scholarly journals Validated Computational Framework for Evaluation of In Vivo Knee Mechanics

2020 ◽  
Vol 142 (8) ◽  
Author(s):  
Azhar A. Ali ◽  
Erin M. Mannen ◽  
Paul J. Rullkoetter ◽  
Kevin B. Shelburne
Keyword(s):  
Fe Simulation ◽  
Knee Extension ◽  
Musculoskeletal Modeling ◽  
Whole Body ◽  
Knee Ligament ◽  
Knee Mechanics ◽  
Flexion Extension ◽  
Subject Specific ◽  
The Impact

Abstract Dynamic, in vivo evaluations of knee mechanics are important for understanding knee injury and repair, and developing successful treatments. Computational models have been used with in vivo experiments to quantify joint mechanics, but they are typically not predictive. The current study presents a novel integrated approach with high-speed stereo radiography, musculoskeletal modeling, and finite element (FE) modeling for evaluation of subject-specific, in vivo knee mechanics in a healthy subject performing a seated knee extension and weight-bearing lunge. Whole-body motion capture, ground reaction forces, and radiography-based kinematics were used to drive musculoskeletal and predictive FE models for load-controlled simulation of in vivo knee mechanics. A predictive simulation of knee mechanics was developed in four stages: (1) in vivo measurements of one subject performing a lunge and a seated knee extension, (2) rigid-body musculoskeletal modeling to determine muscle forces, (3) FE simulation of knee extension for knee-ligament calibration, and (4) predictive FE simulation of a lunge. FE models predicted knee contact and ligament mechanics and evaluated the impact of cruciate ligament properties on joint kinematics and loading. Calibrated model kinematics demonstrated good agreement to the experimental motion with root-mean-square differences of tibiofemoral flexion–extension <3 deg, internal–external <4 deg, and anterior–posterior <2 mm. Ligament reference strain and attachment locations were the most critical properties in the calibration process. The current work advances previous in vivo knee modeling through simulation of dynamic activities, modeling of subject-specific knee behavior, and development of a load-controlled knee model.

scholarly journals Magnetic Resonance-Compatible Arm-Crank Ergometry: A New Platform Linking Whole-Body Calorimetry to Upper-Extremity Biomechanics and Arm Muscle Metabolism

2020 ◽  
Author(s):  
Riemer JK Vegter ◽  
Sebastiaan van den Brink ◽  
Leonora J Mouton ◽  
Anita Sibeijn-Kuiper ◽  
Lucas H.V. van der Woude ◽  
...  
Keyword(s):  
Magnetic Resonance ◽  
Surface Electromyography ◽  
Motor Units ◽  
Daily Practice ◽  
Muscle Disease ◽  
Upper Body ◽  
Whole Body ◽  
Energetic Efficiency ◽  
The Impact

Abstract Background: Evaluation of the effect of human upper body training regimens may benefit from knowledge of local energy expenditure in arm muscles. To that end, we developed a novel asynchronous arm-crank ergometry platform for use in a clinical magnetic resonance (MR) scanner with 31P spectroscopy capability to study arm muscle energetics. The utility of the platform was tested in an investigation of the impact of daily practice on the energetic efficiency of execution of an arm-cranking task (ACT) in healthy subjects. Results: We recorded the first ever in vivo 31P MR spectra from the human biceps bracii muscle during ACT execution pre- and post-three weeks of daily practice bouts, respectively. Complementary datasets on whole body oxygen consumption, arm muscle electrical activity, arm-force and power output, respectively, were obtained in the mock-up scanner. The mean gross mechanical efficiency of execution of the ACT significantly increased 1.5-fold from 5.7 ± 1.2% to 8.6 ± 1.7% (P<0.05) after training, respectively. However, in only one subject this improvement was associated with recruitment of strictly oxidative motor units in the working biceps muscle. In all other subjects, biceps pH fell below 6.8 during exercise indicating recruitment of anaerobic motor units, the magnitude of which was either unaffected (two subjects) or even increased (two subjects) post-training. Surface electromyography and mechanical force recordings revealed that individuals employed various arm muscle recruitment strategies, using either predominantly elbow flexor muscles (two subjects), elbow extensor muscles (one subject,) or a combination of the two (two subjects), respectively. Three weeks of training improved muscle coordination but did not alter individual strategies. Conclusions: The new platform has produced the first ever in vivo dynamic data on human biceps energy and pH balance during upper body exercise. It allows evaluation of cyclic motor performance and outcomes of upper-body training regimens in healthy novices by integrating these new measurements with whole body calorimetry, surface electromyography and biomechanical measurements. This methodology may be equally valid for lower-limb impaired athletes, wheelchair users and patients with debilitating muscle disease.

