201
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Sakuma T, Sari I, Goodman CN, Lindner JR, Klibanov AL, Kaul S. Simultaneous integrin αβ and glycoprotein IIb/IIIa inhibition causes reduction in infarct size in a model of acute coronary thrombosis and primary angioplasty. Cardiovasc Res 2005; 66:552-61. [PMID: 15914120 DOI: 10.1016/j.cardiores.2005.01.016] [Citation(s) in RCA: 40] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/21/2004] [Revised: 01/12/2005] [Accepted: 01/13/2005] [Indexed: 11/23/2022] Open
Abstract
OBJECTIVE We tested the hypothesis that simultaneous inhibition of the endothelial integrin alpha(v)beta(3) and the platelet glycoprotein IIb/IIIa receptor will substantially reduce infarct size in a model of acute coronary thrombosis and primary angioplasty. METHODS Dogs were subjected to thrombus formation in the left anterior descending coronary artery followed by primary angioplasty. Prior to angioplasty, they were randomized into 3 treatment groups. Group 1 (n=7) received saline; Group 2 (n=9) received MK-383 that inhibits only IIb/IIIa; and Group 3 (n=9) received CP-4715, that inhibits both IIb/IIIa and alpha(v)beta(3). RESULTS There was a 59% reduction in infarct size in dogs receiving CP-4715 compared to controls (p=0.002) and a 37% reduction compared to the dogs receiving MK-383 (p=0.04). Myocardium microthrombi were seen to be reduced similarly with both drugs on post-mortem (99m)Tc-DMP444 autoradiography that reflects in vivo IIb/IIIa receptor activity. In vivo imaging using echistatin-conjugated and leukocyte-targeted microbubbles revealed significant alpha(v)beta(3) inhibition and reduction in active leukocyte recruitment only in Group 3 dogs. Myocardial blood flow and regional function after reperfusion were also significantly better in this group. CONCLUSION Simultaneous inhibition of IIb/IIIa and alpha(v)beta(3) causes a marked reduction in infarct size in a model of acute coronary thrombosis and primary PTCA that is associated with reduced myocardial microthrombi and inflammation, as well as improved myocardial blood flow and regional function. These results may have important implications in the treatment of acute coronary syndromes.
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Affiliation(s)
- Tadamichi Sakuma
- Cardiovascular Division, Medical Center, University of Virginia, Charlottesville, 22908-0158, USA
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202
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Bragadeesh T, Sari I, Pascotto M, Micari A, Kaul S, Lindner JR. Detection of peripheral vascular stenosis by assessing skeletal muscle flow reserve. J Am Coll Cardiol 2005; 45:780-5. [PMID: 15734625 DOI: 10.1016/j.jacc.2004.11.045] [Citation(s) in RCA: 52] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/02/2004] [Revised: 11/12/2004] [Accepted: 11/15/2004] [Indexed: 11/25/2022]
Abstract
OBJECTIVES We sought to determine whether the severity of peripheral arterial disease (PAD) can be assessed by measuring blood flow reserve in limb skeletal muscle with contrast-enhanced ultrasound (CEU). BACKGROUND Noninvasive imaging of distal limb perfusion could improve management of patients with PAD by evaluating the impact of large and small vessel disease, and collateral flow. METHODS In 12 dogs, blood flow in the quadriceps femoris was measured by CEU at rest and during either electrostimulated contractile exercise or adenosine infusion. Femoral artery blood flow was measured by Doppler ultrasound. Studies were performed in the absence and presence of either moderate or severe stenosis (pressure gradient of 10 to 20 mm Hg and >20 mm Hg, respectively). RESULTS Resting femoral artery blood flow progressively decreased with stenosis severity, while resting skeletal muscle flow was reduced only with severe stenosis (52 +/- 21% of baseline, p < 0.05), indicating the presence of collateral flow. Skeletal muscle flow reserve during contractile exercise or adenosine decreased incrementally with increasing stenosis severity (p < 0.01). The stenotic pressure gradient correlated with skeletal muscle flow reserve for exercise and adenosine (r = 0.70 for both, p < 0.01). CONCLUSIONS Contrast-enhanced ultrasound of limb skeletal muscle can be used to assess the severity of PAD by measuring muscle flow reserve during either contractile exercise or pharmacologic vasodilation. Unlike currently used methods, this technique may provide a measure of the physiologic effects of large- and small-vessel PAD, and the influence of collateral perfusion.
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Affiliation(s)
- Thanjuvar Bragadeesh
- Cardiovascular Imaging Center, Cardiovascular Division, University of Virginia School of Medicine, Charlottesville, Virginia
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203
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Affiliation(s)
- Wolfgang Lepper
- Cardiovascular Imaging Center, Cardiovascular Division, University of Virginia, Charlottesville, Va 22908-0158, USA
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204
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Le DE, Jayaweera AR, Wei K, Coggins MP, Lindner JR, Kaul S. Changes in myocardial blood volume over a wide range of coronary driving pressures: role of capillaries beyond the autoregulatory range. Heart 2004; 90:1199-205. [PMID: 15367524 PMCID: PMC1768470 DOI: 10.1136/hrt.2003.020875] [Citation(s) in RCA: 43] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/04/2022] Open
Abstract
OBJECTIVE To determine whether, when the vasomotor capacity of the coronary arterioles is exhausted at rest, myocardial blood volume decreases in order to maintain a normal capillary hydrostatic pressure, even at the expense of myocardial oxygen delivery. METHODS 18 dogs were studied. In group 1 (n = 9), coronary driving pressure (CDP) was reduced by 10-80 mm Hg below normal by a stenosis; in group 2 (n = 9), it was increased 20-80 mm Hg above baseline by increasing aortic pressure with phenylephrine. Myocardial contrast echocardiography (MCE) was undertaken to measure the myocardial blood volume fraction and myocardial blood flow (MBF). RESULTS In group 1 dogs, as CDP was reduced, both coronary blood flow (CBF) and MBF decreased. Myocardial blood volume fraction also decreased and myocardial vascular resistance increased, while coronary sinus PO2 decreased. In group 2 dogs, as CDP was increased, epicardial CBF increased but MBF remained unchanged because of a decrease in myocardial blood volume fraction. Myocardial vascular resistance decreased, however, implying the presence of coronary arteriovenous shunting, which was supported by a progressive increase in the coronary sinus PO2. CONCLUSIONS When arteriolar tone is exhausted so that CBF becomes dependent on CDP, myocardial blood volume decreases in order to maintain a constant capillary hydrostatic pressure, which takes precedence over myocardial oxygen delivery. These novel findings implicate capillaries in the regulation of CBF beyond the autoregulatory range.
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Affiliation(s)
- D E Le
- The Cardiovascular Imaging Center, the Cardiovascular Division, University of Virginia School of Medicine, Charlottesville, Virginia, USA
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205
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Affiliation(s)
- Jonathan R Lindner
- Cardiovascular Division, University of Virginia Medical Center, Charlottesville, Virginia 22908, USA.
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207
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Vincent MA, Clerk LH, Lindner JR, Klibanov AL, Clark MG, Rattigan S, Barrett EJ. Microvascular recruitment is an early insulin effect that regulates skeletal muscle glucose uptake in vivo. Diabetes 2004; 53:1418-23. [PMID: 15161743 DOI: 10.2337/diabetes.53.6.1418] [Citation(s) in RCA: 317] [Impact Index Per Article: 15.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/24/2023]
Abstract
Insulin increases glucose disposal into muscle. In addition, in vivo insulin elicits distinct nitric oxide synthase-dependent vascular responses to increase total skeletal muscle blood flow and to recruit muscle capillaries (by relaxing resistance and terminal arterioles, respectively). In the current study, we compared the temporal sequence of vascular and metabolic responses to a 30-min physiological infusion of insulin (3 mU. min(-1). kg(-1), euglycemic clamp) or saline in rat skeletal muscle in vivo. We used contrast-enhanced ultrasound to continuously quantify microvascular volume. Insulin recruited microvasculature within 5-10 min (P < 0.05), and this preceded both activation of insulin-signaling pathways and increases in glucose disposal in muscle, as well as changes in total leg blood flow. Moreover, l-NAME (N(omega)-nitro-l-arginine-methyl ester), a specific inhibitor of nitric oxide synthase, blocked this early microvascular recruitment (P < 0.05) and at least partially inhibited early increases in muscle glucose uptake (P < 0.05). We conclude that insulin rapidly recruits skeletal muscle capillaries in vivo by a nitric oxide-dependent action, and the increase in capillary recruitment may contribute to the subsequent glucose uptake.
