Search results for "Arid"

Los pasados políticos de Grass / Ridruejo

2006

The Allyl Ester as Carboxy-Protecting Group in the Stereoselective Construction of Neuraminic-Acid Glycosides

1988

The application of the allyl-ester moiety as protecting principle for the carboxy group of N-acetylneuraminic acid is described. Peracetylated allyl neuraminate 2 is synthesized by reacting the caesium salt of the acid 1 with allyl bromide. Treatment of 2 with HCl in AcCl or with HF/pyridine gives the corresponding 2-chloro or 2-fluoro derivatives 3 and 4, respectively (Scheme 1). In the presence of Ag2CO3, the 2-chloro carbohydrate 3 reacts with di-O-isopropylidene-protected galactose 5 to give the 2–6 linked disaccharide with the α-D-anomer 6a predominating (α-D/β-D = 6:1; Scheme 2). Upon activation of the 2-fluoro derivative 4 with BF3 · Et2O, the β-D-anomer 6b is formed preferentially (…

Variations in Jurassic echinoid biodiversity at ammonite zone levels: Stratigraphical and palaeoecological significance

2020

After a relatively low but stable phase of taxonomic diversity during the Lias (Lower Jurassic), echinoids diversity strongly increases from Aalenian (Dogger-Middle Jurassic) to Kimmeridgian (Malm-Late Jurassic) and a conspicuous crisis takes place in Tithonian times, before the end of the Jurassic. During these major phases, minor decreases in diversity correspond with regressions (sea-level falls), mainly in the Middle Bathonian (Middle Jurassic). From the Aalenian to Callovian, the average duration of irregular echinoid species is about 3.8 m.y. whereas it is about 5.5 m.y. for the regular ones; the later value corresponding to the average duration of a Jurassic. From Callovian to Tithon…

Sediment quality assessment using Gmelinoides fasciatus and Monoporeia affinis (Amphipoda, Gammaridea) in the northeastern Baltic Sea

2013

Crustaceans in the order Amphipoda are sensitive organisms for the assessment of sediment quality. In this work we performed 10-day toxicity tests on muddy sediments collected from a total of 29 sites in the Gulf of Finland, the Gulf of Riga and the Gulf of Bothnia (northeastern Baltic Sea) using Baltic Sea species such as the native amphipod Monoporeia affinis (Bousfield, 1989) and the invasive amphipod Gmelinoides fasciatus (Stebbing, 1899), and also compared these results with those of bioassays carried out using the standard test species, laboratory-cultivated amphipod Hyalella azteca (Saussure, 1858). The sediment samples (three cm of the upper layer) were collected by a GEMAX Dual Cor…

Borate-driven gatelike scaffolding using mesoporous materials functionalised with saccharides.

2009

We report the development of an MCM-41 mesoporous support that is functionalised with saccharides at the pore outlets and contains the dye [Ru(bipy)(3)](2+) in the pores (solid S1; bipy = 2,2'-bipyridyl). For this hybrid system, the inhibition of mass transport of the dye from the pore voids to the bulk solution in the presence of borate is demonstrated in water at neutral pH. The formation of the corresponding boroester derivative is related to the selective reaction of borate with the appended saccharides. This control is selective and only anion borate, among several anions and cations, can act as a molecular tap and inhibit the delivery of the entrapped guest. Additionally, the S1-borat…

Attachment of chloride anion to sugars: mechanistic investigation and discovery of a new dopant for efficient sugar ionization/detection in mass spec…

2012

International audience; A new method for efficient ionization of sugars in the negative-ion mode of electrospray mass spectrometry is presented. Instead of using strongly hydrophobic dopants such as dichloromethane or chloroform, efficient ionization of sugars has been achieved by using aqueous HCl solution for the first time. This methodology makes it possible to use hydrophilic dopants, which are more appropriate for chromatographic separation techniques with efficient sugar ionization and detection in mass spectrometry. The interaction between chloride anions and monosaccharides (glucose and galactose) was studied by DFT in the gas phase and by implementing the polarizable continuum mode…

Anthemis wiedemanniana essential oil prevents LPS-induced production of NO in RAW 264.7 macrophages and exerts antiproliferative and antibacterial ac…

2012

Anthemis wiedemanniana is known in folk medicine for the treatment of microbial infections, cancer and also urinary and pulmonary problems. In this study, the chemical composition of the essential oil from A. wiedemanniana was evaluated and its antibacterial activity was tested against 10 bacterial strains. The oil was also tested for its potentiality to inhibit nitric oxide production in RAW 264.7 macrophages and for its cytotoxicity against four human cancer cell lines. A. wiedemanniana oil, rich of oxygenated monoterpenes (25.4%), showed a good antibacterial activity against Gram-positive bacteria and a good activity against the two Gram-negative bacteria, Escherichia coli and Proteus vu…

Chemical Constituents and Pharmacological Properties ofPoria cocos

2011

Poria cocos (Polyporaceae) is a saprophytic fungus that grows in diverse species of Pinus. Its sclerotium, called fu-ling or hoelen, is used in traditional Chinese and Japanese medicine for its diuretic, sedative, and tonic effects. Various studies of this fungus have demonstrated its marked anti-inflammatory activity in different experimental models of acute and chronic inflammation. It is widely used as a constituent of many preparations in Asian medicine, but the number of research papers on its clinical properties is insufficient for establishing its efficacy and safety from a scientific point of view. In this review, we have compiled all the published data concerning the chemistry, pha…

Formation of a new cell wall by protoplasts of Candida albicans: effect of papulacandin B, tunicamycin and Nikkomycin.

1987

SUMMARY: Incorporation of polysaccharides into the walls of regenerating protoplasts of Candida albicans was followed in the presence of papulacandin B, tunicamycin and nikkomycin. With the first drug, chitin was incorporated normally whereas incorporation of glucans and mannoproteins was significantly decreased. Tunicamycin decreased incorporation of all wall polymers when added at the beginning of the regeneration process but blocked only mannan and alkali-insoluble glucan incorporation when added after 5 h. Nikkomycin inhibited chitin synthesis, and the walls formed by the protoplasts were enriched in alkali-soluble glucan. Pulse-chase experiments suggested that a precursor-product relat…

Microarray analysis of antibodies induced with synthetic antitumor vaccines : specificity against diverse mucin core structures

2017

Glycoprotein research is pivotal for vaccine development and biomarker discovery. Many successful methodologies for reliably increasing the antigenicity toward tumor-associated glycopeptide structures have been reported. Deeper insights into the quality and specificity of the raised polyclonal, humoral reactions are often not addressed, despite the fact that an immunological memory, which produces antibodies with cross-reactivity to epitopes exposed on healthy cells, may cause autoimmune diseases. In the current work, three MUC1 antitumor vaccine candidates conjugated with different immune stimulants are evaluated immunologically. For assessment of the influence of the immune stimulant on a…