Biomedical Engineering and Bioengineering Commons^™

Metallurgical Structures Of As-Cast And Heat-Treated High-Palladium Dental Alloys, William A. Brantley, Zhuo Cai, Alan B. Carr, John C. Mitchell

Cells and Materials

Scanning electron microscope observations and energy-dispersive spectroscopic analyses have been performed on two first-generation and two second-generation high-palladium dental casting alloys. A specimen design simulating a maxillary central incisor coping was employed to conserve metal, while providing thin and thick sections to yield a range of solidification rates. The alloys were centrifugally cast in air, following standard dental laboratory techniques; three castings were prepared for each alloy. Each casting was sectioned to produce two mirror-image specimens, and one specimen received the appropriate oxidation heat treatment, followed by a simulated full porcelain firing sequence. After metallographic polishing, specimens were examined with …

A Comparative Study Of The Interactions Of Two Calcium Phosphates, Peo/Pbt Copolymer (Polyactive) And A Silicone Rubber With Bone And Fibrous Tissue, C. A. Van Blitterswijk, J. R. De Wijn, H. Leenders, J. V.D. Brink, S. C. Hesseling, D. Bakker

Cells and Materials

In this study, hydroxyapatite, tetracalcium phosphate, HPEO/PBT 55145 copolymer, PEO/PBT 55!45 copolymer (Polyactive) and silicone rubber were implanted as dense blocks, subcutaneously and. into the tibia of rats. Biocompatibility and degradation were investigated but most attention was directed to .the bone/biomaterial interactions. None of the materials showed any significant adverse tissue reactions. With exception of the silicone rubber, all materials sho~ed bone bonding phenomena based on both morphological and mechanical evaluations. (H)PEO/PBT 55145 copolymer is the first polymer reported to be bonded by bone and thus widens the spectrum of bone bonding materials with a low modulus, degradable, elastomer in …

A Scanning Electron Microscope Study Of The Ultrastructural Organization Of Bone Mineral, F. B. Bagambisa, U. Joos, W. Schilli

Cells and Materials

Scanning electron microscopy (SEM) was used to study samples of lamellar bone at magnifications typical for the published transmission electron micrographs, to gain more insight into the three-dimensional ultrastructure of bone mineral. Untreated (whole bone) samples allowed an assessment of the degree of mineralization. Deproteinized samples revealed the ultrastructural form and organization of bone apatite to be a function of the extent to which collagen fibers were imbibed with mineral. Numerous parallel formations reminiscent of troughs, gutters, or furrows, pierced and traversed the mineralization front. These troughs showed varying diameters identifiable with collagen fibers, and were separated from one another …

Immunohistochemical Investigation Of Tracks Left By The Migration Of Fibroblasts On Titanium Surfaces, Y. Abiko, D. M. Brunette

Cells and Materials

Fibronectin, a major attachment protein, has been thought to be involved in pathway guidance, a process in which cells migrate along specific pathways within a tissue during development. Fibroblasts exhibit the phenomenon of contact guidance, the tendency of cells to be guided in their direction of migration by the shape of the substratum. The purpose of our study was to test the hypothesis that fibronectin tracks are deposited by fibroblasts moving on smooth and grooved titanium surfaces.

The study was carried out on human gingival fibroblasts which were plated onto both smooth and grooved titanium substrata using medium containing either …

Mineralization Of An Axially Aligned Collagenous Matrix: A Morphological Study, D. L. Christiansen, F. H. Silver

Cells and Materials

Bone can be described as a highly ordered composite of type I collagen integrated with an inorganic mineral phase. In vitro models of bone mineralization using collagenous substrates have been reported in the literature. This study reports an in vitro system of mineralized reconstituted collagen fibers, with aligned fibrillar substructure. The collagen fibers were mineralized in a double diffusion chamber saturated with respect to calcium and phosphate. The morphology and ultrastructure of the mineral precipitate were evaluated as a function of the pH of the incubating media. Brushite crystal was observed at acidic pH. Large rectangular crystals formed at pH …

Pulpal Response To Calcium Phosphate Materials. In Vivo Study Of Calcium Phosphate Materials In Endodontics, A. H. Jean, J. A. Pouezat, G. Daculsi

