scholarly journals Relationships between in vivo surface and ex vivo electrical impedance myography measurements in three different neuromuscular disorder mouse models

PLoS ONE ◽  
2021 ◽  
Vol 16 (10) ◽  
pp. e0259071
Author(s):  
Sarbesh R. Pandeya ◽  
Janice A. Nagy ◽  
Daniela Riveros ◽  
Carson Semple ◽  
Rebecca S. Taylor ◽  
...  
Keyword(s):  
Electrical Impedance ◽  
Ex Vivo ◽  
Neuromuscular Disorders ◽  
Neuromuscular Disorder ◽  
Mdx Mouse ◽  
Obese Mouse ◽  
Moderate Degree ◽  
Frequency Range ◽  
Low Frequencies

Electrical impedance myography (EIM) using surface techniques has shown promise as a means of diagnosing and tracking disorders affecting muscle and assessing treatment efficacy. However, the relationship between such surface-obtained impedance values and pure muscle impedance values has not been established. Here we studied three groups of diseased and wild-type (WT) animals, including a Duchenne muscular dystrophy model (the D2-mdx mouse), an amyotrophic lateral sclerosis (ALS) model (the SOD1 G93A mouse), and a model of fat-related atrophy (the db/db diabetic obese mouse), performing hind limb measurements using a standard surface array and ex vivo measurements on freshly excised gastrocnemius muscle. A total of 101 animals (23 D2-mdx, 43 ALS mice, 12 db/db mice, and corresponding 30 WT mice) were studied with EIM across a frequency range of 8 kHz to 1 MHz. For both D2-mdx and ALS models, moderate strength correlations (Spearman rho values generally ranging from 0.3–0.7, depending on the impedance parameter (i.e., resistance, reactance and phase) were obtained. In these groups of animals, there was an offset in frequency with impedance values obtained at higher surface frequencies correlating more strongly to impedance values obtained at lower ex vivo frequencies. For the db/db model, correlations were comparatively weaker and strongest at very high and very low frequencies. When combining impedance data from all three disease models together, moderate correlations persisted (with maximal Spearman rho values of 0.45). These data support that surface EIM data reflect ex vivo muscle tissue EIM values to a moderate degree across several different diseases, with the highest correlations occurring in the 10–200 kHz frequency range. Understanding these relationships will prove useful for future applications of the technique of EIM in the assessment of neuromuscular disorders.

scholarly journals Electrical impedance myography for the in vivo and ex vivo assessment of muscular dystrophy (mdx ) mouse muscle

2014 ◽  
Vol 49 (6) ◽  
pp. 829-835 ◽  
Author(s):  
Jia Li ◽  
Tom R. Geisbush ◽  
Glenn D. Rosen ◽  
Jennifer Lachey ◽  
Aaron Mulivor ◽  
...  
Keyword(s):  
Muscular Dystrophy ◽  
Electrical Impedance ◽  
Ex Vivo ◽  
Mdx Mouse ◽  
Mouse Muscle

scholarly journals Differential impact of Kv8.2 loss on rod and cone signaling and degeneration.

2021 ◽  
Author(s):  
Shivangi M Inamdar ◽  
Colten K Lankford ◽  
Deepak Poria ◽  
Joseph G Laird ◽  
Eduardo Solessio ◽  
...  
Keyword(s):  
Membrane Potential ◽  
Ex Vivo ◽  
Light Stimulus ◽  
Resting Membrane Potential ◽  
Cone Dystrophy ◽  
Extracellular Potassium ◽  
Delayed Response ◽  
Low Frequencies ◽  
Ionic Imbalance

The voltage-gated potassium channel responsible for controlling photoreceptor signaling is a heteromeric complex of Kv2.1 subunits with a regulatory Kv8.2 subunit. Kv2.1/Kv8.2 channels are localized to the photoreceptor inner segment and carry IKx, largely responsible for setting the photoreceptor resting membrane potential. Mutations in Kv8.2 result in childhood-onset Cone Dystrophy with Supernormal Rod Response (CDSRR). We generated a Kv8.2 knockout (KO) mouse and examined retinal signaling and photoreceptor degeneration to gain deeper insight into the complex phenotypes of this disease. Using electroretinograms we show that there is a tradeoff between delayed or reduced signaling from rods depending on the intensity of the light stimulus, consistent with reduced capacity for light-evoked changes in membrane potential. The delayed response was not seen ex vivo where extracellular potassium levels are the same, so we conclude the in vivo alteration is influenced by ionic imbalance. We observed mild retinal degeneration. Signaling from cones was reduced but there was no loss of cone density. Loss of Kv8.2 altered responses to flickering light with responses attenuated at high frequencies and altered in shape at low frequencies. The Kv8.2 KO line on an all-cone retina background had reduced cone signaling associated with degeneration. We conclude that Kv8.2 is required by rods and cones for responding to dynamic changes in lighting. The timing and cell type affected by degeneration is different in the mouse and human but there is a window of time in both for therapeutic intervention.

