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Virginia Commonwealth University

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Full-Text Articles in Biomedical Engineering and Bioengineering

Designing Biomimetic Implant Surfaces To Promote Osseointegration Under Osteoporotic Conditions By Revitalizing Mechanisms Coupling Bone Resorption To Formation, Ethan M. Lotz Jan 2019

Designing Biomimetic Implant Surfaces To Promote Osseointegration Under Osteoporotic Conditions By Revitalizing Mechanisms Coupling Bone Resorption To Formation, Ethan M. Lotz

Theses and Dissertations

In cases of compromised bone remodeling like osteoporosis, insufficient osseointegration occurs and results in implant failure. Implant retention relies on proper secondary fixation, which is developed during bone remodeling. This process is disrupted in metastatic bone diseases like osteoporosis. Osteoporosis is characterized low bone mass and bone strength resulting from either accelerated osteoclast-mediated bone resorption or impaired osteoblast-mediated bone formation. These two processes are not independent phenomena. In fact, osteoporosis can be viewed as a breakdown of the cellular communication connecting bone resorption to bone formation. Because bone remodeling occurs at temporally generated specific anatomical sites and at different times ...


Design And Testing Of An Agonist-Antagonist Position-Impedance Controlled Myoelectric Prosthesis, Christopher Aymonin Jan 2019

Design And Testing Of An Agonist-Antagonist Position-Impedance Controlled Myoelectric Prosthesis, Christopher Aymonin

Theses and Dissertations

Intuitive prosthetic control is limited by the inability to easily convey intention and perceive physical requirements of the task. Rather than providing haptic feedback and allowing users to consciously control every component of manipulation, relegating some aspects of control to the device may simplify operation. This study focuses on the development and testing of a control scheme able to identify object stiffness and regulate impedance. The system includes an algorithm to detect the apparent stiffness of an object, a proportional nonlinear EMG control algorithm for interpreting a user’s desired grasp aperture, and an antagonistically acting impedance controller. Performance of ...


Eralpha Isoforms Modulate The Tumorigenicity Of 24r,25(Oh)2d3 In Estrogen-Responsive Cancer, Anjali Verma Jan 2019

Eralpha Isoforms Modulate The Tumorigenicity Of 24r,25(Oh)2d3 In Estrogen-Responsive Cancer, Anjali Verma

Theses and Dissertations

Over 200,000 cases of breast cancer are diagnosed every year. Nearly 20% of these patients supplement their diets with some form of vitamin D. This high frequency of vitamin D supplement use may be due in part to research suggesting that cancer patients with higher serum vitamin D3 levels have better prognoses than patients with low serum vitamin D3. However, double-blind clinical trials on the efficacy of vitamin D3 supplementation in breast cancer have been inconclusive. A recent meta-analysis showed evidence of reduced cancer recurrence in patients taking vitamin D3 supplements who had ‘estrogen receptor ...


A Computational Assessment Of Lisfranc Injuries And Their Surgical Repairs, Michael Perez Jan 2019

A Computational Assessment Of Lisfranc Injuries And Their Surgical Repairs, Michael Perez

Theses and Dissertations

While Lisfranc injuries in the mid foot are less common than other ankle and mid foot injuries, they pose challenges in both properly identifying them and treating them. When Lisfranc injuries are ligamentous and do not include obvious fractures, they are very challenging for clinicians to identify unless weight bearing radiographs are used. The result is that 20%-40% of Lisfranc injuries are missed in the initial evaluation. Even when injuries are correctly identified the outcomes of surgical procedures remain poor. Existing literature has compared the different surgical procedures but has not had a standard approach or procedures across studies ...


The Role Of Kras In Mechanosensing In Non-Small Cell Lung Cancer, Krista M. Powell Jan 2019

The Role Of Kras In Mechanosensing In Non-Small Cell Lung Cancer, Krista M. Powell

Theses and Dissertations

Lung cancer is the number one cause of cancer related death worldwide, with more than 1.6 million fatalities each year. Non-small cell lung cancer (NSCLC) accounts for 80-85% of all lung cancers, with KRAS being one of the most prevalent oncogenic driver mutations. Therapeutic approaches for KRAS-mutated NSCLC have been extensively explored due to the US National Cancer Institute RAS Initiative, but methods of directly targeting KRAS or downstream effectors, such as MEK, still have poor results. Previous reports have shown that KRAS-mutated NSCLC activate distinct receptor tyrosine kinases (RTKs) depending on the epithelial or mesenchymal state. Epithelial-to-mesenchymal transition ...


