bluuebunny/crossref_metadata_2025_split huggingface dataset:
Development of a new toxic-unit model for the bioassessment of metals in streams
Authors: Schmidt Travis S. , Clements William H. , Mitchell Katharine A. , Church Stanley E. , Wanty Richard B. , Fey David L. , Verplanck Philip L. , San Juan Carma A. 
Published: August 2010

Abstract
Two toxic-unit models that estimate the toxicity of trace-metal mixtures to benthic communities were compared. The chronic criterion accumulation ratio (CCAR), a modification of biotic ligand model (BLM) outputs for use as a toxic-unit model, accounts for the modifying and competitive influences of major cations (Ca2+, Mg2+, Na+, K+, H+), anions (HCO-3, Cl2−3, S2−) and dissolved organic carbon (DOC) in determining the free metal ion available for accumulation on the biotic ligand. The cumulative criterion unit (CCU) model, an empirical statistical model of trace-metal toxicity, considers only the ameliorative properties of Ca2+ and Mg2+ (hardness) in determining the toxicity of total dissolved trace metals. Differences in the contribution of a metal (e.g., Cu, Cd, Zn) to toxic units as determined by CCAR or CCU were observed and attributed to how each model incorporates the influences of DOC, pH, and alkalinity. Akaike information criteria demonstrate that CCAR is an improved predictor of benthic macroinvertebrate community metrics as compared with CCU. Piecewise models depict great declines (thresholds) in benthic macroinvertebrate communities at CCAR of 1 or more, while negative changes in benthic communities were detected at a CCAR of less than 1. We observed a 7% reduction in total taxa richness and a 43% decrease in Heptageniid abundance between background (CCAR = 0.1) and the threshold of chronic toxicity on the basis of continuous chronic criteria (CCAR = 1). In this first application of the BLM as a toxic-unit model, we found it superior to CCU. Environ. Toxicol. Chem. 2010;29:2432–2442. © 2010 SETAC
Interaction between an organic dye in water and sand packs in a flume system
Authors: Nome Rene A. , Souza Aloisio J. , Nome Carlos A. , Souza Bruno S. , Nome Faruk , Fiedler Haidi D. 
Published: August 2010

Abstract
The sorption kinetics of methylene blue (MB), a standard compound in the American Society for Testing and Materials tests, on natural sand in a batch system at a reciprocal shaking speed of 120 rpm is fast, with equilibrium and surface coverage attained in minutes. When the same experiment is carried out in a recirculating flume, adsorption is much slower, with lifetimes increasing up to several months in the flume. Sorption retardation is dependent on the diffusion coefficient of the dye and on the depth of penetration of the MB layer in sand. The experimental results suggest that, in field experiments, formation of thin films dramatically inhibits the sorption kinetics and, in a closed system, such as a lake or reservoir, contaminants will remain in the water column for long periods, with very slow penetration in the sediment layer. In rivers, the contaminant will travel farther with less penetration into the sediment layer, compared to more static systems. Environ. Toxicol. Chem. 2010;29:2426–2431. © 2010 SETAC
Effect of specimen geometry on tensile strength of cortical bone
Authors: Feng Liang , Jasiuk Iwona 
Published: August 2010

AbstractWe investigate the effect of specimen geometry on the ultimate tensile strength of cortical bone measured by a tensile test. This article is motivated by the fact that there is no clear consensus in the literature on a suitable specimen shape for cortical bone testing. We consider three commonly used tensile test specimen shapes: strip, dumbbell with sharp junctions, and dumbbell with rounded junctions. We conduct this study computationally, using a finite element method, and experimentally by testing porcine femurs. Our results show that local stress concentration factors in the specimen lead to reduced values in the measured tensile strength. The higher the stress concentrations are, the lower is the measured strength. We find that the strip specimens are not a good choice due to high stress concentrations. For the same reason, dumbbell specimens with sharp junctions between the grip and gage sections should also be avoided. The dumbbell shaped tensile test specimens with an arc transition and a maximized radius of fillet are a better choice because such geometry lowers stress concentrations. © 2010 Wiley Periodicals, Inc. J Biomed Mater Res Part A, 2010.
The effect of amphiphilic siloxane oligomers on fibroblast and keratinocyte proliferation and apoptosis
Authors: Lynam Emily C. , Xie Yan , Loli Bree , Dargaville Tim R. , Leavesley David I. , George Graeme A. , Upton Zee 
Published: August 2010

