bluuebunny/crossref_metadata_2025_split huggingface dataset:
On the fast search algorithms for vector quantization encoding
Authors: Chen Wen‐Shiung , Hsieh Lili , Yuan Shang‐Yuan 
Published: February 2003

AbstractOne of the major difficulties arising in vector quantization (VQ) is high encoding time complexity. Based on the well‐known partial distance search (PDS) method and a special order of codewords in VQ codebook, two simple and efficient methods are introduced in fast full search vector quantization to reduce encoding time complexity. The exploitation of the “move‐to‐front” method, which may get a smaller distortion as early as possible, combined with the PDS algorithm, is shown to improve the encoding efficiency of the PDS method. Because of the feature of energy compaction in DCT domain, search in DCT domain codebook may be further speeded up. The experimental results show that our fast algorithms may significantly reduce search time of VQ encoding. © 2003 Wiley Periodicals, Inc. Int J Imaging Syst Technol 12, 204–210, 2002; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/ima.10030
A nonlinear inverse problem inspired by three‐dimensional diffuse tomography: Explicit formulas
Authors: Grünbaum F. Alberto , Matusevich Laura Felicia 
Published: February 2003

AbstractWe use time of flight information to obtain explicit inversion formulas for a simple model of optical tomography. This can be considered as an instance of a more general nonlinear inversion problem for multi‐terminal networks. In this case the network is nonplanar with lots of cycles but the underlying physical model yields a highly structured situation. © 2003 Wiley Periodicals, Inc. Int J Imaging Syst Technol 12, 198–203, 2002; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/ima.10031
The role of the TH1 and TH2 immune responses in loosening and osteolysis of cemented total hip replacements
Authors: Arora Amarpal , Song Yong , Chun Linda , Huie Phil , Trindade Michael , Smith R. Lane , Goodman Stuart 
Published: February 2003

AbstractThe mechanisms underlying the development of osteolysis and aseptic loosening have an impact on the longevity of total hip replacements (THRs). This study examines the specific roles of lymphocytes in the TH1 and TH2 subsets in osteolysis and aseptic loosening of THR. Tissue from periprosthetic regions from patients with loose, cemented acetabular components were used to determine the TH1 and TH2 cytokine profile. Twelve tissue specimens from patients with radiographic signs of osteolysis, and nine tissue specimens from patients with no signs of osteolysis were harvested during revision surgery. Immunohistochemistry using primary antibodies against CD3, interferon (IFN)‐γ, interleukin (IL)‐2, IL‐4, and IL‐10 was performed on frozen sections to determine the percentage of positive cells for each of the sections. No statistically significant differences in the percentage of positive cells expressing cytokines characteristic of the TH1 pathway (IFN‐γ, IL‐2) or TH2 pathway (IL‐4, IL‐10) were found when comparing osteolytic and non‐osteolytic tissues. However, significant numbers of T cells (averaging about 10% of the total cells) and TH1 and TH2 immune cytokines (averaging 3–5% of cells) implicate a possible role for immune processes at the prosthetic interface. © 2003 Wiley Periodicals, Inc. J Biomed Mater Res 64A: 693–697, 2003
Transmission electron microscopic study on setting mechanism of tetracalcium phosphate/dicalcium phosphate anhydrous‐based calcium phosphate cement
Authors: Chen Wen‐Cheng , Lin Jiin‐Huey Chern , Ju Chien‐Ping 
Published: February 2003

AbstractThis work studied transmission electron microscopy on the setting mechanism of tetracalcium phosphate/dicalcium phosphate anhydrous (TTCP/DCPA)‐based calcium phosphate cement. The results suggest the process for early‐stage apatite formation as the follows: When TTCP and DCPA powders are mixed in the phosphate‐containing solution, the TTCP powder is quickly dissolved because of its higher solubility in the acidic solution. The dissolved calcium and phosphate ions, along with those ions readily in the solution, are then precipitated predominantly on the surface of DCPA particles. Few apatite crystals were observed on the surface of TTCP powder. During the later stages of reaction, the extensive growth of apatite crystals/whiskers, with a calcium/phosphorous ratio very close to that of hydroxyapatite, effectively linked DCPA particles together and also bridged the larger TTCP particles. It is suggested that, when the large TTCP particles are locked in place by the bridging apatite crystals/whiskers, the CPC is set and would not dissolve when immersed in Hanks' solution after 20–40 min of reaction. © 2003 Wiley Periodicals, Inc. J Biomed Mater Res 64A: 664–671, 2003
Ultra‐high molecular weight polyethylene oxidation reduces metalloproteinase 2 secretion in human osteoblast‐like cells in vitro: A mechanism of modulation of extracellular matrix
Authors: Bosetti M. , Renò F. , Bracco P. , Costa L. , Cannas M. 
Published: February 2003

