The impact of valve simplifications on left ventricular hemodynamics in a three dimensional simulation based on in vivo MRI data

2016 ◽  
Vol 49 (9) ◽  
pp. 1482-1489 ◽  
Author(s):  
Ali Imanparast ◽  
Nasser Fatouraee ◽  
Farhad Sharif
Keyword(s):  
Three Dimensional ◽  
Left Ventricular ◽  
Simulation Based ◽  
Dimensional Simulation ◽  
The Impact

Three-Dimensional Simulation for Perikinetic Flocculation of Fine Sediment under the Ionization in Still Water

2011 ◽  
Vol 356-360 ◽  
pp. 2282-2290
Author(s):  
Lin Shuang Liu ◽  
Xin Luo ◽  
Guo Lu Yang ◽  
Ming Hui Yu
Keyword(s):  
Electrostatic Force ◽  
Three Dimensional ◽  
Fine Sediment ◽  
Radius Of Gyration ◽  
Brownian Dynamic ◽  
System A ◽  
Simulation Based ◽  
Dimensional Simulation ◽  
Original Cell ◽  
Random Variation

A simulation based on Brownian dynamic for perikinetic flocculation of fine sediment under the ionization is presented. The Langevin equation is used as dynamical equation for tracking each particle making up a floc. Monte Carlo method was used for simulate random variation in particle movement. An initial condition and periodic boundary condition which conformed to reality well is used for calculation. In each cell 1000 particles of 10𝝁 m, 15𝝁m, 20𝝁m, 25𝝁m, 30𝝁m in diameter were served as primary particles. Floc growth is based on the thermal force and the electrostatic force. The electrostatic force on a particle in the simulation cell is considered as a sum of the electrostatic force from other particles in the original cell. The particles are supposed to be motion with uncharged and charged state in dispersion system. A comparison of the initial flocculent time and smashing time in sludge density 1010kg/m3, 1025 kg/m3, 1050 kg/m3, 1075 kg/m3, 1100 kg/m3were present to show the effect of it on floc growth. The increase of sludge density deferred the flocculation rate. To study morphological shape of floc, the radius of gyration was revealed under different situations. On one hand the radius of gyration presented random variation with uncharged particle, On the other hand, the radius of gyration increases gradually with the increase of polar electrical charges on primal particle. Moreover, the morphological shape for the charged floc was more open than that of unchanged state. Finally, a series of experimental results are present, which is coincide with model well.

Influence of structural geometry on the severity of bicuspid aortic stenosis

2004 ◽  
Vol 287 (3) ◽  
pp. H1410-H1416 ◽  
Author(s):  
Kathryn E. Richards ◽  
Dimitri Deserranno ◽  
Erwan Donal ◽  
Neil L. Greenberg ◽  
James D. Thomas ◽  
...  
Keyword(s):  
Pressure Loss ◽  
Three Dimensional ◽  
Left Ventricular ◽  
Pressure Recovery ◽  
Orifice Diameter ◽  
Local Geometry ◽  
Reduced Pressure ◽  
Orifice Area ◽  
Area Functional ◽  
The Impact

Doppler-derived gradients may overestimate total pressure loss in degenerative and prosthetic aortic valve stenosis (AS) due to unaccounted pressure recovery distal to the orifice. However, in congenitally bicuspid valves, jet eccentricity may result in a higher anatomic-to-effective orifice contraction ratio, resulting in an increased pressure loss at the valve and a reduced pressure recovery distal to the orifice leading to greater functional severity. The objective of our study was to determine the impact of local geometry on the total versus Doppler-derived pressure loss and therefore the assessed severity of the stenosis in bicuspid valves. On the basis of clinically obtained measurements, two- and three-dimensional computer simulations were created with various local geometries by altering the diameters of the left ventricular outflow tract (LVOT; 1.8–3.0 cm), orifice diameter (OD; 0.8–1.6 cm), and aortic root diameter (AR; 3.0–5.4 cm). Jet eccentricity was altered in the models from 0 to 25°. Simulations were performed under steady-flow conditions. Axisymmetric simulations indicate that the overall differences in pressure recovery were minor for variations in LVOT diameter (<3%). However, both OD and AR had a significant impact on pressure recovery (6–20%), with greatest recovery being the larger OD and the smaller recovery being the AR. In addition, three-dimensional data illustrate a greater pressure loss for eccentric jets with the same orifice area, thus increasing functional severity. In conclusion, jet eccentricity results in greater pressure loss in bicuspid valve AS due to reduced effective orifice area. Functional severity may also be enhanced by larger aortic roots, commonly occurring in these patients, leading to reduced pressure recovery. Thus, for the same anatomic orifice area, functional severity is greater in bicuspid than in degenerative tricuspid AS.

