A comparison of anesthetic protective barriers for the management of COVID-19 pediatric patients.

BACKGROUND: Barrier techniques, such as plastic sheets or intubation boxes, are purported to offer additional protection for healthcare workers. AIMS: To assess the functionality, perceived safety, droplet protection, and aerosol protection of several barrier techniques. METHODS: Firstly, a simulation study with 12 different laryngoscopists was conducted to assess the time taken to perform an intubation (via direct laryngoscopy, via video laryngoscopy, and via a bougie) with four different barrier techniques (personal protective equipment only, a plastic sheet, a tented plastic sheet, and an intubation box). Secondly, a cough at the time of intubation was simulated using ultraviolet dye to assess the spread of droplets; and thirdly, smoke was used to assess the spread of aerosols. RESULTS: Intubation time using the box was noninferior to using no barrier. Based on subjective ratings by the laryngoscopists, the most functional technique was no barrier followed by the intubation box, then the tented sheet, and then the plastic sheet. The technique that conferred the highest feeling of safety to the laryngoscopists was the intubation box, followed by the tented sheet, then no barrier, and then the plastic sheet. All the barriers prevented the ultraviolet dye contaminating the head and torso of the laryngoscopist. Smoke remained within the intubation box if plastics sheets were used to cover the openings and suction was ineffective at clearing it. With no barrier in place, smoke was effectively cleared away from the patient in a theater with laminar flow but tended to spread up toward the laryngoscopist in a room without laminar flow. CONCLUSIONS: A well-designed intubation box is an effective barrier against droplets and is noninferior to no barrier in relation to intubation time. However, a box interferes with laminar flow in theaters with formal ventilation systems and may result in accumulation of aerosols if it is completely enclosed.

Gloss Retention on Enamel and Resin Composite Surfaces After Brushing Teeth with Commercial and Modified Dentifrices.

OBJECTIVES: We examined the surface gloss and roughness of a dental composite and human enamel after brushing with a new bioactive glass (BCF201) additive designed to treat dentine hypersensitivity. METHODS: We prepared 2 cohorts of samples: a resin-based composite (RBC) and human enamel. Each cohort received 20 000 brushing cycles with Colgate Optic White Enamel (Colgate Optic), Sensodyne Whitening Repair and Protect (Sensodyne), Colgate Enamel Health Sensitivity Relief (Colgate-EN) with and without BCF201 added or Germiphene Gel 7 HT (Gel 7) with and without BCF201 added. The average gloss and roughness of the enamel and RBC surfaces were measured before brushing and after 20 000 back-and-forth brushing cycles. A linear regression function was applied to the gloss results, and the data were analyzed using ANOVA and a Tukey post-hoc test (α = 0.05). RESULTS: After 20 000 brushing cycles, the control (Gel 7) had no significant effect on the gloss or roughness of the RBC. However, the choice of dentifrice had a significant effect on both gloss and roughness (p < 0.001). With respect to RBC, after brushing, surface roughness was ranked from smoothest to roughest: Gel 7 = Gel 7 plus BCF201 > Colgate-EN plus BCF201 = Colgate Optic = Colgate-EN > Sensodyne. With respect to enamel, the smoothest to the roughest surfaces after brushing were: Gel 7 plus BCF201 = Sensodyne = Colgate-EN plus BCF201 > Gel 7 = Colgate Optic = Colgate-EN. CONCLUSION: The bioactive glass additive had no adverse effect on the surface roughness or gloss of human enamel or RBC. SIGNIFICANCE: The addition of BCF201 appears to have a polishing effect on RBC and enamel and reduced the abrasive effects of Colgate-EN on RBC and enamel.

Effect of cellulose nanowhiskers on surface morphology, mechanical properties, and cell adhesion of melt-drawn polylactic Acid fibers.

