pinecone/core-2020-05-10-deduplication huggingface dataset:
A systematic review and meta-analysis on the influence of biological implant surface coatings on periimplant bone formation

This systematic review and meta-analysis evaluated the influence of biological implant surface coatings on periimplant bone formation in comparison to an uncoated titanium reference surface in experimental large animal models. The analysis was structured according to the PRISMA criteriae. Of the1077 studies, 30 studies met the inclusion criteriae. Nineteen studies examined the bone implant contact (BIC) and were included in the meta-analysis. Overall, the mean increase in BIC for the test surfaces compared to the reference surfaces was 3.7 percentage points (pp) (95% CI -3.9-11.2, p = 0.339). Analyzing the increase in BIC for specific coated surfaces in comparison to uncoated reference surfaces, inorganic surface coatings showed a significant mean increase in BIC of 14.7 pp (95% CI 10.6-18.9, p < 0.01), extracellular matrix (ECM) surface coatings showed an increase of 10.0 pp (95% CI 4.4-15.6, p < 0.001), and peptide coatings showed a statistical trend with 7.1 pp BIC increase (95% CI -0.8-15.0, p = 0.08). In this review, no statistically significant difference could be found for growth factor surface coatings (observed difference -3.3 pp, 95% CI -16.5-9.9, p = 0.6). All analyses are exploratory in nature. The results show a statistically significant effect of inorganic and ECM coatings on periimplant bone formation. © 2016 Wiley Periodicals, Inc. J Biomed Mater Res Part A: 104A: 2898-2910, 2016
The effect of mesoporous bioglass on osteogenesis and adipogenesis of osteoporotic BMSCs

This study evaluated the effect of mesoporous bioglass (MBG) dissolution on the differentiation of bone marrow mesenchymal stem cells (BMSCs) derived from either sham control or ovariectomized (OVX) rats. MBG was fabricated by evaporation-induced self-assembly method. Cell proliferation was tested by Cell Counting Kit-8 assay, and cytoskeletal morphology was observed by fluorescence microscopy. Osteogenic differentiation was evaluated by alkaline phosphatase (ALP) staining and activity, Alizarin Red staining, while adipogenic differentiation was assessed by Oil Red-O staining. Quantitative real-time PCR and Western blot analysis were taken to evaluate the expression of runt-related transcription factor 2 (Runx2) and proliferator-activated receptor-γ (PPARγ). We found that MBG dissolution (0, 25, 50, 100, 200 µg/mL) was nontoxic to BMSCs growth. Sham and OVX BMSCs exhibited the highest ALP activity in 50 µg/mL of MBG osteogenic dissolution, except that sham BMSCs in 100 µg/mL showed the highest ALP activity on day 14. Runx2 was significantly upregulated after 100 µg/mL of MBG stimulation in sham and OVX BMSCs for 7 and 14 days, except that 25 µg/mL showed highest upregulation effect on OVX BMSCs at day 7. PPARγ was downregulated after MBG stimulation. The protein level of Runx2 from the sham BMSCs group was significantly upregulated after lower doses (25 and 50 µg/mL) of MBG stimulation, whereas PPARγ was downregulated in the sham and OVX BMSCs group. Thus, both the osteogenic and adipogenic abilities of BMSCs were damaged under OVX condition. Moreover, lower concentration of MBG dissolution can promote osteogenesis but inhibit adipogenesis of the sham and OVX BMSCs
Differential magnesium implant corrosion coat formation and contribution to bone bonding.

Magnesium alloys are presently under investigation as promising biodegradable implant materials with osteoconductive properties. To study the molecular mechanisms involved, the potential contribution of soluble magnesium corrosion products to the stimulation of osteoblastic cell differentiation was examined. However, no evidence for the stimulation of osteoblast differentiation could be obtained when cultured mesenchymal precursor cells were differentiated in the presence of metallic magnesium or in cell culture medium containing elevated magnesium ion levels. Similarly, in soft tissue no bone induction by metallic magnesium or by the corrosion product magnesium hydroxide could be observed in a mouse model. Motivated by the comparatively rapid accumulation solid corrosion products physicochemical processes were examined as an alternative mechanism to explain the stimulation of bone growth by magnesium-based implants. During exposure to physiological solutions a structured corrosion coat formed on magnesium whereby the elements calcium and phosphate were enriched in the outermost layer which could play a role in the established biocompatible behavior of magnesium implants. When magnesium pins were inserted into avital bones, corrosion lead to increases in the pull out force, suggesting that the expanding corrosion layer was interlocking with the surrounding bone. Since mechanical stress is a well-established inducer of bone growth, volume increases caused by the rapid accumulation of corrosion products and the resulting force development could be a key mechanism and provide an explanation for the observed stimulatory effects of magnesium-based implants in hard tissue. © 2016 Wiley Periodicals, Inc. J Biomed Mater Res Part A: 105A: 697-709, 2017
Experimental and computational examination of anastellin (FnIII1c)-polymer interactions

