Genome-wide cancer-specific chromatin accessibility patterns derived from archival processed xenograft tumors.

Chromatin accessibility states that influence gene expression and other nuclear processes can be altered in disease. The constellation of transcription factors and chromatin regulatory complexes in cells results in characteristic patterns of chromatin accessibility. The study of these patterns in tissues has been limited because existing chromatin accessibility assays are ineffective for archival formalin-fixed, paraffin-embedded (FFPE) tissues. We have developed a method to efficiently extract intact chromatin from archival tissue via enhanced cavitation with a nanodroplet reagent consisting of a lipid shell with a liquid perfluorocarbon core. Inclusion of nanodroplets during the extraction of chromatin from FFPE tissues enhances the recovery of intact accessible and nucleosome-bound chromatin. We show that the addition of nanodroplets to the chromatin accessibility assay formaldehyde-assisted isolation of regulatory elements (FAIRE), does not affect the accessible chromatin signal. Applying the technique to FFPE human tumor xenografts, we identified tumor-relevant regions of accessible chromatin shared with those identified in primary tumors. Further, we deconvoluted non-tumor signal to identify cellular components of the tumor microenvironment. Incorporation of this method of enhanced cavitation into FAIRE offers the potential for extending chromatin accessibility to clinical diagnosis and personalized medicine, while also enabling the exploration of gene regulatory mechanisms in archival samples.

Element Position Calibration for Matrix Array Transducers with Multiple Disjoint Piezoelectric Panels.

Two-dimensional ultrasound transducers enable the acquisition of fully volumetric data that have been demonstrated to provide greater diagnostic information in the clinical setting and are a critical tool for emerging ultrasound methods, such as super-resolution and functional imaging. This technology, however, is not without its limitations. Due to increased fabrication complexity, some matrix probes with disjoint piezoelectric panels may require initial calibration. In this manuscript, two methods for calibrating the element positions of the Vermon 1024-channel 8 MHz matrix transducer are detailed. This calibration is a necessary step for acquiring high resolution B-mode images while minimizing transducer-based image degradation. This calibration is also necessary for eliminating vessel-doubling artifacts in super-resolution images and increasing the overall signal-to-noise ratio (SNR) of the image. Here, we show that the shape of the point spread function (PSF) can be significantly improved and PSF-doubling artifacts can be reduced by up to 10 dB via this simple calibration procedure.

Sagittal Plane Alignment for First Metatarsal Phalangeal Arthrodesis Correlated with Postoperative Function: What is the Optimal Position?

There have been many reports describing the proposed alignment of a first metatarsal phalangeal arthrodesis to obtain optimum function. Most of these recommendations are based upon historical and anecdotal evidence. Furthermore, there are few reports directly comparing alignment to patient reported function. We studied radiographic sagittal plane alignment in a group of 60 patients (80 feet) who had undergone a first metatarsal phalangeal joint arthrodesis (20 of the 60 had bilateral arthrodesis) to better understand how this component of the arthrodesis position translates to real world function. The patients in this study had completed a functional survey in 2022 at a mean of 28.4 (median 27.8; range 13.2-45.7) months with very high satisfaction for return to activities of daily living and recreational sports. We measured the sagittal plane position of the first metatarsal relative to the proximal phalanx in this cohort with known post operative activity data. We found that a mean (standard of deviation) sagittal plane angle (angle between the anatomic axis of the first metatarsal and the proximal phalanx) of 15.4 (SD 7.4) degrees and a proximal phalanx head to ground height of 12.7 (SD 3.3) mm was present in this group. Comparing the functional and positional results we conclude that this sagittal plane position provides a good recommendation for alignment.

What Do Patients Report Regarding Their Real-World Function Following Concurrent Arthrodesis of the First Tarsometatarsal and First Metatarsophalangeal Joints.

