Involvement of Kindlin-1 in cutaneous squamous cell carcinoma.

Kindler syndrome (KS) is a rare genodermatosis resulting from loss-of-function mutations in FERMT1, the gene that encodes Kindlin-1. KS patients have a high propensity to develop aggressive and metastatic cutaneous squamous cell carcinoma (cSCC). Here we show in non-KS-associated patients that elevation of FERMT1 expression is increased in actinic keratoses compared to normal skin, with a further increase in cSCC supporting a pro-tumorigenic role in this population. In contrast, we show that loss of Kindlin-1 leads to increased SCC tumor growth in vivo and in 3D spheroids, which was associated with the development of a hypoxic tumor environment and increased glycolysis. The metalloproteinase Mmp13 was upregulated in Kindlin-1-depleted tumors, and increased expression of MMP13 was responsible for driving increased invasion of the Kindlin-1-depleted SCC cells. These results provide evidence that Kindlin-1 loss in SCC can promote invasion through the upregulation of MMP13, and offer novel insights into how Kindlin-1 loss leads to the development of a hypoxic environment that is permissive for tumor growth.

An in vitro agent-based modelling approach to optimization of culture medium for generating muscle cells.

Methodologies for culturing muscle tissue are currently lacking in terms of quality and quantity of mature cells produced. We analyse images from in vitro experiments to quantify the effects of culture media composition on mouse-derived myoblast behaviour and myotube quality. Metrics of early indicators of cell quality were defined. Images of muscle cell differentiation reveal that altering culture media significantly affects quality indicators and myoblast migratory behaviours. To study the effects of early-stage cell behaviours on mature cell quality, metrics drawn from experimental images or inferred by approximate Bayesian computation (ABC) were applied as inputs to an agent-based model (ABM) of skeletal muscle cell differentiation with quality indicator metrics as outputs. Computational modelling was used to inform further in vitro experiments to predict the optimum media composition for culturing muscle cells. Our results suggest that myonuclei production in myotubes is inversely related to early-stage nuclei fusion index and that myonuclei density and spatial distribution are correlated with residence time of fusing myoblasts, the age at which myotube-myotube fusion ends and the repulsion force between myonuclei. Culture media with 5% serum was found to produce the optimum cell quality and to make muscle cells cultured in a neuron differentiation medium viable.

Evaluation of routine proximal bone analysis for microbiology and histopathology in diabetes-related foot infections and osteomyelitis.

PURPOSE: The value of proximal bone analysis for surgical clearance of infection remains debated. Real-world practice traditionally utilized proximal bone microbiology rather than histopathology to diagnose residual diabetes-related osteomyelitis of the foot (DFO) post-amputation. We assessed the concordance between proximal bone microbiology and histopathology in determining residual infection and their predictability for revision operation in DFO and diabetes-related foot infection (DFI). METHODOLOGY: A single-centre retrospective study was conducted between June and December 2020 at a tertiary institution. We recruited patients with diabetes mellitus who had minor amputations for DFO and DFI and analyzed their proximal bone microbiology, histopathology and outcomes at 6 months. RESULTS: Eighty-four patients were recruited; 64 (76.2%) were male. The mean age was 69.3 years. The mean HbA1c was 8.6%. Seventy-seven operations were performed for DFO and 17 for DFI. Negative microbiology showed complete concordance with histopathology; and none had revision operation (P = 0.99). Positive microbiology had 9.8% concordance with histopathology (P = 0.99). Positive histopathology was associated with a higher rate of revision operation (80% vs. 12.5%; P = 0.01). High preoperative C-reactive protein was associated with residual DFO (P = 0.02) and revision operation (P = 0.01). CONCLUSION: Positive histopathology was more reliable for determining significant residual DFO and predicting revision operation. Positive microbiology was valuable for guiding antibiotic selection. We suggest routine proximal bone analysis for both histopathology and microbiology to optimize the treatment of DFO and DFI.

A case series of first rib resection patients assessed with a novel MRI protocol for neurogenic thoracic outlet syndrome.

Selecting patients who will benefit from first rib resection for neurogenic thoracic outlet syndrome (nTOS) is made difficult by the variety of overlap symptoms with other musculoskeletal, neurogenic and psychological disease. A single diagnostic test is not available, and the diagnosis is typically made based on clinical findings and history. This case series assessed the utility of magnetic resonance imaging (MRI), with the patient's arm placed in a symptom provoking position above the head, as a component of diagnosis nTOS and selection of patients to offer surgery. Outcomes from first rib resection were assessed using the guidelines of The Society for Vascular Surgery for Thoracic Outlet Syndrome. The cases demonstrate that the loss of perineural fat signal on MRI of the brachial plexus with the arm in the provocative position is a useful tool for assessing patients who would benefit from first rib resection for nTOS.

