Biomedical Engineering and Bioengineering Commons^™

Backscattered Electron Imaging To Enhance Microstructural Contrast In Poly(Methyl Methacrylate) Bone Cement Fracture Analysis, L. D. T. Topoleski, P. Rutledge, X. Lu

Cells and Materials

Poly(methyl methacrylate) (PMMA) bone cement is used as a grout to secure joint replacement prostheses into bone. It has a distinct microstructure made up of: prepolymerized beads, an interbead matrix polymer, a radiopacifier {barium sulphate (BaS04) or zirconium dioxide (Zr02)}, and pores or voids; the radiopacifier is found only in the interbead matrix of the cured bone cement. The mechanism of slow or fatigue crack growth appears to be initial micro-cracking through the interbead matrix, followed by coalescence of the microcracks to form a continuous crack. Thus, distinguishing the interbead matrix from the pre-polymerized beads is important for investigating fatigue …

Biodegradation Of Synthetic Biphasic Calcium Phosphate And Biological Calcified Substratum By Cells Of Hemopoietic Origin, A. Soueidan, O. I. Gan, J. M. Bouler, F. Gouin, G. Daculsi

Cells and Materials

Different types of osteoclastic cells (authentic osteoclasit from human giant cell tumor and bone marrow of newborn rats; newly-formed osteoclasts from adult rat bone marrow), giant multinucleated cells and macrophages were studied for their effect on synthetic and natural mineralized substrata. Biphasic calcium phosphate ceramic consisted of hydroxyapatite and beta tricalcium phosphate was chosen for in vitro experiments, and dentine served as a positive control for cell resorbing activity . Our results show the limited capacity of authentic and newly-formed osteoclasts to resorb synthetic ceramic as compared to that of natural substrata. In vitro cell-mediated biodegradation included also modifications of …

Resorption Of Natural Calcium Carbonate By Avian Osteoclasts In Vitro, G. Guillemin, S. J. Hunter, C. V. Gay

Cells and Materials

Osteoclasts isolated from the endosteum of 2.5 to 3-week chick tibia were cultured on glass coverslips or natural CaC03 (Tridacna) wafers for 2 and 4 days. The cells were exposed to the pH-dependent dye, acridine orange, and fluorescence was measured by a light microscope photometer. Fluorescence intensity values were higher in cells adherent to Tridacna wafers than in those incubated on glass after 2 and 4 days of culture (three and two-fold, respectively). Moreover, osteoclasts on Tridacna wafers were more flattened and were found to produce resorption pits. Acid production by osteoclasts cultured on Tridacna wafers was stimulated …

Cell Adhesion To Crystal Surfaces: A Model For Initial Stages In The Attachment Of Cells To Solid Substrates, D. Hanein, B. Geiger, L. Addadi

Cells and Materials

This study addresses the mechanism of the chirally-restricted, ROD-independent adhesion of A6 epithelial cells to the {011} faces of calcium {R,R)-tartrate tetrahydrate crystals. The extensive and rapid adhesion of the cells to these surfaces, in the presence or absence of serum proteins, is distinctly different from the extracellular matrix-mediated adhesion to conventional tissue culture surfaces or to the {101} faces of the same crystals. The differences are manifested by insensitivity to ATP depletion, to disruption of microfilaments and microtubules and even to formaldehyde fixation of the cells. Furthermore, trypsin pretreatment does not affect cell attachment to the {011} faces, nor …

Room Temperature Aging Of Pd-Cu-Ga Dental Alloys, William A. Brantley, Zhuo Cai, Qiang Wu, Alan B. Carr, John C. Mitchell

Cells and Materials

Specimens of three Pd-Cu-Ga dental alloys cast five years ago and subsequently stored at room temperature were reexamined and observed to have lower amounts of the eutectic constituents in the near-surface region than originally present, along with other microstructural changes. This previously unreported room temperature aging behavior of these alloys is attributed to the presence of high-diffusivity paths in the non-equilibrium ascast eutectic structures and to the essential role of the surface for the vacancy diffusion mechanism. These results may have important clinical significance for the ill vivo corrosion resistance and long-term biocompatibility of the Pd-Cu-Ga alloys.

