bluuebunny/crossref_metadata_2025_split huggingface dataset:
Laser tissue welding in ophthalmic surgery
Authors: Rossi Francesca , Matteini Paolo , Ratto Fulvio , Menabuoni Luca , Lenzetti Ivo , Pini Roberto 
Published: July 2008

AbstractLaser welding of ocular tissues is an alternative technique or adjunct to conventional suturing in ophthalmic surgery. It is based on the photothermal interaction of laser light with the main components of the extracellular matrix of connective tissues. The advantages of the welding procedure with respect to standard suturing and stapling are reduced operation times, lesser inflammation, faster healing and increased ability to induce tissue regeneration. The procedure we set up is based on the use of an infrared diode laser in association with the topical application of the chromophore Indocyanine Green. Laser light may be delivered either continuously or in pulses, thus identifying two different techniques that have been applied clinically in various types of transplants of the cornea. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
A prospective consecutive study of instrumented posterolateral lumbar fusion using synthetic hydroxyapatite (Bongros®‐HA) as a bone graft extender
Authors: Lee Jae Hyup , Hwang Chang‐Ju , Song Byung‐Wook , Koo Ki‐Hyung , Chang Bong‐Soon , Lee Choon‐Ki 
Published: July 2008

AbstractA prospective, single institution, clinical case‐matched, radiographic study was undertaken. Thirty‐two patients underwent posterior lumbar interbody fusion with cages containing laminectomized bone chips and posterolateral lumbar fusion with pedicle screws. Autogenous bone graft (3 mL) plus 3 mL of hydroxyapatite was placed in one side of a posterolateral gutter, and 6 mL of autogenous iliac bone graft was placed on the other side. Bony union, volumes of fusion mass, and bone absorption rates were postoperatively evaluated using simple radiographs and 3D‐CT scans. Average postoperative Lenke scores at 3 and 6 months in the hydroxyapatite group were statistically higher than in the autograft group, but at 12 months no difference was found between the hydroxyapatite and autograft groups in terms of fusion rate. Complete fusion rates by 3D‐CT were 86.7% in the hydroxyapatite group and 88.9% in the autograft group, which are not significantly different. Volumes of fusion mass and bone absorption rates at 12 months were 2.35 mL in the hydroxyapatite group and 1.31 mL in the autograft group. The mean fusion mass volume was greater in the hydroxyapatite group than in the autograft group. Lumbar posterolateral fusion using a mixture of hydroxyapatite artificial bone and autogenous bone graft showed good bony union similar to that shown with autogenous bone only. This study suggests that hydroxyapatite bone chips could be used usefully as a bone‐graft extender in short‐segment posterolateral spinal fusion. © 2008 Wiley Periodicals, Inc. J Biomed Mater Res, 2009
Tissue response and orbital floor regeneration using cyclic acetal hydrogels
Authors: Betz Martha W. , Caccamese John F. , Coletti Domenick P. , Sauk John J. , Fisher John P. 
Published: July 2008

AbstractOrbital floor injuries are a common form of traumatic craniofacial injury that may not heal properly through the body's endogenous response. Reconstruction is often necessary, and an optimal method does not exist. We propose a tissue engineering approach for orbital bone repair based upon a cyclic acetal biomaterial formed from 5‐ethyl‐5‐(hydroxymethyl)‐β,β‐dimethyl‐1,3‐dioxane‐2‐ethanol diacrylate (EHD) and poly(ethylene glycol) diacrylate (PEGDA). The EHD monomer and PEGDA polymer may be fabricated into an EH‐PEG hydrogel by radical polymerization. The objectives of this work were to study (1) the tissue response to EH‐PEG hydrogels in an orbital bone defect and (2) the induction of bone formation by delivery of bone morphogenetic protein‐2 (BMP‐2) from EH‐PEG hydrogels. EH‐PEG hydrogels were fabricated and implanted into an 8‐mm rabbit orbital floor defect. Experimental groups included unloaded EH‐PEG hydrogels, and EH‐PEG hydrogels containing 0.25 μg and 2.5 μg BMP‐2/implant. Results demonstrated that the unloaded hydrogel was initially bordered by a fibrin clot and then by fibrous encapsulation. BMP‐2 loaded EH‐PEG hydrogels, independent of concentration, were surrounded by fibroblasts at both time points. Histological analysis also demonstrated that significant bone growth was present at the 2.5 μg BMP‐2/implant group at 28 days. This work demonstrates that the EH‐PEG construct is a viable option for use and delivery of BMP‐2 in vivo. © 2008 Wiley Periodicals, Inc. J Biomed Mater Res, 2009
Synthesis, characterization, and biocompatibility of novel injectable, biodegradable, and in situ crosslinkable polycarbonate‐based macromers
Authors: Sharifi Shahriar , Imani Mohammad , Mirzadeh Hamid , Atai Mohammad , Ziaee Farshid , Bakhshi Raheleh 
Published: July 2008