Impact of in vivo fatty acid oxidation blockade on glucose turnover and muscle glucose metabolism during low-dose AICAR infusion

2006 ◽  
Vol 291 (5) ◽  
pp. E1131-E1140 ◽  
Author(s):  
Michael Christopher ◽  
Christian Rantzau ◽  
Zhi-Ping Chen ◽  
Rodney Snow ◽  
Bruce Kemp ◽  
...  
Keyword(s):  
Fatty Acid ◽  
Glucose Metabolism ◽  
Fatty Acid Oxidation ◽  
Low Dose ◽  
Whole Body ◽  
Glucose Turnover ◽  
Acid Oxidation ◽  
Metabolic Clearance ◽  
The Impact

AMPK plays a central role in influencing fuel usage and selection. The aim of this study was to analyze the impact of low-dose AMP analog 5-aminoimidazole-4-carboxamide-1-β-d-ribosyl monophosphate (ZMP) on whole body glucose turnover and skeletal muscle (SkM) glucose metabolism. Dogs were restudied after prior 48-h fatty acid oxidation (FAOX) blockade by methylpalmoxirate (MP; 5 × 12 hourly 10 mg/kg doses). During the basal equilibrium period (0–150 min), fasting dogs ( n = 8) were infused with [3-3H]glucose followed by either 2-h saline or AICAR (1.5–2.0 mg·kg−1·min−1) infusions. SkM was biopsied at completion of each study. On a separate day, the same protocol was undertaken after 48-h in vivo FAOX blockade. The AICAR and AICAR + MP studies were repeated in three chronic alloxan-diabetic dogs. AICAR produced a transient fall in plasma glucose and increase in insulin and a small decline in free fatty acid (FFA). Parallel increases in hepatic glucose production (HGP), glucose disappearance (Rd tissue), and glycolytic flux (GF) occurred, whereas metabolic clearance rate of glucose (MCRg) did not change significantly. Intracellular SkM glucose, glucose 6-phosphate, and glycogen were unchanged. Acetyl-CoA carboxylase (ACC∼pSer221) increased by 50%. In the AICAR + MP studies, the metabolic responses were modified: the glucose was lower over 120 min, only minor changes occurred with insulin and FFA, and HGP and Rd tissue responses were markedly attenuated, but MCRg and GF increased significantly. SkM substrates were unchanged, but ACC∼pSer221 rose by 80%. Thus low-dose AICAR leads to increases in HGP and SkM glucose uptake, which are modified by prior FAox blockade.

scholarly journals Selective regulation of cellular and secreted multimeric adiponectin by antidiabetic therapies in humans

2009 ◽  
Vol 297 (3) ◽  
pp. E767-E773 ◽  
Author(s):  
Susan A. Phillips ◽  
Jacqueline Kung ◽  
Theodore P. Ciaraldi ◽  
Charles Choe ◽  
Louis Christiansen ◽  
...  
Keyword(s):  
Insulin Sensitivity ◽  
Low Dose ◽  
Whole Body ◽  
Serum Adiponectin ◽  
High Dose ◽  
Hmw Adiponectin ◽  
Dose Combination ◽  
Cell Expression ◽  
The Impact

