The synthesis of a series of six‐membered 2‐acetamido l‐iminosugar C‐alkyl and C‐aryl glycosides is reported. A diastereoselective sugar‐ring enlargement/C‐alkylation (or arylation) /ring‐contraction ...sequence applied to d‐gluco‐ and d‐manno‐configured 2‐acetamido azidolactols provides new l‐iminosugar C‐glycosides. The 1,2‐trans stereocontrolled introduction of the pseudoanomeric substituent in these heterocycles strongly suggests a NHAc neighbouring‐group participation. In their deprotected form, the nine iminosugars exhibit moderate hexosaminidases and β‐glucuronidase inhibition.
A Staudinger/azawittig/Grignard/ring‐contraction sequence applied to two d‐glycopyranose derivatives bearing an acetamido group at the C‐2 position and an azido group at the C‐6 position allows access to unprecedented six‐membered l‐iminosugars C‐glycosides as GlcNAc and ManNAc mimics. The high 1,2‐trans diastereoselectivity observed for the Grignard addition strongly suggests an anchimeric assistance by the NHAc group.
Field description and sampling along four representative pits were done to determine the occurrence and the perspective earthenware valorisation from clay materials in the northern Cameroon. The ...methodology used include grain size analysis, Atterberg limits determination, mineralogical and geochemical analyses, and technological tests. Sand fraction was important in all samples. Interval plastic is tight to wide and the main clay minerals were kaolinite, illite and smectite. They were associated to quartz and feldspar minerals. Geochemically, SiO
2
(48.46–65.62%), Al
2
O
3
(14.8–20.28%), Fe
2
O
3
(4.79–11.47%) and 5 to 13% of flux elements (CaO, MgO, K
2
O and Na
2
O) were found as main oxides. The presence of smectite is attributed to the low landscape positions, the presence of a clay-rich alluvial parent material and the hydrological conditions in this region, which is characterised by low rainfall and high temperature inducing high evaporation and thus soil solutions concentrated in silica and basic cations. Kaolinite is formed by the decomposition of orthoclase feldspar. The simultaneous occurrence of smectite and kaolinite, as a result of bisiallitisation and monosiallitisation processes respectively, could be related to light and successive variations in drainage conditions. Firing specimens showed red colour, which is attributed to the presence of hematite in the mineral composition. The presence of kaolinite promotes mullite formation while that of illite and smectite may promote glassy phase formation, which leads to the densification (1.7 to 2.09 g/cm
3
) and the good cohesion of the fired products with temperature development and the evolution of the metallic sound. Following some standards, the water absorption values (10.47 to 20.12%) and the compressive strength (2 to 5.7 MPa) suggest that the studied clay materials are suitable for earthenware production.
The Cover Feature shows the synthesis of unprecedented 2‐acetamido C‐alkyl and C‐aryl iminosugars. This synthesis was achieved through a Staudinger/aza‐Wittig/ Grignard/ring contraction sequence. An ...audacious parallel is made between Louis Blériot's achievement, being the first to fly an aircraft across the English Channel in 1909 and this work, the first “trip” to 2‐acetamido C‐alkyl and C‐aryl iminosugars, achieved by his relative and collaborators. The cover art was created by S. Riffaut. More information can be found in the Full Paper by Y. Blériot, A. Kato, J. Désiré et al.
Mechanisms regulating thrombus stabilization remain largely unknown. Here, we report that loss of any 1 of the Gas6 receptors (Gas6-Rs), i.e., Tyro3, Axl, or Mer, or delivery of a soluble ...extracellular domain of Axl that traps Gas6 protects mice against life-threatening thrombosis. Loss of a Gas6-R does not prevent initial platelet aggregation but impairs subsequent stabilization of platelet aggregates, at least in part by reducing "outside-in" signaling and platelet granule secretion. Gas6, through its receptors, activates PI3K and Akt and stimulates tyrosine phosphorylation of the beta3 integrin, thereby amplifying outside-in signaling via alphaIIbbeta3. Blocking the Gas6-R-alphaIIbbeta3 integrin cross-talk might be a novel approach to the reduction of thrombosis.
The Cu‐glutathione (GSH) redox system, essential in biology, is designed here as a supramacromolecular assembly in which the tetrahedral 18e Cu(I) center loses a thiol ligand upon adsorption onto ...ZIF‐8, as shown by EXAFS and DFT calculation, to generate a very robust 16e planar trigonal single‐atom Cu(I) catalyst. Synergy between Cu(I) and ZIF‐8, revealed by catalytic experiments and DFT, affords CO2 conversion into high‐value‐added chemicals with a wide scope of substrates by reaction with terminal alkynes or propargyl amines in excellent yields under mild conditions and reuse at least 10 times without significant decrease in catalytic efficiency.
