Community-Based Cluster-Randomized Trial to Reduce Opioid Overdose Deaths.

BACKGROUND: Evidence-based practices for reducing opioid-related overdose deaths include overdose education and naloxone distribution, the use of medications for the treatment of opioid use disorder, and prescription opioid safety. Data are needed on the effectiveness of a community-engaged intervention to reduce opioid-related overdose deaths through enhanced uptake of these practices. METHODS: In this community-level, cluster-randomized trial, we randomly assigned 67 communities in Kentucky, Massachusetts, New York, and Ohio to receive the intervention (34 communities) or a wait-list control (33 communities), stratified according to state. The trial was conducted within the context of both the coronavirus disease 2019 (Covid-19) pandemic and a national surge in the number of fentanyl-related overdose deaths. The trial groups were balanced within states according to urban or rural classification, previous overdose rate, and community population. The primary outcome was the number of opioid-related overdose deaths among community adults. RESULTS: During the comparison period from July 2021 through June 2022, the population-averaged rates of opioid-related overdose deaths were similar in the intervention group and the control group (47.2 deaths per 100,000 population vs. 51.7 per 100,000 population), for an adjusted rate ratio of 0.91 (95% confidence interval, 0.76 to 1.09; P = 0.30). The effect of the intervention on the rate of opioid-related overdose deaths did not differ appreciably according to state, urban or rural category, age, sex, or race or ethnic group. Intervention communities implemented 615 evidence-based practice strategies from the 806 strategies selected by communities (254 involving overdose education and naloxone distribution, 256 involving the use of medications for opioid use disorder, and 105 involving prescription opioid safety). Of these evidence-based practice strategies, only 235 (38%) had been initiated by the start of the comparison year. CONCLUSIONS: In this 12-month multimodal intervention trial involving community coalitions in the deployment of evidence-based practices to reduce opioid overdose deaths, death rates were similar in the intervention group and the control group in the context of the Covid-19 pandemic and the fentanyl-related overdose epidemic. (Funded by the National Institutes of Health; HCS ClinicalTrials.gov number, NCT04111939.).

Cost of start-up activities to implement a community-level opioid overdose reduction intervention in the HEALing Communities Study.

BACKGROUND: Communities That HEAL (CTH) is a novel, data-driven community-engaged intervention designed to reduce opioid overdose deaths by increasing community engagement, adoption of an integrated set of evidence-based practices, and delivering a communications campaign across healthcare, behavioral-health, criminal-legal, and other community-based settings. The implementation of such a complex initiative requires up-front investments of time and other expenditures (i.e., start-up costs). Despite the importance of these start-up costs in investment decisions to stakeholders, they are typically excluded from cost-effectiveness analyses. The objective of this study is to report a detailed analysis of CTH start-up costs pre-intervention implementation and to describe the relevance of these data for stakeholders to determine implementation feasibility. METHODS: This study is guided by the community perspective, reflecting the investments that a real-world community would need to incur to implement the CTH intervention. We adopted an activity-based costing approach, in which resources related to hiring, training, purchasing, and community dashboard creation were identified through macro- and micro-costing techniques from 34 communities with high rates of fatal opioid overdoses, across four states-Kentucky, Massachusetts, New York, and Ohio. Resources were identified and assigned a unit cost using administrative and semi-structured-interview data. All cost estimates were reported in 2019 dollars. RESULTS: State-level average and median start-up cost (representing 8-10 communities per state) were $268,657 and $175,683, respectively. Hiring and training represented 40%, equipment and infrastructure costs represented 24%, and dashboard creation represented 36% of the total average start-up cost. Comparatively, hiring and training represented 49%, purchasing costs represented 18%, and dashboard creation represented 34% of the total median start-up cost. CONCLUSION: We identified three distinct CTH hiring models that affected start-up costs: hospital-academic (Massachusetts), university-academic (Kentucky and Ohio), and community-leveraged (New York). Hiring, training, and purchasing start-up costs were lowest in New York due to existing local infrastructure. Community-based implementation similar to the New York model may have lower start-up costs due to leveraging of existing infrastructure, relationships, and support from local health departments.

Chitosan Membranes Stabilized with Varying Acyl Lengths Release Cis-2-Decenoic Acid and Bupivacaine at Controlled Rates and Inhibit Pathogenic Biofilm.

