bluuebunny/crossref_metadata_2025_split huggingface dataset:
Permeation of protein from porous poly(ϵ‐caprolactone) films
Authors: Lu Chia‐Hui , Lin Wen‐Jen 
Published: October 2004

AbstractThe objective of this study was designed to extend the application of poly(ϵ‐caprolactone) (PCL) in delivery of macromolecular proteins. The strategy applied here is to create a porous structure in PCL films in order to control the diffusion rate of protein. Various amounts of both high‐molecular‐weight and low‐molecular‐weight poly(ethylene glycol) (PEG) were used as pore‐forming agents. The porous films were prepared by a solvent‐casting‐leaching method. The thicknesses of the prepared films were controlled to be in the range of 75.3 ± 0.6 ∼ 81.7 ± 0.6 μm. The pore fraction of films was determined to be 27.7 ± 1.0% ∼ 52.5 ± 0.8% for PEG10000 and 26.6 ± 1.8% ∼ 48.8 ± 1.4% for PEG4000. The pore fraction initially increased with increasing amounts of PEG, independent of the molecular weight of PEG. In the permeation study, lysozyme was used as a model diffuser. The permeation rate of protein increased as the pore fraction of films increased, especially when 30 ∼ 40% of PEG was added initially, and this phenomenon was more prominent when low‐molecular‐weight PEG was used. This result was probably due to the highly porous structure creating interconnected channels in the films, further enhancing protein diffusion. In addition, the size of micropores formed by PEG4000 was observed to be larger than by PEG10000, which also accounted for faster permeation rate of lysozyme through PCL‐PEG4000 porous films. © 2002 John Wiley & Sons, Inc. J Biomed Mater Res (Appl Biomater) 63: 220–225, 2002; DOI 10.1002/jbm.10120
Macroporous poly(L‐lactide) scaffold 1. Preparation of a macroporous scaffold by liquid–liquid phase separation of a PLLA–dioxane–water system
Authors: Hua Feng Jun , Kim Go Eun , Lee Jong Doo , Son Yong Keun , Lee Doo Sung 
Published: October 2004

AbstractA biodegradable poly(L‐lactic acid) (PLLA) macroporous scaffold with a regular and highly interconnected structure in the size range from 50 to 150 μ m was fabricated from a PLLA–dioxane–water ternary system with the use of the thermally induced phase separation (TIPS) process. The phase diagram of PLLA with molecular weight above 200,000 was measured. It was found that a small change in the water content in the solvent caused a large shift in the cloud‐point temperature. The porous morphology of the scaffold was closely related to the quenching route and formulation parameters, including polymer concentration, quenching temperature, aging time, and solvent composition of the ternary system. The porous morphology development in the scaffold was recorded as a function of aging time by scanning electronic microscopy (SEM). For systems with lower polymer concentrations (<4.5 wt%), polymer sedimentation occurred in the later stages of phase separation. A slight increase in the water content of the solvent mixture caused the sedimentation boundary to expand to higher polymer concentration. For systems with higher polymer concentrations (≥4.5 wt%), the development of phase separation was restricted by gelation that resulted from the crystallization of the PLLA chains. This gelation effect was greater at high polymer concentrations and low quenching temperatures. The macroporous expected scaffold could be optimized from the slow development of phase separation during the long coarsening process. © 2002 John Wiley & Sons, Inc. J Biomed Mater Res (Appl Biomater) 63: 161–167, 2002
Effect of additives on the microstructure and thermal properties of a mica‐based glass‐ceramic
Authors: Denry I. L. , Holloway J. A. 
Published: October 2004