Polylactic acid (PLA) fibers were produced with an average diameter of 11.2 (± 0.9) µm via a melt-drawing process. The surface of the PLA fibers was coated with blends of cellulose nanowhiskers (CNWs) (65 to 95 wt %) and polyvinyl acetate (PVAc). The CNWs bound to the smooth PLA fiber surface imparted roughness, with the degree of roughness depending on the coating blend used. The fiber tensile modulus increased 45% to 7 GPa after coating with 75 wt % CNWs compared with the uncoated PLA fibers, and a significant increase in the fiber moisture absorption properties at different humidity levels was also determined. Cytocompatibility studies using NIH-3T3 mouse fibroblast cells cultured onto CNWs-coated PLA surface revealed improved cell adhesion compared with the PLA control, making this CNW surface treatment applicable for biomedical and tissue engineering applications. Initial studies also showed complete cell coverage within 2 days.

State of the Art Review for Titanium Fluorine Glasses and Glass Ceramics.

Titanium (Ti) and fluorine (F) have the potential to provide a variety of desirable physical, chemical, mechanical, and biological properties applicable to a broad range of indications. Consequently, Ti- and F-containing glasses and glass ceramics are currently under investigation for use in nuclear, optical, electrochemical, dental, and industrial fields. Accordingly, significant interest exists with respect to understanding the individual and interaction effects that these elements have on material structure and properties to support the accelerated design, development, and deployment of these materials. This review aims to serve as a foundational reference across multiple disciplines, highlighting the fundamental properties and versatility of Ti- and F-containing glasses and glass ceramics. By consolidating our current knowledge of these materials, this broad overview will identify areas in which we can further our understanding to support the a priori prediction and effective design of these systems. Finally, this paper will introduce the potential to improve material design by integrating experimentation, modelling, and computational approaches in a manner commensurate with the principles of the Materials Genome Initiative.

Inside the Borate Anomaly: Leveraging a Predictive Modelling Approach to Navigate Complex Composition-Structure-Property Relationships in Oxyhalide Borate Glasses.

This study employs a systematic and predictive modelling approach to investigate the structure and properties of multi-component borate glasses. In particular, this work is focused on understanding the individual and interaction effects of multiple constituents on several material properties. By leveraging advanced modeling techniques, this work examines how the inclusion and variation of B2O3, CaF2, TiO2, ZnO, and Na2CO3 influence the glass network, with particular attention to modifier fractions ≥ 30 mol%. This research addresses the gap in knowledge regarding the complex behavior of borate glasses in this high modifier fraction range, known as the borate anomaly, where prediction of glass structure and properties becomes particularly challenging. The use of a design of mixtures (DoM) approach facilitated the generation of polynomial equations indicating the influence of mixture components on various responses, enabling the prediction and optimization of glass properties over broad compositional ranges despite being within the anomalous region. This methodical approach not only advances our understanding of borate glass systems but also underscores the importance of predictive modelling in the accelerated design and development of novel glass materials for diverse applications.

Engineering upper hinge improves stability and effector function of a human IgG1.

Upper hinge is vulnerable to radical attacks that result in breakage of the heavy-light chain linkage and cleavage of the hinge of an IgG1. To further explore mechanisms responsible for the radical induced hinge degradation, nine mutants were designed to determine the roles that the upper hinge Asp and His play in the radical reactions. The observation that none of these substitutions could inhibit the breakage of the heavy-light chain linkage suggests that the breakage may result from electron transfer from Cys(231) directly to the heavy-light chain linkage upon radical attacks, and implies a pathway separate from His(229)-mediated hinge cleavage. On the other hand, the substitution of His(229) with Tyr showed promising advantages over the native antibody and other substitutions in improving the stability and function of the IgG1. This substitution inhibited the hinge cleavage by 98% and suggests that the redox active nature of Tyr did not enable it to replicate the ability of His to facilitate radical induced degradation. We propose that the lower redox potential of Tyr, a residue that may be the ultimate sink for oxidizing equivalents in proteins, is responsible for the inhibition. More importantly, the substitution increased the antibody's binding to FcγRIII receptors by 2-3-fold, and improved ADCC activity by 2-fold, while maintaining a similar pharmacokinetic profile with respect to the wild type. Implications of these observations for antibody engineering and development are discussed.

