Measurements, cell survival

Cell Survival Measurements. L1210 cell survival was quanti-fied by colony forming ability in soft agar ( ). V79 colony-... 

Increased nonconjugated (indirect) bilirubin Shortened red cell survival time as measured by injection of autologous Cr-labeled red cells... 

High antioxidative activity carvedilol has been shown in isolated rat heart mitochondria [297] and in the protection against myocardial injury in postischemic rat hearts [281]. Carvedilol also preserved tissue GSL content and diminished peroxynitrite-induced tissue injury in hypercholesterolemic rabbits [298]. Habon et al. [299] showed that carvedilol significantly decreased the ischemia-reperfusion-stimulated free radical formation and lipid peroxidation in rat hearts. Very small I50 values have been obtained for the metabolite of carvedilol SB 211475 in the iron-ascorbate-initiated lipid peroxidation of brain homogenate (0.28 pmol D1), mouse macrophage-stimulated LDL oxidation (0.043 pmol I 1), the hydroxyl-initiated lipid peroxidation of bovine pulmonary artery endothelial cells (0.15 pmol U1), the cell damage measured by LDL release (0.16 pmol l-1), and the promotion of cell survival (0.13 pmol l-1) [300]. SB 211475 also inhibited superoxide production by PMA-stimulated human neutrophils. 

Another proposed in vitro assay for muscle irritancy for injectable formulations is the red blood cell hemolysis assay (Brown et al., 1989). Water-soluble formulations in a 1 2 ratio with freshly collected human blood are gently mixed for 5 min. The percentage of red blood cell survival is then determined by measuring differential absorbance at 540 nm this value is then compared to values for known irritants and nonirritants. Against a very small group of compounds (four), this assay reportedly accurately predicts muscle irritation. 

The antioxidant activity afforded by NO is most important if it translates into a meaningful therapeutic event. To test the importance of this reaction pathway to cell survival, we compared viability of the cells exposed to in the presence or absence of NO, When cells are exposed to 20 pM there was appreciable loss of cell membrane integrity as measured by trypan blue dye exclusion (Kelley et al, 1999) the addition of NO deaeased cell membrane damage (Figure 6). 

AP-induced toxicity and measurement of cell survival/injury were performed as described in detail elsewhere.1011 Briefly, 6-day-old cells were exposed to fresh solutions of either Ap25 35 or Ap, 42 for 24 h, in the presence or absence of different drugs. Cell survival and extent of cell death were determined using MTT and Sytox green assays, respectively. Measurement of intracellular reactive oxygen species was determined by dichlorofluorescein (DCF) fluorescence assay, as described previously.23... 

Cytotoxicity assays can be performed in various ways. In some cases, alterations of metabolic activities induced by drugs are measured. In other cases, structural integrity, which may or may not be directly related to cell death, is evaluated. Alternatively, cell survival assays measuring the result of each metabolic perturbation can be performed and used to evaluate cell recovery or death. 

Theoretically, the only conclusive signal of cell survival after drug exposure is the demonstration of reproductive integrity, which can be evaluated through plating efficiency and cell proliferation tests. Nevertheless, metabolic parameters could also be employed as a survival measure when the cell population is submitted to a recovery period after drug exposure. 

Clonogenic survival of B16 melanoma cells measured after exposure to graded doses of 211 At-AMT for 45 minutes is represented in Figure 12, showing that this radiolabelled modified melanin precursor is exceptionally cytotoxic. The linear cell survival curve, without a shoulder in the low-dose region, is characterisitc for high-LET a radiation125. 

While these techniques are sensitive, they can be hampered by cytotoxic side effects of the labeling procedures and can be limited by dilution and loss of the marker over time as a result of cell division [55], Thus, while useful for measuring the efficiency of acute delivery, these techniques may offer minimal long-term information regarding cell survival, proliferation, and differentiation [56],... 

A common use of chromium-51 is in studies of red blood cells. The isotope can be used to find out how many blood cells are present in a person s body. It can be used to measure how long the blood cells survive in the body. The isotope can also be used to study the flow of blood into and out of a fetus (an unborn child). 

The ATP-vesicles were also tested for their effect on cell survival during varions ischemic conditions. Using HUVECs incubated with ATP-vesicles, we tested the effect of 6-h hypoxia (<0.5% O ) on cell viability as measured by adherence. The experiments were repeated three times for each condition... 

The animals into which these cells were inoculated were either drug-treated or untreated controls. They were checked daily for survival. It is critical to note that cells used for DNA assays were aliquots of identical cells used for vivo survival measurements. Further, by mixing oppositely labeled cells prior to drug treatment, uniform drug exposure was assured... 

Figure 5. Relation between DNA interstrand crosslinking and DNA protein crosslinking and survival of L1210 cells as measured by soft-agar colony formation. Key to conditions top, without proteinase-K (DPC + ISC) and bottom, with proteinase-K (ISC only). (Reproduced with permission from Ref. 9.)...

Cytotoxicity Assay. Test materials were evaluated for cytotoxicity by measuring cell survival at the end of the each experiment using the sulforhodamine B staining method (8). 

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