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Panagiotopoulou O, Iriarte-Diaz J, Abraha HM, Taylor AB, Wilshin S, Dechow PC, Ross CF. Corrigendum to "Biomechanics of the mandible of Macaca mulatta during the power stroke of mastication: Loading, deformation, and strain regimes and the impact of food type" [Journal of Human Evolution 147 (2020) 102865]. J Hum Evol 2023; 179:103367. [PMID: 37084622 PMCID: PMC10627476 DOI: 10.1016/j.jhevol.2023.103367] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 04/23/2023]
Affiliation(s)
- Olga Panagiotopoulou
- Department of Anatomy & Developmental Biology, Monash Biomedicine Discovery Institute, Faculty of Medicine Nursing and Health Sciences, Monash University, Clayton, Melbourne, Victoria, 3800, Australia.
| | - Jose Iriarte-Diaz
- Department of Biology, University of the South, Sewanee, TN, 37383, USA
| | - Hyab Mehari Abraha
- Department of Anatomy & Developmental Biology, Monash Biomedicine Discovery Institute, Faculty of Medicine Nursing and Health Sciences, Monash University, Clayton, Melbourne, Victoria, 3800, Australia
| | - Andrea B Taylor
- Department of Basic Science, Touro University, CA, 94592, USA
| | - Simon Wilshin
- Comparative Biomedical Sciences, The Royal Veterinary College, Hawkshead Lane, Herts, AL97TA, UK
| | - Paul C Dechow
- Department of Biomedical Sciences, Texas A&M University College of Dentistry, Dallas, TX, 75246, USA
| | - Callum F Ross
- Department of Organismal Biology and Anatomy, University of Chicago, Chicago, IL, 60637, USA.
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Haravu PN, Abraha HM, Shang M, Iriarte-Diaz J, Taylor AB, Reid RR, Ross CF, Panagiotopoulou O. Macaca mulatta is a good model for human mandibular fixation research. R Soc Open Sci 2022; 9:220438. [PMID: 36405636 PMCID: PMC9667141 DOI: 10.1098/rsos.220438] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 04/05/2022] [Accepted: 10/26/2022] [Indexed: 06/16/2023]
Abstract
Biomechanical and clinical studies have yet to converge on the optimal fixation technique for angle fractures, one of the most common and controversial fractures in terms of fixation approach. Prior pre-clinical studies have used a variety of animal models and shown abnormal strain environments exacerbated by less rigid (single-plate) Champy fixation and chewing on the side opposite the fracture (contralateral chewing). However, morphological differences between species warrant further investigation to ensure that these findings are translational. Here we present the first study to use realistically loaded finite-element models to compare the biomechanical behaviour of human and macaque mandibles pre- and post-fracture and fixation. Our results reveal only small differences in deformation and strain regimes between human and macaque mandibles. In the human model, more rigid biplanar fixation better approximated physiologically healthy global bone strains and moments around the mandible, and also resulted in less interfragmentary strain than less rigid Champy fixation. Contralateral chewing exacerbated deviations in strain, moments and interfragmentary strain, especially under Champy fixation. Our pre- and post-fracture fixation findings are congruent with those from macaques, confirming that rhesus macaques are excellent animal models for biomedical research into mandibular fixation. Furthermore, these findings strengthen the case for rigid biplanar fixation over less rigid one-plate fixation in the treatment of isolated mandibular angle fractures.
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Affiliation(s)
- Pranav N. Haravu
- Department of Surgery, Section of Plastic Surgery, The University of Chicago Medical Centre, Chicago, IL, USA
| | - Hyab Mehari Abraha
- Monash Biomedicine Discovery Institute, Department of Anatomy and Developmental Biology, Monash University, Victoria, Australia
| | - Michelle Shang
- Department of Surgery, Section of Plastic Surgery, The University of Chicago Medical Centre, Chicago, IL, USA
| | - Jose Iriarte-Diaz
- Department of Biology, The University of the South, Sewanee, TN, USA
| | | | - Russell R. Reid
- Department of Surgery, Section of Plastic Surgery, The University of Chicago Medical Centre, Chicago, IL, USA
| | - Callum F. Ross
- Department of Organismal Biology and Anatomy, University of Chicago, Chicago, IL, USA
| | - Olga Panagiotopoulou
- Monash Biomedicine Discovery Institute, Department of Anatomy and Developmental Biology, Monash University, Victoria, Australia
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Antony I, Mehari Abraha H, Hameed A, Conway C. A European update on transcatheter aortic valve implantation (TAVI) in the COVID era. J Anat 2022; 242:50-63. [PMID: 36152032 PMCID: PMC9773167 DOI: 10.1111/joa.13740] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/28/2021] [Revised: 07/26/2022] [Accepted: 07/26/2022] [Indexed: 12/31/2022] Open
Abstract
Minimally invasive approaches for aortic valve replacement are now at the forefront of pathological aortic valve treatment. New trials show comparability of these devices to existing therapies, not only in high-risk surgical cohorts but also in low-risk and intermediate-risk cohorts. This review provides vital clinical and anatomical background to aortic valvular disease treatment guidelines, while also providing an update on transcatheter aortic valve implantation (TAVI) devices in Europe, their interventional trials and associated complications.
