The relative permittivity ε' and the dielectric loss ε″ for various hematocrit values H for static bovine blood condition have been measured using the dielectric relaxation method to detect thrombosis in real time. The suitable measurement frequency f m ranged within 60 kHz to 1 MHz, and the relaxation frequency of red blood cells (RBCs) f rc was observed to be 2 MHz. In the f m, the temporal change of normalized ε' exhibited a minimum (called as bottom point). The bottom point was observed to be exponentially shortened as H increased. This characteristic of the ε'* minimum is discussed from three viewpoints: during fibrin formation, direct thrombus formation, and rouleaux formation processes. ε'* during the fibrin formation process decreased over time, irrespective of f. However, ε'* in f m during the direct thrombus formation process and during the aggregation formation process increased immediately and rapidly over time. Therefore, the ε'* bottom point in f m might be the indication of micrometer-scale thrombus formation by RBC aggregation due to fibrin formation.
Dielectric relaxation method has been proposed for the possibility of real-time detection of thrombosis by exploiting the electrical properties of the blood. In-vitro experiments were conducted with bovine blood to measure relative permittivity and dielectric loss in the case of various hematocrit values under static blood condition. As a result, the relaxation frequency of the electrode and red blood cells were observed at 20 kHz and 2 MHz respectively. The characteristics frequency showing the permittivity of the red blood cells membrane was in the range of 60 kHz to 1 MHz. The time variations of resistivity and relative permittivity were observed at this frequency range of characteristics frequency of red blood cell membrane. Resistivity and relative permittivity measured at this frequency range increased in the case of the increase in the hematocrit values. Additionally, a peak was observed in the temporal change in relative permittivity only in the case of that frequency range. Moreover, from the results of visual check of thrombosis, this peak indicated the start of the micro-thrombus formation. This phenomenon was specific to the thrombosis, and was observed only in the presence of red blood cells. The experiments showed the possibility of the real time detection of thrombosis for implantable ventricular assistance devices, heart-lung machines and artificial kidney.
Monitoring of thrombogenic process is very important in ventricular assistance devices (VADs) used as temporary or permanent measures in patients with advanced heart failure. Currently, there is a lack of a system which can perform a real-time monitoring of thrombogenic activity. Electrical signals vary according to the change in concentration of coagulation factors as well as the distribution of blood cells, and thus have potential to detect the thrombogenic process in an early stage. In the present work, we have made an assessment of an instrumentation system exploiting the electrical properties of blood. The experiments were conducted using bovine blood. Electrical resistance tomography with eight-electrode sensor was used to monitor the spatio-temporal change in electrical resistivity of blood in thrombogenic and non-thrombogenic condition. Under non-thrombogenic condition, the resistivity was uniform across the cross-section and average resistivity monotonically decreased with time before remaining almost flat. In contrary, under thrombogenic condition, there was non-uniform distribution across the cross-section, and average resistivity fluctuated with time.
Mutations in a number of genes related to chromosomal segregation reportedly cause developmental disorders, e.g., chromosome alignment-maintaining phosphoprotein 1 (CHAMP1). We report on an 8-year-old Japanese girl who presented with a developmental disorder and microcephaly and carries a novel nonsense mutation in CHAMP1. Therefore, CHAMP1 mutation should be considered as a differential diagnosis of global developmental delay and microcephaly.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.