Hypotension | EPFL Graph Search

Hypotension is low blood pressure. Blood pressure is the force of blood pushing against the walls of the arteries as the heart pumps out blood. Blood pressure is indicated by two numbers, the systolic blood pressure (the top number) and the diastolic blood pressure (the bottom number), which are the maximum and minimum blood pressures, respectively. A systolic blood pressure of less than 90 millimeters of mercury (mmHg) or diastolic of less than 60 mmHg is generally considered to be hypotension. Different numbers apply to children. However, in practice, blood pressure is considered too low only if noticeable symptoms are present. Symptoms may include dizziness, lightheadedness, confusion, feeling tired, weakness, headache, blurred vision, nausea, neck or back pain, an irregular heartbeat or feeling that the heart is skipping beats or fluttering, and fainting. Hypotension is the opposite of hypertension, which is high blood pressure. It is best

Implanted System for Orthostatic Hypotension in Multiple-System Atrophy

Suje Amir, Léonie Asboth, Maxime Berney, Jocelyne Bloch, Grégoire Courtine, Robin Jonathan Demesmaeker, Grégory Didier Dumont, Nicolas Hankov, Sergio Daniel Hernandez, Jordan Squair

Orthostatic hypotension is a cardinal feature of multiple-system atrophy. The upright posture provokes syncopal episodes that prevent patients from standing and walking for more than brief periods. We implanted a system to restore regulation of blood pressure and enable a patient with multiple-system atrophy to stand and walk after having lost these abilities because of orthostatic hypotension. This system involved epidural electrical stimulation delivered over the thoracic spinal cord with accelerometers that detected changes in body position.

MASSACHUSETTS MEDICAL SOC2022

Notch Signaling in Pigment Cells and Generation of Mouse Models for Ocular Diseases

Bhushan Sarode

Cellular signaling mediated by Notch receptors results in coordinated regulation of cell growth, survival and differentiation. In melanocytes, Notch signaling is essential for the maintenance of melanocytes and the melanocyte stem cell population. Whereas, in pigmented eye structures, specifically in ciliary body and iris, the role of Notch signaling in their structure and their development is largely unknown. In the first part, I have tried to identify possible Notch target genes in melanocytes which might indicate why the melanocyte stem cell population disappears in the absence of Notch. For that purpose, I carried out microarray analysis on Notch deficient melanoblasts and identified putative Notch targets. I have furthermore established mouse melanocyte cell lines from mice which could be used as a valuable tool to study melanocyte biology. In the second part, I have elucidated the functional significance of the Notch cascade in pigmented eye structures. The ciliary body and iris are pigmented epithelial structures in the anterior eye segment that function to maintain correct intraocular pressure and regulate exposure of the internal eye structures to light respectively. In this part I have analyzed the role of the Notch signaling by performing both loss- and gain-of-function experiments for Notch in the murine ocular pigmented epithelium using Mart-1::Cre mice. Loss of canonical Notch2 signaling results in normal iris development but ciliary body aplasia. In contrast, Notch gain-of-function induces the reciprocal phenotype and causes aniridia and ciliary body hyperplasia. The loss and gain-of-function models I have generated develop ocular hypotony and ocular hypertension respectively, mimicking the human diseases phthisis bulbi and closed angle glaucoma. Importantly, the ocular hypertension that occurs following Notch overexpression is responsive to hypotensive drugs, and thus can serve as a platform to evaluate novel hypotensive agents that may be used to treat closed angle glaucoma. In summary, the present study has identified novel putative Notch target genes which will provide us information to study the pigmentation and related disorder. The data obtained in the second chapter provide novel insight into the role of Notch signaling during development of the ciliary body and iris and thus represent a conceptual advance in our understanding of how pigmented structures of the eye are formed. In addition, the genetic models presented in this study represent robust tools with which to study the etiology, pathology and treatment of diseases related to aberrant intraocular pressure, such as phthisis bulbi and closed angle glaucoma.

EPFL2013

Biomechanical adaptation of porcine carotid vascular smooth muscle to hypo and hypertension in vitro

Nikolaos Stergiopulos, Martin Zulliger

Previous research in arterial remodeling in response to changes in blood pressure seldom included both hyper- and hypotension. To compare the effects of low and high pressure on arterial remodeling and vascular smooth muscle tone and performance, we have utilized an in vitro model. Porcine carotid arteries were cultured for 3 days at 30 and 170mmHg and compared to controls cultured at 100mmHg for 1 and 3 days. On the first and last day of culture, pressure-diameter and pressure-wall thickness curves were measured under normal smooth muscle tone using a high-resolution ultrasonic device. Last-day experiments included measurements where vascular smooth muscle was contracted or totally relaxed. From the data wall cross-sectional area, Hudetz elastic modulus and a contraction index related to the diameter reduction under normal smooth muscle tone were calculated. We found that although wall cross-sectional area (indicating wall mass) did not change much, Hudetz elastic modulus was significantly reduced in the 3-day hypotension group. Inspection of the wall contraction index suggests that this is due to a reduction in the vascular smooth muscle tone. Further, the peak of contraction index was found to be shifted to higher pressures in the 3-day 170mmHg group. We conclude that vascular smooth muscle performance adapts to both hypo- and hypertension at short time scales and can alter the biomechanics of the vascular wall in vitro.

2002

Notch Signaling in Pigment Cells and Generation of Mouse Models for Ocular Diseases

Bhushan Sarode

EPFL2013