2,4(5)-Diarylimidazoles: synthesis and biological evaluation of a new class of sodium channel blockers against hNa(v)1.2

A small family of novel 2,4(5)-diarylimidazoles were prepared through a simple and efficient synthesis and evaluated as potential inhibitors of hNa(v)1.2 sodium channel currents. One member of this series (4) exhibited profound inhibition of Na(v)1.2 currents, emerging as a promising lead compound for further structure-activity relationship studies for the development of novel sodium channel blockers.     

Iron dictates the virulence of <Emphasis Type="Italic">Pseudomonas aeruginosa</Emphasis> in urinary tract infections

Iron-limiting conditions have been reported to be prevalent in the milieu of urinary tract. In the present investigation, effect of iron on virulence of uropathogenic Pseudomonas aeruginosa in planktonic and biofilm cell mode was studied. Significant enhancement in elaboration of all the virulence traits along with increased adherence to uroepithelial cells and decreased phagocytosis of P. aeruginosa was observed following growth in iron-deplete medium. On the contrary, decrease in all these parameters except phagocytosis was observed when P. aeruginosa was grown in iron-rich medium. In vivo, P. aeruginosa grown in iron-deplete medium showed increased renal bacterial load and tissue pathology in a mouse model of ascending urinary tract infection compared with organisms grown in iron-replete medium. The results of the present study may help in understanding host–parasite interaction and in developing alternative preventive approach against P. aeruginosa induced urinary tract infections.     

Three-phase partitioning for simultaneous renaturation and partial purification of Aspergillus niger xylanase

Three-phase partitioning (TPP) is carried out by mixing ammonium sulfate and t-butanol to obtain organic phase, interfacial precipitate and aqueous phase. It is shown that TPP of an 8 M urea/100 mM dithiothreitol-denatured xylanase preparation resulted in simultaneous renaturation and purification. This integrated novel approach gave recovery of 93% enzyme activity with 21-fold purification. The implications of this in the context of recovering activity from inclusion bodies are discussed.     

Adenosine receptors regulate exosome production

Exosomes, small-sized extracellular vesicles, carry components of the purinergic pathway. The production by cells of exosomes carrying this pathway remains poorly understood. Here, we asked whether type 1, 2A, or 2B adenosine receptors (A₁Rs, A_2ARs, and A_2BRs, respectively) expressed by producer cells are involved in regulating exosome production. Preglomerular vascular smooth muscle cells (PGVSMCs) were isolated from wildtype, A₁R^?/?, A_2AR^?/?, and A_2BR^?/? rats, and exosome production was quantified under normal or metabolic stress conditions. Exosome production was also measured in various cancer cells treated with pharmacologic agonists/antagonists of A₁Rs, A_2ARs, and A_2BRs in the presence or absence of metabolic stress or cisplatin. Functional activity of exosomes was determined in Jurkat cell apoptosis assays. In PGVSMCs, A₁R and A_2AR constrained exosome production under normal conditions (p?=?0.0297; p?=?0.0409, respectively), and A₁R, A_2AR, and A_2BR constrained exosome production under metabolic stress conditions. Exosome production from cancer cells was reduced (p?=?0.0028) by the selective A_2AR agonist CGS 21680. These exosomes induced higher levels of Jurkat apoptosis than exosomes from untreated cells or cells treated with A₁R and A_2BR agonists (p?=?0.0474). The selective A_2AR antagonist SCH 442416 stimulated exosome production under metabolic stress or cisplatin treatment, whereas the selective A_2BR antagonist MRS 1754 reduced exosome production. Our findings indicate that A_2ARs suppress exosome release in all cell types examined, whereas effects of A₁Rs and A_2BRs are dependent on cell type and conditions. Pharmacologic targeting of cancer with A_2AR antagonists may inadvertently increase exosome production from tumor cells.

     

Auxin-induced Fruit Set in Capsicum annuum L. Requires Downstream Gibberellin Biosynthesis

A hierarchical scheme for the central role of the plant hormones auxin and gibberellins in fruit set and development has been established for the model plants Arabidopsis and tomato. In the fruit crop Capsicum annuum, the importance of auxin as an early signal in fruit set has also been recognized; however, the effect of gibberellins and their interaction with auxin has not yet been studied. The aim of this study was to determine the role of gibberellin and the hierarchy between auxin and gibberellin. We applied gibberellin alone or in combination with auxin or with the gibberellin biosynthesis inhibitor paclobutrazol on stigmas of emasculated flowers. Gibberellin application enhanced fruit set, whereas application of paclobutrazol reduced fruit set. The effect of paclobutrazol treatment could be counteracted by coapplication of gibberellin but not by auxin_. These results indicate that in C. annuum, like in Arabidopsis and tomato, auxin is the major inducer of fruit set that acts in part by inducing gibberellin biosynthesis. Interestingly, gibberellin does not significantly contribute to the final fruit size but seems to play an important role in preventing flower and fruit abscission, a major determinant of production loss in C. annuum. At the same time, gibberellin together with auxin seems to balance cell division and cell expansion during fruit growth.     

