scholarly journals Diffusion in Replica Healthy and Emphysematous Alveolar Models Using Computational Fluid Dynamics

2013 ◽  
Vol 2013 ◽  
pp. 1-9 ◽  
Author(s):  
Edward M. Harding ◽  
Emily J. Berg ◽  
Risa J. Robinson
Keyword(s):  
Steady State ◽  
Airway Remodeling ◽  
Three Dimensional ◽  
Gas Barrier ◽  
Nanoparticle Deposition ◽  
Dimensional Reconstruction ◽  
Steady State Simulation ◽  
Diseased Lung ◽  
Convective Diffusion Equation

Deposition of nanosized particles in the pulmonary region has the potential of crossing the blood-gas barrier. Experimental in vivo studies have used micron-sized particles, and therefore nanoparticle deposition in the pulmonary region is not well understood. Furthermore, little attention has been paid to the emphysematous lungs, which have characteristics quite different from the healthy lung. Healthy and emphysematous replica acinus models were created from healthy and diseased human lung casts using three-dimensional reconstruction. Particle concentration and deposition were determined by solving the convective-diffusion equation numerically for steady and unsteady cases. Results showed decreased deposition efficiencies for emphysema compared to healthy lungs, consistent with the literature and attributed to significant airway remodeling in the diseased lung. Particle diffusion was found to be six times slower in emphysema compared to healthy model. The unsteady state simulation predicted deposition efficiencies of 96% in the healthy model for the 1 nm and 3 nm particles and 94% and 93% in the emphysema model for the 1 nm and 3 nm particles, respectively. Steady state was achieved in less than one second for both models. Comparisons between steady and unsteady predictions indicate that a steady-state simulation is reasonable for predicting particle transport under similar conditions.

scholarly journals Measurements of the wall shear stress distribution in the outflow tract of an embryonic chicken heart

2009 ◽  
Vol 7 (42) ◽  
pp. 91-103 ◽  
Author(s):  
C. Poelma ◽  
K. Van der Heiden ◽  
B. P. Hierck ◽  
R. E. Poelmann ◽  
J. Westerweel
Keyword(s):  
Shear Stress ◽  
Wall Shear Stress ◽  
Three Dimensional ◽  
Outflow Tract ◽  
Chicken Heart ◽  
Embryonic Chicken ◽  
Dimensional Reconstruction ◽  
Wall Shear ◽  
Embryo Heart

In order to study the role of blood–tissue interaction in the developing chicken embryo heart, detailed information about the haemodynamic forces is needed. In this study, we present the first in vivo measurements of the three-dimensional distribution of wall shear stress (WSS) in the outflow tract (OFT) of an embryonic chicken heart. The data are obtained in a two-step process: first, the three-dimensional flow fields are measured during the cardiac cycle using scanning microscopic particle image velocimetry; second, the location of the wall and the WSS are determined by post-processing flow velocity data (finding velocity gradients at locations where the flow approaches zero). The results are a three-dimensional reconstruction of the geometry, with a spatial resolution of 15–20 µm, and provides detailed information about the WSS in the OFT. The most significant error is the location of the wall, which results in an estimate of the uncertainty in the WSS values of 20 per cent.

Ultrasonic three-dimensional reconstruction: In vitro and In vivo volume and area measurement

1994 ◽  
Vol 20 (8) ◽  
pp. 719-729 ◽  
Author(s):  
Timothy C. Hodges ◽  
Paul R. Detmer ◽  
David H. Burns ◽  
Kirk W. Beach ◽  
D.Eugene Strandness
Keyword(s):  
Three Dimensional ◽  
Area Measurement ◽  
Three Dimensional Reconstruction ◽  
Dimensional Reconstruction

SIMULATION OF VESSEL STRESS AND SECONDARY FLOWS FOR BLOOD FLOWS THROUGH A REALISTIC AORTA WITH THREE BRANCHES

2007 ◽  
Vol 19 (04) ◽  
pp. 215-223 ◽  
Author(s):  
Yang-Yao Niu ◽  
Pang-Chung Wu ◽  
Wen-Yih I. Tseng ◽  
Hsi-Yu Yu
Keyword(s):  
Secondary Flow ◽  
Aortic Arch ◽  
Three Dimensional ◽  
Wall Stress ◽  
Outer Wall ◽  
Secondary Flows ◽  
Blood Flows ◽  
Flow Recirculation ◽  
Dimensional Reconstruction

