678 research outputs found
Nanoscale Topography and Poroelastic Properties of Model Tissue Breast Gland Basement Membranes
Basement membranes (BMs) are thin layers of condensed extracellular matrix proteins serving as permeability filters, cellular anchoring sites, and barriers against cancer cell invasion. It is believed that their biomechanical properties play a crucial role in determining cellular behavior and response, especially in mechanically active tissues like breast glands. Despite this, so far, relatively little attention has been dedicated to their analysis because of the difficulty of isolating and handling such thin layers of material. Here, we isolated BMs derived from MCF10A spheroids—three-dimensional breast gland model systems mimicking in vitro the most relevant phenotypic characteristics of human breast lobules—and characterized them by atomic force microscopy, enhanced resolution confocal microscopy, and scanning electron microscopy. By performing atomic force microscopy height-clamp experiments, we obtained force-relaxation curves that offered the first biomechanical data on isolated breast gland BMs to our knowledge. Based on enhanced resolution confocal microscopy and scanning electron microscopy imaging data, we modeled the system as a polymer network immersed in liquid and described it as a poroelastic material. Finite-element simulations matching the experimental force-relaxation curves allowed for the first quantification, to our knowledge, of the bulk and shear moduli of the membrane as well as its water permeability. These results represent a first step toward a deeper understanding of the mechanism of tensional homeostasis regulating mammary gland activity as well as its disruption during processes of membrane breaching and metastatic invasion
Ultrasonic Characterization of Ibidi μ-Slide I Luer Channel Slides for Studies With Ultrasound Contrast Agents
Understanding and controlling the ultrasound contrast agent&#x2019;s response to an applied ultrasound pressure field is crucial when investigating ultrasound imaging sequences and therapeutic applications. The magnitude and frequency of the applied ultrasonic pressure waves affect the oscillatory response of the ultrasound contrast agent. Therefore, it is important to have an ultrasound compatible and optically transparent chamber in which the acoustic response of the ultrasound contrast agent can be studied. The aim of our study was to determine the <italic>in-situ</italic> ultrasound pressure amplitude in the ibidi &#x03BC;-slide I Luer channel, an optically transparent chamber suitable for cell culture including culture under flow, for all microchannel heights (200, 400, 600, 800 &#x03BC;m). First, the <italic>in-situ</italic> pressure field in the 800 &#x03BC;m-high channel, was experimentally characterized using Brandaris 128 ultra-high-speed camera recordings of microbubbles and a subsequent iterative processing method, upon insonification at 2 MHz, 45&#x00B0; incident angle, and 50 kPa peak negative pressure. Control studies in another cell culture chamber, the CLINIcell, were compared to the obtained results. The pressure amplitude was &#x2013;3.7 dB with respect to the pressure field without the ibidi &#x03BC;-slide. Second, using finite element analysis, we determined the <italic>in-situ</italic> pressure amplitude in the ibidi with the 800 &#x03BC;m channel (33.1 kPa) which was comparable to the experimental value (34 kPa). The simulations were extended to the other ibidi channel heights (200, 400, 600 &#x03BC;m) with either 35&#x00B0; or 45&#x00B0; incident angle, and at 1 MHz and 2 MHz. The predicted <italic>in-situ</italic> ultrasound pressure fields were between -8.7 dB to -1.1 dB of the incident pressure field depending on the listed configurations of ibidi slides with different channel heights, applied ultrasound frequencies, and incident angles. In conclusion, the determined ultrasound <italic>in-situ</italic> pressures demonstrate the acoustic compatibility of the ibidi &#x03BC;-slide I Luer for different channel heights, thereby showing its potential for studying the acoustic behavior of ultrasound contrast agents for imaging and therapy.</p
Ultrasonic Characterization of Ibidi μ-Slide I Luer Channel Slides for Studies With Ultrasound Contrast Agents
Understanding and controlling the ultrasound contrast agent&#x2019;s response to an applied ultrasound pressure field is crucial when investigating ultrasound imaging sequences and therapeutic applications. The magnitude and frequency of the applied ultrasonic pressure waves affect the oscillatory response of the ultrasound contrast agent. Therefore, it is important to have an ultrasound compatible and optically transparent chamber in which the acoustic response of the ultrasound contrast agent can be studied. The aim of our study was to determine the <italic>in-situ</italic> ultrasound pressure amplitude in the ibidi &#x03BC;-slide I Luer channel, an optically transparent chamber suitable for cell culture including culture under flow, for all microchannel heights (200, 400, 600, 800 &#x03BC;m). First, the <italic>in-situ</italic> pressure field in the 800 &#x03BC;m-high channel, was experimentally