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Search Results: 1 - 10 of 325918 matches for " Vinita S Chauhan "
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Exacerbated metastatic disease in a mouse mammary tumor model following latent gammaherpesvirus infection
Vinita S Chauhan, Daniel A Nelson, Lopamudra Das Roy, Pinku Mukherjee, Kenneth L Bost
Infectious Agents and Cancer , 2012, DOI: 10.1186/1750-9378-7-11
Abstract: Mice latently infected with HV-68 had a similar primary tumor burden, but much greater metastatic disease, when compared to mock treated mice given the transplantable tumor, 4?T1. This was true for lung lesions, as well as secondary tumor masses. Increased expression of pan-cytokeratin and VEGF-A in tumors from HV-68 infected mice was consistent with increased metastatic disease in these animals. Surprisingly, no viral particles could be cultured from tumor tissues, and the presence of viral DNA or RNA transcripts could not be detected in primary or secondary tumor tissues.Latent HV-68 infection had no significant effect on the size of primary 4?T1 mammary tumors, but exacerbated the number of metastatic lung lesions and secondary tumors when compared to mock treated mice. Increased expression of the tumor marker, pan-cytokeratin, and VEGF-A in tumors of mice harboring latent virus was consistent with an exacerbated metastatic disease. Mechanisms responsible for this exacerbation are indirect, since no virus could be detected in cancerous tissues.
Murine gammaherpesvirus-68 expands, but does not activate, CD11b+ gr-1+ splenocytes in vivo
Daniel A Nelson, Vinita S Chauhan, Melanie D Tolbert, Kenneth L Bost
Journal of Inflammation , 2012, DOI: 10.1186/1476-9255-9-14
Abstract: Mice were infected with HV-68, with viral latency being established in these animals. At varying times post-infection, cells were isolated for detection of viral genomes, phenotyping of myeloid cell populations, and ex vivo analysis of suppressor activity of myeloid cells.CD11b?+?Gr-1+ myeloid cells accumulated in the spleens, but not the bone marrow, of HV-68 infected mice. These cells were predominantly Gr-1+ Ly-6?G+, and could be found to contain viral genomes. Increased levels of serum S100A8/A9 produced during viral infection were consistent with the expansion of these CD11b?+?Gr-1+ myeloid cells. Despite their expansion, these cells exhibited no increased arginase 1 or iNOS activity, and did not have the ability to suppress anti-CD3 antibody activated T lymphocyte responses.We concluded that HV-68 infection was capable of expanding a population of myeloid cells which were phenotypically similar to MDSC. However these cells were not sufficiently activated during the establishment of viral latency to actively suppress T cell responses.
A role for DNA-dependent activator of interferon regulatory factor in the recognition of herpes simplex virus type 1 by glial cells
Samantha R Furr, Vinita S Chauhan, Megan J Moerdyk-Schauwecker, Ian Marriott
Journal of Neuroinflammation , 2011, DOI: 10.1186/1742-2094-8-99
Abstract: Expression of DAI and its downstream effector molecules was determined in C57BL/6-derived microglia and astrocytes, either at rest or following exposure to herpes simplex virus type 1 (HSV-1) and/or murine gammaherpesvirus-68 (MHV-68), by immunoblot analysis. In addition, such expression was studied in ex vivo microglia/macrophages and astrocytes from uninfected animals or mice infected with HSV-1. Inflammatory cytokine production by glial cultures following transfection with a DAI specific ligand (B-DNA), or following HSV-1 challenge in the absence or presence of siRNA directed against DAI, was assessed by specific capture ELISA. The production of soluble neurotoxic mediators by HSV-1 infected glia following DAI