Determination of Real Time In-Vivo Cartilage Contact Deformation in the Ankle Joint

2007 ◽  
Author(s):  
Guoan Li ◽  
Lu Wan ◽  
Michal Kozanek
Keyword(s):  
Computational Models ◽  
Ex Vivo ◽  
Loading Conditions ◽  
Contact Deformation ◽  
Normal Cartilage ◽  
Physiological Loading ◽  
Contact Data ◽  
Biomechanical Responses

Knowledge of in-vivo articular cartilage contact deformation is critical for understanding normal cartilage function and the etiology of osteoarthritis (2,8). This knowledge is also instrumental for design of ex-vivo experiment to investigate the chondrocyte mechanotransductions under physiological loading conditions (7). Further, in-vivo cartilage contact data is necessary for validation of 3D computational models used to predict biomechanical responses of the articular joints (1,5). However, due to the complexity of in-vivo joint loading conditions as well as the complicated joint geometry, little information is available on in-vivo cartilage deformation in literature (9). In-vivo cartilage deformation as a function of loading history has not been delineated.

scholarly journals Insight into Glutamatergic Involvement in Rewarding Effects of Mephedrone in Rats: In Vivo and Ex Vivo Study

2021 ◽  
Author(s):  
Olga Wronikowska ◽  
Maria Zykubek ◽  
Agnieszka Michalak ◽  
Anna Pankowska ◽  
Paulina Kozioł ◽  
...  
Keyword(s):  
Ex Vivo ◽  
Interdisciplinary Approach ◽  
Nmda Antagonist ◽  
Exchange Chromatography ◽  
Resonance Spectroscopy ◽  
Monoamine Transporters ◽  
Ex Vivo Study ◽  
Insight Into

AbstractMephedrone is a widely used drug of abuse, exerting its effects by interacting with monoamine transporters. Although this mechanism has been widely studied heretofore, little is known about the involvement of glutamatergic transmission in mephedrone effects. In this study, we comprehensively evaluated glutamatergic involvement in rewarding effects of mephedrone using an interdisciplinary approach including (1) behavioural study on effects of memantine (non-selective NMDA antagonist) on expression of mephedrone-induced conditioned place preference (CPP) in rats; (2) evaluation of glutamate concentrations in the hippocampus of rats following 6 days of mephedrone administration, using in vivo magnetic resonance spectroscopy (MRS); and (3) determination of glutamate levels in the hippocampus of rats treated with mephedrone and subjected to MRS, using ion-exchange chromatography. In the presented research, we confirmed priorly reported mephedrone-induced rewarding effects in the CPP paradigm and showed that memantine (5 mg/kg) was able to reverse the expression of this effect. MRS study showed that subchronic mephedrone administration increased glutamate level in the hippocampus when measured in vivo 24 h (5 mg/kg, 10 mg/kg and 20 mg/kg) and 2 weeks (5 mg/kg and 20 mg/kg) after last injection. Ex vivo chromatographic analysis did not show significant changes in hippocampal glutamate concentrations; however, it showed similar results as obtained in the MRS study proving its validity. Taken together, the presented study provides new insight into glutamatergic involvement in rewarding properties of mephedrone.

scholarly journals Comparison of the Resistance to Bending Forces of the 4.5 LCP Plate-rod Construct and of 4.5 LCP Alone Applied to Segmental Femoral Defects in Miniature Pigs

2010 ◽  
Vol 79 (4) ◽  
pp. 613-620 ◽  
Author(s):  
Lucie Urbanová ◽  
Robert Srnec ◽  
Pavel Proks ◽  
Ladislav Stehlík ◽  
Zdeněk Florian ◽  
...  
Keyword(s):  
Ex Vivo ◽  
Femoral Diaphysis ◽  
Miniature Pig ◽  
Femoral Bone ◽  
Bone Implant ◽  
Miniature Pigs ◽  
Bone Defect Healing ◽  
Considerable Strain

The study deals with the determination of mechanical properties, namely resistance to bending forces, of flexible buttress osteosynthesis using two different bone-implant constructs stabilizing experimental segmental femoral bone defects (segmental ostectomy) in a miniature pig ex vivo model using 4.5 mm titanium LCP and a 3 mm intramedullary pin (“plate and rod” construct) (PR-LCP), versus the 4.5 mm titanium LCP alone (A-LCP). The “plate and rod” fixation (PR-LCP) of the segmental femoral defect is significantly more resistant (p < 0.05) to bending forces (200 N, 300 N, and 500 N) than LCP alone (A-LCP). Stabilisation of experimental segmental lesions of the femoral diaphysis in miniature pigs by flexible bridging osteosynthesis 4.5 mm LCP in combination with the “plate and rod” construct appears to be a suitable fixation of non-reducible fractures where considerable strain of the implants by bending forces can be assumed. These findings will be used in upcoming in vivo experiments in the miniature pig to investigate bone defect healing after transplantation of mesenchymal stem cells in combination with biocompatible scaffolds.

