contrast-enhanced-ultrasound-imaging-for-assessment-spinal-cord-blood

Contrast Enhanced Ultrasound Imaging for Assessment of Spinal Cord Blood Flow in Experimental Spinal Cord Injury

Reduced spinal cord blood flow (SCBF) (i.e., ischemia) plays a key role in traumatic spinal cord injury (SCI) pathophysiology and is accordingly an ...

Faculté de Médecine Paris Diderot Paris VII, U942

This study investigated the capability of fibered confocal fluorescence microscopy (FCFM) to provide in vivo microvascular observations. FCFM is specifically designed for in vivo in situ observation thanks to a probe composed of a fiber bundle and micro-optics having a diameter as small as 650 microm. In the first part of the study, we compared the main characteristics of FCFM with those of intravital fluorescence microscopy (IFM). A mouse cremaster preparation was used as a common basis to allow for imaging with both modalities. We discussed the feasibility of obtaining quantitative measurements usually provided by IFM in the context of FCFM: morphometry, capillary permeability, functional capillary density, vasoconstriction and dilation effects. In addition, the possibility to visualize fluorescent red blood cells or leukocytes was also evaluated. Phototoxicity issues and limitations of FCFM were also discussed. We showed that FCFM allows observations and measurements usually provided by IFM and that the real-time capability of the system, as well as the flexibility and small diameter of the optical probe enable micro-invasiveness and can extend imaging capabilities for in vivo in situ observations when compared to IFM.

Fibered confocal fluorescence microscopy (Cell-viZio) facilitates extended imaging in the field of microcirculation. A comparison with intravital microscopy.

CADASIL (Cerebral Autosomal Dominant Arteriopathy with Subcortical Infarcts and Leukoencephalopathy) is caused by mutations in the Notch3 receptor expressed at the surface of vascular smooth muscle cells. The functional consequences of the disease at the peripheral microcirculation level are incompletely elucidated. In this study, we aimed to assess, in vivo, the endothelium-dependent and independent vasodilation of the skin microvasculature in CADASIL patients. Twenty-three affected subjects were compared with 23 gender and age-matched controls. The brachial artery endothelium-dependent and endothelium-independent vasodilation were assessed after forearm cuff occlusion and nitroglycerin administration. Skin vasoreactivity to transcutaneous administration of acetylcholine and sodium nitroprussiate, and after postocclusive hyperemia were measured by Laser Doppler flowmetry. The maximum changes in the diameter of the brachial artery after the cuff release or after nitroglycerin administration did not differ between patients and controls. With iontopheresis, only the peak value of the dose response was found decreased in normocholesterolemic patients after nitroprussiate administration. The postocclusive test revealed a large increase of the time to peak value and whole duration of the hyperemic response in CADASIL patients. The results of this study show that the skin vasoreactivity is altered in CADASIL. Particularly, the kinetics of reactive hyperemia after cuff occlusion is dramatically changed with a lengthened and delayed response. This characteristic pattern may be related to the specific ultrastructural modifications related to Notch3 gene mutations involving smooth muscle cells in the microvasculature.

Characteristic features of in vivo skin microvascular reactivity in CADASIL.

