The Experts below are selected from a list of 294 Experts worldwide ranked by ideXlab platform
Richard H. Gomer - One of the best experts on this subject based on the ideXlab platform.
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Cell Density sensing and size determination.
Development growth & differentiation, 2011Co-Authors: Richard H. Gomer, Wonhee Jang, Derrick BrazillAbstract:The social amoeba Dictyostelium discoideum is one of the leading model systems used to study how Cells count themselves to determine the number and/or Density of Cells. In this review, we describe work on three different Cell-Density sensing systems used by Dictyostelium. The first involves a negative feedback loop in which two secreted signals inhibit Cell proliferation during the growth phase. As the Cell Density increases, the concentrations of the secreted factors concomitantly increase, allowing the Cells to sense their Density. The two signals act as message authenticators for each other, and the existence of two different signals that require each other for activity may explain why previous efforts to identify autocrine proliferation-inhibiting signals in higher eukaryotes have generally failed. The second system involves a signal made by growing Cells that is secreted only when they starve. This then allows Cells to sense the Density of just the starving Cells, and is an example of a mechanism that allows Cells in a tissue to sense the Density of one specific Cell type. The third Cell Density counting system involves Cells in aggregation streams secreting a signal that limits the size of fruiting bodies. Computer simulations predicted, and experiments then showed, that the factor increases random Cell motility and decreases Cell-Cell adhesion to cause streams to break up if there are too many Cells in the stream. Together, studies on Dictyostelium Cell Density counting systems will help elucidate how higher eukaryotes regulate the size and composition of tissues.
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Cell-Density sensing: Come on inside and tell us about it
Current biology : CB, 1997Co-Authors: Richard H. GomerAbstract:The developmental pathway chosen by a Bacillus subtilis Cell is influenced by the local Cell Density. To sense Cell Density, the Cell monitors at least three different secreted signal peptides, two of which are detected by a new type of transduction mechanism involving their specific transport into the Cell.
Derrick Brazill - One of the best experts on this subject based on the ideXlab platform.
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Cell Density sensing and size determination.
Development growth & differentiation, 2011Co-Authors: Richard H. Gomer, Wonhee Jang, Derrick BrazillAbstract:The social amoeba Dictyostelium discoideum is one of the leading model systems used to study how Cells count themselves to determine the number and/or Density of Cells. In this review, we describe work on three different Cell-Density sensing systems used by Dictyostelium. The first involves a negative feedback loop in which two secreted signals inhibit Cell proliferation during the growth phase. As the Cell Density increases, the concentrations of the secreted factors concomitantly increase, allowing the Cells to sense their Density. The two signals act as message authenticators for each other, and the existence of two different signals that require each other for activity may explain why previous efforts to identify autocrine proliferation-inhibiting signals in higher eukaryotes have generally failed. The second system involves a signal made by growing Cells that is secreted only when they starve. This then allows Cells to sense the Density of just the starving Cells, and is an example of a mechanism that allows Cells in a tissue to sense the Density of one specific Cell type. The third Cell Density counting system involves Cells in aggregation streams secreting a signal that limits the size of fruiting bodies. Computer simulations predicted, and experiments then showed, that the factor increases random Cell motility and decreases Cell-Cell adhesion to cause streams to break up if there are too many Cells in the stream. Together, studies on Dictyostelium Cell Density counting systems will help elucidate how higher eukaryotes regulate the size and composition of tissues.
Junhong Yang - One of the best experts on this subject based on the ideXlab platform.
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Effects of Light and pH on Cell Density of Chlorella Vulgaris
Energy Procedia, 2014Co-Authors: Qitao Gong, Yuanzheng Feng, Ligai Kang, Mengyuan Luo, Junhong YangAbstract:Abstract Improving the Cell Density of microalgae cultivation is one of the keys to reduce the cost of microalgae biodiesel. Many studies showed that the adjustment of pH and light intensity could increase Cell Density. The effects of light intensities, pH and pH adjustments on the growth of Chlorella vulgaris were studied in light incubator. The light intensities were set at 3960, 7920 and 11920lux; values of pH were 7, 8, 9 and 10 respectively; and pH adjustment methods included without and with pH control. Results show that: (1) In terms of light intensity, without pH control, the Cell Density under 3960lux is highest. With pH control, the Cell Density under 7920lux is higher than other levels. (2) In terms of pH, under the same light intensity, the Cell Density with pH control at 10 is highest, which indicates the light intensity will not affect the optimal pH value. And the pH fluctuates between 10 and 10.5 with pH control at 10, which is the most suitable range of pH for Chlorella vulgaris cultivation. (3) For pH adjustment methods, under 7920lux, the Cell Density with pH control at 10.0 is 56.7% higher than that with initial pH at 10.0, while the Cell Density with initial pH at 7.0 is 34.7% than that with pH control at 7.0, which indicates the method with pH control at values of the optimum pH makes better growth of microalgae.