Biomaterials Associated Infections: The Scale Of The Problem, David J. Stickler, Robert J. C. Mclean

Cells and Materials

The biomaterials used in the manufacture of implanted prosthetic devices profoundly impair the host's ability to opsonise and phagocytose invading microbes. As a result, while these devices generally provide effective relief from painful, crippling and life-threatening disorders, they can also induce vulnerability to infection in the recipients. The surfaces of the implants are susceptible to colonisation by microbial biofilms. The cells in the biofilm.s are further protected against opsonophagocytosis and are also resistant to antibacterials. Device associated infections thus tend to be refractile to antibiotic therapy and in many cases the device has to be removed before the infection will …

Synthetic Hydrogel As An Artificial Vitreous Body. A One-Year Animal Study Of Its Effects On The Retina, T. V. Chirila, I. J. Constable, Y. Hong, S. Vijayasekaran, M. F. Humphrey, P. D. Dalton, S. G. Tahija, M. A. L. Maley, M. J. H. Cuypers, C. Sharp, S. R. Moore, M. J. Davies

Cells and Materials

A hydrogel with a high water content was assessed in vitro and in vivo as a possible vitreous substitute. From a large series of polymers produced by the aqueous polymerization of methyl acrylamidoglycolate methyl ether (MAGME), a gel synthesized in 80% water was selected for an animal study. The gel was injected intravitreally into rabbit eyes and followed clinically by ophthalmoscopy, tonometry, and fundus photography. The gel was clinically well tolerated, but after 6 months ophthalmoscopy revealed progressive pallor of the optic nerve head. The eyes were enucleated one year after injection of polymer. Histopathological examination by light microscopy of …

Three-Dimensional Morphology And Platelet Adhesion On Pyrolytic Carbon Heart Valve Materials, S. L. Goodman, K. S. Tweden, R. M. Albrecht

Cells and Materials

Low-temperature isotropic pyrolytic carbon (LTIC) is the preferred material for mechanical heart valve prosthetics due to its durability and good thromboresistance, although thromboembolic complications remain a significant clinical problem. LTlC morphology has been previously studied using scanning (SEM) and transmission electron microscopy (TEM), and scanning tunneling microscopy (STM). However, these microscopies have limitations with imaging rough surfaces. In this study, LTIC valve leaflets from CarboMedics, Inc. and St. Jude Medical, Inc. were prepared and polished exactly as used in clinical prosthetics, and examined at magnifications up to macromolecular resolution using stereo-pair low-voltage SEM (LV -SEM). LV -SEM reveals that LTIC …

A Morphological Assessment Of Bovine Chondrocytes Cultured On Poly(Ethyl Methacrylate)/Tetrahydrofurfuryl Methacrylate, R. M. Sawtell, M. V. Kayser, S. Downes

Cells and Materials

A heterocyclic methacrylate polymer system, PEMA/THFMA, has shown potential as a biomaterial for cartilage repair in a rabbit model and has properties making it suitable for use clinically. The ability of the polymer system, PEMA/THFMA, and a related system, PEMA/HEMA, to support chondrocytes in vitro was assessed by scanning electron microscopy. Chondrocytes adhered to the surface of the PEMA/THFMA by day one, having a rounded morphology and clustered appearance opposed to the Thermanox® control, where the cells had spread out and become fibroblastic in appearance. The chondrocytes divided rapidly on the PEMA/ THFMA system by day three and had completely …

Adsorption Of Bovine Serum Albumin Onto Octacalcium Phosphate And Its Hydrolyzates, O. Suzuki, H. Yagishita, M. Yamazaki, T. Aoba