Electronic determination of root canal working length in primary molar teeth: an in vivo and ex vivo study

2011 ◽  
Vol 44 (5) ◽  
pp. 402-406 ◽  
Author(s):  
A. P. C. A. Beltrame ◽  
T. C. Triches ◽  
N. Sartori ◽  
M. Bolan
Keyword(s):  
Root Canal ◽  
Ex Vivo ◽  
Primary Molar ◽  
Working Length ◽  
Molar Teeth ◽  
Ex Vivo Study

A New Hypothesis for Human Atherosclerotic Plaque Progression Based on Serial In Vivo MRI and Computational Modeling Method

2007 ◽  
Author(s):  
Sayan Mondal ◽  
Chun Yang ◽  
Joseph D. Petruccelli ◽  
Chun Yuan ◽  
Fei Liu ◽  
...  
Keyword(s):  
Shear Stress ◽  
Wall Thickness ◽  
Computational Models ◽  
Ex Vivo ◽  
Maximum Principal Stress ◽  
Magnetic Resonance Images ◽  
Shear Stresses ◽  
Flow Shear ◽  
Flow Shear Stress

It has been well-accepted that atherosclerosis initiation and progression correlate positively with low and oscillating flow wall shear stresses. However, this shear stress mechanism cannot fully explain why advanced plaques continue to grow under elevated flow shear stress conditions. Our previous investigations using 3D computational models with fluid-structure interactions (FSI) based on in vivo/ex vivo magnetic resonance images (MRI) of human carotid atherosclerotic plaques indicated that there is a negative correlation between advanced plaque wall thickness and structural maximum principal stress (Stress-P1) in the plaque and a positive correlation between plaque wall thickness and flow shear stress [3].

scholarly journals Models of tendon development and injury

2019 ◽  
Vol 1 (1) ◽  
Author(s):  
Sophia K. Theodossiou ◽  
Nathan R. Schiele
Keyword(s):  
Computational Models ◽  
Ex Vivo ◽  
Current Model ◽  
Stem Cell Differentiation ◽  
Tendon Injury ◽  
Model Systems ◽  
Tendon Development ◽  
Key Aspects

AbstractTendons link muscle to bone and transfer forces necessary for normal movement. Tendon injuries can be debilitating and their intrinsic healing potential is limited. These challenges have motivated the development of model systems to study the factors that regulate tendon formation and tendon injury. Recent advances in understanding of embryonic and postnatal tendon formation have inspired approaches that aimed to mimic key aspects of tendon development. Model systems have also been developed to explore factors that regulate tendon injury and healing. We highlight current model systems that explore developmentally inspired cellular, mechanical, and biochemical factors in tendon formation and tenogenic stem cell differentiation. Next, we discuss in vivo, in vitro, ex vivo, and computational models of tendon injury that examine how mechanical loading and biochemical factors contribute to tendon pathologies and healing. These tendon development and injury models show promise for identifying the factors guiding tendon formation and tendon pathologies, and will ultimately improve regenerative tissue engineering strategies and clinical outcomes.

DETERMINATION OF PHYSIOLOGICAL LOADING CONDITIONS AT THE HUMAN DISTAL RADIUS

2012 ◽  
Vol 45 ◽  
pp. S100
Author(s):  
Patrik Christen ◽  
Bert van Rietbergen ◽  
Ingrid Knippels ◽  
Ralph Müller ◽  
G. Harry van Lenthe ◽  
...  
Keyword(s):  
Distal Radius ◽  
Loading Conditions ◽  
Physiological Loading

scholarly journals Determination of Elastic Modulus in Mouse Bones Using a Nondestructive Micro-Indentation Technique Using Reference Point Indentation

2018 ◽  
Vol 140 (7) ◽  
Author(s):  
Ganesh Thiagarajan ◽  
Mark T. Begonia ◽  
Mark Dallas ◽  
Nuria Lara-Castillo ◽  
JoAnna M. Scott ◽  
...  
Keyword(s):  
Elastic Modulus ◽  
Reference Point ◽  
Ex Vivo ◽  
Numerical Procedure ◽  
Indentation Modulus ◽  
Three Point Bending ◽  
Bending Modulus ◽  
Reference Point Indentation

The determination of the elastic modulus of bone is important in studying the response of bone to loading and is determined using a destructive three-point bending method. Reference point indentation (RPI), with one cycle of indentation, offers a nondestructive alternative to determine the elastic modulus. While the elastic modulus could be determined using a nondestructive procedure for ex vivo experiments, for in vivo testing, the three-point bending technique may not be practical and hence RPI is viewed as a potential alternative and explored in this study. Using the RPI measurements, total indentation distance (TID), creep indentation distance, indentation force, and the unloading slope, we have developed a numerical analysis procedure using the Oliver–Pharr (O/P) method to estimate the indentation elastic modulus. Two methods were used to determine the area function: (1) Oliver–Pharr (O/P—based on a numerical procedure) and (2) geometric (based on the calculation of the projected area of indentation). The indentation moduli of polymethyl methacrylate (PMMA) calculated by the O/P (3.49–3.68 GPa) and geometric (3.33–3.49 GPa) methods were similar to values in literature (3.5–4 GPa). In a study using femurs from C57Bl/6 mice of different ages and genders, the three-point bending modulus was lower than the indentation modulus. In femurs from 4 to 5 months old TOPGAL mice, we found that the indentation modulus from the geometric (5.61 ± 1.25 GPa) and O/P (5.53 ± 1.27 GPa) methods was higher than the three-point bending modulus (5.28 ± 0.34 GPa). In females, the indentation modulus from the geometric (7.45 ± 0.86 GPa) and O/P (7.46 ± 0.92 GPa) methods was also higher than the three-point bending modulus (7.33 ± 1.13 GPa). We can conclude from this study that the RPI determined values are relatively close to three-point bending values.

