Fluid Structural Analysis of Urine Flow in a Stented Ureter

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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About Puncture Testing Applied for Mechanical Characterization of Fetal Membranes

Journal of Biomechanical Engineering ◽

10.1115/1.4028446 ◽

2014 ◽

Vol 136 (11) ◽

Cited By ~ 6

Author(s):

Wilfried Bürzle ◽

Edoardo Mazza ◽

John J. Moore

Keyword(s):

Deformation Behavior ◽

Mechanical Characterization ◽

Ex Vivo ◽

Fetal Membrane ◽

Membrane Rupture ◽

Resistance To Deformation ◽

Ex Vivo Testing ◽

Insight Into

Puncture testing has been applied in several studies for the mechanical characterization of human fetal membrane (FM) tissue, and significant knowledge has been gained from these investigations. When comparing results of mechanical testing (puncture, inflation, and uniaxial tension), we have observed discrepancies in the rupture sequence of FM tissue and significant differences in the deformation behavior. This study was undertaken to clarify these discrepancies. Puncture experiments on FM samples were performed to reproduce previous findings, and numerical simulations were carried out to rationalize particular aspects of membrane failure. The results demonstrate that both rupture sequence and resistance to deformation depend on the samples' fixation. Soft fixation leads to slippage in the clamping, which reduces mechanical loading of the amnion layer and results in chorion rupturing first. Conversely, the stiffer, stronger, and less extensible amnion layer fails first if tight fixation is used. The results provide a novel insight into the interpretation of ex vivo testing as well as in vivo membrane rupture.

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Numerical Sensitivity Analysis for Dielectric Characterization of Biological Samples by Open-Ended Probe Technique

Sensors ◽

10.3390/s20133756 ◽

2020 ◽

Vol 20 (13) ◽

pp. 3756

Author(s):

Marta Cavagnaro ◽

Giuseppe Ruvio

Keyword(s):

Water Content ◽

Ex Vivo ◽

High Water ◽

Biological Tissues ◽

Fundamental Aspect ◽

High Water Content ◽

Insertion Depth ◽

Dielectric Characterization

Dielectric characterization of biological tissues has become a fundamental aspect of the design of medical treatments based on electromagnetic energy delivery and their pre-treatment planning. Among several measuring techniques proposed in the literature, broadband and minimally-invasive open-ended probe measurements are best-suited for biological tissues. However, several challenges related to measurement accuracy arise when dealing with biological tissues in both ex vivo and in vivo scenarios such as very constrained set-ups in terms of limited sample size and probe positioning. By means of the Finite Integration Technique in the CST Studio Suite® software, the numerical accuracy of the reconstruction of the complex permittivity of a high water-content tissue such as liver and a low water-content tissue such as fat is evaluated for different sample dimensions, different location of the probe, and considering the influence of the background environment. It is found that for high water-content tissues, the insertion depth of the probe into the sample is the most critical parameter on the accuracy of the reconstruction. Whereas when low water-content tissues are measured, the probe could be simply placed in contact with the surface of the sample but a deeper and wider sample is required to mitigate biasing effects from the background environment. The numerical analysis proves to be a valid tool to assess the suitability of a measurement set-up for a target accuracy threshold.

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Consequences of SUR2[A478V] Mutation in Skeletal Muscle of Murine Model of Cantu Syndrome

Cells ◽

10.3390/cells10071791 ◽

2021 ◽

Vol 10 (7) ◽

pp. 1791

Author(s):

Rosa Scala ◽

Fatima Maqoud ◽

Nicola Zizzo ◽

Giuseppe Passantino ◽

Antonietta Mele ◽

...