AbstractPrevious work has shown that lithium mica glass‐ceramics were excellent potential candidates as dental ceramics. The purpose of this study was to evaluate the effect of various additives on the microstructure and thermal properties of a mica glass‐ceramic in the system Li2O‐K2O‐SiO2‐MgO‐F. Five glass compositions were prepared: a base composition and four compositions with various additives. The compositions were melted at 1400 °C for 2 h and cast into 50 × 8 mm ingots. Differential thermal analyses were performed on the glasses up to 1400 °C. Bars (4 × 8 × 25 mm) were cut from the ingots and heat treated at various temperatures. The crystalline phases were analyzed by x‐ray diffraction. The microstructure was investigated by scanning electron microscopy. The percent crystallinity, crystal density, and average particle size were calculated from stereology measurements. X‐ray diffraction revealed that the major crystalline phase was taeniolite for all glass‐ceramics. Differential thermal analyses showed that the crystallization exotherm occurred in the temperature range 600–700 °C. The addition of calcium fluoride was most efficient in promoting the growth of mica crystals. Larger mica plate diameter could be beneficial to the crack‐propagation resistance of the glass‐ceramic. The addition of aluminum phosphate promoted nucleation rather than crystal growth and led to a significantly lower glass transition temperature and crystallization exotherm temperature. © 2002 Wiley Periodicals, Inc. J Biomed Mater Res (Appl Biomater) 63: 146–151, 2002; DOI 10.1002/jbm.10122
Healing process induced by three composite prostheses in the repair of abdominal wall defects
Authors: Bellón Juan M. , Jurado Francisca , García‐Moreno Francisca , Corrales Celia , Carrera‐San Martín Antonio , Buján Julia 
Published: October 2004

AbstractThe present study compared the performance of three composite prostheses used to repair abdominal wall defects in rabbits. Two of them [Parietex Composite® (PC) and Composix® (CS)] are commonly used in clinical practice and one was designed by the present team (PL‐PU99). At 14 and 90 days postimplant, specimens were obtained for morphological, macrophage response (RAM‐11) and morphometric and biomechanical analysis. The prosthetic area covered by adhesions was significantly greater (p < 0.05) in the CS group (6.83 ± 2.31 cm2) than in PC (0.11 ± 0.02 cm2) or PL‐PU99 (0.10 ± 0.07 cm2). At 14 days, it was observed a homogeneous, organized, well‐vascularized neoperitoneum that was significantly thicker (p < 0.05) in PL‐PU99. Except in the CS implants, this layer was covered by a continuous mesothelium. All three composites achieved good recipient tissue integration. Highest macrophage levels were recorded at 14 days with significantly higher values in the PL‐PU99 prosthesis. Biomechanical strength was significantly greater (p < 0.05) in CS at two weeks postimplant, but it was similar at 90 days. These findings suggest that the three composites show ideal integration with host tissue, along with similar biomechanical strength at 90 days, and significantly higher adhesion formation is induced by the CS prosthesis, possibly due to incomplete mesothelialization of the lower prosthetic surface. © 2002 John Wiley & Sons, Inc. J Biomed Mater Res (Appl Biomater) 63: 182–190, 2002; DOI 10.002/jbm.10123
Cytotoxicity of precious and nonprecious alloys—experimental comparison of in vitro data from two laboratories
Authors: Bumgardner Joel D. , Gerard Patrick D. , Geurtsen Werner , Leyhausen Gabriele 
Published: October 2004

AbstractThe aim of this investigation was to evaluate and compare the reproducibility of cytotoxicity data generated in two different laboratories using the same testing protocols. A series of dental alloys that are widely used in both countries were chosen. These alloys (five precious, two nonprecious) were wet ground up to 1200 grit SiC, sterilized in 70% ethanol, and extracted in sterile culture medium for 7 days. Pure copper was used as a positive control and Teflon® and media only were used as negative controls. Test and control samples were randomized and blinded to each laboratory. Cells, primary human gingival fibroblasts, and immortalized 3T3 fibroblasts, were exposed to the extracts for 24 h. Extract cytotoxicity was evaluated spectrophotometrically with the use of a mitochondrial enzyme activity assay. Data were collected from both laboratories, combined, and subjected to a mixed‐model analysis of variance. No statistical difference was obtained for the immortalized 3T3 cells, except for two extracts in which differences between the two labs were significant but were still not cytotoxic. Furthermore, no statistical differences were found for the primary cells. These data strongly suggest that cytotoxicity tests performed in different laboratories with the use of the same test materials may lead to comparable results if sample preparation, cells, test procedures, and data analyses are carefully considered. © 2002 John Wiley & Sons, Inc. J Biomed Mater Res (Appl Biomater) 63: 214–219, 2002; DOI 10.1002/jbm.10124
Mechanical properties of newly developed loop ligament for connection between the endobutton and hamstring tendons: Comparison with Ethibond sutures and Endobutton tape
Authors: Uchio Yuji , Ochi Mitsuo , Sumen Yoshio , Adachi Nobuo , Kawasaki Kenzo , Iwasa Junji , Katsube Kenichi 
Published: October 2004