scholarly journals Simulated-Physiological Loading Conditions Preserve Biological and Mechanical Properties of Caprine Lumbar Intervertebral Discs in Ex Vivo Culture

PLoS ONE ◽  
2012 ◽  
Vol 7 (3) ◽  
pp. e33147 ◽  
Author(s):  
Cornelis P. L. Paul ◽  
Hendrik A. Zuiderbaan ◽  
Behrouz Zandieh Doulabi ◽  
Albert J. van der Veen ◽  
Peter M. van de Ven ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Ex Vivo ◽  
Intervertebral Discs ◽  
Loading Conditions ◽  
Physiological Loading ◽  
Ex Vivo Culture

Detection of allergen-induced airway hyperresponsiveness in isolated mouse lungs

2006 ◽  
Vol 291 (3) ◽  
pp. L466-L472 ◽  
Author(s):  
Martin Witzenrath ◽  
Birgit Ahrens ◽  
Stefanie M. Kube ◽  
Armin Braun ◽  
Heinz G. Hoymann ◽  
...  
Keyword(s):  
Airway Hyperresponsiveness ◽  
Ex Vivo ◽  
Whole Body ◽  
Strongly Correlated ◽  
Ex Vivo Model ◽  
Isolated Lungs ◽  
Spontaneously Breathing

Airway hyperresponsiveness (AHR) is a hallmark of bronchial asthma. Important features of this exaggerated response to bronchoconstrictive stimuli have mostly been investigated in vivo in intact animals or in vitro in isolated tracheal or bronchial tissues. Both approaches have important advantages but also certain limitations. Therefore, the aim of our study was to develop an ex vivo model of isolated lungs from sensitized mice for the investigation of airway responsiveness (AR). BALB/c mice were sensitized by intraperitoneal ovalbumin (Ova) and subsequently challenged by Ova inhalation. In vivo AR was measured in unrestrained animals by whole body plethysmography after stimulation with aerosolized methacholine (MCh) with determination of enhanced pause ( Penh). Twenty-four hours after each Penh measurement, airway resistance was continuously registered in isolated, perfused, and ventilated lungs on stimulation with inhaled or intravascular MCh or nebulized Ova. In a subset of experiments, in vivo AR was additionally measured in orotracheally intubated, spontaneously breathing mice 24 h after Penh measurement, and lungs were isolated further 24 h later. Isolated lungs of allergen-sensitized and -challenged mice showed increased AR after MCh inhalation or infusion as well as after specific provocation with aerosolized allergen. AR was increased on days 2 and 5 after Ova challenge and had returned to baseline on day 9. AHR in isolated lungs after aerosolized or intravascular MCh strongly correlated with in vivo AR. Pretreatment of isolated lungs with the β2-agonist fenoterol diminished AR. In conclusion, this model provides new opportunities to investigate mechanisms of AHR as well as pharmacological interventions on an intact organ level.

scholarly journals Fluid Structural Analysis of Urine Flow in a Stented Ureter

2016 ◽  
Vol 2016 ◽  
pp. 1-7 ◽  
Author(s):  
J. Carlos Gómez-Blanco ◽  
F. Javier Martínez-Reina ◽  
Domingo Cruz ◽  
J. Blas Pagador ◽  
Francisco M. Sánchez-Margallo ◽  
...  
Keyword(s):  
Computational Models ◽  
Mechanical Characterization ◽  
Ex Vivo ◽  
Biological Tissues ◽  
Urine Flow ◽  
Computational Environment ◽  
Computational Fluid Dynamics Cfd

Many urologists are currently studying new designs of ureteral stents to improve the quality of their operations and the subsequent recovery of the patient. In order to help during this design process, many computational models have been developed to simulate the behaviour of different biological tissues and provide a realistic computational environment to evaluate the stents. However, due to the high complexity of the involved tissues, they usually introduce simplifications to make these models less computationally demanding. In this study, the interaction between urine flow and a double-J stented ureter with a simplified geometry has been analysed. The Fluid-Structure Interaction (FSI) of urine and the ureteral wall was studied using three models for the solid domain: Mooney-Rivlin, Yeoh, and Ogden. The ureter was assumed to be quasi-incompressible and isotropic. Data obtained in previous studies from ex vivo and in vivo mechanical characterization of different ureters were used to fit the mentioned models. The results show that the interaction between the stented ureter and urine is negligible. Therefore, we can conclude that this type of models does not need to include the FSI and could be solved quite accurately assuming that the ureter is a rigid body and, thus, using the more simple Computational Fluid Dynamics (CFD) approach.

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