First metatarsal phalangeal joint and the first Tarsometatarsal arthrodesis have both been used for deformity correction and treatment of pain and arthritis. Concomitant arthrodesis of the first metatarsophalangeal and first tarsometatarsal joints (Double First Ray Arthrodesis) has rarely been described. We surveyed 29 patients who underwent double first-ray arthrodesis for primary or revision correction of hallux valgus. A custom questionnaire was used to assess their activities of daily living and sports activity at a mean follow-up of 19.6 months (median 18.4 months). Secondary endpoints were return to activity, deformity correction, and arthrodesis healing rate. The primary outcomes showed an excellent return to activities of daily living with 96.6% of patients capable of walking as much as they liked after surgery at a normal pace. About 96.6% reported they felt that their surgery was successful, they had no pain, and the loss of motion at the joint fusion sites did not affect their ability to perform daily activities. Protected walking in a fracture boot was initiated at a mean (SD) of 9.8 (9.9) days. Return to an athletic shoe occurred at a mean (SD) of 44.2 (11.7) days. Full unrestricted activity was at a mean (SD) of 105.2 (19.3) days with 65% of the patient group reporting that their recovery was easier than expected. There was 1 nonunion and no other complications. This data set supports the hypothesis that patients undergoing double first-ray arthrodesis can return to activities of daily living and sports with and low complication rate.

A fully automated algorithm for heart rate detection in post-dive precordial Doppler ultrasound.

Background: Doppler ultrasound is used currently in decompression research for the evaluation of venous gas emboli (VGE). Estimation of heart rate from post-dive Doppler ultrasound recordings can provide a tool for the evaluation of physiological changes from decompression stress, as well as aid in the development of automated VGE detection algorithms that relate VGE presence to cardiac activity. Method: An algorithm based on short-term autocorrelation was developed in MATLAB to estimate the heart rate in post-dive precordial Doppler ultrasound. The algorithm was evaluated on 21 previously acquired and labeled precordial recordings spanning Kisman-Masurel (KM) codes of 111-444 (KM I-IV) with manually derived instantaneous heart rates. Results: A window size of at least two seconds was necessary for robust and accurate instantaneous heart rate estimation with a mean error of 1.56 ± 7.10 bpm. Larger window sizes improved the algorithm performance, at the cost of beat-to-beat heart rate estimates. We also found that our algorithm provides good results for low KM grade Doppler recordings with and without flexion, and high KM grades without flexion. High KM grades observed after movement produced the greatest mean absolute error of 6.12 ± 8.40 bpm. Conclusion: We have developed a fully automated algorithm for the estimation of heart rate in post-dive precordial Doppler ultrasound recordings.

What Do Patients Report Regarding Their Real-World Function Following Triplane Metatarsophalangeal Joint Arthrodesis for Hallux Valgus?

First metatarsal phalangeal (MTP) joint arthrodesis has been employed for decades for pain related to arthritis and other associated abnormalities. Despite the commonality of the procedure there continues to be questions regarding functional expectations following the procedure especially when employed for correction of hallux valgus deformity. We surveyed 60 patients who had a tri plane MTP joint arthrodesis at mean 28.4 months (median 27.8) regarding their activities of daily living and sports activity through a direct conversation. Secondary endpoints assessed were return to activity, deformity correction and arthrodesis healing rate based on chart review and weightbearing radiographs. The primary outcomes showed robust return to all activities of daily living with 96.7% able to walk without restrictions and or pain, 98.3% were able to walk at a normal pace and 95% responded that loss of motion of their big toe did not affect their daily function. Regarding return to sports all patients that participated in sports before surgery resumed participation after with a trend toward increased sports activity. Early return to walking in a fracture boot was noted in this cohort at mean 4.1 days, return to athletic shoe at mean 6.3 weeks and full unrestricted activity at mean 13.3 weeks with no non-unions identified on radiographic or clinical exam. Deformity correction of the typical components of hallux valgus deformity was similar to previously published studies. This data set supports the hypothesis that patients undergoing first MTP joint arthrodesis can expect rapid and full return to activities of daily living and sports with a low complication rate.

What Do Patients Report Regarding Their Real-World Function Following Triplane Metatarsophalangeal Joint Arthrodesis for Hallux Valgus?

