scholarly journals Tissue Optimisation Strategies for High Quality Ex Vivo Diffusion Imaging

2021 ◽  
Author(s):  
Rachel L. C. Barrett ◽  
Diana Cash ◽  
Camilla Simmons ◽  
Eugene Kim ◽  
Tobias C. Wood ◽  
...  
Keyword(s):  
Ex Vivo ◽  
Signal To Noise Ratio ◽  
Diffusion Imaging ◽  
B Value ◽  
Tissue Preparation ◽  
Imaging Data ◽  
Fixed Tissue ◽  
Volume Coil ◽  
Snr Efficiency

Ex vivo diffusion imaging can be used to study healthy and pathological tissue microstructure in the rodent brain with microscopic resolution, providing a link between in vivo MRI and ex vivo microscopy techniques. A major challenge for the successful acquisition of ex vivo diffusion imaging data however are changes in the relaxivity and diffusivity of brain tissue following perfusion fixation. In this study we address this question by examining the combined effects of tissue preparation factors that influence image quality, including tissue rehydration time, fixative concentration and contrast agent concentration. We present an optimisation strategy combining these factors to manipulate the T1 and T2 of fixed tissue and maximise signal-to-noise ratio (SNR) efficiency. Applying this strategy in the rat brain resulted in a doubling of SNR and an increase in SNR per unit time by 135% in grey matter and 88% in white matter. This enabled the acquisition of excellent quality high-resolution (78 μm isotropic voxel size) diffusion data in less than 4 days, with a b-value of 4000 s/mm2, 30 diffusion directions and a field of view of 40 x 13 x 18 mm, using a 9.4 Tesla scanner with a standard 39 mm volume coil and a 660 mT/m 114 mm gradient insert. It was also possible to achieve comparable data quality for a standard resolution (150 μm) diffusion dataset in 21/4 hours. In conclusion, the optimisation strategy presented here may be used to improve signal quality, increase spatial resolution and/or allow faster acquisitions in preclinical ex vivo diffusion MRI experiments.

scholarly journals Rationally Designing Simple Rod-Like Amphiphilic NIR-Emissive AIE Probes for Precise In-Vivo Detection of Aβ Fibrils/Plaques at A Super-Early Stage

2021 ◽  
Author(s):  
Yipu Wang ◽  
Dong Mei ◽  
Xinyi Zhang ◽  
Da-Hui Qu ◽  
Ju Mei ◽  
...  
Keyword(s):  
High Performance ◽  
Ex Vivo ◽  
Early Stage ◽  
Signal To Noise Ratio ◽  
High Signal ◽  
In Vivo Detection ◽  
Different Strains ◽  
Aβ Fibrils

With increase of social aging, Alzheimer's disease (AD) has been one of the serious diseases threatening human health. The occurrence of A<i>β </i>fibrils<i> </i>or plaques is recognized as the hallmark of AD.<i> </i>Currently, optical imaging has stood out to be a promising technique for the imaging of A<i>β</i> fibrils/plaques and the diagnosis of AD. However, restricted by their poor blood-brain barrier (BBB) penetrability, short-wavelength excitation and emission, and aggregation-caused quenching (ACQ) effect, the clinically used gold-standard optical probes such as <a>thioflavin</a> T (ThT) and thioflavin S (ThS), are not effective enough in the early diagnosis of AD <i>in vivo</i>. Herein, we put forward an “all-in-one” design principle and demonstrate its feasibility in developing high-performance fluorescent probes which are specific to A<i>β</i> fibrils/plaques and promising for super-early <i>in</i>-<i>vivo</i> diagnosis of AD. As a proof of concept, a simple rod-like amphiphilic NIR fluorescent AIEgen, i.e., AIE-CNPy-AD, is developed by taking the specificity, BBB penetration ability, deep-tissue penetration capacity, high signal-to-noise ratio (SNR) into consideration. AIE-CNPy-AD is constituted by connecting the electron-donating and accepting moieties through single bonds and tagging with a propanesulfonate tail, giving rise to the NIR fluorescence, aggregation-induced emission (AIE) effect, amphiphilicity, and rod-like structure, which in turn result in high binding-affinity and excellent specificity to A<i>β</i> fibrils/plaques, satisfactory ability to penetrate BBB and deep tissues, ultrahigh SNR and sensitivity, and high-fidelity imaging capability. <i>In-vitro, ex-vivo,</i> and <i>in-vivo</i> <a>identifying of A<i>β</i> fibrils/plaques</a> in different strains of mice indicate that AIE-CNPy-AD holds the universality to the detection of A<i>β</i> fibrils/plaques. It is noteworthy that AIE-CNPy-AD is even able to trace the small and sparsely distributed A<i>β</i> fibrils/plaques in very young AD model mice such as 4-month-old APP/PS1 mice which are reported to be the youngest mice to have A<i>β</i> deposits in brains, suggesting its great potential in diagnosis and intervention of AD at a super-early stage.