Adiponectin, an insulin-sensitizing factor secreted from adipose tissue, is decreased in individuals with type 2 diabetes (T2D) and increased in response to thiazolidinedione (TZD) therapy. Changes in its secretion and assembly into higher-order forms affect insulin sensitivity. To determine the relative potency of TZDs on intra-adipocyte multimerization and secretion of adiponectin, we assessed the impact of in vivo low- or high-dose rosiglitazone treatment alone or combined with metformin in subjects with T2D. T2D subjects received high-dose rosiglitazone (8 mg/day), high-dose metformin (2,000 mg/day), or low-dose combination rosiglitazone-metformin therapy (4 mg + 1,000 mg/day) for 4 mo. All subjects were then switched to high-dose rosiglitazone-metformin combination therapy (8 mg + 2,000 mg/day) for another 4 mo. Low-dose rosiglitazone increased serum adiponectin, whereas the high dose increased both adipocyte content and serum adiponectin levels. TZDs selectively increased the percentage of circulating adiponectin in the potent, high-molecular-weight (HMW) form. No TZD effects were evident on multimer distribution in the cell. Expression of the chaperone protein ERp44, which retains adiponectin within the cell, was decreased by TZD treatment. No changes occurred in Ero1-Lα expression. Metformin had no effect on any of these measures. Increases in adiponectin correlated with improvements in insulin sensitivity. In vivo, TZDs have apparent dose-dependent effects on cellular and secreted adiponectin. TZD-mediated improvements in whole body insulin sensitivity are associated with increases in circulating but not cellular levels of the HMW adiponectin multimer. Finally, TZDs promote the selective secretion of HMW adiponectin, potentially, in part, through decreasing the expression of the adiponectin-retaining protein ERp44.

Development and Evaluation of a Subject-Specific Lower Limb Model With an Eleven-Degrees-of-Freedom Natural Knee Model Using Magnetic Resonance and Biplanar X-Ray Imaging During a Quasi-Static Lunge

2020 ◽  
Vol 142 (6) ◽  
Author(s):  
David Leandro Dejtiar ◽  
Christine Mary Dzialo ◽  
Peter Heide Pedersen ◽  
Kenneth Krogh Jensen ◽  
Martin Kokholm Fleron ◽  
...  
Keyword(s):  
Magnetic Resonance ◽  
Knee Joint ◽  
Joint Model ◽  
Joint Kinematics ◽  
Contact Forces ◽  
Joint Mechanics ◽  
X Ray ◽  
Knee Mechanics ◽  
Subject Specific

Abstract Musculoskeletal (MS) models can be used to study the muscle, ligament, and joint mechanics of natural knees. However, models that both capture subject-specific geometry and contain a detailed joint model do not currently exist. This study aims to first develop magnetic resonance image (MRI)-based subject-specific models with a detailed natural knee joint capable of simultaneously estimating in vivo ligament, muscle, tibiofemoral (TF), and patellofemoral (PF) joint contact forces and secondary joint kinematics. Then, to evaluate the models, the predicted secondary joint kinematics were compared to in vivo joint kinematics extracted from biplanar X-ray images (acquired using slot scanning technology) during a quasi-static lunge. To construct the models, bone, ligament, and cartilage structures were segmented from MRI scans of four subjects. The models were then used to simulate lunges based on motion capture and force place data. Accurate estimates of TF secondary joint kinematics and PF translations were found: translations were predicted with a mean difference (MD) and standard error (SE) of 2.13 ± 0.22 mm between all trials and measures, while rotations had a MD ± SE of 8.57 ± 0.63 deg. Ligament and contact forces were also reported. The presented modeling workflow and the resulting knee joint model have potential to aid in the understanding of subject-specific biomechanics and simulating the effects of surgical treatment and/or external devices on functional knee mechanics on an individual level.

