CPG-Controlled Frontal Biped Model for the Evaluation of Pathological Gait

2009 ◽  
Author(s):  
Betsy V. Hunter ◽  
Yasin Y. Dhaher
Keyword(s):  
Three Dimensional ◽  
Frontal Plane ◽  
Experimental Conditions ◽  
Gait Adaptation ◽  
Gait Kinematics ◽  
Model Dynamics ◽  
Stable Gait ◽  
Pathological Gait ◽  
Inclined Surface

Increased frontal-plane hip movement of the affected leg during the swing phase is a commonly observed gait adaptation in stroke patients. Recent evidence suggests that pathologically-induced torque coupling may contribute to asymmetric gait behaviors observed following stroke. This study proposes to use a CPG-controlled three-dimensional (3D) bipedal model to quantify the effects of abnormal torque coupling on frontal plane gait kinematics. Model dynamics have been evaluated using overground data collection observed under comparable in vivo experimental conditions. The CPG controller has demonstrated ability to provide sustained stable gait over an inclined surface in a simplified model. Preliminary results indicate that the proposed framework is feasible to control a 3D model for investigating the effects of torque coupling on the abnormal frontal plane kinematics of pathological gait.

Rationale for a Modified Crutch Use Methodology for Individuals With Weak or Paralyzed Hip Abductor Muscles

2013 ◽  
Author(s):  
James Borrelli ◽  
Henry W. Haslach
Keyword(s):  
Three Dimensional ◽  
Frontal Plane ◽  
The Body ◽  
Moment Arm ◽  
Gait Kinematics ◽  
Hip Abductor ◽  
Pathological Gait ◽  
The Moment ◽  
Positive Effect ◽  
Traditional Manner

Individuals with weak or paralyzed hip abductors may make use of two methods to reduce pathological gait kinematics as a result of their disability; reducing the need for the hip abductors or developing an equivalent torque on the body. Compensatory motions such as torso tilting or hip hiking “balance” the body reducing the need for the torque that would be developed by the hip abductors. A contralateral crutch develops a body torque that is equivalent to that developed by the hip abductors. Individuals with weak or paralyzed hip abductors intuitively adopt a wide crutch stance, contrary to the prescribed method where the crutches are vertical in the frontal plane. Using a wide stance angle in the frontal plane is hypothesized to improve gait with weak or paralyzed hip abductors more so than when using crutches in the traditional manner. Crutches develop a torque on the body that is equivalent to what would be developed by the hip abductors while standing still. A wide stance angle increases the moment arm that the crutch force acts through while standing still, increasing the torque developed, potentially increasing the positive effect of the crutch which may reduce the need for compensatory motions. However, a similar effect has not been characterized during gait. The hypothesis is that a wide crutch stance angle improves a gait with paralyzed hip abductors more so than a crutch used vertically in the frontal plane. The assumption is that this is accomplished by decreasing energy expenditure and/or reducing the need for compensatory motions more so than a crutch used vertically in the frontal plane. A three-dimensional dynamic model is used to test the hypothesis. The model predicts that excessive pelvis depression and decreased pelvic rotation result when the hip abductors are paralyzed. Compensatory motions, hip hiking and torso tilting, and crutch use are shown to decrease the prevalence of pathological kinematics. Crutch use with a wide stance angle improves gait kinematics more than a vertical crutch with the same body weight supported on it. This study provides evidence that the need for compensatory motions and the prevalence of pathological gait kinematics may be reduced when using a wide crutch stance angle compared to a vertical crutch stance angle.

scholarly journals Zebrafish Vascular Quantification (ZVQ): a tool for quantification of three-dimensional zebrafish cerebrovascular architecture by automated image analysis

Development ◽  
2022 ◽  
Author(s):  
E. C. Kugler ◽  
J. Frost ◽  
V. Silva ◽  
K. Plant ◽  
K. Chhabria ◽  
...  
Keyword(s):  
Image Analysis ◽  
Rapid Assessment ◽  
Three Dimensional ◽  
Vascular Anatomy ◽  
Light Sheet ◽  
Automated Image Analysis ◽  
Cerebral Vasculature ◽  
Experimental Conditions ◽  
Branching Points

Zebrafish transgenic lines and light sheet fluorescence microscopy allow in-depth insights into three-dimensional vascular development in vivo. However, quantification of the zebrafish cerebral vasculature in 3D remains highly challenging. Here, we describe and test an image analysis workflow for 3D quantification of the total or regional zebrafish brain vasculature, called zebrafish vasculature quantification “ZVQ”. It provides the first landmark- or object-based vascular inter-sample registration of the zebrafish cerebral vasculature, producing Population Average Maps allowing rapid assessment of intra- and inter-group vascular anatomy. ZVQ also extracts a range of quantitative vascular parameters from a user-specified Region of Interest including volume, surface area, density, branching points, length, radius, and complexity. Application of ZVQ to thirteen experimental conditions, including embryonic development, pharmacological manipulations and morpholino induced gene knockdown, shows ZVQ is robust, allows extraction of biologically relevant information and quantification of vascular alteration, and can provide novel insights into vascular biology. To allow dissemination, the code for quantification, a graphical user interface, and workflow documentation are provided. Together, ZVQ provides the first open-source quantitative approach to assess the 3D cerebrovascular architecture in zebrafish.

