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Abstract Measurement of auricle parameters for planning and post-operative evaluation presents substantial challenges due to the complex 3D structure of the human auricle. Traditional measurement methods rely on manual techniques, resulting in limited precision. This study introduces a novel automated surface-based three-dimensional measurement method for quantifying human auricle parameters. The method was applied to virtual auricles reconstructed from Computed Tomography (CT) scans of a cadaver head and subsequent measurement of important clinically relevant aesthetical auricular parameters (length, width, protrusion, position, auriculocephalic angle, and inclination angle). Reference measurements were done manually (using a caliper and using a 3D landmarking method) and measurement precision was compared to the automated method. The CT scans were performed using both a contemporary high-end and a low-end CT scanner. Scans were conducted at a standard scanning dose, and at half the dose. The automatic method demonstrated significantly higher precision in measuring auricle parameters compared to manual methods. Compared to traditional manual measurements, precision improved for auricle length (9×), width (5×), protrusion (5×), Auriculocephalic Angle (5–54×) and posteroanterior position (23×). Concerning parameters without comparison with a manual method, the precision level of supero-inferior position was 0.489 mm; and the precisions of the inclination angle measurements were 1.365 mm and 0.237 mm for the two automated methods investigated. Improved precision of measuring auricle parameters was associated with using the high-end scanner. A higher dose was only associated with a higher precision for the left auricle length. The findings of this study emphasize the advantage of automated surface-based auricle measurements, showcasing improved precision compared to traditional methods. This novel algorithm has the potential to enhance auricle reconstruction and other applications in plastic surgery, offering a promising avenue for future research and clinical application.

Abstract An oblique double-cut rotation osteotomy (ODCRO) enables correcting a complex bone deformation by aligning, in 3D, the distal, middle and proximal bone segments with a target bone, without intersegmental gaps. We propose virtual preoperative planning of an ODCRO. To minimize a residual translation error, we use an optimization algorithm and optimize towards bone length, alignment in the transverse direction, or a balanced reconstruction. We compare the residual alignment error with an oblique single-cut rotation osteotomy using 15 complex bone deformations. The single-cut approach was not feasible in 5 cases, whereas the ODCRO procedure was feasible in all cases. The residual alignment error was smaller for the ODCRO than for the single-cut approach except for one case. In a subset for length reconstruction, the length error of 7.3–21.3 mm was restored to 0.0 mm in 4 of 5 cases, although at the cost of an increased transverse translation. The proposed method renders planning an ODCRO feasible and helps restoring bone alignment and lengthening better than an oblique single-cut rotation osteotomy. Awareness of the challenges and possibilities in preoperative planning of an ODCRO will be of value for future alignment surgery and for patients.

Background Hyperthermic intraperitoneal chemotherapy (HIPEC) is administered to treat residual microscopic disease after cytoreductive surgery (CRS). During HIPEC, fluid (41–43 °C) is administered and drained through a limited number of catheters, risking thermal and drug heterogeneities within the abdominal cavity that might reduce effectiveness. Treatment planning software provides a unique tool for optimizing treatment delivery. This study aimed to investigate the influence of treatment-specific parameters on the thermal and drug homogeneity in the peritoneal cavity in a computed tomography based rat model. Method We developed computational fluid dynamics (CFD) software simulating the dynamic flow, temperature and drug distribution during oxaliplatin based HIPEC. The influence of location and number of catheters, flow alternations and flow rates on peritoneal temperature and drug distribution were determined. The software was validated using data from experimental rat HIPEC studies. Results The predicted core temperature and systemic oxaliplatin concentration were comparable to the values found in literature. Adequate placement of catheters, additional inflow catheters and higher flow rates reduced intraperitoneal temperature spatial variation by −1.4 °C, −2.3 °C and −1.2 °C, respectively. Flow alternations resulted in higher temperatures (up to +1.5 °C) over the peritoneal surface. Higher flow rates also reduced the spatial variation of chemotherapy concentration over the peritoneal surface resulting in a more homogeneous effective treatment dose. Conclusion The presented treatment planning software provides unique insights in the dynamics during HIPEC, which enables optimization of treatment-specific parameters and provides an excellent basis for HIPEC treatment planning in human applications.