scholarly journals Ultrasonography validation for early alteration of diaphragm echodensity and function in the mdx mouse model of Duchenne muscular dystrophy

PLoS ONE ◽  
2021 ◽  
Vol 16 (1) ◽  
pp. e0245397
Author(s):  
Antonietta Mele ◽  
Paola Mantuano ◽  
Adriano Fonzino ◽  
Francesco Rana ◽  
Roberta Francesca Capogrosso ◽  
...  
Keyword(s):  
Duchenne Muscular Dystrophy ◽  
Muscular Dystrophy ◽  
Mouse Model ◽  
Ex Vivo ◽  
Eccentric Contraction ◽  
Invasive Technique ◽  
Mdx Mouse ◽  
Early Stages ◽  
Over Time

The mdx mouse model of Duchenne muscular dystrophy is characterized by functional and structural alterations of the diaphragm since early stages of pathology, closely resembling patients’ condition. In recent years, ultrasonography has been proposed as a useful longitudinal non-invasive technique to assess mdx diaphragm dysfunction and evaluate drug efficacy over time. To date, only a few preclinical studies have been conducted. Therefore, an independent validation of this method by different laboratories is needed to increase results reliability and reduce biases. Here, we performed diaphragm ultrasonography in 3- and 6-month-old mdx mice, the preferred age-window for pharmacology studies. The alteration of diaphragm function over time was measured as diaphragm ultrasound movement amplitude. At the same time points, a first-time assessment of diaphragm echodensity was performed, as an experimental index of progressive loss of contractile tissue. A parallel evaluation of other in vivo and ex vivo dystrophy-relevant readouts was carried out. Both 3- and 6-month-old mdx mice showed a significant decrease in diaphragm amplitude compared to wild type (wt) mice. This index was well-correlated either with in vivo running performance or ex vivo isometric tetanic force of isolated diaphragm. In addition, diaphragms from 6-month-old dystrophic mice were also highly susceptible to eccentric contraction ex vivo. Importantly, we disclosed an age-dependent increase in echodensity in mdx mice not observed in wt animals, which was independent from abdominal wall thickness. This was accompanied by a notable increase of pro-fibrotic TGF-β1 levels in the mdx diaphragm and of non-muscle tissue amount in diaphragm sections stained by hematoxylin & eosin. Our findings corroborate the usefulness of diaphragm ultrasonography in preclinical drug studies as a powerful tool to monitor mdx pathology progression since early stages.

scholarly journals β-Dystroglycan Restoration and Pathology Progression in the Dystrophic mdx Mouse: Outcome and Implication of a Clinically Oriented Study with a Novel Oral Dasatinib Formulation

Biomolecules ◽  
2021 ◽  
Vol 11 (11) ◽  
pp. 1742
Author(s):  
Paola Mantuano ◽  
Brigida Boccanegra ◽  
Elena Conte ◽  
Michela De Bellis ◽  
Santa Cirmi ◽  
...  
Keyword(s):  
Mechanism Of Action ◽  
Ex Vivo ◽  
Mdx Mouse ◽  
Mdx Mice ◽  
Partial Recovery ◽  
Glycoprotein Complex ◽  
Promising Therapeutic Target ◽  
Potential Synergy ◽  
Dystrophin Glycoprotein Complex