First metatarsalphalangeal (MTP) joint arthrodesis has been employed for decades for pain related to arthritis and other associated abnormalities. Despite the commonality of the procedure there continues to be questions regarding functional expectations following the procedure especially when employed for correction of hallux valgus deformity. We surveyed 60 patients who had a triplane MTP joint arthrodesis at mean 28.4 months (median 27.8) regarding their activities of daily living and sports activity through a direct conversation. Secondary endpoints assessed were return to activity, deformity correction and arthrodesis healing rate based on chart review and weightbearing radiographs. The primary outcomes showed robust return to all activities of daily living with 97% able to walk without restrictions and or pain, 98% were able to walk at a normal pace and 95% responded that loss of motion of their big toe did not affect their daily function. Regarding return to sports all patients that participated in sports before surgery resumed participation after with a trend toward increased sports activity. Early return to walking in a fracture boot was noted in this cohort at mean 4.1 days, return to athletic shoe at mean 6.3 weeks and full unrestricted activity at mean 13.3 weeks with no non-unions identified on radiographic or clinical exam. Deformity correction of the typical components of hallux valgus deformity was similar to previously published studies. This data set supports the hypothesis that patients undergoing first MTP joint arthrodesis can expect rapid and full return to activities of daily living and sports with a low complication rate.

Low-boiling Point Perfluorocarbon Nanodroplets as Dual-Phase Dual-Modality MR/US Contrast Agent.

Detection of bare gas microbubbles by magnetic resonance (MR) at low concentrations typically used in clinical contrast-ultrasound studies was recently demonstrated using hyperCEST. Despite the enhanced sensitivity achieved with hyperCEST, in vivo translation is challenging as on-resonance saturation of the gas-phase core of microbubbles consequently results in saturation of the gas-phase hyperpolarized 129 Xe within the lungs. Alternatively, microbubbles can be condensed into the liquid phase to form perfluorocarbon nanodroplets, where 129 Xe resonates at a chemical shift that is separated from the gas-phase signal in the lungs. For ultrasound applications, nanodroplets can be acoustically reverted back into their microbubble form to act as a phase-change contrast agent. Here, we show that low-boiling point perfluorocarbons, both in their liquid and gas form, generate phase-dependent hyperCEST contrast. Magnetic resonance detection of ultrasound-mediated phase transition demonstrates that these perfluorocarbons could be used as a dual-phase dual-modality MR/US contrast agent.

Focused Ultrasound for Immunomodulation of the Tumor Microenvironment.

Focused ultrasound (FUS) has recently emerged as a modulator of the tumor microenvironment, paving the way for FUS to become a safe yet formidable cancer treatment option. Several mechanisms have been proposed for the role of FUS in facilitating immune responses and overcoming drug delivery barriers. However, with the wide variety of FUS parameters used in diverse tumor types, it is challenging to pinpoint FUS specifications that may elicit the desired antitumor response. To clarify FUS bioeffects, we summarize four mechanisms of action, including thermal ablation, hyperthermia/thermal stress, mechanical perturbation, and histotripsy, each inducing unique vascular and immunological effects. Notable tumor responses to FUS include enhanced vascular permeability, increased T cell infiltration, and tumor growth suppression. In this review, we have categorized and reviewed recent methods of using therapeutic ultrasound to elicit an antitumor immune response with examples that reveal specific solutions and challenges in this new research area.

A Rapid Prototyping Method for Sub-MHz Single-Element Piezoelectric Transducers by Using 3D-Printed Components.

