Syntheses of 3-O-(2-acetamido-2-deoxy-β-d-glucopyranosyl)-α-d-galactopyranose (“lacto-N-biose II”) and 3,4-di-O-(2-acetamido-2-deoxy-β-d-glucopyranosyl)-d-galactopyranose

3- O-(2-Acetamido-2-deoxy-β-d-glucopyranosyl)-α-d-galactopyranose (10, “Lacto-N-biose II”) was synthesized by treatment of benzyl 6-O-allyl-2,4-di-O-benzyl-β-d-galactopyranoside with 2-methyl-(3,4,6-tri-O-acetyl-1,2-dideoxy-α-d-glucopyrano)[2,1-d]-2-oxazoline (5), followed by selective O-deallylation, O-deacetylation, and catalytic hydrogenolysis. Condensation of 5 with benzyl 6-O-allyl-2-O-benzyl-α-d-galactopyranoside, followed by removal of the protecting groups, gave 10 and a new, branched trisaccharide, 3,4-di-O-(2-acetamido-2-deoxy-β-d-glucopyranosyl)-d-galactopyranose (27).     

Two Chikungunya isolates from the outbreak of La Reunion (Indian Ocean) exhibit different patterns of infection in the mosquito, Aedes albopictus

Background

A Chikungunya (CHIK) outbreak hit La Réunion Island in 2005–2006. The implicated vector was Aedes albopictus. Here, we present the first study on the susceptibility of Ae. albopictus populations to sympatric CHIKV isolates from La Réunion Island and compare it to other virus/vector combinations.

Methodology and Findings

We orally infected 8 Ae. albopictus collections from La Réunion and 3 from Mayotte collected in March 2006 with two Chikungunya virus (CHIKV) from La Réunion: (i) strain 05.115 collected in June 2005 with an Alanine at the position 226 of the glycoprotein E1 and (ii) strain 06.21 collected in November 2005 with a substitution A226V. Two other CHIKV isolates and four additional mosquito strains/species were also tested. The viral titer of the infectious blood-meal was 10⁷ plaque forming units (pfu)/mL. Dissemination rates were assessed by immunofluorescent staining on head squashes of surviving females 14 days after infection. Rates were at least two times higher with CHIKV 06.21 compared to CHIKV 05.115. In addition, 10 individuals were analyzed every day by quantitative RT-PCR. Viral RNA was quantified on (i) whole females and (ii) midguts and salivary glands of infected females. When comparing profiles, CHIKV 06.21 produced nearly 2 log more viral RNA copies than CHIKV 05.115. Furthermore, females infected with CHIKV 05.115 could be divided in two categories: weakly susceptible or strongly susceptible, comparable to those infected by CHIKV 06.21. Histological analysis detected the presence of CHIKV in salivary glands two days after infection. In addition, Ae. albopictus from La Réunion was as efficient vector as Ae. aegypti and Ae. albopictus from Vietnam when infected with the CHIKV 06.21.

Conclusions

Our findings support the hypothesis that the CHIK outbreak in La Réunion Island was due to a highly competent vector Ae. albopictus which allowed an efficient replication and dissemination of CHIKV 06.21.     

A RasGAP SH3 peptide aptamer inhibits RasGAP-Aurora interaction and induces caspase-independent tumor cell death

The Ras GTPase-activating protein RasGAP catalyzes the conversion of active GTP-bound Ras into inactive GDP-bound Ras. However, RasGAP also acts as a positive effector of Ras and exerts an anti-apoptotic activity that is independent of its GAP function and that involves its SH3 (Src homology) domain. We used a combinatorial peptide aptamer approach to select a collection of RasGAP SH3 specific ligands. We mapped the peptide aptamer binding sites by performing yeast two-hybrid mating assays against a panel of RasGAP SH3 mutants. We examined the biological activity of a peptide aptamer targeting a pocket delineated by residues D295/7, L313 and W317. This aptamer shows a caspase-independent cytotoxic activity on tumor cell lines. It disrupts the interaction between RasGAP and Aurora B kinase. This work identifies the above-mentioned pocket as an interesting therapeutic target to pursue and points its cognate peptide aptamer as a promising guide to discover RasGAP small-molecule drug candidates.     

Transepithelial potential in the Magadi tilapia, a fish living in extreme alkalinity