Variable sensitivity multimaterial robotic e-skin combining electronic and ionic conductivity using electrical impedance tomography.

Electronic skins (e-skins) aim to replicate the capabilities of human skin by integrating electronic components and advanced materials into a flexible, thin, and stretchable substrate. Electrical impedance tomography (EIT) has recently been adopted in the area of e-skin thanks to its robustness and simplicity of fabrication compared to previous methods. However, the most common EIT configurations have limitations in terms of low sensitivities in areas far from the electrodes. Here we combine two piezoresistive materials with different conductivities and charge carriers, creating anisotropy in the sensitive part of the e-skin. The bottom layer consists of an ionically conducting hydrogel, while the top layer is a self-healing composite that conducts electrons through a percolating carbon black network. By changing the pattern of the top layer, the resulting distribution of currents in the e-skin can be tuned to locally adapt the sensitivity. This approach can be used to biomimetically adjust the sensitivities of different regions of the skin. It was demonstrated how the sensitivity increased by 500% and the localization error reduced by 40% compared to the homogeneous case, eliminating the lower sensitivity regions. This principle enables integrating the various sensing capabilities of our skins into complex 3D geometries. In addition, both layers of the developed e-skin have self-healing capabilities, showing no statistically significant difference in localization performance before the damage and after healing. The self-healing bilayer e-skin could recover full sensing capabilities after healing of severe damage.

Sensorized Skin With Biomimetic Tactility Features Based on Artificial Cross-Talk of Bimodal Resistive Sensory Inputs.

Tactility in biological organisms is a faculty that relies on a variety of specialized receptors. The bimodal sensorized skin, featured in this study, combines soft resistive composites that attribute the skin with mechano- and thermoreceptive capabilities. Mimicking the position of the different natural receptors in different depths of the skin layers, a multi-layer arrangement of the soft resistive composites is achieved. However, the magnitude of the signal response and the localization ability of the stimulus change with lighter presses of the bimodal skin. Hence, a learning-based approach is employed that can help achieve predictions about the stimulus using 4500 probes. Similar to the cognitive functions in the human brain, the cross-talk of sensory information between the two types of sensory information allows the learning architecture to make more accurate predictions of localization, depth, and temperature of the stimulus contiguously. Localization accuracies of 1.8 mm, depth errors of 0.22 mm, and temperature errors of 8.2 °C using 8 mechanoreceptive and 8 thermoreceptive sensing elements are achieved for the smaller inter-element distances. Combining the bimodal sensing multilayer skins with the neural network learning approach brings the artificial tactile interface one step closer to imitating the sensory capabilities of biological skin.

Generating fast-twitch myotubes in vitro with an optogenetic-based, quantitative contractility assay.

The composition of fiber types within skeletal muscle impacts the tissue's physiological characteristics and susceptibility to disease and ageing. In vitro systems should therefore account for fiber-type composition when modelling muscle conditions. To induce fiber specification in vitro, we designed a quantitative contractility assay based on optogenetics and particle image velocimetry. We submitted cultured myotubes to long-term intermittent light-stimulation patterns and characterized their structural and functional adaptations. After several days of in vitro exercise, myotubes contract faster and are more resistant to fatigue. The enhanced contractile functionality was accompanied by advanced maturation such as increased width and up-regulation of neuron receptor genes. We observed an up-regulation in the expression of fast myosin heavy-chain isoforms, which induced a shift towards a fast-twitch phenotype. This long-term in vitro exercise strategy can be used to study fiber specification and refine muscle disease modelling.

Correction to 'Mathematical modelling of oxygen transport in a muscle-on-chip device' (2022) by Hardman et al.

[This corrects the article DOI: 10.1098/rsfs.2022.0020.][This corrects the article DOI: 10.1098/rsfs.2022.0020.].

3D Printable Soft Sensory Fiber Networks for Robust and Complex Tactile Sensing.

The human tactile system is composed of multi-functional mechanoreceptors distributed in an optimized manner. Having the ability to design and optimize multi-modal soft sensory systems can further enhance the capabilities of current soft robotic systems. This work presents a complete framework for the fabrication of soft sensory fiber networks for contact localization, using pellet-based 3D printing of piezoresistive elastomers to manufacture flexible sensory networks with precise and repeatable performances. Given a desirable soft sensor property, our methodology can design and fabricate optimized sensor morphologies without human intervention. Extensive simulation and experimental studies are performed on two printed networks, comparing a baseline network to one optimized via an existing information theory based approach. Machine learning is used for contact localization based on the sensor responses. The sensor responses match simulations with tunable performances and good localization accuracy, even in the presence of damage and nonlinear material properties. The potential of the networks to function as capacitive sensors is also demonstrated.