Development Of Novel Models To Study Deep Brain Effects Of Cortical Transcranial Magnetic Stimulation, Farheen Syeda Jan 2018

Development Of Novel Models To Study Deep Brain Effects Of Cortical Transcranial Magnetic Stimulation, Farheen Syeda

Theses and Dissertations

Neurological disorders require varying types and degrees of treatments depending on the symptoms and underlying causes of the disease. Patients suffering from medication-refractory symptoms often undergo further treatment in the form of brain stimulation, e.g. electroconvulsive therapy (ECT), transcranial direct current stimulation (tDCS), deep brain stimulation (DBS), or transcranial magnetic stimulation (TMS). These treatments are popular and have been shown to relieve various symptoms for patients with neurological conditions. However, the underlying effects of the stimulation, and subsequently the causes of symptom-relief, are not very well understood. In particular, TMS is a non-invasive brain stimulation therapy which uses time-varying ...


Reducing Uncertainty In Head And Neck Radiotherapy With Plastic Robotics, Mark R. Ostyn Jan 2018

Reducing Uncertainty In Head And Neck Radiotherapy With Plastic Robotics, Mark R. Ostyn

Theses and Dissertations

One of the greatest challenges in achieving accurate positioning in head and neck radiotherapy is that the anatomy at and above the cervical spine does not act as a single, mechanically rigid body. Current immobilization techniques contain residual uncertainties that are especially present in the lower neck that cannot be reduced by setting up to any single landmark. The work presented describes the development of a radiotherapy friendly mostly-plastic 6D robotic platform for positioning independent landmarks, (i.e., allowing remote, independent positioning of the skull relative to landmarks in the thorax), including analysis of kinematics, stress, radiographic compatibility, trajectory planning ...


Improving Realtime 3-D Tracking Of High Dose Rate Radiation Source Using A Flat Panel Detector, Leo Uchechukwu Udeji Jan 2018

Improving Realtime 3-D Tracking Of High Dose Rate Radiation Source Using A Flat Panel Detector, Leo Uchechukwu Udeji

Theses and Dissertations

Previous research 1 on this subject tracked the presumed exact path the HDR source would follow in real-time, during breast brachytherapy treatments in other to ensure accurate dose delivery and effectively confirm actual source position. As a continuation, this research has three objectives. Firstly, we will extract information from patient DICOM file which will be used to perform evaluations, then we will establish communication between our C program and the new Varex Paxscan flat panel detector (FPD). Finally, we will try to embed our C codes into a MATLAB graphical user interface (GUI) This research will attempt to improve the ...


Nuclear Rupture In Progeria Expressing Cells, Kranthidhar Bathula Jan 2018

Nuclear Rupture In Progeria Expressing Cells, Kranthidhar Bathula

Theses and Dissertations

Cells regularly take on various types of force in the body. They have structures that are able to mediate, transfer and respond to the forces. A mutation in force regulating proteins such as lamin in the nucleus or the KASH domain which connects the nucleus to the cytoskeleton of the cell can cause catastrophic events to occur. The aims of this study were to better understand the response of the nucleus when structural proteins are mutated or are not present while under force. Progeria, a rare disease where an additional farnesyl group is attached to lamin was used in this ...


Exogenous Fniii 12-14 Regulates Tgf-Β1-Induced Markers, Hilmi M. Humeid Jan 2018

Exogenous Fniii 12-14 Regulates Tgf-Β1-Induced Markers, Hilmi M. Humeid

Theses and Dissertations

The extracellular matrix protein Fibronectin (FN) plays an important role in cell contractility, differentiation, growth, adhesion, and migration. The 12th -14th Type III repeats of FN (FNIII 12-14), also referred to as the Heparin-II domain, comprise a highly promiscuous growth factor (GF) binding region. This binding domain aids in cellular signaling initiated from the ECM. Additionally, FN has the ability to assemble into fibrils under certain conditions, mostly observed during cell contractile processes such as those that initiate due to upregulation of Transforming Growth Factor Beta 1 (TGF-β1) [1], [2]. Previous work from our lab has shown that self-assembly of ...