High-impact Routines to Ameliorate Trunk and Lower Limbs Flexibility in Women

2020 ◽  
Vol 41 (14) ◽  
pp. 1039-1046
Author(s):  
Massimo De Nardi ◽  
Carlo Facheris ◽  
Piero Ruggeri ◽  
Antonio La Torre ◽  
Roberto Codella
Keyword(s):  
Young Women ◽  
Knee Extension ◽  
Position Sense ◽  
Lower Limbs ◽  
Whole Body ◽  
Crossover Fashion ◽  
Single Session ◽  
Partial Body ◽  
The Impact ◽  
Trunk Position

AbstractSeveral types of routines and methods have been experimented to gain neuro/muscular advantages, in terms of overall range of motion, in athletes and fitness enthusiasts. The aim of the present study was to evaluate the impact of different routines on trunk- and lower limbs flexibility in a sample of young women. In a randomized-crossover fashion, eleven subjects underwent to: hamstrings stretching [S]; hamstrings stretching plus whole-body vibration [S+WBV]; partial-body cryotherapy [Cryo]; rest [Control]. Standing hamstrings stretch performance and sit-and-reach amplitude resulted to be improved with [S+WBV] compared to all other protocols (p<0.05). [Cryo] ameliorated the active knee extension performance with respect to all other interventions (p<0.05). These flexibility improvements were obtained without a loss in the trunk position sense proprioception. These results represent the first evidence that a single session of either vibration or cryotherapy can ameliorate flexibility without losing the trunk position sense proprioception in young women.

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 On the impact of modelling assumptions in multi-scale, subject-specific models of aortic haemodynamics

2016 ◽  
Vol 13 (119) ◽  
pp. 20160073 ◽  
Author(s):  
Jordi Alastruey ◽  
Nan Xiao ◽  
Henry Fok ◽  
Tobias Schaeffter ◽  
C. Alberto Figueroa
Keyword(s):  
Boundary Conditions ◽  
Three Dimensional ◽  
Small Region ◽  
Model Parameters ◽  
Simulation Framework ◽  
Non Invasive ◽  
Subject Specific ◽  
Modelling Assumptions ◽  
The Impact

Simulation of haemodynamics has become increasingly popular within the research community. Irrespective of the modelling approach (zero-dimensional (0D), one-dimensional (1D) or three-dimensional (3D)), in vivo measurements are required to personalize the arterial geometry, material properties and boundary conditions of the computational model. Limitations in in vivo data acquisition often result in insufficient information to determine all model parameters and, hence, arbitrary modelling assumptions. Our goal was to minimize and understand the impact of modelling assumptions on the simulated blood pressure, flow and luminal area waveforms by studying a small region of the systemic vasculature—the upper aorta—and acquiring a rich array of non-invasive magnetic resonance imaging and tonometry data from a young healthy volunteer. We first investigated the effect of different modelling assumptions for boundary conditions and material parameters in a 1D/0D simulation framework. Strategies were implemented to mitigate the impact of inconsistencies in the in vivo data. Average relative errors smaller than 7% were achieved between simulated and in vivo waveforms. Similar results were obtained in a 3D/0D simulation framework using the same inflow and outflow boundary conditions and consistent geometrical and mechanical properties. We demonstrated that accurate subject-specific 1D/0D and 3D/0D models of aortic haemodynamics can be obtained using non-invasive clinical data while minimizing the number of arbitrary modelling decisions.

Title efficacy of phosphodiesterase 5 inhibitor on distant burn-induced muscle autophagy, microcirculation, and survival rate

2013 ◽  
Vol 304 (9) ◽  
pp. E922-E933 ◽  
Author(s):  
Sachiko Hosokawa ◽  
Hiroaki Koseki ◽  
Michio Nagashima ◽  
Yoshihiro Maeyama ◽  
Kentaro Yomogida ◽  
...  
Keyword(s):  
Skeletal Muscle ◽  
Survival Rate ◽  
Muscle Wasting ◽  
Burn Injury ◽  
Whole Body ◽  
Phosphodiesterase 5 Inhibitor ◽  
Skeletal Muscle Wasting ◽  
The Impact ◽  
Phosphodiesterase 5

Skeletal muscle wasting is an exacerbating factor in the prognosis of critically ill patients. Using a systemic burn injury model in mice, we have established a role of autophagy in the resulting muscle wasting that is distant from the burn trauma. We provide evidence that burn injury increases the autophagy turnover in the distal skeletal muscle by conventional postmortem tissue analyses and by a novel in vivo microscopic method using an autophagy reporter gene (tandem fluorescent LC3). The effect of tadalafil, a phosphodiesterase 5 inhibitor (PDE5I), on burn-induced skeletal muscle autophagy is documented and extends our published results that PDE5Is attenuates muscle degeneration in a muscular dystrophy model. We also designed a translational experiment to examine the impact of PDE5I on whole body and demonstrated that PDE5I administration lessened muscle atrophy, mitigated microcirculatory disturbance, and improved the survival rate after burn injury.

