Influence of steel implant surface microtopography on soft and hard tissue integration.

After implantation of an internal fracture fixation device, blood contacts the surface, followed by protein adsorption, resulting in either soft-tissue adhesion or matrix adhesion and mineralization. Without protein adsorption and cell adhesion under the presence of micro-motion, fibrous capsule formation can occur, often surrounding a liquid filled void at the implant-tissue interface. Clinically, fibrous capsule formation is more prevalent with electropolished stainless steel (EPSS) plates than with current commercially pure titanium (cpTi) plates. We hypothesize that this is due to lack of micro-discontinuities on the standard EPSS plates. To test our hypothesis, four EPSS experimental surfaces with varying microtopographies were produced and characterized for morphology using the scanning electron microscope, quantitative roughness analysis using laser profilometry and chemical analysis using X-ray photoelectron spectroscopy. Clinically used EPSS (smooth) and cpTi (microrough) were included as controls. Six plates of each type were randomly implanted, one on both the left and right intact tibia of 18 white New Zealand rabbits for 12 weeks, to allow for a surface interface study. The results demonstrate that the micro-discontinuities on the upper surface of internal steel fixation plates reduced the presence of liquid filled voids within soft-tissue capsules. The micro-discontinuities on the plate under-surface increased bony integration without the presence of fibrous tissue interface. These results support the hypothesis that the fibrous capsule and the liquid filled void formation occurs mainly due to lack of micro-discontinuities on the polished smooth steel plates and that bony integration is increased to surfaces with higher amounts of micro-discontinuities. © 2017 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater, 106B: 705-715, 2018.

Sclerostin Antibody Therapy for the Treatment of Osteoporosis: Clinical Prospects and Challenges.

It is estimated that over 200 million adults worldwide have osteoporosis, a disease that has increasing socioeconomic impact reflected by unsustainable costs associated with disability, fracture management, hospital stays, and treatment. Existing therapeutic treatments for osteoporosis are associated with a variety of issues relating to use, clinical predictability, and health risks. Consequently, additional novel therapeutic targets are increasingly sought. A promising therapeutic candidate is sclerostin, a Wnt pathway antagonist and, as such, a negative regulator of bone formation. Sclerostin antibody treatment has demonstrated efficacy and superiority compared to other anabolic treatments for increasing bone formation in both preclinical and clinical settings. Accordingly, it has been suggested that sclerostin antibody treatment is set to achieve market approval by 2017 and aggressively compete as the gold standard for osteoporotic treatment by 2021. In anticipation of phase III trial results which may potentially signify a significant step in achieving market approval here, we review the preclinical and clinical emergence of sclerostin antibody therapies for both osteoporosis and alternative applications. Potential clinical challenges are also explored as well as ongoing developments that may impact on the eventual clinical application of sclerostin antibodies as an effective treatment of osteoporosis.

Translational diffusion of water inside hydrophobic carbon micropores studied by neutron spectroscopy and molecular dynamics simulation.

When water molecules are confined to nanoscale spacings, such as in the nanometer-size pores of activated carbon fiber (ACF), their freezing point gets suppressed down to very low temperatures (∼150K), leading to a metastable liquid state with remarkable physical properties. We have investigated the ambient pressure diffusive dynamics of water in microporous Kynol ACF-10 (average pore size ∼11.6Å, with primarily slit-like pores) from temperature T=280 K in its stable liquid state down to T=230 K into the metastable supercooled phase. The observed characteristic relaxation times and diffusion coefficients are found to be, respectively, higher and lower than those in bulk water, indicating a slowing down of the water mobility with decreasing temperature. The observed temperature-dependent average relaxation time 〈τ〉 when compared to previous findings indicate that it is the width of the slit pores-not their curvature-that primarily affects the dynamics of water for pore sizes larger than 10 Å. The experimental observations are compared to complementary molecular dynamics simulations of a model system, in which we studied the diffusion of water within the 11.6 Å gap of two parallel graphene sheets. We find generally a reasonable agreement between the observed and calculated relaxation times at the low momentum transfer Q(Q≤0.9Å(-1)). At high Q, however, where localized dynamics becomes relevant, this ideal system does not satisfactorily reproduce the measurements. Consequently, the simulations are compared to the experiments at low Q, where the two can be best reconciled. The best agreement is obtained for the diffusion parameter D associated with the hydrogen-site when a representative stretched exponential function, rather than the standard bimodal exponential model, is used to parametrize the self-correlation function I(Q,t).

