Direct Measurement of the Permeability of Human Cervical Tissue

2013 ◽  
Vol 135 (2) ◽  
Author(s):  
Michael Fernandez ◽  
Joy Vink ◽  
Kyoko Yoshida ◽  
Ronald Wapner ◽  
Kristin M. Myers
Keyword(s):  
Mechanical Behavior ◽  
Material Behavior ◽  
Patient Specific ◽  
Diagnostic Tools ◽  
Hydraulic Permeability ◽  
Cervical Tissue ◽  
Large Variability ◽  
Developmental Problems ◽  
External Forces

The mechanical integrity of the uterine cervix is critical for a pregnancy to successfully reach full term. It must be strong to retain the fetus throughout gestation and then undergo a remodeling and softening process before labor for delivery of the fetus. It is believed that cervical insufficiency (CI), a condition in pregnancy resulting in preterm birth (PTB), is related to a cervix with compromised mechanical strength which cannot resist deformation caused by external forces generated by the growing fetus. Such PTBs are responsible for infant developmental problems and in severe cases infant mortality. To understand the etiologies of CI, our overall research goal is to investigate the mechanical behavior of the cervix. Permeability is a mechanical property of hydrated collagenous tissues that dictates the time-dependent response of the tissue to mechanical loading. The goal of this study was to design a novel soft tissue permeability testing device and to present direct hydraulic permeability measurements of excised nonpregnant (NP) and pregnant (PG) human cervical tissue from women with different obstetric histories. Results of hydraulic permeability testing indicate repeatability for specimens from single patients, with an order of magnitude separating the NP and PG group means (2.1 ± 1.4×10-14 and 3.2 ± 4.8×10-13m4/N·s, respectively), and large variability within the NP and PG sample groups. Differences were found between samples with similar obstetric histories, supporting the view that medical history may not be a good predictor of permeability (and therefore mechanical behavior) and highlighting the need for patient-specific measurements of cervical mechanical properties. The permeability measurements from this study will be used in future work to model the constitutive material behavior of cervical tissue and to develop in vivo diagnostic tools to stage the progression of labor.

Uniaxial and Biaxial Mechanical Behavior of Human Amnion

2004 ◽  
Vol 844 ◽  
Author(s):  
Michelle L. Oyen ◽  
Triantafyllos Stylianopoulos ◽  
Victor H. Barocas ◽  
Steven E. Calvin ◽  
Robert F. Cook
Keyword(s):  
Energy Dissipation ◽  
Stress Relaxation ◽  
Mechanical Behavior ◽  
Biaxial Tension ◽  
Critical Role ◽  
Material Behavior ◽  
Integral Approach ◽  
Membrane Repair ◽  
Highly Nonlinear

ABSTRACTChorioamnion, the membrane surrounding a fetus during gestation (the “amniotic sac”), is a structural soft tissue for which the mechanical behavior is poorly understood—despite its critical role in maintaining a successful pregnancy and delivery. Preterm rupture of the chorioamnion accounts for one third of all premature births. The structural component of chorioamnion is the amnion sublayer, which provides the membrane's mechanical integrity via a dense collagen network. Amnion uniaxial and planar equi-biaxial tension testing was performed using monotonic loading, cyclic loading and stress-relaxation. The prefailure material behavior was highly nonlinear, exhibiting an approximately quadratic response. Cyclic testing, both uniaxial and biaxial, exhibited dramatic energy dissipation in the first cycle followed by less hysteresis on subsequent cycles and an eventual stable hysteresis response with approximately 20% energy dissipation per cycle. Stress-relaxation testing, both uniaxial and biaxial, demonstrated a load dependent response and continued relaxation after long hold times. A nonlinear viscoelastic (separable) hereditary integral approach was used to model the amnion stress-strain-time response during relaxation. The mechanical results are discussed within the context of the in vivo clinical performance of amnion, and the potential for membrane repair.