scholarly journals Is HPV the Novel Target in Male Idiopathic Infertility? A Systematic Review of the Literature

2021 ◽  
Vol 12 ◽  
Author(s):  
Francesco Muscianisi ◽  
Luca De Toni ◽  
Gloria Giorato ◽  
Andrea Carosso ◽  
Carlo Foresta ◽  
...  
Keyword(s):  
Systematic Review ◽  
Male Infertility ◽  
Seminal Fluid ◽  
Hpv Infection ◽  
Point Of View ◽  
Whole Body ◽  
Idiopathic Infertility ◽  
The Impact

Infertility is an important health problem that affects up to 16% of couples worldwide. Male infertility is responsible for about 50% of the cases, and the various causes of male infertility may be classified in pre-testicular (for example hypothalamic diseases), testicular, and post-testicular (for example obstructive pathologies of seminal ducts) causes. Sexually transmitted infections (STI) are increasingly widely accepted by researchers and clinicians as etiological factors of male infertility. In particular, several recent reports have documented the presence of HPV in seminal fluid and observed that sperm infection can also be present in sexually active asymptomatic male and infertile patients. In this review, we aimed to perform a systematic review of the whole body of literature exploring the impact of HPV infection in natural and assisted fertility outcomes, from both an experimental and a clinical point of view. Starting from in-vitro studies in animals up to in-vivo studies in humans, we aimed to study and evaluate the weight of this infection as a possible cause of idiopathic infertility in males with any known cause of conception failure.

Impact of variable insulinemia and glycemia on in vivo glycolysis and glucose storage in dogs

1994 ◽  
Vol 266 (1) ◽  
pp. E62-E71 ◽  
Author(s):  
M. J. Christopher ◽  
C. Rantzau ◽  
G. M. Ward ◽  
F. P. Alford
Keyword(s):  
Glucose Uptake ◽  
Tritiated Water ◽  
Insulin Level ◽  
Whole Body ◽  
Glucose Disposal ◽  
Glycolytic Flux ◽  
Insulin Levels ◽  
Glucose Storage ◽  
The Impact

To determine the impact of variable plasma insulin concentrations and glycemia on the partitioning of whole body glucose metabolism between glycolysis and glucose storage, we estimated endogenous hepatic glucose production and rates of in vivo glycolytic flux (GF) and glucose storage (GS) in six normal dogs from the generation of plasma tritiated water (3H2O) and [3-3H]glucose specific activity during 150 min of somatostatin euglycemic (E) and hyperglycemic (H) clamps at hypoinsulinemic, basal, intermediate, and high insulin levels. During both E and H clamps, overall rates of GF and GS increased with the rising insulin levels, but the relative contributions to in vivo glucose disposal of GF decreased, whereas GS rose progressively with increasing insulin levels. The relative contribution of GS during H to overall glucose disposal was greater at the lower insulin level. In addition, in absolute terms, GF and GS were significantly higher (P < 0.05) during H than during E at all insulin levels. Moreover, the incremental rise in GF induced by H was equal for the low to intermediate insulin levels tested, independent of the prevailing free fatty acid (FFA) levels. However, when whole body glucose disposal rates were matched, GF and GS rates were independent of the coexisting glycemia, insulin, and/or FFA levels. We conclude that 1) insulin has a major impact on the intracellular fate of infused glucose, with a lesser but significant effect of hyperglycemia per se on these processes; 2) the magnitude of the hyperglycemia-induced increase in GF is independent of the prevailing insulin level from low to intermediate levels; and 3) in vivo GF and GS are dependent on the net rate of glucose uptake into cells but independent of absolute FFA levels or whether glucose uptake is stimulated by raised insulin or glucose levels.

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