Connector sensors for permittivity-based thrombus monitoring in extracorporeal life support.

Extracorporeal circulation is vital in cardiovascular surgery, but thrombus formation at connector interface is a major threat. Optical coherence tomography (OCT) is presently used to monitor thrombogenesis at connectors, but it is expensive to install and complex to use. This study fabricated and evaluated a connector sensor for real-time permittivity-based thrombus monitoring at tube-connector interface. Computational simulations were initially done to pre-evaluate the applicability of connector sensor. The sensor was fabricated by incorporating two stainless steel electrodes on acrylic tube for measuring permittivity changes at the tube-connector interface. OCT images were also taken from the interface at intervals for comparisons. Results show that the sensor was able to detect thrombus formation at the interface in form of sudden rise in permittivity after time t = 9 min. The permittivity changes were confirmed by OCT images which showed thrombus formation after time t = 14 min implying that permittivity changes were due to regional aggregation of red blood cells. The connector sensor is therefore envisioned as an affordable alternative to OCT for real-time permittivity-based monitoring of thrombogenesis at tube-connector interface.

Linear relationship between cytoplasm resistance and hemoglobin in red blood cell hemolysis by electrical impedance spectroscopy & eight-parameter equivalent circuit.

We have developed a non-invasive rapid and real-time red blood cell (RBC) hemolysis detection method which is a more accurate for point of care testing of hemolysis in various medical settings. An eight-parameter equivalent circuit is employed to quantify the release of hemoglobin (Hb) and the cytoplasm from RBC into the blood plasma. RBC hemolysis is induced by adding different volume fractions of distilled water into the blood. The cytoplasm released following RBC hemolysis is estimated from the experimental values. A strong relationship between RBC hemolysis and change in the electrical characteristics of blood has been demonstrated. The cytoplasm resistance (Rc) shows a linear relationship with the Hb. This relationship between Rc and Hb is described by the equation Rc = 0.2203Hb + 2.4775, with a correlation coefficient of 0.9905.

Red blood cells aggregability measurement of coagulating blood in extracorporeal circulation system with multiple-frequency electrical impedance spectroscopy.

Red blood cells (RBCs) aggregability AG of coagulating blood in extracorporeal circulation system has been investigated under the condition of pulsatile flow. Relaxation frequency fc from the multiple-frequency electrical impedance spectroscopy is utilized to obtain RBCs aggregability AG. Compared with other methods, the proposed multiple-frequency electrical impedance method is much easier to obtain non-invasive measurement with high speed and good penetrability performance in biology tissues. Experimental results show that, RBCs aggregability AG in coagulating blood falls down with the thrombus formation while that in non-coagulation blood almost keeps the same value, which has a great agreement with the activated clotting time (ACT) fibrinogen concertation (Fbg) tests. Modified Hanai formula is proposed to quantitatively analyze the influence of RBCs aggregation on multiple-frequency electrical impedance measurement. The reduction of RBCs aggregability AG is associated with blood coagulation reaction, which indicates the feasibility of the high speed, compact and cheap on-line thrombus measurement biosensors in extracorporeal circulation systems.

Relative permittivity measurement during the thrombus formation process using the dielectric relaxation method for various hematocrit values.

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.

Risk analysis and detection of thrombosis by measurement of electrical resistivity of blood.

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.

DIPOS: database of interacting proteins in Oryza sativa.

Rice is an important crop throughout the world and is the staple food for about half the world's population. For better breeding and improved production, we need to know the function of rice molecules which facilitate their function through interactions with each other. The database of interacting proteins in Oryza sativa (DIPOS) provides comprehensive information of interacting proteins in rice, where the interactions are predicted using two computational methods, i.e., interologs and domain based methods. DIPOS contains 14 614 067 pairwise interactions among 27 746 proteins, covering about 41% of the whole Oryaza sativa proteome. Furthermore, each interaction is assigned a confidence score which further enables biologists to sort out the important proteins. Biological explanations of pathways and interactions are also provided based on the database. Public access to the DIPOS is available at and .