Biomedical subjects

Gennaro Galasso

Publications and source records attributed to Gennaro Galasso.

10 recordsLinked to original sources

PubMed2006

Microarray analysis of Akt1 activation in transgenic mouse hearts reveals transcript expression profiles associated with compensatory hypertrophy and failure.

To investigate molecular mechanisms involved in the development of cardiac hypertrophy and heart failure, we developed a tetracycline-regulated transgenic system to conditionally switch a constitutively active form of the Akt1 protein kinase on or off in the adult heart. Short-term activation (2 wk) of Akt1 resulted in completely reversible hypertrophy with maintained contractility. In contrast, chronic Akt1 activation (6 wk) induced extensive cardiac hypertrophy, severe contractile dysfunction, and massive interstitial fibrosis. The focus of this study was to create a transcript expression profile of the heart as it undergoes reversible Akt1-mediated hypertrophy and during the transition from compensated hypertrophy to heart failure. Heart tissue was analyzed before transgene induction, 2 wk after transgene induction, 2 wk of transgene induction followed by 2 days of repression, 6 wk after transgene induction, and 6 wk of transgene induction followed by 2 wk of repression. Acute overexpression of Akt1 (2 wk) leads to changes in the expression of 826 transcripts relative to noninduced hearts, whereas chronic induction (6 wk) led to changes in the expression of 1,611, of which 65% represented transcripts that were regulated during the pathological phase of heart growth. Another set of genes identified was uniquely regulated during heart regression but not growth, indicating that nonoverlapping transcription programs participate in the processes of cardiac hypertrophy and atrophy. These data define the gene regulatory programs downstream of Akt that control heart size and contribute to the transition from compensatory hypertrophy to heart failure.

Animals↗

PubMed2005

Impaired angiogenesis in glutathione peroxidase-1-deficient mice is associated with endothelial progenitor cell dysfunction.

Several vascular disease are characterized by elevated levels of reactive oxygen species (ROS). Vascular endothelium is protected from oxidant stress by expressing enzymes such as glutathione peroxidase type 1 (GPx-1). In this study, we investigated the effect of vascular oxidant stress on ischemia-induced neovascularization in a murine model of homozygous deficiency of GPx-1. GPx-1-deficient mice showed impaired revascularization following hindlimb ischemic surgery based on laser Doppler measurements of blood flow and capillary density in adductor muscle. GPx-1-deficient mice also showed an impaired ability to increase endothelial progenitor cell (EPC) levels in response to ischemic injury or subcutaneous administration of vascular endothelial growth factor protein. EPCs isolated from GPx-1-deficient mice showed a reduced ability to neutralize oxidative stress in vitro, which was associated with impaired migration toward vascular endothelial growth factor and increased sensitivity to ROS-induced apoptosis. EPCs isolated from GPx-1-deficient mice were impaired in their ability to promote angiogenesis in wild-type mice, whereas wild-type EPCs were effective in stimulating angiogenesis in GPx-1-deficient mice. These data suggest that EPC dysfunction is a mechanism by which elevated levels of ROS can contribute to vascular disease.

Animals↗

PubMed2005

Ischemic neoangiogenesis enhanced by beta2-adrenergic receptor overexpression: a novel role for the endothelial adrenergic system.

Beta2-adrenergic receptors (beta2ARs) are widely expressed, although their physiological relevance in many tissues is not yet fully understood. In vascular endothelial cells, they regulate NO release and vessel tone. Here we provide novel evidence that beta2ARs can regulate neoangiogenesis in response to chronic ischemia. We used in vivo adenoviral-mediated gene transfer of the human beta2AR to the endothelium of the rat femoral artery and increased beta2AR signaling resulting in ameliorated angiographic blood flow and hindlimb perfusion after chronic ischemia. Histological analysis confirmed that beta2AR overexpression also produced benefits on capillary density. The same maneuver partially rescued impaired angiogenesis in spontaneously hypertensive rats (SHR), whereas gene delivery of the G-protein-coupling defective mutant Ile164 beta2AR failed to provide ameliorations. Stimulation of endogenous and overexpressed beta2AR on endothelial cells in vitro was found to regulate cell number by inducing proliferation and [3H]-thymidine incorporation through means of extracellular receptor-activated kinase and vascular endothelial growth factor. The beta2AR also has novel effects on endothelial cell number through stimulation of proapoptosis and antiapoptosis pathways involving p38 mitogen-activated protein kinase and PI3-kinase/Akt activation. Therefore, beta2ARs play a critical role in endothelial cell proliferation and function including revascularization, suggesting a novel and physiologically relevant role in neoangiogenesis in response to ischemia.

