Engineering Commons^™

Laparoscopic Assisted Fusion Of The Lumbosacral Spine: A Biomechanical And Histologic Analysis Of The Open Versus Laparoscopic Technique In An Animal Model, Lee H. Riley Iii, Jason C. Eck, Hiryuki Yoshida, Jeffrey M. Toth, Nguyen Cahn, Tae Hong Lim, Linda M. Mcgrady

Biomedical Engineering Faculty Research and Publications

Study Design. An animal model for laparoscopic lumbosacral fusion.

Objectives. To compare the biomechanical and histologic results of open to laparoscopic lumbosacral discectomy and fusion in an animal model.

Background Data. Early clinical reports of laparoscopic lumbosacral fusions are encouraging, but animal experiments have not been reported.

Methods. Ten pigs (50-80 kg) were divided into two groups. Group 1 underwent an open anterior lumbosacral discectomy and fusion at L7-S1 using autologous bone graft and a titanium MOSS (DePuy Motech) cage. Group 2 was identical to Group 1 except that a laparoscopic technique was used. The animals were killed at 3 …

Experimental Spinal Fusion With Recombinant Human Bone Morphogenetic Protein-2 Without Decortication Of Osseous Elements, Harvinder Sandhu, Linda E.A. Kanim, Jeffrey M. Toth, J. Michael Kabo, David Liu, Rick B. Delamarter, Edgar G. Dawson

Biomedical Engineering Faculty Research and Publications

Study Design. L4-L5 intertransverse process fusions were produced with 58 μg, 230 μg, or 920 μg of recombinant human bone morphogenetic protein-2 in 20 dogs. Eleven had traditional decortication of posterior elements before insertion of the implant. Nine were left undecorticated. All animals were evaluated 3 months after surgery.

Objectives. To determine whether decortication is a prerequisite for successful fusion in the presence of osteoinductive proteins such as bone morphogenetic protein-2.

Summary of Background Data. Recombinant osteoinductive proteins can induce de novo bone in ectopic soft-tissue sites in the absence of bone marrow elements. Traditional methods for achieving spinal fusion …

Determination And Studying Of Stress Distribution In Various Ankle-Foot Orthoses : Experimental Stress Analysis, Rong Feng

Theses

Ankle-Foot Orthosis (AFO) is prescribed to constrain and inhibit abnormal motion such as "drop foot" due to stroke. Most orthoses were hand-made by orthotists according to their own experience. However, some types of AFO were easy to fatigue (out of their functional capabilities) than others due to regular usage. In order to improve the design and usage, quantitative stress analysis of different types of orthoses is needed. The objective of this project is to obtain experimental data which will confirm the results obtained from previous Finite Element Analysis (FEA)^[1]. In addition, the experimental analysis is extended to obtain …

The Relationship Between Thermoregulatory And Haemodynamic Responses Of The Skin To Relaxation And Stress, Paul O. Nketia

Theses

The present study investigated the effects of stress and relaxation on (1) EEG coherence and (2) peripheral blood flow.

EEG coherence of two meditators in two different but adjacent rooms was measured during eyes opened, eyes closed, single meditation and group meditation. The skin temperatures of the subjects together with their room temperatures were also recorded. EEG coherence plots (Cospar) showed a spread out of the alpha band to the beta, theta and occasionally to the delta wave bands during group meditation. The area above the 0.98 coherence threshold in the alpha band was greater during group meditation than during …

Renin-Angiotensin System And Its Relationship To Arterial Pressure Regulation, Sami D. Saume

Theses

The renal system is known to participate in the natural regulation of blood pressure. A renal system model that simulates interaction responses of renal output to arterial blood pressure was developed. The major components of this model are glomerular filtration rate, tubular sodium reabsorption, the renin-angiotensin system, Aldosterone secretion, and antidiuretic hormone secretion. The model's differential equations were coded using Vissim 1.2 student version. It was found that, the renal output increased as glomerular filtration rate, Aldosterone concentration, and blood pressure increased. Conversely, increasing antidiuretic hormone concentration lead to decreased renal output.

Additionally, Angiotensin II and Aldosterone concentrations increased as …

Computer Simulation Of Cerebrovascular Circulation : Assessment Of Intracranial Hemodynamics During Induction Of Anesthesia, Steven D. Wolk

Theses

The purpose of this project was to develop a computer model of cerebrovascular hemodynamics interacting with a pharmacokinetic drug model to examine the effects of various stimuli during anesthesia on cerebral blood flow and intracranial pressure.

