Lysis of human monocytic leukemia cells by extracellular adenosine triphosphate: mechanism and characterization of the adenosine triphosphate receptor

The present study shows that extracellular adenosine triphosphate (ATP) has the capacity to mediate dose-dependent lysis of the monocytic leukemia cell line THP-1. The lysis, assessed by 51Cr release, was found to be selective for ATP, because adenosine diphosphate (ADP) or other nucleotides were less effective in their ability to lyse the cells. The amount of 51Cr released was particularly enhanced by the stimulation of the cells with 1,000 U/mL of interferon gamma (IFN-gamma) for 3 days, and the sensitivity was time and dose dependent. Analysis of the mechanism of lysis indicated that the fully ionized form, ATP4-, mediated the lysis, because the addition of cation chelators or the absence of the divalent cations, Ca2+ and Mg2+, in the culture medium of a 6-hour 51Cr release assay increased the percent specific lysis. Therefore, the ATP receptors on THP-1 cells were classified as P2Z purinoceptors. Moreover, it is shown here that the Ca2+/calmodulin complex plays a role in the regulation of the lysis by extracellular ATP of THP-1 cells, because antagonists of this complex, such as trifluoperazine or KN-62, were found to inhibit the ATP-mediated cell lysis.     

The uptake of fenbendazole by cattle and buffalo following long-term low-level administration in urea-molasses blocks: further studies on block formulations

Fenbendazole (Hoechst India Ltd.) was incorporated at 0.5 g/kg into urea molasses blocks made by two different processes. The proportion of the drug remaining in the blocks and the plasma concentrations of the parent compound and its metabolites were measured. Recovery of the drug in blocks made by the cold and the modified hot processes was 90% and 96%, respectively. The plasma metabolite profile revealed a plateau between days 4 and 6 of feeding in cattle and buffalo. However, the plasma concentrations of fenbendazole and its metabolites were low in buffalo compared to cattle.     

Effect of Nb doping on structural and electric properties of PZT (65/35) ceramic

The aim of this study is to determine the effect of Nb⁵⁺ doping on PZT (65/35) based bulk materials in their structure, micro structure and electrical properties. The Nb content was chosen 0-9 mole%. These materials were prepared by conventional mixed oxide method. X ray diffraction studies suggest the compound to be of rhombohedral perovskite phase. Excess addition of Nb result in pyrochlore and fluorite phase develops in PZT (65/35) sample. Detailed studies of dielectric constant as a function of temperature (40degC to 500degC) and frequency (100 Hz to 1 MHz) suggest that the compounds undergo diffuse type of phase transition. Maximum dielectric constant and resistivity were found to be strongly dependent on doping and measuring frequencies. Using complex impedance analysis micro structural parameters such as bulk and grain boundary resistance, bulk charge carrier concentration and relaxation time were determined     

A green route for the acylation of resorcinol with acetic acid

2',4'-Dihydroxyacetophenone, also known as resoacetophenone, is a commercially important intermediate which is generally prepared by the acylation of resorcinol with acetic acid in the presence of a molar excess of zinc chloride, which leads to waste disposal problems. The most frequently used acylating agents such as acetic anhydride and acetyl chloride have several disadvantages and need to be replaced by cheap and benign agents. In this connection, acetic acid is a better choice but with a non-polluting and reusable catalyst. The synthesis of 2',4'-dihydroxyacetophenone from resorcinol and acetic acid was carried out in the presence of a variety of solid acid catalysts such as montmorillonite clay (K-10), dodecatungstophosphoric acid (DTP) supported on K-10, sulfated zirconia and ion exchange resins. Amongst these catalysts, Amberlyst-36, an ion exchange resin, was found to be the most effective. The effects of various parameters on the rate of reaction and selectivity were investigated to establish the intrinsic kinetics of the reaction. It was possible to deduce the adsorption equilibrium constant and rate constant simultaneously for the reaction including the corresponding energies of activation. The catalyst is reusable. The process is in consonance with the principles of green chemistry. Electronic Publication