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Affiliation(s)
- Michelle A Vincent
- Department of Internal Medicine, Box 801410, University of Virginia Health Sciences Center, Charlottesville, VA 22908, USA
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208
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Takalkar AM, Klibanov AL, Rychak JJ, Lindner JR, Ley K. Binding and detachment dynamics of microbubbles targeted to P-selectin under controlled shear flow. J Control Release 2004; 96:473-82. [PMID: 15120903 DOI: 10.1016/j.jconrel.2004.03.002] [Citation(s) in RCA: 183] [Impact Index Per Article: 9.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/21/2003] [Accepted: 03/03/2004] [Indexed: 11/30/2022]
Abstract
This study was performed to assess the binding kinetics of a targeted microbubble contrast agent exposed to shear stress. An ultrasound contrast targeted to P-selectin was designed by conjugating monoclonal antibodies against murine P-selectin (RB40.34) to the lipid monolayer shell of the microbubble using poly(ethylene glycol)-biotin-streptavidin. The attachment and detachment of targeted microbubbles to P-selectin immobilized on a culture dish were assessed in a parallel-plate flow chamber. Targeted microbubbles (5 x 10(6) particles/ml) drawn through the flow chamber coated with P-selectin (109 sites/microm(2)) at a shear stress of 0.3 dyn/cm(2) accumulated at a rate of 565 mm(-2) min(-1). Attachment rates increased at higher plate surface densities of P-selectin, and microbubble detachment was reduced. Accumulation rate first increased with shear stress, reached a maximum at approximately 0.6 dyn/cm(2) and then decreased. Control experiments on a plate that lacked P-selectin, or was blocked with mAb RB40.34, resulted in minimal bubble attachment. Microbubble detachment was tested by ramping up shear stress at 30-s intervals. Half-maximal detachment was reached at 34 dyn/cm(2). Overall, accumulation and retention of targeted ultrasound contrast agents is possible under physiologic flow conditions and is strongly influenced by shear stress and surface density of the target receptor.
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Affiliation(s)
- Amol M Takalkar
- Cardiovascular Research Center and Department of Biomedical Engineering, University of Virginia Health System, Charlottesville, VA 22908-1394, USA
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209
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210
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Bragadeesh TK, Micari A, Pascotto M, Sari I, Kaul S, Lindner JR. 1074-155 The severity of peripheral vascular disease can be assessed by skeletal muscle contrast-enhanced ultrasound. J Am Coll Cardiol 2004. [DOI: 10.1016/s0735-1097(04)91391-5] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 10/26/2022]
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211
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Li X, Jiang H, Paine D, Mao Z, Bhat AH, Bader RS, von Behren P, Gustafson D, Lindner JR, Klibanov AL, Sahn DJ. 1074-152 Will combinations of multiple agents produce more robust contrast imaging? An in vitro study and in vivo studies in dogs. J Am Coll Cardiol 2004. [DOI: 10.1016/s0735-1097(04)91388-5] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
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212
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Abstract
There is growing interest in the development of methods for imaging cellular and molecular mediators of cardiovascular diseases. Techniques for imaging molecular and cellular alterations have been explored for essentially all noninvasive cardiac imaging modalities. Molecular imaging with contrast-enhanced ultrasound relies on the detection of novel site-targeted microbubble contrast agents. These microbubbles are retained within regions of a specific disease process, thereby allowing phenotypic characterization of tissue. As microbubbles are pure intravascular tracers, the disease processes assessed must be characterized by antigens that are expressed within the vascular compartment. Accordingly, the pathologic states that have been targeted include inflammation, neoplasms, angiogenesis, and thrombus formation, all of which are mediated in part by molecular events within the vascular space. This review describes (1) different strategies that have been used to target microbubbles to regions of disease, (2) the unique challenges for imaging targeted ultrasound contrast agents, and (3) some of the early experience imaging molecular events in animal models of disease.
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Affiliation(s)
- Jonathan R Lindner
- Cardiovascular Division, University of Virginia Medical Center, Charlottesville, VA 22908, USA.
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213
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Clerk LH, Vincent MA, Lindner JR, Clark MG, Rattigan S, Barrett EJ. The vasodilatory actions of insulin on resistance and terminal arterioles and their impact on muscle glucose uptake. Diabetes Metab Res Rev 2004; 20:3-12. [PMID: 14737741 DOI: 10.1002/dmrr.414] [Citation(s) in RCA: 80] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
Abstract
Whether a discrete vascular action of insulin in skeletal muscle integrally participates in insulin-mediated glucose disposal has been extensively examined but remains a contentious issue. Here, we review some of the data both supporting and questioning the role of insulin-mediated increases in limb blood flow in glucose metabolism. We advance the hypothesis that controversy has arisen, at least in part, from a failure to recognize that insulin exerts at least three separate actions on the peripheral vasculature, each with its own characteristic dose and time responsiveness. We summarize how, viewed in this manner, certain points of contention can be resolved. We also advance the hypothesis that an action on the precapillary arteriole may play the dominant role in mediating perfusion-dependent effects of insulin on glucose metabolism in muscle.
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Affiliation(s)
- Lucy H Clerk
- Department of Internal Medicine, University of Virginia Health Sciences Center, Charlottesville, Virginia 22908, USA
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214
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Pereira AM, van Thiel SW, Lindner JR, Roelfsema F, van der Wall EE, Morreau H, Smit JWA, Romijn JA, Bax JJ. Increased prevalence of regurgitant valvular heart disease in acromegaly. J Clin Endocrinol Metab 2004; 89:71-5. [PMID: 14715829 DOI: 10.1210/jc.2003-030849] [Citation(s) in RCA: 114] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/12/2023]
Abstract
Cardiac involvement is common in acromegaly, but the prevalence of valvular abnormalities in patients with acromegaly has not been documented and is the topic of this study. In a prospective study design, 40 consecutive patients with acromegaly and 120 control subjects (matched for age, sex, hypertension, and left ventricular systolic function) were studied. All patients and controls were evaluated using conventional two-dimensional and Doppler echocardiography. Significant valve disease was more prevalent in acromegalics compared with controls (22% vs. 6.7%, respectively; P = 0.005). Aortic valve regurgitation (>/=>trace severity) was present in 30% of patients vs. 7% of controls (P < 0.001), and mitral regurgitation (>/=moderate severity) was absent in controls but present in 5% of acromegalics (P = 0.014 vs. controls). Binary logistic regression analysis showed a significant impact only for disease duration on valvular disease, with an odds ratio of 1.19 (95% confidence interval, 1.028-1.376; P = 0.019). Acromegaly is associated with an increased prevalence of regurgitant valvular heart disease. This is dependent on the duration of exposure to increased GH concentrations, with a 19% increase in odds per year. This increased prevalence of occult valvular disease indicates that these patients require appropriate follow-up care and monitoring, especially patients with inadequate control of GH overproduction.
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Affiliation(s)
- Alberto M Pereira
- Department of Endocrinology and Metabolism, Leiden University Medical Center, 2300 RC Leiden, The Netherlands.
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215
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Abstract
Despite continued improvements in imaging technology, transthoracic echocardiography does not reliably provide images adequate for interpretation in all patients. In these patients, the administration of ultrasound contrast agents can markedly enhance the diagnostic utility of the test. Contrast echocardiography relies on the ultrasound detection of contrast agents composed of encapsulated microbubbles that are generally smaller than red blood cells. Intravenous administration of microbubble contrast agents results in left ventricular opacification and facilitates delineation of the endocardial border. This procedure has been shown to consistently increase the number of myocardial segments that can be interpreted, to improve accuracy of assessing regional and global left ventricular function, to decrease interinterpreter variability, to increase interpreter confidence, and to be a cost-effective strategy. Accordingly, patient selection for contrast echocardiography should be based not only on adequacy of the baseline images, but also on the clinical question being asked.