Cells and Materials

The aim of this study was to determine if calcium phosphate (CaP) materials could be used to substitute for calcium hydroxide (CH) as a pulp capping agent. Especially prepared and characterized CaP materials with CH as the reference or control material were used for pulpcapping teeth of pigs, rats, and dogs. The CaP materials included: DCPD (dicalcium phosphate dihydrate), OCP (octacalcium phosphate), ß-TCP ({3-tricalcium phosphate), BCP (biphasic calcium phosphate mixture of 50150 HA and ß-TCP), and HA (hydroxyapatite) which were used in particle sizes of < 5 μm or < 150 μm. The animals were sacrificed after 21 days to …

Preferential Adhesion Of Urethral Bacteria From A Mixed Population To A Urinary Catheter, Gregor Reid, Christina Tieszer

Cells and Materials

The ability of uropathogens to adhere to catheters and subsequently colonize the urinary mucosa leads to urinary tract infections which afflict a large patient population. In vitro studies were carried out whereby Escherichia coli Hu734 (water contact angle 12 °) and Enterococcus faecalis (19°) were found to be highly adhesive to silicone latex urinary catheters. The addition of one of four Lactobacillus sp., with water contact angles ranging from 19-105 °, to the suspending fluid caused a 60-86% reduction in pathogen adhesion with a significant effect against E. coli, the organism most commonly found to infect the urinary tract. …

Experimental Induction Of Odontoblast Differentiation And Stimulation During Preparative Processes, H. Lesot, C. Begue-Kirn, M. D. Kubler, J. M. Meyer, A. J. Smith, N. Cassidy, J. V. Ruch

Cells and Materials

In vivo implantation experiments have shown that ethylenediaminetetraaceticacid(EDTA)-soluble frac tions of dentin stimulate reparative dentinogenesis . When isolated embryonic dental papillae were cultured in the presence of these dentin constituents, odontoblast cytological and functional differentiation could be initiated and maintained in the absence of an enamel organ. These effects were attributed to the presence of TGF-/1- related molecules [TGF-/11 or bone morphogenetic protein -2a (BMP-2a)] which had to be used in combination with an EDT A-soluble fraction of dentin in order to specifically affect competent preodontoblasts . These EDT A-soluble constituents present in dentin could be replaced by heparin or …

Attachment Kinetics And Differentiations Of Osteoblasts On Different Biomaterials, U. Meyer, D. H. Szulczewski, K Moller, H. Heide, D. B. Jones

Cells and Materials

Primary bovine osteoblast cell cultures were used to study the response of osteoblasts ton three different biomaterials, ionomeric cement (IC), tri-calcium phosphate poly-L-lactic acid composite foil (TCP) and poly-L-lactate-polycitric acid composite foil (PLA). The cells which grew on the materials produced all typical bone matrix proteins and were osteoblast-Iike as shown by immuno-staining. Analysis of the cell attachment kinetics revealed significant differences within the first 7 hours between the various materials. The best rate of cell attachment was found on the IC surface, followed by the TCP and then the PLA surface. The kinetics of attach ment appeared to be …

Organic Extracellular Matrix Components At The Bone Cell/Substratum Interface, X. Shen, E. Roberts, S. A. F. Peel, J. E. Davies

Cells and Materials

We have recently shown that differentiating bone cells are capable of elaborating, in vitro, a calcified matrix at the interface with several non-biological substrata which is similar to cement lines found in remodelling bone tissue. From previous morphological observations, this matrix appeared free of assembled collagen fibres which indicated that osteogenic cells produce an initial mineralized matrix before overt collagen fibre production. In the work reported herein, we used six antibodies to extracellular matrix components and two conjugates of secondary antibody, fluorescein and colloidal gold, to initiate a preliminary characterization of the organic components at the bone cell substratum …

Intravital Microscopic Evidence That Polylactide-Polyglycolide (Plga) Delays Neo-Osteogenesis And Neo-Angiogenesis In Healing Bone, H. Winet, J. O. Hollinger

Cells and Materials

The bone chamber implant (BCI) has allowed monitoring a healing bone defect as well as the effect of an eroding implant on the healing process. The BCI is a useful tool and intravital microscopy a valuable technique for obtaining quantitative data chronicling osseous wound healing. The physiological parameters that form the initial data base documenting healing are neo-osteogenesis and neo-angiogenesis. This review compares and characterizes osseous wound healing in a BCI loaded with an erodible copolymer, PLGA (polylactide-polyglycolide). To determine if a statistically significant deviation from normal healing had occurred, the results were compared with present and historical controls. In …

In-Vivo Reactions In Some Bioactive Glasses And Glass-Ceramics Granules, A. M. Gatti, T. Yamamuro, L. L. Hench, O. H. Andersson

Cells and Materials

Two different bioactive glasses and one glass-ceramic were implanted as granules for 2 months in rabbit muscle and for 5 months in sheep jaw in order to study the influence of the biological surroundings on the reactions of the materials.

