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Biomedical subjects

Massimo Volpe

Publications and source records attributed to Massimo Volpe.

At least 55 records · Page 3Linked to original sources
PubMed2003

Contribution of genetic factors to renal lesions in the stroke-prone spontaneously hypertensive rat.

Stroke-prone spontaneously hypertensive rats (SHRSP) develop renal lesions more frequently than the closely related control strain, the stroke-resistant SHR. The aim of this study was to investigate the contribution of genetic factors to the enhanced susceptibility to renal damage of SHRSP in an SHRSP/SHR F2 intercross by means of a genotype/phenotype cosegregation analysis. For this purpose, 154 6-week-old F2-SHRSP/SHR rats (79 male, 75 female) were fed a stroke-permissive Japanese diet for 4 weeks. Systolic blood pressure (SBP) was recorded at the end of the dietary period. Renal damage was scored from 0 to 3, and 274 genetic markers polymorphic between SHR and SHRSP were genotyped. Linkage of genotype markers to the degree of renal disease was determined by chi2 test. Experimental threshold level to declare linkage was calculated by QTL cartographer. SBP was not correlated to renal damage (rho coefficient, 0.201; P=NS). Grade 2 and grade 3 lesions were more frequent in male than in female rats (P=0.01). Two loci, D1Rat238, on chromosome 1 and the IGF receptor-binding protein 4 (Rbp4g) on chromosome 10, were significantly linked to the degree of renal damage, with SHRSP allele being aggressive at D1Rat238 locus and protective at Rbp4g locus. In male rats only, the SHRSP allele at one locus on chromosome 16, D16Mit2, was associated with a more severe degree of renal disease. Our results demonstrate that in this intercross, susceptibility to renal damage is influenced by several genetic loci acting independently from high blood pressure levels and also shows a sexual dimorphism.

Animals↗
PubMed2003

High glucose causes upregulation of cyclooxygenase-2 and alters prostanoid profile in human endothelial cells: role of protein kinase C and reactive oxygen species.

BACKGROUND: Prostaglandins generated by cyclooxygenase (COX) have been implicated in hyperglycemia-induced endothelial dysfunction. However, the role of individual COX isoenzymes as well as the molecular mechanisms linking oxidative stress and endothelial dysfunction in diabetes remains to be clarified. METHODS AND RESULTS: Human aortic endothelial cells were exposed to normal (5.5 mmol/L) and high (22.2 mmol/L) glucose. Glucose selectively increased mRNA and protein expression of COX-2. Its upregulation was associated with an increase of thromboxane A2 and a reduction of prostacyclin (PGI2) release. Glucose-induced activation of PKC resulted in the formation of peroxynitrite and tyrosine nitration of PGI2 synthase. NO release was reduced despite 2-fold increase of endothelial NO synthase expression. Phorbol ester caused an increase of COX-2 and endothelial NO synthase expression similar to that elicited by glucose. These effects were prevented by the PKC inhibitor calphostin C. N-acetylcysteine, vitamin C, and calphostin C prevented ROS formation, restored NO release, and reduced colocalization of nitrotyrosine and PGI2 synthase. Expression of p22(phox), a subunit of NAD(P)H oxidase, was increased, and diphenyleneiodonium inhibited ROS formation. By contrast, indomethacin did not affect glucose-induced ROS generation. CONCLUSIONS: Thus, high glucose, via PKC signaling, induces oxidative stress and upregulation of COX-2, resulting in reduced NO availability and altered prostanoid profile.

Cells, Cultured↗
PubMed2003

p300/cAMP-response-element-binding-protein ('CREB')-binding protein (CBP) modulates co-operation between myocyte enhancer factor 2A (MEF2A) and thyroid hormone receptor-retinoid X receptor.