We present a rapid prototyping method for sub-megahertz single-element piezoelectric transducers by using 3D-printed components. In most of the early research phases of applying new sonication ideas, the prototyping quickness is prioritized over the final packaging quality, since the quickness of preliminary demonstration is crucial for promptly determining specific aims and feasible research approaches. We aim to develop a rapid prototyping method for functional ultrasonic transducers to overcome the current long lead time (>a few weeks). Here, we used 3D-printed external housing parts considering a single matching layer and either air backing or epoxy-composite backing (acoustic impedance > 5 MRayl). By molding a single matching layer on the top surface of a piezoceramic in a 3D-printed housing, an entire packaging time was significantly reduced (<26 h) compared to the conventional methods with grinding, stacking, and bonding. We demonstrated this prototyping method for 590-kHz single-element, rectangular-aperture transducers for moderate pressure amplitudes (mechanical index > 1) at focus with temporal pulse controllability (maximum amplitude by <5-cycle burst). We adopted an air-backing design (Type A) for efficient pressure outputs, and bandwidth improvement was tested by a tungsten-composite-backing (Type B) design. The acoustic characterization results showed that the type A prototype provided 3.3 kPa/Vpp far-field transmitting sensitivity with 25.3% fractional bandwidth whereas the type B transducer showed 2.1 kPa/Vpp transmitting sensitivity with 43.3% fractional bandwidth. As this method provided discernable quickness and cost efficiency, this detailed rapid prototyping guideline can be useful for early-phase sonication projects, such as multi-element therapeutic ultrasound array and micro/nanomedicine testing benchtop device prototyping.

One- and Two-Year Analysis of a Five-Year Prospective Multicenter Study Assessing Radiographic and Patient-Reported Outcomes Following Triplanar First Tarsometatarsal Arthrodesis With Early Weightbearing for Symptomatic Hallux Valgus.

We report one- and 2-year results of a prospective, 5-year, multicenter study of radiographic, clinical, and patient-reported outcomes following triplanar first tarsometatarsal arthrodesis with early weightbearing. One-hundred and seventeen patients were included with a mean (95% confidence interval [CI]) follow-up time of 16.6 (15.5, 17.7) months. Mean (95% CI) time to weightbearing in a boot walker was 7.8 (6.6, 9.1) days, mean time to return to athletic shoes was 45.0 (43.5, 46.6) days, and mean time to return to unrestricted activity was 121.0 (114.5, 127.5) days. There was a significant improvement in radiographic measures with a mean corrective change of -18.0° (-19.6, -16.4) for hallux valgus angle, -8.3° (-8.9, -7.8) for intermetatarsal angle and -2.9 (-3.2, -2.7) for tibial sesamoid position at 12 months (n = 108). Additionally, there was a significant improvement in patient-reported outcomes (Visual Analog Scale, Manchester-Oxford Foot Questionnaire, and Patient-Reported Outcomes Measurement Information System) and changes were maintained at 12 and 24 months postoperatively. There was 1/117 (0.9%) reported recurrence of hallux valgus at 12 months. There were 16/117 (13.7%) subjects who experienced clinical complications of which 10/117 (8.5%) were related to hardware. Of the 7/117 (6.0%) who underwent reoperation, only 1/117 (0.9%) underwent surgery for a nonunion. The results of the interim report of this prospective, multicenter study demonstrate favorable clinical and radiographic improvement of the HV deformity, early return to weightbearing, low recurrence, and low rate of complications.

Magnetic Resonance Detection of Gas Microbubbles via HyperCEST: A Path Toward Dual Modality Contrast Agent.

Gas microbubbles are an established clinical ultrasound contrast agent. They could also become a powerful magnetic resonance (MR) intravascular contrast agent, but their low susceptibility-induced contrast requires high circulating concentrations or the addition of exogenous paramagnetic nanoparticles for MR detection. In order to detect clinical in vivo concentrations of raw microbubbles via MR, an alternative detection scheme must be used. HyperCEST is an NMR technique capable of indirectly detecting signals from very dilute molecules (concentrations well below the NMR detection threshold) that exchange hyperpolarized 129 Xe. Here, we use quantitative hyperCEST to show that microbubbles are very efficient hyperCEST agents. They can accommodate and saturate millions of 129 Xe atoms at a time, allowing for their indirect detection at concentrations as low as 10 femtomolar. The increased MR sensitivity to microbubbles achieved via hyperCEST can bridge the gap for microbubbles to become a dual modality contrast agent.

Ultrasound in decompression research: fundamentals, considerations, and future technologies.

