Biomedical Engineering and Bioengineering Commons^™

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. …

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 …

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 …

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 …

Morphological Characterization Of Maltodextrin Derivatives Using Scanning Electron Microscopy, K. K. Singh, D. J. Robison, Y. V. Pathak

Cells and Materials

This paper deals with the study of the significance of the morphological characteristics of some maltodextrin derivatives in the preparation of tablet dosage forms. Six maltodextrin derivatives, M-040, 100, 150, 180, 500, and 700, with varying dextrose equivalent (DE) values and varying degrees of agglomeration were studied for their suitability in the preparation of the tablets based on the morphological characteristics observed by scanning electron microscopy. A comparison of micromeritic properties, moisture absorption, and morphological characteristics of various maltodextrin derivatives is reported.

In Vitro Studies Of Encrustations On Catheters, A Model Of Infection Stone Formation, W. Schmitz, A. Nolde, G. Marklein, A. Hesse

Cells and Materials

Deposition of infection-induced stone material on urinary catheters is a common problem in urological patients. Therefore, a crystallization model was developed in order to form this material in a reproducible manner. Furthermore, the dissolving potency of two solutions (Suby-G® and Solution-R®) was investigated with this model. The encrustations were examined by infrared (IR) spectroscopy, chemical encrustation analysis , scanning electron microscopy (SEM) and X-ray microanalysis. In addition, the encrustations were calculated from the results of the urine analysis, before and after each experiment, as contents remaining in each artificial bladder. The model conditions changed during the experiment and led to …

A Simple Freeze Fracture Technique For Scanning Electron Microscopy Of Collagenous Biomaterials, David L. Christiansen, George Pins, Frederick H. Silver

Cells and Materials

A simple freeze fracture technique for the ultrastructural analysis of fragile collagenous biomaterials is presented. Following standard methods of preparation and dehydration, fragile biomaterials are fractured with a sharp blade attached to a modified slide hammer. The sliding mass imparts a sudden impact load on the frozen surface of the material , creating a distortion free cleavage plane across the material. More traditional methods including bending and cutting with scissors introduce artifacts indirectly associated with stress concentration produced by bending, and sample compression at the edges with cutting. The impact loading of the sample during fracture results in preservation of …

The Effect Of Peo Ratio On Degradation, Calcification And Bone Bonding Of Peo/Pbt Copolymer (Polyactive), C. A. Van Blitterswijk, J. V.D. Brink, H. Leenders, D. Baaker

Cells and Materials

In this study, we evaluated the effect of PEO/ PBT proportion on the behavior of a range of PEO/ PBT segmented copolymers (Polyactive) during subcutaneous and intrabony implantation in the rat. It was demonstrated that varying the PEO proportion affected degradation, calcification and bone-bonding. The PEO/PBT 70/30 and 60/40 showed extensive degradation after 1 year, PEO/PBT 55145 an intermediate degradation, and the 40/60 and 30170 copolymers showed little and hardly any degradation respectively. PEO content also affected the degree of calcification . PEO/PBT 70/30 showed extensive and early calcification whereas almost no calcification was seen with PEO/PBT 30170. Since calcified …

Characterization Of Bovine Osteoclasts On An Ionomeric Cement In Vitro, D. H. Szulczewski, U. Meyer, K. Moller, U. Stratmann, S. B. Doty, D. B. Jones

Cells and Materials

Primary bovine osteoclasts were obtained by an outgrowth method from bovine periosteum and cultured for 7 days on an ionomeric cement for biomaterial testing. Osteoclasts cultured on slices of bovine bone and on glass microscope cover-slides served as a control. The cells were characterised as osteoclasts by a number of tests. Osteoclasts showed positive staining for tartrate resistant acid phosphatase and reactivity with the antibodies 13C2 and 23C6, which react with the alphachain of the vitronectin receptor. Addition of salmon calcitonin to the culture medium led to sudden cessation of lamellipodial activity. The cells resorbed bone by making pits. 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 …

