The aim of this study was to estimate the incidence of COVID-19 disease in the French national population of dialysis patients, their course of illness and to identify the risk factors associated with mortality. Our study included all patients on dialysis recorded in the French REIN Registry in April 2020. Clinical characteristics at last follow-up and the evolution of COVID-19 illness severity over time were recorded for diagnosed cases (either suspicious clinical symptoms, characteristic signs on the chest scan or a positive reverse transcription polymerase chain reaction) for SARS-CoV-2. A total of 1,621 infected patients were reported on the REIN registry from March 16th, 2020 to May 4th, 2020. Of these, 344 died. The prevalence of COVID-19 patients varied from less than 1% to 10% between regions. The probability of being a case was higher in males, patients with diabetes, those in need of assistance for transfer or treated at a self-care unit. Dialysis at home was associated with a lower probability of being infected as was being a smoker, a former smoker, having an active malignancy, or peripheral vascular disease. Mortality in diagnosed cases (21%) was associated with the same causes as in the general population. Higher age, hypoalbuminemia and the presence of an ischemic heart disease were statistically independently associated with a higher risk of death. Being treated at a selfcare unit was associated with a lower risk. Thus, our study showed a relatively low frequency of COVID-19 among dialysis patients contrary to what might have been assumed.

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Abstract-Angiotensin II is a potent growth factor involved in arterial wall homeostasis. In resistance arteries, chronic increases in blood flow induce a rise in diameter associated with arterial wall hypertrophy. Nevertheless, the role of angiotensin II in this remodeling is unknown. We investigated the effect of blocking angiotensin II production or receptor activation on flow-induced remodeling of mesenteric resistance arteries. Arteries were ligated in vivo to generate high-flow arteries compared with normal flow (control) vessels located at a distance. Arteries were isolated after 1 week for in vitro analysis. Arterial diameter, media surface, endothelial NO synthase expression, superoxide production, and extracellular signal-regulated kinase 1/2 phosphorylation were higher in high-flow than in control arteries. Angiotensin-converting enzyme inhibition (perindopril) and angiotensin II type 1 receptor blockade (candesartan) prevented arterial wall hypertrophy without affecting diameter enlargement. The nonselective vasodilator hydralazine had no effect on remodeling. Although perindopril and candesartan increased endothelial NO synthase expression in high-flow arteries, hypertrophy remained in rats treated with N G -nitro-L-arginine methyl ester and mice lacking endothelial NO synthase. Perindopril and candesartan reduced oxidative stress in high-flow arteries, but superoxide scavenging did not prevent hypertrophy. Both Tempol and the absence of endothelial NO synthase prevented the rise in diameter in high-flow vessels. Extracellular signal-regulated kinase 1/2 activation in high-flow arteries was prevented by perindopril and candesartan and not by hydralazine. Extracellular signal-regulated kinase 1/2 inhibition in vivo (U0126) prevented hypertrophy in high-flow arteries. Thus, a chronic rise in blood flow in resistance arteries induces a diameter enlargement involving NO and superoxide, whereas hypertrophy was associated with extracellular signal-regulated kinase 1/2 activation by angiotensin II. (Hypertension. 2010;55:109-115.) Key Words: resistance arteries Ⅲ blood flow Ⅲ angiotensin II Ⅲ ERK1/2 Ⅲ shear stress Ⅲ angiotensin I-converting enzyme inhibitors Ⅲ angiotensin II type 1 receptor inhibitor A ngiotensin II is a potent vasoactive hormone involved in the regulation of vascular tone, 1,2 in cell growth and apoptosis, 3 and in cell migration and extracellular matrix deposition. 4 Angiotensin II also has a central role in the functional and structural integrity of the vascular wall and in the pathogenesis of cardiovascular diseases. [5][6][7] Chronic changes in blood flow occur in physiological conditions, such as exercise, pregnancy, or postnatal development, and in pathological conditions, such as arterial occlusive diseases, diabetes mellitus, or hypertension. 1,8 A chronic increase in blood flow induces remodeling of the vascular wall to adapt arterial wall strain to the new hemodynamic conditions, as described in large blood vessels 9 and in small resistance arteries. 1,8 Indeed, in resistance art...