AbstractUltra‐high molecular weight polyethylene (UHMWPE) sterilization with gamma rays induced high oxidation levels both on the surface and in the bulk that alter its structure and mechanical properties. The oxidation process of gamma‐radiated UHMWPE induces a reduction of molecular weight and, consequently, a less abrasive resistance that has been related, among others, to the failure of UHMWPE in vivo. To explain the role of cells in such events, human osteoblast‐like cells were seeded onto UHMWPE and oxidized UHMWPE discs. Cellular viability and morphology were evaluated along with matrix metalloproteinases (MMPs) production and activity. Oxidized UHMWPE did not induce any significant cytotoxic effects as observed by lactate dehydrogenase activity compared to the nonoxidized form; no changes in the cell morphology after 4 and 8 days proliferation were observed. In growth medium metalloproteinase 2 (gelatinase‐A, MMP‐2) was produced and released by osteoblast‐like cells. We observed that cells grown onto oxidized UHMWPE discs decreased the release and activity of MMP‐2 after 4 and 8 days culture compared to cells grown on control and non‐oxidized UHMWPE discs; metalloproteinase 9 (gelatinase‐B, MMP‐9) release was not significantly influenced. The absence of cytotoxic and morphological effects in the presence of a down‐regulation of MMP‐2 release and activity suggest that oxidized polyethylene surfaces may modulate matrix remodeling and, consequently, bone formation. © 2003 Wiley Periodicals, Inc. J Biomed Mater Res 64A: 698–705, 2003
Polymeric matrices based on graft copolymers of PCL onto acrylic backbones for releasing antitumoral drugs
Authors: Abraham Gustavo A. , Gallardo Alberto , San Román Julio , Fernández‐Mayoralas Alfonso , Zurita Mercedes , Vaquero Jesús 
Published: February 2003

AbstractGraft copolymers of poly(ϵ‐caprolactone) (PCL) on poly(dimethylacrylamide) (PDMAm), poly(methylmethacrylate) (PMMA), or on copolymers of poly(DMAm‐co‐MMA) have been synthesized and characterized by 1H NMR spectroscopy, differential scanning calorimetry (DSC), and size exclusion chromatography (SEC). These partially biodegradable copolymer matrices have been proposed as drug delivery systems for the release of low‐molecular‐weight glycosides. Octyl‐N‐acetyl‐6‐O‐[2,2‐bis(hydroxymethyl)‐3‐hydroxypropyl]‐α‐D‐glucosamide, a synthetic carbohydrate able to inhibit the proliferation of human malignant glioma cells in culture and transplanted glioma in rats was selected as drug model. The in vitro aqueous behavior of four drug‐loaded and unloaded graft copolymers of different MMA: DMAm and PCL ratios has been analyzed performing swelling, degradation, and drug release experiments. An intimate dependence of the aqueous behavior with the composition has been found. The higher was the DMAm content, the higher was the hydrophilicity of the synthesized systems as well as the swelling, degradation, and drug release rate. In vivo experiments in pigs demonstrated the very good tolerance of drug‐loaded implanted polymeric discs, and that >95% of the charged drug is released after 2 months' implantation. © 2003 Wiley Periodicals, Inc. J Biomed Mater Res 64A: 638–647, 2003
Behavior of MG‐63 cells on nylon/chitosan‐blended membranes
Authors: Wang Jyh‐Horng , Wei Cheng‐Wey , Liu Hwa‐Chang , Young Tai‐Horng 
Published: February 2003

