Cardiomyocyte-targeting exosomes from sulforaphane-treated fibroblasts affords cardioprotection in infarcted rats.

BACKGROUND: Exosomes (EXOs), tiny extracellular vesicles that facilitate cell-cell communication, are being explored as a heart failure treatment, although the features of the cell source restrict their efficacy. Fibroblasts the most prevalent non-myocyte heart cells, release poor cardioprotective EXOs. A noninvasive method for manufacturing fibroblast-derived exosomes (F-EXOs) that target cardiomyocytes and slow cardiac remodeling is expected. As a cardioprotective isothiocyanate, sulforaphane (SFN)-induced F-EXOs (SFN-F-EXOs) should recapitulate its anti-remodeling properties. METHODS: Exosomes from low-dose SFN (3 µM/7 days)-treated NIH/3T3 murine cells were examined for number, size, and protein composition. Fluorescence microscopy, RT-qPCR, and western blot assessed cell size, oxidative stress, AcH4 levels, hypertrophic gene expression, and caspase-3 activation in angiotensin II (AngII)-stressed HL-1 murine cardiomyocytes 12 h-treated with various EXOs. The uptake of fluorescently-labeled EXOs was also measured in cardiomyocytes. The cardiac function of infarcted male Wistar rats intramyocardially injected with different EXOs (1·1012) was examined by echocardiography. Left ventricular infarct size, hypertrophy, and capillary density were measured. RESULTS: Sustained treatment of NIH/3T3 with non-toxic SFN concentration significantly enhances the release of CD81 + EXOs rich in TSG101 (Tumor susceptibility gene 101) and Hsp70 (Heat Shock Protein 70), and containing maspin, an endogenous histone deacetylase 1 inhibitor. SFN-F-EXOs counteract angiotensin II (AngII)-induced hypertrophy and apoptosis in murine HL-1 cardiomyocytes enhancing SERCA2a (sarcoplasmic/endoplasmic reticulum Ca2+ ATPase 2a) levels more effectively than F-EXOs. In stressed cardiomyocytes, SFN-F-EXOs boost AcH4 levels by 30% (p < 0.05) and significantly reduce oxidative stress more than F-EXOs. Fluorescence microscopy showed that mouse cardiomyocytes take in SFN-F-EXOs ~ threefold more than F-EXOs. Compared to vehicle-injected infarcted hearts, SFN-F-EXOs reduce hypertrophy, scar size, and improve contractility. CONCLUSIONS: Long-term low-dose SFN treatment of fibroblasts enhances the release of anti-remodeling cardiomyocyte-targeted F-EXOs, which effectively prevent the onset of HF. The proposed method opens a new avenue for large-scale production of cardioprotective exosomes for clinical application using allogeneic fibroblasts.

Ultra-high-frequency ultrasound and machine learning approaches for the differential diagnosis of melanocytic lesions.

Malignant melanoma (MM) is one of the most dangerous skin cancers. The aim of this study was to present a potential new method for the differential diagnosis of MM from melanocytic naevi (MN). We examined 20 MM and 19 MN with a new ultra-high-frequency ultrasound (UHFUS) equipped with a 70 MHz linear probe. Ultrasonographic images were processed for calculating 8 morphological parameters (area, perimeter, circularity, area ratio, standard deviation of normalized radial range, roughness index, overlap ratio and normalized residual mean square value) and 122 texture parameters. Colour Doppler images were used to evaluate the vascularization. Features reduction was implemented by means of principal component analysis (PCA), and 23 classification algorithms were tested on the reduced features using histological response as ground-truth. Best results were obtained using only the first component of the PCA and the weighted k-nearest neighbour classifier; this combination led to an accuracy of 76.9%, area under the ROC curve of 83%, sensitivity of 84% and specificity of 70%. The histological analysis still remains the gold-standard, but the UHFUS images processing using a machine learning approach could represent a new non-invasive approach.

Mitochondrial P2X7 Receptor Localization Modulates Energy Metabolism Enhancing Physical Performance.

