Browsing by Author "Omkumar, RV"

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    Growth of gold nanoparticles in human cells
    (LANGMUIR, 2005) Anshup; Venkataraman, JS; Subramaniam, C; Kumar, RR; Priya, S; Kumar, TRS; Omkumar, RV; John, A; Pradeep, T
    Gold nanoparticles of 20-100 nm diameter were synthesized within HEK-293 i human embryonic kidney), HeLa (human cervical cancer), SiHa (human cervical cancer), and SKNSH (human neuroblastoma) cells, Incubation of 1 mM tetrachloroaurate solution, prepared in phosphate buffered saline (PBS), pH 7.4, with human cells grown to similar to 80% confluency yielded systematic growth of nanoparticles over a period of 96 h. The cells, stained due to nanoparticle growth, were adherent to the bottom of the wells of the tissue culture plates, with their morphology preserved, indicating that the cell membrane was intact. Transmission electron microscopy of ultrathin sections showed the presence of nanoparticles within the cytoplasm and in the nucleus, the latter being much smaller in dimension. Scanning near field microscopic images confirmed the growth of large particles within the cytoplasm. Normal cells gave UV-visible signatures of higher intensity than the cancer cells. Differences in the cellular metabolism of cancer and noricancer cells were manifested, presumably in their ability to carry out the reduction process.
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    Hysteresis In CaMKII activity: A Stochastic Model
    (2014 INTERNATIONAL CONFERENCE ON ADVANCES IN COMPUTING, COMMUNICATIONS AND INFORMATICS (ICACCI), 2014) Arun, AV; Ranjith, G; Omkumar, RV
    Calcium/calmodulin dependent protein kinase II (CaMKII) plays a crucial role in the induction of Long Term Potentiation. Several mathematical models have been developed to predict the activity levels of CaMKII in the physiological condition and its molecular switch properties. This paper attempts to study the hysteresis property of CaMKII using a stochastic model. It was observed that hysteresis exists under physiological conditions, but the width of the hysteresis band depends on the concentration of protein phosphatase 1 (PPl). The hysteresis band was maximum at low concentrations of PPI and reduced with increasing concentrations of PPI. It was also observed that the number of phosphorylated subunits saturates beyond a threshold value of calcium signal.