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Affiliation(s)
- Ishan Antony
- School of MedicineRCSI University of Medicine and Health SciencesDublinIreland,Department of Anatomy and Regenerative Medicine, Tissue Engineering Research Group (TERG)RCSI University of Medicine and Health SciencesDublinIreland
| | - Hyab Mehari Abraha
- Department of Anatomy and Regenerative Medicine, Tissue Engineering Research Group (TERG)RCSI University of Medicine and Health SciencesDublinIreland,Trinity Centre for Biomedical Engineering (TCBE)Trinity College DublinDublinIreland
| | - Aamir Hameed
- Department of Anatomy and Regenerative Medicine, Tissue Engineering Research Group (TERG)RCSI University of Medicine and Health SciencesDublinIreland,Trinity Centre for Biomedical Engineering (TCBE)Trinity College DublinDublinIreland
| | - Claire Conway
- Department of Anatomy and Regenerative Medicine, Tissue Engineering Research Group (TERG)RCSI University of Medicine and Health SciencesDublinIreland,Trinity Centre for Biomedical Engineering (TCBE)Trinity College DublinDublinIreland
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Mehari Abraha H, Iriarte‐Diaz J, Reid RR, Ross CF, Panagiotopoulou O. Fracture Fixation Technique and Chewing Side Impact Jaw Mechanics in Mandible Fracture Repair. JBMR Plus 2021; 6:e10559. [PMID: 35079674 PMCID: PMC8770999 DOI: 10.1002/jbm4.10559] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/03/2021] [Revised: 08/17/2021] [Accepted: 09/07/2021] [Indexed: 12/04/2022] Open
Abstract
Lower jaw (mandible) fractures significantly impact patient health and well‐being due to pain and difficulty eating, but the best technique for repairing the most common subtype—angle fractures—and rehabilitating mastication is unknown. Our study is the first to use realistic in silico simulation of chewing to quantify the effects of Champy and biplanar techniques of angle fracture fixation. We show that more rigid, biplanar fixation results in lower strain magnitudes in the miniplates, the bone around the screws, and in the fracture zone, and that the mandibular strain regime approximates the unfractured condition. Importantly, the strain regime in the fracture zone is affected by chewing laterality, suggesting that both fixation type and the patient's post‐fixation masticatory pattern—ipsi‐ or contralateral to the fracture— impact the bone healing environment. Our study calls for further investigation of the impact of fixation technique on chewing behavior. Research that combines in vivo and in silico approaches can link jaw mechanics to bone healing and yield more definitive recommendations for fixation, hardware, and postoperative rehabilitation to improve outcomes. © 2021 The Authors. JBMR Plus published by Wiley Periodicals LLC on behalf of American Society for Bone and Mineral Research.