Basal expression of the P2X7 receptor (P2X7R) improves mitochondrial metabolism, Adenosine 5'-triphosphate (ATP) synthesis, and overall fitness of immune and non-immune cells. We investigated P2X7R contribution to energy metabolism and subcellular localization in fibroblasts (mouse embryo fibroblasts and HEK293 human fibroblasts), mouse microglia (primary brain microglia, and the N13 microglia cell line), and heart tissue. The P2X7R localizes to mitochondria, and its lack (1) decreases basal respiratory rate, ATP-coupled respiration, maximal uncoupled respiration, resting mitochondrial potential, mitochondrial matrix Ca2+ level, (2) modifies expression pattern of oxidative phosphorylation enzymes, and (3) severely affects cardiac performance. Hearts from P2rx7-deleted versus wild-type mice are larger, heart mitochondria smaller, and stroke volume, ejection fraction, fractional shortening, and cardiac output, are significantly decreased. Accordingly, the physical fitness of P2X7R-null mice is severely reduced. Thus, the P2X7R is a key modulator of mitochondrial energy metabolism and a determinant of physical fitness.

Myo-inositol and d-chiro-inositol oral supplementation ameliorate cardiac dysfunction and remodeling in a mouse model of diet-induced obesity.

Obesity is an independent risk factor to develop cardiac functional and structural impairments. Here, we investigated the effects of supplementation of inositols on the electrical, structural, and functional cardiac alterations in the mouse model of high fat diet (HFD) induced obesity. Three groups of C57BL6 mice (n = 16 each) were studied: j) HFD feeding; jj) HFD feeding + inositols from week 9 to 13; jjj) standard diet feeding. Study observation period was 13 weeks. Inositols were administered as mixture of myo-inositol and d-chiro-inositol in the drinking water. Effects of inositols were evaluated based on electrical, structural, and functional cardiac features, autonomic sympatho-vagal balance and arrhythmogenic susceptibility to adrenergic challenge. Heart samples were collected for histological evaluations and transcriptional analyses of genes involved in defining the shape and propagation of the action potential, fatty acid metabolism and oxidative stress. Inositol supplementation significantly restored control values of heart rate and QTc interval on ECG and of sympatho-vagal balance. Moreover, it blunted the increase in left ventricular mass and cardiomyocyte hypertrophy, reversed diastolic dysfunction, reduced the susceptibility to arrhythmic events and restored the expression level of cardiac genes altered by HFD. The present study shows, for the first time, how a short period of supplementation with inositols is able to ameliorate the HFD-induced electrical, structural and functional heart alterations including ventricular remodeling. Results provide a new insight into the cardioprotective effect of inositols, which could pave the way for a novel therapeutic approach to the treatment of HFD obesity-induced heart dysfunction.

Murine model of left ventricular diastolic dysfunction and electro-mechanical uncoupling following high-fat diet.

BACKGROUND/OBJECTIVES: It is well established that obesity is an independent risk factor for cardiac death. In particular various cardiac alterations have been described in obese patients such as long QT on ECG, impaired diastolic filling of the left ventricle (LV), and all-type arrhythmias. In the present study, the above alterations were all reproduced in a mouse model of fat diet-induced obesity. ANIMALS/METHODS: In C57BL6 mice fed on a high fat (n = 20, HF-group) or standard diet (n = 20, C-group) for 13 weeks, balanced by sex and age, we examined heart morphology and function by high-frequency ultrasounds and electric activity by surface ECG. Besides, the autonomic sympathovagal balance (heart-rate variability) and the arrhythmogenic susceptibility to adrenergic challenge (i.p. isoproterenol) were compared in the two groups, as well as glucose tolerance (i.p. glucose test) and liver steatosis (ultrasounds). RESULTS: Body weight in HF-group exceeded C-group at the end of the experiment (+28% p < 0.01). An abnormal ventricular repolarization (long QTc on ECG) together with impaired LV filling rate and increased LV mass was found in HF-group as compared to C. Moreover, HF-group showed higher heart rate, unbalanced autonomic control with adrenergic prevalence and a greater susceptibility to develop rhythm disturbances under adrenergic challenge (i.p. isoprenaline). Impaired glucose tolerance and higher liver fat accumulation were also found in HF mice compared to C. CONCLUSIONS: The described murine model of 13 weeks on HF diet, well reproduced the cardiovascular and metabolic disorders reported in clinical obesity, suggesting its potential utility as translational mean suitable for testing new pharmaco-therapeutic approaches to the treatment of obesity and its comorbidity.

