Biology subjects

Emery, N. C.

Publications and source records attributed to Emery, N. C..

4 recordsLinked to original sources

bioRxiv2023

Intervertebral Disc Elastography to Relate Shear Modulus and Relaxometry in Compression and Bending

Intervertebral disc degeneration is the most recognized cause of low back pain, characterized by the decline of tissue structure and mechanics. Image-based mechanical parameters (e.g., strain, stiffness) may provide an ideal assessment of disc function that is lost with degeneration but unfortunately remains underdeveloped. Moreover, it is unknown whether strain or stiffness of the disc may be predicted by MRI relaxometry (e.g. T1 or T2), an increasingly accepted quantitative measure of disc structure. In this study, we quantified T1 and T2 relaxation times and in-plane strains using displacement-encoded MRI within the disc under physiological levels of compression and bending. We then estimated shear modulus in orthogonal image planes and compared these values to relaxation times and strains within regions of the disc. Intratissue strain depended on the loading mode, and shear modulus in the nucleus pulposus was typically an order of magnitude lower than the annulus fibrosis, except in bending, where the apparent stiffness depended on the loading. Relative shear moduli estimated from strain data derived under compression generally did not correspond with those from bending experiments, with no correlations in the sagittal plane and only 4 of 15 regions correlated in the coronal plane, suggesting that future inverse models should incorporate multiple loading conditions. Strain imaging and strain-based estimation of material properties may serve as imaging biomarkers to distinguish healthy and diseased discs. Additionally, image-based elastography and relaxometry may be viewed as complementary measures of disc structure and function to assess degeneration in longitudinal studies.

bioengineering↗

bioRxiv2022

Acellular Cartilage-Bone Allografts Restore Structure, Mechanics, and Surface Properties In Vivo, but Limit Recellularization and Integrative Repair

The repair of articular cartilage after damage is challenging, and clinical interventions to promote regeneration remain elusive. The most effective treatment for cartilage defects utilizes viable osteochondral allografts from young donors, but unfortunately suffers from severe source limitations and short storage time. Decellularized tissue offers the potential to utilize native tissue structure and composition while also overcoming source limitations, but the long-term efficacy of acellular allografts is unknown. Here, we show that acellular osteochondral allografts improve functional and integrative cartilage repair in defect regions after 6 months in a preclinical (sheep) animal model. Functional measures of intratissue strain and structure assessed by MRI demonstrate similar biomechanical performance between implants and native cartilage. Compared to native tissue, the structure, composition, and tribology of acellular allografts conserve surface roughness and lubrication, native cartilage material properties under compression and relaxation, and compositional ratios of collagen:glycosaminoglycan and collagen:phosphate. However, while high cellularity was observed in the integration zones between native cartilage and acellular allografts, recellularization throughout the chondral implant was largely lacking, potentially limiting long-term cellular maintenance in the graft and repair success. Our results advance a suite of joint-to-cellular functional assays, demonstrate the biomechanical efficacy of acellular allografts for at least six months in vivo, and suggest that long-term implant success may suffer from a lack of cell migration into the dense decellularized chondral tissue.

bioengineering↗

bioRxiv2021

Training Data: How can we best prepare instructors to teach data science in undergraduate biology and environmental science courses?

There is a clear and concrete need for greater quantitative literacy in the biological and environmental sciences. Data science training for students in higher education necessitates well-equipped and confident instructors across curricula. However, not all instructors are versed in data science skills or research-based teaching practices. Our study sought to survey the state of data science education across institutions of higher learning, identify instructor needs, and illuminate barriers to teaching data science in the classroom. We distributed a survey to instructors around the world, focused on the United States, and received 106 complete responses. Our results indicate that instructors across institutions use, teach, and view data management, analysis, and visualization as important for students to learn. Code, modeling, and reproducibility were less valued by instructors, although there were differences by institution type (doctoral, masters, or baccalaureate), and career stage (time since terminal degree). While there were a variety of barriers highlighted by respondents, instructor background, student background, and space in the curriculum were the greatest barriers of note. Interestingly, instructors were most interested in receiving training for how to teach code and data analysis in the undergraduate classroom. Our study provides an important window into how data science is taught in higher education as well as suggestions for how we can best move forward with empowering instructors across disciplines.

scientific communication and education↗

bioRxiv2019

Longitudinal study of persistence in professional development outcomes of early career biology faculty

The diversity of teaching professional development (PD) programs that occurred over the last few decades merits our collective attention to assess the impact of these programs over time. In general, the goal of PD programs is that participants continue to practice what they learn in the long term. However, we do not know the degree to which the outcomes of these programs were achieved and ultimately persist. We tracked postdoc participants from the Faculty Institutes for Reformed Science Teaching (FIRST) IV program into their current position as early-career faculty at institutions across the United States. We assessed their teaching approaches, practices, and student perceptions of the learning environment over 6-10 years. Additionally, the FIRST IV faculty were paired with colleagues of similar status in the same departments. We found that professional development outcomes from the FIRST IV program persisted over time and across a significant career transition, from postdoc to faculty. These participants not only maintained their student-centered practices, but were significantly more student-focused than their peers. Lastly, we found that faculty approaches to teaching were correlated with observed teaching practices in the classroom for both groups of faculty. These results provide compelling evidence for the success of the FIRST IV program and the long-term persistence of professional development outcomes.

scientific communication and education↗