Enantioselective synthesis and cytotoxic evaluation of 4,5-dihydro-5-[aryl(hydroxy)methyl]-3-methylidenefuran-2(3H)-ones

A series of enantiomerically enriched 4,5-dihydro-5-[aryl(hydroxy)methyl]-3-methylidenefuran-2(3H)-ones (8) were synthesized by means of asymmetric Sharpless dihydroxylation of the 2-phosphorylated 5-aryl-pent-4-enoic acids 13, followed by Horner-Wadsworth-Emmons reaction of the resulting furanones 15 (Scheme 2). An enantiomeric excess (ee) of 20-95% was achieved for compounds 8, and their absolute configurations were determined by the Mosher ester method. Cytotoxic evaluation against L-1210 and HL-60 leukemia cell lines revealed that the target compounds 8 are active in the micromolar concentration range (Table 2). Thereby, significant differences in activity between the corresponding enantiomers were observed for the HL-60 cell line.     

The structure of Yersinia pestis V-antigen, an essential virulence factor and mediator of immunity against plague

The LcrV protein (V-antigen) is a multifunctional virulence factor in Yersinia pestis, the causative agent of plague. LcrV regulates the translocation of cytotoxic effector proteins from the bacterium into the cytosol of mammalian cells via a type III secretion system, possesses antihost activities of its own, and is also an active and passive mediator of resistance to disease. Although a crystal structure of this protein has been actively sought for better understanding of its role in pathogenesis, the wild-type LcrV was found to be recalcitrant to crystallization. We employed a surface entropy reduction mutagenesis strategy to obtain crystals of LcrV that diffract to 2.2 A and determined its structure. The refined model reveals a dumbbell-like molecule with a novel fold that includes an unexpected coiled-coil motif, and provides a detailed three-dimensional roadmap for exploring structure-function relationships in this essential virulence determinant.     

Augmentation of hypoxic respiration after brief hyperoxia in the anesthetized cat: Putative function of GABA<Subscript>A</Subscript> neurotransmission

In this study, we attempted to determine the role of GABA neurotransmission in augmentation of hypoxic respiration by antecedent hyperoxic breathing. The experiments were performed in anesthetized, paralyzed and vagotomized cats divided into control and bicuculline (a GABA_A receptor blocker)-injected groups. The experimental protocol consisted of exposing the animals to successive hypoxic-hyperoxic-hypoxic conditions. Respiration was assessed using phrenic electroneurograms, from which the peak phrenic height, a surrogate of the tidal volume component, and respiratory rate were obtained, and their product, the respiratory minute output, was calculated. We found that prior hyperoxic ventilation increased the subsequent respiratory response to hypoxia by an average of 23.5%, compared with the preoxygen response. This increase was driven by volume respiration. The biphasic character of the hypoxic respiratory response, consisting of stimulatory and depressant phases, was sustained. Bicuculline abolished the augmentative effect on hypoxic respiration of prior hyperoxia, which suggests that oxygenation induces GABA_A-mediated hyperexcitability of respiratory neurons, possibly by the liberation of reactive oxygen species. We concluded that GABA neurotransmission is pertinent to the effect of hyperoxia on hypoxic respiratory reactivity.     

Binding of the new morphiceptin analogs to human MCF-7 breast cancer cells and their effect on growth

In the present study, we reported on the synthesis of two new mu-opioid peptide analogs, [D-1-Nal3]morphiceptin and [D-1-Nal4]-morphiceptin [1-Nal=3-(1-naphthyl)-alanine] which expressed receptor binding affinities at least at the level of the primary opioid ligands. The new analogs also labeled mu-opioid receptors on the cells of human breast cancer MCF-7 cell line with affinity much higher than that of endomorphins and morphiceptin, the well-known mu-selective opioid peptides. However, none of the tested peptides significantly decreased cell proliferation of MCF-7 cells.     

