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Cell Growth Rate (cell + growth_rate)
Selected AbstractsMicrotubule-interacting drugs induce moderate and reversible damage to human bone marrow mesenchymal stem cellsCELL PROLIFERATION, Issue 4 2009H. Polioudaki Objectives:, This study aimed to investigate molecular and cellular changes induced in human bone marrow mesenchymal stem cells (hMSCs) after treatment with microtubule-interacting agents and to estimate damage to the bone marrow microenvironment caused by chemotherapy. Materials and methods:, Using an in vitro hMSC culture system and biochemical and morphological approaches, we studied the effect of nocodazole and taxol® on microtubule and nuclear envelope organization, tubulin and p53 synthesis, cell cycle progression and proliferation and death of hMSCs isolated from healthy donors. Results and conclusions:, Both nocodazole and taxol reduced hMSC proliferation and induced changes in the microtubular network and nuclear envelope morphology and organization. However, they exhibited only a moderate effect on cell death and partial arrest of hMSCs at G2 but not at M phase of the cell cycle. Both agents induced expression of p53, exclusively localized in abnormally shaped nuclei, while taxol, but not nocodazole, increased synthesis of ,-tubulin isoforms. Cell growth rates and microtubule and nuclear envelope organization gradually normalized after transfer, in drug-free medium. Our data indicate that microtubule-interacting drugs reversibly inhibit proliferation of hMSCs; additionally, their cytotoxic action and effect on microtubule and nuclear envelope organization are moderate and reversible. We conclude that alterations in human bone marrow cells of patients under taxol chemotherapy are transient and reversible. [source] Analysis of glutathione endpoints for measuring copper stress in Chlamydomonas reinhardthENVIRONMENTAL TOXICOLOGY & CHEMISTRY, Issue 8 2007Tasha L. Stoiber Abstract Glutathione (GSH) is the most abundant nonprotein thiol in eukaryotic cells and it protects cells by functioning as an antioxidant and a metal-binding ligand. Because glutathione readily undergoes oxidation-reduction reactions to combat oxidative stress, intracellular ratios of the reduced (GSH) to the oxidized (GSSG) forms of glutathione may serve as an important biomarker of exposure and effect of trace metals in eukaryotic cells. We compared sensitivity of glutathione ratios in the freshwater alga Chlamydomonas reinhardtii to the traditional endpoints of cell growth rates and chlorophyll a following exposure to Cu for periods of 6 and 24 h. A response of the GSH:GSSG ratio to Cu concentration was observed at Cu levels of 40 and 80 nM after exposure for both 6 and 24 h. The concentration of total GSH at 24 h was roughly half the value at 6 h after exposure to either 40 or 80 nM Cu. A response for cell growth rate was observed only at 24 h, whereby the average specific growth rate decreased from about 1.1 to 0.4 d,1. The total Cu concentrations eliciting a cell response of 50%, effect concentrations (EC50s), after 24 h of exposure were similar (49.2, 49.8, and 38.2 nM Cu) and not significantly different for GSH:GSSG ratio, GSH levels, and specific growth, respectively. Total cell-associated Cu concentrations after exposure for 24 h were calculated from the EC50 endpoints and ranged from 13.3 to 17.0 fg/cell. Overall, thiol ratios were indicative of toxicity resulting from exposure to Cu, but precision may be greater for the cell growth rate endpoints. [source] Escherichia coli tRNase Z can shut down growth probably by removing amino acids from aminoacyl-tRNAsGENES TO CELLS, Issue 11 2008Hiroaki Takaku In most organisms, tRNase Z is considered to be essential for 3, processing of tRNA molecules. The Escherichia coli tRNase Z gene, however, appears to be dispensable under normal growth conditions, and its existence remained an enigma. Here we intensively examined various (pre-)tRNAs for good substrates of E. coli tRNase Z in vitro, and found that the enzyme can remove the 3, terminal CCA residues from mature tRNAs regardless of their nucleotide modifications. Furthermore, we discovered that E. coli tRNase Z, when sufficiently expressed in the cell, can shut down growth probably by removing amino acids from aminoacyl-tRNAs. We confirmed in vitro that E. coli tRNase Z exceptionally possesses the activity that cleaves off the 3, terminal residues charging an amino acid from an aminoacyl-tRNA molecule. The current data suggest that tRNase Z might help modulate a cell growth rate by repressing translation under some stressful conditions. [source] Inhibition of human vascular endothelial cells proliferation by terbinafineINTERNATIONAL JOURNAL OF CANCER, Issue 1 2004Pei-Yin Ho Abstract We have demonstrated previously that terbinafine (TB), an oral antifungal agent used in the treatment of superficial mycosis, suppresses proliferation of various