AbstractIn this work, the properties of nylon, chitosan, and their blended membranes were investigated by scanning electron microscopy (SEM), differential scanning calorimetry (DSC), and wide‐angle X‐ray diffraction analysis. The SEM photographs show that the undulating surface of the nylon membrane became less obvious by blending with chitosan. The DSC and X‐ray diffraction analysis show that constitutionally different features in the combination of two polymer chains were revealed, suggesting that nylon and chitosan are immiscible at the microscopic level in the blended membranes. Furthermore, an attempt was made to understand whether the two components contribute independently to the adhesion, growth, and activation of MG‐63 osteoblastlike cells. The cell adhesion increased with increasing chitosan content, indicating that the affinity between the cells and the membranes increased with increasing chitosan content. Although the blended membranes with higher nylon content exerted an inhibitory effect on cell adhesion, cells cultured on the nylon membrane proliferated at higher rates and the nylon membrane was the least stimulating of MG‐63 cell cytokine production over a 4‐day period when compared with all the other membranes. Combined with the result of cell growth and cell activation, the chitosan content in the blended membrane did not proportionally influence the behavior of MG‐63 cells. It is proposed that cell's size was larger than the scale of nylon or chitosan domain in the blended membranes because of the incomplete miscibility between them. Therefore, even if the composition of the blended membranes is systematically changed, every cell covers a multiphase surface that is considered a totally new material for cells. Consequently, cell growth and cell activation on a blended membrane are not simply proportional to their composition. In contrast, cell adhesion is a simpler process, like a physical adsorption process, which is related to the bulk property of a blended membrane. © 2003 Wiley Periodicals, Inc. J Biomed Mater Res 64A: 606–615, 2003
Electrochemically assisted deposition of thin calcium phosphate coatings at near‐physiological pH and temperature
Authors: Rößler S. , Sewing A. , Stölzel M. , Born R. , Scharnweber D. , Dard M. , Worch H. 
Published: February 2003

AbstractAn electrochemical method for the deposition of calcium phosphate phases on titanium surfaces using the galvanostatic mode is presented. Deposition was performed in a (Ca2+/HxPO4(3−x)−)‐containing electrolyte near physiological conditions with regard to pH (6.4) and temperature (36°C). Cathodic alkalization leads first to the formation of a thin homogeneous layer that shows a nanoscale surface topography of alternating wall‐like elevations and channels. It is thought that these channels in the calcium phosphate prelayer are formed as pathways for hydroxyl ions and hydrogen. Upon this layer, spheres of amorphous calcium phosphate (ACP) are formed as indicated by Fourier transform infrared spectroscopy (FTIR) and transmission electron microscopy. According to transmission electron microscopy images, these spheres consist of small clusters of calcium phosphate (∼30 nm) and can grow up to 300 nm in diameter. Characteristic for this ACP is a high water content as seen by FTIR. As a function of current density, the ACP is then transformed into crystalline hydroxyapatite (HAP), which was identified using FTIR and X‐ray diffraction. The morphology of the HAP crystals can be described as needles with dimensions of <500‐nm length and <60‐nm width. By choice of different electrochemical parameters, a homogeneous coating of either ACP, HAP, or the intermediate phase can be achieved, as shown in a kinetic phase diagram, thus allowing the formation of coatings with different properties in solubility and morphology. © 2003 Wiley Periodicals, Inc. J Biomed Mater Res 64A: 655–663, 2002
Inhibition of CEM calcification by the sequential pretreatment with ethanol and EDTA
Authors: Singla Anuj , Lee Chi H. 
Published: February 2003

AbstractThe major object of the present study is to optimize the anticalcification activity of ethanol on bioprosthetic heart valve (BHV) calcification. We hypothesize that the chelating agent, in combination with ethanol, will synergistically prevent aortic wall calcification. Collagen‐elastin matrix (CEM) was developed as a calcifiable matrix for simulating the calcification process of implantable biomaterials. The efficacy of the combination effects of ethanol and EDTA on the calcification process of CEMs was investigated by implanting them after pretreatment with various conditions of ethanol and EDTA in the rat subdermal model. The relationship between calcium concentrations and pretreatment conditions (a series vs. simultaneous, i.e., first ethanol and then EDTA in water solution, the reverse, or EDTA in ethanol) was established and the optimal condition for prevention of BHV calcification was determined. The mechanistic studies on anticalcification effects exerted by particular pretreatment sequences were also conducted using FTIR and differential scanning calorimetry (DSC). The sequential pretreatment of CEM first with ethanol and then EDTA in water solution significantly decreased the calcification rate of CEM compared the control. The percentage of prevention of calcification by the serial treatment of ethanol (80 % v/v) and then EDTA in water solutions decreased, as the concentration of elastin in the CEM increased. The percentage of preventing calcification was 42%, 28.6%, and 22.9% for CEM containing collagen and elastin ratios of 90:10, 50:50, 20:80, respectively. These results indicate that elastin is the major regulatory component of BHV calcification, and preventive effects on calcification increased only when CEM were pretreated with first ethanol and then EDTA in water solution. Moreover, the sequential effect is more apparent in the matrix of less elastin content, which is close to the physiological range. The sequential inhibitory effects of ethanol and EDTA could occur due to the distinct separate actions of each agent, thereby achieving a relatively greater inhibition of calcification. © 2003 Wiley Periodicals, Inc. J Biomed Mater Res 64A: 706–713, 2003
Fibronectin fibrillogenesis on sulfonated polystyrene surfaces
Authors: Pernodet Nadine , Rafailovich Miriam , Sokolov Jonathan , Xu D. , Yang Nan‐Loh , McLeod Kenneth 
Published: February 2003