knockdown was assessed by analysis of the susceptibility of neuron-like cells to conditioned glial media.We show that isolated microglia and astrocytes constitutively express DAI and its effector molecules, and show that such expression is upregulated following DNA virus challenge. We demonstrate that these resident CNS cells express DAI in situ, and show that its expression is similarly elevated in a murine model of HSV-1 encephalitis. Importantly, we show B-DNA transfection can elicit inflammatory cytokine production by isolated glial cells and DAI knockdown can significantly reduce microglial and astrocyte responses to HSV-1. Finally, we demonstrate that HSV-1 challenged microglia and astrocytes release neurotoxic mediators and show that such production is significantly attenuated following DAI knockdown.The functional expression of DAI by microglia and astrocytes may represent an important innate immune mechanism underlying the rapid and potentially lethal inflammation associated with neurotropic DNA virus infection.The neurotropic DNA virus herpes simplex virus type 1 (HSV-1) is capable of causing severe necrotizing encephalitis and accounts for 95% of all fatal cases of sporadic viral encephalitis [1]. Untreated HSV-1 encephalitis has a 70% mortality
An expanded myeloid derived suppressor cell population does not play a role in gammaherpesvirus-exacerbated breast cancer metastases
Nelson Daniel A,Chauhan Vinita S,Tolbert Melanie D,Bost Kenneth L
Infectious Agents and Cancer , 2012, DOI: 10.1186/1750-9378-7-22
Abstract: Background Mice latently infected with murine gammaherpesvirus 68 (HV-68) and transplanted with 4 T1 breast cancer cells developed exacerbated metastatic lesions when compared to controls. The mechanisms responsible for this viral-exacerbated disease were not clear. The ability of HV-68 infection to induce S100A8 and S100A9 production and to expand a population of CD11b+Gr-1+ cells suggested that increased numbers, or activity, of viral-expanded myeloid derived suppressor cells (MDSCs) might contribute to HV-68-associated metastatic breast cancer in this model. We questioned whether mock or HV-68 infected mice with significant breast cancer might have differences in the number and/or activity of MDSCs. Methods Myeloid-derived macrophages and dendritic cells were isolated from normal mice and cultured in vitro with HV-68 to assess S100A8 and S100A9 mRNA and protein expression. In vivo studies were performed using groups of mice that were mock treated or infected with HV-68. After viral latency was established, 4 T1 breast cancer cells were transplanted in mice. When primary breast tumors were present mice were euthanized and cells isolated for phenotyping of myeloid cell populations using FACS, and for ex vivo analysis of suppressor activity. Serum from these animals was also collected to quantify S100A8 and S100A9 levels. Results In vitro studies demonstrated that direct exposure of myeloid cells to HV-68 did not induce increased expression of S100A8 or S100A9 mRNAs or secreted protein. HV-68 infected mice with metastatic breast cancer disease had no increases in S100A8/A9 levels and no significant increases in the numbers or activation of CD11b+Gr-1+MDSCs when compared to mock treated mice with breast cancer. Conclusions Together these studies are consistent with the notion that expanded myeloid derived suppressor cells do not play a role in gammaherpesvirus-exacerbated breast cancer metastases. The mechanisms responsible for HV-68 induced exacerbation of metastatic breast cancer remain unclear.
Rice Husk Biochar Influences Seedling Emergence of Junglerice (Echinochloa colona) and Herbicide Efficacy  [PDF]
Bhagirath S. Chauhan
American Journal of Plant Sciences (AJPS) , 2013, DOI: 10.4236/ajps.2013.47164