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Affiliation(s)
- Hyab Mehari Abraha
- Monash Biomedicine Discovery Institute, Department of Anatomy and Developmental Biology Monash University Melbourne Australia
| | | | - Russell R Reid
- Department of Surgery, Section of Plastic Surgery The University of Chicago Medical Centre Chicago IL USA
| | - Callum F Ross
- Department of Organismal Biology and Anatomy University of Chicago Chicago IL USA
| | - Olga Panagiotopoulou
- Monash Biomedicine Discovery Institute, Department of Anatomy and Developmental Biology Monash University Melbourne Australia
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Palci A, LeBlanc ARH, Panagiotopoulou O, Cleuren SGC, Mehari Abraha H, Hutchinson MN, Evans AR, Caldwell MW, Lee MSY. Plicidentine and the repeated origins of snake venom fangs. Proc Biol Sci 2021; 288:20211391. [PMID: 34375553 PMCID: PMC8354744 DOI: 10.1098/rspb.2021.1391] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/21/2021] [Accepted: 07/19/2021] [Indexed: 12/26/2022] Open
Abstract
Snake fangs are an iconic exemplar of a complex adaptation, but despite striking developmental and morphological similarities, they probably evolved independently in several lineages of venomous snakes. How snakes could, uniquely among vertebrates, repeatedly evolve their complex venom delivery apparatus is an intriguing question. Here we shed light on the repeated evolution of snake venom fangs using histology, high-resolution computed tomography (microCT) and biomechanical modelling. Our examination of venomous and non-venomous species reveals that most snakes have dentine infoldings at the bases of their teeth, known as plicidentine, and that in venomous species, one of these infoldings was repurposed to form a longitudinal groove for venom delivery. Like plicidentine, venom grooves originate from infoldings of the developing dental epithelium prior to the formation of the tooth hard tissues. Derivation of the venom groove from a large plicidentine fold that develops early in tooth ontogeny reveals how snake venom fangs could originate repeatedly through the co-option of a pre-existing dental feature even without close association to a venom duct. We also show that, contrary to previous assumptions, dentine infoldings do not improve compression or bending resistance of snake teeth during biting; plicidentine may instead have a role in tooth attachment.
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Affiliation(s)
- Alessandro Palci
- College of Science and Engineering, Flinders University, Adelaide, SA 5042, Australia
- South Australian Museum, North Terrace, Adelaide, SA 5000, Australia
| | - Aaron R. H. LeBlanc
- Department of Biological Sciences, University of Alberta, Edmonton, AB Canada, T6G 2E9
- Faculty of Dentistry, Oral and Craniofacial Sciences, Guy's Campus, King's College London, London WC2R 2LS, UK
| | - Olga Panagiotopoulou
- Department of Anatomy and Developmental Biology, Monash Biomedicine Discovery Institute, Faculty of Medicine Nursing and Health Sciences, Monash University, Melbourne, VIC 3800, Australia
| | | | - Hyab Mehari Abraha
- Department of Anatomy and Developmental Biology, Monash Biomedicine Discovery Institute, Faculty of Medicine Nursing and Health Sciences, Monash University, Melbourne, VIC 3800, Australia
| | - Mark N. Hutchinson
- College of Science and Engineering, Flinders University, Adelaide, SA 5042, Australia
- South Australian Museum, North Terrace, Adelaide, SA 5000, Australia
| | - Alistair R. Evans
- School of Biological Sciences, Monash University, VIC 3800, Australia
- Geosciences, Museums Victoria, Melbourne, VIC 3001, Australia
| | - Michael W. Caldwell
- Department of Biological Sciences, University of Alberta, Edmonton, AB Canada, T6G 2E9
- Department of Earth and Atmospheric Sciences, University of Alberta, Edmonton, AB Canada, T6G 2E9
| | - Michael S. Y. Lee
- College of Science and Engineering, Flinders University, Adelaide, SA 5042, Australia
- South Australian Museum, North Terrace, Adelaide, SA 5000, Australia
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Panagiotopoulou O, Iriarte-Diaz J, Mehari Abraha H, Taylor AB, Wilshin S, Dechow PC, Ross CF. Biomechanics of the mandible of Macaca mulatta during the power stroke of mastication: Loading, deformation, and strain regimes and the impact of food type. J Hum Evol 2020; 147:102865. [PMID: 32905895 PMCID: PMC7541691 DOI: 10.1016/j.jhevol.2020.102865] [Citation(s) in RCA: 13] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/28/2020] [Revised: 07/21/2020] [Accepted: 07/21/2020] [Indexed: 12/26/2022]
Abstract
Mandible morphology has yet to yield definitive information on primate diet, probably because of poor understanding of mandibular loading and strain regimes, and overreliance on simple beam models of mandibular mechanics. We used a finite element model of a macaque mandible to test hypotheses about mandibular loading and strain regimes and relate variation in muscle activity during chewing on different foods to variation in strain regimes. The balancing-side corpus is loaded primarily by sagittal shear forces and sagittal bending moments. On the working side, sagittal bending moments, anteroposterior twisting moments, and lateral transverse bending moments all reach similar maxima below the bite point; sagittal shear is the dominant loading regime behind the bite point; and the corpus is twisted such that the mandibular base is inverted. In the symphyseal region, the predominant loading regimes are lateral transverse bending and negative twisting about a mediolateral axis. Compared with grape and dried fruit chewing, nut chewing is associated with larger sagittal and transverse bending moments acting on balancing- and working-side mandibles, larger sagittal shear on the working side, and larger twisting moments about vertical and transverse axes in the symphyseal region. Nut chewing is also associated with higher minimum principal strain magnitudes in the balancing-side posterior ramus; higher sagittal shear strain magnitudes in the working-side buccal alveolar process and the balancing-side oblique line, recessus mandibulae, and endocondylar ridge; and higher transverse shear strains in the symphyseal region, the balancing-side medial prominence, and the balancing-side endocondylar ridge. The largest food-related differences in maximum principal and transverse shear strain magnitudes are in the transverse tori and in the balancing-side medial prominence, extramolar sulcus, oblique line, and endocondylar ridge. Food effects on the strain regime are most salient in areas not traditionally investigated, suggesting that studies seeking dietary effects on mandible morphology might be looking in the wrong places.
