Citotoxicidade: Diferenzas entre revisións
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== Medición ==
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Os ensaios de citotoxicidade son amplamente utilizados pola industria farmacéutica para facer exames de citotoxicidade en bibliotecas compostas. Os investigadores poden buscar compostos citotóxicos, se están interesados no desenvolvemento dunha terapéutica que se dirixe contra as células cancerosas en rápida división, por exemplo; ou poden examinar os "golpes" ("hits") dos exames iniciais de fármacos de alto rendemento polos efectos citotoxicos non desexado antes de investir no seu desenvolvemento farmacéutico.
Assessing cell membrane integrity is one of the most common ways to measure cell viability and cytotoxic effects. Compounds that have cytotoxic effects often compromise cell membrane integrity. Vital dyes, such as [[trypan blue]] or propidium iodide are normally excluded from the inside of healthy cells; however, if the cell membrane has been compromised, they freely cross the membrane and stain intracellular components.<ref name="riss1"/> Alternatively, membrane integrity can be assessed by monitoring the passage of substances that are normally sequestered inside cells to the outside. One molecule, [[lactate dehydrogenase]] (LDH), is commonly measured using [[LDH assay]]. LDH reduces NAD to NADH which elicits a colour change by interaction with a specific probe.<ref>{{cite journal |author=Decker T, Lohmann-Matthes ML |title=A quick and simple method for the quantitation of lactate dehydrogenase release in measurements of cellular cytotoxicity and tumor necrosis factor (TNF) activity |journal=J. Immunol. Methods |volume=115 |issue=1 |pages=61–9 |date=November 1988 |pmid=3192948 |doi= 10.1016/0022-1759(88)90310-9|url=|last2=Lohmann-Matthes }}</ref> Protease biomarkers have been identified that allow researchers to measure relative numbers of live and dead cells within the same cell population. The live-cell protease is only active in cells that have a healthy cell membrane, and loses activity once the cell is compromised and the protease is exposed to the external environment. The dead-cell protease cannot cross the cell membrane, and can only be measured in culture media after cells have lost their membrane integrity.<ref>{{cite journal |vauthors=Niles AL, Moravec RA, Eric Hesselberth P, Scurria MA, Daily WJ, Riss TL |title=A homogeneous assay to measure live and dead cells in the same sample by detecting different protease markers |journal=Anal. Biochem. |volume=366 |issue=2 |pages=197–206 |date=July 2007 |pmid=17512890 |doi=10.1016/j.ab.2007.04.007 }}</ref>▼
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Cytotoxicity can also be monitored using the 3-(4, 5-Dimethyl-2-thiazolyl)-2, 5-diphenyl-2H-tetrazolium bromide ([[MTT assay|MTT]]) or with 2,3-bis-(2-methoxy-4-nitro-5-sulfophenyl)-2H-tetrazolium-5-carboxanilide (XTT), which yields a water-soluble product, or the MTS assay. This assay measures the reducing potential of the cell using a colorimetric reaction. Viable cells will reduce the MTS reagent to a colored [[formazan]] product. A similar redox-based assay has also been developed using the fluorescent dye, [[resazurin]]. In addition to using dyes to indicate the redox potential of cells in order to monitor their viability, researchers have developed assays that use [[Adenosine triphosphate|ATP]] content as a marker of viability.<ref name=riss1/> Such ATP-based assays include bioluminescent assays in which ATP is the limiting reagent for the [[luciferase]] reaction.<ref>{{cite journal |author=Fan F, Wood KV |title=Bioluminescent assays for high-throughput screening |journal=Assay Drug Dev Technol |volume=5 |issue=1 |pages=127–36 |date=February 2007 |pmid=17355205 |doi=10.1089/adt.2006.053 |url=|last2=Wood }}</ref>
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* [[Natural killer T cell]]s
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== Notas ==
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