bluuebunny/crossref_metadata_2025_split huggingface dataset:
The Effect of Disc Degeneration on the Kinematic Characteristics of the Lumbar Motion Segment
Authors: Lim Tae-Hong , An Howard S. , Hong Jung Hwa , Yoshida Hyroyuki 
Published: July 2023

Abstract
Degenerative processes of the lumbar motion segment involve aging and degenerative changes of the intervertebral disc and facet joints. The classification most widely used for grading the disc degeneration was based upon the appearance of the disc in the horizontal section.4 Limitations of this grading scheme includes no assessment of changes in the end-plate and vertebral body, insufficient categories to distinguish wide range of appearances encountered, and the lack of tested validity of the scheme.7 Recently, Thompson et al.7 proposed a five-category grading scheme for assessing the gross morphology of midsagittal sections of the intervertebral disc.
Tissue Engineering: A Review
Authors: Ranieri John P. 
Published: July 2023

Abstract
Tissue engineering is defined as the in vitro or in vivo creation or regeneration of differentiated tissue for the clinical replacement of a compromised body structure. The ultimate goal of tissue engineering is to reconstruct an organ by taking advantage of recent progress in molecular biology (i.e., mechanisms controlling cell differentiation and gene transfer), materials science (development of “smart” and bioresorbable polymers), and surgical techniques. Tissue engineering is not so much a science in the traditional sense, but an amalgam of technologies from disparate fields that are grouped such that clinically relevant tissue replacement therapies may result.
Development, Manufacture and Clinical Testing of an Engineered Tissue: Experience With Human Skin
Authors: Parenteau Nancy L. 
Published: July 2023

Abstract
Development of a cell therapy beyond proof of principle requires overcoming practical as well scientific hurdles. Our experimental and clinical experience has been obtained developing a full-thickness human skin replacement (Graftskin™). Feasible cell sourcing, a scalable culture process, and mode of cell delivery are important to success both in the clinic and the marketplace. The ability to create working cell banks of the needed cell population allows reproducible manufacture of a complex tissue. For example, specialized keratinocyte cultivation techniques enable the production of approximately 200,000, 44 cm2 units of Graftskin using cells cultivated from one 1.5 cm2 infant foreskin.
A Mathematical Model of the Circulation in the Presence of a Bidirectional Cavopulmonary Anastomosis: Hemodynamics and Oxygen Concentration
Authors: Pennati Giancarlo , Migliavacca Francesco , Dubini Gabriele , Fumero Roberto , de Leval Marc R. 
Published: July 2023

Abstract
A mathematical model of the circulation was developed to study the hemodynamics in the presence of the bidirectional cavopulmonary anastomosis (BCPA). Computer simulations were conducted to evaluate the influence of an additional source of blood flow (ABF) from the native pulmonary artery on the hemodynamics and the oxygen concentration in the upper part of the body.
Effects of Upstream Curvature on Stenotic Flows
Authors: Bergman Harris L. , Ku David N. 
Published: July 2023

Abstract
Physiologic flows are unsteady and complicated. Fluid mechanics investigations of these flows typically simplify the geometries by assuming smooth, rigid walls and, in some cases, axisymmetry. Stenotic geometries have been of interest because they cause non-typical flow anomalies such as head loss and turbulence. Most studies with stenotic geometries have used axisymmetric stenoses with straight inlets. Both experimental and numerical results thus show only one jet configuration: with the jet staying along the centerline. Another stable configuration is for the jet to stick to a wall. Note that, in vivo, there are no perfectly straight vessels. In fact, stenoses which present morbidity and mortality typically originate downstream of bifurcations. After bifurcating, the flow in each branch is characterized by skewing of the velocity profile and by secondary flows. It is therefore necessary to ask how different is the post stenotic flow field when upstream curvature is present.
Analysis of Fluid Mechanical Energy Losses in Aortic Valve Stenosis
Authors: Heinrich Russell S. , Fontaine Arnold A. , Grimes Randall Y. , Moore Kristin E. , Levine Robert A. , Yoganathan Ajit P. 
Published: July 2023