scholarly journals In Vivo Tracking of Murine Adipose Tissue-Derived Multipotent Adult Stem Cells and Ex Vivo Cross-Validation

2013 ◽  
Vol 2013 ◽  
pp. 1-13 ◽  
Author(s):  
Chiara Garrovo ◽  
Natascha Bergamin ◽  
Dave Bates ◽  
Daniela Cesselli ◽  
Antonio Paolo Beltrami ◽  
...  
Keyword(s):  
Stem Cells ◽  
Adipose Tissue ◽  
Optical Imaging ◽  
Adult Stem Cells ◽  
Near Infrared ◽  
Cross Validation ◽  
Ex Vivo ◽  
Imaging Data ◽  
Imaging Results

Stem cells are characterized by the ability to renew themselves and to differentiate into specialized cell types, while stem cell therapy is believed to treat a number of different human diseases through either cell regeneration or paracrine effects. Herein, an in vivo and ex vivo near infrared time domain (NIR TD) optical imaging study was undertaken to evaluate the migratory ability of murine adipose tissue-derived multipotent adult stem cells [mAT-MASC] after intramuscular injection in mice. In vivo NIR TD optical imaging data analysis showed a migration of DiD-labelled mAT-MASC in the leg opposite the injection site, which was confirmed by a fibered confocal microendoscopy system. Ex vivo NIR TD optical imaging results showed a systemic distribution of labelled cells. Considering a potential microenvironmental contamination, a cross-validation study by multimodality approaches was followed: mAT-MASC were isolated from male mice expressing constitutively eGFP, which was detectable using techniques of immunofluorescence and qPCR. Y-chromosome positive cells, injected into wild-type female recipients, were detected by FISH. Cross-validation confirmed the data obtained by in vivo/ex vivo TD optical imaging analysis. In summary, our data demonstrates the usefulness of NIR TD optical imaging in tracking delivered cells, giving insights into the migratory properties of the injected cells.

Diffusion restriction in the human spinal cord characterized in vivo with high b-value STEAM diffusion imaging

NeuroImage ◽  
2013 ◽  
Vol 82 ◽  
pp. 416-425 ◽  
Author(s):  
Novena A. Rangwala ◽  
David B. Hackney ◽  
Weiying Dai ◽  
David C. Alsop
Keyword(s):  
Spinal Cord ◽  
Diffusion Imaging ◽  
B Value ◽  
Diffusion Restriction ◽  
Human Spinal Cord ◽  
High B Value

scholarly journals Polo-like kinase 2 inhibition reduces serine-129 phosphorylation of physiological nuclear alpha-synuclein but not of the aggregated alpha-synuclein

2021 ◽  
Author(s):  
Sara Elfarrash ◽  
Nanna Møller Jensen ◽  
Nelson Ferreira ◽  
Sissel Ida Schmidt ◽  
Emil Gregersen ◽  
...  
Keyword(s):  
Ex Vivo ◽  
Signal To Noise Ratio ◽  
Lewy Bodies ◽  
Alpha Synuclein ◽  
Sample Collection ◽  
Lewy Pathology ◽  
Organotypic Brain Slice ◽  
Short Time

Accumulation of aggregated alpha-synuclein (α-syn) is believed to play a pivotal role in the pathophysiology of Parkinson’s disease (PD) and other synucleinopathies. α-Syn is a key constituent protein of  Lewy pathology, and α-syn phosphorylated at serine-129 (pS129) constitutes more than 90% of α-syn in Lewy bodies and hence, it is used extensively as a pathological marker for the aggregated form of α-syn. However, the exact role of pS129 remains controversial as well as the kinase(s) responsible for the phosphorylation. In this study, we investigated the effect of Polo-like kinase 2 (PLK2) inhibition on formation of pS129 using ex-vivo organotypic brain slice model of synucleinopathy. Our data demonstrated that PLK2 inhibition has no effect on α-syn aggregation, pS129 or inter-neuronal spreading of the aggregated α-syn seen in the organotypic slices. Instead, PLK2 inhibition reduced the soluble nuclear pS129 level confined in the nuclei. The same finding was replicated in an in-vivo mouse models of templated α-syn aggregation and human dopaminergic neurons, suggesting that PLK2 is more likely to be involved in S129 phosphorylation of soluble non-pathology related fraction of α-syn. We also demonstrated that reduction of nuclear pS129 but not the aggregates specific pS129 following PLK2 inhibition for a short time before sample collection improves the signal to noise ratio when quantifying pS129 aggregate pathology.