Breaking the light and heavy chain linkage of human immunoglobulin G1 (IgG1) by radical reactions.

We report that the production of hydrogen peroxide by radical chain reductions of molecular oxygen into water in buffers leads to hinge degradation of a human IgG1 under thermal incubation conditions. The production of the hydrogen peroxide can be accelerated by superoxide dismutase or redox active metal ions or inhibited by free radical scavengers. The hydrogen peroxide production rate correlates well with the hinge cleavage. In addition to radical reaction mechanisms described previously, new degradation pathways and products were observed. These products were determined to be generated via radical reactions initiated by electron transfer and addition to the interchain disulfide bond between Cys(215) of the light chain and Cys(225) of the heavy chain. Decomposition of the resulting disulfide bond radical anion breaks the C-S bond at the side chain of Cys, converting it into dehydroalanine and generating a sulfur radical adduct at its counterpart. The hydrolysis of the unsaturated dehydropeptides removes Cys and yields an amide at the C terminus of the new fragment. Meanwhile, the competition between the carbonyl (-C(α)ONH-) and the side chain of Cys allows an electron transfer to the α carbon, forming a new intermediate radical species (-(·)C(α)(O(-))NH-) at Cys(225). Dissociative deamidation occurs along the N-C(α) bond, resulting in backbone cleavage. Given that hydrogen peroxide is a commonly observed product of thermal stress and plays a role in mediating the unique degradation of an IgG1, strategies for improving stability of human antibody therapeutics are discussed.

Investigation of Multicomponent Fluoridated Borate Glasses through a Design of Mixtures Approach.

Due to their enhanced dissolution, solubility and reaction speed, borate glasses offer potential advantages for the design and development of therapeutic ion-release systems. However, the field remains poorly understood relative to traditional phosphosilicate and silicate bioglasses. The increased structural complexity and relative lack of published data relating to borates, particularly borofluorates, also decreases the accuracy of artificial intelligence models, which are used to predict glass properties. To develop predictive models for borofluorate networks, this paper uses a design of mixtures approach for rapid screening of composition-property relationships, including the development of polynomial equations that comprehensively establish the predictive capabilities for glass transition, density, mass loss and fluoride release. A broad range of glass compositions, extending through the boron anomaly range, were investigated, with the inclusion of 45 to 95 mol% B2O3 along with 1-50 mol% MgO, CaO and Na2O as well as 1-30% KF and NaF. This design space allows for the investigation of the impact of fluorine as well as mixed alkali-alkaline earth effects. Glass formation was found to extend past 30 mol% KF or NaF without a negative impact on glass degradation in contrast to the trends observed in phosphosilicates. The data demonstrates that fluoroborate materials offer an exceptional base for the development of fluoride-releasing materials.

In vitro evaluation of Sensi-IP®: A soluble and mineralizing sensitivity solution.