BACKGROUND: Adherence of complex bacterial biofilm communities to burned tissue creates a challenge for treatment, with infection causing 51% of burn victim deaths. This study evaluated the release of therapeutics from wound care biomaterials and their antimicrobial activity against pathogens Staphylococcus aureus, Acinetobacter baumannii, and Pseudomonas aeruginosa. METHODS: Electrospun chitosan membranes (ESCMs) were fabricated and acylated with chain lengths ranging from 6-10 carbons then loaded with 0.15 mg of anti-biofilm agent, cis-2-decenoic acid (C2DA), and 0.5 mg of local anesthetic, bupivacaine. RESULTS: Combinations of therapeutics released from modified ESCMs at a cumulative amount of 45-70% of bupivacaine and less than 20% of C2DA. Results from bacterial studies suggest that this combination reduced biofilm 10-fold for S. aureus, 2-fold for Acinetobacter baumannii, and 2-3-fold for Pseudomonas aeruginosa by 24 hours. Additionally, dual loaded groups reduced planktonic Staphylococcus aureus ~4-fold by 24 hours as well as Acinetobacter baumannii ~3-fold by 48 hours. CONCLUSIONS: The combination of therapeutics used has a significant role in biofilm prevention for selected strains via direct contact or diffusion in aqueous solutions.

Association Between Community Social Vulnerability and Preventable Hospitalizations.

Preventable hospitalizations are common and costly events that burden patients and our health care system. While research suggests that these events are strongly linked to ambulatory care access, emerging evidence suggests they may also be sensitive to a patient's social, environmental, and economic conditions. This study examines the association between variations in social vulnerability and preventable hospitalization rates. We conducted a cross-sectional analysis of county-level preventable hospitalization rates for 33 states linked with data from the 2020 Social Vulnerability Index (SVI). Preventable hospitalizations were 40% higher in the most vulnerable counties compared with the least vulnerable. Adjusted regression results confirm the strong relationship between social vulnerability and preventable hospitalizations. Our results suggest wide variation in community-level preventable hospitalization rates, with robust evidence that variation is strongly related to a community's social vulnerability. The human toll, societal cost, and preventability of these hospitalizations make understanding and mitigating these inequities a national priority.

Deer dietary responses to wildfire: Optimal foraging, individual specialization, or opportunism?

Increasing impacts of wildfire on arid regions of the world fuelled by climate change highlight the need to better understand how natural communities respond to fire. We took advantage of a large (1660-km2 ) wildfire that erupted in northern California during an in-progress study of black-tailed deer (Odocoileus hemionus columbianus) to investigate deer use of and diets within burned and unburned habitats before and after the fire. We compared deer diet breadth to predictions of optimal foraging theory, the niche variation hypothesis, and opportunistic (i.e., generalist) foraging expectations under the assumption that overall availability and diversity of forage in burned areas declined immediately after the fire and increased as the plant community recovered in the next 3 years after the fire. We used faecal pellet counts to document space use and metabarcoding to study diet during pre-fire, post-fire, and recovery periods. Pellet counts supported predictions that deer increased use of unburned sites and reduced use of burn sites after the fire and began to return to burned sites in subsequent sampling years. Diet diversity did not differ significantly between control and burn sites before the fire, but was lower in burn than control sites post-fire (p < .001), when and where diet was dominated by oak (Quercus spp). In contrast, during subsequent years, diet diversity was higher (including more herbaceous plants) in burn than control sites (p < .05). In contrast to predictions of optimal foraging and niche variation hypotheses, individual deer foraged as generalists for which changes in dietary niche breadth paralleled fire-induced changes in diversity of the plant community.

E-cadherin adhesion dynamics as revealed by an accelerated force ramp are dependent upon the presence of α-catenin.