Blood secondary flows and vessel wall shear stress distributions in a human aortic arch have been predicted numerically for a Reynolds number of 4700 at entrance. The simulation geometry was derived from a three-dimensional reconstruction of a series of two-dimensional slices obtained in vivo. Numerical results demonstrate wall stresses were highly dynamic, but were generally high along the outer wall in the vicinity of the branches and low along the inner wall, particularly in the descending thoracic aorta. The maximum wall stress distribution is presented on the aortic arch in the systole. Extensive secondary flow motion was observed in the aorta, and the structure of these secondary flows was influenced considerably by the presence of the branches. Within the aorta, it is observed that clockwise secondary flow recirculation, also seen in the MRA scan data, appears in the downstream of aortic arch in the late systole and turn out to be a pair of counter-clockwise vortex in the downstream of the arch in the early diastole.

Direct Observation of Hydroxyapatite Nanoparticles In Vivo

2012 ◽  
Vol 503-504 ◽  
pp. 688-691 ◽  
Author(s):  
Wei Zhou ◽  
Jun Zheng
Keyword(s):  
Positron Emission Tomography ◽  
Real Time ◽  
Pet Imaging ◽  
Three Dimensional ◽  
Transverse Plane ◽  
Emission Tomography ◽  
Hydroxyapatite Nanoparticles ◽  
Positron Emission ◽  
Dimensional Reconstruction

While nano-hydroxyapatite (nano-HAP) has been well known for series of amazing properties in chemical or physical, the controversy on the risks of its applications has also been existed. The worries of nano-HAP applications in preclinic and clinic indicate the blank researches of nano-HAP pharmacodynamics. It is important and necessary to trace and clarify the localizations of HAP nanoparticles in vivo. In the present paper, 18F is used as radiotracer for Positron Emission Tomography (PET) imaging of HAP nanoparticles. Through the transverse plane slices and three-dimensional reconstruction pictures, it is very clear to observe the localization of nano-HAP in vivo at real time. Most nano-HAP particles were noted in organs lump, liver, spleen, stomach and existed for period of time. Therefore, PET can be a new powerful technique for tracing nano-biomaterial and their pharmacodynamics researches.

scholarly journals The Telomerase/Vault-Associated Protein Tep1 Is Required for Vault RNA Stability and Its Association with the Vault Particle

2001 ◽  
Vol 152 (1) ◽  
pp. 157-164 ◽  
Author(s):  
Valerie A. Kickhoefer ◽  
Yie Liu ◽  
Lawrence B. Kong ◽  
Bryan E. Snow ◽  
Phoebe L. Stewart ◽  
...  
Keyword(s):  
Rna Stability ◽  
Three Dimensional ◽  
Telomerase Activity ◽  
Telomerase Rna ◽  
Protein Subunit ◽  
Negative Stain ◽  
Dimensional Reconstruction ◽  
Stable Association ◽  
Vault Rna

Vaults and telomerase are ribonucleoprotein (RNP) particles that share a common protein subunit, TEP1. Although its role in either complex has not yet been defined, TEP1 has been shown to interact with the mouse telomerase RNA and with several of the human vault RNAs in a yeast three-hybrid assay. An mTep1−/− mouse was previously generated which resulted in no apparent change in telomere length or telomerase activity in six generations of mTep1-deficient mice. Here we show that the levels of the telomerase RNA and its association with the telomerase RNP are also unaffected in mTep1−/− mice. Although vaults purified from the livers of mTep1−/− mice appear structurally intact by both negative stain and cryoelectron microscopy, three-dimensional reconstruction of the mTep1−/− vault revealed less density in the cap than previously observed for the intact rat vault. Furthermore, the absence of TEP1 completely disrupted the stable association of the vault RNA with the purified vault particle and also resulted in a decrease in the levels and stability of the vault RNA. Therefore, we have uncovered a novel role for TEP1 in vivo as an integral vault protein important for the stabilization and recruitment of the vault RNA to the vault particle.

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