Fibronectin Mechanics And Signaling In Tgf-Β1-Induced Epithelial To Mesenchymal Transition, Lauren Griggs Jan 2018

Fibronectin Mechanics And Signaling In Tgf-Β1-Induced Epithelial To Mesenchymal Transition, Lauren Griggs

Theses and Dissertations

Epithelial to Mesenchymal Transition (EMT) is a dynamic process by which a distinct change in the phenotype and function of epithelial cells render them as mesenchymal cells. Characteristics of mesenchymal cells include the ability to invade, increased migratory kinetics and heightened resistance to apoptosis. Therefore, there is a strong need to fully understand the mechanism for the induction of EMT in pathological conditions such as carcinoma progression. Recent advances highlight two pivotal contributors, soluble growth factor (gf) signals, and mechanical signals, in the process. However, to date, no clear mechanism exists linking the two in epithelial transdifferentiation. Transforming Growth Factor-β1 ...


Automatic Image Processing And Conversion To Tactile Graphics, Tyler Ferro Jan 2018

Automatic Image Processing And Conversion To Tactile Graphics, Tyler Ferro

Theses and Dissertations

Graphical information has become a critical method for portraying information for education, work and personal tasks and decisions. Unfortunately there are currently limited means of providing this information to individuals who are blind or visually impaired: alternate text is frequently missing, and accessible tactile diagrams tend to be time consuming to make and require expertise in order for them to be interpretable (which may be costly to the user and/or impossible to get). The aim of this project is to provide an accessible system to automatically generate tactile graphics for those who need to interpret information contained in visual ...


Modulating The Innate Immune Response To Electrospun Scaffolds And Polymer Degradative Byproducts, Daniel Abebayehu Jan 2017

Modulating The Innate Immune Response To Electrospun Scaffolds And Polymer Degradative Byproducts, Daniel Abebayehu

Theses and Dissertations

Implanted biomaterials often induce inflammation that frequently leads to the foreign body response, fibrosis, and the failure of the implant. Thus, it is important to evaluate how cells interact with materials to promote a more regenerative response. It is critical to determine how to modulate the response of tissue resident innate immune cells, as they are among the first cells to interact with implanted materials. Among tissue resident innate immune cells are mast cells, which are inflammatory sentinels that degranulate and orchestrate the fate of other cell populations, such as monocytes/macrophages and lymphocytes. Mast cells have also been reported ...


The Effect Of Vibrotactile Feedback On Remote Manual Task Performance, Matthew S. Standard Jan 2017

The Effect Of Vibrotactile Feedback On Remote Manual Task Performance, Matthew S. Standard

Theses and Dissertations

Vibrotactile feedback offers a unique opportunity to augment or reconstruct impaired tactile sensations, whether that be in the form of enhancing prosthetics or specialized protective clothing. Important information about temperature and object slippage serve to endanger the human operator or equipment. This thesis presents three experiments which investigate amplitude modulated vibrotactile signals as a scalar dimension of roughness, the effect those signals and their locations (finger pad, forearm, bicep) have on the performance of two tasks: the sensing of temperatures simulated by vibrotactile signals and gripping an object of simulated surface texture. The results show task performance increase when the ...


Investigation Of Polymeric Composites For Controlled Drug Release, Hsi-Wei Yeh Jan 2017

Investigation Of Polymeric Composites For Controlled Drug Release, Hsi-Wei Yeh

Theses and Dissertations

The Electrospray (ES) technique is a promising particle generation method for drug delivery due to its capabilities of producing monodisperse PLGA composite particles with unique configurations and high drug encapsulation efficiency. In the dissertation work, the coaxial dual capillary ES was used to generate drug-loaded core-shell PLGA particles to study the effects of particle filling materials, drug loading locations and particle shell thicknesses on the resultant in vitro release behaviors of the hydrophilic and/ or hydrophobic model drugs. Through release profile characterization of drug-loaded PLGA particles (particle size: 400 nm and 1 μm), it was confirmed that the co-encapsulation of ...


