The Calorimetric-respirometric Ratio: Its Potential as a Cytotoxicity Test

1994 ◽  
Vol 22 (5) ◽  
pp. 364-376
Author(s):  
Richard B. Kemp ◽  
Catherine Stephansen ◽  
Sajid Mohamed ◽  
R.W. John Meredith
Keyword(s):  
Heat Flux ◽  
Salt Solution ◽  
Krebs Cycle ◽  
Cytotoxicity Test ◽  
Antimycin A ◽  
Rich Medium ◽  
Animal Cells ◽  
Normal Input ◽  
High Level ◽  
L929 Mouse

The ratio between heat flux and oxygen flux, the calorimetric ratio, is an enthalpy budget device used to identify anaerobic pathways in the presence of respiration. Ratios that are more exothermic (i.e. more negative) than the average for catabolic substrates (-450kJ mol O2 ± 5%; Thornton's rule), are usual for cells established in culture, including suspension-adapted LS-L929 mouse fibroblasts. A common reason for this is a high level of glycolysis, to produce lactate, simultaneously with aerobic pathways. To test the idea that the calorimetric-respirometric (CR) ratio is a revealing cytotoxic endpoint, LS cells grown in serum-rich medium were insulted with known metabolic poisons. Malonate, 2,4-dinitrophenol (2,4-DNP) and a mixture of antimycin A and rotenone increased the CR ratio to degrees largely explained by greater lactate flux, the CR700 values being 22μM malonate, 56μM 2,4-DNP and, for the mixture, 2μM antimycin A and 5μM rotenone. Higher concentrations of 2,4-DNP gave an “exothermic gap” for which there was no explained pathway. Iodoacetate decreased the CR ratio while inhibiting glycolysis, a result which can be explained by the hypothesis that substrates available in the serum were degraded by mitochondrial pathways and thereby substituted for the normal input from the Krebs cycle, which had been arrested by pyruvate starvation. In a balanced salt solution containing only 5.5mM glucose, the metabolic rate slowed and the CR ratio was more exothermic (CR700 = 6μM), giving a “gap” for which there was no explanation. Ten MEIC chemicals gave CR700 endpoints which closely corresponded to the order of toxicity for a battery of tests using animal cells. The CR method thus provides a good basis for investigating the mechanisms by which chemicals have toxic effects on cells.

scholarly journals Evidence That Runt Acts as a Counter-Repressor of Groucho During Drosophila melanogaster Primary Sex Determination

2020 ◽  
Vol 10 (7) ◽  
pp. 2487-2496
Author(s):  
Sharvani Mahadeveraju ◽  
Young-Ho Jung ◽  
James W. Erickson
Keyword(s):  
Drosophila Melanogaster ◽  
Sex Determination ◽  
Transcriptional Repression ◽  
Biological Effects ◽  
Regulatory Gene ◽  
Animal Cells ◽  
Interaction Domain ◽  
Link Type ◽  
High Level ◽  
Runx Proteins

Runx proteins are bifunctional transcription factors that both repress and activate transcription in animal cells. Typically, Runx proteins work in concert with other transcriptional regulators, including co-activators and co-repressors to mediate their biological effects. In Drosophila melanogaster the archetypal Runx protein, Runt, functions in numerous processes including segmentation, neurogenesis and sex determination. During primary sex determination Runt acts as one of four X-linked signal element (XSE) proteins that direct female-specific activation of the establishment promoter (Pe) of the master regulatory gene Sex-lethal (Sxl). Successful activation of SxlPe requires that the XSE proteins overcome the repressive effects of maternally deposited Groucho (Gro), a potent co-repressor of the Gro/TLE family. Runx proteins, including Runt, contain a C-terminal peptide, VWRPY, known to bind to Gro/TLE proteins to mediate transcriptional repression. We show that Runt’s VWRPY co-repressor-interaction domain is needed for Runt to activate SxlPe. Deletion of the Gro-interaction domain eliminates Runt-ability to activate SxlPe, whereas replacement with a higher affinity, VWRPW, sequence promotes Runt-mediated transcription. This suggests that Runt may activate SxlPe by antagonizing Gro function, a conclusion consistent with earlier findings that Runt is needed for Sxl expression only in embryonic regions with high Gro activity. Surprisingly we found that Runt is not required for the initial activation of SxlPe. Instead, Runt is needed to keep SxlPe active during the subsequent period of high-level Sxl transcription suggesting that Runt helps amplify the difference between female and male XSE signals by counter-repressing Gro in female, but not in male, embryos.