Impact of Cavity on Sunroof Buffeting: A Two Dimensional CFD Study

2004 ◽  
Author(s):  
Chang-Fa An ◽  
Seyed Mehdi Alaie ◽  
Michael S. Scislowicz
Keyword(s):  
Fluid Dynamics ◽  
Wind Tunnel ◽  
Three Dimensional ◽  
Leading Edge ◽  
Two Dimensional ◽  
Deep Insight ◽  
Simulation Results ◽  
Dimensional Simulation ◽  
The Impact ◽  
Insight Into

Driven by fluid dynamics principles, the concept for buffeting reduction, a cavity installed at the leading edge of the sunroof opening, is analyzed. The cavity provides a room to hold the vortex, shed from upstream, and prevents the vortex from escaping and from directly intruding into the cabin. The concept has been verified by means of a two dimensional simulation for a production SUV using the CFD software — FLUENT. The simulation results show that the impact of the cavity is crucial to reduce buffeting. It is shown that the buffeting level may be reduced by 3 dB by adding a cavity to the sunroof configuration. Therefore, the cavity could be considered as a means of buffeting reduction, in addition to the three currently-known concepts: wind deflector, sunroof glass comfort position and cabin venting. Thorough understanding of the buffeting mechanism helps explain why and how the cavity works to reduce buffeting. Investigation of the buffeting-related physics provides a deep insight into the flow nature and, therefore, a useful hint to geometry modification for buffeting reduction. The buffeting level may be further reduced by about 4 dB or more by cutting the corners of the sunroof opening into smooth ramps, guided by ideas coming from careful examining the physics of flow. More work including three dimensional simulation and wind tunnel experiment should follow in order to develop more confidence in the functionality of the cavity to hopefully promote this idea to the level that it can be utilized in a feasible way to address sunroof buffeting.

Rogue Wave Impact on a Semi-Submersible Offshore Platform

2008 ◽  
Author(s):  
Murray Rudman ◽  
Paul Cleary ◽  
Justin Leontini ◽  
Matthew Sinnott ◽  
Mahesh Prakash
Keyword(s):  
Rogue Wave ◽  
Three Dimensional ◽  
Breaking Waves ◽  
Attractive Alternative ◽  
Wave Impact ◽  
Particle Hydrodynamics ◽  
Smoothed Particle ◽  
Dimensional Simulation ◽  
The Impact ◽  
Structural Motion

Full three-dimensional simulation of the impact of a rogue wave on a semi-submersible platform is undertaken using the Smoothed Particle Hydrodynamics (SPH) technique. Two different mooring configurations are considered: A Tension Leg Platform (TLP) system and a Taut Spread Mooring (TSM) system. It is seen that for a wave impact normal to the platform side, the heave and surge responses of the platform are significantly different for the two mooring systems. The TLP system undergoes large surge but comparatively smaller heave motions than the TSM system. The degree of pitch is very similar. The total tension in the mooring cables is approximately four times higher in the TSM system and exceeds the strength of the cables used in the simulation. SPH is seen to be an attractive alternative to standard methods for simulating the coupled interaction of highly non-linear breaking waves and structural motion.

scholarly journals Hoxblinc Is Aberrantly Expressed in Acute Myeloid Leukemia and Functions As a Potent Oncogenic Long Non-Coding RNA in Leukemogenesis

Blood ◽  
2018 ◽  
Vol 132 (Supplement 1) ◽  
pp. 886-886
Author(s):  
Ganqian Zhu ◽  
Huacheng Luo ◽  
Shi Chen ◽  
Qian Lai ◽  
Ying Guo ◽  
...  
Keyword(s):  
Mononuclear Cells ◽  
Conflicts Of Interest ◽  
Flow Cytometric Analysis ◽  
Three Dimensional ◽  
Donor Cell ◽  
Lower Percentage ◽  
Leukemic Transformation ◽  
Aberrant Expression ◽  
The Impact