Thyroid hormone receptors (TRs) and members of the myocyte enhancer factor 2 (MEF2) family are involved in the regulation of muscle-specific gene expression during myogenesis. Physical interaction between these two factors is required to synergistically activate gene transcription. p300/cAMP-response-element-binding-protein ('CREB')-binding protein (CBP) interacting with transcription factors is able to increase their activity on target gene promoters. We investigated the role of p300 in regulating the TR-MEF2A complex. To this end, we mapped the regions of these proteins involved in physical interactions and we evaluated the expression of a chloramphenicol acetyltransferase (CAT) reporter gene in U2OS cells under control of the alpha-myosin heavy chain promoter containing the thyroid hormone response element (TRE). Our results suggested a role of p300/CBP in mediating the transactivation effects of the TR-retenoid X receptor (RxR)-MEF2A complex. Our findings showed that the same C-terminal portion of p300 binds the N-terminal domains of both TR and MEF2A, and our in vivo studies demonstrated that TR, MEF2A and p300 form a ternary complex. Moreover, by the use of CAT assays, we demonstrated that adenovirus E1A inhibits activation of transcription by TR-RxR-MEF2A-p300 but not by TR-RxR-MEF2A. Our data suggested that p300 can bind and modulate the activity of TR-RxR-MEF2A at TRE. In addition, it is speculated that p300 might modulate the activity of the TR-RxR-MEF2A complex by recruiting a hypothetical endogenous inhibitor which may act like adenovirus E1A.

Animals↗
PubMed2003

Comparison of the blood pressure-lowering effects and tolerability of Losartan- and Amlodipine-based regimens in patients with isolated systolic hypertension.

BACKGROUND: Elevated systolic blood pressure is a more important risk factor for cardiovascular and renal disease than elevated diastolic blood pressure. Isolated systolic hypertension (ISH) is the predominant form of hypertension in the elderly. Effects of angiotensin II on the vascular wall and endothelium may contribute to development of ISH. OBJECTIVE: The primary objective of this study was to compare the effects on trough sitting systolic blood pressure (SiSBP) of a regimen of losartan, a selective angiotensin II-receptor antagonist, and an amlodipine-based regimen in patients with ISH. METHODS: This multicenter, prospective, randomized, double-blind, parallel-group study consisted of a 4-week placebo phase and an 18-week active-treatment phase. The losartan-based regimen consisted of losartan 50 mg, increased as needed to losartan 50 mg/hydrochlorothiazide (HCTZ) 12.5 mg at week 6 and to losartan 100 mg/HCTZ 25 mg at week 12 to achieve a target SiSBP <140 mm Hg. the amlodipine-based regimen consisted of amlodipine 5 mg, increased as needed to amlodipine 10 mg at week 6 and to amlodipine 10 mg/HCTZ 25 mg at week 12. The primary efficacy measure was change in trough SiSBP from baseline to week 18. Information on the tolerability of study treatments was collected at each visit, including the investigator's and patient's observations of clinical adverse experiences (CAEs), laboratory adverse experiences, and responses to a symptom questionnaire. RESULTS: Eight hundred fifty-seven patients (65.6% female) were randomized to treatment, 432 in the losartan group and 425 in the amlodipine group. Their mean age was 67.6 years, and they had a mean duration of hypertension of 6.7 years at baseline. The losartan and amlodipine groups (intent-to-treat population) had baseline mean SiSBP values of 171.2 and 171.9 mm Hg, respectively. At week 18 (the primary end point), the mean change from baseline in SiSBP was -27.4 mm Hg for 426 patients who received losartan and -28.1 mm Hg for 419 patients who received amlodipine (estimated least-square mean difference, 0.3 mm Hg; 95% CI, -1.4 to 2.0), indicating that losartan's effect on systolic blood pressure was noninferior to that of amlodipine. The proportion of patients who responded (SiSBP <140 mm Hg or a > or =20-mm Hg decrease in SiSBP from baseline) was comparable between groups (73.9% losartan, 75.4% amlodipine). The incidence of CAEs and drug-related CAEs was significantly greater in the amlodipine group (amlodipine, 79.8% and 43.8%, respectively; losartan, 67.8% and 25.5%; P < or = 0.001). In addition, more patients in the amlodipine group discontinued therapy due to a drug-related CAE compared with patients in the losartan group (12.9% vs 4.4%, respectively; P < or = 0.001). Lower-extremity edema was the most common drug-related CAE in the amlodipine group (24.0% amlodipine, 2.5% losartan; P < or = 0.001); dizziness was the most common drug-related CAE in the losartan group (6.0% losartan, 4.0% amlodipine). CONCLUSIONS: In these patients with ISH, losartan and amlodipine produced comparable clinically relevant reductions in SiSBP; however, losartan was better tolerated, as evidenced by fewer CAEs and discontinuations compared with amlodipine. Losartan may be considered for the initial treatment of ISH.