Animals↗

PubMed2005

Impaired revascularization in a mouse model of type 2 diabetes is associated with dysregulation of a complex angiogenic-regulatory network.

OBJECTIVE: Diabetes is a risk factor for the development of cardiovascular diseases associated with impaired angiogenesis or increased endothelial cell apoptosis. METHODS AND RESULTS: Here it is shown that angiogenic repair of ischemic hindlimbs was impaired in Lepr(db/db) mice, a leptin receptor-deficient model of diabetes, compared with wild-type (WT) C57BL/6 mice, as evaluated by laser Doppler flow and capillary density analyses. To identify molecular targets associated with this disease process, hindlimb cDNA expression profiles were created from adductor muscle of Lepr(db/db) and WT mice before and after hindlimb ischemia using Affymetrix GeneChip Mouse Expression Set microarrays. The expression patterns of numerous angiogenesis-related proteins were altered in Lepr(db/db) versus WT mice after ischemic injury. These transcripts included neuropilin-1, vascular endothelial growth factor-A, placental growth factor, elastin, and matrix metalloproteinases implicated in blood vessel growth and maintenance of vessel wall integrity. CONCLUSIONS: These data illustrate that impaired ischemia-induced neovascularization in type 2 diabetes is associated with the dysregulation of a complex angiogenesis-regulatory network.

Animals↗

PubMed2005

Role of beta2 adrenergic receptors in human atherosclerotic coronary arteries.

BACKGROUND: Adrenergic regulation of coronary vasomotion is balanced between alpha1-adrenergic-mediated (alpha1-AR) constriction and beta2-adrenergic-mediated (beta2-AR) relaxation. This study aimed at assessing the role of beta2-ARs in normal, mildly atherosclerotic, and stenotic human coronary arteries. METHODS AND RESULTS: During intracoronary (IC) infusion of increasing doses of the beta2-AR agonist salbutamol (0.15, 0.3, and 0.6 mug/min) and the endothelial vasodilator acetylcholine (1, 3, and 10 microg/min), we measured (1) changes in lumen diameter (LD) by quantitative coronary angiography in 34 normal, 55 mildly atherosclerotic, and 42 stenotic coronary artery segments and (2) changes in average peak velocity (APV) and coronary blood flow (CBF) with the use of Doppler flow wire in 11 normal, 10 mildly atherosclerotic, and 11 stenotic coronary arteries. In 6 of 11 stenotic coronary arteries, the protocol was repeated after an IC bolus (12 microg/kg) of the alpha-adrenergic blocker phentolamine. In 6 of 11 normal coronary arteries, the protocol was repeated after an IC infusion (60 micromol/min) of N(G)-monomethyl-L-arginine (L-NMMA), a nitric oxide inhibitor. Neither salbutamol IC infusion nor acetylcholine significantly changed heart rate or blood pressure, whereas L-NMMA slightly increased blood pressure. In normal coronary arteries, salbutamol increased LD (LD max %: 11+/-2, P<0.05), APV (APV max %: 53+/-17, P<0.05), and CBF (CBF max %: 57+/-17, P<0.05), whereas L-NMMA caused a blunted APV (APV max %: 27+/-6, P<0.05) and CBF (CBF max %: 29+/-6, P<0.05) response to salbutamol. In mildly atherosclerotic coronary arteries, the salbutamol increase in LD (LD max %: 10+/-2, P<0.05), APV (APV max %: 33+/-12, P<0.05), and CBF (CBF max %: 37+/-12, P<0.05) was preserved. In stenotic coronary arteries, salbutamol induced a paradoxical reduction in LD (LD max %: -6+/-2, P<0.05), APV (APV max %: -15+/-9, P<0.05), and CBF (CBF max %: -15+/-6, P<0.05), which was no longer observed after phentolamine. Acetylcholine increased LD (LD max %: 14+/-3, P<0.05), APV (APV max %: 61+/-20, P<0.05), and CBF (CBF max %: 67+/-19, P<0.05) in normal coronary arteries. In mildly atherosclerotic coronary arteries, acetylcholine induced a significant reduction in LD (LD max %: -15+/-2, P<0.05) and no changes in APV (APV max %: -6+/-13, P=NS) and CBF (CBF max %: -10+/-13, P=NS). In stenotic coronary arteries, acetylcholine significantly reduced LD (LD max %: -15+/-3, P<0.05), APV (APV max %: -15+/-9, P<0.05), and CBF (CBF max %: -15+/-6, P<0.05). CONCLUSIONS: In severely atherosclerotic coronary arteries, beta2-adrenergic vasodilatation is impaired, and this might contribute to alter the vasomotor balance, further precipitating myocardial ischemia during sympathetic activation.