OBJECTIVES: Sensi-IP®OG (SIP-OG) and Sensi-IP®FF (SIP-FF) are soluble bioactive glasses developed to treat dentin hypersensitivity and promote remineralization. Evaluation of their therapeutic potential to reduce dentin hypersensitivity and recover enamel strength was evaluated using standardized in vitro assessments based on simulated use. METHODS: To assess dentin occlusion a visual occlusion methodology was employed. Dentin discs were subjected to twice-daily simulated brushing (for 5 days) using 0.67 g of toothpaste for 10 s. Simple prototype toothpastes containing SIP-OG and SIP-FF were compared to commercially available controls: Colgate® Sensitive Pro-Relief (CPR) and Sensodyne® Repair and Protect with NovaMin® (SRP). Samples were stored in artificial saliva between treatments. All samples were assessed at baseline and subsequent to each treatment and were scored on a 5-point categorical scale for occlusion. For enamel surface effects, test articles of SIP-OG, SIP-FF, and SIP-FF with NaF were compared to a positive (with NaF) and a negative (no NaF) control paste. Enamel samples were subjected to a pH cycling regime, providing exposure to the toothpaste slurry (i.e., 2 parts deionized water to 1 part toothpaste), mineralizing solution, and demineralizing solution over 5 days of simulated use. Samples were stored overnight in mineralizing solution. Samples were evaluated for fluoride uptake and changes to surface microhardness. RESULTS: Visual occlusion scores (1 fully occluded to 5 unoccluded) were 2.6, 3.8, 4.4 and 4.0 after 1 day of simulated use for SIP-OG, SIP-FF with NaF, Colgate® Sensitive Pro-Relief and Sensodyne® Repair and Protect, respectively, decreasing to 1.0, 1.8, 3.1 and 3.9 after 5 days of application. SIP-OG provided superior occlusion at the significance level of p ≤ 0.05 at 1, 2, 3, 4, and 5 days. SIP-FF with NaF provided superior occlusion at the significance level of p ≤ 0.05 at 2, 4, and 5 days. Fluoride uptake ranged from 9.0 µg/cm2 for SIP-OG to 12.4 µg/cm2 for SIP-FF with NaF. Surface microhardness after acid cycling allowed recovery of 59 % of surface microhardness after treatment with SIP-OG or SIP-FF with NaF. SIP-OG achieved significant surface microhardness recovery versus SIP-FF alone, a NaF control paste, and a fluoride free control paste at the significance level of p ≤ 0.05. SIP-FF with NaF achieved surface microhardness recovery versus SIP-FF alone, a NaF control paste, and a fluoride free control paste at the significance level of p ≤ 0.05. CONCLUSIONS: Superior occlusion of dentin tubules was observed with both novel additives compared to commercially available toothpastes. A build-up effect with increasing occlusion was noted with repeated application for both novel additives and ascribed to mineralization effects, as supported by surface microhardness recovery on initial enamel lesions.

Characterization of glycation in an IgG1 by capillary electrophoresis sodium dodecyl sulfate and mass spectrometry.

We report a case study of characterization of a non-enzymatically glycated IgG1 using reducing capillary electrophoresis sodium dodecyl sulfate (CE-SDS) and mass spectrometry (MS). Glycation was found to occur nonspecifically at multiple sites in both the light and heavy chains. The glycated light and heavy chains result in wider peaks eluting late in the reducing CE-SDS profile; in particular, the glycated light chain behaved as a shoulder peak detected by either ultraviolet (UV) or laser-induced fluorescence (LIF) signals. The glycated species can be enriched by boronate affinity chromatography. Analyzing the enriched samples by reversed phase high-performance liquid chromatography in line with time-of-flight MS (RP-HPLC-TOF/MS) revealed adducts of +162 and +324 Da to both the light and heavy chains, suggesting the presence of multiple glycation sites. Tryptic peptide mapping and tandem mass sequencing were used to identify two glycation sites on each of the light and heavy chains.

The feasibility of degradable glass microspheres as transient embolic medical devices.

The deliberate occlusion of blood flow through transarterial embolization is currently being used to treat conditions ranging from hemorrhages to hypervascular tumors. Degradable, imageable high borate glass microspheres (BRS2) were developed and tested to improve lesion targeting and promote a temporary vascular occlusion which is sufficient for most embolization procedure. A 48 hour pilot study, in a swine renal model, was conducted to assess the embolization effectiveness and potential risks of this new embolic agent. Bilateral embolization of the caudal branch of the renal arteries using test and control particles were performed in 4 pigs. Embolization efficacy, recanalization and resulting ischemia were evaluated at different time frame (0, 24 and 48 hours). The primary outcomes for this study were the assessment of: (i) embolization effectiveness, and (ii) vessel recanalization. The test article was found to occlude vessels as effectively as the control microspheres, with the use of a smaller volume of microspheres. At the 24 hour time point, over 95% of the material was found to be completely degraded, although little to no recanalization was observed. This data suggests that BRS2 is an effective embolic agent, however further investigations into the method of delivery are required prior to clinical implementation.