Measuring the Interaction Between the Macro- and Micro-Vasculature.

Structural and functional dysfunction in both the macro- and microvasculature are a feature of essential hypertension. In a healthy cardiovascular system, the elastic properties of the large arteries ensure that pulsations in pressure and flow generated by cyclic left ventricular contraction are dampened, so that less pulsatile pressure and flow are delivered at the microvascular level. However, in response to aging, hypertension, and other disease states, arterial stiffening limits the buffering capacity of the elastic arteries, thus exposing the microvasculature to increased pulsatile stress. This is thought to be particularly pertinent to high flow/low resistance organs such as the brain and kidney, which may be sensitive to excess pressure and flow pulsatility, damaging capillary networks, and resulting in target organ damage. In this review, we describe the clinical relevance of the pulsatile interaction between the macro- and microvasculature and summarize current methods for measuring the transmission of pulsatility between the two sites.

Obese mice exposed to psychosocial stress display cardiac and hippocampal dysfunction associated with local brain-derived neurotrophic factor depletion.

INTRODUCTION: Obesity and psychosocial stress (PS) co-exist in individuals of Western society. Nevertheless, how PS impacts cardiac and hippocampal phenotype in obese subjects is still unknown. Nor is it clear whether changes in local brain-derived neurotrophic factor (BDNF) account, at least in part, for myocardial and behavioral abnormalities in obese experiencing PS. METHODS: In adult male WT mice, obesity was induced via a high-fat diet (HFD). The resident-intruder paradigm was superimposed to trigger PS. In vivo left ventricular (LV) performance was evaluated by echocardiography and pressure-volume loops. Behaviour was indagated by elevated plus maze (EPM) and Y-maze. LV myocardium was assayed for apoptosis, fibrosis, vessel density and oxidative stress. Hippocampus was analyzed for volume, neurogenesis, GABAergic markers and astrogliosis. Cardiac and hippocampal BDNF and TrkB levels were measured by ELISA and WB. We investigated the pathogenetic role played by BDNF signaling in additional cardiac-selective TrkB (cTrkB) KO mice. FINDINGS: When combined, obesity and PS jeopardized LV performance, causing prominent apoptosis, fibrosis, oxidative stress and remodeling of the larger coronary branches, along with lower BDNF and TrkB levels. HFD/PS weakened LV function similarly in WT and cTrkB KO mice. The latter exhibited elevated LV ROS emission already at baseline. Obesity/PS augmented anxiety-like behaviour and impaired spatial memory. These changes were coupled to reduced hippocampal volume, neurogenesis, local BDNF and TrkB content and augmented astrogliosis. INTERPRETATION: PS and obesity synergistically deteriorate myocardial structure and function by depleting cardiac BDNF/TrkB content, leading to augmented oxidative stress. This comorbidity triggers behavioral deficits and induces hippocampal remodeling, potentially via lower BDNF and TrkB levels. FUND: J.A. was in part supported by Rotary Foundation Global Study Scholarship. G.K. was supported by T32 National Institute of Health (NIH) training grant under award number 1T32AG058527. S.C. was funded by American Heart Association Career Development Award (19CDA34760185). G.A.R.C. was funded by NIH (K01HL133368-01). APB was funded by a Grant from the Friuli Venezia Giulia Region entitled: "Heart failure as the Alzheimer disease of the heart; therapeutic and diagnostic opportunities". M.C. was supported by PRONAT project (CNR). N.P. was funded by NIH (R01 HL136918) and by the Magic-That-Matters fund (JHU). V.L. was in part supported by institutional funds from Scuola Superiore Sant'Anna (Pisa, Italy), by the TIM-Telecom Italia (WHITE Lab, Pisa, Italy), by a research grant from Pastificio Attilio Mastromauro Granoro s.r.l. (Corato, Italy) and in part by ETHERNA project (Prog. n. 161/16, Fondazione Pisa, Italy). Funding source had no such involvement in study design, in the collection, analysis, interpretation of data, in the writing of the report; and in the decision to submit the paper for publication.