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Affiliation(s)
- Jonathan R Lindner
- Cardiovascular Division, University of Virginia Medical Center, Charlottesville, VA 22908, USA.
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216
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Christiansen JP, French BA, Klibanov AL, Kaul S, Lindner JR. Targeted tissue transfection with ultrasound destruction of plasmid-bearing cationic microbubbles. Ultrasound Med Biol 2003; 29:1759-67. [PMID: 14698343 DOI: 10.1016/s0301-5629(03)00976-1] [Citation(s) in RCA: 175] [Impact Index Per Article: 8.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/07/2023]
Abstract
The aim of this study was to assess the relative efficacy and mechanism of gene transfection by ultrasound (US) destruction of plasmid-bearing microbubbles. Luciferase reporter plasmid was charge-coupled to cationic lipid microbubbles. Rat hindlimb skeletal muscle was exposed to intermittent high-power US during dose-adjusted intra-arterial (IA) or IV administration of plasmid-bearing microbubbles via the carotid artery or jugular vein, respectively. At 4 days, luciferase activity in US-exposed skeletal muscle was 200-fold greater with IA than with IV administration of plasmid-bearing microbubbles, and was similar to transfection achieved by IM injection of plasmid (positive control). No transfection occurred with US and IA injection of plasmid alone. Intravital microscopy of the cremaster muscle in mice following administration of microbubbles and US exposure demonstrated perivascular deposition of fluorescent plasmid, the extent of which was twofold greater for IA compared to IV injection. Electron microscopy demonstrated a greater extent of myocellular microporations in US-exposed muscle after IA injection of microbubbles. We conclude that muscle transfection by US destruction of plasmid-bearing cationic microbubbles is amplified by IA, rather than IV, injection of microbubbles due to greater extravascular deposition of plasmid and to greater extent of myocellular microporation.
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Affiliation(s)
- Jonathan P Christiansen
- Cardiovascular Division, University of Virginia School of Medicine, Charlottesville, VA, USA
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217
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Ellegala DB, Leong-Poi H, Carpenter JE, Klibanov AL, Kaul S, Shaffrey ME, Sklenar J, Lindner JR. Imaging tumor angiogenesis with contrast ultrasound and microbubbles targeted to alpha(v)beta3. Circulation 2003; 108:336-41. [PMID: 12835208 DOI: 10.1161/01.cir.0000080326.15367.0c] [Citation(s) in RCA: 389] [Impact Index Per Article: 18.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
BACKGROUND Angiogenesis is a critical determinant of tumor growth and metastasis. We hypothesized that contrast-enhanced ultrasound (CEU) with microbubbles targeted to alpha(v)-integrins expressed on the neovascular endothelium could be used to image angiogenesis. METHODS AND RESULTS Malignant gliomas were produced in 14 athymic rats by intracerebral implantation of U87MG human glioma cells. On day 14 or day 28 after implantation, CEU was performed with microbubbles targeted to alpha(v)beta3 by surface conjugation of echistatin. CEU perfusion imaging with nontargeted microbubbles was used to derive tumor microvascular blood volume and blood velocity. Vascular alpha(v)-integrin expression was assessed by immunohistochemistry, and microbubble adhesion was characterized by confocal microscopy. Mean tumor size increased markedly from 14 to 28 days (2+/-1 versus 35+/-14 mm2, P<0.001). Tumor blood volume increased by approximately 35% from day 14 to day 28, whereas microvascular blood velocity decreased, especially at the central portions of the tumors. On confocal microscopy, alpha(v)beta3-targeted but not control microbubbles were retained preferentially within the tumor microcirculation. CEU signal from alpha(v)beta3-targeted microbubbles in tumors increased significantly from 14 to 28 days (1.7+/-0.4 versus 3.3+/-1.0 relative units, P<0.05). CEU signal from alpha(v)beta3-targeted microbubbles was greatest at the periphery of tumors, where alpha(v)-integrin expression was most prominent, and correlated well with tumor microvascular blood volume (r=0.86). CONCLUSIONS CEU with microbubbles targeted to alpha(v)beta3 can noninvasively detect early tumor angiogenesis. This technique, when coupled with changes in blood volume and velocity, may provide insights into the biology of tumor angiogenesis and be used for diagnostic applications.
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Affiliation(s)
- Dilantha B Ellegala
- Department of Neurosurgery, University of Virginia School of Medicine, Charlottesville, USA
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218
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Vincent MA, Barrett EJ, Lindner JR, Clark MG, Rattigan S. Inhibiting NOS blocks microvascular recruitment and blunts muscle glucose uptake in response to insulin. Am J Physiol Endocrinol Metab 2003; 285:E123-9. [PMID: 12791603 DOI: 10.1152/ajpendo.00021.2003] [Citation(s) in RCA: 234] [Impact Index Per Article: 11.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/05/2023]
Abstract
We examined the effects of inhibiting nitric oxide synthase with Nomega-nitro-l-arginine-methyl ester (l-NAME) on total hindlimb blood flow, muscle microvascular recruitment, and hindlimb glucose uptake during euglycemic hyperinsulinemia in vivo in the rat. We used two independent methods to measure microvascular perfusion. In one group of animals, microvascular recruitment was measured using the metabolism of exogenously infused 1-methylxanthine (1-MX), and in a second group contrast-enhanced ultrasound (CEU) was used. Limb glucose uptake was measured by arterial-venous concentration differences after 2 h of insulin infusion. Saline alone did not alter femoral artery flow, glucose uptake, or 1-MX metabolism. Insulin (10 mU.min-1.kg-1) significantly increased hindlimb total blood flow (0.69 +/- 0.02 to 1.22 +/- 0.11 ml/min, P < 0.05), glucose uptake (0.27 +/- 0.05 to 0.95 +/- 0.08 micromol/min, P < 0.05), 1-MX uptake (5.0 +/- 0.5 to 8.5 +/- 1.0 nmol/min, P < 0.05), and skeletal muscle microvascular volume measured by CEU (10.0 +/- 1.6 to 15.0 +/- 1.2 video intensity units, P < 0.05). Addition of l-NAME to insulin completely blocked the effect of insulin on both total limb flow and microvascular recruitment (measured using either 1-MX or CEU) and blunted glucose uptake by 40% (P < 0.05). We conclude that insulin specifically recruits flow to the microvasculture in skeletal muscle via a nitric oxide-dependent pathway and that this may be important to insulin's overall action to regulate glucose disposal.
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Affiliation(s)
- M A Vincent
- Department of Internal Medicine, University of Virginia Health Sciences Center, Charlottesville 22908, USA
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219
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van den Brink MR, Geluk CA, Lindner JR, Velthuis BK, Vonken EJ, Cramer MJM. Novel ways to noninvasively detect inflammation of the myocardium: contrast-enhanced MRI and myocardial contrast echocardiography. Neth Heart J 2003; 11:163-168. [PMID: 25696203 PMCID: PMC2499839] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/04/2023] Open
Abstract
Both contrast-enhanced magnetic resonance imaging (CE-MRI) and myocardial contrast echocardiography (MCE) are promising tools to detect cardiac inflammation. CE-MRI can be used to characterise the location and extent of myocardial inflammation, since areas of abnormal signal enhancement associated with regional wall motion abnormalities reliably indicate areas of active myocarditis. In MCE, chemically composed microbubbles can be visualised by ultrasound and used to determine the status of the cardiac microvasculature. If there is any inflammation the microbubbles will be phagocytosed by neutrophils and monocytes, thus enabling the degree of inflammation to be assessed. These noninvasive techniques may allow early diagnosis and accurate evaluation of myocardial inflammation.
