bluuebunny/crossref_metadata_2025_split huggingface dataset:
Simple surface modification of poly(ϵ‐caprolactone) to induce its apatite‐forming ability
Authors: Oyane Ayako , Uchida Masaki , Yokoyama Yoshiro , Choong Cleo , Triffitt James , Ito Atsuo 
Published: July 2005

AbstractA biodegradable polymer coated with a bone‐like apatite layer on its surface is useful as a scaffold for bone tissue regeneration. In this work, a poly(ϵ‐caprolactone) (PCL) surface was modified by an O2 plasma surface treatment to form oxygen‐containing functional groups. The plasma‐treated samples were subsequently dipped alternately in an alcoholic solution containing calcium ions and one containing phosphate ions to deposit apatite precursors on the surface. The surface‐modified PCL samples formed a dense and uniform surface bone‐like apatite layer after immersion for 24 h in a simulated body fluid with ion concentrations approximately equal to those of human blood plasma. This surface‐modification process is applicable to two‐dimensional PCL plates and three‐dimensional PCL meshes. In the resulting apatite–PCL composite, the apatite layer strongly adhered to the PCL surface and remained intact after a tape‐detachment test. Therefore, this type of composite material will be a useful scaffold for bone tissue engineering. © 2005 Wiley Periodicals, Inc. J Biomed Mater Res, 2005
In vitro release of clomipramine HCl and buprenorphine HCl from poly adipic anhydride (PAA) and poly trimethylene carbonate (PTMC) blends
Authors: Dinarvand Rassoul , Alimorad Mohammed Massoud , Amanlou Massoud , Akbari Hamid 
Published: July 2005

AbstractControlled drug‐delivery technology is concerned with the systematic release of a pharmaceutical agent to maintain a therapeutic level of the drug in the body for modulated and/or prolonged periods of time. This may be achieved by incorporating the therapeutic agent into a degradable polymer vehicle, which releases the agent continuously as the matrix erodes. In this study, poly trimethylene carbonate (PTMC), an aliphatic polycarbonate, and poly adipic anhydride (PAA), an aliphatic polyanhydride, were synthesized via melt condensation and ring‐opening polymerization of trimethylene carbonate and adipic acid, respectively. The release of clomipramine HCl and buprenorphine HCl from discs prepared with the use of PTMC‐PAA blends in phosphate buffer (pH 7.4) are also described. Clomipramine HCl and buprenorphine HCl were both used as hydrophilic drug models. Theoretical treatment of the data with the Peppas model revealed that release of clomipramine HCl (5%) in devices containing 70% PTMC or more followed a Fickian diffusion model. However, the releases of buprenorphine HCl (5%) in the same devices were anomalous. For devices containing 50% and more PAA, surface erosion may play a significant role in the release of both molecules. © 2005 Wiley Periodicals, Inc. J Biomed Mater Res, 2005
Preparation and characterization of nano‐hydroxyapatite/chitosan composite scaffolds
Authors: Kong Lijun , Gao Yuan , Cao Wenling , Gong Yandao , Zhao Nanming , Zhang Xiufang 
Published: July 2005

AbstractA novel nano‐hydroxyapatite (HA)/chitosan composite scaffold with high porosity was developed. The nano‐HA particles were made in situ through a chemical method and dispersed well on the porous scaffold. They bound to the chitosan scaffolds very well. This method prevents the migration of nano‐HA particles into surrounding tissues to a certain extent. The morphologies, components, and biocompatibility of the composite scaffolds were investigated. Scanning electron microscopy, porosity measurement, thermogravimetric analysis, X‐ray diffraction, X‐ray photoelectron spectroscopy, and Fourier transformed infrared spectroscopy were used to analyze the physical and chemical properties of the composite scaffolds. The biocompatibility was assessed by examining the proliferation and morphology of MC 3T3‐E1 cells seeded on the scaffolds. The composite scaffolds showed better biocompatibility than pure chitosan scaffolds. The results suggest that the newly developed nano‐HA/chitosan composite scaffolds may serve as a good three‐dimensional substrate for cell attachment and migration in bone tissue engineering. © 2005 Wiley Periodicals, Inc. J Biomed Mater Res, 2005
Improved performance of primary rat hepatocytes on blended natural polymers
Authors: Li Keguo , Qu Xinjian , Wang Yun , Tang Yuefeng , Qin Dajiang , Wang Yanjun , Feng Meifu 
Published: July 2005