cultured human cancer cells in vitro and in vivo by inhibiting DNA synthesis and activating apoptosis. In our study, we further demonstrated that TB at a range of concentrations (0,120 ,M) dose-dependently decreased cell number in cultured human umbilical vascular endothelial cells (HUVEC). Terbinafine was not cytotoxic at a concentration of 120 ,M, indicating that it may have an inhibitory effect on the cell proliferation in HUVEC. The TB-induced inhibition of cell growth rate is reversible. [3H]thymidine incorporation revealed that TB reduced the [3H]thymidine incorporation into HUVEC during the S-phase of the cell-cycle. Western blot analysis demonstrated that the protein levels of cyclin A, but not cyclins B, D1, D3, E, CDK2 and CDK4, decreased after TB treatment. The TB-induced cell-cycle arrest in HUVEC occurred when the cyclin-dependent kinase 2 (CDK2) activity was inhibited just as the protein level of p21 was increased and cyclin A was decreased. Pretreatment of HUVEC with a p21 specific antisense oligonucleotide reversed the TB-induced inhibition of [3H]thymidine incorporation. Taken together, these results suggest an involvement of the p21-associated signaling pathway in the TB-induced antiproliferation in HUVEC. Capillary-like tube formation and chick embryo chorioallantoic membrane (CAM) assays further demonstrated the anti-angiogenic effect of TB. These findings demonstrate for the first time that TB can inhibit the angiogenesis. © 2004 Wiley-Liss, Inc. [source] Effects of temperature, ammonium and glucose concentrations on yeast growth in a model wine systemINTERNATIONAL JOURNAL OF FOOD SCIENCE & TECHNOLOGY, Issue 10 2006Daniela D'Amato Summary In enology, alcoholic fermentation is a complex process involving several mechanisms. Slow and incomplete alcoholic fermentation is a chronic problem for the wine industry and factors leading to sluggish and stuck fermentations have been extensively studied and reviewed. The most studied cause of sluggish and stuck fermentation is the nitrogen content limitation. Nevertheless, other factors, such as temperature of fermentation and sugar concentration can affect the growth of yeasts. In this study we modelled the yeast growth-cycle in wine model system as a function of temperature, sugar and ammonium concentrations; the individual effects and the interaction of these factors were analysed by means of a quadratic response surface methodology. Cell concentrations and weight loss were monitored in the whole wine fermentation process. The results of central composite design show that lower is the availability of nitrogen, higher is the cell growth rate; moreover, initial nitrogen concentration also influences survival time of Saccharomyces cerevisiae. [source] Cultured epithelial cells response to phototherapy with low intensity laser,LASERS IN SURGERY AND MEDICINE, Issue 4 2007Fernanda P. Eduardo PhD Abstract Background and Objectives Little is known about the intracellular response of epithelial cells to phototherapy. The aim of this in vitro study was to analyze the effect of phototherapy with low-energy lasers with different wavelengths and powers on cultured epithelial cell growth under different nutritional conditions. Study Design/Materials and Methods Epithelial cell cultures (Vero cell line) grown in nutritional deficit in culture medium supplemented with 2% fetal bovine serum (FBS) were irradiated with low-energy laser from one to three times with a GaAlAs laser (660 nm) and InGaAlP (780 nm), 40 and 70 mW, respectively, with 3 or 5 J/cm2. Cell growth was indirectly assessed by measuring the cell mitochondrial activity. Results Nonirradiated cell cultures grown in nutritional regular medium supplemented with 10% FBS produced higher cell growth than all cultures grown in nutritional deficit irradiated or not. The overall cell growth of cultures grown under nutritionally deficit conditions was significantly improved especially when irradiated with 780 nm for three times. Conclusions Phototherapy with the laser parameters tested increases epithelial cell growth rate for cells stressed by growth under nutritionally deficient states. This cell growth improvement is directly proportional to the number of irradiations; however, was not enough to reach the full cell growth potential rate of Vero epithelial cell line observed when growing under nutritional regular condition. Lasers Surg. Med. 39: 365,372, 2007. © 2007 Wiley-Liss, Inc. [source] Dynamic analysis of GS-NS0 cells producing a recombinant monoclonal antibody during fed-batch cultureBIOTECHNOLOGY & BIOENGINEERING, Issue 2 2007Scott H. Stansfield Abstract In this study we have analyzed the dynamic covariation of the mammalian cell proteome with respect to functional phenotype during fed-batch culture of NS0 murine myeloma cells producing a recombinant IgG4 monoclonal antibody. GS-NS0 cells were cultured in duplicate 10 L bioreactors (36.5°C, 15% DOT, pH 7.0) for 335 h