Adult↗
PubMed2003

Altered regulation of endothelin A receptor subtype in the cerebral arterioles in response to a Japanese-style diet, in stroke-prone hypertensive rats.

OBJECTIVE: To investigate the expression of endothelin (ET)-1 and its receptors in the cerebral arterioles of stroke-prone (spSHR) and control spontaneously hypertensive rats (SHRs) and the changes in endothelin receptor subtypes A and B density elicited by a stroke-permissive diet, before the development of stroke. METHODS: Six-week-old SHRs (n=11) and spSHRs (n=11) were assigned to either a regular or a "Japanese"-style diet, in addition to 1% NaCl in the drinking water, for 4 weeks. Cryosections (10 microm thick) of rat brain were assessed for endothelin receptor distribution and density by autoradiography with [125I]ET-1 (10(-10) mol/l) in the presence of cold ET-1 (10(-6) mol/l) or the peptide antagonists BQ-123 (10(-6) mol/l) or BQ-788 (10(-6) mol/l). Reverse transcriptase polymerase chain reaction (RT-PCR) and immunohistochemistry were used to detect specific mRNAs and localize immunoreactive ET-1 and ET(A) and ET(B). RESULTS: In both strains, immunoreactive ET-1 was detected in the endothelium of cerebral arterioles, and RT-PCR and autoradiography demonstrated the coexistence of both receptor subtypes in brain homogenates and the cerebral arteriole walls, respectively. With the regular diet, the ET(A) receptor density was lower in SHRs than in spSHRs (P = 0.007), whereas the ET(B) receptor density was similar (P = NS). The Japanese-style diet increased the density of ET(A) receptors (P = 0.006) in SHRs, but decreased it (P = 0.019) in spSHRs. No effect was seen on ET(B) receptor density. CONCLUSIONS: ET(A) and ET(B) receptor subtypes are expressed in the wall of cerebral arterioles of SHRs and spSHRs. The latter strain showed a marked increase in ET(A) receptor density under a regular diet, in addition to an altered regulation in response to a stroke-permissive diet.

Animals↗
PubMed2003

Is it time to measure microalbuminuria in hypertension?

Former guidelines on hypertension never made a commitment to the detection of microalbuminuria for screening or follow-up of hypertensive patients. On the other hand, growing evidence support the contributory role of microalbuminuria in the prediction of absolute cardiovascular risk in hypertension and document the potential relevance of this parameter to the initial choice of antihypertensive treatment. Upcoming new guidelines and diagnostic algorithms in hypertension need to underscore the clinical positioning of microalbuminuria for stratification of risk and follow-up purposes.

Albuminuria↗
PubMed2003

Angiotensin II AT2 receptor subtype: an uprising frontier in cardiovascular disease?

The renin-angiotensin system (RAS) plays a pivotal role in the regulation of fluid, electrolyte balance and blood pressure, and is a modulator of cellular growth and proliferation. Biological actions of RAS are linked to the binding of the effector molecule, angiotensin II (AngII), to specific membrane receptors, mostly the AT1 subtype and, to a lesser extent, other subtypes. Following the identification and characterization of the AT2 subtype receptor, it has been proposed that a complex interaction between AngII and its receptors may play an important role in the effects of RAS. In this paper current information on AngII subtype receptors--their structure, regulation and intracellular signalling--are reviewed, with a particular emphasis on the potential relevance for cardiovascular pathophysiology. In addition, we discuss modulation of expression of the AT2 receptor and its interaction with the AT1 receptor subtype, as well as the potential effects of this receptor on blood pressure regulation. A better understanding of the integrated effects of the AngII subtype receptors may help to elucidate the function of the RAS, as well as their participation in the mechanisms of cardiovascular disease and attendant therapeutic implications.

Animals↗
PubMed2003

Genetic polymorphism of the renin-angiotensin-aldosterone system and arterial hypertension in the Italian population: the GENIPER Project.

