scholarly journals Effects of glycemic control and hypoglycemia on Thrombus formation assessed using automated microchip flow chamber system: an exploratory observational study

2019 ◽  
Vol 17 (1) ◽  
Author(s):  
Kiyoaki Yamamoto ◽  
Takashi Ito ◽  
Tomoka Nagasato ◽  
Atsushi Shinnakasu ◽  
Mihoko Kurano ◽  
...  
Keyword(s):  
Glycemic Control ◽  
Observational Study ◽  
Thrombus Formation ◽  
Flow Chamber ◽  
Chamber System

scholarly journals A modified microchip-based flow chamber system for evaluating thrombogenicity in patients with thrombocytopenia

2020 ◽  
Vol 18 (1) ◽  
Author(s):  
Bengo Atari ◽  
Takashi Ito ◽  
Tomoka Nagasato ◽  
Tomoko Ohnishi ◽  
Kazuya Hosokawa ◽  
...  
Keyword(s):  
Major Bleeding ◽  
Platelet Transfusion ◽  
Thrombus Formation ◽  
Flow Chamber ◽  
University Hospital ◽  
Minor Bleeding ◽  
Chamber System ◽  
Occlusion Time ◽  
Function Tests ◽  
Thrombogenic Potential

Abstract Background In the intensive care unit (ICU), patients with thrombocytopenia are at high risk for bleeding and should be assessed for their thrombogenic potential. However, the analytical conditions of conventional hemostatic tests are unsuitable for the evaluation of low-platelet samples. Here we aimed to establish suitable analytical conditions with the Total Thrombus-formation Analysis System (T-TAS) for quantitative assessment of thrombogenic potential in patients with thrombocytopenia and to investigate how T-TAS values relate to bleeding symptoms and the effects of platelet transfusion. Methods Modified chips with a different chamber depth were developed for the analysis of low-platelet samples in the T-TAS. We included 10 adult patients admitted to the ICU of Kagoshima University Hospital who required platelet transfusion. Patients were divided into major and minor bleeding groups according to their bleeding scale before platelet transfusion. The thrombogenic potential of these patients before and after platelet transfusion was assessed with hemostatic function tests, including rotational thromboelastometry, multiplate aggregometry, and the T-TAS. Results Analysis of low-platelet samples revealed that, compared with the conventional chip (80-μm-deep chamber), the modified chip (50-μm-deep chamber) achieved higher sensitivity in detecting elevation of flow pressure caused by growth of an occlusive thrombus in the T-TAS analytical chamber. All patients in the minor bleeding group retained thrombogenic potential that occluded the modified chip (occlusion time 16.3 ± 3.3 min), whereas most patients in the major bleeding group were unable to occlude the modified chip during the 30-min measurement (P <  0.01). The recovery of thrombogenic potential after platelet transfusion was confirmed with the T-TAS and correlated with the function, rather than the count, of transfused platelets. Among all evaluated parameters in hemostatic function tests, only the T-TAS showed significant differences in occlusion time and area under the curve both between the minor and major bleeding groups and between pre- and post-platelet transfusion. Conclusions We developed a modified microchip-based flow chamber system that reflects the hemostatic function of patients with thrombocytopenia.

scholarly journals A microchip flow-chamber system for quantitative assessment of the platelet thrombus formation process

2012 ◽  
Vol 83 (2) ◽  
pp. 154-161 ◽  
Author(s):  
Kazuya Hosokawa ◽  
Tomoko Ohnishi ◽  
Masashi Fukasawa ◽  
Taro Kondo ◽  
Hisayo Sameshima ◽  
...  
Keyword(s):  
Formation Process ◽  
Quantitative Assessment ◽  
Thrombus Formation ◽  
Flow Chamber ◽  
Chamber System ◽  
Platelet Thrombus

Combined Dabigatran and Antiplatelet Agents Assessed by the Novel Microchip-Based Flow Chamber System

