Disease relevance of Formazan

• The MTT (C,N-diphenyl-N'-4,5-dimethyl thiazol-2-yl tetrazolium bromide) colorimetric assay (reduction of tetrazolium salt to formazan) was applied to rat islets and rat insulinoma cell lines [1].
• Macrophages isolated from normal mucosa (greater than 5 cm from tumour) and inflamed mucosa (from patients with inflammatory bowel disease) of colon and ileum were studied for their ability to undergo a respiratory burst as assessed by reduction of nitroblue tetrazolium to formazan [2].
• Formazan cells in protein and protein-calorie malnutrition [3].
• During hypoxia neurons reduced nitroblue tetrazolium to form the blue precipitate formazan, and the color change was blocked in neurons pretreated with superoxide dismutase in depolarizing medium [4].
• The data indicate that the exposure of ciliated respiratory epithelium to mycoplasma cells or membranes results in diminished oxidative metabolism, and that the ability to reduce TTC to its formazan is correlated with relative ciliary activity [5].

Psychiatry related information on Formazan

• In XTT assay, the production of formazan increases with reaction time over a protracted period of time, we assessed the possibility of performing assays with fewer cells than MTT was used [6].

High impact information on Formazan

• METHODS: Effects were assayed by a formazan-based colorimetric assay, [(3)H]thymidine incorporation, fluorescent nuclear staining, annexin V binding, DNA fragmentation assay, and immunoblotting of cytoplasmic and membrane fractions for PKC isozymes [7].
• The stimulatory state of Kupffer cells based on the ability to produce superoxide anions estimated by formazan deposition after liver perfusion with nitro blue tetrazolium and phorbol myristate acetate was increased between 24 and 72 hours after operation [8].
• Incubation of rings with nitro blue tetrazolium (NBT) resulted in blue formazan staining of the adventitia, and lucigenin chemiluminescence was significantly greater when detected from the adventitial compared with the intimal aspect of the artery [9].
• By means of a formazan dye-based spectrophotometric assay of cell viability and light microscopy, manumycin was shown to decrease the number of viable cells in all six of the cell lines though to a lesser degree in DRO and C643 cells than in ARO, Hth-74, KAT-4, and KAT-18 cells [10].
• AS cyclin D1 significantly inhibited cell proliferation by both [3H]thymidine incorporation in six SCC cell lines (P = 0.01-0.001) and the conversion of tetrazolium salt to formazan in four SCC cell lines (P = 0.01-0.004) [11].

Chemical compound and disease context of Formazan

• Toxicity is assessed by an objective, automated method based on the reduction of 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl tetrazolium bromide to an insoluble purple formazan by the mitochondria of viable cells and correlates with that based on trypan blue exclusion [12].
• The rate of appearance of red-colored formazan indicating reduction of 2,3,5,-triphenyltetrazolium chloride by Mycoplasma pneumoniae was dependent on the inoculum size [13].
• Conclusions: Formation of formazan from TTC can depend on both the staining method and the metabolic burden of the brain tissue causing uncertainties in the volume of ischemia-induced brain injury measured by TTC staining [14].
• A study was performed on 74 medicolegal autopsy cases for the purpose of comparing the reliability of four different techniques (haematoxylin-eosin stain, acridine orange method, formazan test and K/Na ratio) used for the postmortem diagnosis of myocardial infarction [15].
• These results suggest that alterations in cell cycle phase redistribution of MCF-7 human breast cancer, by ursolic acid, may significantly influence MTT reduction to formazan [16].

Biological context of Formazan

• When perfused in situ with nitroblue tetrazolium, an indicator for superoxide formation, the liver of transgenic mice displayed intense formazan deposition in Kupffer cells, indicating oxygen radical production, and S-phase hepatocytes were commonly seen adjacent to the stained Kupffer cells [17].
• Cell proliferation assays (tetrazolium salt conversion to formazan colorimetric assay) were performed beginning 2-8 days after plating [18].
• Evaluation of a soluble tetrazolium/formazan assay for cell growth and drug sensitivity in culture using human and other tumor cell lines [19].
• The use of an artificial system (formazan production) to study beta oxidation in the absence of the electron transport chain is described [20].
• LK-activated macrophages underwent an oxidative burst upon the phagocytosis of PE as evidenced by the accumulation of reduced formazan in the NBT assay [21].