We investigated the transepithelial potential (TEP) and its responses to changes in the external medium in Alcolapia grahami, a small cichlid fish living in Lake Magadi, Kenya. Magadi water is extremely alkaline (pH = 9.92) and otherwise unusual: titratable alkalinity (290 mequiv L(-1), i.e. HCO(3) (-) and CO(3) (2-)) rather than Cl(-) (112 mmol L(-1)) represents the major anion matching Na(+) = 356 mmol L(-1), with very low concentrations of Ca(2+) and Mg(2+) (<1 mmol L(-1)). Immediately after fish capture, TEP was +4 mV (inside positive), but stabilized at +7 mV at 10-30 h post-capture when experiments were performed in Magadi water. Transfer to 250% Magadi water increased the TEP to +9.5 mV, and transfer to fresh water and deionized water decreased the TEP to -13 and -28 mV, respectively, effects which were not due to changes in pH or osmolality. The very negative TEP in deionized water was attenuated in a linear fashion by log elevations in [Ca(2+)]. Extreme cold (1 vs. 28°C) reduced the positive TEP in Magadi water by 60%, suggesting blockade of an electrogenic component, but did not alter the negative TEP in dilute solution. When fish were transferred to 350 mmol L(-1) solutions of NaHCO(3), NaCl, NaNO(3), or choline Cl, only the 350 mmol L(-1) NaHCO(3) solution sustained the TEP unchanged at +7 mV; in all others, the TEP fell. Furthermore, after transfer to 50, 10, and 2% dilutions of 350 mmol L(-1) NaHCO(3), the TEPs remained identical to those in comparable dilutions of Magadi water, whereas this did not occur with comparable dilutions of 350 mmol L(-1) NaCl-i.e. the fish behaves electrically as if living in an NaHCO(3) solution equimolar to Magadi water. We conclude that the TEP is largely a Na(+) diffusion potential attenuated by some permeability to anions. In Magadi water, the net electrochemical forces driving Na(+) inwards (+9.9 mV) and Cl(-) outwards (+3.4 mV) are small relative to the strong gradient driving HCO(3) (-) inwards (-82.7 mV). Estimated permeability ratios are P (Cl)/P (Na) = 0.51-0.68 and [Formula: see text] = 0.10-0.33. The low permeability to HCO(3) (-) is unusual, and reflects a unique adaptation to life in extreme alkalinity. Cl(-) is distributed close to Nernst equilibrium in Magadi water, so there is no need for lower P (Cl). The higher P (Na) likely facilitates Na(+) efflux through the paracellular pathway. The positive electrogenic component is probably due to active HCO(3) (-) excretion.     

Chemical evaluation of compounds as nitric oxide or peroxynitrite donors using the reactions with serotonin

The aim of this work was to assess the capacities of some ^·NO-donors to release ^·NO, and consequently NOx in aerobic medium, or to give peroxynitrite. The method was based on the differential reactivity of serotonin (5-HT) with either NO_x or peroxynitrite, leading in phosphate-buffered solutions to 4-nitroso- and 4-nitro-5-HT formation, respectively. Yields and formation rates of 5-HT derivatives with ^·NO-donor were compared to those obtained with authentic ^·NO or peroxynitrite in similar conditions. Aside from the capacity of diazenium diolates (SPER/NO and DEA/NO) to release ^·NO spontaneously, converting 5-HT exclusively to 4-nitroso-5-HT, all other ^·NO donors must undergo redox reactions to produce ^·NO. S-nitrosoglutathione (GSNO) and sodium nitroprus-side (SNP) modified 5-HT only in the presence of Cu²⁺, GSNO yielding 6 times more 4-nitroso-5-HT than SNP. Furthermore, in the presence of Cu⁺, the yield of ^·NO-release from GSNO was 45%. The molsidomine metabolite (SIN-1), which was presumed to release both ^·NO and O2/·- at pH 7.4, reacted with 5-HT differently, depending on the presence of reductant or oxidant. Under aerobic conditions, SIN-1 acted predominantly as a 5-HT oxidant and also as a poor ^·NO and peroxynitrite donor (15% yield of ^·NO-release and 14 % yield of peroxynitrite formation). The strong oxidant Cu²⁺, even in the presence of air oxygen, accelerated oxidation and increased ^·NO release from SIN-1 up to 86%. Only a small part of SIN-1 gave simultaneously ^·NO and O2/·- able to link together to give peroxynitrite, but other oxidants could enhance ^·NO release from SIN-1.     

Haemolytic activity,cytotoxicity and membrane cell permeabilization of semi-synthetic and natural lupane- and oleanane-type saponins

The haemolysis of red blood cells inducing toxicity in most animals including humans is a major drawback for the clinical development of saponins as antitumour agents. In this study, the haemolytic and cytotoxic activities as well as the membrane cell permeabilization property of a library of 31 semi-synthetic and natural lupane- and oleanane-type saponins were evaluated and the structure–activity relationships were established. It was shown that lupane-type saponins do not exhibit any haemolytic activity and membrane cell permeabilization property at the maximum concentration tested (100 μM) independently of the nature of the sugar moieties. While oleanane-type saponins such as β-hederin (25) and hederacolchiside A₁ (27) cause the death of cancer cell lines by permeabilizing the cellular membranes, lupane-type saponins seem to proceed via another mechanism, which could be related to the induction of apoptosis. Altogether, the results indicate that the cytotoxic lupane-type glycosides 10 and 22 bearing an α-l-rhamnopyranose moiety at the C-3 position represent promising antitumour agents for further studies on tumour-bearing mice since they are devoid of toxicity associated with the haemolysis of red blood cells.     