Microstructural Enhancement Of Dental Composite And Ceramic Materials By Plasma Etching, H. J. Mueller, M. S. Bapna

Cells and Materials

Radio frequency plasma etching of a selected number of dental materials , including glass filled polymeric composites, alumina reinforced ceramic, glass ionomer, and zinc oxide eugenol enhanced microstructural detail for scanning electron microscopy analyses. All four plasmas, argon , oxygen, carbon tetrafluoride (CF4), and CF4 + 4% 0 2 , proved effective, but the latter was the most effective. The etching of all materials , except the ceramic, was accomplished by the selective removal of a polymeric component. For the glass filled composites , this involved removal of the Bis-GMA matrix resin, leaving the filler particles in relief. For a …

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 …

Scanning Electron Microscopy Of The Osteoclast-Bone Interface In Vivo, H. Zhou, R. Chernecky, J. E. Davies

Cells and Materials

Rat femoral bones were studied by scanning electron microscopy to demonstrate the morphology of osteoclast- bone matrix interfacial relationships. Two general morphological types of actively resorbing osteoclasts were observed . One cell type was approximately ovoid with highly fimbriated borders, fully attached and closely adapted to the resorption surface. The ruffled border of such cells was composed of a number of individual filopodia which were of uniform , regular shape and approximately 2-3 μm in length and 150 nm in diameter. They were found to penetrate the bone matrix to a depth of 1 μm and interdigitated with the surrounding …

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 …

Analysis Of The Bony Interface With Various Types Of Hydroxyapatite In Vitro, J. D. De Bruijn, J. S. Flach, K. De Groot, C. A. Van Blitterswijk, J. E. Davies

Cells and Materials

Rat bone marrow cells, capable of forming bonelike tissue, were cultured on three types of plasma sprayed hydroxyapatite that differed in degree of crystallinity from 15%, 43% to 69%. The interface between the mineralized extracellular matrix and the hydroxyapatite was studied with scanning and transmission electron microscopy. At the onset of bone formation, calcium and phosphorous-rich afibrillar globules, with a diameter varying from 0.2 to 0.8 μm, were produced and deposited onto the different substrata. These globules subsequently fused to form a homogeneous layer to which collagen fibres became anchored. Individual globules could be distinguished on the non-degrading 69 % …

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 …

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 …

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 …

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.

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 …

The Peo/Pbt Copolymer-Mineralized Matrix Interface In Vitro, A. M. Radder, J. E. Davies, H. Leenders, C. A. Van Blitterswijk

Cells and Materials

Previous implantation experiments have investigated the interaction between a series of PEO/PBT copolymers (Polyactive®) and bone tissue, and shown the morphology of bone-bonding with several PEO/PBT ratios. However, the underlying mechanism of bone-bonding remains largely unknown. Therefore, an in-vitro approach was chosen to obtain more information on the events occurring at the PEO/PBT copolymer-bone interface. Rat marrow cells were cultured on two PEO/PBT copolymer proportions: a 60/40 ratio which is known to bond with bone tissue in-vivo and a 30170 ratio which, within one year of implantation, does not bond with bone. Evaluation was performed with light microscopy, scanning, backscatter …

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 …

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 …

The Effect Of Substratum Roughness On Osteoclast-Like Cells In Vitro, K. Gomi, J. D. De Bruijn, M. Ogura, J. E. Davies

Cells and Materials

Calcium phosphate powders were used to produce three groups of experimental substrata for the culture of primary rat bone marrow cells in conditions which permitted the survival and function of osteoclasts. Each of the three experimental groups were subdivided by differences in substratum surface roughness and following a culture period of 7 to 11 days, the culture units were stained for tartrate-resistant acid phosphatase activity. In all samples both small, sometimes mononuclear, and large multinucleate cells stained positive for tartrate-resistant acid phosphatase activity and the numbers and types of cells were quantified and statistically analyzed. Following histochemical staining the samples …

Microstructure Of Mica Glass-Ceramics And Interface Reactions Between Mica Glass-Ceramics And Bone, W. Holand, W. Gotz, G. Carl, W. Vogel

Cells and Materials

This review paper characterizes glass-ceramics containing mica as main crystal phase. The phase formation reactions in dependence of the chemical composition and the microstructure are shown. Microstructure of mica glass-ceramics has been studied by electron replica and scanning electron microscopic (SEM) techniques.

