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At least 73 records · Page 4Linked to original sources
PubMed1975

Direct spectrophotometric observation of intracellular nitro-blue tetrazolium and its formazan by multiple internal reflectance infrared spectroscopy.

A technique is described which permits the direct, infrared (IR) spectrophotometric observation of peripheral leukocytes by utilizing multiple internal reflectance (MIR) spectroscopy on zinc selenide prisms. The IR spectra of nitro-blue tetrazolium (NBT) and its derivative, nitro-blue diformazan (NBF), are described and examined and these spectra are compared with those of the intracellular NBT and NBF yielding several peaks which may prove to be analytically useful. Additionally, the presence of unreduced NBT in leukocytes is demonstrated, which microscopic and chemical "NBT tests" have not previously done.

Formazans↗
PubMed1994

Anti-proliferative effects of deflazacort on Nb2 cells as quantitated by formazan production.

Prolactin and other lactogenic hormones are mitogenic for the rat T-cell lymphoma line, Nb2. Glucocorticoids have antiproliferative effects on these cells. A limiting feature of experiments utilizing the Nb2 line is their labor-intensive nature. We therefore adapted the commonly used MTT dye proliferation assay for the Nb2 cell line. While rPRL, hPRL, oPRL, hGH, bPL, and to a lesser extent bPRL stimulated the Nb2 cells, hormones without lactogenic activity, rGH and oGH did not. Human serum and rat sera from animals bearing a PRL-secreting tumor stimulated the Nb2 cells in parallel to standards. Glucocorticoids had anti-proliferative effects on Nb2 cells in the presence of half-maximal or maximal PRL doses, as measured by the MTT proliferation assay. It has been claimed that an oxazoline steroid, deflazacort, has anti-inflammatory effects in clinical studies with fewer of the deleterious side-effects common to glucocorticoids. We therefore compared the in vitro anti-proliferative effects of deflazacort with other glucocorticoids. Deflazacort's negative effect on Nb2 cell proliferation was similar to that of cortisol and prednisolone and less than that of dexamethasone. We conclude that the MTT proliferation assay can be used to study both mitogenic and anti-proliferative substances in Nb2 cells. In addition we found that deflazacort acts similarly in vitro to other glucocorticoids.

Animals↗
PubMed2000

Analysis of anionic metallized azo and formazan dyes by capillary electrophoresis-mass spectrometry.

Capillary electrophoresis-mass spectrometry was applied to the separation of several anionic dyes containing copper(II), chromium(III), or cobalt(III) as part of the dye molecule. The dyes were separated using a 110 cm x 50 microm uncoated fused-silica capillary and a 5 mM ammonium acetate buffer (pH 9) containing 40% acetonitrile. Excellent separation efficiencies (N = 500,000 plates/column) and low detection limits of 20-50 pg (selected ion monitoring, S/N = 10) were achieved. Mass spectra were acquired at different cone voltages. At low cone voltages (low collision energies), sensitivity was maximized and the mass spectra contained only signals of the (multiply charged) molecular ions and low levels of sodium ion and proton adducts. At higher cone voltages, the 2:1 (ligand:metal) chromium and cobalt dyes showed losses of one of the two dye ligands, accompanied by a reduction of the metal. The copper dyes showed signals due to loss of SO2 and SO3-, but no release of metal. Azo cleavage, otherwise typical of azo dyes, was not observed with the metallized dyes.

Anions↗
PubMed1991

The tetrazolium-formazan system: design and histochemistry.

Our increasing knowledge about the chemistry and the correlations between chemical structure and histochemical properties of the tetrazolium/formazan system is resulting in: a better understanding of existing histochemical tetrazolium techniques; the selection of optimal tetrazolium salts for qualified use in histochemistry, cytochemistry and biochemistry; both qualitative and quantitative improvements in histochemical techniques for purposes demonstrating the activities of various dehydrogenating enzymes; an extended insight into the "state" of the tested biological object by means of tetrazolium indicators with special properties; and the combination of histochemical enzyme determination with further morphological techniques. This article has attempted to illustrate the progress in the use of the tetrazolium/formazan-system for histochemical purposes.

