bluuebunny/crossref_metadata_2025_split huggingface dataset:
Effects of particulate high‐density polyethylene and titanium alloy on tissue ingrowth into bone harvest chamber in rabbits
Authors: Goodman Stuart , Aspenberg Per , Song Yong , Doshi Amol , Regula Donald , Lidgren Lars 
Published: May 2005

AbstractThe purpose of this study was to determine whether small, phagocytosable particles of titanium alloy (Ti) and high‐density polyethylene (HDPE) have an adverse effect on bone ingrowth. The bone harvest chamber (BHC) was implanted bilaterally in the proximal tibial metaphysis of six mature rabbits. The BHC has a transverse 1‐mm wide pore providing a continuous canal through the chamber for tissue ingrowth. After an initial 6‐week period for osseointegration of the BHC, the contents of the canal were harvested repeatedly at 3 weekly intervals. This could be done with the chamber in place, without disturbing its exterior surface or the surrounding bone. The carrier solution, 1% sodium hyaluronate (Healon) was implanted first. In subsequent implantations, Healon was mixed with particles of HDPE or Ti averaging 4.7 ± 2.1 and 3.0 ± 2.6 μm, respectively. The contralateral chamber was left empty and served as a control. The chambers were harvested repeatedly, alternating experimental and control sides. The sections from the control side, and those containing Healon alone demonstrated extensive trabecular bone in a fibrovascular stroma. The sections containing Ti alloy particles were qualitatively and quantitatively similar to the control sections and those containing Healon, except for the presence of small black granules of Ti alloy, dispersed in the fibrovascular stroma or phagocytosed by scattered macrophages. The sections containing HDPE particles were infiltrated and engulfed by mononuclear and multinuclear histiocytic cells in a highly fibrous stroma. The majority of the multinucleated cells present were interpreted as being foreign body giant cells. Less trabecular bone was seen in the HDPE group compared to the other groups. Using the parameters chosen for this experiment, it would appear that small, phagocytosable HDPE particles are more deleterious to net formation of bone compared to particles of Ti alloy. © 1995 John Wiley & Sons, Inc.
Biological response to ligament wear particles
Authors: Claes Lutz E. , Ludwig Jörg , Margevicius Kristen J. , Dürselen Lutz 
Published: May 2005

AbstractIn ligament replacement cases where the artificial ligament has worn and partially or totally ruptured, the released wear particles have been associated with a chronic synovitis that inhibits integration of the ligament and contributes to the ultimate failure of the device. In this study, the biological response to ligament wear particles from nine different artificial ligaments was quantitatively evaluatedin vivo. Wear particles, the majority of which were <7 μm, were generatedin vitro. These particles were injected into rabbit knee joints, and the biological response as well as the systemic migration of the particles were evaluated histologically after 4 weeks. The extent of the inflammatory reaction to the ligament wear particles was found to be significantly (p< 0.05) influenced by the type of material implanted. No particles were found in the regional lymph nodes or in the spleen, liver, kidney, or lung. © 1995 John Wiley & Sons, Inc.
Bond strength of metal–ceramic systems in three‐point flexure bond test
Authors: Lenz Jürgen , Schwarz Siegmund , Schwickerath Hans , Sperner Franz , Schäfer Astrid 
Published: May 2005

AbstractThis study deals with a three‐point flexure test for the metal‐ceramic bond involving geometrically simple specimens (alloy strips partly coated with ceramic) that can be fabricated with reasonable expenditure and sufficient reproducibility. The calculation of the stress distribution in such specimens with the aid of the finite‐element method (FEM) is presented. The aim of this numerical analysis is: to investigate the stress distribution in a ceramometallic specimen with dimensions that, in a large number of experiments, have proven to lead to debonding at one end of the ceramic veneer instead of a crack in the middle of the veneer; and to assign a bond strength to the measured critical bending force that takes into account the influence of the Young's modulus of the alloy as well as a possible deviation of the thickness of the metal substrate from the standard value. Bond strength values of a variety of metal‐ceramic combinations are demonstrated. These experimental results demonstrate the reproducibility of the test method as well as its sensitivity to diverse parameters. The presented method is proposed as an alternative to another flexure bond test nominated for international standard. In this test ceramometallic strips are bent over a rod to a 90° angle of the specimen ends, subsequently flattened, and the fracture surface visually inspected for adherence of the ceramic to the alloy substrate along the predominant part of the middle third of the specimen. It is clear that such a test can at most deliver qualitative results. © 1995 John Wiley & Sons, Inc.
Migration of polyethylene wear debris in hip arthroplasties: A canine model
Authors: Kraemer W. J. , Maistrelli G. L. , Fornasier V. , Binnington A. , Zhao J. F. 
Published: May 2005

