Donor Limb Functional Restoration via a Novel Clinical Care Pathway following Fibula Free Flap Harvest for Head and Neck Reconstruction.

Patients undergoing head and neck skeletal reconstruction (HNR) often require free tissue transfer from the extremities to ensure proper restoration of form and function. This requires a team-based, highly reliable medical system centered around the patient needs. Surgical intervention across multiple sites and harvesting of donor tissue results in short- and long-term physical impairments. There is a paucity of research objectively measuring impairments resulting from the graft donor site. There is a lack of research that objectively measures impairments and protocols for the management of these patients postoperatively. Patients undergo little, if any, formal approach to dealing with the vast impairments, which are sequelae to this surgery. This leads to large discrepancies in proposed functional progressions, return to duty timelines, and utilization of rehabilitative resources. At a major military medical center, an innovative clinical care pathway for patients undergoing HNR using free tissue transfer was implemented using a multidisciplinary model that focuses on early engagement with rehabilitation. This model, paired with a single surgery, will attempt to return service members to duty months earlier than the traditional approach. This report describes the conceptual framework and implementation of a new criteria-based, multidisciplinary clinical care pathway for HNR patients. The collaboration amongst the multidisciplinary care team has optimized the holistic health of the patient and communication with their support network, yielding faster return to normalization of daily life activities. The long-term goal is to further develop and formalize this pathway to best serve this patient population.

A microfluidic platform for the synthesis of polymer and polymer-protein-based protocells.

In this study, we demonstrate the fabrication of polymersomes, protein-blended polymersomes, and polymeric microcapsules using droplet microfluidics. Polymersomes with uniform, single bilayers and controlled diameters are assembled from water-in-oil-in-water double-emulsion droplets. This technique relies on adjusting the interfacial energies of the droplet to completely separate the polymer-stabilized inner core from the oil shell. Protein-blended polymersomes are prepared by dissolving protein in the inner and outer phases of polymer-stabilized droplets. Cell-sized polymeric microcapsules are assembled by size reduction in the inner core through osmosis followed by evaporation of the middle phase. All methods are developed and validated using the same glass-capillary microfluidic apparatus. This integrative approach not only demonstrates the versatility of our setup, but also holds significant promise for standardizing and customizing the production of polymer-based artificial cells.

Immediate dental rehabilitation in fibula free flaps for malignancy: Is it feasible?

BACKGROUND: Fibula free flap reconstruction has revolutionized maxillofacial reconstruction. While immediate dental rehabilitation with dental implants and teeth has shown benefits, it remains uncommon, especially for patients with malignancy. METHODS: A retrospective cohort study at a single institution explored immediate dental rehabilitation in fibula flaps for patients with malignant disease. Thirteen patients with malignancies that underwent immediate fibula free flap reconstruction with dental implants and dental prosthesis were included with a minimum of 3-month follow-up. RESULTS: Forty eight implants replaced 90 teeth in 13 patients. All implants were integrated at 3 months, with an overall success rate of 87.5%. Two patients experienced delayed (>3 months postoperatively) implant loss due to osteoradionecrosis and infection. Peri-mucositis occurred in three patients which resolved with treatment. Skin paddles were used in 11 patients and radiation therapy was not delayed for any patient. CONCLUSION: With proper patient selection, diagnosis of malignancy and the need for osteocutaneous flap reconstruction does not exclude the ability to place immediate implants and deliver an immediate dental prosthesis in head and neck reconstruction.

Determinants that enable disordered protein assembly into discrete condensed phases.

