Synergistic effect of PEG-400 and cyclodextrin to enhance solubility of progesterone

Conclusion  PEG-400, polysorbate 80, and 2 CDs (Trappsol HPB and Captisol) were used in an attempt to improve the aqueous solubility of a model hydrophobic drug, progesterone. The aqueous solubility of progesterone improved significantly from 0.007 mg/mL by the addition of PEG-400, CDs, and polysorbate 80. In systems containing various amounts of PEG-400 and 3% Trappsol HPB in water (% wt/wt), the theoretical solubility was calculated by adding the solubilities in the individual systems. The observed solubility values were up to 96% higher than the theoretical values. The effect of synergism was significant in 5% to 50% PEG-400/water systems containing Trappsol HPB. Systems containing Captisol did not show such synergistic effects. In general, the addition of polysorbate 80 to the PEG-400/water systems containing CDs affected synergism negatively.     

Effects of parathyroid hormone on Wnt signaling pathway in bone

The Wnt signaling pathway has recently been demonstrated to play an important role in bone cell function. In previous studies using DNA microarray analyses, we observed a change in some of the molecular components of the canonical Wnt pathway namely, frizzled-1 (FZD-1) and axil, in response to continuous parathyroid hormone (PTH) treatment in rats. In the present study, we further explored other components of the Wnt signaling pathway in rat distal metaphyseal bone in vivo, and rat osteoblastic osteosarcoma cells (UMR 106) in culture. Several Wnt pathway components, including low-density lipoprotein-receptor-related protein 5 (LRP5), LRP6, FZD-1, Dickkopf-1 (Dkk-1), and Kremen-1 (KRM-1), were expressed in bone in vivo and in osteoblasts in vitro. Continuous exposure to PTH (1-38) both in vivo and in vitro upregulated the mRNA expression of LRP6 and FZD-1 and decreased LRP5 and Dkk-1. These effects in UMR 106 cells were associated with an increase in beta-catenin as measured by Western blots and resulted in functional activation (three to six-fold) of a downstream Wnt responsive TBE6-luciferase (TCF/LEF-binding element) reporter gene. Activation of the TBE6-luciferase reporter gene by PTH (1-38) in UMR 106 cells was inhibited by the protein kinase A (PKA) inhibitor, H89. Activation was mimicked by PTH (1-31), PTH-related protein (1-34), and forskolin, but both PTH (3-34) and (7-34) had no effect. These findings suggest that the effect of PTH on the canonical Wnt signaling pathway occurs at least in part via the cAMP-PKA pathway through the differential regulation of the receptor complex proteins (FZD-1/LRP5 or LRP6) and the antagonist (Dkk-1). Taken together, these results reveal a possible role for the Wnt signaling pathway in PTH actions in bone.     

Degradative potential of Stenotrophomonas strain HPC383 having genes homologous to dmp operon

A strain, Stenotrophomonas HPC383 is isolated from effluent treatment plant treating wastewater from pesticide industry; degrades various aromatic compounds (cresols, phenol, catechol, 4methyl-catechol and hydroquinone) and crude oil, as determined through HPLC and GC analysis. Culture HPC383 could degrade (%) various compounds (1 mM) from a mixture: phenol - 99, p-cresol - 100, 4-methylcatechol - 96 and hydroquinone - 43 within 48 h of incubation, whereas it took 7 days to degrade 94% of 0.5% crude oil. Gene locus dmpN, to identify phenol degrading capacity was determined by PCR followed by southern analysis. The sequenced DNA fragment exhibited 99% sequence similarity to phenol hydroxylase gene from Arthrobacter sp. W1 (FJ610336). Amino acid sequence analysis of phenol hydroxylase reveals it to belong to high-Ks (affinity constant) group. Application of HPC383 in bioremediation of aquatic and terrestrial sites contaminated with petrochemical has been suggested.     

Analysis of DNA curvature distribution in mycobacterial promoters using theoretical models

In this paper, 125 different mycobacterial promoters are analyzed for their DNA curvature distribution using several di- and tri-nucleotide dependent models of DNA curvature. Different models give similar behavior and therefore qualitative validation of the results. Mycobacterial promoters resembling the E. coli sigma(70) type have almost 81% (85%) sequences having medium and high curvature profiles using dinucleotide-dependent models. Non-E. coli sigma(70) type mycobacterial promoters have comparatively higher percent of low curvature profiles. Very few extended -10 promoters have low curvature profiles. Mycobacterial promoters having A(n)T(m) (n+m > or =3) tract in the upstream region of -35 box and repeated in phase with each other have high curvature profiles. M. smegmatis promoters have high curvature profiles compared to M. tuberculosis promoters.     

Glycogen synthase kinase 3beta phosphorylates Alzheimer's disease-specific Ser396 of microtubule-associated protein tau by a sequential mechanism

Phosphorylation of tau on S(396) was suggested to be a key step in the development of neurofibrillary pathology in Alzheimer's disease brain [Bramblett, G. T., Goedert, M., Jacks, R., Merrick, S. E., Trojanowski, J. Q., and Lee, V. M.-Y. (1993) Neuron 10, 1089-1099]. GSK3beta phosphorylates Ser(396) of tau in the brain by a mechanism which is not clear. In this study, when HEK-293 cells were cotransfected with tau and GSK3beta, GSK3beta co-immunoprecipitated with tau and phosphorylated tau on S(202), T(231), S(396), and S(400) but not on S(262), S(235), and S(404). Blocking phosphorylation on T(231), S(235), S(396), S(400), or S(404) did not prevent the subsequent phosphorylation on S(202) by GSK3beta. These data suggest that GSK3beta directly phosphorylates tau on S(202) (without requiring prephosphorylation). However, preventing phosphorylation on S(235), S(400), and S(404) prevented GSK3beta-dependent phosphorylation of T(231), S(396), and S(400), respectively. This indicates that phosphorylation of T(231), S(396), and S(400) by GSK3beta depends on a previous phosphorylation of S(235), S(400), and S(404), respectively. To examine S(396) phosphorylation, we analyzed phosphorylation of S(396), S(400), and S(404). Blocking phosphorylation of S(404) prevented the subsequent GSK3beta-dependent phosphorylation of both S(400) and S(396). When phosphorylation of S(404) was allowed but S(400) blocked, GSK3beta failed to phosphorylate S(396). Thus, GSK3beta phosphorylates S(396) by a two-step mechanism. In the first step, GSK3beta phosphorylates S(400) of previously S(404)-phosphorylated tau. This event primes tau for second-step phosphorylation of S(396) by GSK3beta. We conclude that GSK3beta phosphorylates tau directly at S(202) but requires the previous phosphorylation on S(235) to phosphorylate T(231). Phosphorylation of S(396), on the other hand, occurs sequentially. Once a priming kinase phosphorylates S(404), GSK3beta sequentially phosphorylates S(400) and then S(396).