AbstractThe distal migration of polyethylene wear debris appears to be a major cause of loosening and osteolysis of cementless total hip arthroplasties. The use of modern cementing techniques, circumferential porous or hydroxyapatite (HA) coating has been advocated as a means of preventing access of the particles to the bone‐implant interface. The purpose of this study was to compare the ability of different methods of implant fixation to prevent wear debris migration. Three each of smooth, porous‐coated, HA‐coated, and cemented hemiarthroplasties were implanted in the right hip of 12 dogs. Polyethylene particles were injected into the hip once a month for 4 months and then the femurs were sectioned. The percentage bone ingrowth was 8% for the smooth, 38% for the porous, and 83% for the HA‐coated sections. Infiltration of the interface membrane by histiocytes containing polyethylene particles, and endosteal scalloping or osteolysis were found on all sections of the smooth prostheses. No particles or osteolysis were found on any sections of the other three types of prostheses. Capsular and lymph node sections from all dogs revealed histiocytic infiltration with numerous polyethylene particles present. It is concluded that the use of cement, porous, or HA coating prevents or delays access of the polyethylene wear debris to the bone‐implant interface. No one of these methods of fixation proved more advantageous in the 5‐month limit of this study. © 1995 John Wiley & Sons, Inc.
Mechanical and histological fixation of hydroxylapatite‐coated pyrolytic carbon and titanium alloy implants: A report of short‐term results
Authors: Hetherington Vincent J. , Lord Christine E. , Brown Stanley A. 
Published: May 2005

AbstractHistorically, pyrolytic carbon has been a material for cardiovascular applications, but it has several properties suited for orthopedic uses as well. Pyrolytic carbon has an elastic modulus similar to bone and is highly fatigue resistant, but has not been used in orthopedics because of poor fixation to bone. Plasma sprayed hydroxylapatite (HA) has significantly improved the bonding of bone to titanium alloy implants. The effect of plasma‐sprayed HA on pyrolytic carbon implants was investigated in this study. Cylindrical samples were implanted through a single cortex in Beagle femurs. The animals were sacrificed after 8 weeks, and a mechanical push‐out test was performed on the implants immediately after explantation. Samples were microradiographed, stained for histology, and examined histomorphometrically. Interface strength for each type of implant was calculated. Pyrolytic carbon showed almost no attachment strength with an average strength value of 1.59 MPa. HA‐coated pyrolytic carbon (8.71 MPa) yielded the same interfacial strength as HA‐coated titanium (8.71 MPa). Histology revealed that bone was in direct apposition to all implants, both HA coated and noncoated. Failures occurred between the core material and the coating, or within the coating, but not at the bone/HA interface. Histomorphometry results confirmed that the two types of HA‐coated implants had more bone apposition than the uncoated pyrolytic carbon implants. It was concluded that a plasma sprayed HA coating significantly improves the bone fixation of pyrolytic carbon. © 1995 John Wiley & Sons, Inc.
Immobilization of heparin oligosaccharides onto radiofrequency plasma modified pyrolytic carbon‐coated graphite
Authors: Yuan Shengmei , Cai Weizhen , Szakalas‐Gratzl Gyongyi , Kottke‐Marchant Kandice , Tweden Katherine , Marchant Roger E. 
Published: May 2005