Mathematical modelling of oxygen transport in a muscle-on-chip device.

Muscle-on-chip devices aim to recapitulate the physiological characteristics of in vivo muscle tissue and so maintaining levels of oxygen transported to cells is essential for cell survival and for providing the normoxic conditions experienced in vivo. We use finite-element method numerical modelling to describe oxygen transport and reaction in a proposed three-dimensional muscle-on-chip bioreactor with embedded channels for muscle cells and growth medium. We determine the feasibility of ensuring adequate oxygen for muscle cell survival in a device sealed from external oxygen sources and perfused via medium channels. We investigate the effects of varying elements of the bioreactor design on oxygen transport to optimize muscle tissue yield and maintain normoxic conditions. Successful co-culturing of muscle cells with motor neurons can boost muscle tissue function and so we estimate the maximum density of seeded neurons supported by oxygen concentrations within the bioreactor. We show that an enclosed bioreactor can provide sufficient oxygen for muscle cell survival and growth. We define a more efficient arrangement of muscle and perfusion chambers that can sustain a predicted 50% increase in maximum muscle volume per perfusion vessel. A study of simulated bioreactors provides functions for predicting bioreactor designs with normoxic conditions for any size of perfusion vessel, muscle chamber and distance between chambers.

Manipulation of free-floating objects using Faraday flows and deep reinforcement learning.

The ability to remotely control a free-floating object through surface flows on a fluid medium can facilitate numerous applications. Current studies on this problem have been limited to uni-directional motion control due to the challenging nature of the control problem. Analytical modelling of the object dynamics is difficult due to the high-dimensionality and mixing of the surface flows while the control problem is hard due to the nonlinear slow dynamics of the fluid medium, underactuation, and chaotic regions. This study presents a methodology for manipulation of free-floating objects using large-scale physical experimentation and recent advances in deep reinforcement learning. We demonstrate our methodology through the open-loop control of a free-floating object in water using a robotic arm. Our learned control policy is relatively quick to obtain, highly data efficient, and easily scalable to a higher-dimensional parameter space and/or experimental scenarios. Our results show the potential of data-driven approaches for solving and analyzing highly complex nonlinear control problems.

Compressed vessels bias red blood cell partitioning at bifurcations in a hematocrit-dependent manner: Implications in tumor blood flow.

The tumor microenvironment is abnormal and associated with tumor tissue hypoxia, immunosuppression, and poor response to treatment. One important abnormality present in tumors is vessel compression. Vessel decompression has been shown to increase survival rates in animal models via enhanced and more homogeneous oxygenation. However, our knowledge of the biophysical mechanisms linking tumor decompression to improved tumor oxygenation is limited. In this study, we propose a computational model to investigate the impact of vessel compression on red blood cell (RBC) dynamics in tumor vascular networks. Our results demonstrate that vessel compression can alter RBC partitioning at bifurcations in a hematocrit-dependent and flow rate-independent manner. We identify RBC focusing due to cross-streamline migration as the mechanism responsible and characterize the spatiotemporal recovery dynamics controlling downstream partitioning. Based on this knowledge, we formulate a reduced-order model that will help future research to elucidate how these effects propagate at a whole vascular network level. These findings contribute to the mechanistic understanding of hemodilution in tumor vascular networks and oxygen homogenization following pharmacological solid tumor decompression.

Incidence, Management, and Outcomes of Aortic Graft Infection.