Evaluation of Cartilage Repair by Mesenchymal Stem Cells Seeded on a PEOT/PBT Scaffold in an Osteochondral Defect.

The main objective of this study was to evaluate the effectiveness of a mesenchymal stem cell (MSC)-seeded polyethylene-oxide-terephthalate/polybutylene-terephthalate (PEOT/PBT) scaffold for cartilage tissue repair in an osteochondral defect using a rabbit model. Material characterisation using scanning electron microscopy indicated that the scaffold had a 3D architecture characteristic of the additive manufacturing fabrication method, with a strut diameter of 296 ± 52 µm and a pore size of 512 ± 22 µm × 476 ± 25 µm × 180 ± 30 µm. In vitro optimisation revealed that the scaffold did not generate an adverse cell response, optimal cell loading conditions were achieved using 50 µg/ml fibronectin and a cell seeding density of 25 × 10(6) cells/ml and glycosaminoglycan (GAG) accumulation after 28 days culture in the presence of TGFß3 indicated positive chondrogenesis. Cell-seeded scaffolds were implanted in osteochondral defects for 12 weeks, with cell-free scaffolds and empty defects employed as controls. On examination of toluidine blue staining for chondrogenesis and GAG accumulation, both the empty defect and the cell-seeded scaffold appeared to promote repair. However, the empty defect and the cell-free scaffold stained positive for collagen type I or fibrocartilage, while the cell-seeded scaffold stained positive for collagen type II indicative of hyaline cartilage and was statistically better than the cell-free scaffold in the blinded histological evaluation. In summary, MSCs in combination with a 3D PEOT/PBT scaffold created a reparative environment for cartilage repair.

A phenotypic comparison of osteoblast cell lines versus human primary osteoblasts for biomaterials testing.

Immortalized cell lines are used more frequently in basic and applied biology research than primary bone-derived cells because of their ease of access and repeatability of results in experiments. It is clear that these cell models do not fully resemble the behavior of primary osteoblast cells. Although the differences will affect the results of biomaterials testing, they are not clearly defined. Here, we focused on comparing proliferation and maturation potential of three osteoblast cell lines, SaOs2, MG-63, and MC3T3-E1 with primary human osteoblast (HOb) cells to assess their suitability as in vitro models for biomaterials testing. We report similarities in cell proliferation and mineralization between primary cells and MC3T3-E1. Both, SaOs2 and MG-63 cells demonstrated a higher proliferation rate than HOb cells. In addition, SaOs2, but not MG-63, cells demonstrated similar ALP activity, mineralization potential and gene regulation to HOb's. Our results demonstrate that despite SaOs-2, MG63, and MC3T3 cells being popular choices for emulating osteoblast behavior, none can be considered appropriate replacements for HOb's. Nevertheless, these cell lines all demonstrated some distinct similarities with HOb's, thus when applied in the correct context are a valuable in vitro pilot model of osteoblast functionality, but should not be used to replace primary cell studies.

Bacteriophage ecology in a commercial cucumber fermentation.

