G. Leftheriotis

Disseminated Arterial Calcification and Enhanced Myogenic Response Are Associated With Abcc6 Deficiency in a Mouse Model of Pseudoxanthoma Elasticum

Objective—Pseudoxanthoma elasticum is an inherited metabolic disorder resulting from ABCC6 gene mutations. It is characterized by progressive calcification and fragmentation of elastic fibers in the skin, retina, and the arterial wall. Despite calcium accumulation in the arteries of patients with pseudoxanthoma elasticum, functional consequences remain unknown. In the present study, we investigated arterial structure and function in Abcc6−/− mice, a model of the human disease. Approach and Results—Arterial calcium accumulation was evaluated using alizarin red stain and atomic absorption spectrometry. Expression of genes involved in osteochondrogenic differentiation was measured by polymerase chain reaction. Elastic arterial properties were evaluated by carotid echotracking. Vascular reactivity was evaluated using wire and pressure myography and remodeling using histomorphometry. Arterial calcium accumulation was 1.5- to 2-fold higher in Abcc6−/− than in wild-type mice. Calcium accumulated locally leading to punctuate pattern. Old Abcc6−/− arteries expressed markers of both osteogenic (Runx2, osteopontin) and chondrogenic lineage (Sox9, type II collagen). Abcc6−/− arteries displayed slight increase in arterial stiffness and vasoconstrictor tone in vitro tended to be higher in response to phenylephrine and thromboxane A2. Pressure-induced (myogenic) tone was significantly higher in Abcc6−/− arteries than in wild type. Arterial blood pressure was not significantly changed in Abcc6−/−, despite higher variability. Conclusions—Scattered arterial calcium depositions are probably a result of osteochondrogenic transdifferentiation of vascular cells. Lower elasticity and increased myogenic tone without major changes in agonist-dependent contraction evidenced in aged Abcc6−/− mice suggest a reduced control of local blood flow, which in turn may alter vascular homeostasis in the long term.

e-PWV: A Web Application for Assessing Online Carotid-Femoral Pulse Wave Velocity

This article presents e-PWV, a web application for the determination of Pulse Wave Velocity (PWV) running on a web platform called NooLib. e-PWV has been applied on signals recorded by an ultrasound system (\(PWV_{et}\), Aloka, Japan) and representing the arterial diameter changes in carotid and femoral sites. \(PWV_{et}\) measurements were compared to PWV recorded by a tonometric technique (\(PWV_{pp}\), PulsePen, Italy). The study was conducted on 120 patients. We found an excellent correlation of r = 0.95 between \(PWV_{et}\) et \(PWV_{pp}\) (\(P<0.0001\); 95% confidence interval of 0.91–0.96; \(PWV_{et}=0.88\times PWV_{pp} + 0.57\)). We observed a small offset of \(-0.33\) ms\(^{-1}\) on the Bland-Altman plot with a limit of agreement from \(-2.21\) to 1.54 ms\(^{-1}\). Our results suggest that e-PWV application can produce online a reliable marker of the regional aortic stiffness using an echotracking system.