Cells harbour numerous mesoscale membraneless compartments that house specific biochemical processes and perform distinct cellular functions. These protein- and RNA-rich bodies are thought to form through multivalent interactions among proteins and nucleic acids, resulting in demixing via liquid-liquid phase separation. Proteins harbouring intrinsically disordered regions (IDRs) predominate in membraneless organelles. However, it is not known whether IDR sequence alone can dictate the formation of distinct condensed phases. We identified a pair of IDRs capable of forming spatially distinct condensates when expressed in cells. When reconstituted in vitro, these model proteins do not co-partition, suggesting condensation specificity is encoded directly in the polypeptide sequences. Through computational modelling and mutagenesis, we identified the amino acids and chain properties governing homotypic and heterotypic interactions that direct selective condensation. These results form the basis of physicochemical principles that may direct subcellular organization of IDRs into specific condensates and reveal an IDR code that can guide construction of orthogonal membraneless compartments.

Dental prosthesis extraoral indexing and pick-up technique for mandibular full arch immediate rehabilitation in fibula free flap reconstruction.

Same-day ablative and reconstructive surgeries for the treatment of head and neck pathologies are gaining in popularity with the recognition that single-day surgeries reduce morbidity and increase quality of life. Implant-borne prosthetics on the donor graft provide immediate dental reconstruction. This report describes a novel technique for extraoral pickup of a full arch immediate prosthesis from the donor site free flap. This technique minimizes intraoperative occlusal adjustments, saves intraoperative time, prevents undesirable "rolling" of a fibula segment, and immediately rehabilitates patients with dental prosthetics.

Not all (cells) who wander are lost: Upstream migration as a pervasive mode of amoeboid cell motility.

Leukocytes possess the ability to migrate upstream-against the direction of flow-on surfaces of specific chemistry. Upstream migration was first characterized in vitro for T-cells on surfaces comprised of intracellular adhesion molecule-1 (ICAM-1). Upstream migration occurs when the integrin receptor αLß2 (also known as lymphocyte function-associated antigen-1, or LFA-1) binds to ICAM-1. LFA-1/ICAM-1 interactions are ubiquitous and are widely found in leukocyte trafficking. Upstream migration would be employed after cells come to arrest on the apical surface of the endothelium and might confer an advantage for both trans-endothelial migration and tissue surveillance. It has now been shown that several other motile amoeboid cells which have the responsibility of trafficking from blood vessels into tissues, such as Marginal zone B cells, hematopoietic stem cells, and neutrophils (when macrophage-1 antigen, Mac-1, is blocked), can also migrate upstream on ICAM-1 surfaces. This review will summarize what is known about the basic mechanisms of upstream migration, which cells have displayed this phenomenon, and the possible role of upstream migration in physiology and tissue homeostasis.

Asymmetry-Enhanced Motion of Urease-Powered Micromotors from Double Emulsion-Templated Microcapsules.

Autonomous motion of enzyme-powered motors has important implications for drug delivery, cell-cell communication, and protocell engineering. Although many of these systems are inspired by the motion of biological cells, most of them lack key structural features, like micrometer-sized boundaries and aqueous compartments, and rely on bubble propulsion to generation motion. In this study, we use droplet microfluidics to generate large populations of cell-sized microcapsules with poly(lactic-co-glycolic acid) shells and functionalize their surfaces with the enzyme urease to drive their motion. We adjust the number of surface functional groups for urease conjugation by preparing microcapsules with two different surfactants, poly(vinyl alcohol) (PVA) and poly(ethylene-alt-maleic anhydride) (PEMA). We also tune the surface roughness of the microcapsules by varying the concentration of silica nanoparticles in the droplet middle phase. We find that PEMA plays a crucial role in increasing the grafting density of urease on the surface of smooth microcapsules, leading to active motion in the presence of urea. In addition, rough microcapsules prepared with PEMA and loaded with comparable amounts of urease move up to three times faster than their smooth counterparts, which we believe is due to an asymmetric distribution of urease on the surface, giving rise to a preferred direction of motion. Taken together, these results provide new insights into the role that various stabilizing agents play in the induction of motion by enzymatic motors prepared from microfluidics, which is a potentially powerful tool for future preparation of motile protocells in biomedicine.

Determinants of Disordered Protein Co-Assembly Into Discrete Condensed Phases.