AbstractA series of novel self‐crosslinkable and biodegradable polymers, poly(hexamethylene carbonate‐fumarate) and poly(hexamethylene carbonate) diacrylate, and their amphiphilic copolymers with polyethylene glycol, poly(ethylene glycol fumarate‐co‐hexamethylene carbonate‐fumarate) (PEGF‐co‐PHMCF), were developed for tissue engineering using propylene oxide as an acid scavenger. The synthesized polymers are white, which makes them more suitable for self‐crosslinking via photopolymerization. These novel polymers were fully characterized using nuclear magnetic resonance spectroscopy, Fourier‐transform infrared spectroscopy, gel permeation chromatography, differential scanning calorimetry, and rheometry. The cytocompatibility of the photocrosslinked networks were evaluated by [3‐(4,5‐dimethylthiazol‐2‐yl)‐2,5‐diphenyltetrazolium bromide] assay. These polymers can be used as precursors to prepare polymer networks and scaffolds with controlled hydrophilicity, biodegradability, and mechanical characteristics. Results obtained suggest that these polymers are potentially useful as injectable and photocrosslinkable materials for cell delivery, tissue engineering, and drug delivery applications. © 2008 Wiley Periodicals, Inc. J Biomed Mater Res, 2009
In vitro osteogenic potential of human bone marrow stromal cells cultivated in porous scaffolds from mineralized collagen
Authors: Bernhardt A. , Lode A. , Mietrach C. , Hempel U. , Hanke T. , Gelinsky M. 
Published: July 2008

AbstractPorous 3D structures from mineralized collagen were fabricated applying a procedure in which collagen fibril reassembly and precipitation of nanocrystalline hydroxyapatite (HA) occur simultaneously. The resulting matrices were evaluated in vitro with respect to their suitability as scaffolds for bone tissue engineering. We found a high capacity of the material to bind serum proteins as well as to absorb Ca2+ ions, which could be advantageous to promote cell attachment, growth, and differentiation. Human bone marrow stromal cells (hBMSCs) were seeded onto the 3D scaffolds and cultivated for 4 weeks in the presence and absence of osteogenic supplements. We studied viability, proliferation, and osteogenic differentiation in terms of total lactate dehydrogenase (LDH) activity, DNA content, and alkaline phosphatase (ALP) activity. Furthermore, the expression for bone‐related genes (ALP, bone sialo protein II (BSP II), and osteocalcin) was analyzed. In our investigation we found a 2.5‐fold to 5‐fold raise in DNA content and an increase of ALP activity for osteogenic induced hBMSC on collagen HA scaffolds. The expression of ALP and BSP II in these cells was also stimulated in the course of cultivation; however, we did not detect an upregulation of osteocalcin gene expression. These data suggest, that porous collagen HA scaffolds are suitable for the expansion and osteogenic differentiation of hBMSC and are therefore promising candidates for application as bone grafts. © 2008 Wiley Periodicals, Inc. J Biomed Mater Res, 2009
The influence of Young's modulus of loaded implants on bone remodeling: An experimental and numerical study in the goat knee
Authors: Stoppie Nele , Van Oosterwyck Hans , Jansen John , Wolke Joop , Wevers Martine , Naert Ignace 
Published: July 2008

