scholarly journals MODELING THE EFFECT OF VARIATION IN SAGITTAL CURVATURE ON THE FORCE REQUIRED TO PRODUCE A FOLLOWER LOAD IN THE LUMBAR SPINE

2012 ◽  
Vol 12 (01) ◽  
pp. 1250013 ◽  
Author(s):  
JUDITH R. MEAKIN ◽  
RICHARD M. ASPDEN
Keyword(s):  
Lumbar Spine ◽  
Sagittal Plane ◽  
Spinal Curvature ◽  
Spinal Stability ◽  
Follower Load ◽  
Dimensional Model ◽  
Standing Posture ◽  
Extensor Muscles

The aim of this study was to investigate how the forces required to stabilize the lumbar spine in the standing posture may be affected by variation in its shape. A two-dimensional model of the lumbar spine in the sagittal plane was developed that included a simplified representation of the lumbar extensor muscles. The shape of the model was varied by changing both the magnitude and distribution of the lumbar curvature. The forces required to produce a resultant load traveling along a path as close to the vertebral body centroids as possible (a follower load) were determined. In general,the forces required to produce a follower load increased as the curvature became larger and more evenly distributed. The results suggest that the requirements of the lumbar muscles to maintain spinal stability in vivo will vary between individuals. This has implications for understanding the role of spinal curvature and muscle atrophy in back pain.

The Path to Deliver the Most Realistic Follower Load for a Lumbar Spine in Standing Posture: A Finite Element Study

2019 ◽  
Vol 141 (3) ◽  
Author(s):  
Han Zhang ◽  
Weiping Zhu
Keyword(s):  
Finite Element ◽  
Lumbar Spine ◽  
Three Dimensional ◽  
Compressive Load ◽  
Element Model ◽  
Lumbosacral Spine ◽  
Follower Load ◽  
Load Path ◽  
Standing Posture

A spine is proven to be subjected to a follower load which is a compressive load of physiologic magnitude acting on the whole spine. The path of the follower load approximates the tangent to the curve of the spine in in vivo neutral standing posture. However, the specific path location of the follower load is still unclear. The aim of this study is to find out the most realistic location of the follower load path (FLP) for a lumbar spine in standing. A three-dimensional (3D) nonlinear finite element model (FEM) of lumbosacral vertebrae (L1-S1) with consideration of the calibrated material properties was established and validated by comparing with the experimental data. We show that the shape of the lumbosacral spine is strongly affected by the location of FLP. An evident nonlinear relationship between the FLP location and the kinematic response of the L1-S1 lumbosacral spine exists. The FLP at about 4 and 3 mm posterior to the curve connecting the center of the vertebral bodies delivers the most realistic location in standing for healthy people and patients having low back pains (LPBs), respectively. Moreover, the “sweeping” method introduced in this study can be applicable to all individualized FEM to determine the location of FLP.

Investigation of Lumbosacral Spine Anatomical Variation Effect on Load-Partitioning Under Follower Load Using Geometrically Personalized Finite Element Model

2014 ◽  
Author(s):  
Sadegh Naserkhaki ◽  
Jacob L. Jaremko ◽  
Greg Kawchuk ◽  
Samer Adeeb ◽  
Marwan El-Rich
Keyword(s):  
Finite Element ◽  
Lumbar Spine ◽  
Anatomical Variation ◽  
Load Sharing ◽  
Element Model ◽  
Collagen Fibers ◽  
Spinal Curvature ◽  
Lumbosacral Spine ◽  
Follower Load ◽  
Spinal Load

The spinal load sharing and mechanical stresses developed in the spine segments due to mechanical loads are dependent on the unique spinal anatomy (geometry and posture). Variation in spinal curvature alters the load sharing of the lumbar spine as well as the stiffness and stability of the passive tissues. In this paper, effects of lumbar spine curvature variation on spinal load sharing under compressive Follower Load (FL) are investigated numerically. 3D nonlinear Finite Element (FE) models of three ligamentous lumbosacral spines are developed based on personalized geometries; hypo-lordotic (Hypo-L), normal (Normal-L) and hyper-lordotic (Hyper-L) cases. Analysis of each model is performed under Follower Load and developed stress in the discs and forces in the collagen fibers are investigated. Stresses on the discs vary in magnitude and distribution depending on the degree of lordosis. A straight hypo-lordotic spine shows stresses more equally distributed among discs while a highly curved hyper-lordotic spine has stresses concentrated at lower discs. Stresses are uniformly distributed in each disc for Hypo-L case while they are concentrated posteriorly for Hyper-L case. Also, the maximum force in collagen fibers is developed in the Hyper-L case. These differences might be clinically significant related to back pain.

