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| 2. |
- Ruda, K., et al.
(författare)
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Synthesis of the Leishmania LPG core heptasaccharyl myo-inositol
- 2000
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Ingår i: Journal of the American Chemical Society. - : American Chemical Society (ACS). - 0002-7863 .- 1520-5126. ; 122:45, s. 11067-11072
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Tidskriftsartikel (refereegranskat)abstract
- Total synthesis of the core heptasaccharyl myo-inositol, Galp(a1-6)Galp(a1-3)Galf(ß1-3)[Glcp(a1-PO4-6)Manp](a1-3)Manp(a1-4)GlcN p(a1-6)Ins-1-PO4, and the corresponding hexasaccharyl myo-inositol, Galp(a1-6)Galp(a1-3)Galf(ß1-3)Manp(a1-3)Manp(a1-4)GlcNp(a1-6)Ins-1-PO4 , found in the lipophosphoglycans of Leishmania parasites are described. The target molecules contain synthetic challenges such as an unusual internal galactofuranosyl residue and an anomeric phosphodiester. The synthesis was accomplished using a convergent block synthetic strategy. Four building blocks, a trigalactoside, a dimannoside, a glucosyl inositolphosphate, and a glucosyl-a-1-H-phosphonate, all appropriately protected, were used. The trigalactoside was linked to the dimannoside followed by glycosylation with the glucosyl inositolphosphate to produce the fully protected hexasaccharyl myo-inositol. Subsequent oxidative coupling of the glucosyl-H-phosphonate formed the anomeric phosphodiester linkage to produce the protected heptasaccharyl myo-inositol. Both the assembly order of the subunits and sequence of deprotection were essential for the successful synthesis of these complex molecules. The deprotection was accomplished by deacetylation and clevage of benzyl ethers with sodium in liquid ammonia, followed by acidic deacetalization/desilylation to produce the target molecules.
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| 3. |
- Garegg, P.J., et al.
(författare)
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Transglucosidation of methyl and ethyl D-glucopyranosides by alcoholysis
- 2002
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Ingår i: Carbohydrate Research. - 0008-6215 .- 1873-426X. ; 337:6, s. 517-521
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Tidskriftsartikel (refereegranskat)abstract
- The transglucosidations of methyl 4-O-methyl-a- and -ß-D-glucopyranoside in ethanolic camphor-10-sulfonic acid, and of ethyl 4-O-methyl-a- and -ß-D-glucopyranoside in methanolic camphor-10-sulfonic acid, have been studied. Samples were removed at intervals and the proportions of the glucosides determined by GC of their acetates. The results show that the anomer with the inverted configuration predominates in the initially formed product (˜59-70%). This indicates that all the studied reactions proceed via the same mechanism, involving exocyclic C-O cleavage and formation of a glucopyranosylium ion, but that the eliminated alcohol exerts some steric hindrance, which favors the approach of the other alcohol from the opposite side. © 2002 Published by Elsevier Science Ltd.
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| 4. |
- Johannsen, A., et al.
(författare)
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Effects of stabilized stannous fluoride dentifrice on dental calculus, dental plaque, gingivitis, halitosis and stain: A systematic review
- 2019
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Ingår i: Heliyon. - : Elsevier BV. - 2405-8440. ; 5:12
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Tidskriftsartikel (refereegranskat)abstract
- Objectives: The aim of the present systematic review was to examine the scientific evidence for the efficacy of stabilized stannous fluoride (SnF2) dentifrice in relation to dental calculus, dental plaque, gingivitis, halitosis and staining. Data and sources: Medline OVID, Embase.com, and the Cochrane Library were searched from database inception until June 2017. Six researchers independently selected studies, extracted data, and assessed methodological quality. A meta-analysis of the 6-month gingivitis studies was done. Risk of bias was estimated using a checklist from the Swedish Agency for Health Technology Assessment (SBU, 2018). Study selection: Two studies on dental calculus, 21 on dental plaque and gingivitis, 4 on halitosis, and 5 on stain met the inclusion criteria. Risk of bias was high for the studies on dental calculus, halitosis, and stain, and varied for the dental plaque and gingivitis studies. Significant reductions in dental calculus and in halitosis were reported for the SnF2 dentifrice; no differences in stain reduction were noted. A meta-analysis on gingivitis found better results for the SnF2 dentifrice compared to other dentifrices, though the results of the individual trials in the metaanalysesshowed a substantial heterogeneity. Conclusions: The present review found that stabilized SnF2 toothpaste had a positive effect on the reduction of dental calculus build-up, dental plaque, gingivitis, stain and halitosis. A tendency towards a more pronounced effect than using toothpastes not containing SnF2 was found. However, a new generation of well conducted randomized trials are needed to further support these findings. Clinical relevance: Adding a SnF2 toothpaste to the daily oral care routine is an easy strategy that may have multiple oral health benefits.