AbstractAlginate (Alg), chitosan (Chi), collagen (Col), gelatin (Gel), and the mixtures of every two of them were screened to determine their suitability for hepatocyte culture. The test materials were fabricated as films and then evaluated on the basis of their abilities to promote the attachment and functions of rat hepatocytes cultured on them. Cellular attachment on Col and Gel was favorable. However, cellular viability, cytoskeleton organization and function, as evaluated by albumin production, ureagenesis, and enzyme activity of cytochrome P450 as well as expression levels of hepatocyte nuclear factor 4α deteriorated. Reverse cellular behavior was observed on Alg and Chi. Two blends, composed of Chi and Col or Gel, were found to be superior to other materials and sustained viability and differentiated functions of hepatocyte. © 2005 Wiley Periodicals, Inc. J Biomed Mater Res, 2005
The influence of ultrasound on the release of gentamicin from antibiotic‐loaded acrylic beads and bone cements
Authors: Ensing Geert T. , Hendriks Johannes G.E. , Jongsma Jelmer E. , van Horn Jim R. , van der Mei Henny C. , Busscher Henk J. 
Published: July 2005

AbstractGentamicin‐loaded acrylic beads are loosely placed in infected bone cavities, whereas gentamicin‐loaded acrylic bone cement is used as a mechanical filler in bone to anchor prosthetic components. Both drug delivery systems are used to decrease infection rates by gentamicin release. The objective of this study is to investigate the effects of pulsed ultrasound on gentamicin release from both materials. Gentamicin release from gentamicin‐loaded beads (Septopal) and from three commercially‐available brands of gentamicin‐loaded bone cement (CMW 1, Palacos R‐G, and Palamed G) was measured after 18 h of exposure in PBS to an ultrasonic field of 46.5 kHz in a 1:3 duty cycle with an average acoustic intensity of 167 mW/cm2. Samples not exposed to ultrasound were used as controls. Pulsed ultrasound significantly enhanced gentamicin release from gentamicin‐loaded beads, whereas gentamicin release from the gentamicin‐loaded bone cements was not significantly enhanced. Mercury intrusion porosimetry revealed an increased distribution of pores between 0.1 and 0.01 μm in beads after gentamicin release, while in bone cements no increase in the number of pores was found. Increased gentamicin release in beads due to ultrasound may be explained by microstreaming in a porous structure, whereas the absence of changes in pore structure after gentamicin release in bone cement is concurrent with the lack of an enhanced release of the antibiotic by ultrasound. As an effective treatment of infections requires high local concentrations of antibiotic, increased gentamicin release due to ultrasound may be of clinical significance, especially since ultrasound has been demonstrated to increase bacterial killing by antibiotics. © 2005 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater, 2005
Electron paramagnetic resonance analyses of surface radical chemistries of γ‐sterilized orthopedic materials: Implications pointing to cytotoxicity via wear debris–induced inflammation
Authors: DiCicco Michael , Compton Ryan , Duong Thanh , Jansen‐Varnum Susan A. 
Published: July 2005

AbstractIn this research, electron paramagnetic resonance (EPR) spin‐trapping was utilized to determine if surface radical chemistries occur for gamma (γ)‐sterilized orthopedic materials—ultra‐high molecular weight polyethylene (UHMWPE) and the novel, hybrid, diurethane dimethacrylate (DUDMA)‐based RHAKOSS™. The materials' ability to competitively chelate catalytic ferrous ions (Fe2+) or readily reduce ferric ions (Fe3+), and hydrogen peroxide (H2O2) directly, in facilitating the Fenton reaction (FR), is indicative of cytotoxicity. Validations with a radical scavenger aids to confirm a radical mechanism. In conjunction, materials were thermally annealed and characterized by attenuated total reflectance–Fourier‐transform infrared (ATR‐FTIR) spectroscopy in order to explore accelerated oxidative degradation induced by residual radicals evolving from γ‐sterilization. Particularly, there was a significant decrease in spin‐adduct peak areas obtained from the reduction of H2O2 in the presence of RHAKOSS or UHMWPE, evaluated against their respective controls. Additionally, chelated Fe2+ accelerated the rate of FR. This phenomenon suggests that the materials are not better chelators than the Fe‐activating chelator, edta. Neither material had the propensity to readily reduce Fe3+ to the relevant Fe2+, as certified by a nonradical mechanism. Alternatively, the false spin‐adduct signal acquired when chelated Fe3+ is employed arises via the nucleophilic addition of water onto the DMPO spin trap. Residual radicals in UHMWPE did not recombine/terminate following thermal annealing in an inert atmosphere. The radicals in RHAKOSS, however, did recombine under mild heating in an oxidizing or inert atmosphere. Both materials displayed quenching of ˙OH; however, for UHMWPE, this mechanism was jointly accountable for its accelerated degradation, evidenced by ATR‐FTIR. Quenching of ˙OH by the silica found in RHAKOSS manifested in a competing effect that counterbalanced the observed FR. Implanted RHAKOSS is not likely to promote cytotoxicity and should not degrade, but the damaging effect of γ sterilization on UHMWPE is a serious dilemma confronting its long‐term durability and biocompatibility. © 2005 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater, 2005
Biomimetic porous scaffolds with high elasticity made from mineralized collagen—An animal study
Authors: Yokoyama Atsuro , Gelinsky Michael , Kawasaki Takao , Kohgo Takao , König Ulla , Pompe Wolfgang , Watari Fumio 
Published: July 2005