Mitochondrial neurogastrointestinal encephalomyopathy (MNGIE) is a rare autosomal metabolic disorder caused by thymidine phosphorylase (TP) deficiency. Successful therapeutic interventions for this disease rely on a means for efficient and long-lasting circulation of the TP enzyme. In this study we exploit lentiviral transduction of hematopoietic stem cells and an erythroid cell line (BEL-A) to generate reticulocytes that contain active TP. Significant loss of overexpressed TP during erythroid differentiation can be reduced by addition of the ubiquitination inhibitor MG132. However, the ubiquitination sites are located in the substrate binding site in human TP, and their removal abolished enzyme activity. Examination of the TP structure and mechanism suggested that these sites are only exposed in the absence of substrate. We show that supplementation of culture media with thymidine during differentiation reduces enzyme degradation, doubling the amount of TP retained in reticulocytes. This study provides proof of principle that therapeutic reticulocytes expressing TP can be generated in vitro and that ubiquitin-mediated degradation can be subverted through masking ubiquitination sites to ensure retention of human TP in reticulocytes following erythroid differentiation.

Abstract Background Foot and ankle joint kinematics are measured during clinical gait analyses with marker‐based multi‐segment foot models. To improve on existing models, measurement errors due to soft tissue artifacts (STAs) and marker misplacements should be reduced. Therefore, the aim of this study is to define a clinically informed, universally applicable multi‐segment foot model, which is developed to minimize these measurement errors. Methods The Amsterdam foot model (AFM) is a follow‐up of existing multi‐segment foot models. It was developed by consulting a clinical expert panel and optimizing marker locations and segment definitions to minimize measurement errors. Evaluation of the model was performed in three steps. First, kinematic errors due to STAs were evaluated and compared to two frequently used foot models, i.e. the Oxford and Rizzoli foot models (OFM, RFM). Previously collected computed tomography data was used of 15 asymptomatic feet with markers attached, to determine the joint angles with and without STAs taken into account. Second, the sensitivity to marker misplacements was determined for AFM and compared to OFM and RFM using static standing trials of 19 asymptomatic subjects in which each marker was virtually replaced in multiple directions. Third, a preliminary inter‐ and intra‐tester repeatability analysis was performed by acquiring 3D gait analysis data of 15 healthy subjects, who were equipped by two testers for two sessions. Repeatability of all kinematic parameters was assessed through analysis of the standard deviation (σ) and standard error of measurement (SEM). Results The AFM was defined and all calculation methods were provided. Errors in joint angles due to STAs were in general similar or smaller in AFM (≤2.9°) compared to OFM (≤4.0°) and RFM (≤6.7°). AFM was also more robust to marker misplacement than OFM and RFM, as a large sensitivity of kinematic parameters to marker misplacement (i.e. > 1.0°/mm) was found only two times for AFM as opposed to six times for OFM and five times for RFM. The average intra‐tester repeatability of AFM angles was σ:2.2[0.9°], SEM:3.3 ± 0.9° and the inter‐tester repeatability was σ:3.1[2.1°], SEM:5.2 ± 2.3°. Conclusions Measurement errors of AFM are smaller compared to two widely‐used multi‐segment foot models. This qualifies AFM as a follow‐up to existing foot models, which should be evaluated further in a range of clinical application areas.

Background: The detection and localization of electrophysiological substrates currently involve invasive cardiac mapping. Electrocardiographic imaging (ECGI) using the equivalent dipole layer (EDL) method allows the noninvasive estimation of endocardial and epicardial activation and repolarization times (AT and RT), but the RT validation is limited to in silico studies. We aimed to assess the temporal and spatial accuracy of the EDL method in reconstructing the RTs from the surface ECG under physiological circumstances and situations with artificially induced increased repolarization heterogeneity.Methods: In four Langendorff-perfused pig hearts, we simultaneously recorded unipolar electrograms from plunge needles and pseudo-ECGs from a volume-conducting container equipped with 61 electrodes. The RTs were computed from the ECGs during atrial and ventricular pacing and compared with those measured from the local unipolar electrograms. Regional RT prolongation (cooling) or shortening (pinacidil) was achieved by selective perfusion of the left anterior descending artery (LAD) region.Results: The differences between the computed and measured RTs were 19.0 ± 17.8 and 18.6 ± 13.7 ms for atrial and ventricular paced beats, respectively. The region of artificially delayed or shortened repolarization was correctly identified, with minimum/maximum RT roughly in the center of the region in three hearts. In one heart, the reconstructed region was shifted by ~2.5 cm. The total absolute difference between the measured and calculated RTs for all analyzed patterns in selectively perfused hearts (n = 5) was 39.6 ± 27.1 ms.Conclusion: The noninvasive ECG repolarization imaging using the EDL method of atrial and ventricular paced beats allows adequate quantitative reconstruction of regions of altered repolarization.