Intertester Reliability and Validity of Motion Assessments During Lumbar Spine Accessory Motion Testing

2008 ◽  
Vol 88 (1) ◽  
pp. 43-49 ◽  
Author(s):  
Rob Landel ◽  
Kornelia Kulig ◽  
Michael Fredericson ◽  
Bernard Li ◽  
Christopher M Powers
Keyword(s):  
Lumbar Spine ◽  
Magnetic Resonance ◽  
Sagittal Plane ◽  
Magnetic Resonance Images ◽  
Segmental Motion ◽  
Segmental Mobility ◽  
Spine Motion ◽  
Mobile Segment ◽  
Good Agreement

Background and PurposePosterior-anterior (PA) assessment of the lumbar spine correlates with radiographic signs of instability and can guide treatment choices, yet studies of the validity of lumbar PA assessments have not been conducted in vivo. The purposes of this study were to determine the intertester reliability of the PA examination in assessing intersegmental lumbar spine motion and to evaluate the validity of this procedure in vivo with dynamic magnetic resonance imaging (MRI).SubjectsTwenty-nine subjects with central lumbar pain participated in this study.MethodsTwo physical therapists independently identified each subject's most and least mobile lumbar segments using the PA procedure. Midsagittal lumbar images were obtained simultaneously during one examiner's assessment. Lumbar segmental mobility was quantified from magnetic resonance images as the change in the intervertebral angle between the resting position and the end range of the PA force application. For each vertebral level tested, maximal sagittal-plane segmental motion was determined.ResultsThe intertester reliability for identifying the least mobile segment was good (agreement=82.8%, kappa=.71, 95% confidence interval [CI]=.48 to .94), but it was poor for identifying the most mobile segment (kappa=.29, 95% CI=−.13 to .71), despite good agreement (79.3%). The level of agreement between the PA assessments and intervertebral motion measured by MRI was poor (kappa=.04, 95% CI=−.16 to .24, and kappa=.00, 95% CI=−.09 to .08, for the least and most mobile segments, respectively).Discussion and ConclusionDespite good intertester reliability for identifying the least mobile segment, PA assessments of lumbar segmental mobility did not agree with sagittal-plane motion measured by dynamic MRI. This finding calls into question the validity of the PA procedure for assessing intervertebral lumbar spine motion.

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

Role of Trunk Muscles in Generating Follower Load in the Lumbar Spine of Neutral Standing Posture

2008 ◽  
Vol 130 (4) ◽  
Author(s):  
Kyungsoo Kim ◽  
Yoon Hyuk Kim
Keyword(s):  
Lumbar Spine ◽  
Shear Force ◽  
Muscle Activation ◽  
Optimization Problem ◽  
Load Condition ◽  
Joint Moment ◽  
Trunk Muscles ◽  
Follower Load ◽  
Muscle Forces

Recently, experimental results have demonstrated that the load carrying capacity of the human spine substantially increases under the follower load condition. Thus, it is essential to prove that a follower load can be generated in vivo by activating the appropriate muscles in order to demonstrate the possibility that the stability of the spinal column could be maintained through a follower load mechanism. The aim of this study was to analyze the coordination of the trunk muscles in order to understand the role of the muscles in generating the follower load. A three-dimensional finite element model of the lumbar spine was developed from T12 to S1 and 117 pairs of trunk muscles (58 pairs of superficial muscles and 59 pairs of deep muscles) were considered. The follower load concept was mathematically represented as an optimization problem. The muscle forces required to generate the follower load were predicted by solving the optimization problem. The corresponding displacements and rotations at all nodes were estimated along with the follower forces, shear forces, and joint moments acting on those nodes. In addition, the muscle forces and the corresponding responses were investigated when the activations of the deep muscles or the superficial muscles were restricted to 75% of the maximum activation, respectively. Significantly larger numbers of deep muscles were involved in the generation of the follower load than the number of superficial muscles, regardless of the restriction on muscle activation. The shear force and the resultant joint moment are more influenced by the change in muscle activation in the superficial muscles. A larger number of deep trunk muscles were activated in order to maintain the spinal posture in the lumbar spine. In addition, the deep muscles have a larger capability to reduce the shear force and the resultant joint moment with respect to the perturbation of the external load or muscle fatigue compared to the superficial muscles.

Mitochondrial matrix calcium ions regulate energy production in myocardium: A cytochemical study

1990 ◽  
Vol 48 (2) ◽  
pp. 166-167
Author(s):  
W.A. Jacob ◽  
R. Hertsens ◽  
A. Van Bogaert ◽  
M. De Smet
Keyword(s):  
Energy Metabolism ◽  
Calcium Ions ◽  
Energy Production ◽  
Regulation Of Respiration ◽  
Free Calcium ◽  
Mitochondrial Matrix ◽  
Cytochemical Study ◽  
Nmr Techniques

In the past most studies of the control of energy metabolism focus on the role of the phosphorylation potential ATP/ADP.Pi on the regulation of respiration. Studies using NMR techniques have demonstrated that the concentrations of these compounds for oxidation phosphorylation do not change appreciably throughout the cardiac cycle and during increases in cardiac work. Hence regulation of energy production by calcium ions, present in the mitochondrial matrix, has been the object of a number of recent studies.Three exclusively intramitochondnal dehydrogenases are key enzymes for the regulation of oxidative metabolism. They are activated by calcium ions in the low micromolar range. Since, however, earlier estimates of the intramitochondnal calcium, based on equilibrium thermodynamic considerations, were in the millimolar range, a physiological correlation was not evident. The introduction of calcium-sensitive probes fura-2 and indo-1 made monitoring of free calcium during changing energy metabolism possible. These studies were performed on isolated mitochondria and extrapolation to the in vivo situation is more or less speculative.

