The virtual microscopy database—sharing digital microscope images for research and education

Peer Reviewedhttps://deepblue.lib.umich.edu/bitstream/2027.42/146335/1/ase1774_am.pdfhttps://deepblue.lib.umich.edu/bitstream/2027.42/146335/2/ase1774.pd

Intracortical Remodeling Parameters Are Associated With Measures of Bone Robustness

Prior work identified a novel association between bone robustness and porosity, which may be part of a broader interaction whereby the skeletal system compensates for the natural variation in robustness (bone width relative to length) by modulating tissue‐level mechanical properties to increase stiffness of slender bones and to reduce mass of robust bones. To further understand this association, we tested the hypothesis that the relationship between robustness and porosity is mediated through intracortical, BMU‐based (basic multicellular unit) remodeling. We quantified cortical porosity, mineralization, and histomorphometry at two sites (38% and 66% of the length) in human cadaveric tibiae. We found significant correlations between robustness and several histomorphometric variables (e.g., % secondary tissue [R 2  = 0.68, P  < 0.004], total osteon area [R 2  = 0.42, P  < 0.04]) at the 66% site. Although these associations were weaker at the 38% site, significant correlations between histological variables were identified between the two sites indicating that both respond to the same global effects and demonstrate a similar character at the whole bone level. Thus, robust bones tended to have larger and more numerous osteons with less infilling, resulting in bigger pores and more secondary bone area. These results suggest that local regulation of BMU‐based remodeling may be further modulated by a global signal associated with robustness, such that remodeling is suppressed in slender bones but not in robust bones. Elucidating this mechanism further is crucial for better understanding the complex adaptive nature of the skeleton, and how interindividual variation in remodeling differentially impacts skeletal aging and an individuals' potential response to prophylactic treatments. Anat Rec, 297:1817–1828, 2014. © 2014 Wiley Periodicals, Inc.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/108629/1/ar22962.pd

Measuring the dynamic mechanical response of hydrated mouse bone by nanoindentation

This study demonstrates a novel approach to characterizing hydrated bone's viscoelastic behavior at lamellar length scales using dynamic indentation techniques. We studied the submicron-level viscoelastic response of bone tissue from two different inbred mouse strains, A/J and B6, with known differences in whole bone and tissue-level mechanical properties. Our results show that bone having a higher collagen content or a lower mineral-to-matrix ratio demonstrates a trend towards a larger viscoelastic response. When normalized for anatomical location relative to biological growth patterns in the antero-medial (AM) cortex, bone tissue from B6 femora, known to have a lower mineral-to-matrix ratio, is shown to exhibit a significantly higher viscoelastic response compared to A/J tissue. Newer bone regions with a higher collagen content (closer to the endosteal edge of the AM cortex) showed a trend towards a larger viscoelastic response. Our study demonstrates the feasibility of this technique for analyzing local composition-property relationships in bone. Further, this technique of viscoelastic nanoindentation mapping of the bone surface at these submicron length scales is shown to be highly advantageous in studying subsurface features, such as porosity, of wet hydrated biological specimens, which are difficult to identify using other methods

Assessment of lamellar level properties in mouse bone utilizing a novel spherical nanoindentation data analysis method

In this work, we demonstrate the viability of using our recently developed data analysis procedures for spherical nanoindentation in conjunction with Raman spectroscopy for studying lamellar-level correlations between the local composition and local mechanical properties in mouse bone. Our methodologies allow us to convert the raw load-displacement datasets to much more meaningful indentation stress–strain curves that accurately capture the loading and unloading elastic moduli, the indentation yield points, as well as the post-yield characteristics in the tested samples. Using samples of two different inbred mouse strains, A/J and C57BL/6J (B6), we successfully demonstrate the correlations between the mechanical information obtained from spherical nanoindentation measurements to the local composition measured using Raman spectroscopy. In particular, we observe that a higher mineral-to-matrix ratio correlated well with a higher local modulus and yield strength in all samples. Thus, new bone regions exhibited lower moduli and yield strengths compared to more mature bone. The B6 mice were also found to exhibit lower modulus and yield strength values compared to the more mineralized A/J strain

Measuring the dynamic mechanical response of hydrated mouse bone by nanoindentation