Scanning electron microscope and energy dispersive X-ray microanalysis showed that a calcium and phosphorous-rich (CaP) surface layer (adjacent to a silicon rich-layer) forms on both glasses in both implantation sites. The glass-ceramic developed only a CaP layer. A chemical process of degradation was more evident in muscle, even though the implantation time was shorter than that in bone. For all …

Calcification Of Liposomes And Red Cell Ghosts In Vitro And In Vivo, Kookmin M. Kim

Cells and Materials

To study the role of membranous phospholipids in calcification , liposomes made of phosphatidylserine and red blood cell ghosts (RBCG) prepared from rat and canine blood were incubated in minimal essential medium (MEM) with 2 .5 mM (mmol/l) calcium and 1.3 mM phosphate, pH 7.4 (MEM-2.5), and homologous (rat) or autologous (canine) plasma filtrate (serum) at 37°C for up to 1 week. Calcification was determined by electron probe microanalysis , electron diffraction, and depletions of calcium and phosphate from MEM-2.5 and sera. Liposomes and rat-RBCG incubated in MEM-2.5 and serum calcified in a week, whereas isolated collagen and elastin did …

The Structure Of Urinary Catheter Encrusting Bacterial Biofilms, D. J. Stickler, J. King, J. Nettleton, C. Winters

Cells and Materials

A major complication of long-term urethral catheterization is catheter blockage by encrustation. We have examined 20 encrusted catheters and in each case crystal formation was associated with the presence of bacterial biofilms on the luminal surfaces. Scanning electron microscopy and X-ray microanalysis indicated the presence of struvite and hydroxyapatite in the biofilms. Urease producing bacteria were colonizing 16 of the catheters. Proteus mirabilis was the commonest species being recovered from ten of the catheters. These results support the hypothesis that catheter encrustation has a similar etiology to that of infection-induced urinary stones and confirm that the important target for any …

Interaction Of Ciprofloxacin Loaded Liposomes With Pseudomonas Aeruginosa Cells, R. Nicholov, A. E. Khoury, A. W. Bruce, F. Dicosmo

Cells and Materials

An antibiotic delivery system has been developed using ciprotloxacin (CIPRO) encapsulated within sonicated unilamellar vesicles (SUV) of different lipid compositions composed of dipalmitoylphospatidylcholine (DPPC), L-aphosphatidylcholine (PC), phosphatidylethanolamine (PEA) and cholesterol (CHOL). The interaction of SUV (i.e. liposomes) with Pseudomonas aeruginosa (Tl 2977) cells was studied and the effect of the liposome encapsulated antibiotic was tested. Encapsulation of CIPRO apparently increased the amount of antibiotic resident in the vicinity of bacteria in aqueous solution at neutral pH.

Electrophoretic mobility measurements showed that P. aeruginosa cells were negatively charged. The zeta potential of P. aeruginosa was -11.4 ± 2.9 m V in …

Lysine Effect On Ruthenium Red And Alcian Blue Preservation And Staining Of The Staphylococcal Glycocalyx, Theresa A. Fassel, James R. Sanger, Charles E. Edmiston

Cells and Materials

The effect of lysine on ruthenium red (RR) and alcian blue (AB) preservation arid/or staining for transmission electron microscopy of glycocalyces was evaluated for three species of the gram-positive, coagulase-negative staphylococci. A RR and an AB procedure were compared with and without lysine included in the glutaraldehyde prefixation. Minimal or no glycocalyx was preserved or stained by glutaraldehyde fixation only. For all species, the inclusion of lysine increased visualization of fibrous material. RR treatment without lysine, results in sparse or limited fibrous material or artifactual condensations which contrasts with enhanced fibrous material seen when lysine is included with RR. The …

Are Long Term Cryopreservation And Patency Of Vein Allograft Truly Achievable?, G. Pasquinelli, G. L. Faggioli, P. Preda, M. Vici, G. N. Martinelli, R. Giardino, M. D'Addato, J. J. Ricotta