characterized using Brandaris 128 ultra-high-speed camera recordings of microbubbles and a subsequent iterative processing method, upon insonification at 2 MHz, 45&#x00B0; incident angle, and 50 kPa peak negative pressure. Control studies in another cell culture chamber, the CLINIcell, were compared to the obtained results. The pressure amplitude was &#x2013;3.7 dB with respect to the pressure field without the ibidi &#x03BC;-slide. Second, using finite element analysis, we determined the <italic>in-situ</italic> pressure amplitude in the ibidi with the 800 &#x03BC;m channel (33.1 kPa) which was comparable to the experimental value (34 kPa). The simulations were extended to the other ibidi channel heights (200, 400, 600 &#x03BC;m) with either 35&#x00B0; or 45&#x00B0; incident angle, and at 1 MHz and 2 MHz. The predicted <italic>in-situ</italic> ultrasound pressure fields were between -8.7 dB to -1.1 dB of the incident pressure field depending on the listed configurations of ibidi slides with different channel heights, applied ultrasound frequencies, and incident angles. In conclusion, the determined ultrasound <italic>in-situ</italic> pressures demonstrate the acoustic compatibility of the ibidi &#x03BC;-slide I Luer for different channel heights, thereby showing its potential for studying the acoustic behavior of ultrasound contrast agents for imaging and therapy.</p
Automated Motion Analysis of Bony Joint Structures from Dynamic Computer Tomography Images: A Multi-Atlas Approach
Dynamic computer tomography (CT) is an emerging modality to analyze in-vivo joint kinematics at the bone level, but it requires manual bone segmentation and, in some instances, landmark identification. The objective of this study is to present an automated workflow for the assessment of three-dimensional in vivo joint kinematics from dynamic musculoskeletal CT images. The proposed method relies on a multi-atlas, multi-label segmentation and landmark propagation framework to extract bony structures and detect anatomical landmarks on the CT dataset. The segmented structures serve as regions of interest for the subsequent motion estimation across the dynamic sequence. The landmarks are propagated across the dynamic sequence for the construction of bone embedded reference frames from which kinematic parameters are estimated. We applied our workflow on dynamic CT images obtained from 15 healthy subjects on two different joints: thumb base (n = 5) and knee (n = 10). The proposed method resulted in segmentation accuracies of 0.90 ± 0.01 for the thumb dataset and 0.94 ± 0.02 for the knee as measured by the Dice score coefficient. In terms of motion estimation, mean differences in cardan angles between the automated algorithm and manual segmentation, and landmark identification performed by an expert were below 1◦. Intraclass correlation (ICC) between cardan angles from the algorithm and results from expert manual landmarks ranged from 0.72 to 0.99 for all joints across all axes. The proposed automated method resulted in reproducible and reliable measurements, enabling the assessment of joint kinematics using 4DCT in clinical routine
Elevated CO\u3csub\u3e2\u3c/sub\u3e and warming shift the functional composition of soil nematode communities in a semiarid grassland
Climate change can alter soil communities and functions, but the consequences are uncertain for most ecosystems. We assessed the impacts of climate change on soil nematodes in a semiarid grassland using a 7-year, factorial manipulation of temperature and [CO2]. Elevated CO2 and warming decreased the abundance of plant-feeding nematodes and nematodes with intermediate to high values on the colonizer-persister scale (cp3-5), including predators and omnivores. Thus, under futuristic climate conditions, nematode communities were even more dominated by r-strategists (cp1-2) that feed on bacteria and fungi. These results indicate that climate change could alter soil functioning in semiarid grasslands. For example, the lower abundance of plant-feeding nematodes could facilitate positive effects of elevated CO2 and warming on plant productivity. The effects of elevated CO2 and warming on nematode functional composition were typically less than additive, highlighting the need for multi-factor studies
Cross-Cultural Adaptation and Validation of the Methotrexate Intolerance Severity Score Questionnaire in Portuguese (Brazil) for Children and Adolescents with Juvenile Idiopathic Arthritis
The Methotrexate (MTX) Intolerance Severity Score (MISS) questionnaire has been developed to identify MTX adverse events in juvenile idiopathic arthritis (JIA). The objective of this study was to translate and validate MISS into Brazilian Portuguese for children and adolescents. The MISS was translated into Portuguese following the standardized guidelines. We analyzed the following psychometric properties: acceptability, internal consistency, test–retest reproducibility, relative–child reliability, and external criterion and discriminant validity. We included 138 JIA patients (age: 8–18 years) and 108 relatives who took less than 5 min to answer MISS. Reproducibility tested after 15 days was good, with a kappa > 0.76. We observed good internal consistency (Cronbach’s coefficient 0.75–0.87 (patients) and 0.75–0.79 (relatives)). Reliability between patients and relatives was good except for stomachache and restlessness. Cut-off points of 5 and 6 had good sensitivity (84 and 71, respectively) and specificity (80 and 87, respectively). Using a cut-off value of 6, we observed 86 (62.3%) MTX-intolerant patients. In conclusion, MISS is a viable and practical tool for routine clinical care to identify MTX intolerance in JIA. Parents do not easily identify stomachache and restlessness as adverse MTX events