AbstractA new artificial loop ligament (LL) without mechanical weak points, such as a knot, has been developed to connect the EndoButton and hamstring tendons for anterior or posterior cruciate ligament (CL) reconstruction. This study assessed the mechanical properties of the LL and sutures (No. 5 Ethibond thread, EndoButton tape) and those of the different CL constructs with these materials and fixation devices commonly used in CL reconstruction. The LL had a significantly higher ultimate tensile load (UTL) and stiffness value (p < 0.001) than No. 5 Ethibond thread or EndoButton tape in static and fatigue tests (50–500 N, 1.08 million cycles). The LL‐tendons‐Leeds‐Keio artificial ligament‐staple construct complex also had significantly higher UTL and stiffness value than the Ethibond loops or EndoButton tape loop‐tendons‐Ethibond sutures‐postscrew‐fixed construct complex. Furthermore, the LL construct complex elongated the least after cyclic loading (50–150 N, 90,000 cycles). These findings suggested that using the LL construct complex might avoid a bungee cord effect and elongation before biological healing between the construct and bony socket. The LL construct complex could be a safe substitute for use during the postoperative period. © 2002 John Wiley & Sons, Inc. J Biomed Mater Res (Appl Biomater) 63: 173–181, 2002; DOI 10.002/jbm.10125
Thermal analysis of dental resins cured with blue light‐emitting diodes (LEDs)
Authors: Nomura Y. , Teshima W. , Tanaka N. , Yoshida Y. , Nahara Y. , Okazaki M. 
Published: October 2004

AbstractThermal analysis was used to measure the characteristics of dental resins cured with the use of a new light‐activation unit equipped with high illuminant blue light‐emitting diodes (LEDs). The characteristics were compared with those of resins cured with the use of two conventional halogen lamp units. The prepared base monomer consisted of a mixture of Bis‐GMA and TEGDMA (60:40 by weight), with 0.5 wt% CQ/DMPT or CQ/DMAEMA. The two experimental visible‐light‐cured resins were polymerized for 40 s. Differential scanning calorimetry (DSC) was used to examine the thermal characteristics of the cured resins. The activation energy for the decomposition of the dental resin was calculated from the peaks of the endothermic curves obtained when the specimens were heated at three different rates (5, 10, and 15 °C/min) during DSC. The activation energies calculated for the LED‐cured specimens were more than 220 kJ/mol; specimens cured with the use of the halogen units had activation energies of less than 192 kJ/mol. The Knoop hardness number (KHN) of the same specimens was measured, and was higher with the blue LED units than with halogen lamp units. Therefore, dental resins cured using blue LEDs have a higher degree of polymerization and more stable three‐dimensional structures than those cured with halogen lamps. © 2002 John Wiley & Sons, Inc. J Biomed Mater Res (Appl Biomater) 63: 209–213, 2002; DOI 10.1002/jbm.10126
Rheological properties of acrylic bone cement during curing and the role of the size of the powder particles
Authors: Lewis Gladius , Carroll Michael 
Published: October 2004

AbstractA dynamic compressive rheometric technique was used to determine the true or complex viscosity (η*) of three poly (methyl methacrylate), PMMA‐based bone cement formulations (one commercially available and two experimental), as a function of the time that elapsed from commencement of hand mixing of the cement constituents (t). For each cement, two rheological parameters [namely, the time of onset of cure (tons) and the critical cure rate (CCR), which is herein defined as the complex viscosity rate computed at tons] were determined from the η*−t data. For each cement, particle analysis was used to obtain the powder particle size distribution, from which the following parameters were obtained: (a) the overall mean particle diameter Dm, and (b) the relative amounts of small‐sized PMMA beads (mean diameter d between 0 and 40 μm) (α) and large‐sized PMMA beads (d > 75 μm) (β). It is seen that the key particle parameter is not Dm per se but α and β. Thus, the highest values of tons and CCR were obtained from a cement with the highest values of α and β. An explanation for these trends is given, and two areas for further research work in this field are outlined. © 2002 John Wiley & Sons, Inc. J Biomed Mater Res (Appl Biomater) 63: 191–199, 2002; DOI 10.1002/jbm.10127
Bioactivity and osseointegration study of calcium phosphate ceramic of different chemical composition
Authors: Manjubala I. , Sivakumar M. , Sureshkumar R. V. , Sastry T. P. 
Published: October 2004