The elicitor-induced oxidative processes in leaves of Solanum species with differential polygenic resistance to Phytophthora infestans

Previous studies have shown that suspension-cultured cells of Solanum genotypes with various polygenic resistances to Phytophthora infestans differed in activities of early oxidative processes in response to culture filtrate (CF) from this pathogen. These studies have now been extended by analysing production of reactive oxygen species (ROS), lipid peroxidation and Lipoxygenase (LOX, E.C.1.13.11.12) activity induced by CF in detached leaves of S. tuberosum cv Bzura and clone H-8105, polygenically resistant and susceptible, respectively, as well as S. nigrum, nonhost, completely resistant. The relative increase in the ROS production was higher in the susceptible clone H-8105 than in both resistant genotypes. Lipid peroxidation increased only in the nonhost S. nigrum. An increase in lipid peroxidation in S. nigrum leaves coincided with enhanced LOX activity. In both S. tuberosum genotypes, significant increases in LOX activity were delayed and unaccompanied by changes in the level of lipid peroxidation. LOX activity attained a higher level in both of the resistant genotypes than in the susceptible one. The present results suggest that the involvement of both ROS production and LOX activity in the defense strategy in Solanum species/P. infestans interactions.     

Origin, distribution and 3D-modeling of Gr-EXPB1, an expansin from the potato cyst nematode Globodera rostochiensis

Southern analysis showed that Gr-EXPB1, a functional expansin from the potato cyst nematode Globodera rostochiensis, is member of a multigene family, and EST data suggest expansins to be present in other plant parasitic nematodes as well. Homology modeling predicted that Gr-EXPB1 domain 1 (D1) has a flat beta-barrel structure with surface-exposed aromatic rings, whereas the 3D structure of Gr-EXPB1-D2 was remarkably similar to plant expansins. Gr-EXPB1 shows highest sequence similarity to two extracellular proteins from saprophytic soil-inhabiting Actinobacteria, and includes a bacterial type II carbohydrate-binding module. These results support the hypothesis that a number of pathogenicity factors of cyst nematodes is of procaryotic origin and were acquired by horizontal gene transfer.     

Genetic immunization of ducks for production of antibodies specific to Helicobacter pylori UreB in egg yolks

Following genetic immunization of laying ducks with a plasmid expressing Helicobacter pylori UreB (large subunit of urease), IgY against UreB were obtained from egg yolks. These polyclonal and monospecific IgY antibodies are of higher-titer and specifically recognize recombinant H. pylori urease purified from Escherichia coli. To our knowledge this is the first report describing generation of IgY antibodies directed against antigens of H. pylori by DNA-based immunization.     

Preliminary study on the determination of selenium compounds in some selenium-accumulating mushrooms

Using various chromatographic techniques (size exclusion, anion exchange, and cation exchange) combined with several detectors (neutron activation analysis and atomic fluorescence spectrometry), an attempt was made to characterize selenium compounds in some edible, selenium-accumulating mushrooms (Albatrellus pes-caprae and Boletus edulis). The mushrooms contained mostly low-molecular-weight (6 kDa) selenium compounds. After proteolysis, only a small fraction of the extractable selenium could be identified as selenite (3.0–9.2%, Albatrellus pes-caprae), selenocystine (minor, Albatrellus pes-caprae; 7.5%, Boletus edulis), or selenomethionine (1.0%, Boletus edulis), leaving the form of the bulk still to be elucidated.     

Immunolocalization and expression of kinin B1R and B2R receptors in human inflammatory bowel disease

Bradykinin is a mediator of inflammation, responsible for pain, vasodilation, and capillary permeability. Bradykinin receptor 1 (B(1)R) and bradykinin receptor 2 (B(2)R) are G protein-coupled receptors that mediate kinin effects. The latter is constitutive and rapidly desensitized; the former is induced by inflammatory cytokines and resistant to densensitization. The distribution of bradykinin receptors in human intestinal tissue was studied in patients with inflammatory bowel disease (IBD), namely ulcerative colitis (UC) and Crohn's disease (CD). Both B(2)R and B(1)R proteins are expressed in the epithelial cells of normal and IBD intestines. B(1)R protein is visualized in macrophages at the center of granulomas in CD. B(2)R protein is normally present in the apexes of enterocytes in the basal area and intracellularly in inflammatory tissue. In contrast, B(1)R protein is found in the basal area of enterocytes in normal intestine but in the apical portion of enterocytes in inflamed tissue. B(1)R protein is significantly increased in both active UC and CD intestines compared with controls. In patients with active UC, B(1)R mRNA is significantly higher than B(2)R mRNA. However, in inactive UC patients, the B(1)R and B(2)R mRNA did not differ significantly. Thus bradykinin receptors in IBD may reflect intestinal inflammation. Increased B(1)R gene and protein expression in active IBD provides a structural basis of the important role of bradykinin in chronic inflammation.