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220
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Balcells E, Powers ER, Lepper W, Belcik T, Wei K, Ragosta M, Samady H, Lindner JR. Detection of myocardial viability by contrast echocardiography in acute infarction predicts recovery of resting function and contractile reserve. J Am Coll Cardiol 2003; 41:827-33. [PMID: 12628729 DOI: 10.1016/s0735-1097(02)02962-5] [Citation(s) in RCA: 88] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
Abstract
OBJECTIVES We sought to determine whether myocardial contrast echocardiography (MCE) performed before and early after primary coronary stenting (PCS) in patients with acute myocardial infarction (AMI) could predict recovery of resting left ventricular systolic function and contractile reserve. BACKGROUND Myocardial contrast echocardiography can be used to assess perfusion within the risk area before PCS and the extent of necrosis soon after PCS. METHODS In 30 patients with AMI, MCE and two-dimensional echocardiography were performed before PCS and 3 to 5 days and 4 weeks after PCS. Contractile reserve was assessed by dobutamine echocardiography at four weeks in patients with persistent severe wall-motion abnormalities. RESULTS Of segments without perfusion at 3 to 5 days, 95% had severe hypokinesis to akinesis at 4 weeks. Of segments with normal perfusion at 3 to 5 days, 90% had normal wall motion or mild hypokinesis at 4 weeks, whereas those with partial perfusion at 3 to 5 days were evenly divided between normal wall motion, hypokinesis, and akinesis. In segments with persistent severe wall-motion abnormalities at four weeks, contractile reserve was found in >80% of segments with perfusion, compared with only 10% of segments without detectable perfusion (p < 0.01). The presence of myocardial perfusion by MCE before PCS was associated with maintained or improved perfusion at 3 to 5 days and eventual recovery of resting wall motion. CONCLUSIONS Myocardial contrast echocardiography performed early after PCS provides information on the extent of infarction, and hence the likelihood for recovery of resting systolic function or contractile reserve. The presence of perfusion before PCS, from either collateral or antegrade flow, predicts the maintenance of perfusion and recovery of systolic function.
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Affiliation(s)
- Eduardo Balcells
- Cardiovascular Division, University of Virginia, Charlottesville, Virginia 22908, USA
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221
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Kaul S, Senior R, Firschke C, Lindner JR, Villanueva FS, Firoozan S, Kontos MC, Taylor AJ, Watson DD, Wang XQ. Incremental value of cardiac imaging in patients presenting to the emergency department with chest pain and without ST-segment elevation: A multicenter study. J Am Coll Cardiol 2003. [DOI: 10.1016/s0735-1097(03)81205-6] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
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222
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Leong-Poi H, Christiansen JP, Klibanov AL, Kaul S, Lindner JR. Noninvasive assessment of angiogenesis by contrast ultrasound imaging with microbubbles targeted to alpha-V integrins. J Am Coll Cardiol 2003. [DOI: 10.1016/s0735-1097(03)81289-5] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 10/26/2022]
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223
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Sakuma T, Sari I, Goodman CN, Lindner JR, Klibanov AL, Leong-Poi H, Kaul S. Simultaneous inhibition of integrin alpha V beta 3 potentiates the effect of platelet glycoprotein IIb/IIIa antagonism on infarct size reduction in acute coronary thrombosis. J Am Coll Cardiol 2003. [DOI: 10.1016/s0735-1097(03)81207-x] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 10/26/2022]
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Leong-Poi H, Ellegala D, Carpenter J, Klibanov AL, Duong V, Kaul S, Shaffrey ME, Lindner JR. Site-specific imaging of tumor angiogenesis using contrast-enhanced ultrasound imaging with microbubbles targeted to alpha-V beta-3. J Am Coll Cardiol 2003. [DOI: 10.1016/s0735-1097(03)81292-5] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
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Abstract
BACKGROUND Noninvasive methods for characterizing neovessel formation during angiogenesis are currently lacking. We hypothesized that angiogenesis could be imaged with the use of contrast-enhanced ultrasound (CEU) with microbubbles targeted to alpha(v)-integrins. METHODS AND RESULTS Microbubbles targeted to alpha(v)-integrins were prepared by conjugating echistatin (MB(E)) or monoclonal antibody against murine alpha(v) (MB(alpha)) to their surface. Control microbubbles (MB(c)) were also prepared. The microvascular behavior of these microbubbles was assessed by intravital microscopy of the cremaster muscle in mice treated for 4 days with sustained-release FGF-2. Microvascular retention was much greater (P<0.01) for MB(E) (11+/-6 mm(-3)) and MB(alpha) (10+/-7 mm(-3)) than that for MB(c) (1+/-1 mm(-3)). Retained MB(E) and MB(alpha) attached directly to the microvascular endothelial surface. Microbubble retention in 4 control mice was minimal. Subcutaneous matrigel plugs enriched with FGF-2 were created in 12 mice and studied 10 days later. Neovessels within the matrigel stained positive for alpha(v)-integrins. CEU demonstrated greater (P<0.01) acoustic intensity for MB(E) (16.0+/-5.9 U) and MB(alpha) (17.0+/-5.5 U) compared with MB(c) (5.8+/-2.6 U). The signal from targeted microbubbles (MB(E) and MB(alpha)) correlated well (r=0.90) with the matrigel blood volume determined by CEU perfusion imaging. CONCLUSIONS CEU with microbubbles targeted for alpha(v)-integrins may provide a noninvasive method for assessing therapeutic angiogenesis.
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Affiliation(s)
- Howard Leong-Poi
- Cardiovascular Imaging Center, Cardiovascular Division, University of Virginia, Charlottesville 22908, USA
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226
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Abstract
Inflammatory cell infiltration is an important factor in the progression and instability of atherosclerotic plaques. There has been great interest in the development of noninvasive methods that can assess these inflammatory processes to detect vulnerable plaques or patients, and to assess novel therapies. This review focuses on some recent advances in contrast-enhanced ultrasound (CEU), which can potentially be used for imaging plaque inflammation. These methods rely on ultrasound detection of microbubble contrast agents that are targeted to inflamed tissue. For this purpose, novel microbubbles have been formulated that are targeted either to activated leukocytes adherent to inflamed endothelium, or to endothelial cell adhesion molecules (p-selectin, intercellular adhesion molecule-1, alpha(v)beta(3)) expressed on the plaque surface or within plaque neovessels. Microbubble targeting has been achieved by modifications of shell components or conjugation of specific ligands to the shell surface. Although application of targeted CEU for imaging inflamed plaques is at the early stages of development, it is potentially easily translatable to routine clinical practice because the technique is relatively inexpensive, portable, and uses technology that already is used widely to evaluate vascular disease.
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Affiliation(s)
- Jonathan R Lindner
- Cardiac Imaging Center, the Cardiovascular Division, University of Virginia School of Medicine, Charlottesville 22908, USA.
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Abstract
Future clinical applications for contrast-enhanced ultrasound will likely expand beyond perfusion imaging. There has been considerable progress in the past few years in the development of site-targeted microbubbles, such that instead of passing unimpeded through the circulation, they attach to specific markers of disease. Accumulation of targeted microbubbles in diseased tissue can allow noninvasive ultrasound imaging of molecular and cellular processes. In this review, the strategies for designing site-targeted microbubbles and the early experience with molecular imaging will be discussed. The use of microbubbles and ultrasound for therapeutic purposes is also just now being realized. A promising development is the ability to package either drugs or genes into or onto microbubble contrast agents. Conceptually, ultrasound-mediated destruction of microbubble vehicles will provide focal release in a tissue of interest and may facilitate extravascular sojourn of the therapeutic agent. Preliminary experience using microbubbles as vectors for gene delivery is also reviewed.
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Affiliation(s)
- Jonathan R Lindner
- Cardiac Imaging Center, Cardiovascular Division, University of Virginia School of Medicine, Charlottesville, USA.
