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Application of the Anomeric Samarium Route for the Convergent Synthesis of the <i>C</i>-Linked Trisaccharide α-d-Man-(1→3)-[α-d-Man-(1→6)]-d-Man and the Disaccharides α-d-Man-(1→3)-d-Man and α-d-Man-(1→6)-d-Man
No full textStudies are reported on the assembly of the branched C-trisaccharide, α-d-Man-(1→3)-[α-d-Man-(1→6)]-d-Man, representing the core region of the asparagine-linked oligosaccharides. The key step
in this synthesis uses a SmI2-mediated coupling of two mannosylpyridyl sulfones to a C3,C6-diformyl
branched monosaccharide unit, thereby assembling all three sugar units in one reaction and with
complete stereocontrol at the two anomeric carbon centers. Subsequent tin hydride-based deoxygenation followed by a deprotection step produces the target C-trimer. In contrast to many of the
other C-glycosylation methods, this approach employes intact carbohydrate units as C-glycosyl
donors and acceptors, which in many instances parallels the well-studied O-glycosylation reactions.
The synthesis of the C-disaccharides α-d-Man-(1→3)-d-Man and α-d-Man-(1→6)-d-Man is also
described, they being necessary for the following conformational studies of all three carbohydrate
analogues both in solution and bound to several mannose-binding proteins
Application of the Anomeric Samarium Route for the Convergent Synthesis of the <i>C</i>-Linked Trisaccharide α-d-Man-(1→3)-[α-d-Man-(1→6)]-d-Man and the Disaccharides α-d-Man-(1→3)-d-Man and α-d-Man-(1→6)-d-Man
No full textStudies are reported on the assembly of the branched C-trisaccharide, α-d-Man-(1→3)-[α-d-Man-(1→6)]-d-Man, representing the core region of the asparagine-linked oligosaccharides. The key step
in this synthesis uses a SmI2-mediated coupling of two mannosylpyridyl sulfones to a C3,C6-diformyl
branched monosaccharide unit, thereby assembling all three sugar units in one reaction and with
complete stereocontrol at the two anomeric carbon centers. Subsequent tin hydride-based deoxygenation followed by a deprotection step produces the target C-trimer. In contrast to many of the
other C-glycosylation methods, this approach employes intact carbohydrate units as C-glycosyl
donors and acceptors, which in many instances parallels the well-studied O-glycosylation reactions.
The synthesis of the C-disaccharides α-d-Man-(1→3)-d-Man and α-d-Man-(1→6)-d-Man is also
described, they being necessary for the following conformational studies of all three carbohydrate
analogues both in solution and bound to several mannose-binding proteins
Conformation of Glycomimetics in the Free and Protein-Bound State: Structural and Binding Features of the <i>C</i>-glycosyl Analogue of the Core Trisaccharide α-d-Man-(1 → 3)-[α-d-Man-(1 → 6)]-d-Man
No full textThe conformational properties of the C-glycosyl analogue of the core trisaccharide α-d-Man-(1
→ 3)-[α-d-Man-(1 → 6)]-d-Man in solution have been carefully analyzed by a combination of NMR
spectroscopy and time-averaged restrained molecular dynamics. It has been found that both the α-1,3-
and the α-1,6-glycosidic linkages show a major conformational averaging. Unusual Φ ca. 60° orientations
for both Φ torsion angles are found. Moreover, a major conformational distinction between the natural
compound and the glycomimetic affects to the behavior of the ω16 torsion angle around the α-1 → 6-linkage.
Despite this increased flexibility, the C-glycosyl analogue is recognized by three mannose binding lectins,
as shown by NMR (line broadening, TR−NOE, and STD) and surface plasmon resonance (SPR) methods.
Moreover, a process of conformational selection takes place, so that these lectins probably bind the
glycomimetic similarly to the way they recognize the natural analogue. Depending upon the architecture
and extension of the binding site of the lectin, loss or gain of binding affinity with respect to the natural
analogue is found
Direct Synthesis of β-Mannans. A Hexameric [→3)-β-d-Man-(1→4)-β-d-Man-(1]<sub>3</sub> Subunit of the Antigenic Polysaccharides from <i>Leptospira </i><i>b</i><i>iflexa</i> and the Octameric (1→2)-Linked β-d-Mannan of the <i>Candida a</i><i>lbicans</i> Phospholipomannan. X-ray Crystal Structure of a Protected Tetramer
No full textDirect Synthesis of β-Mannans. A Hexameric
[→3)-β-d-Man-(1→4)-β-d-Man-(1]3 Subunit of the
Antigenic Polysaccharides from Leptospira biflexa
and the Octameric (1→2)-Linked β-d-Mannan of the
Candida albicans Phospholipomannan. X-ray Crystal
Structure of a Protected Tetrame
Direct Synthesis of β-Mannans. A Hexameric [→3)-β-d-Man-(1→4)-β-d-Man-(1]<sub>3</sub> Subunit of the Antigenic Polysaccharides from <i>Leptospira </i><i>b</i><i>iflexa</i> and the Octameric (1→2)-Linked β-d-Mannan of the <i>Candida a</i><i>lbicans</i> Phospholipomannan. X-ray Crystal Structure of a Protected Tetramer
No full textDirect Synthesis of β-Mannans. A Hexameric
[→3)-β-d-Man-(1→4)-β-d-Man-(1]3 Subunit of the
Antigenic Polysaccharides from Leptospira biflexa
and the Octameric (1→2)-Linked β-d-Mannan of the
Candida albicans Phospholipomannan. X-ray Crystal
Structure of a Protected Tetrame
Synthesis of the <i>C</i>-Linked Disaccharide α-d-Man-(1→4)-d-Man Employing a SmI<sub>2</sub>-Mediated <i>C</i>-Glycosylation Step: En Route to Cyclic <i>C</i>-Oligosaccharides
No full textInvestigations are reported on the assembly of the C-linked disaccharide α-d-Man-(1→4)-d-Man,
