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Search Results: 1 - 10 of 248 matches for " Swaminathan Sethu "
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Phospholipase D1 Mediates TNFα-Induced Inflammation in a Murine Model of TNFα-Induced Peritonitis
Swaminathan Sethu,Peter N. Pushparaj,Alirio J. Melendez
PLOS ONE , 2012, DOI: 10.1371/journal.pone.0010506
Abstract: Tumor Necrosis Factor alpha (TNFα) is a pleiotropic cytokine extensively studied for its role in the pathogenesis of a variety of disease conditions, including in inflammatory diseases. We have recently shown that, in vitro, that TNFα utilizes PLD1 to mediate the activation of NFκB and ERK1/2 in human monocytes. The aim of this study was to investigate the role(s) played by phospholipase D1 (PLD1) in TNFα-mediated inflammatory responses in vivo.
Differential regulation of intracellular factors mediating cell cycle, DNA repair and inflammation following exposure to silver nanoparticles in human cells
PV AshaRani, Swaminathan Sethu, Hui Lim, Ganapathy Balaji, Suresh Valiyaveettil, M Prakash Hande
Genome Integrity , 2012, DOI: 10.1186/2041-9414-3-2
Abstract: We report that silver nanoparticles are capable of adsorbing cytosolic proteins on their surface that may influence the function of intracellular factors. Gene and protein expression profiles of Ag-np exposed cells revealed up regulation of many DNA damage response genes such as Gadd 45 in both the cell types and ATR in cancer cells. Moreover, down regulation of genes necessary for cell cycle progression (cyclin B and cyclin E) and DNA damage response/repair (XRCC1 and 3, FEN1, RAD51C, RPA1) was observed in both the cell lines. Double strand DNA damage was observed in a dose dependant manner as evidenced in γH2AX foci assay. There was a down regulation of p53 and PCNA in treated cells. Cancer cells in particular showed a concentration dependant increase in phosphorylated p53 accompanied by the cleavage of caspase 3 and PARP. Our results demonstrate the involvement of NFκB and MAP kinase pathway in response to Ag-np exposure. Up regulation of pro-inflammatory cytokines such as interleukins (IL-8, IL-6), macrophage colony stimulating factor, macrophage inflammatory protein in fibroblasts following Ag-np exposure were also observed.In summary, Ag-np can modulate gene expression and protein functions in IMR-90 cells and U251 cells, leading to defective DNA repair, proliferation arrest and inflammatory response. The observed changes could also be due to its capability to adsorb cytosolic proteins on its surface.Wide spread use of nanoparticles has increased the risk of nanoparticle induced toxic effects in the environment and in humans. The rate of exposure increased progressively over the years when engineered nanomaterials were extensively used in a variety of industries. Intentional manipulation of nanoparticle surfaces with biomolecules and chemicals to cater various applications resulted in nanomaterials with unforeseeable activity. Large scale production and improper waste disposal may elevate human exposure to them and subsequent accumulation of these nanomaterial
Thymoquinone Induces Telomere Shortening, DNA Damage and Apoptosis in Human Glioblastoma Cells
Resham Lal Gurung,Shi Ni Lim,Aik Kia Khaw,Jasmine Fen Fen Soon,Kirthan Shenoy,Safiyya Mohamed Ali,Manikandan Jayapal,Swaminathan Sethu,Rajamanickam Baskar,M. Prakash Hande
PLOS ONE , 2012, DOI: 10.1371/journal.pone.0012124
Abstract: A major concern of cancer chemotherapy is the side effects caused by the non-specific targeting of both normal and cancerous cells by therapeutic drugs. Much emphasis has been placed on discovering new compounds that target tumour cells more efficiently and selectively with minimal toxic effects on normal cells.
