Vasa vasorum interna in the carotid wall of active forms of Takayasu arteritis evidenced by ultrasound localization microscopy.

Introduction: Takayasu arteritis (TA) is associated with microvascularization of the wall of large arteries and is related to inflammation. Ultrasound localization microscopy (ULM), combining ultrafast ultrasound imaging with microbubble (MB) injection, can track the path of MBs within the arterial wall and thus provide imaging of the vasa vasorum. From the analysis of MB tracks in the common carotid arteries of patients with active TA, we report the presence of microvessels in connection with the carotid lumen (i.e., vasa vasorum interna [VVI]). Methods: ULM maps were obtained on five patients with active disease in the observational single-center series of the TAK-UF study. MB tracks connected to the carotid lumen were automatically identified, allowing the reconstruction of VVI. Results: MB tracking allows us to observe a microvascular network on the inner part of the wall, with some vessels in communication with the carotid lumen. This type of vessel was identified in all patients with active TA (n = 5) with a median of 2.2 [1.1-3.0] vessels per acquisition (2D longitudinal view of 3 cm of the common carotid artery). The blood flow within these vessels is mainly centrifugal; that is, toward the adventitia (88% [54-100] of MB tracks with flow directed to the outer part of the wall). Conclusion: VVI are present in humans in the case of active TA and emphasize the involvement of the intima in the pathological process. ClinicalTrials.gov Identifier: NCT03956394.

Fluoroquinolone Use Preceding Visceral Artery Dissection: A Case Series.

Fluoroquinolones (FQ), commonly prescribed antibiotics, may trigger aortic and carotid dissections. We report three successive cases of visceral artery dissection: one patient with celiac trunk dissection and two with dissection of the superior mesenteric artery. These events occurred up to 4 months after 7 to 14 days of FQ treatment (2 cases of ofloxacin, 1 of norfloxacin). There was no other apparent cause of dissection. These dissections were isolated, apart from a minimal aortic dissection separate from the visceral arterial dissection in one case. A case series cannot certify the relationship between dissection and FQ, but it can be hypothesized. The association between fluoroquinolone use and higher occurrence of aneurysm and dissection remains discussed in aortic syndrome. The potential link between FQ and visceral artery dissection is even less described but should be reported in the absence of previous cases in the literature. The pathophysiological theory is the induction of overexpression of some matrix metalloproteinases and a decrease of their inhibitors, provoking a dysregulation in collagen synthesis and degradation of the extracellular matrix.

Is carotid web an arterial wall dysplasia? A histological series.

INTRODUCTION: Described for 60 years under various names, the carotid web is a suspected cause of cryptogenic stroke, especially in young patients. The web creates an intraluminal protrusion that may contribute to turbulent flow and thrombus embolization into cerebral arteries. Although the carotid web has frequently been related to arterial fibrodysplasia, its natural history and pathological description remain unclear. PATIENTS: Among all consecutive patients admitted to the stroke unit of Sainte-Anne Hospital and referred to the vascular surgery department from January 2015 to December 2022, we retrospectively identified 9 patients with a carotid web. The surgical specimens of the 9 patients were submitted to systematic pathological analysis. RESULTS: The patients with a histologically confirmed carotid web were young (median age was 42 years), prominently women (7/9), and presenting with low cardiovascular risk. Eight patients had a stroke proven by a magnetic resonance imaging, and 1 had transient monocular amaurosis. The typical pathological lesion supporting the imaging pattern of the carotid web was a focal eccentric intimal hyperplasia forming a protruding lesion characterized by a population of vascular smooth muscle cells intermingled in an abundant, most often loose extracellular matrix. Pathologically proven thrombus was observed in 4 cases. Importantly atherosclerosis was absent. CONCLUSION: Histological features in our 9 cases strengthen carotid web characterization as a homogeneous pattern of localized intimal hyperplasia. It is a unique entity consistent with intimal fibroplasia, distinct from medial fibromuscular dysplasia and early atherosclerosis.

Methods: Aortic wall deformation assessment by ultrafast ultrasound imaging: Application to bicuspid aortic valve associated aortopathy.