It is widely accepted that bubbles are a necessary but insufficient condition for the development of decompression sickness. However, open questions remain regarding the precise formation and behavior of these bubbles after an ambient pressure reduction (decompression), primarily due to the inherent difficulty of directly observing this phenomenon in vivo. In decompression research, information about these bubbles after a decompression is gathered via means of ultrasound acquisitions. The ability to draw conclusions regarding decompression research using ultrasound is highly influenced by the variability of the methodologies and equipment utilized by different research groups. These differences play a significant role in the quality of the data and thus the interpretation of the results. The purpose of this review is to provide a technical overview of the use of ultrasound in decompression research, particularly Doppler and brightness (B)-mode ultrasound. Further, we will discuss the strengths and limitations of these technologies and how new advancements are improving our ability to understand bubble behavior post-decompression.

A fully automated method for late ventricular diastole frame selection in post-dive echocardiography without ECG gating.

Venous gas emboli (VGE) are often quantified as a marker of decompression stress on echocardiograms. Bubble-counting has been proposed as an easy to learn method, but remains time-consuming, rendering large dataset analysis impractical. Computer automation of VGE counting following this method has therefore been suggested as a means to eliminate rater bias and save time. A necessary step for this automation relies on the selection of a frame during late ventricular diastole (LVD) for each cardiac cycle of the recording. Since electrocardiograms (ECG) are not always recorded in field experiments, here we propose a fully automated method for LVD frame selection based on regional intensity minimization. The algorithm is tested on 20 previously acquired echocardiography recordings (from the original bubble-counting publication), half of which were acquired at rest (Rest) and the other half after leg flexions (Flex). From the 7,140 frames analyzed, sensitivity was found to be 0.913 [95% CI: 0.875-0.940] and specificity 0.997 [95% CI: 0.996-0.998]. The method's performance is also compared to that of random chance selection and found to perform significantly better (p≺0.0001). No trend in algorithm performance was found with respect to VGE counts, and no significant difference was found between Flex and Rest (p>0.05). In conclusion, full automation of LVD frame selection for the purpose of bubble counting in post-dive echocardiography has been established with excellent accuracy, although we caution that high quality acquisitions remain paramount in retaining high reliability.

ACFAS Clinical Consensus Statement: Acute Achilles Tendon Pathology.

Injuries to the Achilles tendon are a challenge to the foot and ankle surgeon. In recent years, research has led to a relative change in the way that many surgeons view acute Achilles tendon rupture. In an effort to fully evaluate these trends, as well as to evaluate all aspects of care for acute Achilles tendon rupture, the American College of Foot and Ankle Surgeons convened a panel of experts to create a clinical consensus statement to address selected aspects of care of the acute Achilles tendon injury.

A Systematic Approach to the Surgical Correction of Combined Hallux Valgus and Metatarsus Adductus Deformities.

The presence of metatarsus adductus (MTA) adds complexity to the diagnosis and treatment of hallux valgus (HV). Identification and careful analysis of these combined deformities is of paramount importance. The inability to completely correct HV and an increased incidence of recurrence has been established when MTA deformity is present. We present an option for correction of the combined deformities with multiplanar angular correction arthrodesis of the first, second, and third tarsometatarsal (TMT) joints.

Triplanar Correction for First Metatarsophalangeal Fusion.

Successful deformity correction utilizing first metatarsophalangeal (MTP) fusion for hallux valgus with concomitant degenerative changes of the first MTP joint is well documented. Currently, there is limited discussion in the literature focusing on triplanar correction of the first MTP arthrodesis. Presented is a novel approach for triplane correction and fusion of the first MTP joint utilizing a biplanar locked plating system.

Comparison of Radiographic Measurements Before and After Triplane Tarsometatarsal Arthrodesis for Hallux Valgus.