Abstract Aberrant expression of long non-coding RNAs (lncRNAs) might contribute to the development and progression of leukemia. However, functional studies on the actual role of lncRNAs during the development of leukemia remain scarce, and very few lncRNAs have been shown to be involved in leukemogenesis. HoxBlinc is an anterior HoxB gene-associated intergenic lncRNA. It is a cis-acting lncRNA and functions as an epigenetic regulator to coordinate anterior HoxB gene expression. Giving the dysregulation of HOXA/B genes is a dominant mechanism of leukemic transformation, HoxBlinc might be an oncogenic lncRNA of leukemia. To determine whether HOXBLINC lncRNA is aberrantly expressed in human AML samples, we performed RT-qPCR on bone marrow mononuclear cells (BMMNCs) from a cohort of 73 AML patients. A dramatic up-regulation of HOXBLINC was observed in over 60% of the patients. When TCGA-AML datasets of a cohort of 179 AML patients were analyzed for their HOXBLINC expression, a significant portion of these AML patients had high levels of HOXBLINC expression. Interestingly, AML patients with high HOXBLINC expression (the top thirty percentile of patients) had a significantly shortened survival as compared to patients with low HOXBLINC expression (the bottom thirty percentile). To investigate the impact of HoxBlinc overexpression on normal hematopoiesis and the pathogenesis of hematological malignancies in vivo, we generated a HoxBlinc transgenic(Tg) mouse model. Within 1 year of age, 67% of the HoxBlincTg mice (10 of 15) died or were sacrificed because of a moribund condition due to AML. We then assessed whether overexpression of HoxBlinc affects the pools of HSC/HPCs by flow cytometric analysis on the BM cells of young WT and HoxBlincTg mice (8-10 weeks of age). HoxBlincTg BM had a dramatically greater number of LT-HSC, ST-HSC, MPP cells, and a significantly higher percentage of GMP, but a lower percentage of MEP/CMP cell populations as compared to WT group. To determine the effect of HoxBlinc overexpression on the function of HSC/HPCs, we performed paired-daughter cell assay, replating assay and liquid culture on sorted LT-HSC, LSK or LK cells from young WT and HoxBlincTg mice, the results indicate that transgenic expression of HoxBlinc enhances HSC self-renewal and impairs HSC/HPC differentiation. To assess whether HoxBlinc overexpression-mediated changes in HSC/HPC function are cell-autonomous, we performed competitive transplantation assays to examine the repopulating capacity of HoxBlincTg BM cells. When the donor cell chimerism was analyzed kinetically in the PB of recipient mice, the CD45.2 cell population remained ~50% in mice receiving WT BM cells, whereas the CD45.2 chimerism in the recipients transplanted with HoxBlincTg BM cells steadily increased. Interestingly, mice receiving HoxBlincTg BM cells developed AML at 2-6 months after transplantation. Previous data reported that HoxBlinc can recruit the Setd1a/Mll1 histone H3K4 methyltransferase complex to mediate formation of the active topologically associated domain (TAD) in the anterior HoxB locus for transcription of the anterior HoxB genes. In this study, LSK or LK cells sorted from young WT and HoxBlincTg mice were analyzed by RNA-seq, ATAC-seq, H3K4me3 CHIP-seq and 4C analysis. Mechanistically, HoxBlinc overexpression alters HoxB locus chromatin three-dimensional organization to enhance enhancer/promoter chromatin accessibility and coordinate the expression of not only HoxB1-5 but also HoxA9, Runx1, Meis1 and so on, which are critical genes for HSC regulation and/or leukemogenesis. Our study provides novel insights into the HSC regulation by lncRNAs and identifies HOXBLINC, which coordinates to maintain an oncogenic transcription program for leukemic transformation, as a potent oncogenic lncRNA in leukemogenesis. Disclosures No relevant conflicts of interest to declare.