Medical and Health Science Journal , 2011,
Abstract: Small cell neuroendocrine carcinoma, also known as oat cell carcinoma is a frequently encountered bronchogenic neoplasm. Neuroendocrine carcinomas of the head and neck are rare aggressive tumors and pose a diagnostic and management challenge. Differentiation from conventional nasopharyngeal carcinoma is difficult due to morphological characteristics and small biopsy specimen. Distinguishing is very important because of difference in natural history ,prognosis and treatment among these neoplasms. In this article we present an unusual case of 51 year old man with small cell neuroendocrine carcinoma of nasopharynx, who was treated with radiotherapy and achieved complete tumor remission. Subsequently he developed local recurrence and liver metastasis and succumbed to the disease
The Induced Bounded-Degree Subgraph Problem and Stream Control in MIMO Networks
Harish Sethu
Computer Science , 2007,
Abstract: In this report, we consider maximal solutions to the induced bounded-degree subgraph problem and relate it to issues concerning stream control in multiple-input multiple-output (MIMO) networks. We present a new distributed algorithm that completes in logarithmic time with high probability and is guaranteed to complete in linear time. We conclude the report with simulation results that address the effectiveness of stream control and the relative impact of receiver overloading and flexible interference suppression.
Design and Testing of Biochar Stoves  [PDF]
Rajaram Swaminathan, Hileni Amupolo
Open Journal of Applied Sciences (OJAppS) , 2014, DOI: 10.4236/ojapps.2014.414056
Abstract: Biochar is a solid material obtained from the carbonization of biomass. Biochar is used on agricultural lands as a soil amendment to improve the fertility of the soils. Currently the most common method of producing biochar is through biochar stoves. There are two basic stove operations in the production of biochar. The first type of stove produces biochar by direct combustion of biomass. Here biomass is burnt inside a chamber in an oxygen limited environment. The resulting residue is the bio-char. The second type involves burning the biomass in one chamber and housing the biomass to be charred in the annular portion of an outer chamber. Heat is transferred from the burning fuel on the inner chamber to the material to be charred in the outer chamber. While the process of biochar production in these stoves is known, the basic principles of the stove design are not readily available. The design methodology for both the types was developed from first principles. Prototypes of both types were constructed based on the design developed and tested. The paper lists the basic principles in the design of biochar stoves and the test results.
Inactivation of Chk2 and Mus81 Leads to Impaired Lymphocytes Development, Reduced Genomic Instability, and Suppression of Cancer
Samah El Ghamrasni equal contributor,Ashwin Pamidi equal contributor,Marie Jo Halaby,Miyuki Bohgaki,Renato Cardoso,Li Li,Shriram Venkatesan,Swaminathan Sethu,Atsushi Hirao,Tak W. Mak,Manoor Prakash Hande,Anne Hakem ,Razqallah Hakem
PLOS Genetics , 2011, DOI: 10.1371/journal.pgen.1001385
Abstract: Chk2 is an effector kinase important for the activation of cell cycle checkpoints, p53, and apoptosis in response to DNA damage. Mus81 is required for the restart of stalled replication forks and for genomic integrity. Mus81Δex3-4/Δex3-4 mice have increased cancer susceptibility that is exacerbated by p53 inactivation. In this study, we demonstrate that Chk2 inactivation impairs the development of Mus81Δex3-4/Δex3-4 lymphoid cells in a cell-autonomous manner. Importantly, in contrast to its predicted tumor suppressor function, loss of Chk2 promotes mitotic catastrophe and cell death, and it results in suppressed oncogenic transformation and tumor development in Mus81Δex3-4/Δex3-4 background. Thus, our data indicate that an important role for Chk2 is maintaining lymphocyte development and that dual inactivation of Chk2 and Mus81 remarkably inhibits cancer.
