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Magnetic ratcheting cytometry is a promising approach to separate magnetically-labeled cells and magnetic particles based on the quantity of magnetic material. We have previously reported on the ability of this technique to separate magnetically-labeled cells. Here, with a new chip design, containing high aspect ratio permalloy micropillar arrays, we demonstrate the ability of this technique to rapidly concentrate and collect superparamagnetic iron oxide particles. The platform consists of a mechatronic wheel used to generate and control a cycling external magnetic field that impinges on a “ratcheting chip.” The ratcheting chip is created by electroplating a 2D array of high aspect ratio permalloy micropillars onto a glass slide, which is embedded in a thin polymer layer to create a planar surface above the micropillars. By varying magnetic field frequency and direction through wheel rotation rate and angle, we direct particle movement on chip. We explore the operating conditions for this system, identifying the effects of varying ratcheting frequency, along with time, on the dynamics and resulting concentration of these magnetic particles. We also demonstrate the ability of the system to rapidly direct the movement of superparamagnetic iron oxide particles of varying sizes. Using this technique, 2.8 μm, 500 nm, and 100 nm diameter superparamagnetic iron oxide particles, suspended within an aqueous fluid, were concentrated. We further define the ability of the system to concentrate 2.8 μm superparamagnetic iron oxide particles, present in a liquid suspension, into a small chip surface area footprint, achieving a 100-fold surface area concentration, and achieving a concentration factor greater than 200%. The achieved concentration factor of greater than 200% could be greatly increased by reducing the amount of liquid extracted at the chip outlet, which would increase the ability of achieving highly sensitive downstream analytical techniques. Magnetic ratcheting-based enrichment may be useful in isolating and concentrating subsets of magnetically-labeled cells for diagnostic automation.

OBJECTIVE Twin vaginal deliveries (VDs) are often performed in the operating room (OR) given the risk of conversion to cesarean delivery (CD) for the aftercoming twin. We aim to investigate the rates of conversion to CD for planned twin VDs and identify predictors and outcomes of conversion. STUDY DESIGN A retrospective cohort study of all women who underwent a planned twin VD at two large academic medical centers over 4 years. Demographic and outcome data were chart abstracted. Various statistical tests were used to evaluate the influence of perinatal variables on mode of delivery and identify possible predictors of conversion. RESULTS Eight hundred and eighty-five twin deliveries were identified, of which 725 (81.9%) were possible candidates for VD. Of those, 237 (32.7%) underwent successful VD of twin A. Ninety-five (40.1%) had a nonvertex second twin at time of delivery. Conversion to CD occurred in 10 planned VDs (4.2%). Conversions were higher with spontaneous labor (relative risk [RR]: 2.1; 95% confidence interval [CI] 1.6-2.7; p = 0.003), and having an intertwin delivery interval greater than 60 minutes (RR: 5.1; 95% CI: 2.5-10.8; p

The mechanical phenotype of a cell is an inherent biophysical marker of its state and function, with many applications in basic and applied biological research. Microfluidics-based methods have enabled single-cell mechanophenotyping at throughputs comparable to those of flow cytometry. Here, we present a standardized cross-laboratory study comparing three microfluidics-based approaches for measuring cell mechanical phenotype: constriction-based deformability cytometry (cDC), shear flow deformability cytometry (sDC) and extensional flow deformability cytometry (xDC). All three methods detect cell deformability changes induced by exposure to altered osmolarity. However, a dose-dependent deformability increase upon latrunculin B-induced actin disassembly was detected only with cDC and sDC, which suggests that when exposing cells to the higher strain rate imposed by xDC, cellular components other than the actin cytoskeleton dominate the response. The direct comparison presented here furthers our understanding of the applicability of the different deformability cytometry methods and provides context for the interpretation of deformability measurements performed using different platforms. This Analysis compares microfluidics-based methods for assessing mechanical properties of cells in high throughput.

The asthma-obesity syndrome represents a major public health concern that disproportionately contributes to asthma severity and induces insensitivity to therapy. To date, no study has shown an intrinsic difference between human airway smooth muscle (HASM) cells derived from nonobese subjects and those derived from obese subjects. The objective of this study was to address whether there is a greater response to agonist-induced calcium mobilization, phosphorylation of myosin light chain (MLC), and greater shortening in HASM cells derived from obese subjects. HASM cells derived from nonobese and obese subjects were age and sex matched. Phosphorylation of MLC was measured after having been stimulated by carbachol. Carbachol- or histamine-induced mobilization of calcium and cell shortening were assessed in HASM cells derived from nonobese and obese donors. Agonist-induced MLC phosphorylation, mobilization of calcium, and cell shortening were greater in obese compared with non-obese-derived HASM cells. The MLC response was comparable in HASM cells derived from obese nonasthma and nonobese fatal asthma subjects. HASM cells derived from obese female subjects were more responsive to carbachol than HASM cells derived from obese male subjects. Insulin pretreatment had little effect on these responses. Our results show an increase in agonist-induced calcium mobilization associated with an increase in MLC phosphorylation and an increase in ASM cell shortening in favor of agonist-induced hyperresponsiveness in HASM cells derived from obese subjects. Our studies suggest that obesity induces a retained phenotype of hyperresponsiveness in cultured human airway smooth muscle cells.