AbstractThe formation of hypertrophic scars (HSF) is a frequent medical outcome of wound repair and often requires further therapy with treatments such as silicone gel sheets (SGS) or apoptosis‐inducing agents, including bleomycin. Although widely used, knowledge regarding SGS and their mode of action is limited. Preliminary research has shown that small amounts of amphiphilic silicone present in SGS have the ability to move into skin during treatment. We demonstrate herein that a commercially available analogue of these amphiphilic siloxane species, the rake copolymer GP226, decreases collagen synthesis on exposure to cultures of fibroblasts derived from HSF. By size exclusion chromatography, GP226 was found to be a mixture of siloxane species, containing five fractions of different molecular weight. By studies of collagen production, cell viability and proliferation, it was revealed that a low molecular weight fraction (fraction IV) was the most active, reducing the number of viable cells present after treatment and thereby reducing collagen production as a result. On exposure of fraction IV to human keratinocytes, viability and proliferation were also significantly affected. HSF undergoing apoptosis after application of fraction IV were also detected via real‐time microscopy and by using the TUNEL assay. Taken together, these data suggests that these amphiphilic siloxanes could be potential non‐invasive substitutes to apoptotic‐inducing chemical agents that are currently used as scar treatments. © 2010 Wiley Periodicals, Inc. J Biomed Mater Res Part A, 2010.
Soft tissue adaptation to modified titanium surfaces
Authors: Lee Shermin , Goh Bee Tin , Wolke Joop , Tideman Henk , Stoelinga Paul , Jansen John 
Published: August 2010

AbstractSurface modification of titanium alloy implants to enhance soft tissue adherence is important to minimize soft tissue dehiscence. This study aimed to confirm if a dual acid etched “Osseotite®” titanium surface contributes to soft tissue adherence in muscle. It also aims to explore if a radio frequency magnetron sputtered hydroxyapatite (HA)/bioglass (BG) coating can serve this purpose and provides soft tissue adherence in mucosal tissue. The study was carried out in 18 Macaca fascicularis animals, 14 Osseotite® coated Ti6Al4V bullets inserted intramuscularly and 12 HA/BG coated Ti6Al4V plates inserted into the submucosa. These were compared with machined Ti6Al4V surfaces as controls. The histological and histomorphometrical results revealed that no significant difference existed in muscle tissue response between machined and Osseotite® surfaces. On the other hand, the HA/BG coated submucosal plates showed statistically significant differences with a thinner capsule quantity (p < 0.0001), an increased capsule quality (p < 0.0001) and interface quality score (p < 0.05). In conclusion, the deposited HA/BG coatings facilitated soft tissue (mucosa) adaptation at 1 month of implant installation, whereas the acid etched Osseotite® surface did not enhance muscular adaptation. © 2010 Wiley Periodicals, Inc. J Biomed Mater Res Part A, 2010.
Hydroxyapatite nanoparticles in poly‐D,L‐lactic acid coatings on porous titanium implants conducts bone formation
Authors: Jensen Thomas , Jakobsen Thomas , Baas Jørgen , Nygaard Jens V. , Dolatshahi‐Pirouz Alireza , Hovgaard Mads B. , Foss Morten , Bünger Cody , Besenbacher Flemming , Søballe Kjeld 
Published: August 2010

AbstractIt is well established in the field of biomaterials that hydroxyapatite (HA) may provide interesting osteoconductive properties. In this study, we investigated the osseointegrational effect of a 50/50 vol % composite of HA nanoparticles and poly‐D,L‐lactic acid (PDLLA) coated on model titanium bone implants in an in vivo animal model. The aim is to evaluate how the addition of HA to PDLLA may improve the bone formation and initial fixation of the implant. Two titanium implants coated with the PDLLA/HA composite and pure PDLLA, respectively, were implanted bilaterally in proximal part of humeri with a 2‐mm peri‐implant gap in 10 sheep. After 12 weeks, the remains of the coatings were present on 20.3 and 19.8% of PDLLA/HA composite‐ and PDLLA‐coated implants, respectively. It was observed that newly formed bone (39.3%) and fibrous tissue (58.3%) had replaced the PDLLA/HA composite, whereas pure PDLLA was replaced almost completely by fibrous tissue (96.2%). Consequently, the PDLLA/HA composite‐coated implants were better fixated as confirmed by push‐out tests. Using quantification of peri‐implant tissue and implant fixation as parameters, the present findings, therefore, clearly reveal that the addition of nanoparticulate HA to a PDLLA coating on titanium implants increases osseointegration. © 2010 Wiley Periodicals, Inc. J Biomed Mater Res Part A, 2010.
Core/shell microspheres via coaxial electrohydrodynamic atomization for sequential and parallel release of drugs
Authors: Nie Hemin , Dong Zhenguo , Arifin Davis Yohanes , Hu Yong , Wang Chi‐Hwa 
Published: August 2010