Numerical simulation of novel concept 4D cardiac microtomography for small rodents based on all-optical Thomson scattering X-ray sources.

Accurate dynamic three-dimensional (4D) imaging of the heart of small rodents is required for the preclinical study of cardiac biomechanics and their modification under pathological conditions, but technological challenges are met in laboratory practice due to the very small size and high pulse rate of the heart of mice and rats as compared to humans. In 4D X-ray microtomography (4D µCT), the achievable spatio-temporal resolution is hampered by limitations in conventional X-ray sources and detectors. Here, we propose a proof-of-principle 4D µCT platform, exploiting the unique spatial and temporal features of novel concept, all-optical X-ray sources based on Thomson scattering (TS). The main spatial and spectral properties of the photon source are investigated using a TS simulation code. The entire data acquisition workflow has been also simulated, using a novel 4D numerical phantom of a mouse chest with realistic intra- and inter-cycle motion. The image quality of a typical single 3D time frame has been studied using Monte Carlo simulations, taking into account the effects of the typical structure of the TS X-ray beam. Finally, we discuss the perspectives and shortcomings of the proposed platform.

Cardiometabolic risk and subclinical vascular damage assessment in idiopathic inflammatory myopathies: a challenge for the clinician.

OBJECTIVES: A high prevalence of cardiovascular disease (CVD), not fully explained by the prevalence of traditional risk factors only, is reported in patients with idiopathic inflammatory myopathies (IIMs). Thus, we investigated if novel markers of CVD risk, like carotid diameter and advanced glycated end products, can better predict increased CVD risk in IIM patients. METHODS: We studied 43 consecutive patients diagnosed with IIM. All the patients underwent a clinical and laboratory evaluation of cardiovascular risk factors and characterisation of myositis disease activity. Non-invasive instrumental examinations performed included the measurement of carotid parameters (intima-media thickness, IMT and mean arterial diameter, mAD) by ultrasonic techniques, advanced glycation end-product accumulation in the skin by autofluorescence (AF) and body composition by bioelectrical impedance analysis. The parameters were compared to those measured in 29 controls, with similar mean age, BMI, blood pressure and smoking habits. RESULTS: IIM patients showed normal carotid IMT and distensibility, but higher carotid mAD (p=0.012), higher skin AF (p<0.001), lower fat free mass (p=0.036) and increased waist circumference compared to controls. A significant correlation was observed among AF and mAD (rho=0.317 p<0.05), carotid distension (rho=0.391 p=0.036) and IMT (rho=0.627 p<0.001). CONCLUSIONS: Abnormalities of the studied parameters suggest a higher risk of CV disease in IIM patients independent of disease activity. In this population, a thorough assessment of CV risk is recommended also in absence of overt CV disease during the clinical evaluation.

Alterations in Carotid Parameters in ApoE-/- Mice Treated with a High-Fat Diet: A Micro-ultrasound Analysis.