scholarly journals In Vivo and Ex Vivo Microscopy: Moving Toward the Integration of Optical Imaging Technologies Into Pathology Practice

2018 ◽  
Vol 143 (3) ◽  
pp. 288-298 ◽  
Author(s):  
Wendy A. Wells ◽  
Michael Thrall ◽  
Anastasia Sorokina ◽  
Jeffrey Fine ◽  
Savitri Krishnamurthy ◽  
...  
Keyword(s):  
Optical Imaging ◽  
Ex Vivo ◽  
Imaging Techniques ◽  
Clinical Care ◽  
Imaging Data ◽  
Imaging Technologies ◽  
Optical Images ◽  
Tissue Removal ◽  
Excised Tissue

The traditional surgical pathology assessment requires tissue to be removed from the patient, then processed, sectioned, stained, and interpreted by a pathologist using a light microscope. Today, an array of alternate optical imaging technologies allow tissue to be viewed at high resolution, in real time, without the need for processing, fixation, freezing, or staining. Optical imaging can be done in living patients without tissue removal, termed in vivo microscopy, or also in freshly excised tissue, termed ex vivo microscopy. Both in vivo and ex vivo microscopy have tremendous potential for clinical impact in a wide variety of applications. However, in order for these technologies to enter mainstream clinical care, an expert will be required to assess and interpret the imaging data. The optical images generated from these imaging techniques are often similar to the light microscopic images that pathologists already have expertise in interpreting. Other clinical specialists do not have this same expertise in microscopy, therefore, pathologists are a logical choice to step into the developing role of microscopic imaging expert. Here, we review the emerging technologies of in vivo and ex vivo microscopy in terms of the technical aspects and potential clinical applications. We also discuss why pathologists are essential to the successful clinical adoption of such technologies and the educational resources available to help them step into this emerging role.

scholarly journals ISOLATION OF CUCURBITACIN-B FROM CUCUMIS CALLOSUS AND ITS HYPOGLYCEMIC EFFECT IN ISOLATED RAT ENTEROCYTES

2018 ◽  
Vol 10 (5) ◽  
pp. 123
Author(s):  
Siva Prasad Panda ◽  
Asit Kumar Sarangi ◽  
Uttam Prasad Panigrahy
Keyword(s):  
Ex Vivo ◽  
Hypoglycemic Effect ◽  
Albino Rats ◽  
Tissue Preparation ◽  
Potent Inducer ◽  
Standard Drug ◽  
Reference Drug ◽  
Cucurbitacin B ◽  
Rat Enterocytes

Objective: The pericarp of fruits of Cucumis callous (Rottl.) Cogn. (Cucurbitaceae) is traditionally used for curing diabetes, epilepsy, and diarrhea. It has an active compound include Cucurbitacin-B (CuB), which acts as a potent inducer of CYP450 of rat enterocytes. This study was conducted with the aim of elaborating and reconciling our previous finding on the glucose-lowering effect of Cucumis callosus (Rottl.) Cogn. fruits.Methods: In vivo hypoglycemic potential for methanolic pericarp extracts from C callosus (MPCC, 350 mg/kg b.w. p. o), methanolic seed extract of C callosus (MSCC, 250 mg/kg b.w. p. o) and CuB (80 µg/kg b.w. p. o) were studied in streptozotocin (STZ, 55 mg/kg b.w. i. p) induced diabetic rats. Metformin (25 mg/kg b.w. p. o) served as reference drug. Ex vivo model of intestinal tissue preparation of Swiss albino rats named Single Pass Intestinal Perfusion (SPIP) technique was performed for ex vivo hypoglycemic study. The glucose levels in the serosal fluid were determined by commercially available glucose oxidase kit and compared with the standard drug metformin (0.1 mg/kg).Results: In vivo results showed that administration of MPCC (350 mg/kg b.w. p. o) and Cucurbitacin-B (80 µg/kg b.w. p. o) produced the hypoglycemic effect. The MPCC (1.4 mg/kg) and CuB (0.4 µg/kg) produced hypoglycemic effect in ex vivo technique. These effects are due to induction of 0.53 mµmoles of CYP450 proteins with maximum absorption at 454 mµ in rat enterocytes.Conclusion: The present investigation gave evidence that bitter pericarp of C callosus fruit has a hypoglycemic effect due to the presence of Cucurbitacin B as phytoconstituent but seeds did not have such effects.

scholarly journals Navigator-Free Submillimeter Diffusion Imaging Using Multishot-Encoded Simultaneous Multi-Slice (MUSIUM)