Multisensory Oddity Detection as Bayesian Inference
Timothy Hospedales, Sethu Vijayakumar
PLOS ONE , 2009, DOI: 10.1371/journal.pone.0004205
Abstract: A key goal for the perceptual system is to optimally combine information from all the senses that may be available in order to develop the most accurate and unified picture possible of the outside world. The contemporary theoretical framework of ideal observer maximum likelihood integration (MLI) has been highly successful in modelling how the human brain combines information from a variety of different sensory modalities. However, in various recent experiments involving multisensory stimuli of uncertain correspondence, MLI breaks down as a successful model of sensory combination. Within the paradigm of direct stimulus estimation, perceptual models which use Bayesian inference to resolve correspondence have recently been shown to generalize successfully to these cases where MLI fails. This approach has been known variously as model inference, causal inference or structure inference. In this paper, we examine causal uncertainty in another important class of multi-sensory perception paradigm – that of oddity detection and demonstrate how a Bayesian ideal observer also treats oddity detection as a structure inference problem. We validate this approach by showing that it provides an intuitive and quantitative explanation of an important pair of multi-sensory oddity detection experiments – involving cues across and within modalities – for which MLI previously failed dramatically, allowing a novel unifying treatment of within and cross modal multisensory perception. Our successful application of structure inference models to the new ‘oddity detection’ paradigm, and the resultant unified explanation of across and within modality cases provide further evidence to suggest that structure inference may be a commonly evolved principle for combining perceptual information in the brain.
Continuous Evolution of Statistical Estimators for Optimal Decision-Making
Ian Saunders, Sethu Vijayakumar
PLOS ONE , 2012, DOI: 10.1371/journal.pone.0037547
Abstract: In many everyday situations, humans must make precise decisions in the presence of uncertain sensory information. For example, when asked to combine information from multiple sources we often assign greater weight to the more reliable information. It has been proposed that statistical-optimality often observed in human perception and decision-making requires that humans have access to the uncertainty of both their senses and their decisions. However, the mechanisms underlying the processes of uncertainty estimation remain largely unexplored. In this paper we introduce a novel visual tracking experiment that requires subjects to continuously report their evolving perception of the mean and uncertainty of noisy visual cues over time. We show that subjects accumulate sensory information over the course of a trial to form a continuous estimate of the mean, hindered only by natural kinematic constraints (sensorimotor latency etc.). Furthermore, subjects have access to a measure of their continuous objective uncertainty, rapidly acquired from sensory information available within a trial, but limited by natural kinematic constraints and a conservative margin for error. Our results provide the first direct evidence of the continuous mean and uncertainty estimation mechanisms in humans that may underlie optimal decision making.
The role of feed-forward and feedback processes for closed-loop prosthesis control
Ian Saunders, Sethu Vijayakumar
Journal of NeuroEngineering and Rehabilitation , 2011, DOI: 10.1186/1743-0003-8-60
Abstract: Healthy subjects were fitted with a closed-loop robotic hand and instructed to grasp and lift objects of different weights as we recorded trajectories and force profiles. We conducted three experiments under different feed-forward and feed-back configurations to elucidate the role of tactile feedback (i) in ideal conditions, (ii) under sensory deprivation, and (iii) under feed-forward uncertainty.(i) We found that subjects formed economical grasps in ideal conditions. (ii) To our surprise, this ability was preserved even when visual and tactile feedback were removed. (iii) When we introduced uncertainty into the hand controller performance degraded significantly in the absence of either visual or tactile feedback. Greatest performance was achieved when both sources of feedback were present.We have introduced a novel method to understand the cognitive processes underlying grasping and lifting. We have shown quantitatively that tactile feedback can significantly improve performance in the presence of feed-forward uncertainty. However, our results indicate that feed-forward and feed-back mechanisms serve complementary roles, suggesting that to improve on the state-of-the-art in prosthetic hands we must develop prostheses that empower users to correct for the inevitable uncertainty in their feed-forward control.For many decades researchers have considered the possibility of 'closing the loop' for upper-limb prosthesis wearers. Historically, feedback has been added to increase patient confidence [1] and to improve object grasping and lifting [2,3]. In the future we may see prosthetic hands that integrate directly with the amputee's nervous system, utilising state-of-the-art sensor technology [4,5] and relying on pioneering medical procedures [6-8]. Nevertheless, state-of-the-art upper limb prostheses are still open-loop devices with limited degrees of control, described as "clumsy" [9] and requiring considerable mental effort [10]. As technology continues to advance it i
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