AbstractHistological investigations of a new hydroxyapatite–collagen composite material were carried out to evaluate its possible suitability as a bone substitute. The three‐dimensional scaffolds made from biomimetically mineralized collagen exhibit an interconnecting pore structure and elastic mechanical properties. They were implanted into the subcutaneous tissue and bone defects made in the femur of rats and harvested with the surrounding tissue at 1, 2, 4, 8, and 12 weeks after surgery. The materials implanted in the subcutaneous tissue were covered by fibrous connective tissue with a slight inflammatory response, and many foreign‐body giant cells were observed on the surface of the scaffolds. Most of the material implanted in the subcutaneous tissue was resorbed at 8 weeks by phagocytosis. In the bone defects, new bone formation was observed on the surface of the material at 1 week. New bone increased with time, and osteoclasts were seen on the surface of the scaffolds at 2 weeks. Resorption and replacement by new bone of many parts of the materials implanted in the femur were observed by 12 weeks. These responses occurred faster than those of other hydroxyapatite‐collagen composites. The results suggested that the new biomimetically mineralized collagen scaffolds were suitable as an implant material for bone‐tissue reconstruction. © 2005 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater, 2005
Collagen‐immobilized poly (vinyl alcohol) as an artificial cornea scaffold that supports a stratified corneal epithelium
Authors: Miyashita Hideyuki , Shimmura Shigeto , Kobayashi Hisatoshi , Taguchi Tetsushi , Asano‐Kato Naoko , Uchino Yuichi , Kato Masabumi , Shimazaki Jun , Tanaka Junzo , Tsubota Kazuo 
Published: July 2005

AbstractThe cornea is a transparent tissue of the eye, which is responsible for the refraction of incoming light. Both biological corneal equivalents and synthetic keratoprostheses have been developed to replace donor tissue as a means to restore vision. However, both designs have drawbacks in terms of stability and biocompatibility. Clinically available synthetic devices do not support an intact epithelium, which poses a risk of microbial infection or protrusion of the prosthesis. In the present study, type I collagen was immobilized onto poly(vinyl alcohol) (PVA‐COL) as a possible artificial cornea scaffold that can sustain a functional corneal epithelium. Human and rabbit corneal epithelial cells were air‐lift cultured with 3T3 feeder fibroblasts to form a stratified epithelial layer on PVA‐COL. The epithelial sheet expressed keratin 3/12 differentiation markers, the tight junction protein occludin, and had characteristic microvilli structures on transmission electron microscopy. Functionally, the stratified epithelium contained normal glycogen levels, and an apical tight‐junction network was observed to exclude the diffusion of horseradish peroxidase. Furthermore, the epithelium‐PVA‐COL composite was suturable in the rabbit cornea, suggesting the possibility of using PVA‐COL as a biocompatible material for keratoprosthesis. © 2005 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater, 2006
Structural features and mechanical properties of in situ–bonded meshes of segmented polyurethane electrospun from mixed solvents
Authors: Kidoaki Satoru , Kwon Il Keun , Matsuda Takehisa 
Published: July 2005

AbstractThe relationships between the structural features and mechanical properties of electrospun segmented polyurethane (SPU) meshes and electrospinning parameters such as formulation (e.g., polymer concentration and solvent mixing ratio) and operation parameters (e.g., applied voltage, air gap, and flow rate) were studied with the use of a mixed‐solvent system of tetrahydrofuran (THF) and N,N‐dimethylacrylamide (DMF). After the relationships between the structure of electrospun SPU and the operation parameters under a fixed SPU concentration of single THF solution were established, SPU was electrospun from the mixed solvent of THF and DMF with different mixing ratios [DMF content: 5, 10, and 30% (v/v)]. Scanning electron microscopy showed that an increase in DMF ratio significantly enhances the degree of bonding between SPU fibers at contact sites and decreases the diameter of fibers formed. The porosimetric characterization showed the following: (1) The porosity of the electrospun SPU meshes decreased with an increase of DMF ratio. (2) The pore size distribution exhibited three representative peaks of different void sizes (i.e., approximately 5, 20, and 70 μm). (3) The proportion of the 20‐μm void markedly decreased with an increase in DMF ratio. A tensile test on the meshes showed that an increase in DMF ratio induces an increase in elasticity of the mesh. Such a regulation of the structural features and mechanical properties of electrospun SPU meshes using a mixed‐solvent system with low‐ and high‐boiling‐point solvents may be useful in the engineering of SPU‐fiber based matrices or scaffolds. © 2005 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater, 2006
Biomechanical investigation of the effect of high hydrostatic pressure treatment on the mechanical properties of human bone
Authors: Steinhauser Erwin , Diehl Peter , Hadaller Martin , Schauwecker Johannes , Busch Raymonde , Gradinger Reiner , Mittelmeier Wolfram 
Published: July 2005