Reactive oxygen species (ROS) participate in tissue injury after ischemia-reperfusion. Their implication in leukocyte adherence and increase in permeability at the venular side of the microcirculation have been reported, but very little is known about ROS production in arterioles. The objective of this work was to evaluate, in the arteriole wall in vivo, the temporal changes in superoxide anion production during ischemia and reperfusion and to identify the source of this production. Mouse cremaster muscle was exposed to 1 h of ischemia followed by 30 min of reperfusion, and superoxide anion production was assessed by a fluorescent probe, i.e., intracellular dihydroethidium oxidation. During ischemia, we found a significant increase in dihydroethidium oxidation; however, we observed no additional increase in fluorescence during the subsequent reperfusion. This phenomenon was significantly inhibited by pretreatment with superoxide dismutase. Allopurinol (xanthine oxidase inhibitor) or stigmatellin [Q(o)-site (oriented toward the intermembrane space) inhibitor of mitochondrial complex III] or simultaneous administration of these two inhibitors significantly reduced superoxide production during ischemia to 80%, 88%, and 72%, respectively, of that measured in the untreated ischemia-reperfusion group. By contrast, no significant inhibition was found when NADPH oxidase was inhibited by apocynin or when mitochondrial complex I or complex II was inhibited by rotenone or thenoyltrifluoroacetone. A significant increase in ROS was found with antimycin A [Q(i)-site (located in the inner membrane and facing the mitochondrial matrix) inhibitor of mitochondrial complex III]. We conclude that a significant increase in ROS production occurs during ischemia in the arteriolar wall. This increased production involves both a cytoplasmic source (i.e., xanthine oxidase) and the mitochondrial complex III at the Q(o) site.

In vivo reactive oxygen species production induced by ischemia in muscle arterioles of mice: involvement of xanthine oxidase and mitochondria.

Real-time and spatial quantification using contrast-enhanced ultrasonography of spinal cord perfusion during experimental spinal cord injury.

Cerebrospinal fluid (CSF) pressure elevation may worsen spinal cord ischaemia after spinal cord injury (SCI). We developed a rat model to investigate relationships between CSF pressure and spinal cord blood flow (SCBF).

Rat model of spinal cord injury preserving dura mater integrity and allowing measurements of cerebrospinal fluid pressure and spinal cord blood flow.

In the acute phase of spinal cord injury (SCI), ischemia and parenchymal hemorrhage are believed to worsen the primary lesions induced by mechanical trauma. To minimize ischemia, keeping the mean arterial blood pressure above 85 mmHg for at least 1 week is recommended, and norepinephrine is frequently administered to achieve this goal. However, no experimental study has assessed the effect of norepinephrine on spinal cord blood flow (SCBF) and parenchymal hemorrhage size. We have assessed the effect of norepinephrine on SCBF and parenchymal hemorrhage size within the first hour after experimental SCI.

Effect of norepinephrine on spinal cord blood flow and parenchymal hemorrhage size in acute-phase experimental spinal cord injury.

Sexual dysfunction is significantly more prevalent in women than in men. However, to date, no satisfactory oral treatment is yet available.

Article	Year
Fibered confocal fluorescence microscopy (Cell-viZio) facilitates extended imaging in the field of microcirculation. A comparison with intravital microscopy. Journal of vascular research\| PubMed ID: 15467299	2004
Characteristic features of in vivo skin microvascular reactivity in CADASIL. Journal of cerebral blood flow and metabolism : official journal of the International Society of Cerebral Blood Flow and Metabolism\| PubMed ID: 16788714	2007
In vivo reactive oxygen species production induced by ischemia in muscle arterioles of mice: involvement of xanthine oxidase and mitochondria. American journal of physiology. Heart and circulatory physiology\| PubMed ID: 18055522	2008
Real-time and spatial quantification using contrast-enhanced ultrasonography of spinal cord perfusion during experimental spinal cord injury. Spine\| PubMed ID: 22814303	2012
Rat model of spinal cord injury preserving dura mater integrity and allowing measurements of cerebrospinal fluid pressure and spinal cord blood flow. European spine journal : official publication of the European Spine Society, the European Spinal Deformity Society, and the European Section of the Cervical Spine Research Society\| PubMed ID: 23508337	2013
Effect of norepinephrine on spinal cord blood flow and parenchymal hemorrhage size in acute-phase experimental spinal cord injury. European spine journal : official publication of the European Spine Society, the European Spinal Deformity Society, and the European Section of the Cervical Spine Research Society\| PubMed ID: 24232597	2014
Effects of adenosine monophosphate used in combination with L-arginine on female rabbit corpus cavernosum tissue. Sexual medicine\| PubMed ID: 25356295	2014

Elisabeth Laemmel

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