scholarly journals Super-Resolution Imaging with Ultrasound for Visualization of the Renal Microvasculature in Rats Before and After Renal Ischemia: A Pilot Study

Diagnostics ◽  
2020 ◽  
Vol 10 (11) ◽  
pp. 862
Author(s):  
Sofie Bech Andersen ◽  
Iman Taghavi ◽  
Carlos Armando Villagómez Hoyos ◽  
Stinne Byrholdt Søgaard ◽  
Fredrik Gran ◽  
...  
Keyword(s):  
Ultrasound Imaging ◽  
Super Resolution ◽  
Microvascular Blood Flow ◽  
Sprague Dawley ◽  
Renal Vasculature ◽  
Vasa Recta ◽  
Before And After ◽  
Renal Microvasculature ◽  
High Level

In vivo monitoring of the microvasculature is relevant since diseases such as diabetes, ischemia, or cancer cause microvascular impairment. Super-resolution ultrasound imaging allows in vivo examination of the microvasculature by detecting and tracking sparsely distributed intravascular microbubbles over a minute-long period. The ability to create detailed images of the renal vasculature of Sprague-Dawley rats using a modified clinical ultrasound platform was investigated in this study. Additionally, we hypothesized that early ischemic damage to the renal microcirculation could be visualized. After a baseline scan of the exposed kidney, 10 rats underwent clamping of the renal vein (n = 5) or artery (n = 5) for 45 min. The kidneys were rescanned at the onset of clamp release and after 60 min of reperfusion. Using a processing pipeline for tissue motion compensation and microbubble tracking, super-resolution images with a very high level of detail were constructed. Image filtration allowed further characterization of the vasculature by isolating specific vessels such as the ascending vasa recta with a 15–20 μm diameter. Using the super-resolution images alone, it was only possible for six assessors to consistently distinguish the healthy renal microvasculature from the microvasculature at the onset of vein clamp release. Future studies will aim at attaining quantitative estimations of alterations in the renal microvascular blood flow using super-resolution ultrasound imaging.

scholarly journals Evaluation of 2D super-resolution ultrasound imaging of the rat renal vasculature using ex vivo micro-computed tomography

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Sofie Bech Andersen ◽  
Iman Taghavi ◽  
Hans Martin Kjer ◽  
Stinne Byrholdt Søgaard ◽  
Carsten Gundlach ◽  
...  
Keyword(s):  
Ultrasound Imaging ◽  
Ex Vivo ◽  
Imaging Techniques ◽  
Rat Kidney ◽  
Vascular Anatomy ◽  
Super Resolution ◽  
Sprague Dawley ◽  
Micro Computed Tomography ◽  
Renal Vasculature

AbstractSuper-resolution ultrasound imaging (SRUS) enables in vivo microvascular imaging of deeper-lying tissues and organs, such as the kidneys or liver. The technique allows new insights into microvascular anatomy and physiology and the development of disease-related microvascular abnormalities. However, the microvascular anatomy is intricate and challenging to depict with the currently available imaging techniques, and validation of the microvascular structures of deeper-lying organs obtained with SRUS remains difficult. Our study aimed to directly compare the vascular anatomy in two in vivo 2D SRUS images of a Sprague–Dawley rat kidney with ex vivo μCT of the same kidney. Co-registering the SRUS images to the μCT volume revealed visually very similar vascular features of vessels ranging from ~ 100 to 1300 μm in diameter and illustrated a high level of vessel branching complexity captured in the 2D SRUS images. Additionally, it was shown that it is difficult to use μCT data of a whole rat kidney specimen to validate the super-resolution capability of our ultrasound scans, i.e., validating the actual microvasculature of the rat kidney. Lastly, by comparing the two imaging modalities, fundamental challenges for 2D SRUS were demonstrated, including the complexity of projecting a 3D vessel network into 2D. These challenges should be considered when interpreting clinical or preclinical SRUS data in future studies.