and supplemented with a continuous feed stream after 120 h. Cell-specific growth rate declined continuously after 72 h of culture. Cell-specific recombinant monoclonal antibody production rate (qP) varied sixfold through culture. Whilst qP correlated with relative recombinant heavy chain mRNA abundance up to 216 h, qP subsequently declined, independent of recombinant heavy chain or light chain mRNA abundance. GS-NS0 cultures were sampled at 48 h intervals between 24 and 264 h of culture for proteomic analyses. Total protein abundance and nascent polypeptide synthesis was determined by 2D PAGE of unlabeled proteins visualized by SYPRO® Ruby and autoradiography of 35S-labeled polypeptides, respectively. Covariation of nascent polypeptide synthesis and abundance with biomass-specific cell growth, glucose and glutamate consumption, lactate and Mab production rates were then examined using two partial least squares regression models. Most changes in polypeptide synthesis or abundance for proteins previously identified by mass spectrometry were positively correlated with biomass-specific growth rate. We conclude that the substantial transitions in cell physiology and qP that occur during culture utilize a relatively constant complement of the most abundant host cell machines that vary primarily with respect to induced changes in cell growth rate. Biotechnol. Bioeng. 2007;97: 410,424. © 2006 Wiley Periodicals, Inc. [source] Metabolism of PER.C6TM cells cultivated under fed-batch conditions at low glucose and glutamine levelsBIOTECHNOLOGY & BIOENGINEERING, Issue 1 2006Luis Maranga Abstract This is the first study to examine PER.C6TM cell glucose/energy and glutamine metabolism with fed-batch cultures at controlled low glutamine, low glucose, and simultaneous low glucose and low glutamine levels. PER.C6TM cell metabolism was investigated in serum-free suspension bioreactors at two-liter scale. Control of glucose and/or glutamine concentrations had a significant effect on cellular metabolism leading to an increased efficiency of nutrient utilization, altered byproduct synthesis, while having no effect on cell growth rate. Cultivating cells at a controlled glutamine concentration of 0.25 mM reduced qGln and q by approximately 30%, qAla 85%, and qNEAA 50%. The fed-batch control of glutamine also reduced the overall accumulation of ammonium ion by approximately 50% by minimizing the spontaneous chemical degradation of glutamine. No major impact upon glucose/energy metabolism was observed. Cultivating cells at a glucose concentration of 0.5 mM reduced qGlc about 50% and eliminated lactate accumulation. Cells exhibited a fully oxidative metabolism with Y of approximately 6 mol/mol. However, despite no increase in qGln, an increased ammonium ion accumulation and Y were also observed. Effective control of lactate and ammonium ion accumulation by PER.C6TM cells was achieved using fed-batch with simultaneously controlled glucose and glutamine. A fully oxidative glucose metabolism and a complete elimination of lactate production were obtained. The qGln value was again reduced and, despite an increased q compared with batch culture, ammonium ion levels were typically lower than corresponding ones in batch cultures, and the accumulation of non-essential amino acids (NEAA) was reduced about 50%. In conclusion, this study shows that PER.C6TM cell metabolism can be confined to a state with improved efficiencies of nutrient utilization by cultivating cells in fed-batch at millimolar controlled levels of glucose and glutamine. In addition, PER.C6TM cells fall into a minority category of mammalian cell lines for which glutamine plays a minor role in energy metabolism. © 2006 Wiley Periodicals, Inc. [source] Enhanced cutinase production with Thermobifida fusca by two-stage pH control strategyBIOTECHNOLOGY JOURNAL, Issue 3 2007Guo-cheng Du Abstract A mutant of Thermobifida fusca ATCC 27730 was used for cutinase production. Acetate was the most suitable carbon source for cell growth and cutinase production compared with others. The pH was one of the most important factors affecting cutinase yield and productivity. Batch cutinase fermentations by mutant Thermobifida fusca WSH04 at various pH values ranging from 7.0 to 7.9 were studied. Based on the effects of different pH values on the specific cell growth rate and specific cutinase formation rate, a two-stage pH control strategy was developed, in which the pH was set at 7.3 for the first 20 h, and switched to 7.6 afterwards. By applying this two-stage pH control strategy for cutinase fermentation, the maximal cutinase activity reached 19.8 U/mL. [source] Feed development for fed-batch CHO production process by semisteady state analysisBIOTECHNOLOGY PROGRESS, Issue 3 2010Sarwat F. Khattak Abstract Semisteady state cultures are useful for studying cell physiology and facilitating media development. Two semisteady states with a viable cell density of 5.5 million