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228
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Affiliation(s)
- Jonathan R Lindner
- Cardiovascular Division, University of Virginia Medical Center, Charlottesville, VA, USA
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Schumann PA, Christiansen JP, Quigley RM, McCreery TP, Sweitzer RH, Unger EC, Lindner JR, Matsunaga TO. Targeted-microbubble binding selectively to GPIIb IIIa receptors of platelet thrombi. Invest Radiol 2002; 37:587-93. [PMID: 12393970 DOI: 10.1097/00004424-200211000-00001] [Citation(s) in RCA: 178] [Impact Index Per Article: 8.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
RATIONALE AND OBJECTIVES New targeted microbubbles directed to the GPIIb IIIa receptor have been developed. The objective was to determine whether targeting microbubbles to clots would enhance ultrasound imaging. Systematic studies were designed to determine whether in vitro methodology is an acceptable predictor of in vivo efficacy. MATERIALS AND METHODS Bioconjugate ligands were inserted into lipid-coated membranes of perfluorocarbon gas microbubbles and binding studies performed on activated platelets immobilized on cell culture plates. Targeted microbubble binding to clots in a flow through chamber was also assessed. Finally, microbubble binding studies on arteriolar and venular clots in a mouse cremasteric muscle model were conducted. RESULTS Binding studies on platelet-immobilized plates demonstrated an affinity for targeted microbubbles versus untargeted microbubbles. Semiquantitative light obscuration techniques helped to measure extent of targeted microbubble binding. Targeted microbubbles similarly bound to platelet clots in the flow model. Finally, studies in the mouse model confirmed binding of targeted microbubbles in both venules and arterioles. CONCLUSION The use of receptor selective targeted microbubbles improved binding to vascular thrombi in both in vitro and in vivo settings.
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230
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Leong-Poi H, Song J, Rim SJ, Christiansen J, Kaul S, Lindner JR. Influence of microbubble shell properties on ultrasound signal: Implications for low-power perfusion imaging. J Am Soc Echocardiogr 2002; 15:1269-76. [PMID: 12411916 DOI: 10.1067/mje.2002.124516] [Citation(s) in RCA: 61] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Low mechanical index perfusion imaging relies on the detection of signals produced by microbubble oscillation at low acoustic powers that results in minimal microbubble destruction. We hypothesized that the optimal acoustic power for real-time imaging would differ for microbubbles with different shell characteristics. Three microbubble agents with varying shell elastic properties according to their polymer composition were studied. Differences in the elastic properties of these microbubbles was demonstrated by: (1) measurement of their bulk modulus and (2) evaluation of their acoustic lability by microscopic visualization of microbubble destruction during insonification at incremental acoustic powers. The ultrasound signal generated by these microbubbles at various mechanical indexes and the degree of microbubble destruction during continuous imaging was determined both in an in vitro flow system and during in vivo imaging in an open-chest canine model. Both studies indicated that optimal power for achieving maximal signal intensity with minimal microbubble destruction was influenced by the shell elastic properties. We conclude that the acoustic power for maximizing acoustic signal without destroying microbubbles during low mechanical index imaging varies according to shell characteristics.
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Affiliation(s)
- Howard Leong-Poi
- Cardiovascular Imaging Center, Cardiovascular Division, University of Virginia School of Medicine, Charlottesville, USA
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231
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Le DE, Bin JP, Coggins MP, Wei K, Lindner JR, Kaul S. Relation between myocardial oxygen consumption and myocardial blood volume: a study using myocardial contrast echocardiography. J Am Soc Echocardiogr 2002; 15:857-63. [PMID: 12221400 DOI: 10.1067/mje.2002.121275] [Citation(s) in RCA: 42] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Myocardial blood volume (MBV) is the volume of blood residing in myocardial vessels, 90% of which is in capillaries. MBV can be measured in vivo using myocardial contrast echocardiography (MCE). It has been shown that when increases in coronary blood flow (CBF) are not associated with increase in myocardial oxygen consumption (MVO(2)), MBV does not increase. We hypothesized that MBV would increase when increases in CBF are associated with an increase in MVO(2). The atrioventricular node was ablated in 18 dogs and dual-chamber pacing was instituted. In group 1 dogs (n = 9), heart rate was altered from 50 to 150 bpm(-1) in increments of 20 bpm(-1) in random order. In group 2 dogs (n = 9), heart rate was kept constant, and dobutamine was infused at doses of 5, 10, 20, 30, and 40 microg/kg(-1)/min(-1). During each intervention, hemodynamic parameters and MVO(2) were measured, and MCE was performed. MVO(2) increased more (P <.01) with inotropic compared with chronotropic stimulation, resulting in a parallel increase in CBF. MBV fraction and MCE-derived myocardial blood flow increased significantly with increases in MVO(2) (P <.05 and P <.001, respectively) when dobutamine was infused, but remained unchanged when heart rate alone was increased. We conclude that when MVO(2) is increased substantially, the resulting increase in CBF and MCE-derived myocardial blood flow is mediated, in part, by an increase in MBV. Thus, capillary recruitment plays an important role in the physiologic regulation of CBF. Lack of increase in MBV during dobutamine stress may indicate the presence of coronary stenosis or microvascular disease.
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Affiliation(s)
- D Elizabeth Le
- Cardiovascular Imaging Center, Cardiovascular Division, School of Medicine, University of Virginia Medical Center, Charlottesville, VA 22908, USA
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232
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Fisher NG, Christiansen JP, Klibanov A, Taylor RP, Kaul S, Lindner JR. Influence of microbubble surface charge on capillary transit and myocardial contrast enhancement. J Am Coll Cardiol 2002; 40:811-9. [PMID: 12204515 DOI: 10.1016/s0735-1097(02)02038-7] [Citation(s) in RCA: 99] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
OBJECTIVE The goal of the study was to determine whether microbubble charge influences the microvascular retention of microbubble contrast agents. BACKGROUND Interactions between serum proteins and lipid membranes are greater with anionic compared with neutral membranes. These interactions may influence the microvascular behavior of anionic lipid microbubbles. METHODS Intravital microscopy of the cremaster muscle was performed in six wild-type mice and three C3-deficient mice during intravenous injection of lipid-shelled microbubbles with either a neutral or a negative charge. Both agents were prepared with and without a protective surface layer of polyethyleneglycol (PEG). Complement attachment to microbubbles was assessed by flow cytometry with flourescein isothiocyanate-conjugated anti-C3b monoclonal antibody. Myocardial contrast echocardiography was performed in six dogs to assess pulmonary and myocardial retention of microbubbles. RESULTS Size-independent capillary retention of microbubbles, occurring for a few seconds to >10 min, was frequently observed with anionic, but rarely with neutral, microbubbles (4.3 +/- 0.3 vs. 0.4 +/- 0.1 mm(-3), p < 0.01). Anionic microbubble retention was reduced by 70% by surface PEG and was also markedly reduced in C3-deficient mice (1.4 +/- 0.1 mm(-3), p < 0.05 vs. wild-type). Flow cytometry demonstrated complement attachment to only anionic microbubbles. Contrast echocardiography indicated both pulmonary and myocardial retention of only anionic microbubbles, the latter evidenced by persistent opacification >10 min after bolus intravenous injection. CONCLUSIONS Lipid microbubbles with a net negative charge can be retained within capillaries via complement-mediated attachment to endothelium. This property may be useful for the development of ultrasound contrast agents that can be imaged late after venous injection.