Blood ◽  
2012 ◽  
Vol 120 (21) ◽  
pp. 1167-1167
Author(s):  
Kenichi Tanaka ◽  
Kazuya Hosokawa ◽  
Tomoko Ohnishi ◽  
Hisayo Sameshima ◽  
Takehiko Koide ◽  
...  
Keyword(s):  
Whole Blood ◽  
Platelet Rich Plasma ◽  
Thrombus Formation ◽  
Antiplatelet Agents ◽  
Lag Time ◽  
Flow Chamber ◽  
Chamber System ◽  
Shear Rates ◽  
Antithrombotic Effects ◽  
Flow Pressure

Abstract Abstract 1167 Evaluation of the overall antithrombotic activity of dabigatran in combination with antiplatelet agents is difficult because plasma-based clotting for dabigatran, and platelet aggregometry in anticoagulated blood are two separate tests which do not reflect physiological interactions between soluble factors and platelets. The use of a flow chamber could be more suitable in evaluating a flow-dependent platelet activation and coagulation responses. The aim of the current study was to comparatively evaluate antithrombotic effects of dabigatran in combination with dual antiplatelet therapy (aspirin plus P2Y12 blockade) using the microchip-based flow chamber (T-TAS, Fujimori Kogyo, Japan)(1), and thrombin generation (TG) assay (Thrombinoscope, Maastricht, the Netherlands)(2). After the local ethics committee approval, blood samples were obtained from consented 5 healthy volunteers in the tubes containing 3.2% sodium citrate. Whole blood samples were mixed with dabigatran (250, 500, 1000 nM), aspirin (100 nM) plus ARC-66096 (P2Y12 inhibitor, 1000 nM) at 25¡C for 10 min. Corn trypsin inhibitor (50 μg/ml) was used to prevent contact activation. The whole blood sample was perfused in the capillary pre-coated with collagen and thromboplastin at the shear rate of 240 or 600 s−1. The process of thrombus formation was monitored by flow pressure increases inside the capillary; (i) lag time before it reaches 10 kPa (T10), (ii) occlusion time (OT) is the lag time before it reaches 80 kPa as thrombus completely occludes the capillary, and (iii) AUC30 is an area under the flow pressure curve (under 80 kPa) after 30 min of perfusion. For TG assay, platelet-rich plasma (platelet count 150 × 103/μl) was prepared from citrated whole blood. TG was triggered by adding 20 μl of CaCl2-fluorogenic substrate buffer to 80 μl of the sample mixed with tissue factor (1 pM) in each well. The lag time (min), and peak thrombin concentration (nM) were evaluated. In the flow chamber, dabigatran inhibited white thrombus formation in a concentration dependent manner at shear rates of 240 and 600 s−1(Fig. 1). At 500 nM of dabigatran, OT was prolonged by ∼2-fold from the (non-treated) control at both shear rates. The combination of aspirin and AR-C66096 only weakly suppressed thrombus formation, but it enhanced the antithrombotic efficacy of dabigatran at both shear rates (Fig. 1). In TG measurements using platelet-rich plasma, dabigatran at 500 nM prolonged the by 3.17-fold, and reduced the peak by 57.6% compared to the untreated control (Table 1). Aspirin and AR-C66096 weakly prolonged the lag time without affecting the peak height. There were relatively small changes in these parameters when antiplatelet agents were combined with dabigatran (Table 1). Our results suggest that combined antithrombotic effects of dabigatran, aspirin, and P2Y12inhibition can be demonstrated in the whole blood using the flow chamber system compared without additional plasma preparation required for TG assay. The re-calcified whole blood was perfused at the shear rate of 240 s−1 or 600 s−1. Asp/AR-C=aspirin and AR-C66096 Table 1. Lag time (min) Peak (nM) Native Asp/AR-C Native Asp/AR-C Control 6.8 ± 0.8 9.4 ± 3.2 92.1 ± 23.7 91.2 ± 29.5 Dabi 250 nM 18.6 ± 5.4 21.1 ± 4.5 69.3 ± 20.6 52.2 ± 13.6 Dabi 500 nM 21.6 ± 5.3 26.2 ± 10.2 53.0 ± 5.8 47.8 ± 9.1 Dabi 1000 nM 30.2 ± 5.6 35.1 ± 6.3 23.0 ± 6.9 22.0 ± 8.4 Dabi=dabigatran, Native=no antiplatelet agents, Asp/AR-C=aspirin and AR-C66096 Disclosures: Hosokawa: Fujimori Kogyo: Employment. Ohnishi:Fujimori Kogyo: Employment. Sameshima:Fujimori Kogyo: Employment.