OBJECTIVE: To detect the association of single polymorphisms of the renin-angiotensin-aldosterone system (RAAS), or different combinations thereof, with hypertension. DESIGN AND METHODS: The GENIPER database is the result of a collaborative effort of 13 Italian research centres to collect genomic DNA in subjects well characterized in terms of blood pressure status. A total of 2461 subjects (normotensive = 611; hypertensive = 1850) were selected and genotyped for the angiotensin-converting enzyme insertion/deletion (ACE I/D), angiotensinogen (AGT) T/C704, angiotensin receptor type 1 (AT1) A/C1166 and aldosterone synthase (ALDO) T/C-344 genetic variants. RESULTS: Allele frequencies were homogeneous over the Italian territory, with the relevant exception of the ACE I/D, the D allele being significantly less frequent in the northern region (61%) than in the rest of the country (67%; P < 0.0001). When comparing allele and genotype distributions in normotensives and hypertensives, the latter presented a small but statistically significant increase of the C allele of AGT T/C704, the A allele of AT1 A/C1166 and the T allele of ALDO T/C-344 polymorphisms (P = 0.018, P = 0.037 and P = 0.015, respectively), with similar trends all over the country. A step-wise logistic regression analysis confirmed these findings, by entering in the model as independent predictors of blood pressure status of AGT T/C704 (P = 0.013), ALDO T/C-344 (P = 0.032) and AT1 A/C1166 polymorphisms (P = 0.075), but not ACE I/D (P = 0.996). We also found some evidence of an additive effect of individual genetic variants of the RAAS, modulating at different levels the same functional pathway, on the risk of developing hypertension, but no synergistic interaction was observed. CONCLUSIONS: Our results suggest that some allelic variants of RAAS genes carry a small but identifiable risk of developing arterial hypertension.

Databases, Genetic↗
PubMed2003

Enhanced TNF alpha and oxidative stress in patients with heart failure: effect of TNF alpha on platelet O2- production.

Experimental studies have suggested that TNF alpha, a pro-inflammatory cytokine, may contribute to the deterioration of cardiovascular function through various mechanisms, including the generation of reactive oxygen species. It has not yet been demonstrated whether TNF alpha has prooxidant activity in patients with heart failure, and what the mechanism eventually resulting in this effect are. We analyzed 42 patients (38 men and 4 women, aged 26 to 74 years) with heart failure, secondary to idiopathic dilated cardiomyopathy (n=21), coronary artery disease (n=15), and valve disease (n=6), and 20 controls (18 men and 2 women, aged 49 to 67 years). Ten patients were in class I, 9 in class II, 15 in class III and 8 in class IV according to NYHA Classification. Blood samples were obtained from each patient to evaluate basal and collagen-induced platelet O(2)(-) production, and plasma TNF alpha. In vivo results showed increased platelet O(2)(-) production and plasma TNF alpha levels in NYHA class III-IV compared with that in controls or in NYHA I-II (p<0,001); platelet O(2)(-) production correlated significantly (R=0,6; p<0,01) with TNF alpha plasma levels. In vitro studies showed TNF alpha dose-dependently (5-40 pg/ml) induced platelet O(2)(-) production, and that this effect was significantly inhibited by its specific inhibitor, WP9QY (1 microM); aspirin (100 microM), AACOCF(3), a specific PLA(2) inhibitor (14 microM), and DPI, an inhibitor of NADPH oxidase, significantly inhibited TNF alpha-mediated platelet O(2)(-) production. This study suggests that in patients with heart failure, enhanced platelet O(2)(-) production is mediated by TNF alpha via activation of arachidonic acid and NADPH oxidase pathways.

Adult↗
PubMed2002

Effect of a regulatory mutation on the rat atrial natriuretic peptide gene transcription.

To investigate the functional relevance of a regulatory mutation affecting the enhancer element PEA2 of the rat ANP gene we transfected rat cardiomyocytes and aortic endothelial cells with either the mutant or the wild-type ANP promoter construct (-683 +54) and performed CAT assays both at baseline and in response to Phenylephrine and Angiotensin II. In the myocardial cells we also determined the DNA/nuclear protein interaction through electrophoretic mobility shift assay. These studies showed a significantly lower degree of ANP transcription in the presence of the mutant PEA2 site, thus demonstrating its functional significance and the biological relevance of ANP gene structural alterations.