Stromal Transcriptional Profiles Reveal Hierarchies of Anatomical Site,Serum Response and Disease and Identify Disease Specific Pathways

Synovial fibroblasts in persistent inflammatory arthritis have been suggested to have parallels with cancer growth and wound healing, both of which involve a stereotypical serum response programme. We tested the hypothesis that a serum response programme can be used to classify diseased tissues, and investigated the serum response programme in fibroblasts from multiple anatomical sites and two diseases. To test our hypothesis we utilized a bioinformatics approach to explore a publicly available microarray dataset including rheumatoid arthritis (RA), osteoarthritis (OA) and normal synovial tissue, then extended those findings in a new microarray dataset representing matched synovial, bone marrow and skin fibroblasts cultured from RA and OA patients undergoing arthroplasty. The classical fibroblast serum response programme discretely classified RA, OA and normal synovial tissues. Analysis of low and high serum treated fibroblast microarray data revealed a hierarchy of control, with anatomical site the most powerful classifier followed by response to serum and then disease. In contrast to skin and bone marrow fibroblasts, exposure of synovial fibroblasts to serum led to convergence of RA and OA expression profiles. Pathway analysis revealed three inter-linked gene networks characterising OA synovial fibroblasts: Cell remodelling through insulin-like growth factors, differentiation and angiogenesis through _3 integrin, and regulation of apoptosis through CD44. We have demonstrated that Fibroblast serum response signatures define disease at the tissue level, and that an OA specific, serum dependent repression of genes involved in cell adhesion, extracellular matrix remodelling and apoptosis is a critical discriminator between cultured OA and RA synovial fibroblasts.     

A Comparison of Some Organizational Characteristics of the Mouse Central Retina and the Human Macula

Mouse models have greatly assisted our understanding of retinal degenerations. However, the mouse retina does not have a macula, leading to the question of whether the mouse is a relevant model for macular degeneration. In the present study, a quantitative comparison between the organization of the central mouse retina and the human macula was made, focusing on some structural characteristics that have been suggested to be important in predisposing the macula to stresses leading to degeneration: photoreceptor density, phagocytic load on the RPE, and the relative thinness of Bruch’s membrane. Light and electron microscopy measurements from retinas of two strains of mice, together with published data on human retinas, were used for calculations and subsequent comparisons. As in the human retina, the central region of the mouse retina possesses a higher photoreceptor cell density and a thinner Bruch’s membrane than in the periphery; however, the magnitudes of these periphery to center gradients are larger in the human. Of potentially greater relevance is the actual photoreceptor cell density, which is much greater in the mouse central retina than in the human macula, underlying a higher phagocytic load for the mouse RPE. Moreover, at eccentricities that correspond to the peripheral half of the human macula, the rod to cone ratio is similar between mouse and human. Hence, with respect to photoreceptor density and phagocytic load of the RPE, the central mouse retina models at least the more peripheral part of the macula, where macular degeneration is often first evident.     

Bioactivities of black cumin essential oil and its main terpenes from Tunisia

Ex vivo antioxidant, anti-inflammatory, anticancer and antibacterial activities of the essential oil from Tunisian Nigella sativa seeds and its main terpenes (p-cymene, γ-terpinene, thymoquinone, β-pinene, carvacrol, terpinen-4-ol and longifolene) were determined. The essential oil exhibited strong ex vivo antioxidant activity, inhibiting DCFH oxidation with an IC₅₀ of 1.0 µg/ml, and high anti-inflammatory activity, inhibiting NO radical excretion with an IC₅₀ value of 6.3 µg/ml. Thymoquinone was found to be the most active to decrease DCFH oxidation and NO excretion. The oil was found to significantly inhibit the growth of A-549 and DLD-1 cancer cell lines (IC₅₀ values of 43.0 and 46.0 µg/ml, respectively) and to exert antibacterial activity against Staphylococcus aureus and Escherichia coli with IC₅₀ values of 12.0 and 62.0 µg/ml. The anticancer and antibacterial activities could be mainly due to the action of thymoquinone and longifolene.     

Darwin on woman

In his 1871 book The Descent of Man, Darwin exposed the idea of sexual selection as a major principle of human evolution. His main hypothesis, which was already briefly presented in The Origin of Species, is that there exists, besides “natural selection”, another form of selection, milder in its effect, but no less efficient. This selection is operated by females to mate and reproduce with some partners that are gifted with more qualities than others, and more to their taste. At more evolved stages, sexual selection was exerted by men who became able to choose the women most attractive to their taste. However, Darwin insists, sexual selection in the human species is limited by a certain number of cultural practices. If Darwin's demonstration sometimes carried the prejudices of his times regarding gender differences he was the first who took into account the importance of sexual choices in his view on evolution, and who insisted on the evolutionary role of women at the dawn of humanity. Thus, he opened the space for a rich reflection, which after him was widely developed and discussed in anthropological and gender studies.