Cells and Materials

Despite extensive experimental work, neither the effect of long term cryopreservation on vein graft architecture nor the failure of alloveins due to graft rejection have yet been investigated. Herein, we investigated ultrastructurally: a) the integrity of rabbit jugular veins following 1, 2 and 3 months of cryopreservation; b) the outcome of the three-month cryopreserved vein auto- and allografts after 1 month of implantation in the rabbit carotid artery; and c) the immunologic response to cryopreserved vein allografts with and without seeded autologous endothelium. Prior to implantation, the cryopreserved rabbit veins were well-maintained except for endothelial cell damage. Following implantation, the …

Immunocytochemical And Lectin-Gold Characterization Of The Interface Between Alveolar Bone And Implanted Hydroxyapatite In The Rat, H. Kawaguchi, M. D. Mckee, H. Okamoto, A. Nanci

Cells and Materials

The tissue response to implanted hydroxyapatite (HAP) in rat alveolar bone was investigated using morphological and cytochemical approaches. High-resolution immunogold labeling was used to examine the distribution of two non-collagenous bone proteins, osteopontin and osteocalcin, and two plasma proteins, a2HSglycoprotein (fetuin) and albumin. Glycoconjugates were characterized by lectin-gold cytochemistry using Ricinus communis I agglutinin and Wheat germ agglutinin. Transmission electron microscopy demonstrated the presence of an electron-dense, lamina limitans-like layer at the HAP particle-bone interface and organic material within the micropores of the particles. Mineral was observed in relation to both these sites. The HAP particle-bone interface was strongly …

Bone Growth On Sol-Gel Calcium Phosphate Thin Films In Vitro, Q. Qiu, P. Vincent, B. Lowenberg, M. Sayer, J. E. Davies

Cells and Materials

Thin, sub-micron, films of calcium phosphate were fabricated on either glass or quartz supports by a colloidal suspension sol-gel method. These films, which varied in both surface chemistry and topography were then employed as culture substrata for osteogenic rat bone marrow cells. During an 18 day culture period, the cells elaborated a morphologically distinguishable bone matrix on all substrata which was similar to that reported earlier on tissue culture polystyrene. Selected samples of the culture substrata were fractured, critical point dried, and observed by scanning electron microscopy. Particular attention was paid to the morphologies of the interface between the so1-gellayer …

Cell-Degradation Of Calcium Phosphate Ceramics, P. Frayssinet, N. Rouquet, F. Tourenne, J. Fages, D. Hardy, G. Bonel

Cells and Materials

Calcium phosphate ceramics are used in bone surgery under different forms: dense or porous ceramic s as bone substitute, thin ceramic coatings on metallic implants as an osseointegration enhancer. Their degradation depends on their physico-chemical properties and particularly on their chemical composition. Natural calcium phosphates of bone are degraded by mononuclear or multinuclear cells and the extracellular matrix induces the differentiation of the degrading-cells. Hydroxyapatite, which is one of the most used calcium phosphates , is known as a low degradation material. However, the histological analysis of implanted HA-materials both in animals and in humans showed that a cellular degradation …

Influence Of Crystal Structure On The Establishment Of The Bone-Calcium Phosphate Interface In Vitro, J. D. De Bruijn, C. P. A. T. Klein, K. De Groot, C. A. Van Blitterswijk

Cells and Materials

An in vitro rat bone marrow cell system was used to examine the interfacial ultrastructure established between various calcium phosphates and mineralized tissue. The investigated calcium phosphates comprised hydroxyapatite (HA), fluorapatite (FA), tricalcium phosphate (TCP), tetracalcium phosphate (TECP) and magnesium whitlockite (MWL). Both scanning and transmission electron microscopy were used to examine the elaborated interface. The time in which a mineralized extracellular matrix was formed on the various materials differed from 2 weeks on HA, TCP and TECP, to 8 weeks on FA. It was only occasionally observed in some areas on MWL, which might have been due to aluminum …

Degradation Of Polymeric Biomaterials, Shalaby W. Shalaby, Russell A. Johnson, Meng Deng

Cells and Materials

Environmental and processing factors affecting the biostability of medical devices made from traditionally "stable" polymers, such as isotactic polypropylene (PP) and ultrahigh molecular weight polyethylene (UHMW-PE) , were analyzed and their undesirable degradation was related to performance of typical medical devices. Among the critical phenomena determining the biological performance of UHMW-PE and PP devices are oxidation during melt-processing and the propensity of the polymer chains to radiolyse and radio-oxidize. Polyesters and their biomedical devices , which can be designed to degrade predictably, are addressed with some focus on the less obvious determinants of performance.