To reduce high-salt waste from cucumber fermentations, low-salt fermentations are under development. These fermentations may require the use of starter cultures to ensure normal fermentations. Because potential phage infection can cause starter culture failure, it is important to understand phage ecology in the fermentations. This study investigated the phage ecology in a commercial cucumber fermentation. Brine samples taken from a fermentation tank over a 90-day period were plated onto deMan-Rogosa-Sharpe agar plates. A total of 576 lactic acid bacterial isolates were randomly selected to serve as potential hosts for phage isolation. Filtered brine served as a phage source. Fifty-seven independent phage isolates were obtained, indicating that 10% of the bacterial isolates were sensitive to phage attack. Phage hosts include Lactobacillus brevis (67% of all hosts), Lactobacillus plantarum (21%), Weissella paramesenteroides, Weissella cibaria, and Pediococcus ethanolidurans. Nearly 50% of phages were isolated on day 14, and the majority of them attacked L. brevis. Some phages had a broad host range and were capable of infecting multiple hosts in two genera. Other phages were species specific or strain specific. About 30% of phage isolates produced turbid pinpoint plaques or only caused reduced cell growth on the bacterial lawns. Six phages with distinct host ranges were characterized. The data from this study showed that abundant and diverse phages were present in the commercial cucumber fermentation, which could cause significant mortality to the lactic acid bacteria population. Therefore, a phage control strategy may be needed in low-salt cucumber fermentations.

In search of an osteoblast cell model for in vitro research.

The process of bone formation, remodelling and healing involves a coordinated action of various cell types. Advances in understanding the biology of osteoblast cells during these processes have been enabled through the use of various in vitro culture models from different origins. In an era of intensive bone tissue engineering research, these cell models are more and more often applied due to limited availability of primary human osteoblast cells. While they are a helpful tool in developing novel therapies or biomaterials; concerns arise regarding their phenotypic state and differences in relation to primary human osteoblast cells. In this review we discuss the osteoblastic development of some of the available cell models; such as primary human, rat, mouse, bovine, ovine and rabbit osteoblast cells; as well as MC3T3-E1, MG-63 and SaOs-2 cell lines, together with their advantages and disadvantages. Through this, we provide suggestions on the selection of the appropriate and most relevant osteoblast model for in vitro studies, with specific emphasis on cell-material based studies.

The cell-surface interaction.

The realm of surface-dependent cell and tissue responses is the foundation of orthopaedic-device-related research. However, to design materials that elicit specific responses from tissues is a complex proposition mainly because the vast majority of the biological principles controlling the interaction of cells with implants remain largely ambiguous. Nevertheless, many surface properties, such as chemistry and topography, can be manipulated in an effort to selectively control the cell-material interaction. On the basis of this information there has been much research in this area, including studies focusing on the structure and composition of the implant interface, optimization of biological and chemical coatings and elucidation of the mechanisms involved in the subsequent cell-material interactions. Although a wealth of information has emerged, it also advocates the complexity and dynamism of the cell-material interaction. Therefore, this chapter aims to provide the reader with an introduction to the basic concepts of the cell-material interaction and to provide an insight into the factors involved in determining the cell and tissue response to specific surface features, with specific emphasis on surface microtopography.

The use of titanium and stainless steel in fracture fixation.

The use of metal in fracture fixation has demonstrated unrivalled success for many years owing to its high stiffness, strength, biological toleration and overall reliable function. The most prominent materials used are electropolished stainless steel and commercially pure titanium, along with the more recent emergence of titanium alloys. Despite the many differences between electropolished stainless steel and titanium, both materials provide a relatively predictable clinical outcome, and offer similar success for fulfilling the main biomechanical and biological requirements of fracture fixation despite distinctive differences in implant properties and biological responses. This article explores these differences by highlighting the limitations and advantages of both materials, and addresses how this translates to clinical success.

The role of surface microtopography in the modulation of osteoblast differentiation.