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Affiliation(s)
- Olga Panagiotopoulou
- Department of Anatomy & Developmental Biology, Monash Biomedicine Discovery Institute, Faculty of Medicine Nursing and Health Sciences, Monash University, Clayton, Melbourne, Victoria, 3800, Australia.
| | - Jose Iriarte-Diaz
- Department of Biology, University of the South, Sewanee, TN, 37383, USA
| | - Hyab Mehari Abraha
- Department of Anatomy & Developmental Biology, Monash Biomedicine Discovery Institute, Faculty of Medicine Nursing and Health Sciences, Monash University, Clayton, Melbourne, Victoria, 3800, Australia
| | | | - Simon Wilshin
- Comparative Biomedical Sciences, The Royal Veterinary College, Hawkshead Lane, Herts, AL97TA, UK
| | - Paul C Dechow
- Department of Biomedical Sciences, Texas A&M University College of Dentistry, Dallas, TX, USA
| | - Callum F Ross
- Department of Organismal Biology and Anatomy, University of Chicago, Chicago, IL, 60637, USA.
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To XV, Benetatos J, Soni N, Liu D, Mehari Abraha H, Yan W, Panagiotopoulou O, Nasrallah FA. Ultra-High-Field Diffusion Tensor Imaging Identifies Discrete Patterns of Concussive Injury in the Rodent Brain. J Neurotrauma 2020; 38:967-982. [PMID: 32394788 DOI: 10.1089/neu.2019.6944] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022] Open
Abstract
Although concussions can result in persistent neurological post-concussion symptoms, they are typically invisible on routine magnetic resonance imaging (MRI) scans. Our study aimed to investigate the use of ultra-high-field diffusion tensor imaging (UHF-DTI) in discerning severity-dependent microstructural changes in the mouse brain following a concussion. Twenty-three C57BL/6 mice were randomly allocated into three groups: the low concussive (LC, n = 9) injury group, the high concussive (HC, n = 6) injury group, and the sham control (SC, n = 7) group. Mice were perfused on day 2 post-injury, and the brains were scanned on a 16.4T MRI scanner with UHF-DTI and neurite orientation dispersion imaging (NODDI). Finite element analysis (FEA) was performed to determine the pattern and extent of the physical impact on the brain tissue. MRI findings were correlated with histopathological analysis in a subset of mice. In the LC group, increased fractional anisotropy (FA) and decreased orientation dispersion index (ODI) but limited neurite density index (NDI) changes were found in the gray matter, and minimal changes to white matter (WM) were observed. The HC group presented increased mean diffusivity (MD), decreased NDI, and decreased ODI in the WM and gray matter (GM); decreased FA was also found in a small area of the WM. WM changes were associated with WM degeneration and neuroinflammation. FEA showed varying region-dependent degrees of stress, in line with the different imaging findings. This study provides evidence that UHF-DTI combined with NODDI can detect concussions of variable intensities. This has significant implications for the diagnosis of concussion in humans.