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Affiliation(s)
- Nicholas G Fisher
- Cardiovascular Imaging Center, Cardiovascular Division, University of Virginia, Charlottesville, Virginia 22908-0158, USA
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Riou LM, Ruiz M, Sullivan GW, Linden J, Leong-Poi H, Lindner JR, Harris TD, Beller GA, Glover DK. Assessment of myocardial inflammation produced by experimental coronary occlusion and reperfusion with 99mTc-RP517, a new leukotriene B4 receptor antagonist that preferentially labels neutrophils in vivo. Circulation 2002; 106:592-8. [PMID: 12147542 DOI: 10.1161/01.cir.0000023878.04716.6d] [Citation(s) in RCA: 19] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
BACKGROUND 99mTc-RP517 is a new leukotriene B4 (LTB4) receptor antagonist developed for imaging acute inflammation or infection. A unique property of 99mTc-RP517 is its ability to label white blood cells in vivo after intravenous injection. The goals of this study were to determine relative 99mTc-RP517 binding to human leukocyte subtypes and the 99mTc-RP517 uptake pattern in canine myocardium where inflammation was induced by either coronary occlusion and reperfusion or tumor necrosis factor alpha (TNFalpha) injection. METHODS AND RESULTS Fluorescence-activated cell sorter analysis was performed on whole human blood (n=2) and isolated neutrophils (n= 4) with a fluorescent analog of 99mTc-RP517, [F]-RP517. In whole blood, [F]-RP517 (500 nmol/L) preferentially labeled neutrophils. On isolated neutrophils, [F]-RP517 (10 nmol/L) binding was inhibited by 44% when LTB4 (400 nmol/L) was added. 99mTc-RP517 was injected intravenously in anesthetized, open-chest dogs before coronary occlusion (90 minutes) and reperfusion (120 minutes) (n=9) or before intramyocardial TNFalpha injection (n=3). Ex vivo images of heart slices were acquired. The left ventricle was divided into 72 segments for flow and 99mTc-RP517 uptake analysis. There was an inverse exponential relationship between 99mTc-RP517 uptake and occlusion flow (r=0.73). In the same 15 segments, 99mTc-RP517 uptake was highly correlated with the neutrophil enzyme myeloperoxidase (r=0.91). Ex vivo images revealed tracer uptake in the reperfused area (ischemic to normal count ratio=2.7+/-0.2). CONCLUSIONS RP517 binds to the neutrophil LTB4 receptor after intravenous injection. After reperfusion, 99mTc-RP517 uptake correlated with myeloperoxidase and was observed on ex vivo images, indicating that this tracer may have potential as an inflammation-imaging agent.
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Affiliation(s)
- Laurent M Riou
- University of Virginia Health System, Charlottesville, Va 22908-0500, USA
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234
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Abstract
The application of noninvasive imaging techniques to assess myocardial viability has become an important part of routine management of patients with acute myocardial infarction and chronic coronary artery disease. Information regarding the presence and extent of viability may help identify patients likely to benefit from revascularization or therapy directed at attenuating left ventricular remodeling. Myocardial contrast echocardiography (MCE) is capable of defining the presence and extent of viability by providing an accurate assessment of microvascular integrity needed to maintain myocellular viability. It is especially suited for the spatial assessment of perfusion, even when myocardial blood flow is reduced substantially in the presence of severe epicardial stenoses or in a bed dependent on collateral perfusion. The routine use of MCE to evaluate viability in patients with acute and chronic coronary artery disease is now feasible with the advent of new imaging technologies and microbubble agents capable of myocardial opacification from venous injections. The utility of this technique for determining treatment strategies has not been established but is forthcoming.
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Affiliation(s)
- Jonathan R Lindner
- Cardiovascular Division at the University of Virginia Medical Center, Charlottesville 22908, USA.
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235
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Abstract
The microvascular rheology and extent of pulmonary retention of second-generation microbubble ultrasound contrast agents has not previously been well characterized. We assessed the microvascular behavior of Definity, a lipid-shelled microbubble agent containing perfluoropropane gas, using intravital microscopy of either rat spinotrapezius muscle or mouse cremaster muscle. Immediately after intra-arterial injection, which was performed to model pulmonary retention, larger microbubbles (> 5 microm) were entrapped within small arterioles and capillaries. The retention fraction of microbubbles was low (1.2% +/- 0.1%) and entrapment was transient (85% dislodged by 10 minutes), resulting in no adverse hemodynamic effects. Leukocyte or platelet adhesion at the site of entrapment was not seen. After intravenous injection, no microbubble entrapment was observed and the velocities of microbubbles in arterioles, venules, and capillaries correlated well with those of red blood cells. We conclude that after intravenous injection and pulmonary passage, the microvascular rheology of Definity microbubbles is similar to that of red blood cells. Microbubble entrapment within the pulmonary microcirculation after venous injection should be negligible and transient. These findings are important for establishing the safety of this agent.
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Affiliation(s)
- Jonathan R Lindner
- Cardiac Imaging Center, the Cardiovascular Division, University of Virginia School of Medicine, Charlottesville, USA.
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236
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Abstract
BACKGROUND We hypothesized that myocardial contrast echocardiography (MCE) with leukocyte-targeted microbubbles could temporally and spatially characterize the severity of postischemic myocardial inflammation. METHODS AND RESULTS In 9 open-chest dogs, either the left anterior descending or left circumflex coronary artery was occluded for 90 minutes (n=6), while the remaining dogs served as non-ischemic controls. During occlusion, MCE was performed to determine the risk area (RA) and regions supplied by collateral flow. Myocardial inflammation was assessed 5, 60, and 120 minutes after reflow by MCE imaging of leukocyte-targeted (phosphatidylserine-containing) lipid microbubbles. The spatial extent and severity of inflammation were also assessed by radionuclide imaging of the neutrophil-avid tracer 99mTcRP517 and tissue myeloperoxidase activity. Early after reflow, MCE detected inflammation throughout the entire risk area, the extent of which decreased over time due to reduced signal in collateral-supplied regions. The spatial extent of inflammation late after reflow was similar for MCE and radionuclide imaging. The severity of inflammation in the infarct zone, the noninfarcted risk area, and collateral-supplied territories determined by quantitative MCE correlated well with myeloperoxidase activity (r=0.81). CONCLUSIONS MCE with leukocyte-targeted microbubbles can temporally assess the severity and extent of postischemic myocardial inflammation and could be used to evaluate new treatment strategies designed to limit inflammation in acute coronary syndromes.
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Affiliation(s)
- Jonathan P Christiansen
- Cardiovascular Division, University of Virginia School of Medicine, Charlottesville, Va, USA
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237
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Lepper W, Balcells E, Lindner JR, Kaul S, Belcik T, Powers E, Wei K. Collateral flow can prevent myocardial necrosis despite persistent coronary occlusion: insights using myocardial contrast echocardiography in patients. J Am Coll Cardiol 2002. [DOI: 10.1016/s0735-1097(02)81745-4] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
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238
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Christiansen JP, Klibanov AL, Lindner JR. Transfection of plasmid DNA in cardiac and skeletal muscle with ultrasound and intravenous cationic microbubble vehicles. J Am Coll Cardiol 2002. [DOI: 10.1016/s0735-1097(02)81620-5] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
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239
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Dawson D, Vincent MA, Barrett EJ, Kaul S, Clark A, Leong-Poi H, Lindner JR. Vascular recruitment in skeletal muscle during exercise and hyperinsulinemia assessed by contrast ultrasound. Am J Physiol Endocrinol Metab 2002; 282:E714-20. [PMID: 11832377 DOI: 10.1152/ajpendo.00373.2001] [Citation(s) in RCA: 120] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
The purpose of this study was to noninvasively quantify the effects of insulin on capillary blood volume (capBV) and RBC velocity (V(RBC)) in skeletal muscle in vivo with the use of contrast-enhanced ultrasound. We performed contrast ultrasound of the rat hindlimb adductor muscles at baseline and after 2-h infusions of either insulin (3 or 40 mU x kg(-1) x min(-1)) or saline. Saline-treated animals were also studied during contractile exercise. V(RBC) and capBV were calculated from the relation between pulsing interval and video intensity. Femoral artery blood flow, measured by a flow probe, increased with both contractile exercise and insulin. Contractile exercise increased capBV more than twofold and V(RBC) fivefold. Insulin also increased capBV more than twofold in a dose-dependent fashion but did not significantly alter V(RBC). Saline infusion did not significantly alter capBV, V(RBC), or femoral artery blood flow. We conclude that physiological changes in skeletal muscle capillary perfusion can be assessed in vivo with the use of contrast-enhanced ultrasound. Exercise increases both V(RBC) and capBV, whereas hyperinsulinemia selectively increases only capBV, which may enhance skeletal muscle glucose uptake.
