scholarly journals Real-Time Amperometric Recording of Extracellular H2O2 in the Brain of Immunocompromised Mice: An In Vitro, Ex Vivo and In Vivo Characterisation Study

Sensors ◽  
2017 ◽  
Vol 17 (7) ◽  
pp. 1596 ◽  
Author(s):  
◽  
Keyword(s):  
Real Time ◽  
Ex Vivo ◽  
Immunocompromised Mice ◽  
The Brain

Ex Vivo Brain Preparation to Analyze Vocal Pathways of Xenopus Frogs

2021 ◽  
Vol 2021 (9) ◽  
pp. pdb.prot106872
Author(s):  
Ayako Yamaguchi
Keyword(s):  
Neural Activity ◽  
Ex Vivo ◽  
Neural Circuitry ◽  
Neural Basis ◽  
Vocal Production ◽  
Basic Principles ◽  
Electrophysiological Recordings ◽  
The Brain

Understanding the neural basis of behavior is a challenging task for technical reasons. Most methods of recording neural activity require animals to be immobilized, but neural activity associated with most behavior cannot be recorded from an anesthetized, immobilized animal. Using amphibians, however, there has been some success in developing in vitro brain preparations that can be used for electrophysiological and anatomical studies. Here, we describe an ex vivo frog brain preparation from which fictive vocalizations (the neural activity that would have produced vocalizations had the brain been attached to the muscle) can be elicited repeatedly. When serotonin is applied to the isolated brains of male and female African clawed frogs, Xenopus laevis, laryngeal nerve activity that is a facsimile of those that underlie sex-specific vocalizations in vivo can be readily recorded. Recently, this preparation was successfully used in other species within the genus including Xenopus tropicalis and Xenopus victorianus. This preparation allows a variety of techniques to be applied including extracellular and intracellular electrophysiological recordings and calcium imaging during vocal production, surgical and pharmacological manipulation of neurons to evaluate their impact on motor output, and tract tracing of the neural circuitry. Thus, the preparation is a powerful tool with which to understand the basic principles that govern the production of coherent and robust motor programs in vertebrates.

scholarly journals Live View of Gonadotropin-Releasing Hormone Containing Neuron Migration

Endocrinology ◽  
2005 ◽  
Vol 146 (1) ◽  
pp. 463-468 ◽  
Author(s):  
Elizabeth P. Bless ◽  
Heather J. Walker ◽  
Kwok W. Yu ◽  
J. Gabriel Knoll ◽  
Suzanne M. Moenter ◽  
...  
Keyword(s):  
Real Time ◽  
Direct Evidence ◽  
Gonadotropin Releasing Hormone ◽  
Releasing Hormone ◽  
Reproductive Axis ◽  
Gnrh Neurons ◽  
Migratory Route ◽  
The Brain

Neurons that synthesize GnRH control the reproductive axis and migrate over long distances and through different environments during development. Prior studies provided strong clues for the types of molecules encountered and movements expected along the migratory route. However, our studies provide the first real-time views of the behavior of GnRH neurons in the context of an in vitro preparation that maintains conditions comparable to those in vivo. The live views provide direct evidence of the changing behavior of GnRH neurons in their different environments, showing that GnRH neurons move with greater frequency and with more changes in direction after they enter the brain. Perturbations of guiding fibers distal to moving GnRH neurons in the nasal compartment influenced movement without detectable changes in the fibers in the immediate vicinity of moving GnRH neurons. This suggests that the use of fibers by GnRH neurons for guidance may entail selective signaling in addition to mechanical guidance. These studies establish a model to evaluate the influences of specific molecules that are important for their migration.

scholarly journals Real-Time Wireless Platform for In Vivo Monitoring of Bone Regeneration

Sensors ◽  
2020 ◽  
Vol 20 (16) ◽  
pp. 4591 ◽  
Author(s):  
Pablo Blázquez-Carmona ◽  
Manuel Sanchez-Raya ◽  
Juan Mora-Macías ◽  
Juan Antonio Gómez-Galán ◽  
Jaime Domínguez ◽  
...  
Keyword(s):  
Bone Regeneration ◽  
Real Time ◽  
Ex Vivo ◽  
Low Cost ◽  
Bone Lengthening ◽  
Bone Callus ◽  
Reliable Solution ◽  
Regeneration Processes

For the monitoring of bone regeneration processes, the instrumentation of the fixation is an increasingly common technique to indirectly measure the evolution of bone formation instead of ex vivo measurements or traditional in vivo techniques, such as X-ray or visual review. A versatile instrumented external fixator capable of adapting to multiple bone regeneration processes was designed, as well as a wireless acquisition system for the data collection. The design and implementation of the overall architecture of such a system is described in this work, including the hardware, firmware, and mechanical components. The measurements are conditioned and subsequently sent to a PC via wireless communication to be in vivo displayed and analyzed using a developed real-time monitoring application. Moreover, a model for the in vivo estimation of the bone callus stiffness from collected data was defined. This model was validated in vitro using elastic springs, reporting promising results with respect to previous equipment, with average errors and uncertainties below 6.7% and 14.04%. The devices were also validated in vivo performing a bone lengthening treatment on a sheep metatarsus. The resulting system allowed the in vivo mechanical characterization of the bone callus during experimentation, providing a low-cost, simple, and highly reliable solution.