Acetylcholine↗

PubMed2005

Akt1/protein kinase Balpha is critical for ischemic and VEGF-mediated angiogenesis.

Akt, or protein kinase B, is a multifunctional serine-threonine protein kinase implicated in a diverse range of cellular functions including cell metabolism, survival, migration, and gene expression. However, the in vivo roles and effectors of individual Akt isoforms in signaling are not explicitly clear. Here we show that the genetic loss of Akt1, but not Akt2, in mice results in defective ischemia and VEGF-induced angiogenesis as well as severe peripheral vascular disease. Akt1 knockout (Akt1-/-) mice also have reduced endothelial progenitor cell (EPC) mobilization in response to ischemia, and reintroduction of WT EPCs, but not EPCs isolated from Akt1-/- mice, into WT mice improves limb blood flow after ischemia. Mechanistically, the loss of Akt1 reduces the basal phosphorylation of several Akt substrates, the migration of fibroblasts and ECs, and NO release. Reconstitution of Akt1-/- ECs with Akt1 rescues the defects in substrate phosphorylation, cell migration, and NO release. Thus, the Akt1 isoform exerts an essential role in blood flow control, cellular migration, and NO synthesis during postnatal angiogenesis.

Animals↗

PubMed2003

Increased inflammatory status and higher prevalence of three-vessel coronary artery disease in patients with concomitant coronary and peripheral atherosclerosis.

The aim of this study was to determine whether patients with coronary artery disease (CAD) and concomitant peripheral arterial disease (PAD) have a greater inflammatory status than those with CAD alone. To this aim, we evaluated PAD (ankle/brachial pressure index <0.9), and measured plasma levels of C-reactive protein (CRP), interleukin-6 (IL-6) and the soluble forms of intercellular adhesion molecule-1 (sICAM-1) and vascular cell adhesion molecule-1 (sVCAM-1) in 234 patients who underwent coronary angiography. Median levels of CRP, IL-6 and sICAM-1 were higher in the CAD without PAD (n=134) and CAD+PAD (n=40) groups than in 60 patients without either disease ("controls"). Median CRP values were higher in patients with CAD+PAD than in patients with CAD alone (4.7 mg/L [1.5; 7.6] vs 2.4 mg/L [0.9; 3.8], p < 0.01).Three-vessel CAD was diagnosed in 60% of CAD+PAD patients and in 21% (p< 0.01) of CAD only patients. After adjustment for confounding factors, only PAD was independently associated with three-vessel CAD (p<0.001). This association was maintained after adjustment for IL-6, the only inflammatory parameter significantly associated with three-vessel CAD at univariate analysis (p<0.01). In conclusion, in CAD the coexistence of PAD is associated with a greater inflammatory status and more widespread coronary atherosclerosis. These results could help to explain the high cardiovascular risk of patients with concomitant CAD and PAD and suggest that PAD be included among the variables used to identify CAD patients for further diagnostic evaluation.

Aged↗

PubMed2002

Immediate and long-term outcome of recanalization of chronic total coronary occlusions.

Eighty-three consecutive patients with 85 coronary total occlusions undergoing coronary angioplasty were retrospectively studied. Patients were divided into two groups according to the occlusion age that was < 30 days (subacute total occlusion [STO]: 25 patients; range 1-30 days) or > 30 days (chronic total occlusion [CTO]: 58 patients; range 3-144 months). All procedures were carried out using a hydrophilic guidewire. Clinical success, consisting of crossing the lesion, balloon dilatation, stent deployment without complications, was 96% in STO and 81% in CTO. Multiple stepwise logistic regression analysis identified a family history of coronary artery disease (CAD), left anterior descending and right coronary artery occlusions as independent predictors of a successful procedure. No major events occurred during or immediately after the angioplasty. After a mean follow-up of 24 +/- 2 months, no difference was found in survival or freedom from myocardial infarction or target vessel revascularization among the STO and CTO patients. Successful recanalization by using a hydrophilic guidewire was achieved in a high percentage of chronic total occlusions with a low incidence of complications and a satisfactory late clinical outcome. Family history of CAD and occlusion of left anterior descending or right coronary arteries are independent predictors of procedural success.