scholarly journals Decreased Platelet Thrombus Size, Due to a Heightened Proteolysis of VWF By ADAMTS13, Is Quickly Restored after Valve Replacement in Aortic Stenosis Patients

Blood ◽  
2014 ◽  
Vol 124 (21) ◽  
pp. 2857-2857
Author(s):  
Hideo Yagi ◽  
Masaki Hayakawa ◽  
Naoko Yamaguchi ◽  
Keigo Yamashita ◽  
Shigeki Taniguchi ◽  
...  
Keyword(s):  
Shear Stress ◽  
Aortic Valve ◽  
Valve Replacement ◽  
Thrombus Formation ◽  
Flow Chamber ◽  
High Shear ◽  
Chamber System ◽  
High Shear Stress ◽  
Platelet Thrombus ◽  
Von Willebrand

Abstract Background: The patients with severe aortic-valve stenosis (AS) are often complicated with bleeding episodes. The association between AS and gastrointestinal bleeding due to angiodysplasia is reported as Heyde's syndrome, which is categorized as one of the acquired von Willebrand disease (AVWD) in cardiovascular disorders. An international survey has shown that Type 2A is the common subtype of AVWD in the patients with AS. AVWD Type 2A is characterized by impaired platelet-dependent VWF function caused by marked decrease or absence of the most hemostatically active HMW-VWFM. In the patients with AS, a significant correlation between the increased high shear stress and loss of HMW-VWFM in vivo. Further, the absence of HMW-VWFM and bleeding tendency are normalized after valve replacement. These results suggest that enhanced proteolysis of von Willebrand factor (VWF) as it passes through the stenotic valve may induce the loss of HMW-VWFM because high shear stress can induce structure changes in VWF, which is sensitive form to the VWF cleaving protease, termed ADAMTS13. Here, we performed investigation of plasma levels of VWF antigen (VWF:Ag), ADAMTS13 activity (ADAMTS13:AC), and platelet thrombus formation in the patients with AS by valve replacement to confirm the pathophysiological mechanism of this rare disease. Patients and Methods: Ten consecutive patients who underwent aortic valve replacement for AS in Nara Medical University Hospital were enrolled in this study. The severity of AS was judged by the American Heart Association guideline. All patients had no bleeding history and received bovine tissue valves replacement followed by administration of warfarin and/or anti-platelet agents for prevention of thrombosis a week after surgery. We collected a series of blood samples from these patients before and day1, 8, 15, 22 after valve replacement. Excluding one patient who developed critical cardiac failure just after valve replacement, 9 patients were eventually evaluated by analyses of VWF:Ag, VWF multimers, ADAMTS13:AC, and mural thrombus formation using flow chamber system. VWF:Ag was measured by sandwich ELISA using a rabbit anti-human VWF polyclonal antiserum. Analysis of VWF multimers was performed according to the method of Ruggeri and Zimmerman. ADAMTS13:AC was measured by a chromogenic ADAMTS13-act-ELISA. Platelet thrombus formation was evaluated by thrombus generation under a high shear stress in a parallel plate flow chamber system. Briefly, whole blood anti-coagulated with argatroban was incubated with the fluorescent dye DiOC6 (1uM), and these samples containing DiOC6 -labeled platelets were perfused for 7 min over a type I collagen-coated glass surface under a high shear rate (1500 s-1). The DiOC6 fluorescence corresponding to the platelets was examined at an excitation wavelength of 488 nm with a barrier filter at 500 nm. The percentage of the area covered by adhering platelets (surface coverage) and each thrombus volume were evaluated. Results: Plasma levels of VWF:Ag before surgery were 78.1 % (median) and those on day 1, 8, 15, 22 after surgery were 130, 224, 155, and 134 %, respectively (Fig 1). Conversely, these levels of ADAMTS13:AC were 50.5, 35.5, 25.5, 25.1, and 30.3 %, respectively (Fig 2). The ratio of VWF:Ag/ADAMTS13:AC at before and day 1, 8, 15, 22 after surgery were 1.6, 4.5, 8.1, 6.1, and 4.1, respectively. In VWF multimer analysis, we found the obvious defect of HMW-VWFM in 7 of 9 patients before surgery, who were diagnosed with severe AS. The remaining two patients had moderate AS with the slight defect of HMW-VWFM. These defects were improved within 14 days after surgery. In platelet thrombus formation, the amount of thrombus volumes significantly increased at day 8, 15, and 22 after compared with before surgery (Fig 3). Conclusion: The dramatic recovery of platelet thrombus formation was observed in the patients with AS by valve replacement. The rapid increment of VWF and normalization of VWFM pattern, together with reduction of ADAMTS13 after valve replacement suggested heightened proteolysis of VWF by ADAMTS13 under high shear stress would be a major cause of this unique bleeding complication. The highest ratio of VWF:Ag/ADAMTS13:AC at day 8 after surgery might imply the necessity of blockade of heightened VWF function with anti-platelet agents. Figure 1 Figure 1. Disclosures Matsumoto: Alfresa Pharma Corporation: Patents & Royalties. Fujimura:Alfresa Pharma Corporation: Patents & Royalties.