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Affiliation(s)
- Dana Dawson
- Cardiovascular Division, University of Virginia School of Medicine, Charlottesville, Virginia 22908, USA
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240
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Christiansen JP, Leong-Poi H, Amiss LR, Drake DB, Kaul S, Lindner JR. Skin perfusion assessed by contrast ultrasound predicts tissue survival in a free flap model. Ultrasound Med Biol 2002; 28:315-320. [PMID: 11978411 DOI: 10.1016/s0301-5629(01)00523-3] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/23/2023]
Abstract
The purpose of this study was to assess perfusion in a free skin flap model using contrast-enhanced ultrasound (CEU), and to determine if the extent of perfusion early after venous occlusion predicted long-term flap survival. Perfusion was assessed in an autologous abdominal skin flap and adjacent healthy skin in rats using CEU imaging before venous occlusion and following reflow. Perfusion assessment was possible in all flaps and quantitative measurements of microvascular blood volume (BV) and blood velocity were expressed as a ratio to that in the healthy skin. Proximal flap BV 18 h after venous occlusion was significantly greater in those that survived (n = 4) vs. those that became necrotic (n = 6) (BV ratio 0.8 +/- 0.1 vs. 0.2 +/- 0.1, p = 0.0001). A BV ratio of 0.5 predicted graft viability with a sensitivity and specificity of 100%. Microvascular blood velocity at 18 h was similar in grafts that survived and those that became necrotic. Qualitative assessment of perfusion by a "blinded" observer correlated well with quantitative data and predicted flap outcome in all cases. We conclude that skin perfusion can be assessed with CEU. Perfusion 18 h following a secondary ischemic insult in a free flap accurately predicts subsequent tissue survival in this model.
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Affiliation(s)
- Jonathan P Christiansen
- Cardiac Imaging Center, the Cardiovascular Division, University of Virginia School of Medicine, Charlottesville, VA 22908, USA
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242
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Fisher NG, Christiansen JP, Klibanov AL, Leong-Poi H, Kaul S, Lindner JR. Microvascular behavior of microbubbles is strongly influenced by shell charge and polyethyleneglycol coat. J Am Coll Cardiol 2002. [DOI: 10.1016/s0735-1097(02)81536-4] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
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243
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Balcells E, Lepper W, Kaul S, Lindner JR, Belcik T, Powers E, Wei K. Infarct-related artery patency can be assessed by quantification of myocardial blood flow velocity with contrast echocardiography. J Am Coll Cardiol 2002. [DOI: 10.1016/s0735-1097(02)81631-x] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
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244
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Christiansen JP, Leong-Poi H, Amiss LR, Drake DB, Kaul S, Lindner JR. Skin perfusion assessed by contrast ultrasound predicts tissue survival in a free flap model. J Am Coll Cardiol 2002. [DOI: 10.1016/s0735-1097(02)81537-6] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
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245
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Fisher NG, Christiansen JP, Leong-Poi H, Jayaweera AR, Lindner JR, Kaul S. Myocardial and microcirculatory kinetics of BR14, a novel third-generation intravenous ultrasound contrast agent. J Am Coll Cardiol 2002; 39:530-7. [PMID: 11823094 DOI: 10.1016/s0735-1097(01)01759-4] [Citation(s) in RCA: 44] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
OBJECTIVES This study sought to investigate the myocardial and microvascular kinetics of BR14, a novel third-generation ultrasound contrast agent. BACKGROUND BR14 produces persistent myocardial opacification after the administration of a single intravenous bolus when the left ventricular cavity contrast has considerably diminished. The mechanism of this finding is unknown. METHODS Nine open-chest dogs with non-critical stenosis of a single coronary artery were given intravenous bolus injections of BR14 during coronary hyperemia. Time versus acoustic intensity (AI) plots were generated from the normal and stenosed beds and myocardial blood flow (MBF) was measured with radiolabeled microspheres. Intravital microscopy was performed on an exteriorized cremaster muscle in 11 wild-type mice to study the microvascular kinetics of the agent. RESULTS At peak contrast enhancement, the ratio between AI in the stenosed and normal bed was 0.44+/-0.23, which was similar to the radiolabeled microsphere-derived MBF ratio between the two beds (0.45 +/-0.20). At 400 s after injection, the AI ratio between the two beds approximated unity (0.99+/-0.07) despite no changes in MBF, indicating redistribution of the agent. The myocardial kinetics of BR14 was best characterized by a modified lagged normal density function. Only about 3% of administered microbubbles were estimated to be retained in the myocardium. Intravital microscopy showed that most of these bubbles were retained only transiently (2 to 3 s) within capillaries. CONCLUSIONS BR14 demonstrates redistribution because of transient retention within capillaries. Therefore, similar to (201)Tl, it could potentially be used to detect both coronary stenosis and myocardial viability after a single injection during stress.
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Affiliation(s)
- Nicholas G Fisher
- Cardiovascular Imaging Center, Cardiovascular Division, University of Virginia, Charlottesville, Virginia 22908, USA
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Vincent MA, Dawson D, Clark ADH, Lindner JR, Rattigan S, Clark MG, Barrett EJ. Skeletal muscle microvascular recruitment by physiological hyperinsulinemia precedes increases in total blood flow. Diabetes 2002; 51:42-8. [PMID: 11756321 DOI: 10.2337/diabetes.51.1.42] [Citation(s) in RCA: 160] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
Abstract
Supraphysiological doses of insulin enhance total limb blood flow and recruit capillaries in skeletal muscle. Whether these processes change in response to physiological hyperinsulinemia is uncertain. To examine this, we infused either saline (n = 6) or insulin (euglycemic clamp, 3.0 mU x min(-1) x kg(-1), n = 9) into anesthetized rats for 120 min. Femoral artery flow was monitored continuously using a Doppler flow probe, and muscle microvascular recruitment was assessed by metabolism of infused 1-methylxanthine (1-MX) and by contrast-enhanced ultrasound (CEU). Insulin infusion raised plasma insulin concentrations by approximately 10-fold. Compared with saline, physiological hyperinsulinemia increased femoral artery flow (1.02 +/- 0.10 vs. 0.68 +/- 0.09 ml/min; P < 0.05), microvascular recruitment (measured by 1-MX metabolism [6.6 +/- 0.5 vs. 4.5 +/- 0.48 nmol/min; P < 0.05] as well as by CEU [167.0 +/- 39.8 vs. 28.2 +/- 13.8%; P < 0.01]), and microvascular flow velocity (beta, 0.14 +/- 0.02 vs. 0.09 +/- 0.02 s(-1)). Subsequently, we studied the time dependency of insulin's vascular action in a second group (n = 5) of animals. Using CEU, microvascular volume was measured at 0, 30, and 90 min of insulin infusion. Insulin augmented microvascular perfusion within 30 min (52.8 +/- 14.8%), and this persisted at 90 min (64.6 +/- 9.9%). Microvascular recruitment occurred without changes to femoral artery flow or beta. We conclude that insulin increases tissue perfusion by recruiting microvascular beds, and at physiological concentrations this precedes increases in total muscle blood flow by 60-90 min.
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Affiliation(s)
- M A Vincent
- Department of Internal Medicine, University of Virginia Health Sciences Center, Charlottesville, Virginia 22908, USA.
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247
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Rim SJ, Leong-Poi H, Lindner JR, Wei K, Fisher NG, Kaul S. Decrease in coronary blood flow reserve during hyperlipidemia is secondary to an increase in blood viscosity. Circulation 2001; 104:2704-9. [PMID: 11723023 DOI: 10.1161/hc4701.099580] [Citation(s) in RCA: 65] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
BACKGROUND During maximal hyperemia, capillaries provide the greatest resistance to flow. A major determinant of capillary resistance is viscosity. We, therefore, hypothesized that abnormal coronary blood flow (CBF) reserve observed during hyperlipidemia is secondary to increased blood viscosity and not abnormal coronary vasomotion. METHODS AND RESULTS Maximal hyperemia was induced in 9 dogs using adenosine. Serum triglyceride levels were increased by incremental doses of Intralipid. A good correlation was noted between serum triglyceride levels and blood viscosity (r=0.82). Neither total coronary blood volume nor myocardial blood volume changed with increasing serum triglyceride levels, indicating lack of vasomotion. Myocardial vascular resistance (MVR) increased with increasing triglyceride levels (r=0.84), while hyperemic myocardial blood flow (MBF) decreased (r=-0.64). The decrease in hyperemic MBF was associated with a decrease in blood velocity (r=-0.56). These findings were confirmed with direct intravital microscopic observations in the mice cremaster muscle. CONCLUSIONS Increasing lipid levels in a fully dilated normal coronary bed causes no change in large or small vessel dimensions. Instead, the increase in blood viscosity causes capillary resistance to rise, which attenuates hyperemic CBF. Therefore, the abnormal CBF reserve associated with hyperlipidemia is due to increase blood viscosity and not abnormal vascular function.