Cytotoxicity of Pharma Grade ZnO with Higher Surficial Oxygen on L929 Mouse Cell

2019 ◽  
Vol 290 ◽  
pp. 286-291
Author(s):  
Nur Mariam Kamaruddin ◽  
Shahrom Mahmud ◽  
Sufiniza Nordin ◽  
Abdulsalam Abuelsamen ◽  
Azman Seeni ◽  
...  
Keyword(s):  
Cell Viability ◽  
Particle Surface ◽  
L929 Cell ◽  
Average Crystallite Size ◽  
Fibroblast Cell ◽  
Mouse Cell ◽  
Mouse Fibroblast ◽  
Cytotoxicity Test ◽  
Zno Powder ◽  
L929 Mouse

Apart from being a promising optoelectronic devices such as photodetector and sensors, ZnO has many dental and biomedical applications. ZnO has been known to possess strong toxicity towards bacteria, cancer and fungi. Cytotoxicity test of pharmaceutical grade of ZnO on L929 mouse fibroblast cell lines was carried out using trypan blue assay. ZnO was characterized for its morphology, structure and optical properties using FESEM, EDS, UV-Vis and XRD. ZnO exhibited various morphologies like rod, platelet, slab and irregular-shaped particles. EDS data showed the ZnO powder possessed relatively higher oxygen atomic percentage if compared to zinc atoms with an oxygen-to-zinc ratio of 1.219. The average crystallite size obtained was about 39 nm. The percentage of cell viability on L929 cell was decreased with increasing ZnO concentrations. The cells viability after 72h were achieved and the concentration of ZnO below 1 mM was summarized as non-toxic after treated with ZnO. The higher surficial oxygen on ZnO particle surface could have promoted higher generation of reactive oxygen species that caused lower L929 cell viability.

Behavior of Np, Pu, Am, Tc Upon Glass Corrosion in a Concentrated Mg(Ca)Cl2Solution

1994 ◽  
Vol 353 ◽  
Author(s):  
Bernd Grambow ◽  
Andreas Loida ◽  
Lothar Kahl ◽  
Werner Lutze
Keyword(s):  
Salt Solution ◽  
Near Field ◽  
Fluid Phase ◽  
Glass Waste ◽  
Glass Dissolution ◽  
Glass Corrosion ◽  
Corrosion Studies ◽  
High Level ◽  
Drill Holes ◽  
Kinetics Of

AbstractThe objective of this investigation is to describe the extent to which Np, Pu, Am and Tc are mobilized from vitrified high-level radioactive waste into the near field of an HLW repository in a salt formation, when a hot and concentrated salt solution comes into contact with the glass. Waste form corrosion studies are conducted with a salt solution representing the composition of a fluid phase encountered in drill holes in the Gorleben salt dome. Test temperatures are determined by the designed maximum surface temperature of 200°C for the vitrified waste in the Gorleben salt. The following results were obtained: 1. pH changes of the radio-active leachate are the same as in inactive leachates. 2. The time and temperature dependence of the reaction for the radioactive glass are in excellent agreement with that of the inactive glass. 3. Np, Pu, Am, and Tc have not been reimmobilized in secondary minerals. Hence, mobilization of these radionuclides is governed by the kinetics of glass dissolution. Pu oxidation states were analyzed and related to Pu concentrations.

Cooling of a Heated Surface by Mist Flow

1994 ◽  
Vol 116 (1) ◽  
pp. 167-172 ◽  
Author(s):  
S. L. Lee ◽  
Z. H. Yang ◽  
Y. Hsyua
Keyword(s):  
Heat Transfer ◽  
Heat Flux ◽  
Liquid Film ◽  
Heated Surface ◽  
High Heat ◽  
Dynamic Interaction ◽  
High Heat Flux ◽  
Steady Temperature ◽  
Mist Flow ◽  
High Level