scholarly journals Latest Trends in Electrochemical Sensors for Neurotransmitters: A Review

Sensors ◽  
2019 ◽  
Vol 19 (9) ◽  
pp. 2037 ◽  
Author(s):  
Tavakolian-Ardakani ◽  
Hosu ◽  
Cristea ◽  
Mazloum-Ardakani ◽  
Marrazza
Keyword(s):  
Electrochemical Sensors ◽  
Ex Vivo ◽  
Analytical Techniques ◽  
Substantial Improvement ◽  
Robust Detection ◽  
Brain Functions ◽  
The Brain ◽  
Made In

Neurotransmitters are endogenous chemical messengers which play an important role in many of the brain functions, abnormal levels being correlated with physical, psychotic and neurodegenerative diseases such as Alzheimer's, Parkinson's, and Huntington's disease. Therefore, their sensitive and robust detection is of great clinical significance. Electrochemical methods have been intensively used in the last decades for neurotransmitter detection, outclassing more complicated analytical techniques such as conventional spectrophotometry, chromatography, fluorescence, flow injection, and capillary electrophoresis. In this manuscript, the most successful and promising electrochemical enzyme-free and enzymatic sensors for neurotransmitter detection are reviewed. Focusing on the activity of worldwide researchers mainly during the last ten years (2010–2019), without pretending to be exhaustive, we present an overview of the progress made in sensing strategies during this time. Particular emphasis is placed on nanostructured-based sensors, which show a substantial improvement of the analytical performances. This review also examines the progress made in biosensors for neurotransmitter measurements in vitro, in vivo and ex vivo.

scholarly journals Modeling Immune Checkpoint Inhibitor Efficacy in Syngeneic Mouse Tumors in an Ex Vivo Immuno-Oncology Dynamic Environment

2020 ◽  
Vol 21 (18) ◽  
pp. 6478
Author(s):  
Daniel T. Doty ◽  
Julia Schueler ◽  
Vienna L. Mott ◽  
Cassie M. Bryan ◽  
Nathan F. Moore ◽  
...  
Keyword(s):  
Real Time ◽  
Mouse Models ◽  
Immune Checkpoint ◽  
Checkpoint Inhibitors ◽  
Ex Vivo ◽  
Confocal Imaging ◽  
Checkpoint Blockade ◽  
Syngeneic Mouse

The immune checkpoint blockade represents a revolution in cancer therapy, with the potential to increase survival for many patients for whom current treatments are not effective. However, response rates to current immune checkpoint inhibitors vary widely between patients and different types of cancer, and the mechanisms underlying these varied responses are poorly understood. Insights into the antitumor activities of checkpoint inhibitors are often obtained using syngeneic mouse models, which provide an in vivo preclinical basis for predicting efficacy in human clinical trials. Efforts to establish in vitro syngeneic mouse equivalents, which could increase throughput and permit real-time evaluation of lymphocyte infiltration and tumor killing, have been hampered by difficulties in recapitulating the tumor microenvironment in laboratory systems. Here, we describe a multiplex in vitro system that overcomes many of the deficiencies seen in current static histocultures, which we applied to the evaluation of checkpoint blockade in tumors derived from syngeneic mouse models. Our system enables both precision-controlled perfusion across biopsied tumor fragments and the introduction of checkpoint-inhibited tumor-infiltrating lymphocytes in a single experiment. Through real-time high-resolution confocal imaging and analytics, we demonstrated excellent correlations between in vivo syngeneic mouse and in vitro tumor biopsy responses to checkpoint inhibitors, suggesting the use of this platform for higher throughput evaluation of checkpoint efficacy as a tool for drug development.

scholarly journals Microelectrode Sensor for Real-Time Measurements of Nitrite in the Living Brain, in the Presence of Ascorbate

Biosensors ◽  
2021 ◽  
Vol 11 (8) ◽  
pp. 277
Author(s):  
Tiago Monteiro ◽  
Cândida Dias ◽  
Cátia F. Lourenço ◽  
Ana Ledo ◽  
Rui M. Barbosa ◽  
...  
Keyword(s):  
Blood Flow ◽  
Real Time ◽  
Brain Research ◽  
Electrochemical Techniques ◽  
Spatial Dynamics ◽  
Fast Scan Cyclic Voltammetry ◽  
Hypoxic Conditions ◽  
The Brain