Mica glass-ceramics have previously been developed in Si02-B20rA120rMgO-F--base glasses. The material is machinable because of the precipitation of micas of fluorophlogopite-type. Also, a machinable glass-ceramic for dental applications was developed based on KMg2_5(Si40 10)F2-micas. We developed mica glass-ceramics in the Si02-Al20rMgO-NaiO-K20-F glass system. Phase formation within these glasses was observed by SEM. A double controlled nucleation and crystallization …

The Effect Of Polymethylmethacrylate Bone Cement Vibration On The Bone-Cement Interface, A. M. C. Thomas, D. J. W. Mcminn, M. Haddaway, I. W. Mccall

Cells and Materials

Low frequency vibration of polymethylmethacrylate (PMMA) bone cement reduces the viscosity of the cement by shear thinning. The effect of this low frequency vibration on the bone-cement interface was studied using microfocal radiography (MFR) and scanning electron microscopy (SEM). Effects were studied in-vitro and in-vivo. In-vitro, samples of Palacos low viscosity PMMA were placed on blocks of Kiel bone and vibrated. MFR and SEM demonstrated an improvement in the appearance of the bone-cement interface. In-vivo, PMMA was injected into the upper tibia of the dog. An assessment of the effect of high and low pressure injection, and the effect of …

Ultrastructural Assessment Of Lesion Development In The Collared Rabbit Carotid Artery Model, J. E. Beesley, A. C. Honey, J. F. Martin

Cells and Materials

Cellular reactions associated with the formation of lesions generated in the carotid artery of rabbits fed either normal or high cholesterol diets by the placement of a flexible, silastic collar around the artery, were studied by electron microscopy.

Endothelial cells remained as a monolayer throughout lesion development. The endothelial cell surface in both experimental and sham operated carotids, 4 hours and 8 hours after the initiation of the experiments, were covered with platelets and leukocytes. Neutrophils were present until 7 days in the arteries from within the collar of animals maintained on a normal diet, but only to 1 day …

The Effect Of Serial Passaging Of Lactobacilli In Liquid Medium On Their Physico-Chemical And Structural Surface Characteristics, Pieter L. Cuperus, Henny C. Van Der Mei, Gregor Reid, Andrew W. Bruce, Antoine E. Khoury, Paul G. Rouxhet, Henk J. Busscher

Cells and Materials

The aim of this study was to examine the effect of serial passaging in liquid medium on physico-chemical and structural surface characteristics of two lactobacillus strains. To this end, starting cultures (p = 1) of urogenital isolate L. acidophilus RC 14 and poultry isolate L. fermentum B54 were serially passaged in liquid medium up to 20 times (p = 20). In both strains, similar physico-chemical and structural changes were observed following serial passaging. According to water contact angle measurements , cells in p = 20 cultures became less hydrophobic. Microelectrophoresis showed that isoelectric points shifted towards the acidic region upon …

The Incorporation Of Glass-Ceramic Implants In Bone After Surface Conditioning Glow-Discharge Treatment, C. M. Muller-Mai, C. Voigt, R. E. Baier, U. M. Gross

Cells and Materials

Glow discharge (GD)-treated and autoclaved glass-ceramics of bone-bonding and non-bonding type were implanted into the femoral diaphysis of rats for 3, 7, 14 and 28 days and were investigated by applying light microscopy and histomorphometry , and scanning and transmission electron microscopy. More bone and chondroid, and faster osteoid development were observed at glow-discharge treated implants even in nonbonding implants when compared to autoclaved controls. Ultrastructural investigations showed a higher leach ing- rate of GD-treated bone-bonding implants during the early days after implantation leading to a higher rugosity, whereas no morphological changes were observed on non-bonding implant surfaces. More extracellular …