The mathematical model of intracranial hemodynamics is a seven compartment constant volume system. A series of resistances relate blood and cerebrospinal fluid fluxes to pressure gradients between compartments. Arterial, venous, and tissue compliance are also included. Autoregulation is modeled by transmural pressure dependent arterial-arteriolar resistance. The effect of a drug (thiopental) on cerebrovascular circulation was simulated by a variable arteriolar-capillary resistance. Thiopental concentration, in …

Relative Dentifrice Abrasivity On Dentin And Enamel, Laura Marchetti

Theses

The abrasive characteristics of six (6) brands of toothpastes on Enamel and Dentin material were assessed. Human teeth were sliced to expose the dentin surface and then polished using 3 μm and 0.25 μm diamond paste. The outside surface of the tooth (after slicing) was used "as is" for the enamel surface testing. The surface smoothness was evaluated prior to testing using a surface profiler and averaging four (4) to five (5) readings across the surface for each sample.

The tooth slices were then embedded into the acrylic plate surface by routing out an area with a dental drill and …

Mechanical Evaluation Of Pedicle Screw Fixation Of The Lumbar Spine, Ding Lu

Theses

Pedicle screw fixation of the lumbar spine has been reported to increase fusion rates A biomechanical evaluation of four different pedicle screw implant systems, (AO. Rogozinski, TSRH and Wiltse). was performed to compare intrinsic device stiffness under conditions of flexion-compression and forty-five degree off-axis flexion-compression The effect on stiffness of the loosening of device members was also studied. Testing was done in load control using an electrohvdrualic testing machine. UHMWPe blocks are used to simulate the vertebra.

Assuming that stiffness is directly proportional to the probability of obtaining fusion. this study allows the ranking of the systems tested in their …

Local Delivery Of Interleukin 4 By Retrovirus-Transduced T Lymphocytes Ameliorates Experimental Autoimmune Encephalomyelitis., Michael K. Shaw, James B. Lorens, Archana Dhawan, Richard Dalcanto, Harley Y. Tse, Alyssa B. Tran, Colleen Bonpane, Shanti L. Eswaran, Stefan Brocke, Nora Sarvetnick, Lawrence Steinman, Garry P. Nolan, C. Garrison Fathman

Journal Articles: Regenerative Medicine

Experimental autoimmune encephalomyelitis (EAE) is an inflammatory autoimmune disease of the central nervous system which serves as a model for the human disease multiple sclerosis. We demonstrate here that encephalitogenic T cells, transduced with a retroviral gene, construct to express interleukin 4, and can delay the onset and reduce the severity of EAE when adoptively transferred to myelin basic protein-immunized mice. Thus, T lymphocytes transduced with retroviral vectors can deliver "regulatory cytokines" in a site-specific manner and may represent a viable therapeutic strategy for the treatment of autoimmune disease.

The Synthesis, Characterization, And Cell Seeding Of A Collagen/Hydroxyapatite Porous Scaffold For Treatment Of Osseous Defects, Kim Rachel Patterson

All Theses

The need for finding a bone graft substitute stems from the fact that approximately 200,000 bone grafting procedures are performed annually in the U.S. alone. Although biological grafting options (i.e. autografts & allografts) exist, they do suffer from inherent problems. These include limited resources, costly processing, and potential for pathogen transfer. Thus, investigators have sought synthetic alternatives.

The objective of this research was to utilize hydroxyapatite (HA) and collagen, both analogues to the major constituents of bone, to fabricate an optimal synthetic osteoconductive/osteoinductive bone scaffold. Current attempts by other investigators to combine the two materials have been met with some …

Tillage Effects On Soil Erosion Potential And Soil Quality Of A Former Conservation Reserve Program Site, John E. Gilley, J. W. Doran

Department of Agricultural and Biological Systems Engineering: Faculty Publications

This study was conducted to determine the effects of tillage on soil erosion potential and soil quality characteristics of a former Conservation Research Program (CRP) site. Following tillage, the study area in northern Mississippi was maintained in a fallow condition for nine months. Soil loss from simulated rainfall events was minimal on recently tilled plots and an adjoining, undisturbed CRP area. In contrast, soil loss from the former CRP site which had been tilled nine months previously was similar to values obtained before the CRP program when the area had been cropped for several years. Tillage and over-winter fallowing caused …