AbstractHerein, it is demonstrated that coaxial electrohydrodynamic atomization can be used for the fabrication of microspheres with distinct core/shell structure. This allows the encapsulation of two different types of drugs in different compartments in one single step. In Group A, we prepared microspheres in which the core and the shell contain hydrophobic and hydrophilic drugs, respectively. In contrast, in Group B, the opposite is prepared. While the former can be achieved by using amphiphilic polymers in aqueous environment, the latter is difficult to be prepared. The release patterns of the two groups are significantly different. The release of drugs from Group A microspheres is rather sequential, whereas group B microspheres release drugs in a parallel (co‐release) manner. Nevertheless, in both groups, we found that the release of drugs can be easily tailored by altering outer/inner flow ratios. These findings present the advantages and possible application of this multi‐drug release system in chemotherapy. Moreover, cell culture experiments have been performed to testify the performances of different microspheres in cytotoxicity and cellular apoptosis in vitro. © 2010 Wiley Periodicals, Inc. J Biomed Mater Res Part A, 2010.
Enhancement of capillary and cellular ingrowth in ePTFE implants with a proangiogenic recombinant construct derived from fibronectin
Authors: Wijelath Errol , Kohler Ted R. , Murray Jacqueline , Namekata Mayumi , Yagi Mayumi , Sobel Michael 
Published: August 2010

AbstractBased on our discoveries of a unique, synergistic interplay between vascular endothelial growth factor (VEGF) and specific domains of the matrix protein fibronectin (FN), we used recombinant technology to create a new protein construct derived from the cell‐binding and VEGF‐binding domains of FN. We wished to test the hypothesis that this prototype recombinant FN (rFN) protein would enhance cellular and capillary ingrowth in vivo into expanded polytetrafluoroethylene (ePTFE) implants. ePTFE disks of high porosity (60 micron internodal distance) were embedded with fibrin gel and heparin, with/without mixtures of VEGF and rFN and were implanted subcutaneously in rats. Control implants embedded with fibrin glue and heparin alone showed an average of 8.5% (±0.51% standard error mean (SEM)) cellular ingrowth. The addition of either VEGF or rFN caused a modest but significant increase in cellular ingrowth (12.7 ± 1% and 11.8 ± 0.98%, respectively, p < 0.004). However, the combination of rFN/VEGF/heparin dramatically increased cellular ingrowth (27.6 ± 1.62%, p < 0.001), compared with all other treatments. Quantification of capillary ingrowth yielded the same pattern. These results suggest that the incorporation of such biological modulators into cardiovascular implants could offer new strategies for the design of a ready‐made small diameter prosthetic graft with enhanced capacity for neovascularization and endothelialization. © 2010 Wiley Periodicals, Inc. J Biomed Mater Res Part A, 2010.
The impact of plasma rich in growth factors on clinical and biological factors involved in healing processes after third molar extraction
Authors: Mozzati Marco , Martinasso Germana , Pol Renato , Polastri Carolina , Cristiano Antonio , Muzio Giuliana , Canuto Rosa 
Published: August 2010

AbstractExtraction of an impacted mandibular third molar is a common surgical procedure, although it still leads to several postoperative symptoms and complications. The study assessed the efficacy of autologous plasma rich in growth factors (PRGF) in the healing process by checking the difference of tissue cytokines and other healing factors produced by the mucosa after extraction between sites treated with PRGF and control sites and, at the same time, by evaluating the clinical efficacy of PRGF in terms of reduced pain and facial swelling. This study was a split‐mouth study, in which the patient becomes his/her own control, to eliminate any individual response differences toward PRGF treatment. The parameters regarding inflammation and subsequent wound healing were all significantly higher at PRGF sites than at control sites. The increase at PRGF sites of the two proinflammatory cytokines evaluated, interleukin (IL)‐1β and IL‐6, was accompanied by the increase of two anti‐inflammatory cytokines, IL‐10 and transforming growth factor‐β. Furthermore, IL‐1β and IL‐6 induce fibroblast and keratinocyte proliferation, important events in wound healing. Postoperative pain and the swelling, measured at all experimental times, were reduced in the presence of PRGF. © 2010 Wiley Periodicals, Inc. J Biomed Mater Res Part A, 2010.
Long term in vitro biostability of segmented polyisobutylene‐based thermoplastic polyurethanes
Authors: Cozzens David , Ojha Umaprasana , Kulkarni Pallavi , Faust Rudolf , Desai Shrojal 
Published: August 2010