Aged↗

PubMedDate not supplied

Estimation of coronary flow reserve by Tc-99m sestamibi imaging in patients with coronary artery disease: comparison with the results of intracoronary Doppler technique.

BACKGROUND: This study compared coronary flow reserve (CFR) estimated by technetium 99m sestamibi imaging with the results obtained with intracoronary Doppler in patients with coronary artery disease. Intraobserver and interobserver reproducibility of the radionuclide-estimated CFR was also assessed. METHODS AND RESULTS: Fourteen consecutive patients (mean age, 54 +/- 7 years) with documented coronary artery disease in whom percutaneous coronary intervention was planned underwent dipyridamole (0.74 mg/kg) sestamibi imaging and intracoronary Doppler within 5 days. Myocardial blood flow (MBF) was estimated by measurement of first transit counts in the pulmonary artery and myocardial counts from single photon emission computed tomography images. Estimated CFR was expressed as the ratio of stress MBF to rest MBF. In the study vessels, CFR was 1.36 +/- 0.43 as estimated by sestamibi and 1.39 +/- 0.42 by intracoronary Doppler ( P = .69). A significant relationship between CFR estimated by sestamibi and CFR obtained by intracoronary Doppler was observed ( r = 0.85, P < .001). On Bland-Altman analysis, the mean difference between CFR by sestamibi and by Doppler was 0.03 and the intraclass correlation coefficients for intraobserver and interobserver reproducibility were high (all P < .001) for both global and regional CFR. CONCLUSIONS: This study demonstrates a good agreement between CFR estimated by sestamibi imaging and by intracoronary Doppler results and a lack of intraobserver and interobserver variability of this noninvasive approach.

Algorithms↗

PubMedDate not supplied

Relationship between contractile reserve, Tl-201 uptake, and collateral angiographic circulation in collateral-dependent myocardium: implications regarding the evaluation of myocardial viability.

BACKGROUND: The aim of this study was to compare collateral angiographic circulation (CC), thallium 201 single photon emission computed tomography (SPECT), low-dose dobutamine echocardiography (LDDE), and their combination in identifying viable myocardium beyond a chronic occlusion. METHODS AND RESULTS: We studied 33 consecutive patients with a chronic occluded coronary artery and regional ventricular dysfunction who underwent dobutamine infusion (5-10 microg x kg(-1) x min(-1)), Tl-201 SPECT, and coronary revascularization (15 patients underwent coronary artery bypass grafting and 18 patients percutaneous transluminal coronary angioplasty). Echocardiography and Tl-201 SPECT at rest were repeated 90 +/- 48 days after revascularization. For viability assessment, Tl-201 SPECT showed the best sensitivity and accuracy (77% and 72%, respectively) compared with LDDE (64% and 63%, respectively) and CC (74% and 55%, P < .05 vs Tl-201 SPECT). Specificity was significantly better for both Tl-201 SPECT (65%) and LDDE (62%) compared with collateral circulation (27%, P < .001 vs Tl-201 SPECT and LDDE). Furthermore, combined Tl-201 SPECT and LDDE data improved specificity (from 88% to 92%) and positive predictive power (from 75% to 78%) but not global accuracy. A direct relationship between the number of viable segments and global functional recovery after revascularization was found only in the case of Tl-201 SPECT (r = 0.48, P = .04). CONCLUSIONS: This study demonstrates that CC has a very low specificity in the evaluation of viability in collateral-dependent myocardium and that LDDE has a very low sensitivity, whereas Tl-201 SPECT is the most reliable method, particularly in akinetic segments, and optimally identifies patients who will mostly benefit from revascularization in terms of ventricular functional improvement. No additional advantages in terms of accuracy were found when Tl-201 SPECT and LDDE data were combined.

Aged↗