Tissue remodeling and shape changes often rely on force-induced cell rearrangements occurring via cell-cell contact dynamics. Epithelial cell-cell contact shape changes are particularly dependent upon E-cadherin adhesion dynamics which are directly influenced by cell-generated and external forces. While both the mobility of E-cadherin adhesions and their adhesion strength have been reported before, it is not clear how these two aspects of E-cadherin adhesion dynamics are related. Here, using magnetic pulling cytometry, we applied an accelerated force ramp on the E-cadherin adhesion between an E-cadherin-coated magnetic microbead and an epithelial cell to ascertain this relationship. Our approach enables the determination of the adhesion strength and force-dependent mobility of individual adhesions, which revealed a direct correlation between these key characteristics. Since α-catenin has previously been reported to play a role in both E-cadherin mobility and adhesion strength when studied independently, we also probed epithelial cells in which α-catenin has been knocked out. We found that, in the absence of α-catenin, E-cadherin adhesions not only had lower adhesion strength, as expected, but were also more mobile. We observed that α-catenin was required for the recovery of strained cell-cell contacts and propose that the adhesion strength and force-dependent mobility of E-cadherin adhesions act in tandem to regulate cell-cell contact homeostasis. Our approach introduces a method which relates the force-dependent adhesion mobility to adhesion strength and highlights the morphological role played by α-catenin in E-cadherin adhesion dynamics.

Cis-2-Decenoic Acid and Bupivacaine Delivered from Electrospun Chitosan Membranes Increase Cytokine Production in Dermal and Inflammatory Cell Lines.

Wound dressings serve to protect tissue from contamination, alleviate pain, and facilitate wound healing. The biopolymer chitosan is an exemplary choice in wound dressing material as it is biocompatible and has intrinsic antibacterial properties. Infection can be further prevented by loading dressings with cis-2-decenoic acid (C2DA), a non-antibiotic antimicrobial agent, as well as bupivacaine (BUP), a local anesthetic that also has antibacterial capabilities. This study utilized a series of assays to elucidate the responses of dermal cells to decanoic anhydride-modified electrospun chitosan membranes (DA-ESCMs) loaded with C2DA and/or BUP. Cytocompatibility studies determined the toxic loading ranges for C2DA, BUP, and combinations, revealing that higher concentrations (0.3 mg of C2DA and 1.0 mg of BUP) significantly decreased the viability of fibroblasts and keratinocytes. These high concentrations also inhibited collagen production by fibroblasts, with lower loading concentrations promoting collagen deposition. These findings provide insight into preliminary cellular responses to DA-ESCMs and can guide future research on their clinical application as wound dressings.

α-Catenin Dependent E-cadherin Adhesion Dynamics as Revealed by an Accelerated Force Ramp.

Tissue remodeling and shape changes often rely on force-induced cell rearrangements occurring via cell-cell contact dynamics. Epithelial cell-cell contact shape changes are particularly dependent upon E-cadherin adhesion dynamics which are directly influenced by cell-generated and external forces. While both the mobility of E-cadherin adhesions and their adhesion strength have been reported before, it is not clear how these two aspects of E-cadherin adhesion dynamics are related. Here, using magnetic pulling cytometry, we applied an accelerated force ramp on the E-cadherin adhesion between an E-cadherin-coated magnetic microbead and an epithelial cell to ascertain this relationship. Our approach enables the determination of the adhesion strength and force-dependent mobility of individual adhesions, which revealed a direct correlation between these key characteristics. Since α-catenin has previously been reported to play a role in both E-cadherin mobility and adhesion strength when studied independently, we also probed epithelial cells in which α-catenin has been knocked out. We found that, in the absence of α-catenin, E-cadherin adhesions not only had lower adhesion strength, as expected, but were also more mobile. We observed that α-catenin was required for the recovery of strained cell-cell contacts and propose that the adhesion strength and force-dependent mobility of E-cadherin adhesions act in tandem to regulate cell-cell contact homeostasis. Our approach introduces a method which relates the force-dependent adhesion mobility to adhesion strength and highlights the morphological role played by α-catenin in E-cadherin adhesion dynamics.

Titanium coated with 2-decenoic analogs reduces bacterial and fungal biofilms.