The osteoinductive and conductive capabilities of commercially pure titanium and its alloys is well documented, as is their ability to provide long-term stability for permanent implantable devices. Fracture fixation in paediatric and trauma patients generally requires transient fixation after which the implant becomes redundant and requires removal. Removal can be complicated due to excessive bony over-growth which is encouraged by the standard micro-rough implant surface. We have shown in vivo that removal related morbidity can be significantly reduced with surface polishing, a technique which reduces the micro-roughness of clinically available materials. However, tissue integration at the bone-implant interface requires activation of key regulatory pathways which influences osteoblastic differentiation and maturation therefore we do not believe this effect to be purely mechanical. To elucidate potential mechanisms by which surface polishing exerts its effect on bone regeneration this study assessed in vitro the effect of surface polishing commercially pure titanium on cell growth, morphology and on the regulation of core binding factor 1, osterix, collagen I, alkaline phosphatase, bone sialoprotein and osteocalcin for primary rat calvarial osteoblasts. Results indicate that polishing differentially influences osteoblast differentiation in a surface dependent manner and that these changes are potentially linked to surface dependent morphology, but not to differences in cell proliferation.

Surface polishing positively influences ease of plate and screw removal.

Difficulties removing temporary fracture fixation devices due to excessive bony on-growth results in extended surgical time leading to excessive blood loss, debris contamination and potentially refracture. Commercially available locking plates and screws are manufactured for clinics with a micro-rough surface, which contributes to the excessive bony on-growth reported. We have applied polishing technology to commercially pure titanium locking compression plates (LCP) and titanium-6%aluminium-7%niobium (TAN) plates and screws to assess if it can alleviate problems with strong bony overgrowth. Samples were implanted for 6, 12 and 18 months in a bilateral sheep tibia non fracture model and assessed for screw removal torque, percentage of bone contact and tissue-material response. Both electropolishing (p=0.001) and paste polishing (p=0.010) of TAN screws significantly reduced the mean torque required for removal compared to their micro-rough counterparts. This was accompanied by a trend for a lower percentage of bone contact for polished screws. This difference in bone contact was significant for paste polished TAN screws (p<0.001 parallel but not electropolished TAN screws (p=0.066). Ex vivo, soft tissue removal was much easier (approximately five minutes) for polished constructs, which was difficult and at least four times longer for standard micro-rough constructs. We suggest that polishing of locked plate/screw systems will improve ease of removal and reduce implant related removal complications encountered due to excessive strong bony on-growth while maintaining biocompatibility and implant stability. Future studies aim to assess the potential of this technology in the next level of complication, a fracture model.

An in vivo evaluation of surface polishing of TAN intermedullary nails for ease of removal.

Fractures of the tibia and femoral diaphysis are commonly repaired by intra-medullary (IM) nailing. Currently IM nails are available in either electropolished stainless steel (SS) or in Titanium-Aluminium-Niobium (TAN). After healing, removal of the nails still is common but removal of TAN IM nails often has complications whereas SS IM nails of the same design are less often associated with problems. We believe the differences in removal are due to the ability of TAN to promote strong bone on-growth. We have previously shown in vivo that polishing cortical screws reduces removal torque and the percentage of bone-implant contact. Therefore, we postulate that bony on-growth onto IM nails can be reduced by means of surface polishing, for ease of removal. Here we aim to compare the pull-out forces for removal of standard TAN (TAN-S) compared to experimental paste polished TAN (TAN-PP) IM nails from a bilateral non-fracture sheep tibia model after 12 months implantation. Histological analysis was also performed to assess tissue on-growth to the nails. We show that polishing significantly reduces (p=0.05) the extraction force required for TAN IM nail removal. This effect in part is attributable to the distinct tissue-material reaction produced. For TAN-S nails direct bone contact was observed while for TAN-PP nails a fibrous tissue interface was noted. Since TAN is preferred over SS for IM nailing due to superior biocompatibility and mechanical properties, we believe these findings could be used to recommend changes to current surface technologies of intramedullary nails to reduce complications seen with nail removal especially in rapidly growing bone in children.

An in vivo evaluation of the biocompatibility of anodic plasma chemical (APC) treatment of titanium with calcium phosphate.