Quantification of Diastolic Viscoelastic Properties of Isolated Cardiac Muscle Cells

2001 ◽  
Author(s):  
Catalin F. Baicu ◽  
Michael R. Zile
Keyword(s):  
Cardiac Muscle ◽  
Viscoelastic Properties ◽  
Three Dimensional ◽  
Pressure Overload ◽  
Muscle Cells ◽  
Elastic Stiffness ◽  
Experimental Conditions ◽  
Cardiac Muscle Cells ◽  
Diastolic Properties

Abstract Pathological processes which cause diastolic congestive heart failure (CHF), such as pressure overload hypertrophy (POH), produce abnormalities in the material properties of cardiac muscle cells (cardiomyocytes) and may selectively alter its elastic stiffness, viscosity, or both. Previous methods used to characterize these cardiomyocyte viscoelastic properties were constrained by specific biological and engineering limitations, which prevented testing in conditions that mimic normal physiology. The current study proposes an uniaxial variable-rate stretching method, in which isolated cardiomyocytes embedded in a three-dimensional gel matrix were subjected to stretch. Physiological Ca++ (2.5 mM) and rapid stretch rates up to 100 μm/sec provided experimental conditions parallel to in vivo physiology. The proposed method identified and individually quantified both cellular stiffness and viscosity, and showed that POH increased both elastic and viscous cardiomyocyte diastolic properties.

Intracellular diaphragmed fenestrae in cultured capillary endothelial cells

1988 ◽  
Vol 89 (3) ◽  
pp. 441-447 ◽  
Author(s):  
R. Montesano ◽  
L. Orci
Keyword(s):  
Endothelial Cells ◽  
Endothelial Cell ◽  
Three Dimensional ◽  
Collagen Matrix ◽  
Cell Cytoplasm ◽  
Experimental Conditions ◽  
Intracellular Location ◽  
Capillary Endothelial Cells

The endothelium of visceral capillaries is characterized by the occurrence of numerous fenestrae, which are usually bridged by a thin, single-layered diaphragm. Both in vivo and in vitro, diaphragmed fenestrae perforate the endothelial cell cytoplasm in the most attenuated regions of the cell. We report here that in capillary endothelial cells grown under experimental conditions promoting the development of intracellular lumina (for example, suspension within a three-dimensional collagen matrix), diaphragmed fenestrae can form in a unique, previously undescribed intracellular location - that is, within thin cytoplasmic septa separating contiguous luminal compartments.

scholarly journals Three-Dimensional Renal Organoids from Whole Kidney Cells: Generation, Optimization, and Potential Application in Nephrotoxicology In Vitro

2020 ◽  
Vol 29 ◽  
pp. 096368971989706 ◽  
Author(s):  
Beichen Ding ◽  
Guoliang Sun ◽  
Shiliang Liu ◽  
Ejun Peng ◽  
Meimei Wan ◽  
...  
Keyword(s):  
Kidney Function ◽  
Drug Screening ◽  
Screening Tool ◽  
Three Dimensional ◽  
Penicillin G ◽  
Kidney Cells ◽  
Experimental Conditions ◽  
Study Results

The kidney function of patients with chronic kidney disease (CKD) is impaired irreversibly. Organ transplantation is the only treatment to restore kidney function in CKD patients. The assessment of new potential therapeutic procedures relies heavily on experimental animal models, but it is limited by its human predictive capacity. In addition, the frequently used two-dimensional in vitro human renal cell models cannot replicate all the features of the in vivo situation. In this study, we developed a three-dimensional (3D) in vitro human renal organoid model from whole kidney cells as a promising drug screening tool. At present, the renal tissue generated from human pluripotent stem cells (hPSCs) exhibits intrinsic tumorigenicity properties. Here we first developed a 3D renal organoid culture system that originated from adult differentiated cells without gene modification. Renal organoids composed of multiple cell types were created under optimal experimental conditions and evaluated for morphology, viability and erythropoietin production. As a novel screening tool for renal toxicity, 3D organoids were exposed to three widely used drugs: aspirin, penicillin G and cisplatin. The study results showed this 3D renal organoid model can be used as a drug screening tool, a new in vitro 3D human kidney model, and provide hope for potential regenerative therapies for CKD.