Cells harbor numerous mesoscale membraneless compartments that house specific biochemical processes and perform distinct cellular functions. These protein and RNA-rich bodies are thought to form through multivalent interactions among proteins and nucleic acids resulting in demixing via liquid-liquid phase separation (LLPS). Proteins harboring intrinsically disordered regions (IDRs) predominate in membraneless organelles. However, it is not known whether IDR sequence alone can dictate the formation of distinct condensed phases. We identified a pair of IDRs capable of forming spatially distinct condensates when expressed in cells. When reconstituted in vitro, these model proteins do not co-partition, suggesting condensation specificity is encoded directly in the polypeptide sequences. Through computational modeling and mutagenesis, we identified the amino acids and chain properties governing homotypic and heterotypic interactions that direct selective condensation. These results form the basis of physicochemical principles that may direct subcellular organization of IDRs into specific condensates and reveal an IDR code that can guide construction of orthogonal membraneless compartments.

The Clinical Observership Program: A Valuable Experience for Oral & Maxillofacial Surgery Residents.

PURPOSE: Training during oral and maxillofacial surgery residency must include exposure to the scope of the specialty, but success in practice often requires particular experience and knowledge of complex oral regenerative procedures such as bone grafting and implant surgery, as well as practice management. Osteo Science Foundation created the Clinical Observership Program (COP) in 2017 to provide residents the opportunity to spend several weeks in an established oral and maxillofacial surgery practice to increase experience in these areas. The purpose of this study is to report the results of a survey of all resident participants in the COP from 2017 to 2021 in which participants were asked to rate their experience numerically. MATERIALS AND METHODS: This is an institutional retrospective case series completed via an electronic survey sent to all participants in the COP from 2017 to 2021. The primary outcome is the subjective assessment of the COP based on six questions in which the respondent was asked to rate the program on a scale of 1 to 10 (10 being best). Categories included: 1) Did the program achieve expectations? 2) Was adequate time spent with the mentor? 3) Did you observe/participate in a variety of procedures? 4) Did the mentor provide additional didactic education? 5) Did you learn about practice management? and 6) How would you rate the overall experience? Descriptive statistics including mean score and standard deviation of each question were calculated, and no other covariates were analyzed. RESULTS: All 55 participants in the COP from 2017 to 2021 were contacted and 55 complete responses were received. The overall mean score for all categories rated by the residents was 9.63, the mean rating for questions 1 to 6 were 9.55, 9.89, 9.21, 9.60, 9.69, and 9.86 respectively, and the range of scores was 7 to 10. CONCLUSION: Overall, residents rated the COP experience highly. This survey indicates that the COP is a valuable supplemental experience in oral and maxillofacial surgery resident education.

Recombinant Protein Micelles to Block Transduction by SARS-CoV-2 Pseudovirus.

The continuing emergence of variants of the SARS-CoV-2 virus requires the development of modular molecular therapies. Here, we engineered a recombinant amphiphilic protein, oleosin, to spontaneously self-assemble into multivalent micellar nanostructures which can block the Spike S1 protein of SARS-CoV-2 pseudoviruses (PVs). Short recombinant proteins like oleosin can be formulated more easily than antibodies and can be functionalized with precision through genetic engineering. We cloned S1-binding mini-protein genes called LCBx, previously designed by David Baker's laboratory (UW Seattle), to the N-terminus of oleosin, expressing Oleo-LCBx proteins in E. coli. These proteins largely formed 10-100 nm micelles as verified by dynamic light scattering. Two proteins, Oleo-LCB1 and Oleo-LCB3, were seen to completely and irreversibly block transduction by both wild-type and delta variant PVs into 293T-hsACE2 cells at 10 µM. Presented in multivalent micelles, these proteins reduced transduction by PVs down to a functional protein concentration of 5 nM. Additionally, Oleo-LCB1 micelles outperformed corresponding synthetic LCB1 mini-proteins in reducing transduction by PVs. Tunable aqueous solubility of recombinant oleosin allowed incorporation of peptides/mini-proteins at high concentrations within micelles, thus enhancing drug loading. To validate the potential multifunctionality of the micelles, we showed that certain combinations of Oleo-LCB1 and Oleo-LCB3 performed much better than the individual proteins at the same concentration. These micelles, which we showed to be non-toxic to human cells, are thus a promising step toward the design of modular, multifunctional therapeutics that could bind to and inactivate multiple receptors and proteins necessary for the infection of the SARS-CoV-2 virus.

