Journal of Biorheology
Online ISSN : 1867-0474
Print ISSN : 1867-0466
Volume 35, Issue 2
Displaying 1-4 of 4 articles from this issue
ORIGINAL ARTICLE
  • Hiroshi Ujiie, Takashi Igarashi, Ryuichi Nakagawa, Makoto Kaibara
    2021 Volume 35 Issue 2 Pages 43-48
    Published: 2021
    Released on J-STAGE: December 24, 2021
    JOURNAL FREE ACCESS

    A simple seesaw-type method using a sphere-shaped capsule as a blood testing container was developed, which is able to determine the time of onset of coagulation (coagulation time) of blood. The method is based on when a capsule containing a blood sample ceases rolling down a slope in a series of periodic, repetitive runs. From the elapsed time that the capsule stops rolling, the coagulation time can be determined. This method enables concurrent measurement of coagulation times for multiple blood samples. Optimal experimental conditions including the angle of slope and amount of blood were determined using cattle blood. The mean value of coagulation time for normal human donors was 19.6 ± 3.5 min, while that for patients taking direct oral anticoagulants (DOACs) was quite large. Addition of a coagulation accelerant (APTT reagent) to blood obtained from a normal donor and a DOAC-treated patient suffering from atrial fibrillation brought about dramatic shortening of the coagulation time. In addition, coagulation of the patient was slightly delayed compared with that of the normal donor. In this paper, it is shown that the present technique may be useful for assessing the anticoagulant effect of DOACs in patients as well as for determining the coagulation time of blood.

    Download PDF (495K)
  • Akiko Oota-Ishigaki, Osamu Maruyama, Toru Masuzawa, Masahiro Nishida
    2021 Volume 35 Issue 2 Pages 49-56
    Published: 2021
    Released on J-STAGE: December 24, 2021
    JOURNAL FREE ACCESS

    Thrombus formation on rough surfaces in cardiovascular devices implanted into patients with heart failure is a significant problem. It is, therefore, necessary to investigate the thrombus formation mechanism on rough surfaces. We have proposed a hypothesis that micro-secondary flows which are proportional to the size of micro-structure composing the rough surfaces contribute the platelet adhesion around micro-structure, that is, enhance possibility of thrombus formation. In this study, blood perfusion tests were conducted, using bovine blood with different platelet aggregation abilities, to evaluate platelet adhesion on a test piece with micro-cylinders on its surface. It was found that the platelet adhesion was sufficiently enhanced and the platelets exhibited high aggregation ability. This phenomenon depends on shear flow, and the platelets may selectively adhere to the perimeter of larger structures in the presence of micro-structures of different sizes. Our results indicate that the platelet adhesion increases in proportion to size of micro-structures when there is an average platelet aggregation per unit platelet (NL-PATI/PLT) ratio of over 0.002. These results can aid in designing the surface roughness of the blood contact material to help reduce the risk of thrombus formation.

    Download PDF (2027K)
  • Toru Maruyama, Michinari Hieda
    2021 Volume 35 Issue 2 Pages 57-61
    Published: 2021
    Released on J-STAGE: December 24, 2021
    JOURNAL FREE ACCESS

    Current sophisticated open heart surgical technologies have improved the prognosis of patients undergoing heart valve repair and replacement. Optimal antithrombotic strategy is now established using antiplatelet and anticoagulant agents, whereas subclinical erythrocyte damage caused by prosthetic heart valves is drawing less attention. Therefore, the aim of this study is to investigate the erythrocyte damage in prosthetic heart valve recipients from several viewpoints of serum biochemistry, erythrocyte morphology, and clinical hemorheology. Serum lactate dehydrogenase level was elevated significantly (p = 0.007) in patients with metallic heart valves (n = 6) but not in those with bioprosthetic heart valves (n = 8) as compared with healthy controls (n = 8). In the microscopic examination, teardrop cells, fragmented cells, and erythrocyte with local membrane protrusion (so-called budding) were observed in some patients with metallic heart valve replacement but not in the other two groups. Erythrocyte filterability estimated by our specific gravity filtration technique showed significant intergroup difference at low filtration pressure (50 cmH2O) (p < 0.001), but not at high filtration pressure (100 cmH2O). Therefore, damage to the erythrocyte by prosthetic heart valves is evident from morphologic, biochemical, and hemorheological perspectives. These findings indicate that damaged erythrocytes may have rheological impact at low shear rate condition reflecting the complicated relationship between structure and function of erythrocyte membrane regulating whole-cell deformability in concert.

    Download PDF (566K)
  • Nobuo Watanabe, Naoki Kawada
    2021 Volume 35 Issue 2 Pages 62-67
    Published: 2021
    Released on J-STAGE: December 24, 2021
    JOURNAL FREE ACCESS

    Hemolysis during mechanical circulatory support has been suggested as a possible trigger for non-hemorrhagic stroke. The purpose of this study was to investigate the hypothesis that slight hemolysis enhances thrombus formation through platelet aggregation under physiological shear stress in humans. Using sodium citrate-treated porcine whole blood from a slaughterhouse, platelet suspensions with a constant platelet density of 20.5 ± 1.3 × 103 cells/μL with three plasma free hemoglobin (pfHb) concentrations (44.9 ± 15.0, 74.3 ± 18.3, and 130.6 ± 20.3 mg/dL) were prepared through centrifugation. These suspensions were exposed to a physiological shear rate up to 200 (1/s) using our custom-built shear chamber for 0, 5, 10, and 15 min. After exposure to each shear load, microscopic image acquisition was performed and the images were analyzed to count the number of aggregated platelets. It was observed that platelet aggregation increased in an exposure time-dependent manner in all suspension fluids. In addition, the samples with the highest mean pfHb concentration of 130.6 mg/dL showed 1.23- and 1.28-fold numerically greater aggregation than those with a pfHb concentration of 74.3 and 44.9 mg/dL, respectively. The Wilcoxon signed-rank sum test showed p-values of 0.028 and 0.047 between 5 vs. 10 min and 10 vs. 15 min under the lowest pfHb concentration, respectively, and a p-value of 0.028 between 0 vs. 5 min under the medium pfHb concentration. However, there was no significant difference in aggregation according to pfHb concentration at the same exposure time. From these results, our data suggest that hemolysis might enhance platelet aggregation under physiological shear conditions.

    Download PDF (462K)
feedback
Top