Abstract: The capacity to undergo substantial deformation is a defining characteristic of the red blood cell (RBC), facilitating transit through the splenic interendothelial slits and microvasculature. Establishment of this remarkable property occurs during a process of reticulocyte maturation that begins with egress through micron-wide pores in the bone marrow and is completed within the circulation. The requirement to undertake repeated cycles of deformation necessitates that both reticulocytes and erythrocytes regulate membrane-cytoskeletal protein interactions in order to maintain cellular stability. In the absence of transcriptional activity, modulation of these interactions in RBCs is likely to be achieved primarily through specific protein posttranslational modifications, which at present remain undefined. In this study, we use high-throughput methods to define the processes that underlie the response to deformation and shear stress in both reticulocytes and erythrocytes. Through combination of a bead-based microsphiltration assay with phosphoproteomics we describe posttranslational modification of RBC proteins associated with deformation. Using microsphiltration and microfluidic biochip-based assays, we explore the effect of inhibiting kinases identified using this dataset. We demonstrate roles for GSK3 and Lyn in capillary transit and maintenance of membrane stability following deformation and show that combined inhibition of these kinases significantly decreases reticulocyte capacity to undergo repeated deformation. Finally, we derive a comprehensive and integrative phosphoproteomic dataset that provides a valuable resource for further mechanistic dissection of the molecular pathways that underlie the RBC's response to mechanical stimuli and for the study of reticulocyte maturation.

The process of maturation of reticulocytes into fully mature erythrocytes that occurs in the circulation is known to be characterized by a complex interplay between loss of cell surface area and volume, removal of remnant cell organelles and redundant proteins, and highly selective membrane and cytoskeletal remodeling. However, the mechanisms that underlie and drive these maturational processes in vivo are currently poorly understood and, at present, reticulocytes derived through in vitro culture fail to undergo the final transition to erythrocytes. Here, we used high-throughput proteomic methods to highlight differences between erythrocytes, cultured reticulocytes and endogenous reticulocytes. We identify a cytoskeletal protein, non-muscle myosin IIA (NMIIA) whose abundance and phosphorylation status differs between reticulocytes and erythrocytes and localized it in the proximity of autophagosomal vesicles. An ex vivo circulation system was developed to simulate the mechanical shear component of circulation and demonstrated that mechanical stimulus is necessary, but insufficient for reticulocyte maturation. Using this system in concurrence with non-muscle myosin II inhibition, we demonstrate the involvement of non-muscle myosin IIA in reticulocyte remodeling and propose a previously undescribed mechanism of shear stress-responsive vesicle clearance that is crucial for reticulocyte maturation.

A rigid surface–volume registration scheme is presented in this study to register computed tomography (CT) and free-hand tracked ultrasound (US) images of the talocrural joint. Prior to registration, bone surfaces expected to be visible in US are extracted from the CT volume and bone contours in 2D US data are enhanced based on monogenic signal representation of 2D US images. A 3D monogenic signal data is reconstructed from the 2D data using the position of the US probe recorded with an optical tracking system. When registering the surface extracted from the CT scan to the monogenic signal feature volume, six transformation parameters are estimated so as to optimize the sum of monogenic signal features over the transformed surface. The robustness of the registration algorithm was tested on a dataset collected from 12 cadaveric ankles. The proposed method was used in a clinical case study to investigate the potential of US imaging for pre-operative planning of arthroscopic access to talar (osteo)chondral defects (OCDs). The results suggest that registrations with a registration error of 2 mm and less is achievable, and US has the potential to be used in assessment of an OCD’ arthroscopic accessibility, given the fact that 51% of the talar surface could be visualized.