scholarly journals Numerical Modelling of the Behaviour of the Cervical Spine under the Effect of a Flexion / Extension

2019 ◽  
Vol 01 (02) ◽  
pp. 144-153 ◽  
Author(s):  
Nadir Damba ◽  
Abdellatif OUDRANE ◽  
Benaoumeur AOUR ◽  
Mohammed Salah BENNOUNA ◽  
Nabil BELKAHELLA ◽  
...  
Keyword(s):  
Cervical Spine ◽  
Classical Mechanics ◽  
Three Dimensional ◽  
Individual Variability ◽  
In Vitro Tests ◽  
Three Dimensional Model ◽  
Major Interest ◽  
Flexion Extension

Numerical simulation is today widely used in several fields of engineering, and research undertaken for more than 20 years concerning the geometric and mechanical modeling of the spine gradually leads to clinical applications of major interest. Indeed, the in vivo and in vitro evaluation tools pose a certain number of limitations: non-standardized procedures and inter-specimen variability for in vitro tests, medical, ethical constraints, and inter-individual variability for in vivo. These limitations are actually obstacles to comparison. It is notably within the framework of implant comparisons that the methods of structural calculation, and more particularly finite element modeling, widely used in classical mechanics, find their usefulness. in this context, this present work consists in developing a three-dimensional model of the cervical spine, in order to subsequently optimize the fitting of disc prostheses

scholarly journals Identification of Novel Recognition Motifs and Regulatory Targets for the Yeast Actin-regulating Kinase Prk1p

2003 ◽  
Vol 14 (12) ◽  
pp. 4871-4884 ◽  
Author(s):  
Bo Huang ◽  
Guisheng Zeng ◽  
Alvin Y.J. Ng ◽  
Mingjie Cai
Keyword(s):  
Actin Cytoskeleton ◽  
Phosphorylation Site ◽  
Three Dimensional ◽  
Kinase Domain ◽  
Yeast Genome ◽  
Three Dimensional Model ◽  
Recognition Sequence ◽  
Yeast Saccharomyces Cerevisiae

Prk1p is a serine/threonine kinase involved in the regulation of the actin cytoskeleton organization in the yeast Saccharomyces cerevisiae. Previously, we have identified LxxQxTG as the phosphorylation site of Prk1p. In this report, the recognition sequence for Prk1p is investigated more thoroughly. It is found that the presence of a hydrophobic residue at the position of P-5 is necessary for Prk1p phosphorylation and L, I, V, and M are all able to confer the phosphorylation at various efficiencies. The residue flexibility at P-2 has also been identified to include Q, N, T, and S. A homology-based three-dimensional model of the kinase domain of Prk1p provided some structural interpretations for these substrate specificities. The characterization of the [L/I/V/M]xx[Q/N/T/S]xTG motif led to the identification of a spectrum of potential targets for Prk1p from yeast genome. One of them, Scd5p, which contains three LxxTxTG motifs and is previously known to be important for endocytosis and actin organization, has been chosen to demonstrate its relationship with Prk1p. Phosphorylation of Scd5p by Prk1p at the three LxxTxTG motifs could be detected in vitro and in vivo, and deletion of PRK1 suppressed the defects in actin cytoskeleton and endocytosis in one of the scd5 mutants. These results allowed us to conclude that Scd5p is likely another regulatory target of Prk1p.

scholarly journals Mutagenesis and Molecular Modeling Reveal Three Key Extracellular Loops of the Membrane Receptor HasR That Are Involved in Hemophore HasA Binding

2007 ◽  
Vol 189 (14) ◽  
pp. 5379-5382 ◽  
Author(s):  
Clément Barjon ◽  
Karine Wecker ◽  
Nadia Izadi-Pruneyre ◽  
Philippe Delepelaire
Keyword(s):  
Molecular Modeling ◽  
Outer Membrane ◽  
Three Dimensional ◽  
Membrane Receptor ◽  
Dimensional Model ◽  
Outer Membrane Receptor ◽  
Three Dimensional Model ◽  
Extracellular Loops

ABSTRACT On the basis of the three-dimensional model of the heme/hemophore TonB-dependent outer membrane receptor HasR, mutants with six-residue deletions in the 11 putative extracellular loops were generated. Although all mutants continued to be active TonB-dependent heme transporters, mutations in three loops abolished hemophore HasA binding both in vivo and in vitro.

scholarly journals Ranges of Cervical Intervertebral Disc Deformation During an In Vivo Dynamic Flexion–Extension of the Neck