Cells and Materials

Octacalcium phosphate (OCP) has been advocated to be a precursor of biomineral s. Tn this report , we aimed at investigating OCP hydrolysis and the interaction of OCP and its hydrolyzates (apatitic products) with bovine serum albumin (BSA). A batch of synthetic OCP was allowed to hydrolyze either (a) in deionized water at 70°C or (b) in Tris buffer (pH 7.4) containing 2 ppm fluoride at 37°C. OCP hydrolysis was completed within reasonable experimental periods: after 48 hours at 70°C and after 10 days at 37°C in the presence of fluoride. The adsorption isotherms of BSA onto the original OCP …

Adsorption Of Proteins At Solid-Liquid Interfaces, Willem Norde

Cells and Materials

This paper concisely reviews the general principles underlying protein adsorption from aqueous solution onto a solid surface. The discussion includes the various stages of the adsorption process, i. e., transport of the protein molecules towards the surface, the absorbed amount under equilibrium conditions, desorption and re-adsorption. Among the interactions that determine the overall protein adsorption process (1 ) redistribution of charged groups in the interfacial layer, (2) changes in the hydration of the sorbent and the protein surface, and (3) structural rearrangements in the protein molecule play major roles. Special attention is given to the relation between the structural stability …

Creep Fatigue, Part Iii: Diercks Equation: Modification And Applicability, Tarun Goswami

Biomedical, Industrial & Human Factors Engineering Faculty Publications

Creep-fatigue data of low allow steels were compiled from international sources, and trends in creep-fatigue behavior were identified in Paper I. Methods of life prediction and their trends were examined in Paper II with respect to compiled data. Diercks equation, a multivariate creep-fatigue life extrapolation equation, for SS, 304, in terms of strain range, temperature, hold time and strain rate parameters is modified and extended to the life prediction of low alloy steels in this paper.

Reliability Of Human Fresh And Frozen Gingiva Explant Culture In Assessing Dental Materials Cytocompatibility, R. Warocquier-Clerout, G. C. Hachom-Nitcheu, M. F. Sigot-Luizard

Cells and Materials

An explant culture of human gingival epithelium has been set up in order to provide a valuable test for evaluating the cytocompatibility of dental material s. In an attempt to supply a bank of gingiva ex plants, frozen and freshly excised specimens were cultured in parallel. Optical and scanning electron microscopy showed an early release of cuboidal cells forming a dense layer around the explants. Afterwards, cultures evolved differently . Spread cells grew and migrated more rap idly in fresh than in frozen explant cultures but their adhesion to substratum increased earlier in frozen ones. Epithelial phenotype of cells had …

Biphasic Sodium Fluoride Effects On Bone And Bone Mineral: A Review, P. -T. Cheng, S. M. Bader, M. D. Grynpas

Cells and Materials

This paper reviews the clinical and experimental findings on the effects of sodium fluoride (NaF) on human and animal bone. NaF has been shown to cause a significant increase in axial skeletal bone mass. However, there is concern that the new bone may not provide the desired increase in bone strength. Yet, NaF remains the most commonly used agent capable of stimulating bone formation in most patients (30% non-responders). But whether NaF reduces vertebral fracture rate (VFR) remains controversial. For a given treatment duration, the effect of F on bone quality appears to depend on dose: there is a marked …

Natural History Of Bone Response To Hydroxyapatite-Coated Hip Prostheses Implanted In Humans, P. Frayssinet, D. Hardy, J. S. Hanker, B. L. Giammara

Cells and Materials

A series of 15 autopsied femurs containing hydroxyapatite- coated (HA-coated) prostheses was analysed histologically. Their implantation time ranged from 5 days up to 3 years. The coating thickness of some prostheses and the percentage of the coating in contact with bone at different levels were evaluated using an image analysis device. After the newly formed bone tissue had became mature, several bone morphotypes were identified at the coating contact. From the proximal to the distal part of the prosthesis, bone morphotype was denser and the percentage of the coating surface in contact with bone increased. Several stages in the prosthesis …

Treatment Of Pentachlorophenol With Manganese Oxide Addition To Biotic And Abiotic Sediments, R. Petrie, J. E. Mclean, Ronald C. Sims

Biological Engineering Faculty Publications

Laboratory microcosms containing subsamples of a complex environmental sediment were used to evaluate the addition of oxidized manganese as the primary electron acceptor in the presence of pentachlorophenol (PCP) as the primary electron donor. Manganese oxide (MnO₂) particles were added to poisoned abiotic and non-poisoned biotic microcosms and incubated at 11°C in the presence of sediment samples that were shown capable of mineralizing PCP with indigenous microorganisms. Reduction in PCP concentration and production of reduced manganese was measured for both abiotic and biotic systems.