2020 ◽  
Author(s):  
Wei-Tang Chang ◽  
Khoi Huynh ◽  
Pew-Thian Yap ◽  
Weili Lin
Keyword(s):  
Signal To Noise Ratio ◽  
Diffusion Imaging ◽  
Brain Structures ◽  
Peak Amplitude ◽  
Acquisition Time ◽  
Rf Power ◽  
Isotropic Resolution ◽  
Low Snr ◽  
Scan Time

Abstract The ability to achieve submillimter isotropic resolution diffusion MR imaging (dMRI) is critically important to study fine-scale brain structures. One of the major challenges in submillimeter dMRI is the inherently low signal-to-noise ratio (SNR). While approaches capable of mitigating the low SNR have been proposed, namely simultaneous multi-slab (SMSlab) and generalized slice dithered enhanced resolution with simultaneous multislice (gSlider-SMS), limitations are associated with these approaches. The SMSlab sequences suffer from the slab boundary artifacts and require additional navigators for phase estimation. On the other hand, gSlider sequences require relatively high RF power and peak amplitude, which increase the SAR and complicate the RF excitation. In this work, we developed a navigator-free multishot-encoded simultaneous multi-slice (MUSIUM) imaging approach, achieving enhanced SNR, low RF power and peak amplitude, and being free from slab boundary artifacts. The dMRI with ultrahigh resolution (0.86 mm isotropic), whole brain coverage and ~12.5 minute acquisition time were achieved, revealing detailed structures at cortical and white matter areas. The simulated and in vivo results also demonstrated that the MUSIUM imaging was minimally affected by the motion. Taken together, the MUSIUM imaging is a promising approach to achieve submillimeter diffusion imaging on 3T scanner within clinically feasible scan time.

scholarly journals An event-based paradigm for analyzing fluorescent astrocyte activity uncovers novel single-cell and population-level physiology

2018 ◽  
Author(s):  
Yizhi Wang ◽  
Nicole V. DelRosso ◽  
Trisha Vaidyanathan ◽  
Michael Reitman ◽  
Michelle K. Cahill ◽  
...  
Keyword(s):  
Ex Vivo ◽  
Single Cells ◽  
Region Of Interest ◽  
Population Level ◽  
Analytical Framework ◽  
Model Organisms ◽  
Imaging Data ◽  
Fluorescent Indicators ◽  
Event Based

AbstractRecent work examining astrocytic physiology centers on fluorescence imaging approaches, due to development of sensitive fluorescent indicators and observation of spatiotemporally complex calcium and glutamate activity. However, the field remains hindered in fully characterizing these dynamics, both within single cells and at the population-level, because of the insufficiency of current region-of-interest-based approaches to describe activity that is often spatially unfixed, size-varying, and propagative. Here, we present a paradigm-shifting analytical framework that releases astrocyte biologists from ROI-based tools. Astrocyte Quantitative Analysis (AQuA) software enables users to take an event-based approach to accurately capture and quantify the irregular activity observed in astrocyte imaging datasets. We apply AQuA to a range of ex vivo and in vivo imaging data, and uncover previously undescribed physiological phenomena in each. Since AQuA is data-driven and based on machine learning principles, it can be applied across model organisms, fluorescent indicators, experimental modes, and imaging resolutions and speeds, enabling researchers to elucidate fundamental astrocyte physiology.

scholarly journals In vivo pulse-labeling of isochronic cohorts of cells in the central nervous system using FlashTag

2018 ◽  
Author(s):  
Subashika Govindan ◽  
Polina Oberst ◽  
Denis Jabaudon
Keyword(s):  
Central Nervous System ◽  
Nervous System ◽  
Cell Sorting ◽  
Ex Vivo ◽  
Live Cells ◽  
Fixed Tissue ◽  
System A ◽  
M Phase ◽  
The Central Nervous System

AbstractThis protocol describes a fluorescence birthdating technique to label, track and isolate isochronic cohorts of newborn cells in the central nervous system in vivo. Injection of carboxyfluorescein esters into the cerebral ventricle allows pulse-labeling of M-phase progenitors in touch with the ventricle and their progeny across the central nervous system, a procedure we termed FlashTag. Labeled cells can be imaged ex vivo or in fixed tissue, targeted for electrophysiological experiments, or isolated using Fluorescence-Activated Cell Sorting (FACS) for cell culture or (single-cell) RNA-sequencing. The dye is retained for several weeks, allowing labeled cells to be identified postnatally. This protocol describes the labeling procedure using in utero injection, the isolation of live cells using FACS, as well as the processing of labeled tissue using immunohistochemistry.

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