Altering A Runner’S Foot Strike Using A Modified Elliptical Trainer, Daniel Shull Jan 2017

Altering A Runner’S Foot Strike Using A Modified Elliptical Trainer, Daniel Shull

Theses and Dissertations

One possible solution to common running related injuries is to transition runners from a rearfoot strike during initial contact to a midfoot strike. Natural rearfoot strike runners were studied to see if a modified elliptical trainer could be used to alter their running pattern to that of a midfoot strike runner. Their results were compared to subjects who ran on a non-modified elliptical trainer. After training on the modified elliptical trainer, subjects demonstrated a decrease in foot angle at initial contact when attempting to run with a midfoot strike. Training did not affect all kinetic metrics or stride frequency. However ...


Development And Validation Of A Novel Resonant Energy Transfer (Fret) Biosensor To Measure Tensile Forces At The Linc Complex In Live Cells, Paul Arsenovic Jan 2017

Development And Validation Of A Novel Resonant Energy Transfer (Fret) Biosensor To Measure Tensile Forces At The Linc Complex In Live Cells, Paul Arsenovic

Theses and Dissertations

There is a large body of evidence supporting the theory that cell physiology largely depends on the mechanical properties of its surroundings or micro-environment. More recently studies have shown that changes to intra-cellular mechanical properties can also have a meaningful impact on cell function and in some cases lead to the progression of ailments or disease. For example, small changes to the protein sequence of a structural nuclear envelope protein called lamin-A is known to cause a variety of neurological and musculoskeletal diseases referred to as laminopathies. Currently, there is little incite into how these mutations lead to disease progression ...


Development Of An Electrospun And 3d Printed Cellular Delivery Device For Dermal Wound Healing, Ryan M. Clohessy Jan 2017

Development Of An Electrospun And 3d Printed Cellular Delivery Device For Dermal Wound Healing, Ryan M. Clohessy

Theses and Dissertations

The goal of this research was to develop a system of individualized medicine that could be applied to dermal wounds serving as a wound dressing and synthetic extracellular matrix while delivering stem cells to the wound bed. First, fabrication parameters for electrospinning polymer fibers were determined. This involved evaluating fiber morphology with respect to polymer selection and solution concentration. Next, construct fabrication was examined to produce an integrated void space, or cargo area, suitable to maintain stem cells. In vitro studies to ensure stem cell viability and phenotype were conducted, and results supported the notion that cells could be administered ...


Modified Pamam Dendrimers In Tunable Drug-Delivery Systems: A Sustained-Release Dendrimer Hydrogel For Anti-Glaucoma Drugs And Surface-Engineered Macrophages As Nanoparticle Carriers For Targeted Anti-Cancer Therapy, Christopher A. Holden Jan 2017

Modified Pamam Dendrimers In Tunable Drug-Delivery Systems: A Sustained-Release Dendrimer Hydrogel For Anti-Glaucoma Drugs And Surface-Engineered Macrophages As Nanoparticle Carriers For Targeted Anti-Cancer Therapy, Christopher A. Holden

Theses and Dissertations

Two specific drug-delivery applications were sought in this work using polyamidoamine (PAMAM) dendrimers. One drug-delivery system used a novel dendrimer hydrogel (DH) for sustained delivery of anti-glaucoma drugs. In this work, PAMAM G3.0 dendrimers were covalently bonded with poly(ethylene glycol) (PEG­12000) molecules which were subsequently acrylated, resulting in photocurable DH conjugates. For pharmacological studies, DH were loaded with a solution of intraocular pressure lowering drugs, brimonidine and timolol maleate, and were characterized for in vitro release and ex vivo transport and uptake. DH formulations were shown to increase the loading of drug molecules, increase transcorneal drug delivery ...


Eye Movement Control: An Index For Athleticism, Brittany L. Oshea Jan 2017

Eye Movement Control: An Index For Athleticism, Brittany L. Oshea

Theses and Dissertations

Athletic potential is one of the most complex human traits. An elite athlete is produced from a complex interaction of an innumerable number of traits exhibited by the athlete. However, it’s not clear whether these traits are innate, allowing the athlete to excel, or, alternatively, are a consequence of practice. To be successful, athletes rely heavily on sensory information from the visual and vestibular systems. This study investigated the relationship eye movement control has with innate athleticism by comparing the saccadic and Vestibulo-Ocular Reflex (VOR) responses of former, no longer practicing, elite athletes against their age and gender matched ...