AbstractExtracellular matrix (ECM) protein adsorption and organization serves as a critical first step in the development and organization of tissues. Advances in tissue engineering, therefore, will depend on the ability to control the rate and pattern of ECM formation. Fibronectin is a prominent component of the ECM, which undergoes fibrillogenesis in the presence of cells. Using sulfonated polysyrene surfaces, we showed that fibronectin undergoes a transition from monolayer to multilayer adsorption at calculated surface charge densities above 0.03 Coulombs (C)/m2. At charge densities above approximately 0.08 C/m2, distinct fibronectin fibrillar networks are observed to form with a fibril morphology similar to those observed to form in situ on cell surfaces. This self‐organization process is time dependent, with the fibrils achieving dimensions of 30–40 μm in length and 1 μm in height after 72 h of incubation. We suggest that the polarization of charge domains on the polyampholytic fibronectin molecules near high charge density surfaces is sufficient to initiate the multilayer adsorption and the organization of these fibrillar structures. These results suggest that the nonlinear dependence of adsorption on surface charge density may play an important role in the self‐organization of many matrix components. © 2003 Wiley Periodicals, Inc. J Biomed Mater Res 64A: 684–692, 2003
Textured hydroxyapatite interface onto biomedical titanium‐based coatings
Authors: Manso Miguel , Herrero P. , Fernández M. , Langlet M. , Martínez‐Duart J. M. 
Published: February 2003

AbstractHydroxyapatite (HAP) bioceramic coatings grown onto titanium‐nitride (TiN) buffer layers by the aerosol‐gel procedure present interfaces with a preferred growth orientation. These coatings were crystallized at 800°C and subsequently etched to ease the study of the interface by Auger electron spectroscopy depth profiling. Ion beam milling was applied to cross‐section samples to analyze the interface structures using transmission electron microscopy. At the interface, the HAP crystals showed a 〈002〉 orientation. It was shown by Auger electron spectroscopy depth profiling that O atoms diffuse into the nitride interlayer, indicating that the formation of O channels in the HAP structure is the driving force inducing the textured film. The outstanding biocompatible properties of both the materials and properties of their interface suggest that HAP/TiN structures are particularly well suited for endoprosthetic applications. © 2003 Wiley Periodicals, Inc. J Biomed Mater Res 64A: 600–605, 2003
Fibroblast growth on surface‐modified dental implants: An in vitro study
Authors: Groessner‐Schreiber Birte , Neubert Anja , Müller Wolf‐Dieter , Hopp Michael , Griepentrog Michael , Lange Klaus‐Peter 
Published: February 2003

AbstractA major consideration in designing dental implants is the creation of a surface that provides strong attachment between the implant and bone, connective tissue, or epithelium. In addition, it is important to inhibit the adherence of oral bacteria on titanium surfaces exposed to the oral cavity to maintain plaque‐free implants. Previous in vitro studies have shown that titanium implant surfaces coated with titanium nitride (TiN) reduced bacterial colonization compared to other clinically used implant surfaces. The aim of the present study was to examine the support of fibroblast growth by a TiN surface that has antimicrobial characteristics. Mouse fibroblasts were cultured on smooth titanium discs that were either magnetron‐sputtered with a thin layer of titanium nitride, thermal oxidized, or modified with laser radiation (using a Nd‐YAG laser). The resulting surface topography was examined by scanning electron microscopy (SEM), and surface roughness was estimated using a two‐dimensional contact stylus profilometer. A protein assay (BCA assay) and a colorimetric assay to examine fibroblast metabolism (MTT) were used. Cellular morphology and cell spreading were analyzed using SEM and fluorescence microscopy. Fibroblasts on oxidized titanium surfaces showed a more spherical shape, whereas cells on laser‐treated titanium and on TiN appeared intimately adherent to the surface. The MTT activity and total protein were significantly increased in fibroblasts cultured on titanium surfaces coated with TiN compared to all other surface modifications tested. This study suggests that a titanium nitride coating might be suitable to support tissue growth on implant surfaces. © 2003 Wiley Periodicals, Inc. J Biomed Mater Res 64A: 591–599, 2003
Reevaluation of ethylene oxide hemolysis and irritation potential
Authors: Anand V. P. , Cogdill C. P. , Klausner K. A. , Lister L. , Barbolt T. , Page B. F. J. , Urbanski P. , Woss Casimir J. , Boyce John 
Published: February 2003