Animals↗
PubMed2002

ACE inhibition and cardiovascular mortality and morbidity in essential hypertension: the end of the search or a need for further investigations?

Scientific evidence currently available supports the concept that renin-angiotensin blockade with angiotensin converting enzyme inhibitors as a first-line treatment exhibits in arterial hypertension beneficial effects in the prevention of mortality and morbidity comparable to those achieved with diuretics and beta-blockers. In addition, the renin-angiotensin blockade has also proved to be beneficial in the secondary prevention of several complications of hypertensive disease such as after myocardial infarction and congestive heart failure, as well as in the prevention of the incidence of type 2 diabetes, and the progression of diabetic and nondiabetic nephropathy. In this later regard, recent evidence with angiotensin II receptor antagonists in reducing the progression of nephropathy in type 2 diabetes strongly confirms that antagonism of the renin-angiotensin system is an effective approach to cardiovascular and renal disease. Finally, the renin-angiotensin blockade in high-risk patients may reduce cardiovascular mortality independently of the effect on blood pressure (BP). The effect of other antihypertensive drugs on cardiovascular risk in patients with high-normal BP should be investigated to establish whether they exhibit a comparable effect or whether there is a class-related benefit of drugs blocking the renin-angiotensin system. Such a strategy could also be encouraged to design future interventional studies with the newer classes of compounds (angiotensin II AT1-receptor antagonists, vasopeptidase inhibitors, endothelin antagonists), which would have the additional potential advantage of providing information more easily transferable to large-scale clinical practice.

Angiotensin-Converting Enzyme Inhibitors↗
PubMed2002

Hypertension guidelines: criteria that might make them more clinically useful.

Cardiovascular disease prevention depends on reduction of risk factors, including hypertension. Guidelines designed to improve management of hypertension are widely available. Their purpose is to assemble the available data from basic biomedical science, epidemiology, and clinical science in an accessible form with which physicians and patients can make reasoned decisions for individual cases. However, guidelines have been neither widely accepted, nor effectively implemented. We recommend a strategy for guideline preparation designed to yield a product more user friendly, accessible, and effective. Guideline recommendations and the evidence used to make them should be based on an explicit grading system. Relevant clinical as well as nonclinical factors must be considered. Moreover, because the goal of antihypertensive therapy is to prevent cardiovascular events, and the likelihood of such events is determined by multifactor or absolute risk assessment, risk, rather than level of blood pressure (BP), should determine the need for therapy. Similarly, the benefit of therapy must be assessed by reduction in cardiovascular disease morbidity and mortality.

Humans↗
PubMed2002

Nitric-oxide-mediated relaxations in salt-induced hypertension: effect of chronic beta1 -selective receptor blockade.

BACKGROUND: Nebivolol is a new beta1-selective adrenergic receptor antagonist with a direct vasorelaxant effect that involves activation of the l-arginine-nitric oxide (NO) pathway. Therefore, treatment with nebivolol may protect against endothelial injury in hypertension. OBJECTIVE: To investigate whether chronic selective beta1-blockade with nebivolol could prevent endothelial dysfunction in salt-induced hypertension, and to compare it with atenolol. METHODS: Dahl salt-sensitive rats were treated for 8 weeks with standard chow or chow containing 4% NaCl alone or in combination with nebivolol (10 mg/kg per day) or atenolol (100 mg/kg per day). Isometric tension was continuously recorded in isolated aorta and small mesenteric arteries. Constitutive NO synthase (cNOS) activity was determined by [3H]citrulline assay. RESULTS: Chronic salt administration increased systolic blood pressure by 38 +/- 5 mmHg in salt-treated rats as compared with that in control rats. Both nebivolol and atenolol prevented a salt-induced increase in pressure. cNOS activity was significantly decreased by a high-salt diet. The impairment of endothelium-dependent relaxations in response to acetylcholine in salt-treated rats was prevented only by nebivolol, in both large and small arteries. In contrast, the reduced endothelium-independent relaxations and contractions in response to sodium nitroprusside and endothelin-1, respectively, were restored by both drugs. Nebivolol, but not atenolol, restored cNOS activity. CONCLUSIONS: Despite nebivolol and atenolol having the same blood-pressure-decreasing effect, only nebivolol was able to prevent endothelial dysfunction. This study demonstrates for the first time that the acute NO-mediated vasodilatory action of nebivolol is also present during chronic treatment. Hence, nebivolol might become a new therapeutic tool with which to exert vascular protective effects against end-organ damage in conditions associated with NO deficiency.