Evaluation of two novel aluminum-free, zinc-based glass polyalkenoate cements as alternatives to PMMA bone cement for use in vertebroplasty and balloon kyphoplasty.

Vertebroplasty (VP) and balloon kyphoplasty (BKP) are now widely used for treating patients in whom the pain due to vertebral compression fractures is severe and has proved to be refractory to conservative treatment. These procedures involve percutaneous delivery of a bolus of an injectable bone cement either directly to the fractured vertebral body, VB (VP) or to a void created in it by an inflatable bone tamp (BKP). Thus, the cement is a vital component of both procedures. In the vast majority of VPs and BKPs, a poly(methyl methacrylate) (PMMA) bone cement is used. This material has many shortcomings, notably lack of bioactivity and very limited resorbability. Thus, there is room for alternative cements. We report here on two variants of a novel, bioactive, Al-free, Zn-based glass polyalkenoate cement (Zn-GPC), and how their properties compare to those of an injectable PMMA bone cement (SIMPL) that is widely used in VP and BKP. The properties determined were injectability, radiopacity, uniaxial compressive strength, and biaxial flexural modulus. In addition, we compared the compression fatigue lives of a validated synthetic osteoporotic VB model (a polyurethane foam cube with an 8 mm-diameter through-thickness cylindrical hole), at 0-2300 N and 3 Hz, when the hole was filled with each of the three cements. A critical review of the results suggests that the performance of each of the Zn-GPCs is comparable to that of SIMPL; thus, the former cements merit further study with a view to being alternatives to an injectable PMMA cement for use in VP and BKP.

The use of recombinant human bone morphogenic protein in posterior interbody fusions of the lumbar spine: a clinical series.

STUDY DESIGN: A 48 patient clinical series investigated posterior lumbar interbody fusions (PLIFs) incorporating bone morphogenic protein as an alternative to iliac crest bone graft. Patients were radiographically evaluated at an average of 16.9 months postsurgery. OBJECTIVE: To determine safety and efficacy of PLIF procedures using recombinant human bone morphogenic protein type 2 (rhBMP-2) and an absorbable collagen sponge carrier as an alternative for iliac crest bone graft. SUMMARY OF BACKGROUND DATA: Studies have shown that rhBMP-2 is safe and effective in anterior interbody and posterolateral lumbar spinal fusions to promote osteoinduction. METHODS: Consecutive series of 48 patients who underwent PLIF procedures at a total of 59 operative levels, without autologous bone grafting, were evaluated preoperatively and at a minimum of 11.2 months postoperatively (maximum 23.8 mo). Radiographic assessment was conducted with thin-slice computed tomography reconstructions to assess for fusion. Clinical measures including Oswestry Disability Questionnaire were also used. RESULTS: All patients demonstrated successful interbody and posterolateral fusions at all levels as determined by computed tomography scans. No patients demonstrated canal compromise, heterotopic bone formation, or adjacent level fusion. CONCLUSIONS: PLIF using rhBMP-2 is a promising method for facilitating lumbar arthrodesis while eliminating the need for iliac crest bone graft harvesting.

Mechanical loading, an important factor in the evaluation of ion release from bone augmentation materials.

The controlled release of therapeutic inorganic ions from biomaterials is an emerging area of international research. One of the foci for this research is the development of materials, which spatially and temporally modulate therapeutic release, via controlled degradation in the intended physiological environment. Crucially however, our understanding of the release kinetics for such systems remains limited, particularly with respect to the influence of physiological loading. Consequently, this study was designed to investigate the effect of dynamic mechanical loading on a composite material intended to stabilize, reinforce and strengthen vertebral bodies. The composite material contains a borate glass engineered to release strontium as a therapeutic inorganic ion at clinically relevant levels over extended time periods. It was observed that both cyclic (6 MPa 2 Hz) and static (4.3 MPa) compressive loading significantly increased the release of strontium ions in comparison to the static unloaded case. The observed alterations in ion release kinetics suggest that the mechanical loading of the implantation environment should be considered when evaluating the ion release kinetics.