Abstract
Aortic valve stenosis occurs when the aortic valve does not open fully during systole, thus creating an obstruction to blood flow leaving the left ventricle. Maximum orifice pressure drop and valve orifice area are the primary clinical indicators of the severity of aortic stenosis. Pressure drop can be measured by catheter insertion or calculated with the modified Bernoulli equation from Doppler ultrasound velocity measurements. Unfortunately there are discrepancies between the two techniques that are often attributed to pressure recovery downstream of stenotic aortic valves [Levine et al, 1989]. The relationship between orifice pressure drop and left ventricular function is ambiguous. This has been emphasized in a recent paper by Vandervoort et al [1996], which states, “Although maximum, transvalvular, and net pressure gradients are all different gradients that physically exist, it is currently not known which of these gradients is most relevant to reflect the work load imposed on the heart”. Since it has been shown that left ventricular function has a significant effect on post-operative recovery [Ross, 1985], it is imperative that the severity of aortic valve stenosis be evaluated in terms of left ventricular work capacity. Therefore, the purpose of this study was to determine the relationship between left ventricular work and pressure drop measurements in aortic stenosis. The hypothesis that motivated this study was that the left ventricle performs work to overcome energy losses caused by aortic valve stenosis, and the pressure drop that most accurately represents this work should be used for clinical assessment of aortic stenosis.
Sensitivity of Endothelial Cell Response to the Onset Rate of Shear Stress
Authors: Blackman Brett R. , LaPlaca Michelle C. , Barbee Kenneth A. , Thibault Lawrence E. 
Published: July 2023

Abstract
Bovine pulmonary aortic endothelial cells (BPAEC) exposed to controlled levels of fluid shear stress in the absence of ATP exhibited transient intracellular free calcium (Ca2+i) responses that were sensitive to the onset rate of shear stress (ORSS). A coaxial parallel-disk device was used to control the application of a high (&gt;900 dyn/cm s−1) or low (&lt; 6 dyn/cm s−1) ORSS. The high rate elicited greater peak responses and final levels of intracellular free calcium concentrations, [Ca2+]i, compared to the low rate. The ORSS appears to be an important parameter characterizing the mechanical environment of endothelial cells and may play a role in their differential responses in disturbed versus undisturbed flow regions.
Model Studies on the Origination of Pseudo-Regurgitation During Heart Valve Closure
Authors: Talukder Niranjan K. , Komerath Narayanan M. 
Published: July 2023

Abstract
The role of back flow or regurgitation in heart valve closure has been a matter of controversy for a long time. According to Bellhouse and Bellhouse (1969) a little back flow is necessary to close a heart valve and vortices play a crucial role in minimizing the back flow through heart valves. Talukder et al. (1977) advanced the hypothesis that under pulsatile flow valve closure may take place without the least regurgitation. Reul et al. (1981) demonstrated that, the flow pulsatility being maintained, valve movements remain practically unchanged in absence of vortices near the valve. They pointed out the important roles of the adverse pressure gradient during flow deceleration. Recent studies by Talukder and Komerath (1995) using flow visualization and Spatial Correlation Velocimetry (SCV) showed that, after the onset of flow deceleration, the valve leaflets are accelerated towards closure while the flow in the valve aperture is still forward. The present paper provides evidence for the fact that forward flow through the valve aperture persists even when the net flow across the valve root is reversed and attempts to explain the origination of this reversed flow.
Effect of Shear Stress on Albumin Uptake Into Cultured Endothelial Cells
Authors: Kudo Susumu , Ikezawa Kenji , Matsumura Shinji , Ikeda Mariko , Oka Kotaro , Tanishita Kazuo 
Published: July 2023

Abstract
The endothelial cell monolayer exposed to shear stress by a blood flow in vivo is a principal barrier for macromolecules transport across the vascular wall. Abnormal uptake of macromolecules into endothelial cell monolayer causes several vascular diseases. Therefore we studied the effect of shear stress on macromolecules uptake into cultured endothelial cells. After 48hr. exposure to shear stress, endothelial cells on coverslips were incubated at 37°C for 60 minutes in PBS containing Tetrametylrhodamine Isothiocyanate conjugated Albumin (TRITC-Albumin). Thereafter the uptake of albumin and the shape of endothelial cells were observed by a laser scanning confocal microscope. The uptake of albumin into endothelial cells exposed to shear stress increased for lower shear stress range and decreased for high shear stress.
Determination of Stresses and Strains in Heterogeneous, Diseased Human Aorta
Authors: Beattie Deborah K. , Vito Raymond P. , Xu Chengpei , Glagov Seymour 
Published: July 2023

