Conjugation to Nedd8 instigates ubiquitylation and down-regulation of activated receptor tyrosine kinases

When appended to the epidermal growth factor receptor (EGFR), ubiquitin serves as a sorting signal for lysosomal degradation. Here we demonstrate that the ubiquitin ligase of EGFR, namely c-Cbl, also mediates receptor modification with the ubiquitin-like molecule Nedd8. EGF stimulates receptor neddylation, which enhances subsequent ubiquitylation, as well as sorting of EGFR for degradation. Multiple lysine residues, located within the tyrosine kinase domain of EGFR, serve as attachment sites for Nedd8. A set of clathrin coat-associated binders of ubiquitin also bind Nedd8, but they undergo ubiquitylation, not neddylation. We discuss the emerging versatility of the concerted action of ubiquitylation and neddylation in the process that desensitizes growth factor-activated receptor tyrosine kinases.     

Synthesis and characterization of new micrometer-sized radiopaque polymeric particles of narrow size distribution by a single-step swelling of uniform polystyrene template microspheres for X-ray imaging applications

Radiopaque micron-sized non-cross-linked polystyrene/poly(2-methacryloyloxyethyl(2,3,5-triiodobenzoate)) particles of narrow size distribution were prepared by a single-step swelling of uniform polystyrene template microspheres with emulsion droplets of methylene chloride containing the initiator benzoyl peroxide and the iodinated monomer 2-methacryloyloxyethyl(2,3,5-triiodobenzoate), followed by the polymerization of the monomer within the swollen template particles at 73 degrees C. Radiopaque micron-sized uniform cross-linked polystyrene/poly(2-methacryloyloxyethyl(2,3,5-triiodobenzoate)-divinylbenzene) composite particles were prepared similarly with emulsion droplets of methylene chloride containing divinylbenzene, in addition to the initiator and the iodinated monomer. Radiopaque micron-sized uniform cross-linked poly(2-methacryloyloxyethyl(2,3,5-triiodobenzoate)-divinylbenzene) particles were formed by dissolving the template polystyrene polymer belonging to the former cross-linked composite particles. Characterization of these novel radiopaque polymeric particles was performed by methods such as FTIR, TGA, DSC, SEM, XPS, elemental analysis, and light microscopy. The influence of the weight ratio [2-methacryloyloxyethyl(2,3,5-triiodobenzoate)]/[polystyrene] and [2-methacryloyloxyethyl(2,3,5-triiodobenzoate)]/[divinylbenzene] on the bulk and surface properties of the non-cross-linked and cross-linked particles, respectively was elucidated. The radiopacity of these iodinated particles was demonstrated by an imaging technique based on X-ray absorption usually used in hospitals. These novel radiopaque particles may be used for different X-ray imaging needs, e.g., blood pool, body organs, embolization, dental composition, implants, protheses, and nanocomposites.     

Genome analysis of bovine-mastitis-associated Escherichia coli O32:H37 strain P4

Escherichia coli is a major pathogen of bovine intramammary infections. Here we report the first draft of the genome sequence of the E. coli O32:H37 P4 strain, which is widely used in experimental bovine mastitis studies.     

Antihyperglycaemic activity of 2,4:3,5-dibenzylidene-D-xylose-diethyl dithioacetal in diabetic mice

We have recently generated lipophilic D-xylose derivatives that increase the rate of glucose uptake in cultured skeletal muscle cells in an AMP-activated protein kinase (AMPK)-dependent manner. The derivative 2,4:3,5-dibenzylidene-D-xylose-diethyl dithioacetal (EH-36) stimulated the rate of glucose transport by increasing the abundance of glucose transporter-4 in the plasma membrane of cultured myotubes. The present study aimed at investigating potential antihyperglycaemic effects of EH-36 in animal models of diabetes. Two animal models were treated subcutaneously with EH-36: streptozotocin-induced diabetes in C57BL/6 mice (a model of insulin-deficient type 1 diabetes), and spontaneously diabetic KKAy mice (Kuo Kondo rats carrying the A(y) yellow obese gene; insulin-resistant type 2 diabetes). The in vivo biodistribution of glucose in control and treated mice was followed with the glucose analogue 2-deoxy-2-[(18) F]-D-glucose; the rate of glucose uptake in excised soleus muscles was measured with [(3) H]-2-deoxy-D-glucose. Pharmacokinetic parameters were determined by non-compartmental analysis of the in vivo data. The effective blood EH-36 concentration in treated animals was 2 μM. It reduced significantly the blood glucose levels in both types of diabetic mice and also corrected the typical compensatory hyperinsulinaemia of KKAy mice. EH-36 markedly increased glucose transport in vivo into skeletal muscle and heart, but not to adipose tissue. This stimulatory effect was mediated by Thr(172) -phosphorylation in AMPK. Biochemical tests in treated animals and acute toxicological examinations showed that EH-36 was well tolerated and not toxic to the mice. These findings indicate that EH-36 is a promising prototype molecule for the development of novel antidiabetic drugs.     