AbstractLong term in vitro biostability of thermoplastic polyurethanes (TPUs) containing mixed polyisobutylene (PIB)/poly(tetramethylene oxide) (PTMO) soft segment was studied under accelerated conditions in 20% H2O2 solution containing 0.1M CoCl2 at 50°C to predict resistance to metal ion oxidative degradation (MIO) in vivo. The PIB‐based TPUs showed significant oxidative stability as compared to the commercial controls Pellethane™ 2363‐55D and 2363‐80A. After 12 weeks in vitro the PIB‐PTMO TPUs with 10–20% PTMO in the soft segment showed 6–10% weight loss whereas the Pellethane™ TPUs degraded completely in about 9 weeks. Attenuated total reflectance Fourier transform infrared spectroscopy confirmed the degradation of Pellethane™ samples via MIO by the loss of the ∼1110 cm−1 aliphatic COC stretching peak height attributed to chain scission, and the appearance of a new peak at ∼1174 cm−1 attributed to crosslinking. No such changes were apparent in the spectra of the PIB‐based TPUs. The PIB‐based TPUs exhibited 10–30% drop in tensile strength compared to 100% for the Pellethane™ TPUs after 12 weeks. The molecular weight of the PIB‐based TPUs decreased slightly (10–15%) at 12 weeks. The Pellethane™ TPUs showed a dramatic decrease in Mn and an increase in low molecular weight degradation product. Scanning electron microscopy (SEM) showed severe cracking in the Pellethane™ samples after 2 weeks, whereas the PIB‐based TPUs exhibited a continuous surface morphology. The weight loss, tensile, and SEM data correlate well with each other and indicate excellent biostability of these materials. © 2010 Wiley Periodicals, Inc. J Biomed Mater Res Part A, 2010.
Suppression of anoikis by collagen coating of interconnected macroporous nanometric carbonated hydroxyapatite/agarose scaffolds
Authors: Alcaide María , Serrano María‐Concepción , Roman Jesús , Cabañas María‐Victoria , Peña Juan , Sánchez‐Zapardiel Elena , Vallet‐Regí María , Portolés María‐Teresa 
Published: August 2010

AbstractThree dimensional interconnected macroporous (pore diameter: 600–800 μm) hydroxyapatite/agarose disks have been evaluated in this study as potential bone regeneration scaffolds. With this purpose, the adhesion and proliferation of human Saos‐2 osteoblasts on this biomaterial were analyzed. As an index of cell function, the following parameters were measured: cell morphology, viability, cell size/complexity, cell cycle, reactive oxygen species (ROS) content, and lactate dehydrogenase (LDH) release. The existence of anoikis induced by inappropriate contacts between the cell and the scaffold has been detected by scanning electron microscopy, confocal microscopy, and flow cytometry. The intracellular nitric oxide content has been also measured as potential inducer of anoikis. The positive effects of previous scaffold coating with type I collagen on osteoblast adhesion as well as the collagen protection against anoikis have been demonstrated in this study. © 2010 Wiley Periodicals, Inc. J Biomed Mater Res Part A, 2010.
In vitro osteoblast‐like cell proliferation on nano‐hydroxyapatite coatings with different morphologies on a titanium‐niobium shape memory alloy
Authors: Xiong Jianyu , Li Yuncang , Hodgson Peter D. , Wen Cui'e 
Published: August 2010

AbstractThe morphology of nanomaterials significantly affects their physical, chemical, and biological properties. In the present study, nano‐hydroxyapatite coatings with different morphologies were produced on the surface of a titanium‐niobium shape memory alloy via a hydrothermal process. The effect of the nano‐hydroxyapatite coatings on the in vitro proliferation of SaOS‐2 osteoblast‐like cells was investigated. Factors including crystallinity, surface micro‐roughness, and surface energy of the nano‐hydroxyapatite coatings were discussed. Results show that in vitro proliferation of the osteoblast‐like cells was significantly enhanced on the nano‐hydroxyapatite‐coated titanium‐niobium alloy compared to the titanium‐niobium alloy without coating. The cell numbers on the nano‐hydroxyapatite‐coated titanium‐niobium alloy changed consistently with the surface energy of the hydroxyapatite coatings. This study suggests that surface energy as a characteristic parameter influencing the in vitro proliferation of osteoblast‐like cells was predominant over the crystallinity and surface micro‐roughness of the nano‐hydroxyapatite coatings. © 2010 Wiley Periodicals, Inc. J Biomed Mater Res Part A, 2010.
Biofilm formation and composition on different implant materials in vivo
Authors: Al‐Ahmad A. , Wiedmann‐Al‐Ahmad M. , Faust J. , Bächle M. , Follo M. , Wolkewitz M. , Hannig C. , Hellwig E. , Carvalho C. , Kohal R. 
Published: August 2010