The reliability and validity of the juvenile idiopathic arthritis magnetic resonance scoring system for temporomandibular joints
In children with juvenile idiopathic arthritis (JIA), the temporomandibular joint (TMJ) can be involved. To prevent TMJ damage due to inflammation, early recognition is important, for which contrast-enhanced magnetic resonance imaging (MRI) is the gold standard. In this study, the interobserver reliability and construct validity of the Juvenile Idiopathic Arthritis Magnetic Resonance Scoring System for Temporomandibular Joints (JAMRIS-TMJ) was assessed. Two radiologists independently examined 38 MRIs using the JAMRIS-TMJ scoring system. Inter-observer reliability was assessed by Cohen's (weighted) kappa (κ), 95% confidence intervals (CIs) and absolute agreement (%). Construct validity was assessed by correlation between the JAMRIS-TMJ items and TMJ involvement, active maximum interincisal mouth opening (AMIO), and anterior maximum voluntary bite force (AMVBF). The interobserver reliability for the JAMRIS-TMJ items varied from poor to good (κ = 0.18-0.61). Joint enhancement had the highest reliability (κ = 0.61). Correlations were found between TMJ involvement, AMIO, and the JAMRIS-TMJ items, although variation between radiologists and TMJ side existed. No correlation was found between AMVBF and the JAMRIS-TMJ items for both radiologists. The strongest correlations were found between most of the JAMRIS-TMJ items and AMIO. Our findings support the utility of AMIO as a clinical measure of TMJ status in children with JIA
The Genetic Risk for COVID-19 Severity Is Associated With Defective Immune Responses
Recent genome-wide association studies (GWASs) of COVID-19 patients of European ancestry have identified genetic loci significantly associated with disease severity. Here, we employed the detailed clinical, immunological and multi-omics dataset of the Human Functional Genomics Project (HFGP) to explore the physiological significance of the host genetic variants that influence susceptibility to severe COVID-19. A genomics investigation intersected with functional characterization of individuals with high genetic risk for severe COVID-19 susceptibility identified several major patterns: i. a large impact of genetically determined innate immune responses in COVID-19, with ii. increased susceptibility for severe disease in individuals with defective cytokine production; iii. genetic susceptibility related to ABO blood groups is probably mediated through the von Willebrand factor (VWF) and endothelial dysfunction. We further validated these identified associations at transcript and protein levels by using independent disease cohorts. These insights allow a physiological understanding of genetic susceptibility to severe COVID-19, and indicate pathways that could be targeted for prevention and therapy
Automated Motion Analysis of Bony Joint Structures from Dynamic Computer Tomography Images: A Multi-Atlas Approach
Dynamic computer tomography (CT) is an emerging modality to analyze in-vivo joint kinematics at the bone level, but it requires manual bone segmentation and, in some instances, landmark identification. The objective of this study is to present an automated workflow for the assessment of three-dimensional in vivo joint kinematics from dynamic musculoskeletal CT images. The proposed method relies on a multi-atlas, multi-label segmentation and landmark propagation framework to extract bony structures and detect anatomical landmarks on the CT dataset. The segmented structures serve as regions of interest for the subsequent motion estimation across the dynamic sequence. The landmarks are propagated across the dynamic sequence for the construction of bone embedded reference frames from which kinematic parameters are estimated. We applied our workflow on dynamic CT images obtained from 15 healthy subjects on two different joints: thumb base (n = 5) and knee (n = 10). The proposed method resulted in segmentation accuracies of 0.90 ± 0.01 for the thumb dataset and 0.94 ± 0.02 for the knee as measured by the Dice score coefficient. In terms of motion estimation, mean differences in cardan angles between the automated algorithm and manual segmentation, and landmark identification performed by an expert were below 1°. Intraclass correlation (ICC) between cardan angles from the algorithm and results from expert manual landmarks ranged from 0.72 to 0.99 for all joints across all axes. The proposed automated method resulted in reproducible and reliable measurements, enabling the assessment of joint kinematics using 4DCT in clinical routine
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