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| 5. |
- Kardeby, Caroline, 1989-, et al.
(författare)
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Synthetic glycopolymers and natural fucoidans cause human platelet aggregation via PEAR1 and GPIbα
- 2019
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Ingår i: Blood Advances. - : American Society of Hematology. - 2473-9529 .- 2473-9537. ; 3:3, s. 275-287
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Tidskriftsartikel (refereegranskat)abstract
- Fucoidans are sulfated fucose-based polysaccharides that activate platelets and have pro- and anticoagulant effects; thus, they may have therapeutic value. In the present study, we show that 2 synthetic sulfated α-l-fucoside-pendant glycopolymers (with average monomeric units of 13 and 329) and natural fucoidans activate human platelets through a Src- and phosphatidylinositol 3-kinase (PI3K)-dependent and Syk-independent signaling cascade downstream of the platelet endothelial aggregation receptor 1 (PEAR1). Synthetic glycopolymers and natural fucoidan stimulate marked phosphorylation of PEAR1 and Akt, but not Syk. Platelet aggregation and Akt phosphorylation induced by natural fucoidan and synthetic glycopolymers are blocked by a monoclonal antibody to PEAR1. Direct binding of sulfated glycopolymers to epidermal like growth factor (EGF)-like repeat 13 of PEAR1 was shown by avidity-based extracellular protein interaction screen technology. In contrast, synthetic glycopolymers and natural fucoidans activate mouse platelets through a Src- and Syk-dependent pathway regulated by C-type lectin-like receptor 2 (CLEC-2) with only a minor role for PEAR1. Mouse platelets lacking the extracellular domain of GPIbα and human platelets treated with GPIbα-blocking antibodies display a reduced aggregation response to synthetic glycopolymers. We found that synthetic sulfated glycopolymers bind directly to GPIbα, substantiating that GPIbα facilitates the interaction of synthetic glycopolymers with CLEC-2 or PEAR1. Our results establish PEAR1 as the major signaling receptor for natural fucose-based polysaccharides and synthetic glycopolymers in human, but not in mouse, platelets. Sulfated α-l-fucoside-pendant glycopolymers are unique tools for further investigation of the physiological role of PEAR1 in platelets and beyond.
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| 8. |
- Konradsson-Geuken, A, et al.
(författare)
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Cortical kynurenic acid bi-directionally modulates prefrontal glutamate levels as assessed by microdialysis and rapid electrochemistry.
