[en] A new method is proposed for the determination of small amounts of zinc in metallic cadmium with Neotetrazolium chloride (NTC). It is based on the formation of ionic associations with the thiocyanate complexes of cobalt and of zinc. The blue cobalt ion associate is more soluble in water and organic solvents than the zinc ion associate. This characteristic leads to the conversion of the cobalt association into the zinc association, if zinc is added to the solution of the cobalt ion association. The concentration of the zinc introduced is proportional to the decrease in the light absorption of the cobalt ion association. Cadmium does not interfere with the determination. The smallest zinc content in cadmium that can still be determined is 0.003%. The relative standard deviation of the method is +-3.35%. (author)

[en] The ability to interact with live cells in vitro in combination with either sequential image acquisition or continuous force sensing provide the means for tracking the dynamics of intra- or inter-cell processes. The former operational mode is relatively slow and is most suitable for events where the temporal evolution takes place on a time scale of several minutes to hours. For instance, aspects of cytoskeletal dynamics, cell motility or conformational response to external stimuli fall into this category. In this study we demonstrate cell responses from exposure to cytochalasin, glutaraldehyde and a tetrazolium salt. Significant changes in mechanical properties and structural features are observed on time scales up to 3 hrs. In addition, comparative studies of cytoskeletal components of dried and living cells are undertaken

[en] In this paper, we discuss the influence of different factors on the measured values of dehydrogenase activity. We focus on the incubation time of the sample and optimal 2,3,5-triphenyl-tetrazolium chloride concentration. We provide a comparison between results obtained from three methods: Casida method, standard method, and optimization method. Some disadvantages of traditional methods were critically discussed. We showed that the results of dehydrogenase activity determination strongly depend on the method used. To minimize these discrepancies, the increase in TPF concentration should be described with the kinetic model which allows determining tangent activity. Michaelis–Menten kinetics can be used to describe the relationship between TTC concentration and tangent activities. We suggest using the value of 4 km as the optimal TTC concentration.

[en] Integrin α5β1 immobilized on a ProteoChip was used to screen new antagonistic peptides from multiple hexapeptide sub-libraries of the positional scanning synthetic peptide combinatorial library (PS-SPCL). The integrin α5β1-Fibronectin interaction was demonstrated on the chip. A novel peptide ligand, A5-1 (VILVLF), with high affinity to integrin α5β1 was identified from the hexapeptide libraries with this chip-based screening method on the basis of a competitive inhibition assay. A5-1 inhibits the integrin-fibronectin interaction in a dose-dependent manner (IC₅₀; 1.56 ± 0.28 μM. In addition, it inhibits human umbilical vein endothelial cell proliferation, migration, adhesion, tubular network formation, and bFGF-induced neovascularization in a chick chorioallantoic membrane. These results suggest that A5-1 will be a potent inhibitor of neovascularization.

[en] The published data on the synthesis, physicochemical properties, structures and reactions of 1,3-(1,3,5)- and 1,4-(1,4,5)-substituted tetrazolium salts are systematised and generalised. Their applications as starting compounds in the preparative chemistry of heterocyclic derivatives and some other branches of science and technology are reviewed. The bibliography includes 122 references.

[en] The measurement of radiation survival using a clonogenic assay, the established standard, can be difficult and time consuming. In this study, We have used the MTT assay, based on the reduction of a tetrazolium salt to a purple formazan precipitate by living cells, as a substitution for clonogenic assay and have examined the optimal condition for performing this assay in determination of radiation sensitivity. Four human cancer cell lines - PCI-1, SNU-1066, NCI-H63O and RKO cells have been used. For each cell line, a clonogenic assay and a MTT assay using Premix WST-1 solution, which is one of the tetrazolium salts and does not require washing or solubilization of the precipitate were carried out after irradiation of 0, 2, 4, 6, 8, 10 Gy, For clonogenic assay, cells in 25 cm² flasks were irradiated after overnight incubation and the resultant colonies containing more than 50 cells were scored after culturing the cells for 10-14 days, For MTT assay, the relationship between absorbance and cell number, optimal seeding cell number, and optimal timing of assay was determined. Then, MTT assay was performed when the irradiated cells had regained exponential growth or when the non-irradiated cells had undergone four or more doubling times. There was minimal variation in the values gained from these two methods with the standard deviation generally less than 5%, and there were no statistically significant differences between two methods according to t-test in low radiation dose (below 6 Gy). The regression analyses showed high linear correlation with the R² value of 0.975-0.992 between data from the two different methods. The optimal cell numbers for MTT assay were found to be dependent on plating efficiency of used cell line. Less than 300 cells/well were appropriate for cells with high plating efficiency (more than 30%). For cells with low plating efficiency (less than 30%), 500 cells/well or more were appropriate for assay. The optimal time for MTT assay was alter 6 doubling times for the results compatible with those of clonogenic assay, at least after 4 doubling times was required for valid results. In consideration of practical limits of assay (12 days, in this study) cells with doubling time more than 3 days were inappropriate for application. In conclusion, it is found that MTT assay can successfully replace clonogenic assay of tested cancer cell lines after irradiation only if MTT assay was undertaken with optimal assay conditions that included plating efficiency of each cell line and doubling time at least