cells/mL were obtained in CHO cell cultures and compared with a fed-batch mode control. In the first semisteady state, the culture was maintained at 5 mM glucose and 0.5 mM glutamine. The second condition had threefold higher concentrations of both nutrients, which led to a 10% increase in lactate production, a 78% increase in ammonia production, and a 30% reduction in cell growth rate. The differences between the two semisteady states indicate that maintaining relatively low levels of glucose and glutamine can reduce the production of lactate and ammonia. Specific amino acid production and consumption indicated further metabolic differences between the two semisteady states and fed-batch mode. The results from this experiment shed light in the feeding strategy for a fed-batch process and feed medium enhancement. The fed-batch process utilizes a feeding strategy whereby the feed added was based on glucose levels in the bioreactor. To evaluate if a fixed feed strategy would improve robustness and process consistency, two alternative feeding strategies were implemented. A constant volume feed of 30% or 40% of the initial culture volume fed over the course of cell culture was evaluated. The results indicate that a constant volumetric-based feed can be more beneficial than a glucose-based feeding strategy. This study demonstrated the applicability of analyzing CHO cultures in semisteady state for feed enhancement and continuous process improvement. © 2009 American Institute of Chemical Engineers Biotechnol. Prog., 2010 [source] Nonlinear Dynamics of Regulation of Bacterial trpOperon: Model Analysis of Integrated Effects of Repression, Feedback Inhibition, and AttenuationBIOTECHNOLOGY PROGRESS, Issue 4 2002Zhi-Long Xiu The trpoperon encodes the five genes for the enzymes required to convert chorismate to tryptophan, and its switching on and off is controlled by both feedback repression and attenuation in response to different levels of tryptophan in the cell. Repression of the operon occurs when tryptophan concentration is high, and attenuation fine-tunes the transcription level at a lower cellular concentration of tryptophan. An extended mathematical model is established in this study to describe the switching on and off of the trpoperon by considering the integrated effects of repression and attenuation. The influences of cell growth rate on the biosynthesis of tryptophan, stability and dynamic behavior of the trpoperon are investigated. Sustained oscillations of tryptophan levels are predicted from the regulated turning on and off of the trpoperon. It is interesting to note that during such oscillations the regulation of transcription displays a kind of "on" and "off" state in terms of gene expression, indicating the existence of a genetic circuit or switch in the regulation of the trpoperon. Time lags between transcription and translation are also predicted and may explain the occurrence of such oscillation phenomenon. [source] Bone morphogenetic protein 7 induces mesenchymal-to-epithelial transition in melanoma cells, leading to inhibition of metastasisCANCER SCIENCE, Issue 11 2009Yi-Rang Na Bone morphogenetic protein (BMP) 7 counteracts physiological epithelial-to-mesenchymal transition, a process that is indicative of epithelial plasticity in developmental stages. Because epithelial-to-mesenchymal transition and its reversed process mesenchymal-to-epithelial transition (MET) are also involved in cancer progression, we investigated whether BMP7 plays a role in WM-266-4 melanoma cell growth and metastasis. An MTT assay was conducted in WM-266-4 and HEK293T cell lines to show the cell growth inhibition ability of BMP7 and cisplatin. Semiquantitative RT-PCR was used to determine MET in morphologically changed BMP7-treated melanoma cells. MET-induced cells expressed less a basic helix-loop-helix transcription factor (TWIST) in western blot analysis, and we confirm that BMP receptor (Alk2) siRNA transduction could restore TWIST protein expression via blocking of Smad 1, 5 and 8 signaling. Matrigel invasion and cell migration assays were done to investigate the BMP7-induced metastasis inhibition ability. BMP7 treatment only slightly reduced cell growth rate, but induced apparent MET. BMP7 also reduced the invasion and migration ability. Furthermore, BMP7 reduced the resistance of WM-266-4 cells to cisplatin. Collectively, our findings indicate that the metastatis inhibition ability of BMP7 is involved in MET, and that BMP7 could be used as a potential metastasis inhibitor in human melanoma cells. (Cancer Sci 2009) [source] Analysis of glutathione endpoints for measuring copper stress in Chlamydomonas reinhardthENVIRONMENTAL TOXICOLOGY & CHEMISTRY, Issue 8 2007Tasha L. Stoiber Abstract Glutathione (GSH) is the most abundant nonprotein thiol in eukaryotic cells and it protects cells by functioning as an antioxidant and a metal-binding ligand. Because glutathione readily undergoes