Subject-Specific Finite Element Modeling of the Tibiofemoral Joint in Vivo: Development, Verification and Application

A new methodology for subject-specific finite element (FE) modeling of the tibiofemoral (TF) joint based on in vivo computed tomography (CT), magnetic resonance imaging (MRI), and dynamic stereo-radiography (DSX) data is presented. Two techniques to incorporate in vivo skeletal kinematics as FE boundary conditions were implemented and compared: one used MRI-measured tibiofemoral kinematics in a non-weight-bearing supine position and allowed five degrees of freedom at the joint in response to an axially applied force; the other used DSX-measured tibiofemoral kinematics in a weight-bearing standing position and permitted only axial translation in response to the same force. The model-predicted cartilage-cartilage contact areas were examined against ‘benchmarks’ from a novel in situ contact area analysis (ISCAA) in which the intersection volume between non-deformed femoral and tibial cartilage was characterized to determine the contact. The results showed that the DSX-based model predicted contact areas in close alignment with the benchmarks, and outperformed the MRI-based model. The importance of accurate, task-specific skeletal kinematics in subject-specific FE modeling and the necessity of subject-specific verification are discussed. A study of the effects of partial meniscectomy on the intra-articular contact mechanics was then conducted as an illustration of application of the verified models. A musculoskeletal dynamic model was used to generate the knee joint forces as boundary conditions for the above developed FE models. Thus, a sequence of quasi-static position-dependent FE models was developed for a series of time points throughout a decline walking task. These time points include heel-strike and in increments of 0.05 seconds up to 0.30 seconds, and additionally, the time points of the two peak compressive joint force values for each knee. Several factors were observed to measure the effects on intra-articular contact mechanics. The greatest maximum compressive stress was recorded in the partially meniscectomized compartment or in the opposite compartment of the contralateral knee throughout all time points. The significance of the application of the FE models for evaluation of the biomechanical effects of meniscectomy is demonstrated, and the importance of simultaneously observing joint kinematics and intra-articular contact mechanics at more than one time point during a dynamic task is discussed

Chiasma

Newspaper reporting on events at the Boston University School of Medicine in the 1960s

Cavitation in soft matter

Cavitation is the sudden, unstable expansion of a void or bubble within a liquid or solid subjected to a negative hydrostatic stress. Cavitation rheology is a field emerging from the development of a suite of materials characterization, damage quantification, and therapeutic techniques that exploit the physical principles of cavitation. Cavitation rheology is inherently complex and broad in scope with wide-ranging applications in the biology, chemistry, materials, and mechanics communities. This perspective aims to drive collaboration among these communities and guide discussion by defining a common core of high-priority goals while highlighting emerging opportunities in the field of cavitation rheology. A brief overview of the mechanics and dynamics of cavitation in soft matter is presented. This overview is followed by a discussion of the overarching goals of cavitation rheology and an overview of common experimental techniques. The larger unmet needs and challenges of cavitation in soft matter are then presented alongside specific opportunities for researchers from different disciplines to contribute to the field

Magneto-Driven Gradients of Diamagnetic Objects for Engineering Complex Tissues

Engineering complex tissues represents an extraordinary challenge and, to date, there have been few strategies developed that can easily recapitulate native‐like cell and biofactor gradients in 3D materials. This is true despite the fact that mimicry of these gradients may be essential for the functionality of engineered graft tissues. Here, a non‐traditional magnetics‐based approach is developed to predictably position naturally diamagnetic objects in 3D hydrogels. Rather than magnetizing the objects within the hydrogel, the magnetic susceptibility of the surrounding hydrogel precursor solution is enhanced. In this way, a range of diamagnetic objects (e.g., polystyrene beads, drug delivery microcapsules, and living cells) are patterned in response to a brief exposure to a magnetic field. Upon photo‐crosslinking the hydrogel precursor, object positioning is maintained, and the magnetic contrast agent diffuses out of the hydrogel, supporting long‐term construct viability. This approach is applied to engineer cartilage constructs with a depth‐dependent cellularity mirroring that of native tissue. These are thought to be the first results showing that magnetically unaltered cells can be magneto‐patterned in hydrogels and cultured to generate heterogeneous tissues. This work provides a foundation for the formation of opposing magnetic‐susceptibility‐based gradients within a single continuous material

