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At least 235 records · Page 13Linked to original sources
PubMed1999

Enhancement of MTT, a tetrazolium salt, exocytosis by amyloid beta-protein and chloroquine in cultured rat astrocytes.

The effect of amyloid beta-protein (Abeta) on the cellular reducing activity has been a controversial issue. We determined the cellular reducing activity in cultured astrocytes using 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) and 2-(2-methoxy-4-nitrophenyl)-3-(4-nitrophenyl)-5-(2,4-disulfophenyl )-2H-tetrazolium (WST-8) reduction assays following Abeta treatment. MTT reduction was inhibited whereas WST-8 reduction was unaffected by the Abeta treatment. Furthermore, the early extracellular appearance of MTT formazan, a reduced product of MTT, was observed in association with the rapid disappearance of intracellular formazan granules. Notably, similar results were obtained in cultures treated with chloroquine, a perturbant of membrane trafficking. Our results suggest that MTT formazan exocytosis is enhanced in a similar manner by Abeta and chloroquine and that this biological activity of Abeta may underlie the pathogenesis of Alzheimer's disease.

Amyloid beta-Peptides↗
PubMed1983

[Histochemical detection of tissue changes using tetrazolium salts of differing nitrosensitivity].

By histochemical detection of succinic dehydrogenase in the myocardium of rats, it was shown that cell alterations induced by isoprenaline can be demonstrated in different qualities by the use of the atypical formazans of suitable nitro-monotetrazolium salts. The chemical structure of these nitro-monotetrazolium salts defines their different trends ("nitro-sensitivity") to react in their atypically-coloured formazans under histochemical conditions. A range of nitro-monotetrazolium salts with graded nitro-sensitivities is stated for improved histochemical detection of cell and tissue injuries.

Animals↗
PubMed1980

Tetrazolium salts in pharmaceutical analysis II: direct assay of diethylstilbestrol and diethylstilbestrol dipropionate.

A convenient spectrophotometric determination of diethylstilbestrol and diethylstilbestrol dipropionate was developed involving their interaction with triphenyltetrazolium chloride at 50 degrees for 45 min and subsequent measurement of the formazan formed. The significance of extended conjugation within t,e 4,4'-stilbenediol molecule to induce the color reaction is documented. Ideal adherence of color absorption to Beer's law permitted accurate and precise determination of diethylstilbestrol and diethylstilbestrol dipropionate pure forms over the range of 2-22 microgram of diethylstilbestrol/ml. Application of the tetrazolium color reaction to the analysis of diethylstilbestrol dipropionate dosage forms was achieved without prior hydrolysis or extraction.

Color↗
PubMed1967

Use of tetrazolium salts for electron transport studies in meningopneumonitis. 3. Separation and examination of large and small particles.

Purified suspensions of meningopneumonitis can be separated on potassium tartrate gradient into populations which are 80 to 90% large particles and those which are 90% small particles. Examination of the tetrazole reduction of both particle types indicates that the small particle has associated with it all of the enzymatic activity of the preparation; it also has associated with it most of the infectivity as well.

Centrifugation, Density Gradient↗
PubMed1996

A combined assay of cell viability and in vitro cytotoxicity with a highly water-soluble tetrazolium salt, neutral red and crystal violet.

Cell viability and in vitro cytotoxicity assay methods were developed using a combination of dyes, 4-[3-(4-iodophenyl)-2-(4-nitrophenyl)-2H-5-tetrazolio]-1,3-benzene disulfonate (WST-1), neutral red (NR) and crystal violet (CV), with HeLa cells as a bioindicatior. As WST-1 produces a highly water soluble and non-cytotoxic formazan dye, ti allows each assay to be carried out in one culture dish. The combined cell viability assay using WST-1, NR and CV gave an absorbance that correlated linearly with the number of cells over the range 1000 to 50,000 cells/well. The combined assay was applied to the evaluation of IC50 values for sodium dodecyl sulfate as a model toxicant, which yielded similar values to those obtained with each assay independently.

Cell Survival↗
PubMedDate not supplied

Quantitative structure-retention relationship study of tetrazolium salts on alumina support.

