The Experts below are selected from a list of 1680 Experts worldwide ranked by ideXlab platform
Klaus Ley - One of the best experts on this subject based on the ideXlab platform.
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ultrasound assessment of inflammation and renal tissue injury with microbubbles targeted to p selectin
Circulation, 2001Co-Authors: Jonathan R Lindner, Ji Song, Jonathan P Christiansen, Alexander L Klibanov, Klaus LeyAbstract: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 (MBp) were created by conjugating monoclonal antibodies against murine P-selectin to the lipid shell. The microvascular behaviors of MBp and control microbubbles without antibody (MB) or with isotype control antibody (MBiso) were assessed by intravital microscopy of cremasteric venules of control and tumor necrosis factor (TNF)-α–stimulated wild-type mice. Retention of all microbubbles increased (P<0.05) with TNF-α treatment because of increased attachment to activated leukocytes. Extensive attachment of MBp directly to the venular endothelium or to Adherent Platelet-leukocyte aggregates was observed in TNF-α–stimulated mice, resulting in 4-fold ...
Elizabeth M Van Cott - One of the best experts on this subject based on the ideXlab platform.
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assessment of a cohort of primarily pediatric patients with a presumptive diagnosis of type 1 von willebrand disease with a novel high shear rate non citrated blood flow device
Thrombosis Research, 2012Co-Authors: Eric F. Grabowski, Marjorie A Curran, Elizabeth M Van CottAbstract:Abstract Background A precise approach to the diagnosis of von Willebrand disease (vWD) remains elusive. One important reason is that vWD is a blood flow‐related disorder: a vW Factor‐Platelet GPIb binding defect exists in this condition under the high shear‐rate (>1000sec‐1 in whole blood; >3000sec‐1 in PRP) conditions of physiologic blood flow which exist in the arterioles of mucous membranes, from which most bleeding in vWD occurs. Methods We therefore studied 28 patients (mean 18.9yrs) with vWD, diagnosed according to the 2007 NHLBI clinical guidelines, and 26 healthy controls (mean 17.5yrs). Blood was collected into a plastic tube containing 4 U/ml FC dalteparin, 1.75μg/ml of the Tab (anti‐CD41) monoclonal antibody directed against Platelet GPIIb, and 1.0μg/ml of an ALEXA 555‐conjugated rabbit anti‐mouse second antibody. Within 30–90min, the blood was then withdrawn at 667 and 1330sec −1 through a special flow chamber allowing for real-time epifluorescence digital videomicroscopy of Platelets interacting with a microfibrillar collagen substrate. With MetaMorph software (Universal Imaging) we quantified the percent area (PA) covered by and total volume (TV) of Adherent Platelet aggregates within a 435μm×580μm field of view. Results At 667sec −1 after 1min PA and TV were similar for patients and controls, but at 1330sec −1 PA was 9.32±4.21 (mean±SD) for patients, a value lower (p 4 for patients, a value also lower (p 4 for controls. PA or TV was below the 2.5th percentile for controls in 10 patients (36%) and both PA and TV were below the 2.5th percentile in eight. Conclusions The novel flow device found that PA and TV were significantly reduced under high shear stress in vWD patients compared to normal controls. However, there was some overlap between the vWD and the control group, suggesting that some vWD patients had normal Platelet adhesion/aggregation under the conditions studied. Further study with a higher shear rate appears indicated.
Eric F. Grabowski - One of the best experts on this subject based on the ideXlab platform.
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recombinant fviii and fviia added to flowing hemophiliac blood co localize with Platelet aggregates Adherent to a collagen surface promoting local fibrin deposition in wake like patterns around the aggregates