Information on the common carotid artery and cerebral microcirculation can be obtained by micro-ultrasound (µUS). The aim of the study described here was to investigate high-fat diet-induced alterations in vascular parameters in ApoE-/- mice. Twenty-two ApoE-/- male mice were examined by µUS and divided into the standard diet (ApoE-/-SD) and high-fat diet (ApoE-/-HF) groups. The µUS examination was repeated after 4 mo (T1). Carotid stiffness, reflection magnitude and reflection index were measured; the amplitudes of the first (W1) and second (W2) local maxima, the local minimum (Wb) and the reflection index (RIWIA = Wb/W1) were assessed with wave intensity analysis. At T1, ApoE-/-HF mice had increased carotid stiffness (1.48 [0.36] vs. 1.88 [0.51]) and reflection magnitude (0.89 [0.07] vs. 0.94 [0.07]) values. Longitudinal comparisons highlighted increases in carotid stiffness for ApoE-/-HF mice (from 1.37 [0.25] to 1.88 [0.51] m/s) but not for ApoE-/-SD mice (from 1.40 [0.62] to 1.48 [0.36] m/s). ApoE-/-HF mice exhibited carotid artery stiffening and increased wave reflections.

Antitumoral effects of attenuated Listeria monocytogenes in a genetically engineered mouse model of melanoma.

Attenuated Listeria monocytogenes (Lmat-LLO) represents a valuable anticancer vaccine and drug delivery platform. Here we show that in vitro Lmat-LLO causes ROS production and, in turn, apoptotic killing of a wide variety of melanoma cells, irrespectively of their stage, mutational status, sensitivity to BRAF inhibitors or degree of stemness. We also show that, when administered in the therapeutic setting to Braf/Pten genetically engineered mice, Lmat-LLO causes a strong decrease in the size and volume of primary melanoma tumors, as well as a reduction of the metastatic burden. At the molecular level, we confirm that the anti-melanoma activity exerted in vivo by Lmat-LLO depends also on its ability to potentiate the immune response of the organism against the infected tumor. Our data pave the way to the preclinical testing of listeria-based immunotherapeutic strategies against metastatic melanoma, using a genetically engineered mouse rather than xenograft models.

Acute Cardiovascular Adaptation to Strenuous Exercise: An Integrative Ultrasound Study.

OBJECTIVES: The aim of this study was to evaluate the acute effects of participation in an Ironman distance triathlon competition on arterial function by ultrasound, in relation to cardiac function and body water content. METHODS: Twenty-eight male triathletes participating in an Ironman distance competition underwent carotid, femoral, and cardiac ultrasound examinations. Moreover, the presence of extravascular lung water was identified by lung echo B-lines (echogenic coherent wedge-shaped signal with a narrow origin from the hyperechoic pleural line) at rest and within 20 minutes of arrival. RESULTS: At the end of the competition, athletes showed an increased heart rate (mean ± SD, from 60.2 ± 13.1 to 82.8 ± 15.6 beats/min; P < .0001) and unchanged mean blood pressure (from 93 ± 14 to 91 ± 10 mm Hg; P > .05) in the presence of negligible dehydration (total body water from 48.0 ± 4.0 to 46.5 ± 3.9 kg; P > .05). Cardiac output increased (from 5.5 ± 1.2 to 6.7 ± 2.4 L/min; P < .05) in the presence of an unchanged stroke volume (from 64 ± 14 to 59 ± 16 mL; P > .05) and unchanged left ventricular elastance (from 1.52 ± 0.48 to 1.39 ± 0.48 mm Hg/mL/m2 ; P > .05). The mean carotid diameter increased (from 7.19 ± 0.65 to 7.61 ± 0.76 mm; P < .05), whereas the mean femoral diameter was unchanged at the end of the competition (from 10.41 ± 0.83 to 10.49 ± 0.82 mm; P > .05). Carotid intima-media thickness was significantly reduced (from 537 ± 70 to 495 ± 70 µm; P < .05), whereas B-lines increased significantly after the competition (from 1 [0-4] to 12 [5-23]; P < .0001). CONCLUSIONS: These data suggest different acute functional adaptation in central arteries with respect to peripheral leg vessels.

In vivo evaluation of an elastomeric small-diameter vascular graft reinforced with a highly flexible Nitinol mesh.