2017 ◽  
Vol 139 (6) ◽  
Author(s):  
Yan Yu ◽  
Haiqing Mao ◽  
Jing-Sheng Li ◽  
Tsung-Yuan Tsai ◽  
Liming Cheng ◽  
...  
Keyword(s):  
Cervical Spine ◽  
Imaging System ◽  
Human Subjects ◽  
Three Dimensional ◽  
Cervical Disc ◽  
Significant Difference ◽  
Flexion Extension ◽  
Fluoroscopic Imaging ◽  
Magnetic Resonance Imaging Mri

While abnormal loading is widely believed to cause cervical spine disc diseases, in vivo cervical disc deformation during dynamic neck motion has not been well delineated. This study investigated the range of cervical disc deformation during an in vivo functional flexion–extension of the neck. Ten asymptomatic human subjects were tested using a combined dual fluoroscopic imaging system (DFIS) and magnetic resonance imaging (MRI)-based three-dimensional (3D) modeling technique. Overall disc deformation was determined using the changes of the space geometry between upper and lower endplates of each intervertebral segment (C3/4, C4/5, C5/6, and C6/7). Five points (anterior, center, posterior, left, and right) of each disc were analyzed to examine the disc deformation distributions. The data indicated that between the functional maximum flexion and extension of the neck, the anterior points of the discs experienced large changes of distraction/compression deformation and shear deformation. The higher level discs experienced higher ranges of disc deformation. No significant difference was found in deformation ranges at posterior points of all the discs. The data indicated that the range of disc deformation is disc level dependent and the anterior region experienced larger changes of deformation than the center and posterior regions, except for the C6/7 disc. The data obtained from this study could serve as baseline knowledge for the understanding of the cervical spine disc biomechanics and for investigation of the biomechanical etiology of disc diseases. These data could also provide insights for development of motion preservation surgeries for cervical spine.

Comparison of three-dimensional helical axes of the cervical spine between in vitro and in vivo testing

2018 ◽  
Vol 18 (3) ◽  
pp. 515-524 ◽  
Author(s):  
René Jonas ◽  
Robert Demmelmaier ◽  
Steffen P. Hacker ◽  
Hans-Joachim Wilke
Keyword(s):  
Cervical Spine ◽  
Three Dimensional ◽  
In Vivo Testing

scholarly journals Subject-Specific Inverse Dynamics of the Head and Cervical Spine During in Vivo Dynamic Flexion-Extension

2013 ◽  
Vol 135 (6) ◽  
Author(s):  
William J. Anderst ◽  
William F. Donaldson ◽  
Joon Y. Lee ◽  
James D. Kang
Keyword(s):  
Finite Element ◽  
Cervical Spine ◽  
Inverse Dynamics ◽  
Total Force ◽  
Finite Element Models ◽  
Moment Arms ◽  
Flexion Extension ◽  
Subject Specific

The effects of degeneration and surgery on cervical spine mechanics are commonly evaluated through in vitro testing and finite element models derived from these tests. The objectives of the current study were to estimate the load applied to the C2 vertebra during in vivo functional flexion-extension and to evaluate the effects of anterior cervical arthrodesis on spine kinetics. Spine and head kinematics from 16 subjects (six arthrodesis patients and ten asymptomatic controls) were determined during functional flexion-extension using dynamic stereo X-ray and conventional reflective markers. Subject-specific inverse dynamics models, including three flexor muscles and four extensor muscles attached to the skull, estimated the force applied to C2. Total force applied to C2 was not significantly different between arthrodesis and control groups at any 10 deg increment of head flexion-extension (all p values ≥ 0.937). Forces applied to C2 were smallest in the neutral position, increased slowly with flexion, and increased rapidly with extension. Muscle moment arms changed significantly during flexion-extension, and were dependent upon the direction of head motion. The results suggest that in vitro protocols and finite element models that apply constant loads to C2 do not accurately represent in vivo cervical spine kinetics.

scholarly journals Recent Advances in Three-Dimensional Multicellular Spheroid Culture and Future Development

Micromachines ◽  
2021 ◽  
Vol 12 (1) ◽  
pp. 96
Author(s):  
Honglin Shen ◽  
Shuxiang Cai ◽  
Chuanxiang Wu ◽  
Wenguang Yang ◽  
Haibo Yu ◽  
...  
Keyword(s):  
Three Dimensional ◽  
Multicellular Spheroids ◽  
Three Dimensional Model ◽  
Advantages And Disadvantages ◽  
High Throughput Drug Screening ◽  
Tumor Research ◽  
Basic Biology ◽  
And Function