Deformable Image Registration Between Cardiac PET Images Encompassing a Range of Physical Heart Sizes

2011 ◽  
Author(s):  
Benjamin R. Coleman ◽  
Alexander I. Veress
Keyword(s):  
Mechanical Performance ◽  
Fe Analysis ◽  
Material Behavior ◽  
Patient Specific ◽  
Stress And Strain ◽  
Myocardial Tissue ◽  
Cardiac Pet ◽  
Considerable Research ◽  
Deformation Stress

Cardiac mechanical performance depends upon myocardial tissue elongation and contraction. Deformation, stress and strain within the myofibers provide valuable information about potential tissue adaptation [1]. Specifically, the stress state of the tissue is believed to drive remodeling of the myocardium. Because it is not possible to measure in-vivo stress in the human heart, considerable research has gone into developing patient specific, mathematical models of the heart based on finite element (FE) analysis and cardiac imaging [2, 3]. Stress estimates from these models could yield valuable information about of the material behavior of the myocardium that would provide valuable information for research into cardiac pathologies.

Training and validation cohort analysis for predicting radiation therapy response in human glioblastoma.

2013 ◽  
Vol 31 (15_suppl) ◽  
pp. e13018-e13018
Author(s):  
David Corwin ◽  
Russell Rockne ◽  
Maciej M. Mrugala ◽  
Jason K. Rockhill ◽  
Kristin Swanson
Keyword(s):  
Mathematical Model ◽  
Radiation Therapy ◽  
Clinical Decision Making ◽  
Cohort Analysis ◽  
Patient Specific ◽  
Clinical Tool ◽  
Disease Heterogeneity ◽  
Large Variability ◽  
Post Surgery

e13018 Background: Glioblastomas comprise 50% of primary brain tumors and are the most fatal, with a median survival time of 14 months despite aggressive treatment. Due to disease heterogeneity and the presence of subclinical disease, there is a large variability in treatment response among patients, making it difficult to assess treatment efficacy and confounding clinical decision making. Methods: A patient-specific, mathematical model of glioblastoma has been shown to predict untreated growth as well as the effect of radiation therapy. We expand on the technique presented in Rockne 2010 to determine patient-specific radiosensitivity and post therapy radial growth using only pretreatment data. From a potential cohort of 44 patients we randomly chose a training set of 30 to compute the relationship for the radiosensitivity parameter (alpha) versus the net proliferation rate. We then used that relationship to compute an individualized alpha for the remaining 14 test patients based only on pretreatment information. For each of the test patients we compared the observed T1Gd visible radius at the first post radiotherapy timepoint with the simulated prediction. Results: Half of the patients demonstrated average absolute differences between the observed and simulated post radiotherapy T1Gd radii of less than 5 mm, within the measurement error associated with contouring the tumor on MRI, with a maximum difference of 2.5 cm. The largest errors were observed in patients with significant resection. Conclusions: This patient-specific, mathematical model of glioma growth and response to radiotherapy can potentially predict radioresponse in vivo, prior to the commencement of therapy. As a clinical tool, this can have prognostic applications and separate responders from non-responders before deciding to treat with radiotherapy. The larger error for patients with more extensive resections is not unexpected given the difficulties in contouring and assessing tumor burden post surgery. This can be improved by including other imaging modalities such as pre-gadolinium T1 and improving the quantification of extent of resection.

Direct Measurement of Human Cervical Tissue Permeability

2012 ◽  
Author(s):  
Michael Fernandez ◽  
Joy Vink ◽  
Ronald Wapner ◽  
Kyoko Yoshida ◽  
Kristin M. Myers
Keyword(s):  
Direct Measurement ◽  
Previous History ◽  
Cervical Tissue ◽  
Confined Compression ◽  
Tissue Samples ◽  
Developmental Problems ◽  
History Of ◽  
Research Goal ◽  
Softening Process

The mechanical integrity of the uterine cervix is critical for the full-term success of a pregnancy. It must be strong to retain the fetus throughout gestation and then undergo a remodeling and softening process before labor to allow dilation and delivery. We hypothesize that the preterm birth (PTB) condition known as cervical insufficiency (CI) is related to a weak or soft cervix. Such PTBs are responsible for infant developmental problems and in severe cases, infant mortality. To understand the etiologies of CI, our overall research goal is to investigate the mechanical behavior of the cervix. As a foundation for future in-vivo tools to assess cervical softness, we aim to quantify cervical structure-material property relationships for nonpregnant (NP) and pregnant (PG) tissue from women with different obstetric backgrounds, including women with a previous history of CI. The goal of this study is to characterize cervical tissue as a poroelastic (biphasic) material. Here we present the results of two mechanical experiments on NP and PG hysterectomy cervical tissue samples: first, confined compression and second, direct measurement of permeability by a custom strain-adjustable permeation rig.