BACKGROUND: Infection complicates 1% of aortic grafts, and although uncommon, the associated morbidity and mortality are significant. We sought to determine risk factors for aortic graft infection (AGI), the long-term outcomes in patients managed both nonoperatively and via explantation. METHODS: This observational study reviewed sequential aortic grafts (thoracic or abdominal) inserted via open or endovascular means between 2000 and 2017. We used Cox proportional hazards regression analyses to compare risk factors between groups who did and did not acquire an AGI and recorded method of management, morbidity, mortality, and duration to adverse event. RESULTS: There were 883 aortic repairs, 49% were endovascular. 17.2% were for ruptured aneurysms, 1.1% for symptomatic aneurysms, 1.4% for type B dissections, and 0.5% for occlusive disease. Twelve patients presented with AGI, of which ten had their index procedure performed at our institution (AGI incidence of 1.1%). There was no difference in rates of AGI between open and endovascular repairs (0.9 vs. 1.4%, P = 0.24). AGI was significantly associated with emergency aortic repair (HR 3.63, 95% CI 1.13-11.57, P = 0.03), septic process requiring in-patient management during follow-up (HR 5.44, 95% CI 1.21-24.26, P = 0.02), and suprarenal clamping during open repair (HR 5.21, 95% CI 1.00-26.99, P = 0.05). Four patients were managed with explantation and revascularization (3 extra-anatomical bypasses) and remained well at a median follow-up of 46 months. Of the 8 patients managed nonoperatively, 4 died at an average of 13.5 days after representation, and the other 4 remained well on oral antibiotics at a median follow-up of 26.5 months. No patient suffered limb loss, and there was no change in the rate of infection over the period. CONCLUSIONS: Incidence of AGI remains low but is associated with significant mortality. Patients with aortic grafts in situ require aggressive treatment of septic foci to prevent graft infection.

On the prediction of monocyte deposition in abdominal aortic aneurysms using computational fluid dynamics.

In abdominal aortic aneurysm disease, the aortic wall is exposed to intense biological activity involving inflammation and matrix metalloproteinase-mediated degradation of the extracellular matrix. These processes are orchestrated by monocytes and rather than affecting the aorta uniformly, damage and weaken focal areas of the wall leaving it vulnerable to rupture. This study attempts to model numerically the deposition of monocytes using large eddy simulation, discrete phase modelling and near-wall particle residence time. The model was first applied to idealised aneurysms and then to three patient-specific lumen geometries using three-component inlet velocities derived from phase-contrast magnetic resonance imaging. The use of a novel, variable wall shear stress-limiter based on previous experimental data significantly improved the results. Simulations identified a critical diameter (1.8 times the inlet diameter) beyond which significant monocyte deposition is expected to occur. Monocyte adhesion occurred proximally in smaller abdominal aortic aneurysms and distally as the sac expands. The near-wall particle residence time observed in each of the patient-specific models was markedly different. Discrete hotspots of monocyte residence time were detected, suggesting that the monocyte infiltration responsible for the breakdown of the abdominal aortic aneurysm wall occurs heterogeneously. Peak monocyte residence time was found to increase with aneurysm sac size. Further work addressing certain limitations is needed in a larger cohort to determine clinical significance.

Comparison of patient-specific inlet boundary conditions in the numerical modelling of blood flow in abdominal aortic aneurysm disease.

Three inlet boundary condition datasets were derived from phase-contrast MRI: (i) centre line velocity data converted to two-dimensional (2D) velocity profile using Womersley equations (Womersley), (ii) 2D velocity profile with one axial component of velocity (1CV), (iii) 2D velocity profile with three components of velocity (3CV). Computational fluid dynamics was performed using a rigid wall approach with geometry data extracted from the computed tomography dataset. Helical flow was present in the 1CV and 3CV simulations, with more complex patterns for the 3CV case. The Womersley method produced simplified flow patterns with an absence of helical flow. Mean values of quantitative indices (helical flow index, mean wall shear stress, oscillatory index) were compared with the 3CV inlet data. These were lower for both the Womersley inlet data (28%, 71%, 56%) and the 1CV inlet data (9%, 24%, 69%). It was concluded that inlet methods based on centre line velocity, such as might be obtained from Doppler ultrasound, lead to significantly simplified abdominal aortic aneurysm haemodynamics and thus are not recommended. Single velocity component (axial) data from MRI might suffice when general flow characteristics and spatial wall shear stress are required. Ideally 2D MRI velocity profiles with 3-velocity component data are preferred to fully account for helical flow.

The role of botanic gardens in the science and practice of ecological restoration.

Many of the skills and resources associated with botanic gardens and arboreta, including plant taxonomy, horticulture, and seed bank management, are fundamental to ecological restoration efforts, yet few of the world's botanic gardens are involved in the science or practice of restoration. Thus, we examined the potential role of botanic gardens in these emerging fields. We believe a reorientation of certain existing institutional strengths, such as plant-based research and knowledge transfer, would enable many more botanic gardens worldwide to provide effective science-based support to restoration efforts. We recommend botanic gardens widen research to include ecosystems as well as species, increase involvement in practical restoration projects and training practitioners, and serve as information hubs for data archiving and exchange.

Development of the surgical science examination of the Royal Australasian College of Surgeons surgical education and training programme: putting the chicken before the egg.

