The Effect of Angle and Flow Rate Upon Hemodynamics in Distal Vascular Graft Anastomoses: A Numerical Model Study

1994 ◽  
Vol 116 (3) ◽  
pp. 331-336 ◽  
Author(s):  
Ding-Yu Fei ◽  
James D. Thomas ◽  
Stanley E. Rittgers
Keyword(s):  
Numerical Model ◽  
Stagnation Point ◽  
Arterial Wall ◽  
Artery Bypass ◽  
Three Dimensional ◽  
Separated Flow ◽  
Reynolds Numbers ◽  
In Vivo Studies ◽  
Stagnation Points

Flow in distal end-to-side anastomoses of iliofemoral artery bypass grafts was simulated using a steady flow, three-dimensional numerical model. With the proximal artery occluded, anastomotic angles were varied over 20, 30, 40, 45, 50, 60 and 70 deg while the inlet Reynolds numbers were 100 and 205. Fully developed flow in the graft became somewhat skewed toward the inner wall with increasing angle for both Reynolds numbers. Separated flow regions were seen along the inner arterial wall (toe region) for angles ≥ 60 deg at Re = 100 and for angles ≥ 45 deg at Re = 205 while a stagnation point existed along the outer arterial wall (floor region) for all cases which moved downstream relative to the toe of the anastomosis with decreasing angles. Normalized shear rates (NSR) along the arterial wall varied widely throughout the anastomotic region with negative values seen in the separation zones and upstream of the stagnation points which increased in magnitude with angle. The NSR increased with distance downstream of the stagnation point and with magnitudes which increased with the angle. Compared with observations from chronic in vivo studies, these results appear to support the hypothesis of greater intimal hyperplasia occurring in regions of low fluid shear.

scholarly journals Three-Dimensional Zirconia-Based Scaffolds for Load-Bearing Bone-Regeneration Applications: Prospects and Challenges

Materials ◽  
2021 ◽  
Vol 14 (12) ◽  
pp. 3207
Author(s):  
Kumaresan Sakthiabirami ◽  
Vaiyapuri Soundharrajan ◽  
Jin-Ho Kang ◽  
Yunzhi Peter Yang ◽  
Sang-Won Park
Keyword(s):  
Bone Regeneration ◽  
Biological Activities ◽  
Three Dimensional ◽  
In Vivo Studies ◽  
High Mechanical Strength ◽  
Real World Applications ◽  
3D Fabrication ◽  
Dental Applications

The design of zirconia-based scaffolds using conventional techniques for bone-regeneration applications has been studied extensively. Similar to dental applications, the use of three-dimensional (3D) zirconia-based ceramics for bone tissue engineering (BTE) has recently attracted considerable attention because of their high mechanical strength and biocompatibility. However, techniques to fabricate zirconia-based scaffolds for bone regeneration are in a stage of infancy. Hence, the biological activities of zirconia-based ceramics for bone-regeneration applications have not been fully investigated, in contrast to the well-established calcium phosphate-based ceramics for bone-regeneration applications. This paper outlines recent research developments and challenges concerning numerous three-dimensional (3D) zirconia-based scaffolds and reviews the associated fundamental fabrication techniques, key 3D fabrication developments and practical encounters to identify the optimal 3D fabrication technique for obtaining 3D zirconia-based scaffolds suitable for real-world applications. This review mainly summarized the articles that focused on in vitro and in vivo studies along with the fundamental mechanical characterizations on the 3D zirconia-based scaffolds.

scholarly journals The Challenging Melanoma Landscape: From Early Drug Discovery to Clinical Approval

Cells ◽  
2021 ◽  
Vol 10 (11) ◽  
pp. 3088
Author(s):  
Mariana Matias ◽  
Jacinta O. Pinho ◽  
Maria João Penetra ◽  
Gonçalo Campos ◽  
Catarina Pinto Reis ◽  
...  
Keyword(s):  
Therapeutic Potential ◽  
Drug Evaluation ◽  
Three Dimensional ◽  
Experimental Models ◽  
In Vivo Studies ◽  
Murine Models ◽  
In Vivo Experiments ◽  
Novel Therapeutic Strategies

Melanoma is recognized as the most dangerous type of skin cancer, with high mortality and resistance to currently used treatments. To overcome the limitations of the available therapeutic options, the discovery and development of new, more effective, and safer therapies is required. In this review, the different research steps involved in the process of antimelanoma drug evaluation and selection are explored, including information regarding in silico, in vitro, and in vivo experiments, as well as clinical trial phases. Details are given about the most used cell lines and assays to perform both two- and three-dimensional in vitro screening of drug candidates towards melanoma. For in vivo studies, murine models are, undoubtedly, the most widely used for assessing the therapeutic potential of new compounds and to study the underlying mechanisms of action. Here, the main melanoma murine models are described as well as other animal species. A section is dedicated to ongoing clinical studies, demonstrating the wide interest and successful efforts devoted to melanoma therapy, in particular at advanced stages of the disease, and a final section includes some considerations regarding approval for marketing by regulatory agencies. Overall, considerable commitment is being directed to the continuous development of optimized experimental models, important for the understanding of melanoma biology and for the evaluation and validation of novel therapeutic strategies.

scholarly journals Potential anticancer activity of curcumin analogs containing sulfone on human cancer cells

2016 ◽  
Vol 68 (1) ◽  
pp. 125-133 ◽  
Author(s):  
Qiuyan Zhang ◽  
Dongli Li ◽  
Yue Liu ◽  
Hui Wang ◽  
Changyuan Zhang ◽  
...  
Keyword(s):  
Prostate Cancer ◽  
Human Cancer ◽  
Three Dimensional ◽  
In Vivo Studies ◽  
Anticancer Activities ◽  
Human Cancer Cells ◽  
Curcumin Analogs ◽  
Phosphorylated Akt ◽  
Transcription 3