Keyword(s):

Skeletal Muscle ◽

Katp Channel ◽

Ex Vivo ◽

Channel Modulation ◽

Flexor Digitorum Brevis ◽

Inflammatory Edema ◽

Flexor Digitorum ◽

Channel Currents

(1) Background: Cantu syndrome (CS) arises from gain-of-function (GOF) mutations in the ABCC9 and KCNJ8 genes, which encode ATP-sensitive K+ (KATP) channel subunits SUR2 and Kir6.1, respectively. Most CS patients have mutations in SUR2, the major component of skeletal muscle KATP, but the consequences of SUR2 GOF in skeletal muscle are unknown. (2) Methods: We performed in vivo and ex vivo characterization of skeletal muscle in heterozygous SUR2[A478V] (SUR2wt/AV) and homozygous SUR2[A478V] (SUR2AV/AV) CS mice. (3) Results: In SUR2wt/AV and SUR2AV/AV mice, forelimb strength and diaphragm amplitude movement were reduced; muscle echodensity was enhanced. KATP channel currents recorded in Flexor digitorum brevis fibers showed reduced MgATP-sensitivity in SUR2wt/AV, dramatically so in SUR2AV/AV mice; IC50 for MgATP inhibition of KATP currents were 1.9 ± 0.5 × 10−5 M in SUR2wt/AV and 8.6 ± 0.4 × 10−6 M in WT mice and was not measurable in SUR2AV/AV. A slight rightward shift of sensitivity to inhibition by glibenclamide was detected in SUR2AV/AV mice. Histopathological and qPCR analysis revealed atrophy of soleus and tibialis anterior muscles and up-regulation of atrogin-1 and MuRF1 mRNA in CS mice. (4) Conclusions: SUR2[A478V] “knock-in” mutation in mice impairs KATP channel modulation by MgATP, markedly so in SUR2AV/AV, with atrophy and non-inflammatory edema in different skeletal muscle phenotypes.

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Applications of Vibrational Spectroscopy for Analysis of Connective Tissues

Molecules ◽

10.3390/molecules26040922 ◽

2021 ◽

Vol 26 (4) ◽

pp. 922

Author(s):

William Querido ◽

Shital Kandel ◽

Nancy Pleshko

Keyword(s):

Raman Spectroscopy ◽

Vibrational Spectroscopy ◽

Near Infrared ◽

Ex Vivo ◽

Biological Tissues ◽

Label Free ◽

Connective Tissues ◽

Bone Properties ◽

Composition And Structure

Advances in vibrational spectroscopy have propelled new insights into the molecular composition and structure of biological tissues. In this review, we discuss common modalities and techniques of vibrational spectroscopy, and present key examples to illustrate how they have been applied to enrich the assessment of connective tissues. In particular, we focus on applications of Fourier transform infrared (FTIR), near infrared (NIR) and Raman spectroscopy to assess cartilage and bone properties. We present strengths and limitations of each approach and discuss how the combination of spectrometers with microscopes (hyperspectral imaging) and fiber optic probes have greatly advanced their biomedical applications. We show how these modalities may be used to evaluate virtually any type of sample (ex vivo, in situ or in vivo) and how “spectral fingerprints” can be interpreted to quantify outcomes related to tissue composition and quality. We highlight the unparalleled advantage of vibrational spectroscopy as a label-free and often nondestructive approach to assess properties of the extracellular matrix (ECM) associated with normal, developing, aging, pathological and treated tissues. We believe this review will assist readers not only in better understanding applications of FTIR, NIR and Raman spectroscopy, but also in implementing these approaches for their own research projects.

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Characterization of Intrinsically Radiolabeled Poly(lactic-co-glycolic acid) Nanoparticles for ex Vivo Autologous Cell Labeling and in Vivo Tracking

Bioconjugate Chemistry ◽

10.1021/acs.bioconjchem.1c00271 ◽

2021 ◽

Author(s):

Massis Krekorian ◽

Gerwin G. W. Sandker ◽

Kimberley R. G. Cortenbach ◽

Oya Tagit ◽

N. Koen van Riessen ◽

...