AbstractHeparin oligosaccharides with different anticoagulant activities were prepared and immobilized onto pyrolytic carbon coated graphite (PC) heart valve materials commonly used in mechanical heart valve prostheses. Prior to immobilization, PC surfaces were modified by radio‐frequency plasma polymerizedN‐vinyl‐2‐pyrrolidone (PPNVP) thin films (∼ 100 nm) and derivatized to provide surface hydroxyl groups. Cleaved, low affinity heparin (C‐heparin) with factor Xa inhibition activity of 107 to 130 IU/mg, was prepared by partial deaminative cleavage of commercial crude heparin, and high‐affinity heparin (HA‐heparin) with factor Xa inhibition activity of 550 to 1000 IU/mg was prepared by fractionation of C‐heparin using agarose‐ATIII affinity chromatography. C‐heparin and HA‐heparin were immobilized to surface modified PC by reductive amination. Anticoagulant activity of the heparin immobilized surfaces was determined by chromogenic assay for the inhibition of factor Xa. Highest surface anticoagulant activity was measured on C‐heparin immobilized surfaces (64.0 ± 7.3 mIU/cm2) compared with HA‐heparin immobilized surfaces (27.2 ± 12.2 mIU/cm2), suggesting higher binding of C‐heparin than HA‐heparin on the modified PC surfaces. Immobilized surfaces were evaluated under dynamic flow conditions, by subjecting samples to shear stress of up to 206 dyn/cm2in the presence of 5% albumin solution or human plasma. Anticoagulant activity of the immobilized heparin was retained, although reduced, and the modified surfaces showed evidence for protein resistance. © 1995 John Wiley & Sons, Inc.
Finite element analysis of crestal bone loss around porous‐coated dental implants
Authors: Vaillancourt H. , Pilliar R. M. , McCammond D. 
Published: May 2005

AbstractCrestal bone loss is observed around various designs of dental implants. A possible cause of this bone loss is related to the stresses acting on periimplant bone. To investigate the relationship between stress state and bone loss, two‐dimensional finite element models corresponding to bucco‐lingual and mesio‐distal sections of canine mandibles with one of two designs of porous‐coated dental implants were analyzed. A fully porous‐coated design consisting of a solid Ti6A14V core had a porous coating over the entire outer surface of the implant component, while a partially porous‐coated design had the porous coating over the apical two‐thirds of the implant surface only. Occlusal forces with axial and transverse components were assumed to act on the implant with interface bonding and effective force transfer at all porous coat‐bone interfaces and no bonding for the non‐porous‐coated regions. The results of the analysis indicated that at most implant aspects (buccal, lingual, mesial, and distal), the equivalent stresses in crestal bone adjacent to the coronal‐most, non‐porous‐coated zone of the partially porous‐coated implants were lower than around the most coronal region of the fully porous‐coated implants. The region of lower stresses around the partially porous‐coated implants corresponded to observed areas of crestal bone loss in animal studies, suggesting that crestal bone loss in this case was due to bone disuse atrophy. A number of parameters of the finite element models were varied to determine the effect on the resulting stress fields and, therefore, possible long‐term bone remodeling. Based on differences in observed bone structures by histological examination and results of finite element analyses with fully and partially porous‐coated implants, an equivalent stress equal to 1.6 MPa was determined to be sufficient to avoid bone loss due to disuse atrophy in the canine mandibular premolar region. © 1995 John Wiley & Sons, Inc.
Self‐dual codes and the (22,8,4) balanced incomplete block design
Authors: Bilous R. T. , van Rees G. H. J. 
Published: May 2005

AbstractAn Erratum has been published for this article in Journal of Combinatorial Designs 14: 83–83, 2006.We enumerate a list of 594 inequivalent binary (33,16) doubly‐even self‐orthogonal codes that have no all‐zero coordinates along with their automorphism groups. It is proven that if a (22,8,4) Balanced Incomplete Block Design were to exist then the 22 rows of its incident matrix will be contained in at least one of the 594 codes. Without using computers, we eliminate this possibility for 116 of these codes. © 2005 Wiley Periodicals, Inc. J Combin Designs.
Characteristics of a BHK cell variant defective in the cell‐substratum contact process
Authors: Shiba Yoshika , Grinnell Frederick 
Published: May 2005

