Cells metabolic activity

The cells are permitted to "plant" to the ECM and adjust to the incubator temperature (37°C) and C02 concentration. Then test compounds or controls (both in 0.1% dimethyl sulfoxide, DMSO) are added to the test wells. The cells are then incubated overnight, and the indicator dye Alamar blue10 is added. This noncytotoxic dye reacts to mitochondrial redox reactions and is measured fluorometrically. Cell metabolic activity is determined starting at 3 h after the dye is added and daily thereafter. 

The cell ntrmber is often estimated indirectly by evaluation of the cell metabolic activity using tests of activity various enzymes, e.g. esterases or mitochondrial enzymes (MTT, MTS or XTT tests), or mesrrrement of DNA content in cell lysates [11,37,43,55,56]. The indirect methods are suitable paticularly for cells growing inside three-dimensional materials, not accessible for direct cell cormting. 

In in vitro systems, criteria of toxicity will generally be measurements of either specific biochemical changes, such as ATP level or protein synthesis, or general indicators such as cell metabolic activity, viability, or membrane damage as indicated by dye uptake or enzyme leakage. 

Pluorouracil is a pyrimidine analog which is converted metabolically to its toxic form, fluorodeoxyuridylate (F-dUMP). As cells metabolically activate the drug it acts as a "suicide" inhibitor of Thymidyiate Synthetase. 

This bioluminescent system has been widely used as reporter system for the detection of pollutants because of its high sensitivity. The co-substrate (FMNH2) and substrate (R-CHO) required for this reaction do not accumulate in the cell, but their levels depend on the level and balance of metabolism. Thus the bioluminescent reaction is directly linked to the cells metabolic activity, and so in models using lux as the reporter system, the light emission capacity is directly affected by factors such as changes in cell growth and dissolved oxygen concentration (Nelson and Lawrence, 1980). 

Ipomeanol. This pulmonary toxin is produced by a mould which grows on sweet potatoes. The toxin produces oedema, congestion and haemorrhage resulting from necrosis of the Clara cells (non-ciliated bronchiolar cells). Metabolic activation by a specific form of cytochrome P-450 in these cells produces a reactive metabolite which binds to macromolecules in these cells causing necrosis. Induction and inhibition of cytochrome P-450 may increase and decrease toxicity and depleting GSH increases the toxicity. 

Cytotoxicity test The L929 fibroblast cell line is the most widely used for cytotoxicity assessment 9-11. The cell metabolic activity was evaluated by succinc acid dehydrogenase (SDH) of mitochondria in living cell, which can deoxidized MTT salt into insoluble purple crystal. These crystals can be resolved by dimethyl sulfoxide (DMSO), and measured by the spectrophotometric microplate reader at 490 nm. To some extent, the optical density value (OD) of supernatant raised with the number of the living cell. Therefore, the measurement of MTT crystal OD can reflect the relative growth rate and the activity of cells, which can also leads to a reliable assessment to the cytotoxicity of the sample. 

Cagide, E. et al.. Cytotoxicity assessment of several marine toxins by using an indicator of cell metabolic activity for kinetic measurements, in XII International lUPAC Symposium on Mycotoxins and Phycotoxins, Istanbul, Turkey, 2007. 

A series of changes takes place in the nucleic acid metabolism of the remnant, some of which are evident within an hour after surgery. A well-defined wave of DNA synthesis sweeps through the tissue 18-24 hours after surgery this event coincides roughly with a burst of mitotic activity. Some synchronization of cell metabolic activities is indicated by the time course of these events however, the synchrony is soon lost. Definition of the biochemical factors which initiate the sudden burst of DNA synthesis has been a particular goal of investigators. 

The size of porous silicon particles is also an important factor. Particles smaller than 3 pm have been demonstrated to be cytotoxic to monocytes (Ainslie et al. 2008) loss in Caco-2 cell metabolic activity was seen with particles between 1.2 and 25 pm in size (Santos et al. 2010). In contrast, particles below 500 nm were demonstrated to be nontoxic to lymphoma cells (De Angelis et al. 2010), and particles smaller than 1 pm did not cause any cytotoxic effects with macrophage and endothelial cells (Godin et al. 2012). 

The degree of the mutation response to chemical compounds depends on several factors. The mutation curve rises with increasing dose, reaches a plateau at a certain dose (concentration), and then falls off. But what we actually found after treatment with various compounds was not simple due to the interaction of a number of variables. Major variables are dose of chemical, developmental stage of germ cells, metabolic activation of the chemical, and others. Since observed mutation frequencies are the product of interaction among all these factors, they vary more or less from experiment to experiment. 

Figure 14.12 Monitoring of lactate concentration and the change of cell metabolic activity after stimulation by fetal bovine serum (FBS) (Boubriak et al., 2006a).

Zhao F, Pathi P, Grayson W, Xing Q, Locke BR, Ma T. 2005. Effects of oxygen transport on 3-d human mesenchymal stem cell metabolic activity in perfusion and static cultures Experiments and mathematical model. Biotechnol Rro 21(4) 1269-80. 

Viable cells mean cells which can grow non-viable cells mean cells which cannot. Microbiologists use the same terms but can divide non-viable cells into cells, which remain metabolically active in some respects and cells which are effectively dead. They can also distinguish within their category of "viable cells between cells, which are actively dividing, and cells such as spore cells whose growth activities are potential rather than actual. 

For type 3 processes, growth and metabolic activity reach a maximum early in the batch process cycle (Figure 3.1) and it is not until a later stage, when oxidative activity is low, that maximum desired product formation occurs. The stoichiometric descriptions for both type 3 and 4 processes depend upon the particular substrates and products involved. In the main, product formation in these processes is completely uncoupled from cell growth and dictated by kinetic regulation and activity of cells. 

This discrepancy is due to die fact that other products such as formate, are formed in very small amounts as byproducts of the metabolic routes leading to L-phenylalanine and polymer synthesis. Of course, part of die glucose is also used for die metabolic activities in the micro-organism necessary to maintain the cells in a viable state, this is termed the maintenance energy requirement... 

Cell growth and metabolic activities are similarly described as a simple chemical reaction. It is also necessary to establish a definite formula for dry cell matter. The elemental composition of certain strains of microorganism is defined by an empirical formula CHaO/3Ns. The general biochemical reaction for biomass production is based on consumption of organic substrate, as shown below. Substrate oxidation is simplified in the following biochemical oxidation ... 

The composition of body fluids remains relatively constant despite the many demands placed on the body each day. On occasion, these demands cannot be met, and electrolytes and fluids must be given in an attempt to restore equilibrium. The solutions used in the management of body fluids discussed in this chapter include blood plasma, plasma protein fractions, protein substrates, energy substrates, plasma proteins, electrolytes, and miscellaneous replacement fluids. Electrolytes are electrically charged particles (ions) that are essential for normal cell function and are involved in various metabolic activities. This chapter discusses the use of electrolytes to replace one or more electrolytes that may be lost by the body. The last section of this chapter gives a brief overview of total parenteral nutrition (TPN). 

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