Molecular profiling of multiplexed gene markers to assess viability of ex vivo human colon explant cultures

© Janice E. Drew et al. 2015; Published by Mary Ann Liebert, Inc. This Open Access article is distributed under the terms of the Creative Commons License (http://creativecommons.org/licenses/by/4.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly credited. Acknowledgments The authors would like to thank the patients who kindly donated tissue samples, Sally Chalmers of the Tayside Tissue Bank for her help with collecting of the tissue donor samples, Emma Moss for advice on human colon dissection and explant culture, and Claus Dieter Mayer, Biomathematics and Statistics Scotland, for advice on statistical analysis. This work was supported by the Scottish Government (GT403), Scottish Universities Life Science Alliance, and TENOVUS Scotland.Peer reviewedPublisher PD

Predictive gene signatures:molecular markers distinguishing colon adenomatous polyp and carcinoma

Funding: This study was supported by the Scottish Government's Rural and Environment Science and Analytical Services Division Food, Land and People Programme GT403 (http://www.scotland.gov.uk/Topics/Research/About/EBAR/StrategicResearch/future-research-strategy/Themes), Scottish Universities Life Science Alliance Translational Biology Studentship 10/09, (http://www.sulsa.ac.uk/), NHS Grampian Endowment Fund 12/07 (http://www.nhsgrampian.co.uk/nhsgrampian/gra_display_hospital.jsp?pContentID=65&p_applic=CCC&p_service=Content.show&). The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript. Data Availability: The authors confirm that all data underlying the findings are fully available without restriction. All relevant data are within the paper and its Supporting Information files.Peer reviewedPublisher PD

Impact of Riparian Grass Filter Strips on Surface-Water Quality

The effectiveness of natural riparian grass filter strips in removing sediment and agricultural chemicals from surface runoff was studied using no-tillage and conventional-tillage erosion plots. Runoff from the tillage plots was directed onto 4.57, 9.14, and 13.72 m (15, 30, and 45 ft.) length filter strips, where the inflow and outflow concentrations and sediment size distributions were measured. Trapping efficiencies for sediment and agricultural chemicals typically ranged near or above 90 percent, mainly because of high infiltration rates. The filters also significantly reduced peak discharge concentrations, which reduced the impact of sediment and agricultural chemicals on receiving surface waters

Changes in suspected adverse drug reaction reporting via the Yellow Card scheme in Wales following the introduction of a National Reporting Indicator

AIMS: This study aimed to assess the impact of a National Reporting Indicator (NRI) on rates of reporting of suspected adverse drug reactions using the Yellow Card scheme following the introduction of the NRI in Wales (UK) in April 2014. METHODS: Yellow Card reporting data for general practitioners and other reporting groups in Wales and England for the financial years 2014–15 (study period 1) and 2015–16 (study period 2) were obtained from the Medicines and Healthcare Products Regulatory Agency and compared with those for 2013–14 (pre‐NRI control period). RESULTS: The numbers of Yellow Cards submitted by general practitioners in Wales were 271, 665 and 870 in the control period, study period 1 and study period 2, respectively. This is equivalent to an increase of 145% in study period 1 and 221% in study period 2 compared with the 12‐month control period (2013–14). Corresponding increases in England were 17% and 37%, respectively (P < .001 chi–squared test). The numbers of Yellow Cards submitted by other groups in Wales were 906, 795 and 947 in each of the study periods. CONCLUSIONS: Introduction of the NRI corresponded with a significant increase in the number of Yellow Cards submitted by general practitioners in Wales. General practitioner reporting rates continued to increase year on year through to 2018–19 with the NRI still in place. No concomitant change was found in reporting rates by other groups in the health boards in Wales