AbstractIn this paper we document the phenotypic characteristics of a novel BHK cell adhesion variant designated FN‐2. Unlike parental cells, FN‐2 cells did not attach to fibronectin (pFN)‐coated dishes, even after 4‐hr incubations on dishes treated with 100 μg/ml of pFN. Mixing experiments with the variant and parental cells revealed that the parental cells attached normally in the presence of a ninefold excess of variant cells and the variant cells failed to attach in the presence of a ninefold excess of parental cells. Therefore, the defect in FN‐2 cells could not be explained by secretion of a factor inhibiting attachment or lack of secretion of a factor required for attachment. Also, the inability of FN‐2 cells to attach to pFN‐coated dishes could not be explained by an absence of cell pFN receptors since the variant cells bound normal numbers of small (ca. 0.8 μm) pFN‐coated latex beads, although they phagocytosed the beads poorly compared to parental cells. Also, the variant cells were not able to bind large (5.7 or 16.8 μm) pFN‐coated beads. When tested on dishes coated with ligands that, unlike fibronectin, have a high affinity for cell surface receptors, e.g., lectins and anti‐BHK antibodies, FN‐2 cells were observed to attach at a rate similar to that of parental cells but spread much more slowly. The phenotypic characteristics of FN‐2 cells suggest that they are deficient in what previously has been called the “cell contact” process in cell adhesion. It is proposed that the cell contact process is the initial formation by an individual cell of a sufficient number of cell‐substratum bonds to resist the shear forces operationally used to define “attachment,” and that more cell‐substratum bonds are necessary for cell attachment to large substrata (dishes or large beads) than for attachment to small substrata (small beads). The molecular defect in FN‐2 cells was studied by electroblotting analysis. A high molecular weight (ca. 370 kd) glycoprotein detected by blotting with anti‐BHK antibodies and ConA that was present in parental cell membranes was reduced or absent in the variant cells.
Inhibition of rat cervical epithelial cell growth by heparin and its reversal by EGF
Authors: Wright Thomas C. , Johnstone Theresa V. , Castellot John J. , Karnovsky Morris J. 
Published: May 2005

AbstractThe effects of heparin on the in vitro growth of rat cervical epithelial cells were examined. Heparin was found to inhbit in a dose dependent fashion the log‐phase growth of rat cervical epithelial cells (RCEC) grown in the absence of medium supplements. An inhibition of growth is observed at concentrations as low as 500 ng/ml and 50% inhibition of growth occurs at a concentration of 5 μ/ml. The growth inhibitory activity of heparin is independent of anticoagulant activity since three separate non‐anticoagulant preparations of heparin all inhibit growth. Other glycosaminoglycans including chondroitin 4‐sulfate, chondroitin 6‐sulfate, dermatan sulfate, hyaluronic acid, and keratin sulfate do not inhibit the growth of rat cervical epithelial cells. The ability of heparin to inhibit the log‐phase growth of rat cervical epithelial cells is dependent on the composition of the medium in which the cells are grown. The addition of ≥ 7.5 ng/ml epidermal growth factor to epithelial cultures blocks the growth inhibitory activity of heparin. These results suggest that components of the extracellular matrix modulate the growth responses of epithelial cells and may be important in regulating cellular proliferation in normal and pathological states.
Hormonal control of cholesterogenesis and related enzymes in isolated rat hepatocytes during pre‐ and postnatal development
Authors: Leoni S. , Spagnuolo S. , Devirgiliis L. Conti , Dini L. , Mangiantini M. T. , Trentalance A. 
Published: May 2005

AbstractThe effect of glucagon and insulin on the incorporation of 1‐14C‐acetate into cholesterol and fatty acids and on the enzymes involved in the first steps of cholesterol synthesis (3‐hydroxy‐3‐methyl‐glutaryl‐coenzyme A reductase, 3‐hydroxy‐3‐methyl‐glutaryl‐coenzyme A synthase, and acetoacetyl‐coenzyme A thiolase) was investigated. Isolated rat hepatocytes at different stages of fetal and postnatal development were employed. Data obtained show the appearance of hormonal control on the 18th day of fetal life, indicating the same pattern, as regards acetate incorporation and HMGCoA reductase prepared and assayed in the presence of NaF. On the contrary, HMGCoA reductase, prepared without NaF, HMGCoA synthase, and acetoacetyl CoA thiolase, does not appear to respond to hormonal stimulation. In the perinatal period, the hormonal effect is no longer detectable, probably because of a hormone resistance of this metabolic pathway.
Cell cycle traverse and protein metabolism in human NHIK 3025 cells: The role of anchorage
Authors: Rogne Sissel , Rønning Øystein W. , Myklebost Ola , Seglen Per O. , Pettersen Erik O. 
Published: May 2005

