scholarly journals Ocular Pressure-Volume Relationship and Ganglion Cell Death in Glaucoma

2020 ◽  
Vol 05 (02) ◽  
pp. 1-1
Author(s):  
Ji-Jie Pang ◽  
◽  
Samuel M. Wu ◽  
Keyword(s):  
Normal Tension Glaucoma ◽  
Curvature Radius ◽  
Published Data ◽  
Wild Type ◽  
Volume Relationship ◽  
Universal Expansion ◽  
Normal Atmospheric Pressure ◽  
Pressure Volume Relationship ◽  
Ocular Pressure ◽  
Ganglion Cell Death

We studied how GC death in glaucoma related to the intraocular pressure (IOP), eyeball volume (VS) and elasticity (volumetric KS and tensile ES), and eyeball volume-pressure relation. Glaucomatous GC loss was studied in DBA/2J (D2) mice with wild-type mice as controls. GCs were retrogradely identified and observed with a confocal microscope. The elasticity calculation was also done on published data from patients treated by a gas bubble injection in the vitreous cavity. The GC population in D2 mice (1.5- to 14-month-old) was negatively correlated with following factors: VS (p = 0.0003), age (p = 0.0026) and IOP (but p = 0.0966). As indicated by average values, adult D2 mice (³6 months) suffered significant GC loss, low KS and ES, and universal expansion of VS with normal IOP. KS and ES in the patients were also lower upon prolonged eyeball expansion compared to acute expansion. Based on the results and presumptions of a closed and continuous eyeball space (thereby ΔVS » ΔVW, ΔVW-the change in the aqueous humor amount), we deduced equations on the ocular volume-pressure relationship: ΔIOP = KS*ΔVW/VS or ΔIOP = (2/3)*[1/(1-n)]*(H/R)*ES*ΔVW/VS (n, Poisson’s ratio taken as 0.5; R, the curvature radius; and H, the shell thickness). Under normal atmospheric pressure, IOP of 10~50 mmHg contributed only 1.2~6.6% of the pressure opposing the retina and eyeball shell. We conclude: 1) A disturbance of ocular volume-pressure homeostasis, mediated primarily by low KS and ES, expanded VS, and large ΔVW, is correlated with GC death in glaucoma and 2) D2 mice with GC loss and normal IOP may serve as animal models for human normal-tension glaucoma.

scholarly journals Longitudinal Reinforcement of Acute Myocardial Infarcts Improves Function by Transmurally Redistributing Stretch and Stress

2019 ◽  
Vol 142 (2) ◽  
Author(s):  
Ana Cristina Estrada ◽  
Kyoko Yoshida ◽  
Samantha A. Clarke ◽  
Jeffrey W. Holmes
Keyword(s):  
Diastolic Pressure ◽  
Heart Function ◽  
Systolic Function ◽  
Systolic Pressure ◽  
Left Ventricular ◽  
Published Data ◽  
Longitudinal Reinforcement ◽  
Wide Range ◽  
Volume Relationship ◽  
Pressure Volume Relationship

Abstract A wide range of emerging therapies, from surgical restraint to biomaterial injection to tissue engineering, aim to improve heart function and limit adverse remodeling following myocardial infarction (MI). We previously showed that longitudinal surgical reinforcement of large anterior infarcts in dogs could significantly enhance systolic function without restricting diastolic function, but the underlying mechanisms for this improvement are poorly understood. The goal of this study was to construct a finite element model that could match our previously published data on changes in regional strains and left ventricular function following longitudinal surgical reinforcement, then use the model to explore potential mechanisms for the improvement in systolic function we observed. The model presented here, implemented in febio, matches all the key features of our experiments, including diastolic remodeling strains in the ischemic region, small shifts in the end-diastolic pressure–volume relationship (EDPVR), and large changes in the end-systolic pressure–volume relationship (ESPVR) in response to ischemia and to patch application. Detailed examination of model strains and stresses suggests that longitudinal reinforcement reduces peak diastolic fiber stretch and systolic fiber stress in the remote myocardium and shifts those peaks away from the endocardial surface by reshaping the left ventricle (LV). These findings could help to guide the development of novel therapies to improve post-MI function by providing specific design objectives.

Area beneath the end-systolic pressure-volume relationship as an index of inotropicstate in intact dogs

1986 ◽  
Vol 18 ◽  
pp. 20-20 ◽  
Author(s):  
A CROTTOGINI ◽  
J BARRA ◽  
M RODRIGUEZCHATRUC ◽  
R ARMENTANO ◽  
E CABRERA ◽  
...  
Keyword(s):  
Systolic Pressure ◽  
Volume Relationship ◽  
Pressure Volume Relationship

A modified tangent-gas approximation for two-dimensional steady flow

1958 ◽  
Vol 4 (6) ◽  
pp. 600-606 ◽  
Author(s):  
G. Power ◽  
P. Smith
Keyword(s):  
Least Squares ◽  
Steady Flow ◽  
Variational Approach ◽  
Least Squares Method ◽  
Two Dimensional ◽  
Subsonic Flows ◽  
Von Karman ◽  
Straight Line ◽  
Volume Relationship ◽  
Pressure Volume Relationship

A set of two-dimensional subsonic flows past certain cylinders is obtained using hodograph methods, in which the true pressure-volume relationship is replaced by various straight-line approximations. It is found that the approximation obtained by a least-squares method possibly gives best results. Comparison is made with values obtained by using the von Kármán-Tsien approximation and also with results obtained by the variational approach of Lush & Cherry (1956).