PCP was observed to be transformed most rapidly and to the greatest extent in …

Evaluation Of Biological Treatability Of Soil Contaminated With Manufactured Gas Plant Waste, J. S. Ginn, Ronald C. Sims, I. P. Murarka

Biological Engineering Faculty Publications

The biological treatability of subsurface soil contaminated with manufactured gas plant (MGP) waste was evaluated. Mineralization assays incorporating ¹⁴C-phenanthrene were used to evaluate the biotransformation potential of indigenous microorganisms at the site. Multi-phase laboratory microcosms were used to evaluate the interphase transfer potential and chemical mass distribution of phenanthrene. The Microtox™ bioassay was used to evaluate detoxification trends at the site. Mineralization results indicated that indigenous microorganisms at the site were capable of transforming phenanthrene, a component of coal-tar creosote. Results also indicated that spiked ¹⁴C-phenanthrene mineralization was influenced by nutrient addition and by the amount of contamination. …

Mn-Catalyzed Oxidation Of Multiple-Ringed Aromatics, G. Whelan, Ronald C. Sims

Biological Engineering Faculty Publications

The role of manganese (Mn) oxides in catalyzing the abiotic oxidation of polynuclear aromatic compounds (PNAs) has been investigated by monitoring the oxidation of dihydrodiol and dione PNAs and corresponding reduction of Mn in an aqueous environment. 1,4-, 1,3-, and 2,3-naphthalenediol, 1,4-naphthoquinone, and l,4-dihydroxy-9,10-anthracenedione (Quinizarin) were oxidized in an oxic, aqueous environment, where each of these organic compounds is soluble in water, except Quinizarin. A mathematical model is presented, which describes the redox reactions, and suggests that electron transfer/organic release from the oxide surface is rate limiting with the reaction apparently proceeding through a free-radical formation. Results indicate significant oxidation …

Mn-Catalyzed Oxidation Of Naphthalenediol, G. Whelan, Ronald C. Sims

Biological Engineering Faculty Publications

This study investigates the effects that manganese(IV) dioxide particles have on 2,3-naphthalenediol at varying pH levels (i.e., initial pH of 4.58, 5.85, and 8.75) and under different organic concentration conditions (4×¹⁰⁻³, 4×¹⁰⁻⁴, and 4×¹⁰⁻⁵ M), and assesses the importance of Mn oxides on abiotic catalysis of the multiple-ringed aromatic compound. Proton concentration affected the rates of reductive dissolution; as the pH values increased, the rate of reductive dissolution decreased, as predicted by theory. Also, as the concentration of naphthalenediol increased, the rate of reductive dissolution increased, although not proportionally; thus indicating that a majority of …

Optical Bone Chambers As Tools For Studying The Bone-Implant Interface: A Review, Howard Winet

Cells and Materials

Bone chamber intravital microscopy combines the control volume of in vitro models and the chemical complexity of in vivo models to optimize the study of bone physiology in situ. As an optical tool it provides a window to dynamic events at the tissue level of magnification. In particular, it allows measures of microvascular events: (1) in space by magnifying local perfused vasculature and microcirculation at any instant, and (2) in time by providing the same volume of tissue for weekly viewing of an evolving process such as bone healing. This quartz-bearing titanium screw has revealed a consistent order for …

Co-Culture Of Endothelial Cells And Smooth Muscle Cells In A Flow Environment: An Improved Culture Model Of The Vascular Wall?, Thierry Ziegler, Keith A. Robinson, R. Wayne Alexander, Robert M. Nerem