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Affiliation(s)
- Xuan Vinh To
- The Queensland Brain Institute, The University of Queensland, Brisbane, Queensland, Australia
| | - Joseph Benetatos
- The Queensland Brain Institute, The University of Queensland, Brisbane, Queensland, Australia
| | - Neha Soni
- The Queensland Brain Institute, The University of Queensland, Brisbane, Queensland, Australia
| | - Dedao Liu
- Department of Mechanical and Aerospace Engineering, Faculty of Engineering, Department of Anatomy and Developmental Biology, Faculty of Medicine, Nursing and Health Sciences, Monash University, Melbourne, Victoria, Australia
| | - Hyab Mehari Abraha
- Monash Biomedicine Discovery Institute, Department of Anatomy and Developmental Biology, Faculty of Medicine, Nursing and Health Sciences, Monash University, Melbourne, Victoria, Australia
| | - Wenyi Yan
- Department of Mechanical and Aerospace Engineering, Faculty of Engineering, Department of Anatomy and Developmental Biology, Faculty of Medicine, Nursing and Health Sciences, Monash University, Melbourne, Victoria, Australia
| | - Olga Panagiotopoulou
- Monash Biomedicine Discovery Institute, Department of Anatomy and Developmental Biology, Faculty of Medicine, Nursing and Health Sciences, Monash University, Melbourne, Victoria, Australia
| | - Fatima A Nasrallah
- The Queensland Brain Institute, The University of Queensland, Brisbane, Queensland, Australia.,The Center for Advanced Imaging, The University of Queensland, Brisbane, Queensland, Australia
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Weisbecker V, Guillerme T, Speck C, Sherratt E, Abraha HM, Sharp AC, Terhune CE, Collins S, Johnston S, Panagiotopoulou O. Individual variation of the masticatory system dominates 3D skull shape in the herbivory-adapted marsupial wombats. Front Zool 2019; 16:41. [PMID: 31695725 PMCID: PMC6824091 DOI: 10.1186/s12983-019-0338-5] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/27/2019] [Accepted: 10/04/2019] [Indexed: 12/19/2022] Open
Abstract
Background Within-species skull shape variation of marsupial mammals is widely considered low and strongly size-dependent (allometric), possibly due to developmental constraints arising from the altricial birth of marsupials. However, species whose skulls are impacted by strong muscular stresses – particularly those produced through mastication of tough food items – may not display such intrinsic patterns very clearly because of the known plastic response of bone to muscle activity of the individual. In such cases, allometry may not dominate within-species shape variation, even if it is a driver of evolutionary shape divergence; ordination of shape in a geometric morphometric context through principal component analysis (PCA) should reveal main variation in areas under masticatory stress (incisor region/zygomatic arches/mandibular ramus); but this main variation should emerge from high individual variability and thus have low eigenvalues. Results We assessed the evidence for high individual variation through 3D geometric morphometric shape analysis of crania and mandibles of three species of grazing-specialized wombats, whose diet of tough grasses puts considerable strain on their masticatory system. As expected, we found little allometry and low Principal Component 1 (PC1) eigenvalues within crania and mandibles of all three species. Also as expected, the main variation was in the muzzle, zygomatic arches, and masticatory muscle attachments of the mandibular ramus. We then implemented a new test to ask if the landmark variation reflected on PC1 was reflected in individuals with opposite PC1 scores and with opposite shapes in Procrustes space. This showed that correspondence between individual and ordinated shape variation was limited, indicating high levels of individual variability in the masticatory apparatus. Discussion Our results are inconsistent with hypotheses that skull shape variation within marsupial species reflects a constraint pattern. Rather, they support suggestions that individual plasticity can be an important determinant of within-species shape variation in marsupials (and possibly other mammals) with high masticatory stresses, making it difficult to understand the degree to which intrinsic constraints act on shape variation at the within-species level. We conclude that studies that link micro- and macroevolutionary patterns of shape variation might benefit from a focus on species with low-impact mastication, such as carnivorous or frugivorous species.