Clinical determination of the linear equation for the subtalar joint axis

1992 ◽  
Vol 82 (1) ◽  
pp. 1-20 ◽  
Author(s):  
RD Phillips ◽  
RH Lidtke
Keyword(s):  
Linear Equation ◽  
Subtalar Joint ◽  
Angular Displacement ◽  
Three Dimensional ◽  
Frontal Plane ◽  
Linear Displacement ◽  
Transverse Plane ◽  
Joint Movement ◽  
Joint Axis

The authors present a methodology to measure the frontal plane angular and linear displacement and the transverse plane angular displacement of subtalar joint movement. This method is combined with a modification of the Kirby method for determining the transverse plane projection of the subtalar joint axis onto the plantar foot. A mathematical model is then used to construct the subtalar joint axis into a three-dimensional linear equation. Data are obtained from an in vivo series of 62 feet that indicates that within acceptable clinical errors of measurement the subtalar joint is a ginglymus type of joint that moves around a single fixed axis. Results also indicate that the subtalar joint axis is more superior and lateral to the neutral foot than any previous studies on cadaver feet have shown. Finally, the authors show that once the subtalar joint axis can be accurately located, the torque on the joint axis produced by ground reactive forces and muscular forces can be computed.

In vitro and in vivo polysaccharides assembly: ultrastructural and cytochemical study of growing plant cell wall components.

1978 ◽  
Vol 36 (2) ◽  
pp. 434-435
Author(s):  
D. Reis ◽  
B. Vian ◽  
J. C. Roland
Keyword(s):  
Cell Wall ◽  
Self Assembly ◽  
Plant Cell Wall ◽  
Higher Plants ◽  
Three Dimensional ◽  
Cytochemical Study ◽  
Wall Components

Wall morphogenesis in higher plants is a problem still open to controversy. Until now the possibility of a transmembrane control and the involvement of microtubules were mostly envisaged. Self-assembly processes have been observed in the case of walls of Chlamydomonas and bacteria. Spontaneous gelling interactions between xanthan and galactomannan from Ceratonia have been analyzed very recently. The present work provides indications that some processes of spontaneous aggregation could occur in higher plants during the formation and expansion of cell wall.Observations were performed on hypocotyl of mung bean (Phaseolus aureus) for which growth characteristics and wall composition have been previously defined.In situ, the walls of actively growing cells (primary walls) show an ordered three-dimensional organization (fig. 1). The wall is typically polylamellate with multifibrillar layers alternately transverse and longitudinal. Between these layers intermediate strata exist in which the orientation of microfibrils progressively rotates. Thus a progressive change in the morphogenetic activity occurs.

Three-Dimensional Subcellular Organization of Hepatocytes in Intact Liver: Simultaneous Visualization of Cytoskeletal and Membrane Markers by Confocal Microscopy

1996 ◽  
Vol 54 ◽  
pp. 288-289
Author(s):  
Greg V. Martin ◽  
Ann L. Hubbard
Keyword(s):  
Three Dimensional ◽  
Integral Membrane Proteins ◽  
Polarized Secretion ◽  
Microscope Images ◽  
Computer Aided ◽  
Intracellular Organelles ◽  
Cytoskeletal Elements ◽  
Simultaneous Visualization

The microtubule (MT) cytoskeleton is necessary for many of the polarized functions of hepatocytes. Among the functions dependent on the MT-based cytoskeleton are polarized secretion of proteins, delivery of endocytosed material to lysosomes, and transcytosis of integral plasma membrane (PM) proteins. Although microtubules have been shown to be crucial to the establishment and maintenance of functional and structural polarization in the hepatocyte, little is known about the architecture of the hepatocyte MT cytoskeleton in vivo, particularly with regard to its relationship to PM domains and membranous organelles. Using an in situ extraction technique that preserves both microtubules and cellular membranes, we have developed a protocol for immunofluorescent co-localization of cytoskeletal elements and integral membrane proteins within 20 µm cryosections of fixed rat liver. Computer-aided 3D reconstruction of multi-spectral confocal microscope images was used to visualize the spatial relationships among the MT cytoskeleton, PM domains and intracellular organelles.

Superoxide, Xanthine Oxidase and Platelet Reactions: Further Studies on Mechanisms by which Oxidants Influence Platelets

1981 ◽  
Vol 45 (03) ◽  
pp. 290-293 ◽  
Author(s):  
Peter H Levine ◽  
Danielle G Sladdin ◽  
Norman I Krinsky
Keyword(s):  
Superoxide Dismutase ◽  
Cytochrome C ◽  
Xanthine Oxidase ◽  
Direct Effect ◽  
Platelet Function ◽  
Experimental Conditions ◽  
Release Reaction

SummaryIn the course of studying the effects on platelets of the oxidant species superoxide (O- 2), Of was generated by the interaction of xanthine oxidase plus xanthine. Surprisingly, gel-filtered platelets, when exposed to xanthine oxidase in the absence of xanthine substrate, were found to generate superoxide (O- 2), as determined by the reduction of added cytochrome c and by the inhibition of this reduction in the presence of superoxide dismutase.In addition to generating Of, the xanthine oxidase-treated platelets display both aggregation and evidence of the release reaction. This xanthine oxidase induced aggreagtion is not inhibited by the addition of either superoxide dismutase or cytochrome c, suggesting that it is due to either a further metabolite of O- 2, or that O- 2 itself exerts no important direct effect on platelet function under these experimental conditions. The ability of Of to modulate platelet reactions in vivo or in vitro remains in doubt, and xanthine oxidase is an unsuitable source of O- 2 in platelet studies because of its own effects on platelets.

Sign in / Sign up

Export Citation Format

Share Document