Using a combination of experimental and computational approaches, the interaction between anastellin, a recombinant fragment of fibronectin, and representative biomaterial surfaces has been examined. The molecular interaction was directly quantified by atomic force microscope (AFM) based force spectroscopy, complemented by adsorption measurements using quartz crystal microbalance (QCM). It was found that the anastellin molecules facilitates a stronger adhesion on polyurethane films (72.0 pN nm-1) than on poly (methyl methacrylate) films (68.6 pN nm-1). This is consistent with the adsorption measurements of anastellin on the two polymeric surfaces, observed by QCM. Molecular dynamics simulations of the behaviour of anastellin on polyurethane in water solution were performed to rationalise the experimental data, and show that anastellin is capable of rapid adsorption to PU while its secondary structure is stable upon adsorption in water
The behavior of novel hydrophilic composite bone cements in simulated body fluids

Composite bone cements were formulated with bioactive glass (MgOOSiO2O3CaO !
P2O5) as the filler and hydrophilic matrix. The matrix was composed of a starch/cellulose acetate
blend (SCA) as the solid component and a mixture of methylmethacrylate/acrylic acid (MMA/AA)
as the liquid component. The curing parameters, mechanical properties, and bioactive behavior of
these composite cements were determined. The addition of up to 30 wt % of glass improved both
compressive modulus and yield strength and kept the maximum curing temperature at the same
value presented by a typical acrylic-based commercial formulation. The lack of a strongly bonded
interface (because no coupling agent was used) had important effects on the swelling and mechanical
properties of the novel bone cements. However, bone cements containing AA did not show a
bioactive behavior, because of the deleterious effect of this monomer on the calcium phosphate
precipitation on the polymeric surfaces. Formulations without AA were prepared with MMA or
2-hydroxyethyl methacrylate (HEMA) as the liquid component. Only these formulations could
form an apatite-like layer on their surface. These systems, therefore, are very promising: They are
bioactive, hydrophilic, partially degradable, and present interesting mechanical properties. This
combination of properties could facilitate the release of bioactive agents from the cement, allow
bone ingrowth in the cement, and induce a press-fitting effect, improving the interfaces with both
the prosthesis and the bone
Histology and ultrastructure of a tissue-engineered collagen meniscus before and after implantation

The collagen meniscus implant (CMI) is a tissue-engineering technique designed to stimulate regeneration of meniscus-like tissue in cases of irreparable tears or previous meniscectomy. CMI morphology was investigated before and after implantation by light microscopy, scanning electron microscopy (SEM), and transmission electron microscopy (TEM). In a case series biopsy specimens were harvested from four patients who underwent a second arthroscopic look 6 months after placement of the CMI. CMI sections appeared composed of parallel connective laminae of 10-30 mu m, connected by smaller bundles (5-10 mu m). This connective network formed lacunae with diameters between 40 and 60 mu m. At greater magnification, the walls of the lacunae demonstrated tightly packed and randomly distributed collagen fibrils, with diameters ranging from 73 to 439 nm. In the biopsy specimens, the lacunae were filled with connective tissue that contained newly formed vessels and fibroblast-like cells, presenting an abundant rough endoplasmic reticulum and several mitochondria. In the extracellular matrix, the collagen fibrils showed uniform diameters (126 nm +/- 32 nm). The original structure of CMI was still recognizable, and no inflammatory cells were detected within the implant. The morphological findings of this case series demonstrate that CMI provides a three-dimensional scaffold suitable for colonization by precursor cells and vessels and leading to the formation of a fully functional tissue
Microhardness and fracture toughness of dental materials by indentation method