AIMS: Due to antibiotic tolerance of microbes within biofilm, non-antibiotic methods for prevention and treatment of implant-related infections are preferable. The goal of this work is to evaluate a facile loading strategy for medium-chain fatty-acid signaling molecules 2-heptycyclopropane-1-carboxylic acid (2CP), cis-2-decenoic acid (C2DA), and trans-2-decenoic acid, which all act as diffusible signaling factors (DSFs), onto titanium surfaces for comparison of their antimicrobial efficacy. METHODS AND RESULTS: Titanium coupons were drop-coated with 0.75 mg of DSF in ethanol and dried. Surface characteristics and the presence of DSF were confirmed with Fourier Transform infrared spectroscopy, x-ray photoelectron spectroscopy, and water contact angle. Antimicrobial assays analyzing biofilm and planktonic Staphylococcus aureus, Escherichia coli, or Candida albicans viability showed that planktonic growth was reduced after 24-h incubation but only sustained through 72 h for S. aureus and C. albicans. Biofilm formation on the titanium coupons was also reduced for all strains at the 24-h time point, but not through 72 h for E. coli. Although ∼60% of the loaded DSF was released within the first 2 days, enough remained on the surface after 4 days of elution to significantly inhibit E. coli and C. albicans biofilm. Cytocompatibility evaluations with a fibroblast cell line showed that none of the DSF-loaded groups decreased viability, while C2DA and 2CP increased viability by up to 50%. CONCLUSIONS: In this study, we found that DSF-loaded titanium coupons can inhibit planktonic microbes and prevent biofilm attachment, without toxicity to mammalian cells.

Customized Scaffolds for Direct Assembly of Functionalized DNA Origami.

Functional DNA origami nanoparticles (DNA-NPs) are used as nanocarriers in a variety of biomedical applications including targeted drug delivery and vaccine development. DNA-NPs can be designed into a broad range of nanoarchitectures in one, two, and three dimensions with high structural fidelity. Moreover, the addressability of the DNA-NPs enables the precise organization of functional moieties, which improves targeting, actuation, and stability. DNA-NPs are usually functionalized via chemically modified staple strands, which can be further conjugated with additional polymers and proteins for the intended application. Although this method of functionalization is extremely efficient to control the stoichiometry and organization of functional moieties, fewer than half of the permissible sites are accessible through staple modifications. In addition, DNA-NP functionalization rapidly becomes expensive when a high number of functionalizations such as fluorophores for tracking and chemical modifications for stability that do not require spatially precise organization are used. To facilitate the synthesis of functional DNA-NPs, we propose a simple and robust strategy based on an asymmetric polymerase chain reaction (aPCR) protocol that allows direct synthesis of custom-length scaffolds that can be randomly modified and/or precisely modified via sequence design. We demonstrated the potential of our strategy by producing and characterizing heavily modified scaffold strands with amine groups for dye functionalization, phosphorothioate bonds for stability, and biotin for surface immobilization. We further validated our sequence design approach for precise conjugation of biomolecules by synthetizing scaffolds including binding loops and aptamer sequences that can be used for direct hybridization of nucleic acid tagged biomolecules or binding of protein targets.

Size-tunable ICG-based contrast agent platform for targeted near-infrared photoacoustic imaging.

Near-infrared photoacoustic imaging (NIR-PAI) combines the advantages of optical and ultrasound imaging to provide anatomical and functional information of tissues with high resolution. Although NIR-PAI is promising, its widespread use is hindered by the limited availability of NIR contrast agents. J-aggregates (JA) made of indocyanine green dye (ICG) represents an attractive class of biocompatible contrast agents for PAI. Here, we present a facile synthesis method that combines ICG and ICG-azide dyes for producing contrast agents with tunable size down to 230 nm and direct functionalization with targeting moieties. The ICG-JA platform has a detectable PA signal in vitro that is two times stronger than whole blood and high photostability. The targeting ability of ICG-JA was measured in vitro using HeLa cells. The ICG-JA platform was then injected into mice and in vivo NIR-PAI showed enhanced visualization of liver and spleen for 90 min post-injection with a contrast-to-noise ratio of 2.42.

A Microfluidic Platform to Monitor Real-Time Effects of Extracellular Vesicle Exchange between Co-Cultured Cells across Selectively Permeable Barriers.

Exosomes and other extracellular vesicles (EVs) play a significant yet poorly understood role in cell-cell communication during homeostasis and various pathological conditions. Conventional in vitro and in vivo approaches for studying exosome/EV function depend on time-consuming and expensive vesicle purification methods to obtain sufficient vesicle populations. Moreover, the existence of various EV subtypes with distinct functional characteristics and submicron size makes their analysis challenging. To help address these challenges, we present here a unique chip-based approach for real-time monitoring of cellular EV exchange between physically separated cell populations. The extracellular matrix (ECM)-mimicking Matrigel is used to physically separate cell populations confined within microchannels, and mimics tissue environments to enable direct study of exosome/EV function. The submicron effective pore size of the Matrigel allows for the selective diffusion of only exosomes and other smaller EVs, in addition to soluble factors, between co-cultured cell populations. Furthermore, the use of PEGDA hydrogel with a very small pore size of 1.2 nm in lieu of Matrigel allows us to block EV migration and, therefore, differentiate EV effects from effects that may be mediated by soluble factors. This versatile platform bridges purely in vitro and in vivo assays by enabling studies of EV-mediated cellular crosstalk under physiologically relevant conditions, enabling future exosome/EV investigations across multiple disciplines through real-time monitoring of vesicle exchange.