scholarly journals Human induced pluripotent stem cell-derived three-dimensional cardiomyocyte tissues ameliorate the rat ischemic myocardium by remodeling the extracellular matrix and cardiac protein phenotype

PLoS ONE ◽  
2021 ◽  
Vol 16 (3) ◽  
pp. e0245571
Author(s):  
Junya Yokoyama ◽  
Shigeru Miyagawa ◽  
Takami Akagi ◽  
Mitsuru Akashi ◽  
Yoshiki Sawa
Keyword(s):  
Myocardial Infarction ◽  
Extracellular Matrix ◽  
Pluripotent Stem Cell ◽  
Heart Function ◽  
Three Dimensional ◽  
Induced Pluripotent Stem Cell ◽  
Left Ventricular ◽  
Induced Pluripotent

The extracellular matrix (ECM) plays a key role in the viability and survival of implanted human induced pluripotent stem cell-derived cardiomyocytes (hiPSC-CMs). We hypothesized that coating of three-dimensional (3D) cardiac tissue-derived hiPSC-CMs with the ECM protein fibronectin (FN) would improve the survival of transplanted cells in the heart and improve heart function in a rat model of ischemic heart failure. To test this hypothesis, we first explored the tolerance of FN-coated hiPSC-CMs to hypoxia in an in vitro study. For in vivo assessments, we constructed 3D-hiPSC cardiac tissues (3D-hiPSC-CTs) using a layer-by-layer technique, and then the cells were implanted in the hearts of a myocardial infarction rat model (3D-hiPSC-CTs, n = 10; sham surgery control group (without implant), n = 10). Heart function and histology were analyzed 4 weeks after transplantation. In the in vitro assessment, cell viability and lactate dehydrogenase assays showed that FN-coated hiPSC-CMs had improved tolerance to hypoxia compared with the control cells. In vivo, the left ventricular ejection fraction of hearts implanted with 3D-hiPSC-CT was significantly better than that of the sham control hearts. Histological analysis showed clear expression of collagen type IV and plasma membrane markers such as desmin and dystrophin in vivo after implantation of 3D-hiPSC-CT, which were not detected in 3D-hiPSC-CMs in vitro. Overall, these results indicated that FN-coated 3D-hiPSC-CT could improve distressed heart function in a rat myocardial infarction model with a well-expressed cytoskeletal or basement membrane matrix. Therefore, FN-coated 3D-hiPSC-CT may serve as a promising replacement for heart transplantation and left ventricular assist devices and has the potential to improve survivability and therapeutic efficacy in cases of ischemic heart disease.

Left ventricle: systolic function

2016 ◽  
Author(s):  
Bernard Cosyns ◽  
Thor Edvardsen ◽  
Krasimira Hristova ◽  
Hyung-Kwan Kim
Keyword(s):  
Systolic Function ◽  
Imaging Modality ◽  
Correct Diagnosis ◽  
Three Dimensional ◽  
Daily Practice ◽  
Left Ventricular ◽  
Severe Arrhythmia ◽  
Dimensional Echocardiography ◽  
Lv Systolic Function

The assessment of left ventricular (LV) systolic function is one of the most important parts of correct diagnosis, selection of treatment strategy or medications, and prediction of prognosis. Although cardiac magnetic resonance imaging is generally accepted as the gold standard in vivo imaging modality for assessing LV systolic function, its practical use is limited due to its limited availability, high cost, and the presence of conditions precluding its performance such as a pacemaker, claustrophobia, and severe arrhythmia. Thus, transthoracic echocardiography is a first-line imaging modality employed in daily practice and has been widely used. Since the first attempts with M-mode approach, remarkable improvements have been made with the advent of two-dimensional echocardiography, and more recently three-dimensional echocardiography, with high accuracy and reproducibility. More sophisticated methodologies such as strain imaging, based on Doppler or speckle tracking techniques, provide a more sensitive and quantitative measurement of myocardial contractility, and are gaining a place in common daily practice. This chapter describes different modalities that have been used for assessment of LV systolic function based on echocardiography, and is grossly composed of two parts: LV global systolic function and LV regional or segmental systolic function. For better application of these conventional and novel methods of assessing LV systolic function, strengths and pitfalls of these techniques should be acknowledged.

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