Monoclonal Antibody Assay And Kit For Detecting Metal Cations In Body Fluids (Continuation), Randall R. Carlson, Jay S. Stout, Dwane E. Wylie, Fred W. Wagner, Malcolm Riddell

Biological Process Development Facility: Staff Publications

The invention provides method and kits for detecting a metallic cation in a sample of a body fluid. The preferred method and kits include the use of at least two different types of antibodies having different specificities. In the preferred method, the sample of body fluid can be contacted with an effective amount of a capture antibody specific for a naturally occurring polypeptide that can bind the metallic cation to form a first antigen-antibody complex. An effective amount of an antibody specific for an epitope on a metallic cation-naturally occurring polypeptide complex or an antibody specific for a metallic cation …

Slice Location Dependence Of Aortic Regurgitation Measurements With Mr Phase Velocity Mapping, George P. Chatzimavroudis, Peter G. Walker, John N. Oshinski, Robert H. Franch, Roderic I. Pettigrew, Ajit P. Yoganathan

Chemical & Biomedical Engineering Faculty Publications

Although several methods have been used clinically to assess aortic regurgitation (AR), there is no “gold standard” for regurgitant volume measurement. Magnetic resonance phase velocity mapping (PVM) can be used for noninvasive blood flow measurements. To evaluate the accuracy of PVM in quantifying AR with a single imaging slice in the ascending aorta, in vitro experiments were performed by using a compliant aortic model. Attention was focused on determining the slice location that provided the best results. The most accurate measurements were taken between the aortic valve annulus and the coronary ostia where the measured (Y) and actual …

Glycerolysis Of Fats And Methyl Esters., Hossein Noureddini, V Medikonduru

Papers in Biomaterials

The glycerolysis of methyl esters and triglycerides with crude glycerol. a coproduct from the transesterification of triglycerides, was studied. Three procedures were followed ior this conversion. The first procedure was a one-step glycerolysis with methyl esters. The second procedure was a two-step process. This proced~~irnev olved an initial partial glycerolysis with methyl esters, followed by fat glycerolysis. The third procedure u,as a simultaneous glycerolysis n,ith methyl esters and triglycerides. In the glycerolysis with methyl esters, the removal of methanol is vital to the production of mono- and diglycerides. Methanol was removed either by drawing vacuum on the reactor or by …

Generic, Geometric Finite Element Analysis Of The Transtibial Residual Limb And Prosthetic Socket, Barbara Silver-Thorn, Dudley S. Childress

Biomedical Engineering Faculty Research and Publications

Finite element analysis was used to investigate the stress distribution between the residual limb and prosthetic socket of persons with transtibial amputation (TTA). The purpose of this study was to develop a tool to provide a quantitative estimate of prosthetic interface pressures to improve our understanding of residual limb/prosthetic socket biomechanics and prosthetic fit. FE models of the residual limb and prosthetic socket were created. In contrast to previous FE models of the prosthetic socket/residual limb system, these models were not based on the geometry of a particular individual, but instead were based on a generic, geometric approximation of the …

Kinetics Of Transesterification Of Soybean Oil, Hossein Noureddini, D Zhu

Papers in Biomaterials

Transesterification of soybean oil with methanol was investigated. Three stepwise and reversible reacttons are believed to occur. The effect of variations in mixing intensity (Reynolds number = 3,100 to 12,400) and temperature (30 to 70'CJ on the rate oireaction were studied while the molar ratio of alcohol to triglycerol (6:l) and the concentration of catalyst (0.20 wt% based on soybean oil) were held constant. The variations in mixing intensity appear to effect the reaction parallel to the variations in temperature. A reaction mechanism consisting of an initial mass transfer-controlled region followed by a kinetically controlled region is proposed. The experimental …

Ifn-Gamma, Igif, And Iddm., Nora Sarvetnick

Journal Articles: Regenerative Medicine

No abstract provided.