The main objective of this study was to measure the fracture toughness of the human teeth enamel using the microindentation technique and to compare the results calculated from the equations developed for Palmqvist and radial-median cracks. Vickers microhardness measurements of dental ceramic (alumina) and human teeth were performed using indentation fracture method. The fracture toughness of enamel was calculated using different equations reported in the literature. Vickers microhardness of the sintered alumina specimen (98.8% theoretical density) was measured to be 14.92 GPa under 9.8N indentation load. Three equations based on the radial-median cracks were found to be applicable for the fracture toughness determination of the enamel. Results show that indentation fracture method is adequate to measure microhardness and fracture toughness of dental materials. However the calculation of fracture toughness depended on the nature of the cracks and also on the location of the indentation. Therefore, it is necessary to identify the crack profile and to select the appropriate equation for accurate fracture toughness values
Equivalences between refractive index and equilibrium water content of conventional and silicone hydrogel soft contact lenses from automated and manual refractometry

PURPOSE: The purpose of the present study was to develop mathematical relationships that allow obtaining equilibrium water content and refractive index of conventional and silicone hydrogel soft contact lenses from refractive index measures obtained with automated refractometry or equilibrium water content measures derived from manual refractometry, respectively. METHODS: Twelve HEMA-based hydrogels of different hydration and four siloxane-based polymers were assayed. A manual refractometer and a digital refractometer were used. Polynomial models obtained from the sucrose curves of equilibrium water content against refractive index and vice-versa were used either considering the whole range of sucrose concentrations (16-100% equilibrium water content) or a range confined to the equilibrium water content of current soft contact lenses ( approximately 20-80% equilibrium water content). RESULTS: Values of equilibrium water content measured with the Atago N-2E and those derived from the refractive index measurement with CLR 12-70 by the applications of sucrose-based models displayed a strong linear correlation (r(2) = 0.978). The same correlations were obtained when the models are applied to obtain refractive index values from the Atago N-2E and compared with those (values) given by the CLR 12-70 (r(2) = 0.978). No significantly different results are obtained between models derived from the whole range of the sucrose solution or the model limited to the normal range of soft contact lens hydration. CONCLUSIONS: Present results will have implications for future experimental and clinical research regarding normal hydration and dehydration experiments with hydrogel polymers, and particularly in the field of contact lenses.This study was supported in part by a grant from the Science and Technology Foundation (FCT) - Ministry of Science and Superior Education (MCES) under contract 8281/2002 from the European Social Funding granted to JMG-M
Strategies for the prevention of microbial biofilm formation on silicone rubber voice prostheses

Total laryngectomy, a surgical treatment for extensive cancer of larynx, which alters swallowing and respiration in patients, is followed up with a surgical voice restoration
procedure comprising tracheoesophageal puncture techniques with insertion of a ‘‘voice
prosthesis’’ to improve successful voice rehabilitation. However, microbial colonization is a major drawback of these devices. Antimicrobials are usually used to prevent the colonization of silicone rubber voice prostheses by microorganisms. However, long-term medication induces the development of resistant strains with all associated risks and the development of alternative prophylactic and therapeutic agents, including probiotics and biosurfactants, have been suggested. The inhibition of microbial growth on surfaces can also be achieved by several
other techniques involving the modification of physicochemical properties of the biomaterial
surface or the covalently binding of antimicrobial agents to the biomaterial surface. An overview of the different approaches investigated to date and future perspectives to reduce the frequent replacements of voice prostheses in laryngectomized patients through microbial
biofilm retardation is presented and discussed.Fundação para a Ciência e a Tecnologia (FCT
In vivo performance of antibiotic embedded electrospun PCL membranes for prevention of abdominal adhesions

The aim of this study was to prepare nonwoven materials from poly(-caprolactone) (PCL) and their antibiotic containing forms by electrospinning, so as to prevent postsurgery induced abdominal adhesions in rats. -Caprolactone was first polymerized by ring-opening polymerization, and then it was processed into matrices composed of nanofibers by electrospinning. A model antibiotic (Biteral®) was embedded within a group of PCL membranes. In the rat model, defects on the abdominal walls in the peritoneum were made to induce adhesion. The plain or antibiotic embedded PCL membranes were implanted on the right side of the abdominal wall. No membrane implantation was made on the left side of the abdominal wall that served as control. Macroscopical and histological evaluations showed that using these barriers reduces the extent, type, and tenacity of adhesion. The antibiotic embedded membranes significantly eliminated postsurgery abdominal adhesions, and also improved healing
Wrist arthroplasty; bone fixation, clinical development and mid to long term results