[en] To explore the effect of neamine on cell proliferation, migration, and invasion in H7402 human hepatoma cells.This study was conducted at the Institute of Genetics and Cytology, School of Life Science, Northeast Normal University, Changchun, China between October 2008 and February 2010. First, we employed the MTT (thiazol blue tetrazolium bromide) and soft agar assay to detect the effect of neamine on cell proliferation, and investigated the migration and invasion by using a transwell assay in H7402 cells. We, then, investigated nuclear translocation of angiogenin by immunofluorescence staining. Finally, we stable transfected H7402 cells with the plasmids pCI-Ang (+) and pCI-Ang (-), which contain the entire coding region of human angiogenin in the sense and antisense orientations, to obtain angiogenin under-expressing/over-expressing transfectants, and investigated the effect of neamine on angiogenin induced cell proliferation. The results showed that neamine positively inhibited the proliferation, migration, and invasion of H7402 cells. Nuclear translocation of angiogenin was blocked by neamine, and angiogenin-induced cell proliferation was inhibited by neamine.Neamine positively inhibited H7402 cells. Since the toxicity of neamine is much less than neomycin, and is close to that of streptomycin and kanamycin, it may serve as a lead agent for the development of hepatocellular carcinoma therapeutics (Author).

[en] Research highlights: → Real-time data acquisition by RT-CES requires low operative effort. → Time to result is reduced by using RT-CES instead of conventional methods. → RT-CES enables quantification of virus titers in unknown samples. → RT-CES is a useful tool for high-throughput characterization of antiviral agents. → An RT-CES-based virus neutralization test was established. -- Abstract: Impedance-based biosensing known as real-time cell electronic sensing (RT-CES) belongs to an emerging technology for analyzing the status of cells in vitro. In the present study protocols were developed for an RT-CES-based system (xCELLigence^TM, Roche Applied Science, ACEA Biosciences Inc.) to supplement conventional techniques in pox virology. First, proliferation of cells susceptible to orthopoxviruses was monitored. For virus titration cells were infected with vaccinia virus and cell status, represented by the dimensionless impedance-based cell index (CI), was monitored. A virus-dose dependent decrease in electrical impedance could be shown. Calculation of calibration curves at a suitable CI covering a dynamic range of 4 log enabled the quantification of virus titers in unknown samples. Similarly, antiviral effects could be determined as shown for anti-poxviral agents ST-246 and Cidofovir. Published values for the in vitro concentration that inhibited virus replication by 50% (IC₅₀) could be confirmed while cytotoxicity in effective concentrations was excluded in long-term incubation experiments. Finally, an RT-CES-based virus neutralization test was established. Various poxvirus-specific antibodies were examined for their neutralizing activity and a calculation mode for the neutralizing antibody titer was introduced. In summary, the presented RT-CES-based methods outmatch end-point assays by observing the cell population throughout the entire experiment while workload and time to result are reduced.

[en] The colourless radiochromic chloride salt of blue tetrazolium (BT²⁺) is reduced radiolytically to the deep violet-coloured formazan. Dosimeter films of this radiation sensor can be produced by dissolving polyvinyl alcohol (PVA) in a heated aqueous solution of the salt, and, upon cooling, by casting the solution on a horizontal glass plate. In the present development, the resulting flexible transparent film is readily stripped from the plate, with a thickness of 0.045 mm. Upon irradiation with gamma rays or electron beams, a permanent image is produced with a broad absorption band in the visible spectrum. The radiation response is approximately a linear function in terms of the increase in optical absorbance (ΔA) measured at λ_max 552 nm wavelength versus absorbed dose (D) over the range 5 to 50 kGy. The radiochromic image has a relatively high spatial resolution and can be used to register dose distributions and beam profiles. The value of ΔA shows a gradual increase for the first 24 hours after irradiation but is stable thereafter. The variation of response with irradiation temperature is negligible over the temperature range -20 deg. C to +30 deg. C, but displays a pronounced positive temperature dependence at higher temperatures. The response to gamma radiation shows negligible dose-rate dependence as long as the radiochromic sensor concentration in the PVA matrix is sufficiently high (> 6 % by weight). (author)

[en] The extraction equilibrium of the ternary ion-association complex of iodo-nitro-tetrazolium [3-(4-iodophenyl)2-(4-nitrophenyl)-5-phenyltetrazolium chloride] with the chlorocomplex of thallium(III) is investigated radiochemically. The molar ratio of the ion-associate is found to be 1:1, the association constant has a value of 3.2x10³ in aqueous solution and the distribution constant is 8.9. The extraction constant which gives a quantitative characterization of the equilibrium is 2.3x10⁴. From the investigation performed it can be concluded that a quite satisfactory extraction of thallium(III) by means of iodo-nitro-tetrazole in benzene can be carried out. The extraction constant has a relatively high value which allows to use this system conveniently for the extraction-photometric determination of thallium(III). (T.C.)