Ligands with polyfluorophenyl moieties promote a local structural rearrangement in the Spinach2 and Broccoli aptamers that increases ligand affinities.

The interaction of nucleic acids with their molecular targets often involves structural reorganization that may traverse a complex folding landscape. With the more recent recognition that many RNAs, both coding and noncoding, may regulate cellular activities by interacting with target molecules, it becomes increasingly important to understand how nucleic acids interact with their targets and how drugs might be developed that can influence critical folding transitions. We have extensively investigated the interaction of the Spinach2 and Broccoli aptamers with a library of small molecule ligands modified by various extensions from the imido nitrogen of DFHBI [(Z)-5-(3,5-difluoro-4-hydroxybenzylidene)-2,3-dimethyl-3,5-dihydro-4H-imidazol-4-one] that reach out from the Spinach2 ligand binding pocket. Studies of the interaction of these compounds with the aptamers revealed that polyfluorophenyl-modified ligands initiate a slow change in aptamer affinity that takes an extended time (half-life of ∼40 min) to achieve. The change in affinity appears to involve an initial disruption of the entrance to the ligand binding pocket followed by a gradual transition to a more defined structure for which the most likely driving force is an interaction of the gateway adenine with a nearby 2'OH group. These results suggest that polyfluorophenyl modifications might increase the ability of small molecule drugs to disrupt local structure and promote RNA remodeling.

Tetrabromobisphenol A and hexabromocyclododecane alter secretion of IL-1ß from human immune cells.

Tetrabromobisphenol A (TBBPA) and hexabromocyclododecane (HBCD), flame retardant compounds used in epoxy resin circuit boards and upholstery, contaminate the environment and are found in human serum. Lymphocytes and monocytes are immune cells that, among other functions, secrete pro-inflammatory cytokines such as interleukin (IL)-1ß, an important regulator of immune responsiveness and tissue growth and repair. Thus, if its levels are dysregulated, loss of proper immune function and increased invasiveness of tumors could ensue. This study examines whether exposures to varying concentrations (0.05-5.0 µM) of TBBPA and HBCD for 24 h, 48 h and 6 days interfere with the ability of immune cells to secrete IL-1ß. The immune cell preparations examined were human natural killer (NK) cells, monocyte-depleted (MD) peripheral blood mononuclear cells (MD-PBMC) and PBMC. Both increased and decreased secretion of IL-1ß from all three types of cell preparation were seen with TBBPA exposures and were dependent on concentration and length of exposure. TBBPA induced changes varied considerably from donor to donor. Exposure to HBCD from 0.5-5.0 µM caused increases in IL-1ß secretion after all lengths of exposures in all cell preparations. The specific HBCD levels at which increases occurred varied among donors. Examinations of the signaling pathway(s) responsible for the elevated secretion of IL-1ß after HBCD exposure were carried out in MD-PBMC cells. Results revealed that MAPK pathways (ERK1/2 and p38) appear to be the targets of HBCD that lead to increased IL-1ß secretion from immune cells.

Market Assessment and Product Evaluation of Probiotic Containing Dietary Supplements Available in Bangladesh Market.

Probiotics containing food supplements available in Bangladesh market were identified and collected for assessment. To assess their label claim, they were resuspended into sterile distilled water. Then, series dilutions of each sample solution were prepared and immediately plated out, in duplicate, into De Man Rogosa Sharpe (MRS) agar. These plates were then incubated at 37°C for 48 hours and colonies were counted. Viable cell numbers stated on the labels were compared with actual viable cell numbers. To assess the viability of the probiotics included in the products, probiotic strains were isolated from each of the four products and screened for inhibitory activity against six indicator strains. It was surprisingly found that although the viable cell numbers of all supplements were three to four log cycles lower than label claim of the products, however, this problem did not affect the inhibitory activity of the probiotic strains against indicator strains according to in vitro assessment. Legislation and regulation regarding prebiotic-probiotic containing products should be built up in Bangladesh to ensure quality products supply to the consumers. Moreover, manufacturers of probiotic containing products should take the responsibility for providing the consumer with scientifically and legally correct information.