Residual Strength Of Equine Bone Is Not Reduced By Intense Fatigue Loading: Implications For Stress Fracture, R. B. Martin, V. A. Gibson, S. M. Stover, J. C. Gibeling, L. V. Griffin

Biomedical Engineering

Fatigue or stress fractures are an important clinical problem in humans as well as racehorses. An important question in this context is, when a bone experiences. fa!igue damage ~uring e~treme use, how much is it weakened compared to its original state? Since there are very ltmtted data on thts quesuon and stress fractures are common in racehorses, we sought to determine the effect of fatigue loading on the monotonic l:trength of equine cortical bone. Beams were machined from the dorsal, medial and lateral cortices of the third metacarpal bones of six thoroughbred racehorses. Beams from left and right bones were …

Design Of A Mode Of Delivery For Macrobead Transplantation, Jagdip Desai

Theses

The macrobead is a form of a biohybrid artificial pancreas (BAP), which is being developed to treat type 1 diabetes. A hypothetical human transplant would require 125 rat equivalent macrobeads. For intraperitoneal transplantation a mode of delivery that allows the placement of several hundred macrobeads into a basket or pouch type device is required.

In this study, four commercially available materials were studied as possible candidates for creating a pouch. These materials are polyvinyl chloride acrylic copolymer (PVC), polyethersulfone (PES), polyvinylidenedifluoride (PVDF), and polytetrafluorethylene (PTFE). Tubular pouches of each material were designed. They then underwent in vivo biocompatibility and in-vitro …

Three-Dimensional Stress Analysis Of The Femur With Prosthetic Hip Stem Utilizing Computed Tomography Scans Of The Femur For Geometry And Material Properties, Thomas J. Lavin

Theses

Three-dimensional finite element stress analyses of the femur with prosthesis hip stem were performed for two cases, one male and one female, using ideally bonded cemented titanium prostheses. Computed tomography data files were used to derive the three-dimensional femur geometry and material properties for each cortical bone element. The maximum shear stress (4.7 MPa) in the cement was greater then the maximum tensile stress and occurred at the cement-bone interface. The tensile stresses in the cement were less then the fatigue strength of the cement. The stress patterns were quite similar for the two cases.

A data analysis program was …

Laser Profilometry Of Polymeric Materials, Eduard A. Kulik, Patrick Calahan

Cells and Materials

Unlike the mechanical stylus profilometer, the laser profilometer does not damage the surface of soft materials. However, the accuracy of autofocusing of the laser profilometer is not always sensitive enough to discriminate the material/air interface from subsurface structures of semitransparent polymers. In the present study over ten polymeric surfaces were gold coated in order to investigate the effect of gold coating on the readings of a laser profilometer. Surface profiles of some polymeric materials became much smoother even if a very thing gold coating was applied to increase the reflection from the surface. It was concluded that a thin gold …

Image Analysis Of Primary Bone-Derived Cells On Different Polystyrene Surfaces, R. M. Shelton, G. Landini

Cells and Materials

The aim of the present study was to examine whether two different cell populations could be discerned using image analysis of a variety of morphological parameters on bacteriological and tissue culture polystyrene surfaces. Rat periosteal and osteoblast cultures were established on both polystyrene petri dishes and examined using phase contrast microscopy after one and two weeks before capturing digital images which were stored on a personal computer. The digital images were processed to identify the cell margins or perimeter, from which seven different morphological parameters were calculated using a program developed (by GL) for both the cell populations on the …

Corrosion Of Metal Hip Arthroplasties And Its Possible Role In Loosening, H. K. Koerten, J. J. A. M. Van Raay, J. J. M. Onderwater, F. P. Bernoski, P. M. Rozing

Cells and Materials

Tissue removed with human hip arthroplasties during revision surgery of 45 patients was evaluated by transmission electron microscopy and X -ray microanalysis (XRMA). The results show that microscopic and submicroscopic particles are abundantly present in the tissue at the tissue/implant interface. XRMA of individual particles shows that the chemical composition of a portion of the particles was in agreement with that of the retrieved implants. Regularly, particulates with a dissimilar chemical composition were found. Sometimes, these particles could be recognized as filler particles of the cements used. Other particles could partly or completely be composed of the chemical elements that …

Macrophage Response To Polymethylmethacrylate Particles, Stephen M. Horowtiz

Cells and Materials

This paper reviews studies performed by this laboratory involving the macrophage response to implant particles. Through the development of a tissue culture model, we have studied the events which occur following macrophage phagocytosis of bone cement particles, the released mediators and cell interactions which may ultimately lead to bone resorption, and the inhibition of this process with the use of pharmaceutical agents. This is divided into the following sections: Histologic response of macrophages to cement particles I toxicity I and mediator release, the effects of particle size and composition on mediator release by macrophages, macrophage I osteoblast interactions, macrophage I …

Fracture Of An Acetabular Component Inserted Without Cement: A Case Report, R T. Trousdale, D J. Berry, Joshua J. Jacobs, Jeremy L. Gilbert

Biomedical and Chemical Engineering - All Scholarship

No abstract provided.