Absorbed dose kernel and self-shielding calculations for a novel radiopaque glass microsphere for transarterial radioembolization.

PURPOSE: Radiopaque microspheres may provide intraprocedural and postprocedural feedback during transarterial radioembolization (TARE). Furthermore, the potential to use higher resolution x-ray imaging techniques as opposed to nuclear medicine imaging suggests that significant improvements in the accuracy and precision of radiation dosimetry calculations could be realized for this type of therapy. This study investigates the absorbed dose kernel for novel radiopaque microspheres including contributions of both short and long-lived contaminant radionuclides while concurrently quantifying the self-shielding of the glass network. METHODS: Monte Carlo simulations using EGSnrc were performed to determine the dose kernels for all monoenergetic electron emissions and all beta spectra for radionuclides reported in a neutron activation study of the microspheres. Simulations were benchmarked against an accepted 90 Y dose point kernel. Self-shielding was quantified for the microspheres by simulating an isotropically emitting, uniformly distributed source, in glass and in water. The ratio of the absorbed doses was scored as a function of distance from a microsphere. The absorbed dose kernel for the microspheres was calculated for (a) two bead formulations following (b) two different durations of neutron activation, at (c) various time points following activation. RESULTS: Self-shielding varies with time postremoval from the reactor. At early time points, it is less pronounced due to the higher energies of the emissions. It is on the order of 0.4-2.8% at a radial distance of 5.43 mm with increased size from 10 to 50 µm in diameter during the time that the microspheres would be administered to a patient. At long time points, self-shielding is more pronounced and can reach values in excess of 20% near the end of the range of the emissions. Absorbed dose kernels for 90 Y, 90m Y, 85m Sr, 85 Sr, 87m Sr, 89 Sr, 70 Ga, 72 Ga, and 31 Si are presented and used to determine an overall kernel for the microspheres based on weighted activities. The shapes of the absorbed dose kernels are dominated at short times postactivation by the contributions of 70 Ga and 72 Ga. Following decay of the short-lived contaminants, the absorbed dose kernel is effectively that of 90 Y. After approximately 1000 h postactivation, the contributions of 85 Sr and 89 Sr become increasingly dominant, though the absorbed dose-rate around the beads drops by roughly four orders of magnitude. CONCLUSIONS: The introduction of high atomic number elements for the purpose of increasing radiopacity necessarily leads to the production of radionuclides other than 90 Y in the microspheres. Most of the radionuclides in this study are short-lived and are likely not of any significant concern for this therapeutic agent. The presence of small quantities of longer lived radionuclides will change the shape of the absorbed dose kernel around a microsphere at long time points postadministration when activity levels are significantly reduced.

Advances in Degradable Embolic Microspheres: A State of the Art Review.

Considerable efforts have been placed on the development of degradable microspheres for use in transarterial embolization indications. Using the guidance of the U.S. Food and Drug Administration (FDA) special controls document for the preclinical evaluation of vascular embolization devices, this review consolidates all relevant data pertaining to novel degradable microsphere technologies for bland embolization into a single reference. This review emphasizes intended use, chemical composition, degradative mechanisms, and pre-clinical safety, efficacy, and performance, while summarizing the key advantages and disadvantages for each degradable technology that is currently under development for transarterial embolization. This review is intended to provide an inclusive reference for clinicians that may facilitate an understanding of clinical and technical concepts related to this field of interventional radiology. For materials scientists, this review highlights innovative devices and current evaluation methodologies (i.e., preclinical models), and is designed to be instructive in the development of innovative/new technologies and evaluation methodologies.

The Feasibility and Functional Performance of Ternary Borate-Filled Hydrophilic Bone Cements: Targeting Therapeutic Release Thresholds for Strontium.