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Affiliation(s)
- S J Rim
- Cardiovascular Imaging Center, Cardiovascular Division, University of Virginia, Charlottesville, VA, USA
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248
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Rim SJ, Leong-Poi H, Lindner JR, Couture D, Ellegala D, Mason H, Durieux M, Kassel NF, Kaul S. Quantification of cerebral perfusion with "Real-Time" contrast-enhanced ultrasound. Circulation 2001; 104:2582-7. [PMID: 11714654 DOI: 10.1161/hc4601.099400] [Citation(s) in RCA: 68] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
BACKGROUND No noninvasive technique is currently capable of "real-time" assessment and monitoring of cerebral blood flow (CBF). We hypothesized that cerebral perfusion could be accurately measured and monitored in "real time" with contrast-enhanced ultrasound (CEU). METHODS AND RESULTS Cerebral perfusion was assessed in 9 dogs through a craniotomy with CEU at baseline and during hypercapnia and hypocapnia while normoxia was maintained. Cerebral microvascular blood volume (A), microbubble velocity (beta), and blood flow (Axbeta) were calculated from time-versus-acoustic intensity relations. Compared with baseline, hypercapnia and hypocapnia significantly increased and decreased CBF, respectively, as measured by CEU. These changes in blood flow were mediated by changes in both A and beta. A good correlation was found between Axbeta derived from CEU and CBF measured by radiolabeled microspheres (y=0.67x-0.04, r=0.91, P<0.001). CONCLUSIONS Changes in both cerebral microvascular blood volume and red blood cell velocity can be accurately assessed with CEU. Thus, CEU has the potential for bedside measurement and monitoring of cerebral perfusion in real time in patients with craniotomies or burr holes.
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Affiliation(s)
- S J Rim
- Cardiovascular Imaging Center, Cardiovascular Division, Department of Internal Medicine, Division of Neurosurgical Anesthesia, University of Virginia, Charlottesville, USA
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249
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Coggins MP, Sklenar J, Le DE, Wei K, Lindner JR, Kaul S. Noninvasive prediction of ultimate infarct size at the time of acute coronary occlusion based on the extent and magnitude of collateral-derived myocardial blood flow. Circulation 2001; 104:2471-7. [PMID: 11705827 DOI: 10.1161/hc4501.098954] [Citation(s) in RCA: 97] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
BACKGROUND We hypothesized that by detecting regions with adequate collateral-derived myocardial blood flow (MBF) within the risk area (RA), we could predict ultimate infarct size (IS) at the time of coronary occlusion. METHODS AND RESULTS Group 1 dogs (n=15) underwent coronary occlusion without reperfusion, whereas group 2 dogs (n=6) underwent both occlusion and reperfusion. RA was measured with aortic root injections of microbubbles. Myocardial contrast echocardiography (MCE) was performed with high mechanical index intermittent harmonic imaging at pulsing intervals (PIs) of <1 to 30 cardiac cycles during an intravenous infusion of microbubbles (Sonozoid). MBF was measured with radiolabeled microspheres, and postmortem tissue staining was used to determine IS. Perfusion defect size (PDS) on MCE varied with the PI and was largest at a PI of 2.6+/-0.4 seconds, where it correlated well with RA (r=0.82). PDS was smallest at a PI of >/=10.6+/-1.5 seconds, where it correlated closely with IS (r>/=0.92). Areas that underwent necrosis could be identified early after coronary occlusion as having the lowest microvascular flow velocity (beta) and MCE-derived MBF (Axbeta). The results were similar with or without reperfusion. Because of variability in collateral-derived MBF, there was no correlation between RA and ultimate IS (P=0.37). The extent of regional dysfunction also correlated poorly with IS (r=0.31). CONCLUSIONS MCE can be used immediately after coronary occlusion to define ultimate IS by measuring the magnitude and spatial extent of collateral-derived residual MBF within the RA. Thus, it could help individualize risk and management in acute myocardial infarction.
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Affiliation(s)
- M P Coggins
- Cardiovascular Imaging Center, Cardiovascular Division, University of Virginia School of Medicine, Charlottesville, VA, USA
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250
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Lindner JR, Song J, Christiansen J, Klibanov AL, Xu F, Ley K. Ultrasound assessment of inflammation and renal tissue injury with microbubbles targeted to P-selectin. Circulation 2001; 104:2107-12. [PMID: 11673354 DOI: 10.1161/hc4201.097061] [Citation(s) in RCA: 298] [Impact Index Per Article: 13.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Abstract
BACKGROUND Routine methods capable of assessing tissue inflammation noninvasively are currently not available. We hypothesized that tissue retention of microbubbles targeted to the endothelial cell adhesion molecule P-selectin would provide a means to assess inflammation with ultrasound imaging. METHODS AND RESULTS Phospholipid microbubbles targeted to P-selectin (MB(p)) were created by conjugating monoclonal antibodies against murine P-selectin to the lipid shell. The microvascular behaviors of MB(p) and control microbubbles without antibody (MB) or with isotype control antibody (MB(iso)) were assessed by intravital microscopy of cremasteric venules of control and tumor necrosis factor (TNF)-alpha-stimulated wild-type mice. Retention of all microbubbles increased (P<0.05) with TNF-alpha treatment because of increased attachment to activated leukocytes. Extensive attachment of MB(p) directly to the venular endothelium or to adherent platelet-leukocyte aggregates was observed in TNF-alpha-stimulated mice, resulting in 4-fold greater (P<0.01) retention of MB(p) than either MB(iso) or MB. Enhanced retention of MB(p) was completely abolished in TNF-alpha-stimulated P-selectin-deficient mice. The ultrasound signal from microbubbles retained in inflamed tissue was assessed by contrast-enhanced renal ultrasound imaging of the kidneys of mice undergoing ischemia-reperfusion injury. In wild-type mice, this signal was significantly higher (P<0.05) for MB(p) (12+/-2 U) than either MB(iso) (6+/-3 U) or MB (5+/-3 U). In P-selectin-deficient mice, the signal for MB(p) was equivalent to that from control microbubbles. CONCLUSIONS Microvascular retention of microbubbles targeted to P-selectin produces strong signal enhancement on ultrasound imaging of inflamed tissue. These results suggest that site-targeted microbubbles may be used to assess inflammation, tissue injury, and other endothelial responses noninvasively with ultrasound.
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MESH Headings
- Animals
- Antibodies, Monoclonal/chemistry
- Antibodies, Monoclonal/metabolism
- Cell Adhesion/drug effects
- Cell Adhesion/immunology
- Contrast Media/administration & dosage
- Contrast Media/chemistry
- Contrast Media/metabolism
- Endothelium, Vascular/drug effects
- Endothelium, Vascular/immunology
- Endothelium, Vascular/physiopathology
- Inflammation/chemically induced
- Inflammation/diagnostic imaging
- Inflammation/physiopathology
- Injections, Intravenous
- Kidney/blood supply
- Kidney/diagnostic imaging
- Kidney/physiopathology
- Leukocytes/drug effects
- Leukocytes/immunology
- Leukocytes/metabolism
- Mice
- Mice, Knockout
- Micelles
- Muscle, Skeletal/blood supply
- Muscle, Skeletal/diagnostic imaging
- Muscle, Skeletal/drug effects
- P-Selectin/genetics
- P-Selectin/immunology
- P-Selectin/metabolism
- Phospholipids/chemistry
- Phospholipids/metabolism
- Predictive Value of Tests
- Reperfusion Injury/chemically induced
- Reperfusion Injury/diagnosis
- Reperfusion Injury/physiopathology
- Sensitivity and Specificity
- Tumor Necrosis Factor-alpha
- Ultrasonography/methods
- Venules/diagnostic imaging
- Venules/drug effects
- Venules/physiopathology
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Affiliation(s)
- J R Lindner
- Cardiovascular Division, University of Virginia School of Medicine, Charlottesville, USA.
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