We present a comparison of preoperative and final postoperative first ray measurements in 109 feet after triplane tarsometatarsal arthrodesis at a mean follow-up time of 17.4 months. Preoperative and final postoperative first ray variables including intermetatarsal angle (IMA), hallux valgus angle (HVA), tibial sesamoid position (TSP), distal metatarsal articular angle (DMAA), Seiberg index, metatarsal rotation angle (MRA), sesamoid subluxation, osseous union, and hardware failure were evaluated. Measurements were made by consistently using the mid-diaphyseal line of the bone segments for both preoperative and postoperative assessments. The mean preoperative HVA, IMA, and TSP were 22.9°, 13.3°, and 4.6. The mean differences (95% confidence interval) in preoperative and postoperative values were -14.9° (-16.3° to -13.4°) for HVA, -7.7° (-8.2° to -7.2°) for IMA, and -2.6 (-2.8 to -2.3) for TSP. Among bunions with MRA measurements, the mean difference was -12.3° (-14.5° to -10.0°). The preoperative to postoperative DMAA decreased by a mean of -14.2° (-15.9° to -12.6°). The results of this study suggest that triplane tarsometatarsal arthrodesis produces appropriate correction of hallux valgus radiographic parameters.

On Command Drug Delivery via Cell-Conveyed Phototherapeutics.

Herein, the use of red blood cells (RBCs) as carriers of cytoplasmically interned phototherapeutic agents is described. Photolysis promotes drug release from the RBC carrier thereby providing the means to target specific diseased sites. This strategy is realized with a vitamin B12-taxane conjugate (B12-TAX), in which the drug is linked to the vitamin via a photolabile CoC bond. The conjugate is introduced into mouse RBCs (mRBCs) via a pore-forming/pore-resealing procedure and is cytoplasmically retained due to the membrane impermeability of B12. Photolysis separates the taxane from the B12 cytoplasmic anchor, enabling the drug to exit the RBC carrier. A covalently appended Cy5 antenna sensitizes the conjugate (Cy5-B12-TAX) to far red light, thereby circumventing the intense light absorbing properties of hemoglobin (350-600 nm). Microscopy and imaging flow cytometry reveal that Cy5-B12-TAX-loaded mRBCs act as drug carriers. Furthermore, intravital imaging of mice furnish a real time assessment of circulating phototherapeutic-loaded mRBCs as well as evidence of the targeted photorelease of the taxane upon photolysis. Histopathology confirms that drug release occurs in a well resolved spatiotemporal fashion. Finally, acoustic angiography is employed to assess the consequences of taxane release at the tumor site in Nu/Nu-tumor-bearing mice.

Benthic responses to an Antarctic regime shift: food particle size and recruitment biology.

Polar ecosystems are bellwether indicators of climate change and offer insights into ecological resilience. In this study, we describe contrasting responses to an apparent regime shift of two very different benthic communities in McMurdo Sound, Antarctica. We compared species-specific patterns of benthic invertebrate abundance and size between the west (low productivity) and east (higher productivity) sides of McMurdo Sound across multiple decades (1960s-2010) to depths of 60 m. We present possible factors associated with the observed changes. A massive and unprecedented shift in sponge recruitment and growth on artificial substrata observed between the 1980s and 2010 contrasts with lack of dramatic sponge settlement and growth on natural substrata, emphasizing poorly understood sponge recruitment biology. We present observations of changes in populations of sponges, bryozoans, bivalves, and deposit-feeding invertebrates in the natural communities on both sides of the sound. Scientific data for Antarctic benthic ecosystems are scant, but we gather multiple lines of evidence to examine possible processes in regional-scale oceanography during the eight years in which the sea ice did not clear out of the southern portion of McMurdo Sound. We suggest that large icebergs blocked currents and advected plankton, allowed thicker multi-year ice, and reduced light to the benthos. This, in addition to a possible increase in iron released from rapidly melting glaciers, fundamentally shifted the quantity and quality of primary production in McMurdo Sound. A hypothesized shift from large to small food particles is consistent with increased recruitment and growth of sponges on artificial substrata, filter-feeding polychaetes, and some bryozoans, as well as reduced populations of bivalves and crinoids that favor large particles, and echinoderms Sterechinus neumayeri and Odontaster validus that predominantly feed on benthic diatoms and large phytoplankton mats that drape the seafloor after spring blooms. This response of different guilds of filter feeders to a hypothesized shift from large to small phytoplankton points to the enormous need for and potential value of holistic monitoring programs, particularly in pristine ecosystems, that could yield both fundamental ecological insights and knowledge that can be applied to critical conservation concerns as climate change continues.