Highly porous small-diameter vascular grafts (SDVGs) prepared with elastomeric materials such as poly(ether urethane) (PEtU)-polydimethylsiloxane (PEtU-PDMS) are capable to biodegrade but may develop aneurismal dilatation. Through a compliance/patency assessment with ultrasound techniques, the current study investigated the functionality, in terms of patency and endothelialization, of a highly flexible and porous Nitinol mesh incorporated into PEtU-PDMS SDVGs in a sheep carotid model. Nitinol-PEtU-PDMS grafts with an internal diameter (ID) of 4 mm were manufactured by spray, phase-inversion technique. Compliance tests were performed by ultrasound (US) imaging using a high-resolution ultrasound diagnostic system. Ten adult sheep were implanted with 7 cm long grafts. The results of this study demonstrated an almost complete neointima luminal coverage in transmurally porous grafts reinforced with the Nitinol meshes after 6 months of implantation. Additionally, ultrasound has been used to quantitatively assess and monitor hemodynamic variables in an experimental model of synthetic vascular graft replacement. The use of reinforced PEtU-PDMS grafts may accelerate the endothelialization process of relatively long grafts, such as those needed for aortocoronary bypass. © 2018 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater 107B: 951-964, 2019.

Steato-Score: Non-Invasive Quantitative Assessment of Liver Fat by Ultrasound Imaging.

Non-alcoholic fatty liver disease is becoming a global epidemic. The aim of this study was to develop a system for assessing liver fat content based on ultrasound images. Magnetic resonance spectroscopy measurements were obtained in 61 patients and the controlled attenuation parameter in 54. Ultrasound images were acquired for all 115 participants and used to calculate the hepatic/renal ratio, hepatic/portal vein ratio, attenuation rate, diaphragm visualization and portal vein wall visualization. The Steato-score was obtained by combining these five parameters. Magnetic resonance spectroscopy measurements were significantly correlated with hepatic/renal ratio, hepatic/portal vein ratio, attenuation rate, diaphragm visualization and portal vein wall visualization; Steato-score was dependent on hepatic/renal ratio, attenuation rate and diaphragm visualization. Area under the receiver operating characteristic curve was equal to 0.98, with 89% sensitivity and 94% specificity. Controlled attenuation parameter values were significantly correlated with hepatic/renal ratio, attenuation rate, diaphragm visualization and Steato-score; the area under the curve was 0.79. This system could be a valid alternative as a non-invasive, simple and inexpensive assessment of intrahepatic fat.

Ultrasonographic Characterization of the db/db Mouse: An Animal Model of Metabolic Abnormalities.

The availability of an animal model able to reliably mirror organ damage occurring in metabolic diseases is an urgent need. These models, mostly rodents, have not been fully characterized in terms of cardiovascular, renal, and hepatic ultrasound parameters, and only sparse values can be found in literature. Aim of this paper is to provide a detailed, noninvasive description of the heart, vessels, liver, and kidneys of the db/db mouse by ultrasound imaging. Sixteen wild type and thirty-four db/db male mice (11-week-old) were studied. State-of-the-art ultrasound technology was used to acquire images of cardiovascular, renal, and hepatic districts. A set of parameters describing function of the selected organs was evaluated. db/db mice are characterized by systolic and diastolic dysfunction, confirmed by strain analysis. Abdominal aortic and carotid stiffness do not seem to be increased in diabetic rodents; furthermore, they are characterized by a smaller mean diameter for both vessels. Renal microcirculation is significantly compromised, while liver steatosis is only slightly higher in db/db mice than in controls. We offer here for the first time an in vivo detailed ultrasonographic characterization of the db/db mouse, providing a useful tool for a thoughtful choice of the right rodent model for any experimental design.

Digital liver biopsy: Bio-imaging of fatty liver for translational and clinical research.