ROS-activated cSrc tyrosine kinase (TK) promotes the degradation of β-dystroglycan (β-DG), a dystrophin-glycoprotein complex component, which may reinforce damaging signals in Duchenne muscular dystrophy (DMD). Therefore, cSrc-TK represents a promising therapeutic target. In mdx mice, a 4-week subcutaneous treatment with dasatinib (DAS), a pan-Src-TKs inhibitor approved as anti-leukemic agent, increased muscle β-DG, with minimal amelioration of morphofunctional indices. To address possible dose/pharmacokinetic (PK) issues, a new oral DAS/hydroxypropyl(HP)-β-cyclodextrin(CD) complex was developed and chronically administered to mdx mice. The aim was to better assess the role of β-DG in pathology progression, meanwhile confirming DAS mechanism of action over the long-term, along with its efficacy and tolerability. The 4-week old mdx mice underwent a 12-week treatment with DAS/HP-β-CD10% dissolved in drinking water, at 10 or 20 mg/kg/day. The outcome was evaluated via in vivo/ex vivo disease-relevant readouts. Oral DAS/HP-β-CD efficiently distributed in mdx mice plasma and tissues in a dose-related fashion. The new DAS formulation confirmed its main upstream mechanism of action, by reducing β-DG phosphorylation and restoring its levels dose-dependently in both diaphragm and gastrocnemius muscle. However, it modestly improved in vivo neuromuscular function, ex vivo muscle force, and histopathology, although the partial recovery of muscle elasticity and the decrease of CK and LDH plasma levels suggest an increased sarcolemmal stability of dystrophic muscles. Our clinically oriented study supports the interest in this new, pediatric-suitable DAS formulation for proper exposure and safety and for enhancing β-DG expression. This latter mechanism is, however, not sufficient by itself to impact on pathology progression. In-depth analyses will be dedicated to elucidating the mechanism limiting DAS effectiveness in dystrophic settings, meanwhile assessing its potential synergy with dystrophin-based molecular therapies.

scholarly journals Novel method to study pericyte contractility and responses to ischaemia in vitro using electrical impedance

2016 ◽  
Vol 37 (6) ◽  
pp. 2013-2024 ◽  
Author(s):  
Ain A Neuhaus ◽  
Yvonne Couch ◽  
Brad A Sutherland ◽  
Alastair M Buchan
Keyword(s):  
Electrical Impedance ◽  
Ex Vivo ◽  
Capillary Endothelium ◽  
Tissue Slices ◽  
In Vitro Techniques ◽  
Endothelin 1 ◽  
Mural Cells ◽  
Novel Method

Pericytes are contractile vascular mural cells overlying capillary endothelium, and they have been implicated in a variety of functions including regulation of cerebral blood flow. Recent work has suggested that both in vivo and ex vivo, ischaemia causes pericytes to constrict and die, which has implications for microvascular reperfusion. Assessing pericyte contractility in tissue slices and in vivo is technically challenging, while in vitro techniques remain unreliable. Here, we used isolated cultures of human brain vascular pericytes to examine their contractile potential in vitro using the iCelligence electrical impedance system. Contraction was induced using the vasoactive peptide endothelin-1, and relaxation was demonstrated using adenosine and sodium nitroprusside. Endothelin-1 treatment also resulted in increased proliferation, which we were able to monitor in the same cell population from which we recorded contractile responses. Finally, the observation of pericyte contraction in stroke was reproduced using chemical ischaemia, which caused a profound and irreversible contraction clearly preceding cell death. These data demonstrate that isolated pericytes retain a contractile phenotype in vitro, and that it is possible to quantify this contraction using real-time electrical impedance recordings, providing a significant new platform for assessing the effects of vasoactive and vasculoprotective compounds on pericyte contractility.

scholarly journals Radiosynthesis and preclinical evaluation of a carbon-11 labeled PDE7 inhibitor for PET neuroimaging

2021 ◽  
Author(s):  
Zhiwei Xiao ◽  
Jiyun Sun ◽  
Masayuki Fujinaga ◽  
Huiyi Wei ◽  
Chunyu Zhao ◽  
...  
Keyword(s):  
Ex Vivo ◽  
Specific Binding ◽  
Cell Uptake ◽  
Mammalian Brain ◽  
Intracellular Camp ◽  
Moderate Degree ◽  
Preclinical Evaluation ◽  
Ex Vivo Biodistribution