AbstractSeveral methods are available for reconstruction of bone defects due to malignant tumors. To extracorporally devitalize resected tumor‐bearing bone segments two methods, that is, extracorporal irradiation or autoclaving, are available up to now. However, both methods have substantial disadvantages like decrease of bone's mechanical strength. To develop an alternative method for tumor inactivation in skeletal segments, high hydrostatic pressure (HHP) was applied. Previous investigations have shown that human normal and tumor cell lines as well as tumor‐afflicted human bone specimens were irreversibly damaged at 350 MPa when subjected to HHP. This study was aimed to examine the alterations of biomechanical properties of human bone after exposure to HHP. Trabecular and cortical bone specimens were harvested from six pair of fresh‐frozen human cadaveric femora. The bone specimens from one side were exposed to different pressure values of 300 or 600 MPa over 10 min. Bone samples from the contralateral sites were used as untreated controls. Biomechanical properties were investigated by a quasi‐static compression test for trabecular specimens and by a quasi‐static four‐point bending test for cortical specimens, respectively. Biomechanical properties of the cortical and trabecular bone did not decrease after exposure to 300 MPa regarding the testing parameters Young's modulus and ultimate strength (200.7 ± 38.7 MPa for HHP treated cortical bone versus 186.5 ± 34.3 MPa for the untreated control group). After pressure treatment at 600 MPa Young's modulus and ultimate strength respectively remained almost unchanged in trabecular bone and were reduced about 15% in cortical bone (p < 0.001 and p =0.002, respectively). We anticipate that in orthopedic surgery HHP can serve as a novel, promising methodical approach for tumor cell inactivation, which occurs at pressure levels of about 300 MPa. Thereby immediate reimplantation of treated bone segments by preservation of the essential biomechanical properties of bone could become possible. Even after HHP treatment at 600 MPa the strength of bone only decreases up to 15%. © 2005 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater, 2006
Joint properties of cast Fe‐Pt magnetic alloy laser welded to gold alloys
Authors: Watanabe Ikuya , Nguyen Khoi , Benson P. Andrew , Tanaka Yasuhiro 
Published: July 2005

AbstractThis study investigated the joint properties of a cast Fe‐Pt magnetic alloy (Fe‐36 at % Pt) laser welded to three gold alloys. The gold alloys used were ADA Type II and Type IV gold alloys, and an Ag‐based (Ag‐Au) gold alloy. Cast plates (0.5 × 3.0 × 10 mm) were prepared for each alloy. After the cast Fe‐Pt plates were heat treated, they were butted against each of the three alloys and then laser welded with Nd:YAG laser at 200 V. Homogeneously welded specimens were also prepared for each alloy. Tensile testing was conducted at a crosshead speed of 1 mm/min. Failure load (N) and elongation (%) were recorded. After tensile testing, the fractured surfaces were examined with the use of SEM. The failure‐load values of the group of alloys welded homogeneously were ranked in the order of: Ag‐Au alloy > Type IV alloy > Type II alloy > Fe‐Pt alloy. The Type IV alloy welded to Fe‐Pt alloy had the highest failure‐load value among the three alloys tested. The elongation results tended to follow a similar pattern. The results of this study indicated that Type IV gold alloy is a suitable alloy for metal frameworks to which cast Fe‐Pt magnetic alloy is laser welded. © 2005 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater, 2006
Removal of surface by‐products from sintered hydroxyapatite: Effect of a chelation treatment on fibronectin adsorption and cell adhesion
Authors: Pellenc Delphine , Giraudier Sébastien , Champion Eric , Anselme Karine , Larreta‐Garde Véronique , Gallet Olivier 
Published: July 2005