Protein Condensate Formation via Controlled Multimerization of Intrinsically Disordered Sequences.

Many proteins harboring low complexity or intrinsically disordered sequences (IDRs) are capable of undergoing liquid-liquid phase separation to form mesoscale condensates that function as biochemical niches with the ability to concentrate or sequester macromolecules and regulate cellular activity. Engineered disordered proteins have been used to generate programmable synthetic membraneless organelles in cells. Phase separation is governed by the strength of interactions among polypeptides with multivalency enhancing phase separation at lower concentrations. Previously, we and others demonstrated enzymatic control of IDR valency from multivalent precursors to dissolve condensed phases. Here, we develop noncovalent strategies to multimerize an individual IDR, the RGG domain of LAF-1, using protein interaction domains to regulate condensate formation in vitro and in living cells. First, we characterize modular dimerization of RGG domains at either terminus using cognate high-affinity coiled-coil pairs to form stable condensates in vitro. Second, we demonstrate temporal control over phase separation of RGG domains fused to FRB and FKBP in the presence of dimerizer. Further, using a photocaged dimerizer, we achieve optically induced condensation both in cell-sized emulsions and within live cells. Collectively, these modular tools allow multiple strategies to promote phase separation of a common core IDR for tunable control of condensate assembly.

Incorporation and Assembly of a Light-Emitting Enzymatic Reaction into Model Protein Condensates.

Eukaryotic cells partition enzymes and other cellular components into distinct subcellular compartments to generate specialized biochemical niches. A subclass of these compartments form in the absence of lipid membranes, via liquid-liquid phase separation of proteins to form biomolecular condensates or "membraneless organelles" such as nucleoli, stress granules, and P-bodies. Because of their propensity to form compartments from simple starting materials, membraneless organelles are an attractive target for engineering new functionalities in both living cells and protocells. In this work, we demonstrate incorporation of a novel enzymatic activity in protein coacervates with the light-generating enzyme, NanoLuc, to produce bioluminescence. Using condensates comprised of the disordered RGG domain of Caenorhabditis elegans LAF-1, we functionalized condensates with enzymatic activity in vitro and show that enzyme localization to coacervates enhances assembly and activity of split enzymes. To build condensates that function as light-emitting reactors, we designed a NanoLuc enzyme flanked by RGG domains. The resulting condensates concentrated NanoLuc by 10-fold over bulk solution and displayed significantly increased reaction rates. We further show that condensate viscosity impacts light emission due to diffusion-limited behavior. Because our model condensates have low viscosities, we predict NanoLuc diffusion-limited behavior in most other condensates and thus propose the condensate-Nanoluc system as a potential strategy for high-throughput screening of condensate targeting drugs. By splitting the NanoLuc enzyme into its constituent components, we demonstrate that NanoLuc activity can be reconstituted via co-condensation. In addition, we demonstrate control of the spatial localization of the enzyme within condensates by targettng NanoLuc to the surface of in vitro condensates. Collectively, this work demonstrates that membraneless organelles can be endowed with localized enzymatic activity and that this activity can be spatially and temporally controlled via biochemical reconstitution and design of protein surfactants.

Integrin cross-talk modulates stiffness-independent motility of CD4+ T lymphocytes.