Electrospraying Extracellular Matrix To Form Nanoparticles, Patrick Link Jan 2017

Electrospraying Extracellular Matrix To Form Nanoparticles, Patrick Link

Theses and Dissertations

Chronic Obstructive Pulmonary Disease (COPD) is a leading cause of death worldwide. Alveolar wall destruction is a significant contributor to COPD. Inflammatory macrophages are a major source of the Extracellular Matrix (ECM) proteolysis. ECM breakdown causes air to get trapped in the alveoli, obstructing airflow. One step in curing COPD may be to convert inflammatory to pro-regenerative macrophages. Recently, decellularized ECM scaffolds have shown the ability to induce a pro-regenerative phenotype.

Yet these scaffolds are incapable for reaching the alveolar region of the lungs. To reach the alveolar region particles need a diameter of 1-5 μm or smaller than 300 ...


Role Of E-Cadherin Force In The Spatial Regulation Of Cell Proliferation, Abhinav Mohan Jan 2016

Role Of E-Cadherin Force In The Spatial Regulation Of Cell Proliferation, Abhinav Mohan

Theses and Dissertations

Cell proliferation and contact inhibition play a major role in maintaining epithelial cell homeostasis. A hallmark of epithelial cells is strong cell-cell junctions. These junctions include E-Cadherin, a type of adherens junction that is critical for both barrier function and contact inhibition. Prior experiments by other groups have shown that adherens junctions are subject to mechanical tension. Externally applied forces (e.g. stretch) results in changes in E-Cadherin forces that coordinate proliferation. My current work tests the hypothesis that E-Cadherin forces mediate the spatial regulation of cell proliferation even in the absence of externally applied forces.


An Injectable Stem Cell Delivery System For Treatment Of Musculoskeletal Defects, Shirae Leslie Jan 2016

An Injectable Stem Cell Delivery System For Treatment Of Musculoskeletal Defects, Shirae Leslie

Theses and Dissertations

The goal of this research was to develop a system of injectable hydrogels to deliver stem cells to musculoskeletal defects, thereby allowing cells to remain at the treatment site and secrete soluble factors that will facilitate tissue regeneration. First, production parameters for encapsulating cells in microbeads were determined. This involved investigating the effects of osmolytes on alginate microbead properties, and the effects of alginate microbead cell density, alginate microbead density, and effects of osteogenic media on microencapsulated cells. Although cells remained viable in the microbeads, alginate does not readily degrade in vivo for six months. Therefore, a method to incorporate ...


Efficiency Evaluation Of A Magnetically Driven Multiple Disk Centrifugal Blood Pump, Kayla H. Moody Jan 2016

Efficiency Evaluation Of A Magnetically Driven Multiple Disk Centrifugal Blood Pump, Kayla H. Moody

Theses and Dissertations

Heart failure is expected to ail over 8 million people in America by 2030 leaving many in need of cardiac replacement. To accommodate this large volume of people, ventricular assist devices (VADs) are necessary to provide mechanical circulatory support. Current VADs exhibit issues such as thrombosis and hemolysis caused by large local pressure drops and turbulent flow within the pump. Multiple disk centrifugal pumps (MDCPs) use shearing and centrifugal forces to produce laminar flow patterns and eliminate large pressure drops within the pump which greatly reduce risks that are in current VADs. The MDCP has a shaft drive system (SDS ...


The Molecular And Mechanical Mechanisms Of The Age-Associated Increase In The Severity Of Experimental Ventilator Induced Lung Injury, Joseph Ames Herbert Jan 2016

The Molecular And Mechanical Mechanisms Of The Age-Associated Increase In The Severity Of Experimental Ventilator Induced Lung Injury, Joseph Ames Herbert

Theses and Dissertations

Abstract

Background

The majority of patients requiring mechanical ventilation are over the age of 65 and advanced age is known to increase the severity of ventilator-induced lung injury (VILI) and mortality. However, the mechanisms which predispose aging ventilator patients to increased mortality rates are not fully understood.

Pulmonary edema is a hallmark of VILI and the severity of edema increases with age. Ventilation with conservative fluid management decreases mortality rates in acute respiratory distress (ARDS) patients, but has not been investigated in VILI. We hypothesized that age-associated increases in pulmonary edema promote age-related increases in ventilator-associated mortality. Endoplasmic reticulum (ER ...