Background: Dysfunction of cyclic nucleotide phosphodiesterase 7 (PDE7) has been associated with excess intracellular cAMP concentrations, fueling pathogenic processes that are implicated in neurodegenerative disorders. The aim of this study was to develop a suitable PDE7-targeted positron emission tomography (PET) probe that allows non-invasive mapping of PDE7 in the mammalian brain. Methods: Based on a spiro cyclohexane-1,4'-quinazolinone scaffold with known inhibitory properties towards PDE7, we designed and synthesized a methoxy analog that was suitable for carbon-11 labeling. Radiosynthesis was conducted with the respective desmethyl precursor using [11C]MeI. The resulting PET probe, codenamed [11C]26, was evaluated by cell uptake studies, ex vivo biodistribution and radiometabolite studies, as well as in vivo PET experiments in rodents and non-human primates (NHP). Results: Target compound 26 and the corresponding phenolic precursor were synthesized in 2-3 steps with overall yields of 49.5% and 12.4%, respectively. An inhibitory constant (IC50) of 31 nM towards PDE7A was obtained and no significant interaction with other PDE isoforms were observed. [11C]26 was synthesized in high molar activities (170 - 220 GBq/μmol) with radiochemical yields of 34±7%. In vitro cell uptake of [11C]26 was 6-7 fold higher in PDE7B overexpressing cells, as compared to the controls, whereas an in vitro specificity of up to 90% was measured. Ex vivo metabolite studies revealed a high fraction of intact parent in the rat brain (98% at 5 min and 75% at 30 min post injection). Considerable brain penetration was further corroborated by ex vivo biodistribution and PET imaging studies – the latter showing heterogenic brain uptake. While marginal specific binding was observed by PET studies in rodents, a moderate, but dose-dependent, blockade was observed in the NHP brain following pretreatment with non-radioactive 26. Conclusion: In this work, we report on the preclinical evaluation of [11C]26 ( [11C]P7-2104), a PDE7-targeted PET ligand that is based on a spiroquinazolinone scaffold. [11C]26 displayed promising in vitro performance characteristics, a moderate degree of specific binding in PET studies with NHP. Accordingly, [11C]26 will serve as a valuable lead compound for the development of a new arsenal of PDE7-targeted probes with potentially improved in vivo specificity.

scholarly journals Electrical characterization of bolus material as phantom for use in electrical impedance and computed tomography fusion imaging

2019 ◽  
Vol 5 (1) ◽  
pp. 34-39 ◽  
Author(s):  
Parvind K Grewal ◽  
Majid Shokoufi ◽  
Jeff Liu ◽  
Krishnan Kalpagam ◽  
Kirpal S Kohli
Keyword(s):  
Electrical Impedance ◽  
Electrical Characterization ◽  
Fusion Imaging ◽  
Biological Tissues ◽  
Frequency Range ◽  
Imaging Studies ◽  
Impedance Tomography ◽  
Clinical Imaging

Abstract Phantoms are widely used in medical imaging to predict image quality prior to clinical imaging. This paper discusses the possible use of bolus material, as a conductivity phantom, for validation and interpretation of electrical impedance tomography (EIT) images. Bolus is commonly used in radiation therapy to mimic tissue. When irradiated, it has radiological characteristics similar to tissue. With increased research interest in CT/EIT fusion imaging there is a need to find a material which has both the absorption coefficient and electrical conductivity similar to biological tissues. In the present study the electrical properties, specifically resistivity, of various commercially available bolus materials were characterized by comparing their frequency response with that of in-vivo connective adipose tissue. It was determined that the resistivity of Gelatin Bolus is similar to in-vivo tissue in the frequency range 10 kHz to 1MHz and therefore has potential to be used in EIT/CT fusion imaging studies.

scholarly journals Bioimpedance and Bone Fracture Detection: A State of the Art

2019 ◽  
Author(s):  
Antonio Dell'Osa ◽  
Franco Simini ◽  
Jose C. Felice
Keyword(s):  
Bone Fracture ◽  
Electrical Impedance ◽  
Ex Vivo ◽  
New Technology ◽  
Electrical Impedance Spectroscopy ◽  
Long Bone ◽  
Fracture Detection ◽  
Impedance Tomography ◽  
Non Invasive

Bioimpedance measurements are used increasingly in health applications because bioelectric parameters have been associated with anatomical and physiological properties, thus enabling to distinguish medical conditions. For bone fracture diagnostics, nevertheless, there is no established non-invasive method. Ex vivo studies and In vivo bioimpedance procedures, both invasive and non-invasive, on mammalians long bones are associated with promising results. In this work, out of a total of 568 papers, we reviewd 59 articles that mention long bone integrity by electric properties, be it Bioimpedance Analysis, Electrical Impedance Spectroscopy or Electrical Impedance Tomography. The papers are described in three sections, “Ex vivo measurements”, “In vivo invasive measurements” and “In vivo non-invasive measurements”. This review allows to establish the basics to planning the development of new technology to detect bone fracture via bioimpedance measurements.

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