Implant loosening is an unresolved complication associated with prosthetics. Previous studies report improved osseointegration with hydroxyapatite (HA) or tri-calcium phosphate coatings. Unfortunately, the brittleness and low strength of these coatings in adhesion to the implant or internal cohesion is problematic, restricting their use. Anodic plasma-chemical (APC) treatment, an advanced anodisation method, allows for porous oxide layer formation with incorporation of calcium and phosphate directly into the oxide. This produces superior adhesive strength than a conventional coating of calcium phosphate offering potential for long-term osseointegration. Although the cytocompatibility of several APC treatments have been previously shown, this study was the first to investigate the biocompatibility and osteoconductivity of APC surfaces in vivo when compared with standard HA coated and noncoated commercially pure titanium implant cortical screws. Sample screws were implanted in female Swiss alpine sheep for 12 weeks. Bone remodelling in situ, differences in bone apposition resulting in cortical thickening as well as peak removal torque measurements were assessed. We found no significant differences between the tested coatings and no delamination was observed with any of the APC-treated surfaces. The results suggest that APC-treated samples have similar biological performance to HA-coated screws. In our opinion, APC treatment, which also has superior binding strength to the base metal compared with standard HA coatings as well as similar biocompatibility as shown here, holds great potential for biomedical applications. Now that the in vivo biocompatibility has been proven, the work is being extended to more challenging in vivo models.

Determination of 5-log pathogen reduction times for heat-processed, acidified vegetable brines.

Recent outbreaks of acid-resistant food pathogens in acid foods, including apple cider and orange juice, have raised concerns about the safety of acidified vegetable products. We determined pasteurization times and temperatures needed to assure a 5-log reduction in the numbers of Escherichia coli O157:H7, Listeria monocytogenes, and Salmonella strains in acidified cucumber pickle brines. Cocktails of five strains of each pathogen were (separately) used for heat-inactivation studies between 50 and 60 degrees C in brines that had an equilibrated pH value of 4.1. Salmonella strains were found to be less heat resistant than E. coli O157:H7 or L. monocytogenes strains. The nonlinear killing curves generated during these studies were modeled using a Weibull function. We found no significant difference in the heat-killing data for E. coli O157:H7 and L. monocytogenes (P = 0.9709). The predicted 5-log reduction times for E. coli O157:H7 and L. monocytogenes were found to fit an exponential decay function. These data were used to estimate minimum pasteurization times and temperatures needed to ensure safe processing of acidified pickle products and show that current industry pasteurization practices offer a significant margin of safety.

Independent effects of acetic acid and pH on survival of Escherichia coli in simulated acidified pickle products.

Our objective was to determine the effects of organic acids and pH on the rate at which selected strains of Escherichia coli O157:H7 die in acid solutions representative of acidified pickle products (pH < 4.6). We used gluconic acid/sodium gluconate (pKa = 3.7) as a noninhibitory buffer to maintain pH at selected values in the absence of other organic acids. This was possible because we found that the inhibitory effects of this acid on E. coli strains at pH 3.1 were independent of acid concentration over a range of 2 to 200 mM. By this method, the lethal effects of acetic acid solutions (100 to 400 mM) at selected pH values between 3.1 and 4.1 were compared with the effects of pH alone (as determined using gluconate buffer). We found D-values were two- to fourfold lower with acetic acid compared with the effect of pH alone for simulated pickle brines in this pH range. Glutamic acid, an amino acid that is known to enhance acid resistance in E. coli and is a component of pickle brines, protected the E. coli strains from the specific effects of acetic acid.

Getting nurses involved: use of existing databases for pediatric trauma research.

Nurses are strategically positioned to contribute to the research base of practice in pediatric trauma care. Nurses who are new to research and feel burdened by the time commitment for data collection may consider analyzing existing data from records and registries. Much of the published research in pediatric trauma and critical care is the result of descriptive studies that have had an impact at all phases of trauma care. The analysis of existing data saves time for the researcher and avoids some of the ethical questions and concerns for informed consent with this vulnerable patient population. Nurses can make an important contribution to the knowledge base and evidence-based care for injured children.

Florida's bicycle helmet law and a bicycle safety educational program: did they help?