AbstractThe aim of this study was to examine the influence of the Young's modulus of the implant material on the bone remodeling in a loaded condition. A combined animal experimental and computational study was set up. The animal experimental group comprised of 16 Saanen goats, each receiving one titanium implant (Young's modulus 110 GPa) and one high‐density polyethylene (HDPE) implant (Young's modulus 1 GPa) in the left femoral condyle. Both types of implants received a titanium coating of 100 nm thickness. The implants protruded in the knee joint space and were directly weight bearing. The first group of eight goats was sacrificed after 6 weeks of loading and the second group of eight goats after 6 months of loading. The 16 femoral condyles with the 32 implants were prepared for microfocus computed tomography (micro‐CT) scanning and histological sectioning. Three‐dimensional trabecular bone parameters were calculated on the micro‐CT images for the zones neck, middle, and apex of the implant. The percent of bone contact with the implant was measured on longitudinal histological sections. An axisymmetric finite element (FE) model was created to compare peri‐implant bone strains and relative motion between a titanium and a HDPE implant for the experimental loading condition, and to assess the influence of different bone‐implant interface (contact) conditions. From the statistical analysis of the 3D bone parameters, the difference between the titanium and HDPE implants was not significantly different (p > 0.05) between the zones (neck, middle, and apex) for both groups of goats. The implants could be considered in their entirety. After 6 weeks of loading, the PE implant presented lower connectivity and smaller marrow spaces in the circular region of 0–500 μm. In the region 500–1500 μm more bone volume was present for the PE implant. After 6 months, the PE implants showed more bone volume and thicker trabeculae than the titanium implants for the entire length of the implant. This effect was already present in the smallest region of interest, 0–500 μm. After 6 months more fibrous encapsulation was found around titanium implants. FE results demonstrated a substantial influence of the interface conditions on peri‐implant strains and relative motion. For interface conditions that were representative for the early postoperative situation (involving press‐fit and friction), differences in peri‐implant bone strain distributions between titanium and HDPE could be related to the experimentally observed differences in amounts of bone and fibrous encapsulation. In contrast, differences in relative motion did not seem to play a role. Both the experimental and computational results suggest that implant stiffness can affect the peri‐implant tissue response, which may be related to differences in peri‐implant strains. © 2008 Wiley Periodicals, Inc. J Biomed Mater Res, 2009
Regional variations in the viscoelastic compressive properties of the temporomandibular joint disc and implications toward tissue engineering
Authors: Lumpkins Sarah B. , McFetridge Peter S. 
Published: July 2008

AbstractEvidence from experimental and finite element studies have shown that the temporomandibular joint disc is heavily loaded during normal physiological function. Several studies have been carried out to investigate the response of the disc to tensile and static compressive forces. However, there is limited information that elucidates the dynamic characteristics of the disc under in vivo loading conditions. These investigations assessed the effect of physiologically relevant applied strain amplitudes and frequencies to determine regional mechanical properties of the disc. Cyclic tests on porcine TMJ discs were carried out over a period of 15 cycles, and the resultant compressive moduli and energy dissipation properties of the disc were reported. Results showed that modulus values were more dependent on strain amplitude than on frequency, and modulus values exhibited a strong regional variation. Clear hysteresis loops were evident in each set of testing parameters, and the only statistically significant regional variation in energy dissipation was between the central and medial regions. From these investigations, a more detailed understanding of the spatial mechanical properties of the TMJ disc has been achieved under physiologically relevant loading conditions. Combined with studies on other loading modalities of the disc, these results will serve as a benchmark for future TMJ disc tissue engineering endeavors. © 2008 Wiley Periodicals, Inc. J Biomed Mater Res, 2009
Cellular responses to degradable cyclic acetal modified PEG hydrogels
Authors: Kaihara Sachiko , Matsumura Shuichi , Fisher John P. 
Published: July 2008

AbstractIn this study, high viability of bone marrow stromal stem cells (BMSCs) encapsulated in a synthetic, poly[poly(ethylene glycol)‐co‐cyclic acetal] (PECA) hydrogel has been reported. This novel degradable hydrogel, which contains cyclic acetal as degradable segments and poly(ethylene glycol) (PEG) as hydrophilic segments, has been designed to limit the release of acidic products during hydrolytic degradation. PECAs with three different molecular weights (PECA 600, 1000, and 2000) were prepared to evaluate the effect of polymer main chain molecular weight on the viability and morphology of BMSCs embedded in PECA hydrogels as well as the viability of BMSCs exposed to PECA degradation products. Results demonstrated high BMSC viability when incubated in control media with PECA, while a significant decrease in viability was noted after 4 days when incubated in media augmented with PEG diacrylate. There was no effect of PECA molecular weight on the differentiation and cytotoxicity of degradation products up to 4 days, indicating that the degradation products' terminal carbonyl groups do not significantly affect cell viability and differentiation. BMSC viability when embedded on PECA hydrogels was evaluated by a LIVE/DEAD assay, and confirmed high viability up to 14 days. Gene expression analysis confirmed that BMSCs embedded in PECA hydrogels undergo osteogenic differentiation. Histological analysis also showed that cell morphology was significantly influenced by hydrogel swelling degree, which is itself controllable by the molecular weights of PECA main chains. These results indicate that PECA hydrogels may be utilized as scaffolds for regeneration of bone‐like tissues. © 2008 Wiley Periodicals, Inc. J Biomed Mater Res, 2009
Pulsed electric field as a potential new method for microbial inactivation in scaffold materials for tissue engineering: The effect on collagen as a scaffold
Authors: Smith Sharon , Griffiths Sarah , MacGregor Scott , Beveridge Joe , Anderson John , van der Walle Chris , Grant M. Helen 
Published: July 2008

