Corrigendum to Ellerbrock et al. (2018) “Four in vivo g-ratio-weighted imaging methods: Comparability and repeatability at the group level”

Endothelin (ET) receptor dysregulation has been described in a number of pathophysiological processes, including cardiovascular disorders, renal failure, and cancer. The aim of this study was to evaluate the expression of the ET-A receptor (ETAR) in murine models of thyroid carcinoma using optical imaging methods. A recently developed near-infrared fluorescent tracer was first assessed in isolated artery preparations for its functional performance in comparison with known ETAR antagonists BQ123 and PD156707. Before evaluation of the tracer in vivo, different thyroid carcinoma cell lines were characterized with respect to their ET receptor expression by RT-PCR and autoradiography. In vivo, sc and orthotopic papillary thyroid tumor xenografts were clearly visualized by fluorescence reflectance imaging and fluorescence-mediated tomography up to 48 h after injection of the tracer. Binding specificity of the probe was demonstrated by predosing with PD156707 as a competing inhibitor. In conclusion, optical imaging with a fluorescent ETAR tracer allows the noninvasive imaging of tumor-associated ETAR expression in vivo. In the future, this technique may help surgeons to evaluate lesion dimensions in intraoperative settings (e.g. thyroidectomy).

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Analysis of White Matter Damage in Patients with Multiple Sclerosis via a Novel In Vivo MR Method for Measuring Myelin, Axons, and G-Ratio

American Journal of Neuroradiology ◽

10.3174/ajnr.a5312 ◽

2017 ◽

Vol 38 (10) ◽

pp. 1934-1940 ◽

Cited By ~ 25

Author(s):

A. Hagiwara ◽

M. Hori ◽

K. Yokoyama ◽

M. Nakazawa ◽

R. Ueda ◽

...

Keyword(s):

Multiple Sclerosis ◽

White Matter ◽

White Matter Damage ◽

G Ratio

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Mapping axon conduction delays in vivo from microstructural MRI

10.1101/503763 ◽

2018 ◽

Cited By ~ 1

Author(s):

Mark Drakesmith ◽

Derek K Jones

Keyword(s):

Conduction Velocity ◽

Action Potentials ◽

Volume Fraction ◽

Relative Sensitivity ◽

Significant Advance ◽

Relaxation Processes ◽

Neural Communication ◽

Axonal Density ◽

G Ratio

AbstractThe conduction velocity (CV) of action potentials along axons is a key neurophysiological property central to neural communication. The ability to estimate CV in humans in vivo from non-invasive MRI methods would therefore represent a significant advance in neuroscience. However, there are 2 major challenges that this paper aims to address: (1) much of the complexity of the neurophysiology of action potentials cannot be captured with currently available MRI techniques. Therefore, we seek to establish the variability in CV that can be captured when predicting CV purely from parameters that can be estimated from MRI (axon diameter and g-ratio); and (2) errors inherent in existing MRI-based biophysical models of tissue will propagate through to estimates of CV, the extent to which is currently unknown.Issue (1) is investigated by performing a sensitivity analysis on a comprehensive model of axon electrophysiology and determining the relative sensitivity to various morphological and electrical parameters.The investigations suggest that 89.2 % of the variance in CV is accounted for by variation in AD and g-ratio. The observed dependency of CV on AD and g-ratio is well characterised by a previously reported model by Rushton.Issue (2) is investigated through simulation of diffusion and relaxometry MRI data for a range of axon morphologies, applying models of restricted diffusion and relaxation processes to derive estimates of axon volume fraction (AVF), AD and g-ratio and estimating CV from the derived parameters. The results show that errors in the AVF have the biggest detrimental impact on estimates of CV, particularly for sparse fibre populations (AVF< 0.3). CV estimates are most accurate (below 5% error) where AVF is above 0.3, g-ratio is between 0.6 and 0.85 and AD is below 10 µm. Fortunately, these parameter bounds are typically satisfied by most myelinated axons.In conclusion, we demonstrate that accurate CV estimates can be inferred in axon populations across a range of configurations, except in some exceptional cases or where axonal density is low. As a proof of concept, for the first time, we generated an in vivo map of conduction velocity in the human corpus callosum with estimates consistent with values previously reported from invasive electrophysiology in primates.

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Sodium Alginate as a Potential Therapeutic Filler: An In Vivo Study in Rats

Marine Drugs ◽

10.3390/md18100520 ◽

2020 ◽

Vol 18 (10) ◽

pp. 520

Author(s):

Masanori Mori ◽

Rintaro Asahi ◽

Yoshihiro Yamamoto ◽

Takanobu Mashiko ◽

Kayo Yoshizumi ◽

...