AbstractSynthetic hydroxyapatite (HA) and tricalcium phosphate (TCP) are promising bone‐substitute materials in the orthopaedic and dental fields, as their chemical composition is similar to that of bone. This study investigated the osseointegration performance of carbonated biphasic calcium phosphate (CBCP) ceramics containing carbonated hydroxyapatite and tricalcium phosphate prepared by microwave irradiation, in femoral defects of dogs. The defects were created as 3‐mm holes on the lateral aspect of femur and filled with the implant material. The serum was collected postoperatively and biochemical assays for alkaline phosphatase activity levels were carried out. The animals' defective sites were radiographed at 4, 8, and 12 weeks. The radiographic results showed that the process of ossification started after 4 weeks and the defect was completely filled with new bone after 8 weeks. Histological examination of the tissue showed the osteoblastic activity inducing the osteogenesis in the defect. The complete haversian system with osteoblastic and osteoclastic activity and bone remodelling process were observed after 12 weeks. The alkaline phosphatase activity levels also correlated with the formation of osteoblast cells. This calcium phosphate ceramic has proved to work well as a biocompatible implant and as an osteoconductive and osteoinductive material for the filling of bone defects. © 2002 John Wiley & Sons, Inc. J Biomed Mater Res (Appl Biomater) 63: 200–208, 2002; DOI 10.1002/jbm.10128
Flexural strength distribution of a PMMA‐based bone cement
Authors: Vallo Claudia I. 
Published: October 2004

AbstractPolymethylmethacrylate bone cement containing either no added antibiotic or 0.5 g of Gentamicin was prepared and stored either in air at room temperature or in a 37 °C water bath for 48 h. An additive‐free cement stored in air at room temperature was also tested for purposes of comparison. Following storage the specimens were tested in flexure. Weibull statistics demonstrated to fit the flexural strength distribution of all the materials tested with regression coefficients of at least 0.98. The presence of a BaSO4 radiopacifier markedly reduced the mean flexural strength and increased the data scatter in the air‐stored specimens. On the other hand, the flexural strength of both impregnated and nonimpregnated antibiotic increased when those materials were stored in water at 37 °C, compared with the same material stored in air, as a consequence of the water ingress. The water‐stored antibiotic‐impregnated cement displayed lower flexural strength, increased data scatter, and a remarkably higher number of weak specimens compared with the antibiotic‐free cement. The influence of the load type on the flexural behavior was studied by testing the air‐stored specimens in three‐point bending and four‐point bending. Cements tested in four‐point bending resulted in lower flexural strength than that tested in three‐point bending. The ratio of mean strength measured in the different load arrangements was satisfactory, as predicted by the Weibull model. © 2002 John Wiley & Sons, Inc. J Biomed Mater Res (Appl Biomater) 63: 226–236, 2002; DOI 10.1002/jbm.10129
A new electrochemically graded hydroxyapatite coating for osteosynthetic implants promotes implant osteointegration in a rat model
Authors: Schmidmaier G. , Wildemann B. , Schwabe P. , Stange R. , Hoffmann J. , Südkamp N. P. , Haas N. P. , Raschke M. 
Published: October 2004