Abstract
Atherosclerosis continues to be a leading cause of death and disability in this and other western industrialized nations. Although little is known regarding the relationships between stresses and strains in the arterial wall and disease etiology, one of the most clinically relevant issues is the stability of the established plaque. In this research, an experimental technique was developed to determine the finite strain field in heterogeneous, diseased arterial cross-sections in vitro. The distribution of histologic attributes such as lipid accumulations, regions of calcification, and the plaque fibrous cap is quantified. By coupling experimental and histologic data in a finite element analysis, plaque mechanical properties, stresses, and strain energies can be determined using an optimization approach. Such results form a basis for establishing links between the composition of diseased vessels and plaque failure in vivo.
Hemodynamics of the Total Cavopulmonary Connection: An In-Vitro Study
Authors: Kim Sang Hyun , Park Young Hwan , Cho Bum Ku , Hong Yoo Sun 
Published: July 2023

Abstract
Total cavopulmonary (CP) connection has been developed to treat hearts with essentially a single ventricular chamber[1]. In a typical CP connection, the superiour vena cava (SVC) and inferior vena cava (IVC) are connected directly to the right pulmonary artery (RPA). High incidence of failures occurred due to fibromuscular ingrowth, valvular degeneration and pseudo-intimal peel formation. All of which depend upon the hemodynamics of the connection through the presence of stasis, wall shear stress or energy loss due to the conduits. There is very little in-vitro study on the hemodynamics of the CP connection[2,3]. In terms of the local fluid dynamics, the surgically created circuit should not cause blood flow abnomalities. It is important to obtain quantitative informations to optimise the hemodynamic design of the CP connection. The objective of this study is to compare the flow fields across the models of the CP connection.
Effects of Ventricular Overloading on Multiaxial Mechanics in Passive Myocardium
Authors: Emery Jeff L. , Omens Jeffrey H. , McCulloch Andrew D. 
Published: July 2023

Abstract
Passive overstretch of myocardium occurs in the ischemic and dilated heart, but the subsequent changes in local tissue mechanics and structure remain unclear. Therefore, we estimated changes in myocardial biaxial stiffness using by solving an inverse finite element problem. The differences between the strains measured on the epicardium of the isolated rat left ventricle (LV) during overstretch and those of a prolate-spheroidal finite element model were minimized by optimizing the material parameters of an exponential constitutive law. When passive LV pressure was increased from 10 to 120 mmHg, there were progressive decreases in wall stiffness up to 93% that were equal in fiber and cross-fiber directions. Thus, myocardium softens isotropically with progressive overstretch independently of muscle fiber direction. This local strain softening may, therefore, arise from damage to structures with uniform distribution of orientation rather than components aligned with myofibrils.
An Optical System to Determine Axial Surface Strains in Skeletal Muscle
Authors: Best Thomas M. , McElhaney James E. , Garrett William E. , Myers Barry S. 
Published: July 2023

Abstract
Muscle is compliant, undergoes large deformations and demonstrate anisotropic behavior when loaded. The variable amount of specimen slippage can result in error when strain estimates are determined by measures of grip-to-grip motion (Zernicke et al., 1984). In this paper we describe a noncontact optical system and method of analysis to measure full field surface strains in skeletal muscle. The system is used to examine the effect of stretch rate on the distribution of axial strains in rabbit skeletal muscle.
Effects of Aging on Compressive and Laser Scatter Properties of Articular Cartilage
Authors: Athanasiou Kyriacos , Kovach Ian 
Published: July 2023