Purpose: Aortic maximal rate of systolic distention (MRSD) is a prognosis factor of ascending aorta dilatation with magnetic resonance imaging. Its calculation requires precise continuous tracking of the aortic diameter over the cardiac cycle, which is not feasible by focused ultrasound. We aimed to develop an automatic aortic acquisition using ultrafast ultrasound imaging (UUI) to provide access to the aortic MRSD. Methods: A phased array probe and developed sequences at 2000 frames/s were used. A created interface automatically tracked the anterior and posterior aortic walls over the cardiac cycle. Tissue Doppler allowed a precise estimation of the walls' movements. MRSD was the maximum derivative of the aortic diameter curve over time. To assess its feasibility, 34 patients with bicuspid aortic valve (BAV) and 31 controls were consecutively included to evaluate the BAV-associated aortopathy at the sinus of Valsalva, the tubular ascending aorta, and the aortic arch. Results: UUI acquisitions and the dedicated interface allow tracking of the aortic diameter and calculating the MRSD for the BAV patients and controls (mean age of 34 vs. 43 years, p = 0.120). A trend toward lower deformation in the different aortic segments was observed, as expected. Still, only the MRSD with UUI was significantly different at the sinus of Valsalva in this small series: (0.61 .103.s-1 [0.37-0.72] for BAV patients vs. 0.92 .103.s-1 [0.72-1.02] for controls, p = 0.025). Conclusion: Aortic deformation evaluated with UUI deserves attention with a simple and automated measurement technique that could assess the segmental aortic injury associated with BAV.

Novel mechanism of inhibition of HIV-1 reverse transcriptase by a new non-nucleoside analog, KM-1.

2-Naphthalenesulfonic acid (4-hydroxy-7-[[[[5-hydroxy-6-[(4 cinnamylphenyl)azo]-7-sulfo-2-naphthalenyl]amino]-carbonyl]amino]-3-[(4-cinnamylphenyl)]azo (KM-1)) is a novel non-nucleoside reverse transcriptase inhibitor (NNRTI) that was designed to bind at an unconventional site on human immunodeficiency virus type 1 reverse transcriptase (RT) (Skillman, A. G., Maurer, K. W., Roe, D. C., Stauber, M. J., Eargle, D., Ewing, T. J., Muscate, A., Davioud-Charvet, E., Medaglia, M. V., Fisher, R. J., Arnold, E., Gao, H. Q., Buckheit, R., Boyer, P. L., Hughes, S. H., Kuntz, I. D., and Kenyon, G. L. (2002) Bioorg. Chem. 30, 443-458). We have investigated the mechanism by which KM-1 inhibits wild-type human immunodeficiency virus type 1 RT by using pre-steady state kinetic methods to examine the effect of KM-1 on the parameters governing the single nucleotide incorporation catalyzed by RT. Analysis of the pre-steady-state burst phase of dATP incorporation showed that KM-1 decreased the amplitude of the reaction as previously shown for other NNRTIs, because of the slow equilibration of the inhibitor with RT. In the ternary enzyme-DNA-KM-1 complex (E-DNA-I), incorporation of the next nucleotide onto the primer is blocked. However, unlike conventional NNRTIs, the inhibitory effect was caused primarily by weakening the DNA binding affinity and displacing DNA from the enzyme. Wild-type RT binds a 25/45-mer DNA duplex with an apparent K(d) of 3 nm, which was increased to 400 nm upon saturation with KM-1. Likewise, the apparent K(d) for KM-1 binding to RT increased at higher DNA concentrations. We therefore conclude that KM-1 represents a new class of inhibitor distinct from nevirapine and related NNRTIs. KM-1 can bind to RT in both the absence and presence of DNA but weakens the affinity for DNA 140-fold so that it favors DNA dissociation. The data suggest that KM-1 distorts RT conformation and misaligns DNA at the active site.

Purification of salmon thrombin and its potential as an alternative to mammalian thrombins in fibrin sealants.

A method to produce highly purified thrombin from salmon blood is described, and a series of biochemical, cell biologic, and biophysical assays demonstrate the functional similarities and some differences between salmon and human thrombins. Salmon thrombin with specific activity greater than 1000 units/mg total protein can be prepared by modifications of the methods used for purification of human thrombin. Using a synthetic substrate based on the human fibrinogen A-alpha polypeptide sequence as an indicator of enzymatic activity, salmon and human thrombin preparations contain similar specific activities per mass of purified protein. Salmon thrombin activates human fibrinogen and initiates the formation of fibrin clots whose structure and rheologic properties are indistinguishable from those of human fibrin clotted by human thrombin. Salmon thrombin also activates human platelets. Approximately 10 times higher activities are needed for the same rate of platelet aggregation compared to human thrombin, and some aspects of platelet activation, most notably phosphatidylserine exposure, are diminished relative to the effects of human thrombin. This latter finding suggests that salmon thrombin may not activate all of the receptors that are targets of human thrombin, although it does appear to activate signals that are sufficient to produce normal rates of activation and aggregation as measured by conventional aggregometry. Together with the recent purification of salmon fibrinogen and its application in mammalian wound healing, the availability of salmon thrombin allows the formulation of biological sealants devoid of any exogenous mammalian proteins and so may aid the design of materials with increased safety from infectious disease transmission.