PurposeTo design and validate a fully automated computer system for the detection and anatomic localization of traumatic thoracic and lumbar vertebral body fractures at computed tomography (CT).Materials and methodsThis retrospective study was HIPAA compliant. Institutional review board approval was obtained, and informed consent was waived. CT examinations in 104 patients (mean age, 34.4 years; range, 14-88 years; 32 women, 72 men), consisting of 94 examinations with positive findings for fractures (59 with vertebral body fractures) and 10 control examinations (without vertebral fractures), were performed. There were 141 thoracic and lumbar vertebral body fractures in the case set. The locations of fractures were marked and classified by a radiologist according to Denis column involvement. The CT data set was divided into training and testing subsets (37 and 67 subsets, respectively) for analysis by means of prototype software for fully automated spinal segmentation and fracture detection. Free-response receiver operating characteristic analysis was performed.ResultsTraining set sensitivity for detection and localization of fractures within each vertebra was 0.82 (28 of 34 findings; 95% confidence interval [CI]: 0.68, 0.90), with a false-positive rate of 2.5 findings per patient. The sensitivity for fracture localization to the correct vertebra was 0.88 (23 of 26 findings; 95% CI: 0.72, 0.96), with a false-positive rate of 1.3. Testing set sensitivity for the detection and localization of fractures within each vertebra was 0.81 (87 of 107 findings; 95% CI: 0.75, 0.87), with a false-positive rate of 2.7. The sensitivity for fracture localization to the correct vertebra was 0.92 (55 of 60 findings; 95% CI: 0.79, 0.94), with a false-positive rate of 1.6. The most common cause of false-positive findings was nutrient foramina (106 of 272 findings [39%]).ConclusionThe fully automated computer system detects and anatomically localizes vertebral body fractures in the thoracic and lumbar spine on CT images with a high sensitivity and a low false-positive rate.

Here we highlight emerging technologies in the synthesis, handling, and application of encoded microparticles for multiplexed assays. Traditionally, in drug discovery and life sciences research, multiple reactions will be conducted in parallel using microwell plate formats or microfluidic implementations, in which volumes are confined and reactions annotated by knowledge of what reagents were added to each volume. Microparticle-based information carriers provide an alternative approach to performing such multiplexed reactions, in which reactions and events are instead annotated with unique codes associated with the solid-phase particle. One challenge has been in creating a unique and large enough code set that is also easily readout, and we highlight two approaches that have brought orthogonal optical tagging techniques to bear. Another challenge has been that in such approaches, reactions have usually been confined to the surface of, or within the bulk of the specifically-tagged particle. We also highlight a creative approach and strategy for multiplexing – called “partipetting” – in which the coded particle can be a carrier of a unique fluid reagent.

The vertebral body is the main axial load-bearing structure of the spinal vertebra. Assessment of acute injury and chronic deformity of the vertebral body is difficult to assess accurately and quantitatively by simple visual inspection. We propose a cortical shell unwrapping method to examine the vertebral body for injury such as fractures and degenerative osteophytes. The spine is first segmented and partitioned into vertebrae. Then the cortical shell of the vertebral body is extracted using deformable dual-surface models. The cortical shell is then unwrapped onto a 2D map and the complex 3D detection problem is effectively converted to a pattern recognition problem on a 2D plane. Characteristic features adapted for different applications are computed and sent to a committee of support vector machines for classification. The system was evaluated on two applications, one for fracture detection on trauma CT datasets and the other on degenerative osteophyte assessment on sodium fluoride PET/CT. The fracture CAD achieved 93.6% sensitivity at 3.2 false positive per patient and the degenerative osteophyte CAD achieved 82% sensitivity at 4.7 false positive per patient.

Assessment of trauma patients with multiple injuries can be one of the most clinically challenging situations dealt with by the radiologist. We propose a fully automated method to detect acute vertebral body fractures on trauma CT studies. The spine is first segmented and partitioned into vertebrae. Then the cortical shell of the vertebral body is extracted using deformable dual-surface models. The extracted cortical shell is unwrapped onto a 2D map effectively converting a complex 3D fracture detection problem into a pattern recognition problem of fracture lines on a 2D plane. Twenty-eight features are computed for each fracture line and sent to a committee of support vector machines for classification. The system was tested on 18 trauma CT datasets and achieved 95.3% sensitivity and 1.7 false positives per case by leave-one-out cross validation.