Modulation of inflammatory responses by diterpene acids from Helianthus annuus L

Fractionation of a petroleum ether extract of Helianthus annuus L. led to the isolation of three diterpene acids: grandiflorolic, kaurenoic and trachylobanoic acids. These compounds were studied for potential anti-inflammatory activity on the generation of inflammatory mediators in lipopolysaccharide (LPS)-activated RAW 264.7 macrophages. At non-toxic concentrations, these compounds reduced, in a concentration-dependent manner nitric oxide (NO), prostaglandin E₂ (PGE₂) and tumor necrosis factor (TNF-α) production, as well as expression of inducible nitric oxide synthase (NOS-2) and cyclooxygenase-2 (COX-2).All diterpenoids displayed significant in vivo anti-inflammatory activity and suppressed the 12-O-tetradecanoylphorbol-13-acetate (TPA)-mouse ear edema. In addition, inhibition of myeloperoxidase (MPO) activity, an index of cellular infiltration, was observed.In summary, our results suggest that the inhibition of the expression of NOS-2, COX-2 and the release of inflammatory cytokines, is responsible for the anti-inflammatory effects of the diterpenoids isolated from H. annuus L. which likely contributes to the pharmacological action of sunflower.     

Compartments and organising boundaries in the Drosophila eye: the role of the homeodomain Iroquois proteins.

The Drosophila eye is patterned by a dorsal-ventral organising centre mechanistically similar to those in the fly wing and the vertebrate limb bud. Here we show how this organising centre in the eye is initiated - the first event in retinal patterning. Early in development the eye primordium is divided into dorsal and ventral compartments. The dorsally expressed homeodomain Iroquois genes are true selector genes for the dorsal compartment; their expression is regulated by Hedgehog and Wingless. The organising centre is then induced at the interface between the Iroquois-expressing and non-expressing cells at the eye midline. It was previously thought that the eye develops by a mechanism distinct from that operating in other imaginal discs, but our work establishes the importance of lineage compartments in the eye and thus supports their global role as fundamental units of patterning.     

Use of RT-Defective HIV Virions: New Tool to Evaluate Specific Response in Chronic Asymptomatic HIV-Infected Individuals

Background

Generation of new reagents that can be used to screen or monitor HIV-1-specific responses constituted an interesting field in the development of HIV vaccines to improve their efficacy.

Methods

We have evaluated the specific T cell response against different types of NL4-3 virions (including NL4-3 aldrithiol-2 treated, NL4-3/ΔRT and R5 envelopes: NL4-3/ΔRT/ΔEnv[AC10] and NL4-3/ΔRT/ΔEnv[Bal]) and against pools of overlapping peptides (15 mer) encompassing the HIV-1 Gag and Nef regions. Cryopreserved PBMC from a subset of 69 chronic asymptomatic HIV positive individuals have been employed using different techniques including IFN-γ ELISPOT assay, surface activation markers and intracellular cytokine staining (ICS) by flow cytometry.

Results

The differential response obtained against NL4-3 aldrithiol-2 treated and NL4-3/ΔRT virions (25% vs 55%, respectively) allow us to divide the population in three groups: “full-responders” (positive response against both viral particles), “partial-responders” (positive response only against NL4-3/ΔRT virions) and “non-responders” (negative responses). There was no difference between X4 and R5 envelopes. The magnitude of the total responses was higher against NL4-3/ΔRT and was positively correlated with gender and inverse correlated with viral load. On the contrary CD4+ T cell count was not associated with this response. In any case responses to the viruses tended to be lower in magnitude than those detected by the overlapping peptides tested. Finally we have found an increased frequency of HLA-B27 allele (23% vs 9%) and a significant reduction in some activation markers (CD69 and CD38) on T cells surface in responders vs non-responders individuals.

Conclusions

In summary these virions could be considered as alternative and useful reagents for screening HIV-1-specific T cell responses in HIV exposed uninfected people, HIV infected patients and to assess immunogenicity of new prototypes both in vitro and in vaccine trials, by a feasible, simply, effective and low cost assay.     

Crystal structure of CbpF,a bifunctional choline‐binding protein and autolysis regulator from Streptococcus pneumoniae

Phosphorylcholine, a crucial component of the pneumococcal cell wall, is essential in bacterial physiology and in human pathogenesis because it binds to serum components of the immune system and acts as a docking station for the family of surface choline‐binding proteins. The three‐dimensional structure of choline‐binding protein F (CbpF), one of the most abundant proteins in the pneumococcal cell wall, has been solved in complex with choline. CbpF shows a new modular structure composed both of consensus and non‐consensus choline‐binding repeats, distributed along its length, which markedly alter its shape, charge distribution and binding ability, and organizing the protein into two well‐defined modules. The carboxy‐terminal module is involved in cell wall binding and the amino‐terminal module is crucial for inhibition of the autolytic LytC muramidase, providing a regulatory function for pneumococcal autolysis.     