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Affiliation(s)
- Vera Weisbecker
- 1School of Biological Sciences, The University of Queensland, Brisbane, Australia
| | - Thomas Guillerme
- 1School of Biological Sciences, The University of Queensland, Brisbane, Australia
| | - Cruise Speck
- 1School of Biological Sciences, The University of Queensland, Brisbane, Australia
| | - Emma Sherratt
- 2School of Biological Sciences, The University of Adelaide, Adelaide, Australia
| | - Hyab Mehari Abraha
- 3Monash Biomedicine Discovery Institute, Department of Anatomy & Developmental Biology, Monash University, Melbourne, Australia
| | - Alana C Sharp
- 4Department of Cell & Developmental Biology, University College London, London, UK.,5Institute of Ageing and Chronic Disease, University of Liverpool, Liverpool, UK
| | - Claire E Terhune
- 6Department of Anthropology, University of Arkansas, Fayetteville, USA
| | - Simon Collins
- 7School of Agricultural and Food Sciences, The University of Queensland, Brisbane, Australia
| | - Stephen Johnston
- 7School of Agricultural and Food Sciences, The University of Queensland, Brisbane, Australia
| | - Olga Panagiotopoulou
- 3Monash Biomedicine Discovery Institute, Department of Anatomy & Developmental Biology, Monash University, Melbourne, Australia
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Mehari Abraha H, Iriarte-Diaz J, Ross CF, Taylor AB, Panagiotopoulou O. The Mechanical Effect of the Periodontal Ligament on Bone Strain Regimes in a Validated Finite Element Model of a Macaque Mandible. Front Bioeng Biotechnol 2019; 7:269. [PMID: 31737614 PMCID: PMC6831558 DOI: 10.3389/fbioe.2019.00269] [Citation(s) in RCA: 16] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/15/2019] [Accepted: 09/27/2019] [Indexed: 11/13/2022] Open
Abstract
The primary anatomical function of the periodontal ligament (PDL) is to attach teeth to their sockets. However, theoretical and constitutive mechanical models have proposed that during mastication the PDL redistributes local occlusal loads and reduces the jaw's resistance to torsional deformations. These hypotheses imply that accurately modeling the PDL's material properties and geometry in finite element analysis (FEA) is a prerequisite to obtaining precise strain and deformation data. Yet, many finite element studies of the human and non-human primate masticatory apparatus exclude the PDL or model it with simplicity, in part due to limitations in μCT/CT scan resolution and material property assignment. Previous studies testing the sensitivity of finite element models (FEMs) to the PDL have yielded contradictory results, however a major limitation of these studies is that FEMs were not validated against in vivo bone strain data. Hence, this study uses a validated and subject specific FEM to assess the effect of the PDL on strain and deformation regimes in the lower jaw of a rhesus macaque (Macaca mulatta) during simulated unilateral post-canine chewing. Our findings demonstrate that the presence of the PDL does influence local and global surface strain magnitudes (principal and shear) in the jaw. However, the PDL's effect is limited (diff. ~200-300 με) in areas away from the alveoli. Our results also show that varying the PDL's Young's Modulus within the range of published values (0.07-1750 MPa) has very little effect on global surface strains. These findings suggest that the mechanical importance of the PDL in FEMs of the mandible during chewing is dependent on the scope of the hypotheses being tested. If researchers are comparing strain gradients across species/taxa, the PDL may be excluded with minimal effect on results, but, if researchers are concerned with absolute strain values, sensitivity analysis is required.
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Affiliation(s)
- Hyab Mehari Abraha
- Moving Morphology and Functional Mechanics Laboratory, Department of Anatomy and Developmental Biology, Monash Biomedicine Discovery Institute, Monash University, Clayton, VIC, Australia
| | - Jose Iriarte-Diaz
- Department of Biology, The University of the South, Sewanee, TN, United States
| | - Callum F. Ross
- Department of Organismal Biology and Anatomy, University of Chicago, Chicago, IL, United States
| | - Andrea B. Taylor
- Department of Basic Science, Touro University, Vallejo, CA, United States
| | - Olga Panagiotopoulou
- Moving Morphology and Functional Mechanics Laboratory, Department of Anatomy and Developmental Biology, Monash Biomedicine Discovery Institute, Monash University, Clayton, VIC, Australia
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Panagiotopoulou O, Iriarte-Diaz J, Wilshin S, Dechow PC, Taylor AB, Mehari Abraha H, Aljunid SF, Ross CF. In vivo bone strain and finite element modeling of a rhesus macaque mandible during mastication. ZOOLOGY 2017; 124:13-29. [PMID: 29037463 DOI: 10.1016/j.zool.2017.08.010] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/28/2016] [Revised: 08/25/2017] [Accepted: 08/25/2017] [Indexed: 12/29/2022]
Abstract
Finite element analysis (FEA) is a commonly used tool in musculoskeletal biomechanics and vertebrate paleontology. The accuracy and precision of finite element models (FEMs) are reliant on accurate data on bone geometry, muscle forces, boundary conditions and tissue material properties. Simplified modeling assumptions, due to lack of in vivo experimental data on material properties and muscle activation patterns, may introduce analytical errors in analyses where quantitative accuracy is critical for obtaining rigorous results. A subject-specific FEM of a rhesus macaque mandible was constructed, loaded and validated using in vivo data from the same animal. In developing the model, we assessed the impact on model behavior of variation in (i) material properties of the mandibular trabecular bone tissue and teeth; (ii) constraints at the temporomandibular joint and bite point; and (iii) the timing of the muscle activity used to estimate the external forces acting on the model. The best match between the FEA simulation and the in vivo experimental data resulted from modeling the trabecular tissue with an isotropic and homogeneous Young's modulus and Poisson's value of 10GPa and 0.3, respectively; constraining translations along X,Y, Z axes in the chewing (left) side temporomandibular joint, the premolars and the m1; constraining the balancing (right) side temporomandibular joint in the anterior-posterior and superior-inferior axes, and using the muscle force estimated at time of maximum strain magnitude in the lower lateral gauge. The relative strain magnitudes in this model were similar to those recorded in vivo for all strain locations. More detailed analyses of mandibular strain patterns during the power stroke at different times in the chewing cycle are needed.
