scholarly journals Prenatal muscle forces are necessary for vertebral segmentation and disc structure, but not for notochord involution in mice

2021 ◽  
Vol 41 ◽  
pp. 558-575
Author(s):  
A Levillain ◽  
S Ahmed ◽  
D-M Kaimaki ◽  
S Schuler ◽  
S Barros ◽  
...  
Keyword(s):  
Annulus Fibrosus ◽  
Critical Role ◽  
Collagen Fibre ◽  
Dorsal Side ◽  
Muscle Contractions ◽  
Spinal Curvature ◽  
Cervical Region ◽  
Muscle Forces ◽  
Muscle Loading

Embryonic muscle forces are necessary for normal vertebral development and spinal curvature, but their involvement in intervertebral disc (IVD) development remains unclear. The aim of the current study was to determine how muscle contractions affect (1) notochord involution and vertebral segmentation, and (2) IVD development including the mechanical properties and morphology, as well as collagen fibre alignment in the annulus fibrosus. Muscular dysgenesis (mdg) mice were harvested at three prenatal stages: at Theiler Stage (TS)22 when notochord involution starts, at TS24 when involution is complete, and at TS27 when the IVD is formed. Vertebral and IVD development were characterised using histology, immunofluorescence, and indentation testing. The results revealed that notochord involution and vertebral segmentation occurred independently of muscle contractions between TS22 and TS24. However, in the absence of muscle contractions, we found vertebral fusion in the cervical region at TS27, along with (i) a displacement of the nucleus pulposus towards the dorsal side, (ii) a disruption of the structural arrangement of collagen in the annulus fibrosus, and (iii) an increase in viscous behaviour of the annulus fibrosus. These findings emphasise the important role of mechanical forces during IVD development, and demonstrate a critical role of muscle loading during development to enable proper annulus fibrosus formation. They further suggest a need for mechanical loading in the creation of fibre-reinforced tissue engineering replacement IVDs as a therapy for IVD degeneration.

The Effect of Muscle Loading on Internal Mechanical Parameters of the Lumbar Spine: A Finite Element Study

2011 ◽  
Author(s):  
Benjamin C. Gadomski ◽  
John Rasmussen ◽  
Christian M. Puttlitz
Keyword(s):  
Annulus Fibrosus ◽  
Critical Role ◽  
Complex Loading ◽  
Tissue Level ◽  
Mechanical Parameters ◽  
Loading Conditions ◽  
Additional Stability ◽  
Muscle Loading ◽  
Pure Moment

The human spine experiences complex loading in vivo; however, simplifications to these loading conditions are commonly made in computational and experimental protocols. Pure moments are often used in cadaveric preparations to replicate in vivo loading conditions, and previous studies have shown this method adequately predicts range of motion behavior (1, 2). It is unclear what effect pure moment loading has on the tissue-level internal mechanical parameters such as stresses in the annulus fibrosus and facet contact parameters. Recent advances in musculoskeletal modeling have elucidated previously unknown quantities of the musculature recruitment patterns such as times, forces, and directions. The advancements are especially relevant in cases of surgical intervention because the spinal musculature has been reported to play a critical role in providing additional stability to the spine when defects such as discectomy and nucleotomy are involved (2). Thus, the aim of the study was to determine the importance of computational loading conditions on the resultant global ranges of motion, as well as the tissue-level predictions of annulus fibrosus stresses, and facet contact pressures, forces, and areas.

scholarly journals Sensory neurons contacting the cerebrospinal fluid require the Reissner fiber to detect spinal curvature in vivo

2019 ◽  
Author(s):  
Adeline Orts-Del’Immagine ◽  
Yasmine Cantaut-Belarif ◽  
Olivier Thouvenin ◽  
Julian Roussel ◽  
Asha Baskaran ◽  
...  
Keyword(s):  
Spinal Cord ◽  
Cerebrospinal Fluid ◽  
Sensory Neurons ◽  
Critical Role ◽  
Central Canal ◽  
Spinal Curvature ◽  
List Type ◽  
Close Vicinity