Involvement of Microtubules in the Regulation of Bcl2 Phosphorylation and Apoptosis through Cyclic AMP-Dependent Protein Kinase

The Bcl2 family of proteins plays a significant role in regulation of apoptosis. In this study, the microtubule-damaging drugs paclitaxel, vincristine, and vinblastine induced Bcl2 hyperphosphorylation and apoptosis in MCF-7 and MDA-MB-231 cells and reduced Bcl2-Bax dimerization. Paclitaxel or vincristine induced increased expression of Bax, while overexpression of Bcl2 in these cell lines counteracted the effects of low doses of these drugs. In addition, paclitaxel- and vincristine-induced activation of cyclic AMP (cAMP)-dependent protein kinase (protein kinase A [PKA]) induced Bcl2 hyperphosphorylation and apoptosis, which were blocked by the PKA inhibitor Rp diastereomers of cAMP (Rp-cAMP). This finding suggests that activation of PKA due to microtubule damage is an important event in Bcl2 hyperphosphorylation and induction of apoptosis. These microtubule-damaging drugs caused growth arrest in G₂-M phase of the cell cycle and had no effect on p53 induction, suggesting that hyperphosphorylation mediated inactivation of Bcl2 and apoptosis without the involvement of p53. By comparison, the DNA-damaging drugs methotrexate and doxorubicin had no effect on Bcl2 hyperphosphorylation but induced p53 expression. Interestingly, paclitaxel or vincristine induced activation of caspase 3 and cleavage of poly(ADP-ribose) polymerase downstream of Bcl2 hyperphosphorylation. These data suggest that there may be a signaling cascade induced by agents that disrupt or damage the cytoskeleton that is distinct from (i.e., p53 independent), but perhaps related to (i.e., involves kinase activation and leads to apoptosis), the cellular response to DNA damage.     

Macrophage inflammatory protein-2, neutrophil recruitment and bacterial persistence in an experimental mouse model of urinary tract infection

This study analyzed macrophage inflammatory protein-2 (MIP-2) production and neutrophil recruitment in urinary tract in response to Pseudomonas aeruginosa in an ascending model of urinary tract infection (UTI) in mice. Both planktonic and biofilm cells of P. aeruginosa were used for inducing UTI in mice. MIP-2 levels determined in urine, bladder and kidney showed maximum MIP-2 production 6 h postinfection, which correlated with neutrophil recruitment. Biofilm cells showed significantly more MIP-2 production and neutrophil recruitment. However, no correlation between bacterial numbers and neutrophil recruitment was observed in urine and kidney tissue. The role of MIP-2 and neutrophils in relation to the persistence of P. aeruginosa in the urinary tract of mice is discussed.     

Bitter gourd proteinase inhibitors: potential growth inhibitors of Helicoverpa armigera and Spodoptera litura

Proteinase inhibitors (PIs) from the seeds of bitter gourd (Momordica charantia L.) were identified as strong inhibitors of Helicoverpa armigera gut proteinases (HGP). Biochemical investigations showed that bitter gourd PIs (BGPIs) inhibited more than 80% HGP activity. Electrophoretic analysis revealed the presence of two major proteins (BGPI-1 and-2) and two minor proteins (BGPI-3 and-4) having inhibitory activity against both trypsin and HGP. The major isoforms BGPI-1 and BGPI-2 have molecular mass of 3.5 and 3.0 kDa, respectively. BGPIs inhibited HGP activity of larvae fed on different host plants, on artificial diet with or without added PIs and proteinases excreted in fecal matter. Degradation of BGPI-1 by HGP showed direct correlation with accumulation of BGPI-2-like peptide, which remained stable and active against high concentrations of HGP up to 3 h. Chemical inhibitors of serine proteinases offered partial protection to BGPI-1 from degradation by HGP, suggesting that trypsin and chymotrypsin like proteinases are involved in degradation of BGPI-1. In larval feeding studies, BGPIs were found to retard growth and development of two lepidopteran pests namely Helicoverpa armigera and Spodoptera litura. This is the first report showing that BGPIs mediated inhibition of insect gut proteinases directly affects fertility and fecundity of both H. armigera and S. litura. The results advocate use of BGPIs to introduce insect resistance in otherwise susceptible plants.     

Production of Cellulase-Free Xylanase from Bacillus megaterium by Solid State Fermentation for Biobleaching of Pulp

Xylanase production from B. megaterium was enhanced using solid state fermentation with respect to the use of solid substrate, moistening solution, moisture content, inoculum, sugars, soyabean meal, amino acids, and extraction with surfactant. An increase of ≈423-fold in xylanase production and complete suppression of CMCase production was achieved over submerged liquid fermentation. Biobleaching using this cellulase-free xylanase, 8 U/g of oven dried pulp of 10% consistency, showed 8.12% and 1.16% increase in brightness and viscosity, 13.67% decrease in kappa number, and 31% decrease in chlorine consumption at the CD stage.