The rapidly growing field of functional, molecular and structural bio-imaging is providing an extraordinary new opportunity to overcome the limits of invasive liver biopsy and introduce a "digital biopsy" for in vivo study of liver pathophysiology. To foster the application of bio-imaging in clinical and translational research, there is a need to standardize the methods of both acquisition and the storage of the bio-images of the liver. It can be hoped that the combination of digital, liquid and histologic liver biopsies will provide an innovative synergistic tri-dimensional approach to identifying new aetiologies, diagnostic and prognostic biomarkers and therapeutic targets for the optimization of personalized therapy of liver diseases and liver cancer. A group of experts of different disciplines (Special Interest Group for Personalized Hepatology of the Italian Association for the Study of the Liver, Institute for Biostructures and Bio-imaging of the National Research Council and Bio-banking and Biomolecular Resources Research Infrastructure) discussed criteria, methods and guidelines for facilitating the requisite application of data collection. This manuscript provides a multi-Author review of the issue with special focus on fatty liver.

Ultrasound-based Pulse Wave Velocity Evaluation in Mice.

Arterial stiffness can be evaluated by calculating pulse wave velocity (PWV), i.e., the speed with which the pulse wave travels in a conduit vessel. This parameter is being increasingly investigated in small rodent models in which it is used for assessing alterations in vascular function related to particular genotypes/treatments or for characterizing cardiovascular disease progression. This protocol describes an image processing algorithm which leads to non-invasive arterial PWV measurement in mice using ultrasound (US) images only. The proposed technique has been used to assess abdominal aorta PWV in mice and evaluate its age-associated changes. Abdominal aorta US scans are obtained from mice under gaseous anesthesia using a specific US device equipped with high-frequency US probes. B-mode and Pulse-Wave Doppler (PW-Doppler) images are analyzed in order to obtain diameter and mean velocity instantaneous values, respectively. For this purpose, edge detection and contour tracking techniques are employed. The single-beat mean diameter and velocity waveforms are time aligned and combined in order to achieve the diameter-velocity (lnD-V) loop. PWV values are obtained from the slope of the linear part of the loop, which corresponds to the early systolic phase. With the present approach, anatomical and functional information about the mouse abdominal aorta can be non-invasively achieved. Requiring the processing of US images only, it may represent a useful tool for the non-invasive characterization of different arterial sites in the mouse in terms of elastic properties. The application of the present technique can be easily extended to other vascular districts, such as the carotid artery, thus providing the possibility to obtain a multi-site arterial stiffness assessment.

Wave intensity analysis in mice: age-related changes in WIA peaks and correlation with cardiac indexes.

Mouse models are increasingly employed in the comprehension of cardiovascular disease. Wave Intensity Analysis (WIA) can provide information about the interaction between the vascular and the cardiac system. We investigate age-associated changes in WIA-derived parameters in mice and correlate them with biomarkers of cardiac function. Sixteen wild-type male mice were imaged with high-resolution ultrasound (US) at 8 weeks (T 0) and 25 weeks (T 1) of age. Carotid pulse wave velocity (PWV) was calculated from US images using the diameter-velocity loop and employed to evaluate WIA. Amplitudes of the first (W 1) and the second (W 2) local maxima, local minimum (W b) and the reflection index (RI = W b/W 1) were assessed. Cardiac output (CO), ejection fraction (EF), fractional shortening (FS) and stroke volume (SV) were evaluated; longitudinal, radial and circumferential strain and strain rate values (LS, LSR, RS, RSR, CS, CSR) were obtained through strain analysis. W 1 (T 0: 4.42e-07 ± 2.32e-07 m2/s; T 1: 2.21e-07 ± 9.77 m2/s), W 2 (T 0: 2.45e-08 ± 9.63e-09 m2/s; T 1: 1.78e-08 ± 7.82 m2/s), W b (T 0: -8.75e-08 ± 5.45e-08 m2/s; T 1: -4.28e-08 ± 2.22e-08 m2/s), CO (T 0: 19.27 ± 4.33 ml/min; T 1: 16.71 ± 2.88 ml/min), LS (T 0: 17.55 ± 3.67%; T 1: 15.05 ± 2.89%), LSR (T 0: 6.02 ± 1.39 s-1; T 1: 5.02 ± 1.25 s-1), CS (T 0: 27.5 ± 5.18%; T 1: 22.66 ± 3.09%) and CSR (T 0: 10.03 ± 2.55 s-1; T 1: 7.50 ± 1.84 s-1) significantly reduced with age. W 1 was significantly correlated with CO (R = 0.58), EF (R = 0.72), LS (R = 0.65), LSR (R = 0.89), CS (R = 0.61), CSR (R = 0.70) at T 0; correlations were lost at T 1. The decrease in W 1 and W 2 suggests a cardiac performance reduction, while that in Wb, considering unchanged RI, might indicate a wave energy decrease. The loss of correlation between WIA-derived and cardiac parameters might reflect an alteration in cardiovascular interaction.