List of papers. The papers are removed from the thesis due to publisher restrictions.<br><br>

Paper 1: Reigstad O, Franke-Stenport V, Johansson CB, Wennerberg A, Røkkum M, Reigstad A. Improved bone ingrowth and fixation with a thin calcium phosphate coating intended for complete resorption. J Biomed Mater Res B Appl Biomater. 2007 Oct;83(1):9-15. <a href="http://dx.doi.org/10.1002/jbm.b.30762">doi:10.1002/jbm.b.30762</a><br><br>

Paper 2: Reigstad O, Johansson C, Stenport V, Wennerberg A, Reigstad A, Røkkum M. Different patterns of bone fixation with hydroxyapatite and resorbable CaP coatings in the rabbit tibia at 6, 12, and 52 weeks. J Biomed Mater Res B Appl Biomater. 2011 Oct;99(1):14-20. <a href="http://dx.doi.org/10.1002/jbm.b.31866">doi:10.1002/jbm.b.31866</a><br><br>

Paper 3: Reigstad A, Reigstad O, Grimsgaard C, Røkkum M. New concept for total wrist replacement. J Plast Surg Hand Surg. 2011 Jun;45(3):148-56. <a href="http://dx.doi.org/10.3109/2000656X.2011.579720">doi:10.3109/2000656X.2011.579720</a><br><br>

Paper 4: Reigstad O, Lütken T, Grimsgaard C, Bolstad B, Thorkildsen R, Røkkum M. Promising 1-6 years results with the Motec wrist arthroplasty in SNAC and SLAC patients. J Bone and Joint Surg Br 2012 Nov;94(11):1540-5. <a href="http://dx.doi.org/10.1302/0301-620X.94B11.30130">doi:10.1302/0301-620X.94B11.30130</a
Strontium-substituted apatite coating grown on Ti6Al4V substrate through biomimetic synthesis

During the last few years Strontium has been shown to have beneficial effects when
incorporated at certain doses in bone by stimulating bone formation. It is believed that its
presence locally at the interface between an implant and bone will enhance osteointegration
and therefore, ensure the longevity of a joint prosthesis. In this study we explore the possibility
of incorporating Sr into nano-apatite coatings prepared by a solution-derived process
according to an established biomimetic methodology for coating titanium based implants. The
way this element is incorporated in the apatite structure and its effects on the stereochemistry
and morphology of the resulting apatite layers was investigated, as well as its effect in the
mineralization kinetics. By using the present methodology it was possible to incorporate
increasing amounts of Sr in the apatite layers. Sr was found to incorporate in the apatite layer
through a substitution mechanism by replacing Ca in the apatite lattice. The presence of Sr in
solution induced an inhibitory effect on mineralization, leading to a decrease in the thickness
of the mineral layers. The obtained Sr-substituted biomimetic coatings presented a bone-like
structure similar to the one found in the human bone and therefore, are expected to enhance
bone formation and osteointegration
Qualitative and quantitative characterization of the in vitro dehydration process of hydrogel contact lenses