Cells and Materials

Numerous studies have demonstrated that the neighboring smooth muscle cells (SMC) influence the morphology, cytoskeleton and growth of co-cultured endothelial cells (EC). Also, flow-induced laminar shear stress has been shown to induce cell elongation, F-actin reorganization and growth inhibition in cultured EC. We investigated the effect of neighboring SMC and collagen matrix on the response of EC to shear stress. The co-culture system was made by growing porcine aortic SMC in a gel of collagen type I and then seeding porcine aortic EC (P AEC) on the top surface. Then the co-culture was exposed to steady, laminar shear stress of …

Bone Absorptiometry In Metabolic Bone Disease: Baseline Values And Long-Term Treatment With Calcitriol (Post-Menopausal Osteoporosis Versus Osteomalacia), A. Caniggia, B. Frediani

Cells and Materials

Total body bone absorptiometry reveals low mineral density in both postmenopausal osteoporosis and osteomalacia patients. The method was used to investigate the effect of calcitriol administration on patients suffering from one of these conditions. In osteomalacia, the administration of calcitriol resulted in a dramatic improvement in bone mineral density (sometimes up to 50% in 12 months), indicating the rapid mineralization of previously uncalcified bone tissue as a result of the normalization of the Ca x P product. In osteoporosis a similar treatment was seen to halt the progressive decrease in bone mineral levels and sometimes resulted in minor increases in …

Scanning Electron Microscopy Studies Of Ceramic Layers And Interfacial Regions For Calcium Phosphate-Coated Titanium Dental Implants, W. A. Brantley, E. Tufecki, J. C. Mitchell, D. W. Foreman, E. A. Mcglumphy

Cells and Materials

The surface and cross-section characteristics of the plasma-sprayed calcium phosphate coatings, along with the microstructures and elemental compositions near the titanium alloy interface, were investigated by scanning electron microscopy for two different dental implants of proprietary compositions: Integra!® (Calcitek) and BioVent ® (Dentsply). Elemental concentrations (Ca, P, Ti, AI, and V) near the interfaces were obtained by X-ray energy-dispersive spectroscopy. Coating surfaces exhibited a splat deposition topography of greatly differing microstructural scale for the two implants, along with other features characteristic of the plasma-spraying process; cross-sections of the coatings revealed minimal porosity. Some interdiffusion of principally titanium and calcium was …

Some Biological And Physical Properties Of Laser Deposited Hydroxyapatite Based Films, Tatjana Dostalova, Lucie Himmlova, Miroslav Jelinek, Jirina Bartova

Cells and Materials

The preliminary results of biological and physical tests of hydroxyapatite thin films deposited on dental implants by a new technology with the KrF excimer laser ablation method were evaluated. Biological and physical properties were studied and analyzed by the lymphocyte proliferation test and scanning electron microscopy (SEM), X-ray analysis, Rutherford backscattering analysis (RBS) and particle induced X-ray emission (PIXE) methods. Ten bioceramic films from 45 samples had very good physical and biological properties. Creation of hydroxyapatite thin films with laser ablation can have a positive effect on adhesion of the film and protection for corrosion.

Some Observations On The Structure Of Encrusting Biofilms Of Proteus Mirabilis On Urethral Catheters, C. Winters, D. J. Stickler, N. S. Howe, T. J. Williams, N. Wilkinson, C. J. Buckley

Cells and Materials

A physical model of the bladder has been used to study the process of urinary catheter encrustation. Techniques have been devised for the preparation of sections through these encrustations in situ on the luminal surfaces of catheters and for mapping the distribution of calcium and magnesium in the biofilms. Transmission electron microscopy on these sections showed struvite-like crystals lying in the matrix and in direct contact with the catheter surface. Calcium phosphate ("bioapatite") was distributed throughout the film and many of these amorphous particles appear to have cells at their cores. Freeze-substituted sections of biofilms also showed electron dense materials …