SummaryRecent evidence indicate active roles for the cerebrospinal fluid (CSF) on body axis development and morphogenesis of the spine implying CSF-contacting neurons (CSF-cNs) in the spinal cord. CSF-cNs project a ciliated apical extension into the central canal that is enriched in the channel PKD2L1 and enables the detection of spinal curvature in a directional manner. Dorsolateral CSF-cNs ipsilaterally respond to lateral bending while ventral CSF-cNs respond to longitudinal bending. Historically, the implication of the Reissner fiber (RF), a long extracellular thread in the CSF, to CSF-cN sensory functions has remained a subject of debate. Here, we reveal using electron microscopy in zebrafish larvae that the RF is in close vicinity with cilia and microvilli of ventral and dorsolateral CSF-cNs. We investigate in vivo the role of cilia and the Reissner fiber in the mechanosensory functions of CSF-cNs by combining calcium imaging with patch-clamp recordings. We show that disruption of cilia motility affects CSF-cN sensory responses to passive and active curvature of the spinal cord without affecting the Pkd2l1 channel activity. Since ciliary defects alter the formation of the Reissner fiber, we investigated whether the Reissner fiber contributes to CSF-cN mechanosensitivity in vivo. Using a hypomorphic mutation in the scospondin gene that forbids the aggregation of SCO-spondin into a fiber, we demonstrate in vivo that the Reissner fiber per se is critical for CSF-cN mechanosensory function. Our study uncovers that neurons contacting the cerebrospinal fluid functionally interact with the Reissner fiber to detect spinal curvature in the vertebrate spinal cord.Abstract FigureeToCThe role of the Reissner fiber, a long extracellular thread running in the cerebrospinal fluid (CSF), has been since its discovery in 1860 a subject of debate. Orts-Del’Immagine et al. report that the Reissner fiber plays a critical role in the detection of spinal curvature by sensory neurons contacting the CSF.HighlightsSince its discovery, the role of the Reissner fiber has long been a subject of debateMechanoreception in CSF-contacting neurons (CSF-cNs) in vivo requires the Reissner fiberCSF-cN apical extension is in close vicinity of the Reissner fiberCSF-cNs and the Reissner fiber form in vivo a sensory organ detecting spinal curvature

The Role of the SLP in Autism Spectrum Disorder Screening and Assessment

2008 ◽  
Vol 15 (2) ◽  
pp. 50-59 ◽  
Author(s):  
Amy Philofsky
Keyword(s):  
Language Development ◽  
Critical Role ◽  
Children With Autism ◽  
Autism Spectrum ◽  
Children With Asd ◽  
Prevalence Estimates ◽  
Notable Increase ◽  
Screening Assessment ◽  
Critical Components

AbstractRecent prevalence estimates for autism have been alarming as a function of the notable increase. Speech-language pathologists play a critical role in screening, assessment and intervention for children with autism. This article reviews signs that may be indicative of autism at different stages of language development, and discusses the importance of several psychometric properties—sensitivity and specificity—in utilizing screening measures for children with autism. Critical components of assessment for children with autism are reviewed. This article concludes with examples of intervention targets for children with ASD at various levels of language development.

A critical role of iNOS-derived Nitric Oxide (NO) and progesterone in implantation

1998 ◽  
Vol 5 (1) ◽  
pp. 115A-115A
Author(s):  
K CHWALISZ ◽  
E WINTERHAGER ◽  
T THIENEL ◽  
R GARFIELD
Keyword(s):  
Nitric Oxide ◽  
Critical Role

Bridging the Gap between Ethical Climate and Nurses’ Service Behaviors: the Critical Role of Professional Well-Being

2018 ◽  
Vol 20 (3) ◽  
pp. 99-110
Author(s):  
Na Zhang ◽  
Jingjing Li ◽  
Xing Bu ◽  
Zhenxing Gong ◽  
Gilal Faheem Gul
Keyword(s):  
Ethical Climate ◽  
Critical Role ◽  
Well Being

Bridging the Knowledge Gaps in Arrhythmogenic Cardiovascular Conditions: The Critical Role of Registries

2016 ◽  
Vol 10 (2) ◽  
pp. 1 ◽  
Author(s):  
Melody Hermel ◽  
Rebecca Duffy ◽  
Alexander Orfanos ◽  
Isabelle Hack ◽  
Shayna McEnteggart ◽  
...  
Keyword(s):  
Clinical Trials ◽  
Natural History ◽  
Risk Stratification ◽  
Critical Role ◽  
Knowledge Gaps ◽  
Level Of Evidence ◽  
The Future

Cardiac registries have filled many gaps in knowledge related to arrhythmogenic cardiovascular conditions. Despite the less robust level of evidence available in registries when compared with clinical trials, registries have contributed a range of clinically useful information. In this review, the authors discuss the role that registries have played – related to diagnosis, natural history, risk stratification, treatment, and genetics of arrhythmogenic cardiovascular conditions – in closing knowledge gaps, and their role in the future.

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