To carry out their physiological responsibilities, CD4+ T lymphocytes interact with various tissues of different mechanical properties. Recent studies suggest that T cells migrate upstream on surfaces expressing intracellular adhesion molecule-1 (ICAM-1) through interaction with leukocyte function-associated antigen-1 (αLß2) (LFA-1) integrins. LFA-1 likely behaves as a mechanosensor, and thus we hypothesized that substrate mechanics might affect the ability of LFA-1 to support upstream migration of T cells under flow. Here we measured motility of CD4+ T lymphocytes on polyacrylamide gels with predetermined stiffnesses containing ICAM-1, vascular cell adhesion molecule-1 (VCAM-1), or a 1:1 mixture of VCAM-1/ICAM-1. Under static conditions, we found that CD4+ T cells exhibit an increase in motility on ICAM-1, but not on VCAM-1 or VCAM-1/ICAM-1 mixed, surfaces as a function of matrix stiffness. The mechanosensitivity of T-cell motility on ICAM-1 is overcome when VLA-4 (very late antigen-4 [α4ß1]) is ligated with soluble VCAM-1. Last, we observed that CD4+ T cells migrate upstream under flow on ICAM-1-functionalized hydrogels, independent of substrate stiffness. In summary, we show that CD4+ T cells under no flow respond to matrix stiffness through LFA-1, and that the cross-talk of VLA-4 and LFA-1 can compensate for deformable substrates. Interestingly, CD4+ T lymphocytes migrated upstream on ICAM-1 regardless of the substrate stiffness, suggesting that flow can compensate for substrate stiffness.

Multivariable Dependence of Acoustic Contrast of Fluorocarbon and Xenon Microbubbles under Flow.

Microbubbles (MBs) are 1 to 10 µm gas particles stabilized by an amphiphilic shell capable of responding to biomedical ultrasound with strong acoustic signals, allowing them to be commonly used in ultrasound imaging and therapy. The composition of both the shell and the core determines their stability and acoustic properties. While there has been extensive characterization of the dissolution, oscillation, cavitation, collapse and therefore, ultrasound contrast of MBs under static conditions, few reports have examined such behavior under hydrodynamic flow. In this study, we evaluate the interplay of ultrasound parameters (five different mechanical indices [MIs]), MB shell parameter (shell stiffness), type of gas (perfluorocarbon for diagnostic imaging and xenon as a therapeutic gas), and a flow parameter (flow rate) on the ultrasound signal of phospholipid-stabilized MBs flowing through a latex tube embedded in a tissue-mimicking phantom. We find that the contrast gradient (CG), a metric of the rate of decay of contrast along the length of the tube, and the contrast peak (CP), the location where the maximum contrast is reached, depend on the conditions of flow, imaging, and MB material. For instance, while the contrast near the flow inlet of the field of view is highest for a softer shell (dipalmitoylphosphatidylcholine [DPPC], C16) than for stiffer shells (distearoylphosphatidylcholine [DSPC], C18, and dibehenoylphosphatidylcholine [DBPC], C22), the contrast decay is also faster; stiffer shells provide more resistance and hence lead to slower MB dissolution/destruction. At higher flow rates, the CG is low for a fixed length of time because each MB is exposed to ultrasound for a shorter period. The CG becomes high for low flow rates, especially at high incident pressures (high MI), causing more MB destruction closer to the inlet of the field of view. Also, the CP shifts toward the inlet at low flow rates, high MIs, and low shell stiffness. We also report the first demonstration of sustained ultrasound flow imaging of a water-soluble, therapeutic gas MB (xenon). We find that an increased MB concentration is necessary for obtaining the same signal magnitude for xenon MBs. In summary, this study builds a framework depicting how multiple variables simultaneously affect the evolution of MB ultrasound contrast under flow. Depending on the MB composition, imaging conditions, transducer positioning, and image processing, building on such a framework could potentially allow for extraction of additional diagnostic information than is commonly analyzed for physiological flow.

Immediate Teeth in Fibulas: Expanded Clinical Applications and Surgical Technique.