Blood, 2015Co-Authors: Eric F. Grabowski, Bohan Liu, Matthew Gerace, Paul E Grabowski, Peter Gunnarsson, Mirella EzbanAbstract:Mural Platelet thrombi are considered to facilitate hemostasis in hemophilia via rFVIII/ rFVIIa binding to Platelet membranes with enhancement of local fibrin deposition. We therefore sought to show that Factors VIII and VIIa co-localize to Platelet membranes of Adherent Platelet aggregates and promote local deposition of fibrin. We collected blood from 9 patients with severe hemophilia A just prior to a prophylactic dose of rFVIII, and from 8 normals, into a plastic tube containing 5 U/ml FC low MW heparin, 1.75 µg/ml of the Tab (anti-CD41) mo antibody, and 1.0 μg/ml of ALEXA 555-conjugated rabbit anti-mouse secondary antibody, plus 0, 11, 33 or 100 ng/ml rFVIII-Oregon green. Similar approaches were used for rFVIIa or fibrin. Fibrin was detected using the monoclonal antibody 59D8 directed against human β fibrin, together with the above Alexa555-conjugated rabbit anti-mouse secondary antibody, and co-localized to Platelet aggregate surfaces using 10 µM quinicrine dihydrochloride. Blood at 37° C was withdrawn at 270 sec-1 through a flow chamber, over 150 µm glass cover slips with preadsorbed microfibrillar collagen, using epifluorescence video microscopy and digital image analysis (MetaMorph Premier software). Added rFVIII or rFVIIa co-localized (Fig. 1) with Platelet membranes and increased with rFVIII concentration. With hemophiliac blood and 100 ng/ml rFVIII, percent co-localization at 7 min was 52.6 ± 7.7 (N=4). Platelet aggregate growth rate, image pixels/min from time 3 to 9 min, was 26% lower in hemophiliac blood, but increased (p = 0.0001) 2.34 ± 0.62 (6)-fold with rFVIII, and (p = 0.0005) 1.91 ± 0.56 (6)-fold with 30 nM rFVIIa (Fig. 2). These increases essentially restored (or only slightly augmented) Platelet deposition to levels observed in normal blood. In contrast, the effect on local fibrin deposition was profound: fibrin deposition was delayed by 3-5 min in normal blood, but by >13 min in hemophiliac blood. Addition of rFVIII or rFVIIa shortened the latter time to 7-9 min. Increases in Platelet aggregate growth rate, following a lag phase in growth rate, paralleled the onset of fibrin formation. Fibrin appeared as comet-shaped deposits (comet head 20-25 µm in diameter) centered over each Platelet aggregate (3-10 µm), the comet tail trailing 60-75 µm downstream (Fig. 3). In flowing whole blood in real time, these data show that rFVIII and rFVIIa co-localize with Platelet membranes of activated, surface-Adherent Platelet aggregates, and support fibrin deposition in the slow-flow wakes immediately surrounding the Platelet aggregates. Disclosures Grabowski: CSL Behring: Membership on an entity9s Board of Directors or advisory committees; Novo Nordisk, Denmark: Research Funding. Gunnarsson: Novo Nordisk: Employment. Ezban: Novo Nordisk: Employment.
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assessment of a cohort of primarily pediatric patients with a presumptive diagnosis of type 1 von willebrand disease with a novel high shear rate non citrated blood flow device
Thrombosis Research, 2012Co-Authors: Eric F. Grabowski, Marjorie A Curran, Elizabeth M Van CottAbstract:Abstract Background A precise approach to the diagnosis of von Willebrand disease (vWD) remains elusive. One important reason is that vWD is a blood flow‐related disorder: a vW Factor‐Platelet GPIb binding defect exists in this condition under the high shear‐rate (>1000sec‐1 in whole blood; >3000sec‐1 in PRP) conditions of physiologic blood flow which exist in the arterioles of mucous membranes, from which most bleeding in vWD occurs. Methods We therefore studied 28 patients (mean 18.9yrs) with vWD, diagnosed according to the 2007 NHLBI clinical guidelines, and 26 healthy controls (mean 17.5yrs). Blood was collected into a plastic tube containing 4 U/ml FC dalteparin, 1.75μg/ml of the Tab (anti‐CD41) monoclonal antibody directed against Platelet GPIIb, and 1.0μg/ml of an ALEXA 555‐conjugated rabbit anti‐mouse second antibody. Within 30–90min, the blood was then withdrawn at 667 and 1330sec −1 through a special flow chamber allowing for real-time epifluorescence digital videomicroscopy of Platelets interacting with a microfibrillar collagen substrate. With MetaMorph software (Universal Imaging) we quantified the percent area (PA) covered by and total volume (TV) of Adherent Platelet aggregates within a 435μm×580μm field of view. Results At 667sec −1 after 1min PA and TV were similar for patients and controls, but at 1330sec −1 PA was 9.32±4.21 (mean±SD) for patients, a value lower (p 4 for patients, a value also lower (p 4 for controls. PA or TV was below the 2.5th percentile for controls in 10 patients (36%) and both PA and TV were below the 2.5th percentile in eight. Conclusions The novel flow device found that PA and TV were significantly reduced under high shear stress in vWD patients compared to normal controls. However, there was some overlap between the vWD and the control group, suggesting that some vWD patients had normal Platelet adhesion/aggregation under the conditions studied. Further study with a higher shear rate appears indicated.
