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Electrophysiology
Published in A. Bakiya, K. Kamalanand, R. L. J. De Britto, Mechano-Electric Correlations in the Human Physiological System, 2021
A. Bakiya, K. Kamalanand, R. L. J. De Britto
The concentration of the ions in the solution changes during the electron and ion interaction. Hence, the charge neutrality is inconsistent in this region, and hence, the electrolyte surrounding the conducting metal is at a different electrical potential from the rest of the solution. This potential difference is called a half-cell potential (Bronzino, 2000). The half-cell potential is most important when using the electrodes for DC measurement (Albulbul, 2016; Bronzino, 2000).
Bioelectric and Biomagnetic Signal Analysis
Published in Arvind Kumar Bansal, Javed Iqbal Khan, S. Kaisar Alam, Introduction to Computational Health Informatics, 2019
Arvind Kumar Bansal, Javed Iqbal Khan, S. Kaisar Alam
The cells depolarize and repolarize based upon the difference between the ion concentrations of Ca++ (calcium ion), NA+ (sodium ion) and K+ (potassium ion) across the cell walls. During the resting phase, the cell potential is around −90 mV due to outward leakage of K+ (potassium ion) ions from the cell. During resting phase Ca++ (calcium ion) and Na+ (sodium ion) channels for the inflow of ions into the cells are closed. Before a depolarization starts, Na+ (sodium ion) concentration outside the cell is higher than inside the cell. Electrical activity starts from the SA-node (Sino-atrial node) located on the top right corner of the right-atrium, and then it spreads through the atrium.
Designing a Low-Cost ECG Sensor and Monitor: Practical Considerations and Measures
Published in Daniel Tze Huei Lai, Rezaul Begg, Marimuthu Palaniswami, Healthcare Sensor Networks, 2016
Ahsan H. Khandoker, Brian A. Walker
The best materials to use for electrodes minimize the half cell potential (which causes DC baseline offsets and drifts), are easy to manufacture and are not highly reactive. Materials which produce low half cell potentials increase electrode stability. For example, lithium would not be used for the electrodes as its half cell potential is −3 V, and its reactivity is enough to burn the skin. Another problem to consider is that the half cell potential could vary depending on the amount of current flowing through the electrode. This is known as an overpotential (Hinz 2002). Electrodes which do not have overpotentials are known as nonpolarizable electrodes. Examples of nonpolarizable electrodes include those made from copper and silver chloride (Allaby and Allaby 1999). Normally, commercial electrodes are made from silver with a coating of silver chloride (Amer 2008). The half cell potential of silver chloride is very low, 223 mV, and is ideal for ECG measurement. Copper can also give satisfactory results; it has a half cell potential of 342 mV (Hinz 2002).
Selective delivery of curcumin to breast cancer cells by self-targeting apoferritin nanocages with pH-responsive and low toxicity
Published in Drug Delivery, 2022
Peng Ji, Xianglong Wang, Jiabing Yin, Yi Mou, Haiqin Huang, Zhenkun Ren
Generally, apoptosis is one of the main mechanisms leading to the death of cancer cells, making it necessary to evaluate the apoptotic cell potential of the preparation (Singh et al., 2019). The apoptosis of 4T1 cells treated with Cur and Cur@HFn was analyzed using annexin V-FITC/PI flow cytometer. Figure S3A shows the dotted line graph detected by flow cytometry. The lower left quadrant (Q4) corresponds to live cells; the lower right quadrant (Q3) corresponds to early apoptotic cells; the upper right quadrant (Q2) represents late apoptosis, and the upper left quadrant (Q1) contains necrotic cells. The total amount of apoptosis was calculated by Q3 and Q2 (Figure S3B). Compared with the Cur group, Cur@HFn induced a greater proportion of 4T1 cell apoptosis (p < .001), reaching 15% of cell apoptosis. The enhanced cancer cell suppression effect of Cur@HFn may be attributed to the high-efficiency targeted cell uptake and cur enrichment to produce excessive ROS (Yu et al., 2021), which is consistent with the above-mentioned in vitro cytotoxicity test results. Nuclei were visualized by counterstaining with DAPI (blue, Figure S3C). Compared with the control group, the cells in the drug-treated group showed condensed nuclei and deepened staining. The special morphological (Figure S3D) feature of apoptotic cell was observed with electron microscope, and the volume of cells in the Cur@HFn group was significantly reduced. The morphological results indicated that Cur and Cur@HFn induced apoptosis at an early stage, which was consistent with the flow cytometry results.
Subacute oral toxicity investigation of selenium nanoparticles and selenite in rats
Published in Drug and Chemical Toxicology, 2019
Niels Hadrup, Katrin Loeschner, Karen Mandrup, Gitte Ravn-Haren, Henrik L. Frandsen, Erik H. Larsen, Henrik R. Lam, Alicja Mortensen
Dopamine, noradrenaline, and serotonin were measured as previously described (Hadrup et al.2012). A brief description is as follows, brain tissue was homogenized under ice-cold conditions in 0.32 M sucrose (9 mL/whole brain) using an UltraTurrax T25 homogenizer (IKA, Staufen, Germany). Then, the homogenate was de-proteinised using a 1:1 volume of 0.2 M perchloric acid (HClO4) followed by centrifugation (20 min, 0–4 °C, 10 000 ×g). For the noradrenaline and dopamine measurements, 3,4-dihydroxybenzylamine (Sigma, D 7012) was added as internal standard. Next, the samples were purified on aluminum oxide (Anton and Sayre 1962) followed by elution with 0.2 M HClO4. For the analysis of 5-HT, N-ϖ-methyl-5-HT (Sigma, M 1514) was added as internal standard. The neurotransmitters were measured using high-performance liquid chromatography with electrochemical detection. The instrumentation consisted of a Hewlett-Packard Ti-SERIES 1100 liquid chromatograph equipped with an ESA MD-150 analytical column (3 mm ID 15 cm, C18, 5 mm). Separation was achieved with a 5% (v/v) acetonitrile modified 75 mM sodium phosphate buffer (1.7 octanylsulfonic acid, 100 mL triethylamine/L, and 25 mM EDTA; pH 3). Signals were detected using a dual potentiostat electrochemical detector (ESA Model 5200 A Coulochem II and ESA Model 5011 high sensitivity analytical cell with an E1 of 150 mV and an E2 of +220 mV; guard cell potential: +350 mV, Chelmsford, MA).
The existence and potential of germline stem cells in the adult mammalian ovary
Published in Climacteric, 2019
Central to the identification of these cells is their ability to undergo mitotic division, to express proteins associated with the germline, such as DDX4, KIT, DPPA3, IFITM3, and PRDM1, and with pluripotency, including POU5F1, LIN28, and NANOG. Several studies have now demonstrated the isolation of mitotic cells expressing germline markers from ovaries of adult rodents6,7,9–11, cows12, sheep13, primates14, and humans7,12,13,15–18. These cells have been called female germline stem cells, oogonial stem cells (OSCs), egg precursor cells, or indeed very small embryonic-like stem cells. In this review the cells will be referred to as putative OSCs in recognition that these cells have yet to be fully characterized and their true stem cell potential determined.