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Affiliation(s)
- Olga Panagiotopoulou
- Moving Morphology & Functional Mechanics Laboratory, School of Biomedical Sciences, The University of Queensland, St Lucia, Brisbane, QLD 4072, Australia; Department of Anatomy and Developmental Biology, School of Biomedical Sciences, Faculty of Medicine, Nursing and Health Sciences, Monash University, Clayton, Melbourne, Victoria 3800, Australia
| | - José Iriarte-Diaz
- Department of Oral Biology, University of Illinois, 801 S. Paulina St., Chicago, IL 60612, USA
| | - Simon Wilshin
- Department of Biomedical Sciences, The Royal Veterinary College, Hawkshead Lane, North Mymms, Hatfield, Hertfordshire AL9 7TA, United Kingdom
| | - Paul C Dechow
- Department of Biomedical Sciences, College of Dentistry, Texas A&M University, 3302 Gaston Ave., Dallas, TX 75246, USA
| | - Andrea B Taylor
- Department of Basic Science, Touro University, 1310 Club Drive, Mare Island, Vellejo, CA 94592, USA
| | - Hyab Mehari Abraha
- Moving Morphology & Functional Mechanics Laboratory, School of Biomedical Sciences, The University of Queensland, St Lucia, Brisbane, QLD 4072, Australia
| | - Sharifah F Aljunid
- Materialise Unit 5-01, Menara OBYU, No. 4, Jalan PJU 8/8A, Damansara Perdana, 47820 Petaling Jaya, Selangor, Malaysia
| | - Callum F Ross
- Department of Organismal Biology and Anatomy, University of Chicago, 1027 E. 57th St., Chicago, IL 60637, USA.
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Colthorpe K, Mehari Abraha H, Zimbardi K, Ainscough L, Spiers JG, Chen HJC, Lavidis NA. Assessing students' ability to critically evaluate evidence in an inquiry-based undergraduate laboratory course. Adv Physiol Educ 2017; 41:154-162. [PMID: 28235754 DOI: 10.1152/advan.00118.2016] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/22/2016] [Revised: 10/28/2016] [Accepted: 12/14/2016] [Indexed: 06/06/2023]
Abstract
The ability to critically evaluate and use evidence from one's own work or from primary literature is invaluable to any researcher. These skills include the ability to identify strengths and weakness of primary literature, to gauge the impact of research findings on a field, to identify gaps in a field that require more research, and to contextualize findings within a field. This study developed a model to examine undergraduate science students' abilities to critically evaluate and use evidence through an analysis of laboratory reports from control and experimental groups in nonresearch-aligned and research-aligned inquiry-based laboratory classes, respectively, and contrasted these with published scientific research articles. The reports analyzed (n = 42) showed that students used evidence in a variety of ways, most often referring to literature indirectly, and least commonly highlighting limitations of literature. There were significant positive correlations between grade awarded and the use of references, evidence, and length, but there were no significant differences between control and experimental groups, so data were pooled. The use of evidence in scientific research articles (n = 7) was similar to student reports except that expert authors were more likely to refer to their own results and cite more references. Analysis showed that students, by the completion of the second year of their undergraduate degree, had expertise approaching that of published authors. These findings demonstrate that it is possible to provide valuable broad-scale undergraduate research experiences to all students in a cohort, giving them exposure to the methods and communication processes of research as well as an opportunity to hone their critical evaluation skills.