This study demonstrates a novel approach to characterizing hydrated bone's viscoelastic behavior at lamellar length scales using dynamic indentation techniques. We studied the submicron-level viscoelastic response of bone tissue from two different inbred mouse strains, A/J and B6, with known differences in whole bone and tissue-level mechanical properties. Our results show that bone having a higher collagen content or a lower mineral-to-matrix ratio demonstrates a trend towards a larger viscoelastic response. When normalized for anatomical location relative to biological growth patterns in the antero-medial (AM) cortex, bone tissue from B6 femora, known to have a lower mineral-to-matrix ratio, is shown to exhibit a significantly higher viscoelastic response compared to A/J tissue. Newer bone regions with a higher collagen content (closer to the endosteal edge of the AM cortex) showed a trend towards a larger viscoelastic response. Our study demonstrates the feasibility of this technique for analyzing local composition-property relationships in bone. Further, this technique of viscoelastic nanoindentation mapping of the bone surface at these submicron length scales is shown to be highly advantageous in studying subsurface features, such as porosity, of wet hydrated biological specimens, which are difficult to identify using other methods

An analysis of anatomy education before and during Covid-19: August-December 2020

Coronavirus disease-2019 (Covid-19) disrupted the in-person teaching format of anatomy. To study changes in gross anatomy education that occurred during August-December, 2020 compared to before the pandemic, an online survey was distributed to anatomy educators. The 191 responses received were analyzed in total and by academic program, geographic region, and institution type. Cadaver use decreased overall (before: 74.1 ± 34.1%, during: 50.3 ± 43.0%, P \u3c 0.0001), as well as across allopathic and osteopathic medicine, therapy, undergraduate, and veterinary programs (P \u3c 0.05), but remained unchanged for other programs (P \u3e 0.05). Cadaver use decreased internationally and in the US (P \u3c 0.0001), at public and private (P \u3c 0.0001) institutions, and among allopathic medical programs in Northeastern, Central, and Southern (P \u3c 0.05), but not Western, US geographical regions. Laboratories during Covid-19 were delivered through synchronous (59%), asynchronous (4%), or mixed (37%) formats (P \u3c 0.0001) and utilized digital resources (47%), dissection (32%), and/or prosection (21%) (P \u3c 0.0001). The practical laboratory examination persisted during Covid-19 (P = 0.419); however, the setting and materials shifted to computer-based (P \u3c 0.0001) and image-based (P \u3c 0.0001), respectively. In-person lecture decreased during Covid-19 (before: 88%, during: 24%, P = 0.003). When anatomy digital resources were categorized, dissection media, interactive software, and open-access content increased (P ≤ 0.008), with specific increases in BlueLink, Acland\u27s Videos, and Complete Anatomy (P \u3c 0.05). This study provided evidence of how gross anatomy educators continued to adapt their courses past the early stages of the pandemic

An Analysis of Anatomy Education Before and During Covid-19: May-August 2020.

Coronavirus disease 2019 (Covid-19) created unparalleled challenges to anatomy education. Gross anatomy education has been particularly impacted given the traditional in-person format of didactic instruction and/or laboratory component(s). To assess the changes in gross anatomy lecture and laboratory instruction, assessment, and teaching resources utilized as a result of Covid-19, a survey was distributed to gross anatomy educators through professional associations and listservs. Of the 67 survey responses received for the May-August 2020 academic period, 84% were from United States (US) institutions, while 16% were internationally based. Respondents indicated that in-person lecture decreased during Covid-19 (before: 76%, during: 8%, P \u3c 0.001) and use of cadaver materials declined (before: 76 ± 33%, during: 34 ± 43%, P \u3c 0.001). The use of cadaver materials in laboratories decreased during Covid-19 across academic programs, stand-alone and integrated anatomy courses, and private and public institutions (P ≤ 0.004). Before Covid-19, cadaveric materials used in laboratories were greater among professional health programs relative to medical and undergraduate programs (P ≤ 0.03) and among stand-alone relative to integrated anatomy courses (P ≤ 0.03). Furthermore, computer-based assessment increased (P \u3c 0.001) and assessment materials changed from cadaveric material to images (P \u3c 0.03) during Covid-19, even though assessment structure was not different (P \u3e 0.05). The use of digital teaching resources increased during Covid-19 (P \u3c 0.001), with reports of increased use of in-house created content, BlueLink, and Complete Anatomy software (P \u3c 0.05). While primarily representing US institutions, this study provided evidence of how anatomy educators adapted their courses, largely through virtual mediums, and modified laboratory protocols during the initial emergence of the Covid-19 pandemic