Validation of ICD-10-CM surveillance codes for traumatic brain injury inpatient hospitalizations.

Objective: Using inpatient data from a 1,160-bed health system, we assessed the positive predictive value (PPV) of ICD-10-CM (International Classification of Diseases, Tenth Revision, Clinical Modification) codes included in a traumatic brain injury (TBI) surveillance definition proposed by the Centers for Disease Control and Prevention (CDC) in 2016. Methods: A random sample of 196 records with ICD-10-CM TBI codes was reviewed. The PPVs for the ICD-10-CM codes' ability to capture true TBI cases were calculated as the percentage of records with confirmed clinical provider-documented TBI and reported with 95% confidence intervals [95%CIs]. Results: The estimated overall PPV was 74% [67.9%, 80.1%] when the codes were listed in any diagnostic field, but 91.5% [86.2%, 96.8%] when listed as the principal diagnosis. S06 codes (intracranial injury) had an overall PPV of 80.2% [74.3%, 86.1%] and 96.9% [93.3%, 100%] when listed as the principal diagnosis. S02.0-.1 codes (vault/base skull fractures) in any position without co-existing S06 codes had a PPV of 15.8% [0%, 33.2%]. Conclusions: Intracranial injury codes (S06) in any diagnostic position had a very high estimated PPV. Further research is needed to determine the utility of other codes included in the CDC proposed definition for TBI surveillance.

Health economic design for cost, cost-effectiveness and simulation analyses in the HEALing Communities Study.

BACKGROUND: The HEALing Communities Study (HCS) is designed to implement and evaluate the Communities That HEAL (CTH) intervention, a conceptually driven framework to assist communities in selecting and adopting evidence-based practices to reduce opioid overdose deaths. The goal of the HCS is to produce generalizable information for policy makers and community stakeholders seeking to implement CTH or a similar community intervention. To support this objective, one aim of the HCS is a health economics study (HES), the results of which will inform decisions around fiscal feasibility and sustainability relevant to other community settings. METHODS: The HES is integrated into the HCS design: an unblinded, multisite, parallel arm, cluster randomized, wait list-controlled trial of the CTH intervention implemented in 67 communities in four U.S. states: Kentucky, Massachusetts, New York, and Ohio. The objectives of the HES are to estimate the economic costs to communities of implementing and sustaining CTH; estimate broader societal costs associated with CTH; estimate the cost-effectiveness of CTH for overdose deaths avoided; and use simulation modeling to evaluate the short- and long-term health and economic impact of CTH, including future overdose deaths avoided and quality-adjusted life years saved, and to develop a simulation policy tool for communities that seek to implement CTH or a similar community intervention. DISCUSSION: The HCS offers an unprecedented opportunity to conduct health economics research on solutions to the opioid crisis and to increase understanding of the impact and value of complex, community-level interventions.

Synthesis of DNA Origami Scaffolds: Current and Emerging Strategies.

DNA origami nanocarriers have emerged as a promising tool for many biomedical applications, such as biosensing, targeted drug delivery, and cancer immunotherapy. These highly programmable nanoarchitectures are assembled into any shape or size with nanoscale precision by folding a single-stranded DNA scaffold with short complementary oligonucleotides. The standard scaffold strand used to fold DNA origami nanocarriers is usually the M13mp18 bacteriophage's circular single-stranded DNA genome with limited design flexibility in terms of the sequence and size of the final objects. However, with the recent progress in automated DNA origami design-allowing for increasing structural complexity-and the growing number of applications, the need for scalable methods to produce custom scaffolds has become crucial to overcome the limitations of traditional methods for scaffold production. Improved scaffold synthesis strategies will help to broaden the use of DNA origami for more biomedical applications. To this end, several techniques have been developed in recent years for the scalable synthesis of single stranded DNA scaffolds with custom lengths and sequences. This review focuses on these methods and the progress that has been made to address the challenges confronting custom scaffold production for large-scale DNA origami assembly.