AbstractHybrid scaffolds for tissue engineering are becoming increasingly complex through incorporation of biologically active biomacromolecules. There is a need to develop a compatible sterilization method that is capable of killing microorganisms, without adversely affecting the labile scaffold biomaterials or biomacromolecular components. Pulsed electric field (PEF) treatment has been successful as a nonthermal microbial inactivation–pasteurization method within the food industry. We have previously demonstrated that PEF treatment inactivates E. coli seeded in collagen gels. Here, we show that PEF treatment does not affect the structural integrity of the collagen molecule or its adsorption to polystyrene and hydroxyapatite surfaces. Moreover, osteoblast cells cultured on PEF‐treated collagen, which was coated onto two‐ and three‐dimensional scaffolds, retained their normal morphology, growth rate, and functionality. PEF treatment, therefore, shows great potential to be used as a sterilization method for collagen‐based biomaterials. © 2008 Wiley Periodicals, Inc. J Biomed Mater Res, 2009
Comparison of new bone formation, implant integration, and biocompatibility between RGD‐hydroxyapatite and pure hydroxyapatite coating for cementless joint prostheses—An experimental study in rabbits
Authors: Bitschnau Achim , Alt Volker , Böhner Felicitas , Heerich Katharina Elisabeth , Margesin Erika , Hartmann Sonja , Sewing Andreas , Meyer Christof , Wenisch Sabine , Schnettler Reinhard 
Published: July 2008

AbstractThis is the first work to report on additional Arginin‐Glycin‐Aspartat (RGD) coating on precoated hydroxyapatite (HA) surfaces regarding new bone formation, implant bone contact, and biocompatibility compared to pure HA coating and uncoated stainless K‐wires. There were 39 rabbits in total with 6 animals for the RGD‐HA and HA group for the 4 week time period and 9 animals for each of the 3 implant groups for the 12 week observation. A 2.0 K‐wire either with RGD‐HA or with pure HA coating or uncoated was placed into the intramedullary canal of the tibia. After 4 and 12 weeks, the tibiae were harvested and three different areas of the tibia were assessed for quantitative and qualitative histology for new bone formation, direct implant bone contact, and formation of multinucleated giant cells. Both RGD‐HA and pure HA coating showed statistically higher new bone formation and implant bone contact after 12 weeks than the uncoated K‐wire. There were no significant differences between the RGD‐HA and the pure HA coating in new bone formation and direct implant bone contact after 4 and 12 weeks. The number of multinucleated giant did not differ significantly between the RGD‐HA and HA group after both time points. Overall, no significant effects of an additional RGD coating on HA surfaces were detected in this model after 12 weeks. © 2008 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater, 2009
Recellularization of biological heart valves with human vascular cells: In vitro hemocompatibility assessment
Authors: Schopka Simon , Schmid Franz‐Xaver , Hirt Stephan , Birnbaum Dietrich E. , Schmid Christof , Lehle Karla 
Published: July 2008