Meiotic CENP-C is a shepherd: bridging the space between the centromere and the kinetochore in time and space

2020 ◽  
Vol 64 (2) ◽  
pp. 251-261
Author(s):  
Jessica E. Fellmeth ◽  
Kim S. McKim
Keyword(s):  
Chromosome Segregation ◽  
New Technologies ◽  
Early Prophase ◽  
Unique Role ◽  
Kinetochore Assembly ◽  
M Phase ◽  
In Vivo Analysis ◽  
Meiosis I

Abstract While many of the proteins involved in the mitotic centromere and kinetochore are conserved in meiosis, they often gain a novel function due to the unique needs of homolog segregation during meiosis I (MI). CENP-C is a critical component of the centromere for kinetochore assembly in mitosis. Recent work, however, has highlighted the unique features of meiotic CENP-C. Centromere establishment and stability require CENP-C loading at the centromere for CENP-A function. Pre-meiotic loading of proteins necessary for homolog recombination as well as cohesion also rely on CENP-C, as do the main scaffolding components of the kinetochore. Much of this work relies on new technologies that enable in vivo analysis of meiosis like never before. Here, we strive to highlight the unique role of this highly conserved centromere protein that loads on to centromeres prior to M-phase onset, but continues to perform critical functions through chromosome segregation. CENP-C is not merely a structural link between the centromere and the kinetochore, but also a functional one joining the processes of early prophase homolog synapsis to late metaphase kinetochore assembly and signaling.

The Role of Polyphenols in the Modulation of Plasma Non-Enzymatic Antioxidant Capacity (NEAC)

2012 ◽  
Vol 82 (3) ◽  
pp. 228-232 ◽  
Author(s):  
Mauro Serafini ◽  
Giuseppa Morabito
Keyword(s):  
Antioxidant Capacity ◽  
Dietary Intervention ◽  
Ex Vivo ◽  
The Body ◽  
Dietary Polyphenols ◽  
Enzymatic Antioxidant ◽  
Endogenous Antioxidant

Dietary polyphenols have been shown to scavenge free radicals, modulating cellular redox transcription factors in different in vitro and ex vivo models. Dietary intervention studies have shown that consumption of plant foods modulates plasma Non-Enzymatic Antioxidant Capacity (NEAC), a biomarker of the endogenous antioxidant network, in human subjects. However, the identification of the molecules responsible for this effect are yet to be obtained and evidences of an antioxidant in vivo action of polyphenols are conflicting. There is a clear discrepancy between polyphenols (PP) concentration in body fluids and the extent of increase of plasma NEAC. The low degree of absorption and the extensive metabolism of PP within the body have raised questions about their contribution to the endogenous antioxidant network. This work will discuss the role of polyphenols from galenic preparation, food extracts, and selected dietary sources as modulators of plasma NEAC in humans.

Potential Uses of Vinegar as a Medicine and Related in vivo Mechanisms

2016 ◽  
Vol 86 (3-4) ◽  
pp. 127-151 ◽  
Author(s):  
Zeshan Ali ◽  
Zhenbin Wang ◽  
Rai Muhammad Amir ◽  
Shoaib Younas ◽  
Asif Wali ◽  
...  
Keyword(s):  
Chemical Structure ◽  
Review Paper ◽  
Heart Diseases ◽  
Folk Medicine ◽  
Active Role ◽  
Current Review ◽  
Different Types ◽  
Positive Effect

While the use of vinegar to fi ght against infections and other crucial conditions dates back to Hippocrates, recent research has found that vinegar consumption has a positive effect on biomarkers for diabetes, cancer, and heart diseases. Different types of vinegar have been used in the world during different time periods. Vinegar is produced by a fermentation process. Foods with a high content of carbohydrates are a good source of vinegar. Review of the results of different studies performed on vinegar components reveals that the daily use of these components has a healthy impact on the physiological and chemical structure of the human body. During the era of Hippocrates, people used vinegar as a medicine to treat wounds, which means that vinegar is one of the ancient foods used as folk medicine. The purpose of the current review paper is to provide a detailed summary of the outcome of previous studies emphasizing the role of vinegar in treatment of different diseases both in acute and chronic conditions, its in vivo mechanism and the active role of different bacteria.

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