AbstractIt was observed that fibronectin precipitates when deposited on hydroxyapatite (HA) ceramics. Fibronectin's known affinity for calcium and the composition of the ceramic itself suggested that calcium release could be the main cause of this aggregation effect. It was then decided to investigate the effect of a surface chelation treatment on fibronectin adsorption, and MG63 cell adhesion, onto porous ceramics of hydroxyapatite (HA), beta‐tricalcium phosphate (β‐TCP), and HA/TCP biphasic material (BCP). Those ceramics were immersed in an EDTA solution and the effect of this treatment on the material composition was assayed. X‐ray diffraction data showed the presence of α‐ and β‐TCP phases in HA and BCP materials, which were both completely removed by the chelation treatment in the case of HA. On BCP, α‐TCP was removed and β‐TCP partially dissolved. The TCP material, which was pure β‐TCP, underwent a mass loss, but no change in composition was observed. Adhesion of MG63 cells was overall higher on the fibronectin‐coated EDTA‐treated HA material, but was especially enhanced on EDTA‐treated HA. Changes in surface morphologies, as compared with the use of scanning electron microscopy, did not seem to be related to the effects observed. The EDTA treatment proved to be a very efficient way of removing by‐products of HA sintered materials, and thus enhancing the biocompatibility of the material. © 2005 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater, 2006
Dual‐level direct dynamics studies on the reaction Cl + CHBr2Cl
Authors: Zhang Hui , Wu Jia‐Yan , Li Ze‐Sheng , Liu Jing‐Yao , Sheng Li , Sun Chia‐Chung 
Published: July 2005

AbstractTheoretical investigations are carried out on the multichannel reaction CHBr2Cl + Cl by means of direct dynamics methods. The minimum energy path (MEP) is obtained at the BH&H‐LYP/6‐311G(d,p) level, and energetic information is further refined at the CCSD(T)/6‐311+G(2df,2p) (single‐point) level. The rate constants for three reaction channels, H‐abstraction, Br‐abstraction, and Cl‐abstraction, are calculated by using the improved canonical variational transition state theory (ICVT) incorporating with the small‐curvature tunneling (SCT) correction. The theoretical overall rate constants are in good agreement with the available experimental data and are found to be k = 2.58 × 10−15 T1.18 exp(−861.17/T) cm3molecule−1s−1 over the temperature range 200–2400 K. For the title reaction, H‐abstraction reaction channel is the major channel at the lower temperatures, while as the temperature increases, the contribution of Br‐abstraction reaction channel should be taken into account. At 2180 K, the rate constants of these two pathways are equal. Cl‐abstraction reaction channel is minor channel over the whole temperature region. © 2005 Wiley Periodicals, Inc. J Comput Chem 26: 1421–1426, 2005
Radiosyntheses and reactivities of novel [18F]2‐fluoroethyl arylsulfonates
Authors: Musachio John L. , Shah Jay , Pike Victor W. 
Published: July 2005

Abstract[18F]2‐Fluoroethyl tosylate ([18F]FEOX, X=Ts) is widely used for labeling radiotracers for positron emission tomography (PET). Little work has been reported on syntheses of other [18F]2‐fluoroethyl arylsulfonates ([18F]FEOX) that bear a less electron‐rich aryl group, even though these might offer enhanced reactivities. Thus, a series of novel [18F]FEOX (X=benzenesulfonyl, brosyl, nosyl, 3,4‐dibromobenzenesulfonyl) were synthesized and reactivities compared to [18F]FEOTs. Precursors for radiolabeling (bis‐ethylene glycol arylsulfonates) and reference FEOX were synthesized (alcohol+arylsulfonyl chloride+KOSiMe3 in THF). Regardless of substitution pattern, [18F]FEOX (110°C, 5 min, acetonitrile) were obtained in similar decay‐corrected isolated radiochemical yields (RCY; 47–53%). All [18F]FEOX gave excellent RCYs (64–87%) of the dopamine uptake radioligand, [18F]FECNT (130°C, 10 min, acetonitrile). The 3,4‐dibromobenzensulfonate gave the highest RCY of [18F]FECNT (87%) and this HPLC‐purified labeling agent was used directly for efficient [18F]FECNT production. When the secondary aniline of an amyloid probe (HM‐IMPY) or p‐nitrophenol was reacted with [18F]FEOX, RCYs were appreciably higher for brosylate and nosylate than for tosylate, while 3,4‐dibromobenzenesulfonate again gave the highest RCY. Owing to the high reactivity of the new [18F]FEOX and their ease of syntheses via stable precursors, such agents (particularly 3,4‐dibromobenzenesulfonate) should be considered as alternatives to [18F]FEOTs. Copyright © 2005 John Wiley & Sons, Ltd.