The retention of 7 monotetrazolium and 9 ditetrazolium salts was determined on alumina and reversed-phase (RP) alumina layers using n-hexane-2-propanol and water-2-propanol mixtures as eluents. The retention capacity and the specific surface area of solutes in contact with the stationary phases were calculated. Quantitative structure-retention relationship calculations indicated that the retention capacity of solutes on RP alumina layers depended not only on the molecular hydrophobicity but also on the hydrogen-donor and acceptor properties. Specific surface areas were related to the electronic and steric parameters of the solutes. Calculations suggested that the retention on both alumina and RP alumina layers is of mixed character, hydrophobic, electronic and steric parameters are equally involved in the retention.

Aluminum Oxide↗
PubMedDate not supplied

MCF-7 cell cycle arrested at G1 through ursolic acid, and increased reduction of tetrazolium salts.

The effect of ursolic acid on the proliferation of MCF-7 human breast tumor cells was studied. During investigations of the anti-proliferative effects of this triterpene, we observed a clear difference between MTT colorimetric assay and direct cell counting, particularly 24 h after drug treatment. The MTT assay showed a stimulation of formazan production in the first 24 h exposure of cells to drug. The maximum stimulation was obtained with 15 and 20 microM of ursolic acid (about 30 - 40% of increase with respect to control); however, the number of cells was not increased as revealed by direct cell counting. Ursolic acid is a potent inhibitor of MCF-7 cell proliferation. This triterpene exhibits both cytostatic and cytotoxic activity. It exerts an early cytostatic effect at G1 followed by cell death. Cell cycle analysis is performed by propidium iodide staining and flow cytometry technique. 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.

Antineoplastic Agents, Phytogenic↗
PubMed1995

The MTT tetrazolium salt assay scrutinized: how to use this assay reliably to measure metabolic activity of cell cultures in vitro for the assessment of growth characteristics, IC50-values and cell survival.

The 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazoliumbromide (MTT) assay is widely used for in vitro measurement of the metabolic viability of cell cultures subjected to different culture conditions. This convenient assay, which is based on the ability of viable cells to produce formazan, can be affected significantly by a number of conditions. These conditions can be roughly divided into groups, firstly influences which affect the spectrum of the produced formazan and secondly influences which affect the amount of formazan produced per cell. We studied the various chemical and biochemical aspects involved in the MTT assay. Our data indicated that microscopical viewing of cell cultures before and after performing the assay, a medium renewal with a well-defined MTT-incubation medium at the end of the culture period and regular cell counting are essential steps to ensure a reliable performance of the MTT assay. In conclusion, providing the necessary precautions are taken, the MTT assay can be used reliably to measure metabolic activity of cell cultures in vitro for the assessment of growth characteristics, IC50-values and cell survival.

Cell Division↗
PubMed2004

Identification of cytochrome P450-reductase as the enzyme responsible for NADPH-dependent lucigenin and tetrazolium salt reduction in rat epididymal sperm preparations.

Lucigenin-dependent chemiluminescence and WST-1 reduction can be detected following addition of NADPH to many cell types, including rat epididymal sperm suspensions. Although many reports suggest that such a phenomenon is due to reactive oxygen species production, other probes-such as MCLA and luminol-that are capable of detecting reactive oxygen metabolites do not produce a chemiluminescent signal in this model system. Our aim was to purify and identify the enzyme catalyzing the NADPH-dependent lucigenin and WST-1 reduction from rat epididymal spermatozoa preparations. Here, we show the identity of this enzyme as cytochrome P450-reductase. In support of this, a homogenous preparation of this protein was capable of reducing lucigenin and WST-1 in the presence of NADPH. Moreover, COS-7 cells overexpressing cytochrome P450-reductase displayed a 3-fold increase in the aforementioned activity compared with mock-transfected cells. Immunolocalization studies and biochemical analysis suggest that the majority of the NADPH-lucigenin activity is localized to the epithelial cells present within the epididymis. These results emphasize the importance of the direct NADPH-dependent reduction of superoxide-sensitive probes by cytochrome P450-reductase even though this enzyme does not, on its own accord, produce reactive oxygen species.

Acridines↗