AbstractThe in vitro hemolytic and in vivo mucosal irritation potential of ethylene oxide (EO) was investigated with standard procedures used to determine the biocompatibility of medical devices. Test solutions containing EO at concentrations of 25, 50, 100, 250, 500, 1,250, 2,500, 5,000, or 10,000 μg/mL were prepared in saline to simulate a worst‐case aqueous extraction of standard medical devices containing 125, 250, 500, 1,250, 2,500, 6,250, 12,500, 25,000, or 50,000 μg/g of EO, respectively. Concentrations of EO up to 500 μg/mL were not hemolytic (<5% hemolysis after a 4‐h exposure), whereas ≥1250 μg/mL of EO resulted in significant hemolysis. Hamster cheek pouches exposed to cotton pellets saturated with EO at concentrations of up to 2500 μg/mL for 4 h with a recovery period of 14 days were without effects attributable to EO. However, at ≥5000 μg/mL of EO, significant histomorphological alterations of the buccal mucosa were observed and attributed to EO exposure. It was concluded that solutions of EO of up to 500 μg/mL representing an aqueous extract of a general medical device containing at least 2500 μg/g of EO residue do not result in significant hemolysis and irritation. © 2003 Wiley Periodicals, Inc. J Biomed Mater Res 64A: 648–654, 2003
Juniper wood as a possible implant material
Authors: Gross K. A. , Ezerietis E. 
Published: February 2003

AbstractNatural materials, such as wood and bone, possess structures fulfilling the requirements of support and transport of nutrients. Similarity in function and properties provides inspiration for investigating the possible use of wood as an implant material. Juniperus communis wood is dense, durable, and strong and has naturally impregnated essential oils that display antiseptic properties. This study investigated the toxicity of the oil, the effect of sterilization on the mechanical properties of the wood, and bone attachment with animal studies. The possible toxicity of the oil was determined orally and by intravenous injection. At low concentrations, the dose that would be released by the wood in the body could be tolerated without any detrimental effects. Sterilization of the wood in boiling water lowered the elastic modulus and modulus of rupture to a level at which the elastic modulus could be better matched to bone. Wood shaped into the form of femoral implants were implanted into rabbits and displayed good acceptance by the body up to a period of 3 years, indicating bone apposition, abutment into pores, and growth into drilled cavities. © 2003 Wiley Periodicals, Inc. J Biomed Mater Res 64A: 672–683, 2003
The effect of sintered dicalcium pyrophosphate on osteoclast metabolism: An ultrastructural study
Authors: Sun Jui‐Sheng , Huang Yi‐Chau , Lin Feng‐Huei , Chen Li‐Ting 
Published: February 2003

AbstractSintered dicalcium pyrophosphate (SDCP), a synthetic compound, has proved to be both bioabsorbable and biocompatible in vivo. Recent work in our institute also has demonstrated that the ingestion of SDCP can increase bone mass in the ovariectomized rat. In this study, we used an in vitro cell culture model to investigate the ultrastructural changes and fate of osteoclasts induced by SDCP. Quantitative evaluation of osteoblasts and osteoclasts after administration of SDCP was performed. We studied immunohistochemical and ultrastructural features of osteoclasts undergoing apoptosis. The results showed that at 10−4 M SDCP, the osteoblast cell count increased significantly, whereas the osteoclast population decreased significantly. Apoptosis of the osteoclast population was well demonstrated by immunohistochemical study. Ultrastructural study showed that the Golgi apparatus was degraded or dispersed in the cytoplasm. Later, osteoclasts revealed pyknotic nuclei showing condensation and margination of heterochromatins and DNA fragmentation, which are typical features of apoptosis. In addition, disruption of nuclear envelopes leading to leakage of nuclear contents into the cytoplasm was observed in the late stage of apoptosis. In conclusion, SDCP‐induced apoptosis of osteoclasts was characterized by ultrastructural changes of the nucleus accompanied by degradation of cellular organelles. © 2003 Wiley Periodicals, Inc. J Biomed Mater Res 64A: 616–621, 2003