Three-dimensional multicellular spheroids (MCSs) have received extensive attention in the field of biomedicine due to their ability to simulate the structure and function of tissues in vivo more accurately than traditional in vitro two-dimensional models and to simulate cell–cell and cell extracellular matrix (ECM) interactions. It has become an important in vitro three-dimensional model for tumor research, high-throughput drug screening, tissue engineering, and basic biology research. In the review, we first summarize methods for MCSs generation and their respective advantages and disadvantages and highlight the advances of hydrogel and microfluidic systems in the generation of spheroids. Then, we look at the application of MCSs in cancer research and other aspects. Finally, we discuss the development direction and prospects of MCSs

scholarly journals The interleaved partial active shape model (IPASM) search algorithm – towards 3D ultrasound-based bone surface reconstruction

10.29007/rbgl ◽  
2019 ◽  
Author(s):  
Benjamin Hohlmann ◽  
Klaus Radermacher
Keyword(s):  
Search Algorithm ◽  
Three Dimensional ◽  
3D Ultrasound ◽  
Three Dimensional Model ◽  
In Vivo Experiments ◽  
Distal Surface ◽  
Cheap Alternative ◽  
Orthopedic Applications

Several orthopedic applications require a three-dimensional model of the bone. Ultrasound is a radiation-free and cheap alternative to the state-of-the-art imaging modalities if its limitations in terms of image quality and viewing range can be overcome. This work presents in-vitro as well as in-vivo experiments evaluating the IPASM search, a method for combined segmentation, registration as well as extrapolation. The algorithm is capable to reconstruct the distal surface of a phantom femur with an average surface distance error of roughly 1mm in case of in-vitro as well as below 2mm for in-vivo records, even if the shape varies strongly from the initial model.

Engineering a Three-Dimensional In Vitro Drug Testing Platform for Glioblastoma

2015 ◽  
Vol 6 (4) ◽  
Author(s):  
Metin Akay ◽  
Duong T. Nguyen ◽  
Yantao Fan ◽  
Yasemin M. Akay
Keyword(s):  
Cell Culture ◽  
Drug Testing ◽  
Three Dimensional ◽  
In Vitro Tests ◽  
Valuable Insight ◽  
Poly Ethylene Glycol ◽  
Poly Ethylene ◽  
Cancer Spheroids

Three-dimensional (3D) in vivo cell culture modeling is quickly emerging as a platform to replace two-dimensional (2D) monolayer cell culture in vitro tests. Three-dimensional tumor models mimic physiological conditions and provide valuable insight of the tumor cell response to drug discovery application. In this study, we used poly(ethylene glycol) (PEG) hydrogel microwells to generate 3D brain cancer spheroids and studied their treatment with anticancer drugs in single or combination treatment. Glioblastoma (GBM) spheroids were grown through 14 days before infecting with two drugs: Pitavastatin and Irinotecan at various concentrations. A significant cell lysis was observed and cell viability decreased to lower than 7% when drugs were combined at the concentration Pitavastatin 10 μM and Irinotecan 50 μM to infect after 7 days. These findings demonstrate a promising platform—PEG hydrogel microwells—that should be an efficient way to test the drug sensitivity in vitro as well as application in different studies.

scholarly journals Új, laparoszkópos beültetésre alkalmas sérvháló állatkísérletes vizsgálata

2016 ◽  
Vol 157 (5) ◽  
pp. 180-184 ◽  
Author(s):  
Péter Marcell Guba
Keyword(s):  
Vinyl Alcohol ◽  
Three Dimensional ◽  
Major Complication ◽  
Biological Properties ◽  
Poly Vinyl Alcohol ◽  
In Vitro Tests ◽  
In Vivo Tests ◽  
Male Wistar Rats

Introduction: Reconstruction of the abdominal wall with mesh is a widely used surgical procedure. The non-absorbable meshes tend to cause numerous side-effects. Aim: The aim of the author was to produce an absorbable, polymer-based mesh that possesses appropriate chemical, mechanical and biological properties. Method: A three-dimensional, biocompatible mesh was produced from poly-vinyl-alcohol using reactive electrospinning. Toxicity and cell-mesh interactions were tested using human lung carcinoma epithelial cells (A-549), and in vivo tests were conducted in 42 male Wistar rats at the 1–5, 7 and 14 postoperative days (3 rats/groups). Results: In the in vitro tests poly-vinyl-alcohol was biocompatible. In the in vivo tests no major complication was associated with the mesh made of poly-vinyl-alcohol. Conclusions: The author concludes that this polymer mesh is biocompatible, it does not damage the surrounding tissues and integrates well with them. Orv. Hetil., 2016, 157(5), 180–184.

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