Seasonal variability of lipophilic toxins during a Dinophysis acuta bloom in Western Iberia: Differences between picked cells and plankton concentrates

This work describes and compares the seasonal variability of toxin profiles and content, estimated by LC–MS analyses, in picked cell of Dinophysis acuta Ehrenberg, in plankton concentrates rich in this species, and in extracellular lipophilic toxins collected by adsorbent resins during weekly sampling in a Galician ría (Western Iberia) from October 2005 to January 2006. Picked cells of D. acuta—which exhibited a fairly stable OA:DTX2 ratio, close to 3:2, but a variable okadaates:PTX2 ratio—showed a 9-fold variation in cell toxin quota, which was partly related to cellular volume, with maximum values (19 pg cell⁻¹) observed during the exponential decline of the population. Large differences in toxin profiles and content were observed between picked cells and plankton concentrates (up to 73 pg cell⁻¹ in the latter), that were most conspicuous after the bloom decline. The toxin profile of picked cells was more similar to that observed in the adsorbent resins than to the profiles of plankton concentrates. Their continued detection several weeks after the disappearance of Dinophysis spp. indicates that these toxins may take a long time to be degraded. It is concluded that analyses of picked-cells are essential to determine the contribution of each species of Dinophysis to a toxic outbreak. Estimates of cellular toxin content from plankton concentrates can lead to considerable overestimates after Dinophysis blooms decay due to extracellular toxins that persist in the water column, possibly bound to organic aggregates and detritus, and are retained (>0.22 μm) in the filters.     

Cloning,Expression, and Characterization of a Peculiar Choline-Binding β-Galactosidase from Streptococcus mitis

A Streptococcus mitis genomic DNA fragment carrying the SMT1224 gene encoding a putative β-galactosidase was identified, cloned, and expressed in Escherichia coli. This gene encodes a protein 2,411 amino acids long with a predicted molecular mass of 268 kDa. The deduced protein contains an N-terminal signal peptide and a C-terminal choline-binding domain consisting of five consensus repeats, which facilitates the anchoring of the secreted enzyme to the cell wall. The choline-binding capacity of the protein facilitates its purification using DEAE-cellulose affinity chromatography, although its complete purification was achieved by constructing a His-tagged fusion protein. The recombinant protein was characterized as a monomeric β-galactosidase showing a specific activity of around 2,500 U/mg of protein, with optimum temperature and pH ranges of 30 to 40°C and 6.0 to 6.5, respectively. Enzyme activity is not inhibited by glucose, even at 200 mM, and remains highly stable in solution or immobilized at room temperature in the absence of protein stabilizers. In S. mitis, the enzyme was located attached to the cell surface, but a significant activity was also detected in the culture medium. This novel enzyme represents the first β-galactosidase having a modular structure with a choline-binding domain, a peculiar property that can also be useful for some biotechnological applications.Streptococcus mitis belongs to the viridans group of streptococci and is a relevant microorganism because it is both an opportunistic pathogen and phylogenetically close to Streptococcus pneumoniae, a major respiratory human pathogen. Although S. mitis isolates usually produce only mild infections, some S. mitis strains have acquired increased virulence and are one of the main causes of infectious endocarditis (15, 36). Remarkably, S. mitis, like only a few other streptococci, displays phosphorylcholine residues in its cellular envelope (3). This aminoalcohol is used for the anchorage of proteins belonging to the so-called “choline-binding proteins” (CBPs), which fulfill important physiological functions in these bacteria. CBPs bind to phosphorylcholine residues present in the teichoic and lipoteichoic acids located at the surface of S. pneumoniae and some streptococci of the mitis group. CBPs share a modular organization consisting of a biologically active domain and a conserved choline-binding domain (CBD), which contains 6 to 18 imperfect 20-amino-acid tandem repeats each located either at the carboxy- or amino-terminal ends of the proteins (26). This CBD is able to specifically bind to choline or its structural analogues like DEAE (diethylaminoethanol), which permits purification by affinity chromatography in a single step using DEAE-cellulose supports (38). Crystallographic studies of CBPs have shown that a typical CBD consists of several β-hairpins organized as a left-handed superhelix and that the linkage of CBPs to the choline-containing cell wall substrate is carried out through the binding of choline residues to the interface of two consecutive choline-binding repeats, named choline-binding sites (9, 13, 14).β-d-Galactosidases (β-d-galactoside galactohydrolase; EC 3.2.1.23) constitute a large family of proteins that cleave the glycosidic bond between two or more carbohydrates or between a carbohydrate and a noncarbohydrate moiety, e.g., lactose and related chromogens, like o-nitrophenyl-β-d-galactopyranoside (ONPG), p-nitrophenyl-β-d-galactopyranoside (PNPG), or 6-bromo-2-naphthyl-galactopyranoside. β-d-galactosidases belong to the glycosyl hydrolase (GH) superfamily, which contains 114 families (see http://www.CAZY.org) classified on the basis of amino acid sequence similarity (12). The enzymes exhibiting β-galactosidase activity are currently classified within four different families: GH-1, GH-2, GH-35, and GH-42. β-Galactosidases are widely distributed in nature and are present in numerous microorganisms (yeasts, fungi, bacteria, and archaea), plants, and animals (34, 44). These enzymes are of great interest for several industrial or biotechnological processes; the hydrolytic activity has been applied in the food industry for decades to reduce the lactose content of milk products in order to circumvent lactose intolerance, which is prevalent in more than half of the world''s population (27). More recently, interest in β-galactosidases has increased due to their ability to synthesize β-galactosyl derivatives that have received a great deal of attention owing to their important roles in many biological processes (27).In this study, we report the purification and biochemical characterization of a peculiar β-galactosidase encoded by the SMT1224 gene of S. mitis that represents a new type of β-galactosidase within this paradigmatic enzyme family.     

TSAO Derivatives: Highly Specific Inhibitors of Human Immunodeficiency Virus Type-1 (HIV-1) Replication

Abstract

TSAO derivatives represent a unique class of nucleosides that are specifically targeted at HIV-1 RT. This overview is focussed on the chemical synthesis, the conformational studies, the antiviral and metabolic properties of TSAO derivatives, as well as their mechanism of antiviral action and the molecular basis of the rapid selection of resistant HIV-1 strains that emerge in cell culture in the presence of TSAO derivatives.