INTRODUCTION: This research studied the effectiveness of Florida's mandatory helmet law for children and a community bicycle safety campaign promoting helmet use. Children's use of helmets before and after the law's enactment and the type and extent of head injuries sustained in bicycle crashes were evaluated. METHODS: The trauma and medical records from Broward General Medical Center's Pediatric Referral Trauma Center provided demographic data, injury severity scores, and information on the type and extent of head injuries sustained. Data were compared using independent sample t tests and Pearson chi(2) statistics with.05 as the significance level. RESULTS: Each group consisted of 72 children, predominantly 7- to 12-year-old boys. Known helmet use rose from 5.6% to 20.8%, with children aged 10 to 12 years having the greatest increase in helmet use (27%). Helmet use rose in urban and suburban areas. Changes in the type and extent of head injuries were mixed. Injury severity scores were higher for nonhelmeted children in the after-law group. DISCUSSION: Although helmet use increased, especially among the 7- to 12-year-olds targeted during the bicycle safety campaigns, bicycle helmet use remains too low, and nonhelmeted children continue to have a higher risk for serious injuries. Community bicycle safety programs that promote helmet use remain an important adjunct to mandatory helmet use laws.

Motor vehicle crashes and positive toxicology screens in adolescents and young adults.

The purpose of this study was to identify and describe the outcome of motor vehicle crashes for adolescents and young adults with positive toxicology screens. A retrospective design was used to collect data for 134 subjects ranging in age from 15 to 25 at an urban Level II trauma center. Outcomes related to sex, age, injury-severity score, length of stay, and hospital cost were analyzed using multiple regression, and the relationship was significant (p < .0001). Spearman's correlation analysis resulted in a significant relationship between survival outcome, injury severity, discharge, and hospital cost (p < .05).

The prostacyclin receptor is isoprenylated. Isoprenylation is required for efficient receptor-effector coupling.

The prostacyclin receptor (IP), a G protein-coupled receptor, mediates the actions of the prostanoid prostacyclin and its mimetics. IPs from a number of species each contain identically conserved putative isoprenylation CAAX motifs, each with the sequence CSLC. Metabolic labeling of human embryonic kidney (HEK) 293 cells stably overexpressing the hemagluttinin epitope-tagged IP in the presence of [(3)H]mevalonolactone established that the mouse IP is isoprenylated. Studies involving in vitro assays confirmed that recombinant forms of the human and mouse IP are modified by carbon 15 farnesyl isoprenoids. Disruption of isoprenylation, by site-directed mutagenesis of Cys(414) to Ser(414), within the CAAX motif, abolished isoprenylation of IP(SSLC) both in vitro and in transfected cells. Scatchard analysis of the wild type (IP) and mutant (IP(SSLC)) receptor confirmed that each receptor exhibited high and low affinity binding sites for [(3)H]iloprost, which were not influenced by receptor isoprenylation. Whereas stable cell lines overexpressing IP generated significant agonist (iloprost and cicaprost)-mediated increases in cAMP relative to nontransfected cells, cAMP generation by IP(SSLC) cells was not significantly different from the control, nontransfected HEK 293 cells. Moreover, co-expression of the alpha (alpha) subunit of Gs generated significant augmentations in cAMP by IP but not by IP(SSLC) cells. Whereas IP also demonstrated significant, dose-dependent increases in [Ca(2+)](i) in response to iloprost or cicaprost compared with the nontransfected HEK 293 cells, mobilization of [Ca(2+)](i) by IP(SSLC) was significantly impaired. Co-transfection of cells with either Galpha(q) or Galpha(11) resulted in significant augmentation of agonist-mediated [Ca(2+)](i) mobilization by IP cells but not by IP(SSLC) cells or by the control, HEK 293 cells. In addition, inhibition of isoprenylation by lovastatin treatment significantly reduced agonist-mediated cAMP generation by IP in comparison to the nonisoprenylated beta(2) adrenergic receptor or nontreated cells. Hence, isoprenylation of IP does not influence ligand binding but is required for efficient coupling to the effectors adenylyl cyclase and phospholipase C.