Basic science knowledge is a foundational element of surgical practice. Increasing surgical specialization may merit a reconsideration of the 'whole-body' approach to basic science curriculum in favour of specialty specific depth. The conundrum of depth or breadth of basic science curriculum is currently being addressed by the Royal Australasian College of Surgeons, which introduced a new surgical education and training programme for nine surgical specialties in 2008. This paper describes an innovative solution to the design of a basic science curriculum in the nine different surgical specialty streams of this programme. The task was to develop a curriculum and rigorous assessment in basic sciences to meet the needs of the training programme, for implementation within the first year. A number of political/cultural and technical issues were identified as critical to success. To achieve a robust assessment within the required time frame attention was paid to engagement, governance, curriculum definition, assessment development, and implementation. The pragmatic solution to curriculum and assessment was to use the existing assessment items and blueprint to determine a new curriculum definition and assessment. The resulting curriculum comprises a generic component, undertaken by all trainees, and specialty specific components. In a time critical environment, a pragmatic solution to curriculum, applied with predetermined, structured and meticulous methodology, allowed explicit definition of breadth for the generic basic science curriculum for surgical training in Australia and New Zealand. Implicit definition of specialty specific-basic science curricula was through the creation of a blueprinted assessment.

Follow-up costs increase the cost disparity between endovascular and open abdominal aortic aneurysm repair.

OBJECTIVE: This study compared the hospital and follow-up costs of patients who have undergone endovascular (EVAR) or open (OR) elective abdominal aortic aneurysm repair. METHODS: The records of 195 patients (EVAR, n = 55; OR, n = 140) who underwent elective aortic aneurysm repair between 1995 and 2004 were reviewed. Primary costing data were analyzed for 54 EVAR and 135 OR patients. Hospital costs were divided into preoperative, operative, and postoperative costs. Follow-up costs for EVAR patients were recorded, with a median follow-up time of 12 months. RESULTS: Mean preoperative costs were slightly higher in the EVAR group (AU $961/US $733 vs AU $869/US $663; not significant). Operative costs were significantly higher in the EVAR group (AU $16,124/US $12,297 vs AU $6077/US $4635; P < .001); this was entirely due to the increased cost of the endograft (AU $10,181/US $7,765 for EVAR vs AU $476/US $363 for OR). Postoperative costs were significantly reduced in the EVAR group (AU $4719/US $3599 vs AU $11,491/US $8,764; P < .001). Total hospital costs were significantly greater in the EVAR group (AU $21,804/US $16,631 vs AU $18,437/US $14,063; P < .001). The increase in total hospital costs was due to a significant difference in graft costs, which was not offset by reduced postoperative costs. The average follow-up cost per year after EVAR was AU $1316/US $999. At 1 year of follow-up, EVAR remained significantly more expensive than OR (AU $23,120/US $17,640 vs AU $18,510/US $14,122; P < .001); this cost discrepancy increased with a longer follow-up. CONCLUSIONS: EVAR results in significantly greater hospital costs compared with OR, despite reduced hospital and intensive care unit stays. The inclusion of follow-up costs further increases the cost disparity between EVAR and OR. Because EVAR requires lifelong surveillance and has a high rate of reintervention, follow-up costs must be included in any cost comparison of EVAR and OR. The economic cost, as well as the efficacy, of new technologies such as EVAR must be addressed before their widespread use is advocated.

A new teaching model for resident training in regional anesthesia.

UNLABELLED: The adequacy of resident education in regional anesthesia is of national concern. A teaching model to improve resident training in regional anesthesia was instituted in the Anesthesiology Residency in 1996 at Duke University Health System. The key feature of the model was the use of a CA-3 resident in the preoperative area to perform regional anesthesia techniques. We assessed the success of the new model by comparing the data supplied by the Anesthesiology Residency to the Residency Review Committee for Anesthesiology for the training period July 1992-June 1995 (pre-model) and the training period July 1998-June 2001 (post-model). During the 3-yr training period, the pre-model CA-3 residents (n = 12) performed a cumulative total of 80 (58-105) peripheral nerve blocks (PNBs), 66 (59-74) spinal anesthetics, and 133 (127-142) epidural anesthetics. The CA-3 post-model residents (n = 10) performed 350 (237-408) PNBs, 107 (92-123) spinal anesthetics, and 233 (221-241) epidural anesthetics (P < 0.0001). All results are reported as median (interquartile range). We conclude that our new teaching model using our CA-3 residents as block residents in the preoperative area has increased their clinical exposure to PNBs. IMPLICATIONS: Inadequate exposure to peripheral nerve blocks has been a national problem. A teaching model instituted at Duke University Health System has resulted in a fourfold increase in exposure to peripheral nerve blocks compared with the national averages.