Right Ventricular Pressure-Volume Relationship to Evaluate Right Ventricular-Pulmonary Arterial Coupling and Energetics

2015 ◽  
Vol 21 (10) ◽  
pp. S152
Author(s):  
Takafumi Sakamoto ◽  
Kohtaro Abe ◽  
Kazuya Hosokawa ◽  
Keiji Oi ◽  
Yasushi Mukai ◽  
...  
Keyword(s):  
Right Ventricular ◽  
Ventricular Pressure ◽  
Volume Relationship ◽  
Pressure Volume Relationship ◽  
Pulmonary Arterial

scholarly journals Longitudinal Study on Ocular Manifestations in a Cohort of Patients with Fabry Disease

2019 ◽  
Author(s):  
Langis Michaud
Keyword(s):  
Anterior Segment ◽  
Published Data ◽  
Retinal Vessels ◽  
Enzyme Replacement ◽  
Corneal Haze ◽  
Ocular Manifestations ◽  
Ocular Pressure ◽  
Upper Lid ◽  
Group 2 ◽  
Conjunctival Vessels

ABSTRACTPurposeThis study aims to assess the evolution of ocular manifestations in a cohort of Fabry patients.METHODSThis is a prospective observational study conducted from 2013 to 2017 (5 consecutive exams). All subjects underwent a comprehensive ocular examination including oriented case history, refraction, corneal topography, biomechanical corneal properties and pachometry assessments, aberrometry, anterior segment evaluation, double-frequency visual field (FDT), intra-ocular pressure, and ocular fundus. At baseline, 41 subjects enrolled but 9 dropped-out and 4 files were not kept for analysis (missing data). Remaining 28 subjects were classified into: Group 1 -hemizygotes (HMZ), all on enzyme replacement therapy (ERT) (N=10); Group 2 -heterozygotes (HTZ) actively ERT-treated (N=8), and Group 3 -HTZ not treated (N=10).RESULTSThere is a high intra and inter-subjects variability. At baseline, prevalence of the ocular manifestations found is similar to published data: cornea verticillata (89.2%), conjunctival vessels tortuosity (85.7%), corneal haze (67.8%), retinal vessels tortuosity (64.2%), anterior cataract (39.2%) and posterior cataract (28.5%). Prevalence for new elements are found: upper lid vessels toricity (96.4%) and micro-aneurysms (42.8%). At the end, micro-aneurysms (+82%), posterior cataract (+75%) corneal haze (+21%) anterior cataract (+17%) and retinal vessels tortuosities (+4%) evolved in prevalence and severity despite the fact that 68% of the patients were on ERT. Treated heterozygotes evolved more than other groups (p>0.05)CONCLUSIONERT does not halt the clinical evolution of several ocular manifestations. Longer observational time may be required to fully confirm these findings.

scholarly journals Linear end-systolic pressure-volume relationship during pulsatile left ventricular bypass represents native heart function

1995 ◽  
Vol 109 (4) ◽  
pp. 780-786 ◽  
Author(s):  
Osamu Kawaguchi ◽  
John S. Sapirstein ◽  
William B. Daily ◽  
Walter E. Pae ◽  
William S. Pierce
Keyword(s):  
Heart Function ◽  
Systolic Pressure ◽  
Left Ventricular ◽  
Volume Relationship ◽  
Pressure Volume Relationship

scholarly journals Under Pressure: Intraluminal Filling Pressures of Postpartum Hemorrhage Tamponade Balloons

2017 ◽  
Vol 07 (02) ◽  
pp. e86-e92 ◽  
Author(s):  
Kathleen Antony ◽  
Diana Racusin ◽  
Michael Belfort ◽  
Gary Dildy
Keyword(s):  
Postpartum Hemorrhage ◽  
Ex Vivo ◽  
Volume Ratio ◽  
Intraluminal Pressure ◽  
Acute Hemorrhage ◽  
Volume Relationship ◽  
Pressure Volume Relationship ◽  
Relationship Of ◽  
Condom Catheter ◽  
Filling Capacity

Objective Uterine tamponade by fluid-filled balloons is now an accepted method of controlling postpartum hemorrhage. Available tamponade balloons vary in design and material, which affects the filling attributes and volume at which they rupture. We aimed to characterize the filling capacity and pressure-volume relationship of various tamponade balloons. Study Design Balloons were filled with water ex vivo. Intraluminal pressure was measured incrementally (every 10 mL for the Foley balloons and every 50 mL for all other balloons). Balloons were filled until they ruptured or until 5,000 mL was reached. Results The Foley balloons had higher intraluminal pressures than the larger-volume balloons. The intraluminal pressure of the Sengstaken-Blakemore tube (gastric balloon) was initially high, but it decreased until shortly before rupture occurred. The Bakri intraluminal pressure steadily increased until rupture occurred at 2,850 mL. The condom catheter, BT-Cath, and ebb all had low intraluminal pressures. Both the BT-Cath and the ebb remained unruptured at 5,000 mL. Conclusion In the setting of acute hemorrhage, expeditious management is critical. Balloons that have a low intraluminal pressure-volume ratio may fill more rapidly, more easily, and to greater volumes. We found that the BT-Cath, the ebb, and the condom catheter all had low intraluminal pressures throughout filling.

Sign in / Sign up

Export Citation Format

Share Document