Flagella and their property affect the transport and deposition behaviors of Escherichia coli in quartz sand

2021 ◽  
Author(s):  
Mengya Zhang ◽  
Lei He ◽  
Meiping Tong
Keyword(s):  
Escherichia Coli ◽  
Porous Media ◽  
Quartz Sand ◽  
Packed Column ◽  
High Mobility ◽  
Deposition Process ◽  
Flow Chamber ◽  
Chamber System ◽  
Bacterial Flagella ◽  
Silica Surfaces

&lt;p&gt;The effects of bacterial flagella as well as their property on the transport and deposition of bacteria were examined by using four types of &lt;em&gt;Escherichia coli &lt;/em&gt;(&lt;em&gt;E.coli&lt;/em&gt;) with or without flagella, as well as with normal or sticky flagella. Packed column, quartz crystal microbalance with dissipation (QCM-D), visible parallel plate flow chamber system, as well as visible flow chamber system packed with porous media system were utilized to investigate the deposition behaviors and the deposition mechanisms of bacteria with different property of flagella. We found that the presence of flagella favored &lt;em&gt;E.coli&lt;/em&gt; deposition onto quartz sand/silica surfaces. Moreover, by changing the porous media porosity and directly observing the deposition process of bacteria in porous media, grain-to-grain contacts were found to be major sites for bacterial deposition. Particularly, flagella could help bacteria swim near and then deposit at grain-to-grain contacts. In addition, we found that due to the stronger adhesive forces, sticky flagella could further enhance bacterial deposition onto quartz sand/silica surfaces. Elution experiments showed that the portion of bacteria with flagella depositing onto secondary energy minima was relatively lower than bacteria without flagella, indicating that flagella could help bacteria attach onto sand surfaces more irreversibly. Clearly, flagella and their property would have obvious influence on the transport and deposition behaviors of bacteria in porous media. By removing the flagella or changing their property, the transport and deposition of bacteria in porous media can be altered. Particularly, bacterial flagella can be removed to facilitate the transport of bacteria in remediation system requiring high mobility of bacteria, while in system requiring the immobilization bacteria in porous media, bacteria with sticky flagella can be employed.&lt;/p&gt;

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