Cooling requirements in modern industrial applications, such as the removal of heat from electronic equipments, often demand the simultaneous attainment of a high heat flux and a low and relatively uniform and steady temperature of the heated surface to be cooled. The conventional single-phase convection cooling obviously cannot be expected to function adequately, since the heat flux there is directly proportional to the temperature difference between the heated surface and the surrounding medium. To maintain a high heat flux, the temperature of the heated surface usually must be kept at a high level. An attractive alternative is cooling by a spray, which takes advantage of the significant latent heat of evaporation of the liquid. However, in conventional industrial spray coolings, such as in the case of the cooling tower of a power plant, the temperature of the heated surface usually remains relatively high and is nonuniform and unsteady containing numerous flashy hot spots. In order to optimize the performance of the spray cooling of a heated surface by a mist flow, a clear understanding is required of (1) the dynamic interaction between the droplets and the carrier fluid and (2) the thermal reception of the droplets at the heated surface. It is the dynamic interaction between the phases that is causing the droplets to deposit onto the heated surface. The thermal reception at the heated wall develops mass and heat transfer leading to the mode of cooling of the heated surface. In the present study, an experimental investigation was made of the combination of the dynamic depositional behavior of droplets in a water droplet-air mist flow with the use of a specially designed particle-sizing two-dimensional laser-Doppler anemometer. Also, the heat transfer characteristics at the heated surface were investigated in relation to droplet deposition on the heated surface for wide ranges of droplet size, droplet concentration, mist flow velocity, and heat flux. It was discovered that over a certain suitable range of combination of these parameters, a superbly effective cooling scheme could be established by the evaporation on the outside surface of an ultrathin liquid film. Such a film was formed on the heated surface by the continuous deposition of fine droplets from the mist flow. Under these conditions, the heat flux is primarily related to the evaporation of the ultrathin liquid film on the heated surface and thus depends less on the temperature difference between the heated surf ace and the ambient mist flow. The heated surface is quenched to a low, relatively uniform and steady temperature at a very high level of heat flux. Heat transfer enhancement as high as seven times has been found so far. This effective heat transfer scheme is here termed mist cooling.

scholarly journals MEMBRANES OF ANIMAL CELLS

1968 ◽  
Vol 37 (3) ◽  
pp. 729-746 ◽  
Author(s):  
L. Warren ◽  
M. C. Glick
Keyword(s):  
Culture Medium ◽  
Surface Membrane ◽  
Particulate Material ◽  
Metabolic Inhibitors ◽  
Plateau Phase ◽  
Animal Cells ◽  
Growing Cell ◽  
Specific Activities ◽  
Cell Fractions ◽  
High Level

Turnover studies of the surface membrane and of cell particulate matter of L cells in tissue culture in logarithmic and plateau phase of growth have been made. The rate of incorporation of isotope into these fractions and the rate of fall of specific activities of labeled L-cell fractions have been observed. The following interpretation of the data appears most likely although other interpretations are possible. Growing and nongrowing cells synthesize approximately similar amounts of surface membrane and particulate material. In the growing cell the material is incorporated with net increases in substance. There is relatively little turnover. In the nongrowing cell newly synthesized material is incorporated, but a corresponding amount of material is eliminated so that there is turnover without net increase of substance. Our results suggest that there is no gross differential turnover between the protein, lipid, and carbohydrate of the surface membrane under the conditions of our experiments. Metabolic inhibitors or omission of amino acids in the culture medium lead to a decrease in synthesis of surface membrane and cell particulates and cause an equivalent decrease in the rate of degradation of surface membrane and of particulates; therefore the synthetic and degradative aspects of turnover appear to be coupled. As cultures of nongrowing cells in suspension or on a glass surface age, their synthetic and turnover capacities diminish. Our results suggest that the cell may exist in a nongrowing state with a level of synthesis similar to that of a growing cell. It can exist in this state with a high level of turnover.

AREVA’s Test Facility KATHY: Robust Critical Heat Flux Measurements, a Prerequisite for Reliable CHF Prediction

2014 ◽  
Author(s):  
O. Wieckhorst ◽  
J. Kronenberg ◽  
H. Gabriel ◽  
S. Opel ◽  
D. Kreuter ◽  
...  
Keyword(s):  
Heat Flux ◽  
Fuel Assembly ◽  
Critical Heat Flux ◽  
Development Process ◽  
Heat Removal ◽  
Test Facility ◽  
Hydraulic Facility ◽  
Key Factor ◽  
Unique Experience ◽  
High Level

The primary tool for assuring the heat removal from the fuel design’s rod surfaces is properly represented in the numerical simulations of a LWR fuel assembly design is the critical heat flux (CHF) or dryout correlation. During the last decade, AREVA has compiled unique experience in correlation development that has led to an improved development process to meet increased technical challenges. This is based upon the high level of expertise in CHF measurements for PWR and BWR fuel assembly designs gained by AREVA at its KATHY facility (KArlstein Thermal HYdraulic facility). The utilization of KATHY in conjunction with this improved development process is a key factor in ensuring reliable CHF prediction for safety analysis application. This paper describes the capabilities of the KATHY loop and the process used by AREVA to attain high quality CHF measurements.