Abstract
The effects of maturation and aging on the functional characteristics of articular cartilage have not been fully studied. Known age- or maturation-related changes in this tissue’s biochemical constituents include accumulation of hyaluronic acid, chondrocyte modification, proteoglycan alterations, decreased water content, decreased proteoglycan extractability, greater degree of collagen crosslinking, and shortening of the core protein region. Numerous approaches can be employed to quantify age-related changes on the functional properties of articular cartilage. In this study, we chose to measure some of the tissue’s mechanical and optical properties in an aging baboon model. We obtained intrinsic, compressive, mechanical properties and correlated those to small angle laser light scatter characteristics. To our knowledge, this is the first time that the effects of maturation and aging have been measured on the compressive and light scattering properties of articular cartilage.
Tissue Engineering Striated Muscle Organs by Mechanical Forces
Authors: Vandenburgh Herman H. 
Published: July 2023

Abstract
Mechanical forces play a significant role during the organogenesis of striated muscle. The rapid bone elongation in the limb and the marked increases in blood pressure and volume during development help to organize skeletal myofibers and cardiomyocytes, respectively, into the proper three-dimensional cellular pattern necessary for a functional organ. The mechanotransduction processes regulating organogenesis can be studied in tissue culture by growing isolated embryonic cells on an elastic substratum and repetitively loading the substratum with computer controlled stepper motors. Both avian skeletal muscle and rodent cardiac muscle cells have been mechanically loaded while undergoing differentiation in vitro by patterns of activity that simulate the in vivo environment. In the presence of appropriate exogenous growth factors and extracellular matrix molecules, mechanical stimulation leads to the growth and organization of these cells into 2- and 3-dimensional organ-like structures (“organoids”) (Vandenburgh and Karlisch, 1989; Vandenburgh et al., 1991; Vandenburgh et al., 1995b). These organoids display many morphological characteristics of in vivo organs including skeletal myofibers organized into fascicles with developing tendon-like structures (Fig. 1), and sheets of parallel, interconnected rod-shaped cardiomyocytes. The pattern of unidirectional and repetitive mechanical stimulation is critical for the proper in vivo-like arrangement of the cells. For example, unidirectional stretching without relaxation of both skeletal and cardiac muscle cells aligns them in the direction of stretch, while repetitive stretch-relaxation of the same cells causes them to align perpendicular to the direction of stretch. Percent cell stretch and frequency of stretch are also important parameters in determining the growth response of the cells to mechanical forces.
Comparison of Optimal Seat Suspension Parameters Obtained Using Different Vibration Sensitivity Standards
Authors: Wan Yi , Schimmels Joseph M. 
Published: July 2023

Abstract
This paper investigates the effects that different vibration sensitivity standards have on optimal seat suspension designs. Optimal seat suspensions are obtained using a previously published 4 degree of freedom (DOF) model of a human exposed to vertical vibration [4] and five different previously published model-based human sensitivity standards to assess human sensitivity to imposed vibration [5]. Seat suspension optimal parameters obtained using the different vibration sensitivity standards are compared. The optimal parameter values are also compared with the results of previous optimal suspension design studies.
Fall Direction and the Likelihood of Fracture of the Proximal Femur
Authors: Sabick Michelle B. , Goel Vijay K. 
Published: July 2023

Abstract
Falls are a common cause of hip fractures in the elderly. Epidemiologic research suggests that the fall direction, and therefore the position of the femur at impact, affects the likelihood that a hip fracture will occur. The purpose of this research was to apply several loads which simulated likely fall directions to a finite element model of the proximal femur. Eight loads of 6000 N magnitude but varying in direction were applied. The magnitude of the resulting peak von Mises equivalent strains for each load case were calculated and compared to determine which fall directions were more likely to cause hip fracture. Falls with a 15° angle of femur inclination produced the highest strains regardless of the internal rotation angle of the femur. All simulated fall positions caused strains well above the three percent failure criterion, suggesting fractures would have occurred.
A Numerical Study of Flow Through a Mechanical Heart Valve
Authors: Wang Jong H. , Guo George , Schreck Stefan , Prisco Michael 
Published: July 2023

Abstract
The purpose of this study was to develop a numerical model for simulating the flow through a Mechanical Heart Valve (MHV), for which a good understanding of the detailed flow information is desired. This is because that fluid mechanics may play an important role in the thrombus formation and hemolysis in the mechanical valve prosthesis.
Experimental-Numerical Analysis of Mitral Mechanical Heart Valve Fluid Dynamics and Cavitation Potential
Authors: Siegel John M. , Makhijani Vinod B. , Singhal Ashok K. 
Published: July 2023