In situ determination of exerted forces in magnetic pulling cytometry.

Localized application of exogenous forces on soft biomaterials and cells is often essential for the study of their response to external mechanical stimuli. Magnetic means of applying forces, particularly those based on permanent magnets and magnetic beads coupled to substrates or cells provide an accessible means of exerting forces of appropriate magnitude. The amount of force exerted, however, is often inferred from calibration performed ex situ, with typically similar but different magnetic beads. Here, we construct a simple magnetic tweezer by coupling a pencil-shaped stainless-steel probe to permanent neodymium magnets using a 3D printed adapter. We then demonstrate the in situ determination of magnetic bead pulling forces on a super-paramagnetic micro-bead coupled to a soft substrate using traction force microscopy. We determine the force exerted on the magnetic bead by the magnet probe - and thus exerted by the magnetic bead on the soft polyacrylamide substrate - as a function of the distance between the probe tip and the magnetic bead. We also show that we can determine the force exerted on a magnetic bead coupled to a cell by the changes in the traction force exerted by the cell on the soft substrate beneath. We thus demonstrate that forces of nanonewton magnitude can be locally exerted on soft substrates or cells and simultaneously determined using traction force microscopy. Application of this method for the in situ measurement of localized exogenous forces exerted on cells can also enable dissection of cellular force transmission pathways.

Xylan hemicellulose improves chitosan hydrogel for bone tissue regeneration.

The hemicellulose xylan, which has immunomodulatory effects, has been combined with chitosan to form a composite hydrogel to improve the healing of bone fractures. This thermally responsive and injectable hydrogel, which is liquid at room temperature and gels at physiological temperature, improves the response of animal host tissue compared with similar pure chitosan hydrogels in tissue engineering models. The composite hydrogel was placed in a subcutaneous model where the composite hydrogel is replaced by host tissue within 1 week, much earlier than chitosan hydrogels. A tibia fracture model in mice showed that the composite encourages major remodeling of the fracture callus in less than 4 weeks. A non-union fracture model in rat femurs was used to demonstrate that the composite hydrogel allows bone regeneration and healing of defects that with no treatment are unhealed after 6 weeks. These results suggest that the xylan/chitosan composite hydrogel is a suitable bone graft substitute able to aid in the repair of large bone defects.

Improved bio-implant using ultrafast laser induced self-assembled nanotexture in titanium.

The most successful metal implant materials currently have relatively smooth surfaces on the micron size scale, with most failures occurring after only 10 years. To move beyond this limiting time scale, texturing methods have been developed to modify the metal surface to enhance integration of the implant directly with surrounding bone. A flexible single-step ultrafast-laser texturing process has been developed that results in a surface texture that exhibits micron scale peaks and troughs with superimposed submicron and nano-scale features. The textured titanium samples remain completely hydrophilic with no measurable contact angle even after several weeks in normal atmosphere. An increase in mesenchymal stem cell number is observed over that on an untreated control titanium surface. Extensive formation of cellular bridges by stromal cells between pillars shows the favorable response of differentiated cells to the surface and the promotion of their attachment. Expression of the alkaline phosphatase and osteocalcin genes in human bone marrow cells were seen to increase on the textured surface. The development of this single-step method for creating micron, submicron, and nano-scale surface texture directly on metals makes a significant contribution to the goal of improving the integration and life span of joint replacement implants.

Peptides from phage display library modulate gene expression in mesenchymal cells and potentiate osteogenesis in unicortical bone defects.

Two novel synthetic peptides accelerate bone formation and can be delivered using a collagen matrix. The aim of this study was to investigate the effects on bone repair in a unicortical defect model. Treatment of mesenchymal cells produced an increase in alkaline phosphatase activity, showed nodule formation by the cells, and increased the expression of genes for runx2, osterix, bone sialoprotein, and osteocalcin. A collagen sponge soaked with peptide promoted repair of bone defects, whereas the control was less effective. The results from this study demonstrated that mesenchymal cells treated with peptide in vitro differentiate towards osteogenesis, and, that peptides delivered in vivo using a collagen sponge promote the repair of unicortical defects.