Carotid-Ventricular Coupling During Exercise: A Pilot Study.

OBJECTIVES: To evaluate carotid elasticity and left ventricular elastance during a graded bicycle semisupine exercise test in patients with known or suspected coronary artery disease and compare them with a control group of healthy young volunteers. METHODS: Thirty-six elderly patients and 18 young healthy volunteers were recruited. The right carotid diameter was estimated by an automatic system applied to B-mode sonographic sequences, central mean blood and pulse pressures by radial artery tonometry, and cardiac volumes by 2-dimensional transthoracic echocardiography; from these direct measurements, the carotid cross-sectional distensibility coefficient and left ventricular elastance index were obtained. Analyses were performed at rest, at peak stress, and during the recovery phase. RESULTS: The elderly patients included 20 men (mean age ± SD, 61 ± 8 years); the volunteers included 9 men (mean age, 34 ± 3 years). The mean blood pressure (at rest: patients, 97 ± 7 mm Hg; controls, 93 ± 9 mm Hg; not significant) increased similarly in both groups during exercise and decreased during the recovery phase. The diameter was higher in patients than controls (7.5 ± 1.1 versus 6.2 ± 0.5 mm) and increased significantly with exercise only in the latter group (at peak: 6.5 ± 0.6 mm; P < .05). The distensibility coefficient and elastance index were lower in patients than controls during the test phases [at rest: 24.5 ± 10.2 versus 60.8 ± 21.3 × 10(-3)/kPa and 3.6 ± 1.4 versus 1.6 ± 0.8 mm Hg/(mL/m(2))] and mostly changed in the controls, showing a decreased distensibility coefficient (peak: 40.6 ± 15.1 × 10(-3)/kPa) and an increased elastance index [peak: 5.9 ± 2.8 mm Hg/(mL/m(2))]. CONCLUSIONS: In older patients with multiple cardiovascular risk factors or established coronary artery disease, an abnormal carotid-ventricular adaptation to exercise was observed when compared to young healthy individuals.

Time Course of Isoflurane-Induced Vasodilation: A Doppler Ultrasound Study of the Left Coronary Artery in Mice.

Isoflurane is widely used as vasodilator in studies of coronary flow reserve (CFR) in small animals, but the protocols have not been standardized. This study assessed the time course of the increase in isoflurane-induced flow in the mouse coronary artery by pulsed-wave Doppler measurements at 1% isoflurane concentration maintained for 6 min and then increased to 2.5% for 30 min. Velocity-time integral and velocity peak values were best fitted by the sigmoid model, which allowed derivation of the mean time (Tt90 = 14 min) of high-isoflurane needed to reach 90% of the hyperemic plateau value. In subsequent experiments, CFR was measured at 4 min (mean time of literature data) and 14 min of hyperemic response. The 4-min CFR was significantly lower than the 14 -min CFR, and the Bland-Altman plot revealed significant bias of the 4-min CFR against the 14-min CFR. This result suggests that measurements of flow velocity at times shorter than 14 min may be inappropriate for expressing the effective value of CFR.