Anatomical context of Formazan

• NBT was reduced to formazan in 71% of monocytes exposed to promastigotes [22].
• In rat hepatocytes in primary culture incubated with nitro blue tetrazolium, formazan content was increased by addition of t-butyl hydroperoxide, a potent oxidant, in a dose-related manner, but not by addition of valinomycin, which kills hepatocytes through mitochondrial damage [23].
• The protection against SZ and ROI was associated with preserved mitochondrial activity, as determined by the ability of the islet cells to convert the tetrazolium salt 3-(4,5-dimethylthiazolyl-2)-2,5-diphenyltetrazolium bromide into its formazan [24].
• Activated peritoneal macrophages exhibiting phagocytosing capacity produced an electron-dense precipitate of formazan in contact sites of macrophage plasmalemma and phagocytosed yeast cells [25].
• Endothelial cell viability was determined by measuring cellular reduction of 3-[4,5-dimethylthiazol-2-yl]-2,3-diphenyltetrazolium bromide to a purple formazan dye [26].

Associations of Formazan with other chemical compounds

• Furthermore, the following studies showed that inhibition of Ia by NO was not due to macrophage death: trypan blue exclusion, macrophage adhesion, conversion of the tetrazolium dye (MTT) to its formazan by a functioning electron transport system, and phagocytosis of IgG opsonized SRBCs [27].
• Treatment of frozen sections to demonstrate succinate dehydrogenase showed early changes in the character of formazan, suggesting the possibility of a transient alteration in the hydrogen transport system [28].
• No production of formazan occurred, when non-opsonized latex particles were ingested by macrophages [25].
• When a liver perfusion with nitro blue tetrazolium (NBT) and phorbol myristate acetate (PMA) was performed in carbon tetrachloride (CCl4)-intoxicated rats, formazan deposition was remarkable in macrophages in the necrotic areas of the liver, its intensity varying with the extent of injury [29].
• When peroxisomal membranes were assayed under native conditions using NADH or NADPH as inducer, two different O2(-).-dependent Formazan Blue bands were detected [30].

Gene context of Formazan

• Differential 'medium conditioning' led to a difference in formazan production per cell between IFN and control cells and this was the major basis of the observed discrepancy [31].
• RESULTS: Leptin stimulated proliferation of serum-deprived fetal rat islet cells, as indicated by increased formation of formazan dye from a tetrazolium salt WST-1 [32].
• In addition, a new staining procedure is described that allows the visualization of GPT activity on gels by the deposition of formazan [33].
• The presence of formazan deposits within Purkinje cells was verified by colocalization with calbindin D-28k immunoreactivity [34].
• Two cell populations of almost equal size could be discerned in heterozygotes for G6PD deficiency, one completely negative, the other with a variable amount of formazan per cell [35].

Analytical, diagnostic and therapeutic context of Formazan

• The same culture dishes were assessed by image analysis and by formazan colorimetry for purposes of comparing multiple methods of measuring growth as well as growth inhibition [36].
• This highly quantitative in vitro colorimetric bioassay is based upon the reduction of a tetrazolium salt, 3-[4,5-dimethyl-thiazol-2-yl]2,5-diphenyl tetrazolium bromide (MTT), to its formazan by lactogen-activated Nb2 cells [37].
• Cell number was determined by mitochondrial formazan production; apoptosis was measured by Tdt-mediated dUTP nick end labeling reaction and DNA fragmentation-based enzyme-linked immunosorbent assay [38].
• When the same compounds (0.1 microgram) were administered to mice which had been pretreated i.p. with thioglycollate 6 days prior to the experiment, PMA, PDB, 4-O-Me-PMA, mezerein and A23187 all caused an increase in the number of formazan-positive PECs 2 h after treatment [39].
• Enumeration of respiring Pseudomonas spp. in milk within 6 hours by fluorescence in situ hybridization following formazan reduction [40].

References