AbstractCoverage of cardiovascular bioprostheses with autologous endothelium is used for the purpose of improving blood compatibility. The aim of our study was to analyze endothelialization potential of glutaraldehyde‐fixed heart valves, cellular functions of seeded endothelial cells (EC), and the impact of a two‐stage seeding protocol using human vascular fibroblasts (FB) and EC from saphenous veins (HSVEC) on cellular functional properties invitro. Adherence and morphology of adhered cells were assessed by scanning electronic microscopy and immunohistochemistry. Reproducible, complete surface coverage with EC was established on decellularized and glutaraldehyde‐fixed bovine pericardium. Analyzing functional properties of cells directly adhered to biomaterial revealed nonproliferative cells, which were capable of inflammatory stimulation in terms of TNF‐induced increase in interleukin‐6 secretion and adhesion of inflammatory cells. Furthermore, EC showed sustained antithrombotic properties quantified by platelet adhesion onto EC and prostacyclin secretion by EC. Preseeding with vascular fibroblasts using a two‐stage seeding protocol induced EC proliferation and improved inflammatory and anti‐thrombotic functions. Cardiovascular biomaterials differ significantly in their potential to allow for adhesion of human EC. Successfully endothelialized biomaterial, however, revealed cellular properties which are likely to be favorable to improving performance of biomaterials. Two‐stage seeding adds regenerative potential and improves cell functions of adherent EC. © 2008 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater, 2009
Fretting crevice corrosion of stainless steel stem–CoCr femoral head connections: Comparisons of materials, initial moisture, and offset length
Authors: Gilbert Jeremy L. , Mehta Manav , Pinder Bryan 
Published: July 2008

AbstractModular tapers continue to be used in a wide variety of orthopedic implants. In this study, stainless steel (ASTM F‐1568) femoral hip stems combined with Co‐Cr‐Mo alloy heads (SS/CoCr) were tested in an in vitro fretting corrosion test set‐up to assess the propensity for mechanically assisted corrosion. Three different aspects of the modular design were evaluated in this study: (1) material combination compared to CoCr/CoCr, (2) wet versus dry assembly for SS/CoCr couples, and (3) 0‐ and 6‐mm head offset for SS/CoCr couples. Fretting corrosion tests over a range of cyclic loads up to 3300 N were performed, and continuous cyclic loading at 3300 N for 1 M cycles were performed on each group (n = 5). Fretting micromotion was measured as a function of cyclic load on select couples to detect the nature and extent of motion present. The results showed that SS/CoCr couples were more susceptible to fretting corrosion than CoCr/CoCr couples, that dry assembly does not prevent fretting corrosion from taking place but raises the onset load, and that 6‐mm offset heads had higher visual evidence of fretting damage but showed mixed statistical results in terms of onset loads and OCP shifts and currents compared to the 0‐mm offset samples. Current and voltage excursions over 1million cycles tended to diminish towards their unloaded control levels but did not fully recover until cyclic loading ceased. Micromotion measurements indicated fretting motions in the range of 10–25 μm where 0‐mm heads tended to piston on the trunion, while 6 mm heads tended to rock. © 2008 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater, 2009
A 3‐year analysis of plateletpheresis donor deferral pattern in a tertiary health care institute: Assessing the current donor selection criteria in Indian scenario
Authors: Tondon Rashmi , Pandey Prashant , Chaudhry Rajendra 
Published: July 2008

AbstractIntroduction: This study reports the frequency and nature of plateletpheresis deferrals and evaluates donors with low platelet count and hemoglobin levels so as to assess the possibility of reentry without hampering donor safety. Materials and methods: Three‐year retrospective data of plateletpheresis deferral was collected. Data from actual procedures was also reviewed to analyze the safety of performing plateletpheresis in donors with low hemoglobin and platelet values. Results: Four hundred sixteen donors were deferred for various reasons among 1,515 screened (27.5%), of which 69.7% deferrals were because of low platelet count (55.8%) and less hemoglobin levels. Among the low platelet count donor group, 20.3% had a count between 141 and 149 × 109/L and 41.8% below 120 × 109/L. Of the 14% donors deferred for low hemoglobin, 62.1% had values in the range of 11.5–12.4 g/dL with normal mean corpuscular volume and red cell distribution width in most (86.2%) of them. Expected blood loss in each procedure varied between 20 and 30 mL, whereas RBC contamination in the product varied from 0 to 1.6 mL in 538 procedures. There were 176 donations with predonation platelet count <180 × 109/L (32.7%). None of the 14 procedures performed on donors with platelet count of 150 × 109/L showed evidence of thrombocytopenia or donor reaction. Conclusion: Lowering the cut‐off value for plateletpheresis from 12.5 g/dL to 11.5 g/dL has no deleterious effect on donor safety as the blood loss is minimal. One‐fifth deferrals can be reconsidered if the criteria of plateletpheresis donor selection are relaxed for hemoglobin and platelet count. J. Clin. Apheresis, 2008. © 2008 Wiley‐Liss, Inc.