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Affiliation(s)
- Kay Colthorpe
- School of Biomedical Science, The University of Queensland, Brisbane, Queensland, Australia
| | - Hyab Mehari Abraha
- School of Biomedical Science, The University of Queensland, Brisbane, Queensland, Australia
| | - Kirsten Zimbardi
- School of Biomedical Science, The University of Queensland, Brisbane, Queensland, Australia
| | - Louise Ainscough
- School of Biomedical Science, The University of Queensland, Brisbane, Queensland, Australia
| | - Jereme G Spiers
- School of Biomedical Science, The University of Queensland, Brisbane, Queensland, Australia
| | - Hsiao-Jou Cortina Chen
- School of Biomedical Science, The University of Queensland, Brisbane, Queensland, Australia
| | - Nickolas A Lavidis
- School of Biomedical Science, The University of Queensland, Brisbane, Queensland, Australia
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Panagiotopoulou O, Spyridis P, Mehari Abraha H, Carrier DR, Pataky TC. Architecture of the sperm whale forehead facilitates ramming combat. PeerJ 2016; 4:e1895. [PMID: 27069822 PMCID: PMC4824896 DOI: 10.7717/peerj.1895] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/16/2015] [Accepted: 03/14/2016] [Indexed: 11/20/2022] Open
Abstract
Herman Melville’s novel Moby Dick was inspired by historical instances in which large sperm whales (Physeter macrocephalus L.) sank 19th century whaling ships by ramming them with their foreheads. The immense forehead of sperm whales is possibly the largest, and one of the strangest, anatomical structures in the animal kingdom. It contains two large oil-filled compartments, known as the “spermaceti organ” and “junk,” that constitute up to one-quarter of body mass and extend one-third of the total length of the whale. Recognized as playing an important role in echolocation, previous studies have also attributed the complex structural configuration of the spermaceti organ and junk to acoustic sexual selection, acoustic prey debilitation, buoyancy control, and aggressive ramming. Of these additional suggested functions, ramming remains the most controversial, and the potential mechanical roles of the structural components of the spermaceti organ and junk in ramming remain untested. Here we explore the aggressive ramming hypothesis using a novel combination of structural engineering principles and probabilistic simulation to determine if the unique structure of the junk significantly reduces stress in the skull during quasi-static impact. Our analyses indicate that the connective tissue partitions in the junk reduce von Mises stresses across the skull and that the load-redistribution functionality of the former is insensitive to moderate variation in tissue material parameters, the thickness of the partitions, and variations in the location and angle of the applied load. Absence of the connective tissue partitions increases skull stresses, particularly in the rostral aspect of the upper jaw, further hinting of the important role the architecture of the junk may play in ramming events. Our study also found that impact loads on the spermaceti organ generate lower skull stresses than an impact on the junk. Nevertheless, whilst an impact on the spermaceti organ would reduce skull stresses, it would also cause high compressive stresses on the anterior aspect of the organ and the connective tissue case, possibly making these structures more prone to failure. This outcome, coupled with the facts that the spermaceti organ houses sensitive and essential sonar producing structures and the rostral portion of junk, rather than the spermaceti organ, is frequently a site of significant scarring in mature males suggest that whales avoid impact with the spermaceti organ. Although the unique structure of the junk certainly serves multiple functions, our results are consistent with the hypothesis that the structure also evolved to function as a massive battering ram during male-male competition.
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Affiliation(s)
- Olga Panagiotopoulou
- Faculty of Medicine and Biomedical Sciences, Moving Morphology & Functional Mechanics Laboratory, School of Biomedical Sciences, The University of Queensland , Brisbane , Australia
| | - Panagiotis Spyridis
- Polytropos Ltd, London, United Kingdom; Department of Civil Engineering and Natural Hazards, University of Natural Resources and Life Sciences, Vienna, Austria
| | - Hyab Mehari Abraha
- Faculty of Medicine and Biomedical Sciences, Moving Morphology & Functional Mechanics Laboratory, School of Biomedical Sciences, The University of Queensland , Brisbane , Australia
| | - David R Carrier
- Department of Biology, University of Utah , Salt Lake City , Utah, United States of America
| | - Todd C Pataky
- Institute for Fiber Engineering, Department of Bioengineering, Shinshu University , Ueda, Nagano , Japan
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