Publications by authors named "Christine Richer"

Background And Objectives: In France, diabetes mellitus is now the second cause of end stage renal disease. In a large previous French national study, we observed that dialyzed diabetics have a significant lower risk of death by cancer. This first study was focused on cancer death but did not investigate cancer incidence.

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Genetic and pharmacological studies, clinical and experimental, focused on kallikrein-K1, kinin receptors and ACE/kininase II suggest that kinin release in the settings of ischemia or diabetes reduces organ damage, especially in the heart and kidney. Kinin bioavailability may be a limiting factor for efficacy of current kinin-potentiating drugs, like ACE inhibitors. Primary activation of kinin receptors by prototypic pharmacological agonists, peptidase-resistant, selective B1 or B2, displays therapeutic efficacy in experimental cardiac and peripheral ischemic and diabetic diseases.

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Coronary endothelial dysfunction is involved in cardiac ischemia-reperfusion (IR) injury. Vascular endothelial growth factor (VEGF) activates endothelial cells and exerts cardioprotective effects in isolated hearts. The recently discovered viper venom protein called increasing capillary permeability protein (ICPP) exerts VEGF-like effects in endothelial cells.

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Cardiac ischemia is a leading cause of death, especially in diabetic patients. The diabetic ischemic heart is resistant experimentally to established cardioprotective treatments. New pharmacological approaches to cardiac protection are warranted.

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Tissue kallikrein has been suggested to be involved in blood pressure regulation and in protection against hypertension. However, this hypothesis remains debated. Recently, murine genetic models of kallikrein deficiency have been engineered and partial genetic deficiency in kallikrein activity has been characterized in humans.

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A fair amount of data indicates that bradykinin and lysyl-bradykinin exert arterial, cardiac and renal effects which afford protection against organ damage in diseases, especially in the settings of ischemia or diabetes. The concept of kinins acting as therapeutic agents is supported by the wide use of angiotensin I-converting enzyme (ACE) inhibitors. These inhibitors indeed potentiate kinin action by inhibiting kinin degradation.

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Rationale: Homing of proangiogenic cells (PACs) is guided by chemoattractants and requires proteases to disrupt the extracellular matrix. The possibility that PAC recruitment involves an interaction between proteases and chemotactic factor receptors remains largely unexplored.

Objective: To determine the role of human tissue kallikrein (hK1) in PAC invasion and its dependency on kinin receptor signaling.

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Angiotensin I-converting enzyme (ACE; kininase II) levels in humans are genetically determined. ACE levels have been linked to risk of myocardial infarction, but the association has been inconsistent, and the causality underlying it remains undocumented. We tested the hypothesis that genetic variation in ACE levels influences myocardial tolerance to ischemia.

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The kallikrein kinin system (KKS) is involved in arterial and renal functions. It may have an antihypertensive effect in both essential and secondary forms of hypertension. The role of the KKS in the development of two-kidneys, one-clip (2K1C) hypertension, a high-renin model, was investigated in mice rendered deficient in tissue kallikrein (TK) and kinins by TK gene inactivation (TK-/-) and in their wild-type littermates (TK+/+).

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Objective: Human Tissue Kallikrein (hKLK1) overexpression promotes an enduring neovascularization of ischemic tissue, yet the cellular mechanisms of hKLK1-induced arteriogenesis remain unknown. Furthermore, no previous study has compared the angiogenic potency of hKLK1, with its loss of function polymorphic variant, rs5515 (R53H), which possesses reduced kinin-forming activity.

Methods And Results: Here, we demonstrate that tissue kallikrein knockout mice (KLK1-/-) show impaired muscle neovascularization in response to hindlimb ischemia.

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Tissue kallikrein (KLK1) is a kinin-forming serine protease synthesized in many organs including arteries and kidney. Study of the physiological role of KLK1 has benefited from the availability of mouse and human genetic models of KLK1 deficiency, through engineering of KLK1 mouse mutants and discovery of a major polymorphism in the human KLK1 gene that induces a loss of enzyme activity. Studies in KLK1-deficient mice and human subjects partially deficient in KLK1 have documented its critical role in arterial function in both species.

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Background: Tissue kallikrein (TK) is a major kinin-releasing enzyme present in arteries. TK is involved in cardioprotection in the setting of acute myocardial ischaemia but its role in post-ischaemic heart failure (HF), a major cause of delayed mortality after myocardial infarction (MI), is unknown.

Aim: To determine whether TK deficiency in the mouse influences survival and cardiac remodelling after MI.

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Angiotensin-converting enzyme inhibitors limit infarct size in animal models of myocardial ischemia reperfusion injury. This effect has been shown to be due to inhibition of bradykinin degradation rather than inhibition of angiotensin II formation. The purpose of this study was to determine whether angiotensin AT1 receptor blockade by losartan or its active metabolite EXP3174 protects against myocardial ischemia-reperfusion injury in mice and whether this protection is mediated by the kallikrein kinin system.

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Background: We have previously linked hereditary progressive cardiac conduction defect (hereditary Lenègre's disease) to a loss-of-function mutation in the gene encoding the main cardiac Na+ channel, SCN5A. In the present study, we investigated heterozygous Scn5a-knockout mice (Scn5a+/- mice) as a model for hereditary Lenègre's disease.

Methods And Results: In Scn5a+/- mice, surface ECG recordings showed age-related lengthening of the P-wave and PR- and QRS-interval duration, coinciding with previous observations in patients with Lenègre's disease.

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We investigated in mice whether atherosclerosis exacerbates the development of post-ischemic heart failure and alters the beneficial effects of long-term angiotensin II type 1 receptor blockade in this model. ApoE-deficient (ApoE(-/-)) and C57BL/6J (C57) mice with myocardial infarction (coronary ligation) received vehicle (C57 and ApoE(-/-)) or irbesartan (Ir, 50mg/kg/d orally, C57-Ir and ApoE(-/-)-Ir). Ten months post myocardial infarction, survival rates were similar in C57 (58%) and ApoE(62%).

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Objective: The objective of this study was to investigate the effects of fluvastatin on atherosclerosis, systemic and regional hemodynamics, and vascular reactivity in apolipoprotein E-deficient (ApoE(-/-)) mice.

Methods And Results: Hemodynamics (fluospheres) and vasomotor responses of thoracic aorta and carotid artery were evaluated in male wild-type (WT) and untreated (ApoE(-/-) Control) or fluvastatin-treated (50 mg/kg per day for 20 weeks) ApoE(-/-) mice, all fed a Western-type diet. Plasma cholesterol and aortic root atherosclerotic lesions (ALs) were greater in ApoE(-/-) Control mice (19+/-1 mmol/L and 63,0176+/-38,785 micro m(2), respectively) than in WT mice (2+/-1 mmol/L and 1+/-1 micro m(2), respectively, P<0.

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Objectives: Mechanisms involved in hypertension in homozygous mice for the defective endothelial nitric oxide synthase gene (eNOS-/-) have not been fully elucidated. As NO is a potent vasodilator agent and possibly promotes angiogenesis, we investigated whether vasoconstriction and/or microvascular rarefaction could explain hypertension in these mice.

Methods: Immunohistochemistry with mouse monoclonal smooth muscle alpha-actin antibody was used to detect arterioles, and quantification of arteriolar density was performed in the left ventricle and in the gracilis muscle of 12-week-old male eNOS+/+ and eNOS-/- mice.

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