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reduced volume and pattern of Platelet aggregation imaged using epifluorescence digital videomicroscopy in a high shear rate blood flow chamber permit the sensitive and specific diagnosis of von willebrand disease
Blood, 2009Co-Authors: Eric F. Grabowski, Ming Cheung, Emily E Biliouris, Rafail I Kushak, Elizabeth M. Van CottAbstract:Abstract 3051 Poster Board II-1027 Von Willebrand disease (vWD) is one of the most common bleeding disorders worldwide, yet a precise approach to the diagnosis of this condition and prediction of its severity remains elusive. One important reason is that vWD is a blood flow-related disorder: a vW Factor-Platelet GPIb binding defect in this condition exists under the high shear-rate conditions (>670 sec-1 in whole blood; >2000 sec-1 in PRP) of physiologic blood flow which exist in the arterioles of mucous membranes, from which most bleeding in vWD occurs. We therefore studied 15 children (ages 2-17, mean 9.9 yrs) and 2 adults with vWD, diagnosed according to the 2007 NHLBI clinical guidelines, and 12 healthy pediatric and adult controls. Blood was collected into a plastic tube containing 4 U/ml FC dalteparin, 1.75 μg/ml of the Tab (anti-CD41) monoclonal antibody directed against Platelet GPIIb (courtesy of R. P. McEver), 1.0 μg/ml of an ALEXA 555-conjugated rabbit anti-mouse second antibody, and PBS (9 parts blood:1 part PBS). Within 30-90 min, the blood was then withdrawn at 667 and 1330 sec-1 through a special flow chamber allowing for blood exposure to 150 μm glass cover clips precoated with microfibrillar collagen (Helena Laboratories). Using epifluorescence digital videomicroscopy, we imaged Platelets interacting in real time with the collagen substrate, and quantified with Simple PCI software the percent area (PA) covered by Adherent Platelet aggregates, the number of Platelet aggregates (NA), and the total volume (TV) of these aggregates within a 435 μm x 580 μm field of view. Resolution was better than 1 μm. Clinical bleeding score (ICTH) and ristocetin cofactor activity were also recorded. TV at 1330 sec-1 after 1 min, normalized to TV at 670 sec-1 after 1 min, to minimize patient/subject variation, was 2.65 ± 0.483 (mean ± SE) for normal subjects, but 1.55 ± 0.249 in vWD (P =0.043). The visualized pattern of Platelet aggregation itself (Figs. 1 and 2, flow top-to-bottom) identified 14/16 patients, for whom aggregates were 19 μm in width or smaller but NA was 500-1000, and 6/7 controls, for whom aggregates were 32 μm in width or larger and NA was 300-600. This pattern is in accord with a greater accessibility of fresh Platelets for the collagen surface in the presence of smaller aggregates, which “shield” neighboring surface sites less than do larger aggregates. Normalized TV, ristocetin cofactor activity, and bleeding score were not strongly correlated with one another, although bleeding score was positively correlated with age (P =0.0097). Platelet aggregate volume in vWD is markedly reduced in whole blood at a shear rate of 1330 sec-1, with a pattern of smaller but more numerous aggregates providing a high degree of sensitivity and specificity in the diagnosis of vWD. ![Figure][1] Disclosures No relevant conflicts of interest to declare. [1]: pending:yes
Alexander L Klibanov - One of the best experts on this subject based on the ideXlab platform.
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Ultrasound Assessment of Inflammation and Renal Tissue Injury With Microbubbles Targeted to P-Selectin
2016Co-Authors: Alexander L KlibanovAbstract: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 (MBp) were created by conjugating monoclonal antibodies against murine P-selectin to the lipid shell. The microvascular behaviors of MBp and control microbubbles without antibody (MB) or with isotype control antibody (MBiso) were assessed by intravital microscopy of cremasteric venules of control and tumor necrosis factor (TNF)-a–stimulated wild-type mice. Retention of all microbubbles increased (P,0.05) with TNF-a treatment because of increased attachment to activated leukocytes. Extensive attachment of MBp directly to the venular endothelium or to Adherent Platelet-leukocyte aggregates was observed in TNF-a–stimulated mice, resulting in 4-fold greater (P,0.01) retention of MBp than either MBiso or MB. Enhanced retention of MBp was completely abolished in TNF-a–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 MBp (1262 U) than either MBiso (663 U) or MB (563 U). In P-selectin–deficient mice, the signal for MBp was equivalent to that from control microbubbles
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ultrasound assessment of inflammation and renal tissue injury with microbubbles targeted to p selectin
Circulation, 2001Co-Authors: Jonathan R Lindner, Ji Song, Jonathan P Christiansen, Alexander L Klibanov, Klaus LeyAbstract: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 (MBp) were created by conjugating monoclonal antibodies against murine P-selectin to the lipid shell. The microvascular behaviors of MBp and control microbubbles without antibody (MB) or with isotype control antibody (MBiso) were assessed by intravital microscopy of cremasteric venules of control and tumor necrosis factor (TNF)-α–stimulated wild-type mice. Retention of all microbubbles increased (P<0.05) with TNF-α treatment because of increased attachment to activated leukocytes. Extensive attachment of MBp directly to the venular endothelium or to Adherent Platelet-leukocyte aggregates was observed in TNF-α–stimulated mice, resulting in 4-fold ...
Jonathan R Lindner - One of the best experts on this subject based on the ideXlab platform.
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ultrasound assessment of inflammation and renal tissue injury with microbubbles targeted to p selectin
Circulation, 2001Co-Authors: Jonathan R Lindner, Ji Song, Jonathan P Christiansen, Alexander L Klibanov, Klaus LeyAbstract: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 (MBp) were created by conjugating monoclonal antibodies against murine P-selectin to the lipid shell. The microvascular behaviors of MBp and control microbubbles without antibody (MB) or with isotype control antibody (MBiso) were assessed by intravital microscopy of cremasteric venules of control and tumor necrosis factor (TNF)-α–stimulated wild-type mice. Retention of all microbubbles increased (P<0.05) with TNF-α treatment because of increased attachment to activated leukocytes. Extensive attachment of MBp directly to the venular endothelium or to Adherent Platelet-leukocyte aggregates was observed in TNF-α–stimulated mice, resulting in 4-fold ...