The impaired blood flow to the brain causes a decrease in the supply of oxygen that can result in cerebral ischemia; if the blood flow is not restored quickly, neuronal injury or death will occur. Under hypoxic conditions, the production of nitric oxide (●NO), via the classical L-arginine–●NO synthase pathway, is reduced, which can compromise ●NO-dependent vasodilation. However, the alternative nitrite (NO2−) reduction to ●NO, under neuronal hypoxia and ischemia conditions, has been viewed as an in vivo storage pool of ●NO, complementing its enzymatic synthesis. Brain research is thus demanding suitable tools to probe nitrite’s temporal and spatial dynamics in vivo. In this work, we propose a new method for the real-time measurement of nitrite concentration in the brain extracellular space, using fast-scan cyclic voltammetry (FSCV) and carbon microfiber electrodes as sensing probes. In this way, nitrite was detected anodically and in vitro, in the 5–500 µM range, in the presence of increasing physiological concentrations of ascorbate (100–500 µM). These sensors were then tested for real-time and in vivo recordings in the anesthetized rat hippocampus; using fast electrochemical techniques, local and reproducible transients of nitrite oxidation signals were observed, upon pressure ejection of an exogenous nitrite solution into the brain tissue. Nitrite microsensors are thus a valuable tool for investigating the role of this inorganic anion in brain redox signaling.

scholarly journals Inhibition of Tryptophan Catabolism Is Associated With Neuroprotection During Zika Virus Infection

2021 ◽  
Vol 12 ◽  
Author(s):  
Fernanda Martins Marim ◽  
Danielle Cunha Teixeira ◽  
Celso Martins Queiroz-Junior ◽  
Bruno Vinicius Santos Valiate ◽  
Jose Carlos Alves-Filho ◽  
...  
Keyword(s):  
Zika Virus ◽  
Ex Vivo ◽  
Neuroprotective Effect ◽  
Neuronal Cell Death ◽  
Neuronal Cell ◽  
Kynurenine Pathway ◽  
Pcr Analysis ◽  
The Brain

Zika virus (ZIKV) is an arbovirus belonging to Flaviviridae family that emerged as a global health threat due to its association with microcephaly and other severe neurological complications, including Guillain-Barré Syndrome (GBS) and Congenital Zika Syndrome (CZS). ZIKV disease has been linked to neuroinflammation and neuronal cell death. Neurodegenerative processes may be exacerbated by metabolites produced by the kynurenine pathway, an important pathway for the degradation of tryptophan, which induces neuronal dysfunction due to enhanced excitotoxicity. Here, we exploited the hypothesis that ZIKV-induced neurodegeneration can be rescued by blocking a target enzyme of the kynurenine pathway, the Indoleamine 2,3-dioxygenase (IDO-1). RT-PCR analysis showed increased levels of IDO-1 RNA expression in undifferentiated primary neurons isolated from wild type (WT) mice infected by ZIKV ex vivo, as well as in the brain of ZIKV-infected A129 mice. Pharmacological inhibition of IDO-1 enzyme with 1-methyl-D-tryptophan (1-MT), in both in vitro and in vivo systems, led to significant reduction of ZIKV-induced neuronal death without interfering with the ability of ZIKV to replicate in those cells. Furthermore, in vivo analyses using both genetically modified mice (IDO-/- mice) and A129 mice treated with 1-MT resulted in reduced microgliosis, astrogliosis and Caspase-3 positive cells in the brain of ZIKV-infected A129 mice. Interestingly, increased levels of CCL5 and CXCL-1 chemokines were found in the brain of 1-MT treated-mice. Together, our data indicate that IDO-1 blockade provides a neuroprotective effect against ZIKV-induced neurodegeneration, and this is amenable to inhibition by pharmacological treatment.

scholarly journals Activated neutrophil fluorescent imaging technique for human lungs

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Thomas H. Craven ◽  
Tashfeen Walton ◽  
Ahsan R. Akram ◽  
Emma Scholefield ◽  
Neil McDonald ◽  
...  
Keyword(s):  
Real Time ◽  
Ex Vivo ◽  
Optical Signal ◽  
Neutrophil Activation ◽  
Fluorescent Imaging ◽  
Human Neutrophil Elastase ◽  
Clinical Criteria ◽  
Integral Process

AbstractNeutrophil activation is an integral process to acute inflammation and is associated with adverse clinical sequelae. Identification of neutrophil activation in real time in the lungs of patients may permit biological stratification of patients in otherwise heterogenous cohorts typically defined by clinical criteria. No methods for identifying neutrophil activation in real time in the lungs of patients currently exist. We developed a bespoke molecular imaging probe targeting three characteristic signatures of neutrophil activation: pinocytosis, phagosomal alkalinisation, and human neutrophil elastase (HNE) activity. The probe functioned as designed in vitro and ex vivo. We evaluated optical endomicroscopy imaging of neutrophil activity using the probe in real-time at the bedside of healthy volunteers, patients with bronchiectasis, and critically unwell mechanically ventilated patients. We detected a range of imaging responses in vivo reflecting heterogeneity of condition and severity. We corroborated optical signal was due to probe function and neutrophil activation.

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