scholarly journals Super-resolution Ultrasound Imaging of the Renal Microvasculature in Rats with Metabolic syndrome

2020 ◽  
Author(s):  
Stinne Byrholdt Sogaard ◽  
Sofie Bech Andersen ◽  
Iman Taghavi ◽  
Carlos Armando Villagomez Hoyos ◽  
Kristoffer Lindskov Hansen ◽  
...  
Keyword(s):  
Metabolic Syndrome ◽  
Ultrasound Imaging ◽  
Super Resolution ◽  
Renal Microvasculature

Disruption of Balanced Cortical Excitation and Inhibition by Acoustic Trauma

2008 ◽  
Vol 100 (2) ◽  
pp. 646-656 ◽  
Author(s):  
Ben Scholl ◽  
Michael Wehr
Keyword(s):  
Receptive Field ◽  
Cortical Neurons ◽  
Receptive Fields ◽  
Acoustic Trauma ◽  
Tone Frequency ◽  
Synaptic Excitation ◽  
Before And After ◽  
High Level ◽  
Whole Cell Recordings

Sensory deafferentation results in rapid shifts in the receptive fields of cortical neurons, but the synaptic mechanisms underlying these changes remain unknown. The rapidity of these shifts has led to the suggestion that subthreshold inputs may be unmasked by a selective loss of inhibition. To study this, we used in vivo whole cell recordings to directly measure tone-evoked excitatory and inhibitory synaptic inputs in auditory cortical neurons before and after acoustic trauma. Here we report that acute acoustic trauma disrupted the balance of excitation and inhibition by selectively increasing and reducing the strength of inhibition at different positions within the receptive field. Inhibition was abolished for frequencies far below the trauma-tone frequency but was markedly enhanced near the edges of the region of elevated peripheral threshold. These changes occurred for relatively high-level tones. These changes in inhibition led to an expansion of receptive fields but not by a simple unmasking process. Rather, membrane potential responses were delayed and prolonged throughout the receptive field by distinct interactions between synaptic excitation and inhibition. Far below the trauma-tone frequency, decreased inhibition combined with prolonged excitation led to increased responses. Near the edges of the region of elevated peripheral threshold, increased inhibition served to delay rather than abolish responses, which were driven by prolonged excitation. These results show that the rapid receptive field shifts caused by acoustic trauma are caused by distinct mechanisms at different positions within the receptive field, which depend on differential disruption of excitation and inhibition.

scholarly journals Chronic 2P-STED imaging reveals high turnover of dendritic spines in the hippocampus in vivo

eLife ◽  
2018 ◽  
Vol 7 ◽  
Author(s):  
Thomas Pfeiffer ◽  
Stefanie Poll ◽  
Stephane Bancelin ◽  
Julie Angibaud ◽  
VVG Krishna Inavalli ◽  
...  
Keyword(s):  
Dendritic Spines ◽  
Super Resolution ◽  
Mammalian Brain ◽  
Spine Density ◽  
Behavioral Experiments ◽  
High Turnover ◽  
Synaptic Circuits ◽  
Working Distance ◽  
High Level

Rewiring neural circuits by the formation and elimination of synapses is thought to be a key cellular mechanism of learning and memory in the mammalian brain. Dendritic spines are the postsynaptic structural component of excitatory synapses, and their experience-dependent plasticity has been extensively studied in mouse superficial cortex using two-photon microscopy in vivo. By contrast, very little is known about spine plasticity in the hippocampus, which is the archetypical memory center of the brain, mostly because it is difficult to visualize dendritic spines in this deeply embedded structure with sufficient spatial resolution. We developed chronic 2P-STED microscopy in mouse hippocampus, using a ‘hippocampal window’ based on resection of cortical tissue and a long working distance objective for optical access. We observed a two-fold higher spine density than previous studies and measured a spine turnover of ~40% within 4 days, which depended on spine size. We thus provide direct evidence for a high level of structural rewiring of synaptic circuits and new insights into the structure-dynamics relationship of hippocampal spines. Having established chronic super-resolution microscopy in the hippocampus in vivo, our study enables longitudinal and correlative analyses of nanoscale neuroanatomical structures with genetic, molecular and behavioral experiments.