Modification Of Physical And Barrier Properties Of Edible Wheat Gluten-Based Films, Aristippos Gennadios, Curtis L. Weller, Robert F. Testin

Department of Biological Systems Engineering: Papers and Publications

Edible films were produced from wheat gluten-based film-forming solutions. One film was produced as a control. Other types came from subjecting control films to three different soaking treatments. Three additional films were also produced by modifying the control film-forming solution. For all films, selected physical properties and permeability to water vapor and oxygen were measured. Comparisons indicated possible ways to improve the control film. All films were good oxygen barriers but limited water vapor barriers. Films containing hydrolyzed keratin had lower oxygen permeability (83%) and lower water vapor permeability (23%). Films containing mineral oil had lower water vapor permeability (25%). …

Chemical Tracing Techniques For Evaluating Rill Hydraulics, John E. Gilley, Eugene R. Kottwitz

Department of Biological Systems Engineering: Papers and Publications

Development of water erοsiοn and surface water quality control practices requires information concerning the hydraulic characteristics of upland areas. The relatively small flow rates normally found within rills make measurement of hydraulic parameters difficult. Chemical tracing procedures, originally developed for stream and river systems, have been successfully used to measure rill flow properties. A chemical tracer of known concentration is added to the rill and by knowing the degree of dilutiοn at a downstream sampling point, flow rate can be calculated. Rill flow velocity can be measured by determining the time required for a slug of tracer material to travel …

Drying Rate Constants For Yellow Dent Corn As Affected By Fatty Acid Ester Treatments, Curtis L. Weller, J. M. Bunn

Department of Biological Systems Engineering: Papers and Publications

Ethyl oleate and ethyl stearate solutions at various concentrations were used to treat corn samples prior to drying.

Property Modification Of Edible Wheat, Gluten-Based Films, A. Gennadios, Curtis L. Weller, R. F. Testin

Department of Biological Systems Engineering: Papers and Publications

Procedures were developed to produce edible wheat, gluten-based films. A film was produced as a standard. Five additional films were then produced by modifying the initial film-forming solution. Modifications included changing the plasticizer, partially substituting wheat gluten with soy protein isolate and corn zein, and incorporating two acetylated monoglyceride products. All films were characterized by measuring selected mechanical properties, and permeabilities to water vapor and to oxygen. Comparison of the films, in terms of their measured properties, indicates ways to improve the overall performance of the standard film as a potential packaging material. A main limitation of all of the …

Relative Humidity And Temperature Effects On Tensile Strength Of Edible Protein And Cellulose Ether Films, A. Gennadios, H. J. Park, Curtis L. Weller

Department of Biological Systems Engineering: Papers and Publications

The effect of relative humidity and temperature on tensile strength of two types of protein-based [corn zein (CZ) and wheat gluten (WG)] and two types of cellulosic [methylcellulose (MC) and hydroxypropyl cellulose (HPC)] hydrophilic edible films was investigated.

Design And Evaluation Of An Augmentative Communication Aid For Multiply Impaired Individuals, Mark S. Annett

Theses and Dissertations

Individuals with sensory and multiple physical impairments, which may include the loss of the ability to speak, have very specialized communication needs. Based on the belief that the current technology does not fully meet these needs, a prototype communication aid was developed for an individual who is cortically blind, dysphonic, and motor impaired. Furthermore, the communication device has broader applications beyond the present individual.

The prototype system has a direct selection of "Yes" and "No" responses, scanning access to daily phrases, rate enhancement of all scans, prompted encoding for selection of letters, two letter codes for complete sentences, access to …

Crime, Race And Reproduction, Dorothy E. Roberts

All Faculty Scholarship

No abstract provided.

High-Level Expression Of A Heterologous Protein In The Milk Of Transgenic Swine Using The Cdna Encoding Human Protein C, William H. Velander, John L. Johnson, Raymond L. Page, Christopher G. Russell, Anuradha Subramanian, Tracy D. Wilkins, Francis C. Gwazdauskas, Christoph Pittius, William N. Drohan

William H. Velander Publications

Transgenic pigs were generated that produced human protein C in their milk at up to 1 g/liter. The gene construct was a fusion gene consisting of the cDNA for human protein C inserted into the first exon of the mouse whey acidic protein gene. These results demonstrate that the mouse whey acidic protein gene contains regulatory elements that can direct cDNA expression at high levels in the pig mammary gland. Recombinant human protein C that was produced at about 380 pg/ml per hr in transgenic pig milk possessed anticoagulant activity that was equivalent to that of protein C derived from …