Hemorrhagic transformation of acute ischemic stroke is limited in hypertensive patients with cardiac hypertrophy.

Background: It has been clearly demonstrated that hypertension and one of its main evoked effects, cardiac hypertrophy, are independent risk factors for ischemic stroke. However, the ischemic brain lesions can further be affected by a second wave of injury characterized by hemorrhagic transformation (HT) of the primary ischemic lesion, which significantly aggravates the clinical outcome. So far, the risk factors that could affect such a transition in hypertensive patients are still unclear.

Ischaemic stroke following tranexamic acid in young patients carrying heterozygosity of MTHFR C677T.

The objective of this study is to report a new manifestation of acute stroke following antifibrinolytic agent administration in young women carrying heterozygosity for methylene-tetrahydrofolate reductase (MTHFR) C677T. The study included two young women who developed an acute ischaemic stroke following three days of tranexamic acid administration for bleeding gynaecological disorders. Case 1, a 44-year-old woman, presented left hemiplegia, mild dysarthria and anosognosia.

Tumor necrosis factor-alpha mediates hemolysis-induced vasoconstriction and the cerebral vasospasm evoked by subarachnoid hemorrhage.

Hypertension can lead to subarachnoid hemorrhage and eventually to cerebral vasospasm. It has been suggested that the latter could be the result of oxidative stress and an inflammatory response evoked by subarachnoid hemorrhage. Because an unavoidable consequence of hemorrhage is lysis of red blood cells, we first tested the hypothesis on carotid arteries that the proinflammatory cytokine tumor necrosis factor-alpha contributes to vascular oxidative stress evoked by hemolysis.

Myocardial Pitx2 differentially regulates the left atrial identity and ventricular asymmetric remodeling programs.

The Pitx2 gene regulates left-right (L/R) asymmetrical cardiac morphogenesis. Constitutive Pitx2 knock out (ko) mice die before birth and display, among other defects, right atrial isomerism, atrial and ventricular septal defects, and double outlet right ventricle. The myocardial role of the gene has not been dissected.

Emilin1 links TGF-beta maturation to blood pressure homeostasis.

TGF-beta proteins are main regulators of blood vessel development and maintenance. Here, we report an unprecedented link between TGF-beta signaling and arterial hypertension based on the analysis of mice mutant for Emilin1, a cysteine-rich secreted glycoprotein expressed in the vascular tree. Emilin1 knockout animals display increased blood pressure, increased peripheral vascular resistance, and reduced vessel size.

Integrin signalling: the tug-of-war in heart hypertrophy.

The mechanical stress imposed by hemodynamic overload on heart walls is a primary event in triggering the cardiac hypertrophic response. Integrins, a class of membrane receptors, are major players in transmitting the mechanical force across the plasma membrane and sensing the mechanical load in cardiomyocytes. In fact, integrins, together with a number of associated cytoskeletal proteins, connect the sarcomeric contractile apparatus to the extracellular matrix across the plasma membrane and trigger intracellular signaling pathways activating the cardiomyocyte hypertrophy program.

Selective Rac-1 inhibition protects from diabetes-induced vascular injury.

Diabetes mellitus is a main risk factor for vascular diseases. Vascular injury induced by diabetes mellitus is characterized by endothelial dysfunction attributable to an increased oxidative stress. So far, the molecular mechanisms involved in the vasculotoxic effects of diabetes are only partially known.

Replacement of K-Ras with H-Ras supports normal embryonic development despite inducing cardiovascular pathology in adult mice.

Ras proteins are highly related GTPases that have key roles in regulating growth, differentiation and tumorigenesis. Gene-targeting experiments have shown that, out of the three mammalian ras genes, only K-ras is essential for normal mouse embryogenesis, and that mice deprived of H-ras and/or N-ras show no major phenotype. We generated mice (HrasKI) in which the K-ras gene had been modified to encode H-Ras protein.

Cardiac overexpression of melusin protects from dilated cardiomyopathy due to long-standing pressure overload.

We have previously shown that genetic ablation of melusin, a muscle specific beta 1 integrin interacting protein, accelerates left ventricle (LV) dilation and heart failure in response to pressure overload. Here we show that melusin expression was increased during compensated cardiac hypertrophy in mice subjected to 1 week pressure overload, but returned to basal levels in LV that have undergone dilation after 12 weeks of pressure overload. To better understand the role of melusin in cardiac remodeling, we overexpressed melusin in heart of transgenic mice.

PI3Kgamma modulates the cardiac response to chronic pressure overload by distinct kinase-dependent and -independent effects.

The G protein-coupled, receptor-activated phosphoinositide 3-kinase gamma (PI3Kgamma) mediates inflammatory responses and negatively controls cardiac contractility by reducing cAMP concentration. Here, we report that mice carrying a targeted mutation in the PI3Kgamma gene causing loss of kinase activity (PI3KgammaKD/KD) display reduced inflammatory reactions but no alterations in cardiac contractility. We show that, in PI3KgammaKD/KD hearts, cAMP levels are normal and that PI3Kgamma-deficient mice but not PI3KgammaKD/KD mice develop dramatic myocardial damage after chronic pressure overload induced by transverse aortic constriction (TAC).

Adaptive and maladaptive hypertrophic pathways: points of convergence and divergence.

Myocardial hypertrophy is a response of cardiac muscle to altered conditions of haemodynamic overload caused by a large number of physiological and pathological conditions. Traditionally, it has been considered a beneficial mechanism. However, sustained hypertrophy has been associated with a significant increase in the risk of cardiovascular disease and mortality.

Left ventricular hypertrophy is associated with asymptomatic cerebral damage in hypertensive patients.

Background And Purpose: It has been demonstrated that left ventricular hypertrophy (LVH) confers an increased risk for major cerebrovascular events. However, it is still uncertain whether there is an association between LVH and asymptomatic cerebrovascular damage in hypertensive patients. In this study, we investigated the relation between LVH, evaluated by both echocardiography (Echo-LVH) and electrocardiography (ECG-LVH), and preclinical cerebral damage, as identified by magnetic resonance imaging.

Melusin, a muscle-specific integrin beta1-interacting protein, is required to prevent cardiac failure in response to chronic pressure overload.

Cardiac hypertrophy is an adaptive response to a variety of mechanical and hormonal stimuli, and represents an early event in the clinical course leading to heart failure. By gene inactivation, we demonstrate here a crucial role of melusin, a muscle-specific protein that interacts with the integrin beta1 cytoplasmic domain, in the hypertrophic response to mechanical overload. Melusin-null mice showed normal cardiac structure and function in physiological conditions, but when subjected to pressure overload--a condition that induces a hypertrophic response in wild-type controls--they developed an abnormal cardiac remodeling that evolved into dilated cardiomyopathy and contractile dysfunction.

Cardiovascular influences of alpha1b-adrenergic receptor defect in mice.

Background: The alpha1-adrenergic receptors (alpha1-ARs) play a key role in cardiovascular homeostasis. However, the functional role of alpha1-AR subtypes in vivo is still unclear. The aim of this study was to evaluate the cardiovascular influences of alpha1b-AR.