PURPOSE: The placement of immediate implants and teeth during jaw reconstruction using a fibula free flap has increased in recent years. Modifications of traditional fibula reconstructive techniques are needed to maximize success. This technique has not been described in patients requiring simultaneous soft tissue reconstruction. Our patient cohort includes cases with malignant pathology and those requiring skin paddles.  With digital workflows and point-of-care 3D printing, surgery is no longer delayed weeks for prosthesis fabrication. The purpose of this case series is to demonstrate a single institution's experience with expanded clinical applications and surgical techniques that enable predictable outcomes for immediate teeth in fibula flaps. MATERIALS AND METHODS: Ninety-five implants were placed in 22 patients undergoing fibula reconstruction of the jaw with immediate implants and an immediate dental prosthesis. Skin paddles were used in 10 patients while 12 patients had native mucosa. Six patients were treated for malignancies and underwent postoperative radiation. Implant success and complications were compared between implants with skin paddles and implants with native mucosa. RESULTS: Of 95 implants, 92 implants integrated for a 97% integration rate. All 13 radiated implants in 4 patients integrated. All 36 implants adjacent to skin paddles in 10 patients integrated. Seven implants were lost in a delayed fashion 9 to 15 months postoperatively resulting in a 93% overall implant success rate. Of the 22 patients, diagnoses were benign pathology for 11 patients, malignant pathology for 6 patients, gunshot wounds for 3 patients, and osteoradionecrosis for 2 patients. CONCLUSION: Immediate placement of dental prostheses on immediate implants during fibula reconstruction of the jaws can be performed with a high rate of predictability. This technique can be expanded to select patients needing skin paddles. Modifications of traditional fibula reconstructive techniques are helpful to minimize soft tissue and prosthetic challenges.

LFA-1 signals to promote actin polymerization and upstream migration in T cells.

T cell entry into inflamed tissue requires firm adhesion, cell spreading, and migration along and through the endothelial wall. These events require the T cell integrins LFA-1 and VLA-4 and their endothelial ligands ICAM-1 and VCAM-1, respectively. T cells migrate against the direction of shear flow on ICAM-1 and with the direction of shear flow on VCAM-1, suggesting that these two ligands trigger distinct cellular responses. However, the contribution of specific signaling events downstream of LFA-1 and VLA-4 has not been explored. Using primary mouse T cells, we found that engagement of LFA-1, but not VLA-4, induces cell shape changes associated with rapid 2D migration. Moreover, LFA-1 ligation results in activation of the phosphoinositide 3-kinase (PI3K) and ERK pathways, and phosphorylation of multiple kinases and adaptor proteins, whereas VLA-4 ligation triggers only a subset of these signaling events. Importantly, T cells lacking Crk adaptor proteins, key LFA-1 signaling intermediates, or the ubiquitin ligase cCbl (also known as CBL), failed to migrate against the direction of shear flow on ICAM-1. These studies identify novel signaling differences downstream of LFA-1 and VLA-4 that drive T cell migratory behavior.This article has an associated First Person interview with the first author of the paper.

Identifying sequence perturbations to an intrinsically disordered protein that determine its phase-separation behavior.

Phase separation of intrinsically disordered proteins (IDPs) commonly underlies the formation of membraneless organelles, which compartmentalize molecules intracellularly in the absence of a lipid membrane. Identifying the protein sequence features responsible for IDP phase separation is critical for understanding physiological roles and pathological consequences of biomolecular condensation, as well as for harnessing phase separation for applications in bioinspired materials design. To expand our knowledge of sequence determinants of IDP phase separation, we characterized variants of the intrinsically disordered RGG domain from LAF-1, a model protein involved in phase separation and a key component of P granules. Based on a predictive coarse-grained IDP model, we identified a region of the RGG domain that has high contact probability and is highly conserved between species; deletion of this region significantly disrupts phase separation in vitro and in vivo. We determined the effects of charge patterning on phase behavior through sequence shuffling. We designed sequences with significantly increased phase separation propensity by shuffling the wild-type sequence, which contains well-mixed charged residues, to increase charge segregation. This result indicates the natural sequence is under negative selection to moderate this mode of interaction. We measured the contributions of tyrosine and arginine residues to phase separation experimentally through mutagenesis studies and computationally through direct interrogation of different modes of interaction using all-atom simulations. Finally, we show that despite these sequence perturbations, the RGG-derived condensates remain liquid-like. Together, these studies advance our fundamental understanding of key biophysical principles and sequence features important to phase separation.