scholarly journals mRNA-Driven Generation of Transgene-Free Neural Stem Cells from Human Urine-Derived Cells

Cells ◽  
2019 ◽  
Vol 8 (9) ◽  
pp. 1043 ◽  
Author(s):  
Phil Jun Kang ◽  
Daryeon Son ◽  
Tae Hee Ko ◽  
Wonjun Hong ◽  
Wonjin Yun ◽  
...  
Keyword(s):  
Stem Cells ◽  
Neural Stem Cells ◽  
Human Urine ◽  
Neurological Disorders ◽  
Therapeutic Potential ◽  
Embryonic Stem ◽  
Global Gene Expression ◽  
Patient Specific ◽  
Human Neural Stem Cells

Human neural stem cells (NSCs) hold enormous promise for neurological disorders, typically requiring their expandable and differentiable properties for regeneration of damaged neural tissues. Despite the therapeutic potential of induced NSCs (iNSCs), a major challenge for clinical feasibility is the presence of integrated transgenes in the host genome, contributing to the risk for undesired genotoxicity and tumorigenesis. Here, we describe the advanced transgene-free generation of iNSCs from human urine-derived cells (HUCs) by combining a cocktail of defined small molecules with self-replicable mRNA delivery. The established iNSCs were completely transgene-free in their cytosol and genome and further resembled human embryonic stem cell-derived NSCs in the morphology, biological characteristics, global gene expression, and potential to differentiate into functional neurons, astrocytes, and oligodendrocytes. Moreover, iNSC colonies were observed within eight days under optimized conditions, and no teratomas formed in vivo, implying the absence of pluripotent cells. This study proposes an approach to generate transplantable iNSCs that can be broadly applied for neurological disorders in a safe, efficient, and patient-specific manner.

Design, Fabrication, and Accuracy of a Novel Noncovering Lock-Mechanism Bilateral Patient-Specific Drill Guide Template for Nondeformed and Deformed Thoracic Spines

2021 ◽  
pp. 155633162199633
Author(s):  
Mehran Ashouri-Sanjani ◽  
Shima Mohammadi-Moghadam ◽  
Parisa Azimi ◽  
Navid Arjmand
Keyword(s):  
Thoracic Spine ◽  
Sagittal Plane ◽  
Ct Scanning ◽  
Entry Point ◽  
In Vivo Studies ◽  
Patient Specific ◽  
Plane Angle ◽  
Severe Scoliosis ◽  
3D Printed

Background: Pedicle screw (PS) placement has been widely used in fusion surgeries on the thoracic spine. Achieving cost-effective yet accurate placements through nonradiation techniques remains challenging. Questions/Purposes: Novel noncovering lock-mechanism bilateral vertebra-specific drill guides for PS placement were designed/fabricated, and their accuracy for both nondeformed and deformed thoracic spines was tested. Methods: One nondeformed and 1 severe scoliosis human thoracic spine underwent computed tomographic (CT) scanning, and 2 identical proportions of each were 3-dimensional (3D) printed. Pedicle-specific optimal (no perforation) drilling trajectories were determined on the CT images based on the entry point/orientation/diameter/length of each PS. Vertebra-specific templates were designed and 3D printed, assuring minimal yet firm contacts with the vertebrae through a noncovering lock mechanism. One model of each patient was drilled using the freehand and one using the template guides (96 pedicle drillings). Postoperative CT scans from the models with the inserted PSs were obtained and superimposed on the preoperative planned models to evaluate deviations of the PSs. Results: All templates fitted their corresponding vertebra during the simulated operations. As compared with the freehand approach, PS placement deviations from their preplanned positions were significantly reduced: for the nonscoliosis model, from 2.4 to 0.9 mm for the entry point, 5.0° to 3.3° for the transverse plane angle, 7.1° to 2.2° for the sagittal plane angle, and 8.5° to 4.1° for the 3D angle, improving the success rate from 71.7% to 93.5%. Conclusions: These guides are valuable, as the accurate PS trajectory could be customized preoperatively to match the patients’ unique anatomy. In vivo studies will be required to validate this approach.

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