Abstract
Fluid dynamics are of primary importance in the function of mechanical heart valves (MHV’s). Excessive shear rates can cause damage to blood components, regions of stasis can result in blood clots, and extremely high or extremely low pressures can result in structural or cavitation damage, respectively. Experimental techniques can measure pressure and velocity in the region of heart valves, but are unable to resolve the fluid dynamics immediately adjacent to the micron sized ‘squeeze-flow’ gap between the valve leaflet and housing. The current study uses computational fluid dynamics (CFD) to provide a detailed description of the flow field surrounding mitral mechanical heart valves. Experimentally measured leaflet closing velocities are used as an input to the computational model which allows for moving boundaries. The resultant flow field is used to assess the time-history of important fluid parameters such as minimum pressure and maximum shear rate through the final degrees of valve closure.
Time Dependent Characteristics of Valvular Regurgitation: A Numerical Investigation
Authors: Myers Jerry G. , Anayiotos Andreas S. , Perry Gilbert J. 
Published: July 2023

Abstract
The steady normalized centerline-velocity distribution proximal to an orifice has been used in quantifying valvular regurgitation with color Doppler (CD). However, the presence of pulsitility and constraining walls in a viscous flowfield may influence the centerline flow characteristics. This study utilized computational fluid dynamic (CFD) models of the flow region proximal to an axisymmetric orifice to investigate the combined effects of adjacent wall influence and time dependence on the proximal flowfield. Steady state conditions and time waveforms for flowrate and pressure-gradient were used as input boundary conditions. Results of this study indicate that normalized centerline velocity distributions depend on adjacent wall orientation. However, for a specific wall orientation, the instantaneous, normalized, centerline-velocity distribution showed little deviation from steady state distributions. These results suggest that the steady state proximal centerline velocity distribution is a good approximation the pulsatile centerline distribution for a specific time.
Flow Effects on the Concentration of Platelet Active Substances in the Vicinity of Mural Platelet Aggregates
Authors: Perktold Karl , Karner Gerhard , Rappitsch Gerhard 
Published: July 2023

Abstract
The influence of convective flow on the transport of prothrombin, thrombin, antithrombin, ADP and thromboxane in the vicinity of a mural microthrombus has been analysed applying computer simulation. The basis of the study is a suitable reaction, emission and transport model. The reaction kinetics and the mass transport are modelled mathematically with a coupled system of convection-diffusion equations. The description of the flow field near the microthrombus uses the three-dimensional Navier-Stokes equations. The numerical approach applies the finite element method.
A Numerical Simulation for Determination of Velocity Encoded MR Parameters
Authors: Fox James F. , Anayiotos Andreas S. , Doyle Mark 
Published: July 2023

Abstract
Several current investigations aim at developing methods of measuring valvular regurgitation using velocity encoded magnetic resonance (MR) imaging. MR flow encoding provides useful three-dimensional spatial and velocity information. While still in the preliminary stages, these investigations must distinguish the optimum scan parameters necessary to minimize acquisition time and maximize quantitative results. Scan parameters of particular interest are slice thickness and slice orientation. This simulation uses velocity information from computational fluid dynamic (CFD) models to create a numerical, flow dependent, MR scan proximal to an orifice. The purpose of this simulation is to analyze the effect of slice thickness and slice orientation on measuring flow proximal to an orifice. Results indicate that centerline distribution for the four millimeter (mm) slices compare best to the numerical and 1 mm slices, considering that larger slice thicknesses reduce scan time. In addition, given the 4 mm slice thickness, perpendicular slices provide more useful velocity information within the region of interest.
The Effects of Anatomical Models and Cost Functions Used by Optimization Models on the Predicted Spinal Load
Authors: Parnianpour M. , Shirazi-Adl A. , Wang J. L. , Wilke H.-J. , Sparto P. 
Published: July 2023

Abstract
The kinetic redundancy present in the biomechanical models of complex joints has presented an obstacle in estimating the joint reaction forces during simulation of complex physical activities. Six anatomical models used for the spinal loading studies and six cost functions suggested by various groups were considered in determining their effects on the predicted joint reaction forces. Only the type of anatomical model that was used significantly affected the predicted spinal loads.