representing the first steps in our projected synthesis of a cyclic C-oligomer containing repeating
units of this C-dimer. The key step in this synthesis uses a SmI2-mediated coupling of 2,3,4,6-tetra-O-benzyl-α-d-mannopyranosyl 2‘-pyridyl sulfone with a C4-formyl branched mannopyranoside
unit, affording the C-disaccharide derivative with complete stereocontrol at the two new stereogenic
centers. Subsequently, a modified tin hydride based deoxygenation produced the target carbohydrate
analogue. The synthesis of the C4-formyl monosaccharide makes use of a stereoselective radical-based allylation followed by double bond migration and ozonolysis
Competing models of socially constructed economic man : differentiating Defoe's Crusoe from the Robinson of neoclassical economics
No full textDaniel Defoe’s Robinson Crusoe has seldom been read as an explicitly political text. When it has, it appears that the central character was designed to warn the early eighteenth-century reader against political challenges to the existing economic order. Insofar as Defoe’s Crusoe stands for "economic man", he is a reflection of historically-produced assumptions about the need for social conformity, not the embodiment of any genuinely essential economic characteristics. This insight is used to compare Defoe’s conception of economic man with that of the neoclassical Robinson Crusoe economy. On the most important of the ostensibly generic principles espoused by neoclassical theorists, their "Robinson" has no parallels with Defoe’s Crusoe. Despite the shared name, two quite distinct social constructions serve two equally distinct pedagogical purposes. Defoe’s Crusoe extols the virtues of passive middle-class sobriety for effective social organisation; the neoclassical Robinson champions the establishment of markets for the sake of productive efficiency
PATHOLOGICAL CHANGES IN SIX TREATED BABOON‐TO‐MAN RENAL HETEROTRANSPLANTS
No full textSix baboon‐to‐man renal heterotransplants, each consisting of a pair of kidneys, were examined. Two had been removed from their recipients at forty‐nine and sixty days after transplantation because of the ever‐increasing doses of immunosuppressive drugs needed to control rejection; the other four pairs of kidneys were examined after death of the recipients at nineteen, twenty‐three, thirty‐five, and forty‐nine days. All the kidneys were enlarged. On the subcapsular surfaces of one pair there were petechias; four were mottled with irregular haemorrhages and infarcts; one pair had undergone almost complete hemorrhagic infarction. The transplants were heavily infiltrated with plasma cells, lymphocytes, large pyroninophilic lymphoid cells and eosinophils. Mitoses, “LE” cells and erythrophagocytosis were seen. Associated with this infiltration there was rupture of peritubular capillaries, interstitial cedema and widespread tubular damage. Fibrinoid necrosis of the walls of arterioles and interlobular arteries, with narrowing and obstruction of some vessels by fibrin and platelet deposits on the intima were common in all except one pair of kidneys. Associated with these vascular lesions there were focal infarcts and extensive interstitial haemorrhages. All the histological changes were more severe than those seen either in treated human renal homotransplants or in a comparable series of chimpanzee‐to‐man renal heterotransplants where cellular infiltration was slight and vascular lesions only present at the height of rejection. This work was aided by grants A‐6283, A‐6344, HE‐07735, AM‐07772, A1‐01452, and OG‐27 from the U.S. Public Health Service, and by a grant from the Medical Research Council. We would like to thank Drs D. Baitlon, J. Gordon, R. B. Hill, D. Lang, and D. E. Smith who performed the autopsies on these cases. We are particularly grateful to Dr D. T. Rowlands, who supervised most of the autopsies, for his helpful co‐operation throughout this study. Expert assistance in preparing the sections and photomicrographs was given by Miss Jane Rendall. © 1965 BJU International Compan
MeSH term explosion and author rank improve expert recommendations
No full textInformation overload is an often-cited phenomenon that reduces the productivity, efficiency and efficacy of scientists. One challenge for scientists is to find appropriate collaborators in their research. The literature describes various solutions to the problem of expertise location, but most current approaches do not appear to be very suitable for expert recommendations in biomedical research. In this study, we present the development and initial evaluation of a vector space model-based algorithm to calculate researcher similarity using four inputs: 1) MeSH terms of publications; 2) MeSH terms and author rank; 3) exploded MeSH terms; and 4) exploded MeSH terms and author rank. We developed and evaluated the algorithm using a data set of 17,525 authors and their 22,542 papers. On average, our algorithms correctly predicted 2.5 of the top 5/10 coauthors of individual scientists. Exploded MeSH and author rank outperformed all other algorithms in accuracy, followed closely by MeSH and author rank. Our results show that the accuracy of MeSH term-based matching can be enhanced with other metadata such as author rank
Norman D. Nevills and unidentified man.
No full textPhoto shows Norman D. Nevills and unidentified man at a desert campsit
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