Keyword(s):

Glycolic Acid ◽

Ex Vivo ◽

Cell Labeling ◽

Autologous Cell

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Electrophysiological characterization and computational models of HVC neurons in the zebra finch

Journal of Neurophysiology ◽

10.1152/jn.00162.2013 ◽

2013 ◽

Vol 110 (5) ◽

pp. 1227-1245 ◽

Cited By ~ 20

Author(s):

Arij Daou ◽

Matthew T. Ross ◽

Frank Johnson ◽

Richard L. Hyson ◽

Richard Bertram

Keyword(s):

Computational Models ◽

Premotor Cortex ◽

Brain Slices ◽

Ionic Currents ◽

Proper Name ◽

Using Data ◽

Electrophysiological Characterization

The nucleus HVC (proper name) within the avian analog of mammal premotor cortex produces stereotyped instructions through the motor pathway leading to precise, learned vocalization by songbirds. Electrophysiological characterization of component HVC neurons is an important requirement in building a model to understand HVC function. The HVC contains three neural populations: neurons that project to the RA (robust nucleus of arcopallium), neurons that project to Area X (of the avian basal ganglia), and interneurons. These three populations are interconnected with specific patterns of excitatory and inhibitory connectivity, and they fire with characteristic patterns both in vivo and in vitro. We performed whole cell current-clamp recordings on HVC neurons within brain slices to examine their intrinsic firing properties and determine which ionic currents are responsible for their characteristic firing patterns. We also developed conductance-based models for the different neurons and calibrated the models using data from our brain slice work. These models were then used to generate predictions about the makeup of the ionic currents that are responsible for the different responses to stimuli. These predictions were then tested and verified in the slice using pharmacological manipulations. The model and the slice work highlight roles of a hyperpolarization-activated inward current ( Ih), a low-threshold T-type Ca2+ current ( ICa-T), an A-type K+ current ( IA), a Ca2+-activated K+ current ( ISK), and a Na+-dependent K+ current ( IKNa) in driving the characteristic neural patterns observed in the three HVC neuronal populations. The result is an improved characterization of the HVC neurons responsible for song production in the songbird.

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In vivo characterization of the transitional bronchioles by aerosol-derived airway morphometry

Journal of Applied Physiology ◽

10.1152/jappl.1999.87.3.920 ◽

1999 ◽

Vol 87 (3) ◽

pp. 920-927 ◽

Cited By ~ 4

Author(s):

Kirby L. Zeman ◽

Gerhard Scheuch ◽

Knut Sommerer ◽

James S. Brown ◽

William D. Bennett

Keyword(s):

Ex Vivo ◽

Normal Subjects ◽

Characteristic Line ◽

Chronic Obstructive ◽

Obstructive Pulmonary Disease ◽

Lung Capacity ◽

Single Breath ◽

In Vivo Characterization

Effective airway dimensions (EADs) were determined in vivo by aerosol-derived airway morphometry as a function of volumetric lung depth (VLD) to identify and characterize, noninvasively, the caliber of the transitional bronchiole region of the human lung and to compare the EADs by age, gender, and disease. By logarithmically plotting EAD vs. VLD, two distinct regions of the lung emerged that were identified by characteristic line slopes. The intersection of proximal and distal segments was defined as VLDtransand associated EADtrans. In our normal subjects ( n = 20), VLDtrans [345 ± 83 (SD) ml] correlated significantly with anatomic dead space (224 ± 34 ml) and end of phase II of single-breath nitrogen washout (360 ± 53 ml). The corresponding EADtranswas 0.42 ± 0.07 mm, in agreement with other ex vivo measurements of the transitional bronchioles. VLDtrans was smaller (216 ± 64 ml) and EADtrans was larger (0.83 ± 0.04 mm) in our patients with chronic obstructive pulmonary disease ( n = 13). VLDtrans increased with age for children (age 8–18 yr; P = 0.006, n = 26) and with total lung capacity for age 8–81 yr ( P < 0.001, n = 61). This study extends the usefulness of aerosol-derived airway morphometry to in vivo measurements of the transitional bronchioles.