Super-resolution ultrasound imaging for in vivo microvasculature assessment in acute kidney injury mouse model

2019 ◽  
Vol 145 (3) ◽  
pp. 1859-1859
Author(s):  
Qiyang Chen ◽  
Brittney M. Rush ◽  
Jaesok Yu ◽  
Roderick Tan ◽  
Kang Kim
Keyword(s):  
Acute Kidney Injury ◽  
Mouse Model ◽  
Ultrasound Imaging ◽  
Kidney Injury ◽  
Super Resolution

scholarly journals ADP-ribosyl cyclase and ryanodine receptors mediate endothelin ETA and ETB receptor-induced renal vasoconstriction in vivo

2008 ◽  
Vol 295 (2) ◽  
pp. F360-F368 ◽  
Author(s):  
Tiffany L. Thai ◽  
William J. Arendshorst
Keyword(s):  
Ryanodine Receptors ◽  
Ruthenium Red ◽  
Sprague Dawley ◽  
Renal Vasculature ◽  
Receptor Stimulation ◽  
Renal Vasoconstriction ◽  
Adp Ribosyl Cyclase ◽  
Etb Receptor ◽  
Rats And Mice

ADP-ribosyl cyclase (ADPR cyclase) and ryanodine receptors (RyR) participate in calcium transduction in isolated afferent arterioles. We hypothesized that this signaling pathway is activated by ETA and ETB receptors in the renal vasculature to mediate vasoconstriction in vivo. To test this, we measured acute renal blood flow (RBF) responses to ET-1 in anesthetized rats and mice in the presence and absence of functional ADPR cyclase and/or RyR. Inhibitors of ADPR cyclase (nicotinamide) or RyR (ruthenium red) reduced RBF responses to ET-1 by 44% ( P < 0.04 for both) in Sprague-Dawley rats. Mice lacking the predominant form of ADPR cyclase (CD38−/−) had RBF responses to ET-1 that were 47% weaker than those seen in wild-type mice ( P = 0.01). Selective ETA receptor stimulation (ET-1+BQ788) produced decreases in RBF that were attenuated by 43 and 56% by nicotinamide or ruthenium red, respectively ( P < 0.02 for both). ADPR cyclase or RyR inhibition also reduced vasoconstrictor effects of the ETB receptor agonist sarafotoxin 6c (S6c; 77 and 54%, respectively, P < 0.02 for both). ETB receptor stimulation by ET-1 + the ETA receptor antagonist BQ123 elicited responses that were attenuated by 59 and 60% by nicotinamide and ruthenium red, respectively ( P < 0.01 for both). Nicotinamide attenuated RBF responses to S6c by 54% during inhibition of nitric oxide synthesis ( P = 0.001). We conclude that in the renal microcirculation in vivo 1) ET-1-induced vasoconstriction is mediated by ADPR cyclase and RyR; 2) both ETA and ETB receptors activate this pathway; and 3) ADPR cyclase participates in ETB receptor signaling independently of NO.

scholarly journals Super-Resolution Ultrasound Imaging in Vivo with Transient Laser-Activated Nanodroplets

Nano Letters ◽  
2016 ◽  
Vol 16 (4) ◽  
pp. 2556-2559 ◽  
Author(s):  
Geoffrey P. Luke ◽  
Alexander S. Hannah ◽  
Stanislav Y. Emelianov
Keyword(s):  
Ultrasound Imaging ◽  
Super Resolution