AbstractHydroxyapatite (HAP) is widely used as an osteoconductive coating for orthopedic implants. So far standard coating methods like plasma spraying produce a relatively thick coating layer (>30 μm). In addition, the chemical structure of the HAP may be altered because of the heating throughout the coating process. This may have negative effects on the coating stability, implant fixation, and induction of bone formation. The relatively thick layer may detach from the implant with the risk of wear debris. In the present study the potential of a newly developed HAP coating of implants on osteointegration was investigated in a rat model. The coating method, based on an electrochemical process, is applied in a graded manner and results in a biodegradable HAP coating with a thickness of approximately 2 μm. Coated versus uncoated titanium Kirschner wires (1.4‐mm diameter) were inserted into the medullary cavity of the right femora of 5‐month old female Sprague Dawley rats (n=36) in a retrograde fashion. Throughout an experimental period of 2 months the osteointegration was traced radiologically. After this time the animals were sacrificed and the implant integration was tested biomechanically with the use of a push‐out test. To analyze the bone‐implant interface, histological sections (80 μm) were investigated with an image analyzing system. The biomechanical testing revealed a significantly higher implant fixation in the group treated with the HAP‐coated implant (shear strength: 27.8 ± 6.7 MPa) compared to control (shear strength: 8.08 ± 3.4 MPa). The histological analyses demonstrated a better ingrowth of the implants in the HAP group with significantly more direct bone‐implant contacts compared to the control group. The results demonstrate that the HAP coating promotes implant osteointegration in a rat model. © John Wiley & Sons, Inc. J Biomed Mater Res (Appl Biomater) 63: 168–172, 2002; DOI 10.002/jbm.10130
Bioactive glass as bone‐graft substitute for posterior spinal fusion in rabbit
Authors: Lindfors N. C. , Tallroth K. , Aho A. J. 
Published: October 2004

AbstractBioactive glass S53P4 and autogenous bone were studied as bone graft materials for spinal fusion in a rabbit model. Sixteen rabbits underwent surgery by a dorsal approach. A bioactive glass, a combination of bioactive glass and autogenous bone (70/30 vol%), and autogenous bone were implanted at two thoracolumbar vertebraes for 4 and 12 weeks. The volume, consolidation to vertebrae, and fusion of the graft material were evaluated with plain‐film radiology, computed tomography (CT) and bone‐mineral density measurements, and compared with histomorphometrical measurements. Radiological consolidation by CT of bone graft to underlying vertebrae at 12 weeks was observable in all groups. This was histologically confirmed as bone was growing from the vertebrae into the graft material. Radiologic fusion of vertebraes was, at 12 weeks, observable in all groups in 50–75% of the cases. The radiologic fusion seen at the CT scans could, however, not be confirmed by histology in any of the three groups. Significant differences for graft material and observation period with the use of bone‐mineral density measurements (Hounsfield units) were also observable, with the highest measured values for the bioactive glass group and the lowest for the autogenous bone group. The results indicate that bioactive glass have potential as bone‐graft material in spinal fusion. The reliability of radiologic evaluation methods in spinal surgery using bone substitutes is also questioned and discussed. © 2002 John Wiley & Sons, Inc. J Biomed Mater Res (Appl Biomater) 63: 237–244, 2002; DOI 10.1002/jbm.10177
Failure characteristics of multiple‐component fibrin‐based adhesives
Authors: Sierra David H. , Eberhardt Alan W. , Lemons Jack E. 
Published: October 2004

AbstractA series of analyses were performed on fibrin‐based adhesives to describe their failure characteristics. Two test methods were used: uniaxial, monotonic tensile testing of the bulk material, and blister testing using fresh porcine‐source skin graft as the adherend. Two fibrin concentrations, high (HFC), and low (LFC), were used to investigate the effects of the gel matrix density upon mechanical properties. In tensile tests, fibrin gels strain hardened, as functions of percent strain and of strain rate. An increase in modulus of elasticity (E) was seen with increasing strain and strain rate at both tested fibrin concentrations. Mode I failure mechanisms were predominant. Both adhesives appeared to fracture from the outer edge to the interior of the specimen at slower strain rate tests. This trend reversed as strain rate increased, becoming a classic “cup and cone” ductile fracture. Syneresis occurred at both concentrations at lower strain rates, but was more pronounced for the LFC. Ultimate tensile strength and E were greater for the HFC than for the LFC at all strain rates, decreasing with increasing strain rate. In the blister test, the failure locus changed from cohesive to adhesive as the strain rate was increased for the HFC. Failure of fibrin gels likely occurs by percolation of the pressurized saline, displacing the entrapped liquid phase of the gel in regions of relatively low moduli and strength, leading to fracture of the matrix. For LFC, the overall fracture locus remained predominantly cohesive regardless of strain rate. Burst strength and failure energy were higher for HFC than for LFC. It would appear that fibrin acts more as a viscous liquid than a rubberlike/elastic material at lower concentrations because adhesive failures had a higher burst strength and fracture energy (Gc) than did cohesive failures. © 2001 Wiley Periodicals, Inc. J Biomed Mater Res 59: 1–11, 2002