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Between biology and medicine: perspectives on the use of dendritic cells in anticancer therapy

Postępy Higieny i Medycyny Doświadczalnej ◽

10.5604/01.3001.0010.5808 ◽

2017 ◽

Vol 71 (0) ◽

pp. 0-0

Author(s):

Agnieszka Szczygieł ◽

Elżbieta Pajtasz-Piasecka

Keyword(s):

Dendritic Cells ◽

Ex Vivo ◽

Anticancer Therapy ◽

Point Of View ◽

Proper Function ◽

Innate And Adaptive Immunity ◽

Factors Affecting ◽

Antigen Presenting

Dendritic cells (DCs), as a link between innate and adaptive immunity, play a pivotal role in maintaining homeostasis of the immune system. The DC population is characterized by heterogeneity; it consists of many subpopulations which, despite their phenotypic and localization differences, play an essential function – they are professional antigen presenting cells. Due to their role, DCs can be utilized in a new cancer treatment strategy. Their main purpose is to generate an anticancer response leading to the elimination of cancer cells. The tumor microenvironment, abundant in immunosuppressive factors (e.g. IL-10, TGF-β, Arg1, IDO), impairs the proper function of DCs. For this reason, various strategies are necessary for ex vivo preparation of DC-based vaccines and for the support of in vivo DCs to fight against tumors. DC-based vaccines are combined with other forms of immunotherapy (e.g. blockade of immune checkpoint molecules, e.g. PD-1 or CTLA-4) or conventional types of therapies (e.g. chemotherapy). Despite the enormous progress that has been made in anticancer therapy in the past two decades, there are still many unresolved issues regarding the effectiveness of the DCs usage. In this paper we described, in both a mouse and a human subject, a series of DC subpopulations, differentiating in normal conditions or under the influence of cancer microenvironment. We listed factors affecting the quality of the in vivo and ex vivo generations of antitumoral responses, significant from a therapeutic point of view. Moreover, the most important strategies for the use of DCs in anticancer therapies, as well as further developments on this field, have been discussed.

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Ex Vivo Isolation and Characterization of Cd4+Cd25+ T Cells with Regulatory Properties from Human Blood

Journal of Experimental Medicine ◽

10.1084/jem.193.11.1303 ◽

2001 ◽

Vol 193 (11) ◽

pp. 1303-1310 ◽

Cited By ~ 797

Author(s):

Detlef Dieckmann ◽

Heidi Plottner ◽

Susanne Berchtold ◽

Thomas Berger ◽

Gerold Schuler

Keyword(s):

T Cells ◽

Cytotoxic T Lymphocyte ◽

Ex Vivo ◽

Cell Receptor ◽

Regulatory Cells ◽

Suppressor T Cells ◽

Isolation And Characterization ◽

Regulatory Properties

It has been known for years that rodents harbor a unique population of CD4+CD25+ “professional” regulatory/suppressor T cells that is crucial for the prevention of spontaneous autoimmune diseases. Here we demonstrate that CD4+CD25+CD45RO+ T cells (mean 6% of CD4+ T cells) are present in the blood of adult healthy volunteers. In contrast to previous reports, these CD4+CD25+ T cells do not constitute conventional memory cells but rather regulatory cells exhibiting properties identical to their rodent counterparts. Cytotoxic T lymphocyte–associated antigen (CTLA)-4 (CD152), for example, which is essential for the in vivo suppressive activity of CD4+CD25+ T cells, was constitutively expressed, and remained strongly upregulated after stimulation. The cells were nonproliferative to stimulation via their T cell receptor for antigen, but the anergic state was partially reversed by interleukin (IL)-2 and IL-15. Upon stimulation with allogeneic (but not syngeneic) mature dendritic cells or platebound anti-CD3 plus anti-CD28 the CD4+CD25+ T cells released IL-10, and in coculture experiments suppressed the activation and proliferation of CD4+ and CD8+ T cells. Suppression proved IL-10 independent, yet contact dependent as in the mouse. The identification of regulatory CD4+CD25+ T cells has important implications for the study of tolerance in man, notably in the context of autoimmunity, transplantation, and cancer.

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