Design Options for HLW Repository Operation Technology: Part V—Preliminary Study and Small Scale Experiments on the Method of Removal of Buffer Material With Salt Solution

2010 ◽  
Author(s):  
Satohito Toguri ◽  
Takashi Ishii ◽  
Jiho Jang ◽  
Mitsunobu Okihara ◽  
Kengo Iwasa ◽  
...  
Keyword(s):  
Radioactive Waste ◽  
Salt Solution ◽  
Scale Model ◽  
Disposal Site ◽  
Small Scale ◽  
High Level Radioactive Waste ◽  
Buffer Material ◽  
Basic Characteristics ◽  
High Level ◽  
Design Options

The Nuclear Safety Commission of Japan stipulates that “When closing a waste disposal site, the validity of safety assessment results should be verified using the data obtained in the construction and operation phases as well. The retrieval of high-level radioactive waste should be made continuously possible during the period before the verification of the validity.”[1] Retrieving high-level radioactive waste requires the removal of the bentonite-based buffer around the emplaced overpack. In this study, focus was placed on a method for reducing the cohesion of bentonite, a major component of the buffer by dipping the buffer in fluid salt solution and dissolving the material into a slurry using fluid salt solution for removal (method of making a slurry). In order to examine the feasibility and the basic characteristics of the method, element tests were conducted using a small specimen of buffer and fluid salt solution (NaCl solution). In order to verify the feasibility of the infiltration and jetting of fluid salt solution, small-scale model tests were conducted using a specimen composed of 1/14-scale overpack and buffer. It was made clear that the infiltration and jetting of fluid salt solution was feasible as a method for removing a buffer.

scholarly journals Production of Highly Active Recombinant Dermonecrotic Toxin of Bordetella Pertussis

Toxins ◽  
2020 ◽  
Vol 12 (9) ◽  
pp. 596
Author(s):  
Ondrej Stanek ◽  
Irena Linhartova ◽  
Jana Holubova ◽  
Ladislav Bumba ◽  
Zdenko Gardian ◽  
...  
Keyword(s):  
Whooping Cough ◽  
Atrophic Rhinitis ◽  
Airway Epithelial ◽  
Animal Cells ◽  
High Biological Activity ◽  
Dermonecrotic Toxin ◽  
Highly Active ◽  
Rho Family Gtpases ◽  
Epithelial Layers ◽  
High Level

Pathogenic Bordetella bacteria release a neurotropic dermonecrotic toxin (DNT) that is endocytosed into animal cells and permanently activates the Rho family GTPases by polyamination or deamidation of the glutamine residues in their switch II regions (e.g., Gln63 of RhoA). DNT was found to enable high level colonization of the nasal cavity of pigs by B. bronchiseptica and the capacity of DNT to inhibit differentiation of nasal turbinate bone osteoblasts causes atrophic rhinitis in infected pigs. However, it remains unknown whether DNT plays any role also in virulence of the human pathogen B. pertussis and in pathogenesis of the whooping cough disease. We report a procedure for purification of large amounts of LPS-free recombinant DNT that exhibits a high biological activity on cells expressing the DNT receptors Cav3.1 and Cav3.2. Electron microscopy and single particle image analysis of negatively stained preparations revealed that the DNT molecule adopts a V-shaped structure with well-resolved protein domains. These results open the way to structure–function studies on DNT and its interactions with airway epithelial layers.

A nuclear glutathione cycle within the cell cycle

2010 ◽  
Vol 431 (2) ◽  
pp. 169-178 ◽  
Author(s):  
Pedro Diaz Vivancos ◽  
Tonja Wolff ◽  
Jelena Markovic ◽  
Federico V. Pallardó ◽  
Christine H. Foyer
Keyword(s):  
Gene Expression ◽  
Cell Cycle ◽  
Nuclear Dna ◽  
Expression Patterns ◽  
Animal Cells ◽  
Cellular Redox ◽  
Intracellular Compartments ◽  
Glutathione Cycle ◽  
Defence Proteins ◽  
High Level

The complex antioxidant network of plant and animal cells has the thiol tripeptide GSH at its centre to buffer ROS (reactive oxygen species) and facilitate cellular redox signalling which controls growth, development and defence. GSH is found in nearly every compartment of the cell, including the nucleus. Transport between the different intracellular compartments is pivotal to the regulation of cell proliferation. GSH co-localizes with nuclear DNA at the early stages of proliferation in plant and animal cells. Moreover, GSH recruitment and sequestration in the nucleus during the G1- and S-phases of the cell cycle has a profound impact on cellular redox homoeostasis and on gene expression. For example, the abundance of transcripts encoding stress and defence proteins is decreased when GSH is sequestered in the nucleus. The functions of GSHn (nuclear GSH) are considered in the present review in the context of whole-cell redox homoeostasis and signalling, as well as potential mechanisms for GSH transport into the nucleus. We also discuss the possible role of GSHn as a regulator of nuclear proteins such as histones and PARP [poly(ADP-ribose) polymerase] that control genetic and epigenetic events. In this way, a high level of GSH in the nucleus may not only have an immediate effect on gene expression patterns, but also contribute to how cells retain a memory of the cellular redox environment that is transferred through generations.

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