AbstractWe have studied the effect of cell anchorage on the human cell line NHIK 3025 in vitro, to see whether the growth regulating effect of cell anchorage primarily affected DNA division cycle or mass growth cycle. It was found that cell to cell anchorage had the same effect on cell cycle progression as anchorage to a solid surface, which indicates that it is anchorage per se and not cell shape that is important for growth control in NHIK 3025 cells. When NHIK 3025 cells were grown without attachment to a solid surface, both G1 and cell cycle duration was prolonged by 6 h, which means that the prolonged cell cycle was due to a prolonged G1. During the first part of the cell cycle the rate of protein synthesis and degradation was constant, and at the same level in cells grown with and without attachment. This means that the prolonged G1 was not due to a reduced protein accumulation or mass growth. Towards the end of the cell cycle protein accumulation was reduced. This effect was either due to a size control before cell division or a secondary effect of the prolonged G1. We therefore conclude that cell anchorage as a growth regulator primarily affects the DNA/cell division cycle.
Effects of EGF and thrombin on inositol‐containing phospholipids of cultured fibroblasts: Stimulation of phosphatidylinositol synthesis by thrombin but not EGF
Authors: Raben Daniel M. , Cunningham Dennis D. 
Published: May 2005

AbstractThe effects of growth factors on inositol‐containing phospholipids were investigated to test the hypothesis that alterations in their metabolism are involved in mitogenic stimulation. Thrombin and EGF stimulated comparable increases in the synthesis (30–50%) and degradation (20–40%) of phosphatidylinositol 4‐monophosphate (DPI) and phosphatidylinositol 4,5‐bisphosphate (TPI) in a cell line which is mitogenically responsive to both growth factors. The increases in synthesis were time and dose dependent in a manner which was consistent with their involvement in mitogenesis; the increases were observed only under conditions where a mitogenic response occurred. While it has been suggested that an increased synthesis of phosphatidylinositol (PI) is coupled to the stimulation of DPI and TPI synthesis, we found that thrombin stimulated an early synthesis PI but EGF did not. To further evaluate the involvement of PI in thrombin‐stimulated cell division we determined the time and dose dependence of the stimulated PI synthesis and found that it also occurred in a manner which was consistent with its involvement in thrombin‐stimulated cell division. Furthermore, the stimulated PI synthesis was not observed with nonmitogenic proteases or in cell lines which were not responsive to thrombin. These results demonstrate that the metabolism of DPI and TPI appears closely related to the mitogenic response generated by EGF and thrombin. However, an early stimulation of PI synthesis is not coupled to this metabolism and is not necessary for mitogenic stimulation by EGF. Thus, a stimulation of PI synthesis is not a valid measure of alterations in inositol‐containing phospholipids and what has been termed the “PI response.”
Separation of alkadiene‐1‐ol isomers by gas‐liquid chromatography
Authors: Schäfer W. 
Published: May 2005

AbstractComplete gas‐liquid chromatographic separation of the four 10, 12‐hexadecadiene‐l‐ol isomers using a FFAPcoated glass capillary column is described.These measurements are of importance for the analysis of pheromones from biological sources and for the control of material from stereospecific syntheses.
Operational variables of size exclusion columns with semirigid and rigid packings
Authors: Mukherji Anil K. 
Published: May 2005

AbstractSystematic studies on operation variables affecting GPC separations using the semirigid Microstyragel (Waters Associates) and the rigid silica packings (DuPont) of about equivalent porosity are reported. The dependence of (a) flow rate, (b) injection volume, and (c) concentration on elution volume and theoretical plates are examined.
Deactivation of glass capillary columns by silylation. Part 1: Principles and basic technique
Authors: Grob K. , Grob G. , Grob K. 
Published: May 2005

AbstractA deactivation procedure is described based on a published method using hexamethyldisilazane in the gas phase. In addition to unusually high inertia and thermostability, the method produces truly neutral columns which allow simultaneous analysis of moderately strong free acids and bases. The silylated columns show their full potential only with on‐column injection. Preliminary experimental directions are given; more elaborate directions will become available after extended optimization work.
Increased thermostability of non‐polar wall‐coated open tubular columns
Authors: Houtermans W. J. M. , Boodt C. P. 
Published: May 2005

AbstractA method of deactivating the inner surface of glass capillary columns is described, which can be used at 350°C without detoriation. A non‐polar liquid phase was prepared from a commercially available liquid phase which, when coated on a glass surface, can withstand temperatures of 325°C for isothermal analysis and 350°C for temperature‐programmed analysis.After deactivation, the column was coated using the static coating method. Then it was conditioned, tested and kept for 48 hours at 35O°C before being used for the analysis of a mixture of chlorinated pesticides.