The use of carbonized rice husk biochar improves the fertility and productivity of poor soils in rice-based cropping systems. However, biochar may also influence weed seedling emergence and the efficacy of soil-applied herbicides. Experiments were conducted in a screenhouse to evaluate the effect of biochar rates (0, 20, 40, and 80 t·ha?1) and seed burial depth (0, 1, and 2 cm) on seedling emergence of junglerice (Echinochloa colona) and the effect of biochar rates and pendimethalin (0, 500, 1000, and 1500 g·a.i.·ha?1) and pretilachlor doses (0, 300, 600, and 900 g·a.i.·ha?1) on seedling emergence and seedling biomass of junglerice. Data were analyzed using nonlinear regression. The burial depth to inhibit 50% of maximum seedling emergence was 0.76 cm when biochar was not added to soil and the depth increased with an increase in biochar rates for soil. Similarly, compared with the soil with no biochar, the use of bichoar increased the pretilachlor dose to inhibit 50% of maximum emergence or biomass. The pretilachlor dose to inhibit 50% of maximum biomass of junglerice was 100, 130, 240, and

Machinability Study of Titanium (Grade-5) Alloy Using Design of Experiment Technique  [PDF]
Kali Dass, S. R Chauhan
Engineering (ENG) , 2011, DOI: 10.4236/eng.2011.36073
Abstract: This paper presents the findings of an experimental investigation into the effects of cutting speed, feed rate, depth of cut and approach angle in turning of titanium (Grade 5) alloy. A two-level factorial experiment has been used to accomplish the objective of the experimental study. The main cutting force, i.e. tangential force (Fc) and surface roughness (Ra) were the response variables investigated. The experimental results indicate that the proposed mathematical models suggested could adequately describe the performance indicators within the limits of the factors that are being investigated. The feed, cutting speed and depth of cut is the most significant factor that influences the surface roughness and the tangential force. However, there are other factors that provide secondary contributions to the performance indicators.
Amperometric Determination of Serum Cholesterol with Pencil Graphite Rod  [PDF]
Nidhi Chauhan, Jagriti Narang, Chandra S. Pundir
American Journal of Analytical Chemistry (AJAC) , 2010, DOI: 10.4236/ajac.2010.12006
Abstract: A cholesterol oxidase from Streptomycin sp. was immobilized onto pencil graphite rod and employed for amperometric determination of serum cholesterol. The method has the advantage over earlier amperometric methods that it requires low potential to generate electrons from H2O2, which does not allow ionization of serum substances. The optimum working conditions of amperometric determination were pH 6.8, 25?C and 30 s. The current measured was in proportion to cholesterol concentration ranging from 1.29×10-3 to 10.33×10-3 M. Minimum detection limit of the method was 0.09 ×10-3 M. Mean analytical recovery of added cholesterol (100 mg/dl and 200 mg/dl) in serum was 85.0% & 90.0% respectively. Within batch and between batch coefficients of variations were 1.59% & 4.15% respectively. A good correlation (r = 0.99) was obtained between serum cholesterol values by standard enzymic colorimetric method and the present method. No interference by metabolites was observed in the method. The enzyme electrode was reused 200 times over a period of 25 days, when stored at 4?C
Voltage Mode Cascadable AllPass Sections Using Single Active Element and Grounded Passive Components  [PDF]
Jitendra Mohan, Sudhanshu Maheshwari, Durg S. Chauhan
Circuits and Systems (CS) , 2010, DOI: 10.4236/cs.2010.11002
Abstract: In this paper, four new first order voltage mode cascadable allpass sections are proposed using single active element and three grounded passive components, ideal for IC implementation. The active element used is a fully differential current conveyor. All the proposed circuit possess high input and low output impedance feature which is a desirable feature for voltagemode circuits. Nonideality aspects and parasitic effects are also given. As an application, a multiphase oscillator is designed. The proposed circuits are verified through PSPICE simulation results using TSMC 0.35 µm CMOS parameters.
Fertilizer Placement Affects Weed Growth and Grain Yield in Dry-Seeded Rice (Oryza sativa L.) Systems  [PDF]
Bhagirath S. Chauhan, Seth B. Abugho
American Journal of Plant Sciences (AJPS) , 2013, DOI: 10.4236/ajps.2013.46155

A study was conducted in a split-plot design to evaluate the effect of fertilizer placement method on weed growth and grain yield in a dry-seeded rice (DSR) system. Main-plot treatments were four fertilizer placement methods: between narrow rows (between 15-cm-wide rows of the pattern 25-15-25 cm), between uniform rows (between 20-cm-wide rows), within uniform rows, and surface broadcast. Subplot treatments were three weed control methods: herbicide-treated, nontreated, and weed-free. Weed biomass was greater in the nontreated plots than in the herbicide-treated plots. Herbicide application reduced weed biomass by 89% to 99% compared with the nontreated control. Fertilizer placement did not influence weed biomass in the herbicide-treated plots; however, it greatly influenced biomass in the nontreated plots. Fertilizer placement on the surface increased weed biomass (69 -71 g·m2) compared with the placement of fertilizer below the soil surface (37 -57 g·m–2). Fertilizer placement did not influence weed density and biomass at 60 days after planting. Nontreated plots yielded 700 to 2080 kg·ha–1. Grain yield was similar between the herbicide-treated (2660-3250 kg

Effect of Water Stress on the Growth and Development of Amaranthus spinosus, Leptochloa chinensis, and Rice  [PDF]
Bhagirath S. Chauhan, Seth B. Abugho
American Journal of Plant Sciences (AJPS) , 2013, DOI: 10.4236/ajps.2013.45122

Drought is the most important abiotic constraint in rainfed rice systems. In these systems, Amaranthus spinosus and Leptochloa chinensis are the dominant weed species, which may reduce the available water to rice by competition and cause water stress in the crop. Two studies were conducted in a greenhouse to evaluate the growth response of A. spinosus and rice and L. chinensis and rice to water stress. The water stress treatments were 12.5%, 25%, 50%, 75%, and 100% of field capacity and the plants were grown until weed maturity (i.e., 63 days from seeding). Rice plants did not survive at 12.5% and 25% of field capacity, but both weed species survived in all the treatments. Both weed species produced a significant

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