Poliovirus 2b insertion into lipid monolayers and pore formation in vesicles modulated by anionic phospholipids

Enterovirus 2B viroporin has been involved in membrane permeabilization processes occurring late during cell infection. Even though 2B lacks an obvious signal sequence for translocation, the presence of a Lys-based amphipathic domain suggests that this product bears the intrinsic capacity for partitioning into negatively charged cytofacial membrane surfaces. Pore formation by poliovirus 2B attached to a maltose-binding protein (MBP) has been indeed demonstrated in pure lipid vesicles, a fact supporting spontaneous insertion into and direct permeabilization of membranes. Here, biochemical evidence is presented indicating that both processes are modulated by phosphatidylinositol and phosphatidylserine, the main anionic phospholipids existing in membranes of target organelles. Insertion into lipid monolayers and partitioning into phospholipid bilayers were sustained by both phospholipids. However, MBP-2B inserted into phosphatidylserine bilayers did not promote membrane permeabilization and addition of this lipid inhibited the leakage observed in phosphatidylinositol vesicles. Mathematical modelling of pore formation in membranes containing increasing phosphatidylserine percentages was consistent with its inhibitory effect arising from a higher reversibility of MBP-2B surface aggregation. These results support that 2B insertion and pore-opening are mechanistically distinguishable events modulated by the target membrane anionic phospholipids.     

Indomethacin stimulation of macrophage cytostasis against MOPC-315 tumor cells is inhibited by both prostaglandin E2 and nordihydroguaiaretic acid,a lipoxygenase inhibitor

Summary Indomethacin enhanced macrophage cytostasis against MOPC-315 tumor cells in vitro. The effect of indomethacin was inhibited by prostaglandin E₂ and by the lipoxygenase inhibitor nordihydroguaiaretic acid. Prostaglandin E₂ and nordihydroguaiaretic acid also inhibited indomethacin stimulation of macrophage thymidine incorporation. Indomethacin inhibited macrophage prostaglandin E₂ formation and stimulated leukotriene B₄ synthesis. Nordihydroguaiaretic acid inhibited leukotriene B₄ production. Our data indicate that eicosanoids play a role in regulating macrophage cytostasis.     

Metaphor Identification in Large Texts Corpora

Identifying metaphorical language-use (e.g., sweet child) is one of the challenges facing natural language processing. This paper describes three novel algorithms for automatic metaphor identification. The algorithms are variations of the same core algorithm. We evaluate the algorithms on two corpora of Reuters and the New York Times articles. The paper presents the most comprehensive study of metaphor identification in terms of scope of metaphorical phrases and annotated corpora size. Algorithms’ performance in identifying linguistic phrases as metaphorical or literal has been compared to human judgment. Overall, the algorithms outperform the state-of-the-art algorithm with 71% precision and 27% averaged improvement in prediction over the base-rate of metaphors in the corpus.     

Modulation of Learning and Neuronal Membrane Composition in the Rat by Essential Fatty Acid Preparation: Time-Course Analysis

Previous studies have shown that chronic administration of SR-3 (a 1:4 mixture of -linolenic and linoleic acid) affects spatial learning, thermoregulation, pain threshold and protection from seizures. The mode of action is unknown. One possible explanation is that the preparation induces changes in the fatty acids profile and in the cholesterol level in the neuronal membrane. This study used 15 independent groups of rats (n = 12) which were given either saline, mineral oil (vehicle) or SR-3 (25 mg/kg) for 0, 1,2, 3, or 4 weeks. The learning performance was measured in the Morris Water tank and the fatty acids profile and the cholesterol level were examined by the GC method in synaptosomes obtained from the frontal cortex of the rats. SR-3 improved the learning performance and induced major changes in the neuronal membrane composition, such as an increase in the total level of fatty acids, an increase in the level of essential fatty acids and a decrease in the cholesterol level. Those changes occurred after 3 weeks of treatment. The biochemical variables can predict the behavioral variables but not vice versa. The changes in the neuronal membrane may result in a modification of the membrane fluidity, which may, in turn, enhance cognitive and neuropharmacological effects.