oxidation-reduction reactions to combat oxidative stress, intracellular ratios of the reduced (GSH) to the oxidized (GSSG) forms of glutathione may serve as an important biomarker of exposure and effect of trace metals in eukaryotic cells. We compared sensitivity of glutathione ratios in the freshwater alga Chlamydomonas reinhardtii to the traditional endpoints of cell growth rates and chlorophyll a following exposure to Cu for periods of 6 and 24 h. A response of the GSH:GSSG ratio to Cu concentration was observed at Cu levels of 40 and 80 nM after exposure for both 6 and 24 h. The concentration of total GSH at 24 h was roughly half the value at 6 h after exposure to either 40 or 80 nM Cu. A response for cell growth rate was observed only at 24 h, whereby the average specific growth rate decreased from about 1.1 to 0.4 d,1. The total Cu concentrations eliciting a cell response of 50%, effect concentrations (EC50s), after 24 h of exposure were similar (49.2, 49.8, and 38.2 nM Cu) and not significantly different for GSH:GSSG ratio, GSH levels, and specific growth, respectively. Total cell-associated Cu concentrations after exposure for 24 h were calculated from the EC50 endpoints and ranged from 13.3 to 17.0 fg/cell. Overall, thiol ratios were indicative of toxicity resulting from exposure to Cu, but precision may be greater for the cell growth rate endpoints. [source] Comparative measures of the toxicity of component chemicals in aircraft deicing fluidENVIRONMENTAL TOXICOLOGY & CHEMISTRY, Issue 6 2000Jeffrey S. Cornell Abstract Acraft deicingoperationsarea necessarypart of safe air travel, but release large quantities of aircraft deicing fluids (ADFs) to the environment. Effective measures to mitigate the environmental impacts of deicing operations are hindered because of the negative effects some ADF chemicals have on treatment systems and because of the poorly characterized toxicity of ADF components. This research investigated the contributions of environmentally significant concentrations of selected ADF components to the toxicity of ADF-containing waste streams, and to the inhibition of biodegradation of propylene glycol (PG), the most important component of ADF. The component chemicals studied were PG, the corrosion inhibitor 4(5)-methylbenzotriazole (MeBT; common name: tolyltriazole), and proprietary mixes of corrosion inhibitors, buffers, and surfactants referred to as the additive package or AdPack. Relative to PG alone, the different additives increased the toxicity of ADF and decreased PG biodegradation rates. In enrichments of soil microorganisms acclimated to ADF, the MeBT component significantly decreased cell growth rates and yields, and inhibited PG biodegradation to a greater extent than the AdPack. Microtox® tests indicated that MeBT is the ADF component most toxic to microorganisms. However, acute aquatic toxicity tests indicated that the AdPack components were more toxic than MeBT to Ceriodaphnia dubia and Pimephales promelas, although both components were more toxic than PG alone. [source] Downregulation of osteopontin contributes to metastasis suppression by breast cancer metastasis suppressor 1INTERNATIONAL JOURNAL OF CANCER, Issue 3 2008Benjamin D. Hedley Abstract Breast cancer metastasis suppressor 1 (BRMS1) inhibits the ability of multiple human and murine cancer cell lines to metastasize to lymph nodes, bones and lungs. Comparison of mRNA expression in metastatic MDA-MB-435 human carcinoma cells (435) and metastasis-suppressed BRMS1 transfectants (435/BRMS1) showed a marked (>90%) reduction of osteopontin (OPN) mRNA and protein expression in BRMS1-overexpressing cells. OPN expression is associated with disease progression in patients, with higher levels of OPN produced by cancer cells associated with poorer patient survival. Furthermore, OPN has been suggested to promote survival of cancer cells in response to stress, although the mechanisms by which this may occur remain poorly understood. This study tested the hypothesis that re-expression of OPN in metastasis-suppressed 435/BRMS1 cells would reverse metastasis suppression and confer protection from stress-induced apoptosis. A stable pooled population of OPN overexpressing 435/BRMS1 cells was created (435/BRMS1/OPN). OPN re-expression did not affect in vitro cell growth rates; however, increased anchorage independent growth/survival and protection from hypoxia-induced apoptosis was observed (p < 0.05). In vivo, OPN re-expression in BRMS1 transfected cells did not affect in vivo primary tumor growth but did increase the incidence of spontaneous metastasis to lymph nodes and lungs in mice. These novel findings suggest that OPN downregulation by BRMS1 may be responsible, at least in part, for BRMS1-mediated metastasis suppression by sensitizing cancer cells to stress induced apoptosis. These studies clarify one mechanism by which BRMS1 can suppress metastasis. © 2008 Wiley-Liss, Inc. [source] | |||||||||||||