Random Roughness Assessment By The Pin And Chain Method, John E. Gilley, E. R. Kottwitz

Department of Agricultural and Biological Systems Engineering: Faculty Publications

Surface microrelief is frequently characterized using random roughness factors (RRF) defined by Allmaras et al. (1966). Random roughness factors are usually measured using a pin roughness meter or laser. Saleh (1993) recently proposed the chain method as a relatively simple, fast, and inexpensive technique for characterizing surface microrelief. The chain method is based on the principle that as a chain of given length is placed across a surface, the horizontal distance covered by the chain will decrease as surface roughness increases. Reductions in chain length caused by surface roughness are described as Saleh roughness factors (SRF).
In this study, RRF …

Soy Protein Isolate/Poly(Ethylene Oxide) Films, V. M. Ghorpade, A. Gennadios, M. A. Hanna, Curtis L. Weller

Department of Agricultural and Biological Systems Engineering: Faculty Publications

Films were prepared by casting and drying alkaline aqueous film-forming solutions of soy protein isolate (SPI). Four additional types of films were made by combining SPI with poly(ethylene oxide) (PEO) in SPI to PEO ratios of 19:1, 9:1, 4:1, and 1.5:1 (w/w). Glycerin was added to all film-forming solutions as a plasticizer at 60% of total solid weight. Addition of PEO decreased film tensile strength (TS) and increased elongation at break (E). TS values ranged from 1.4 to 3.9 MPa and E values ranged from 83 to 152%. Water vapor permeability of the films ranged from 3.0 x 10^{-9 …}

Thermomechanical Behavior Of Wheat Gluten Films: Effect Of Sucrose, Glycerin, And Sorbitol, George Cherian, Aristippos Gennadios, Curtis L. Weller, Pavinee Chinachoti

Department of Agricultural and Biological Systems Engineering: Faculty Publications

Glass transition temperature (T_g) and mechanical and water vapor barrier properties of wheat gluten films containing glycerin, sucrose, glycerin-sucrose, and glycerin-sorbitol were studied. Glycerin and sucrose were immiscible; the wheat gluten film containing both solutes showed two separate thermal transitions (-58°C and -5°C, respectively). The low temperature (low-T) transition (-58°C) was due to a glycerin-rich region. The low-T tan δ peak height influenced the tensile strength and elongation linearly and the water vapor permeability (WVP) curvilinearly. However, the T_g failed to change with solute composition and exhibited low correlation with barrier and mechanical …

Darcy-Weisbach Roughness Coefficients For Surfaces With Residue And Gravel Cover, John E. Gilley, Eugene R. Kottwitz

Department of Agricultural and Biological Systems Engineering: Faculty Publications

Several types of hydraulic resistance factors may be present on upland agricultural areas. It is not known whether roughness contributions from individual elements are additive or if interactions between resistance factors may occur. In this study, Darcy-Weisbach roughness coefficients were measured on surfaces containing corn-soybeans, sorghum-cotton, and sunflower-wheat residue in addition to gravel cover. Varying rates of flow were introduced into a flume in which residue and gravel materials were securely attached. Roughness coefficients were calculated from measurements of discharge rate and flow velocity for Reynolds number values varying from approximately 1,200 to 13,000. The laboratory data were then used …

Auger Design For Uniform Unloading Of Granular Material: I. Rectangular Cross-Section Containers, David D. Jones, Michael F. Kocher

Department of Agricultural and Biological Systems Engineering: Faculty Publications

Design equations were developed for two auger configurations that for practical purposes generate uniform vertical flow of granular material through containers or boxes having a rectangular cross-section. Both configurations have uniform outside diameters so the simple geometry of the conventional U-trough housings could be used with these augers. One configuration had a uniform pitch for the auger flighting and decreasing inside diameter. The other had a uniform inside diameter and a decreasing pitch of the flighting with distance from the outlet end of the auger. Both configurations dramatically improved the uniformity of flow over the conventional auger. However, confidence intervals …