Formazans↗
PubMed2003

Utility of formazans and cetylpyridinium chloride in rapid spectrophotometric determination of zinc in biological materials and pharmaceutical formulations.

A facile, rapid and sensitive spectrophotometric method for the determination of zinc is performed, based on complexation reaction between the metal ion and 1,5-diphenyl-3-acetylformazan (I) 1-(o-carboxyphenyl)-3-acetyl-5-acetylformazan (II), 1-(o-carboxyphenyl)-3-acetyl-5-phenylformazan (III), and 1-(o-carboxyphenyl)-3-acetyl-5-m-tolylformazan (IV) in the presence of cationic surfactant cetylpyridinium chloride (CPC). The important analytical parameters and their effects on the reported system are investigated. Zinc reacts with the reagents (I-IV) and CPC in the ratio 1:1:2 (metal:reagent:CPC) in the pH range 8.5, 7.5, 5.5 and 6.5 to form a ternary complex with an absorption maximum 616, 656, 672 and 599 nm, respectively. The reaction was extremely rapid at room temperature, and the absorbance value remains unchanged for at least 1 week. The apparent stability constant of the complex were found to be 13.1 9.2, 11.4 and 12.3, and adheres to Beer's law for 0.05-3.50 microg per 10 ml of zinc. For more accurate analysis, Ringbom optimum concentration range was found from 0.08 to 3.20 microg per 10 ml of zinc. The apparent molar absorptivity, Sandell sensitivity, detection and quantification limits are also calculated. Taking a constant concentration of metal ion and determining its concentration in the presence of large number of foreign ions tested the effect of foreign ions. The method was applied for determination of zinc in serum, human hair and pharmaceutical formulations, where excellent agreements between reported and obtained results were achieved. The relative standard deviation was better than 1.67%.

Calibration↗
PubMed2002

Design, synthesis and biological activity of novel non-peptidyl endothelin converting enzyme inhibitors, 1-phenyl-tetrazole-formazan analogues.

A novel non-peptidyl endothelin converting enzyme inhibitor was obtained through a pharmacophore analysis of known inhibitors and three-dimensional structure database search. Analogues of the new inhibitor were designed using the structure-activity relationship of known inhibitors and synthesized. In anesthetized rats, intraperitoneal administration of the analogues suppressed the pressor responses induced by big endothelin-1.

Animals↗
PubMed1979

Improvement of the glucose oxidase immunoenzyme technic. Use of a tetrazolium whose formazan is stable without heavey metal chelation.

Glucose oxidase immunoenzymatic localization provides a simple way to show antigens in mammalian tissues, with no need for the quenching of endogenous nonspecific staining. The method is useful for the demonstration of many antigens in formalin-fixed, paraffin-embedded tissues. Improvement of this technic by the use of p-nitro blue tetrazolium chloride (NBT) as the disclosing reagent provides a stable, finely grained localization not possible with the previously used thiazolyl blue (MTT). The described modification makes available an ideal immunoenzymatic stain for the study of tissues at the level of the light microscope. This stain is especially useful for the examination of tissues with hemorrhagic or inflammatory lesions, since there is no endogenous background staining. Slides are permanent, and the technic can be used with peroxidase-labeled antibody to localize two antigens in the same tissue.

Animals↗
PubMed2005

Enumeration of respiring Pseudomonas spp. in milk within 6 hours by fluorescence in situ hybridization following formazan reduction.

Respiring Pseudomonas spp. in milk were quantified within 6 h by fluorescence in situ hybridization (FISH) with vital staining. FISH with an oligonucleotide probe based on 16S rRNA sequences was used for the specific detection of Pseudomonas spp. at the single cell level. 5-cyano-2,3-ditolyl tetrazolium chloride (CTC) was used to estimate bacterial respiratory activity. The numbers of respiring Pseudomonas cells as determined by FISH with CTC staining (CTC-FISH) were almost the same or higher than the numbers of CFU as determined by the conventional culture method.

Animals↗