AbstractBiofilm formation was evaluated on the following titanium and zirconia implants in vivo: machined titanium (Ti‐m), modified titanium (TiUnite®), modified zirconia (ZiUnite®), machined alumina‐toughened zirconia (ATZ‐m), sandblasted alumina‐toughened zirconia (ATZ‐s), and machined zirconia (TZP‐A‐m). Bovine enamel slabs were used as controls. Surface morphologies were examined by atomic force (AFM) and scanning electron microscopy (SEM). The surface wettability was also determined. Twelve healthy volunteers wore a splint system with the tested materials. After 3 and 5 days the materials were examined by fluorescence in situ hybridization (FISH) and confocal laser scanning microscopy (CLSM). The levels of Streptococcus spp., Veillonella spp., Fusobacteriaum nucleatum, and Actinomyces naeslundii were quantitatively determined. The biofim thickness was found to be between 19.78 and 36.73 μm after 3 days and between 26.11 and 32.43 μm after 5 days. With the exception of Ti‐m the biofilm thickness after 3 days was correlated with surface roughness. In addition to Streptococcus spp. as the main component of the biofilm (11.23–25.30%), F. nucleatum, A. naeslundii, and Veillonella spp. were also detected. No significant differences in biofilm composition on the implant surfaces could be observed. In total, the influence of roughness and material on biofilm formation was compensated by biofilm maturation. © 2010 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater, 2010.
Impactability and time‐dependent mechanical properties of porous titanium particles for application in impaction grafting
Authors: Walschot L. H. B. , Schreurs B. W. , Buma P. , Verdonschot N. 
Published: August 2010

AbstractAims: Impaction grafting with bone particles is a successful technique to restore bone stock loss during hip revision surgery. Allograft shortage is expected within the near future. This study investigates the feasibility of porous titanium particles (TiP) to replace bone particles (BoP) and to compare mechanical properties of TiP and a commercially available porous ceramic bone graft extender (CeP). Impactability and time‐dependent mechanical properties (stability and stiffness during physiologic loading (0.1–2.5 MPa)) were assessed by standardized impaction and a confined compression test. Loaded samples were used for particle release analysis. Findings: TiP were more impactable than BoP and created a stable, highly entangled macroporous construct. CeP were crushed during impaction, resulting in non‐cohesive specimens of small ceramic particles. TiP showed very little deformation at the end of physiological loading. Impacted TiP were stiffer than BoP but more elastic than CeP. TiP generated a low volume of microparticles (0.2% of original TiP weight) with a bimodal size distribution (diameter range, 7–2000 (m). Conclusion: TiP are impactable and create a stable, elastic and highly entangled, macroporous layer. Further in‐vitro testing and biological studies are warranted to verify whether the promising results are maintained with THA reconstructions. © 2010 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater, 2010.
Bone properties surrounding hydroxyapatite‐coated custom osseous integrated dental implants
Authors: Baker M. I. , Eberhardt A. W. , Martin D. M. , McGwin G. , Lemons J. E. 
Published: August 2010

AbstractCalcium phosphate (hydroxyapatite or HA) coatings have been applied to Custom Osseous Integrated Implants (COIIs) to improve the quality of the bone‐implant integration, yet little is known concerning the biomechanical properties of bone surrounding the HA‐coated implants in humans over the long term. The purpose of this study was to characterize the mechanical and histomorphometric properties of the bone along the implant interface. Specimens were prepared from three similar mandibular implants that were functional in three female patients for about 11 years. Histomorphometric analyses showed bone‐implant contact averaging 75% for all specimens. Area coverage of residual HA‐coating ranged from 52 to 70%. When compared with previous studies, these results show a relatively high percentage of residual HA after a decade in vivo. Nanoindentation showed similar average values of hardness and modulus (p = 0.53 and p = 0.56, respectively) comparing bone adjacent to residual HA‐coating and regions where the coating was absent. The elastic modulus was significantly lower for bone near the bone‐implant interface (<200 μm) as compared with bone distant (>1000 μm) from the interface (p = 0.05), thereby reflecting different properties of the bone near these interfaces. Backscattered electron imaging showed darker gray levels which indicated decreased mineral content in bone adjacent to the implant, consistent with the nanoindentation results. © 2010 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater, 2010.