Keyword(s):

Sodium Alginate ◽

Sodium Hyaluronate ◽

Capsule Formation ◽

Filler Injection ◽

Mannuronic Acid ◽

Guluronic Acid ◽

Therapeutic Value ◽

G Ratio

Filler injection demand is increasing worldwide, but no ideal filler with safety and longevity currently exists. Sodium alginate (SA) is the sodium salt of alginic acid, which is a polymeric polysaccharide obtained by linear polymerization of two types of uronic acid, d-mannuronic acid (M) and l-guluronic acid (G). This study aimed to evaluate the therapeutic value of SA. Nine SA types with different M/G ratios and viscosities were tested and compared with a commercially available sodium hyaluronate (SH) filler. Three injection modes (onto the periosteum, intradermally, or subcutaneously) were used in six rats for each substance, and the animals were sacrificed at 4 or 24 weeks. Changes in the diameter and volume were measured macroscopically and by computed tomography, and histopathological evaluations were performed. SA with a low M/G ratio generally maintained skin uplift. The bulge gradually decreased over time but slightly increased at 4 weeks in some samples. No capsule formation was observed around SA. However, granulomatous reactions, including macrophage recruitment, were observed 4 weeks after SA implantation, although fewer macrophages and granulomatous reactions were observed at 24 weeks. The long-term volumizing effects and degree of granulomatous reactions differed depending on the M/G ratio and viscosity. By contrast, SH showed capsule formation but with minimal granulomatous reactions. The beneficial and adverse effects of SA as a filler differed according to the viscosity or M/G ratio, suggesting a better long-term volumizing effect than SH with relatively low immunogenicity

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Anacardic acid induces IL-33 and promotes remyelination in CNS

Proceedings of the National Academy of Sciences ◽

10.1073/pnas.2006566117 ◽

2020 ◽

Vol 117 (35) ◽

pp. 21527-21535 ◽

Cited By ~ 1

Author(s):

Åsa Ljunggren-Rose ◽

Chandramohan Natarajan ◽

Pranathi Matta ◽

Akansha Pandey ◽

Isha Upender ◽

...

Keyword(s):

Experimental Models ◽

Anacardic Acid ◽

Myelin Proteins ◽

Cns Injury ◽

Electron Microscopic ◽

Experimental Allergic Encephalitis ◽

Microscopic Studies ◽

G Ratio ◽

Direct Induction

Given the known neuroreparative actions of IL-33 in experimental models of central nervous system (CNS) injury, we predicted that compounds which induce IL-33 are likely to promote remyelination. We found anacardic acid as a candidate molecule to serve as a therapeutic agent to promote remyelination. Addition of anacardic acid to cultured oligodendrocyte precursor cells (OPCs) rapidly increased expression of myelin genes and myelin proteins, suggesting a direct induction of genes involved in myelination by anacardic acid. Also, when added to OPCs, anacardic acid resulted in the induction of IL-33. In vivo, treatment of with anacardic acid in doses which ranged from 0.025 mg/kg to 2.5 mg/kg,improved pathologic scores in experimental allergic encephalitis (EAE) and in the cuprizone model of demyelination/remyelination. Electron microscopic studies performed in mice fed with cuprizone and treated with anacardic acid showed lower g-ratio scores when compared to controls, suggesting increased remyelination of axons. In EAE, improvement in paralytic scores was seen when the drug was given prior to or following the onset of paralytic signs. In EAE and in the cuprizone model, areas of myelin loss, which are likely to remyelinate, was associated with a greater recruitment of IL-33–expressing OPCs in mice which received anacardic acid when compared to controls.

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In vivo imaging methods to assess glaucomatous optic neuropathy

Experimental Eye Research ◽

10.1016/j.exer.2015.06.001 ◽

2015 ◽

Vol 141 ◽

pp. 139-153 ◽

Cited By ~ 10

Author(s):

Brad Fortune

Keyword(s):

Optic Neuropathy ◽

In Vivo Imaging ◽

Glaucomatous Optic Neuropathy ◽

Imaging Methods

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In Vivo Imaging Methods for the Assessment of Angiogenesis: Clinical and Experimental Applications

Vascularization ◽

10.1201/b16777-16 ◽

2014 ◽

pp. 254-281

Keyword(s):

In Vivo Imaging ◽

Imaging Methods

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Skeletal Muscle Mass and Aging: Regional and Whole-Body Measurement Methods

Canadian Journal of Applied Physiology ◽

10.1139/h01-008 ◽

2001 ◽

Vol 26 (1) ◽

pp. 102-122 ◽

Cited By ~ 41

Author(s):

Robert C. Lee ◽

Zimian Wang ◽

Steven B. Heymsfield

Keyword(s):

Skeletal Muscle ◽

Muscle Mass ◽

Skeletal Muscle Mass ◽

Nutritional Assessment ◽

Whole Body ◽

Imaging Methods ◽

Key Words Skeletal Muscle ◽

Body Counting ◽

Magnetic Resonance Imaging Mri

Skeletal muscle is a large compartment that can now be quantified using research and clinically applicable regional and whole-body methods. The most important advances are the two imaging methods, computed tomography (CT) and magnetic resonance imaging (MRI). Both CT and MRI can serve as regional and whole-body reference methods when evaluating other approaches for estimating skeletal muscle mass. Imaging methods also afford the opportunity to quantify both anatomic skeletal muscle and the smaller adipose-tissue free skeletal muscle component. Other available methods for estimating skeletal muscle, either regional or at the whole body level, include dual-energy x-ray absorptiometry, in vivo neutron activation analysis-whole body counting, anthropometry, ultrasound, bioimpedance analysis, and urinary metabolite markers. Each method is reviewed in the context of the aging process, cost, availability, practicality, and desired accuracy. New insights should be possible when skeletal muscle mass, measured using these methods, is combined with other descriptors of muscle biochemical and mechanical function. Key words: skeletal muscle mass, aging, nutritional assessment, function

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