Adrenergic beta-Antagonists↗
PubMed2002

Functional cross-talk between angiotensin II and epidermal growth factor receptors in NIH3T3 fibroblasts.

BACKGROUND: The main angiotensin (Ang) II subtype receptors (AT1R and AT2R) are involved in cellular growth processes and exert functionally antagonistic effects. OBJECTIVE: To characterize the mechanisms by which Ang II receptors influence growth, by investigating the interactions between Ang II subtype receptors and epidermal growth factor (EGF) receptors on mitogen-activated protein kinase (MAPK) pathway activation. DESIGN AND METHODS: The experiments were performed using a mouse fibroblast cell line, NIH3T3, by transient co-transfection with rat AT1R or AT2R expression vectors, or both. Extracellular-signal-regulated kinase (ERK)1/2 phosphorylation was analysed by western blot and the ERK activity was evaluated using PathDetect, an in-vivo signal transduction pathway trans-reporting system. Selective Ang II receptor antagonists (losartan for AT1R and PD123319 for AT2R) were used to investigate the contributions of each receptor to the response observed. RESULTS: Our data show that, in this cellular model, both Ang II receptors phosphorylate ERK1/2. However, in the cells expressing AT1R, the EGF-induced MAPK pathway was enhanced in the presence of Ang II in a synergistic fashion. In contrast, a reduction of EGF-induced MAPK activation was observed in the cells expressing AT2R. In cells expressing both Ang II subtype receptors, Ang II promoted an enhancement of EGF-induced MAPK activation. However, in the presence of the AT1R antagonist, losartan, the effect of EGF was reduced. CONCLUSION: These data indicate the existence of an opposite cross-talk of AT1R and AT2R with EGF receptors, and suggest a complex functional interaction between these pathways in the regulation of cellular growth processes.

3T3 Cells↗
PubMed2002

The renin-angiotensin system as a risk factor and therapeutic target for cardiovascular and renal disease.

The renin-angiotensin system (RAS) plays an important homeostatic role in BP regulation, water and salt balance, and tissue growth control under physiologic conditions. On the other hand, a pivotal involvement of the RAS in the pathophysiology of cardiovascular and renal disease is extensively supported by both basic and clinical evidence. In particular, it is today recognized that angiotensin II (AngII), the biologic effector of the RAS, may prompt a number of relevant structural and functional abnormalities through the activation of a complex of cellular effects mostly mediated via its binding with the AT(1) subtype receptors. The key role of these AngII-linked mechanisms of disease is strongly corroborated by large interventional studies. In fact, pharmacologic interference with RAS activity, by both preventing AngII formation with angiotensin-converting enzyme inhibitors or antagonizing its binding to cell membrane receptors by selective antagonists, is associated with highly beneficial outcomes in major disease conditions (hypertension, diabetes, renal failure, heart failure, myocardial infarction, stroke, and others). This article briefly reviews the current views on the biologic organization of RAS evidence supporting a pathogenic role of the RAS activity in promoting cardiac, vascular, and renal disease, and finally provides the basis for considering inhibition of RAS activity a major target for therapeutic interventions in these conditions.

Cardiovascular Diseases↗
PubMed2002

Cerebrovascular disease in women.

Stroke represents a severe and growing health problem in the general population. The increasing burden of disease associated with stroke appears to be largely related to progressive ageing of the population, and in fact is increasing more rapidly in women than in men. In addition, emerging pathophysiological, clinical and therapeutic issues confer specific characteristics to stroke in women. This article briefly covers some of the most important of these aspects.

Blood Pressure↗