insulin-dependent diabetes mellitus is significantly associated with depression in the elderly, which may have clinical implications for the achievement of sufficient blood glucose control.

Aged↗
PubMed1996

Some considerations about the "Fibrolipocalcareous myopathy" (Mattioli-Foggia and Raso disease).

Fibrolipocalcareous myopathy also known as Mattioli-Foggia and Raso Disease was observed first time in 1945. They described clinical, anatomopathologic and radiological Bigliardi aspects. At present the published cases are more than forty. We have pointed out our attention on the published cases. We believe, regard to histopathological and whole clinical data, that this disease could be considered as a) the outcome of a vascular hamartoma; or b) the consequence of a "mesoblastic phacomatosis".

Adipose Tissue↗
PubMed1995

Suppression of retinal neovascularization in vivo by inhibition of vascular endothelial growth factor (VEGF) using soluble VEGF-receptor chimeric proteins.

The majority of severe visual loss in the United States results from complications associated with retinal neovascularization in patients with ischemic ocular diseases such as diabetic retinopathy, retinal vein occlusion, and retinopathy of prematurity. Intraocular expression of the angiogenic protein vascular endothelial growth factor (VEGF) is closely correlated with neovascularization in these human disorders and with ischemia-induced retinal neovascularization in mice. In this study, we evaluated whether in vivo inhibition of VEGF action could suppress retinal neovascularization in a murine model of ischemic retinopathy. VEGF-neutralizing chimeric proteins were constructed by joining the extracellular domain of either human (Flt) or mouse (Flk) high-affinity VEGF receptors with IgG. Control chimeric proteins that did not bind VEGF were also used. VEGF-receptor chimeric proteins eliminated in vitro retinal endothelial cell growth stimulation by either VEGF (P < 0.006) or hypoxic conditioned medium (P < 0.005) without affecting growth under nonstimulated conditions. Control proteins had no effect. To assess in vivo response, animals with bilateral retinal ischemia received intravitreal injections of VEGF antagonist in one eye and control protein in the contralateral eye. Retinal neovascularization was quantitated histologically by a masked protocol. Retinal neovascularization in the eye injected with human Flt or murine Flk chimeric protein was reduced in 100% (25/25; P < 0.0001) and 95% (21/22; P < 0.0001) 0.0001) of animals, respectively, compared to the control treated eye. This response was evident after only a single intravitreal injection and was dose dependent with suppression of neovascularization noted after total delivery of 200 ng of protein (P < 0.002). Reduction of histologically evident neovascular nuclei per 6-microns section averaged 47% +/- 4% (P < 0.001) and 37% +/- 2% (P < 0.001) for Flt and Flk chimeric proteins with maximal inhibitory effects of 77% and 66%, respectively. No retinal toxicity was observed by light microscopy. These data demonstrate VEGF's causal role in retinal angiogenesis and prove the potential of VEGF inhibition as a specific therapy for ischemic retinal disease.

Animals↗
PubMed1995

Synergistic effect of vascular endothelial growth factor and basic fibroblast growth factor on angiogenesis in vivo.

BACKGROUND: Recent studies have suggested that vascular endothelial growth factor (VEGF) and basic fibroblast growth factor (bFGF) may have synergistic effects on the induction of angiogenesis in vitro. Therefore, we investigated the hypothesis that the simultaneous administration of VEGF and bFGF, each having been previously shown to independently enhance collateral development in an animal model of hind limb ischemia, could have a synergistic effect in vivo. METHODS AND RESULTS: Ten days after surgical induction of unilateral hind limb ischemia, New Zealand White rabbits were randomized to receive either VEGF 500 micrograms alone (n = 6), bFGF 10 micrograms alone (n = 7), VEGF 500 micrograms, immediately followed by 10 micrograms bFGF (n = 7), or vehicle only (control animals, n = 8) in each case administered intra-arterially via a catheter in the internal iliac artery of the ischemic limb. BP ratio (BPR, ischemic/healthy limb) at day 10 for the VEGF+bFGF group was 0.82 +/- 0.01, much superior (P < .0005) to that of either the VEGF group (0.52 +/- 0.02) or the bFGF group (0.57 +/- 0.02). This outcome persisted at day 30: BPR in the VEGF+bFGF group (0.91 +/- 0.02) exceeded that of the control group (0.49 +/- 0.05, P < .0001), the VEGF group (0.65 +/- 0.03, P < .0005), or the bFGF group (0.66 +/- 0.03, P < .0005). Serial angiography demonstrated a progressive increase in luminal diameter of the stem collateral artery and the number of opacified collaterals in the thigh of the ischemic limbs in all groups. Stem artery diameter with VEGF+bFGF (1.34 +/- 0.07 mm) on day 30 was significantly (P < .05) greater than with either VEGF (1.09 +/- 0.09) or bFGF (1.18 +/- 0.06) alone. Capillary density was significantly greater (P < .05) in VEGF+bFGF animals (275 +/- 20 mm2) compared with VEGF (201 +/- 8) or bFGF (209 +/- 15). CONCLUSIONS: Combined administration of VEGF and bFGF stimulates significantly greater and more rapid augmentation of collateral circulation, resulting in superior hemodynamic improvement compared with either VEGF or bFGF alone. This synergism of two angiogenic mitogens with different target cell specificities may have important implications for the treatment of severe arterial insufficiency in patients whose disease is not amenable to direct revascularization.

Angiography↗
PubMed1995

Failure of protective effect of captopril and enalapril on exercise and dipyridamole-induced myocardial ischemia.

Fifteen patients with angiographic evidence of significant coronary artery disease, exertional myocardial ischemia, and positive dipyridamole echocardiographic test results at basal conditions and after 7 days of placebo treatment were prospectively studied to see whether captopril (containing sulfhydryl) and enalapril (nonsulfhydryl) modify myocardial ischemia induced by exercise testing and the effects of dipyridamole echocardiographic testing on regional myocardial contractility. Patients were randomized to captopril (150 mg/day in 3 separate doses) or enalapril (20 mg/day) for 1 week. At the end of this period each patient crossed over to the alternate regimen after a washout period of 7 days. Exercise stress testing and dipyridamole echocardiographic testing were repeated at the end of each treatment period. Neither captopril nor enalapril had a significantly greater anti-ischemic effect than placebo in any patient. Exercise duration, time to onset of ST-segment depression, maximal workload, degree of ST-segment depression, and rate-pressure product were not affected by either drug. Neither captopril nor enalapril improved dipyridamole-induced mechanical dysfunction or ST-segment depression.

Adult↗