Immediate Teeth in Fibulas: Planning and Digital Workflow With Point-of-Care 3D Printing.

PURPOSE: Point-of-care 3-dimensional (3D) printing has become more common in recent years because many hospitals have created 3D printing laboratories. Traditional techniques to fabricate an immediate dental prosthesis for fibula and implant reconstructions have involved outsourcing to dental laboratories. This results in delays, making it suitable only for benign disease. In the present report, we have demonstrated a technique for in-house creation of a 3D printed dental prosthesis for placement of implants at free fibula maxillofacial reconstruction. Our digital method has reduced costs and shortened the interval to surgery compared with traditional laboratory techniques. MATERIALS AND METHODS: Twelve patients underwent free fibula reconstruction of the mandible or maxilla with immediate implants and immediate teeth. A dental implant-retained restoration was created before surgery for immediate placement at fibula reconstruction. For the first 5 patients, the prosthesis was fabricated by a dental laboratory after virtual surgical planning. For the next 7 patients, the prosthesis was designed by the surgeon and 3D printed via the in-house laboratory. Four of these in-house cases were performed for malignant disease with skin paddles. RESULTS: All 12 patients received an immediate implant-retained fixed prosthesis at fibula reconstruction. The time required to generate the in-house 3D printed prostheses was significantly shorter than that required to create the dental laboratory-fabricated prostheses. The costs were also less with the 3D printed prostheses compared with the dental laboratory-fabricated prostheses. CONCLUSIONS: The digital workflow we have presented eliminates the delay in creating a dental laboratory-fabricated provisional dental prosthesis for fibula and implant reconstruction. This allows for immediate dental restoration for patients with malignant disease previously considered unsuitable owing to the inherent delay required using an offsite dental laboratory. A decrease in cost to create in-house 3D printed prostheses was noted compared with the prostheses fabricated by a dental laboratory. Case selection is critical to predict the soft tissue needs for composite defects.

Ultrasound Responsive Noble Gas Microbubbles for Applications in Image-Guided Gas Delivery.

Noble gases, especially xenon (Xe), have been shown to have antiapoptotic effects in treating hypoxia ischemia related injuries. Currently, in vivo gas delivery is systemic and performed through inhalation, leading to reduced efficacy at the injury site. This report provides a first demonstration of the encapsulation of pure Xe, Ar, or He in phospholipid-coated sub-10 µm microbubbles, without the necessity of stabilizing perfluorocarbon additives. Optimization of shell compositions and preparation techniques show that distearoylphosphatidylcholine (DSPC) with DSPE-PEG5000 can produce stable microbubbles upon shaking, while dibehenoylphosphatidylcholine (DBPC) blended with either DSPE-PEG2000 or DSPE-PEG5000 produces a high yield of microbubbles via a sonication/centrifugation method. Xe and Ar concentrations released into the microbubble suspension headspace are measured using GC-MS, while Xe released directly in solution is detected by the fluorescence quenching of a Xe-sensitive cryptophane molecule. Bubble production is found to be amenable to scale-up while maintaining their size distribution and stability. Excellent ultrasound contrast is observed in a phantom for several minutes under physiological conditions, while an intravenous administration of a bolus of pure Xe microbubbles provides significant contrast in a mouse in pre- and post-lung settings (heart and kidney, respectively), paving the way for image-guided, localized gas delivery for theranostic applications.