In-House Fabrication Of Multi-Sized Polystyrene Microcarriers For Neural Stem Cell Expansion, Jessica Forrester Jan 2016

In-House Fabrication Of Multi-Sized Polystyrene Microcarriers For Neural Stem Cell Expansion, Jessica Forrester

Theses and Dissertations

The clinical demand for neural stem cells drives the need for a reproducible method used to generate a large quantity of well-characterized cells to support regenerative therapies. Microcarriers are currently being used as a scaffold for stem cell culture to aid in this expansion process because they provide a larger surface area while also requiring fewer cell passages compared to monolayer culture. The main objective of this project was to investigate how human neural stem cell attachment, proliferation, and multipotency would respond to three-dimensional (3D) culture using peptide-coated microcarriers of varying diameters. In this study, multi-sized polystyrene microcarriers were fabricated ...


Improved Capability Of A Computational Foot/Ankle Model Using Artificial Neural Networks, Ruchi D. Chande Jan 2016

Improved Capability Of A Computational Foot/Ankle Model Using Artificial Neural Networks, Ruchi D. Chande

Theses and Dissertations

Computational joint models provide insight into the biomechanical function of human joints. Through both deformable and rigid body modeling, the structure-function relationship governing joint behavior is better understood, and subsequently, knowledge regarding normal, diseased, and/or injured function is garnered. Given the utility of these computational models, it is imperative to supply them with appropriate inputs such that model function is representative of true joint function. In these models, Magnetic Resonance Imaging (MRI) or Computerized Tomography (CT) scans and literature inform the bony anatomy and mechanical properties of muscle and ligamentous tissues, respectively. In the case of the latter, literature ...


Characterization Of Poly(Dimethylsiloxane) Blends And Fabrication Of Soft Micropillar Arrays For Force Detection, Thomas J. Petet Jr Jan 2016

Characterization Of Poly(Dimethylsiloxane) Blends And Fabrication Of Soft Micropillar Arrays For Force Detection, Thomas J. Petet Jr

Theses and Dissertations

Diseases involving fibrosis cause tens of thousands of deaths per year in the US alone. These diseases are characterized by a large amount of extracellular matrix, causing stiff abnormal tissues that may not function correctly. To take steps towards curing these diseases, a fundamental understanding of how cells interact with their substrate and how mechanical forces alter signaling pathways is vital. Studying the mechanobiology of cells and the interaction between a cell and its extracellular matrix can help explain the mechanisms behind stem cell differentiation, cell migration, and metastasis. Due to the correlation between force, extracellular matrix assembly, and substrate ...


An Investigation Of Kinetic Visual Biofeedback On Dynamic Stance Symmetry, Trisha J. Massenzo Jan 2016

An Investigation Of Kinetic Visual Biofeedback On Dynamic Stance Symmetry, Trisha J. Massenzo

Theses and Dissertations

The intent of the following research is to utilize task-specific, constraint-induced therapies and apply towards dynamic training for symmetrical balance. Modifications to an elliptical trainer were made to both measure weight distributions during dynamic stance as well as provide kinetic biofeedback through a man-machine interface. Following a review of the background, which includes research from several decades that are seminal to current studies, a design review is discussed to cover the design of the modified elliptical (Chapter 2).

An initial study was conducted in a healthy sample population in order to determine the best visual biofeedback representation by comparing different ...


In Vitro Visualization Of Pediatric Sized Mechanical Heart Valve Performance Using Aortic Root Model In Mock Circulatory Loop, Sarah Lederer Jan 2016

In Vitro Visualization Of Pediatric Sized Mechanical Heart Valve Performance Using Aortic Root Model In Mock Circulatory Loop, Sarah Lederer

Theses and Dissertations

Congenital heart valve disease is one of the most common abnormalities in children, with common valve defects being aortic stenosis, mitral stenosis, and valvular regurgitation. Although adult sized mechanical heart valve (MHV) replacements are widely studied and utilized, there are currently no FDA approved prosthetic heart valves available for the pediatric population. This is due to a variety of reasons such as a limited patient pool for clinical trials, limited valve sizes, and complex health histories in children. Much like adult sized mechanical heart valves, potential complications with pediatric heart valve replacements include thrombosis, blood damage due to high shear ...