Enhanced expression of EGF receptor in a model of salt-sensitive hypertension

2005 ◽  
Vol 289 (2) ◽  
pp. F314-F321 ◽  
Author(s):  
Wei-Zhong Ying ◽  
Paul W. Sanders
Keyword(s):  
Egf Receptor ◽  
Primary Cultures ◽  
Growth Factor Receptor ◽  
Sprague Dawley ◽  
Renal Vasculature ◽  
Downstream Signaling ◽  
Egfr Expression ◽  
Enhanced Expression

Chronic kidney disease in the Dahl/Rapp salt-sensitive (S) rat is related to an arteriolopathic process that occurs following the onset of hypertension and involves vascular smooth muscle cell (VSMC) hyperplasia and luminal constriction. Because previous studies have shown that activation of the epidermal growth factor receptor (EGFR) produces a mitogenic stimulus in VSMC and the EGFR participates integrally in the vasoconstrictor responses of renal arterioles, the present study analyzed the expression of EGFR in these animals. Compared with Sprague-Dawley (SD) rats, renal cortical expression of EGFR was increased in both prehypertensive and hypertensive S rats. Immunohistochemistry using a polyclonal antibody to EGFR demonstrated that EGFR expression was prominent in the renal vasculature, particularly in the media of afferent and efferent arterioles and the aorta of S rats. When examined, primary cultures of VSMC from S rats showed increased expression of EGFR, compared with VSMC from SD and Dahl/Rapp salt-resistant rats. Following addition of EGF, autophosphorylation of the EGFR was enhanced in cells from S rats, as was the downstream signaling events that included activation of p42/44 MAPK and Akt pathways. Thus in vivo and in vitro studies demonstrated augmented expression and functional activity of the EGFR in S rats.

Cocaine increases stimulation-evoked serotonin efflux in the nucleus accumbens

2022 ◽  
Author(s):  
Jason Yuen ◽  
Abhinav Goyal ◽  
Aaron E Rusheen ◽  
Abbas Z Kouzani ◽  
Michael Berk ◽  
...  
Keyword(s):  
Nucleus Accumbens ◽  
Illicit Drugs ◽  
Serotonin Release ◽  
Sprague Dawley ◽  
Nucleus Accumbens Core ◽  
Fast Scan Cyclic Voltammetry ◽  
Carbon Fiber Microelectrode ◽  
Before And After

Cocaine is one of the most common illicit drugs globally, but the role of serotonin in its mechanism of action is insufficiently characterised. Consequently, we investigated the acute effects of the psychomotor stimulant cocaine on electrical stimulation-evoked serotonin (phasic) release in the nucleus accumbens core (NAcc) of urethane-anesthetized (1.5 g/kg i.p.) male Sprague-Dawley rats using N-shaped fast-scan cyclic voltammetry (N-FSCV). A single carbon fiber microelectrode was first implanted in the NAcc. Stimulation was applied to the medial forebrain bundle using 60 Hz, 2 ms, 0.2 mA, 2 s biphasic pulses before and after cocaine (2 mg/kg i.v.) was administered. Stimulation-evoked serotonin release significantly increased 5 minutes after cocaine injection compared to baseline (153±21 nM vs 257±12 nM; p = 0.0042; n = 5) but was unaffected by saline injection (1 ml/kg i.v.; n = 5). N-FSCV's selective measurement of serotonin release in vivo was confirmed pharmacologically via administration of the selective serotonin reuptake inhibitor escitalopram (10 mg/kg i.p.) which effectively increased the signal in a separate group of rats (n = 5). Selectivity to serotonin was further confirmed in vitro in which dopamine was minimally detected by N-FSCV with a serotonin to dopamine response ratio of 1:0.04 (200 nM of serotonin:1 mM dopamine ratio; p = 0.0048; n = 5 electrodes). This study demonstrates a noteworthy influence of cocaine on serotonin dynamics, and confirms that N-FSCV can effectively and selectively measure phasic serotonin release in the NAcc.

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