Biological Response To Particulate Debris: In Vitro And In Vivo Studies, A. S. Shanbhag, J. E. Dowd, J. J. Jacobs, D. M. Tramaglini, T. T. Glant, J. Black, H. E. Rubash

Cells and Materials

In this study, we compared the results of a human monocyte in vitro model and a canine in vivo model, to evaluate the response to different types of particulate wear debris. Both the in vitro and in vivo studies demonstrated that titanium-6 aluminum-4 vanadium (TiAIV), ultrahigh molecular weight polyethylene (UHMWPE) and other particulate wear debris are stimulatory to macrophages and elicit release of several identifiable mediators involved in periprosthetic inflammation and bone resorption. Further, in the in vivo studies, these same particles initiated the formation of interfacial membranes which were histologically and biochemically similar to those seen in clinically failed …

Sintered Carbonate Apatites As Bone Substitutes, Yutaka Doi

Cells and Materials

Sintering of carbonate apatites was investigated and the usefulness of sintered specimens as bone substitutes was evaluated in vitro and in vivo. Osteoclasts appeared to be capable of resorbing sintered carbonate apatite, which was as soluble as deproteinated bone and much more soluble than sintered hydroxyapatite in weak acids. In skull defects of Wistar rats, sintered carbonate apatite particles resorbed to an appreciable extent, but the rate of resorption did not exceed that of new bone formation. At 4 weeks after implantation the defects were filled almost completely with new bone that compared favorably with the host bone. These …

Detachment Of Human Endothelial Cells Under Flow From Wettability Gradient Surfaces With Different Functional Groups, T. G. Ruardy, H. E. Moorlag, J. M. Schakenraad, H. C. Van Der Mei, H. J. Busscher

Cells and Materials

In this study, the position bound adhesion, spreading and detachment under flow of human umbilical cord endothelial cells (HUVEC) was studied on a dichlorodimethylsilane (DDS), dimethylocta-decylchlorosilane (DOCS) and tridecafluor-1,1,2,2-tetrahydrooctyl-1-dimethylchlorosilane (TFCS) wettability gradient on glass. Gradient surfaces were prepared by the diffusion method and characterized by the Wilhelmy plate technique for their wettability and by X-ray photoelectron spectroscopy (XPS) for their chemical composition. Quantitative analysis of the cellular response on the wettability gradient surfaces showed that the position bound cellular response was influenced by wettability for each type of gradient in a different way. On DDS-wettability gradients, cells withstood flow best …

Heat-Treatment Behavior Of High-Palladium Dental Alloys, Qiang Wu, William A. Brantley, John C. Mitchell, Stanley G. Vermilyea, Jianzhong Xiao, Wenhua Guo

Cells and Materials

Four high-palladium dental alloys were cast, quenched following solidification, and heat treated at temperatures ranging from 200° to 1,800°F. The Vickers hardness of each alloy was measured, and microstructural changes were studied by scanning electron microscopy (SEM). Phase transformations were investigated by thermomechanical analysis (TMA). Heat treatment at 1,600° and 1,800°F significantly decreased the hardness of one Pd-Cu-Ga alloy, compared to the as-cast condition, as did heat treatment at 1,800°F for the other Pd-Cu-Ga alloy and one Pd-Ga alloy, and yielded fine-grained microstructures of the palladium solid solution. There were generally no significant changes in the hardness of the other …

A Quantitative Method Of Measuring Cell-Substrate Adhesion Areas, R. G. Richards, G. Rh Owen, B. A. Rahn, I. Ap Gwynn

Cells and Materials

Variability in measurements of the 'cell adhesion strength' of fibroblasts to substrates using mechanical disruption techniques causes difficulty in determining precisely the position, in the cytoskeleton-focal adhesion-matrix -substrate interface, where failure has occurred. In the present study, a quantitative in vitro procedure for measuring the total area and percentage of fibroblast adhesion to biomaterials, using the scanning electron microscope (SEM), is described. The amount of adhesion ofL929 and Balb/c3T3 fibroblasts to discs of stainless steel, commercially pure titanium, and polyethylene terepthalate (Thermanox) was quantified. Cells were fixed, stained with heavy metals, dehydrated and embedded in resin. The resin blocks were …