We examine the feasibility and functionality of hydrophilic modifications to a borate glass reinforced resin composite; with the objective of meeting and maintaining therapeutic thresholds for Sr release over time, as a potential method of incorporating antiosteoporotic therapy into a vertebroplasty material. Fifteen composites were formulated with the hydrophilic agent hydroxyl ethyl methacrylate (HEMA, 15, 22.5, 30, 37.5 or 45 wt% of resin phase) and filled with a borate glass (55, 60 or 65 wt% of total cement) with known Sr release characteristics. Cements were examined with respect to degree of cure, water sorption, Sr release, and biaxial flexural strength over 60 days of incubation in phosphate buffered saline. While water sorption and glass degradation increased with increasing HEMA content, Sr release peaked with the 30% HEMA compositions, scanning electron microscope (SEM) imaging confirmed the surface precipitation of a Sr phosphate compound. Biaxial flexural strengths ranged between 16 and 44 MPa, decreasing with increased HEMA content. Degree of cure increased with HEMA content (42 to 81%), while no significant effect was seen on setting times (209 to 263 s). High HEMA content may provide a method of increasing monomer conversion without effect on setting reaction, providing sustained mechanical strength over 60 days.

Effect of boron oxide addition on the viscosity-temperature behaviour and structure of phosphate-based glasses.

In this study, nine phosphate-based glass formulations from the system P2 O5 -CaO-Na2 O-MgO-B2 O3 were prepared with P2 O5 content fixed as 40, 45 and 50 mol%, where Na2 O was replaced by 5 and 10 mol% B2 O3 and MgO and CaO were fixed to 24 and 16 mol%, respectively. The effect of B2 O3 addition on the viscosity-temperature behaviour, fragility index and structure of the glasses was investigated. The composition of the glasses was confirmed by ICP-AES. The viscosity-temperature behaviour of the glasses were measured using beam-bending and parallel -plate viscometers. The viscosity of the glasses investigated was found to shift to higher temperature with increasing B2 O3 content. The kinetic fragility parameter, m and F1/2 , estimated from the viscosity curve were found to decease with increasing B2 O3 content. The structural analysis was achieved by a combination of Fourier transform infrared spectroscopy and solid state nuclear magnetic resonance. 31 P solid-state magic-angle-spinning nuclear magnetic resonance (MAS-NMR) showed that the local structure of the glasses changes with increasing B2 O3 content. As B2 O3 was added to the glass systems, the phosphate connectivity increases as the as the Q1 units transforms into Q2 units. The 11 B NMR results confirmed the presence of tetrahedral boron (BO4 ) units for all the compositions investigated. Structural analysis indicates an increasing level of cross-linking with increasing B2 O3 content. Evidence of the presence of P-O-B bonds was also observed from the FTIR and 31 P NMR analysis. © 2016 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater, 105B: 764-777, 2017.

Host responses to a strontium releasing high boron glass using a rabbit bilateral femoral defect model.

Borate glasses have shown promising potential as bioactive materials. With recent research demonstrating that glass properties may be modulated by appropriate compositional design. This may provide for indication specific material characteristics and controlled release of therapeutic inorganic ions (i.e., strontium); controlling such release is critical in order to harness the therapeutic potential. Within this sub-chronic pilot study, a rabbit long-bone model was utilized to explore the safety and efficacy of a high borate glass (LB102: 70B2 O3 -20SrO-6Na2 O-4La2 O3 ) particulate (90 - 710 µm) for bone regeneration. Six bilateral full-thickness defects (Ø = 3.5 mm; L = 8 mm) were created in three white New Zealand rabbits. Longitudinal non-decalcified sections of each defect site were produced and stained with Goldner's Trichrome. Histopathological examination revealed that LB102 demonstrated osteoconductive and osseointegrative properties with greater new bone being formed within and surrounding LB102 particles, when compared to the sham control. The inflammatory cell infiltration was observed to be slightly higher in the control when compared to LB102 defect sites, while no significant difference in fibrosis and neovascularization was determined, indicating that healing was occurring in a normal fashion. These data further suggest the possible utility of high borate glasses with appropriate compositional design for medical applications, such as bone augmentation. © 2016 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater, 105B: 1818-1827, 2017.