Capitalizing on a recently reported iminosugar-based aza-crown (ISAC) accessed by a double Staudinger azaWittig coupling reaction, we have expanded the structural diversity of this new family of ...sweet cyclam analogs. Replacement of the two secondary amines linking the iminosugar units by two amide bonds obtained a cyclodimerization by with BOP and DIPEA led to a macrocycle that did not demonstrate efficient Zn2+ chelation unlike the parent ISAC. Introduction of two pyrene moieties on the secondary amines of the parent ISAC yielded a new fluoroionophore that selectively binds Hg2+ in methanol.
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•First synthesis of fluoroionophore based on an iminosugar scaffold.•The fluoroionophore shows selectivity for Hg++ cations.•First synthesis of iminosugar azacrown (ISAC) with amide pending arms.•Introduction of amide arms abolishes the chelation properties observed for ISAC with amine arms.
owns a variability of virulence factors. These factors can increase bacterial pathogenicity and infection severity. Despite the importance of knowledge about them, these factors are not more ...characterized at level of strains derived from local food products. This study aimed to characterize the virulence potential of
isolated from various animal products. Several structural and virulence genes of
including
, and
were detected by polymerase chain reaction (PCR) on 204 strains of
They were isolated from bovine meat (122), fresh fish (49), and smoked fish (33). The 16S rRNA gene was detected on 91.1% of the presumptive strains as
The
gene showed that 99.5% of the strains were
. The
gene (89.2%) was the most frequently detected (
< 0.05). In decreasing importance order,
(86.8%),
(72.1%),
(72.1%),
(40.2%), and
(2.5%) were detected. The
gene was detected in all strains of
serogroups O11 and O16. The prevalence of
, and
genes in these strains varied from 51.2% to 87.4%. The simultaneous determination of serogroups and virulence factors is of interest for the efficacy of surveillance of infections associated with
.
Mechanisms regulating thrombus stabilization remain largely unknown. Here, we report that loss of any 1 of the Gas6 receptors (Gas6-Rs), i.e., Tyro3, Axl, or Mer, or delivery of a soluble ...extracellular domain of Axl that traps Gas6 protects mice against life-threatening thrombosis. Loss of a Gas6-R does not prevent initial platelet aggregation but impairs subsequent stabilization of platelet aggregates, at least in part by reducing “outside-in” signaling and platelet granule secretion. Gas6, through its receptors, activates PI3K and Akt and stimulates tyrosine phosphorylation of the β
3
integrin, thereby amplifying outside-in signaling via α
IIb
β
3
. Blocking the Gas6-R–α
IIb
β
3
integrin cross-talk might be a novel approach to the reduction of thrombosis.
Background & Aims: Survivin is an inhibitor of apoptosis protein (IAP), which also is crucial for mitosis and cell cycle progression. IAPs participate in regulating Fas ligand-induced hepatic ...apoptosis. The aim was to study the contribution of survivin to hepatic apoptosis by generating transgenic mice lacking survivin. Methods: The survivin gene was inactivated in mice by homologous recombination in embryonic stem cells. Survivin+/− and survivin+/+ mice were generated and injected with the Fas agonistic antibody Jo2. Results: In 3 genetic backgrounds, survivin−/− embryos died before 4.5 days post coitum. Survivin+/− mice appeared normal, but liver lysates revealed aseline low-level activation of procaspase-8, Bid, procaspase-9, and procaspase-3, with accumulation of Bax, and release of cytochrome c, indicating a proapoptotic state. Intraperitoneal injection of low-dose Jo2 had no effect on survivin+/+ mice at 2 hours. However, in survivin+/− mice, Jo2 caused hemorrhagic necrosis of the liver, associated with prominent activation of the apoptotic pathway via the mitochondria, and up-regulation of hepatocellular expression of survivin in the cytosol, nuclei, and mitochondria. Isolated mitochondria from survivin+/− livers had more defects in oxidative phosphorylation after C2-ceramide exposure. Conclusions: Absence of survivin is incompatible with life. Although Jo2 induces expression of survivin, diminished baseline levels render the liver more sensitive to Fas, possibly due to functional effects on the mitochondria. This is the first in vivo documentation that survivin modulates caspase activation and that Fas-mediated hepatic apoptosis is regulated by survivin via mitochondrial pathways.
GASTROENTEROLOGY 2002;123:619-631
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