Hava Gil-henn - One of the best experts on this subject based on the ideXlab platform.
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Tumor Cell Density regulates matrix metalloproteinases for enhanced migration.
Oncotarget, 2018Co-Authors: Hasini Jayatilaka, Fatima G. Umanzor, Vishwesh Shah, Tomer Meirson, Gabriella C. Russo, Bartholomew Starich, Pranay Tyle, Jerry S.h. Lee, Shyam B. Khatau, Hava Gil-hennAbstract:Matrix metalloproteinases (MMPs) may play a critical role in metastatic cancers, yet multiple human clinical trials targeting MMPs have surprisingly failed. Cancer Cell Density changes dramatically during the early growth of a primary tumor and during the early seeding steps of secondary tumors and has been implicated in playing an important role in regulating metastasis and drug resistance. This study reveals that the expression of MMPs is tightly regulated by local tumor Cell Density through the synergistic signaling mechanism of Interleukin 6 (IL-6) and Interleukin 8 (IL-8) via the JAK2/STAT3 complex. Local tumor Cell Density also plays a role in the responsiveness of Cells to matrix metalloproteinases inhibitors (MMPI), such as Batimastat, Marimastat, Bryostatin I, and Cipemastat, where different migratory phenotypes are observed in low and high Cell Density conditions. Cell Density-dependent MMP regulation can be directly targeted by the simultaneous inhibition of IL-6 and IL-8 receptors via Tocilizumab and Reparixin to significantly decrease the expression of MMPs in mouse xenograft models and decrease effective metastasis. This study reveals a new strategy to decrease MMP expression through pharmacological intervention of the cognate receptors of IL-6 and IL-8 to decrease metastatic capacity of tumor Cells.
Lajean W Chaffin - One of the best experts on this subject based on the ideXlab platform.
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role for Cell Density in antifungal drug resistance in candida albicans biofilms
Antimicrobial Agents and Chemotherapy, 2007Co-Authors: Palani Perumal, Satish Mekala, Lajean W ChaffinAbstract:Biofilms of Candida albicans are less susceptible to many antifungal drugs than are planktonic yeast Cells. We investigated the contribution of Cell Density to biofilm phenotypic resistance. Planktonic yeast Cells in RPMI 1640 were susceptible to azole-class drugs, amphotericin B, and caspofungin at 1 x 10(3) Cells/ml (standard conditions) using the XTT [2,3-bis(2-methoxy-4-nitro-5-sulfophenyl)-2H-tetrazolium-5-carboxanilide sodium salt] assay. As reported by others, as the Cell concentration increased to 1 x 10(8) Cells/ml, resistance was observed with 10- to 20-fold-greater MICs. Biofilms that formed in microtiter plate wells, like high-Density planktonic organisms, were resistant to drugs. When biofilms were resuspended before testing, phenotypic resistance remained, but organisms, when diluted to 1 x 10(3) Cells/ml, were susceptible. Drug-containing medium recovered from high-Cell-Density tests inhibited low-Cell-Density organisms. A fluconazole-resistant strain showed greater resistance at high planktonic Cell Density, in biofilm, and in resuspended biofilm than did low-Density planktonic or biofilm organisms. A strain lacking drug efflux pumps CDR1, CDR2, and MDR1, while susceptible at a low azole concentration, was resistant at high Cell Density and in biofilm. A strain lacking CHK1 that fails to respond to the quorum-sensing molecule farnesol had the same response as did the wild type. FK506, reported to abrogate tolerance to azole drugs at low Cell Density, had no effect on tolerance at high Cell Density and in biofilm. These observations suggested that Cell Density has a role in the phenotypic resistance of biofilm, that neither the drug efflux pumps tested nor quorum sensing through Chk1p contributes to resistance, and that azole drug tolerance at high Cell Density differs mechanistically from tolerance at low Cell Density.