PURPOSE: To investigate the in vitro dehydration process of conventional hydrogel and silicone-hydrogel contact lens materials. METHODS: Eight conventional hydrogel and five silicone-hydrogel contact lenses were dehydrated under controlled environmental conditions on an analytical balance. Data were taken at 1-min intervals and dehydration curves of cumulative dehydration (CD), valid dehydration (VD), and dehydration rate (DR) were obtained. Several quantitative descriptors of the dehydration process were obtained by further processing of the information. RESULTS: Duration of phase I (r(2) = 0.921), CD at end of phase I (r(2) = 0.971), time to achieve a DR of -1%/min (r(2) = 0.946) were strongly correlated with equilibrium water content (EWC) of the materials. For each individual sample, the VD at different time intervals can be accurately determined using a 2nd order regression equation (r(2) > 0.99 for all samples). The first 5 min of the dehydration process show a relatively uniform average CD of about -1.5%/min. After that, there was a trend towards higher average CD for the following 15 min as the EWC of the material increases (r(2) = 0.701). As a consequence, average VD for the first 5 min displayed a negative correlation with EWC (r(2) = 0.835), and a trend towards uniformization among CL materials for the following periods (r(2) = 0.014). Overall, silicone-hydrogel materials display a lower dehydration, but this seems to be primarily due to their lower EWC. CONCLUSIONS: DR curves under the conditions of the present study can be described as a three-phase process. Phase I consists of a relatively uniform DR with a duration that ranges from 10 to almost 60 min and is strongly correlated with the EWC of the polymer as it is the CD during this phase. Overall, HEMA-based hydrogels dehydrate to a greater extent and faster than silicone-hydrogel materials. There are differences in water retention between lenses of similar water content and thickness that should be further investigated
Chitosan coated alginate beads containing poly(N-isopropylacrylamide) for dual-stimuli-responsive drug release

Chitosan coated alginate beads containing poly(N-isopropylacrylamide) (PNIPAAM),
were prepared to be used as a controlled pH/temperature sensitive drug delivery
system with improved encapsulation efficiency and delayed release rate. The studied beads
were characterized by differential scanning calorimetry, scanning electron microscopy, and
Fourier transform infrared spectroscopy. Water uptake and release studies using indomethacin
as a model drug were also performed. The drug loading efficiency of the beads with the
polyelectrolyte complex coating is significantly higher (84%) than that of the uncoated ones
(74%). The equilibrium swelling of the developed materials was found to be pH- and thermoresponsive.
For all the conditions it was found that the release profile was slower for the coated
beads, indicating that the polyelectrolyte complex coating could slow down the release rate
effectively. These results suggest that the studied smart system has potential to be used as an effective pH/temperature sustainable delivery system for biomedical applications
Comparative study of silicone-hydrogel contact lenses Surfaces before and after wear using atomic force microscopy

Purpose: The aim of this study was to analyze surface changes of three silicone-hydrogel contact lenses after daily wear. The lenses used in this study were balafilcon A, lotrafilcon B (both surface-treated), and galyfilcon A (non surface-treated). Methods: To understand how and where proteins, lipids, and other contaminants change contact lenses, surface roughness was assessed through Atomic Force Microscopy Tapping ModeTM. Roughness parameters were Mean Surface roughness (Ra), Mean-square-roughness (Rq), and Maximum roughness (Rmax). The surface topography of unworn and worn lenses was also mapped in great detail. Results: Contact lenses roughness parameters exhibited different values before and after wear and the surface appearance also changed. After wear, balafilcon A and galyfilcon A showed a significant increase on surface roughness parameters, being this increase more accentuated to galyfilcon A. In lotrafilcon B materials no significant changes were observed with wear. Conclusions: The present study suggests that surface treatment of silicone-hydrogel contact lenses can play a role in the prevention of a significant increase in roughness, and contribute to the better clinical tolerance of these lenses.University of PortoIBM
Effects of compaction pressure and particle shape on the porosity and compression mechanical properties of sintered Ti6Al4V powder compacts for hard tissue implantation

Sintered Ti6Al4V powder compacts potentially to be used in implant applications were prepared using commercially available spherical and angular powders (100-200 mum) within the porosity range of 34-54%. Cylindrical green powder compacts were cold compacted at various pressures and then sintered at 1200 degrees C for 2 h. The final percent porosity and mean pore sizes were determined as functions of the applied compaction pressure and powder type. The mechanical properties were investigated through compression testing. Results have shown that yield strength of the powder compacts of 40-42% porosity was comparable with that of human cortical bone. As compared with previously investigated Ti powder compacts, Ti6Al4V powder compacts showed higher strength at similar porosity range. Microscopic observations on the failed compact samples revealed that failure occurred primarily by the separation of interparticle bond regions in the planes 45 degrees to the loading axis. 

Effects of compaction pressure and particle shape on the porosity and compression mechanical properties of sintered Ti6Al4V powder compacts for hard tissue implantation.Technology Development Foundation of Turkey (TTGV); contract grant number: TTGV-102/T1