- 2010
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Ingår i: Neuroscience. - : Elsevier BV. - 0306-4522 .- 1873-7544. ; 169:4
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Tidskriftsartikel (refereegranskat)abstract
- Using two in vivo methods, microdialysis and rapid in situ electrochemistry, this study examined the modulation of extracellular glutamate levels by endogenously produced kynurenic acid (KYNA) in the prefrontal cortex (PFC) of awake rats. Measured by microdialysis, i.p. administration of KYNA's bioprecursor L-kynurenine dose-dependently elevated extracellular KYNA and reduced extracellular glutamate (nadir after 50 mg/kg kynurenine: 60% decrease from baseline values). This dose-dependent decrease in glutamate levels was also seen using a glutamate-sensitive microelectrode array (MEA) (31% decrease following 50 mg/kg kynurenine). The kynurenine-induced reduction in glutamate was blocked (microdialysis) or attenuated (MEA) by co-administration of galantamine (3 mg/kg i.p.), a drug that competes with KYNA at an allosteric potentiating site of the alpha 7 nicotinic acetylcholine receptor. In separate experiments, extracellular glutamate levels were measured by MEA following the local perfusion (45 min) of the PFC with kynurenine (2.5 microM) or the selective KYNA biosynthesis inhibitor S-ethylsulfonylbenzoylalanine (S-ESBA; 5 mM). In agreement with previous microdialysis studies, local kynurenine application produced a reversible reduction in glutamate (nadir: -29%), whereas perfusion with S-ESBA increased glutamate levels reversibly (maximum: +38%). Collectively, these results demonstrate that fluctuations in the biosynthesis of KYNA in the PFC bi-directionally modulate extracellular glutamate levels, and that qualitatively very similar data are obtained by microdialysis and MEA. Since KYNA levels are elevated in the PFC of individuals with schizophrenia, and since prefrontal glutamatergic and nicotinic transmission mediate cognitive flexibility, normalization of KYNA levels in the PFC may constitute an effective treatment strategy for alleviating cognitive deficits in schizophrenia.
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| 9. |
- Konradsson-Geuken, Asa, et al.
(författare)
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Second-by-second analysis of alpha 7 nicotine receptor regulation of glutamate release in the prefrontal cortex of awake rats.
- 2009
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Ingår i: Synapse. - : Wiley. - 0887-4476 .- 1098-2396. ; 63:12
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Tidskriftsartikel (refereegranskat)abstract
- These experiments utilized an enzyme-based microelectrode selective for the second-by-second detection of extracellular glutamate to reveal the alpha 7-based nicotinic modulation of glutamate release in the prefrontal cortex (PFC) of freely moving rats. Rats received intracortical infusions of the nonselective nicotinic agonist nicotine (12.0 mM, 1.0 microg/0.4 microl) or the selective alpha 7 agonist choline (2.0 mM/0.4 microl). The selectivity of drug-induced glutamate release was assessed in subgroups of animals pretreated with the alpha 7 antagonist, alpha-bungarotoxin (alpha-BGT, 10 microM), or kynurenine (10 microM) the precursor of the astrocyte-derived, negative allosteric alpha 7 modulator kynurenic acid. Local administration of nicotine increased glutamate signals (maximum amplitude = 4.3 +/- 0.6 microM) that were cleared to baseline levels in 493 +/- 80 seconds. Pretreatment with alpha-BGT or kynurenine attenuated nicotine-induced glutamate by 61% and 60%, respectively. Local administration of choline also increased glutamate signals (maximum amplitude = 6.3 +/- 0.9 microM). In contrast to nicotine-evoked glutamate release, choline-evoked signals were cleared more quickly (28 +/- 6 seconds) and pretreatment with alpha-BGT or kynurenine completely blocked the stimulated glutamate release. Using a method that reveals the temporal dynamics of in vivo glutamate release and clearance, these data indicate a nicotinic modulation of cortical glutamate release that is both alpha 7- and non-alpha 7-mediated. Furthermore, these data may also provide a mechanism underlying the recent focus on alpha 7 full and partial agonists as therapeutic agents in the treatment of cortically mediated cognitive deficits in schizophrenia.
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| 10. |
- Lindberg, Jan, et al.
(författare)
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Efficient routes to glucosamine-myo-inositol derivatives, key building blocks in the synthesis of glycosylphosphatidylinositol anchor substances
- 2002
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Ingår i: Tetrahedron. - 0040-4020 .- 1464-5416. ; 58:7, s. 1387-1398
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Tidskriftsartikel (refereegranskat)abstract
- Short synthetic routes to protected derivatives of 2-amino-2-deoxy-a-D-glucopyranosyl-(1?6)-D-myo-inositol are described. Various 2-azido-2-deoxy-glucosyl donors were synthesized, starting from D-glucal or glucosamine hydrochloride. Derivatives of 1,2- and 2,3- D-myo-inositol-camphanylidene acetals were prepared to function as glycosyl acceptors. The subsequent glycosylations produced useful building blocks for the synthesis of GPI-anchor substances. © 2002 Elsevier Science Ltd. All rights reserved.
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