Three curcumin analogs(S1-S3) containing sulfone were investigated for their effects on human prostate cancer PC-3, colon cancer HT-29, lung cancer H1299 and pancreatic cancer BxPC-3 cells. The three compounds were approximately 16-to 96-fold more active than curcumin in these cell lines as determined by the MTT assay. The effects of these compounds on cell growth were further studied in prostate cancer PC-3 cells in both two dimensional (2D) and three dimensional (3D) cultures. S1-S3strongly inhibited the growth and induced cell death in PC-3 cells, and the effects of these compounds were associated with suppression of nuclear factor kappa B (NF-?B) transcriptional activity. Moreover, treatment of PC-3 cells with all three compounds caused a decrease in the level of phosphorylated signal transducer and activator of transcription-3 (p-STAT3) (Tyr705),but not p-STAT3(Ser727). Only S1and S2decreased the presence of phosphorylated Akt (p-Akt) in PC-3 cells. These curcumin analogs warrant further in vivo studies for anticancer activities in suitable animal models.

The Effect of Arterial Wall Deformability on Hemodynamics of CABG

2008 ◽  
Author(s):  
Esfandyar Kouhi ◽  
Yos Morsi ◽  
S. H. Masood
Keyword(s):  
Degrees Of Freedom ◽  
Arterial Wall ◽  
Artery Bypass ◽  
Three Dimensional ◽  
Rigid Wall ◽  
Hemodynamic Forces ◽  
Velocity Magnitude ◽  
Hyper Elastic ◽  
Rigid Model ◽  
Rigid Walls

In this study, hemodynamic forces in a three-dimensional (3D) computational model of Coronary Artery Bypass Grafting (CABG) with deformable and rigid walls were compared. A physiologic pulsatile non-Newtonian blood flow was considered in the arteries for both models. The artery walls in the distensible model were considered to be hyper-elastic with nonlinear strain dependent Young’s module and axial and radial degrees of freedom, while the deformability in all directions of the rigid model was restricted. The velocity distributions and magnitudes, vortex motions and the occurrence of recirculation zones were selected as the primary hemodynamic parameters in order to show the effect of deformability in the arterial wall and in calculating differences versus the rigid wall model. It was found that during systolic, the velocity magnitude at the host artery bed could vary by up to 80% depending on the longitudinal distance from the center of the anastomosis junction.

Three-dimensional study of separated flow over a square cylinder by large eddy simulation

2005 ◽  
Vol 219 (3) ◽  
pp. 225-234 ◽  
Author(s):  
M Farhadi ◽  
M Rahnama
Keyword(s):  
Large Eddy Simulation ◽  
Three Dimensional ◽  
Separated Flow ◽  
Reynolds Numbers ◽  
Square Cylinder ◽  
Mean Flow ◽  
Central Difference ◽  
Eddy Simulation ◽  
Flow Parameters ◽  
Large Eddy

Large eddy simulation of flow over a square cylinder in a channel is performed at Reynolds numbers of 22 000 and 21 400. The selective structure function (SSF) modelling of the subgrid-scale stress terms is used and the convective terms are discretized using quadratic upstream interpolation for convective kinematics (QUICK) and central difference (CD) schemes. A series of time-averaged velocities, turbulent stresses, and some global flow parameters such as lift and drag coefficients and their fluctuations are computed and compared with experimental data. The suitability of SSF model has been shown by comparing the computed mean flow velocities and turbulent quantities with experiments. Results show negligible variation in the flow parameters for the two Reynolds numbers used in the present computations. It was observed that both QUICK and CD schemes are capable of obtaining results close to those of the experiments with some minor differences.

Kinematics of the Midtarsal Joint During Standing Leg Rotation

2002 ◽  
Vol 92 (2) ◽  
pp. 77-81 ◽  
Author(s):  
Christopher Nester ◽  
Peter Bowker ◽  
Peter Bowden
Keyword(s):  
Range Of Motion ◽  
Three Dimensional ◽  
In Vivo Studies ◽  
Kinematic Data ◽  
Joint Characteristics ◽  
Infrared Cameras ◽  
Cadaver Studies ◽  
Midtarsal Joint ◽  
Invasive Techniques

Building on previous work that was cadaver based or involved invasive techniques, this study quantifies the kinematics of an approximation of the midtarsal joint with a noninvasive method. Three-dimensional kinematic data describing the motion of the forefoot and heel during transverse plane rotation of the leg were collected from 25 subjects by means of reflective markers and four infrared cameras. The motion between these segments was assumed to be the best possible clinical approximation of the midtarsal joint. The kinematic characteristics of the midtarsal joint were described in terms of the range and direction of motion in each cardinal body plane, the ratio of the range of motion in each plane, and the orientation of the axis of rotation. The characteristics of the midtarsal joint changed during the range of motion; thus, multiple axes of rotation could be calculated and joint characteristics were varied among subjects. The results of this in vivo method were generally consistent with those of cadaver studies and invasive in vivo studies. (J Am Podiatr Med Assoc 92(2): 77-81, 2002)

scholarly journals Accuracy of aortic annular measurements obtained from three-dimensional echocardiography, CT and MRI: human in vitro and in vivo studies

Heart ◽  
2012 ◽  
Vol 98 (15) ◽  
pp. 1146-1152 ◽  
Author(s):  
Wendy Tsang ◽  
Michael G Bateman ◽  
Lynn Weinert ◽  
Gian Pellegrini ◽  
Victor Mor-Avi ◽  
...  
Keyword(s):  
Three Dimensional ◽  
In Vivo Studies ◽  
Dimensional Echocardiography ◽  
Three Dimensional Echocardiography ◽  
Ct And Mri
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